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  • Open Access

Quantum field theory in flat spacetime with multiple time directions

Bin Chen1,2,3,*, Zezhou Hu2,†, and Xin-Cheng Mao2,‡

  • 1Institute of Fundamental Physics and Quantum Technology, and School of Physical Science and Technology, Ningbo University, Ningbo, Zhejiang 315211, People’s Republic of China
  • 2School of Physics, Peking University, No.5 Yiheyuan Rd, Beijing 100871, People’s Republic of China
  • 3Center for High Energy Physics, Peking University, No.5 Yiheyuan Rd, Beijing 100871, People’s Republic of China

  • *Contact author: chenbin1@nbu.edu.cn
  • †Contact author: z.z.hu@pku.edu.cn
  • ‡Contact author: maoxc1120@stu.pku.edu.cn
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Phys. Rev. D 112, 085008 – Published 9 October, 2025

DOI: https://doi.org/10.1103/rq7p-lvq9

Abstract

This work serves as the generalization of the work [1], where we investigated the quantum field theory in Klein space which has two time directions. We extend studies to the general spacetime Rn,d−n(n,d−n≥2) in a similar manner; the “length of time” q is regarded as the evolution direction of the system and additional modes beyond the plane wave modes are introduced in the canonical quantization. We show that this novel formulation is consistent with the analytical continuation of the results in Minkowski spacetime.

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See Also

QFT in Klein space

Bin Chen, Zezhou Hu, and Xin-Cheng Mao
Phys. Rev. D 113, 085005 (2026)

Article Text

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Phys. Rev. D 112, 085008– Published 9 October, 2025
  • Received 30 June 2025
  • Accepted 25 September 2025
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