arXiv subjects

S. F. Pate

Publications and source records attributed to S. F. Pate.

At least 19 recordsLinked to original sources

arXiv2026

Binned and Unbinned Transverse Single Spin Asymmetry Extraction, including Background Subtraction and Unfolding

The determination of transverse single-spin asymmetries in experiments involving polarized targets and/or beams may encounter challenges when (1) the magnitude of the polarization varies greatly with time, (2) the polarization magnitude is not the same for each spin state, (3) different integrated luminosities occur for different spin states or different target materials, and/or (4) some kinematic variables require unfolding; these are just a few examples. We present general methods of determining the asymmetry based on both binned analysis and unbinned maximum likelihood optimization, incorporating the unfolding of kinematic variables that are smeared by detector effects, and also including the possibility of background subtraction.

hep-ex↗

arXiv2025

Progress on Constraining the Strange Quark Contribution to the Nucleon Spin

We report on a global fit of neutral-current elastic (NCE) neutrino-scattering data and parity-violating electron-scattering (PVES) data with the goal of determining the strange quark contribution to the vector and axial form factors of the proton. Knowledge of the strangeness contribution to the axial form factor, $G_A^s(Q^2)$, at low $Q^2$ will reveal the strange quark contribution to the nucleon spin, as $G_A^s(Q^2=0)=\Delta s$. Previous fits [1,2] of this form included data from a variety of PVES experiments (PVA4, HAPPEx, G0, SAMPLE) and the NCE neutrino and anti-neutrino data from BNL E734. These fits did not constrain $G_A^s(Q^2)$ at low $Q^2$ very well because there was no NCE data for $Q^2<0.45$ GeV$^2$. Our new fit includes for the first time MiniBooNE NCE data from both neutrino and anti-neutrino scattering; this experiment used a hydrocarbon target and so a model of the neutrino interaction with the carbon nucleus was required. Three different nuclear models have been employed; a relativistic Fermi gas (RFG) model, the SuperScaling Approximation (SuSA) model, and a spectral function (SF) model [3]. We find a tremendous improvement in the constraint of $G_A^s(Q^2)$ at low $Q^2$ compared to previous work, although more data is needed from NCE measurements that focus on exclusive single-proton final states, for example from MicroBooNE [4]. This work has been published in Physical Review D [5]. [1] S.F. Pate, D. McKee, V. Papavassiliou, Phys. Rev. C78, 015207 (2008) [2] S.F. Pate, D. Trujillo, EPJ Web of Conferences 66, 06018 (2014) [3] C. Giusti and M.V. Ivanov, J. Phys. G: Nucl. Part. Phys. 47 024001 (2020) [4] L. Ren, NuFact 2021, PoS, 402, 205 (2022), 10.22323/1.402.0205 [5] S.F. Pate et al., Phys. Rev. D 109, 093001, 2024

hep-ph↗

arXiv2024

Measurement of $J/ψ$ and $ψ\left(2S\right)$ production in $p+p$ and $p+d$ interactions at 120 GeV

We report the $p+p$ and $p+d$ differential cross sections measured in the SeaQuest experiment for $J/ψ$ and $ψ\left(2S\right)$ production at 120 GeV beam energy covering the forward $x$-Feynman ($x_F$) range of $0.5 < x_F <0.9$. The measured cross sections are in good agreement with theoretical calculations based on the nonrelativistic QCD (NRQCD) using the long-distance matrix elements deduced from a recent global analysis of proton- and pion-induced charmonium production data. The $σ_{ψ\left(2S\right)} / σ_{J/ψ}$ cross section ratios are found to increase as $x_F$ increases, indicating that the $q \bar{q}$ annihilation process has larger contributions in the $ψ\left(2S\right)$ production than the $J/ψ$ production. The $σ_{pd}/2σ_{pp}$ cross section ratios are observed to be significantly different for the Drell-Yan process and $J/ψ$ production, reflecting their different production mechanisms. We find that the $σ_{pd}/2σ_{pp}$ ratios for $J/ψ$ production at the forward $x_F$ region are sensitive to the $\bar{d}/ \bar{u}$ flavor asymmetry of the proton sea, analogous to the Drell-Yan process. The transverse momentum ($p_T$) distributions for $J/ψ$ and $ψ\left(2S\right)$ production are also presented and compared with data collected at higher center-of-mass energies.

