Possible New Phase of Thermal QCD

Abstract

Using lattice simulations, we show that there is a phase of thermal QCD, where the spectral density $\rho (\lambda )$ of Dirac operator changes as $1/\lambda$ for the infrared eigenvalues $\lambda <T$. This behavior persists over the entire low energy band we can resolve accurately, over three orders of magnitude on our largest volumes. We propose that in this "IR phase", the well-known non-interacting scale invariance at very short distances (UV, $\lambda \to \infty$, asymptotic freedom), coexists with very different interacting type of scale invariance at long distances (IR, $\lambda <T$). Such dynamics may be responsible for the unusual fluidity properties of the medium observed at RHIC and LHC. We point out its connection to the physics of Banks-Zaks fixed point, leading to the possibility of massless glueballs in the fluid. Our results lead to the classification of thermal QCD phases in terms of IR scale invariance. The ensuing picture naturally subsumes the standard chiral crossover feature at $"T_c"\approx 155$ MeV. Its crucial new aspect is the existence of temperature $T_{IR}$ (200 MeV $<T_{IR}<$ 250 MeV) marking the onset of IR phase and possibly a true phase transition.

18 pages, 7 figures; v2: 19 pages, 7 figures, few presentation improvements, published version

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• Topological susceptibility of $N_f=2+1$ QCD from staggered fermions spectral projectors at high temperatures
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• Chiral spin symmetry and the QCD phase diagram
• Proton Mass Decomposition and Hadron Cosmological Constant
• Ideal topological gas in the high temperature phase of SU(3) gauge theory
• Localization of Dirac Fermions in Finite-Temperature Gauge Theory
• Eigenvalues of the QCD Dirac matrix with improved staggered quarks in the continuum limit
• Anderson Metal-to-Critical Transition in QCD
• Topology and emergent symmetries in dense compact star matter
• Super-Universality in Anderson Localization
• Centre vortex evidence for a second finite-temperature QCD transition
• Topology change, emergent symmetries and compact star matter
• Deconfinement and degrees of freedom in $pp$ and $A-A$ collisions at LHC energies
• Localisation of Dirac modes in gauge theories and Goldstone's theorem at finite temperature
• QCD Anderson transition with overlap valence quarks on a twisted-mass sea
• Topological Dimensions from Disorder and Quantum Mechanics?
• Topological observables and $\theta$ dependence in high temperature QCD from lattice simulations
• $U_A(1)$ symmetry breaking quark interactions from vacuum polarization
• Understanding the approach to thermalization from the eigenspectrum of non-Abelian gauge theories
• QCD transition at the physical point, and its scaling window from twisted mass Wilson fermions
• The "Folk Theorem" on Effective Field Theory: A Case for Nuclear Physics
• Finite temperature QCD with $N_f=2+1+1$ Wilson twisted mass fermions at physical pion, strange and charm masses
• QCD at high temperature and density: selected highlights
• Imprints of $U_A(1)$ chiral anomaly and disorder in the Dirac eigenspectrum of QCD at finite temperature
• Gluon Condensate via Dirac Spectral Density: IR Phase, Scale Anomaly and IR Decoupling