Search

An overview of the significant contributions made by the Aligarh group in the field of neutrino physics has been provided. The group's work began with the study of quasielastic neutrino scattering on deuterium, specifically the process $\nu_\mu + d \rightarrow \mu^- + p +p$, focusing on moderate neutrino energies within the impulse approximation framework in order to analyze the early experiments at ANL and BNL with deuterium filled bubble chambers. These studies were later extended to numerically calculate (anti)neutrino interaction cross sections for the inclusive quasielastic scattering from nuclei using local density approximation~(LDA), incorporating nucleon-nucleon correlations for moderate to heavy nuclear targets. The inelastic scattering cross sections for one pion production and the deep inelastic scattering~(DIS) from nuclei have been obtained using LDA with multi nucleon correlation effects. In the case of single pion production, the final state interaction of the pions with the residual nucleus has also been taken into account. In addition, the group has explored other inelastic processes of kaon and eta meson production, in the (anti)neutrino interactions with the nucleon targets. Furthermore, we have investigated electron and positron scattering off proton targets in the intermediate energy range, focusing on polarization observables and T-noninvariance. Our research has also delved into polarized electron scattering to explore the possibility of observing parity-violating asymmetry (PVA) in elastic and deep inelastic scattering, among other related topics. The group has also contributed to the study of atmospheric neutrino flux in the cosmic ray interactions, relevant for various sites of the neutrino oscillation experiments with atmospheric neutrinos., Comment: 8 pages Submitted to Eur. Phys. J. ST special issue "Radio detection of ultra-high energy neutrino and cosmic ray"

In this work, we study the charged current induced neutrino and antineutrino scattering from the free nucleon target. This study has been performed in the energy range of a few GeV, relevant for the (anti)neutrino oscillation experiments with accelerator and atmospheric neutrinos. For a few GeV neutrino, the contribution to the cross section mainly comes from the quasielastic, the inelastic production of mesons like pion, kaon, eta, and hyperons as well as from the deep inelastic scattering by the weak currents in $\Delta S$=0 and $\Delta S$=1 sectors. The numerical results are presented for the $Q^2$ distribution of the differential cross section for all the aforementioned processes. The effect of the cut on the center of mass energy $W$ has been explicitly discussed., Comment: Submitted to Eur. Phys. J. ST special issue "Radio detection of ultra-high energy neutrino and cosmic ray"; 17 pages, 12 figures, 3 tables

EPR steering is a nonclassical correlation that exhibits properties intermediate to entanglement and Bell nonlocality, providing a valuable resource for quantum communication and computation. In this work, we propose a theoretical scheme to investigate stationary gaussian quantum steering, entanglement and Gaussian geometric discord of two spatially separated rotating mirrors (Rms) in a double-Laguerre-Gaussian cavity (DLGC). Each cavity is derived by Laguerre-Gaussian (LG) beam, and a Yttrium Iron Garnet sphere (YIG) is injected in the intersection of the two cavities. We employ Gaussian quantum steering to characterize the steerability between the Rms. The logarithmic negativity measure is used to quantify the amount of entanglement. We quantify all nonclassical correlations between the Rms by harnessing the Gaussian geometric discord (GGD) measure. Our results indicate that various physical parameters, including the temperature, detuning of the magnon mode frequency, orbital angular momentum (OAM) of the LG cavity modes, the coupling between magnon and cavity mode, the mass of the Rms, each play distinct roles in establishing ${\rm Rm_1-Rm_2}$ entanglement. We characterize the entanglement of the two Rms under ambient temperature (300 K). Stationary entanglement is optimal by adjusting the values of Rms frequency and photon-magnon coupling. We show that the stationary entanglement is fragile under thermal effects. Besides, the GGD demonstrates strong resilience to thermal noise, and this can be further enhanced by increasing the mass of the Rms. Under experimentally accessible parameters and with adjusted ratio between the angular frequencies, we achieve both one-way and two-way steering. Finally, we address the feasibility of our proposal based on the present experiments.

We have studied the deep inelastic scattering of polarized charged leptons from polarized nucleon targets and evaluated the polarized structure functions $g_{1,2}(x,Q^2)$ for protons and neutrons as well as the nucleon asymmetries $A_{1p}(x,Q^2)$ and $A_{2p}(x,Q^2)$ for protons. The higher order perturbative corrections up to the next-to-next-to-the-leading order (NNLO) using the parameterization of LSS05 polarized parton distribution functions in the 3-flavor MSbar scheme and the nonperturbative corrections viz. the twist-3 corrections and target mass corrections (TMC) have been included in the calculations. The numerical results for the polarized nucleon structure functions and the proton asymmetries are presented and compared with the experimental results. The sum rule integrals of the nucleon structure functions corresponding to the Ellis-Jaffe, Bjorken, Gottfried and Burkhardt-Cottingham sum rules have been evaluated numerically and are compared with the experimental results., Comment: 22 pages, 13 figures

The charged current weak production of $\Delta (1232)$ from the free proton target induced by the electron/positron in the intermediate energy range corresponding to the beam energy available at JLab and Mainz, has been studied. The results for the differential scattering cross section $\frac{d\sigma}{dQ^2}$, the angular distribution $\frac{d\sigma}{d\Omega_{\Delta}}$, and the total scattering cross section $\sigma(E_e)$ for both the electron and positron induced processes are presented, for the various energies in the range of 0.5--4~GeV. The cross section $\sigma(E_e)$ is found to be of the order of $10^{-39}$~cm$^{2}$ for the electron/positron energies in the few GeV range. The availability of electron/positron beams having well defined energy and direction with very high luminosity of the order of $10^{38}-10^{39}$~cm$^{-2}$~sec$^{-1}$, makes it possible to observe the weak charged current production of $\Delta(1232)$ and determine the axial vector form factors $C_{i}^{A} (Q^2);~(i=3-5)$. The sensitivity of the differential cross section $\frac{d\sigma}{dQ^2}$ to the subdominant form factors $C_{3}^{A}(Q^2)$ and $C_{4}^{A} (Q^2)$ is found to be strong enough, especially in the low $Q^2$ region, which can be used to determine them phenomenologically and to test the various theoretical models proposed to calculate them., Comment: 21 pages, 9 figures, and 1 table

We propose a scheme for the generation of nonreciprocal multipartite entanglement in a two-mode cavity magnomechanical system, consisting of two cross microwave (MW) cavities having an yttrium iron garnet (YIG) sphere, which is coupled through magnetic dipole interaction. Our results show that the magnon self-Kerr effect can significantly enhance bipartite entanglement, which turns out to be non-reciprocal when the magetic field is tuned along the crystallographic axis [110]. This is due to the frequency shift on the magnons (YIG sphere), which depends upon the direction of magnetic field. Interestingly, the degree of nonreciprocity of entanglement depends upon a careful optimal choice of system parameters like normalizd cavity detunings, bipartite nonlinear index $\Delta E_{K}$, self-Kerr coefficient and effective magnomechanical coupling rate $G$. In addition to bipartite entanglement, we also explored the nonreciprocity in tripartite entanglement. Our present theoretical proposal for nonreciprocity in multipartite entanglement may find applications in diverse engineering nonreciprocal devices., Comment: 11 pages, 7figures

Low-disorder two-dimensional electron systems in the presence of a strong, perpendicular magnetic field terminate at very small Landau level filling factors in a Wigner crystal (WC), where the electrons form an ordered array to minimize the Coulomb repulsion. The nature of this exotic, many-body, quantum phase is yet to be fully understood and experimentally revealed. Here we probe one of WC's most fundamental parameters, namely the energy gap that determines its low-temperature conductivity, in record-mobility, ultra-high-purity, two-dimensional electrons confined to GaAs quantum wells. The WC domains in these samples contain $\simeq$ 1000 electrons. The measured gaps are a factor of three larger than previously reported for lower quality samples, and agree remarkably well with values predicted for the lowest-energy, intrinsic, hyper-corelated bubble defects in a WC made of flux-electron composite fermions, rather than bare electrons. The agreement is particularly noteworthy, given that the calculations are done for disorder-free composite fermion WCs, and there are no adjustable parameters. The results reflect the exceptionally high quality of the samples, and suggest that composite fermion WCs are indeed more stable compared to their electron counterparts.

Owing to their large effective mass, strong and tunable spin-orbit coupling, and complex band-structure, two-dimensional hole systems (2DHSs) in GaAs quantum wells provide rich platforms to probe exotic many-body physics, while also offering potential applications in ballistic and spintronics devices, and fault-tolerant topological quantum computing. We present here a systematic study of molecular-beam-epitaxy grown, modulation-doped, GaAs (001) 2DHSs where we explore the limits of low-temperature 2DHS mobility by optimizing two parameters, the GaAs quantum well width and the alloy fraction ($x$) of the flanking Al$_x$Ga$_{1-x}$As barriers. We obtain a breakthrough in 2DHS mobility, with a peak value $\simeq 18 \times 10^6$ cm$^2$/Vs at a density of 3.8 $\times$ 10$^{10}$ /cm$^{2}$, implying a mean-free-path of $\simeq 57 \mu$m. Using transport calculations tailored to our structures, we analyze the operating scattering mechanisms to explain the non-monotonic evolution of mobility with density. We find it imperative to include the dependence of effective mass on 2DHS density, well width, and $x$. We observe concomitant improvement in quality as evinced by the appearance of delicate fractional quantum Hall states at very low density., Comment: 10 pages, 4 figures, Accepted in Physical Review Materials

Single-component fractional quantum Hall states (FQHSs) at even-denominator filling factors may host non-Abelian quasiparticles that are considered to be building blocks of topological quantum computers. Such states, however, are rarely observed in the lowest-energy Landau level, namely at filling factors $\nu<1$. Here we report evidence for an even-denominator FQHS at $\nu=1/4$ in ultra-high-quality two-dimensional hole systems confined to modulation-doped GaAs quantum wells. We observe a deep minimum in the longitudinal resistance at $\nu=1/4$, superimposed on a highly insulating background, suggesting a close competition between the $\nu=1/4$ FQHS and the magnetic-field-induced, pinned Wigner solid states. Our experimental observations are consistent with the very recent theoretical calculations which predict that substantial Landau level mixing, caused by the large hole effective mass, can induce composite fermion pairing and lead to a non-Abelian FQHS at $\nu=1/4$. Our results demonstrate that Landau level mixing can provide a very potent means for tuning the interaction between composite fermions and creating new non-Abelian FQHSs., Comment: 7+9 pages, 3+4 figures