Nuclear Theory·nucl-th

Friday·December 15, 2023

15 papers—6 primary·9 cross-listed

01
Pseudo-neutrino versus recoil formalism for 4-body phase space and applications to nuclear decay
Chien-Yeah Seng🇺🇸
It is well-known that the traditional treatment of radiative corrections that utilizes the "true" neutrino momentum $p_{ν}$ in the differential decay rate formula could lead to a $\sim α / π$ systematic error in certain observables due to the mistreatment of 4-body kinematics. We investigate the theory structure of one of the proposed solutions, the " $ν^{'}$ -formalism", in the non-recoil limit appropriate for neutron and nuclear beta decays. We derive an elegant master formula for the 4-body phase space and use it to re-analyze the spectrum-dependent "outer" radiative corrections to the beta decay of a polarized spin-half nucleus; a complete set of analytic expressions is provided for readers to straightforwardly obtain the final numerical results. We compare it to the "recoil formalism" where the energy of the recoil nucleus is fixed.
nucl-thhep-exhep-phnucl-exPRC(2024)·8 citations
02
Direct solution of Minkowski-space Bethe-Salpeter equation in the massive Wick-Cutkosky model
Shaoyang Jia🇺🇸
In order to solve the Bethe-Salpeter equation (BSE) in the Minkowski space, we first introduce the Nakanishi integral representations of the Bethe-Salpeter amplitude (BSA) and the Bethe-Salpeter wave function (BSWF). We then derive the explicit integral equations for the corresponding spectral functions from the BSE for states of $2$ scalar particles bound by a scalar-particle exchange interaction, where the propagators of constituents are allowed to be fully dressed. These integral equations are subsequently solved numerically in the variation of the Wick-Cutkosky model with massive exchange particles, where an algorithm of adaptive mash grid is proposed. The equations and algorithm we develop here serve as the foundation of Minkowski-space formulation of BSE for bound states of fermions.
nucl-thhep-thPRD(2024)·4 citations
03
Effects of phase transition in hybrid stars from quark-meson coupling hadronic matter to deconfined quark matter
Yida Yang🇨🇳 · Chen Wu🇨🇳 · Ji-Feng Yang🇨🇳
Different types of phase transition from hadron to quark at high density near zero temperature may occur in the inner core of hybrid stars. We investigate the impacts of phase transition types and quark models on properties of hybrid star and quark cores. The quark-meson coupling (QMC) model is used to describe hadronic matter, and the MIT bag model as well as the Nambu-Jona-Lasinio (NJL) model are employed to describe quark matter for comparison. From the mass-radius curves obtained by using equations of state (EOS), we find that EOSs of hadron matter have a decisive influence on the maximum mass of a hybrid star in the first-order phase transition case, while quark matter EOSs have more impacts on results in the crossover transition case. It is also found in the present work that the thermodynamic correction arising from an interpolation scheme considerably stiffens the EOSs. Therefore the crossover type phase transition generally leads to hybrid stars with higher masses. In particular, by using the QMC model and the NJL model to construct crossover EOSs with thermodynamic correction, we discover that the maximum masses of hybrid stars can meet the recent observational constraint on mass from PSR J0952-0607, i.e., $2.35 \pm 0.17 M_{⊙}$ .
nucl-thPRD(2024)·5 citations
04
Fate of the $ρ$ - $a_{1}$ mixing in dilepton production
Azumi Sakai🇯🇵 · Masayasu Harada🇯🇵 · Chiho Nonaka🇯🇵 · Chihiro Sasaki🇵🇱 · Kenta Shigaki🇯🇵 · Satoshi Yano🇯🇵
We investigate the effect of chiral mixing on dilepton production by combining the in-medium spectral function in the chiral effective field theory with the state-of-the-art fluid dynamical simulations. We compare the spectral functions with different chiral symmetry restoration scenarios. We find that the scenario with proper chiral symmetry restoration that takes into account the degenerate $ρ$ and $a_{1}$ mesons leads to an increase of the yield in the window of $1.1 < M < 1.4$ GeV. Whereas, the low-temperature theorem of chiral mixing extrapolated toward a chiral crossover, often used in the literature, leads to a substantial overestimate at $M = 1.2$ GeV.
nucl-thhep-phnucl-exEPJ Web Conf.(2024)·3 citations
05
Global and local polarization of $Λ$ hyperons across RHIC-BES energies
Xiang-Yu Wu🇨🇳 · Cong Yi🇨🇳 · Guang-You Qin🇨🇳 · Shi Pu🇨🇳
We report our recent study on the global and local polarization of $Λ$ hyperons in Au+Au collisions at RHIC-BES energies within the (3+1)-dimensional CLVisc hydrodynamics framework. We present our numerical results for the global polarization as the function of collision energies and the local polarization along the beam direction as functions of azimuthal angle in $20 - 50$ % centrality at $s_{N N}$ =7.7 GeV Au+Au collision energy. We have discussed the effects of initial conditions, Spin Hall effect and baryon diffusion.
nucl-thhep-exhep-phnucl-exEPJ Web Conf.(2024)·3 citations
06
Exploring the freeze-out hypersurface of relativistic nuclear collisions with a rapidity-dependent thermal model
Han Gao🇨🇦 · Lipei Du🇨🇦 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
Considering applications to relativistic heavy-ion collisions, we develop a rapidity-dependent thermal model that includes thermal smearing effect and longitudinal boost. We calibrate the model with thermal yields obtained from a multistage hydrodynamic simulation. Through Bayesian analysis, we find that our model extracts freeze-out thermodynamics with better precision than rapidity-independent models. The potential of such a model to constrain longitudinal flow from data is also demonstrated.
nucl-thhep-phnucl-exEPJ Web Conf.(2024)·1 citation
07
Electron and Muon Dynamics in Neutron Stars Beyond Chemical Equilibrium
Joachim Kopp (CERN and JGU Mainz)🇨🇭 · Toby Opferkuch (UC Berkeley and LBL)🇺🇸
A neutron star harbors of order $1 0^{56}$ electrons in its core, and almost the same number of muons, with muon decay prohibited by Pauli blocking. However, as macroscopic properties of the star such as its mass, rotational velocity, or magnetic field evolve over time, the equilibrium lepton abundances (dictated by the weak interactions) change as well. Scenarios where this can happen include spin-down, accretion, magnetic field decay, and tidal deformation. We discuss the mechanisms by which a star disrupted in one of these ways re-establishes lepton chemical equilibrium. In most cases, the dominant processes are out-of-equilibrium Urca reactions, the rates of which we compute for the first time. If, however, the equilibrium muon abundance decreases, while the equilibrium electron abundance increases (or decreases less than the equilibrium muon abundance), outward diffusion of muons plays a crucial role as well. This is true in particular for stars older than about 10,000 yrs whose core has cooled to $≲ 20$ keV. The muons decay in a region where Pauli blocking is lifted, and we argue that these decays lead to a flux of $O$ (10 MeV) neutrinos. Realistically, however, this flux will remain undetectable for the foreseeable future.
↳ astro-ph.HEhep-phnucl-thJCAP(2024)·1 citation
08
Temporal Entanglement Entropy as a probe of Renormalization Group Flow
Sebastian Grieninger🇺🇸 · Kazuki Ikeda🇺🇸 · Dmitri E. Kharzeev🇺🇸
The recently introduced concept of timelike entanglement entropy has sparked a lot of interest. Unlike the traditional spacelike entanglement entropy, timelike entanglement entropy involves tracing over a timelike subsystem. In this work, we propose an extension of timelike entanglement entropy to Euclidean space ("temporal entanglement entropy"), and relate it to the renormalization group (RG) flow. Specifically, we show that tracing over a period of Euclidean time corresponds to coarse-graining the system and can be connected to momentum space entanglement. We employ Holography, a framework naturally embedding RG flow, to illustrate our proposal. Within cutoff holography, we establish a direct link between the UV cutoff and the smallest resolvable time interval within the effective theory through the irrelevant $T T ˉ$ deformation. Increasing the UV cutoff results in an enhanced capability to resolve finer time intervals, while reducing it has the opposite effect. Moreover, we show that tracing over a larger Euclidean time interval is formally equivalent to integrating out more UV degrees of freedom (or lowering the temperature). As an application, we point out that the temporal entanglement entropy can detect the critical Lifshitz exponent $z$ in non-relativistic theories which is not accessible from spatial entanglement at zero temperature and density.
↳ hep-thgr-qchep-phnucl-thJHEP(2024)·34 citations
09
The mass and spectral function of scalar and pseudoscalar mesons in a hot and chirally imbalanced medium using the two-flavor NJL model
Snigdha Ghosh🇮🇳 · Nilanjan Chaudhuri🇮🇳 · Sourav Sarkar🇮🇳 · Pradip Roy🇮🇳
We explore the properties of neutral mesons within the context of a chirally imbalanced medium, employing the two-flavor Nambu--Jona-Lasinio model. The temperature dependence of the constituent quark mass at finite values of the chiral chemical potential (CCP) demonstrates the well-established phenomena of chiral catalysis at lower temperatures and inverse chiral catalysis at higher temperatures. The polarization functions in both the scalar ( $σ$ ) and pseudo-scalar ( $π^{0}$ ) channels have been evaluated using real time formalism of thermal field theory. These have been used to determine the masses and spectral functions of $σ$ and $π$ mesons. Detailed investigation of the analytic structure of the imaginary part of the polarization function for $σ$ and $π$ mesons results in the emergence of non-trivial Landau cut contributions due to the presence of chiral imbalance. The multiple solutions for the mass of the $π$ meson for specific values of CCP have been analysed on the basis of their residue at the pole. Furthermore, we have observed abrupt changes in the masses of both scalar and pseudo-scalar mesons at finite CCP values, particularly at higher temperatures. A decreasing trend in the Mott transition temperature is seen with the increase in CCP.
↳ hep-phnucl-thPRD(2024)·7 citations
10
Analysis of $T_{cc}$ and $T_{bb}$ based on the hadronic molecular model and their spin multiplets
Manato Sakai🇯🇵 · Yasuhiro Yamaguchi🇯🇵
$T_{cc} (cc u ˉ d ˉ)^{+}$ has been reported by the LHCb experiment in 2022. The analysis using the Breit-Wigner parametrization found the small binding energy, $0.273$ MeV, which is measured from the threshold of $D^{*+} D^{0}$ . In this paper, we consider $T_{cc}$ as a $D D^{*}$ hadronic molecule as a deuteron-like state. The one boson exchange model is employed as for the heavy meson interactions, where we determine the cut-off parameter $Λ$ to reproduce the reported binding energy of $T_{cc}$ with $I (J^{P}) = 0 (1^{+})$ . We discuss the properties of the bound state, and also search for $T_{cc}$ with the quantum numbers other than $0 (1^{+})$ . Futhermore, we analyze $T_{bb}$ as a bottom counterpart of $T_{cc}$ , which involves two bottom quarks, and obtain several bound states. Finally we consider the light-cloud basis for wave functions of the doubly heavy tetraquarks in the heavy quark limit. Using the basis, we find the spin multiplets of their bound states, indicating the spin structures of diquarks in $T_{cc}$ and $T_{bb}$ with the finite quark masses.
↳ hep-phnucl-thPRD(2024)·28 citations
11
The proton magnetic radius: a new puzzle?
Yong-Hui Lin🇩🇪 · Hans-Werner Hammer🇩🇪 · Ulf-G. Meißner🇩🇪
We comment on the puzzling status of the proton magnetic radius determinations.
↳ hep-phhep-exhep-latnucl-ex+1Sci.Bull.(2024)·8 citations
12
Baryon electric charge correlation as a magnetometer of QCD
Heng-Tong Ding🇨🇳 · Jin-Biao Gu🇨🇳 · Arpith Kumar🇨🇳 · Sheng-Tai Li🇨🇳 · Jun-Hong Liu🇨🇳
The correlation between net baryon number and electric charge, $χ_{11}^{BQ}$ , can serve as a magnetometer of QCD. This is demonstrated by lattice QCD computations using the highly improved staggered quarks with physical pion mass of $M_{π} = 135$ MeV on $N_{τ} = 8$ and 12 lattices. We find that $χ_{11}^{BQ}$ along the transition line starts to increase rapidly with magnetic field strength $e B ≳ 2 M_{π}^{2}$ and by a factor 2 at $e B ≃ 8 M_{π}^{2}$ . Furthermore, the ratio of electric charge chemical potential to baryon chemical potential, $μ_{Q} / μ_{B}$ , shows significant dependence on the magnetic field strength and varies from the ratio of electric charge to baryon number in the colliding nuclei in heavy ion collisions. These results can provide baselines for effective theory and model studies, and both $χ_{11}^{BQ}$ and $μ_{Q} / μ_{B}$ could be useful probes for the detection of magnetic fields in relativistic heavy ion collision experiments as compared with corresponding results from the hadron resonance gas model.
↳ hep-lathep-phnucl-exnucl-thPRL(2024)·39 citations
13
Adiabatic Hydrodynamization: a Natural Framework to Find and Describe Prehydrodynamic Attractors
Krishna Rajagopal🇺🇸 · Bruno Scheihing-Hitschfeld🇺🇸 · Rachel Steinhorst🇺🇸
The adiabatic hydrodynamization framework is a promising framework within which to describe and characterize pre-hydrodynamic attractors in a model-independent fashion. Using this framework, we define a procedure to identify a time-dependent change in coordinates which reveals a dynamical reduction in the number of active degrees of freedom. Applying this procedure to the kinetic theory of a Bjorken-expanding gas of gluons in the small angle elastic scattering limit, we are able to intuitively explain the self-similar evolution of the gluon distribution function long before the applicability of hydrodynamics, as well as the loss of memory of its initial condition.
↳ hep-phnucl-thEPJ Web Conf.(2024)·0 citations
14
A Vision for the Science of Rare Isotopes
H. L. Crawford · K. Fossez · S. König · A. Spyrou
The field of nuclear science has considerably advanced since its beginning just over a century ago. Today, the science of rare isotopes is on the cusp of a new era with theoretical and computing advances complementing experimental capabilities at new facilities internationally. In this article we present a vision for the science of rare isotope beams (RIBs). We do not attempt to cover the full breadth of the field, but rather provide a perspective and address a selection of topics that reflect our own interests and expertise. We focus in particular on systems near the drip lines, where one often finds nuclei that are referred to as "exotic," and where the role of the "nuclear continuum" is only just starting to be explored. An important aspect of this article is the attempt to highlight the crucial connections between nuclear structure and nuclear reactions required to fully interpret and leverage the rich data to be collected in the next years at RIB facilities. Further, we connect the efforts in structure and reactions to key questions of nuclear astrophysics.
↳ nucl-exnucl-thAnn.Rev.Nucl.Part.Sci.(2024)·11 citations
15
Nuclear modified transverse momentum dependent parton distribution and fragmentation functions
Mishary Alrashed🇺🇸 · Zhong-Bo Kang🇺🇸 · John Terry🇺🇸 · Hongxi Xing🇨🇳 · Congyue Zhang🇺🇸
In this study, we extend our previous global analysis of nuclear-modified transverse momentum distribution functions (nTMDs) to also consider the nuclear-modified collinear fragmentation function. Our methodology incorporates the global set of experimental data from both Drell-Yan production and Semi-Inclusive Deep Inelastic Scattering. Through a comprehensive global extraction of these distributions, we demonstrate the effectiveness of this extension by strongly describing the entire global dataset. A focal point of this paper is the impact of recent Jefferson Lab measurements. Most notably, to simultaneously describe experimental data at Jefferson Lab and HERMES we find that it is necessary to introduce a parameter which accounts for the non-perturbative scale evolution of the nTMDs. Additionally, we assess the kinematic coverage of the experimental data and provide insights into experimental opportunities at Jefferson Lab, future Electron-Ion Colliders, RHIC, and the LHC. These opportunities have the potential to significantly enhance and refine global analyses of nuclear-modified TMDs, contributing to a deeper understanding of the structure of cold nuclear matter.
↳ hep-phhep-exnucl-exnucl-th10 citations

Affiliations

first authorsco-authorsvia INSPIRE