Nuclear Theory·nucl-th

Friday·October 28, 2022

11 papers—6 primary·5 cross-listed

01
Ab initio no-core shell model study of neutron-rich $^{18, 19, 20}$ C isotopes
Priyanka Choudhary · Praveen C. Srivastava
We implement the ab initio no-core shell model approach to study neutron-rich $^{18}$ C, $^{19}$ C and $^{20}$ C isotopes. For this purpose, we employ charge-dependent Bonn 2000 (CDB2K), inside non-local outside Yukawa (INOY) and chiral next-to-next-to-next-to-leading order (N $^{3}$ LO) nucleon-nucleon interactions. Low-lying energy spectra, electromagnetic properties and point-proton radii for these nuclei up to basis space $N_{max}$ = 4 are calculated. Binding energies obtained with INOY interaction are in better agreement with the experimental values as compared to other \textit{ab initio} interactions. We also show the behavior of ground state energy and point-proton radii with the NCSM parameters, $ℏ$ $Ω$ and $N_{max}$ . We report a strong sensitivity of the B(E2) values from the first excited $2^{+}$ to the ground state of $^{18}$ C and $^{20}$ C to the nuclear interaction. Shell model calculations with YSOX interaction are also performed, and corresponding results are compared with ab initio one.
nucl-thNPA(2023)·9 citations
02
Nuclear Matter and Neutron Stars from Relativistic Brueckner-Hartree-Fock Theory
Hui Tong · Chencan Wang · Sibo Wang
The momentum and isospin dependence of the single-particle potential for the in-medium nucleon are the key quantities in the Relativistic Brueckner-Hartree-Fock (RBHF) theory. It depends on how to extract the scalar and the vector components of the single-particle potential inside nuclear matter. In contrast to the RBHF calculations in the Dirac space with the positive-energy states (PESs) only, the single-particle potential can be determined in a unique way by the RBHF theory together with the negative-energy states (NESs), i.e., the RBHF theory in the full Dirac space. The saturation properties of symmetric and asymmetric nuclear matter in the full Dirac space are systematically investigated based on the realistic Bonn nucleon-nucleon potentials. In order to further specify the importance of the calculations in the full Dirac space, the neutron star properties are investigated. The direct URCA process in neutron star cooling will happen at density $ρ_{DURCA} = 0.43, 0.48, 0.52$ fm $^{- 3}$ with the proton fractions $Y_{p, DURCA} = 0.13$ . The radii of a $1.4 M_{⊙}$ neutron star are predicated as $R_{1.4 M_{⊙}} = 11.97, 12.13, 12.27$ km, and their tidal deformabilities are $Λ_{1.4 M_{⊙}} = 376, 405, 433$ for potential Bonn A, B, C. Comparing with the results obtained in the Dirac space with PESs only, full-Dirac-space RBHF calculation predicts the softest symmetry energy which would be more favored by the gravitational waves (GW) detection from GW170817. Furthermore, the results from full-Dirac-space RBHF theory are consistent with the recent astronomical observations of massive neutron stars and simultaneous mass-radius measurement.
nucl-thApJ(2022)·27 citations
03
Properties of the diffusion and drift kinetic coefficients in momentum space for a cold Fermi system
Sergiy V. Lukyanov
Using the methods of kinetic theory expressions for the diffusion and drift coefficients for a cold Fermi system are obtained. Their dependences on the momentum are calculated for the step distribution function as well as in the case of excitation of a particle-hole pair.
nucl-thNucl.Phys.Atom.Energy(2023)·4 citations
04
Light nuclei production in pp and pA collisions in the Baryon Canonical Ensemble
Natasha Sharma🇮🇳 · Lokesh Kumar🇮🇳 · Pok Man Lo🇵🇱 · Krzysztof Redlich🇵🇱
The increase in yields of light nuclei with charged particle multiplicity, as reported by the ALICE collaboration at CERN in p-p and p-Pb collisions at the LHC energy is investigated in the thermal hadron resonance gas model. The model is extended to account for exact baryon number conservation. The focus is on the production of protons, deuterons, $^{3}$ He, and $_{Λ}^{3}$ H. A very good description of proton and deuteron yields is obtained as a function of charged particle multiplicity in the mid-rapidity region using the same fixed temperature as in central Pb-Pb collisions. The yields of light nuclei $^{3}$ He and $_{Λ}^{3}$ H though qualitatively explained as a function of multiplicity, are lower than the model expectation. One of the possible reasons could be that for $^{3}$ He and $_{Λ}^{3}$ H, the chemical equilibrium is not yet reached at small multiplicities.
nucl-thhep-phPRC(2023)·9 citations
05
Centrality dependence of proton and light nuclei yields as a consequence of baryon annihilation in the hadronic phase
Volodymyr Vovchenko🇺🇸 · Volker Koch🇺🇸
