arXiv subjects

Arpita Mondal

Publications and source records attributed to Arpita Mondal.

14 recordsLinked to original sources

arXiv2026

Imprints of nuclear shell structure in exclusive vector meson production

We report for the first time that, within the saturation framework, exclusive vector meson production at small $x$ is sensitive to the shell structure of the target nucleus. Self-consistent nuclear densities from occupied single-particle orbitals in the quark-meson coupling (QMC) model modify the coherent $|t|$-differential cross section, enhancing secondary diffractive lobes in light nuclei and displacing the higher-order minima in intermediate-mass nuclei, whereas for heavy targets the shifts are weaker. Because the small $J/ψ$ dipole is insensitive to saturation, these features make coherent $J/ψ$ production a clean probe of nuclear shell structure, most favorably for intermediate-mass nuclei such as calcium isotopes. For the larger $ϕ$ dipole, shell structure must be included in the nuclear initial state before saturation effects can be isolated in differential observables at the Electron Ion Collider. Our results establish exclusive vector meson production as a probe of the mean-field nuclear structure at small $x$ and provide a baseline for isolating residual many-body correlations.

hep-ph↗

arXiv2026

Complementary probes of Bilinear RPV SUSY models with a wino-like LSP via Neutrino Oscillation and LHC

In this work, we explore the bilinear R-parity violating Supersymmetry model's parameter space by performing a Markov Chain Monte Carlo scan with neutrino oscillation data, Higgs mass and its coupling strengths, and flavor observables such as $B$-hadron decay branching ratios. From the allowed parameter space, we analyze the decay patterns of wino-like lighter charginos and lightest neutralinos and demonstrate how the branching ratios to different neutrino and charged lepton flavors depend on the neutrino mass hierarchy. Furthermore, we investigate the impact of current LHC bounds and projected future sensitivities from trilepton resonance searches on the allowed parameter space. We show that considering the branching ratio $\mathrm{Br}(\widetildeχ_1^{\pm} \to Zl^\pm; l= e,μ,τ) \sim$23\%, obtained at the best-fit point, the wino-like mass degenerate $\widetildeχ_1^{\pm}/\widetildeχ_1^0$ are excluded upto 565 GeV from LHC Run-II data. The projected exclusion reach with a similar branching ratio at High-Luminosity LHC (HL-LHC) is around 950 GeV. For a simplified scenario where $\widetildeχ_1^{\pm} / \widetildeχ_1^0$ decays via a $Z$ boson with branching ratios of 1\%, 50\%, and 100\%, wino masses can be excluded up to approximately $600~\mathrm{GeV}$, $1185~\mathrm{GeV}$, and $1350~\mathrm{GeV}$ respectively. Our analysis shows that the HL-LHC can probe a significant portion of the 1$σ$ allowed parameter space by neutrino oscillation measurements and other experimental constraints.

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arXiv2025

Exploring the BSM parameter space with Neural Network aided Simulation-Based Inference

Some of the issues that make sampling parameter spaces of various beyond the Standard Model (BSM) scenarios computationally expensive are the high dimensionality of the input parameter space, complex likelihoods, and stringent experimental constraints. In this work, we explore likelihood-free approaches, leveraging neural network-aided Simulation-Based Inference (SBI) to alleviate this issue. We focus on three amortized SBI methods: Neural Posterior Estimation (NPE), Neural Likelihood Estimation (NLE), and Neural Ratio Estimation (NRE) and perform a comparative analysis through the validation test known as the \textit{ Test of Accuracy with Random Points} (TARP), as well as through posterior sample efficiency and computational time. As an example, we focus on the scalar sector of the phenomenological minimal supersymmetric SM (pMSSM) and observe that the NPE method outperforms the others and generates correct posterior distributions of the parameters with a minimal number of samples. The efficacy of this framework is tested on 5 parameter pMSSM with Higgs and flavor physics data and its performance is compared with the MCMC method. We further add dark matter (DM) observables to make the task more challenging and consider a 9 parameter pMSSM. We observe that even though the efficiency factor drops, the amortized SBI method still produces faithful posterior distributions. SBI predicted points satisfying DM constraints are mostly bino-dominated upto $\sim$ 1.5 TeV, and are mostly wino-dominated within the 1.5 - 2 TeV range.

