Nuclear Theory·nucl-th

Thursday·December 30, 2021

27 papers—13 primary·14 cross-listed

01
Transverse mass scaling of dilepton radiation off a quark-gluon plasma
Maurice Coquet🇫🇷 · Xiaojian Du🇩🇪 · Jean-Yves Ollitrault🇫🇷 · Soeren Schlichting🇩🇪 · Michael Winn🇫🇷
The spectrum of dileptons produced by the quark-gluon plasma in an ultrarelativistic nucleus-nucleus collision depends only, to a good approximation, on the transverse mass M_t of the dilepton. This scaling is exact as long as transverse flow is negligible, and the system is in local thermal equilibrium. We implement a state-of-the-art modelization of kinetic and chemical equilibration in the early stages of the evolution to study the modifications of the spectrum. Violations of M_t scaling resulting from these effects are evaluated as a function of the shear viscosity to entropy ratio (eta/s) that controls the equilibration time. We determine the dependence of the spectrum on system size, centrality, rapidity, and collision energy. We show that the quark-gluon plasma produces more dileptons than the Drell-Yan process up to invariant masses of order M = 4 GeV. Due to different kinematics, for a given M_t , the dependence of the dilepton yield on M is opposite for the two processes, so that experiment alone can in principle determine which process dominates.
nucl-thhep-exhep-phnucl-exNPA(2023)·19 citations
02
Machine learning phase transitions of the three-dimensional Ising universality class
Xiaobing Li🇨🇳 · Ranran Guo🇨🇳 · Yu Zhou🇺🇸 · Kangning Liu🇨🇳 · Jia Zhao🇨🇳 · Fen Long🇨🇳 · Yuanfang Wu🇨🇳 · Zhiming Li🇨🇳
Exploration of the QCD phase diagram and critical point is one of the main goals in current relativistic heavy-ion collisions. The QCD critical point is expected to belong to a three-dimensional (3D) Ising universality class. Machine learning techniques are found to be powerful in distinguishing different phases of matter and provide a new way to study the phase diagram. We investigate phase transitions in the 3D cubic Ising model using supervised learning methods. It is found that a 3D convolutional neural network can be trained to effectivelly predict physical quantities in different spin configurations. With a uniform neural network architecture, it can encode phases of matter and identify both second- and first-order phase transitions. The important features that discriminate different phases in the classification processes are investigated. These findings can help study and understand QCD phase transitions in relativistic heavy-ion collisions.
nucl-thhep-phnucl-exCPC(2023)·8 citations
03
Nuclear level densities: from empirical models to microscopic methods
Y. Alhassid🇺🇸
The level density is among the most important statistical nuclear properties. It appears in Fermi's golden rule for transition rates and is an important input to the Hauser-Feshbach theory of compound nucleus reactions. We discuss empirical models of level densities and summarize the main experimental methods used to determine them. The microscopic calculation of level densities in the presence of correlations is a challenging many-body problem. We review recent microscopic approaches to calculate level densities. Mean-field and combinatorial methods have been applied across the nuclear chart, but often need to be augmented with empirical collective enhancement factors. The moment method and the auxiliary-field quantum Monte Carlo (AFMC) method are formulated in the context of the configuration-interaction shell model approach, and include correlations beyond the mean-field approximation.
nucl-thcond-mat.mes-hallSpringer Proc.Phys.(2020)·0 citations
04
Prediction of (p,n) Charge-Exchange Reactions with Uncertainty Quantification
T. R. Whitehead · T. Poxon-Pearson · F. M. Nunes · G. Potel
Background: Charge-exchange reactions are a powerful tool for exploring nuclear structure and nuclear astrophysics, however, a robust charge-exchange reaction theory with quantified uncertainties is essential to extracting reliable physics. Purpose: The goal of this work is to determine the uncertainties due to optical potentials used in the theory for charge-exchange reactions to isobaric analogue states. Method: We implement a two-body reaction model to study (p,n) charge-exchange transitions and perform a Bayesian analysis. We study the (p,n) reaction to the isobaric analog states of $^{14}$ C, $^{48}$ Ca, and $^{90}$ Zr targets over a range of beam energies. We compare predictions using standard phenomenological optical potentials with those obtained microscopically. Results: Charge-exchange cross sections are reasonably reproduced by modern optical potentials. However, when uncertainties in the optical potentials are accounted for, the resulting predictions of charge-exchange cross sections have very large uncertainties. Conclusions: The charge-exchange reaction cross section is strongly sensitive to the input interactions, making it a good candidate to further constrain nuclear forces and aspects of bulk nuclear matter. However, further constraints on the optical potentials are necessary for a robust connection between this tool and the underlying isovector properties of nuclei.
