近日，日本奥羽大学的Takeshi Araki与东京大学的Kento Asai以及九州大学的Hidetoshi Otono等人合作并取得一项新进展。经过不懈努力，他们揭示T2K离轴近探测器对暗光子的新约束。相关研究成果已于2023年11月10日在国际知名学术期刊《高能物理杂志》上发表。

本文探讨了ND280探测器在质子束流场中侦测介子稀有衰变及质子轫致辐射过程所产生的暗光子的能力。经过研究，发现在ND280探测器的十年运作期间，T2K成功排除了暗光子质量和动力学混合的尚未探测的参数区域。同时，研究也指出，在未来的T2K运行中，ND280有能力搜索更广阔的参数范围，以进一步探测暗光子和U(1)_B-L规范玻色子。

据悉，T2K实验是研究中微子振荡的最强大的长基线实验之一。其中，离轴近探测器ND280被安装在距离中微子产生靶下游280米的位置，旨在精确测量中微子的能谱。

附：英文原文

Title: New constraint on dark photon at T2K off-axis near detector

Author: Araki, Takeshi, Asai, Kento, Iizawa, Tomoya, Otono, Hidetoshi, Shimomura, Takashi, Takubo, Yosuke

Issue&Volume: 2023-11-10

Abstract: The T2K experiment is one of the most powerful long-baseline experiments to investigate neutrino oscillations. The off-axis near detector called ND280 is installed 280 m downstream from the neutrino production target to measure the neutrino energy spectrum. In this paper, we study the capability of the ND280 detector to search for the dark photon produced through the meson rare decay and proton bremsstrahlung processes at the proton beam dump. We find that the ten-year operation of T2K with the ND280 detector excludes the unexplored parameter region for the dark photon mass and kinetic mixing. We also show that a broader parameter region can be searched by the ND280 in the future T2K operation for dark photon as well as U(1)_B-L gauge boson.

DOI: 10.1007/JHEP11(2023)056

Source: https://link.springer.com/article/10.1007/JHEP11(2023)056