Neutron star physics in the multi-messenger era
Impact of Dissipation on the Dynamics of Neutron Star Mergers
A decade of Gravitational Wave observations by LIGO-Virgo collaborations has opened a new window to the Universe peeking into the exotic lives of stellar black holes and compact stars. With the observation of GW170817, the first GW observation from coalescence of binary neutron stars along with the associated multi-wavelength spectral observation such as $\gamma$-rays, X-rays, UV, IR and...
We investigate the effects of including strong charge parity violating effects through axion field on the structure and the oscillation modes of the neutron stars with the possibility of a quark matter core. The effects of axions in quark matter is described through a t Hooft determinant interaction in the flavor space within the ambit of a three flavor Nambu--Jona-Lasinio model. The presence...
Recycled millisecond pulsars are susceptible to starquakes as they are continuously accreting matter from their binary companion. A starquake happens when the rotational frequency of the star crosses its breaking frequency. In this study, we perform a model analysis of an accreting neutron star suffering a starquake. We analyse two models: a spherical star with accreting mountains and a...
Our approach offers a phenomenological model for investigating nuclear matter by employing the modified relativistic Dirac formalism coupled with the ฯโฯ and ฯ mesons in the quark-meson coupling model. By considering scalar and vector linear potential for quark confinement and accounting with quantum corrections such as the centre-of-mass motion, gluonic, and pionic corrections, we establish a...
The presence of ultra-strong magnetic fields in magnetar induces significant spin polarization of baryons, profoundly affecting the equation of state (EoS) of dense nuclear matter. This study employs the CDM3Y interaction, a G-matrix-based M3Y interaction, within the Hartree-Fock framework to model spin-polarized nuclear matter in the presence of such extreme magnetic fields. By incorporating...
We investigate the effect of the pion mass on the quantum chromodynamics (QCD) phase diagram in the presence of an external magnetic field, aiming to understand it, for the first time, using Nambu\textendash Jona-Lasinio like effective models [1]. We compare results from both the local and nonlocal versions, finding that inverse magnetic catalysis (IMC) near the crossover is eliminated with...
Fluctuations and correlations of net-conserved quantities, including net-baryon, net-charge, and net-strangeness, are pivotal for exploring the QCD phase structure, as they are directly related to thermodynamic susceptibility ratios in lattice QCD (LQCD) calculations. These quantities probe the thermal properties of the medium and shed light on the nature of the strongly interacting matter...
We have estimated the induced electric field in quark-gluon plasma (QGP) due to its thermoelectric effects. At present, the relativistic heavy-ion collisions are capable of creating QGP, a locally thermalized medium composed of quarks and gluons.
During the space-time evolution of the QGP medium, interesting thermoelectric phenomena occur due to the presence of electrically charged particles...
We investigate the impact of finite volume effects on the QCD phase diagram, particularly in the context of ultrarelativistic heavy ion collisions. Utilizing the Nambu-Jona-Lasinio (NJL) model, we analyze the chiral transition line in the (T, ฮผB) plane with MIT boundary condition, simulating confinement within a fireball of limited dimensions. Our findings reveal that the transition...
We investigate the behavior of the chiral condensate within a Hadron Resonance Gas model, incorporating repulsive mean-field interactions among baryons. By calibrating the strength of these interactions to match the lattice QCD estimations of higher-order baryon charge susceptibilities, we can extend this model to higher baryon densities, where lattice QCD encounters challenges due to the sign...
Understanding the phases of quantum chromodynamics (QCD) matter has become one of the important research areas for both theoretical and experimental high-energy physics community. In the QCD phase diagram, which is characterised by temperature ($T$) and baryochemical potential ($\mu_B$), a first-order phase transition is expected at high $\mu_B$ and low T, which ends at a possible critical...
The proposed QCD Phase Diagram speculates deconfined Quark Matter at aymptotic high Temperature and Baryonic Densities. The region of QCD phase diagram characterized with low temperature and high baryonic density is been speculated to be found in the cores of neutron stars which are prone to phase transitions. The transition between the chiral and diquark condensate is being studied while...
The study of event-by-event mean transverse momentum ($\langle p_{\rm T} \rangle$) fluctuations is reported in terms of the integral two-particle correlator ($\langle \Delta p_{\rm T} \Delta p_{\rm T}\rangle$) and skewness of the event-wise $\langle p_{\rm T} \rangle$ distribution in proton$-$proton (pp) collisions at $\sqrt{s}=13$ TeV. The simulations were carried out using the Monte Carlo...
Higher order cumulants of the distributions of conserved quantities, like net-charge, net-baryon and net-strangeness in heavy-ion collisions, are regarded as sensitive observables to determine the freeze-out parameters and the nature of phase transitions at the LHC energies. Recently, several experimental results suggest the possible formation of QGP medium in high-multiplicity pp collisions....
