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Title: Diphotons, new vacuum angles, and strong CP

The Standard Model contains a well-understood, natural, spin-0 diphoton resonance: the π0. Numerous studies have pointed out that the hint of a new diphoton resonance at 750 GeV could be a pion analog, identified with the pseudo-Nambu-Goldstone boson of a chiral symmetry spontaneously broken by new strong dynamics at the TeV scale. These “hypercolor” models are generically expected to violate parity through a topological angle θ~. We discuss the physics of θ~ and its impact on the phenomenology of the new sector. We also describe some of the theoretical implications of a nonzero θ~. In particular, θ~ can generate an O(1) threshold correction to the QCD vacuum angle θ near the TeV scale, sharply constraining ultraviolet solutions to the strong CP problem. Furthermore, finding that θ~ is small may be interpreted as evidence in favor of UV solutions to strong CP, particularly those based on spontaneously broken P or CP symmetries.
 [1] ;  [2]
  1. Univ. of California Santa Barbara, Santa Barbara, CA (United States)
  2. Univ. of Washington, Seattle, WA (United States)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of High Energy Physics (Online)
Additional Journal Information:
Journal Name: Journal of High Energy Physics (Online); Journal Volume: 2016; Journal Issue: 4; Journal ID: ISSN 1029-8479
Springer Berlin
Research Org:
Univ. of Washington, Seattle, WA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS Beyond Standard Model; chiral Langrangians; CP violation