Table of contents

World-wide collaboration in high-energy physics (HEP) is a tradition which dates back several decades, with scientific publications mostly coauthored by scientists from different countries. This coauthorship phenomenon makes it difficult to identify precisely the ``share'' of each country in HEP scientific production. One year's worth of HEP scientific articles published in peer-reviewed journals is analysed and their authors are uniquely assigned to countries. This method allows the first correct estimation on a pro rata basis of the share of HEP scientific publishing among several countries and institutions. The results provide an interesting insight into the geographical collaborative patterns of the HEP community. The HEP publishing landscape is further analysed to provide information on the journals favoured by the HEP community and on the geographical variation of their author bases. These results provide quantitative input to the ongoing debate on the possible transition of HEP publishing to an Open Access model.

Foreword. This paper reports the results of a recent detailed study of the publishing landscape in high energy physics. We thought that because of its direct relevance to the high energy physics community, this important quantitative input to the debate on the transition to Open Access naturally finds its place in our journal.

Marc Henneaux, JHEP Scientific Director

One-loop string scattering amplitudes computed using the standard D0-brane conformal field theory (CFT) suffer from infrared divergences associated with recoil. A systematic framework to take recoil into account is the worldline formalism, where fixed boundary conditions are replaced by dynamical D0-brane worldlines. We show that, in the worldline formalism, the divergences that plague the CFT are automatically cancelled in a non-trivial way. The amplitudes derived in the worldline formalism can be reproduced by deforming the CFT with a specific ``recoil operator'', which is bilocal and different from the ones previously suggested in the literature.

We present a consistent effective theory that violates the null energy condition (NEC) without developing any instabilities or other pathological features. The model is the ghost condensate with the global shift symmetry softly broken by a potential. We show that this system can drive a cosmological expansion with > 0. Demanding the absence of instabilities in this model requires ≲ H². We then construct a general low-energy effective theory that describes scalar fluctuations about an arbitrary FRW background, and argue that the qualitative features found in our model are very general for stable systems that violate the NEC. Violating the NEC allows dramatically non-standard cosmological histories. To illustrate this, we construct an explicit model in which the expansion of our universe originates from an asymptotically flat state in the past, smoothing out the big-bang singularity within control of a low-energy effective theory. This gives an interesting alternative to standard inflation for solving the horizon problem. We also construct models in which the present acceleration has w<−1; a periodic ever-expanding universe; and a model with a smooth ``bounce'' connecting a contracting and expanding phase.

We investigate the stability of the extra dimensions in a warped, codimension two braneworld that is based upon an Einstein-Maxwell-dilaton theory. The braneworld solution has two 3-branes, which are located at the positions of the conical singularities. For this type of brane solution the relative positions of the branes (the shape modulus) are determined via the tension-deficit relations, if the brane tensions are fixed. However, the volume of the extra dimensions (the volume modulus) is not fixed in the context of the classical theory. Hence, we discuss the one-loop effective potential of the volume modulus for a massless, minimally coupled scalar field. Given the scale invariance of the background solution, the form of the modulus effective potential can only be determined from the sign of the logarithmic term in the effective potential. This term can be evaluated via heat kernel analysis and we show that in most cases the volume modulus is stabilized. In the actual evaluation, due to a lack of knowledge of the UV contributions from the conical branes in a six-dimensional spacetime, we consider its four-dimensional counterpart. We then go on to discuss the mass scale of the modulus itself and find that it becomes comparable to the gravitational scale for mild degrees of warping. Then, we make some suggestions on the original six-dimensional model. Finally, we close this article, after discussing some phenomenological implications relating to the hierarchy problem of the fundamental energy scales and the smallness of the effective vacuum energy on the brane. We find that one-loop corrections in this model appear to alleviate some of these problems.

This paper has been removed because of plagiarism. We regret that the paper was published.

We explore 1/16-BPS objects of type IIB string theory in AdS₅ × S⁵. First, we consider supersymmetric AdS₅ black holes, which should be 1/16-BPS and have a characteristic that not all physical charges are independent. We point out that the Bekenstein-Hawking entropy of these black holes admits a remarkably simple expression in terms of (dependent) physical charges, which suggests its microscopic origin via certain Cardy or Hardy-Ramanujan formula. We also note that there is an upper bound for the angular momenta given by the electric charges. Second, we construct a class of 1/16-BPS giant graviton solutions in AdS₅ × S⁵ and explore their properties. The solutions are given by the intersections of AdS₅ × S⁵ and complex 3 dimensional holomorphic hyperspaces in ¹⁺⁵, the latter being the zero loci of three holomorphic functions which are homogeneous with suitable weights on coordinates. We investigate examples of giant gravitons, including their degenerations to tensionless strings.

We study a subsector of the AdS₄/CFT₃ correspondence where a class of solutions in the bulk and on the boundary can be explicitly compared. The bulk gravitational theory contains a conformally coupled scalar field with a ϕ⁴ potential, and is holographically related to a massless scalar with a ϕ⁶ interaction in three dimensions. We consider the scalar sector of the bulk theory and match bulk and boundary classical solutions of the equations of motion. Of particular interest is the matching of the bulk and the boundary instanton solutions which underlies the relationship between bulk and boundary vacua with broken conformal invariance. Using a form of radial quantization we show that quantum states in the bulk correspond to multiply-occupied single particle quantum states in the boundary theory. This allows us to explicitly identify the boundary composite operator which is dual to the bulk scalar, at the free theory level as well as in the instanton vacuum. We conclude with a discussion of possible implications of our results.

We consider a holographic dual of hydrodynamics of = 4 SYM plasma that undergoes non-isotropic three-dimensional expansion relevant to RHIC fireball. Our model is a natural extension of the Bjorken's one-dimensional expansion, and it describes an elliptic flow whose v₂ and eccentricity are given in terms of anisotropy parameters. Holographic renormalization shows that absence of conformal anomaly in the SYM theory constrains our local rest frame to be a Kasner spacetime. We show that the Kasner spcetime provides a simple description of the anisotropically expanding fluid within a well-controled approximation. We also find that the dual geometry determines some of the hydrodynamic quantities in terms of the initial condition and the fundamental constants.

We examine the dynamics of neutral black rings, and identify and analyze a selection of possible instabilities. We find the dominating forces of very thin black rings to be a Newtonian competition between a string-like tension and a centrifugal force. We study in detail the radial balance of forces in black rings, and find evidence that all fat black rings are unstable to radial perturbations, while thin black rings are radially stable. Most thin black rings, if not all of them, also likely suffer from Gregory-Laflamme instabilities. We also study simple models for stability against emission/absorption of massless particles. Our results point to the conclusion that most neutral black rings suffer from classical dynamical instabilities, but there may still exist a small range of parameters where thin black rings are stable. We also discuss the absence of regular real Euclidean sections of black rings, and thermodynamics in the grand-canonical ensemble.

We compute the instanton partition function for = 4 U(N) gauge theories living on toric varieties, mainly of type ⁴/Γ_p,q including A_p−1 or O₁(−p) surfaces. The results provide microscopic formulas for the partition functions of black holes made out of D4-D2-D0 bound states wrapping four-dimensional toric varieties inside a Calabi-Yau. The partition function gets contributions from regular and fractional instantons. Regular instantons are described in terms of symmetric products of the four-dimensional variety. Fractional instantons are built out of elementary self-dual connections with no moduli carrying non-trivial fluxes along the exceptional cycles of the variety. The fractional instanton contribution agrees with recent results based on 2d SYM analysis. The partition function, in the large charge limit, reproduces the supergravity macroscopic formulae for the D4-D2-D0 black hole entropy.

We study the perturbative expansion of = 8 supergravity in four dimensions from the viewpoint of the ``no-triangle'' hypothesis, which states that one-loop graviton amplitudes in = 8 supergravity only contain scalar box integral functions. Our computations constitute a direct proof at six-points and support the no-triangle conjecture for seven-point amplitudes and beyond.

We formulate here a new world-sheet renormalization-group technique for the bosonic string, which is non-perturbative in the Regge slope α^' and based on a functional method for controlling the quantum fluctuations, whose magnitudes are scaled by the value of α^'. Using this technique we exhibit, in addition to the well-known linear-dilaton cosmology, a new, non-perturbative time-dependent background solution. Using the freedom to perform field redefinitions in string effective actions that leave the string S-matrix invariant, we demonstrate that this solution is conformally invariant to (α^'), and we conjecture on the basis of a heuristic inductive argument that conformal invariance can be maintained to all orders in α^'. This new time-dependent string solution may be applicable to primordial cosmology or to the exit from linear-dilaton cosmology at large times.

It is generally known that the holomorphic anomaly equations in topological string theory reflect the quantum mechanical nature of the topological string partition function. We present two new results which make this assertion more precise: (i) we give a new, purely holomorphic version of the holomorphic anomaly equations, clarifying their relation to the heat equation satisfied by the Jacobi theta series; (ii) in cases where the moduli space is a Hermitian symmetric tube domain G/K, we show that the general solution of the anomaly equations is a matrix element ⟨Ψ|g|Ω⟩ of the Schrödinger-Weil representation of a Heisenberg extension of G, between an arbitrary state ⟨Ψ| and a particular vacuum state |Ω⟩. Based on these results, we speculate on the existence of a one-parameter generalization of the usual topological amplitude, which in symmetric cases transforms in the smallest unitary representation of the duality group G' in three dimensions, and on its relations to hypermultiplet couplings, nonabelian Donaldson-Thomas theory and black hole degeneracies.

Using the attractor mechanism and the relation between the quantization of H³(M) and topological strings on a Calabi Yau threefold M we define a map from BPS black holes into coherent states. This map allows us to represent the Bekenstein-Hawking-Wald entropy as a quantum distribution function on the phase spaceH³(M). This distribution function is a mixed Husimi/anti-Husimi distribution corresponding to the different normal ordering prescriptions for the string coupling and deviations of the complex structure moduli. From the integral representation of this distribution function in terms of the Wigner distribution we recover the Ooguri-Strominger-Vafa (OSV) conjecture in the region ``at infinity" of the complex structure moduli space. The physical meaning of the OSV corrections are briefly discussed in this limit.

We compute the drag force experienced by a heavy quark that moves through plasma in a gauge theory whose dual description involves arbitrary metric and dilaton fields. As a concrete application, we consider the cascading gauge theory at temperatures high above the deconfining scale, where we obtain a drag force with a non-trivial velocity dependence. We compare our results with the jet-quenching parameter for the same theory, and find qualitative agreement between the two approaches. Conversely, we calculate the jet-quenching parameter for = 4 super-Yang-Mills with an R-charge density (or equivalently, a chemical potential), and compare our result with the corresponding drag force.

We show that in a class of universal extra dimension (UED) models that solves both the neutrino mass and proton decay problems using low scale left-right symmetry, the dark matter of the Universe consists of an admixture of KK photon and KK right-handed neutrinos. We present a full calculation of the dark matter density in these models taking into account the co-annihilation effects due to near by states such as the scalar partner of the KK photon as well as fermion states near the right-handed KK neutrino. Using the value of the relic CDM density, we obtain upper limits on R⁻¹ of about 400-650 GeV and M_Z' ⩽ 1.5 TeV, both being accessible to LHC. For a region in this parameter space where the KK right-handed neutrino contributes significantly to the total relic density of dark matter, we obtain a lower bound on the dark matter-nucleon scattering cross section of 10⁻⁴⁴ cm², which can be probed by the next round of dark matter search experiments.

We present an interacting action that lives in loop space, and we argue that this is a generalization of the theory for a free tensor multiplet. From this action we derive the Bogomolnyi equation corresponding to solitonic strings. Using the Hopf map, we find a correspondence between BPS strings and BPS monopoles in four-dimensional super Yang-Mills theory. This enable us to find explicit BPS saturated solitonic string solutions.

We study the μ<0 branch of the minimal supergravity ansatz of the minimal supersymmetric standard model. The extent to which μ<0 is disfavoured compared to μ>0 in global fits is calculated with Markov Chain Monte Carlo methods and bridge sampling. The fits include state-of-the-art two-loop MSSM contributions to the electroweak observables M_W and sin ²θ_w^l, as well as the anomalous magnetic moment of the muon (g−2)_μ, the relic density of dark matter and other relevant indirect observables. μ<0 is only marginally disfavoured in global fits and should be considered in mSUGRA analyses. We estimate that the ratio of probabilities is P(μ<0)/P(μ>0) = 0.07−0.16.

We study giant graviton probes in the framework of the three–parameter deformation of the AdS₅ × S⁵ background. We examine both the case when the brane expands in the deformed ⁵ part of the geometry and the case when it blows up into AdS₅. Performing a detailed analysis of small fluctuations around the giants, the configurations turn out to be stable. Our results hold even for the supersymmetric Lunin-Maldacena deformation.

In this paper we construct a detailed map from pure and mixed half-BPS states of the D1-D5 system to half-BPS solutions of type IIB supergravity. Using this map, we can see how gravity arises through coarse graining microstates, and we can explicitly confirm the microscopic description of conical defect metrics, the M = 0 BTZ black hole and of small black rings. We find that the entropy associated to the natural geometric stretched horizon typically exceeds that of the mixed state from which the geometry was obtained.

We study massless deformations of generalized calibrated cycles, which describe, in the language of generalized complex geometry, supersymmetric D-branes in = 1 supersymmetric compactifications with fluxes. We find that the deformations are classified by the first cohomology group of a Lie algebroid canonically associated to the generalized calibrated cycle, seen as a generalized complex submanifold with respect to the integrable generalized complex structure of the bulk. We provide examples in the SU(3) structure case and in a `genuine' generalized complex structure case. We discuss cases of lifting of massless modes due to world-volume fluxes, background fluxes and a generalized complex structure that changes type.

We study N = 2 Liouville theory with arbitrary central charge in the presence of boundaries. After reviewing the theory on the sphere and deriving some important structure constants, we investigate the boundary states of the theory from two approaches, one using the modular transformation property of annulus amplitudes and the other using the bootstrap of disc two-point functions containing degenerate bulk operators. The boundary interactions describing the boundary states are also proposed, based on which the precise correspondence between boundary states and boundary interactions is obtained. The open string spectrum between D-branes is studied from the modular bootstrap approach and also from the reflection relation of boundary operators, providing a consistency check for the proposal.

We study the expectation values of Wilson-loop operators with the insertions of local operators Z^J and ^J for large J from the bulk viewpoint of AdS/CFT correspondence. Classical solutions of strings attached to such deformed Wilson loops at the conformal boundary are constructed and are applied to the computation of Wilson-loop expectation values. We argue that in order to have such solutions for general insertions at finite positions in the base spacetime of the gauge theory, it is crucial to interpret the holographic correspondence in the semi-classical picture as a tunneling phenomenon, as has been previously established for holographic computations of correlators of BMN operators. This also requires to use the Euclideanized AdS background and Euclidean super Yang-Mills theory.

We construct the pp-wave string associated with the Penrose limit of Y^p,q and L^p,q,r families of Sasaki-Einstein geometries. We identify in the dual quiver gauge theories the chiral and the non-chiral operators that correspond to the ground state and the first excited states. We present an explicit identification in a prototype model of L^1,7,3.

We investigate models of SU(N) SQCD with adjoint matter and non trivial mesonic deformations. We apply standard methods in the dual magnetic theory and we find meta-stable supersymmetry breaking vacua with arbitrary large lifetime. We comment on the difference with known models.

We calculate the tension of (p,q)-strings in the warped deformed conifold using the non-Abelian DBI action. In the large flux limit, we find exact agreement with the recent expression obtained by Firouzjahi, Leblond and Henry-Tye up to and including order 1/M² terms if q is also taken to be large. Furthermore using the finite q prescription for the symmetrised trace operation we anticipate the most general expression for the tension valid for any (p,q). We find that even in this instance, corrections to the tension scale as 1/M² which is not consistent with simple Casimir scaling.

The U(N) Maxwell-Chern-Simons matrix gauge theory is proposed as an extension of Susskind's noncommutative approach. The theory describes D0-branes, nonrelativistic particles with matrix coordinates and gauge symmetry, that realize a matrix generalization of the quantum Hall effect. Matrix ground states obtained by suitable projections of higher Landau levels are found to be in one-to-one correspondence with the expected Laughlin and Jain hierarchical states. The Jain composite-fermion construction follows by gauge invariance via the Gauss law constraint. In the limit of commuting, ``normal'' matrices the theory reduces to eigenvalue coordinates that describe realistic electrons with Calogero interaction. The Maxwell-Chern-Simons matrix theory improves earlier noncommutative approaches and could provide another effective theory of the fractional Hall effect.

We analyze the supersymmetry conditions for a class of SU(2) structure backgrounds of Type IIB supergravity, corresponding to a specific ansatz for the supersymmetry parameters. These backgrounds are relevant for the AdS/CFT correspondence since they are suitable to describe mass deformations or beta-deformations of four-dimensional superconformal gauge theories. Using Generalized Complex Geometry we show that these geometries are characterized by a closed nowhere-vanishing vector field and a modified fundamental form which is also closed. The vector field encodes the information about the superpotential and the type of deformation - mass or beta respectively. We also show that the Pilch-Warner solution dual to a mass-deformation of = 4 Super Yang-Mills and the Lunin-Maldacena beta-deformation of the same background fall in our class of solutions.

We study electromagnetic test fields in the background of vacuum black rings using Killing vectors as vector potentials. We consider both spacetimes with a rotating S¹ and with a rotatingS² and we demonstrate, in particular, that the gyromagnetic ratio of slightly charged black rings takes the value g = 3 (this will in fact apply to a wider class of spacetimes). We also observe that aS²-rotating black ring immersed in an external ``aligned'' magnetic field completely expels the magnetic flux in the extremal limit. Finally, we discuss the mutual alignment of principal null directions of the Maxwell 2-form and of the Weyl tensor, and the algebraic type of exact charged black rings. In contrast to spherical black holes, charged rings display new distinctive features and provide us with an explicit example of algebraically general (type G) spacetimes in higher dimensions. Appendix A contains some global results on black rings with a rotating 2-sphere. Appendix C shows that g = D−2 in any D ⩾ 4 dimensions for test electromagnetic fields generated by a time translation.

We compute the complete topological expansion of the formal hermitian two-matrix model. For this, we refine the previously formulated diagrammatic rules for computing the 1/N expansion of the nonmixed correlation functions and give a new formulation of the spectral curve. We extend these rules obtaining a closed formula for correlation functions in all orders of topological expansion. We then integrate it to obtain the free energy in terms of residues on the associated Riemann surface.

The smallness of the observed neutrino masses might have a radiative origin. Here we revisit a specific two-loop model of neutrino mass, independently proposed by Babu and Zee. We point out that current constraints from neutrino data can be used to derive strict lower limits on the branching ratio of flavour changing charged lepton decays, such as μ→eγ. Non-observation of Br(μ→eγ) at the level of 10⁻¹³ would rule out singly charged scalar masses smaller than 590 GeV (5.04 TeV) in case of normal (inverse) neutrino mass hierarchy. Conversely, decay branching ratios of the non-standard scalars of the model can be fixed by the measured neutrino angles (and mass scale). Thus, if the scalars of the model are light enough to be produced at the LHC or ILC, measuring their decay properties would serve as a direct test of the model as the origin of neutrino masses.

We study the low-energy dynamics of semi-classical vortex strings living above Argyres-Douglas superconformal field theories. The worldsheet theory of the string is shown to be a deformation of the CP^N model which flows in the infra-red to a superconformal minimal model. The scaling dimensions of chiral primary operators are determined and the dimensions of the associated relevant perturbations on the worldsheet and in the four dimensional bulk are found to agree. The vortex string thereby provides a map between the A-series of N=2 superconformal theories in two and four dimensions.

The enormous red-shifting of the modes during the inflationary epoch suggests that physics at the Planck scale may modify the standard, nearly scale-invariant, primordial, density perturbation spectrum. Under the principle of path-integral duality, the space-time behaves as though it has a minimal length L_P (which we shall assume to be of the order of the Planck length), a feature that is expected to arise when the quantum gravitational effects on the matter fields have been taken into account. Using the method of path integral duality, in this work, we evaluate the Planck scale corrections to the spectrum of density perturbations in the case of exponential inflation. We find that the amplitude of the corrections is of the order of (/M_P), where and M_P denote the inflationary and the Planck energy scales, respectively. We also find that the corrections turn out to be completely independent of scale. We briefly discuss the implications of our result, and also comment on how it compares with an earlier result.

In models with ``large'' and/or warped extra dimensions, the higher–dimensional Planck scale may be as low as a TeV. In that case black holes with masses of a few TeV are expected to be produced copiously in multi–TeV collisions, in particular at the LHC. These black holes decay through Hawking radiation into typically (20) Standard Model particles. Most of these particles would be strongly interacting. Naively this would lead to a final state containing 10 or so hadronic jets. However, it has been argued that the density of strongly interacting particles would be so large that they thermalize, forming a ``chromosphere'' rather than well–defined jets. In order to investigate this, we perform a QCD simulation which includes parton–parton scattering in addition to parton showering. We find the effects of parton scattering to remain small for all cases we studied, leading to the conclusion that the decays of black holes with masses within the reach of the LHC will not lead to the formation of chromospheres.

Non-uniform black strings coupled to a gauge field are constructed by a perturbative method in a wide range of spacetime dimensions. At the linear order of perturbations, we see that the Gregory-Laflamme instability vanishes at the point where the background solution becomes thermodynamically stable. The emergence/vanishing of the static mode resembles phase transitions, and in fact we find that its critical exponent is nearly 1/2, which means a second-order transition. By employing higher-order perturbations, the physical properties of the non-uniform black strings are investigated in detail. For fixed spacetime dimensions, we find the critical charges at which the stability of non-uniform states changes. For some range of charge, non-uniform black strings are entropically favored over uniform ones. The gauge charge works as a control parameter that controls not only the stability of uniform black strings but also the non-uniform states. In addition, we find that for a fixed background charge the uniform state is not necessarily the state carrying the largest tension. The phase diagram and a comparison with the critical dimension are also discussed.

We use geodesic probes to recover the entire bulk metric in certain asymptotically AdS spacetimes. Given a spectrum of null geodesic endpoints on the boundary, we describe two remarkably simple methods for recovering the bulk information. After examining the issues which affect their application in practice, we highlight a significant advantage one has over the other from a computational point of view, and give some illustrative examples. We go on to consider spacetimes where the methods cannot be used to recover the complete bulk metric, and demonstrate how much information can be recovered in these cases.

Pair production of W bosons constitutes an important background to Higgs boson and new physics searches at the Large Hadron Collider LHC. We have calculated the loop-induced gluon-fusion process gg→W*W*→leptons, including intermediate light and heavy quarks and allowing for arbitrary invariant masses of the W bosons. While formally of next-to-next-to-leading order, the gg→W*W*→leptons process is enhanced by the large gluon flux at the LHC and by experimental Higgs search cuts, and increases the next-to-leading order WW background estimate for Higgs searches by about 30%. We have extended our previous calculation to include the contribution from the intermediate top-bottom massive quark loop and the Higgs signal process. We provide updated results for cross sections and differential distributions and study the interference between the different gluon scattering contributions. We describe important analytical and numerical aspects of our calculation and present the public GG2WW event generator.

In addition to superconformal symmetry, (1,1) supersymmetric two-dimensional sigma models on special holonomy manifolds have extra symmetries that are in one-to-one correspondence with the covariantly constant forms on these manifolds. The superconformal algebras extended by these symmetries close as W-algebras, i.e. they have field-dependent structure functions. It is shown that it is not possible to write down cohomological equations for potential quantum anomalies when the structure functions are field-dependent. In order to do this it is necessary to linearise the algebras by treating composite currents as generators of additional symmetries. It is shown that all cases can be linearised in a finite number of steps, except for G₂ and SU(3). Additional problems in the quantisation procedure are briefly discussed.

We revisit the impact of the jet algorithm on predictions of energy flow into gaps between hard jets, defined using the k_t clustering procedure. The resulting prediction has two distinct components: a primary emission piece that is related to independent emission of soft gluons by the hard jets and a correlated emission (non-global) piece known only in the large N_c limit. We analytically compute the dependence of the primary emission term on the jet algorithm, which gives significantly more insight than our previous numerical study of the same. We also point out that the non-global component of the answer is reduced even more significantly by the clustering than suggested previously in the literature. Lastly we provide improved predictions for the latest ZEUS photoproduction data, assessing the impact of our latest findings.

From the Polyakov string action using a conformal gauge we construct a three-spin giant magnon solution describing a long open string in AdS₅ × S⁵ which rotates both in two angular directions of S⁵ and in one angular direction of AdS₅. Through the Virasoro constraints the string motion in AdS₅ takes an effect from the string configuration in S⁵. The dispersion relation of the soliton solution is obtained as a superposition of two bound states of magnons. We show that there is a correspondence between a special giant magnon in AdS₂ and the sinh-Gordon soliton.

We study the phase structures of = 4 U(N) super Yang-Mills theories on × S³/_k with large N. The theory has many vacua labelled by the holonomy matrix along the non-trivial cycle on S³/_k, and for the fermions the periodic and the anti-periodic boundary conditions can be assigned along the cycle. We compute the partition functions of the orbifold theories and observe that phase transitions occur even in the zero 't Hooft coupling limit. With the periodic boundary condition, the vacua of the gauge theory are dual to various arrangements of k NS5-branes. With the anti-periodic boundary condition, transitions between the vacua are dual to localized tachyon condensations. In particular, the mass of a deformed geometry is compared with the Casimir energy for the dual vacuum. We also obtain an index for the supersymmetric orbifold theory.

We investigate the relation between gauge theories and brane configurations described by brane tilings. We identify U(1)_B (baryonic), U(1)_M (mesonic), and U(1)_R global symmetries in gauge theories with gauge symmetries in the brane configurations. We also show that U(1)_MU(1)_B² and U(1)_RU(1)_B² 't Hooft anomalies are reproduced as gauge transformations of the classical brane action.

