arXiv subjects

Pooja

Publications and source records attributed to Pooja.

18 recordsLinked to original sources

arXiv2026

Directed flow of D and B mesons in an electrically and chirally conductive QGP at LHC energies

We investigate the directed flow of D and B mesons in the presence of electromagnetic fields incorporating finite electrical and chiral conductivities at LHC energies. The momentum evolution of heavy quarks in the quark-gluon plasma (QGP) is studied using Langevin dynamics, with their interactions with the medium described within the extended quasiparticle model (QPMp) framework. The electromagnetic fields are obtained from analytical solutions of Maxwell equations that account for both electrical and chiral conductivities. These conductivities modify the space-time evolution of the electromagnetic fields and influence the splitting of the directed flow between mesons and anti-mesons. However, the influence of chiral conductivity remains secondary to that of electrical conductivity and its impact on the directed flow is marginal. The results show that heavy mesons containing a charm quark develop a directed flow with a sign opposite to that of heavy mesons containing a bottom quark, with a smaller magnitude for the latter. The present study indicates that a simultaneous experimental measurement of v1 for heavy mesons containing both charm and bottom quarks would provide valuable insight into the electromagnetic field origin of v1 for heavy quarks.

hep-ph↗

arXiv2026

The leading Lyapunov exponent in the glasma

We show that small perturbations in the boost-invariant color fields of the glasma exhibit an exponential growth with the square root of time. We interpret this growth rate as a Lyapunov exponent, related to entropy production and the thermalization timescale in the earliest stage of heavy-ion collisions. Working in a regime that is linear in this perturbation, we extract the time dependence of this mode as $\sim \exp(0.4\sqrt{g^2\mu\tau})$ for SU($2$), where $g^2\mu$ is proportional to the saturation scale and the square-root dependence is caused by the boost-invariant expansion of the system. We show that the growth rate of this mode is, unlike its amplitude, remarkably insensitive to the details of how the perturbations are initialized. In particular, we show that the unstable mode couples to all momentum scales present in the initial perturbation.

hep-ph↗

arXiv2024

Dynamics of Hot QCD Matter 2024 -- Hard Probes

The hot and dense QCD matter, known as the Quark-Gluon Plasma (QGP), is explored through heavy-ion collision experiments at the LHC and RHIC. Jets and heavy flavors, produced from the initial hard scattering, are used as hard probes to study the properties of the QGP. Recent experimental observations on jet quenching and heavy-flavor suppression have strengthened our understanding, allowing for fine-tuning of theoretical models in hard probes. The second conference, HOT QCD Matter 2024, was organized to bring the community together for discussions on key topics in the field. This article comprises 15 sections, each addressing various aspects of hard probes in relativistic heavy-ion collisions, offering a snapshot of current experimental observations and theoretical advancements. The article begins with a discussion on memory effects in the quantum evolution of quarkonia in the quark-gluon plasma, followed by an experimental review, new insights on jet quenching at RHIC and LHC, and concludes with a machine learning approach to heavy flavor production at the Large Hadron Collider.

nucl-ex↗

arXiv2024

Bulk-like structural, magnetic and optical properties of (111)- and (001)-NiO thin films

We have grown (111)- and (001)-oriented NiO thin films on (0001)-Sapphire and (001)-MgO substrates using pulsed laser deposition (PLD), respectively. DC magnetic susceptibility measurements underline that the N\'eel temperatures of the samples are beyond room-temperature. This is further confirmed by the presence of two-magnon Raman scattering modes in these films in ambient conditions. Moreover, relative intensity of the two magnon-mode with respect to a neighboring phonon mode in the films, at least down to 30 nm thickness, is comparable to the same for bulk NiO. UV-vis spectroscopy and spectroscopic ellipsometry determined that the bandgap of the films is 3.6 eV which is well within the range for bulk NiO. Thus, these indicate that the thin films are bulk-like. Further, photoluminescence measurements on (111)-NiO films obtained two-radiative transitions at 385 and 405 nm. The linewidth of the latter broadens towards low temperatures, indicating a plausible exciton-magnon coupling. Overall, these PLD-grown oxide films hold significant technological importance due to their optical transparency and their capacity to host robust magnons at room temperature.

cond-mat.mtrl-sci↗

arXiv2024

Continuous Sign Language Recognition System using Deep Learning with MediaPipe Holistic

Sign languages are the language of hearing-impaired people who use visuals like the hand, facial, and body movements for communication. There are different signs and gestures representing alphabets, words, and phrases. Nowadays approximately 300 sign languages are being practiced worldwide such as American Sign Language (ASL), Chinese Sign Language (CSL), Indian Sign Language (ISL), and many more. Sign languages are dependent on the vocal language of a place. Unlike vocal or spoken languages, there are no helping words in sign language like is, am, are, was, were, will, be, etc. As only a limited population is well-versed in sign language, this lack of familiarity of sign language hinders hearing-impaired people from communicating freely and easily with everyone. This issue can be addressed by a sign language recognition (SLR) system which has the capability to translate the sign language into vocal language. In this paper, a continuous SLR system is proposed using a deep learning model employing Long Short-Term Memory (LSTM), trained and tested on an ISL primary dataset. This dataset is created using MediaPipe Holistic pipeline for tracking face, hand, and body movements and collecting landmarks. The system recognizes the signs and gestures in real-time with 88.23% accuracy.

cs.LG↗

arXiv2024

Structural modulation driven Curie temperature enhancement in Cr-doped SrRuO3

Strongly correlated system with competing ground states are often poised close to the quantum critical point. External perturbations such as pressure, strain, electric field, and chemical doping can stabilise its ground state with exotic physical properties. Cr-doping is the lone exception which enhances the Curie-temperature in one of such correlated system SrRuO$_3$. To find the origin of $T_C$ enhancement, we investigate temperature-dependent structure, spectroscopic, magnetic and magnetotransport properties in SrRu$_{1-x}$Cr$_x$O$_3$. Cr-doping squeezes the unit cell volume which effectively enhances the stretching octahedral distortion by nearly five times than pure SrRuO$_3$. The Curie temperature increment by $\sim$ 22 K for x = 0.15 is found to be intertwined with the structural-modulation. Temperature-dependent Neutron diffraction analysis indicate that the unit cell volume minima coincide exactly with the enhanced ferromagnetic ordering ($\sim$ 190 K). Further analysis reveals that the effect of Cr-doping not only freezes the octahedral tilt below 100 K but also suppresses the complex magnetism responsible for exchange bias and topological hall effect in SrRuO$_3$. The spectroscopic measurements find a reduction of itinerancy of d-electrons with Cr-doping. The magnetotransport measurements portray an evolution from itinerant to localised ferromagnetism.

cond-mat.str-el↗

arXiv2024

Evolution of ferrimagnetism against Griffiths singularity in Calcium Ruthenate

The magnetism in the correlated metal CaRuO$_3$ is enigmatic as it is poised near a triple point among the ferromagnetic, antiferromagnetic, and paramagnetic ground states. Here we report a detailed work on structural, spectroscopic, magnetic, and transport properties in CaRu$_{1-x}$Cr$_x$O$_3$. We find that Cr doping reduces the orthorhombicity in CaRuO$_3$. Surprisingly, a tiny (x = 0.01) amount of Cr-doping drives the magnetic ground state from \enquote{paramagnetic-like} to ferrimagnetic. Slightly higher Cr-doping (x = 0.05) results formation of magnetic clusters which gives rise to Griffiths singularity and power law divergence in magnetic susceptibility. The magnetism in CaRu$_{1-x}$Cr$_x$O$_3$ is explained in terms of \enquote{seven atom} ferrimagnetic clusters. Electrical transport shows a gradual evolution of a non-metallic state upon Cr-doping. In particular, for x $\geq$ 0.1, the temperature-dependent resistivity follows Mott-VRH conduction. The XPS study also supports significant role of disorder and electron correlation which effectively reduces the itinerant character of electrons. Finally, a new T-x phase diagram is constructed depicting the evolution of electronic and magnetic state in CaRu$_{1-x}$Cr$_x$O$_3$.

cond-mat.str-el↗

arXiv2024

$c {\bar c}$ and $b {\bar b}$ suppression in Glasma

This study investigates the evolution and dissociation dynamics of $c\bar{c}$ and $b\bar{b}$ pairs within the pre-equilibrium, gluon-dominated stage of high energy nuclear collisions. An attractive potential made of a perturbative Coulomb-like term and of a confining term is used to simulate the attractive strong force in the pairs. Besides, we implement the interaction of the pairs with the evolving Glasma fields by virtue of the Wong equations. The interaction with the classical color fields dominates the dynamics, causing an increase in pair separation and subsequent dissociation. The observed finite probability of dissociation for these states reveals the intricate interplay between QCD dynamics and the suppression of $c\bar{c}$ and $b\bar{b}$ states during the pre-equilibrium stage. The research highlights differences between $c\bar{c}$ and $b\bar{b}$ pairs, revealing the role of quark flavor in the dissociation process. Dissociation spectra analysis indicates a peak shift towards higher momentum, reflecting a slight energy gain by the pairs. This investigation provides valuable insights into the complex dynamics of $c\bar{c}$ and $b\bar{b}$ pairs in the Glasma, which may help in better interpretation of experimental results on further integration with subsequent phases of the created matter.

hep-ph↗

arXiv2023

Thermalization and isotropization of heavy quarks in a non-Markovian medium in high-energy nuclear collisions

We study the isotropization and thermalization of heavy quarks in a non-Markovian medium in high energy nuclear collisions. In particular, we analyze the case of a non-stationary medium with a noise whose time-correlator decays as a power law (heavy tailed noise). We assume the correlations decay with an exponent $\beta-1$, $0\leq\beta<1$; we treat $\beta$ as a free parameter. We analyze the effect of memory on the thermalization and isotropization of heavy quarks in the medium via a generalized Langevin equation. In general, we find that memory slows down the dynamics of heavy quarks; moreover, thermalization and isotropization happen on the same time scale once a realistic initialization is considered. We also find that while the effect on charm quarks can be relevant, beauty quarks are hardly affected by memory in the quark-gluon plasma phase. Finally, we comment on the effect of memory on the estimate of $D_s$ of charm and beauty.

hep-ph↗

arXiv2023

Human activity recognition using deep learning approaches and single frame cnn and convolutional lstm

Human activity recognition is one of the most important tasks in computer vision and has proved useful in different fields such as healthcare, sports training and security. There are a number of approaches that have been explored to solve this task, some of them involving sensor data, and some involving video data. In this paper, we aim to explore two deep learning-based approaches, namely single frame Convolutional Neural Networks (CNNs) and convolutional Long Short-Term Memory to recognise human actions from videos. Using a convolutional neural networks-based method is advantageous as CNNs can extract features automatically and Long Short-Term Memory networks are great when it comes to working on sequence data such as video. The two models were trained and evaluated on a benchmark action recognition dataset, UCF50, and another dataset that was created for the experimentation. Though both models exhibit good accuracies, the single frame CNN model outperforms the Convolutional LSTM model by having an accuracy of 99.8% with the UCF50 dataset.

cs.CV↗

arXiv2022

Anisotropic fluctuations of angular momentum of heavy quarks in the Glasma

We study the evolution of the angular momentum of the heavy quarks in the very early stage of high energy nuclear collisions, in which the background is made of evolving Glasma fields. Given the novelty of the problem, we limit ourselves to the use of toy heavy quarks with a large, unphysical mass, in order to implement the kinetic equations for the angular momentum in the non-relativistic limit. We find that as a consequence of the anisotropy of the background fields, angular momentum fluctuations are also anisotropic: we understand this in simple terms relating the fluctuations of the angular momentum, $L$, to those of linear momentum. While orbital angular momentum diffuses and develops substantial fluctuations and anisotropies, the spin does not. Hence, we can identify the fluctuations of $L$ with those of the total angular momentum $J=L + S$. Therefore, our study suggests that the total angular momentum of the heavy quarks in the early stage of high energy nuclear collisions will present anisotropic fluctuations.

hep-ph↗

arXiv2022

Dynamics of Hot QCD Matter -- Current Status and Developments

The discovery and characterization of hot and dense QCD matter, known as Quark Gluon Plasma (QGP), remains the most international collaborative effort and synergy between theorists and experimentalists in modern nuclear physics to date. The experimentalists around the world not only collect an unprecedented amount of data in heavy-ion collisions, at Relativistic Heavy Ion Collider (RHIC), at Brookhaven National Laboratory (BNL) in New York, USA, and the Large Hadron Collider (LHC), at CERN in Geneva, Switzerland but also analyze these data to unravel the mystery of this new phase of matter that filled a few microseconds old universe, just after the Big Bang. In the meantime, advancements in theoretical works and computing capability extend our wisdom about the hot-dense QCD matter and its dynamics through mathematical equations. The exchange of ideas between experimentalists and theoreticians is crucial for the progress of our knowledge. The motivation of this first conference named "HOT QCD Matter 2022" is to bring the community together to have a discourse on this topic. In this article, there are 36 sections discussing various topics in the field of relativistic heavy-ion collisions and related phenomena that cover a snapshot of the current experimental observations and theoretical progress. This article begins with the theoretical overview of relativistic spin-hydrodynamics in the presence of the external magnetic field, followed by the Lattice QCD results on heavy quarks in QGP, and finally, it ends with an overview of experiment results.

nucl-th↗

arXiv2022

Memory effects on energy loss and diffusion of heavy quarks in the quark-gluon plasma

We study the dynamics of heavy quarks in a thermalized quark-gluon plasma with a time-correlated thermal noise, $\eta$. In this case it is said that $\eta$ has memory. We use an integro-differential Langevin equation in which the memory enters via the thermal noise and the dissipative force. We assume that the time correlations of the noise decay exponentially on a time scale, $\tau$, that we treat as a free parameter. We compute the effects of $\tau\neq 0$ on the thermalization time of the heavy quarks, on their momentum broadening and on the nuclear modification factor. We find that overall memory slows down the momentum evolution of heavy quarks: in fact, transverse momentum broadening and the formation of $R_{AA}$ are slowed down by memory and the thermalization time of the heavy quarks become larger. The potential impact on other observables is discussed briefly.

hep-ph↗

arXiv2021

Heavy quarks in the early stage of high energy nuclear collisions at RHIC and LHC: Brownian motion versus diffusion in the evolving Glasma

We study the transverse momentum, $p_T$, broadening of charm and beauty quarks in the early stage of high energy nuclear collisions. We aim to compare the diffusion in the evolving Glasma fields with that of a standard, Markovian-Brownian motion in a thermalized medium with the same energy density of the Glasma fields. The Brownian motion is studied via Langevin equations with diffusion coefficients computed within perturbative Quantum Chromodynamics. We find that for small values of the saturation scale, $Q_s$, the average $p_T$ broadening in the two motions is comparable, that suggests that the diffusion coefficient in the evolving Glasma fields is in agreement with the perturbative calculations. On the other hand, for large $Q_s$ the $p_T$ broadening in the Langevin motion is smaller than that in the Glasma fields. This difference can be related to the fact that heavy quarks in the latter system experience diffusion in strong, coherent gluon fields that leads to a faster momentum broadening due to memory, or equivalently to a strong correlation in the transverse plane.

hep-ph↗

arXiv2020

Repurposing the Combination Drug of Favipiravir, Hydroxychloroquine and Oseltamivir as a Potential Inhibitor against SARS-CoV-2: A Computational Study

The virus SARS-CoV-2 has created a situation of global emergency all over the world from the last few months. We are witnessing a helpless situation due to COVID-19 as no vaccine or drug is effective against the disease. In the present study, we have tested the applicability of some combination drugs against COVID-19. We have tried to understand the mechanism of action of some repurposed drugs: Favipiravir (F), Hydroxychloroquine (H) and Oseltamivir (O). The ADME analysis have suggested strong inhibitory possibility of F, H, O combination towards receptor protein of $3CL^{pro}$ of SARS-CoV-2 virus. The strong binding affinity, number of hydrogen bond interaction between inhibitor, receptor and lower inhibition constant computed from molecular docking validated the better complexation possibility of F+H+O: $3CL^{pro}$ combination. Various thermodynamical output from Molecular dynamics (MD) simulations like potential energy ($E_g$), temperature (T), density, pressure, SASA energy, interaction energies, Gibbs free energy ($\Delta G_{bind}$) etc., also favored the complexation between F+H+O and CoV-2 protease. Our In-Silico results have recommended the strong candidature of combination drugs Favipiravir, Hydroxychloroquine and Oseltamivir as a potential lead inhibitor for targeting SARS-CoV-2 infections.

physics.bio-ph↗

arXiv2020

Ivermectin and Doxycycline Combination as a Promising Drug Candidate Against SARS-CoV-2 Infection: A Computational Study

In the present study, we have described how by using molecular docking and molecular dynamic (MD) simulation studies the combination drug of ivermectin and doxycycline can be used as a potential inhibitor for SARS-CoV-2 virus. In lieu of unavailability of specific cure of COVID-19 till now various possibilities for individual and combination drugs have been explored by the medical practitioners/scientists for the remedial purpose of CoV-2 infections. $3CL^{pro}$ is the main protease of SARS-CoV-2 virus which plays an essential role in mediating viral replication in the human body. $3CL^{pro}$ protein can serve as an attractive drug target. In this work, we have studied drug: $3CL^{pro}$ interactions by in silico molecular docking and MD simulation approaches. Common and easily available antiviral drugs ivermectin, doxycycline and their combination have been proved their valid candidature to be used as potential drug candidates against SARS-CoV-2 infections.

physics.bio-ph↗

arXiv2020

Optical and Electronic Properties of CdTe Quantum Dots in their Freezed Solid Matrix Phase and Solution Phase

The present work deals with the comparison of sizes, optical and electronic properties of COOH functionalized CdTe quantum dots (QDs) in freezed solid polymeric (polyvinyl alcohol (PVA) matrix and in solution phase (water). PVA has been chosen as host material for guest CdTe QDs because of its unique properties like hydrophilicity, good thermo stability, and easy process ability. Experimental absorption, emission, X-Ray diffraction spectra and electronic band gap have been studied by UV-Vis absorption, luminescence and X-Ray diffraction spectroscopy. The smaller size of CdTe QDs in solid PVA polymer matrix (~ 6 nm) and larger band gap of ~9.5 eV validates their quantum confinement regime in freezed solid phase. The smaller particle size in solid phase compared to that of the particle size in its solution phase (8 nm) validates the non existence of agglomeration in solid phase. Appearance of high intense and wide luminescence emission in solid form proves the strong candidature of CdTe QDs as promising sensors for today's optoelectronic and biomedical industry.

cond-mat.mtrl-sci↗

arXiv2020

Functionalized CdTe Fluorescence Nanosensor for the Sensitive Detection of Water Borne Environmentally Hazardous Metal Ions

In this work, we have investigated the possibility of using COOH functionalized CdTe quantum dots (QDs) as fluorescent nanosensor for the detection of some environmentally hazardous metal ions ($\rm{Cr^{3+}}$, $\rm{Pb^{2+}}$, $\rm{Cu^{2+}}$, $\rm{Zn^{2+}}$ and $\rm{Co^{2+}}$) in aqueous phase. COOH-CdTe QDs are prepared in aqueous medium and characterized by UV-visible, photo luminescence and FTIR spectrometry. Optical response of CdTe nanosensor is observed to be time and temperature dependent. A strong "Turn-Off" fluorescence response of CdTe is observed in presence of all metals ions ($\rm{X^{n+}}$). The output of Stern volmer relation, graphical Job's plot and FTIR data established the existence of strong 1:1 complexation ($\rm{X^{n+}: ^{-}OOC-CdTe)}$ between CdTe and metal ions. CdTe shows its efficient sensing ability for $\rm{Pb^{2+}}$, $\rm{Cr^{3+}}$ and $\rm{Cu^{2+}}$ ions up to concentration $\rm{10^{-14}}$ M which was established by its low detection of limit (LOD)validation. Further, strong appearance of $\frac{F-F_{0}}{F_{0}}$ establishes the better sensing capability of CdTe QDs for $\rm{Cr^{3+}}$, $\rm{Pb^{2+}}$, $\rm{Cu^{2+}}$ ions which are far better than the existing fluorescent sensors available in industry. The proposed optical techniques and principal component analysis of sensing were successfully applied for testing of dissolved metal ions in real samples like: paint, river water, rain water etc which validates the applicability of COOH functionalized CdTe nanosensor as a effective successful optical sensor for water dissolved metal ions which are responsible for water pollution.

physics.chem-ph↗