Description
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The free energy density of ${\cal N}=4$ supersymmetric Yang-Mills theory in four space-time
dimensions is derived through second order in the 't Hooft coupling $\lambda$
at finite temperature using effective-field theory methods. The contributions to the free energy
density at this order come from the hard scale $T$ and the soft scale $\sqrt{\lambda} T$.
The effects of the scale $T$ are...
In this talk we demonstrate that the early stages of the bottom-up thermalization scenario [1] are well described by the adiabatic hydrodynamization framework. All of the qualitative features exhibited in QCD effective kinetic theory (EKT) simulations at weak coupling [2] are captured by the emergence of an effective low-energy instantaneous ground state for the 1-particle gluon distribution...
We study anomalous transport phenomena with lattice QCD simulations using improved staggered quarks. In particular, we calculate the conductivities both in the free case and in the interacting case, analysing the dependence of these coefficients with several parameters, such as the temperature and the quark mass.
Gribov quantization is a method to improve the infrared dynamics of Yang-Mills theory. We study the thermodynamics and transport properties of a plasma consisting of gluons whose propagator is improved by the Gribov prescription. We first construct the thermodynamics of Gribov plasma using the gauge-invariant Gribov dispersion relation for interacting gluons. When the Gribov parameter in the...
The existence of quark matter inside the cores of massive neutron stars can be probed by modern astrophysical observations. We model these hybrid stars using an (axial)vector meson extended quark-meson model to describe their quark cores, together with various hadronic models. We show that crossover phase transitions between the hadronic and quark phases can naturally create equations of state...
As the strength of the magnetic field ($B$) becomes weak, novel phenomena,
similar to the Hall effect in condensed matter physics
emerges both in charge and heat transport in a thermal
QCD medium with a finite quark chemical potential ($\mu$).
So we have calculated the transport coefficients
in a kinetic theory within a quasiparticle framework,
wherein we compute the effective mass...
It is found from viscous hydrodynamics that the QGP created in ultra relativistic heavy-ion collisions has different longitudinal and transverse pressures at early times. This occurs due to the large momentum space anisotropy in the p_T-p_L plane. This momentum space anisotropy can cause plasma instabilities that are largely responsible for the thermalization and isotropization of the system....
We study the nonperturbative aspects of nonconformal 2+1D Yang-Mills like worldvolume theories on both the isotropic and anisotropic non-supersymmetric D2 brane solution of type II supergravity. Because of broken conformality, the theories for both the cases are found to have running coupling similar to the real world QCD theories. In this context, some salient QCD-like confining properties,...
We present the extraction of the temperature by analyzing the charged particle transverse momentum spectra in lead-lead (Pb-Pb) and proton-proton (${\bf pp}$) collisions at LHC energies from the ALICE Collaboration using the Color String Percolation Model (CSPM) [1]. From the measured energy density ${\varepsilon}$ and the temperature T the dimensionless quantity ${ \varepsilon/}T^{4}$ is ...
The propagation of heavy quarks in the thermal medium closely resembles a Brownian motion characterized by the transport coefficients. In the leading order expansion of inverse mass, these transport coefficients, in particular momentum diffusion, are obtained from the correlators of chromo-electric (E) and chromo-magnetic (B) fields. We investigate longitudinal and transverse diffusion...
We study the impact of asymmetric fermionic and bosonic dark matter on neutron star properties, including tidal deformability, maximum masses, radii, etc. The conditions at which dark matter particles tend to condensate in the core of the star or create an extended halo are presented. We show that dark matter condensed in a core leads to a decrease of the total gravitational mass and tidal...
The phase structure of baryonic matter is investigated with focus on the role of fluctuations beyond the mean-field approximation. The prototype test case studied is the chiral nucleon-meson model, with added comments on the chiral quark-meson model. Applications to nuclear matter include the liquid-gas phase transition. Extensions to high baryon densities are performed for both nuclear and...
We propose and apply a new parameterization of the modified chiral effective model to study rotating neutron stars with hyperon core in the framework of the relativistic mean-field theory. The inclusion of the mesonic cross couplings in the model has improved the density content of the symmetry energy slope parameters, which are in agreement with the findings from recent terrestrial...
Using the hard-thermal-loop (HTL) resummation in real-time formalism, we study the next-to-leading order (NLO) quark self-energy and corresponding NLO dispersion laws. In NLO, we have replaced all the propagators and vertices with the HTL effective ones in the usual quark self-energy diagram. Additionally, a four-point vertex diagram also contributes to the quark NLO self-energy. We calculate...
In this talk, we discuss new symmetries of the Cardy-Rabinovici model and their applications. The Cardy-Rabinovici model is the 4d $U (1)$ gauge theory with electric and magnetic matters, and it is a good playground for studying the dynamics of 4d gauge theories. Although this model is not invariant under the $SL(2,\mathbb{Z})$ electromagnetic transformations strictly, we can realize these...
We study temperature fluctuations in the initial stages of the relativistic heavy-ion collision using a multiphase transport model. We consider the plasma in the initial stages after the collision before it has a chance to equilibrate. We have considered Au + Au collision with a varying center of mass energy. We use the non-equilibrium Tsallis statistics to find the entropic index in the...
Finding order parameters for the detection of critical phenomena and self-similar behavior in and out of equilibrium is a challenging endeavour in non-Abelian gauge theories. Tailored to detect topological structures in noisy data and accompanied by stability and limit theorems, persistent homology allows for the construction of sensible and sensitive observables. Based on state-of-the-art...
In the presence of an external uniform magnetic field $B$, we show that new axial and vector decay constants appear for pions. A general expression for the weak decay $\pi^- \rightarrow l^- \bar{\nu}_l$ is also obtained. We calculate these decay constants within the Nambu-Jona--Lasinio (NJL) model, obtaining an enhancement of the total decay rate up to $\sim 10^3$ for $\mathrm{eB}$ = 1...
I will present a summary of results on parity invariant quantum electrodynamics in three Euclidean dimensions using lattice regularization. The results will show scale invariance independent of the number of massless fermions. Results for monopole scaling dimensions and their relevance will also be discussed.
The aim of this project is to compute the strong sphaleron rate (the diffusion constant for the Chern-Simons topological number for quantum chromodynamics) on 4D lattices in a range of temperatures between 500 MeV and 3 GeV. This rate is important to understand the equilibration between axial quarks through the anomaly equations. Although this quantity has been previously computed in real-time...
More than 20 years ago, Glendenning et al. (1995) proposed the existence of stable white dwarfs with a core of strange quark matter. More recently, by studying radial modes, Alford et al. (2017) concluded that those objects are unstable. We investigate again the stability of these objects by looking at their radial oscillations, and we assume that there is no phase transition between hadronic...
A system of gluon fields generated at the earliest phase of relativistic heavy-ion
collisions can be described in terms of classical fields. Numerical simulations show that the system is unstable but a character of the instability is not well understood. With the intention to systematically study the problem, we analyze a stability of classical chromomagnetic and chromoelectric fields which...
Cold and dense matter can be explored in a systematic way both in the high-density (perturbative QCD) and low-density (Chiral EFT) regime. However, the path connecting them is yet to be discovered. As a result, these descriptions are usually extrapolated into the intermediate density regime and then connected at some transition point. In this work I will present a model that has features of...
We generalize a complex heavy-quark potential model from an isotropic QCD plasma to an anisotropic one by replacing the Debye mass $m_D$ with an anisotropic screening mass depending on the quark pair alignment with respect to the direction of anisotropy.
Such an angle-dependent mass is determined by matching the perturbative contributions in the potential model to the exact result obtained in...
We study the thermal transitions of dense two colour QCD with two flavours of Wilson fermions at a fixed chemical potential $\mu=443$ MeV on a coarse isotropic lattice $a=0.18$ fm. The results on a larger lattice volume ($N_s=24$) are compared with earlier results with the same lattice spacing but a smaller lattice volume ($N_s=16$). Only small finite volume effects are found.
We also...
We study thermalization of gluons with momentum $p$ characterized by $Q$ in spatially homomgeneous systems. In initially under-populated systems in which the equilibrium temperature $T\ll Q$, soft gluons are found to be rapidly generated via radiation to fill a classical thermal distribution $\propto T^*/p$ with $T^*\gg T$. Thermal equilibrium is established only after $T^*$ approaches to $T$...
Quantum Chromodynamics, the theory of strong interactions, predicts the existence, under extreme conditions, of a deconfined state of matter known as the quark-gluon plasma (QGP). We have strong evidence that such an extreme state is produced in relativistic heavy-ion collision experiments, such as RHIC and the LHC. A daring question is what is the smallest possible QGP size, one that can be...
We study the thermoelectric response of a thermal medium of deconfined quarks and gluons in the framework of relativistic kinetic theory. The response of the medium is quantified by the Seebeck and Nernst coefficients which relate the mutually longitudinal and transverse components, respectively, of the induced electric field and the temperature gradient. To obtain the above coefficients, we...
We compare the behavior of zero-modes of the overlap Dirac operator measured on the finite temperature 2+1 flavor lattice QCD configurations, generated with domain wall fermion discreitzation, to the local Polyakov Loop in the temperature range 1.1-1.2T_c, T_c being the pseudo-critical temperature. We show how the position of the zero-modes are anti-correlated to the local value of the Polyakov Loop.
The introduction of electric and magnetic fields in the QCD vacuum generates topological sectors with a non-zero topological charge. For weak fields, there is a linear response for the topological charge. We study this linear response which can be interpreted as the axion-photon coupling. In this work we use lattice simulations with improved staggered quarks including background electric and...