The giant magnon is a rotating spiky string configuration which has the same dispersion relation between the energy and angular momentum as that of a spin magnon. In this paper we investigate the effects of the NS-NS and Melvin fields on the giant magnon. We first analyze the energy and angular momenta of the two-spin spiky D-string moving on the AdS₃ × S¹ with the NS-NS field. Due to the infinite boundary of the AdS spacetime the D-string solution will extend to infinity and it appears the divergences. After adding the counter terms we obtain the dispersion relation of the corresponding giant magnon. The result shows that there will appear a prefactor before the angular momentum, in addition to some corrections in the sine function. We also see that the spiky profile of a rotating D-string plays an important role in mapping it to a spin magnon. We next investigate the energy and angular momentum of the one-spin spiky fundamental string moving on the R × S² with the electric or magnetic Melvin field. The dispersion relation of the corresponding deformed giant magnon is also obtained. We discuss some properties of the correction terms and their relations to the spin chain with deformations.

BiHermitian geometry, discovered long ago by Gates, Hull and Rocek, is the most general sigma model target space geometry allowing for (2,2) world sheet supersymmetry. By using the twisting procedure proposed by Kapustin and Li, we work out the type A and B topological sigma models for a general biHermtian target space, we write down the explicit expression of the sigma model's action and BRST transformations and present a computation of the topological gauge fermion and the topological action.

We analyze the cosmological implications of F-term hybrid inflation with a subdominant Fayet–Iliopoulos D-term whose presence explicitly breaks a D-parity in the inflaton-waterfall sector. This scenario of inflation, which is called F_D-term hybrid model for brevity, can naturally predict lepton number violation at the electroweak scale, by tying the μ-parameter of the MSSM to an SO(3)-symmetric Majorana mass m_N, via the vacuum expectation value of the inflaton field. We show how a negative Hubble-induced mass term in a next-to-minimal extension of supergravity helps to accommodate the present CMB data and considerably weaken the strict constraints on the theoretical parameters, resulting from cosmic string effects on the power spectrum P. The usual gravitino overabundance constraint may be significantly relaxed in this model, once the enormous entropy release from the late decays of the ultraheavy waterfall gauge particles is properly considered. As the Universe enters a second thermalization phase involving a very low reheat temperature, which might be as low as about 0.3 TeV, thermal electroweak-scale resonant leptogenesis provides a viable mechanism for successful baryogenesis, while thermal right-handed sneutrinos emerge as new possible candidates for solving the cold dark matter problem. In addition, we discuss grand unified theory realizations of F_D-term hybrid inflation devoid of cosmic strings and monopoles, based on the complete breaking of an SU(2)_X subgroup. The F_D-term hybrid model offers rich particle-physics phenomenology, which could be probed at high-energy colliders, as well as in low-energy experiments of lepton flavour or number violation.

We implement soft leptogenesis in a warped five dimensional scenario with two branes on the orbifold boundaries coming from an S¹/Z₂ symmetry, and supersymmetry broken on the IR brane. The SM hypermultiplet fields (fermions and Higgs) live in the UV brane and we allow the vector supermultiplets corresponding to the gauge bosons and a hypermultiplet corresponding to the right handed neutrino to live in the bulk. We assume that there are Majorana mass terms for the right handed neutrino superfield fixed on each brane and that there is a Yukawa term involving the right handed neutrino, the left handed neutrino and the Higgs fixed on the UV brane. Supersymmetry is broken by a constant ``superpotential'' on the IR brane, which induces an F-term for the radion hypermultiplet. This F-term leads to a B-term for the right handed sneutrinos as well as a soft SUSY breaking gaugino mass in the 4D theory for the zero modes. The gaugino mass naturally induces an A-term for the right handed sneutrino, left handed sneutrino and the Higgs to be formed through gaugino mediation with a non-trivial CP violating phase. Moreover, we show that within the context of extra dimensions, the condition of out-of-equilibrium decay and the phenomenological constraints on the neutrino mass are both satisfied in a natural way, for UV Majorana masses of the order of the fundamental scale of the theory. Thus all necessary elements for soft leptogenesis are at hand and we are able to predict a correct value for the baryon asymmetry.

We compute the fully–differential →X_ul decay width to all orders in perturbation theory in the large–β₀ limit. Each of the five structure functions that build the hadronic tensor is expressed as a Borel integral, summing up (C_Fβ₀ⁿ⁻¹α_sⁿ) corrections for any n. We derive analytic expressions for the Borel transforms of both real and virtual diagrams with a single dressed gluon, and perform an all–order infrared subtraction, where the Borel parameter serves also as an infrared regulator. Expanding the result we recover the known triple–differential NLO coefficient, and obtain an explicit expression for the (C_Fβ₀α_s²) triple–differential NNLO correction. This result can be used to improve the determination of |V_ub| from inclusive →X_ul measurements at the B factories with a variety of kinematic cuts.

In the large N_c limit of QCD, baryons can be modeled as solitons, for instance, as Skyrmions. This modeling has been justified by Witten's demonstration that all properties of baryons and mesons scale with N_c^−1/2 in the same way as the analogous meson-based soliton model scales with a generic meson-meson coupling constant g. An alternative large N_c limit (the orientifold large N_c limit) has recently been proposed in which quarks transform in the two-index antisymmetric representation of SU(N_c). By carrying out the analog of Witten's analysis for the new orientifold large N_c limit, we show that baryons and solitons can also be identified in the orientifold large N_c limit. However, in the orientifold large N_c limit, the interaction amplitudes and matrix elements scale with N_c⁻¹ in the same way as soliton models scale with the generic meson coupling constant g rather than as N_c^−1/2 as in the traditional large N_c limit.

We study a vectorial gauge theory with gauge group SU(N_c) and a variable number, N_f, of massless fermions in the fundamental representation of this group. Using approximate solutions of Schwinger-Dyson and Bethe-Salpeter equations, we calculate meson masses and investigate how these depend on N_f. We focus on the range of N_f extending from near the boundary with a non-Abelian Coulomb phase, where the theory exhibits a slowly running (``walking'') gauge coupling, toward smaller values where the theory has non-walking behavior. Our results include determinations of the masses of the lowest-lying flavor-adjoint mesons with J^PC = 0⁻⁺, 1⁻⁻, 0⁺⁺, and 1⁺⁺ (the generalized π, ρ, a₀, and a₁). Related results are given for flavor-singlet mesons and for the generalization of f_π. These results give insight into the change from walking to non-walking behavior in a gauge theory, as a function of N_f.

