arXiv subjects

Rishabh Sharma

Publications and source records attributed to Rishabh Sharma.

30 records · Page 2Linked to original sources

arXiv2023

Dissociation and thermodynamical properties of heavy quarkonia in an anisotropic strongly coupled hot QGP: using baryonic chemical potential

We extended the recent work Phys. Rev. D 97(9), 094033 (2018) to investigate quarkonium dissociation in presence of baryonic chemical potential (mu_b) and anisotropy (ξ) using quasi-particle approach in hot quantum chromodynamics (QCD) medium. We have determined binding energy and thermal width of S-states of charmonia and bottomonia for n=1 and n=2 (radial quantum number) with anisotropic parameter (ξ) and baryonic chemical potential. We have also determined the effects of baryonic chemical potential and anisotropy on mass spectra of 1S-states of quarkonia and the results obtained were consistent with theoretical and experimental works. But the key result obtained was dissociation temperature of the S-states with the effect of {mu_b} and ξ. At last, we have calculated the thermodynamical properties of QGP (i.e., pressure, energy density and speed of sound) using the parameter ξ and {mu_b}, which is the main key to study suppression of the quarkonium with latest determined value of energy density psNN after incorporating the effect of ξ and (mu_b).

hep-ph↗

arXiv2023

Study of Quarkonium properties using SUSYQM method with baryonic chemical potential

In this article, we employed the Quasi-particle debye mass at finite baryonic chemical potential which can be used in the medium modified heavy quark potential to solve the N-dimensional Schroedinger equation. The bound state solution of the Schroedinger equation using Cornell potential is obtained by Super-Symmetry Quantum Mechanics (SUSYQM) method. The thermodynamical properties of quark matter is calculated by using baryonic chemical potential (mu). We found that the binding energy of quarkonia dissociates more with quasi-particle debye mass in comparison to non-perturbative and leading order debye mass. The medium modified form of potential (real part) has been used to study the thermodynamical properties of quark matter with different equation of states (EoS) (i.e., pressure, energy density and speed of sound) with {mu}. The mass spectra of quarkonia has been also calculated in the N-dimensional space, and compared with the experimental data at N=3. We have also calculated the dissociation temperature (T_D) for the ground states of quarkonium using the dissociation criteria of thermal width.

hep-ph↗

arXiv2023

Encoding Robust and Fast Memories in Bulk and Nanoscale Amorphous Solids

We investigate the memory effects under oscillatory shear deformation of amorphous solids through computer simulations. Applications of shear deformations in all orthogonal directions show that encoded memories via this protocol are more robust while performing reading. Our extensive system size analysis of memory effects shows that memory encoding in small systems is faster than in larger systems and is probably impossible in thermodynamically large system sizes. In addition to demonstrating how to encode robust memories in 3D bulk amorphous materials, we devise protocols for encoding and reading memories in pseudo-1D materials in the form of amorphous nano-rods. With this, we show that memory encoding and retrieving can also be done in systems with open surfaces, which all materials would necessarily have in practice, and is thus essential to capitalise on the effectiveness of smaller system sizes to encode memories faster. All in all, we provide protocols for encoding robust and faster memories in amorphous solids both at bulk and nanoscale.

cond-mat.soft↗

arXiv2023

Elliptic flow of light nuclei in Au+Au collisions at $\sqrt{s_{NN}}$ = 14.6, 19.6, 27, and 54.4 GeV using the STAR detector

Loosely bound light nuclei are produced in abundance in heavy-ion collisions. There are two main possible models to explain their production mechanism - the thermal model and the coalescence model. The thermal model suggests that the light nuclei are produced from a thermal source, where they are in equilibrium with other species present in the fireball. However, due to the small binding energies, the produced nuclei are not likely to survive the high-temperature conditions of the fireball. The coalescence model tries to explain the production of light nuclei by assuming that they are formed at later stages by the coalescence of protons and neutrons near the kinetic freeze-out surface. The final-state coalescence of nucleons will lead to the mass number scaling of the elliptic flow ($v_2$) of light nuclei. This scaling states that the $v_2$ of light nuclei scaled by their respective mass numbers will follow very closely the $v_2$ of nucleons. Therefore, studying the $v_2$ of light nuclei and comparing it with the $v_2$ of protons will help us in understanding their production mechanism. In this talk, we will present the transverse momentum ($p_{T}$) and centrality dependence of $v_2$ of $d$, $t$, and $^3\text{He}$ in Au+Au collisions at $\sqrt{s_{NN}}$ = 14.6, 19.6, 27, and 54.4 GeV. Mass number scaling of $v_2(p_T)$ of light (anti-)nuclei will be shown and physics implications will be discussed.

nucl-ex↗

arXiv2023

Melting of Quarkonia in strong magnetic field

In this paper, spectra of the quarkonium states has been studied using the conditions temperature, chemical potential and the magnetic field. Here our main focus is to study the effect of strong magnetic field on the quarkonium properties. The binding energies and the dissociation temperature for the ground and the first excited states of the charmonium and bottomonium in the presence of strong magnetic field at chemical potential μ= 500 MeV has been studied. Here we use quasiparticle (QP) Debye mass depending upon temperature, magnetic field and chemical potential obtained from the quasiparticle approach. The Debye mass strongly increases at different values of temperature and magnetic field. The binding energy decreases with increase in the temperature at different magnetic field eB= 0.3, 0.5, and 0.7 GeV2 and also decreases with magnetic field at different at T=200,300 and 400 MeV for the J/ψ, ψ, \upsilon, and \upsilon prime states of the quarkonia. The dissociation temperature of the quarkonium states falls with the increasing values of the magnetic field at critical temperature Tc =197 MeV

hep-ph↗

arXiv2023

Anisotropic behavior of S-wave and P-wave states of heavy quarkonia at finite magnetic field

We studied the effect of momentum space anisotropy on heavy quarkonium states using an extended magnetized effective fugacity quasiparticle model (EQPM). Both the real and imaginary part of the potential has been modified through the dielectric function by including the anisotropic parameter $ξ$. The real part of the medium modified potential becomes more attractive in the presence of the anisotropy and constant magnetic field. The binding energy of the 1S, 2S, and 1P quarkonium states including anisotropy effects for both the oblate and the isotropic case were studied. We find that the binding energy of quarkonium states becomes stronger in the presence of anisotropy. However, the magnetic field is found to reduce the binding energy. The thermal width of the charmonium and bottomonium 1S states have been studied at constant magnetic field eB = 0.3 GeV2 for isotropic and prolate cases. The effect of magnetic field on the mass spectra of the 1P state for the oblate case was also examined. The dissociation temperature for the 1S, 2S, and 1P charmonium and bottomonium have been determined to be higher for the oblate case with respect to the isotropic case

hep-ph↗

arXiv2023

Activity-Induced Annealing leads to Ductile-to-Brittle Transition in Amorphous Solids

Investigating the behavior of amorphous solids under various external loading conditions continues to be an intriguing area of research with significant practical implications. In this study, we demonstrate the utilization of self-motility as a means to anneal glasses and use that as a means to fine-tune the failure mode of the system under uniaxial tensile deformation. We begin by highlighting the annealing effects of activity and draw parallels with other well-known mechanical annealing processes, such as oscillatory shearing (both uni- and multi-directional). Furthermore, we explore the annealing effects in the presence of open boundaries, observing enhanced surface relaxations due to activity. By implementing various activity-induced annealing protocols, we successfully induce a transition in the failure mode from ductile to brittle. This is demonstrated via performing tensile tests on the glass samples resulting from the active-annealing process. The intricate effects of geometry on the formation of shear bands are also examined. We find that samples having an aspect ratio greater than one fail via shear band formation, owing to their formation angle of $45\degree$ from the strain axis. In conclusion, we introduce a novel method for producing well-annealed glasses in silico and establish a correspondence between sheared and actively driven glasses.

cond-mat.soft↗

arXiv2023

Cavitation instabilities in amorphous solids via secondary mechanical perturbations

Amorphous solids are known to fail catastrophically and in some situations, nano-scaled cavities are believed to play a significant role in the failure. In a recent work, using numerical simulations, we have shown the correspondence between cavitation under uniform expansion of amorphous solids and the yielding under shear. In this study, we probe the stability of spatially-homogeneous states sampled from expansion trajectories to alternate modes of driving, viz. macroscopic cyclic shear or local random deformation via activity. We find that, under cyclic shear and activity, the cavitation instabilities can occur in expanded states at much higher densities than under pure uniform-expansion, and the shift in density is determined by the magnitude of the secondary deformation. We also show that barriers to cavitation on the energy landscape are much smaller for cyclic-shear and activity than seen under expansion. Further, we also analyse the spatial manifestation of cavitation and investigate whether large scale irreversible plasticity can set in due to the combination of expansion and the secondary deformation. Overall, our study reveals the interplay between expansion and other deformation modes leading to cavitation instabilities and the existence of abundant relaxation pathways for such processes.

cond-mat.soft↗

arXiv2022

Collective flow of light nuclei and hyper-nuclei in Au+Au collisions at $\sqrt{s_{NN}}$ = 3, 14.6, 19.6, 27, and 54.4 GeV using the STAR detector

Light nuclei and hyper-nuclei are produced in abundance in heavy-ion collisions. The production mechanism of these species in heavy-ion collisions still remains to be understood. In these proceedings, we report the transverse momentum and centrality dependence of elliptic flow ($v_2$) of $d$, $t$, and $^3\text{He}$ in Au+Au collisions at $\sqrt{s_{NN}}$ = 14.6, 19.6, 27, and 54.4 GeV. Mass number scaling of $v_2(p_T)$ of light nuclei is shown. We also report the first observation of hyper-nuclei $^{3}_Λ$H and $^{4}_Λ$H directed flow ($v_1$) in $\sqrt{s_{NN}}$ = 3 GeV mid-central (5-40\%) Au+Au collisions in the fixed target mode.

nucl-ex↗

arXiv2022

Gradient Based Activations for Accurate Bias-Free Learning

Bias mitigation in machine learning models is imperative, yet challenging. While several approaches have been proposed, one view towards mitigating bias is through adversarial learning. A discriminator is used to identify the bias attributes such as gender, age or race in question. This discriminator is used adversarially to ensure that it cannot distinguish the bias attributes. The main drawback in such a model is that it directly introduces a trade-off with accuracy as the features that the discriminator deems to be sensitive for discrimination of bias could be correlated with classification. In this work we solve the problem. We show that a biased discriminator can actually be used to improve this bias-accuracy tradeoff. Specifically, this is achieved by using a feature masking approach using the discriminator's gradients. We ensure that the features favoured for the bias discrimination are de-emphasized and the unbiased features are enhanced during classification. We show that this simple approach works well to reduce bias as well as improve accuracy significantly. We evaluate the proposed model on standard benchmarks. We improve the accuracy of the adversarial methods while maintaining or even improving the unbiasness and also outperform several other recent methods.

cs.LG↗

arXiv2021

Deep Learning methods for automatic evaluation of delayed enhancement-MRI. The results of the EMIDEC challenge

A key factor for assessing the state of the heart after myocardial infarction (MI) is to measure whether the myocardium segment is viable after reperfusion or revascularization therapy. Delayed enhancement-MRI or DE-MRI, which is performed several minutes after injection of the contrast agent, provides high contrast between viable and nonviable myocardium and is therefore a method of choice to evaluate the extent of MI. To automatically assess myocardial status, the results of the EMIDEC challenge that focused on this task are presented in this paper. The challenge's main objectives were twofold. First, to evaluate if deep learning methods can distinguish between normal and pathological cases. Second, to automatically calculate the extent of myocardial infarction. The publicly available database consists of 150 exams divided into 50 cases with normal MRI after injection of a contrast agent and 100 cases with myocardial infarction (and then with a hyperenhanced area on DE-MRI), whatever their inclusion in the cardiac emergency department. Along with MRI, clinical characteristics are also provided. The obtained results issued from several works show that the automatic classification of an exam is a reachable task (the best method providing an accuracy of 0.92), and the automatic segmentation of the myocardium is possible. However, the segmentation of the diseased area needs to be improved, mainly due to the small size of these areas and the lack of contrast with the surrounding structures.

eess.IV↗

arXiv2019

FireNet: A Specialized Lightweight Fire & Smoke Detection Model for Real-Time IoT Applications

Fire disasters typically result in lot of loss to life and property. It is therefore imperative that precise, fast, and possibly portable solutions to detect fire be made readily available to the masses at reasonable prices. There have been several research attempts to design effective and appropriately priced fire detection systems with varying degrees of success. However, most of them demonstrate a trade-off between performance and model size (which decides the model's ability to be installed on portable devices). The work presented in this paper is an attempt to deal with both the performance and model size issues in one design. Toward that end, a `designed-from-scratch' neural network, named FireNet, is proposed which is worthy on both the counts: (i) it has better performance than existing counterparts, and (ii) it is lightweight enough to be deploy-able on embedded platforms like Raspberry Pi. Performance evaluations on a standard dataset, as well as our own newly introduced custom-compiled fire dataset, are extremely encouraging.

cs.CV↗