arXiv subjects

Edward Shuryak

Publications and source records attributed to Edward Shuryak.

At least 91 records · Page 5Linked to original sources

arXiv2016

Light Adjoint Quarks in the Instanton-Dyon Liquid Model IV

We discuss the instanton-dyon liquid model with $N_f$ Majorana quark flavors in the adjoint representation of color $SU_c(2)$ at finite temperature. We briefly recall the index theorem on $S^1\times R^3$ for twisted adjoint fermions in a BPS dyon background of arbitrary holonomy, and use the ADHM construction to explicit the adjoint anti-periodic zero modes. We use these results to derive the partition function of an interacting instanton-dyon ensemble with $N_f$ light and anti-periodic adjoint quarks. We develop the model in details by mapping the theory on a 3-dimensional quantum effective theory with adjoint quarks with manifest $SU(N_f)\times Z_{4N_f}$ symmetry. Using a mean-field analysis at weak coupling and strong screening, we show that center symmetry requires the spontaneous breaking of chiral symmetry, which is shown to only take place for $N_f=1$. For a sufficiently dense liquid, we find that the ground state is center symmetric and breaks spontaneously flavor symmetry through $SU(N_f)\times Z_{4N_f}\rightarrow O(N_f)$. As the liquid dilutes with increasing temperature, center symmetry and chiral symmetry are restored. We present numerical and analytical estimates for the transition temperatures.

hep-ph↗

arXiv2016

Classical interactions of the instanton-dyons with antidyons

Instanton-dyons, also known as instanton-monopoles or instanton-quarks, are topological constituents of the instantons at nonzero temperature and nonzero expectation value of $A_4$. While the interaction between instanton-dyons has been calculated to one-loop order by a number of authors, that for dyon-antidyon pairs remains unknown even at the classical level. In this work we are filling this gap, by solving the gradient flow equation on a 3d lattice. We start with two well separated objects. We find that, after initial rapid relaxation, the configurations follow "streamline" set of configurations, which is basically independent on the initial configurations used. In striking difference to instanton-antiinstanton streamlines, in this case it ends at a quasi-stationary configuration, with an abrupt drop to perturbative fields. We parameterize the action of the streamline configurations, which is to be used in future many-body calculations.

hep-ph↗

arXiv2016

Instanton-dyon Ensemble with two Dynamical Quarks: the Chiral Symmetry Breaking

This is the second paper of the series aimed at understanding the ensemble of instanton-dyons, now with two flavors of light dynamical quarks. The partition function is appended by the fermionic factor, $(det T)^{N_f}$ and Dirac eigenvalue spectra at small values are derived from the numerical simulation of 64 and 128 dyons. Those spectra show clear chiral symmetry breaking pattern at high dyon density.

hep-ph↗

arXiv2015

Heavy Ion Collisions: Achievements and Challenges

A decade ago brief summary of the field could be formulated as a discovery of strongly-coupled Quark-Gluon-Plasma, sQGP, making a very good liquid with surprisingly small viscosity. Since 2010 we have LHC program, which added a lot to our understanding, and now there seems to be a need to consolidate what we learned and formulate a list of issues to be studied next. Hydrodynamical perturbations, leading to higher harmonics of angular correlations, are identified as long-lived sound waves. Recently studied reactions involving sounds include phonon decays into two ("loop viscosity"), phonon+magnetic field into photons/dileptons (sono-magneto-luminescence), and two phonons into a gravity wave, a penetrating probe of the Big Bang. The mainstream issues in the field now include a quest to study transition between $pp,pA$ and heavy ion $AA$ collisions, with an aim to locate "the smallest drops" of the sQGP displaying collective/hydrodynamics behavior. The issues related to out-of-equilibrium stage of the collisions, and mechanisms of the equilibration, in weak and strong coupling, are also hotly debated.

