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Nuclear Theory·nucl-th

Monday·December 7, 2015

5 papers—2 primary·3 cross-listed

All5Primary2Cross-lists3
  1. 01

    On Quasibound N* Nuclei

    N. G. Kelkar🇨🇴 · D. Bedoya Fierro · P. Moskal🇵🇱

    The possibility for the existence of unstable bound states of the S11 nucleon resonance N(1535) and nuclei is investigated. These quasibound states are speculated to be closely related to the existence of the quasibound states of the eta mesons and nuclei. Within a simple model for the N N interaction involving a pion and eta meson exchange, N-nucleus potentials for N*-He and N*-Mg are evaluated and found to be of a Woods-Saxon like form which supports two to three bound states. In case of N*-He, one state bound by only a few keV and another by 4 MeV is found. The results are however quite sensitive to the N N and N N vertex parameters. A rough estimate of the width of these states, based on the mean free path of the exchanged mesons in the nuclei leads to very broad states with 80 and 110 MeV for N*-He and N*-Mg respectively.

    nucl-thnucl-exActa Phys.Polon.B(2016)·12 citations
  2. 02

    Moving forward to constrain the shear viscosity of QCD matter

    Gabriel Denicol🇺🇸 · Akihiko Monnai🇺🇸 · Bjoern Schenke🇺🇸

    We demonstrate that measurements of rapidity differential anisotropic flow in heavy ion collisions can constrain the temperature dependence of the shear viscosity to entropy density ratio {\eta}/s of QCD matter. Comparing results from hydrodynamic calculations with experimental data from RHIC, we find evidence for a small {\eta}/s 0.04 in the QCD cross-over region and a strong temperature dependence in the hadronic phase. A temperature independent {\eta}/s is disfavored by the data. We further show that measurements of the event-by-event flow as a function of rapidity can be used to independently constrain the initial state fluctuations in three dimensions and the temperature dependent transport properties of QCD matter.

    nucl-thhep-phnucl-exPRL(2016)·101 citations
  3. 03

    Spin Polarized Photons from Axially Charged Plasma at Weak Coupling: Complete Leading Order

    Kiminad A. Mamo🇺🇸 · Ho-Ung Yee🇺🇸

    In the presence of (approximately conserved) axial charge in the QCD plasma at finite temperature, the emitted photons are spin-aligned, which is a unique P- and CP-odd signature of axial charge in the photon emission observables. We compute this "P-odd photon emission rate" in weak coupling regime at high temperature limit to complete leading order in the QCD coupling constant: the leading log as well as the constant under the log. As in the P-even total emission rate in the literature, the computation of P-odd emission rate at leading order consists of three parts: 1) Compton and Pair Annihilation processes with hard momentum exchange, 2) soft t- and u-channel contributions with Hard Thermal Loop re-summation, 3) Landau-Pomeranchuk-Migdal (LPM) re-summation of collinear Bremstrahlung and Pair Annihilation. We present analytical and numerical evaluations of these contributions to our P-odd photon emission rate observable.

    ↳ hep-phhep-thnucl-exnucl-thPRD(2016)·13 citations
  4. 04

    Entanglement in Four-Dimensional SU(3) Gauge Theory

    Etsuko Itou🇯🇵 · Keitaro Nagata🇯🇵 · Yoshiyuki Nakagawa🇯🇵 · Atsushi Nakamura🇯🇵 · V.I. Zakharov🇷🇺

    We investigate the quantum entanglement entropy for the four-dimensional Euclidean SU(3) gauge theory. We present the first non-perturbative calculation of the entropic -function () of SU(3) gauge theory in lattice Monte Carlo simulation using the replica method. For ~fm, where is the length of the subspace, the entropic -function is almost constant, indicating conformally invariant dynamics. The value of the constant agrees with that perturbatively obtained from free gluons, with 20 % discrepancy. When is close to the Hadronic scale, the entropic -function decreases smoothly, and it is consistent with zero within error bars at fm.

    ↳ hep-thcond-mat.stat-mechhep-latnucl-thPTEP(2016)·65 citations
  5. 05

    An analysis of the impact of LHC Run I proton-lead data on nuclear parton densities

    Néstor Armesto🇪🇸 · Hannu Paukkunen🇪🇸 · José Manuel Penín🇪🇸 · Carlos A. Salgado🇪🇸 · Pía Zurita🇪🇸

    We report on an analysis of the impact of available experimental data on hard processes in proton-lead collisions during Run I at the Large Hadron Collider on nuclear modifications of parton distribution functions. Our analysis is restricted to the EPS09 and DSSZ global fits. The measurements that we consider comprise production of massive gauge bosons, jets, charged hadrons and pions. This is the first time a study of nuclear PDFs includes this number of different observables. The goal of the paper is twofold: i) checking the description of the data by nPDFs, as well as the relevance of these nuclear effects, in a quantitative manner; ii) testing the constraining power of these data in eventual global fits, for which we use the Bayesian reweighting technique. We find an overall good, even too good, description of the data, indicating that more constraining power would require a better control over the systematic uncertainties and/or the proper proton-proton reference from LHC Run II. Some of the observables, however, show sizable tension with specific choices of proton and nuclear PDFs. We also comment on the corresponding improvements on the theoretical treatment.

    ↳ hep-phhep-exnucl-exnucl-thEPJC(2016)·48 citations

Affiliations

first authorsco-authorsvia INSPIRE