We evaluate the LHC discovery potential for a light Higgs boson in tH (→ℓνbbjj) production, within the Standard Model and if a new Q = 2/3 quark singlet T with a moderate mass exists. In the latter case, T pair production with decays T→W⁺b H/Ht W⁻→W⁺bW⁻H provides an important additional source of Higgs bosons giving the same experimental signature, and other decay modes T→Ht H→W⁺bW⁻HH, T→Zt H/Ht Z→W⁺bW⁻HZ further enhance this signal. Both analyses are carried out with particle-level simulations of signals and backgrounds, including t plus n = 0,...,5 jets which constitute the main background by far. Our estimate for SM Higgs discovery in tH production, 0.4σ significance for M_H = 115 GeV and an integrated luminosity of 30 fb⁻¹, is similar to the most recent ones by CMS which also include the full tnj background. We show that, if a quark singlet with a mass m_T = 500 GeV exists, the luminosity required for Higgs discovery in this final state is reduced by more than two orders of magnitude, and 5σ significance can be achieved already with 8 fb⁻¹. This new Higgs signal will not be seen unless we look for it: with this aim, a new specific final state reconstruction method is presented. Finally, we consider the sensitivity to search for Q = 2/3 singlets. The combination of these three decay modes allows to discover a 500 GeV quark with 7 fb⁻¹ of luminosity.

The addition of fundamental degrees of freedom to a theory which is dual (at low energies) to = 2 SYM in 1+3 dimensions is studied. The gauge theory lives on a stack of N_c D5 branes wrapping an S² with the appropriate twist, while the fundamental hypermultiplets are introduced by adding a different set of N_f D5-branes. In a simple case, a system of first order equations taking into account the backreaction of the N_f ∼ N_c flavor branes is derived. From it, the modification of the holomorphic coupling is computed explicitly. Mesonic excitations are also discussed.

We calculate the (p,q) string spectrum in a warped deformed conifold using the dielectric brane method. The spectrum is shown to have the same functional form as in the dual picture of a wrapped D3-brane with electric and magnetic fluxes on its world volume. The agreement is exact in the limit where q is large. We also calculate the dielectric spectrum in the S-dual picture. The spectrum in the S-dual picture has the same form as in the original picture but it is not exactly S-dual invariant due to an interchange of Casimirs of the non-Abelian gauge symmetries. We argue that in order to restore S-duality invariance the non-Abelian brane action should be refined, probably by a better prescription for the non-Abelian trace operation.

The topological string partition function for the neighbourhood of three spheres meeting at one point in a Calabi-Yau threefold, the so-called 'closed topological vertex', is shown to be reproduced by a simple Calabi-Yau crystal model which counts plane partitions inside a cube of finite size. The model is derived from the topological vertex formalism. This derivation can be understood as 'moving off the strip' in the terminology of hep-th/0410174, and offers a possibility to simplify topological vertex techniques to a broader class of Calabi-Yau geometries. To support this claim a flop transition of the closed topological vertex is considered and the partition function of the resulting geometry is computed in agreement with general expectations.

Using the non-minimal version of the pure spinor formalism, manifestly super-Poincaré covariant superstring scattering amplitudes can be computed as in topological string theory without the need of picture-changing operators. The only subtlety comes from regularizing the functional integral over the pure spinor ghosts. In this paper, it is shown how to regularize this functional integral in a BRST-invariant manner, allowing the computation of arbitrary multiloop amplitudes. The regularization method simplifies for scattering amplitudes which contribute to ten-dimensional F-terms, i.e. terms in the ten-dimensional superspace action which do not involve integration over the maximum number of θ's.

We construct the topological partition function of local nontoric del Pezzo surfaces using the ruled vertex formalism.

Global fits to charmless B→PP decays in the framework of flavor SU(3) symmetry are updated and improved without reference to the sin 2β measured from the charmonium decay modes. Fit results directly constrain the (,) vertex of the unitarity triangle, and are used to predict the branching ratios and CP asymmetries of all decay modes, including those of the B_s system. Different schemes of SU(3) breaking in decay amplitude sizes are analyzed. The major breaking effect between strangeness-conserving and strangeness-changing decays can be accounted for by including a ratio of decay constants in tree and color-suppressed amplitudes. The possibility of having a new physics contribution to Kπ decays is also examined from the data fitting point of view.

We present the diagrammatic technique for calculating the free energy of the matrix eigenvalue model (the model with arbitrary power β by the Vandermonde determinant) to all orders of 1/N expansion in the case where the limiting eigenvalue distribution spans arbitrary (but fixed) number of disjoint intervals (curves).

We investigate the low-energy effective description of non-geometric compactifications constructed by T-dualizing two or three of the directions of a T³ with non-vanishing H-flux. Our approach is to introduce a D3-brane in these geometries and to take an appropriate decoupling limit. In the case of two T-dualities, we find at low energies a non-commutative T² fibered non-trivially over an S¹. In the UV this theory is still decoupled from gravity, but is dual to a little string theory with flavor. For the case of three T-dualities, we do not find a sensible decoupling limit, casting doubt on this geometry as a low-energy effective notion in critical string theory. However, by studying a topological toy model in this background, we find a non-associative geometry similar to one found by Bouwknegt, Hannabuss, and Mathai.

Within the framework of QCD we compute renormalization constants for the strong coupling and the quark masses to four-loop order. We apply the scheme and put special emphasis on the additional couplings which have to be taken into account. This concerns theε-scalar–quark Yukawa coupling as well as the vertex containing fourε-scalars. For a supersymmetric Yang Mills theory, we find, in contrast to a previous claim, that the evanescent Yukawa coupling equals the strong coupling constant through three loops as required by supersymmetry.

We give evidence in favour of a string/black hole transition in the case of BPS fundamental string states of the Heterotic string. Our analysis goes beyond the counting of degrees of freedom and considers the evolution of dynamical quantities in the process. As the coupling increases, the string states decrease their size up to the string scale when a small black hole is formed. We compute the absorption cross section for several fields in both the black hole and the perturbative string phases. At zero frequency, these cross sections can be seen as order parameters for the transition. In particular, for the scalars fixed at the horizon the cross section evolves to zero when the black hole is formed.

We construct supersymmetric D-brane probe solutions in the background of the 2-charge D1-D5 system on M, where M is either K3 or T⁴. We focus on `near-horizon bound states' that preserve supersymmetries of the near-horizon AdS₃ × S³ × M geometry and are static with respect to the global time coordinate. We find a variety of half-BPS solutions that span an AdS₂ subspace in AdS₃, carry worldvolume flux and can wrap an S² within S³ and/or supersymmetric cycles in M.

We investigate the possibility of studying new physics in various processes of t-quark production using kinematical distributions of the secondary lepton coming from the decay of t quarks. We show that the angular distribution of the secondary lepton is insensitive to the anomalous tbW vertex and hence is a pure probe of new physics in a generic process of t-quark production. The energy distribution of the lepton is distinctly affected by anomalous tbW couplings and can be used to analyze them independent of the production process of t quarks. The effects of t polarization on the distributions of the decay lepton are demonstrated for top-pair production process at a γγ collider mediated by a heavy Higgs boson.