Using a $(2+1)$-flavor Nambu--Jona-Lasinio (NJL) model, we study the effects of the strangeness chemical potential ($\mu_{S}$) and vector interactions on the chiral crossover lines, which we then use to examine flavor mixing within this framework. With the curvature coefficients, $\kappa_{2}$'s, showing excellent agreement with available lattice QCD (LQCD) findings, we estimate the permissible...
We estimate the transport coefficients like shear and bulk viscosities of hot hadronic matter in van der Walls hadron resonance gas ( VDW HRG ) model in the relaxation time approximation. We also have compared these results with excluded volume hadron resonance ( EV HRG ) calculations. ฮท/s decreases as the temperature of the hadronic system increases at a fixed baryon chemical potential. ฮท/s...
We investigate a hybrid approach of parametric and nonparametric
regression techniques to analyse the phase boundary between the
confined and deconfined phases of two-flavour quark matter. Data
derived from the Nambu-Jona-Lasinio (NJL) and Polyakov-loop extended
NJL (PNJL) models are trained and further used for the prediction of phase
transition boundaries with enhanced accuracy. We...
One of the outstanding challenges in the theory of strong interactions described by Quantum Chromodynamics is to understand its non-perturbative properties which can explain many important phenomena e.g., color confinement. In this work we study the non-perturbative sector of magnetic gluons whose momenta are given by $|\vec{p}|\leq g^2T/\pi$
in a finite temperature ($T$) QCD plasma...
Higher-order cumulants of (net-)proton multiplicity distributions are sensitive observables for studying the QCD phase structure. At low baryon chemical potential ($\mu_B$), lattice QCD calculations establish the quark-hadron transition to be a crossover, while at large $\mu_B$, QCD-based models predict a first-order phase transition that ends at a critical point.
Here, we focus on the...
In this presentation, we extend our previous investigations on intermittency using the Scaled Factorial Moment (SFM) technique in Au + Au collisions within the FAIR energy range of 2โ12A GeV. Building on our findings published in Eur.Phys.J.A 59 (2023) 4, 92, we now focus on the fluctuations in the number of protons, motivated by QCD-inspired predictions that suggest critical behavior...
Light (anti-)nuclei production in heavy-ion collisions can be described by two different mechanisms: the thermal and coalescence models. By analyzing the yields and ratios of the light (anti-)nuclei, we can gain valuable insights into their formation processes and the properties of the system at freeze-out. The enhancement in the compound ratios of light nuclei, such as $N_{t}N_{p}/N_{d}^{2}$...
We construct anย Euclideanย effective field theory (EFT) for thermal Quantum Chromodynamics (QCD)ย with $N_f=2$ย forย physics near crossover temperatureย usingย the global symmetries of QCD.ย A cut-offย scale isย used along with the ${\rm \overline{MS}}$ regularization schemeย and allย dimension six operators includingย current-current interactions and a gradient cubed termย are utilized.ย The gradient cubed...
Measurement of the event-by-event fluctuations of the mean transverse momentum, $\langle p_{\rm T} \rangle $, help to characterize the properties of the bulk of the system created in ultrarelativistic heavy-ion collisions, called the quark-gluon plasma (QGP). The fluctuations are closely related to the dynamics of the phase transition from the QGP to a hadron gas.
In this presentation, the...
We calculate the energy evolution of quark gluon plasma (QGP) under the two loop correction
at finite chemical potential. The calculation shows a good improvement over the energy evolution
without chemical potential and the stability formation is also obtained at the size of 1.8 fm. This
indicates that QGP droplet can be found with changing the quark and gluon flow parameters.
However...
Event-by-event fluctuations of the mean transverse momentum ($p_{\rm T}$) of relativistic charged particles are analyzed using the two-particle correlator, $\sqrt{C_m}/M(p_{\rm T})_m$ which quantifies the correlations strength in units of the mean $p_{\rm T}$ in proton-proton collision at $\sqrt{s} = 13$ TeV in ALICE both for Minimum Bias and and High-multiplicity triggered events. The...
The photon emission from a finite baryonic Quark-Gluon Plasma is analyzed through annihilation and Compton processes using the Boltzmann distribution function. This analysis incorporates a finite baryonic parameter into the quark mass and coupling constant. Accounting for this parameter enhances the photon production rate compared to earlier theoretical predictions based on this distribution...
We calculated the comparative Polyakov loop potential with chemical potential with temperature and chemical potential dependance. The result of Polyakov loop in these comparative outputs shows that there will be effect in the calculation of equation of state of Polyakov loop with the chemical potential dependance. There are number of calculations in this equation of state of the Polyakov loop...
