Table of contents

The need to enforce fermionic antisymmetry in the nuclear many-body problem commonly requires use of single-particle coordinates, defined relative to some fixed origin. To obtain physical operators which nonetheless act on the nuclear many-body system in a Galilean-invariant fashion, thereby avoiding spurious center-of-mass contributions to observables, it is necessary to express these operators with respect to the translational intrinsic frame. Several commonly-encountered operators in nuclear many-body calculations, including the magnetic dipole and electric quadrupole operators (in the impulse approximation) and generators of U(3) and $\text{Sp}\left(3,\mathbb{R}\right)$ symmetry groups, are bilinear in the coordinates and momenta of the nucleons and, when expressed in intrinsic form, become two-body operators. To work with such operators in a second-quantized many-body calculation, it is necessary to relate three distinct forms: the defining intrinsic-frame expression, an explicitly two-body expression in terms of two-particle relative coordinates, and a decomposition into one-body and separable two-body parts. We establish the relations between these forms, for general (non-scalar and non-isoscalar) operators bilinear in coordinates and momenta.

This white paper reports on the discussions of the 2018 Facility for Rare Isotope Beams Theory Alliance (FRIB-TA) topical program 'From bound states to the continuum: Connecting bound state calculations with scattering and reaction theory'. One of the biggest and most important frontiers in nuclear theory today is to construct better and stronger bridges between bound state calculations and calculations in the continuum, especially scattering and reaction theory, as well as teasing out the influence of the continuum on states near threshold. This is particularly challenging as many-body structure calculations typically use a bound state basis, while reaction calculations more commonly utilize few-body continuum approaches. The many-body bound state and few-body continuum methods use different language and emphasize different properties. To build better foundations for these bridges, we present an overview of several bound state and continuum methods and, where possible, point to current and possible future connections.

We illustrate the connection between electron and neutrino scattering off nuclei and show how the former process can be used to constrain the description of the latter. After reviewing some of the nuclear models commonly used to study lepton-nucleus reactions, we describe in detail the SuSAv2 model and show how its predictions compare with the available electron- and neutrino-scattering data over the kinematical range going from the quasi-elastic peak to pion-production and highly inelastic scattering.

We revisit the rare decays of the Higgs boson to two different quarks in the standard model (SM), which arise at the one-loop level. We perform Taylor series expansions to the complete form factors of the decay amplitudes, according to their different mass hierarchies, this allow us to take full advantage of the Glashow–Iliopoulos–Maiani (GIM) mechanism to eliminate spurious contributions and retain those that truly contribute. We found that Br(H → uc) = 5.00 × 10⁻²⁰, Br(H → ds) = 1.19 × 10⁻¹¹, Br(H → db) = 5.16 × 10⁻⁹ and Br(H → sb) = 1.15 × 10⁻⁷. Our predictions for the H → uc, ds decays disagree with previous results in the literature.

We study the possibility of texture zeros in Majorana light neutrino mass matrix in the light of dark large mixing angle (DLMA) solution to solar neutrino problem where solar mixing angle (sin²θ₁₂ ≃ 0.7) lies in the second octant instead of first octant in standard large mixing angle (LMA) scenario (sin²θ₁₂ ≃ 0.3). In three neutrino scenario, we find that LMA and DLMA solutions lead to different set of allowed and disallowed textures with one and two zeros. While being consistent with existing bounds from neutrino oscillation data, neutrinoless double beta decay and cosmology these allowed textures also lead to interesting correlations among light neutrino parameters which can distinguish LMA from DLMA solution. We also check the implications for texture zeros in 3 + 1 neutrino scenario using both LMA and DLMA solutions. While LMA and DLMA solutions do not play decisive role in ruling out texture zeros in this case, they do give rise to distinct predictions and correlations between light neutrino parameters.

In this study we present a unified phenomenological analysis of the scalar glueball and scalar meson spectra within an AdS/QCD framework in the bottom up approach. For this purpose we generalize the recently developed graviton soft-wall (GSW) model, which has shown an excellent agreement with the lattice QCD glueball spectrum, to a description of glueballs and mesons with a unique energy scale. In this scheme, dilatonic effects, are incorporated in the metric as a deformation of the AdS space. We apply the model also to the heavy meson spectra with success. We obtain quadratic mass equations for all scalar mesons while the glueballs satisfy an almost linear mass equation. Besides their spectra, we also discuss the mixing of scalar glueball and light scalar meson states within a unified framework: the GSW model. To this aim, the light-front (LF) holographic approach, which connects the mode functions of AdS/QCD to the LF wave functions, is applied. This relation provides the probabilistic interpretation required to properly investigate the mixing conditions.

We discuss an experiment to investigate neutrino physics at the LHC, with emphasis on tau flavour. As described in our previous paper Beni et al (2019 J. Phys. G: Nucl. Part. Phys.46 115008), the detector can be installed in the decommissioned TI18 tunnel, ≈480 m downstream the ATLAS cavern, after the first bending dipoles of the LHC arc. The detector intercepts the intense neutrino flux, generated by the LHC beams colliding in IP1, at large pseudorapidity η, where neutrino energies can exceed a TeV. This paper focuses on exploring the neutrino pseudorapity versus energy phase space available in TI18 in order to optimize the detector location and acceptance for neutrinos originating at the pp interaction point, in contrast to neutrinos from pion and kaon decays. The studies are based on the comparison of simulated pp collisions at $\sqrt{s}=$ 13 TeV: PYTHIA events of heavy quark (c and b) production, compared to DPMJET minimum bias events (including charm) with produced particles traced through realistic LHC optics with FLUKA. Our studies favour a configuration where the detector is positioned off the beam axis, slightly above the ideal prolongation of the LHC beam from the straight section, covering 7.4 < η < 9.2. In this configuration, the flux at high energies (0.5–1.5 TeV and beyond) is found to be dominated by neutrinos originating directly from IP1, mostly from charm decays, of which ≈50% are electron neutrinos and ≈5% are tau neutrinos. The contribution of pion and kaon decays to the muon neutrino flux is found small at those high energies. With 150 fb⁻¹ of delivered LHC luminosity in Run 3 the experiment can record a few thousand very high energy neutrino charged current (CC) interactions and over 50 tau neutrino CC events. These events provide useful information in view of a high statistics experiment at HL–LHC. The electron and muon neutrino samples can extend the knowledge of the charm PDF to a new region of x, which is dominated by theory uncertainties. The tau neutrino sample can provide first experience on reconstruction of tau neutrino events in a very boosted regime.

In this paper, we study in detail the phenomenology of the non-SM SU(2)_V singlet Higgs boson ${H}_{1}^{0}$ at the 14 TeV Large Hadron Collider (LHC) in the Georgi–Machacek (GM) model. We present a systematic comparison of the production mechanisms and decay modes of ${H}_{1}^{0}$, especially the vector-boson fusion (VBF) and gluon–gluon fusion (ggF) production mechanisms and the decays to W⁺W⁻, ZZ, H₅H₅, H₃H₃, ${H}_{3}^{{\pm}}{W}^{\mp }$ and ${H}_{3}^{0}Z$. After performing a comprehensive scan over the seven-dimensional parameter space of the GM model, we find that the ${H}_{1}^{0}\to {H}_{3}^{{\pm}}{W}^{\mp }$, ${H}_{1}^{0}\to {H}_{3}^{0}Z$ and ${H}_{1}^{0}\to {H}_{3}{H}_{3}$ decay channels are almost excluded by the theoretical and experimental constraints, while ${H}_{1}^{0}$ can decay into H₅H₅ in an appreciable region of the GM parameter space. Based on the scanning results, we discuss detailedly the ${H}_{1}^{0}$ production via ggF and VBF with subsequent decays of ${H}_{1}^{0}\to {H}_{5}{H}_{5}\to {W}^{+}{W}^{-}{W}^{+}{W}^{-}\to {{l}^{{\pm}}}_{\nu }^{\left(-\right)}{{l}^{{\pm}}}_{\nu }^{\left(-\right)}+4\mathrm{j}\mathrm{e}\mathrm{t}\mathrm{s}$, ${H}_{1}^{0}\to ZZ\to {l}^{+}{l}^{-}{l}^{+}{l}^{-}$ and ${H}_{1}^{0}\to {W}^{+}{W}^{-}\to {e}^{{\pm}}{\mu }^{\mp }\nu \overline{\nu }$ at the 14 TeV LHC. The integrated cross sections and some kinematic distributions of final products for both the signals at some benchmark points of the GM parameter space and the corresponding SM backgrounds are provided. If the decay to H₅H₅ is kinematically allowed, ${H}_{1}^{0}$ can be detected in the ${H}_{1}^{0}\to {H}_{5}{H}_{5}\to {W}^{+}{W}^{-}{W}^{+}{W}^{-}\to {{l}^{{\pm}}}_{\nu }^{\left(-\right)}{{l}^{{\pm}}}_{\nu }^{\left(-\right)}+4\mathrm{j}\mathrm{e}\mathrm{t}\mathrm{s}$ decay channel at high-luminosity LHC unless $BR\left({H}_{1}^{0}\to {H}_{5}{H}_{5}\right)$ is too small or ${m}_{{H}_{1}^{0}}$ is too high. In the mass range of $2{m}_{V}< sim {m}_{{H}_{1}^{0}}{< }2{m}_{{H}_{5}}$, the vector-boson fusion is the most promising production channel in search of ${H}_{1}^{0}$ due to the two hard tagging jets in the final state, and we may expect to discover ${H}_{1}^{0}$ in both ${H}_{1}^{0}\to {W}^{+}{W}^{-}\to {e}^{{\pm}}{\mu }^{\mp }\nu \overline{\nu }$ and ${H}_{1}^{0}\to ZZ\to 4l$ decay channels with $\mathcal{O}\left(1{0}^{2}\right)\enspace {\mathrm{f}\mathrm{b}}^{-1}$ of data if the decay branching ratio of ${H}_{1}^{0}$ to a pair of weak gauge bosons is sufficiently large.

