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Nuclear Theory·nucl-th

Friday·March 1, 2024

15 papers—8 primary·7 cross-listed

All15Primary8Cross-lists7
  1. 09

    Analytic solutions for the linearized first-order magnetohydrodynamics and implications for causality and stability

    Zhe Fang🇨🇳 · Koichi Hattori🇨🇳 · Jin Hu🇨🇳

    We address the linear-mode analysis performed near an equilibrium configuration in the fluid rest frame with a dynamical magnetic field perturbed on a constant configuration. We develop a simple and general algorithm for an analytic solution search that works on an order-by-order basis in the derivative expansion. This method can be applied to general sets of hydrodynamic equations. Applying our method to the first-order relativistic magnetohydrodynamics, we demonstrate that the method finds a complete set of solutions. We obtain two sets of analytic solutions for the four and two coupled modes with seven dissipative transport coefficients. The former set has been missing in the literature for a long time due to the difficulties originating from coupled degrees of freedom and strong anisotropy provided by a magnetic field. The newly developed method resolves these difficulties. We also find that the small-momentum expansions of the solutions break down when the momentum direction is nearly perpendicular to an equilibrium magnetic field due to the presence of another small quantity, that is, a trigonometric function representing the anisotropy. We elaborate on the angle dependence of the solutions and provide alternative series representations that work near the right angle. This identifies the origin of a discrepancy found in recent works. Finally, we discuss the issues of causality and stability based on our analytic solutions and recent developments in the literature.

    ↳ physics.plasm-phastro-ph.HEgr-qchep-ph+1PRD(2024)·15 citations
  2. 10

    Exploring the distribution and impact of bosonic dark matter in neutron stars

    Davood Rafiei Karkevandi🇮🇷 · Mahboubeh Shahrbaf🇵🇱 · Soroush Shakeri🇮🇷 · Stefan Typel🇩🇪

    The presence of dark matter (DM) within neutron stars (NSs) can be introduced by different accumulation scenarios in which DM and baryonic matter (BM) may interact only through the gravitational force. In this work, we consider asymmetric self-interacting bosonic DM which can reside as a dense core inside the NS or form an extended halo around it. It is seen that depending on the boson mass (), self-coupling constant () and DM fraction (), the maximum mass, radius and tidal deformability of NSs with DM admixture will be altered significantly. The impact of DM causes some modifications in the observable features induced solely by the BM component. Here, we focus on the widely used nuclear matter equation of state (EoS) called DD2 for describing NS matter. We show that by involving DM in NSs, the corresponding observational parameters will be changed to be consistent with the latest multi-messenger observations of NSs. It is seen that for MeV and , DM admixed NSs with are consistent with the maximum mass and tidal deformability constraints.

    ↳ astro-ph.HEnucl-thParticles(2024)·41 citations
  4. 12

    QCD at Finite Temperature and Density -- Equation of State

    Jamie M. Karthein🇺🇸

    As an important set of thermodynamic quantities, knowledge of the equation of state over a broad range of temperatures and chemical potentials in the QCD phase diagram is crucial for our understanding of strongly-interacting matter. There is a good understanding from first-principles results in lattice QCD, perturbative QCD and chiral effective field theory about the equation of state. However, these approaches are valid in different regimes of the phase diagram, and therefore, a method of providing an equation of state that covers a full range of the phase diagram involves matching together these results with appropriate models in order to fill in the gaps between these regions. Furthermore, with such equations of state, important questions about QCD phase structure can begin to be addressed, such as whether there is a critical point in the QCD phase diagram. In this contribution to the proceedings, equations of state from first-principles and effective theories will be discussed in order to understand how QCD thermodynamics is affected by the presence of a critical point.

    ↳ hep-phnucl-thEPJ Web Conf.(2024)·1 citation
  5. 13

    B-mesons as essential probes of hot QCD matter

    Vinod Chandra🇮🇳 · Santosh K. Das🇮🇳

    This article elucidates the pivotal role of b-mesons and bottomonium states in exploring the existence and properties of hot QCD matter (commonly known as quark-gluon-plasma (QGP) produced within the crucible heavy-ion collision experiments). Owing to the complex and confounding nature of strong interaction force the direct detection of probing the hot QCD matter is not feasible. In light of this, investigating the dynamics of b-quarks and anti-quarks within the hot QCD medium emerges as an invaluable indirect probe. The impact of b-quarks and the mesons spans a spectrum of interesting domains regarding the physics of QCD at finite temperature, encompassing the QCD phase transition, color screening, quarkonia dissociation, heavy quark energy loss and collective flow, anisotropic aspects, and strongly coupled nature of hot QCD medium. These aspects underscore the indispensable nature of B-mesons in the quest to create and explore the complex nature of strong interaction force through the QGP/hot QCD matter. In this context, we mainly focus on works related to transport studies of b-mesons in hot QCD medium, lattice QCD, and effective field theory studies on bottomonium states, and finally, open quantum system frameworks to quarkonia to explore the properties of hot QCD medium in relativistic heavy-ion collision experiments.

    ↳ hep-phnucl-thEur.Phys.J.ST(2024)·7 citations
  6. 14

    Nuclear medium meson structures from the Schwinger proper-time Nambu--Jona-Lasinio model

    Geoffry Gifari🇮🇩 · Parada T. P. Hutauruk🇰🇷 · Terry Mart🇮🇩

    In this paper, we report the results of our study on the nuclear medium modifications of the meson electromagnetic form factors in the framework of the Nambu--Jona-Lasinio (NJL) model with the help of the Schwinger proper-time regularization scheme to tame the loop divergence and simulate the effect of QCD confinement. In our current approach, the meson structure and nuclear medium are constructed in the same NJL model at the quark level. We examine the free-space and in-medium charge radii of kaon and pion, the spacelike elastic electromagnetic form factors of kaon and pion, and their quark-sector form factors, which reflect their internal structures. By comparing our result to experimental data, we found that the free-space elastic electromagnetic form factors of the mesons are consistent with the data, while the in-medium elastic electromagnetic form factors of the mesons are found to decrease as the nuclear matter density increases, leading to a rise of meson charge radius, which is consistent with the prediction of other theoretical calculations. We also predict the axial nucleon coupling constant in nuclear medium computed via the Goldberger-Treiman relation (GTR), which is crucial for searching the neutrinoless double beta decay ().

    ↳ hep-phnucl-thPRD(2024)·17 citations
  7. 15

    Revisiting model at unphysical pion masses and high temperatures

    Yuan-Lin Lyu🇨🇳 · Qu-Zhi Li🇨🇳 · Zhiguang Xiao🇨🇳 · Han-Qing Zheng🇨🇳

    Roy-equation analyses on lattice data of scattering phase shifts at MeV reveals that the lowest meson becomes a bound state under this condition. In addition, there is a pair of complex poles below threshold generated by crossing symmetry [X.-H. Cao et al., Phys. Rev. D 108, 034009 (2023)]. We use the method to partially recover crossing symmetry of the model amplitude at leading order of expansion, and qualitatively reproduce the pole structure and pole trajectories with varying pion masses as revealed by Roy-equation analyses. The pole trajectory with varying temperature is also discussed and found to be similar to its properties when varying . As the temperature increases, the complex poles firstly move from the second Riemann sheet to the real axis becoming two virtual state poles, and then one virtual state pole moves to the first sheet turning into a bound state pole and finally tends to the pion pole position at high temperature which is as expected from the chiral symmetry restoration. Our results provide further evidences that the lowest state extracted from experiments and lattice data plays the role of meson in the spontaneous breaking of chiral symmetry. Finally, we also briefly discuss the problems of the effective potential in the situation when and temperature get large.

    ↳ hep-phhep-lathep-thnucl-thPRD(2024)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE