Table of contents

Spin dipole (SD) strengths for double beta-decay (DBD) nuclei were studied experimentally for the first time by using measured cross sections of (³He, t) charge-exchange reactions (CERs). Then SD nuclear matrix elements (NMEs) ${M}_{\alpha }({\rm{SD}})$ for low-lying 2⁻ states were derived from the experimental SD strengths by referring to the experimental α = GT (Gamow–Teller) and α = F (Fermi) strengths. They are consistent with the empirical NMEs $M({\rm{SD}})$ based on the quasi-particle model with the empirical effective SD coupling constant. The CERs are used to evaluate the SD NME, which is associated with one of the major components of the neutrino-less DBD NME.

The precision reactor oscillation and spectrum experiment, PROSPECT, is designed to make a precise measurement of the antineutrino spectrum from a highly-enriched uranium reactor and probe eV-scale sterile neutrinos by searching for neutrino oscillations over a distance of several meters. PROSPECT is conceived as a 2-phase experiment utilizing segmented ⁶Li-doped liquid scintillator detectors for both efficient detection of reactor antineutrinos through the inverse beta decay reaction and excellent background discrimination. PROSPECT Phase I consists of a movable 3 ton antineutrino detector at distances of 7–12 m from the reactor core. It will probe the best-fit point of the ${\nu }_{e}$ disappearance experiments at 4σ in 1 year and the favored region of the sterile neutrino parameter space at $\gt 3\sigma$ in 3 years. With a second antineutrino detector at 15–19 m from the reactor, Phase II of PROSPECT can probe the entire allowed parameter space below 10 eV² at 5σ in 3 additional years. The measurement of the reactor antineutrino spectrum and the search for short-baseline oscillations with PROSPECT will test the origin of the spectral deviations observed in recent ${\theta }_{13}$ experiments, search for sterile neutrinos, and conclusively address the hypothesis of sterile neutrinos as an explanation of the reactor anomaly.

We analyze the low-energy nucleon–nucleon (NN) interaction by confronting statistical versus systematic uncertainties. This is carried out with the help of model potentials fitted to the Granada-2013 database where a statistically meaningful partial wave analysis comprising a total of 6713 np and pp published scattering data below 350 MeV from 1950 till 2013 has been made. We extract threshold parameter uncertainties from the coupled-channel effective range expansion up to $j\leqslant 5$. We find that for threshold parameters systematic uncertainties are generally at least an order of magnitude larger than statistical uncertainties. Similar results are found for np phase shifts and amplitude parameters.

The distribution of electric charge in atomic nuclei is fundamental to our understanding of the complex nuclear dynamics and a quintessential observable to validate nuclear structure models.  The aim of this study is to explore a novel approach that combines sophisticated models of nuclear structure with Bayesian neural networks (BNN) to generate predictions for the charge radii of thousands of nuclei throughout the nuclear chart. A class of relativistic energy density functionals is used to provide robust predictions for nuclear charge radii. In turn, these predictions are refined through Bayesian learning for a neural network that is trained using residuals between theoretical predictions and the experimental data. Although predictions obtained with density functional theory provide a fairly good description of experiment, our results show significant improvement (better than 40%) after BNN refinement. Moreover, these improved results for nuclear charge radii are supplemented with theoretical error bars. We have successfully demonstrated the ability of the BNN approach to significantly increase the accuracy of nuclear models in the predictions of nuclear charge radii. However, as many before us, we failed to uncover the underlying physics behind the intriguing behavior of charge radii along the calcium isotopic chain.

In this paper we present the NLO QCD + NLO EW corrections to the ZZZ production with subsequent Z-boson leptonic decays at the LHC by adopting the improved narrow width approximation, which takes into account off-shell contributions and spin correlations. Integrated cross sections at 13, 14, 33 and $100\,\mathrm{TeV}$ hadron colliders and various kinematic distributions are presented. Our numerical results show that the jet emission correction accounts for a large part of the total QCD correction, especially in the high energy region. By applying a proper cut to the jet transverse momentum, e.g., ${p}_{{\rm{T}},{\rm{jet}}}\gt {p}_{{\rm{T}},{\rm{jet}}}^{{\rm{cut}}}=50\,\mathrm{GeV}$, the jet emission correction can be reduced and the cross section is less dependent on the factorization/renormalization scale. This work reveals that both the NLO QCD and the NLO EW corrections are significant. For example, the NLO QCD, NLO EW and NLO QCD + EW relative corrections in the inclusive event selection scheme at the $13\,\mathrm{TeV}$ LHC can reach $63.2 \%$, $-9.6 \%$ and $47.5 \%$, respectively, which means that neither the NLO QCD nor the NLO EW correction is negligible in precision calculations.

The direct detection of dark matter constituents, in particular the weakly interacting massive particles (WIMPs), is considered central to particle physics and cosmology. In this paper we study transitions to the excited states, possible in nuclei which have sufficiently low-lying excited states. Examples considered previously were the first excited states of ¹²⁷I, ¹²⁹Xe and ⁸³Kr. Here, we examine ¹²⁵Te, which offers some advantages and is currently being considered as a target. In all these cases the extra signature of the gamma rays following the de-excitation of these states has definite advantages over the purely nuclear recoil and in principle such a signature can be exploited experimentally. A brief discussion of the experimental feasibility is given in the context of the CUORE experiment.

We present an exploratory study of the ${{\rm{\Lambda }}}_{c,b}\to {N}^{* }$-form factors and the semileptonic decay width within the framework of light-cone sum rules. We use two different methods and two different interpolating currents for the ${{\rm{\Lambda }}}_{c,b}$.

(1) We follow (Khodjamirian et al 2011 J. High Energy Phys.JHEP09(2011)106) and eliminate negative parity partners of the ${{\rm{\Lambda }}}_{c,b}$ by taking linear combinations of different Lorentz-structures.

(2) We extract the form factors by choosing the Lorentz-structures with the highest possible powers of ${p}_{+}$.

As interpolating currents we choose an axial-vector like and a pseudoscalar like current. Our results show that the procedure of eliminating negative parity partners is not well suited for the case at hand and that the second approach with an axial-vector like interpolating current gives the most reliable results. Our predictions are based on the models obtained in (Anikin et al 2015 Phys. Rev. D 92 014018; Braun et al 2014 Phys. Rev. D 89 094511). The largest uncertainty comes from the uncertainty of the twist 4 parameters ${\eta }_{10},{\eta }_{11}$ and we take the spread between the two models in (Anikin et al 2015 Phys. Rev. D 92 014018) as a measure for this. We get$\begin{eqnarray*}\begin{array}{rcl}{\rm{\Gamma }}({{\rm{\Lambda }}}_{b}\to {N}^{* }(1535)l\nu ) & = & ({0.0058}_{-0.0009}^{+0.0010})\times {\left(\displaystyle \frac{{V}_{{ub}}}{3.5\times {10}^{-3}}\right)}^{2},\quad {\rm{LCSR(1)}}\\ {\rm{\Gamma }}({{\rm{\Lambda }}}_{b}\to {N}^{* }(1535)l\nu ) & = & ({0.00070}_{-0.00011}^{+0.00012})\times {\left(\displaystyle \frac{{V}_{{ub}}}{3.5\times {10}^{-3}}\right)}^{2},\quad {\rm{LCSR(2)}}\\ {\rm{\Gamma }}({{\rm{\Lambda }}}_{c}\to {N}^{* }(1535)l\nu ) & = & ({0.0064}_{-0.0011}^{+0.0012})\times {\left(\displaystyle \frac{{V}_{{cd}}}{0.225}\right)}^{2},\quad {\rm{LCSR(1)}}\\ {\rm{\Gamma }}({{\rm{\Lambda }}}_{c}\to {N}^{* }(1535)l\nu ) & = & ({0.00077}_{-0.00014}^{+0.00016})\times {\left(\displaystyle \frac{{V}_{{cd}}}{0.225}\right)}^{2},\quad {\rm{LCSR(2)}}\end{array}\end{eqnarray*}$as predictions for the respective decay widths, where LCSR(1) and LCSR(2) refer to the two different models of the distribution amplitudes of the ${N}^{* }$. It is seen that even a rough measurement of these decays will greatly help to discriminate different models.

We present new constraints on the two Higgs doublet model (THDM) and the leptoquark model parameters using the leptonic and semileptonic decays of the D meson. Our global analysis includes: the leptonic decay of the D_s meson, the semileptonic decays of the D⁰ and ${D}^{+}$ mesons and we have included the spectral distribution of the ${D}^{0}\to {K}^{-}{e}^{+}{\nu }_{e}$ and ${D}^{+}\to {K}^{0}{e}^{+}{\nu }_{e}$ measured by CLEO. We show that D meson decays effectively constrain several variations of the THDM, namely: Type I, Type II, Lepton Specific (LS), Flipped and the aligned model with a Z₂ symmetry while complementing second generation constraints for leptoquark models.

The low-lying electromagnetic dipole strength of the odd-proton nuclide ²⁰⁵Tl has been investigated up to the neutron separation energy exploiting the method of nuclear resonance fluorescence. In total, 61 levels of ²⁰⁵Tl have been identified. The measured strength distribution of ²⁰⁵Tl is discussed and compared to those of even–even and even–odd mass nuclei in the same mass region as well as to calculations that have been performed within the quasi-particle phonon model.

Using mirror symmetry and wave functions for ¹²Be and ¹³B, I have estimated the splitting of strength expected for 0⁺ and 2⁺ final states of ¹²O in neutron removal from ¹³O. Results indicate that most of the peak observed near 2.0 MeV in that reaction corresponds to a 2⁺ state. About 80% of the total 2⁺ strength should reside in a 2⁺ state (or states) near 5 MeV.

A search for double beta decays of ${}^{110}\mathrm{Pd}$ and ${}^{102}\mathrm{Pd}$ into excited states of the daughter nuclides has been performed using three ultra-low background gamma-spectrometry measurements in the Felsenkeller laboratory, Germany, the HADES laboratory, Belgium and at the LNGS, Italy. The combined Bayesian analysis of the three measurements sets improved half-life limits for the 2νββ and 0νββ decay modes of the ${2}_{1}^{+}$, ${0}_{1}^{+}$ and ${2}_{2}^{+}$ transitions in ${}^{110}\mathrm{Pd}$ to $2.9\cdot {10}^{20}$ yr, $4.0\cdot {10}^{20}$ yr and $3.0\cdot {10}^{20}$ yr, respectively, and in ${}^{102}\mathrm{Pd}$ to $7.6\cdot {10}^{18}$ yr, $8.8\cdot {10}^{18}$ yr and $1.4\cdot {10}^{19}$ yr, respectively, with 90% credibility.