Update on 750 GeV diphotons from closed string states

Anchordoqui, Luis A. (Department of Physics and Astronomy, Lehman College, City University of New York, NY, 10468, USA) (Department of Physics, Graduate Center, City University of New York, NY, 10016, USA) (Department of Astrophysics, American Museum of Natural History, NY, 10024, USA) ; Antoniadis, Ignatios (LPTHE, UMR CNRS 7589, Sorbonne Universités, UPMC Paris 6, Paris, 75005, France) (Albert Einstein Center, Institute for Theoretical Physics, Bern University, Sidlerstrasse 5, Bern, CH-3012, Switzerland) ; Goldberg, Haim (Department of Physics, Northeastern University, Boston, MA, 02115, USA) ; Huang, Xing (Department of Physics, National Taiwan Normal University, Taipei, 116, Taiwan) ; Lüst, Dieter (Max-Planck-Institut für Physik, Werner-Heisenberg-Institut, München, 80805, Germany) (Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität München, München, 80333, Germany) ; Taylor, Tomasz R. (Department of Physics, Northeastern University, Boston, MA, 02115, USA)

25 May 2016

Abstract: Motivated by the recent update on LHC searches for narrow and broad resonances decaying into diphotons we reconsider the possibility that the observed peak in the invariant mass spectrum at Mγγ=750 GeV originates from a closed string (possibly axionic) excitation φ (associated with low mass scale string theory) that has a coupling with gauge kinetic terms. We reevaluate the production of φ by photon fusion to accommodate recent developments on additional contributions to relativistic light–light scattering. We also study the production of φ via gluon fusion. We show that for both a narrow and a broad resonance these two initial topologies can accommodate the excess of events, spanning a wide range of string mass scales 7≲Ms/TeV≲30 that are consistent with the experimental lower bound: Ms>7 TeV , at 95% CL. We demonstrate that for the two production processes the LHC13 data is compatible with the lack of a diphoton excess in LHC8 data within ∼1σ . We also show that if the resonance production is dominated by gluon fusion the null results on dijet searches at LHC8 further constrain the coupling strengths of φ , but without altering the range of possible string mass scales.

Published in: Physics letters B (2016)
Published by: Elsevier
DOI: 10.1016/j.physletb.2016.05.063
License: CC-BY-3.0

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