arXiv subjects

Arvind Kumar

Publications and source records attributed to Arvind Kumar.

At least 19 recordsLinked to original sources

arXiv2026

First Plasma Commissioning and Operational Highlights from India's First Spherical Tokamak at IPR

A compact Spherical Tokamak(ST) is commissioned at Institute for Plasma Research (IPR) to explore low aspect ratio tokamak physics and technologies that complement to the existing high aspect ratio tokamaks namely ADITYA-U and SST-1 by enabling studies on non-inductive startup, current drive in over dense plasmas, and shaped plasma physics on a low cost platform. The device, India's first spherical tokamak has completed major mechanical, magnetic, and electrical integration, and the coil system has been successfully tested with series of integrated commissioning. First plasma experiments have been carried out with a modest Ohmic system assisted by a 2.45GHz microwave system, supported by a centralized control and data acquisition system. An initial diagnostic set comprising visible imaging, spectroscopy, magnetics, and radiation monitors required for machine operation has been installed. This paper presents the integrated commissioning experiences and first plasma experiments of the newly installed machine.

physics.plasm-ph↗

arXiv2026

Electronic cooling of a TiW alloy normal-metal island using Nb-based superconducting tunnel junctions

TiW thin films remain non-superconducting down to millikelvin temperatures and are compatible with large-scale CMOS manufacturing, making them attractive for cryogenic and quantum tunnel-junction devices, such as normal-metal-insulator-superconductor (NIS) thermal sensors and electron refrigerators. We demonstrate significant electronic cooling of a TiW-based normal-metal island and electron thermometry by using TiW-Al-AlOx-Nb NIS tunnel-junction stacks. The NIS thermometer enables local electron temperature measurements from 0.5 to 8.32 K. NIS cooling is observed between 0.6 and 3.5 K, with maximum absolute and relative temperature reductions of 217 mK and 27%, respectively. Calculations using tunnel-junction parameters obtained independently from current-voltage fits reproduce the measured optimum-voltage scale, which lies substantially below the ideal low-temperature prediction.

cond-mat.mes-hall↗

arXiv2026

In-medium properties of $D$ and $D^*$ mesons in magnetized isospin asymmetric nuclear matter

We investigate the impact of an external magnetic field on the in-medium properties of pseudoscalar ($D^0,D^+,D_s$) and vector ($D^{0*},D^{+*},D_{s}^{*}$) mesons in isospin asymmetric nuclear matter at finite temperature using a hybrid theoretical framework combining the chiral SU(3) quark mean-field (CQMF) model and the light-front quark model (LFQM). The medium-modified constituent quark masses, obtained from the CQMF model by including the magnetized Dirac sea contribution and anomalous magnetic moments of nucleons, are used as input to the LFQM calculations of meson masses, weak decay constants, and leading-twist distribution amplitudes. We further incorporate the Landau quantization of the charged mesons restricted to the lowest Landau level, while magnetic field induced pseudoscalar-vector mixing is taken into account for each $D$-$D^{*}$ doublet. We find that the external magnetic field enhances the effective masses and decay constants of both pseudoscalar and vector $D$ mesons by magnetic catalysis, while increasing baryon density generally induces an attractive mass shift and suppresses the decay constant and distribution amplitudes. The Landau level contribution further enhances the effective masses of the charged mesons, whereas the pseudoscalar-vector mixing produces a level repulsion, shifting the vector meson masses upward and the pseudoscalar meson masses downward. The interplay between magnetic field and density effects gives rise to a nontrivial medium behavior of heavy-light meson properties, with isospin asymmetry further inducing a small but systematic mass splitting across all the meson states considered. These results provide useful insights into heavy-flavor dynamics in strongly interacting matter and are relevant to ongoing and future studies at FAIR, NICA, and J-PARC.

