Sum-rule constraints on possible diphoton resonances at LHC

Abstract

The study of the forward scattering amplitude $V(k,λ) V(k'λ')\to V(k,λ) V(k',λ')$ of real massless gauge bosons $V$, e.g. photons or gluons, leads to a sum-rule that can be used to investigate beyond the Standard Model signals at LHC in the $γγ$ channel. The sum-rule only relies on general properties such as analyticity, unitarity and crossing. We use the now buried 750 GeV diphoton resonance as a case of study to exemplify the constraints that the forward sum-rule requires to any new physics candidate. In the case of a large $γγ$ or $gg$ partial width, of the order of 10 GeV in our 750 GeV analysis, one finds that an infinite tower of states with spin $J_R=2$ and higher must be ultimately incorporated to the beyond Standard Model theory in order to fulfill the sum-rule. We expect these techniques may be useful in next diphoton searches at LHC and future colliders.

Parallel talk at the XII Quark Confinement and the Hadron Spectrum Conference (CONF12), Thessaloniki, Greece, 29 August - 3 September, 2016; 9 pages, 1 eps figure