Searches for BSM physics in diphoton final state at CMS

Abstract

Many physics scenarios beyond the standard model predict the existence of heavy resonances decaying to diphotons. This note presents searches for BSM physics in the diphoton final state at CMS, focusing on the recent results obtained using data collected at the LHC in 2015. Presented at DIS 2016 XXIV International Workshop on Deep-Inelastic Scattering and Related Subjects Searches for BSM physics in diphoton final state at CMS Milena Quittnat∗ on behalf of the CMS collaboration ETH Zuerich E-mail: milena.quittnat@cern.ch Many physics scenarios beyond the standard model predict the existence of heavy resonances decaying to diphotons. This note presents searches for BSM physics in the diphoton final state at CMS, focusing on the recent results obtained using data collected at the LHC in 2015. XXIV International Workshop on Deep-Inelastic Scattering and Related Subjects 11-15 April, 2016 DESY Hamburg, Germany ∗Speaker. c © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). http://pos.sissa.it/ Searches for BSM physics in diphoton final state at CMS Milena Quittnat Introduction The resonant production of high mass diphoton pairs is a prediction that arises in several extensions of the standard model (SM) of particle physics. The spin of a resonance decaying to two photons must be either 0 or an integer greater than or equal to 2 [1, 2]. Spin-0 resonances decaying to two photons are predicted by SM extensions with non-minimal Higgs sectors [3], while spin-2 resonances decaying to two photons arise in models with additional space-like dimensions, namely the Randall-Sundrum (RS) graviton model [4]. Recently, the ATLAS [5] and CMS [6] collaborations reported results on searches for diphoton resonances at √ s = 13TeV, in the mass ranges 200GeV −2TeVand 500GeV −4.5 TeV, respectively. The results reported in this note are based on 3.3fb−1 of proton-proton collisions collected by the CMS experiment in 2015 at √ s = 13TeV. The results obtained on the √ s = 13TeVdataset are combined statistically with those obtained by the CMS collaboration in similar searches carried out at √ s = 8TeVand are published in [7, 8]. Event selection and reconstruction A detailed description of the CMS detector, together with the relevant kinematic variables, can be found in Ref. [9] and a description of the used simulation in Ref. [8]. In the 13TeVdatset and with B = 3.8T(B = 0T), the trigger selection requires at least two photon candidates of transverse momentum above 60 (40)GeVand is fully efficient for the search range of mX > 0.5TeV. Photons are reconstructed by clustering spatially correlated energy deposits in the ECAL, the calibrations, corrections and techniques used are described in Ref. [11]. In the search region for the 3.8 T dataset the interaction vertex is correctly assigned for about 90% of the signal events [8]. Due to a different vertex algorithm, the probability for the correct assignment is about 60% for B = 0Tdata.Corrections to account for residual differences in the photon energy scale and resolution between the data and simulation are determined using Z→ e+e− events through the procedure described in Ref. [11]. The energy scale correction factors measured for the 3.8 T data are found to be about 1% higher than the 0 T factors, while similar values are measured for the resolution corrections. The variation of the corrections in the EB (EE) region is assessed as a function of the transverse momentum pT up to 150 (100)GeVusing Z→ e+e− data, and is found to be 0.5(0.7)% or less for both the 3.8 and 0 T data. The identification and trigger efficiencies were checked and found in agreement with simulation. In each event, photon candidates are required to have pT > 75GeV and a pseudorapidity of |ηSC| 3TeV. About 90 (80) % of the back1 Searches for BSM physics in diphoton final state at CMS Milena Quittnat ground events in the EBEB (EBEE) sample arises from the γγ -process. These results, estimated from simulation, are validated for the 3.8 T analysis using the method described in Ref. [7]. E ve nt s / ( 2 0 G eV ) 1 10 2 10 Data Fit model σ 1 ± σ 2 ± EBEB (GeV) γ γ m 400 600 80