arXiv subjects

M. K. Pandey

Publications and source records attributed to M. K. Pandey.

6 recordsLinked to original sources

arXiv2026

Constraining Axion-Like-Particles with germanium detector at the Kuo-Sheng Reactor Neutrino Laboratory

We present results of a search for Axion-Like Particles (ALPs) produced $via$ Primakoff and Compton-like scattering channels, using data acquired with TEXONO experiment at the Kuo-Sheng Nuclear Power Station. The analysis is based on 278.91 days of reactor-ON and 43.60 days of reactor-OFF data. These datasets were collected using a 1.06 kg high-purity germanium detector located 28 m from a 2.9 GW reactor core. No significant excess is observed in the residual spectrum from the reactor-ON and reactor-OFF data subtraction. Using data acquired with low-background germanium detectors, upper limits on both the ALP-photon ($g_{a\gamma\gamma}$) and ALP-electron ($g_{aee}$) couplings are derived for ALP masses ranging from 1 eV to 3 MeV at 90\% confidence level. Since both $g_{a\gamma\gamma}$ and $g_{aee}$ couplings contribute to ALP production and detection, a combined analysis is performed by treating both channels as active parameters.

hep-ex↗

arXiv2026

Studies of Neutrino-Nucleus Elastic Scattering with Point-Contact Germanium Detectors at the Kuo-Sheng Reactor Neutrino Laboratory

The low energy and intense flux of electron anti-neutrinos from nuclear reactors provide the perfect stage to study elastic neutrino-nucleus scattering ($\nu A_{el}$) in the fully coherent regime. We report results from the TEXONO experiment using electro-cooled $p$-type point-contact Germanium detectors with masses of 523~g and 1434~g at the Kuo-Sheng Reactor Neutrino Laboratory. We report improved constraints on the $\nu A_{el}$ cross section with a combined exposure of 404(813.7)~kg-days of Reactor ON(OFF) data at an electron-equivalent threshold of 200~eV$_{ee}$. The Lindhard model, in which the quenching factor is parameterized by a single parameter k, is adopted to describe the suppression of ionization yield. At the benchmark value of k=0.162, a limit of $\rho<$2.0 at 90\% confidence level (CL) is derived, where $\rho$ represents the ratio of the observed to the predicted Standard Model cross section. Moreover the region k$>$0.205 is excluded at 90\% CL using the SM-predicted $\nu A_{el}$ rate. A bound on the neutrino magnetic moment from $\nu A_{el}$ at $\mu_{\nu} {<} 5.9 \times 10^{-10}~\mu_B$ at 90\% CL is also derived.

hep-ex↗

arXiv2026

HyPCA-Net: Advancing Multimodal Fusion in Medical Image Analysis

Multimodal fusion frameworks, which integrate diverse medical imaging modalities (e.g., MRI, CT), have shown great potential in applications such as skin cancer detection, dementia diagnosis, and brain tumor prediction. However, existing multimodal fusion methods face significant challenges. First, they often rely on computationally expensive models, limiting their applicability in low-resource environments. Second, they often employ cascaded attention modules, which potentially increase risk of information loss during inter-module transitions and hinder their capacity to effectively capture robust shared representations across modalities. This restricts their generalization in multi-disease analysis tasks. To address these limitations, we propose a Hybrid Parallel-Fusion Cascaded Attention Network (HyPCA-Net), composed of two core novel blocks: (a) a computationally efficient residual adaptive learning attention block for capturing refined modality-specific representations, and (b) a dual-view cascaded attention block aimed at learning robust shared representations across diverse modalities. Extensive experiments on ten publicly available datasets exhibit that HyPCA-Net significantly outperforms existing leading methods, with improvements of up to 5.2% in performance and reductions of up to 73.1% in computational cost. Code: https://github.com/misti1203/HyPCA-Net.

cs.CV↗

arXiv2025

Dark Matter Annual Modulation Analysis with Combined Nuclear and Electron Recoil Channels

After decades of experimental efforts, the DAMA/LIBRA(DL) annual modulation (AM) analysis on the $χN$ (WIMP Dark Matter interactions on nucleus) channel remains the only one which can be interpreted as positive signatures. This has been refuted by numerous time-integrated (TI) and AM analysis. It has been shown that $χe$ (WIMP interactions with electrons) alone is not compatible with the DL AM data. We expand the investigations by performing an AM analysis with the addition of $χe$ long-range and short-range interactions to $χN$, derived using the Frozen Core Approximation method. Two scenarios are considered, where the $χN$ and $χe$ processes are due to a single $χ$ ($Γ^{1 χ}_{tot}$) or two different $χ$'s ($Γ^{2 χ}_{tot}$). The combined fits with $χN$ and $χe$ provide stronger significance to the DL AM data which are compatible with the presence of additional physical effects beyond $χN$ alone. This is the first analysis which explores how $χe$ AM can play a role in DL AM. The revised allowed regions as well as the exclusion contours from the other null AM experiments are presented. All DL AM allowed parameter spaces in $χN$ and $χe$ channels under both $Γ^{1 χ}_{tot}$ and $Γ^{2 χ}_{tot}$ are excluded at the 90\% confidence level by the combined null AM results. It can be projected that DL-allowed parameter spaces from generic models with interactions induced by two-WIMPs are ruled out.

hep-ex↗

arXiv2023

Inverse Primakoff Scattering for Axionlike Particle Coupling

Axionlike particles (ALPs) can be produced in the Sun, and are considered viable candidates for the cosmological dark matter (DM). It can decay into two photons or interact with matter. We identify new inelastic channels of inverse Primakoff processes due to atomic excitation and ionization. Their cross sections are derived by incorporating full electromagnetic fields of atomic charge and current densities, and computed by well-benchmarked atomic many-body methods. Complementing data from the underground XENONnT and surface TEXONO experiments are analyzed. Event rates and sensitivity reaches are evaluated with respect to solar- and DM-ALPs. New parameter space in ALP couplings with the photons versus ALP masses in (1~eV$-$10~keV) not previously accessible to laboratory experiments are probed and excluded with solar-ALPs. However, at regions where DM-ALPs have already decayed, there would be no ALP-flux and hence no interactions at the detectors in direct search experiments. No physics constraints can be derived. Future projects would be able to evade the stability bound and open new observable windows in (100~eV$-$1~MeV) for DM-ALPs.

hep-ph↗

arXiv2019

Constraints on millicharged particles with low threshold germanium detectors at Kuo-Sheng Reactor Neutrino Laboratory

Relativistic millicharged particles ($χ_q$) have been proposed in various extensions to the Standard Model of particle physics. We consider the scenarios where they are produced at nuclear reactor core and via interactions of cosmic-rays with the earth's atmosphere. Millicharged particles could also be candidates for dark matter, and become relativistic through acceleration by supernova explosion shock waves. The atomic ionization cross section of $χ_q$ with matter are derived with the equivalent photon approximation. Smoking-gun signatures with significant enhancement in the differential cross section are identified. New limits on the mass and charge of $χ_q$ are derived, using data taken with a point-contact germanium detector with 500g mass functioning at an energy threshold of 300~eV at the Kuo-Sheng Reactor Neutrino Laboratory.

hep-ph↗