arXiv subjects

Amina Khatun

Publications and source records attributed to Amina Khatun.

10 recordsLinked to original sources

arXiv2026

Mixed Unit Interval Bigraphs : A Characterization

The class of intersection bigraphs of unit intervals of the real line whose ends may be open or closed is called a class of mixed unit interval bigraphs. This class of bigraphs is a strict superclass of the class of unit interval bigraphs. In a previous paper [6] we have provided four infinite families of forbidden induced subgraphs including two separate forbidden induced subgraphs of mixed unit interval bigraphs. In that paper, we also posed a conjecture concerning characterization of mixed unit interval bigraphs and verified parts of it. In the present paper we shall give a complete characterization of mixed unit interval bigraphs.

cs.DM↗

arXiv2021

A New Approach to Probe Non-Standard Interactions in Atmospheric Neutrino Experiments

We propose a new approach to explore the neutral-current non-standard neutrino interactions (NSI) in atmospheric neutrino experiments using oscillation dips and valleys in reconstructed muon observables, at a detector like ICAL that can identify the muon charge. We focus on the flavor-changing NSI parameter $\varepsilon_{μτ}$, which has the maximum impact on the muon survival probability in these experiments. We show that non-zero $\varepsilon_{μτ}$ shifts the oscillation dip locations in $L/E$ distributions of the up/down event ratios of reconstructed $μ^-$ and $μ^+$ in opposite directions. We introduce a new variable $Δd$ representing the difference of dip locations in $μ^-$ and $μ^+$, which is sensitive to the magnitude as well as the sign of $\varepsilon_{μτ}$, and is independent of the value of $Δm^2_{32}$. We further note that the oscillation valley in the ($E$, $\cos θ$) plane of the reconstructed muon observables bends in the presence of NSI, its curvature having opposite signs for $μ^-$ and $μ^+$. We demonstrate the identification of NSI with this curvature, which is feasible for detectors like ICAL having excellent muon energy and direction resolutions. We illustrate how the measurement of contrast in the curvatures of valleys in $μ^-$ and $μ^+$ can be used to estimate $\varepsilon_{μτ}$. Using these proposed oscillation dip and valley measurements, the achievable precision on $|\varepsilon_{μτ}|$ at 90% C.L. is about 2% with 500 kt$\cdot$yr exposure. The effects of statistical fluctuations, systematic errors, and uncertainties in oscillation parameters have been incorporated using multiple sets of simulated data. Our method would provide a direct and robust measurement of $\varepsilon_{μτ}$ in the multi-GeV energy range.

hep-ph↗

arXiv2021

Probing NSI in Atmospheric Neutrino Experiments using Oscillation Dip and Valley

We propose a new approach to probe neutral-current non-standard neutrino interaction parameter $\varepsilon_{μτ}$ using the oscillation dip and oscillation valley. Using the simulated ratio of upward-going and downward-going reconstructed muon events at the upcoming ICAL detector, we demonstrate that the presence of non-zero $\varepsilon_{μτ}$ would result in the shift in the dip location as well as the bending of the oscillation valley. Thanks to the charge identification capability of ICAL, the opposite shifts in the locations of oscillation dips as well as the contrast in the curvatures of oscillation valleys for $μ^-$ and $μ^+$ is used to constrain $|\varepsilon_{μτ}|$ at 90% C.L. to about 2% using 500 kt$\cdot$yr exposure. Our procedure incorporates statistical fluctuations, uncertainties in oscillation parameters, and systematic errors.

hep-ph↗

arXiv2021

From oscillation dip to oscillation valley in atmospheric neutrino experiments

Atmospheric neutrino experiments can show the "oscillation dip" feature in data, due to their sensitivity over a large $L/E$ range. In experiments that can distinguish between neutrinos and antineutrinos, like INO, oscillation dips can be observed in both these channels separately. We present the dip-identification algorithm employing a data-driven approach -- one that uses the asymmetry in the upward-going and downward-going events, binned in the reconstructed $L/E$ of muons -- to demonstrate the dip, which would confirm the oscillation hypothesis. We further propose, for the first time, the identification of an "oscillation valley" in the reconstructed ($E_μ$,$\,\cosθ_μ$) plane, feasible for detectors like ICAL having excellent muon energy and direction resolutions. We illustrate how this two-dimensional valley would offer a clear visual representation and test of the $L/E$ dependence, the alignment of the valley quantifying the atmospheric mass-squared difference. Owing to the charge identification capability of the ICAL detector at INO, we always present our results using $μ^{-}$ and $μ^{+}$ events separately. Taking into account the statistical fluctuations and systematic errors, and varying oscillation parameters over their currently allowed ranges, we estimate the precision to which atmospheric neutrino oscillation parameters would be determined with the 10-year simulated data at ICAL using our procedure.

