Accelerator Neutrinos

Abstract:

We report the measurement of the triple-differential cross section d 3 σ / d E vis d cos ( θ μ ) d P μ for inclusive muon-neutrino charged-current scattering on argon. This measurement utilizes data from 6.4 × 10 20 protons on target of exposure collected using the MicroBooNE liquid argon time projection chamber located along the Fermilab Booster Neutrino Beam with a mean neutrino energy of approximately 0.8 GeV. The mapping from reconstructed kinematics to truth quantities is validated within uncertainties by comparing the distribution of reconstructed hadronic energy in data to that of the model prediction in different muon scattering angle bins after applying a conditional constraint from the muon momentum distribution in data. The success of this validation provides confidence that the energy transfer in the MicroBooNE detector is well-modeled within simulation uncertainties, enabling a reliable unfolding to a triple-differential cross section defined at the nominal neutrino flux over muon momentum, muon scattering angle, and visible neutrino energy. This validation not only supports accurate cross-section extraction, but also establishes a critical foundation for tuning interaction models used in future neutrino oscillation measurements. The unfolded measurement covers an extensive phase space, providing a wealth of information useful for future liquid argon time projection chamber experiments measuring neutrino oscillations. Comparisons against a number of commonly used model predictions are included and their performance in different parts of the available phase-space is discussed.

Abstract:

Since its first observation in the 1970s, neutrino-induced neutral-current single positive pion production ( $\mathrm{NC}1{\pi }^{+}$ ) has remained an elusive and poorly understood interaction channel. This process is a significant background in neutrino oscillation experiments and studying it further is critical for the physics program of next-generation accelerator-based neutrino oscillation experiments. In this Letter, we present the first double-differential cross-section measurement of $\mathrm{NC}1{\pi }^{+}$ interactions using data from the ND280 detector of the T2K experiment collected in $\nu$ -beam mode. The measured flux-averaged integrated cross section is $\sigma =(6.07\pm 1.22)\times {10}^{-41}{\mathrm{cm}}^2/\text{nucleon}$ . We compare the results on a hydrocarbon target to the predictions of several neutrino interaction generators and final-state-interaction models. While model predictions agree with the differential results, the data show a weak preference for a cross-section normalization approximately 30% higher than predicted by most models studied in this Letter.

Abstract:

The T2K Collaboration presents the first measurement of electron neutrino-induced charged-current pion production on a predominantly carbon target in a restricted kinematical phase space. This is performed using data from the 2.5° off-axis near detector, ND280. The differential cross sections with respect to the outgoing electron and pion kinematics, in addition to the total flux-integrated cross section, are obtained. Comparisons between the measured and predicted cross-section results using the eut, enie, and uro Monte Carlo event generators are presented. The measured total flux-integrated cross section is $[2.52\pm 0.52(\mathrm{stat})\pm 0.30(\mathrm{syst})]\times {10}^{-39}{\mathrm{cm}}^2{\text{nucleon}}^{-1}$ , which is lower than the event generator predictions.

Abstract:

The CP properties of the Higgs boson are studied in the vector-boson fusion production mode. The analysis exploits the decay mode of the Higgs boson into two τ-leptons using 140 fb−1 of proton-proton collision data at s=13 TeV collected by the ATLAS experiment at the Large Hadron Collider. Results are obtained using the Optimal Observable method. CP-violating interactions between the Higgs boson and electroweak gauge bosons are considered in the effective field theory framework, with the interaction strength described in the HISZ basis by d~, and in the Warsaw basis by cHW~, cHB~, and cHW~B. No deviations relative to the Standard Model are observed, and limits are obtained on the strength parameters. The d~ parameter is constrained to the interval [−0.012, 0.044] at the 95% confidence level while cHW~ is constrained to [−0.24, 0.83], when considering both linear and quadratic effects of physics beyond the Standard Model.