hep-ph↗

arXiv2026

Asymptotic Resurgence of Facet ideals of Graphic Matroids

Our main results are an upper bound on the asymptotic resurgence of the facet ideal of a graphic matroid in terms of the number of vertices and a lower bound in terms of the circumference. These bounds coincide for Hamiltonian graphs, which form the majority of graphs on $n$ vertices as $n$ tends to infinity. For simple $2$-connected graphs on up to nine vertices, we compute in Sage that the asymptotic resurgence of the facet ideal of a non-Hamiltonian graphic matroid is given either by our upper or lower bound.

math.AC↗

arXiv2026

Asymptotic Resurgence of Facet and Stanley-Reisner ideals of Matroids

Matroid configurations -- introduced by Geramita, Harbourne, Migliore, and Nagel -- are projective varieties which generalize so-called \textit{star configurations} and whose defining ideals are obtained by appropriately specializing the Stanley-Reisner ideal of a matroid. Motivated by this connection, we study the asymptotic resurgence of the Stanley-Reisner ideals of matroids. A result of Villareal shows that it is equivalent to study the asymptotic resurgence of facet ideals. We prove a formula for the asymptotic resurgence of the facet ideal of a matroid in terms of the Waldschmidt constant of facet ideals of the contractions of the matroid. As a consequence, we show that asymptotic resurgence respects the weak order on matroids of the same rank. Therefore, the asymptotic resurgence of the facet ideal of a given matroid is bounded above by the asymptotic resurgence of the facet ideal of a so-called \textit{almost-uniform} matroid of the same rank, which we compute explicitly. Guardo, Harbourne, and Van Tuyl showed that the asymptotic resurgence of an ideal is bounded below by the ratio of the initial degree of the ideal by its Waldschmidt constant. We prove that this lower bound is an equality for facet ideals of many classes of matroids, including matroids of rank $k$ on a ground set of size $n\ge 2k$ whose dual is paving, perfect matroid designs, and sparse paving matroids arising from Steiner systems. For the latter two classes, we explicitly compute the asymptotic resurgence.

math.AC↗

arXiv2026

Matroid correspondence

Motivated by algebraic correspondences and linear operators associated with volume and Lorentzian polynomials, we introduce matroid correspondences and their polymatroid analogues. A matroid correspondence defines a functor between poset categories of matroids whose morphisms are matroid quotients, and various standard functors, including deletion, contraction, free extension, truncation, intersection, union, and pullback, arise in this way. We show that these correspondences preserve representability and algebraicity under natural hypotheses. In the polymatroid setting, we establish compatibility with multisymmetric lifts. Finally, we relate this construction to the supports of linear operators with Lorentzian symbols.

math.CO↗

arXiv2026

Towards compressed baryonic matter densities: D meson diffusion

We study the spatial diffusion coefficient and the momentum transport coefficients of D mesons through a dense nuclear medium in the relaxation time approximation of the kinetic theory. The in medium modifications of the D meson transport properties are computed in the chiral SU(3) hadronic model. Relaxation time is estimated using dilute and degenerate gas approximations for low and high baryonic densities, respectively. We have noticed that relaxation time and spatial diffusion of D meson decrease rapidly in the low density dilute gas domain and mildly in the high density degenerate gas domain. The detailed result of the present work on D meson diffusion is quite contemporary and important towards the compressed baryonic matter densities which can be assessed in future heavy ion collision experiments.

nucl-th↗

arXiv2026

A Multi Center Breast FNAC Whole-Slide Cytology Dataset for AI-Assisted Patch-Wise Classification Using C1 to C5 Reporting Categories

We present a multi center breast fine needle aspiration cytology (FNAC) dataset designed for patch wise classification using C1 to C5 reporting labels. The prospective dataset includes 321 patients and 470 whole-slide images (WSIs) collected from participating tertiary medical centers in India between May 2023 and March 2026. Slides were stained using Papanicolaou (190 WSIs) or MayGrunwald Giemsa (280 WSIs), scanned on a Hamamatsu NanoZoomer S360 at 40X magnification and 0.25 microns per pixel, and stored directly in NDPI format. Across the 470 WSIs, 446 WSIs contain annotated patch regions, yielding 7,398 PNG image patches with expert-verified C1 to C5 labels. The release includes NDPI WSIs, WSI-level GeoJSON annotation files, extracted patch images, deidentified metadata, a data dictionary, a validation summary, a manifest linking WSIs to Zenodo records, and code for dataset inspection and reuse. The complete dataset is approximately 950 GB and is available through Zenodo.