We compare solutions of the quantum string Bethe equations with explicit one-loop calculations in the sigma-model on AdS₅ × S⁵. The Bethe ansatz exactly reproduces the spectrum of infinitely long strings. When the length is finite, we find that deviations from the exact answer arise which are exponentially small in the string length.

We compute the supersymmetric (SUSY) contributions to the observables in B_s⁰→K⁺K⁻ and B_s⁰→K⁰⁰ decays. The hadronic parameters in the standard-model (SM) amplitudes are obtained from the B_d⁰→K⁰⁰ decay using a recent approach that combines flavor SU(3) symmetry and a controlled input from QCD factorization. The latest experimental data for BR(B_s⁰→K⁺K⁻) is in agreement with the SM prediction. We study how the branching ratios and the direct and mixing-induced CP asymmetries of both B_s⁰→K decay modes are affected with the inclusion of SUSY, after imposing constraints from BR(B→X_sγ), B→πK and ΔM_s over the parameter space. While the branching ratios remain unaffected by SUSY, we identify the CP asymmetries of the B_s⁰→K decays as the most promising observables to look for large deviations from the SM.

We develop means of computing exact degeneracies of BPS black holes on toric Calabi-Yau manifolds. We show that the gauge theory on the D4 branes wrapping ample divisors reduces to 2D q-deformed Yang-Mills theory on necklaces of P¹'s. As explicit examples we consider local P², P¹ × P¹ and A_k type ALE space times C. At large N the D-brane partition function factorizes as a sum over squares of chiral blocks, the leading one of which is the topological closed string amplitude on the Calabi-Yau. This is in complete agreement with the recent conjecture of Ooguri, Strominger and Vafa.

We exploit the properties of the hyperbolic space ³ to discuss a simplicial setting for open/closed string duality based on (random) Regge triangulations decorated with null twistorial fields. We explicitly show that the twistorial N-points function, describing Dirichlet correlations over the moduli space of open N-bordered genus g surfaces, is naturally mapped into the Witten-Kontsevich intersection theory over the moduli space of N-pointed closed Riemann surfaces of the same genus. We also discuss various aspects of the geometrical setting which connects this model to PSL(2,) Chern-Simons theory.

We present a detailed study of the charged current Drell-Yan process, which includes the exact (α) electroweak corrections properly matched with leading-log effects due to multiple-photon emission, as required by the experiments at the Tevatron and the LHC. Numerical results for the relevant observables of single W boson production at hadron colliders are presented. The impact of the radiative corrections and of some sources of theoretical uncertainty is discussed in detail. The calculation has been implemented in the new version of the event generator HORACE, which is available for precision simulations of the charged current Drell-Yan process.

By weakly gauging one of the U(1) subgroups of the R-symmetry group, = 4 super-Yang-Mills theory can be coupled to electromagnetism, thus allowing a computation of photon production and related phenomena in a QCD-like non-Abelian plasma at both weak and strong coupling. We compute photon and dilepton emission rates from finite temperature = 4 supersymmetric Yang-Mills plasma both perturbatively at weak coupling to leading order, and non-perturbatively at strong coupling using the AdS/CFT duality conjecture. Comparison of the photo-emission spectra for = 4 plasma at weak coupling, = 4 plasma at strong coupling, and QCD at weak coupling reveals several systematic trends which we discuss. We also evaluate the electric conductivity of = 4 plasma in the strong coupling limit, and to leading-log order at weak coupling. Current-current spectral functions in the strongly coupled theory exhibit hydrodynamic peaks at small frequency, but otherwise show no structure which could be interpreted as well-defined thermal resonances in the high-temperature phase.

We investigate the weak gravity bounds on the U(1) gauge theory and scalar field theories in various dimensional noncommutative space. Many results are obtained, such as the upper bound on the noncommutative scale g_YMM_p for four dimensional noncommutative U(1) gauge theory. We also discuss the weak gravity bounds on their commutative counterparts. For example, our result on 4 dimensional noncommutative U(1) gauge theory reduces in certain limit to its commutative counterpart suggested by Arkani-Hamed et.al at least at tree-level.

We investigate, from a spacetime perspective, some aspects of Horowitz's recent conjecture that black strings may catalyze the decay of Kaluza-Klein spacetimes into a bubble of nothing. We identify classical configurations that interpolate between flat space and the bubble, and discuss the energetics of the transition. We investigate the effects of winding tachyons on the size and shape of the barrier and find no evidence at large compactification radius that tachyons enhance the tunneling rate. For the interesting radii, of order the string scale, the question is difficult to answer due to the failure of the α' expansion.

In this article we study the general structure and special properties of the Schwinger-Dyson equation for the gluon propagator constructed with the pinch technique, together with the question of how to obtain infrared finite solutions, associated with the generation of an effective gluon mass. Exploiting the known all-order correspondence between the pinch technique and the background field method, we demonstrate that, contrary to the standard formulation, the non-perturbative gluon self-energy is transverse order-by-order in the dressed loop expansion, and separately for gluonic and ghost contributions. We next present a comprehensive review of several subtle issues relevant to the search of infrared finite solutions, paying particular attention to the role of the seagull graph in enforcing transversality, the necessity of introducing massless poles in the three-gluon vertex, and the incorporation of the correct renormalization group properties. In addition, we present a method for regulating the seagull-type contributions based on dimensional regularization; its applicability depends crucially on the asymptotic behavior of the solutions in the deep ultraviolet, and in particular on the anomalous dimension of the dynamically generated gluon mass. A linearized version of the truncated Schwinger-Dyson equation is derived, using a vertex that satisfies the required Ward identity and contains massless poles belonging to different Lorentz structures. The resulting integral equation is then solved numerically, the infrared and ultraviolet properties of the obtained solutions are examined in detail, and the allowed range for the effective gluon mass is determined. Various open questions and possible connections with different approaches in the literature are discussed.

We present an improved determination of the CP and CPT violation parameters Re() and Im(δ) based on the unitarity condition (Bell-Steinberger relation) and on recent results from the KLOE experiment. We find Re() = (159.6±1.3) × 10⁻⁵ and Im(δ) = (0.4±2.1) × 10⁻⁵, consistent with no CPT violation.

We derive compact expressions for one-loop scattering amplitudes of four open-string vector bosons around supersymmetric configurations with intersecting or magnetized D-branes on toroidal orbifolds. We check the validity of our formulae against the structure of their singularities and their behaviour under modular transformations to the transverse channel, exposing closed string exchange. We then specialize to the case of forward scattering and compute the total cross section for two massless open string vector bosons on the brane to decay into closed strings in the bulk, relying on the optical theorem. Although not directly related to collider signatures our predictions represent a step forward towards unveiling phenomenological implications of open and unoriented superstrings.