nucl-thnucl-exPRC(2022)·18 citations
05
Time-dependent extension of the self-consistent band theory for neutron star matter: Anti-entrainment effects in the slab phase
Kazuyuki Sekizawa · Sorataka Kobayashi · Masayuki Matsuo
Background: In the solid crust of neutron stars, a variety of crystalline structure may exist. Recently the band theory of solids has been applied to the inner crust of neutron stars and significance of the entrainment between dripped neutrons and the solid crust was advocated. Since it influences interpretations of various phenomena of neutron stars, it has been desired to develop deeper understanding of the microphysics behind. Purpose: The purpose of the present article is to propose a fully self-consistent microscopic framework for describing time-dependent dynamics of neutron star matter, which allows us to explore diverse properties of nuclear matter, including the entrainment effect. Results: As the first application of the time-dependent self-consistent band theory for nuclear systems, we investigate the slab phase of nuclear matter with various proton fractions. From a dynamic response of the system to an external force, we extract the collective mass of a slab, associated with entrained neutrons as well as bound nucleons. We find that the extracted collective mass is smaller than a naive estimation based on a potential profile and single-particle energies. We show that the reduction is mainly caused by "counterflow" of dripped neutrons towards the direction opposite to the motion of the slabs. We interpret it as an "anti-entrainment" effect. As a result, the number of effectively bound neutrons is reduced, indicating an enhancement of the number density of conduction neutrons. We demonstrate that those findings are consistent with a static treatment in the band theory of solids. *shortened due to the arXiv's word limit.
nucl-thastro-ph.HEcond-mat.quant-gasPRC(2022)·30 citations
06
Single-state or low-lying-states dominance mechanism of $2 ν β β$ -decay nuclear matrix elements
W. L. Lv🇨🇳 · Y. F. Niu🇨🇳 · D. L. Fang🇨🇳 · C. L. Bai🇨🇳
The $2 ν β β$ -decay nuclear matrix elements (NMEs) for 11 nuclei are studied with the self-consistent quasiparticle random phase approximation (QRPA) based on Skyrme Hartree-Fock-Bogoliubov (Skyrme HFB) model. As a common feature pointed out in https://journals.aps.org/prc/abstract/10.1103/PhysRevC.98.064325 Phys. Rev. C 98, 064325 (2018), negative contributions in the running sums of NMEs are found, and play important roles in the fulfillment of the single-state dominance or low-lying-states dominance hypothesis. By comparing the results of QRPA model and quasiparticle Tamm-Dancoff approximation (QTDA) model, we find that the negative contributions are due to the enhanced ground-state correlations, which are brought by the backward amplitude in QRPA model and tuned by strong isoscalar pairing interaction. The enhancement of ground-state correlations will change the signs of GT $^{+}$ transition amplitudes of higher-lying states and leads to the negative contributions in the running sum.
nucl-thPRC(2022)·8 citations
07
Evolution of $Λ$ polarization in the hadronic phase of heavy-ion collisions
Yifeng Sun🇮🇹 · Zhen Zhang🇨🇳 · Che Ming Ko🇺🇸 · Wenbin Zhao🇺🇸
Using the AMPT + MUSIC+UrQMD hybrid model, we study the global and local spin polarizations of $Λ$ hyperons as functions of the freeze-out temperature of the spin degree of freedom in the hadronic phase of Au+Au collisions at $s_{N N} = 19.6$ GeV. Including contributions from both the thermal vorticity and thermal shear of the hadronic matter, we find that, with the spin freeze-out temperature dropping from the hadronization temperature of 160 MeV to 110 MeV at the kinetic freeze-out, both the global and local spin polarizations of $Λ$ hyperons due to the thermal vorticity decrease by a factor of two, while those due to the thermal shear decrease quickly and become negligibly small at 140 MeV. Our results suggest the importance of understanding the dynamical evolution of the spin degree of freedom in the hadronic stage in relativistic heavy-ion collisions.
nucl-thhep-phPRC(2022)·34 citations
08
Exact expressions for the number of levels in single-\textit{j} orbits for three, four and five fermions
Michel Poirier🇫🇷 · Jean-Christophe Pain🇫🇷
We propose closed-form expressions of the distributions of magnetic quantum number $M$ and total angular momentum $J$ for three and four fermions in single- $j$ orbits. The latter formulas consist of polynomials with coefficients satisfying congruence properties. Such results, derived using doubly-recursive relations over $j$ and the number of fermions, enable us to deduce explicit expressions for the total number of levels in the case of three-, four- and five-fermion systems. We present applications of these formulas, such as sum rules for six- $j$ and nine- $j$ symbols, obtained from the connection with fractional-parentage coefficients, an alternative proof of the Ginocchio-Haxton relation or cancellation properties of the number of levels with a given angular momentum.
nucl-thPRC(2021)·2 citations
09
Extended relaxation time approximation and relativistic dissipative hydrodynamics
Dipika Dash🇮🇳 · Samapan Bhadury🇮🇳 · Sunil Jaiswal🇮🇳 · Amaresh Jaiswal🇮🇳
Development of a new framework for derivation of order-by-order hydrodynamics from Boltzmann equation is necessary as the widely used Anderson-Witting formalism leads to violation of fundamental conservation laws when the relaxation-time depends on particle energy, or in a hydrodynamic frame other than the Landau frame. We generalize an existing framework for consistent derivation of relativistic dissipative hydrodynamics from the Boltzmann equation with a energy-dependent relaxation-time by extending the Anderson-Witting relaxation-time approximation. We argue that the present framework is compatible with conservation laws and derive first-order hydrodynamic equations in landau frame. Further, we show that the transport coefficients, such as shear and bulk viscosity as well as charge and heat diffusion currents, have corrections due to the energy dependence of relaxation time compared to what one obtains from the Anderson-Witting approximation of the collision term. The ratio of these transport coefficients are studied using a parametrized relaxation-time, and several interesting scaling features are reported.
nucl-thhep-phhep-thPLB(2022)·38 citations
10
Resummed relativistic dissipative hydrodynamics
Huda Alalawi🇺🇸 · Mubarak Alqahtani🇸🇦 · Michael Strickland🇺🇸
In this review, we present the motivation for using relativistic anisotropic hydrodynamics to study the physics of ultrarelativistic heavy-ion collisions. We then highlight the main ingredients of the 3+1D quasiparticle anisotropic hydrodynamics model and present phenomenological comparisons with experimental data at different collision energies. These comparisons show that anisotropic hydrodynamics can describe many bulk observables of the quark-gluon plasma.
nucl-thSymmetry(2022)·19 citations
11
Two-body weak currents in heavy nuclei
E.M. Ney · J. Engel · N. Schunck
In light and medium-mass nuclei, two-body weak currents from chiral effective field theory account for a significant portion of the phenomenological quenching of Gamow-Teller transition matrix elements. Here we examine the systematic effects of two-body axial currents on Gamow-Teller strength and $β$ -decay rates in heavy nuclei within energy-density functional theory. Using a Skyrme functional and the charge-changing finite amplitude method, we add the contributions of two-body currents to the usual one-body linear response in the Gamow-Teller channel, both exactly and though a density-matrix expansion. The two-body currents, as expected, usually quench both summed Gamow-Teller strength and decay rates, but by an amount that decreases as the neutron excess grows. In addition, they can enhance individual low-lying transitions, leading to decay rates that are quite different from those that an energy-independent quenching would produce, particularly in neutron-rich nuclei. We show that both these unexpected effects are related to changes in the total nucleon density as the number of neutrons increases.
nucl-thPRC(2022)·12 citations
12
Thermalization of Nuclear Matter in Heavy-Ion Collisions at Fermi-Energies
Thomas Onyango · Aldo Bonasera · Ralf Rapp
We analyze the time evolution of the kinetic properties of nuclear matter produced in heavy-ion collisions at Fermi energies. The collision system is simulated using Constrained Molecular Dynamics (CoMD) transport calculations whose output is the isospin, position, and momentum of the nucleons. Focusing on central 35A $\cdot$ MeV $^{40}$ Ca+ $^{40}$ Ca collisions we utilize this information to extract localized momentum distributions in volume elements of 8fm $^{3}$ and time steps of 5fm/ $c$ . We then parameterize the single-particle momentum distributions with thermally motivated fit functions in the local rest frame of each cell. While the transverse-momentum distributions are well reproduced by thermal ones, the longitudinal ones carry a marked imprint of the initial nuclear motion which we capture by introducing a centroid motion into our fit functions. In particular, we find that Fermi distributions yield significantly better fits than Boltzmann ones, a consequence of the Pauli blocking implemented in CoMD. From the fits we extract the time dependence of the thermodynamic and collective properties of the excited nuclear medium. We find that the transverse temperature gradually rises to about 6MeV, which is accompanied by a dissipation of the initial centroid motion of the incoming nuclei which vanishes at about 100fm/ $c$ after initial impact. We are therefore able to track the transition of beam energy into random kinetic energy for nucleons, suggesting a three-dimensional equilibration of energy in the late stages of the collision.
nucl-thNPA(2022)·2 citations
13
Characteristic momentum of Hydro+ and a bound on the speed of sound near the QCD critical point
Navid Abbasi🇨🇳 · Matthias Kaminski🇺🇸
Near the critical point in the QCD phase diagram, hydrodynamics breaks down at a momentum where the frequency of the fastest hydrodynamic mode becomes comparable with the decay rate of the slowest non-hydrodynamic mode. Hydro+ was developed as a framework which extends the range of validity of hydrodynamics beyond that momentum value. This was achieved through coupling the hydrodynamic modes to the slowest non-hydrodynamic mode. In this work, analyzing the spectrum of linear perturbations in Hydro+, we find that a slow mode falls out of equilibrium if its momentum is greater than a characteristic momentum value. That characteristic momentum turns out to be set by the branch points of the dispersion relations. These branch points occur at the critical momenta of so-called spectral curves and are related to the radius of convergence of the derivative expansion. The existence of such a characteristic momentum scale suggests that a particular class of slow modes has no remarkable effect on the flow of the plasma. Based on these results and previously derived relations to the stiffness of the equation of state, we find a temperature-dependent upper bound for the speed of sound near the critical point in the QCD phase diagram.
nucl-thhep-phhep-thPRD(2022)·11 citations
14
Energy dependence of the chiral magnetic effect in expanding holographic plasma
Casey Cartwright🇺🇸 · Matthias Kaminski🇺🇸 · Bjoern Schenke🇺🇸
Based on a holographic far-from-equilibrium calculation of the chiral magnetic effect~(CME) in an expanding quark gluon plasma, we study collisions at various energies. We compute the time evolution of the CME current in the presence of a time-dependent axial charge density and subject to a time-dependent magnetic field. The plasma expansion leads to a dilution of the CME current. We study distinct combinations of how the initial magnetic field and initial axial charge behave with changing initial energy as proposed in previous literature. Most scenarios we consider lead to an increasing time-integrated CME current, when increasing the initial energy. This would make it more likely to observe the CME at higher collision energies.
↳ hep-phhep-thnucl-thPRC(2022)·18 citations
15
An Effective Field Theory of Magneto-Elasticity
Shashin Pavaskar🇺🇸 · Riccardo Penco🇺🇸 · Ira Z. Rothstein🇺🇸
We utilize the coset construction to derive the effective field theory of magnon-phonon interactions in (anti)-ferromagnetic and ferrimagnetic insulating materials. The action is used to calculate the equations of motion which generalize the Landau-Lifshitz and stress equations to allow for magneto-acoustic couplings to all orders in the fields at lowest order in the derivative expansion. We also include the symmetry breaking effects due to Zeeman, and Dzyaloshinsky-Moriya interactions. This effective theory is a toolbox for the study of magneto-elastic phenomena from first principles. As an example we use this theory to calculate the leading order contribution to the magnon decay width due to its the decay into phonons.
↳ hep-thcond-mat.mes-hallgr-qchep-ph+1SciPost Phys.(2022)·19 citations
16
Pion and Kaon box contribution to $a_{μ}^{HLbL}$
Ángel Miramontes🇲🇽 · Adnan Bashir🇲🇽 · Khépani Raya🇪🇸 · Pablo Roig🇲🇽
We present an evaluation of the $π^{\pm}$ and $K^{\pm}$ box contributions to the hadronic light-by-light piece of the muon's anomalous magnetic moment, $a_{μ}$ . The calculation of the corresponding electromagnetic form factors (EFFs) is performed within a Dyson-Schwinger equations (DSE) approach to quantum chromodynamics. These form factors are calculated in the so-called rainbow-ladder (RL) truncation, following two different evaluation methods and, subsequently, in a further improved approximation scheme which incorporates meson cloud effects. The results are mutually consistent, indicating that in the domain of relevance for $a_{μ}$ the obtained EFFs are practically equivalent. Our analysis yields the combined estimates of $a_{μ}^{π^{\pm} - b o x} = - (15.6 \pm 0.2) \times 1 0^{- 11}$ and $a_{μ}^{K^{\pm} - box} = - (0.48 \pm 0.02) \times 1 0^{- 11}$ , in full agreement with results previously obtained within the DSE formalism and other contemporary estimates.
↳ hep-phnucl-thPRD(2022)·50 citations
17
Model studies of V0 production ratios in $pp$ collisions at $s$ = 0.2, 0.9, and 7 TeV
M. Ajaz🇵🇰 · M.U. Ashraf🇵🇰 · M. Waqas🇨🇳 · Z. Yasin🇵🇰 · A.M. Khubrani🇸🇦 · S. Hassan🇵🇰 · A. Haj Ismail🇦🇪 · L.L. Li🇨🇳
A comparative study of $V^{0}$ ratios has been performed between HIJING, Sibyll and QGSJET model-based event generators in this paper. The ratios under study are {\alam}/{\lam}, {\alam}/{\ks} and {\xim}/{\lam} as a function of rapidity $y$ , rapidity loss ( $Δ y$ ) and {\ppt} from $pp$ collisions at \sqrts~= 0.2, 0.9, and 7 TeV and these simulations are then compared with the STAR and LHCb fiducial phase spaces in different {\ppt} regions. Although the models could produce some of the ratios in a limited {\ppt} and/or $y$ region, none of them completely predicts the experimental results. The QGSJET has good predictions with the data in most of the cases but since the model does not include the $Ξ$ particle definition, therefore it does not give any predictions for $Ξ$ /{\lam} ratios. The extrapolation to the highest possible energies can be studied by re-tune some of the basic parameters based on current and previous measurements. These kinds of systematic comparison studies are also useful to apply certain constraints on the pQCD and non-pQCD-based hadronic event generators to significantly improve the predictions of Standard Model physics at the RHIC and LHC experimental data for the understanding of underlying physics mechanisms in high energy collisions.
↳ hep-phnucl-thEur.Phys.J.Plus(2023)·9 citations
18
Light-quark mass dependence of the nucleon axial charge and pion-nucleon scattering phenomenology
Fernando Alvarado🇪🇸 · Luis Alvarez-Ruso🇪🇸
The light-quark mass dependence of the nucleon axial isovector charge ( $g_{A}$ ) has been studied up to next-to-next-to-leading order, $O (p^{4})$ , in relativistic chiral perturbation theory using extended-on-mass-shell renormalization, without and with explicit $Δ (1232)$ degrees of freedom. We show that in the $Δ$ -less case, at this order, the flat trend of $g_{A} (M_{π})$ exhibited by state-of-the-art lattice QCD (LQCD) results cannot be reproduced using low energy constants (LECs) extracted from pion-nucleon elastic and inelastic scattering. A satisfactory description of these LQCD data is only achieved in the theory with $Δ$ . From this fit we report $g_{A} (M_{π (phys)}) = 1.260 \pm 0.012$ , close to the experimental result, and $d_{16} = - 0.88 \pm 0.88$ GeV $^{- 2}$ , in agreement with its empirical value. The large uncertainties are of theoretical origin, reflecting the difference between $O (p^{3})$ and $O (p^{4})$ that still persists at large $M_{π}$ in presence of the $Δ$ .
↳ hep-phhep-latnucl-thPRD(2022)·15 citations
19
An energy independent scaling of transverse momentum spectra of direct (prompt) photons from two-body processes in high-energy proton-proton collisions
Qiang Zhang🇨🇳 · Ya-Qin Gao🇨🇳 · Fu-Hu Liu🇨🇳 · Khusniddin K. Olimov🇺🇿
Transverse momentum spectra of direct (prompt) photons from two-body processes in high-energy proton-proton (p+p) collisions are analyzed in this paper. We collected the experimental invariant cross-sections at mid-rapidity in p+p collisions measured by the UA6, CCOR, R806, R110, PHENIX, NA24, CMS, ALICE, and ATLAS Collaborations over a center-of-mass energy range from 24.3 GeV to 13 TeV. In fitting the data, we used different kinds of functions which include the revised Tsallis--Pareto-type function (the TP-like function) at the particle level, the convolution of two TP-like functions at the quark level, and the root-sum-of-squares of two revised Tsallis-like functions in which the quark chemical potentials $μ_{i} = μ_{B} /3$ or $μ_{i} = 0$ , where $μ_{B}$ is the baryon chemical potential. We have extracted the values of three main free parameters: the effective temperature $T$ , power index $n_{0}$ (or entropy index $q$ ), and correction index $a_{0}$ . After analyzing the changing trends of the parameters, we found that $T$ , $q$ , and $a_{0}$ increase and $n_{0}$ decreases with the increase of collision energy. Based on the analyses of transverse momentum spectra, an energy independent scaling, i.e. the $x_{T}$ scaling, is obtained.
↳ hep-phhep-exnucl-exnucl-thAnnalen Phys.(2022)·7 citations
20
Dark Matter Effects on the Compact Star Properties
H. C. Das · Ankit Kumar · Bharat Kumar · S. K. Patra
The neutron star properties are generally determined by the equation of state of $β$ -equilibrated dense matter. In this work, we consider the interaction of fermionic dark matter (DM) particles with the nucleons via Higgs exchange and investigate its effect on the neutron star properties with the relativistic mean-field model equation of state coupled with DM. We deduce that DM significantly affects the neutron star properties, such as considerably reduce the maximum mass of the star, which depends on the percentage of the DM considered inside the neutron star. The tidal Love numbers both for electric and magnetic cases and surficial Love numbers are also studied for DM admixed NS. It is observed that the magnitude of tidal and surficial Love numbers increase with more DM percentage. Further, we point out that post-Newtonian tidal corrections to gravitational waves decreased by increasing DM percentage. Also, the DM effect on the GW signal is significant during the late inspiral and merger stages of binary evolution for GW frequencies >500 Hz.