hep-ph↗

arXiv2019

Boundaries and unphysical fixed points in Dynamical Quantum Phase Transitions

We show that dynamic quantum phase transitions (DQPT) in many situations involve renormalization group (RG) fixed points that are unphysical in the context of thermal phase transitions. In such cases, boundary conditions are shown to become relevant to the extent of even completely suppressing the bulk transitions. We establish these by performing exact RG analysis of the quantum Ising model on scale-invariant lattices of different dimensions, and by analyzing the zeros of the Loschmidt amplitude. Further corroboration of boundaries affecting the bulk transition comes from the three-state quantum Potts chain, for which we also show that the DQPT corresponds to a pair of period-2 fixed points.

cond-mat.stat-mech↗

arXiv2019

Enhancing Sensitivity to Non-Standard Neutrino Interactions at INO combining muon and hadron information

The neutral current non-standard interactions (NSI's) of neutrino with matter fermions while propagating through long distances inside the Earth matter can give rise to the extra matter potentials apart from the standard MSW potential due to the $W$-mediated interactions in matter. In this paper, we explore the impact of flavor violating neutral current NSI parameter $\varepsilon_{μτ}$ in the oscillation of atmospheric neutrino and antineutrino using the 50 kt magnetized ICAL detector at INO. We find that due to non-zero $\varepsilon_{μτ}$, $ν_μ\rightarrowν_μ$ and $\barν_μ\rightarrow\barν_μ$ transition probabilities get modified substantially at higher energies and longer baselines, where vacuum oscillation dominates. We estimate the sensitivity of the ICAL detector for various choices of binning schemes and observables. The most optimistic bound on $\varepsilon_{μτ}$ that we obtain is $-0.01 < \varepsilon_{μτ} < 0.01 $ at 90$\%$ C.L. using 500 kt$\cdot$yr exposure and considering $E_μ,\, \cosθ_μ,\,E'_{\rm had}$ as observables in their ranges [1, 21] GeV, [-1, 1], and [0, 25] GeV respectively. For the first time we show that the charge identification capability of the ICAL detector is crucial to set stringent constraints on $\varepsilon_{μτ}$. We also show that when we marginalize over $\varepsilon_{μτ}$ in fit in its range of -0.1 to 0.1, the mass hierarchy sensitivity deteriorates by 10$\%$ to 20$\%$ depending on the analysis mode, and the precision measurements of atmospheric parameters remain quite robust at the ICAL detector.

hep-ph↗

arXiv2018

Looking for Galactic Diffuse Dark Matter in INO-MagICAL Detector

The Weakly Interacting Massive Particle (WIMP) is a popular particle physics candidate for the dark matter (DM). It can annihilate and/or decay to neutrino and antineutrino pair. The proposed 50 kt Magnetized Iron CALorimeter (MagICAL) detector at the India-based Neutrino Observatory (INO) can observe these pairs over the conventional atmospheric neutrino and antineutrino fluxes. If we do not see any excess of events in ten years, then INO-Magical can place competitive limits on self-annihilation cross-section ($\langleσv\rangle$) and decay lifetime ($τ$) of dark matter at 90\% C.L.: $\langleσv\rangle\leq 1.87\,\times\,10^{-24}$ cm$^3$ s$^{-1}$ and $τ\geq 4.8\,\times\,10^{24}$ s for $m_χ$ = 10 GeV assuming the NFW as DM density profile.

hep-ph↗

arXiv2018

Can INO be Sensitive to Flavor-Dependent Long-Range Forces?

