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Scattering of high energy particles from nucleons probes their structure, as was done in the experiments that established the non-zero size of the proton using electron beams 1 . The use of charged leptons as scattering probes enables measuring the distribution of electric charges, which is encoded in the vector form factors of the nucleon 2 . Scattering weakly interacting neutrinos gives the opportunity to measure both vector and axial vector form factors of the nucleon, providing an additional, complementary probe of their structure. The nucleon transition axial form factor, F A , can be measured from neutrino scattering from free nucleons, ν μ n  →  μ − p and ν ¯ μ p → μ + n , as a function of the negative four-momentum transfer squared ( Q 2 ). Up to now, F A ( Q 2 ) has been extracted from the bound nucleons in neutrino–deuterium scattering 3 – 9 , which requires uncertain nuclear corrections 10 . Here we report the first high-statistics measurement, to our knowledge, of the ν ¯ μ p → μ + n cross-section from the hydrogen atom, using the plastic scintillator target of the MINERvA 11 experiment, extracting F A from free proton targets and measuring the nucleon axial charge radius, r A , to be 0.73 ± 0.17 fm. The antineutrino–hydrogen scattering presented here can access the axial form factor without the need for nuclear theory corrections, and enables direct comparisons with the increasingly precise lattice quantum chromodynamics computations 12 – 15 . Finally, the tools developed for this analysis and the result presented are substantial advancements in our capabilities to understand the nucleon structure in the weak sector, and also help the current and future neutrino oscillation experiments 16 – 20 to better constrain neutrino interaction models. The authors measure the nucleon axial vector form factor, which encodes information on the distribution of the nucleon weak charge, through antineutrino–proton scattering.

We present new measurements of the analyzing power AN in proton-proton elastic scattering in the Coulomb-Nuclear Interference region at √s 7.7 and 21.7 GeV obtained with the polarized atomic hydrogen jet target at RHIC. These measurements complement our earlier results at √s 6.8 and 13.7 GeV confirming the presence of a hadronic helicity flip amplitude contribution in proton-proton elastic scattering at lower energies (√s <8 GeV) while higher energy data (√s >13 GeV) are consistent with no hadronic helicity flip contribution.

Measurements of multiplicity and transverse momentum fluctuations of charged particles were performed in inelastic p+p interactions at 20, 31, 40, 80, and 158  GeV / c beam momentum. Results for the scaled variance of the multiplicity distribution and for three strongly intensive measures of multiplicity and transverse momentum fluctuations Δ [ P T , N ] , Σ [ P T , N ] and Φ p T are presented. For the first time the results on fluctuations are fully corrected for experimental biases. The results on multiplicity and transverse momentum fluctuations significantly deviate from expectations for the independent particle production. They also depend on charges of selected hadrons. The string-resonance Monte Carlo models Epos and U r qmd do not describe the data. The scaled variance of multiplicity fluctuations is significantly higher in inelastic p+p interactions than in central Pb+Pb collisions measured by NA49 at the same energy per nucleon. This is in qualitative disagreement with the predictions of the Wounded Nucleon Model. Within the statistical framework the enhanced multiplicity fluctuations in inelastic p+p interactions can be interpreted as due to event-by-event fluctuations of the fireball energy and/or volume.

The production of$\\Xi (1321)^{-}$and$\\overline{\\Xi }(1321)^{+}$hyperons in inelastic p+p interactions is studied in a fixed target experiment at a beam momentum of 158  $\\hbox {Ge}\\hbox {V}\\!/\\!c$ . Double differential distributions in rapidity${y}$and transverse momentum$p_{T}$are obtained from a sample of 33M inelastic events. They allow to extrapolate the spectra to full phase space and to determine the mean multiplicity of both${\\Xi }{^-} $and$\\overline{\\Xi }{^+} $ . The rapidity and transverse momentum spectra are compared to transport model predictions. The${\\Xi }{^-} $mean multiplicity in inelastic p+p interactions at 158  $\\hbox {Ge}\\hbox {V}\\!/\\!c$is used to quantify the strangeness enhancement in A+A collisions at the same centre-of-mass energy per nucleon pair.

The measurement of$K^{*}(892)^0$resonance production via its$K^{+}\\pi ^{-}$decay mode in inelastic p+p collisions at beam momentum 158  $\\text{ Ge }\\text{ V }\\!/\\!c$( $\\sqrt{s_{NN}}=17.3$   $\\text{ Ge }\\text{ V }$ ) is presented. The data were recorded by the NA61/SHINE hadron spectrometer at the CERN Super Proton Synchrotron. The template method was used to extract the$K^{*}(892)^0$signal and double-differential transverse momentum and rapidity spectra were obtained. The full phase-space mean multiplicity of$K^{*}(892)^0$mesons was found to be$(78.44 \\pm 0.38 \\mathrm {(stat)} \\pm 6.0 \\mathrm {(sys)) \\cdot 10^{-3}}$ . The NA61/SHINEresults are compared with the Epos1.99 and Hadron Resonance Gas models as well as with world data from p+p and nucleus–nucleus collisions.