hep-ex↗

arXiv2024

Global Fit of Electron and Neutrino Elastic Scattering Data to Determine the Strange Quark Contribution to the Vector and Axial Form Factors of the Nucleon

We present a global fit of neutral-current elastic (NCE) neutrino-scattering data and parity-violating electron-scattering (PVES) data with the goal of determining the strange quark contribution to the vector and axial form factors of the proton. Previous fits of this form included data from a variety of PVES experiments (PVA4, HAPPEx, G0, SAMPLE) and the NCE neutrino and anti-neutrino data from BNL E734. These fits did not constrain the strangeness contribution to the axial form factor $G_A^s(Q^2)$ at low $Q^2$ very well because there was no NCE data for $Q^2<0.45$ GeV$^2$. Our new fit includes for the first time MiniBooNE NCE data from both neutrino and anti-neutrino scattering; this experiment used a hydrocarbon target and so a model of the neutrino interaction with the carbon nucleus was required. Three different nuclear models have been employed: a relativistic Fermi gas model, the SuperScaling Approximation model, and a spectral function model. We find a tremendous improvement in the constraint of $G_A^s(Q^2)$ at low $Q^2$ compared to previous work, although more data is needed from NCE measurements that focus on exclusive single-proton final states, for example from MicroBooNE.

hep-ph↗

arXiv2023

Estimation of Combinatoric Background in SeaQuest using an Event-Mixing Method

All experiments observing dilepton pairs (e.g. $e^+e^-$, $μ^+μ^-$) must confront the existence of a combinatoric background caused by the combining of tracks not arising from the same physics vertex. Some method must be devised to calculate and remove this background. In this document we describe a particular event-mixing method relying on many of the unique aspects of the SeaQuest spectrometer and data. The method described here calculates the combinatoric background with correct normalization; i.e., there is no need to assign a floating normalization factor that is then determined in a subsequent fitting procedure. Numerous tests are applied to demonstrate the reliability of the method.

hep-ex↗

arXiv2018

A Model for the Global Quantum Efficiency for a TPB-based Wavelength-Shifting System used with Photomultiplier Tubes in Liquid Argon in MicroBooNE

We present a model for the Global Quantum Efficiency (GQE) of the MicroBooNE optical units. An optical unit consists of a flat, circular acrylic plate, coated with tetraphenyl butadiene (TPB), positioned near the photocathode of a 20.2-cm diameter photomultiplier tube. The plate converts the ultra-violet scintillation photons from liquid argon into visible-spectrum photons to which the cryogenic phototubes are sensitive. The GQE is the convolution of the efficiency of the plates that convert the 128 nm scintillation light from liquid argon to visible light, the efficiency of the shifted light to reach the photocathode, and the efficiency of the cryogenic photomultiplier tube. We develop a GEANT4-based model of the optical unit, based on first principles, and obtain the range of probable values for the expected number of detected photoelectrons ($N_{\rm PE}$) given the known systematic errors on the simulation parameters. We compare results from four measurements of the $N_{\rm PE}$ determined using alpha-particle sources placed at two distances from a TPB-coated plate in a liquid argon cryostat test stand. We also directly measured the radial dependence of the quantum efficiency, and find that this has the same shape as predicted by our model. Our model results in a GQE of $0.0055\pm0.0009$ for the MicroBooNE optical units. While the information shown here is MicroBooNE specific, the approach to the model and the collection of simulation parameters will be widely applicable to many liquid-argon-based light collection systems.

physics.ins-det↗

arXiv2016

Convolutional Neural Networks Applied to Neutrino Events in a Liquid Argon Time Projection Chamber

We present several studies of convolutional neural networks applied to data coming from the MicroBooNE detector, a liquid argon time projection chamber (LArTPC). The algorithms studied include the classification of single particle images, the localization of single particle and neutrino interactions in an image, and the detection of a simulated neutrino event overlaid with cosmic ray backgrounds taken from real detector data. These studies demonstrate the potential of convolutional neural networks for particle identification or event detection on simulated neutrino interactions. We also address technical issues that arise when applying this technique to data from a large LArTPC at or near ground level.

physics.ins-det↗

arXiv2013

Measurement of R = sigma_L / sigma_T and the Separated Longitudinal and Transverse Structure Functions in the Nucleon Resonance Region

We report on a detailed study of longitudinal strength in the nucleon resonance region, presenting new results from inclusive electron-proton cross sections measured at Jefferson Lab Hall C in the four-momentum transfer range 0.2 < Q^2 < 5.5 GeV^2. The data have been used to accurately perform 167 Rosenbluth-type longitudinal / transverse separations. The precision R = sigma_L / sigma_T data are presented here, along with the first separate values of the inelastic structure functions F_1 and F_L in this regime. The resonance longitudinal component is found to be significant, both in magnitude and in the existence of defined mass peaks. Additionally, quark-hadron duality is here observed above Q^2 = 1 GeV^2 in the separated structure functions independently.

nucl-ex↗

arXiv2012

First Measurement of the Neutral Current Excitation of the Delta Resonance on a Proton Target

The parity-violating asymmetry arising from inelastic electron-nucleon scattering at backward angle (~95 degrees) near the Delta(1232) resonance has been measured using a hydrogen target. From this asymmetry, we extracted the axial transition form factor G^A_{NΔ}, a function of the axial Adler form factors C^A_i. Though G^A_{NΔ} has been previously studied using charged current reactions, this is the first measurement of the weak neutral current excitation of the Delta using a proton target. For Q^2 = 0.34 (GeV/c)^2 and W = 1.18 GeV, the asymmetry was measured to be -33.4 \pm (5.3)_{stat} \pm (5.1)_{sys} ppm. The value of G^A_{NΔ} determined from the hydrogen asymmetry was -0.05 \pm (0.35)_{stat} \pm (0.34)_{sys} \pm (0.06)_{theory}. These findings agree within errors with theoretical predictions for both the total asymmetry and the form factor. In addition to the hydrogen measurement, the asymmetry was measured at the same kinematics using a deuterium target. The asymmetry for deuterium was determined to be -43.6 \pm (14.6)_{stat} \pm (6.2)_{sys} ppm.

nucl-ex↗

arXiv2012

Strange Quark Contribution to the Nucleon Spin from Electroweak Elastic Scattering Data

The total contribution of strange quarks to the intrinsic spin of the nucleon can be determined from a measurement of the strange-quark contribution to the nucleon's elastic axial form factor. We have studied the strangeness contribution to the elastic vector and axial form factors of the nucleon, using elastic electroweak scattering data. Specifically, we combine elastic $νp$ and $\barν p$ scattering cross section data from the Brookhaven E734 experiment with elastic $ep$ and quasi-elastic $ed$ and $e$-$^4$He scattering parity-violating asymmetry data from the SAMPLE, HAPPEx, G0 and PVA4 experiments. We have not only determined these form factors at individual values of momentum-transfer ($Q^2$), but also have fit the $Q^2$-dependence of these form factors using simple functional forms. We present the results of these fits, along with some expectations of how our knowledge of these form factors can be improved with data from Fermilab experiments.

hep-ex↗

arXiv2012

Measurement of the parity-violating asymmetry in inclusive electroproduction of $π^-$ near the $Δ^0$ resonance

The parity-violating (PV) asymmetry of inclusive $π^-$ production in electron scattering from a liquid deuterium target was measured at backward angles. The measurement was conducted as a part of the G0 experiment, at a beam energy of 360 MeV. The physics process dominating pion production for these kinematics is quasi-free photoproduction off the neutron via the $Δ^0$ resonance. In the context of heavy-baryon chiral perturbation theory (HB$χ$PT), this asymmetry is related to a low energy constant $d_Δ^-$ that characterizes the parity-violating $γ$N$Δ$ coupling. Zhu et al. calculated $d_Δ^-$ in a model benchmarked by the large asymmetries seen in hyperon weak radiative decays, and predicted potentially large asymmetries for this process, ranging from $A_γ^-=-5.2$ to $+5.2$ ppm. The measurement performed in this work leads to $A_γ^-=-0.36\pm 1.06\pm 0.37\pm 0.03$ ppm (where sources of statistical, systematic and theoretical uncertainties are included), which would disfavor enchancements considered by Zhu et al. proportional to $V_{ud}/V_{us}$. The measurement is part of a program of inelastic scattering measurements that were conducted by the G0 experiment, seeking to determine the $N-Δ$ axial transition form-factors using PV electron scattering.

nucl-ex↗

arXiv2011

Transverse Beam Spin Asymmetries at Backward Angles in Elastic Electron-Proton and Quasi-elastic Electron-Deuteron Scattering

We have measured the beam-normal single-spin asymmetries in elastic scattering of transversely polarized electrons from the proton, and performed the first measurement in quasi-elastic scattering on the deuteron, at backward angles (lab scattering angle of 108 degrees) for Q2 = 0.22 GeV^2/c^2 and 0.63 GeV^2/c^2 at beam energies of 362 MeV and 687 MeV, respectively. The asymmetry arises due to the imaginary part of the interference of the two-photon exchange amplitude with that of single photon exchange. Results for the proton are consistent with a model calculation which includes inelastic intermediate hadronic (piN) states. An estimate of the beam-normal single-spin asymmetry for the scattering from the neutron is made using a quasi-static deuterium approximation, and is also in agreement with theory.

nucl-ex↗

arXiv2011

The G0 Experiment: Apparatus for Parity-Violating Electron Scattering Measurements at Forward and Backward Angles

In the G0 experiment, performed at Jefferson Lab, the parity-violating elastic scattering of electrons from protons and quasi-elastic scattering from deuterons is measured in order to determine the neutral weak currents of the nucleon. Asymmetries as small as 1 part per million in the scattering of a polarized electron beam are determined using a dedicated apparatus. It consists of specialized beam-monitoring and control systems, a cryogenic hydrogen (or deuterium) target, and a superconducting, toroidal magnetic spectrometer equipped with plastic scintillation and aerogel Cerenkov detectors, as well as fast readout electronics for the measurement of individual events. The overall design and performance of this experimental system is discussed.

nucl-ex↗

arXiv2010

Strange Quark Contribution to the Nucleon Spin from Electroweak Elastic Scattering Data

The total contribution of strange quarks to the intrinsic spin of the nucleon can be determined from a measurement of the strange-quark contribution to the nucleon's elastic axial form factor. We have studied the strangeness contribution to the elastic vector and axial form factors of the nucleon, using all available elastic electroweak scattering data. Specifically, we combine elastic $νp$ and $\barν p$ scattering cross section data from the Brookhaven E734 experiment with elastic $ep$ and quasi-elastic $ed$ and $e$-$^4$He scattering parity-violating asymmetry data from the SAMPLE, HAPPEx, G0 and PVA4 experiments. We have not only determined these form factors at individual values of momentum-transfer ($Q^2$), as has been done recently, but also have fit the $Q^2$-dependence of these form factors using simple functional forms. We present the results of these fits using existing data, along with some expectations of how our knowledge of these form factors can be improved with data from the MicroBooNE experiment planned at Fermilab.

hep-ex↗

arXiv2009

Renaissance of the ~1 TeV Fixed-Target Program

This document describes the physics potential of a new fixed-target program based on a ~1 TeV proton source. Two proton sources are potentially available in the future: the existing Tevatron at Fermilab, which can provide 800 GeV protons for fixed-target physics, and a possible upgrade to the SPS at CERN, called SPS+, which would produce 1 TeV protons on target. In this paper we use an example Tevatron fixed-target program to illustrate the high discovery potential possible in the charm and neutrino sectors. We highlight examples which are either unique to the program or difficult to accomplish at other venues.

hep-ex↗

arXiv2009

Terascale Physics Opportunities at a High Statistics, High Energy Neutrino Scattering Experiment: NuSOnG

This article presents the physics case for a new high-energy, ultra-high statistics neutrino scattering experiment, NuSOnG (Neutrino Scattering on Glass). This experiment uses a Tevatron-based neutrino beam to obtain over an order of magnitude higher statistics than presently available for the purely weak processes $ν_μ+e^- \to ν_μ+ e^-$ and $ν_μ+ e^- \to ν_e + μ^-$. A sample of Deep Inelastic Scattering events which is over two orders of magnitude larger than past samples will also be obtained. As a result, NuSOnG will be unique among present and planned experiments for its ability to probe neutrino couplings to Beyond the Standard Model physics. Many Beyond Standard Model theories physics predict a rich hierarchy of TeV-scale new states that can correct neutrino cross-sections, through modifications of $Zνν$ couplings, tree-level exchanges of new particles such as $Z^\prime$s, or through loop-level oblique corrections to gauge boson propagators. These corrections are generic in theories of extra dimensions, extended gauge symmetries, supersymmetry, and more. The sensitivity of NuSOnG to this new physics extends beyond 5 TeV mass scales. This article reviews these physics opportunities.

hep-ph↗

arXiv2009

QCD Precision Measurements and Structure Function Extraction at a High Statistics, High Energy Neutrino Scattering Experiment: NuSOnG

We extend the physics case for a new high-energy, ultra-high statistics neutrino scattering experiment, NuSOnG (Neutrino Scattering On Glass) to address a variety of issues including precision QCD measurements, extraction of structure functions, and the derived Parton Distribution Functions (PDFs). This experiment uses a Tevatron-based neutrino beam to obtain a sample of Deep Inelastic Scattering (DIS) events which is over two orders of magnitude larger than past samples. We outline an innovative method for fitting the structure functions using a parameterized energy shift which yields reduced systematic uncertainties. High statistics measurements, in combination with improved systematics, will enable NuSOnG to perform discerning tests of fundamental Standard Model parameters as we search for deviations which may hint of "Beyond the Standard Model" physics.

hep-ex↗

arXiv2008

Strange Quark Contribution to the Vector and Axial Form Factors of the Nucleon: Combined Analysis of G0, HAPPEx, and Brookhaven E734 Data

The strange quark contribution to the vector and axial form factors of the nucleon has been determined for momentum transfers in the range $0.45<Q^2<1.0$ GeV$^2$. The results are obtained via a combined analysis of forward-scattering, parity-violating elastic $\vec{e}p$ asymmetry data from the G0 and HAPPEx experiments at Jefferson Lab, and elastic $νp$ and $\barν p$ scattering data from Experiment 734 at Brookhaven National Laboratory. The parity-violating asymmetries measured in elastic $\vec{e}p$ scattering at forward angles establish a relationship between the strange vector form factors $G_E^s$ and $G_M^s$, with little sensitivity to the strange axial form factor $G_A^s$. On the other hand, elastic neutrino scattering at low $Q^2$ is dominated by the axial form factor, with some significant sensitivity to the vector form factors as well. Combination of the two data sets allows the simultaneous extraction of $G_E^s$, $G_M^s$, and $G_A^s$ over a significant range of $Q^2$ for the very first time. The $Q^2$-dependence of the strange axial form factor suggests that the strange quark contribution to the proton spin, $Δs$, is negative.

hep-ex↗