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Nuclear Theory·nucl-th

Wednesday·June 9, 2021

15 papers—8 primary·7 cross-listed

All15Primary8Cross-lists7
  1. 09

    [Submitted on 6 Jun 2021] (cross-list from hep-lat)

    Lattice QCD Equation of State for Nonvanishing Chemical Potential by Resumming Taylor Expansion

    Sourav Mondal🇮🇳 · Swagato Mukherjee🇺🇸 · Prasad Hegde🇮🇳

    Taylor expansion in powers of baryon chemical potential () is an oft-used method in lattice QCD to compute QCD thermodynamics for . Based only upon the few known lowest order Taylor coefficients, it is difficult to discern the range of where such an expansion around can be trusted. We introduce a resummation scheme for the Taylor expansion of the QCD equation of state in that is based on the -point correlation functions of the conserved current (). The method resums the contributions of the first correlation function to the Taylor expansion of the QCD partition function to all orders in . We show that the resummed partition function is an approximation to the reweighted partition function at . We apply the proposed approach to high-statistics lattice QCD calculations using 2+1 flavors of Highly Improved Staggered Quarks with physical quark masses on lattices and for temperatures -176 MeV. We demonstrate that, as opposed to the Taylor expansion, the resummed version not only leads to improved convergence but also reflects the zeros of the resummed partition function and severity of the sign problem, leading to its eventual breakdown. We also provide a generalization of our scheme to include resummation of powers of temperature and quark masses in addition to , and show that the alternative expansion scheme of [S. Borsányi et al., Phys. Rev. Lett. 126, 232001 (2021).] is a special case of this generalized resummation.

    Comments:
    Resubmitted to match with the journal version of the paper
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2106.03165 [pdf]
    PRL(2022)·45 citations
  2. 10

    [Submitted on 7 Jun 2021] (cross-list from hep-ph)

    Partonic collinear structure by quantum computing

    Tianyin Li🇨🇳 · Xingyu Guo🇨🇳 · Wai Kin Lai🇨🇳 · Xiaohui Liu🇨🇳 · Enke Wang🇨🇳 · Hongxi Xing🇨🇳 · Dan-Bo Zhang🇨🇳 · Shi-Liang Zhu🇨🇳

    We present a systematic quantum algorithm, which integrates both the hadronic state preparation and the evaluation of real-time light-front correlators, to study parton distribution functions (PDFs). As a proof of concept, we demonstrate the first direct simulation of the PDFs in the 1+1 dimensional Nambu-Jona-Lasinio model. We show the results obtained by exact diagonalization and by quantum computation using classical hardware. The agreement between these two distinct methods and the qualitative consistency with QCD PDFs validate the proposed quantum algorithm. Our work suggests the encouraging prospects of calculating QCD PDFs on current and near-term quantum devices. The presented quantum algorithm is expected to have many applications in high energy particle and nuclear physics.

    Comments:
    6 pages, 3 figures, published version in PHYSICAL REVIEW D (Letter)
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    2106.03865 [pdf]
    PRD(2022)·76 citations
  3. 11

    [Submitted on 7 Jun 2021] (cross-list from hep-lat)

    Bayesian-Wilson coefficients in lattice QCD computations of valence PDFs and GPDs

    Nikhil Karthik🇺🇸 · Raza Sabbir Sufian🇺🇸

    We propose an analysis method for the leading-twist operator product expansion based lattice QCD determinations of the valence parton distribution function (PDF). In the first step, we determine the confidence-intervals of the leading-twist Wilson coefficients, , of the equal-time bilocal quark bilinear, given the lattice QCD matrix element of Ioffe-time distribution for a particular hadron as well as the prior knowledge of the valence PDF, of the hadron determined via global fit from the experimental data. In the next step, we apply the numerically estimated in the lattice QCD determinations of the valence PDFs of other hadrons, and for the zero-skewness generalized parton distribution (GPD) of the same hadron at non-zero momentum transfers. Our proposal still assumes the dominance of leading-twist terms, but it offers a pragmatic alternative to the usage of perturbative Wilson coefficients and their associated higher-loop uncertainties such as the effect of all-order logarithms at larger sub-Fermi quark-antiquark separations .

    Comments:
    13 pages, 5 figures; published version
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2106.03875 [pdf]
    PRD(2021)·9 citations
  4. 12

    [Submitted on 7 Jun 2021] (cross-list from hep-ph)

    Orbital Angular Momentum Distribution of Gluons at Small- : Analytic interpolation between Ji and Jaffe-Manohar

    Raktim Abir🇮🇳 · Khatiza Banu🇮🇳 · Nahid Vasim🇮🇳

    In this work, we first introduced a generalized Wilson line gauge link that reproduces both staple and near straight links along the light cone in different parameter limits. We then studied the gauge-invariant bi-local orbital angular momentum operator with such a general gauge link, in the framework of Chen et. al. decomposition of gauge fields. At the appropriate combination of limits, the operator reproduces both Jaffe-Manohar and Ji's operator structure and offers a continuous analytical interpolation between the two.

