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Nuclear Theory·nucl-th

Tuesday·August 27, 2024

11 papers—6 primary·5 cross-listed

All11Primary6Cross-lists5
  1. 07

    [Submitted on 23 Aug 2024] (cross-list from hep-lat)

    Neutral pion polarizabilities from four-point functions in lattice QCD

    Frank X. Lee🇺🇸 · Walter Wilcox🇺🇸 · Andrei Alexandru🇺🇸 · Chris Culver🇬🇧 · Shayan Nadeem🇺🇸

    We report a proof-of-principle lattice QCD simulation of the electric and magnetic polarizabilities for a neutral pion in the four-point function method. The results are based on the same quenched Wilson ensembles on a lattice at with pion mass from 1100 to 370 MeV previously used for a charged pion. For electric polarizability, the results are largely consistent with those from the background field method and ChPT. In contrast, there are significant differences for magnetic polarizability among the four-point function method, the background field method, and ChPT. The situation points to the potentially important role of disconnected diagrams for a neutral pion. We elucidate a transparent quark decomposition in the four-point function method that can be used to shed light on the issue.

    Comments:
    11 pages, 9 figures, 1 table. This version matches the one published in NPB in content. arXiv admin note: text overlap with arXiv:2307.08620
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2408.13388 [pdf]
    NPB(2024)·5 citations
  2. 08

    [Submitted on 26 Aug 2024] (cross-list from hep-ph)

    The effect of vorticity on the dynamical magnetic fields in heavy-ion collisions

    Anping Huang🇨🇳 · Xiang-Yu Wu🇨🇦 · Mei Huang🇨🇳

    Magnetic fields in heavy-ion collisions are pivotal and subject to diverse factors. In this study, we quantitatively investigate the impact of fluid vorticity on the evolution of magnetic fields in the 20-50\% centrality class in Au+Au collisions, with collision energies of GeV. Our results indicate that fluid vorticity leads to a delay in the evolution of the magnetic field, in which this effect becomes more pronounced as the collision energy decreases. Additionally, we have calculated the mean magnetic field values on the freeze-out hypersurface for various collision energies. Our simulation results align with the values inferred from experimental data of , within the error margins.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2408.14077 [pdf]
    PRD(2024)·6 citations
  3. 09

    [Submitted on 26 Aug 2024] (cross-list from astro-ph.HE)

    Cosmology and nuclear-physics implications of a subsolar gravitational-wave event

    Francesco Crescimbeni🇮🇹 · Gabriele Franciolini🇨🇭 · Paolo Pani🇮🇹 · Massimo Vaglio🇮🇹

    Detecting a compact subsolar object would have profound implications in physics, the reach of which depends on the nature of the object. Here we explore such consequences for a putative subsolar-mass gravitational wave event detected by the LIGO-Virgo-KAGRA Collaboration. We forecast that the nature of a subsolar binary (made of light neutron stars, primordial black holes, or more exotic compact objects) can be inferred with a great statistical confidence level already during the ongoing fourth observing run, based on the large tidal deformability effects on the signal. The detection of a primordial black hole would have implications for cosmology and dark matter scenarios, while the measurement of the tidal deformability of a subsolar neutron star could rule out or confirm the existence of strange stars made of quarks.

    Comments:
    5+4 pages, 3 figures; v2: matching published version
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2408.14287 [pdf]
    PRD(2025)·19 citations
  4. 10

    [Submitted on 26 Aug 2024] (cross-list from hep-ph)

    Relativistic spin hydrodynamics with momentum and spin-dependent relaxation time

    Samapan Bhadury🇵🇱

    Using the extended relaxation time approximation (ERTA) along with the theory of semi-classical spin, we develop a framework of relativistic dissipative spin hydrodynamics such that the relaxation time can depend on the momenta and spin of the constituent spin-1/2 particles. We also consider a general definition of the fluid four-velocity allowing the theory to be valid in a general frame and matching conditions. Consequently, we construct the frame-invariant bulk, shear, particle diffusion, and spin transport coefficients, showing that the evolution of fluid remains unaffected by spin in the limit of small polarization as was the case where the relaxation time was independent of spin or momentum.

    Comments:
    14 pages
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2408.14462 [pdf]
    PRC(2025)·18 citations
  5. 11

    [Submitted on 26 Aug 2024] (cross-list from quant-ph)

    Unitary Designs from Random Symmetric Quantum Circuits

    Hanqing Liu🇺🇸 · Austin Hulse🇺🇸 · Iman Marvian🇺🇸

    In this work, we study distributions of unitaries generated by random quantum circuits containing only symmetry-respecting gates. We develop a unified approach applicable to all symmetry groups and obtain an equation that determines the exact design properties of such distributions. It has been recently shown that the locality of gates imposes various constraints on realizable unitaries, which in general, significantly depend on the symmetry under consideration. These constraints typically include restrictions on the relative phases between sectors with inequivalent irreducible representations of the symmetry. We call a set of symmetric gates semi-universal if they realize all unitaries that respect the symmetry, up to such restrictions. For instance, while 2-qubit gates are semi-universal for , U(1), and SU(2) symmetries in qubit systems, SU(d) symmetry with requires 3-qudit gates for semi-universality. Failure of semi-universality precludes the distribution generated by the random circuits from being even a 2-design for the Haar distribution over symmetry-respecting unitaries. On the other hand, when semi-universality holds, under mild conditions, satisfied by U(1) and SU(2) for example, the distribution becomes a -design for growing polynomially with the number of qudits, where the degree is determined by the locality of gates. More generally, we present a simple linear equation that determines the maximum integer for which the uniform distribution of unitaries generated by the circuits is a -design for all . Notably, for U(1), SU(2) and cyclic groups, we determine the exact value of as a function of the number of qubits and locality of the gates, and for SU(d), we determine the exact value of for up to -qudit gates.

    Comments:
    V2 includes new results on SU(d) symmetry and proof of some previously conjectured combinatorial identities. 33 pages + 28 pages of Appendices, 3 Figs. Comments welcome!
    Subjects:
    Quantum Physics (quant-ph); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Theory (hep-th); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th)
    arXiv:
    2408.14463 [pdf]
    18 citations

Affiliations

first authorsco-authorsvia INSPIRE