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Title: Search for an Invisibly Decaying Z Boson at Belle II in e + e μ + μ ( e ± μ ) Plus Missing Energy Final States

Journal Article · · Physical Review Letters
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Theories beyond the standard model often predict the existence of an additional neutral boson, the Z0. Using data collected by the Belle II experiment during 2018 at the SuperKEKB collider, we perform the first searches for the invisible decay of a Z0 in the process eþe- → μþμ-Z0 and of a lepton-flavor-violating Z0 in eþe- → eμ∓Z0. We do not find any excess of events and set 90% credibility level upper limits on the cross sections of these processes. We translate the former, in the framework of an Lμ - Lτ theory, into upper limits on the Z0 coupling constant at the level of 5 × 10-2 – 1 for MZ0 ≤ 6 GeV=c2.

Research Organization:
Brookhaven National Laboratory (BNL), Upton, NY (United States); Carnegie Mellon Univ., Pittsburgh, PA (United States); Univ. of Hawaii, Honolulu, HI (United States)
Sponsoring Organization:
USDOE Office of Science (SC), High Energy Physics (HEP); National Science Foundation (NSF); KEK - High Energy Accelerator Research Organization
Contributing Organization:
Belle II Collaboration
Grant/Contract Number:
AC06-76RLO1830; AC06-76RL01830; SC0010118; SC0010504
OSTI ID:
1608398
Alternate ID(s):
OSTI ID: 1616433; OSTI ID: 1755603; OSTI ID: 1779499
Report Number(s):
BNL-214873-2020-JAAM; PRLTAO; 141801
Journal Information:
Physical Review Letters, Journal Name: Physical Review Letters Vol. 124 Journal Issue: 14; ISSN 0031-9007
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 43 works
Citation information provided by
Web of Science

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