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Nuclear Theory·nucl-th

Wednesday·February 1, 2017

6 papers—2 primary·4 cross-listed

All6Primary2Cross-lists4
  1. 01

    [Submitted on 31 Jan 2017]

    High baryon densities achievable in the fragmentation regions at RHIC and LHC

    Joseph Kapusta🇺🇸 · Ming Li🇺🇸

    We use the McLerran-Venugopalan model of the glasma energy-momentum tensor to compute the rapidity loss and excitation energy of the colliding nuclei in the fragmentation regions followed by a space-time picture to obtain their energy and baryon densities. At the top RHIC energy we find baryon densities up to 3 baryons/fm, which is 20 times that of atomic nuclei. Assuming the formation of quark-gluon plasma, we find initial temperatures of 200 to 300 MeV and baryon chemical potentials of order 1 GeV. Assuming a roughly adiabatic expansion it would imply trajectories in the plane which would straddle a possible critical point.

    Comments:
    4 pages, 6 figures, 1 table, Proceedings of Strangeness in Quark Matter 2016
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1701.08919 [pdf]
    J.Phys.Conf.Ser.(2017)·1 citation
  2. 02

    [Submitted on 31 Jan 2017]

    Transverse momentum fluctuations in ultrarelativistic Pb+Pb and p+Pb collisions with wounded quarks

    Piotr Bozek🇵🇱 · Wojciech Broniowski🇵🇱

    We analyze the phenomenon of size-flow transmutation in ultrarelativistic nuclear collisions in a model where the initial size fluctuations are driven by the wounded quarks and the collectivity is provided by viscous hydrodynamics. It is found that the model properly reproduces the data for the transverse momentum fluctuations measured for Pb+Pb collisions at 2.76TeV by the ALICE Collaboration. The agreement holds for a remarkably wide range of centralities, from 0-5% up to 70-80%, and displays a departure from a simple scaling with in the form seen in the data. The overall agreement in the model with wounded quarks is significantly better than with nucleon participants. This feature joins the previously-found wounded quark multiplicity scaling in the argumentation in favor of subnucleonic degrees of freedom in the early dynamics. We also examine in detail the correlations between measures of the initial size and final average transverse momentum of hadrons. Predictions are made for the transverse momentum fluctuations in p+Pb collisions at 5.02TeV.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1701.09105 [pdf]
    PRC(2017)·53 citations
  3. 03

    [Submitted on 31 Jan 2017] (cross-list from hep-ph)

    Compositeness Of Quasibound States from Effective Field Theory

    Yuki Kamiya🇯🇵 · Tetsuo Hyodo🇯🇵

    The internal structure of exotic hadron candidates are studied from the viewpoint of the compositeness of near-threshold states. We focus on the Weinberg's weak-binding relation between the experimental observables and the compositeness of the state. First we extend the relation for quasibound states within the framework of the effective field theory. Next, considering the correction term, we develop a systematic method to estimate the uncertainty of compositeness in the weak-binding relation. Finally, applying the extended relation and the error evaluation method, we conclude that the structure of Lambda(1405) is dominated by the Kbar N component.

    Comments:
    8 pages, 1 figure, Proceedings of the 26th International Nuclear Physics Conference (INPC2016), Sep. 11-16, 2016, Adelaide, Australia
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1701.08941 [pdf]
    PoS(2017)·8 citations
  4. 04

    [Submitted on 31 Jan 2017] (cross-list from hep-lat)

    QCD Thermodynamics on the Lattice from the Gradient Flow

    Etsuko Itou🇯🇵 · Sinya Aoki🇯🇵

    To obtain the precise values of the bulk quantities and transport coefficients in quark-gluon-plasma phase, we propose that a direct calculation of the renormalized energy-momentum tensor (EMT) on the lattice using the gradient flow. From one-point function of EMT, authors in Ref.[1] obtained the interaction measure and thermal entropy. The results are consistent with the one obtained by the integral method. Based on the success, we try to measure the two-point function of EMT, which is related to the transport coefficients. Advantages of our method are (1) a clear signal because of the smearing effects of the gradient flow and (2) no need to calculate the wave function renormalization of EMT. In addition, we give a short remark on a comparison of the numerical cost between the positive- and adjoint-flow methods for fermions, needed to obtain the EMT in the (2+1) flavor QCD.

    Comments:
    8pages, Proceeding of the 26th International Nuclear Physics Conference (INPC2016)
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1701.08983 [pdf]
    PoS(2017)·3 citations
  5. 05

    [Submitted on 31 Jan 2017] (cross-list from hep-lat)

    Thermal D mesons from anisotropic lattice QCD

    Aoife Kelly🇮🇪 · Jon-Ivar Skullerud🇮🇪

    We present results for correlators and spectral functions of open charm mesons using 2+1 flavours of clover fermions on anisotropic lattices. The D mesons are found to dissociate close to the deconfinement crossover temperature Tc. Our preliminary results suggest a shift in the thermal D meson mass below Tc. Mesons containing strange quarks exhibit smaller thermal modifications than those containing light quarks.

    Comments:
    6 pages, 4 figures, talk presented at Lattice 2016, Southampton, and Confinement XII, Thessaloniki
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1701.09005 [pdf]
    EPJ Web Conf.(2017)·4 citations
  6. 06

    [Submitted on 31 Jan 2017] (cross-list from hep-ph)

    The electromagnetic Sigma-to-Lambda hyperon transition form factors at low energies

    Carlos Granados🇸🇪 · Stefan Leupold🇸🇪 · Elisabetta Perotti (Uppsala U.)🇸🇪

    Using dispersion theory the low-energy electromagnetic form factors for the transition of a Sigma to a Lambda hyperon are related to the pion vector form factor. The additionally required input, i.e. the two-pion--Sigma--Lambda amplitudes are determined from relativistic next-to-leading-order (NLO) baryon chiral perturbation theory including the baryons from the octet and optionally from the decuplet. Pion rescattering is again taken into account by dispersion theory. It turns out that the inclusion of decuplet baryons is not an option but a necessity to obtain reasonable results. The electric transition form factor remains very small in the whole low-energy region. The magnetic transition form factor depends strongly on one not very well determined low-energy constant of the NLO Lagrangian. One obtains reasonable predictive power if this low-energy constant is determined from a measurement of the magnetic transition radius. Such a measurement can be performed at the future Facility for Antiproton and Ion Research (FAIR).

    Comments:
    18 pages
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1701.09130 [pdf]
    EPJA(2017)·64 citations

Affiliations

first authorsco-authorsvia INSPIRE