Diphotons, new vacuum angles, and strong CP
The Standard Model contains a wellunderstood, natural, spin0 diphoton resonance: the π ^{0}. Numerous studies have pointed out that the hint of a new diphoton resonance at 750 GeV could be a pion analog, identified with the pseudoNambuGoldstone 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.
 Authors:

^{[1]};
^{[2]}
 Univ. of California Santa Barbara, Santa Barbara, CA (United States)
 Univ. of Washington, Seattle, WA (United States)
 Publication Date:
 Grant/Contract Number:
 SC0011637
 Type:
 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 10298479
 Publisher:
 Springer Berlin
 Research Org:
 Univ. of Washington, Seattle, WA (United States)
 Sponsoring Org:
 USDOE Office of Science (SC)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Beyond Standard Model; chiral Langrangians; CP violation
 OSTI Identifier:
 1326971
Draper, Patrick, and McKeen, David. Diphotons, new vacuum angles, and strong CP. United States: N. p.,
Web. doi:10.1007/JHEP04(2016)127.
Draper, Patrick, & McKeen, David. Diphotons, new vacuum angles, and strong CP. United States. doi:10.1007/JHEP04(2016)127.
Draper, Patrick, and McKeen, David. 2016.
"Diphotons, new vacuum angles, and strong CP". United States.
doi:10.1007/JHEP04(2016)127. https://www.osti.gov/servlets/purl/1326971.
@article{osti_1326971,
title = {Diphotons, new vacuum angles, and strong CP},
author = {Draper, Patrick and McKeen, David},
abstractNote = {The Standard Model contains a wellunderstood, natural, spin0 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 pseudoNambuGoldstone 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.},
doi = {10.1007/JHEP04(2016)127},
journal = {Journal of High Energy Physics (Online)},
number = 4,
volume = 2016,
place = {United States},
year = {2016},
month = {4}
}