↳ astro-ph.HEgr-qcnucl-thGalaxies(2022)·46 citations
21
Towards robust constraints on nuclear effective field theory from lattice QCD
Marc Illa (for the NPLQCD Collaboration)🇪🇸
We will discuss several new results from the NPLQCD Collaboration that combine lattice QCD results on (hyper)nuclear systems at unphysical pion masses together with nuclear effective field theories. Two-baryon channels with strangeness $0$ to $- 4$ are analyzed, with findings that point to interesting symmetries observed in hypernuclear forces as predicted in the limit of QCD with a large number of colors. Also, several matrix elements of light nuclei are studied. The tritium axial charge, related to the Gamow-Teller matrix element, and the longitudinal momentum fraction of $^{3}$ He that is carried by the isovector combination of $u$ and $d$ are extracted and extrapolated to the physical point. For this latter case, it can be seen how including lattice results to experimental determinations can have imminent potential to enable more precise determinations and to reveal the QCD origins of the EMC effect.
↳ hep-lathep-phnucl-thPoS(2022)·2 citations
22
Tidal Deformability as a Probe of Dark Matter in Neutron Stars
Davood Rafiei Karkevandi🇮🇷 · Soroush Shakeri🇮🇷 · Violetta Sagun🇵🇹 · Oleksii Ivanytskyi🇵🇱
The concept of boson stars (BSs) was first introduced by Kaup and Ruffini-Bonazzola in the 1960s. Following this idea, we investigate an effect of self-interacting asymmetric bosonic dark matter (DM) according to Colpi et al. model for BSs (1986) on different observable properties of neutron stars (NSs). In this paper, the bosonic DM and baryonic matter (BM) are mixed together and interact only through gravitational force. The presence of DM as a core of a compact star or as an extended halo around it is examined by applying different boson masses and DM fractions for a fixed coupling constant. The impact of DM core/halo formations on a DM admixed NS properties is probed through the maximum mass and tidal deformability of NSs. Thanks to the recent detection of Gravitational-Waves (GWs) and the latest X-ray observations, the DM admixed NS's features are compared to LIGO/Virgo and NICER results.
↳ astro-ph.HEgr-qchep-phnucl-thPublished by the World Scientific, Procee…·24 citations
23
Digital Quantum Simulation of the Schwinger Model and Symmetry Protection with Trapped Ions
Nhung H. Nguyen🇺🇸 · Minh C. Tran🇺🇸 · Yingyue Zhu🇺🇸 · Alaina M. Green🇺🇸 · C. Huerta Alderete🇺🇸 · Zohreh Davoudi🇺🇸 · Norbert M. Linke🇺🇸
Tracking the dynamics of physical systems in real time is a prime application of digital quantum computers. Using a trapped-ion system with up to six qubits, we simulate the real-time dynamics of a lattice gauge theory in 1+1 dimensions, i.e., the lattice Schwinger model, and demonstrate non-perturbative effects such as pair creation for times much longer than previously accessible. We study the gate requirement of two formulations of the model using the Suzuki-Trotter product formula, as well as the trade-off between errors from the ordering of the Hamiltonian terms, the Trotter step size, and experimental imperfections. To mitigate experimental errors, a recent symmetry-protection protocol for suppressing coherent errors and a symmetry-inspired post-selection scheme are applied. This work demonstrates the integrated theoretical, algorithmic, and experimental approach that is essential for efficient simulation of lattice gauge theories and other complex physical systems.
↳ quant-phhep-lathep-phnucl-thPRX Quantum(2022)·181 citations
24
Quantum kinetic theory for spin transport of quarks with background chromo-electromagnetic fields
Di-Lun Yang🇹🇼
We derive the quantum kinetic equations for massive and massless quarks coupled with the background chromo-electromagnetic fields from the Wigner-function approach with the $ℏ$ expansion and effective power-counting scheme. For each case, one obtains coupled color-singlet and color-octet kinetic equations, which also involve the scalar and axial-vector components for the charge and spin transport. These kinetic equations delineate entangled evolution of the corresponding distribution functions decomposed in color space. At weak coupling, we derive the close form of the color-singlet kinetic equations for spin transport, which incorporates the diffusion term and the source term that triggers dynamical spin polarization led by correlation functions of color fields. Also, the non-dynamical source term is found in the axial Wigner function. The induced spin polarization and axial charge currents by these source terms are discussed under physical assumptions for color-field correlators in near-equilibrium quark gluon plasmas. In the constant-field limit, we further obtain non-vanishing axial Ward identities, from which we extract the pseudo-scalar condensate for massive quarks at finite temperature.
