Nuclear Theory·nucl-th

Monday·October 30, 2023

9 papers—5 primary·4 cross-listed

01
Ab initio no-core shell-model study of $^{20 - 23}$ Na isotopes
Chandan Sarma · Praveen C. Srivastava
We have done a systematic no-core shell-model study of $^{20 - 23}$ Na isotopes. The low-energy spectra of these sodium isotopes consisting of natural and un-natural parity states were reported, considering three realistic interactions: inside nonlocal outside Yukawa (INOY), charge-dependent Bonn 2000 (CDB2K), and the chiral next-to-next-to-next-to-leading order (N $^{3}$ LO). We also present the mirror energy differences in the low-energy spectra of $∣ T_{z} ∣$ = 1/2 mirror pair ( $^{21}$ Na - $^{21}$ Ne). Apart from the energy spectra, we have also reported the electromagnetic transition strengths and moments. Finally, considering all three realistic interactions, we report the point-proton radii and neutron skin thicknesses.
nucl-thnucl-exFew Body Syst.(2025)·6 citations
02
Nuclear chiral rotation within Relativistic Configuration-interaction Density functional theory
Yakun Wang · Pengwei Zhao · Jie Meng
The Relativistic Configuration-interaction Density functional (ReCD) theory that combines the advantages of large-scale configuration-interaction shell model and relativistic density functional theory is extended to study nuclear chiral rotation. The energy spectra and transition probabilities of the chiral doublet bands are reproduced satisfactorily without any free parameters. By analyzing the probability amplitudes of the wavefunctions, the significant roles of configuration mixing and four quasiparticle states to the chiral doublets are revealed. The evolution from chiral vibration to static chirality are clearly illustrated by the K plot and azimuthal plot. The present investigation provides both microscopic and quantal descriptions for nuclear chirality for the first time and demonstrates the robustness of chiral geometry against the configuration mixing as well as the four quasiparticle states.
nucl-thPLB(2024)·19 citations
03
Location and symmetry of superconductivity in neutron stars
Dmitry Kobyakov
Earlier, it was a standard assumption that the entire core of neutron stars is superconducting. However, the matter contents in the inner core has been unknown even qualitatively, because the density of matter in that region is expected to be higher than the nuclear saturation density 0.16 $fm^{- 3}$ . As a consequence, no reliable model exists that would describe the neutron star matter in the inner core of neutron stars. Thus, a possibility of presence of normal, nonsuperconducting, plasma in the inner core cannot be excluded as of today. This point is supported by the numerical calculations performed in [1]. The calculations are based on the equation of state and the proton Cooper pairing gap energy derived from the chiral effective field theory. The numerical results show that the superconducting gap goes to zero beyond the depth about 1 km below the crust-core boundary. Given that the stellar radius is of the order of 12 km, therefore the superconducting proton matter is expected to exist only in a thin layer at the tip of the outer core. Recently it has been realized that the symmetry of superconductor is anisotropic in the lasagna region of the pasta phases located at the bottom of the crust. However the question of whether this symmetry is continuous or discreet was unsolved. The numerical calculations performed in [1] have shown that the tunneling rate between the adjacent slabs in the entire range of the corresponding densities is negligibly small. Thus, a discreet model is necessary for the description of the lasagna region. Uncertainties and future directions of the research are discussed.
nucl-thastro-ph.HE0 citations
04
Towards a more complete description of nucleon distortion in lepton-induced single-pion production at low- $Q^{2}$
J. García-Marcos🇪🇸 · T. Franco-Munoz🇪🇸 · R. González-Jiménez🇪🇸 · A. Nikolakopoulos🇺🇸 · N. Jachowicz🇧🇪 · J.M. Udías🇪🇸
Theoretical predictions for lepton-induced single-pion production (SPP) on $^{12}$ C are revisited in order to assess the effect of different treatments of the current operator. On one hand we have the asymptotic approximation, which consists in replacing the particle four-vectors that enter in the operator by their asymptotic values, i.e., their values out of the nucleus. On the other hand we have the full calculation, which is a more accurate approach to the problem. We also compare with results in which the final nucleon is described by a relativistic plane wave, to rate the effect of the nucleon distortion. The study is performed for several lepton kinematics, reproducing inclusive and semi-inclusive cross sections belonging to the low- $Q^{2}$ region (between 0.05 and 1 GeV $^{2}$ ), which is of special interest in charged-current (CC) neutrino-nucleus 1 $π$ production. Inclusive electron results are compared with experimental data. We find non-trivial corrections comparable in size with the effect of the nucleon distortion, namely, corrections up to 6\%, either increasing or diminishing the asymptotic prediction, and a shift of the distributions towards higher energy transfer. For the semi-inclusive cross sections, we observe the correction to be prominent mainly at low values of the outgoing nucleon kinetic energy. Finally, for CC neutrino-induced 1 $π^{+}$ production, we find a reduction at low- $Q^{2}$ with respect to both the plane-wave approach and the asymptotic case.
nucl-thhep-phPRC(2024)·7 citations
05