I analyze a possibility of building an isobar model of the kaon–hyperon pair photoproduction in the γp → K⁺Λ, $\gamma p\to {K}_{S}^{0}{{\Sigma}}^{+}$, and γp → K⁺Σ processes, where the Born terms play a comparatively small role in the full amplitude. The total width of hadron resonances can be written in the form of a sum of partial contributions into the K⁺Λ, ${K}_{S}^{0}{{\Sigma}}^{+}$, and K⁺Σ channels, and the effective inelastic channel with zero strangeness. The introduction of the effective inelastic channel makes it possible to partially restore the broken unitarity of the total amplitude of photoproduction. The latter includes the gauge-invariant Born and resonant s-, t-, and u-channel contributions calculated in the tree-level approximation. The obtained sets of hadron decay widths of intermediate resonances and coupling constants calculated using these decay widths allow one to equally well reproduce the total and some differential cross sections of the K⁺Λ, ${K}_{S}^{0}{{\Sigma}}^{+}$, and K⁺Σ photoproduction.

The puzzle remains in the large discrepancy between neutron lifetime measured by the two distinct experimental approaches—counts of beta decays in a neutron beam and storage of ultracold neutrons in a potential trap, namely, the beam method versus the bottle method. In this paper, we propose a new experiment to measure the neutron lifetime in a cold neutron (CN) beam with a sensitivity goal of 0.1% or sub-1 s. The neutron beta decays will be counted in a superfluid helium-4 scintillation detector at 0.5 K, and the neutron flux will be simultaneously monitored by the helium-3 captures in the same volume. The CN beam must be of wavelength λ > 16.5 Å to eliminate scattering with superfluid helium. A new precise measurement of neutron lifetime with the beam method of unique inherent systematic effects will greatly advance in resolving the puzzle.

The event-by-event fluctuations of the mean transverse momentum (p_t) in Au + Au collisions at $\sqrt{{s}_{\text{NN}}}=7.7$–200 GeV and Pb + Pb collisions at $\sqrt{{s}_{\text{NN}}}=2.76\enspace \mathrm{T}\mathrm{e}\mathrm{V}$ are analyzed using a multiphase transport model (AMPT) with a dynamical quark coalescence mechanism (DQCM). The analysis shows that at 19.6 GeV there exists a splitting between the relative dynamical mean-p_t fluctuation from the DQCM AMPT and from the original AMPT (i.e., AMPT with string melting) at freeze-out. Based on the hadron information obtained at different stages of nuclear collisions from the AMPT model, we show that this splitting first arises from the quark coalescence hadronization process, and then develops during the resonance decay process. The results are compared with measurements from STAR at the relativistic heavy-ion collider (RHIC) and ALICE at the large hadron collider (LHC). The comparison shows that the relative dynamical mean-p_t fluctuation for non-peripheral collisions at 200 GeV and 2.76 TeV can be explained by these two coalescence scenarios. After introducing the DQCM into the AMPT model, the results become slightly larger and appeared to be closer to the experimental data for $\sqrt{{s}_{\text{NN}}}=7.7$–62.4  GeV. Specially, the relative dynamical mean-p_t fluctuation with centrality of 0%–5% can be well reproduced by the DQCM AMPT.