    Comments:
    13 pages, 3 figures, version to appear in Physical Review D
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    2106.03896 [pdf]
    PRD(2022)·8 citations
  5. 13

    [Submitted on 8 Jun 2021] (cross-list from nucl-ex)

    Measurement and Modeling of Proton-Induced Reactions on Arsenic from 35 to 200 MeV

    Morgan B. Fox🇺🇸 · Andrew S. Voyles🇺🇸 · Jonathan T. Morrell🇺🇸 · Lee A. Bernstein🇺🇸 · Jon C. Batchelder🇺🇸 · Eva R. Birnbaum🇺🇸 · Cathy S. Cutler🇺🇸 · Arjan J. Koning🇦🇹 · Amanda M. Lewis🇺🇸 · Dmitri G. Medvedev🇺🇸 · Francois M. Nortier🇺🇸 · Ellen M. O'Brien🇺🇸 · Christiaan Vermeulen🇺🇸

    As is a promising positron emitter for diagnostic imaging that can be employed locally using a Se generator. However, current reaction pathways to Se have insufficient nuclear data for efficient production using regional 100-200 MeV high-intensity proton accelerators. In order to address this deficiency, stacked-target irradiations were performed at LBNL, LANL, and BNL to measure the production of the Se/As PET generator system via As(p,x) between 35 and 200 MeV. This work provides the most well-characterized excitation function for As(p,4n)Se starting from threshold. Additional focus was given to report the first measurements of As(p,x)Ge and bolster an already robust production capability for the highly valuable Ge/Ga PET generator. Thick target yield comparisons with prior established formation routes to both generators are made. In total, high-energy proton-induced cross sections are reported for 55 measured residual products from As, Cu, and Ti targets, where the latter two materials were present as monitor foils. These results were compared with literature data as well as the default theoretical calculations of the nuclear model codes TALYS, CoH, EMPIRE, and ALICE. Reaction modeling at these energies is typically unsatisfactory due to few prior published data and many interacting physics models. Therefore, a detailed assessment of the TALYS code was performed with simultaneous parameter adjustments applied according to a standardized procedure. Particular attention was paid to the formulation of the two-component exciton model in the transition between the compound and pre-equilibrium regions, with a linked investigation of level density models for nuclei off of stability and their impact on modeling predictive power.

    Comments:
    35 pages (+5 for references), 69 figures, preprint prepared for Physical Review Journals, minor revisions for references to recently published work
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2106.04115 [pdf]
    PRC(2021)·13 citations
  6. 14

    [Submitted on 8 Jun 2021] (cross-list from hep-ph)

    From quarks and gluons to color superconductivity at supranuclear densities

    Jens Braun🇩🇪 · Benedikt Schallmo🇩🇪

    We study the emergence of color superconductivity in the theory of the strong interaction at supranuclear densities. To this end, we follow the renormalization group (RG) flow of dense strong-interaction matter with two massless quark flavors from the fundamental quark and gluon degrees of freedom at high energies down to the non-perturbative low-energy regime which is found to be governed by the dynamical formation of diquark states. With the strong coupling at the initial RG scale as the only input parameter, we compute the (chirally symmetric) scalar diquark condensate and analyze its scaling behavior over a wide range of the quark chemical potential. Approximations entering our computations are critically assessed. Since our approach naturally allows us to study the scale dependence of couplings, we also monitor the strength of couplings appearing in low-energy models of dense strong-interaction matter. The observed dependence of these couplings on the quark chemical potential may help to amend model studies in the future. Finally, we estimate the speed of sound of dense QCD matter. Our results indicate that the speed of sound exceeds the value of the noninteracting quark gas at high densities and even increases as the density is decreased, across a wide range, suggesting the existence of a maximum at supranuclear densities.

    Comments:
    22 pages, 5 figures; v2: typos fixed, comments and references added, one section added, two figures added, two appendices added
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2106.04198 [pdf]
    PRD(2022)·38 citations
  7. 15

    [Submitted on 8 Jun 2021] (cross-list from physics.atom-ph)

    Relativistic Fock space coupled cluster study of bismuth electronic structure to extract the Bi nuclear quadrupole moment

    L.V. Skripnikov · A.V. Oleynichenko · A.V. Zaitsevskii · D.E. Maison · A.E. Barzakh

    We report the value of the electric quadrupole moment of Bi extracted from the atomic data. For this, we performed electronic structure calculations for the ground and excited states of atomic Bi using the Dirac-Coulomb-Breit Hamiltonian and the Fock space coupled cluster method with single, double, and full triple amplitudes for the three-particle Fock space sector. The value of the quadrupole moment of Bi, Bi~mb, derived from the resulting electric field gradient values and available atomic hyperfine splittings is in excellent agreement with molecular data. Due to the availability of the hyperfine constants for unstable isotopes of Bi, current atomic calculation allows also to correct their quadrupole moments.

    Subjects:
    Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th); physics.chem-ph (physics.chem-ph)
    arXiv:
    2106.04308 [pdf]
    PRC(2021)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE