arXiv subjects

Arindam Chatterjee

Publications and source records attributed to Arindam Chatterjee.

At least 19 recordsLinked to original sources

arXiv2026

Radiative Corrections to the Direct Detection of Inelastic Scattering of Higgsino-like Neutralino Dark Matter

The direct detection (DD) of Higgsino-like dark matter (DM) through inelastic scattering processes may provide a promising avenue, along with the elastic scattering, when the mass splitting between the neutral Higgsino pairs is extremely tiny. The mass splitting can be reduced further by adopting the on-shell renormalization for the neutral and charged Higgsinos in the MSSM. Moreover, all the one-loop electroweak (EW) corrections to the three-point vertices for the neutralino(s)-Higgs interactions have been considered, while both elastic and inelastic DM-nucleon scattering cross-sections have been calculated primarily through Higgs exchange. Subsequently, the expected number of scattering events in the latest LUX-ZEPLIN (LZ) DD experiment are also computed. Our results highlight a few scenarios in which the inelastic component may exceed the corresponding elastic component, leading to enhanced direct detection scattering rates.

hep-ph↗

arXiv2026

Unveiling the Vanishing Higgsino-Nucleon Scattering in the MSSM at Next-to-Leading Order

Higgsino dark matter (DM) is considered one of the most well-motivated and minimal DM scenarios arising from supersymmetric extensions of the Standard Model. Motivated by the requirement of electroweak naturalness, Higgsinos are expected to be relatively light, with masses close to the weak scale. While a pure Higgsino state typically evades current direct detection limits, next-to-leading (NLO) order radiative corrections may bring it within the sensitivity of upcoming experiments. On the contrary, a more important consequence, observed specifically near the kinematic threshold for the production of two particles, is that the NLO corrections lower the DM-nucleon cross section below the neutrino floor. We explicitly examine the cancellation mechanism responsible for suppressed Higgsino-nucleon scattering and identify regions of MSSM parameter space where spin-independent cross-sections may vanish.

hep-ph↗

arXiv2026

Early- and Late-Time Modifications to $\Lambda$CDM: Implications for the Hubble Tension

We investigate an extension of $\Lambda$CDM in which a fraction of cold Dark Matter (DM) decays into invisible dark radiation (DR) around the radiation-matter equality epoch, together with a non-standard dark energy (DE) equation of state characterized by $w_0$. The decaying DM component modifies the early expansion history and reduces the sound horizon at baryon drag, while the DE alters the expansion rate at the late times. A comprehensive analysis combining \texttt{Planck 2018+ACT DR6+DESI DR2+CMB lensing} datasets has been carried out to explore the viability of this framework in addressing the $H_0$ tension. This model yields a Hubble constant of $H_0 = 69.83 \pm 0.98~\mathrm{km\,s^{-1}\,Mpc^{-1}}$, reducing the discrepancy with SH0ES measurement to ${\sim}2.2\sigma$ and local distance network measurement (H0DN) to ${\sim}2.9\sigma$. Further, considering \texttt{SH0ES} and \texttt{Pantheon+}, the inferred value of the Hubble constant becomes $H_0 = 70.20 \pm 0.66~\mathrm{km\,s^{-1}\,Mpc^{-1}}$. The Bayesian evidence suggests that this framework offers a fit to the relevant cosmological datasets at a statistically similar level as $\Lambda$CDM. It is observed that correlated early- and late-time modifications to the cosmological expansion history provide a more effective route to reducing the $H_0$ tension than either class of modification alone.

astro-ph.CO↗

arXiv2026

Dimming of Photon Ring due to Photon-Axion Conversion around Kerr Black Holes

We investigate photon-axion conversion in the vicinity of rotating Kerr black holes where strong gravity traps photons on near-circular trajectories, effectively enhancing the path length. We explore the observable signatures of such a conversion near the photon region. The process, driven by ambient magnetic fields, is significantly more efficient around supermassive black holes such as M87*, since the luminosity of photons increases with the mass of the BH. By numerically evaluating photon path lengths (on which the conversion depends), we analyze how key parameters-photon frequency, axion mass, photon-axion coupling, magnetic field strength, plasma density, and black hole spin-affect the conversion probability and the resultant dimming of photon spectral luminosity. We find that the conversion is most efficient at high frequencies (X-rays and gamma rays), while the frequency window associated with efficient conversion widens with an increase in the photon-axion coupling and a decrease in the electron density and the axion mass. The magnitude of dimming of the photon spectral luminosity depends primarily on the magnetic field, the photon-axion coupling and the BH spin. Our study reveals that rotating black holes generally exhibit enhanced dimming compared to static ones. Thus, if future telescopes achieving a resolution $\sim 10^{-5}$ arcsec in the X-ray/gamma-ray band detect a dimming of the photon spectral luminosity, then they can provide interesting constraints on the axion mass and its coupling with photons.

