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Nuclear Theory·nucl-th

Thursday·March 7, 2019

14 papers—8 primary·6 cross-listed

All14Primary8Cross-lists6
  1. 09

    Factorization of jet cross sections in heavy-ion collisions

    Jian-Wei Qiu🇺🇸 · Felix Ringer🇺🇸 · Nobuo Sato🇺🇸 · Pia Zurita🇩🇪

    We propose a new phenomenological approach to establish QCD factorization of jet cross sections in the heavy-ion environment. Starting from a factorization formalism in proton-proton collisions, we introduce medium modified jet functions to capture the leading interaction of jets with the hot and dense QCD medium. A global analysis using a Monte Carlo sampling approach is performed in order to reliably determine the new jet functions from the nuclear modification factor of inclusive jets at the LHC. We find that gluon jets are significantly more suppressed due to the presence of the medium than quark jets. In addition, we observe that the jet radius dependence is directly related to the relative suppression of quark and gluon jets. Our approach may help to improve the extraction of medium properties from data.

    ↳ hep-phhep-exnucl-exnucl-thPRL(2019)·65 citations
  2. 10

    A semi-classical transport equation for the chiral quarks surrounding a SU(2) t'Hooft-Polyakov monopole

    Feng Li🇩🇪

    A transport equation of the representative quasi-particles is derived, by solving Dirac (or Dyson) equations under the semi-classical approximation, for describing the entangled motions of the red and blue chiral quarks in the vicinity of a SU(2) t'Hooft-Polyakov monopole. The representative quasi-particles have two states characterized by different dispersion relations. A ground state quasi-particle has a zero pole mass, a zero longitudinal inertial mass and a finite transverse inertial mass, while an excited quasi-particle has a finite pole mass and finite inertial masses. At equilibrium, the red and blue currents flow against each other in the transverse direction, and the red and blue axial currents flow against each other in the radial direction.

    ↳ hep-thnucl-th0 citations
  3. 11

    Bayesian techniques and applications to QCD

    Alexander Rothkopf🇳🇴

    Realizing the full potential of interconnecting the large amounts of data created in physics experiments, phenomenological models and theory simulations requires robust tools for statistical inference. Here I review a particularly promising branch, Bayesian statistics, which over the past decade has found manifold use in high-energy physics. After a brief introduction to Bayesian statistics I will present two concrete examples, where Bayesian thinking has led to progress in understanding strongly interacting matter: unfolding problems in the form of lattice QCD spectral functions (in spirit similar to detector corrections), as well as the efficient estimation of quark-gluon-plasma parameters from a systematic comparison of experimental heavy-ion collision data and phenomenological models.

    ↳ hep-phnucl-thphysics.data-anPoS(2018)·12 citations
  4. 12

    In-medium heavy quarkonium from lattice NRQCD

    Seyong Kim🇰🇷 · Peter Petreczky🇺🇸 · Alexander Rothkopf🇳🇴

    We present the final results from a multi-year study of the in-medium spectral properties of heavy quarkonium bound states on the lattice. In this work we combine high statistics ensembles from the HotQCD collaboration with the effective theory NRQCD and improved Bayesian spectral reconstruction methods. We corroborate with high precision the hierarchical in-medium modification of quarkonium states with respect to their vacuum binding energy and provide updated values on melting temperatures. In particular we are able to understand previous disagreements between different Bayesian methods as resulting from underestimated systematic uncertainties. The main quantitative result is a robust determination of the in-medium mass shifts of quarkonium ground states, which we find are negative, consistent with the behavior observed in strongly coupled pNRQCD potential based computations.

    ↳ hep-lathep-phnucl-thPoS(2019)·0 citations
  5. 13

    Hadron tomography for pion and its gravitational form factors

    Qin-Tao Song🇯🇵

    Generalized parton distributions (GPDs) are three-dimensional structure functions of hadrons, and they can reveal the orbital-angular-momentum contributions to the nucleon spin. Therefore, GPDs are important for solving the proton spin puzzle. The generalized distribution amplitudes (GDAs) are the - crossed quantities of the GPDs, and the GDAs can be investigated in two-photon process () which is accessible at KEKB. The pion GDAs were obtained by analyzing the Belle measurements for production in the collision. From the obtained GDAs, the form factors of energy-momentum tenor were calculated for pion in the timelike region. In order to study the gravitational radii for the pion, the form factors of energy-momentum tenor were obtained in the spacelike region by using the dispersion relation. Then, the mass radius was calculated as 0.32 0.39 fm and the mechanical radius was also estimated for the pion as 0.82 0.88 fm by using the spacelike form factors. This is the first finding on gravitational form factors and radii of hadrons from actual experimental measurements. In the near future we can expect more precise measurements of as the Belle II started data taking by the higher luminosity Super KEKB, so that the GDAs of other hadrons could be studied as well.

    ↳ hep-phhep-exhep-latnucl-thJPS Conf.Proc.(2019)·1 citation
  6. 14

    Monitoring of the eclipsing Wolf-Rayet ULX in the Circinus galaxy

    Yanli Qiu · Roberto Soria

    We studied the eclipsing ultraluminous X-ray source CG X-1 in the Circinus galaxy, re-examining two decades of {\it Chandra} and {\it XMM-Newton} observations. The short binary period (7.21 hr) and high luminosity ( erg s) suggest a Wolf-Rayet donor, close to filling its Roche lobe; this is the most luminous Wolf-Rayet X-ray binary known to-date, and a potential progenitor of a gravitational-wave merger. We phase-connect all observations, and show an intriguing dipping pattern in the X-ray lightcurve, variable from orbit to orbit. We interpret the dips as partial occultation of the X-ray emitting region by fast-moving clumps of Compton-thick gas. We suggest that the occulting clouds are fragments of the dense shell swept-up by a bow shock ahead of the compact object, as it orbits in the wind of the more massive donor.

    ↳ astro-ph.HEnucl-thIAU Symp.(2018)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE