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Randhir Singh

Publications and source records attributed to Randhir Singh.

17 recordsLinked to original sources
arXiv2026

A method for energy and radius reconstruction with simulated charge information in a ton-scale liquid scintillator detector like Taishan Antineutrino Observatory

Small neutrino detectors are a ton level detectors which can be placed very close to the core of Nuclear Power Plant. In some detectors liquid scintilling (LS) material is used as the detecting material. The antineutrinos from the reactor core fall on the liquid scintillator of the detector where they deposit energy via Inverse Beta Decay process (IBD). The energy absorbed by liquid scintillator is re-emitted in the form of scintillation. These photons then travel through the scintillating material and hit the Silicon Photo Multipliers (SiPMs) which are installed on the inner surface of detector's spherical copper shell. These SiPMs absorb the photons to give a charge output signal. The energy and radius reconstruction is done using the information of charge collected by the SiPMs. Due to factors like large photo-coverage with large photon detection efficiency, small spherical detector size and low temperature operation, small size LS detectors can achieve an unprecedented energy resolution. In this paper, we have used a template-dependent method exploiting simulated data to reconstruct the event radius and energy. This method uses response functions generated using radioactive source calibration data and the charge information to reconstruct the energy and the radius of the event by constructing maximizing a likelihood function. This methodology is applicable to all similar size spherical neutrino detector experiments.

physics.ins-det↗
arXiv2026

Elastic neutrino-electron scattering perspectives at nuclear reactors

The determination of the weak mixing angle, $\sin^2θ_W$, at low momentum transfers remains a powerful test of the Standard Model and its potential new physics extensions. In this paper, we explore some physics opportunities at present and future reactor neutrino experiments through elastic neutrino-electron scattering (E$ν$ES). We assess the expected sensitivity to the weak mixing angle considering the CLOUD, TAO, and DANSS experimental configurations. We find that both CLOUD and TAO may achieve a precision that surpasses the current global fit from reactor experiments, while DANSS alone is expected to surpass the benchmark precision set by TEXONO measurement of the weak mixing angle. Additionally, we derive projected upper limits for the non-standard neutrino interactions (NSI), effective neutrino magnetic moment ($μ_ν$) and translate these into constraints on the neutrino transition magnetic moments ($Λ_i$). Our results demonstrate the physics potential of the E$ν$ES channel at current and upcoming reactor-based neutrino experiments.

hep-ph↗
arXiv2026

Taming the Black Swan: A Momentum-Gated Hierarchical Optimisation Framework for Asymmetric Alpha Generation

Conventional momentum strategies, despite their proven efficacy in generating alpha, frequently suffer from the "Winner's Curse", a structural vulnerability in which high performing assets exhibit clustered volatility and severe drawdowns during market reversals. To counteract this propensity for momentum crashes, this study presents the Adaptive Equity Generation and Immunisation System (AEGIS), a novel framework that fundamentally reengineers the trade-off between growth and stability. By leveraging a volatility-adjusted momentum filter to identify trend strength and employing a minimax correlation algorithm to enforce structural diversification, the model utilises sequential least squares programming (SLSQP) to optimise capital allocation for the sortino ratio. This architecture allows the portfolio to dynamically adapt to distinct market regimes: explicitly lowering the intensity of crashes during bear markets by decoupling correlated risks, while retaining asymmetric upside participation during bull runs. Empirical validation via a comprehensive 20-year walk-forward backtest (2006-2025), which covers significant stress events like the 2008 Global Financial Crisis, confirms that the framework produces substantial excess alpha relative to the standard S&P 500 benchmark. Notably, the strategy successfully matched the capital appreciation of the high-beta NASDAQ-100 index while achieving significantly reduced downside volatility and improved structural resilience. These results suggest that synthetic beta can be effectively engineered through mathematical regularisation, enabling investors to capture the high-growth characteristics of concentrated portfolios while preserving the defensive stability typically associated with broad-market diversification.

cs.CE↗
arXiv2024

On the Clean Graph of a Ring

Let $R$ be a ring (not necessarily a commutative ring) with identity. The clean graph $Cl(R)$ of a ring $R$ is a graph with vertices in the form of an ordered pair $(e,u)$, where $e$ is an idempotent and $u$ is a unit of ring $R$, respectively. Two distinct vertices $(e,u)$ and $(f,v)$ are adjacent in $Cl(R)$ if and only if $ef=fe=0$ or $uv=vu=1$. In this study, we considered the induced subgraph $Cl_2(R)$ of $Cl(R)$. We determined the Wiener index of $Cl_2(R)$, and we showed $Cl_2(R)$ has a perfect matching. In addition, we determined the matching number of $Cl_2(R)$ if $|U(R)|$ is not even.

math.CO↗
arXiv2023

On the Clean Graph of a Ring

Let R be a ring (not necessarily commutative ring) with identity. The clean graph Cl(R) of a ring R is a graph with vertices in the form of ordered pair (e; u), where e is an idempotent of the ring R and u is a unit of the ring R. Two distinct vertices (e; u) and (f; v) are adjacent if and only if ef = fe = 0 or uv = vu = 1. In this paper, we determine the Wiener index, Matching number of the clean graph of the ring Zn.

math.CO↗
arXiv2022

Centrality and Transverse Spherocity dependent study of charged-particle production in Xe-Xe collisions at $\sqrt{s_{NN}}$ = 5.44 TeV using PYTHIA8 Angantyr and AMPT models

Transverse Spherocity is an event structure variable which provide an effective way to disentangle the data into hard and soft components of the processes corresponding to events with small and large numbers of multi-parton interactions (MPI), respectively. Recent experimental results in small systems from the LHC suggest the importacnce of transverse spherocity variable in the classification of the events. In this contribution, we have studied the dynamics of identified particle production in Xe-Xe collisions at $\sqrt{s_{NN}}$ = 5.44 TeV using A Multi-Phase Transport Model (AMPT) and the recently developed Angantyr model, which is incorporated within PYTHIA8. A study of the transverse momentum spectra of the dentified particles are presented for soft (isotropic) and hard (jetty-like) events in different centrality intervals.

hep-ph↗
arXiv2021

Open Charm production in proton-proton collisions at $\sqrt{s}$ = 13.6 TeV with Pythia event generator

Charm and beauty are heavy quarks with observed masses of 1.28 GeV/$\textit{c}^2$ and 4.18 GeV/$\textit{c}^2$ respectively. They are produced in initial hard scattering processes. Due to their small formation time ($\Delta t \sim0.1 fm/\textit{c}$) as compared to the formation time of QGP ($\Delta t \sim0.3 fm/\textit{c}$) at the LHC, they experience all the stages occuring during the time evolution of the hot and dense medium produced in heavy-ion collisions. Therefore, the measurement of open charm and beauty production allows probing QGP properties and investigating the color charge and mass dependence of the parton in-medium energy loss. Moreover, due to their large masses ($m_c , m_b \gg \Lambda_{QCD}$ ) their pp production cross-sections are calculable within the domain of perturbative QCD constituting an excellent test of pQCD calculations. The aim of this study is to understand the processes involved in the production of charm quarks through the productions of D$^+$, D$^0$, D$^+_s$ and $\Lambda_c^+$ hadrons. Further to investigate the possibility of hadronization of the charm quarks, ratios like $\Lambda_c^+$/$D^+$, $D_s^+$/$D^+$, $\Lambda_c^+$/$D^0$ and $D_s^+$/$D^0$ are also measured. For the current analysis, the events are generated by using PYTHIA 8 for pp collisions at $\sqrt{s}$ = 13 TeV. PYTHIA 8 has proved to be quite successful in explaining the heavy-flavor particle production at the LHC energies.

hep-ex↗
arXiv2020

Analytic solution of system of singular nonlinear differential equations with Neumann-Robin boundary conditions arising in astrophysics

In this paper, we propose a new approach for the approximate analytic solution of system of Lane-Emden-Fowler type equations with Neumann-Robin boundary conditions. The algorithm is based on Green's function and the homotopy analysis method. This approach depends on constructing Green's function before establishing the recursive scheme for the approximate analytic solution of the equivalent system of integral equations. Unlike Adomian decomposition method (ADM) \cite{singh2020solving}, the present method contains adjustable parameters to control the convergence of the approximate series solution. Convergence and error estimation of the present is provided under quite general conditions. Several examples are considered to demonstrate the accuracy of the current algorithm. Computational results reveal that the proposed approach produces better results as compared to some existing iterative methods.

math.NA↗
arXiv2020

Solving coupled Lane-Emden equations by Green's function and decomposition technique

In this paper, the Green's function and decomposition technique is proposed for solving the coupled Lane-Emden equations. This approach depends on constructing Green's function before establishing the recursive scheme for the series solution. Unlike, standard Adomian decomposition method, the present method avoids solving a sequence of transcendental equations for the undetermined coefficients. Convergence and error estimation is provided. Three examples of coupled Lane-Emden equations are considered to demonstrate the accuracy of the current algorithm.

math.NA↗
arXiv2019

A multiple-frame approach of crop yield estimation from satellite remotely sensed data

Many studies have recently explored the information from the satellite-remotely sensed data (SRSD) for estimating the crop production statistics. The value of this information depends on the aerial and spatial resolutions of SRSD. The SRSD with fine spatial resolution is costly and the aerial coverage is less. Use of multiple frames of SRSD in the estimation process of crop production can increase the precision. We propose an estimator for the average yield of wheat for the state of Haryana, India. This estimator uses the information from the Wide Field Sensor (WiFS) and the Linear Imaging Self Scanner (LISS-III) data from the Indian Remote Sensing satellite (IRS-1D) and the crop cutting experiment data collected by probability sampling design from a list frame of villages. We find that the relative efficiencies of the multiple-frame estimators are high in comparison to the single frame estimators.

stat.AP↗
arXiv2019

Performance of Kriging Based Soft Classification on WiFS/IRS- 1D image using Ground Hyperspectral Signatures