A measurement of charged hadron pair correlations in two-dimensionalΔ η Δ φ   space is presented. The analysis is based on total 30 million central Be + Be collisions observed in the NA61/SHINE detector at the CERN SPS for incident beam momenta of 19A, 30A, 40A, 75A, and 150A  \\text Ge \\text V/c . Measurements were carried out for unlike-sign and like-sign charge hadron pairs independently. TheC(Δ η ,Δ φ )correlation functions were compared with results from a similar analysis on p + p interactions at similar beam momenta per nucleon. General trends of the back-to-back correlations are similar in central Be + Be collisions and p + p interactions, but are suppressed in magnitude due to the increased combinatorial background. Predictions from the Epos and UrQMD models are compared to the measurements. Evolution of an enhancement around(Δ η ,Δ φ ) = (0,0)with incident energy is observed in central Be + Be collisions. It is not predicted by both models and almost non-existing in proton–proton collisions at the same momentum per nucleon.

Scintillating fibers are widely used in particle detectors, mainly for tracking. We have studied the properties and have compared the performance of different blue-emitting 250~\\(\\mu\\)m diameter round double-clad scintillating fibers from Kuraray and Saint-Gobain. Here we focus on the properties of the fibers over short lengths (\\(< 50~{\\rm cm}\\)), in particular on their timing performances. We report on the light yield and attenuation, scintillation light decay time and the achievable time resolution.

Abstract The T2K experiment presents new measurements of neutrino oscillation parameters using$$19.7(16.3)\\times 10^{20}$$19.7 ( 16.3 ) × 10 20 protons on target (POT) in (anti-)neutrino mode at the far detector (FD). Compared to the previous analysis, an additional$$4.7\\times 10^{20}$$4.7 × 10 20 POT neutrino data was collected at the FD. Significant improvements were made to the analysis methodology, with the near-detector analysis introducing new selections and using more than double the data. Additionally, this is the first T2K oscillation analysis to use NA61/SHINE data on a replica of the T2K target to tune the neutrino flux model, and the neutrino interaction model was improved to include new nuclear effects and calculations. Frequentist and Bayesian analyses are presented, including results on$$\\sin ^2\\theta _{13}$$sin 2 θ 13 and the impact of priors on the$$\\delta _{\\textrm{CP}}$$δ CP measurement. Both analyses prefer the normal mass ordering and upper octant of$$\\sin ^2\\theta _{23}$$sin 2 θ 23 with a nearly maximally CP-violating phase. Assuming the normal ordering and using the constraint on$$\\sin ^2\\theta _{13}$$sin 2 θ 13 from reactors,$$\\sin ^2\\theta _{23}=0.561^{+0.021}_{-0.032}$$sin 2 θ 23 = 0 . 561 - 0.032 + 0.021 using Feldman–Cousins corrected intervals, and$$\\varDelta {}m^2_{32}=2.494_{-0.058}^{+0.041}\\times 10^{-3}~\\text {eV}^2$$Δ m 32 2 = 2 . 494 - 0.058 + 0.041 × 10 - 3 eV 2 using constant$$\\varDelta \\chi ^{2}$$Δ χ 2 intervals. The CP-violating phase is constrained to$$\\delta _{\\textrm{CP}}=-1.97_{-0.70}^{+0.97}$$δ CP = - 1 . 97 - 0.70 + 0.97 using Feldman–Cousins corrected intervals, and$$\\delta _{\\textrm{CP}}=0,\\pi $$δ CP = 0 , π is excluded at more than 90% confidence level. A Jarlskog invariant of zero is excluded at more than$$2\\sigma $$2 σ credible level using a flat prior in$$\\delta _{\\textrm{CP}},$$δ CP , and just below$$2\\sigma $$2 σ using a flat prior in$$\\sin \\delta _{\\textrm{CP}}.$$sin δ CP . When the external constraint on$$\\sin ^2\\theta _{13}$$sin 2 θ 13 is removed,$$\\sin ^2\\theta _{13}=28.0^{+2.8}_{-6.5}\\times 10^{-3},$$sin 2 θ 13 = 28 . 0 - 6.5 + 2.8 × 10 - 3 , in agreement with measurements from reactor experiments. These results are consistent with previous T2K analyses.

Measurements of inclusive spectra and mean multiplicities ofπ ^(±) , K ^(±) , p and\\̄text pproduced in inelastic p + p interactions at incident projectile momenta of 20, 31, 40, 80 and 158 \\text{ GeV }{/}{c}(√s̅ = 6.3, 7.7, 8.8, 12.3 and 17.3 \\text{ GeV }{}{,} respectively) were performed at the CERN Super Proton Synchrotron using the large acceptance NA61/SHINE hadron spectrometer. Spectra are presented as function of rapidity and transverse momentum and are compared to predictions of current models. The measurements serve as the baseline in the NA61/SHINE study of the properties of the onset of deconfinement and search for the critical point of strongly interacting matter.