Photon momentum anisotropies from the late stages of relativistic heavy-ion collisions
Hannah Elfner🇩🇪 · Niklas Götz🇩🇪 · Oscar Garcia-Montero🇩🇪 · Jean-Francois Paquet🇺🇸 · Charles Gale🇨🇦
The photon emission from the late stages of the dynamical evolution of heavy-ion reactions at the highest RHIC and LHC energies is investigated. A comparison between a calculation from hadronic rates from a fluid dynamic evolution down to temperatures of 120 MeV and a full non-equilibrium hadronic transport approach is performed. The photon yields are very similar in both cases while the elliptic flow is slightly smaller in the non-equilibrium scenario. This study is important, since it is crucial to apply the same dynamical evolution model for hadronic and electromagnetic observables.
nucl-thnucl-exPoS(2024)·0 citations
06
Improved Standard-Model prediction for $K_{L} \to ℓ^{+} ℓ^{-}$
Martin Hoferichter🇨🇭 · Bai-Long Hoid🇨🇭 · Jacobo Ruiz de Elvira🇪🇸
We present a comprehensive calculation of the $K_{L} \to γ^{*} γ^{*}$ form factor in dispersion theory, using input from the leptonic decays $K_{L} \to ℓ^{+} ℓ^{-} γ$ , $K_{L} \to ℓ_{1}^{+} ℓ_{1}^{-} ℓ_{2}^{+} ℓ_{2}^{-}$ , the hadronic mode $K_{L} \to π^{+} π^{-} γ$ , the normalization $K_{L} \to γ γ$ , and the matching to asymptotic constraints. As key result we obtain an improved determination of the long-distance contribution to $K_{L} \to ℓ^{+} ℓ^{-}$ , leading to the Standard-Model predictions $Br [K_{L} \to μ^{+} μ^{-}] = 7.4 4_{- 0.34}^{+ 0.41} \times 1 0^{- 9}$ , $Br [K_{L} \to e^{+} e^{-}] = 8.46 (37) \times 1 0^{- 12}$ , and more stringent limits on physics beyond the Standard Model. We provide a detailed breakdown of the current uncertainty, and delineate how future experiments and the interplay with lattice QCD could help further improve the precision.
↳ hep-phhep-exhep-latnucl-thJHEP(2024)·21 citations
07
Quark stars in $D_{3}$ - $D_{7}$ holographic model
M. Aleixo🇧🇷 · C.H. Lenzi🇧🇷 · W. de Paula🇧🇷 · R. da Rocha🇧🇷
This work investigates static and dynamical quark star properties within a $D_{3} - D_{7}$ holographic model. We solve the Tolman-Oppenheimer-Volkoff equations for the quark matter equation of state obtained from the brane configuration. We determine the mass-radius diagram for a range of model parameters and compare with recent NICER observational data for the pulsars PSR J $0030 + 0451$ and PSR J $0740 + 6620$ . Motivated by the GW170817 event detected by the LIGO-Virgo collaboration, we also calculate the tidal deformability parameter obtained for each component of the binary star system. We show that quark stars composed of flavor-independent quark matter derived from the $D_{3} - D_{7}$ holographic model are not able to satisfy simultaneously the LIGO-Virgo and NICER astrophysical bounds.
↳ hep-phastro-ph.HEnucl-thEPJC(2024)·5 citations
08
Symmetry breaking and restoration for many-body problems treated on quantum computers
Andres Ruiz🇫🇷
This thesis explores the application of the Symmetry-Breaking/Symmetry-Restoration methodology on quantum computers to better approximate a Hamiltonian's ground state energy within a variational framework in many-body physics. This involves intentionally breaking and restoring the symmetries of the wave function ansatz at different stages of the variational search for the ground state. The Variational Quantum Eigensolver (VQE) is utilized for the variational component together with an ansatz inspired by the Bardeen-Cooper-Schrieffer (BCS) theory. The applications were demonstrated using the pairing and Hubbard Hamiltonians. Two approaches were identified with the VQE method: varying the symmetry-breaking ansatz parameters before or after symmetry restoration, termed Quantum Projection After Variation and Quantum Variation After Projection, respectively. The main contribution of this thesis was the development of a variety of symmetry restoration techniques based on the principles of the Quantum Phase Estimation algorithm, the notion of a Quantum "Oracle," and the Classical Shadow formalism. In the final part, hybrid quantum-classical techniques were introduced to extract an approximation of the low-lying spectrum of a Hamiltonian. Assuming accurate Hamiltonian moment extraction from their generating function with a quantum computer, two methods were presented for spectral analysis: the t-expansion method and the Krylov method, which provides, in particular, information about the evolution of the survival probability. Furthermore, the Quantum Krylov method was introduced, offering similar insights without the need to estimate Hamiltonian moments, a task that can be difficult on near-term quantum computers.
↳ quant-phcond-mat.str-elnucl-th0 citations
09
Mass gaps of a $Z_{3}$ gauge theory with three fermion flavors in 1 + 1 dimensions
Adrien Florio🇺🇸 · Andreas Weichselbaum🇺🇸 · Semeon Valgushev🇺🇸 · Robert D. Pisarski🇺🇸
We consider a $Z_{3}$ gauge theory coupled to three degenerate massive flavors of fermions, which we term "QZD". The spectrum can be computed in $1 + 1$ dimensions using tensor networks. In weak coupling the spectrum is that of the expected mesons and baryons, although the corrections in weak coupling are nontrivial, analogous to those of non-relativistic QED in 1+1 dimensions. In strong coupling, besides the usual baryon, the singlet meson is a baryon anti-baryon state. For two special values of the coupling constant, the lightest baryon is degenerate with the lightest octet meson, and the lightest singlet meson, respectively.
↳ hep-thcond-mat.str-elhep-lathep-ph+1PRD(2024)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE