arXiv subjects

R. B. Singh

Publications and source records attributed to R. B. Singh.

11 recordsLinked to original sources

arXiv2026

Non-Unitarity Effects and Fake CP Violation in Neutrino Oscillation Experiments

Future long-baseline neutrino oscillation experiments aim to establish leptonic CP violation and determine the neutrino mass ordering with unprecedented precision. However, these measurements can be significantly affected by possible deviations from the unitarity of the PMNS mixing matrix, which introduce additional CP-violating phases capable of generating fake CP-violating signals. We investigate the impact of non-unitary leptonic mixing on CP-violation and mass-ordering measurements at DUNE and Hyper-Kamiokande using GLoBES simulations with a custom non-unitary probability engine. We analyze the energy dependence of the neutrino--antineutrino CP asymmetry, quantify the fake-to-genuine CP asymmetry ratio, evaluate the CP violation discovery sensitivity, and study the hierarchy--CP--non-unitarity degeneracies in the $(δ_{CP},ϕ_{21})$ parameter space. We demonstrate that non-unitary mixing can generate sizeable CP asymmetries even for CP-conserving values of the standard Dirac phase, thereby mimicking genuine leptonic CP violation. While the fake contribution remains below $5\%$ of the genuine signal near each experiment's oscillation maximum, it exceeds the genuine signal in specific intermediate energy windows ($\sim130\%$ at $1.5$--$1.6$~GeV), demonstrating that fake CP violation can dominate over the genuine contribution in these regions. The combined DUNE and Hyper-Kamiokande analysis reduces the allowed $(δ_{CP},φ_{21})$ parameter space by a factor of $7$ at $1σ$ and $\sim16$ at $2σ$--$3σ$, substantially suppressing the degeneracy that neither experiment resolves individually and providing a robust strategy for distinguishing genuine from fake CP violation while improving sensitivity to the neutrino mass ordering.

hep-ph↗

arXiv2026

Statistical Framework for Discovery Sensitivity and Majorana Mass Estimation in $^{136}$Xe Neutrinoless Double Beta Decay

Neutrinoless double-beta decay ($0νββ$) is a sensitive probe of lepton-number violation and the Majorana nature of neutrinos. In xenon-based experiments, the expected signal rate inside the region of interest (ROI) is extremely small, requiring sensitivity estimates based on Poisson statistics and a careful treatment of detector resolution, background fluctuations, and systematic uncertainties. In this work, we develop a statistical framework relating energy resolution, ROI width, background index, isotope exposure, and discovery sensitivity for $^{136}$Xe-based $0νββ$ experiments. The formalism combines Poisson likelihood methods with realistic background modeling and includes reconstruction-related and final-state interaction (FSI) systematic effects through an effective ROI broadening approach. Using representative detector parameters for LZ, NEXT-100, KamLAND-Zen, and nEXO, we compare expected background counts, required discovery signal statistics, and half-life sensitivities at matched exposure. The corresponding sensitivities are translated into effective Majorana mass reach within both normal- and inverted-hierarchy neutrino mass ordering. The impact of uncertainties associated with the axial-vector coupling constant $g_A$, nuclear matrix elements, and phase-space factors is also examined. Our results show that background suppression, ROI optimization, and control of detector-related systematics are essential for extending sensitivity toward the normal-ordering regime in future $0νββ$ searches.

hep-ph↗

arXiv2022

Study of pion production in $ν_μ$ interactions on $^{40}$Ar in DUNE using GENIE and NuWro event generators

The study of pion production and the effects of final state interactions (FSI) are important for data analysis in all neutrino experiments. For energies at which current neutrino experiments are being operated, a significant contribution to pion production is made by resonance production process. After its production, if a pion is absorbed in the nuclear matter, the event may become indistinguishable from quasi-elastic scattering process and acts as a background. The estimation of this background is very essential for oscillation experiments and requires good theoretical models for both pion production at primary vertex and after FSI. Due to FSI, the number of final state pions is significantly different from the number produced at primary vertex. As the neutrino detectors can observe only the final state particles, the correct information about the particles produced at the primary vertex is overshadowed by FSI. To overcome this difficulty, a good knowledge of FSI is required which may be provided by theoretical models incorporated in Monte Carlo (MC) neutrino event generators. In this work, we will present simulated events for two different MC generators - GENIE and NuWro, for pion production in $ν_μ$CC interactions on $^{40}$Ar target in DUNE experimental set up. A brief outline of theoretical models used by generators is presented. The results of pion production are presented in the form of tables showing the occupancy of primary and final state pion topologies with 100$\%$ detector resolution and with kinetic energy detector threshold cuts. We observe that NuWro (v-19.02.2) is more transparent (less responsive) to absorption and charge exchange processes as compared to GENIE (v-3.00.06), pions are more likely to be absorbed than created during their intranuclear transport and there is need to improve detector technology to improve the detector threshold for better results.

hep-ph↗

arXiv2021

Constraining nuclear effects in Argon using machine learning algorithms

Neutrino oscillation experiments aim to measure the neutrino oscillation parameters with accuracy and achieve a complete understanding of neutrino physics. For determining the neutrino oscillation parameters, knowledge of neutrino energy is a prerequisite. But neutrino energy needs to be reconstructed, based on the particles in the final state that emerge out of the nucleus following a neutrino-nucleus interaction. Current and upcoming neutrino oscillation experiments use heavy nuclear targets (viz. Argon(Ar), Calcium(Ca), etc.) but the neutrino scattering with such targets becomes complicated as compared to that with a clean target like Hydrogen(H). This work explores the viability of using machine learning algorithms (MLA) in reconstructing neutrino energy. We use final state kinematics generated from two neutrino event generators viz. GENIE and GiBUU to train the MLA. We calculate the Ar/H ratio in an attempt to quantify nuclear effects in the Ar target. We observe a significant improvement in our results when we train the MLA by combining the FSI kinematics of neutrino interactions from both the neutrino event generators.

hep-ph↗

arXiv2020

Impact of Cross-Sectional Uncertainties on DUNE Sensitivity due to Nuclear Effects

In neutrino oscillation experiments precise measurement of neutrino oscillation parameters is of prime importance as well as a challenge. To improve the statistics, presently running and proposed experiments are using heavy nuclear targets. These targets introduce nuclear effects and the quantification of these effects on neutrino oscillation parameters will be decisive in the prediction of neutrino oscillation physics. Limited understanding of neutrino nucleus interactions and inaccurate reconstruction of neutrino energy causes uncertainty in the cross section. The error in the determination of cross section which contributes to systematic error introduces error in the neutrino mixing parameters that are determined by these experiments. In this work we focus on the variation in the predictions of DUNE potential, arising due to systematic uncertainties, using two different event generators-GENIE and GiBUU. These generators have different and independent cross-section models. To check the DUNE potential with the two generators as mentioned we have checked the senstivity studies of DUNE for CP violation, mass hierarchy and octant degeneracy.

hep-ph↗

arXiv2020

Quantifying multinucleon effect in Argon using high-pressure TPC

Neutrino oscillation experiments use heavy nuclear targets to achieve sufficient interaction rates. Nuclear effects are introduced in the experimental environment by the use of these targets and need to be quantified as they add to the systematic errors. In the low energy region(around 1 GeV) multinucleon events are also present along with Quasi Elastic(QE) and Delta interactions. Therefore if these multinucleon events are not incorporated in the data set properly, we end up with an inaccurate reconstruction of neutrino energy. In our work, we have illustrated the importance of incorporation of multinucleon events for the reduction of systematic errors in physics predictions by DUNE-Near Detector(ND). To achieve this we have presented the event distribution ratio of Ar/C, Ar/Ar, and C/C as a function of squared four-momentum transfer by employing different nuclear models. This analysis recommends the addition of 2p2h or multinucleon events in the event sample and promotes model with Random Phase Approximations(RPA) effect for the analysis of the event sample to overcome or reduce the systematic uncertainties.

nucl-th↗

arXiv2020

DUNE prospect for leptophobic dark matter

Highly energetic proton/electron beam fixed target experiments extends an opportunity to probe the sub-GeV dark matter and associated interactions. In this work we have explored the sensitivity of DUNE for sub-GeV leptophobic dark matter i.e. this dark matter barely couples with the leptons. Baryon number gauge theory can predicts the existence of a leptophobic cold dark matter particle candidates. In our work, the dark matter candidate is considered to be scalar whose mass is defined by the symmetry breaking of new baryonic gauge group $U(1)_{B}$. In this scenario a light scalar dark matter couples with the standard model candidates via vector boson mediator $V_{B}$ which belongs to the baryonic gauge group $U(1)_{B}$. This leptophobic dark matter dominantly couples to the quarks. Under this scenario new parameter space for $α_{B}$ is explored by DUNE for leptophobic dark matter candidates. This new parameter space allowed $α_{B}$ to get lower value than the present exiting constraint value of $α_{B}$ i.e. $10^{-6}$.

hep-ph↗

arXiv2020

DUNE potential for sub-GeV dark matter in proton beam dump mode

DUNE with its cutting edge technology is designed to study the neutrino science and proton decay physics. This facility can be further exploited for the study of the ground breaking discoveries i.e. origin of matter, unification of forces, dark matter detection etc. In this work we have explored the DUNE potential for capturing the sub-GeV dark matter in viable dark matter parameter space. The scenario of sub-GeV dark matter range requires a light mediator that couples the hidden sector with the standard model. The choice of the mediator will decide the different channels by which dark matter candidates can be produced. Here three channels $π^{0}/η$-decay, proton bremsstrahlung and parton-level production modes are considered for the production of dark matter with a 120 GeV proton beam facility placed at Fermi lab. To overcome the neutrino background we have used beam dump mode for the production of pure dark matter beam. To explore the new region of parameter space of dark matter at DUNE the elastic scattering of dark matter beam with electrons and nucleons are studied. In terms of DUNE potential for capturing dark matter signatures the dark matter yield results at DUNE (in our work) shows a significant improvement over existing dark matter probes i.e. BaBar, E137, LSND, MiniBooNE, T2K etc.

hep-ph↗

arXiv2019

Neutrino Oscillations and Leptogenesis

The symmetry breaking of left right symmetric model around few TeV range permits the existence of massive right handed neutrinos or gauge bosons. In this work the decay of lightest right handed neutrinos in a class of minimal left right symmetric model is analysed for the generation of adequate lepton asymmetry. An analytical expression for the lepton asymmetry is developed. In an attempt to achieve the required baryogenesis, we have imposed certain constrains on the parameter space corresponding to low energy neutrino oscillation parameters (especially θ 13 ) and the three phases ( CP, majorana and higher energy phase).

hep-ph↗

arXiv2019

Effect of final state interactions on neutrino energy reconstruction at DUNE

We quantitatively study the percentage of fake events present in CCQE and CCRes interactions and the impact of final state interactions on the neutrino oscillation parameters at Dune. Resonance interaction will be the most dominant interaction in the oscillation sensitive region of DUNE. The effect of final-state interactions for DUNE oscillation physics is analysed in an ideal and realistic detector scenario. The $ν_μ$-disappearance Oscillation channel is studied using LAr detector. We find that nuclear effects and detector thresholds plays an significant role in CCQE and CCRes interactions and these nuclear effects induces a significant bias in the determination of atmospheric oscillation parameters. The impression of nuclear effects on the determination of $θ_{23}$ is quantified in this work.

hep-ph↗

arXiv2016

Checking T and CPT violation with sterile neutrino

Post LSND results, sterile neutrinos have drawn attention and motivated the high energy physics, astronomy and cosmology to probe physics beyond the standard model considering minimal 3+1 (3 active and 1 sterile) to 3+N neutrino schemes. The analytical equations for neutrino conversion probabilities are developed in this work for 3+1 neutrino scheme. Here, we have tried to explore the possible signals of T and CPT violations with four flavor neutrino scheme at neutrino factory. Values of sterile parameters considered in this analysis are taken from two different types of neutrino experiments viz. long baseline experiments and reactor+atmospheric experiments. In this work golden and discovery channels are selected for the investigation of T violation. While observing T violation we stipulate that neutrino factory working at 50 GeV energy have the potential to observe the T violation signatures for the considered range of baselines(3000 km-7500 km). The ability of neutrino factory for constraining CPT violation is enhanced with increase in energy for normal neutrino mass hierarchy(NH). Neutrino factory with the exposure time of 500 kt-yr will be able to capture CPT violation with $ δc_{31}\geq 3.6\times10^{-23} $ GeV at 3$ σ$ level for NH and for IH with $ δc_{31}\geq 4\times10^{-23} $ GeV at 3$ σ$ level.

hep-ph↗