cs.CV↗

arXiv2026

Magnetic moments of decuplet baryons in isospin asymmetric magnetized strange matter

We investigate the in-medium masses and magnetic moments of decuplet baryons $(\Delta,\Sigma^*,\Xi^*,\Omega^-)$ in isospin asymmetric magnetized strange matter at finite temperature within a unified chiral effective framework. Medium modifications of baryons are implemented using the chiral SU(3) quark mean-field (CQMF) model, where constituent quarks interact via scalar ($\sigma$, $\zeta$, $\delta$) and vector ($\omega$, $\rho$, $\phi$) meson fields considering the Dirac sea effects. The external magnetic field is incorporated through Landau quantization of charged particles together with anomalous magnetic moments (AMM) of baryons. The resulting in-medium mass of constituent quarks and decuplet baryons obtained from the CQMF model are subsequently employed as input to the chiral constituent quark model ($\chi$CQM) to evaluate magnetic moments of baryons. Contributions from valence quarks, sea quark spin polarizations, and orbital angular momentum of the quark sea are taken into account. Our results provide a systematic understanding of how dense, hot, and magnetized environments influence the magnetic properties of decuplet baryons.

hep-ph↗

arXiv2026

Determining newforms via arithmetic relations among Fourier coefficients

We investigate the distribution of primes satisfying arithmetic inequalities involving the Fourier coefficients of two non-CM newforms at prime powers. More precisely, we establish asymptotic formulas for the number of primes for which the differences, products, and ratios of the Fourier coefficients satisfy prescribed inequalities, together with explicit estimates for the corresponding densities. The proofs combine an effective joint Sato--Tate theorem with a geometric analysis of the associated semi-algebraic regions. As applications, we obtain new multiplicity one criteria, improve a theorem of Matom\"aki on small differences between Fourier coefficients, establish density-one analogues in the spirit of the Atkin--Serre conjecture, and derive a new characterization of twist-equivalence through the distribution of ratios of Fourier coefficients.

math.NT↗

arXiv2026

Magnetic Moment of Octet Baryons in Isospin Asymmetric Magnetized Strange Matter

We investigate the magnetic moments of octet baryons in isospin asymmetric strange hadronic matter under strong external magnetic fields within a unified theoretical framework by combining the chiral SU(3) quark mean field (CQMF) model with the chiral constituent quark ($\chi$CQM) model. At finite temperature, the inclusion of Dirac sea (DS) effect leads to magnetic catalysis attributing to the enhancement of scalar condensates with increasing magnetic field strength. As a consequence, the effective masses of the octet baryons exhibit a monotonic increase as a function of magnetic field. The results highlight the crucial role of vacuum polarization effects in determining the electromagnetic properties of baryons in strongly magnetized matter having relevance in heavy-ion collision and compact stars.

hep-ph↗

arXiv2026

Fluctuations and correlations of conserved charges in the Polyakov chiral SU(3) quark mean field model

