학술논문
First measurement of the strange axial coupling constant using neutral-current quasielastic interactions of atmospheric neutrinos at KamLAND
Document Type
Working Paper
Author
KamLAND Collaboration; Abe, S.; Asami, S.; Eizuka, M.; Futagi, S.; Gando, A.; Gando, Y.; Gima, T.; Goto, A.; Hachiya, T.; Hata, K.; Ichimura, K.; Ieki, S.; Ikeda, H.; Inoue, K.; Ishidoshiro, K.; Kamei, Y.; Kawada, N.; Kishimoto, Y.; Koga, M.; Kurasawa, M.; Mitsui, T.; Miyake, H.; Nakahata, T.; Nakamura, K.; Nakamura, R.; Ozaki, H.; Sakai, T.; Shimizu, I.; Shirai, J.; Shiraishi, K.; Suzuki, A.; Suzuki, Y.; Takeuchi, A.; Tamae, K.; Watanabe, H.; Yoshida, Y.; Obara, S.; Ichikawa, A. K.; Yoshida, S.; Umehara, S.; Fushimi, K.; Kotera, K.; Urano, Y.; Berger, B. E.; Fujikawa, B. K.; Learned, J. G.; Maricic, J.; Axani, S. N.; Fu, Z.; Smolsky, J.; Winslow, L. A.; Efremenko, Y.; Karwowski, H. J.; Markoff, D. M.; Tornow, W.; Detwiler, J. A.; Enomoto, S.; Decowski, M. P.; Grant, C.; Li, A.; Song, H.; Dell'Oro, S.; O'Donnell, T.
Source
Phys. Rev. D 107,072006 (2023)
Subject
Language
Abstract
We report a measurement of the strange axial coupling constant $g_A^s$ using atmospheric neutrino data at KamLAND. This constant is a component of the axial form factor of the neutral-current quasielastic (NCQE) interaction. The value of $g_A^s$ significantly changes the ratio of proton and neutron NCQE cross sections. KamLAND is suitable for measuring NCQE interactions as it can detect nucleon recoils with low-energy thresholds and measure neutron multiplicity with high efficiency. KamLAND data, including the information on neutron multiplicity associated with the NCQE interactions, makes it possible to measure $g_A^s$ with a suppressed dependence on the axial mass $M_A$, which has not yet been determined. For a comprehensive prediction of the neutron emission associated with neutrino interactions, we establish a simulation of particle emission via nuclear deexcitation of $^{12}$C, a process not considered in existing neutrino Monte Carlo event generators. Energy spectrum fitting for each neutron multiplicity gives $g_A^s =-0.14^{+0.25}_{-0.26}$, which is the most stringent limit obtained using NCQE interactions without $M_A$ constraints. The two-body current contribution considered in this analysis relies on a theoretically effective model and electron scattering experiments and requires future verification by direct measurements and future model improvement.