We perform a comprehensive study of partonic energy loss reflected in the nuclear modification factors of charged particles and jets measured in PbPb collisions at $\sqrt{{s}_{\text{NN}}}$ = 2.76 and 5.02 TeV in wide transverse momentum (p_T) and centrality range. The p_T distributions in pp collisions are fitted with a modified power law and the nuclear modification factor in PbPb collisions can be obtained using effective shift (Δp_T) in the spectrum measured at different centralities. Driven by physics consideration, the functional form of energy loss given by Δp_T can be assumed as power law with different power indices in three different p_T regions. The power indices and the boundaries of three p_T regions are obtained by fitting the measured nuclear modification factor as a function of p_T in all collision centralities simultaneously. The energy loss in different collisions centralities are described in terms of fractional power of number of participants. It is demanded that the power law functions in three p_T regions and their derivatives are continuous at the p_T boundaries. The Δp_T for light charged particles is found to increase linearly with p_T in low p_T region below ∼5–6 GeV c⁻¹ and approaches a constant value in high p_T region above ∼22–29 GeV c⁻¹ with an intermediate power law connecting the two regions. The method is also used for jets and it is found that for jets, the Δp_T increases approximately linearly even at very high p_T.

High spin states in ¹⁰⁴Pd were populated via ⁹⁴Zr(¹³C, 3nγ) fusion-evaporation reaction at a beam energy of 55 MeV. The Indian National Gamma Array was utilized to detect the de-exciting γ-rays. Lifetimes of states in the negative parity bands have been determined using the Doppler shift attenuation method. The present lifetime results suggest a moderate quadrupole deformation (β₂ ≈ 0.2) for the negative parity bands. The Woods–Saxon total Routhian surface calculations have also been carried out which predicted a similar deformation for these bands. In addition, lifetimes of states in the positive parity band have also been determined. Present results found in agreement with the earlier reported values of lifetimes and hence agreed with the antimagnetic rotational character of the band as interpreted earlier.

A large wealth of data and a variety of models led to significant progress in understanding the spectra of deformed nuclei. However, a robust theoretical approach, which is less reliant on adjustable parameters is still elusive. Due to the scarcity of data, this drawback gets more pronounced while studying the exotic nuclei. With the motive to overcome this difficulty, we have developed the nonadiabatic quasiparticle approach for the description of rotational states in triaxial deformed odd–odd nuclei. The rotation-particle coupling is carried out utilizing an appropriate basis transformation such that the matrix elements of the odd–odd system can be written in terms of the rotor energies. This provides the advantage of studying the role of core more efficiently as compared to the conventional particle rotor model. The residual interaction between the valence proton and neutron is incorporated in two reliable ways, namely, the constant potential form and the zero-range interaction.

In this paper we discuss the interacting hadron resonance gas (HRG) model in presence of a constant external magnetic field. The short range repulsive interaction between hadrons are accounted through Van der Waals excluded volume correction to the ideal gas pressure. Here we take the sizes of hadrons as r_π (pion radius) = 0 fm, r_K (kaon radius) = 0.35 fm, r_m (all other meson radii) = 0.3 fm and r_b (baryon radii) = 0.5 fm. We analyse the effect of uniform background magnetic field on the thermodynamic properties of interacting hadron gas. We especially discuss the effect of interactions on the behaviour of magnetization of low temperature hadronic matter. The vacuum terms have been regularized using magnetic field independent regularization scheme. We find that the magnetization of hadronic matter is positive which implies that the low temperature hadronic matter is paramagnetic. We further find that the repulsive interactions have very negligible effect on the overall magnetization of the hadronic matter and the paramagnetic property of the hadronic phase remains unchanged. We have also investigated the effects of short range repulsive interactions as well as the magnetic field on the baryon and electric charge number susceptibilities of hadronic matter within the ambit of excluded volume HRG model.

Weak decays in heavy nuclei with charge numbers Z = 101–109 are studied within a microscopic formalism based on deformed self-consistent Skyrme Hartree–Fock mean-field calculations with pairing correlations. The half-lives of β⁺ decay and electron capture are compared with α-decay half-lives obtained from phenomenological formulas. Transfermium isotopes of Md, No, Lr, Rf, Db, Sg, Bh, Hs, and Mt that can be produced in the frontier of cold and hot fusion-evaporation channels are considered. Several isotopes are identified whose β⁺/EC- and α-decay half-lives are comparable. The competition between these decay modes opens the possibility of new pathways towards the islands of stability.