Nuclear Theory·nucl-th

Tuesday·September 20, 2022

13 papers—7 primary·6 cross-listed

01
Fluctuations of conserved charges in hydrodynamics and molecular dynamics
Volodymyr Vovchenko🇺🇸
I present an overview of recent theoretical results on fluctuations of conserved charges in heavy-ion collisions obtained in relativistic hydrodynamics and molecular dynamics frameworks. In particular, I discuss the constraints on the location of the QCD critical point based on comparisons of experimental data on proton number cumulants with precision calculations of non-critical contributions. Recent developments on critical fluctuations in molecular dynamics simulations are covered as well.
nucl-thhep-phnucl-exEPJ Web Conf.(2023)·0 citations
02
Berry's phase and chiral anomalies
Kazuo Fujikawa🇯🇵 · Koichiro Umetsu🇯🇵
The basic materials of Berry's phase and chiral anomalies are presented to appreciate the phenomena related to those notions. As for Berry's phase, a general survey of the subject is presented using both Lagrangian and Hamiltonian formalisms. The canonical Hamiltonian formalism of the Born-Oppenheimer approximation, when applied to the anomalous Hall effect, can incorporate the gauge symmetry of Berry's connection but unable to incorporate the electromagnetic vector potential simultaneously. Transformed to the Lagrangian formalism with a time-derivative term allowed, the Born-Oppenheimer approximation can incorporate the electromagnetic vector potential simultaneously with Berry's connection, but the consistent canonical property is lost and thus becomes classical. The Lagrangian formalism can thus incorporate both gauge symmetries simultaneously but spoils the basic quantum symmetries, and thus results in classical anomalous Poisson brackets and the classical Nernst effect as in the conventional formalism. As for chiral anomalies, we present basic materials by the path integral formulation with an emphasis on fermions on the lattice. A chiral fermion defined by $γ_{5}$ on the lattice does not contain the chiral anomaly for the non-vanishing lattice spacing $a \neq = 0$ . The idea of a spectral flow on the lattice does not lead to an anomaly for each species doubler separately but rather to a pair production in a general sense. We also mention that a specific construction called the Ginsparg-Wilson fermion, which is free of species doublers, may practically be useful. We discuss the representative applications of Berry's phase and chiral anomalies in nuclear physics and related fields to illustrate the use of these two basic notions.
nucl-thhep-thPPNP(2023)·6 citations
03
The causality and stability of relativistic spin-hydrodynamics
Golam Sarwar🇮🇳 · Md Hasanujjaman🇮🇳 · Jitesh R. Bhatt🇮🇳 · Hiranmaya Mishra🇮🇳 · Jan-e Alam🇮🇳
We study the causality and stability of relativistic hydrodynamics with the inclusion of the spin degree of freedom as a hydrodynamic field. We consider two specific models of spin-hydrodynamics for this purpose. A linear mode analysis for static background shows that a first-order dissipative spin-hydrodynamics remains acausal and admits instabilities. Besides, it is found that the inclusion of the spin field in hydrodynamics leads to new kinds of linear modes in the system. These new modes also exhibit instability and acausal behavior. The second model of the spin-hydrodynamics that we have considered here is equivalent to a particular second-order conventional hydrodynamics with no dissipative effects. For a static background, it is found that the linear modes of this model support the sound waves only. However, when the background has constant vorticity, then the model admits instability and acausality in certain situations. It is found that the spin-dynamics have an effect on the hydrodynamic response of the fluid. These findings point toward the need for a causal and stable theory with spin as a hydrodynamic field to describe the spin-polarized fluid.
nucl-thcond-mat.stat-mechhep-phhep-thPRD(2023)·42 citations
04
Alpha-particle formation and clustering in nuclei
E. Khan🇫🇷 · L. Heitz🇫🇷 · F. Mercier🇫🇷 · J.-P. Ebran🇫🇷
The nucleonic localization function has been used for a decade to study the formation of alpha-particles in nuclei, by providing a measure of having nucleons of a given spin in a single place. However, differences in interpretation remain, compared to the nucleonic density of the nucleus. In order to better understand the respective role of the nucleonic localization function and the densities in the alpha-particle formation in cluster states or in alpha-decay mechanism, both an analytic approximation and microscopic calculations, using energy density functionals, are undertaken. The nucleonic localization function is shown to measure the anti-centrifugal effect, and is not sensitive to the level of compactness of the alpha-particle itself. It probes the purity of the spatial overlap of four nucleons in the four possible (spin, isospin) states. The density provides, in addition, information on the compactness of an alpha-particle cluster. The respective roles of the nucleonic localization function and the density are also analyzed in the case of alpha-particle emission. More generally, criteria to assess the prediction of alpha-cluster in nuclear states are provided.
nucl-thPRC(2022)·14 citations
05
Extracting nuclear matter properties from the neutron star matter equation of state using deep neural networks
Márcio Ferreira · Valéria Carvalho · Constança Providência
The extraction of the nuclear matter properties from neutron star (NS) observations is nowadays an important issue, in particular, the properties that characterize the symmetry energy which are essential to describe correctly asymmetric nuclear matter. We use deep neural networks (DNNs) to map the relation between cold $β$ -equilibrium NS matter and the nuclear matter properties. Assuming a quadratic dependence on the isospin asymmetry for the energy per particle of homogeneous nuclear matter and using a Taylor expansion up to fourth order in the iso-scalar and iso-vector contributions, we generate a dataset of different realizations of $β$ -equilibrium NS matter and the corresponding nuclear matter properties. The DNN model was successfully trained, attaining great accuracy in the test set. Finally, a real case scenario was used to test the DNN model, where a set of 33 nuclear models, obtained within a relativistic mean field approach or a Skyrme force description, were fed into the DNN model and the corresponding nuclear matter parameters recovered with considerable accuracy, in particular, the standard deviations $σ (L_{sym}) = 12.85$ MeV and $σ (K_{sat}) = 41.02$ MeV were obtained, respectively, for the slope of the symmetry energy and the nuclear matter incompressibility at saturation.
nucl-thastro-ph.HEhep-phPRD(2022)·29 citations
06
Nuclear DFT electromagnetic moments in heavy deformed open-shell odd nuclei
J. Bonnard🇫🇷 · J. Dobaczewski🇬🇧 · G. Danneaux🇫🇮 · M. Kortelainen🇫🇮
Within the nuclear DFT approach, we determined the magnetic dipole and electric quadrupole moments for paired nuclear states corresponding to the proton (neutron) quasiparticles blocked in the p11/2- (n13/2+) intruder configurations. We performed calculations for all deformed open-shell odd nuclei with 63<=Z<=82 and 82<=N<=126. Time-reversal symmetry was broken in the intrinsic reference frame and self-consistent shape and spin core polarizations were established. We determined spectroscopic moments of angular-momentum-projected wave functions and compared them with available experimental data. We obtained good agreement with data without using effective g-factors or effective charges in the dipole or quadrupole operators, respectively. We also showed that the intrinsic magnetic dipole moments, or those obtained for conserved intrinsic time-reversal symmetry, do not represent viable approximations of the spectroscopic ones.
nucl-thPLB(2023)·24 citations
07
dmscatter: A Fast Program for WIMP-Nucleus Scattering
Oliver Gorton🇺🇸 · Calvin Johnson🇺🇸 · Changfeng Jiao🇺🇸 · Jonathan Nikoleyczik🇺🇸
Recent work, using an effective field theory framework, has shown the number of possible couplings between nucleons and the dark-matter-candidate Weakly Interacting Massive Particles (WIMPs) is larger than previously thought. Inspired by an existing Mathematica script that computes the target response, we have developed a fast, modern Fortran code, including optional OpenMP parallelization, along with a user-friendly Python wrapper, to swiftly and efficiently explore many scenarios, with output aligned with practices of current dark matter searches. A library of most of the important target nuclides is included; users may also import their own nuclear structure data, in the form of reduced one-body density matrices. The main output is the differential event rate as a function of recoil energy, needed for modeling detector response rates, but intermediate results such as nuclear form factors can be readily accessed.
nucl-thastro-ph.COhep-phnucl-exComput.Phys.Commun.(2023)·11 citations
08
Exclusive $J / ψ$ production in ultraperipheral Pb+Pb collisions to NLO pQCD
K. J. Eskola🇫🇮 · C. A. Flett🇫🇮 · V. Guzey🇫🇮 · T. Löytäinen🇫🇮 · H. Paukkunen🇫🇮
We present the first NLO pQCD study of coherent exclusive $J / ψ$ photoproduction in ultraperipheral heavy-ion collisions (UPCs) at the LHC. Taking the generalized parton distributions (GPDs) in their forward limit, as parton distribution functions (PDFs), we quantify the NLO contributions in the rapidity-differential cross section, show that the real part of the amplitude must not be neglected, study the gluon and quark contributions, chart the scale-choice and PDF uncertainties, and compare the NLO results with LHC and HERA data. We show that the scale dependence is significant but a scale choice can be found with which we reproduce the 2.76 and 5.02 TeV UPC data. In particular, we show that the process is clearly more sensitive to the nuclear quark PDFs than thought before.
↳ hep-phnucl-thActa Phys.Polon.Supp.(2023)·1 citation
09
Weinberg's Compositeness
U. van Kolck🇫🇷
Nearly 60 years ago Weinberg suggested a criterion for particle "compositeness", which has acquired new life with the discovery of new, exotic hadrons. His idea resonates with model-based intuition. I discuss the role it plays in the context of another of Weinberg's creations, the model-independent framework of effective field theories.
↳ hep-phnucl-thSymmetry(2022)·31 citations
10
Nucleon spin decomposition with one dynamical gluon
Siqi Xu🇨🇳 · Chandan Mondal🇨🇳 · Xingbo Zhao🇨🇳 · Yang Li🇨🇳 · James P. Vary🇺🇸
We solve for the light-front wave functions of the nucleon from a light-front quantum chromodynamics (QCD) effective Hamiltonian with three-dimensional confinement. We obtain solutions using constituent three quarks combined with three quarks and one gluon Fock components. The resulting light-front wave functions provide a good quality description of the nucleon's quark distribution functions following QCD scale evolution. We present the effects from incorporating a dynamical gluon on the nucleon's gluon densities, helicity distribution and orbital angular momentum that constitutes the nucleon spin sum rule.
↳ hep-phnucl-thPRD(2023)·57 citations
11
Transverse momentum broadening from NLL BFKL to all orders in pQCD
Paul Caucal🇺🇸 · Yacine Mehtar-Tani🇺🇸
We study, to all orders in perturbative QCD, the universal behavior of the saturation momentum $Q_{s} (L)$ controlling the transverse momentum distribution of a fast parton propagating through a dense QCD medium with large size $L$ . Due to the double logarithmic nature of the quantum evolution of the saturation momentum, its large $L$ asymptotics is obtained by slightly departing from the double logarithmic limit of either next-to-leading log (NLL) BFKL or leading order DGLAP evolution equations. At fixed coupling, or in conformal $N = 4$ SYM theory, we derive the large $L$ expansion of $Q_{s} (L)$ up to order $α_{s}^{3/2}$ . In QCD with massless quarks, where conformal symmetry is broken by the running of the strong coupling constant, the one-loop QCD $β$ -function fully accounts for the universal terms in the $Q_{s} (L)$ expansion. Therefore, the universal coefficients of this series are known exactly to all orders in $α_{s}$ .
↳ hep-phhep-thnucl-thPRD(2023)·9 citations
12
Shape evolution in the rapidly rotating $^{140}$ Gd nucleus
H. Pai · S. Rajbanshi · Somnath Nag · Sajad Ali · R. Palit · G. Mukherjee · F. S. Babra · R. Banik · Soumik Bhattacharya · S. Biswas · S. Chakraborty · R. Donthi and 5 other authors
Ground state band of $^{140}$ Gd has been investigated following their population in the $^{112}$ Sn( $^{35}$ Cl,~ $α$ p2n) $^{140}$ Gd reaction at 195 MeV of beam energy using a large array of Compton suppressed HPGe clovers as the detection setup. Apart from other spectroscopic measurements, level lifetimes of the states have been extracted using the Doppler Shift Attenuation Method. Extracted quadrupole moment along with the pairing independent cranked Nilsson-Strutinsky model calculations for the quadrupole band reveal that the nucleus preferably attains triaxiality with $γ$ = -30 $^{\circ}$ . The calculation though shows a slight possibility of rotation around the longest possible principal axis at high spin $\sim$ 30 $ℏ$ which is beyond the scope of the present experiment.
↳ nucl-exnucl-th0 citations
13
Vector dark boson mediated feeble interaction between fermionic dark matter and strange quark matter in quark stars
Debashree Sen🇮🇳 · Atanu Guha🇰🇷
We study the structural properties like the gravitational mass, radius and tidal deformability of dark matter (DM) admixed strange quark stars (SQSs). For the purpose we consider the vector MIT Bag model to describe the strange quark matter (SQM) and investigate the possible presence of accreted DM in the SQSs consequently forming DM admixed SQSs. We introduce feeble interaction between SQM and the accreted fermionic DM via a vector dark boson mediator. Considering the present literature, in the context of possible presence of DM in SQSs, this work is the first to consider interaction between DM and SQM in the DM admixed SQSs. The mass of the DM fermion ( $m_{χ}$ ) and the vector mediator ( $m_{ξ}$ ) and the coupling ( $y_{ξ}$ ) between them are determined in accordance with the constraint from Bullet cluster and the present day relic abundance, respectively. We find that the presence of DM reduces both the mass and radius of the star compared to the no-DM case. The massive the DM fermion, the lower the values of maximum mass and radius of the DM admixed SQSs. For the chosen values of $m_{χ}$ and corresponding values of $m_{ξ}$ and $y_{ξ}$ , the computed structural properties of the DM admixed SQSs satisfy all the various present day astrophysical constraints.We obtain massive DM admixed SQSs configurations consistent with the GW190814 observational data. Hence the secondary compact object associated with this event may be a DM admixed SQS.
↳ hep-phastro-ph.COastro-ph.HEnucl-thMNRAS(2022)·27 citations

Affiliations

first authorsco-authorsvia INSPIRE