Flavor-dependent long-range leptonic forces mediated by the ultra-light and neutral bosons associated with gauged $L_e-L_μ$ or $L_e-L_τ$ symmetry constitute a minimal extension of the Standard Model. In presence of these new anomaly free abelian symmetries, the SM remains invariant and renormalizable, and can lead to interesting phenomenological consequences. For an example, the electrons inside the Sun can generate a flavor-dependent long-range potential at the Earth surface, which can enhance $ν_μ$ and $\barν_μ$ survival probabilities over a wide range of energies and baselines in atmospheric neutrino experiments. In this paper, we explore in detail the possible impacts of these long-range flavor-diagonal neutral current interactions due to $L_e-L_μ$ and $L_e-L_τ$ symmetries (one at-a-time) in the context of proposed 50 kt magnetized ICAL detector at INO. Combining the information on muon momentum and hadron energy on an event-by-event basis, ICAL can place stringent constraints on the effective gauge coupling $α_{eμ/eτ}<1.2\times 10^{-53}$ ($1.75\times 10^{-53}$) at 90$\%$ (3$σ$) C.L. with 500 kt$\cdot$yr exposure. The 90$\%$ C.L. limit on $α_{eμ}$ ($α_{eτ}$) from ICAL is $\sim 46$ (53) times better than the existing bound from the Super-Kamiokande experiment.

hep-ph↗

arXiv2017

Indirect searches of Galactic diffuse dark matter in INO-MagICAL detector

The signatures for the existence of dark matter are revealed only through its gravitational interaction. Theoretical arguments support that the Weakly Interacting Massive Particle (WIMP) can be a class of dark matter and it can annihilate and/or decay to Standard Model particles, among which neutrino is a favorable candidate. We show that the proposed 50 kt Magnetized Iron CALorimeter (MagICAL) detector under the India-based Neutrino Observatory (INO) project can play an important role in the indirect searches of Galactic diffuse dark matter in the neutrino and antineutrino mode separately. We present the sensitivity of 500 kt$\cdot$yr MagICAL detector to set limits on the velocity-averaged self-annihilation cross-section ($\langleσv\rangle$) and decay lifetime ($τ$) of dark matter having mass in the range of 2 GeV $\leq m_χ\leq $ 90 GeV and 4 GeV $\leq m_χ\leq $ 180 GeV respectively, assuming no excess over the conventional atmospheric neutrino and antineutrino fluxes at the INO site. Our limits for low mass dark matter constrain the parameter space which has not been explored before. We show that MagICAL will be able to set competitive constraints, $\langleσv\rangle\leq 1.87\,\times\,10^{-24}$ cm$^3$ s$^{-1}$ for $χχ\rightarrowν\barν$ and $τ\geq 4.8\,\times\,10^{24}$ s for $χ\rightarrowν\barν$ at 90$\%$ C.L. (1 d.o.f.) for $m_χ$ = 10 GeV assuming the NFW as dark matter density profile.

hep-ph↗

arXiv2017

Physics Potential of the ICAL detector at the India-based Neutrino Observatory (INO)

The upcoming 50 kt magnetized iron calorimeter (ICAL) detector at the India-based Neutrino Observatory (INO) is designed to study the atmospheric neutrinos and antineutrinos separately over a wide range of energies and path lengths. The primary focus of this experiment is to explore the Earth matter effects by observing the energy and zenith angle dependence of the atmospheric neutrinos in the multi-GeV range. This study will be crucial to address some of the outstanding issues in neutrino oscillation physics, including the fundamental issue of neutrino mass hierarchy. In this document, we present the physics potential of the detector as obtained from realistic detector simulations. We describe the simulation framework, the neutrino interactions in the detector, and the expected response of the detector to particles traversing it. The ICAL detector can determine the energy and direction of the muons to a high precision, and in addition, its sensitivity to multi-GeV hadrons increases its physics reach substantially. Its charge identification capability, and hence its ability to distinguish neutrinos from antineutrinos, makes it an efficient detector for determining the neutrino mass hierarchy. In this report, we outline the analyses carried out for the determination of neutrino mass hierarchy and precision measurements of atmospheric neutrino mixing parameters at ICAL, and give the expected physics reach of the detector with 10 years of runtime. We also explore the potential of ICAL for probing new physics scenarios like CPT violation and the presence of magnetic monopoles.

physics.ins-det↗