On the interpretation of a possible ∼ 750 GeV particle decaying into γγ

TY - JOUR

T1 - On the interpretation of a possible ∼ 750 GeV particle decaying into γγ

AU - Ellis, John

AU - Ellis, Sebastian A R

AU - Quevillon, Jeremie

AU - Sanz, Verónica

AU - You, Tevong

PY - 2016/3/25

Y1 - 2016/3/25

N2 - We consider interpretations of the recent ∼ 3σ reports by the CMS and ATLAS collaborations of a possible X (∼750 GeV) state decaying into γγ final states. We focus on the possibilities that this is a scalar or pseudoscalar electroweak isoscalar state produced by gluon-gluon fusion mediated by loops of heavy fermions. We consider several models for these fermions, including a single vector-like charge 2/3 T quark, a doublet of vector-like quarks (T, B), and a vector-like generation of quarks, with or without leptons that also contribute to the X → γγ decay amplitude. We also consider the possibility that X (750) is a dark matter mediator, with a neutral vector-like dark matter particle. These scenarios are compatible with the present and prospective direct limits on vector-like fermions from LHC Runs 1 and 2, as well as indirect constraints from electroweak precision measurements, and we show that the required Yukawa-like couplings between the X particle and the heavy vector-like fermions are small enough to be perturbative so long as the X particle has dominant decay modes into gg and γγ. The decays X → ZZ, Zγ and W+W− are interesting prospective signatures that may help distinguish between different vector-like fermion scenarios.

AB - We consider interpretations of the recent ∼ 3σ reports by the CMS and ATLAS collaborations of a possible X (∼750 GeV) state decaying into γγ final states. We focus on the possibilities that this is a scalar or pseudoscalar electroweak isoscalar state produced by gluon-gluon fusion mediated by loops of heavy fermions. We consider several models for these fermions, including a single vector-like charge 2/3 T quark, a doublet of vector-like quarks (T, B), and a vector-like generation of quarks, with or without leptons that also contribute to the X → γγ decay amplitude. We also consider the possibility that X (750) is a dark matter mediator, with a neutral vector-like dark matter particle. These scenarios are compatible with the present and prospective direct limits on vector-like fermions from LHC Runs 1 and 2, as well as indirect constraints from electroweak precision measurements, and we show that the required Yukawa-like couplings between the X particle and the heavy vector-like fermions are small enough to be perturbative so long as the X particle has dominant decay modes into gg and γγ. The decays X → ZZ, Zγ and W+W− are interesting prospective signatures that may help distinguish between different vector-like fermion scenarios.

KW - Beyond Standard Model

KW - Higgs Physics

KW - Technicolor and Composite Models

UR - http://www.scopus.com/inward/record.url?scp=84962016856&partnerID=8YFLogxK

U2 - 10.1007/JHEP03(2016)176

DO - 10.1007/JHEP03(2016)176

M3 - Article

AN - SCOPUS:84962016856

SN - 1126-6708

VL - 2016

JO - Journal of High Energy Physics

JF - Journal of High Energy Physics

IS - 3

M1 - 176

ER -