https://doi.org/10.1140/epjc/s10052-016-4127-4
Regular Article - Theoretical Physics
Photons, photon jets, and dark photons at 750 GeV and beyond
1
Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai, 400005, India
2
PRISMA Cluster of Excellence, Mainz Institute for Theoretical Physics, Johannes Gutenberg University, Staudingerweg 7, Mainz, 55099, Germany
3
DESY, Notkestrasse 85, 22607, Hamburg, Germany
* e-mail: pedro.schwaller@desy.de
Received:
22
February
2016
Accepted:
4
May
2016
Published online:
18
May
2016
In new physics searches involving photons at the LHC, one challenge is to distinguish scenarios with isolated photons from models leading to “photon jets”. For instance, in the context of the 750 GeV diphoton excess, it was pointed out that a true diphoton resonance 
can be mimicked by a process of the form 
, where S is a new scalar with a mass of 750 GeV and a is a light pseudoscalar decaying to two collinear photons. Photon jets can be distinguished from isolated photons by exploiting the fact that a large fraction of photons convert to an 
pair inside the inner detector. In this note, we quantify this discrimination power, and we study how the sensitivity of future searches differs for photon jets compared to isolated photons. We also investigate how our results depend on the lifetime of the particle(s) decaying to the photon jet. Finally, we discuss the extension to 
, where there are no photons at all but the dark photon 
decays to pairs. Our results will be useful in future studies of the putative 750 GeV signal, but also more generally in any new physics search involving hard photons.
© The Author(s), 2016
