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Nuclear Theory·nucl-th

Monday·July 23, 2018

11 papers—6 primary·5 cross-listed

All11Primary6Cross-lists5
  1. 07

    Transverse momentum dependent distributions with jets

    Daniel Gutierrez-Reyes🇪🇸 · Ignazio Scimemi🇪🇸 · Wouter J. Waalewijn🇳🇱 · Lorenzo Zoppi🇳🇱

    We investigate the use of jets to measure transverse momentum dependent distributions (TMDs). The example we use to present our framework is the dijet momentum decorrelation at lepton colliders. Translating this momentum decorrelation into an angle , we analyze the factorization of the cross section for the cases , and , where is the jet radius. Critically, for the Winner-Take-All axis, the jet TMD has the same double-scale renormalization group evolution as TMD fragmentation functions for all radii . TMD fragmentation functions in factorization theorems may then simply be replaced by the jet TMDs we calculate, and all ingredients to perform the resummation to next-to-next-to-leading logarithmic accuracy are available. Our approach also applies to semi-inclusive deep inelastic scattering (SIDIS), where a jet instead of a hadron is measured in the final state, and we find a clean method to probe the intrinsic transverse momentum of quarks and gluons in the proton that is less sensitive to final-state nonperturbative effects.

    ↳ hep-phnucl-thPRL(2018)·81 citations
  2. 08

    Hydrodynamic modes in a magnetized chiral plasma with vorticity

    D. O. Rybalka🇺🇸 · E. V. Gorbar🇺🇦 · I. A. Shovkovy🇺🇸

    By making use of a covariant formulation of the chiral kinetic theory in the relaxation-time approximation, we derive the first-order dissipative hydrodynamics equations for a charged chiral plasma with background electromagnetic fields. We identify the global equilibrium state for a rotating chiral plasma confined to a cylindrical region with realistic boundary conditions. Then, by using linearized hydrodynamic equations, supplemented by the Maxwell equations, we study hydrodynamic modes of magnetized rotating chiral plasma in the regimes of high temperature and high density. We find that, in both regimes, dynamical electromagnetism has profound effects on the spectrum of propagating modes. In particular, there are only the sound and Alfvén waves in the regime of high temperature, and the plasmons and helicons at high density. We also show that the chiral magnetic wave is universally overdamped because of high electrical conductivity in plasma that causes an efficient screening of charge fluctuations. The physics implications of the main results are briefly discussed.

    ↳ hep-thhep-phnucl-thPRD(2019)·26 citations
  3. 09

    Anomaly constraint on massless QCD and the role of Skyrmions in chiral symmetry breaking

    Yuya Tanizaki🇺🇸

    We discuss consequences of the 't Hooft anomaly matching condition for Quantum Chromodynamics (QCD) with massless fundamental quarks. We derive the new discrete 't Hooft anomaly of massless QCD for generic numbers of color and flavor , and an exotic chiral-symmetry broken phase without quark-bilinear condensate is ruled out from possible QCD vacua. We show that the baryon number symmetry is anomalously broken when the discrete axial symmetry and the flavor symmetry are gauged. In the ordinary chiral symmetry breaking, the Skyrmion current turns out to reproduce this 't Hooft anomaly of massless QCD. In the exotic chiral symmetry breaking, however, the anomalous breaking of does not take the correct form, and it is inconsistent with anomaly matching. This no-go theorem is based only on symmetries and anomalies, and thus has a wider range of applicability to the QCD phase diagram than the previous one obtained by QCD inequalities. Lastly, as another application, we check that duality of supersymmetric QCD with satisfies the new anomaly matching.

    ↳ hep-thnucl-thJHEP(2018)·85 citations
  4. 10

    Geometrically confined thermal field theory: Finite size corrections and phase transitions

    Sylvain Mogliacci🇿🇦 · Isobel Kolbé🇿🇦 · W. A. Horowitz🇿🇦

    Motivated by the recent shocking results from RHIC and LHC that show quark-gluon plasma signatures in small systems, we study a simple model of a massless, noninteracting scalar field confined with Dirichlet boundary conditions. We use this system to investigate the finite size corrections to thermal field theoretically derived quantities compared to the usual Stefan-Boltzmann limit of an ideal gas not confined in any direction. Two equivalent expressions with different numerical convergence properties are found for the free energy in rectilinear spacetime dimensions with spatial dimensions of finite extent. We find that the First Law of Thermodynamics generalizes such that the pressure depends on direction but that the Third Law is respected. For systems with finite dimension(s) but infinite volumes, such as a field constrained between two parallel plates or a rectangular tube, the relative fluctuations in energy are zero, and hence the canonical and microcanonical ensembles are equivalent. We present precise numerical results for the free energy, total internal energy, pressure, entropy, and heat capacity of our field between parallel plates, in a tube, and in finite volume boxes of various sizes in 4 spacetime dimensions. For temperatures and system sizes relevant for heavy ion phenomenology, we find large deviations from the Stefan-Boltzmann limit for these quantities, especially for the pressure. Further investigation of an isolated system of fields constrained between parallel plates reveals a divergent isoenergetic compressibility at a critical length . We have thus discovered a new second order phase transition via a first principles calculation, a transition that is driven by the size of the system.

    ↳ hep-thcond-mat.quant-gascond-mat.stat-mechhep-ph+1PRD(2020)·27 citations
  5. 11

    On Bulk Viscosity at Weak and Strong 't Hooft Couplings

    Alina Czajka🇨🇦 · Keshav Dasgupta🇨🇦 · Charles Gale🇨🇦 · Sangyong Jeon🇨🇦 · Aalok Misra🇮🇳 · Michael Richard🇨🇦 · Karunava Sil🇮🇳

    Bulk viscosity is an important transport coefficient that exists in the hydrodynamical limit only when the underlying theory is non-conformal. One example being thermal QCD with large number of colors. We study bulk viscosity in such a theory at low energies and at weak and strong 't Hooft couplings when the temperature is above the deconfinement temperature. The weak coupling analysis is based on Boltzmann equation from kinetic theory whereas the strong coupling analysis uses non-conformal holographic techniques from string and M-theories. Using these, many properties associated with bulk viscosity may be explicitly derived. This is a shortened companion paper that summarizes some of the results of our longer paper arXiv:1807.04713.

    ↳ hep-thcond-mat.str-elhep-phnucl-thMod.Phys.Lett.A(2020)·8 citations

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first authorsco-authorsvia INSPIRE