gr-qc↗

arXiv2026

Aspects of a Five-Dimensional $U(1)_{L_\mu - L_\tau}$ Model at Future Muon-Based Colliders

We study a five-dimensional (5D) framework based on the $U(1)_{L_\mu-L_\tau}$ gauge symmetry, where the associated gauge field $V$ propagates in the bulk, giving rise to an infinite tower of Kaluza--Klein (KK) excitations $V^{(n)}$ that couple selectively to the second- and third-generation leptons. Originally motivated by its potential to address the muon $g-2$ anomaly, this framework remains of interest as a minimal, anomaly-free, phenomenologically well-motivated extension of the Standard Model (SM) of particle physics. We focus on high-energy muon-based colliders, which could directly probe the gauge structure without relying on the kinetic mixing between the SM hypercharge gauge boson and the 5D gauge boson $V$. We explore a set of complementary processes: the elastic $\mu^+\mu^+ \to \mu^+\mu^+$ scattering via off-shell exchange of KK (gauge) excitations $V^{(n)}$; the bremsstrahlung production of $V^{(n)}$ followed by their decays into neutrinos and into $\mu^-\mu^+$ at a future $\mu$TRISTAN collider. Further, we study the $\mu^-\mu^+ \to \mu^-\mu^+$ scattering via resonant KK excitation(s) at a future muon collider. Our results show that these future muon-based colliders could offer sensitive and complementary probes into regions in the parameter space of the scenario that are beyond the reach of low-energy experiments. In particular, such experiments would be able to probe both heavier such KK gauge bosons with TeV-scale masses for relatively large gauge couplings, as well as the much lighter ones with masses in the MeV-scale for couplings as weak as $g_D \sim \mathcal{O}(10^{-5})$, thereby offering a promising $2\sigma$ exclusion reach for such KK excitations, over an extensive range of masses, at these facilities.

hep-ph↗

arXiv2025

Muon Beam Dump Experiments probe five-dimensional nature of $U(1)_{L_{\mu}-L_{\tau}}$

We have investigated the prospects of probing the five-dimensional $U(1)_{L_\mu - L_\tau}$ interactions in present and future muon dump experiments, namely, NA64$_\mu$, M$^3$, MuSIC, and a future muon beam dump experiment. These experiments are classified into two categories: the first two can probe processes where feebly interacting massive particles go into invisible channels, while the latter two can probe processes where these states decay into muon pairs. These two types of experiments are complementary in that they allow exploration of different parameter regions of a model. In our scenario, the presence of multiple massive gauge bosons as Kaluza-Klein (KK) particles leads to an enhancement in the signal events compared to the corresponding four-dimensional scenario. In particular, the decay process into muon pairs enables mass reconstruction of the parent particle, making it possible to directly demonstrate the existence of multiple KK particles in at least some parameter regions. This can provide clear evidence that the origin of the $U(1)_{L_\mu - L_\tau}$ interaction lies in five dimensions. Furthermore, the muon $(g-2)$ value, which is now consistent with the SM, can be used to exclude specific parameter regions for new particles interacting with muons. We also carefully discuss the non-trivial effects arising from nonzero kinetic mixing.

hep-ph↗

arXiv2025

Probing Dark Matter-Electron Interactions in the Cosmic Microwave Background Radiation

In this article, we consider Dark Matter (DM) interactions and study the same in the light of the Cosmic Microwave Background Radiation (CMBR) data. In particular, we focus on the DM-electron interactions. Assuming that such interactions are mediated by rather heavy mediators, we consider effective operators describing the relevant interaction terms in the lagrangian. The presence of such interaction terms leads to both DM annihilation and DM-electron scattering (drag). We focus on operators which lead to velocity-independent DM annihilation and DM-electron scattering cross-sections. Using the CMBR data, we study the implications of both of these effects, imposing constraints on the respective effective operators. This analysis underscores the importance of taking both scattering and annihilation processes into consideration in the study of DM interactions. We observe that the constraints on the DM annihilation and scattering cross-sections can change, up to about 13\% and 12\%, respectively, for the benchmark scenarios we considered, depending on the mass of DM, as compared to the scenario where only DM annihilation is accounted for.

hep-ph↗

arXiv2024

Radiative corrections to the direct detection of the Higgsino-(and Wino-)like neutralino dark matter: Spin-dependent interactions

The lightest neutralino ($\tilde{\chi}_1^0$) is a promising dark matter (DM) candidate in the R-parity conserving minimal supersymmetric standard model (MSSM). In this work, we focus on dominantly Higgsino-like and Wino-like $\tilde{\chi}_1^0$ DM, with small admixtures of gauginos and Higgsinos, respectively. In particular, we explore large one-loop corrections to the $\tilde{\chi}_1^0 \tilde{\chi}_1^0Z$ vertex, which can significantly affect the estimation of the spin-dependent $\tilde{\chi}_1^0$-nucleon scattering cross-section in the regions where such DM candidates are viable. We have used the on-shell renormalization scheme to estimate the relevant counterterm contributions. In the parameter region where $\tilde{\chi}_1^0$ is dominantly Higgsino-like, the radiative corrections (including the contributions from the respective counterterms) are substantial and can enhance the $\tilde{\chi}_1^0\tilde{\chi}_1^0Z$ vertex by up to $\sim 120\%$ for the benchmark scenarios we have considered. Further, for an almost pure Wino-like $\tilde{\chi}_1^0$, the increment in the $\tilde{\chi}_1^0\tilde{\chi}_1^0Z$ vertex is up to $15\%$. The corresponding cross-sections with the proton and the neutron can be changed by up to about $50\%$. In addition, including the electroweak box diagrams, the cross-sections can be significantly enhanced, in particular, for the Wino-like $\tilde{\chi}_1^0$.

hep-ph↗

arXiv2024

Electroweak renormalization of neutralino-Higgs interactions at one-loop and its impacts on spin-independent direct detection of Wino-like dark matter

A Wino-like neutralino dark matter (DM) in the form of the lightest supersymmetric particle (LSP) has been considered one of the popular paradigms that can naturally accommodate {\it new physics} at a relatively higher scale, typically beyond the reach of the LHC. The constraint on the DM relic density typically implies a lightest neutralino mass $\simeq 2$ TeV. Its observational signature through nuclear recoil experiments, specifically involving DM-nucleon spin-independent (SI) scattering, is not impressive, following its high masses and tiny Higgsino fractions. The theoretical calculations can be improved when we compute all the one-loop electroweak (EW) corrections to the three-point vertices for the neutralino (Wino)-Higgs interactions, which in turn boosts the DM-nucleon scattering cross-sections through the SM-like Higgs exchange. Importantly, we include the counterterm contributions. In addition, we incorporate the other next-to-leading order (NLO) EW DM-quark and DM-gluon interactions present in the literature to calculate the DM-nucleon cross-sections. With the improved and precise theoretical estimates, DM-nucleon scattering cross-sections may increase or decrease significantly by more than $100\%$ compared to leading order (LO) cross-sections in different parts of the parameter space.

hep-ph↗

arXiv2024

Prospects of five-dimensional $L_\mu-L_\tau$ gauge interactions in the light of elastic neutrino-electron scatterings: The scope of the DUNE near detector

We discuss the future prospects of a minimally five-dimensional version of the well-motivated scenario for addressing the discrepancy in the muon anomalous magnetic moment, the $U(1)_{L_\mu - L_\tau}$ extension of the standard model (SM) gauge symmetry. Here, multiple associated massive gauge bosons appear thanks to the five-dimensional $U(1)_{L_\mu - L_\tau}$ gauge symmetry, and they contribute to the muon $(g-2)$ and also other processes. We focus on the powerful probe of elastic neutrino-electron scatterings since the upcoming DUNE experiment will explore MeV-scale uncharted regions by previous experiments (e.g., CHARM-II and Borexino) in the near future. We found that even with small kinetic mixing parameters, much of the parameter space, including those satisfying muon $(g-2)$, can be probed using several years of data from the DUNE experiment, focusing on the near detector. In our scenario, interference effects between intermediate-state gauge bosons play an important role. Our results include comparisons between flat and warped extra dimensions.

hep-ph↗

arXiv2024

Statistical inference for subgraph counts and clustering coefficient using network sampling in a sparse Stochastic Block Model framework

This article develops limit laws for network sampling based estimates of subgraph counts and clustering coefficient of a large population network, and uses them for predictive inference. A model based approach is used, where the population network is assumed to be generated from a sparse Stochastic Block Model (SBM). To quantify the effects of node sampling under resource constraints, a sparse Bernoulli node sampling scheme is introduced, where the node selection probability decays to zero as the population size increases. Both induced and ego-centric network formation approaches are explored. Quantitative bounds on the speed of normal approximation for estimated subgraph counts are obtained in a joint model and design based asymptotic framework. These bounds show that inference accuracy depends on model sparsity, sampling sparsity, and features like edge density and minimum vertex cover size of the target subgraph. We find that the ego-centric approach can handle higher sparsity levels in both the model and sampling scheme, compared to the induced approach. We also show that if model sparsity remains below a threshold, inference quality is unaffected; beyond it, the quality degrades rapidly. The sufficient conditions for obtaining a Gaussian limit law also turn out to be necessary. For strictly balanced target subgraphs, we obtain sharp transitions from Gaussian to Poisson based limit laws, as sparsity levels increase. A complete description of limit laws for estimated subgraph counts is given for the induced case, with a near-complete one for the ego-centric case. These results also yield Gaussian and Poisson limit laws for the estimated clustering coefficient. Simulations support the theory across sparsity levels, and the proposed methodology is applied to a real data set.

math.ST↗

arXiv2023

Confronting electroweak MSSM through one-loop renormalized neutralino-Higgs interactions for dark matter direct detection and muon $(g-2)$

We compute the next-to-leading order (NLO) corrections to the vertices where a pair of the lightest neutralino couples to CP-even (light or heavy) Higgs scalars. In particular, the lightest neutralino is assumed to be a dominantly Bino-like mixed state, composed of Bino and Higgsino or Bino, Wino, and Higgsino. After computing all the three-point functions in the electroweak MSSM, we detail the contributions from the counterterms that arise in renormalizing these vertices in one-loop order. The amendment of the renormalized vertices impacts the spin-independent direct detection cross-sections of the scattering of nucleons with dark matter. We perform a comprehensive numerical scan over the parameter space where all the points satisfy the present B-physics constraints and accommodate the muon's anomalous magnetic moment. Finally, we exemplify a few benchmark points, which indulge the present searches of supersymmetric particles. After including the renormalized one-loop vertices, the spin-independent DM-nucleon cross-sections may be enhanced up to $20\%$ compared to its tree-level results. Finally, with the NLO cross-section, we use the recent LUX-ZEPLIN (LZ) results on the neutralino-nucleon scattering to display the relative rise in the lowest allowed band of the Higgsino mass parameter in the $M_1-\mu$ plane of the electroweak MSSM.

hep-ph↗

arXiv2023

Radiative Corrections to Aid the Direct Detection of the Higgsino-like Neutralino Dark Matter: Spin-Independent Interactions

The lightest neutralino ($\tilde{\chi}_1^0$) is a good Dark Matter (DM) candidate in the R-parity conserving Minimal Supersymmetric Standard Model (MSSM). In this work, we consider the light higgsino-like neutralino as the Lightest Stable Particle (LSP), thanks to rather small higgsino mass parameter $\mu$. We then estimate the prominent radiative corrections to the neutralino-neutralino-Higgs boson vertices. We show that for higgsino-like $\tilde{\chi}_1^0$, these corrections can significantly influence the spin-independent direct detection cross-section, even contributing close to 100\% in certain regions of the parameter space. These corrections, therefore, play an important role in deducing constraints on the mass of the higgsino-like lightest neutralino DM, and thus the $\mu$ parameter.

hep-ph↗

arXiv2023

Electroweak Phase Transition in the $Z_3$-invariant NMSSM: Implications of LHC and Dark matter searches and prospects of detecting the gravitational waves

