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Nuclear Theory·nucl-th

Wednesday·September 16, 2020

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    Measuring the surface thickness of the weak charge density of nuclei

    Brendan Reed🇺🇸 · Z. Jaffe🇺🇸 · C. J. Horowitz🇺🇸 · C. Sfienti🇩🇪

    The present PREX-II and CREX experiments are measuring the rms radius of the weak charge density of Pb and Ca. We discuss the feasibility of a new parity violating electron scattering experiment to measure the surface thickness of the weak charge density of a heavy nucleus. Once PREX-II and CREX have constrained weak radii, an additional parity violating measurement at a momentum transfer near 0.76 fm for Pb or 1.28 fm for Ca can determine the surface thickness.

    nucl-thnucl-exPRC(2020)·15 citations
  2. 02

    Beam Energy dependence of Light Nuclei Production in Au+Au Collisions

    Wenbin Zhao🇨🇳 · Chun Shen🇺🇸 · Che Ming Ko🇺🇸 · Quansheng Liu🇨🇳 · Huichao Song🇨🇳

    We study the collision energy dependence of (anti-)deuteron and (anti-)triton production in the most central Au+Au collisions at 7.7, 11.5, 19.6, 27, 39, 62.4 and 200 GeV, using the nucleon coalescence model. The needed phase-space distribution of nucleons at the kinetic freeze-out is generated from a new 3D hybrid dynamical model (\texttt{iEBE-MUSIC}) by using a smooth crossover equation of state (EoS) without a QCD critical point. Our model calculations predict that the coalescence parameters of (anti-)deuteron ( and ) decrease monotonically as the collision energy increases, and the light nuclei yield ratio remains approximately a constant with respect to the collision energy. These calculated observables fail to reproduce the non-monotonic behavior of the corresponding data from the STAR Collaboration. Without including any effects of the critical point in our model, our results serve as the baseline predictions for the yields of light nuclei in the search for the possible QCD critical points from the experimental beam energy scan of heavy ion collisions.

    nucl-thhep-phnucl-exPRC(2020)·47 citations
  3. 03

    Hydrodynamics formalism with Spin dynamics

    Rajeev Singh🇵🇱

    We review the key steps of the relativistic fluid dynamics formalism with spin degrees of freedom initiated recently. We obtain equations of motion of the expansion of the system from the underlying definitions of quantum kinetic theory for the equilibrium phase space distribution functions. We investigate the dynamics of spin polarization of the system in the Bjorken hydrodynamical background.

    nucl-thhep-phhep-thActa Phys.Polon.Supp.(2021)·2 citations
  4. 04

    Inclusive Electron Scattering And The GENIE Neutrino Event Generator

    A. Papadopoulou🇺🇸 · A. Ashkenazi🇺🇸 · S. Gardiner🇺🇸 · M. Betancourt🇺🇸 · S. Dytman🇺🇸 · L.B. Weinstein🇺🇸 · E. Piasetzky🇮🇱 · F. Hauenstein🇺🇸 · M. Khachatryan🇺🇸 · S. Dolan🇨🇭 · G. Megias🇯🇵 · O. Hen (The electrons for neutrinos collaboration)🇺🇸

    The extraction of neutrino mixing parameters from accelerator-based neutrino oscillation experiments relies on proper modeling of neutrino-nucleus scattering processes using neutrino-interaction event generators. Experimental tests of these generators are difficult due to the broad range of neutrino energies produced in accelerator-based beams and the low statistics of current experiments. Here we overcome these difficulties by exploiting the similarity of neutrino and electron interactions with nuclei to test neutrino event generators using high-precision inclusive electron scattering data. To this end, we revised the electron-scattering mode of the GENIE event generator (-GENIE) to include electron-nucleus bremsstrahlung radiation effects and to use, when relevant, the exact same physics models and model parameters, as the standard neutrino-scattering version. We also implemented new models for quasielastic (QE) scattering and meson exchange currents (MEC) based on the theory-inspired SuSAv2 approach. Comparing the new -GENIE predictions with inclusive electron scattering data, we find an overall adequate description of the data in the QE- and MEC-dominated lower energy transfer regime, especially when using the SuSAv2 models. Higher energy transfer-interactions, which are dominated by resonance production, are still not well modeled by -GENIE.

