Measurement of double-differential muon neutrino charged-current interactions on C$_8$H$_8$ without pions in the final state using the T2K off-axis beam

TL;DR

This paper presents the first flux-integrated, double-differential measurement of muon neutrino charged-current interactions on carbon without pions, using the T2K off-axis beam, providing data to test nuclear interaction models.

Contribution

It introduces a novel measurement approach that avoids model-dependent corrections for pion absorption, with two robust analyses demonstrating consistency and comparison with recent theoretical models.

Findings

Measurements agree with models including nucleon-nucleon correlations.

Total cross-section measured as (0.417 ± 0.047 (syst) ± 0.005 (stat))×10^{-38} cm^2 per nucleon.

Cross-section in high-efficiency phase space region is (0.202 ± 0.0359 (syst) ± 0.0026 (stat))×10^{-38} cm^2 per nucleon.

Abstract

We report the measurement of muon neutrino charged-current interactions on carbon without pions in the final state at the T2K beam energy using 5.734$\times10^{20}$ protons on target. For the first time the measurement is reported as a flux-integrated, double-differential cross-section in muon kinematic variables ($\cos\theta_\mu$, $p_\mu$), without correcting for events where a pion is produced and then absorbed by final state interactions. Two analyses are performed with different selections, background evaluations and cross-section extraction methods to demonstrate the robustness of the results against biases due to model-dependent assumptions. The measurements compare favorably with recent models which include nucleon-nucleon correlations but, given the present precision, the measurement does not solve the degeneracy between different models. The data also agree with Monte Carlo simulations which use effective parameters that are tuned to external data to describe the nuclear effects. The total cross-section in the full phase space is $\sigma = (0.417 \pm 0.047 \text{(syst)} \pm 0.005 \text{(stat)})\times 10^{-38} \text{cm}^2$ $\text{nucleon}^{-1}$ and the cross-section integrated in the region of phase space with largest efficiency and best signal-over-background ratio ($\cos\theta_\mu>0.6$ and $p_\mu > 200$ MeV) is $\sigma = (0.202 \pm 0.0359 \text{(syst)} \pm 0.0026 \text{(stat)}) \times 10^{-38} \text{cm}^2$ $\text{nucleon}^{-1}$.