We compute generalized susceptibilities of conserved charges in the Polyakov chiral SU(3) quark mean field (PCQMF) model with the fermion vacuum term. At $\mu_B = 0$ MeV, the calculation covers the diagonal $\chi_n^{B,Q,S}$ through eighth order and all twelve independent fourth-order off-diagonal correlators. Extending to finite $\mu_B$ at $\mu_Q = \mu_S = 0$, we compute $\chi_n^B$ through eighth order, $\chi_n^{Q,S}$ through fourth order, the second-order off-diagonals, all twelve fourth-order off-diagonal correlators, and the odd-order baryon susceptibilities $\chi_1^B$, $\chi_3^B$, $\chi_5^B$. The calculation includes the vacuum term (vac=1) and is repeated for an independently refitted no-sea variant (vac=0). At $\mu_B = 0$ MeV, the chiral pseudocritical temperature is $T_{\mathrm{pc}} = 170.5$ MeV (vac=1) and $166.4$ MeV (vac=0), while the Polyakov-loop deconfinement temperature is $T_{\mathrm{dec}} = 144.4$ MeV (vac=1) and $146.6$ MeV (vac=0). In vac=1, the derivative $-d\Delta_{l,s}/dT$ of the subtracted chiral condensate develops an inflection near $T_{\mathrm{dec}}$. Higher derivative orders resolve the chiral-deconfinement splitting as twin maxima in $\chi_4^B$ and $\chi_6^Q$, twin minima in $\chi_8^B$ and $\chi_8^Q$, and multiple zero crossings in $\chi_6^B$. Among the fourth-order off-diagonal correlators, vac=1 amplitudes exceed vac=0 in the BQ channel across the chiral crossover. The BS, QS, and mixed BQS components peak near the strange-melting temperature, where vac=0 dominates. Along $T_{\mathrm{pc}}(\mu_B)$, the kurtosis ratio $R_{42}^B \equiv \chi_4^B/\chi_2^B$ of vac=1 crosses zero at $\mu_B/T_{\mathrm{pc}} \approx 2.15$, while vac=0 stays positive across the full range. The higher-order ratios $R_{51}^B \equiv \chi_5^B/\chi_1^B$ and $R_{62}^B \equiv \chi_6^B/\chi_2^B$ start negative in vac=1 and grow more negative as $\mu_B$ increases.

hep-ph↗

arXiv2026

Space-like Sachs electric and magnetic form factors of the baryons in the asymmetric nuclear medium

In the present work, we have studied the space-like baryon Sachs form factors in the isospin asymmetric nuclear medium using the vector meson dominance (VMD) model. The in-medium effects are incorporated through the medium-modified masses of vector mesons which are calculated using the QCD sum rule approach taking density dependent scalar quark and gluon condensates as inputs from chiral SU(3) quark mean field (CQMF) model. The effective magnetic moments of the baryons are also calculated in the CQMF model. In the framework of VMD model, the photon couples to the nucleons through intermediary vector mesons with the same quantum number as that of a photon. This coupling leads to the relation of isoscalar and isovector Dirac and Pauli form factors which are then used to calculate the Sachs electric and magnetic form factors, which provide physically measurable quantities that represent the electric and magnetic distributions of the baryons. The present work aims to study the effects of asymmetric nuclear matter at finite temperature on the Sachs form factors of baryons in the space-like region. The electric and magnetic charge radii have also been calculated for the baryons in free space and dense asymmetric nuclear matter. The results obtained have been compared with other available phenomenological models, lattice simulations, and experimental data.

hep-ph↗

arXiv2026

A study of $J/\psi$ mass shift and bound states: Impact of $D D$ and $DD^*$ meson loops

We investigate the modification of the $J/\psi$ meson mass in asymmetric nuclear matter at zero and finite temperatures employing an effective Lagrangian approach that considers the contributions of $DD$ and $DD^*$ meson loops. The medium dependence of $D$ meson masses is determined using the hadronic chiral SU(3) model, where scalar condensates are calculated and subsequently utilized in the QCD sum rules approach. Our findings indicate that an increase in baryonic density results in a negative mass shift of the $J/\psi$ meson. This suggests that the $J/\psi$ meson is attracted to nuclear mean fields indicating the possibility of the formation of meson-nucleus bound states. Moreover, we have also determined the binding energy and absorption decay width of the $J/\psi$ meson for both the ground and excited states of $\text{O}^{16}$, $\text{Ca}^{40}$, $\text{Zr}^{90}$, and $\text{Pb}^{208}$ nuclei. These results are expected to contribute to the understanding of experimental data from upcoming studies at Jefferson lab and the facility for antiproton and ion research, where low-momentum charmed mesons can be produced and examined within nuclei.

hep-ph↗

arXiv2026

Effective Joint Sato-Tate Distribution and Sign Change of Symmetric Power Coefficients

We prove an unconditional, effective joint Sato--Tate distribution for the Fourier coefficients of two twist-inequivalent, non-CM newforms $f$ and $f'$. Our result generalises a result of Thorner, which holds for rectangular regions, by extending it to any measurable region of $[-2,2]^2$ whose boundary consists of finitely many continuous curves of finite length. As a consequence, we develop a unified framework to study various arithmetic properties of Fourier coefficients of symmetric power $L$-functions attached to $f$ and $f'$. In particular, for these coefficients (and their polynomial expressions), we obtain effective distribution results, quantitative statements on simultaneous sign behaviour, and bounds for the first sign change.

math.NT↗

arXiv2026

Pion Parton Distribution Functions in the Light-Cone Quark Model and Experimental Constraints

In this work, we investigate the valence quark parton distribution functions (PDFs) of the pion within the light-cone quark model. The initial quark PDFs are calculated by solving the quark-quark correlation function for the pseudoscalar mesons. The initial quark PDFs have been evolved to higher energy scales through the Dokshitzer,Gribov,Lipatov,Altarelli,Parisi (DGLAP) evolution equations. We also find that our calculated evolved PDFs match experimental and available theoretical extraction data. For the first time, we have also predicted the $F_2$ structure function at next-to-leading (NLO) order accuracy. The calculated $F_2$ structure function has been compared with the available ZEUS and H1 experimental data at DESY-HERA over a wide range of energy scales. Additionally, we display the forward pion production cross-section for the Drell-Yan process caused by pions using the pion PDFs that were calculated and the target nucleon PDFs from the LHAPDF nucleus datasets. The evolved $F_2$ structure function of the pion have been studied at the upcoming electron-ion collider energy kinematics. Overall, it was observed that the quark PDFs of pions computed using the light-cone quark model consistent with the experimental results.

hep-ph↗

arXiv2026

Magnetic moments of decuplet baryons in asymmetric magnetized nuclear matter

Understanding the novel QCD phenomenon under high external magnetic fields of hot and dense medium help us to develop a better understanding of the underlying quark dynamics of baryons. Using a hybrid approach based on the effective field theory that treats quarks as the fundamental degrees of freedom and calculating the individual contribution of valence, sea and orbital angular moment of sea quark, the magnetic moment of a given baryon of the decuplet family is calculated. The incorporation of Landau quantization in the vector and scalar densities of baryons help us to obtain the impact of external magnetic field on the properties of baryons within the chiral SU(3) quark mean field model (CQMF). In the present study, effective masses of the baryons are calculated using CQMF while the framework of chiral constituent quark model ($\chi$CQM), extended to SU(4) sector, is used to obtain the effective magnetic moments of decuplet baryons under the influence of magnetic field.

hep-ph↗

arXiv2026

Spectroscopy of $\rho$-meson in symmetric nuclear medium

In this work, we investigate the behavior of the light vector $\rho$ meson in the presence of a symmetric nuclear medium at zero temperature. We calculate the mass and decay constant of the $\rho$-meson as well as the leading twist distribution amplitudes (DAs) in the light-front quark model in vacuum, which are further investigated at different baryonic densities. We also predict the Mellin moments of the DAs and decay width of the $\rho^0 \to e^+ e^-$ process in both vacuum and medium. The evolution of DAs is carried out by the leading order (LO) Efremov-Radyushkin-Brodsky-Lepage method and compared with available predictions. For better understanding of medium effects on $\rho$-meson, we have also predicted the in-medium charge ($G_C(Q^2)$), magnetic ($G_M(Q^2)$), and quadrupole ($G_Q(Q^2)$) form factors. The in-medium charge radii, magnetic moment, and quadrupole moment have also been predicted in this work. We have found that the nuclear medium induces appreciable modifications on the mass, weak decay constant, decay width, and distribution amplitudes of the $\rho$ meson. However, the charge radii, magnetic moment, and quadrupole moment are observed to exhibit weaker sensitivity to changes in baryonic density.

hep-ph↗