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Nuclear Theory·nucl-th

Wednesday·June 30, 2021

10 papers—6 primary·4 cross-listed

All10Primary6Cross-lists4
  1. 07

    [Submitted on 28 Jun 2021] (cross-list from hep-ph)

    Angularity in DIS at next-to-next-to-leading log accuracy

    Jiawei Zhu🇨🇳 · Daekyoung Kang🇨🇳 · Tanmay Maji🇨🇳

    Angularity is a class of event-shape observables that can be measured in deep-inelastic scattering. With its continuous parameter one can interpolate angularity between thrust and broadening and further access beyond the region. Providing such systematic way to access various observables makes angularity attractive in analysis with event shapes. We give the definition of angularity for DIS and factorize the cross-section by using soft-collinear effective theory. The factorization is valid in a wide range of below and above thrust region but invalid in broadening limit. It contains an angularity beam function, which is new result and we give the expression at . We also perform large log resummation of angularity and make predictions at various values of at next-to-next-to-leading log accuracy.

    Comments:
    37 pages, 7 figuers, 1 table
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2106.14429 [pdf]
    JHEP(2021)·16 citations
  2. 08

    [Submitted on 29 Jun 2021] (cross-list from quant-ph)

    Porter-Thomas fluctuations in complex quantum systems

    K. Hagino🇯🇵 · G.F. Bertsch🇺🇸

    The Gaussian Orthogonal Ensemble (GOE) of random matrices has been widely employed to describe diverse phenomena in strongly coupled quantum systems. An important prediction is that the decay rates of the GOE eigenstates fluctuate according to the distribution for one degree of freedom, as derived by Brink and by Porter and Thomas. However, we find that the coupling to the decay channels can change the effective number of degrees of freedom from to . Our conclusions are based on a configuration-interaction Hamiltonian originally constructed to test the validity of transition-state theory, also known as Rice-Ramsperger-Kassel-Marcus (RRKM) theory in chemistry. The internal Hamiltonian consists of two sets of GOE reservoirs connected by an internal channel. We find that the effective number of degrees of freedom can vary from one to two depending on the control parameter , where is the level density in the first reservoir and is the level decay width. The distribution is a well-known property of the Gaussian Unitary ensemble (GUE); our model demonstrates that the GUE fluctuations can be present under much milder conditions. Our treatment of the model permits an analytic derivation for .

    Comments:
    7 pages, 3 figures
    Subjects:
    Quantum Physics (quant-ph); Nuclear Theory (nucl-th); physics.chem-ph (physics.chem-ph)
    arXiv:
    2106.15251 [pdf]
    PRE(2021)·10 citations
  3. 09

    [Submitted on 29 Jun 2021] (cross-list from hep-ph)

    Phenomenological study of quarkonium suppression and the impact of the energy gap between singlets and octets

    Jean-Paul Blaizot🇫🇷 · Miguel Ángel Escobedo🇪🇸

    The study of heavy quarkonium suppression in heavy-ion collisions represents an important source of information about the properties of the quark-gluon plasma produced in such collisions. In a previous paper, we have considered how to model the evolution of a quarkonium in such a way that the solution of the resulting equations evolves toward the correct thermal equilibrium distribution for an homogeneous and static medium. We found that it is crucial to take into account the energy gap between singlet and octet configurations when the temperature is not much greater than this energy gap. In this manuscript, we explore in more detail the phenomenological consequences of this observation in the more realistic situation of an expanding system. We consider two different scenarios, based on the same approximation scheme, but on different choices of parameters. In the first case, we rely on a Hard Thermal Loop approximation, while the second case is based on a recent determination of the static potential in lattice QCD. In both cases, we compute the decay width and the nuclear modification factor, both taking the energy gap into account and ignoring it. We find that the impact on the predictions is as large in the expanding medium as it is in the static case. Our conclusion is that this energy gap should be taken into account in phenomenological studies.

    Comments:
    Published version. 25 pages, 11 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2106.15371 [pdf]
    PRD(2021)·27 citations
  4. 10

    [Submitted on 29 Jun 2021] (cross-list from nucl-ex)

    Two- and three-particle nonflow contributions to the chiral magnetic effect measurement by spectator and participant planes in relativistic heavy ion collisions

    Yicheng Feng🇺🇸 · Jie Zhao🇺🇸 · Hanlin Li🇨🇳 · Hao-jie Xu🇨🇳 · Fuqiang Wang🇺🇸

    Correlation measurements with respect to the spectator and participant planes in relativistic heavy ion collisions were proposed to extract the chiral magnetic effect (CME) from background dominated azimuthal correlators. This paper investigates the effects of two- and three-particle nonflow correlations on the extracted CME signal fraction, . It is found, guided by a multiphase transport (AMPT) model and the heavy ion jet interaction generator (HIJING) together with experimental data, that the nonflow effects amount to approximately % and % without and with pseudorapidity gaps, respectively, in 20-50% centrality Au+Au collisions at .

    Comments:
    11 pages, 9 figures, 1 table
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2106.15595 [pdf]
    PRC(2022)·33 citations

Affiliations

first authorsco-authorsvia INSPIRE