arXiv subjects

M. Sajjad Athar

Publications and source records attributed to M. Sajjad Athar.

At least 37 records · Page 2Linked to original sources

arXiv2024

Measurement of Electron Neutrino and Antineutrino Cross Sections at Low Momentum Transfer

Accelerator based neutrino oscillation experiments seek to measure the relative number of electron and muon neutrinos and antineutrinos at different $L/E$ values. However high statistics studies of neutrino interactions are almost exclusively measured using muon neutrinos and antineutrinos since the dominant flavor of neutrinos produced by accelerator based beams are of the muon type. This work reports new measurements of electron neutrino and antineutrino interactions in hydrocarbon, obtained by strongly suppressing backgrounds initiated by muon flavor neutrinos and antineutrinos. Double differential cross sections as a function of visible energy transfer, $E_\text{avail}$, and transverse momentum transfer, $p_T$, or three momentum transfer, $q_3$ are presented.

hep-ex↗

arXiv2023

Measurement of the Multi-Neutron $\barν_μ$ Charged Current Differential Cross Section at Low Available Energy on Hydrocarbon

Neutron production in antineutrino interactions can lead to bias in energy reconstruction in neutrino oscillation experiments, but these interactions have rarely been studied. MINERvA previously studied neutron production at an average antineutrino energy of ~3 GeV in 2016 and found deficiencies in leading models. In this paper, the MINERvA 6 GeV average antineutrino energy data set is shown to have similar disagreements. A measurement of the cross section for an antineutrino to produce two or more neutrons and have low visible energy is presented as an experiment-independent way to explore neutron production modeling. This cross section disagrees with several leading models' predictions. Neutron modeling techniques from nuclear physics are used to quantify neutron detection uncertainties on this result.

hep-ex↗

arXiv2023

Weak production of $η$ mesons induced by $ν_μ(\barν_μ)$ at MicroBooNE energies

We have studied neutral and charged current (anti)neutrino induced $η$ production off the free nucleon target at MicroBooNE energies, in the light of recent results reported by the MicroBooNE collaboration for the total $η$ production cross section. This study has been made using a theoretical model in which the weak hadronic current receives contribution from the nonresonant Born terms as well as from the resonance excitations. The Born terms are obtained using the SU(3) symmetric chiral model, used earlier in the study of $K-$meson production. The contribution from the resonance terms is considered from the excitation of five nucleon resonances viz. $S_{11}(1535)$, $S_{11}(1650)$, $P_{11}(1710)$, $P_{11}(1880)$, and $S_{11}(1895)$. To fix the parameters of the vector current interaction, this model is first used to study the electromagnetic production of $η$ mesons induced by real and virtual photons, and the theoretical results have been compared with the data from the MAINZ and JLab experiments. The partially conserved axial-vector current hypothesis and generalized Goldberger-Treiman relation are used to fix the parameters of the axial-vector current interaction. The results are presented for the total cross section for the neutral and charged current induced $η$ production, ratio of the cross sections for the charged current to neutral current, MicroBooNE flux averaged cross section $\langle σ\rangle$, $\left \langle \frac{dσ}{dQ^2} \right\rangle$ and $\left\langle \frac{dσ}{dp_η} \right\rangle$, which may be useful in the future analysis of MicroBooNE as well as other accelerator and atmospheric neutrino experiments being performed in the ${\cal O}$(1)~GeV energy region.

hep-ph↗

arXiv2023

Nuclear effects on tau lepton polarization in charged current deep inelastic $ν_τ/\barν_τ-A$ scattering

We have studied the tau-lepton polarization in the charged current $ν_τ/\barν_τ$ induced deep inelastic scattering (DIS) from the free nucleon as well as off the nuclear targets that are being used in ongoing and proposed experiments such as IceCube, DUNE, etc. For the free nucleon target, the differential scattering cross sections are obtained by taking into account the non-perturbative effect like target mass corrections (TMC) and the perturbative effect like the evolution of the parton densities at the next-to-leading order (NLO) in the four flavor $\overline{\textrm{MS}}-$scheme. In the case of nucleons bound inside a nuclear target, we have incorporated the nuclear medium effects such as Fermi motion, binding energy and nucleon correlations, through the use of nucleon spectral function. We shall present the results for the differential scattering cross sections and the longitudinal and transverse components of the tau-lepton polarization assuming time reversal invariance.

hep-ph↗

arXiv2023

Simultaneous measurement of muon neutrino $ν_μ$ charged-current single $π^+$ production in CH, C, H$_2$O, Fe, and Pb targets in MINERvA

Neutrino-induced charged-current single $π^+$ production in the $Δ(1232)$ resonance region is of considerable interest to accelerator-based neutrino oscillation experiments. In this work, high statistics differential cross sections are reported for the semi-exclusive reaction $ν_μA \to μ^- π^+ +$ nucleon(s) on scintillator, carbon, water, iron, and lead targets recorded by MINERvA using a wide-band $ν_μ$ beam with $\left< E_ν\right> \approx 6$~GeV. Suppression of the cross section at low $Q^2$ and enhancement of low $T_π$ are observed in both light and heavy nuclear targets compared to phenomenological models used in current neutrino interaction generators. The cross-section ratios for iron and lead compared to CH across the kinematic variables probed are 0.8 and 0.5 respectively, a scaling which is also not predicted by current generators.

hep-ex↗

arXiv2023

Neutrino-induced coherent $π^{+}$ production in C, CH, Fe and Pb at $\langle E_ν\rangle \sim 6$ GeV

MINERvA has measured the $ν_μ$-induced coherent $π^{+}$ cross section simultaneously in hydrocarbon (CH), graphite (C), iron (Fe) and lead (Pb) targets using neutrinos from 2 to 20 GeV. The measurements exceed the predictions of the Rein-Sehgal and Berger-Sehgal PCAC based models at multi-GeV $ν_μ$ energies and at produced $π^{+}$ energies and angles, $E_π>1$ GeV and $θ_π<10^{\circ}$. Measurements of the cross-section ratios of Fe and Pb relative to CH reveal the effective $A$-scaling to increase from an approximate $A^{1/3}$ scaling at few GeV to an $A^{2/3}$ scaling for $E_ν>10$ GeV.

hep-ex↗

arXiv2023

High-Statistics Measurement of Antineutrino Quasielastic-like scattering at $E_ν\sim$ 6~GeV on a Hydrocarbon Target

We present measurements of the cross section for anti-neutrino charged-current quasielastic-like scattering on hydrocarbon using the medium energy (ME) NuMI wide-band neutrino beam peaking at $ \sim 6$ GeV. The cross section measurements are presented as a function of the longitudinal momentum ($p_{||}$) and transverse momentum ($p_{T}$) of the final state muon. This work complements our previously reported high statistics measurement in the neutrino channel and extends the previous anti-neutrino measurement made in the low energy (LE) beam at neutrino energy($ $) $\sim$ 3.5 GeV to $p_{T}$ of 2.5 GeV/c. Current theoretical models do not completely describe the data in this previously unexplored high $p_{T}$ region. The single differential cross section as a function of four momentum transfer ($Q^{2}_{QE}$) now extends to 4 GeV$^2$ with high statistics. The cross section as a function of $Q^{2}_{QE}$ shows that the tuned simulations developed by the MINERvA collaboration that agreed well with the low energy beam measurements do not agree as well with the medium energy beam measurements. Newer neutrino interaction models such as the GENIE 3 tunes are better able to simulate the high $Q^{2}_{QE}$.

hep-ex↗

arXiv2023

Simultaneous measurement of muon neutrino quasielastic-like cross sections on CH, C, water, Fe, and Pb as a function of muon kinematics at MINERvA

This paper presents the first simultaneous measurement of the quasielastic-like neutrino-nucleus cross sections on C, water, Fe, Pb and scintillator (hydrocarbon or CH) as a function of longitudinal and transverse muon momentum. The ratio of cross sections per nucleon between Pb and CH is always above unity and has a characteristic shape as a function of transverse muon momentum that evolves slowly as a function of longitudinal muon momentum. The ratio is constant versus longitudinal momentum within uncertainties above a longitudinal momentum of 4.5GeV/c. The cross section ratios to CH for C, water, and Fe remain roughly constant with increasing longitudinal momentum, and the ratios between water or C to CH do not have any significant deviation from unity. Both the overall cross section level and the shape for Pb and Fe as a function of transverse muon momentum are not reproduced by current neutrino event generators. These measurements provide a direct test of nuclear effects in quasielastic-like interactions, which are major contributors to long-baseline neutrino oscillation data samples.

hep-ex↗

arXiv2022

Neutrinos and their interactions with matter

We have presented a review of the properties of neutrinos and their interactions with matter. The different (anti)neutrino processes like the quasielastic scattering, inelastic production of mesons and hyperons, and the deep inelastic scattering from the free nucleons are discussed and the results for the scattering cross sections are presented. The polarization observables for the leptons and hadrons produced in the final state, in the case of quasielastic scattering, are also studied. The importance of nuclear medium effects in the low, intermediate and high energy regions, in the above processes along with the processes of the coherent neutrino-nucleus scattering, coherent meson production, and trident production, have been highlighted. In some cases the results of the cross sections are also given and compared with the available experimental data as well as with the predictions in the different theoretical models. This study would be helpful in understanding the (anti)neutrino interaction cross section with matter in the few GeV energy region relevant to the next generation experiments like DUNE, Hyper-Kamiokande, and other experiments with accelerator and atmospheric neutrinos. We have emphasized the need of better theoretical models for some of these processes for studying the nuclear medium effects in nuclei.

hep-ph↗

arXiv2022

Charged current (anti)neutrino induced eta production off the nucleon

The charged current (anti)neutrino induced eta production from the nucleons is studied in a model based on the effective Lagrangians to evaluate the contribution from the nonresonant and resonant diagrams. The contribution from the nonresonant background terms has been obtained using a microscopic model based on the SU(3) chiral Lagrangians. The contribution from the resonant diagrams due to the low lying $S_{11}(1535)$, $S_{11} (1650)$, and $P_{11} (1710)$ resonances has been evaluated using an effective phenomenological Lagrangian with its parameters determined from the experimental values of their branching ratios and decay widths to the $Nη$ channel. The model is first used to reproduce satisfactorily the experimental data from the MAINZ and JLab on the total cross sections for the photo- and electro- production of $η$ mesons, which fixes the model parameters in the vector current interaction. The PCAC hypothesis and generalized Goldberger-Treiman relation are used to fix the parameters of the axial vector interaction. The model is then applied to study the weak production of eta mesons induced by the neutrinos and antineutrinos, and predicts the numerical values for the $Q^2$-distribution, $η$-momentum distribution, and the total cross section for the reactions $ν_μ + n \longrightarrow μ^{-} + p + η$ and $\barν_μ + p \longrightarrow μ^+ + n + η$ in the energy region up to 2 GeV. It is found that the photo, electro, and (anti)neutrino production of eta mesons is dominated by the contribution from the $S_{11}(1535)$ resonance. The results discussed in this work are relevant for the present and future accelerator experiments like MicroBooNE, T2K, NOvA, MINERvA, T2-HyperK and DUNE as well as for the atmospheric neutrino experiments.

hep-ph↗

arXiv2022

Improved constraint on the MINERvA medium energy neutrino flux using $\barνe^{-} \!\rightarrow \barνe^{-}$ data

Processes with precisely known cross sections, like neutrino electron elastic scattering ($νe^{-} \!\rightarrow νe^{-}$) and inverse muon decay ($ν_μe^{-} \!\rightarrow μ^{-} ν_e$) have been used by MINERvA to constrain the uncertainty on the NuMI neutrino beam flux. This work presents a new measurement of neutrino elastic scattering with electrons using the medium energy \numubar enhanced NuMI beam. A sample of 578 events after background subtraction is used in combination with the previous measurement on the \numu beam and the inverse muon decay measurement to reduce the uncertainty on the \numu flux in the \numu-enhanced beam from 7.6\% to 3.3\% and the \numubar flux in the \numubar-enhanced beam from 7.8\% to 4.7\%.

hep-ex↗

arXiv2022

Simultaneous measurement of proton and lepton kinematics in quasielastic-like $ν_μ$-hydrocarbon interactions from 2 to 20 GeV

Neutrino charged-current quasielastic-like scattering, a reaction category extensively used in neutrino oscillation measurements, probes nuclear effects that govern neutrino-nucleus interactions. This Letter reports the first measurement of the triple-differential cross section for $ν_μ$ quasielastic-like reactions using the hydrocarbon medium of the MINERvA detector exposed to a wide-band beam spanning 2 $\leq$ E$_ν\leq$ 20 GeV. The measurement maps the correlations among transverse and longitudinal muon momenta and summed proton kinetic energies, and compares them to predictions from a state-of-art simulation. Discrepancies are observed that likely reflect shortfalls with modeling of pion and nucleon intranuclear scattering and/or spectator nucleon ejection from struck nuclei. The separate determination of leptonic and hadronic variables can inform experimental approaches to neutrino-energy estimation.

hep-ex↗

arXiv2022

Theoretical tools for neutrino scattering: interplay between lattice QCD, EFTs, nuclear physics, phenomenology, and neutrino event generators

Maximizing the discovery potential of increasingly precise neutrino experiments will require an improved theoretical understanding of neutrino-nucleus cross sections over a wide range of energies. Low-energy interactions are needed to reconstruct the energies of astrophysical neutrinos from supernovae bursts and search for new physics using increasingly precise measurement of coherent elastic neutrino scattering. Higher-energy interactions involve a variety of reaction mechanisms including quasi-elastic scattering, resonance production, and deep inelastic scattering that must all be included to reliably predict cross sections for energies relevant to DUNE and other accelerator neutrino experiments. This white paper discusses the theoretical status, challenges, required resources, and path forward for achieving precise predictions of neutrino-nucleus scattering and emphasizes the need for a coordinated theoretical effort involved lattice QCD, nuclear effective theories, phenomenological models of the transition region, and event generators.

hep-ph↗

arXiv2022

Nuclear medium effects in the deep inelastic $ν_τ/\barν_τ-^{40}Ar$ scattering at DUNE energies

The nuclear medium effects are studied in the $ν_τ/\barν_τ$ interactions from nuclei in the deep inelastic scattering (DIS) region and applied to the $^{40}Ar$ nucleus to obtain the scattering cross sections in the energy region of the proposed DUNE experiment. The free nucleon structure functions ($F_{iN}(x,Q^2);~(i=1-5)$) have been calculated at the next-to-leading order (NLO) using Martin-Motylinski-Harland Lang-Thorne 2014 as well as The Coordinated Theoretical-Experimental Project on QCD parameterizations for parton distribution functions (PDFs) and including the effect of perturbative and nonperturbative QCD corrections \cite{Ansari:2020xne}. These free nucleon structure functions are then convoluted with the nucleon spectral function in the nucleus to obtain the nuclear structure functions ($F_{iA}(x,Q^2);~(i=1-5)$). The nucleon spectral function takes into account the Fermi motion and the binding energy of the nucleons as well as the nucleon correlations within the nucleus. These nuclear structure functions are then used to calculate the deep inelastic scattering cross sections. Moreover, the contribution of $π$ and $ρ$ mesons as well as the corrections due to the shadowing and antishadowing effects in the relevant kinematic region of the Bjorken variable $x$ are also included. The numerical results for the cross sections have been presented and compared with the results obtained in the phenomenological approach using nuclear structure functions from nCTEQnu.

nucl-th↗

arXiv2022

Nuclear medium effects in lepton-nucleus DIS in the region of $x \gtrsim 1$

The nuclear medium effects in the nuclear structure functions and differential cross sections in the deep inelastic scattering (DIS) of charged lepton and neutrino from nuclear targets are studied in the region of large $x$ including $x\ge 1$. The nuclear medium effects due to the Fermi motion and the binding energy of nucleons and the nucleon correlations are included using nucleon spectral function calculated in a microscopic field theoretical model. The numerical results for the nuclear structure functions and the cross sections are obtained using the nucleon structure function evaluated at the next-to-next-to-leading order (NNLO) with the Martin-Motylinski-Harland Lang-Thorne (MMHT) parameterization of the nucleonic parton distribution functions (PDFs) and are compared with the available experimental data on electron scattering from the Jefferson Lab (JLab) and SLAC Nuclear Physics Facility (NPAS). In the case of neutrino scattering the results are relevant for understanding the DIS contributions to the recent inclusive cross sections measured by the Main Injector Neutrino ExpeRiment to study v-A interactions (MINERvA) as well as theoretical predictions are made for Deep Underground Neutrino Experiment (DUNE). The importance of isoscalarity corrections in heavier nuclear targets as well as the effect of the kinematic cut on the CM energy $W$ in defining the DIS region have also been discussed.

hep-ph↗

arXiv2022

Vertex finding in neutrino-nucleus interaction: A Model Architecture Comparison

We compare different neural network architectures for Machine Learning (ML) algorithms designed to identify the neutrino interaction vertex position in the MINERvA detector. The architectures developed and optimized by hand are compared with the architectures developed in an automated way using the package "Multi-node Evolutionary Neural Networks for Deep Learning" (MENNDL), developed at Oak Ridge National Laboratory (ORNL). The two architectures resulted in a similar performance which suggests that the systematics associated with the optimized network architecture are small. Furthermore, we find that while the domain expert hand-tuned network was the best performer, the differences were negligible and the auto-generated networks performed well. There is always a trade-off between human, and computer resources for network optimization and this work suggests that automated optimization, assuming resources are available, provides a compelling way to save significant expert time.

hep-ex↗

arXiv2022

Hyperon production in quasielastic $\barν_τ-$nucleon scattering

The theoretical results for the total cross sections and polarization components of the $τ^{+}$ lepton produced in the charged current induced $|ΔS| = 1$ quasielastic $\barν_τ- N$ scattering leading to hyperons ($Λ, Σ$) have been presented assuming T invariance. The theoretical uncertainties arising due to the use of different vector, axial vector and pseudoscalar form factors as well as the effect of SU(3) symmetry breaking have been studied. We have also presented, for the first time, a comparison of the total cross sections for the production of $e,μ,τ$ leptons to facilitate the implications of lepton flavor universality~(LFU) in the $|ΔS| = 1$ quasielastic reactions induced by the antineutrinos of all flavors i.e., $ν_{l};~l=e,μ,τ$.

hep-ph↗

arXiv2021

T-violating effect in $ν_τ (\barν_τ)-$nucleon quasielastic scattering

The production cross sections and polarization observables of the $τ$ leptons produced in the $|ΔS| = 0$ and $1$ induced $ν_τ(\barν_τ)-N$ quasielastic scattering have been studied. The effect of T violation, in the case of $ΔS=0$ and 1 processes, and the SU(3) symmetry breaking effects, in the case of $ΔS=1$ processes, on the total scattering cross sections as well polarization observables are explored. Experimentally, it would be possible to observe these effects in the forthcoming (anti)neutrino experiments like DUNE, SHiP and DsTau.

hep-ph↗