Theta in new QCD-like sectors

Patrick Draper, Jonathan Kozaczuk, Jiang Hao Yu

Research output: Contribution to journalArticlepeer-review


New QCD-like "hypercolor" sectors can generate a broad class of new signatures at hadron colliders and furnish a variety of dark matter candidates. Paired diboson resonances are a particularly important collider signature, arising both from CP-conserving vector hypermeson decays of the form ρ→ππ→4V and from CP-violating pseudoscalar hypermeson decays of the form η→ππ→4V. The latter are sensitive to the vacuum angle θ in the hypercolor sector. We study single- and paired-diboson resonance signatures in final states involving gluons and photons at the LHC and a future 100 TeV pp collider, illustrating the discovery potential at both colliders in simple benchmark models. We also describe some of the theoretical and cosmological consequences of θ. If CP-violating hypermeson decays are observable at hadron colliders, ordinary QCD must have an axion. Such scenarios also provide a natural setting for a dark pion component of dark matter, with its relic abundance set by CP-violating annihilations. If the new vacuum angle is relaxed to zero by a dark axion, the relic density can instead be a mixture of axions and dark axions. Overproduction of dark axions is most easily avoided if the Universe underwent a period of early matter domination.

Original languageEnglish (US)
Article number015028
JournalPhysical Review D
Issue number1
StatePublished - Jul 1 2018
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


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