    nucl-thhep-exhep-phnucl-exPRD(2021)·48 citations
  5. 05

    Diquark Induced Short-Range Nucleon-Nucleon Correlations \& the EMC Effect

    Jennifer Rittenhouse West🇺🇸

    Diquark formation across a short-range nucleon-nucleon pair is proposed as the underlying QCD physics of short-range correlations (SRC) in nuclei. SRC pairs have been proposed as the cause of distorted quark behavior in nuclei; experimentally observed quark momentum distribution distortions termed the EMC effect. The strong spatial overlap of SRC pairs brings nucleon constituents within range of inter-nucleon QCD potentials and any bonds formed - such as the diquark bond - affects their distributions. In this SRC model, diquarks form in the channel of acting on valence quarks from highly overlapping nucleon wavefunctions. The most energetically favorable diquark is a valence quark from one nucleon with a valence quark from the other in a spin-0 state bound together via continual single gluon exchange and an attractive quantum chromodynamics short-range potential. Formation of a new scalar isospin-singlet diquark across a NN pair is proposed as the primary QCD-level theoretical foundation for SRC models of distorted structure functions in nuclei. Contributions from the higher mass spin-1 isospin triplet states , and are possible, with the spin-1 diquark proposed as a higher mass but viable structure function distortion mechanism for the spin-1 ground state deuteron. Predictions are made for lepton scattering experiments on and nuclear targets, with implications for the coefficients of the 3-valence quark Fock states in the nucleon wavefunction.

    ↳ hep-phastro-ph.HEnucl-thNPA(2023)·19 citations
  6. 06

    Proton fraction in neutron star matter: Dynamical mean-field approach

    Maxim Velikanov · Alexey N. Rubtsov · Boris Krippa

    Dynamical mean field theory (DMFT) is used to study neutron matter, both with and without admixture of the proton fraction. The system is approximated by the lattice Habbard model. The corresponding equation of state as a function of temperature/density/asymmetry is investigated. The results are compared with the standard mean field (MF) approach where the effect of local correlations is neglected. Whereas the influence of the correlations on the properties of a pure neutron matter is found to be moderate, it becomes strong when the proton admixture is taken into account. In particular, we calculate the proton fraction, energy density and pressure in outer core of neutron stars, taking into account the beta equilibrium condition. The DMFT predicts that the proton fraction is several times the MF based calculations, whereas the DMFT results for energy density and pressure are 30-40\% lower then the corresponding MF estimates. Physical implications of our findings for a neutron star dynamics are discussed.

    ↳ cond-mat.str-elnucl-thNew J.Phys.(2021)·1 citation
  7. 07

    Unified Interacting Quark Matter and its Astrophysical Implications

    Chen Zhang🇨🇦 · Robert B. Mann🇨🇦

    We investigate interacting quark matter (IQM), including the perturbative QCD correction and color superconductivity, for both up-down quark matter (QM) and strange quark matter (SQM). We first derive an equation of state (EOS) unifying all cases by a simple reparametrization and rescaling, through which we manage to maximally reduce the number of degrees of freedom. We find, in contrast to the conventional EOS for non-interacting quark matter, that taking the extreme strongly interacting limit on the unified IQM EOS gives , where is the effective bag constant. We employ the unified EOS to explore the properties of pure interacting quark stars (IQSs) composed of IQM. We describe how recent astrophysical observations, such as the pulsar-mass measurements, the NICER analysis, and the binary merger gravitational-wave events GW170817, GW190425, and GW190814, further constrain the parameter space. An upper bound for the maximum allowed mass of IQSs is found to be . Our analysis indicates a new possibility that the currently observed compact stars, including the recently reported GW190814's secondary component (), can be quark stars composed of interacting quark matter.

    ↳ astro-ph.HEgr-qchep-phnucl-thPRD(2021)·101 citations

Affiliations

first authorsco-authorsvia INSPIRE