hep-ph↗

arXiv2015

Collective String Interactions in AdS/QCD and High-Multiplicity pA Collisions

QCD strings originate from high-energy scattering in the form of Reggeons and Pomerons, and have been studied in some detail in lattice numerical simulations. Production of multiple strings, with their subsequent breaking, is now a mainstream model of high energy $pp$ and $pA$ collisions. Recent LHC experiments revealed that high multiplicity end of such collisions show interesting collective effects. This ignited an interest in the interaction of QCD strings and multi-string dynamics. Holographic models, collectively known as AdS/QCD, developed in the last decade, describe both hadronic spectroscopy and basic thermodynamics, but so far no studies of the QCD strings have been done in this context. The subject of this paper is to do this. First, we study in more detail the scalar sector of hadronic spectroscopy, identifying "glueballs" and "scalar mesons," and calculate the degree of their mixing. The QCD strings, holographic images of the fundamental strings, thus have a "gluonic core" and a "sigma cloud." The latter generates $σ$ exchanges and collectivization of the strings, affecting, at a certain density, the chiral condensate and even the minimum of the effective string potential, responsible for the very existence of the QCD strings. Finally, we run dynamical simulations of the multi-string systems, in the "spaghetti" setting approximating central $pA$ collisions, and specify conditions for their collectivization into a black hole, or the dual QGP fireball.

hep-ph↗

arXiv2015

Femtoscopic signature of strong radial flow in high-multiplicity $pp$ collisions

Hydrodynamic simulations are used to calculate the identical pion HBT radii, as a function of the pair momentum $k_{\rm T}$. This dependence is sensitive to the magnitude of the collective radial flow in the transverse plane, and thus comparison to ALICE data enables us to derive its magnitude. By using hydro solutions with variable initial parameters we conclude that in this case fireball explosions start with a very small initial size, well below 1 ${\rm fm}$.

hep-ph↗

arXiv2015

Interacting Ensemble of the Instanton-dyons and Deconfinement Phase Transition in the SU(2) Gauge Theory

Instanton-dyons, also known as instanton-monopoles or instanton-quarks, are topological constituents of the instantons at nonzero temperature and holonomy. We perform numerical simulations of the ensemble of interacting dyons for the SU(2) pure gauge theory. Unlike previous studies, we focus on back reaction on the holonomy and the issue of confinement. We calculate the free energy as a function of the holonomy and the dyon densities, using standard Metropolis Monte Carlo and integration over parameter methods. We observe that as the temperature decreases and the dyon density grows, its minimum indeed moves from small holonomy to the value corresponding to confinement. We then report various parameters of the self-consistent ensembles as a function of temperature, and investigate the role of inter-particle correlations.

hep-ph↗

arXiv2015

Confining Dyon-Anti-Dyon Coulomb Liquid Model I

We revisit the dyon-anti-dyon liquid model for the Yang-Mills confining vacuum discussed by Diakonov and Petrov, by retaining the effects of the classical interactions mediated by the streamline between the dyons and anti-dyons. In the SU(2) case the model describes a 4-component strongly interacting Coulomb liquid in the center symmetric phase. We show that in the linearized screening approximation the streamline interactions yield Debye-Huckel type corrections to the bulk parameters such as the pressure and densities, but do not alter significantly the large distance behavior of the correlation functions in leading order. The static scalar and charged structure factors are consistent with a plasma of a dyon-anti-dyon liquid with a Coulomb parameter $Γ_{D\bar D}\approx 1$ in the dyon-anti-dyon channel. Heavy quarks are still linearly confined and the large spatial Wilson loops still exhibit area laws in leading order. The t$^\prime$ Hooft loop is shown to be 1 modulo Coulomb corrections.

hep-ph↗

arXiv2015

"Explosive regime" should dominate collisions of ultra-high energy cosmic rays

Since the launch of LHC experiments it has been discovered that the high multiplicity trigger in pp, pA collisions finds events behaving differently from the typical (minimally biased) ones. In central pPb case it has been proven that those possess collective phenomena known as the radial, elliptic and triangular flows, similar to what is known in heavy ion (AA) collisions. In this paper we argue that at the ultra-high energies, E_lab ~ 10^{20} eV, of the observed cosmic rays this regime changes from a small-probability fluctuation to a dominant one. We estimate velocity of the transverse collective expansion for the light-light and heavy-light collisions, and find it comparable to what is observed at LHC for the central PbPb case. We argue that significant changes of spectra of various secondaries associated with this phenomenon should be important for the development of the cosmic ray cascades.

hep-ph↗

arXiv2015

Gravity waves generated by sounds from big bang phase transitions

Inhomogeneities associated with the cosmological QCD and electroweak phase transitions produce hydrodynamical perturbations, longitudinal sounds and rotations. It has been demonstrated by Hindmarsh et al. that the sounds produce gravity waves (GW) well after the phase transition is over. We further argue that, under certain conditions, an inverse acoustic cascade may occur and move sound perturbations from the (UV) momentum scale at which the sound is originally produced to much smaller (IR) momenta. The weak turbulence regime of this cascade is studied via the Boltzmann equation, possessing stationary power and time-dependent self-similar solutions. We suggest certain indices for the strong turbulence regime as well, into which the cascade eventually proceeds. Finally, we point out that two on-shell sound waves can produce one on-shell gravity wave, and we evaluate the rate of the process using a standard sound loop diagram.

hep-ph↗

arXiv2015

Light Quarks in the Screened Dyon-Anti-Dyon Coulomb Liquid Model II

We discuss an extension of the dyon-anti-dyon liquid model that includes light quarks in the dense center symmetric Coulomb phase. In this work, like in our previous one, we use the simplest color SU(2) group. We start with a single fermion flavor $N_f=1$ and explicitly map the theory onto a 3-dimensional quantum effective theory with a fermion that is only U$_V(1)$ symmetric. We use it to show that the dense center symmetric plasma develops, in the mean field approximation, a nonzero chiral condensate, although the ensuing Goldstone mode is massive due to the U$_A(1)$ axial-anomaly. We estimate the chiral condensate and $σ,η$ meson masses for $N_f=1$. We then extend our analysis to several flavors $N_f>1$ and colors $N_c>2$ and show that center symmetry and spontaneous chiral symmetry breaking disappear simultaneously when $x=N_f/N_c\geq 2$ in the dense plasma phase. A reorganization of the dense plasma phase into a gas of dyon-antidyon molecules restores chiral symmetry, but may preserve center symmetry in the linearized approximation. We estimate the corresponding critical temperature.

hep-ph↗

arXiv2015

Collective flow in high-multiplicity proton-proton collisions

We present an evidence of strong radial flow in high-multiplicity pp collisions. We analyze the CMS data on the inclusive spectra of the charged pions, kaons and protons in the LHC $\sqrt{s}=7$ TeV collisions. For $ \gtrsim 75$ we demonstrate the consistency of the hydrodynamic description with the (idealized) Gubser's flow. Using a one parameter fit of the model to experimental data, we obtain the initial fireball size to be of the order of 1 fm. At smaller multiplicities, the fit cannot be performed which shows a limitation of the hydrodynamic approach and provides us with falsifiability of our theory.

hep-ph↗

arXiv2015

Gauge topology and confinement: an update

In the instanton ensemble the fermionic zero modes collectivize and break chiral symmetry. Recent studies of resulting zero mode zone confirm its very small width and overall importance for lattice simulations. Confinement however has been related with completely different topological objects, the magnetic monopoles. Instanton constituents -- instanton dyons, discovered at nonzero holonomy by Pierre van Baal and others -- are able to explain both confinement and chiral symmetry breaking. The talk summarizes recent works deriving the instanton-dyon mutual interactions, and statistical studies of their ensemble. At high density the screening is robust enough to do it analytically, in the mean-field-type approach: we call this limit Dense Dyonic Plasma (DDP). Above $T_c$ the classical interaction between the dyons induce strong correlations and should be studied by direct numerical simulations. Those works are now in progress.

hep-ph↗

arXiv2014

Self-interacting QCD strings and string balls

Strings at T ~ T_c are known to be subject to the so-called Hagedorn phenomenon, in which a string's entropy (times T) and energy cancel each other and result in the evolution of the string into highly excited states, or "string balls". Intrinsic attractive interaction of strings -- gravitational for fundamental strings or in the context of holographic models of the AdS/QCD type, or sigma exchanges for QCD strings -- can significantly modify properties of the string balls. If heavy enough, those start approaching properties of the black holes. We generate self-interacting string balls numerically, in a thermal string lattice model. We found that in a certain range of the interaction coupling constants they morph into a new phase, the "entropy-rich" string balls. These objects can appear in the so-called mixed phase of hadronic matter, produced in heavy ion collisions, as well as possibly in the high multiplicity proton-proton or proton-nucleus collisions. Among discussed applications are jet quenching in the mixed phase and also the study of angular deformations of the string balls.

hep-ph↗

arXiv2014

Collective interaction of QCD strings and early stages of high multiplicity pA collisions

We study the early stages of "central" pA and peripheral AA collisions. Several observables indicate that at a sufficiently large number of participant nucleons the system undergoes a transition into a new "explosive" regime. By defining a string-string interaction through the sigma meson exchange and performing molecular dynamics simulation, we argue that one should expect a strong collective implosion of the multi-string "spaghetti" state, creating significant compression of the system in the transverse plane. Another consequence is the collectivization of the "sigma clouds" of all strings into a chirally symmetric fireball. We find that these effects happen provided the number of strings $N_s > 30$ or so, as only such a number can compensate a small sigma-string coupling. These findings should help us to understand the subsequent explosive behavior, observed for the particle multiplicities roughly corresponding to this number of strings.

hep-ph↗

arXiv2014

New Regimes of Stringy (Holographic) Pomeron and High Multiplicity pp and pA Collisions

Holographic AdS/QCD models of the Pomeron unite a string-based description of hadronic reactions of the pre-QCD era with the perturbative BFKL approach. The specific version we will use due to Stoffers and Zahed, is based on a semiclassical quantization of a "tube" (closed string exchange or open string virtual pair production) in its Euclidean formulation using the scalar Polyakov action. This model has a number of phenomenologically successful results. The periodicity of a coordinate around the tube allows the introduction of a Matsubara time and therefore an effective temperature Teff on the string. We observe that at the LHC energies and for sufficiently small impact parameter, Teff approaches and even exceeds the Hagedorn temperature of the QCD strings. Based on studies of the stringy thermodynamics of pure gauge theories we suggest that there should exist two new regimes of the Pomeron: the "near-critical" and the "post-critical" ones. In the former one, string excitations create a high entropy "string ball", with high energy and entropy but small pressure/free energy. If heavy enough this ball becomes a (dual) black hole (BH). As the intrinsic temperature of the string exceeds the Hagedorn temperature, the ball becomes a post-critical explosive "QGP ball". The hydrodynamical explosion resulting from this scenario was predicted by us to have radial flow exceeding that ever seen even in heavy ion collisions, which was recently confirmed by CMS and ALICE at LHC. We also discuss the elastic scattering profile, finding some hints for new phases in it, as well as two-particle correlations.

hep-ph↗

arXiv2014

On Chiral Symmetry Breaking, Topology and Confinement

We start with the relation between the chiral symmetry breaking and gauge field topology. New lattice result further enhance the notion of Zero Mode Zone, a very narrow strip of states with quasizero Dirac eigenvalues. Then we move to the issue of "origin of mass" and Brown-RHo scaling: a number of empirical facts contradicts to the idea that masses of quarks and such hadrons as $ρ,N$ decrease near $T_c$. We argue that while at $T=0$ the main contribution to the effective quark mass is chirally odd $m_{\snchi}$, near $T_c$ it rotates to chirally-even component $m_χ$, because "infinite clusters" of topological solitons gets split into finite ones. Recent progress in understanding of topology require introduction of nonzero holonomy $ \neq 0$, which splits instantons into $N_c$ (anti)selfdual "instanton-dyons". Qualitative progress, as well as first numerical studios of the dyon ensemble are reported. New connections between chiral symmetry breaking and confinement are recently understood, since instanton-dyons generates holonomy potential with a minimum at confining value, if the ensemble is dense enough.

nucl-th↗

arXiv2013

Instabilities near the QCD phase transition in the holographic models

The paper discusses phenomena close to the critical QCD temperature, using the holographic model. One issue studied is the overcooled high-T phase, in which we calculate quasi normal sound modes. We do not find instabilities associated with other first order phase transitions, but nevertheless observe drastic changes in sound propagation/dissipation. The rest of the paper considers a cluster of the high-T phase in the UV in coexistence with the low-T phase, in a simplified ansatz in which the wall separating them is positioned only in the holographic coordinate. This allows to find the force on the wall and classical motion of the cluster. When classical motion is forbidden, we evaluate tunneling probability through the remaining barrier.

hep-th↗