↳ hep-phhep-thnucl-thJHEP(2022)·31 citations
25
Kaon and Nucleon States with Hidden Charm
Brenda B. Malabarba🇧🇷 · A. Martínez Torres🇧🇷 · K.P. Khemchandani🇧🇷 · Xiu-Lei Ren🇩🇪 · Li-Sheng Geng🇨🇳
In this talk we discuss the formation of exotic hadrons with hidden charm arising from three-body interactions. To be more specific, in the strangeness sector, we predict the existence of a mesonic state, $K^{*} (4307)$ , which is dynamically generated from the three-body interactions of the $K D D ˉ^{*}$ system, has mass around $4307$ MeV and quantum numbers $I (J^{P}) = 1/2 (1^{-})$ . In the baryonic sector, we predict the existence of $N^{*}$ states, which are generated from the three-body interactions of the $N D D ˉ^{*}$ system, with masses around $4400 \sim 4600$ MeV, widths of $2 \sim 20$ MeV and positive parity.
↳ hep-phnucl-thRev.Mex.Fis.Suppl.(2022)·0 citations
26
S-wave pion-pion scattering lengths from nucleon-meson fluctuations
Jürgen Eser🇫🇷 · Jean-Paul Blaizot🇫🇷
We present calculations of the $S$ -wave isospin-zero and isospin-two pion-pion scattering lengths within a nucleon-meson model with parity doubling. Both scattering lengths are computed in various approximations, ranging from a mean-field (MF) calculation towards the inclusion of loop corrections by means of the functional renormalization group (FRG). The bosonic part of the investigated nucleon-meson model is formulated in terms of stereographic projections as a "natural" set of coordinates on the respective vacuum manifold. We thereby elucidate subtleties concerning the truncation of the effective action w.r.t. higher-derivative pion interactions and the "successful" computation of the scattering lengths. As the main result, we find simultaneous agreement for the isospin-zero and isospin-two scattering lengths with experimental data within the $LPA^{'}$ -truncation of the FRG, together with chiral symmetry breaking (roughly) occurring at the characteristic scale of $4 π f_{π}$ . The isoscalar $σ$ -mass is dynamically generated by the FRG integration of momentum modes, and is a prediction of the model. It ends being of the order of $500 MeV$ , i.e., much lower than the value ( $> 1 GeV$ ) found in MF or one-loop treatment of this or related models. Finally, the convergence of the corresponding low-energy expansion of the quantum effective action in terms of pion momenta is discussed.
↳ hep-phnucl-thPRD(2022)·8 citations
27
Topological tensor invariants and the current algebra approach: Analysis of 196 nonleptonic two-body decays of single and double charm baryons -- a review
Stefan Groote🇪🇪 · Jürgen G. Körner🇩🇪
We shed new light on the standard current algebra approach to the nonleptonic two-body decays of single and double heavy charm baryons. By making use of the completeness relation for the flavor wave functions of the ground state baryon {\bf 20'} representation we are able to rewrite the results of the current algebra approach in terms of the seven topological tensor invariants describing the decays. The representation of the current algebra results in terms of topological tensor invariants depends only on the initial and final state of the process. The summation over intermediate states inherent to the current algebra result is automatically taken care of in the tensor representation. In this way one arrives at a new, quick and very compact assessment of the results of the current algebra/pole model calculation. For example, one can quickly identify the decays in which the p.v.\ $S$ -wave amplitude is predicted to vanish implying zero polarization asymmetries in these decays. We provide tables of the values of the seven topological tensor invariants for all Cabibbo favored and singly and doubly Cabibbo suppressed nonleptonic single and double charm baryon decays. In total we treat 196 charm baryon decays. We also discuss the charm preserving $Δ C = 0$ decays of single charm baryons and the usual hyperon decays.
↳ hep-phhep-exnucl-thEPJC(2022)·27 citations

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first authorsco-authorsvia INSPIRE