Hard and soft classification techniques are the conventional ways of image classification on satellite data. These classifiers have number of drawbacks. Firstly, these approaches are inappropriate for mixed pixels. Secondly, these approaches do not consider spatial variability. Kriging based soft classifier (KBSC) is a non-parametric geostatistical method. It exploits the spatial variability of the classes within the image. This letter compares the performance of KBSC with other conventional hard/soft classification techniques. The satellite data used in this study is the Wide Field Sensor (WiFS) from the Indian Remote Sensing Satellite -1D (IRS-1D). The ground hyperspectral signatures acquired from the agricultural fields by a hand held spectroradiometer are used to detect subpixel targets from the satellite images. Two measures of closeness have been used for accuracy assessment of the KBSC to that of the conventional classifications. The results prove that the KBSC is statistically more accurate than the other conventional techniques.

eess.IV↗
arXiv2017

Analytical Approach For Solving Population Balances: A Homotopy Perturbation Method

In the present work, a new approach is proposed for finding the analytical solution of population balances. This approach is relying on idea of Homotopy Perturbation Method (HPM). The HPM solves both linear and nonlinear initial and boundary value problems without nonphysical restrictive assumptions such as linearization and discretization. It gives the solution in the form of series with easily computable solution components. The outcome of this study reveals that the proposed method can avoid numerical stability problems which often characterize in general numerical techniques related to this area. Several examples including Austin's kernel available in literature are examined to demonstrate the accuracy and applicability of the proposed method.

math.NA↗
arXiv2017

Optimal homotopy analysis method with Green's function for a class of nonlocal elliptic boundary value problems

In this paper, we present the optimal homotopy analysis method (OHAM) with Green's function technique to acquire accurate numerical solutions for the nonlocal elliptic problems. We first transform the nonlocal boundary value problems into an equivalent integral equation, and then use an OHAM with convergence control parameter $c_0$. To demonstrate convergence and accuracy characteristics of the OHAM method, we compare the OHAM and Adomian decomposition method (ADM) with Green's function. The numerical experiments confirm the reliability of the approach as it handles such nonlocal elliptic differential equations without imposing limiting assumptions that could change the physical structure of the solution. We also discuss the convergence and error analysis of proposed method. In summary: $(i)$ the present approach does not require any additional computational work for unknown constants unlike ADM and VIM \cite{khuri2014variational} $(ii)$ guarantee of convergence $(iii)$ flexibility on choice of initial guess of solution and $(iv)$ useful analytic tool to investigate a class of nonlocal elliptic boundary value problems.

math.NA↗
arXiv2017

Haar wavelet quasilinearization technique for doubly singular boundary value problems

The Haar wavelet based quasilinearization technique for solving a general class of singular boundary value problems is proposed. Quasilinearization technique is used to linearize nonlinear singular problem. Second rate of convergence is obtained of a sequence of linear singular problems. Numerical solution of linear singular prob- lems is obtained by Haar-wavelet method. In each iteration of quasilinearization technique, the numerical solution is updated by the Haar wavelet method. Conver- gence analysis of Haar wavelet method is discussed. The results are compared with the results obtained by the other technique and with exact solution. Eight singular problems are solved to show the applicability of the Haar wavelet quasilinearization technique.

math.NA↗
arXiv2017

Analytical method and its convergence analysis based on homotopy analysis for the integral form of doubly singular boundary value problems

In this paper, we consider the nonlinear doubly singular boundary value problems $(p(x)y'(x))'+ q(x)f(x,y(x))=0,~0<x<1$ with Dirichlet/Neumann boundary conditions at $x=0$ and Robin type boundary conditions at $x=1$. Due to the presence of singularity at $x=0$ as well as discontinuity of $q(x)$ at $x=0$, these problems pose difficulties in obtaining their solutions. In this paper, a new formulation of the singular boundary value problems is presented. To overcome the singular behavior at the origin, with the help of Green's function theory the problem is transformed into an equivalent Fredholm integral equation. Then the optimal homotopy analysis method is applied to solve integral form of problem. The optimal control-convergence parameter involved in the components of the series solution is obtained by minimizing the squared residual error equation. For speed up the calculations, the discrete averaged residual error is used to obtain optimal value of the adjustable parameter $c_0$ to control the convergence of solution. The proposed method \textbf{(a)} avoids solving a sequence of transcendental equations for the undetermined coefficients \textbf{(b)} it is a general method \textbf{(c)} contains a parameter $c_0$ to control the convergence of solution. Convergence analysis and error estimate of the proposed method are discussed. Accuracy, applicability and generality of the present method is examined by solving five singular problems.

math.NA↗
arXiv2017

Adomian decomposition method for solving derivative-dependent doubly singular boundary value problems

In this work, we apply Adomian decomposition method for solving nonlinear derivative-dependent doubly singular boundary value problems: $(py')'= qf(x,y,y')$. This method is based on the modification of ADM and new two-fold integral operator. The approximate solution is obtained in the form of series with easily determinable components. The effectiveness of the proposed approach is examined by considering three examples and numerical results are compared with known results.

math.NA↗