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Nuclear Theory·nucl-th

Tuesday·May 16, 2023

13 papers—8 primary·5 cross-listed

All13Primary8Cross-lists5
  1. 09

    [Submitted on 26 Sept 2022] (cross-list from hep-ph)

    The Equation of State with the EPOS3 model

    Maria Stefaniak🇵🇱 · Klaus Werner🇫🇷 · Johannes Jahan🇫🇷 · Hanna Zbroszczyk🇵🇱

    Transitions between different states of matter and their thermodynamic properties are described by the Equation of State (EoS). A universal representation of the EoS of Quantum Chromodynamics (QCD) for the wide range of phase diagram has yet to be determined. The expectation of the systems to undergo various types of transitions depending on the temperature (T), the chemical potential ({\mu}B), and other thermodynamic features make solving that puzzle challenging. Furthermore, it needs to be apparent which experimentally measurable observables could provide helpful information for determining EoS. The application of different EoS for hydrodynamical evolution was introduced in the EPOS3 generator, which allows one to study its changing effect on the experimental observables. The family of EoS proposed by the BEST Collaboration was implemented. The Critical Point (CP) location and the strength of criticality variations were investigated with particle yield, transverse momentum spectra, flow, and moments of the net-proton distributions.

    Comments:
    9 pages
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    2209.12979 [pdf]
    PRC(2023)·5 citations
  2. 10

    [Submitted on 12 May 2023] (cross-list from hep-th)

    The Hydrohedron: Bootstrapping Relativistic Hydrodynamics

    Michal P. Heller🇧🇪 · Alexandre Serantes🇪🇸 · Michał Spaliński🇵🇱 · Benjamin Withers🇬🇧

    As an effective theory, relativistic hydrodynamics is fixed by symmetries up to a set of transport coefficients. A lot of effort has been devoted to explicit calculations of these coefficients. Here we propose a shift in perspective: we deploy bootstrap techniques to rule out theories that are inconsistent with microscopic causality. What remains is a universal convex geometry in the space of transport coefficients, which we call the hydrohedron. The landscape of all consistent theories necessarily lie inside or on the edges of the hydrohedron. We analytically construct cross-sections of the hydrohedron corresponding to bounds on transport coefficients that appear in sound and diffusion modes for theories without stochastic fluctuations.

    Comments:
    10 pages + appendices, 2 figures. Added N=4 SYM, MIS, BDNK, kinetic theory to the hydrohedron plots. Some technical details moved to appendices
    Subjects:
    High Energy Physics — Theory (hep-th); Statistical Mechanics (cond-mat.stat-mech); General Relativity and Quantum Cosmology (gr-qc); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th)
    arXiv:
    2305.07703 [pdf]
    Nat.Phys.(2024)·45 citations
  3. 11

    [Submitted on 13 May 2023] (cross-list from hep-ph)

    Charm content of the proton: An analytic calculation

    A. R. Olamaei🇮🇷 · S. Rostami🇮🇷 · K. Azizi🇮🇷

    According to general understanding, the proton as one of the main ingredients of the nucleus is composed of one down and two up quarks bound together by gluons, described by Quantum Chromodynamics (QCD). In this view, heavy quarks do not contribute to the primary wave function of the proton. Heavy quarks arise in the proton perturbatively by gluon splitting and the probability gradually increases as increases (extrinsic heavy quarks). In addition, the existence of non-perturbative intrinsic charm quarks in the proton has also been predicted by QCD. In this picture, the heavy quarks also exist in the proton's wave function. In fact, the wave function has a five-quark structure in addition to the three-quark bound state . So far, many studies have been done to confirm or reject this additional component. One of the recent studies has been done by the NNPDF collaboration. They established the existence of an intrinsic charm component at the 3-standard-deviation level in the proton from the structure function measurements. Most of the studies performed to calculate the contribution of the intrinsic charm so far have been based on the global analyses of the experimental data. In this article, for the first time we directly calculate this contribution by an analytic method. We estimate a contribution for the component of the proton.

    Comments:
    6 Pages and 2 Figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    2305.07999 [pdf]
    PRD(2023)·2 citations
  4. 12

    [Submitted on 15 May 2023] (cross-list from hep-ph)

    The QED of Bernabéu-Tarrach sumrule for electric polarizability and its implication for the Lamb shift

    Volodymyr Biloshytskyi🇩🇪 · Iulian Ciobotaru-Hriscu🇩🇪 · Franziska Hagelstein🇩🇪 · Vadim Lensky🇩🇪 · Vladimir Pascalutsa🇩🇪

    We attempt to rehabilitate a sum rule (proposed long ago by Bernabéu and Tarrach) which relates the electric polarizability of a particle to the total photoabsorption of quasi-real longitudinally polarized photons by that particle. We discuss its perturbative verification in QED, which is largely responsible for the scepticism about its validity. The failure of the QED test can be understood via the Sugawara-Kanazawa theorem and is due to the non-vanishing contour contribution in the pertinent dispersion relation. We show another example where this contribution is absent and the perturbative test works exactly. On the empirical side, we show that the sum rule gives a reasonable estimate of the -channel contribution to the proton electric polarizability. If this sum rule is valid indeed, there should be a sum rule for the so-called ``subtraction function'' entering the data-driven calculations of the polarizability effects in the Lamb shift. We have written down a possible sum rule for the subtraction function and verified it in a perturbative calculation.

    Comments:
    7 pages, 4 figures, revised and extended version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
    arXiv:
    2305.08814 [pdf]
    PRD(2024)·4 citations
  5. 13

    [Submitted on 15 May 2023] (cross-list from cond-mat.quant-gas)

    Neural-network quantum states for ultra-cold Fermi gases

    Jane Kim · Gabriel Pescia · Bryce Fore · Jannes Nys · Giuseppe Carleo · Stefano Gandolfi · Morten Hjorth-Jensen · Alessandro Lovato

    Ultra-cold Fermi gases display diverse quantum mechanical properties, including the transition from a fermionic superfluid BCS state to a bosonic superfluid BEC state, which can be probed experimentally with high precision. However, the theoretical description of these properties is challenging due to the onset of strong pairing correlations and the non-perturbative nature of the interaction among the constituent particles. This work introduces a novel Pfaffian-Jastrow neural-network quantum state that includes backflow transformation based on message-passing architecture to efficiently encode pairing, and other quantum mechanical correlations. Our approach offers substantial improvements over comparable ansätze constructed within the Slater-Jastrow framework and outperforms state-of-the-art diffusion Monte Carlo methods, as indicated by our lower ground-state energies. We observe the emergence of strong pairing correlations through the opposite-spin pair distribution functions. Moreover, we demonstrate that transfer learning stabilizes and accelerates the training of the neural-network wave function, enabling the exploration of the BCS-BEC crossover region near unitarity. Our findings suggest that neural-network quantum states provide a promising strategy for studying ultra-cold Fermi gases.

    Comments:
    12 pages, 6 figures
    Subjects:
    Quantum Gases (cond-mat.quant-gas); cond-mat.dis-nn (cond-mat.dis-nn); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    2305.08831 [pdf]
    Commun.Phys.(2024)·58 citations

Affiliations

first authorsco-authorsvia INSPIRE