We study in detail the viability and the patterns of a strong first-order electroweak phase transition as a prerequisite to electroweak baryogenesis in the framework of $Z_3$-invariant Next-to-Minimal Supersymmetric Standard Model (NMSSM), in the light of recent experimental results from the Higgs sector, dark matter (DM) searches and those from the searches of the lighter chargino and neutralinos at the Large Hadron Collider (LHC). For the latter, we undertake thorough recasts of the relevant, recent LHC analyses. With the help of a few benchmark scenarios, we demonstrate that while the LHC has started to eliminate regions of the parameter space with relatively small $μ_\mathrm{eff}$, that favors the coveted strong first-order phase transition, rather steadily, there remains phenomenologically much involved and compatible regions of the same which are yet not sensitive to the current LHC analyses. It is further noted that such a region could also be compatible with all pertinent theoretical and experimental constraints. We then proceed to analyze the prospects of detecting the stochastic gravitational waves, which are expected to arise from such a phase transition, at various future/proposed experiments, within the mentioned theoretical framework and find them to be somewhat ambitious under the currently projected sensitivities of those experiments.

hep-ph↗

arXiv2022

Prospects of a Strong first-order Electroweak Phase Transition in the $Z_3$-NMSSM

We have studied the viability and possible patterns of a strong first-order electroweak phase transition (SFOEWPT) within the $Z_3$-symmetric Next-to-Minimal Supersymmetric Standard Model (NMSSM), in view of the latest experimental results from the dark matter (DM) sector, Higgs sector and the searches of the lighter chargino and neutralinos at the Large Hadron Collider (LHC). We show that the region of parameter space with relatively small $μ_\mathrm{eff}$ that favors an SFOEWPT has started to get excluded from the searches at the LHC and various DM experiments. However, there still remain phenomenologically much involved and compatible regions for an SFOEWPT that are yet not sensitive to the latest LHC and DM searches. We further estimate the production of stochastic gravitational waves (GW) from an SFOEWPT within and without the bag model and the prospects of detecting such signals at various future/proposed GW experiments.

hep-ph↗

arXiv2021

Shedding Light on Dark Matter and Neutrino Interactions from Cosmology

In $\rmΛ$CDM cosmology, Dark Matter (DM) and neutrinos are assumed to be non-interacting. However, it is possible to have scenarios, where DM-neutrino interaction may be present, leading to scattering of DM with neutrinos and annihilation of DM into neutrinos. We investigate the viability of such scenarios in the light of cosmological data by making use of the Planck 2018 dataset (high-l TT+TE+EE, low-l TT, low-l EE) and constrain these processes in the light of the same. We also discuss a viable particle DM model where DM-neutrino interaction is present, and map the constraints obtained to the parameter space of the model.

hep-ph↗

arXiv2020

Inference problems in binary regression model with misclassified responses

Misclassification of binary responses, if ignored, may severely bias the maximum likelihood estimators (MLE) of regression parameters. For such data, a binary regression model incorporating misclassification probabilities is extensively used by researchers in different application contexts. The model, however, suffers from a serious estimation problem because of confounding of the unknown misclassification probabilities with the regression parameters. To overcome this problem, in addition to the main sample, use of internal validation data is proposed. However, the maximum likelihood estimators (MLE) are found to be substantially biased. Investigating further, we propose a maximum pseudo-likelihood method of estimation which leads to bias reduction. For drawing inference on the regression parameters, we develop a rigorous asymptotic theory for the maximum pseudo-likelihood estimators under standard assumptions. To facilitate its easy implementation, a bootstrapped version of the estimator is proposed, and its distributional consistency is proved. Extensions of these results are also provided for more general misclassification models. The results of the simulation studies are encouraging. The methodology is illustrated with a survey data.

math.ST↗

arXiv2019

Inflation, (P)reheating and Neutrino Anomalies: Production of Sterile Neutrinos with Secret Interactions

A number of experimental anomalies involving neutrinos hint towards the existence of at least an extra (a very light) sterile neutrino. However, such a species, appreciably mixing with the active neutrinos, is disfavored by different cosmological observations like Big Bang Nucleosynthesis (BBN), Cosmic Microwave Background (CMB) and Large Scale Structure (LSS). Recently, it was shown that the presence of additional interactions in the sterile neutrino sector via light bosonic mediators can make the scenario cosmologically viable by suppressing the production of the sterile neutrinos from active neutrinos via matter-like effect caused by the mediator. This mechanism works assuming the initial population of this sterile sector to be negligible with respect to that of the Standard Model (SM) particles, before the production from active neutrinos. However, there is fair chance that such bosonic mediators may couple to the inflaton and can be copiously produced during (p)reheating epoch. Consequently, they may ruin this assumption of initial small density of the sterile sector. In this article we, starting from inflation, investigate the production of such a sterile sector during (p)reheating in a large field inflationary scenario and identify the parameter region that allows for a viable early Universe cosmology.

astro-ph.CO↗