Implications of the diphoton excess on left–right models and gauge unification

Frank F Deppisch,Chandan Hati,Prativa Pritimita,Utpal Sarkar,Sudhanwa Patra

doi:10.1016/j.physletb.2016.03.081

Abstract

The recent diphoton excess signal at an invariant mass of 750 GeV can be interpreted in the framework of left-right symmetric models with additional scalar singlets and vector-like fermions. We propose a minimal scenario for such a purpose. Extending the LRSM framework to include these new vector-like fermionic fields, on the other hand, results in interesting phenomenological implications for the LRSM fermion masses and mixing. Furthermore, existence of such vector-like fermions can also have interesting implications for baryogenesis and the dark matter sector. The introduction of a real bi-triplet scalar which contains a potential DM candidate will allow the gauge couplings to unify at $\approx 10^{17.7}$ GeV.

Highlights

The CMS and ATLAS Collaborations have recently reported a roughly 3σ excess in the diphoton channel at an invariant mass of about 750 GeV in the first 3 fb−1 of collected data from Run 2 of the LHC at 13 TeV [1,2]
A large number of interpretations of the diphoton signal in terms of physics beyond the Standard Model have been proposed in the literature [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136]
We explore the possibility of extending the standard Left–Right Symmetric Model (LRSM) framework with vector-like fermions and singlet scalars which can explain the diphoton signal

Summary

Introduction

The CMS and ATLAS Collaborations have recently reported a roughly 3σ excess in the diphoton channel at an invariant mass of about 750 GeV in the first 3 fb−1 of collected data from Run 2 of the LHC at 13 TeV [1,2]. The observation of the γ γ resonance at 750 GeV (much greater than the electroweak symmetry breaking scale) hints towards the existence of vector-like fermions around that mass scale Given that both the ATLAS and CMS Collaborations have suggested signal events consistent with each other at a tempting 3σ statistical significance level, hinting towards a new physics scenario, it is important to explore the possible model framework that can naturally accommodate such vector-like fermions. We explore the possibility of extending the standard LRSM framework with vector-like fermions and singlet scalars which can explain the diphoton signal Adding such new vectorlike fermionic fields, on the other hand, results in interesting phenomenological implications for the LRSM fermion masses and mixing.

Left–right symmetric model framework

Diphoton signal from a scalar resonance

Gauge coupling unification

Implications for baryogenesis and dark matter

Conclusions