We unravel some subtleties involving the definition of sphere angular momentum charges in AdS_q × S^p spacetimes, or equivalently, R-symmetry charges in the dual boundary CFT. In the AdS₃ context, it is known that charges can be generated by coordinate transformations, even though the underlying theory is diffeomorphism invariant. This is the bulk version of spectral flow in the boundary CFT. We trace this behavior back to special properties of the p-form field strength supporting the solution, and derive the explicit formulas for angular momentum charges. This analysis also reveals the higher dimensional origin of three dimensional Chern-Simons terms and of chiral anomalies in the boundary theory.

We study d = 2 0A string theory perturbed by tachyon momentum modes in backgrounds with non-trivial tachyon condensate and Ramond-Ramond (RR) flux. In the matrix model description, we uncover a complexified Toda lattice hierarchy constrained by a pair of novel holomorphic string equations. We solve these constraints in the classical limit for general RR flux and tachyon condensate. Due to the non-holomorphic nature of the tachyon perturbations, the transcendental equations which we derive for the string susceptibility are manifestly non-holomorphic. We explore the phase structure and critical behavior of the theory.

We discuss the potential of analyses at the Large Hadron Collider and the planned International Linear Collider to explore low-energy supersymmetry in a difficult region of the parameter space characterized by masses of the scalar SUSY particles around 2 TeV. Precision analyses of cross sections for light chargino production and forward–backward asymmetries of decay leptons and hadrons at the first stage of the ILC with s^1/2 = 500 GeV, together with mass information on ⁰₂ and squarks from the LHC, allow us to determine the underlying fundamental gaugino/higgsino MSSM parameters and to constrain the masses of the heavy, kinematically inaccessible sparticles. No assumptions on a specific SUSY-breaking mechanism are imposed. For this analysis the complete spin correlations between production and decay processes must be taken into account.

We present a method for solving BPS equations obtained in the collective-field approach to matrix models. The method enables us to find BPS solutions and quantum excitations around these solutions in the one-matrix model, and in general for the Calogero model. These semiclassical solutions correspond to giant gravitons described by matrix models obtained in the framework of AdS/CFT correspondence. The two-field model, associated with two types of giant gravitons, is investigated. In this duality-based matrix model we find the finite form of the n-soliton solution. The singular limit of this solution is examined and a realization of open-closed string duality is proposed.

Terascale supersymmetry has the potential to provide a natural explanation of the dominant dark matter component of the standard ΛCDM cosmology. However once we impose the constraints on minimal supersymmetry parameters from current particle physics data, a satisfactory dark matter abundance is no longer prima facie natural. This Neutralino Tuning Problem could be a hint of nonstandard cosmology during and/or after the Terascale era. To quantify this possibility, we introduce an alternative cosmological benchmark based upon a simple model of quintessential inflation. This benchmark has no free parameters, so for a given supersymmetry model it allows an unambiguous prediction of the dark matter relic density. As a example, we scan over the parameter space of the CMSSM, comparing the neutralino relic density predictions with the bounds from WMAP. We find that the WMAP–allowed regions of the CMSSM are an order of magnitude larger if we use the alternative cosmological benchmark, as opposed to ΛCDM. Initial results from the CERN Large Hadron Collider will distinguish between the two allowed regions.

We describe progress towards constructing a quantum theory of de Sitter space in four dimensions. In particular we indicate how both particle states and Schwarzschild de Sitter black holes can arise as excitations in a theory of a finite number of fermionic oscillators. The results about particle states depend on a conjecture about algebras of Grassmann variables, which we state, but do not prove.

We calculate a number of observables related to particle-antiparticle mixing in the Littlest Higgs model with T-parity (LHT). The resulting effective Hamiltonian for ΔF = 2 transitions agrees with the one of Hubisz et al., but our phenomenological analysis goes far beyond the one of these authors. In particular, we point out that the presence of mirror fermions with new flavour and CP-violating interactions allows to remove the possible Standard Model (SM) discrepancy between the CP asymmetry S_ψKS and large values of |V_ub| and to obtain for the mass difference ΔM_s < (ΔM_s)_SM as suggested by the recent result by the CDF collaboration. We also identify a scenario in which simultaneously significant enhancements of the CP asymmetries S_ψϕ and A_SL^q relative to the SM are possible, while satisfying all existing constraints, in particular from the B→X_sγ decay and A_CP(B→X_sγ) that are presented in the LHT model here for the first time. In another scenario the second, non-SM, value for the angle γ = −(109±16)° from tree level decays, although unlikely, can be made consistent with all existing data with the help of mirror fermions. We present a number of correlations between the observables in question and study the implications of our results for the mass spectrum and the weak mixing matrix of mirror fermions. In the most interesting scenarios, the latter one turns out to have a hierarchical structure that differs significantly from the CKM one.

We present a framework for grand unification in which the grand unified symmetry is broken spontaneously by strong gauge dynamics, and yet the physics at the unification scale is described by (weakly coupled) effective field theory. These theories are formulated, through the gauge/gravity correspondence, in truncated 5D warped spacetime with the UV and IR branes setting the Planck and unification scales, respectively. In most of these theories, the Higgs doublets arise as composite states of strong gauge dynamics, corresponding to degrees of freedom localized to the IR brane, and the observed hierarchies of quark and lepton masses and mixings are explained by the wavefunction profiles of these fields in the extra dimension. We present several realistic models in this framework. We focus on one in which the doublet-triplet splitting of the Higgs fields is realized within the dynamical sector by the pseudo-Goldstone mechanism, with the associated global symmetry corresponding to a bulk gauge symmetry in the 5D theory. Alternatively, the light Higgs doublets can arise as a result of dynamics on the IR brane, without being accompanied by their triplet partners. Gauge coupling unification and proton decay can be studied in these models using higher dimensional effective field theory. The framework also sets a stage for further studies of, e.g., proton decay, fermion masses, and supersymmetry breaking.

We analyze the Higgs intense–coupling regime, in which all Higgs particles of the Minimal Supersymmetric Standard Model are light with masses of the same order and the value of tan β the ratio of vacuum expectation values of the two Higgs fields is large, in the framework of Supergravity scenarios with non–universal soft Supersymmetry breaking scalar masses in the Higgs sector. In particular, we calculate the relic density abundance of the lightest neutralino candidate for cold dark matter and the rates in direct and indirect detection at present and future experiments. We first show that while in the mSUGRA model this regime is disfavored by present data, there are regions in the parameter space of models with non–universal Higgs masses where it can occur. We then show that because of the large value of tan β and the relatively low values of the neutral Higgs boson masses, the cross section for neutralino–nucleon scattering is strongly enhanced in this regime and would allow for the observation of a signal in direct detection experiments such as CDMS–Soudan. The expected sensitivity of gamma–ray detectors like GLAST might be also sufficient to observe the annihilation of neutralinos in such a regime.