Title: String consistency, heavy exotics, and the 750 GeV diphoton excess at the LHC

Abstract

String consistency conditions are stronger than anomaly cancellation and can require the addition of exotics in the visible sector. We study such exotics and demonstrate that they may account for the modest excess at 750 GeV in recent diphoton resonance searches performed by the ATLAS and CMS collaborations. In a previous analysis of type II MSSM D‐brane quivers we systematically added up to five exotics for the sake of satisfying string consistency conditions. Using this dataset, we demonstrate that 89780 of the 89964 quivers have exotics, 78155 of which include singlets that may couple to MSSM or exotic multiplets with coupling structures governed by U (1) symmetries that are often anomalous. We demonstrate that certain sets of exotics are far preferred over others and study the structure of singlet couplings to heavy exotics carrying standard model charges. Typical possibilities include singlets that may decay to vector‐like quarks and/or vector‐like leptons and subsequently to two photons. We show that a narrow width diphoton excess can be accounted for while evading existing bounds if multiple exotics are added, with vector‐like leptons of mass GeV and vector‐like quarks with masses up to ≃ 3 TeV. However, a large width , as suggested bymore » the ATLAS data, cannot be easily accommodated in this framework. Renormalization group equations with GUT‐scale boundary conditions show that these supersymmetric models are perturbative and stable. Type IIA compactifications on toroidal orbifolds allow for O (10) Yukawa couplings in the ultraviolet. We also discuss the possibility of accounting for the diphoton excess in a low string scale scenario via the decay of string axions.« less

Authors:

Cvetič, Mirjam ^[1]; Halverson, James ^[2]; Langacker, Paul ^[3]

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+ Show Author Affiliations

1. Department of Physics and Astronomy University of Pennsylvania Philadelphia PA 19104‐6396 USA, Center for Applied Mathematics and Theoretical Physics University of Maribor Maribor Slovenia
2. Department of Physics Northeastern University Boston MA 02115‐5000 USA
3. School of Natural Science Institute for Advanced Study Einstein Drive Princeton NJ 08540 USA, Department of Physics Princeton University Princeton NJ 08544 USA

Publication Date:

Tue Aug 23 00:00:00 EDT 2016

Sponsoring Org.:

USDOE

OSTI Identifier:

1401006

Grant/Contract Number:  

DE‐SC0013528

Resource Type:

Publisher's Accepted Manuscript

Journal Name:

Fortschritte der Physik

Additional Journal Information:

Journal Name: Fortschritte der Physik Journal Volume: 64 Journal Issue: 10; Journal ID: ISSN 0015-8208

Publisher:

Wiley Blackwell (John Wiley & Sons)

Country of Publication:

Germany

Language:

English