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Nuclear Theory·nucl-th

Wednesday·October 31, 2018

8 papers—2 primary·6 cross-listed

All8Primary2Cross-lists6
  1. 03

    Swimming and swirling colorful ghosts

    Giorgio Torrieri🇧🇷

    We show that the ideal fluid limit, defined as the existance of a flow frame with respect to which the fluid is homogeneus and isotropic, and the consequent independence of the equation of state on , is incompatible with non-Abelian gauge theory. Instead, the equation of state becomes dependent on via modes which are roughly equivalent to ghost modes in the hydrodynamic limit. These modes can be physically imagined as a field of 'purcell swimmers' whose 'arms and legs' are outstretched in Gauge space. Also, vorticity should couple to the Wilson loop via the chromo-electro-magnetic field tensor, which in this limit is not a 'force' but instead represents the polarization tensor of the gluons. We show that because of this coupling vorticity also aquires swirling non-hydrodynamic modes. We then argue that these swirling and swimming non-hydodynamic modes are the manifestation of gauge redunancy within local equilibrium, and speculate on their role in quark-gluon plasma thermalization

    ↳ hep-thhep-phnucl-thphysics.flu-dynEPJA(2020)·9 citations
  2. 04

    Electrical conductivity and relaxation via colored noise in a hadronic gas

    Jan Hammelmann🇩🇪 · Juan M. Torres-Rincon🇺🇸 · Jean-Bernard Rose🇩🇪 · Moritz Greif🇩🇪 · Hannah Elfner🇩🇪

    Motivated by the theory of relativistic hydrodynamic fluctuations we make use of the Green-Kubo formula to compute the electrical conductivity and the (second-order) relaxation time of the electric current of an interacting hadron gas. We use the recently developed transport code SMASH to numerically solve the coupled set of Boltzmann equations implementing realistic hadronic interactions. In particular, we explore the role of the resonance lifetimes in the determination of the electrical relaxation time. As opposed to a previous calculation of the shear viscosity we observe that the presence of resonances with lifetimes of the order of the mean-free time does not appreciably affect the relaxation of the electric current fluctuations. We compare our results to other approaches describing similar systems, and provide the value of the electrical conductivity and the relaxation time for a hadron gas at temperatures between T=60 MeV and T=150 MeV.

    ↳ hep-phnucl-thPRD(2019)·29 citations
  3. 05

    Strong Isospin Breaking in the Decay Constants of Heavy-Light Mesons from Local-Duality QCD Sum Rules

    Wolfgang Lucha🇦🇹 · Dmitri Melikhov🇦🇹 · Silvano Simula🇮🇹

    We explore, by a rather peculiar limit of QCD sum rules subject to a Borel transformation (realized by allowing the related Borel mass parameter to approach infinity), how the small difference of the masses of up and down quark translates into the leptonic decay constants of pseudoscalar or vector heavy-light mesons. For the charmed and bottom mesons, we find that the decay constants of their lowest-lying charged and neutral representatives should differ by an amount of the order of 1 MeV.

    ↳ hep-phhep-latnucl-thPoS(2018)·1 citation
  4. 06

    New data on states in Gd

    A.I. Levon · C. Costache · T. Faestermann · R. Hertenberger · A. Ionescu · R. Lica · A.G. Magner · C. Mihai · R. Mihai · C.R. Nita · S. Pascu · K.P. Shevchenko and 3 other authors

    Excited states in the deformed nucleus Gd have been studied in the (p,t) reaction by using the Munich Tandem and Q3D spectrograph. 30 new excited 0 states (three tentative) have been assigned up to the 4.3 MeV excitation energy. The total number of 34 excited 0 states (four tentatively assigned) in a deformed nucleus, close to a complete level scheme, offers a new opportunity to test nuclear models and obtain more information on the structure of these special states.

    ↳ nucl-exnucl-thPRC(2019)·8 citations
  5. 07

    Three neutrons from Lattice QCD

    Jan-Lukas Wynen🇩🇪 · Evan Berkowitz🇩🇪 · Thomas Luu🇩🇪 · Andrea Shindler🇺🇸 · John Bulava🇩🇰

    We present a study on ab-initio calculations of three-neutron correlators from Lattice QCD. We extend the method of baryon blocks to systems of three spacially displaced baryons. This allows the measurement of three-neutron -wave correlators with total spin and . In addition, we use automatic code generation that has high flexibility and allows for easy inclusion of additional channels in the future while optimizing the evaluation of contractions. Our measurements were performed on a newly generated Clover-Wilson gauge field ensemble with . We present preliminary results of our calculations of one pion and nucleon as well as two nucleon () and three neutron () correlators.

    ↳ hep-latnucl-thPoS(2018)·3 citations
  6. 08

    Global description of bottomonium suppression in proton-nucleus and nucleus-nucleus collisions at LHC energies

    Elena G. Ferreiro🇪🇸

    We show that we can reach a global and coherent description of bottomonium suppression in both proton-nucleus and nucleus-nucleus collisions at the LHC energies. The measured relative suppression of the excited bottomonium states as compared to their ground state allows us to constrain the scattering cross sections between the bottomonia and the comovers created during the collisions. Our result hints at a similar energy distribution of these comovers in the environment created by proton-nucleus and nucleus-nucleus collisions. Along the way of our study, we also update our knowledge for the bottomonium feed-down pattern and our comprehension on the modification of the nuclear parton distribution functions in proton-nucleus collisions. We present our results for Pb collisions at 5.02 and 8.16 TeV and for PbPb collisions at 2.76 and 5.02 TeV.

    ↳ hep-phnucl-thPoS(2018)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE