arXiv subjects

B. K. Singh

Publications and source records attributed to B. K. Singh.

At least 19 recordsLinked to original sources

arXiv2026

Separating non-collective effects in d-Au collisions

In this work, we present the multiplicity and yield of charged hadrons and particle ratios in d-Au collisions at $\sqrt{s_{NN}}= 200$ GeV using the PYTHIA8/Angantyr. The model reproduces the multiplicity ($N_{ch}$) and pseudo-rapidity distribution reasonably well in minimum-biased d-Au collisions without assuming the formation of a thermalized medium. The invariant yield from Angantyr underpredicts the data in central collisions. We discussed the similarity between the nuclear modification factor $R_{AA}$ and data/MC from Angantyr and the possibility of using it as a model-dependent observable to check in-medium effects. The data/MC suggests that the central d-Au collisions exhibit signals like baryon enhancement, but no high $p_T$ suppression was found. The d-Au collisions have a much smaller invariant yield than the thermal model calculation for similar $N_{part}$.

nucl-th↗

arXiv2026

Effects of Geometric configuration in relativistic isobaric collisions at $\sqrt{s_{NN}}=200$ GeV

In this work, we present a study on the effects of nuclear deformation ($β_2$,$β_3$) and surface diffuseness ($a$) on the charged hadron multiplicity ($N_{\mathrm{ch}}$) and elliptic flow ($v_2$), obtained in symmetric isobaric collisions of ${}^{96}_{44}\mathrm{Ru} + {}^{96}_{44}\mathrm{Ru}$ and ${}^{96}_{40}\mathrm{Zr} + {}^{96}_{40}\mathrm{Zr}$. The two extreme configurations (tip-tip and body-body) were used to determine the correlation between the final state observables and initial geometry using the HYDJET++ model. The octupole deformation parameter ($β_3$) enhances $N_{\mathrm{ch}}$ in central tip-tip Zr+Zr collisions and suppresses it in peripheral ones. In mid-central to peripheral body-body Zr+Zr collisions, $β_3$ leads to a reduction in charged hadron production. Surface-diffuseness ($a$), along with quadrapole deformation ($β_2$), also shows a significant impact on multiplicity and elliptic flow. The octupole deformation enhances elliptic flow in Zr's body-body collisions. Results are compared with the STAR blind-analysis data where available.

nucl-th↗

arXiv2026

Physics-informed neural network (PINN) modeling of charged particle multiplicity using the two-component framework in heavy-ion collisions: A comparison with data-driven neural networks

In this study, we employ a conventional deep neural network (NN) framework integrated with physics-based constraints to predict charged hadron multiplicity ($N_{\text{ch}}$) in heavy-ion collisions. The goal is to assess the performance of a purely data-driven deep neural network in comparison to a physics-informed neural network (PINN). To accomplish this, we have taken data generated from the HYDJET++ model for testing and training purposes. We train our neural network frameworks using the data of one million individual $^{96}_{40}\text{Zr}+^{96}_{40}\text{Zr}$ collision events. Our PINN model successfully extracts the hard-scattering fraction ($x$) by learning its underlying relation from the event data. For further testing and comparison with the conventional NN, we take data of $^{96}_{44}\text{Ru}+^{96}_{44}\text{Ru}$ (isobar of Zr) and $^{197}_{79}\text{Au}+^{197}_{79}\text{Au}$ collisions using the same simulation model. We found that the NN model needs more time to train with physics. However, once trained, the PINN model is capable of accurately predicting data that it has not encountered during training, such as Au+Au collision results. Especially in a region of sparse data corresponding to high $N_{\text{ch}}$ in our study, PINN has a clear advantage over a simple NN.

hep-ph↗

arXiv2026

Two-particle cumulant distribution: a simulation study of higher moments

In this work, we have shown the two-particle correlations of charged hadrons in d-Au collisions at 200 GeV in PYTHIA8/Angantyr simulations. These correlations were studied at different multiplicities and pseudorapidity intervals. The two-particle correlations arise due to color reconnections, resonance decays, jet correlations, and hadronic rescattering. These correlations are inversely proportional to multiplicity but remain unaffected for larger pseudorapidity windows. We treated these correlations as distributions and calculated their skewness and kurtosis. The non-flow distributions deviate greatly from a Gaussian distribution and have high skewness and kurtosis. The ``true" elliptic flow distributions resemble Gaussian distributions; they have significantly lower skewness and kurtosis. We suggest that if the two-particle cumulant flow is treated as an event-by-event distribution, its skewness and kurtosis can be instrumental in distinguishing true flow and non-flow.

hep-ph↗

arXiv2026

Statistical properties of non-flow correlations in pp and heavy-ion collisions at RHIC energies

In this work, we have studied the two-particle cumulant in pp, d-Au, and Au-Au collisions. The two-particle cumulant was treated as an event-by-event distribution, and its skewness and kurtosis were analyzed. The non-flow correlations, like jets and decays, constantly produced a skewed distribution, regardless of the model used. On the contrary, HYDJET++ produced a smooth Gaussian distribution at higher $η$ windows in fixed impact parameter collisions. The skewness increased consistently for higher $η$ windows in all non-QGP models like PYTHIA, PHOJET, QGSJET, and DPMJET. The kurtosis of the distribution also increased with $η$ windows in non-QGP models. The skewness and kurtosis of the distributions produced by HYDJET++ decreased with $Δη$ and eventually reached zero at higher $Δη$.

nucl-th↗

arXiv2026

Medium-Induced Quarkonium Dissociation at Finite Chemical Potential and Weak Magnetic Field

We investigate the in-medium modification and dissociation of heavy quarkonium in a hot QCD medium at finite quark chemical potential and in the weak magnetic-field regime. Starting from the one-loop resummed gluon propagator in the imaginary-time formalism, and incorporating non-perturbative effects through a phenomenological correction to the HTL description, we compute the real and imaginary parts of the dielectric permittivity. This, in turn, leads to a complex heavy-quark potential: the real part is used to determine binding energies by solving the nonrelativistic Schrödinger equation, while the imaginary part generates thermal decay widths, dominated by Landau damping. Within the explored parameter range, temperature has the greatest control over Debye screening, potential modification, and quarkonium stability, whereas finite density and weak magnetic fields introduce comparatively smaller quantitative changes. As the temperature increases, binding energies decrease and thermal widths grow, giving rise to the expected hierarchy between ground and excited states and a sequential suppression pattern in the dissociation temperatures. Overall, our results indicate that while finite chemical potential and weak magnetic fields can shift quarkonium properties in a measurable way, thermal effects remain the primary driver of dissociation, with direct relevance for heavy-ion collision phenomenology.

hep-ph↗

arXiv2025

Study of Particle Production in Au+Au Collisions at $\sqrt{s_{NN}} =$ 11.5-200 GeV Using HYDJET++ Framework

Using the HYDJET++ model, we study the production of multi-strange particles($ϕ$ and $Ω$) in Au+Au collisions at $\sqrt{s_{NN}} =$ 11.5, 19.6, 27, 39, and 200 GeV as functions of transverse momentum and centrality. The model calculations employ earlier freeze-out hypersurfaces for multi-strange particle production and are compared with STAR experimental data. Results indicate that the HYDJET++ model demonstrates a better agreement with experimental data for multi-strange particles at higher energies, particularly in relation to early thermal freeze-out. Meanwhile, the default version performs more accurately for lighter, non-strange particles at the same energy scales. We also analyze identified particle and mixed particle ratios, providing insights into strangeness enhancement. The results provide additional constraints on parton energy loss models, contributing to a more precise determination of the transport properties of hot and dense QCD matter.

hep-ph↗

arXiv2025

A study of pure multi-strange hadrons production in Pb+Pb collisions at LHC energies using HYDJET++ model

For the present work, we have used the HYDJET++ model to explore the production of pure multi$-$strange hadrons in Pb+Pb collisions at $\sqrt{s_{NN}}$= 2.76 TeV and $\sqrt{s_{NN}}$= 5.02 TeV collision energies, respectively. \textcolor{red}{We have performed simulation to investigate transverse momentum ($p_{T}$) spectra and elliptic flow ($v_{2}$) for $ϕ-$meson and $Ω-$baryons, and compared the results with ALICE experimental data as well as predictions from various phenomenological models across different centrality classes. Furthermore, we have calculated the nuclear modification factors ($R_{AA}$ and $R_{CP}$), which provide a perception of jet quenching phenomena. Hence, our findings enable the study of the energy and system dependence of $ϕ$ and $Ω$ hadrons production over a wide range of ultra-relativistic collision energies. We also present the particle ratios ( $Ω/ϕ$, $\overlineΩ^{+}/Ω^{-}$, $Ω/π$, and $ϕ/π$ ), offering insights into the strangeness enhancement and chemical properties of the medium at both LHC collision energies. Additionally, we explored the predictions for $Ω$-baryon in Pb+Pb collisions at$\sqrt{s_{NN}}$= 5.02 TeV, focusing on $R_{AA}$, $R_{CP}$, and particle ratios within the HYDJET++ framework, offering insights into future measurements and particle dynamics in high-energy heavy-ion collisions.

hep-ph↗

arXiv2025

Pseudorapidity density, transverse momentum spectra, and elliptic flow studies in Xe-Xe collision systems at $\rm{\sqrt{s_{NN}} = 5.44 TeV}$ using the HYDJET++ model

In this paper, we present a systematic study of Xe--Xe collisions at $\sqrt{s_{\mathrm{NN}}} = 5.44$~TeV center-of-mass energy. We employ the Monte Carlo (hydrodynamics plus jets) HYDJET++ model to calculate the pseudorapidity distribution, transverse momentum ($p_{\mathrm{T}}$) spectra, and the elliptic flow ($v_2$) of charged hadrons with different parameters in two geometrical configurations: body-body and tip-tip types of Xe--Xe collisions. The kinematic ranges $0 < p_{\mathrm{T}} < 50~\mathrm{GeV}/c$ and $|η| < 0.8$ are considered in our study. Results are obtained for seven classes of centrality. For comparison, we have shown results from the AMPT model with the string-melting version. The results obtained for Xe--Xe collision systems for minimum bias at midrapidity match well with the experimental data from the ALICE and CMS Collaborations. We observe that the pseudorapidity density depends on the size and geometry of the colliding system. The centrality dependence of average transverse momentum ($\langle p_{\mathrm{T}} \rangle$) and average elliptic flow ($\langle v_2 \rangle$) is also observed. The charged hadron properties also show clear dependence on the geometrical configuration of the collisions. Our model results have been compared to results obtained from the AMPT model. The HYDJET++ model matches the experimental data more closely than the AMPT model, which tends to overpredict the data.

hep-ph↗

arXiv2025

Higher-order anisotropic flow correlations in Xe-Xe collisions at $\mathrm{\sqrt{s_{NN}}= 5.44 TeV}$

By employing the Monte Carlo HYDJET++ model (HYDrodynamics plus JETs), we produce anisotropic harmonic flow coefficients $v_n$ ($n = 4$-$7$) in deformed Xe-Xe collisions at $\sqrt{s_{NN}} = 5.44~\mathrm{TeV}$. These harmonics are measured with respect to a plane constructed using the lower-order Fourier harmonics $v_2$ and $v_3$, produced using the reaction plane method. The cross-talk between elliptic and triangular flows in the model generates both even and odd higher-order harmonics. By combining analyses of higher harmonics with those of $v_2$ and $v_3$, one can eliminate uncertainties in modeling anisotropic flow from initial conditions and define quantities that involve only nonlinear hydrodynamic response coefficients. In this context, we study the individual response of higher-order flow coefficients to the lower-order ones through a power-law scaling technique of the form $v_n / v_m^m$, as a function of collision centrality. We report that the higher-order flow coefficients $v_n$ ($n = 4$-$7$) exhibit strong centrality dependence and are significantly correlated with the elliptic and triangular flow. The results are compared with data from recent ALICE, ATLAS, and CMS experiments at the LHC.

hep-ph↗

arXiv2025

Study of octupole deformations in Pb-Pb collisions at 5.02 TeV

In this letter, we present the study of the role of octupole deformation in non-spherical nuclei in most-central Pb--Pb collisions at the LHC energy regime. The sensitivity of octupole deformation $β_3$ to the QGP observables is presented by employing the Monte Carlo HYDJET++ model. Motivated by the discrepancies in the $v_2$-to-$v_3$ puzzle found in Pb--Pb collisions and the low-energy nuclear structure calculations of nuclear deformation, we studied the first basic observables necessary for any study in heavy-ion collisions. Using the HYDJET++ framework, we calculate the pseudorapidity distribution, transverse momentum ($p_{\mathrm{T}}$) spectra, and average anisotropic flow ($v_2$ and $v_3$) of primary charged hadrons with different parameters in two geometrical configurations: body-body and tip-tip types of Pb--Pb collisions. The kinematic ranges $0 < p_{\mathrm{T}} < 20~\mathrm{GeV}/c$ and $|η| < 0.8$ are considered. We observe that the charged hadron multiplicity and transverse momentum spectra are dependent on the strength of the octupole deformation parameter. The $\langle v_2 \rangle$ and $\langle v_3 \rangle$ in body-body collisions show a weak positive correlation with $β_3$, while the average anisotropic flow in tip-tip collisions is weakly correlated with $β_3$ in the most-central collision region.

hep-ph↗

arXiv2025

Beam energy dependence of transverse momentum distribution and elliptic flow in Au-Au collisions using HYDJET++ model

In this work, we present the particle ratios, transverse momentum spectra, and elliptic flow ($v_2$) of $π^\pm,k^\pm,$ $p$, and $\bar{p}$ in Au-Au collisions at $\sqrt{s_{NN}}=$ 62.4, 39.0, 27.0, 19.6 and 11.5 GeV using HYDJET++ model. The particle ratios match the experimental data that validates the Cleymans-Reidlich parameterization of freeze-out parameters at lower beam energies under the HYDJET++ framework. The lower collision energies produce a system of high baryon chemical potential ($μ_B$) and have a lower inelastic cross section. The interplay between these effects affects the overall shape of the $p_T$ spectra. The HYDJET++ model calculations for $p_T$ spectra agree well with the available experimental data. The invariant yield ratio of central and peripheral collisions is independent of beam energy. The elliptic flow is calculated based on the scaling between initial and final azimuthal spatial anisotropy ($k$). This interpretation of $v_2$ successfully describes the experimental data for all the collision energies studied in this work. The positive correlation of $k$ with beam energy leads to a small $v_2$ at lower collision energies. The hadrons containing strange quarks tend to have smaller values of $k$ than the non-strange hadrons.

hep-ph↗

arXiv2025

A background for thermal photons in heavy ion collisions

In this work, we present the transverse momentum spectra of prompt and decay photons in Au-Au collisions for $\sqrt{s_{NN}}=$ 200 GeV, 62.4 GeV, 39 GeV, and 27 GeV. The major sources of the photons in Angantyr include hard processes, Parton showers, and resonance decay. The multiparton interactions and hadronic rescatterings significantly increase the photon yield. The model shows a good match with the available experimental data at high $p_T$. The difference in yield at low $p_T $ suggests that Quark Gluon Plasma of $T_{eff}$ = 0.167 GeV/c in central Au-Au collision at 200 GeV is formed, the new effective temperature is less than the ones extracted without removing background photons. At low $p_T$ the decay photon spectra scales with $(\frac{dN_{ch}}{dη})^{1.25}$, the scaling is independent of collision energy and system size. The scaling no longer holds at high $p_T$ and the spectra become beam energy dependent. The scaled $p_T$ spectra of p-p and d-Au collisions show an opposite trend at high $p_T$, their scaled yield is greater than the Au-Au collision at the same energy.

nucl-ex↗

arXiv2024

Quarkonia dissociation at finite magnetic field in the presence of momentum anisotropy

In this study, we investigate the potential of heavy quarkonia within a magnetized hot QGP medium having finite momentum anisotropy. The phenomenon of inverse magnetic catalysis is introduced into the system, influencing the magnetic field-modified Debye mass and thereby altering the effective quark masses. Concurrently, the impact of momentum anisotropy in the medium is considered that influence the particle distribution in the medium. The thermal decay width and dissociation temperature of quarkonium states, specifically the 1S and 2S states of charmonium and bottomonium, are computed. Our results reveal that both momentum anisotropy and the inverse magnetic catalysis effects play a significant role in modifying the thermal decay width and dissociation temperature of these heavy quarkonia states.

hep-ph↗

arXiv2023

Predicting Quadrupole deformation via anisotropic flow and transverse momentum spectra in isotopic $\mathbf{\prescript{128-135}{54}{\mathrm{Xe}}}$ collisions at LHC

In the hydrodynamical description of heavy-ion collisions, the elliptic flow $\mathrm{v_{2}}$ and triangular flow $\mathrm{v_{3}}$ are sensitive to the quadrupole deformation $\mathrm{β_{2}}$ of the colliding nuclei. We produce $\mathrm{v_{2}}$ and $\mathrm{v_{3}}$ ratios qualitatively and quantitatively in most-central Xe-Xe collisions at 5.44 TeV. By employing HYDJET++ model, we study the sensitivity of anisotropic flow coefficients and mean transverse momentum to the quadrupole deformation and system-size in isotopic Xe-Xe collisions. Flow observables strongly depend on the strength of nucleon-nucleon scattering occuring in even-A and odd-A nuclei. Flow for odd-A nuclei is suppressed in comparison to flow in even-A collisions. There exists a linear inter-dependence between $\mathrm{p_{T}}$ integrated anisotropic flow and nuclear deformation. Mean transverse momentum signifies the fireball temperature in body-body and tip-tip collisions. There exists a negative linear correlation of $\mathrm{\langle p_{T} \rangle}$ with collision system-size and a positive correlation with nuclear deformation. Flow measurements in high-energy, heavy-ion collisions using isotopic collision systems, offer a new precision tool to study nuclear structure physics. Observation of nuclear structure properties like nuclear deformation in a heavy-ion collision such as this would be very interesting.

hep-ph↗

arXiv2023

Higher flow harmonics of strange hadrons in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and Pb+Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV with HYDJET++ model

Using the HYDJET++ model, we measure the higher-order flow harmonics $v_{n}$(n=2,3,4) of (multi-) strange hadrons in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and Pb+Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV. We have compared our model results and experimental data at RHIC and LHC energies. The model reproduces the higher flow harmonics of (multi-) strange hadrons as a function of $p_{T}$, centrality, and quark content. We have studied and discussed mass ordering of flows $v_{n}$(n=2,3,4) among $π^{+}+π^{-}$, $K^{-}+K^{+}$, $K_{s}^{0}$, $p+\overline{p}$, $Λ+\overlineΛ$, $Ξ^{-}+\overlineΞ^{+}$, $Ω^{-}+\overlineΩ^{+}$ at low $p_{T}$ and the baryon-meson grouping at intermediate $p_{T}$. NCQ scaling using the HYDJET++ model and its comparison with experimental results at RHIC and LHC energies have also been discussed. Study of flow harmonics behaviour in RHIC and LHC energy regimes will provide an additional insight into the dynamics of anisotropic flow and the effect of radial flow expansion in the system.

hep-ph↗

arXiv2023

Optical linear-nonlinear and dispersion parameters of thermally evaporated SnS thin films as absorber material for solar cells

In this manuscript, we report the results of optical properties of SnS thin films, deposited on FTO coated glass substrates at room temperature by thermal evaporation technique. In addition, the effect of film thickness on the optical behavior of FTO/SnS is analyzed and obtained results are compared with data of SnS films grown on glass and ITO substrates. Our study indicates that the properties of SnS film are independent of the substrate material. Further, the influence of the film thickness on the other optical parameters including, linear and third order nonlinear optical constants and dispersion parameters have also been investigated using the transmission, reflection, and absorption spectra. It is found that the optical band gap decreases from 2.07 to 1.30 eV with increase in SnS film thickness, whereas the refractive index increases with increasing thickness. Additionally, the oscillator energy, and the dispersion energy are estimated using WempleDiDomenico approach. The dispersion energies are in the range of 7.20 to 4.59 eV, while the oscillator energies of the thin films are in the range of 5.49 to 2.24 eV. Moreover, the nonlinear refractive index, and optical susceptibility are calculated by using the empirical relation of Tichy and Ticha. The volume of data suggests optical properties of SnS thin films are strongly dependent on film thickness.

cond-mat.mtrl-sci↗

arXiv2022

Transverse momentum spectra and suppression of charged hadrons in deformed Xe-Xe collisions at $\sqrt{s_{NN}}$ = 5.44 TeV using HYDJET++ model

In this study, we systematically investigate deformed Xe-Xe collisions at 5.44 TeV center of mass energy. We exploit the Monte Carlo HYDJET++ model to compute transverse momentum ($p_{T}$) distribution, nuclear modification factor $R_{AA}$ and relative suppression in terms of $R_{CP}$ as a function of transverse momentum and centrality of collision of charged hadrons in body-body and tip-tip geometrical configurations, respectively. We have compared HYDJET++ model results to those from ALICE experimental data and AMPT model (String-Melting version) results. Minimum bias Xe-Xe collisions show a suitable match with ALICE experimental data at midrapidity. Average transverse momentum ($\langle p_{T} \rangle$) show strong centrality dependence. The contribution of hard parton scatterings to the total charged hadron yield is discussed. Both nuclear modification factor $R_{AA}$ and relative suppression $R_{CP}$ show a clear dependence on centrality as well as transverse momentum. The charged hadron observables show a clear dependence on the geometrical configuration of the collisions. HYDJET++ model justifies experimental data more closely than the AMPT model.

hep-ph↗