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Kevin S. McFarland

Publications and source records attributed to Kevin S. McFarland.

15 recordsLinked to original sources
arXiv2026

Nucleon axial-vector form factor and radius from radiatively-corrected antineutrino scattering data

The nucleon axial-vector form factor, $G_A$, is critical to determine the electroweak interactions of leptons with nucleons. Important examples of processes influenced by $G_A$ are elastic (anti)neutrino-nucleon scattering and muon capture by the proton. Sparse experimental data results in a large uncertainty on the momentum dependence of $G_A$ and has motivated the consideration of new experimental probes and first-principles lattice quantum chromodynamics (QCD) evaluations. The comparison of new and precise theoretical predictions for $G_A$ with future experimental data necessitates the application of radiative corrections to experimentally-observable processes. We apply these corrections in the extraction of $G_A$ and the associated axial-vector radius from the recent MINERvA antineutrino-hydrogen data, compare the effects from radiative corrections to other uncertainties in neutrino scattering experiments, and discuss the comparison of lattice QCD evaluations to experimental measurements.

hep-ph↗
arXiv2023

Radiative corrections to inverse muon decay for accelerator neutrinos

Inverse muon decay ($ν_μe^- \to ν_e μ^-$) is a promising tool to constrain neutrino fluxes with energies $E_ν \ge 10.9~\mathrm{GeV}$. Radiative corrections introduce percent-level distortions to energy spectra of outgoing muons and depend on experimental details. In this paper, we calculate radiative corrections to the scattering processes $ν_μe^- \to ν_e μ^-$ and $\barν_e e^- \to \barν_μμ^-$. We present the muon energy spectrum for both channels, double-differential distributions in muon energy and muon scattering angle and in photon energy and photon scattering angle, and the photon energy spectrum for the dominant $ν_μe^- \to ν_e μ^-$ process. Our results clarify and extend the region of applicability of previous results in the literature for the double differential distribution in muon energy and photon energy, and in the muon energy spectrum with a radiated photon above a threshold energy. We provide analytic expressions for single, double and triple differential cross sections, and discuss how radiative corrections modify experimentally interesting observable distributions.

hep-ph↗
arXiv2022

QED radiative corrections for accelerator neutrinos

Neutrino oscillation experiments at accelerator energies aim to establish charge-parity violation in the neutrino sector by measuring the energy-dependent rate of $ν_e$ appearance and $ν_μ$ disappearance in a $ν_μ$ beam. These experiments can precisely measure $ν_μ$ cross sections at near detectors, but $ν_e$ cross sections are poorly constrained and require theoretical inputs. In particular, quantum electrodynamics radiative corrections are different for electrons and muons. These corrections are proportional to the small quantum electrodynamics coupling $α\approx 1/137$; however, the large separation of scales between the neutrino energy and the proton mass ($\sim{\rm GeV}$), and the electron mass and soft-photon detection thresholds ($\sim{\rm MeV}$) introduces large logarithms in the perturbative expansion. The resulting flavor differences exceed the percent-level experimental precision and depend on nonperturbative hadronic structure. We establish a factorization theorem for exclusive charged-current (anti)neutrino scattering cross sections representing them as a product of two factors. The first factor is flavor universal; it depends on hadronic and nuclear structure and can be constrained by high-statistics $ν_μ$ data. The second factor is non-universal and contains logarithmic enhancements, but can be calculated exactly in perturbation theory. For charged-current elastic scattering, we demonstrate the cancellation of uncertainties in the predicted ratio of $ν_e$ and $ν_μ$ cross sections. We point out the potential impact of non-collinear energetic photons and the distortion of the visible lepton spectra and provide precise predictions for inclusive observables.

hep-ph↗
arXiv2019

Neutrino-electron elastic scattering for flux determination at the DUNE oscillation experiment

We study the feasibility of using neutrino-electron elastic scattering to measure the neutrino flux in the DUNE neutrino oscillation experiment. The neutrino-electron scattering cross section is precisely known, and the kinematics of the reaction allow determination of the incoming neutrino energy by precise measurement of the energy and angle of the recoiling electron. For several possible near detectors, we perform an analysis of their ability to measure neutrino flux in the presence of backgrounds and uncertainties. With realistic assumptions about detector masses, we find that a liquid argon detector, even with limitations due to angular resolution, is able to perform better than less dense detectors with more precise event-by-event neutrino energy measurements. We find that the absolute flux normalization uncertainty can be reduced from ~8% to ~2%, and the uncertainty on the flux shape can be reduced by ~20-30%.

hep-ex↗
arXiv2016

Direct extraction of nuclear effects in quasielastic scattering on carbon

Nuclear effects on neutrino reactions are expected to be a significant complication in current and future neutrino oscillation experiments seeking precision measurements of neutrino flavor transitions. Calculations of these nuclear effects are hampered by a lack of experimental data comparing neutrino reactions on free nucleons to neutrino reactions on nuclei. We present results from a novel technique that compares neutrino and antineutrino charged current quasielastic scattering on hydrocarbons to extract a cross section ratio of antineutrino charged current elastic reactions on free protons to charged current quasielastic reactions on the protons bound in a carbon nucleus. This measurement of nuclear effects is compared to models.

hep-ex↗
arXiv2012

Differences in Quasi-Elastic Cross-Sections of Muon and Electron Neutrinos

Accelerator neutrino oscillation experiments seek to make precision measurements of the neutrino flavor oscillations muon (anti)neutrino to electron (anti)neutrino in order to determine the mass hierarchy of neutrinos and to search for CP violation in neutrino oscillations. These experiments are currently performed with beams of muon neutrinos at energies near 1 GeV where the charged-current quasi-elastic interactions nu+n\rightarrow(l^-)+p and anti-nu+p\rightarrow(l^+)+n dominate the signal reactions. We examine the difference between the quasi-elastic cross-sections for muon and electron neutrinos and anti-neutrinos and estimate the uncertainties on these differences.

hep-ph↗
arXiv2011

Quasi-Elastic Scattering in MINERvA

Determination of the quasi-elastic scattering cross-section over a broad range of neutrino energies, nuclear targets and Q^2 is a primary goal of the MINERvA experiment. We present preliminary comparisons of data and simulation in a sample rich in anti-ν_μ+p\rightarrowμ+n events from approximately one eighth of the total anti-ν events collected by MINERvA to date. We discuss future plans for quasi-elastic analyses in MINERvA.

hep-ex↗
arXiv2008

A Review of Target Mass Corrections

With recent advances in the precision of inclusive lepton--nuclear scattering experiments, it has become apparent that comparable improvements are needed in the accuracy of the theoretical analysis tools. In particular, when extracting parton distribution functions in the large-x region, it is crucial to correct the data for effects associated with the nonzero mass of the target. We present here a comprehensive review of these target mass corrections (TMC) to structure functions data, summarizing the relevant formulas for TMCs in electromagnetic and weak processes. We include a full analysis of both hadronic and partonic masses, and trace how these effects appear in the operator product expansion and the factorized parton model formalism, as well as their limitations when applied to data in the x->1 limit. We evaluate the numerical effects of TMCs on various structure functions, and compare fits to data with and without these corrections.

hep-ph↗
arXiv2003

Conventional Physics Explanations for the NuTeV sin2ThetaW

The NuTeV experiment has measured sin^2Theta_W = 0.2277 +/- 0.0013(stat) +/- 0.0009(syst), approximately 3 standard deviations above the standard model prediction. This discrepancy has motivated speculation that the NuTeV result may be affected significantly by neglected experimental or theoretical effects. We examine the case for a number of proposed explanations.

hep-ph↗
arXiv2003

Summary of Working Group 2

Issues on the physics of, beamlines for, and detectors of neutrino oscillation discussed in Working Group 2 at Nufact'02 are summarized.

hep-ph↗
arXiv2001

Flavor Decomposition of Nucleon Structure at a Neutrino Factory

We explore the possibilities for measuring the quark content of the proton and neutron using neutrino beams produced at a muon storage ring. Because of the nature of the beams, small nuclear targets such as hydrogen and deuterium can be considered, as well as polarized targets. The statistics expected from these targets are calculated using nominal muon storage ring intensities, and the resulting statistical errors on the numerous structure functions available are given, for both polarized and unpolarized targets. It is shown that with a relatively small target, the structure functions F_2, xF_3, xg_1 and xg_5 for neutrinos and antineutrinos on protons and deuterium, either unpolarized or polarized, could be determined with excellent precision over most of the accessible kinematic range.

hep-ph↗
arXiv1999

Neutrino Mass and Oscillation

The question of neutrino mass is one of the major riddles in particle physics. Recently, strong evidence that neutrinos have nonzero masses has been found. While tiny, these masses could be large enough to contribute significantly to the mass density of the universe. The evidence for nonvanishing neutrino masses is based on the apparent observation of neutrino oscillation -- the transformation of a neutrino of one type or "flavor" into one of another. We explain the physics of neutrino oscillation, and review and weigh the evidence that it actually occurs in nature. We also discuss the constraints on neutrino mass from cosmology and from experiments with negative results. After presenting illustrative neutrino mass spectra suggested by the present data, we consider how near- and far-future experiments can further illuminate the nature of neutrinos and their masses.

hep-ph↗
arXiv1998

Detectors for Neutrino Physics at the First Muon Collider

We consider possible detector designs for short-baseline neutrino experiments using neutrino beams produced at the First Muon Collider complex. The high fluxes available at the muon collider make possible high statistics deep-inelastic scattering neutrino experiments with a low-mass target. A design of a low-energy neutrino oscillation experiment on the ``tabletop'' scale is also discussed.

hep-ex↗
arXiv1998

A Small Target Neutrino Deep-Inelastic Scattering Experiment at the First Muon Collider

Several different scenarios for neutrino scattering experiments using a neutrino beam from the muon collider complex are discussed. The physics reach of a neutrino experiment at the front end of a muon collider is shown to extend far beyond that of current neutrino experiments, since the high intensity neutrino beams one would see at the muon collider allow for a large flexibility in choosing neutrino targets. Measurements of quark spin, A-dependence of the structure function $xF_3$ and neutral current chiral couplings to quarks are outlined.

hep-ex↗