hep-ph↗

arXiv2025

Markov Chain Monte Carlo analysis to probe trilinear $R$-parity violating SUSY scenarios and possible LHC signatures

In this article, we probe the trilinear $R$-parity violating (RPV) supersymmetric (SUSY) scenarios with specific nonzero interactions in the light of neutrino oscillation, Higgs, and flavor observables. We attempt to fit the set of observables using a state-of-the-art Markov Chain Monte Carlo (MCMC) setup and study its impact on the model parameter space. Our main objective is to constrain the trilinear couplings individually, along with some other SUSY parameters relevant to the observables. We present the constrained parameter regions in the form of marginalized posterior distributions on different two-dimensional parameter planes. We perform our analyses with two different scenarios characterized by our choices for the lightest SUSY particle (LSP), bino, and stop. Our results indicate that the lepton number violating trilinear couplings $λ_{i33}$ ($i$=1,2) and $λ_{j33}^{\prime}$ ($j$=1,2,3) can be at most of the order of $10^{-4}$ or even smaller while $\tanβ$ is restricted to below 15 even when $3σ$ allowed regions are considered. We further comment on the possible LHC signatures of these LSPs focusing on and around the best-fit regions.

hep-ph↗

arXiv2025

Status of R-parity violating SUSY

In this article, we discuss various phenomenological implications of possible R-parity violating (RPV) supersymmetric scenarios. In this context, the implications of both bilinear and trilinear RPV terms are reviewed from the viewpoint of neutrino physics, anomalous muon magnetic moment, different flavor observables, and collider physics. Apart from discussing the distinctive phenomenological implications of the RPV scenarios, we also survey the updated results from different studies to highlight the present status of the RPV couplings.

hep-ph↗

arXiv2025

Searches for the BSM scenarios at the LHC using decision tree based machine learning algorithms: A comparative study and review of Random Forest, Adaboost, XGboost and LightGBM frameworks

Machine learning algorithms are now being extensively used in our daily lives, spanning across diverse industries as well as academia. In the field of high energy physics (HEP), the most common and challenging task is separating a rare signal from a much larger background. The boosted decision tree (BDT) algorithm has been a cornerstone of the high energy physics for analyzing event triggering, particle identification, jet tagging, object reconstruction, event classification, and other related tasks for quite some time. This article presents a comprehensive overview of research conducted by both HEP experimental and phenomenological groups that utilize decision tree algorithms in the context of the Standard Model and Supersymmetry (SUSY). We also summarize the basic concept of machine learning and decision tree algorithm along with the working principle of \texttt{Random Forest}, \texttt{AdaBoost} and two gradient boosting frameworks, such as \texttt{XGBoost}, and \texttt{LightGBM}. Using a case study of electroweakino productions at the high luminosity LHC, we demonstrate how these algorithms lead to improvement in the search sensitivity compared to traditional cut-based methods in both compressed and non-compressed R-parity conserving SUSY scenarios. The effect of different hyperparameters and their optimization, feature importance study using SHapley values are also discussed in detail.

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arXiv2025

Meson-nucleus bound states in quark meson coupling model

The formations of the $K(\bar{K})$, $D(\bar{D})$, and $B(\bar{B})$ meson-nucleus bound states in ${\rm{^{16}O}}$, ${\rm{^{40}Ca}}$, ${\rm{^{90}Zr}}$, ${\rm{^{197}Au}}$, and ${\rm{^{208}Pb}}$ nucleus are investigated using the quark meson coupling model. The model relies on a mean field description of non-overlapping nucleon bags bound by the self-consistent interactions of scalar ($σ$, $δ$) and vector ($ω$, $ρ$) mesons with the (anti)quarks inside the bags, which is further extended to explore the properties of nuclei. We estimate the meson-nucleus bound state energies by solving the Klein-Gordon equations with the real potentials calculated self-consistently within the model, using a coordinate space approach. The calculations are carried out for different nuclear interactions. The effects of Coulomb interaction are considered in the present study for the charged mesons. Our study indicates the formation of rather deeply bound $B$-mesic states at the very central region of the nuclei, compared to the $D$ and $K$ mesons, offering a more promising probe to explore subtle nuclear medium effects. The investigations of such bound states are of particular interest for the upcoming $\rm{\bar{P}ANDA}$ at FAIR, J-PARC-E29, and JLab experiments.

nucl-th↗

arXiv2025

$ϕ$ meson in nuclear matter and atomic nuclei

The properties (masses and decay widths) of the $ϕ$ meson are investigated in nuclear matter from the $ϕ$ meson self-energy, using the tree-level $ϕK\bar{K}$ Lagrangian, and, incorporating in-medium masses of (anti)kaons calculated within the quark meson coupling (QMC) model. These mass shifts and decay widths are incorporated in the Breit-Wigner spectral function of the $ϕ$ meson to calculate the production cross-section of $ϕ$ in asymmetric nuclear matter. Considerable modifications to the production cross-section are observed at normal nuclear matter density, driven by the in-medium mass reduction and the increase in the decay width of $ϕ$ meson. The potential experienced by $ϕ$ meson in nuclear matter is used to study the possibility of formation of the $ϕ$ mesic bound state with atomic nuclei. We explore the potential formation of $ϕ$-mesic bound states in ${\rm{^{4}He}}$, ${\rm{^{12}C}}$, ${\rm{^{16}O}}$, ${\rm{^{40}Ca}}$, ${\rm{^{90}Zr}}$, ${\rm{^{197}Au}}$ and ${\rm{^{208}Pb}}$ nuclei by investigating their binding energies and absorption widths based on the corresponding $ϕ$-nucleus potentials. Our study shows shallow bound states with the light nuclei and deeply bound states in heavy nuclei. Among the investigated nuclei, a particularly distinct signal for a $ϕ$-mesic bound state is identified in ${\rm{^{16}O}}$, suggesting its potential experimental observability. The work provides valuable insights into $ϕ$ meson interactions in infinite nuclear matter and the potential formation of exotic $ϕ$-mesic nuclear states, offering promising probes for strongly interacting matter in the upcoming experiments at J-PARC, JLab, and ${\rm{\bar{P}}ANDA}$@FAIR physics program.

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arXiv2024

Heavy Quarkonium-nuclear bound states within a generalized linear sigma model

We estimate the binding energies of charmonium ($J/ψ$, $ψ(2S)$, $ψ(1D)$, $χ_{c0}$, $χ_{c1}$, $χ_{c2}$) and bottomonium ($Υ(1S)$, $Υ(2S)$, $Υ_2(1D)$, $χ_{b0}$, $χ_{b1}$, $χ_{b2}$) states bound in various nuclei (${\rm{^{4}He}}$, ${\rm{^{12}C}}$, ${\rm{^{16}O}}$, ${\rm{^{40}Ca}}$, ${\rm{^{90}Zr}}$, and ${\rm{^{208}Pb}}$) using the quarkonia-nuclei potentials obtained from their mass shifts in nuclear matter within the generalized linear sigma model. In the absence of light partons in heavy quarkonia, at the tree level, the medium modifications are driven by the gluon condensate, which is simulated within this model through a scalar dilaton field, $χ$, by introducing broken scale invariance of QCD. Our study shows that charmonium states bind more deeply with the atomic nuclei as compared to bottomonium states, providing a better probe for nuclear medium effects. Such bound states' investigations are particularly interesting for the upcoming J-PARC-E29, $\rm{\bar{P}ANDA}$@FAIR, and CEBAF@JLab experiments. The mass shifts of the heavy quarkonium states in hot isospin asymmetric nuclear matter are investigated and are observed to receive an appreciable medium modification. These medium effects are anticipated at FAIR@GSI, where such neutron-rich hot nuclear matter is expected to be produced.

nucl-th↗

arXiv2024

Bilinear R-parity violating supersymmetry under the light of neutrino oscillation, higgs and flavor data

In this work, we explore a well motivated beyond the Standard Model scenario, namely, R-parity violating Supersymmetry, in the context of light neutrino masses and mixing. We assume that the R-parity is only broken by the lepton number violating bilinear term. We try to fit two non-zero neutrino mass square differences and three mixing angle values obtained from the global $χ^2$ analysis of neutrino oscillation data. We have also taken into account the updated data of the standard model (SM) Higgs mass and its coupling strengths with other SM particles from LHC Run-II along with low energy flavor violating constraints like rare b-hadron decays. We have used a Markov Chain Monte Carlo (MCMC) analysis to constrain the new physics parameter space. While doing so, we ensure that all the existing collider constraints are duly taken into account. Through our analysis, we have derived the most stringent constraints possible to date with existing data on the 9 bilinear R-parity violating parameters along with $μ$ and $\tanβ$. We further explore the possibility of explaining the anomalous muon~(g~-~2) measurement staying within the parameter space allowed by neutrino, Higgs and flavor data while satisfying the collider constraints as well. We find that there still remains a small sub-TeV parameter space where the required excess can be obtained.

hep-ph↗

arXiv2024

Open Strange and Open Heavy Flavour mesons in Asymmetric Nuclear Matter within Quark Meson Coupling model

The in-medium properties of open strange ($K$, $\bar{K}$), open charm ($D$, $\bar{D}$), and open bottom ($B$, $\bar{B}$) mesons are investigated in asymmetric nuclear matter using Quark Meson Coupling (QMC) model. A direct coupling of scalar ($σ$, $δ$) and vector ($ω$, $ρ$) mesons to the light quarks and anti-quarks of these mesons give rise to the in-medium modification of the properties of the corresponding meson within the model. The inclusion of the $δ$ (scalar iso-vector) meson breaks the isospin symmetry for the masses of the light quark and antiquark doublets, causing mass splitting between ($u,\;d$) as well as ($\bar{d},\;\bar{u}$). Consequently, the considered mesons exhibit mass splittings within the isodoublets of $K$, $\bar{K}$, $D$, $\bar{D}$, $B$ and $\bar{B}$ mesons when embedded in asymmetric nuclear matter. In the current study, the interactions of the pseudoscalar meson with the scalar, as well as vector mesons, are considered, which lead to significant medium modifications of the excitation energies of the open strange (charm and bottom) mesons. In asymmetric nuclear matter, due to the interaction of the pseudoscalar meson with the vector iso-vector $ρ$ meson, there is a splitting in the excitation energies of the mesons within the isospin doublets. The isospin effects are seen to be large for high baryon densities. This study can have significant observable consequences, such as in the production ratios, e.g., $K^+/K^0$, $K^-/\bar {K^0}$, $D^+/D^0$, $D^-/\bar{D}^0$, $B^+/B^0$ and $B^-/\bar{B}^0$ in the upcoming heavy ion collision experiments at FAIR project at GSI, where the experiments are planned to be performed using neutron-rich beams to study the compressed baryonic matter.

nucl-th↗

arXiv2023

Slepton searches in the trilinear RPV SUSY scenarios at the HL-LHC and HE-LHC

In this work we have studied a multi-lepton final state arising from sneutrino and left-handed slepton production at the high luminosity and high energy LHC in the context of R-parity violating supersymmetry when only the lepton number violating $λ_{121}$ and/or $λ_{122}$ couplings are non-zero. We have taken into account both pair production and associated production of the three generations of left-handed sleptons and sneutrinos, which are assumed to be mass degenerate. The lightest supersymmetric particle is assumed to be bino and it decays via the R-parity violating couplings into light leptons and neutrinos. Our final state has a large lepton multiplicity, $N_{l}\geq 4~(l=e,~μ)$. We perform both cut-based and machine learning based analyses for comparison. We present our results in the bino-slepton/sneutrino mass plane in terms of exclusion and discovery reach at the LHC. Following our analysis, the slepton mass can be discovered upto $\sim$ 1.54 TeV and excluded upto $\sim$ 1.87 TeV at the high luminosity LHC while these ranges go upto $\sim$ 2.46 TeV and $\sim$ 3.06 TeV respectively at the high energy LHC.

hep-ph↗

arXiv2023

Improving sensitivity of trilinear RPV SUSY searches using machine learning at the LHC

In this work, we have explored the sensitivity of multilepton final states in probing the gaugino sector of R-parity violating supersymmetric scenario with specific lepton number violating trilinear couplings ($λ_{ijk}$) being non-zero. The gaugino spectrum is such that the charged leptons in the final state can arise from the R-parity violating decays of the lightest supersymmetric particle (LSP) as well as R-parity conserving decays of the next-to-LSP (NLSP). Apart from a detailed cut-based analysis, we have also performed a machine learning-based analysis using boosted decision tree algorithm which provides much better sensitivity. In the scenarios with non-zero $λ_{121}$ and/or $λ_{122}$ couplings, the LSP pair in the final states decays to $4l~(l = e, μ) + \rm E{\!\!\!/}_T$ final states with $100\%$ branching ratio. We have shown that under this circumstance, a final state with $\ge 4l$ has the highest sensitivity in probing the gaugino masses. We also discuss how the sensitivity can change in the presence of $τ$ lepton(s) in the final state due to other choices of trilinear couplings. We present our results through the estimation of the discovery and exclusion contours in the gaugino mass plane for both the HL-LHC and the HE-LHC. For $λ_{121}$ and/or $λ_{122}$ nonzero scenario, the projected 2$σ$ exclusion limit on NLSP masses reaches upto 2.37 TeV and 4 TeV for the HL-LHC and the HE-LHC respectively by using a machine learning based algorithm. We obtain an enhancement of $\sim$ 380 (190) GeV in the projected 2$σ$ exclusion limit on the NLSP masses at the 27 (14) TeV LHC. Considering the same final state ($N_l \geq 4$) for $λ_{133}$ and/or $λ_{233}$ non-zero scenario, we find that the corresponding 2$σ$ projected limits are $\sim$ 1.97 TeV and $\sim$ 3.25 TeV for the HL-LHC and HE-LHC respectively.

hep-ph↗

arXiv2022

Medium modifications of Heavy Quarkonia masses in a generalized Linear Sigma Model

We study the mass shifts of the charmonium ($\bar{c}c$) states ($J/ψ$, $ψ(2S)$, $ψ(1D)$, $χ_{c0}$, $χ_{c1}$ and $χ_{c2}$) as well as the bottomonium ($\bar{b}b$) states ($Υ(1S)$, $Υ(2S)$, $Υ_2(1D)$, $χ_{b0}$, $χ_{b1}$ and $χ_{b2}$) in isospin asymmetric nuclear matter. These are investigated using a generalized linear sigma model. The broken scale invariance of QCD is incorporated in the chiral $SU(2)\times SU(2)$ Lagrangian through an effective potential involving logarithmic terms of a scalar (glueball) dilaton field $χ$. The mass shifts of the quarkonium states are obtained through the medium modifications of the dilaton field which simulates the scalar gluon condensate of QCD. We observe an appreciable mass drop in the states of heavy quarkonia under this study. The in-medium masses at finite densities thus obtained should modify the in-medium partial decay widths of heavy quarkonia to open heavy flavor mesons. These density effects can be probed in in the high energy nuclear collisions at the future facility at GSI (at Germany) and JINR (at Russia) in the experiments producing highly dense baryonic matter.

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