The centrality dependence of the $p / π$ ratio measured by the ALICE Collaboration in 5.02 TeV Pb-Pb collisions indicates a statistically significant suppression with the increase of the charged particle multiplicity once the centrality-correlated part of the systematic uncertainty is eliminated from the data. We argue that this behavior can be attributed to baryon annihilation in the hadronic phase. By implementing the $B B ˉ \leftrightarrow 5 π$ reaction within a generalized partial chemical equilibrium framework, we estimate the annihilation freeze-out temperature at different centralities, which decreases with increasing charged multiplicity and yields $T_{ann} = 132 \pm 5$ MeV in 0-5% most central collisions. This value is considerably below the hadronization temperature of $T_{had} \sim 160$ MeV but above the thermal (kinetic) freeze-out temperature of $T_{kin} \sim 100$ MeV. Baryon annihilation reactions thus remain relevant in the initial stage of the hadronic phase but freeze out before (pseudo-)elastic hadronic scatterings. One experimentally testable consequence of this picture is a suppression of various light nuclei to proton ratios in central collisions of heavy ions.
nucl-thhep-phnucl-exPLB(2022)·16 citations
06
Cold Neutron-Deuteron Capture and Wigner-SU(4) Symmetry
Xincheng Lin🇺🇸 · Hersh Singh🇺🇸 · Roxanne P. Springer🇺🇸 · Jared Vanasse🇺🇸
We calculate the cold neutron-deuteron ( $n d$ ) capture cross section, $σ_{n d}$ , to next-to-next-to leading order (NNLO) using the model-independent approach of pionless effective field theory (EFT( $π /$ )). At leading order we find $σ_{n d} = 0.315 \pm 0.217$ mb, while the experimental result is 0.508(15) mb [Jurney, Bendt and Browne in Phys. Rev. C 25, 2810 (1982)] for a laboratory neutron velocity of 2200 m/s. At next-to-leading-order (NLO), we show that $σ_{n d}$ is sensitive to the low energy constant (LEC), $L_{1}^{(0)}$ , of the two-nucleon isovector current appearing at NLO. A fit of $L_{1}^{(0)}$ at NLO to the triton magnetic moment yields a NLO prediction of $σ_{n d} = 0.393 \pm 0.164$ mb, where the error comes from propagating the error from the $L_{1}^{(0)}$ fit. At next-to-next-to-leading-order (NNLO), we find that a new three-nucleon magnetic moment counterterm is required for renormalization group invariance of both $σ_{n d}$ and the triton magnetic moment. Fitting the NNLO correction to $L_{1}^{(0)}$ (denoted $L_{1}^{(1)}$ ) to cold neutron-proton capture ( $σ_{n p}$ ) yields a NNLO prediction of $σ_{n d} = 0.447 \pm 0.130$ mb, where the error comes from propagating the error from the $L_{1}^{(1)}$ fit. We also study different fittings of $L_{1}^{(0)}$ and $L_{1}^{(1)}$ to $σ_{n p}$ , $σ_{n d}$ , and/or the triton magnetic moment. For example, fitting $L_{1}^{(0)}$ simultaneously to $σ_{n p}$ , $σ_{n d}$ , and the triton magnetic moment at NLO, and fitting $L_{1}^{(1)}$ simultaneously to $σ_{n p}$ and $σ_{n d}$ at NNLO, yields $σ_{n d} = 0.480 \pm 0.114$ mb and $0.511 \pm 0.042$ mb, respectively, where errors are naively estimated from EFT( $π /$ ) power counting. In addition, we discuss how Wigner-SU(4) symmetry may alter the naive EFT( $π /$ ) expansion of $σ_{n d}$ .
nucl-thPRC(2023)·10 citations
07
$C P$ violation in $η^{(')} \to π^{+} π^{-} μ^{+} μ^{-}$ decays
Maximilian Zillinger🇩🇪 · Bastian Kubis🇩🇪 · Pablo Sánchez-Puertas🇪🇸
It has been pointed out recently that a certain set of dimension-6 scalar $P$ - and $C P$ -violating light-quark-muon operators may be tested in $η$ and $η^{'}$ decays to various final states involving $μ^{+} μ^{-}$ pairs, at a level not yet excluded by constraints from electric dipole moments. We here work out the hadronic matrix elements required for the predictions for the decays $η, η^{'} \to π^{+} π^{-} μ^{+} μ^{-}$ . We relate a new asymmetry in the angular distribution between the dipion and dimuon decay planes to the corresponding Wilson coefficients. Despite the advantage of not requiring the measurement of muon polarization, the projected sensitivities are shown to be moderate due to a combination of small phase space and chiral suppression. Such sensitivity studies are most timely in view of upcoming or planned high-statistics $η^{(')}$ experiments such as the JLab eta factory or REDTOP.
↳ hep-phhep-exnucl-thJHEP(2022)·13 citations
08
Flow of charge and heat in thermal QCD within the weak magnetic field limit: A BGK model approach
Anowar Shaikh🇮🇳 · Shubhalaxmi Rath🇮🇳 · Sadhana Dash🇮🇳 · Binata Panda🇮🇳
We have computed the charge and heat transport coefficients of hot QCD matter by solving the relativistic Boltzmann transport equation using the BGK model approximation with a modified collision integral in the weak magnetic field regime. This modified collision integral enhances both charge and heat transport phenomena which can be understood by the large values of the above-mentioned coefficients in comparison to the relaxation collision integral. We have also presented a comparative study of coefficients like the electrical conductivity ( $σ_{e l}$ ), Hall conductivity ( $σ_{H}$ ), thermal conductivity ( $κ$ ) and Hall-type thermal conductivity( $κ_{H}$ ) in weak and strong magnetic fields in the BGK model approximation. The effects of weak magnetic field and finite chemical potential on the transport coefficients have been explored using a quasiparticle model. Moreover, we have also studied the effects of weak magnetic field and finite chemical potential on Lorenz number, Knudsen number, specific heat, elliptic flow and Wiedemann-Franz law.
↳ hep-phhep-thnucl-thPRD(2023)·11 citations
09
Cumulants from short-range correlations and baryon number conservation - next-to-leading order
Michał Barej🇵🇱 · Adam Bzdak🇵🇱
We calculate the baryon number cumulants within acceptance with short-range correlations and global baryon number conservation in terms of cumulants in the whole system without baryon conservation. We extract leading and next-to-leading order terms of the large baryon number limit approximation. Our results extend the findings of Refs. [1,2]. These approximations are checked to be very close to the exact results.
↳ hep-phhep-exnucl-exnucl-thPRC(2023)·5 citations
10
Thermodynamic properties of non-Hermitian Nambu--Jona-Lasinio models
Alexander Felski🇩🇪 · Alireza Beygi🇩🇪 · S. P. Klevansky🇩🇪
We investigate the impact of non-Hermiticity on the thermodynamic properties of interacting fermions by examining bilinear extensions to the $3 + 1$ dimensional $S U (2)$ -symmetric Nambu--Jona-Lasinio (NJL) model of quantum chromodynamics at finite temperature and chemical potential. The system is modified through the anti- $P T$ -symmetric pseudoscalar bilinear $ψ ˉ γ_{5} ψ$ and the $P T$ -symmetric pseudovector bilinear $i B_{ν} ψ ˉ γ_{5} γ^{ν} ψ$ , introduced with a coupling $g$ . Beyond the possibility of dynamical fermion mass generation at finite temperature and chemical potential, our findings establish model-dependent changes in the position of the chiral phase transition and the critical end-point. These are tunable with respect to $g$ in the former case, and both $g$ and $∣ B ∣/ B_{0}$ in the latter case, for both lightlike and spacelike fields. Moreover, the behavior of the quark number, entropy, pressure, and energy densities signal a potential fermion or antifermion excess compared to the standard NJL model, due to the pseudoscalar and pseudovector extension respectively. In both cases regions with negative interaction measure $I = ϵ - 3 p$ are found. Future indications of such behaviors in strongly interacting fermion systems, for example in the context of neutron star physics, may point toward the presence of non-Hermitian contributions. These trends provide a first indication of curious potential mechanisms for producing non-Hermitian baryon asymmetry. In addition, the formalism described in this study is expected to apply more generally to other Hamiltonians with four-fermion interactions and thus the effects of the non-Hermitian bilinears are likely to be generic.
↳ hep-phhep-thnucl-thPRD(2023)·4 citations
11
Twin stars as probes of the nuclear equation of state: effects of rotation through the PSR J0952-0607 pulsar and constraints via the tidal deformability from the GW170817 event
Lazaros Tsaloukidis🇩🇪 · P.S. Koliogiannis🇬🇷 · A. Kanakis-Pegios🇬🇷 · Ch.C. Moustakidis🇬🇷
In agreement with the constantly increasing gravitational wave events, new aspects of the internal structure of compact stars can be considered. A scenario in which a first order transition takes place inside these stars is of particular interest as it can lead, under conditions, to a third gravitationally stable branch (besides white dwarfs and neutron stars), the twin stars. The new branch yields stars with the same mass as normal compact stars but quite different radii. In the present work, we focus on hybrid stars undergone a hadron to quark phase transition near their core and how this new stable configuration arises. Emphasis is to be given on the aspects of the phase transition and its parametrization in two different ways, namely with Maxwell and Gibbs construction. We systematically study the gravitational mass, the radius, and the tidal deformability, and we compare them with the predictions of the recent observation by LIGO/VIRGO collaboration, the GW170817 event, along with the mass and radius limits, suggesting possible robust constraints. Moreover, we extent the study in order to include rotation effects on the twin stars configurations. The recent discovery of the fast rotating supermassive pulsar PSR J0952-0607 triggered the effort to constrain the equation of state and moreover to examine possible predictions related to the phase transition in dense nuclear matter. We pay special attention to relate the PSR J0952-0607 pulsar properties with the twin stars predictions and mainly to explore the possibility that the existence of such a massive object would rule out the existence of twin stars. Finally, we discuss the constraints on the radius and mass of the recently observed compact object within the supernova remnant HESS J1731-347. The estimations implies that this object is either the lightest neutron star known, or a star with a more exotic equation of state.
↳ astro-ph.HEnucl-thPRD(2023)·48 citations

Affiliations

first authorsco-authorsvia INSPIRE