Search for new physics in final states with low transverse energy photon and missing transverse energy in proton-proton collisions at $\sqrt{s} = 8$ TeV

Abstract

Search for new physics in low-energy γ + E / T final state Designed, implemented, and commissioned the low-energy photon trigger which operated as part of the CMS "data parking"program. Led the full analysis of the 7.3 fb −1 collected by this trigger at √ s = 8 TeV, which included event selection, data driven and Monte Carlo based background estimations, sensitivity optimization, uncertainty estimation and statistical interpretation of the low photon p T and low missing transverse energy range. This is the first search at the LHC using the low-energy range of the γ + E / T final state.iv Search for new physics in high-energy γ + E / T final state Played a leading role in the analysis using full dataset collected at √ s = 8 TeV by independently performing several aspects of the analysis. The efforts included contributions to the event selection, sensitivity optimization, and uncertainty estimation. Most importantly, developed a new algorithm (MHT minimization) to reduce the contamination of events with mismeasured E / T . This algorithm led to 95% reduction of the dominant instrumental Standard Model background with > 99% signal efficiency.Search for new physics in γ γ final state Computed cross section limits using an alternative statistical technique. This required parametrization of the background and signal shapes and their uncertainty estimations, which allowed the limits to be computed for a larger number of signal mass hypotheses and the possibility to combine the results with resonance searches in different final states.Search for black holes Took part in devising the object selection, search window optimization, and estimation of various systematic uncertainties such as the uncertainty due to the choice of parton distribution functions. Service Work ActivitiesExotica Trigger Contact [2013][2014] Served as Exotica group trigger contact for the multijets, non-hadronic and lepton+jets working groups. Led the coordination of the trigger strategy for these groups for LHC Run 2. Designed and implemented the high energy single and double photon triggers in preparation for LHC Run 2. [2012][2013][2014] Developed software (new openHLT), which is widely used by trigger developers for optimization studies. Constructed the "half rate" menu which was used as the baseline for all Run 2 HLT algorithms within CMS. Contributed to large scale trigger rate studies such as pileup dependence both for the 7 TeV and 8 TeV data taking conditions. Using the data collected with the low-energy γ + / E T trigger, I conducted a search in an experimentally challenging phase space. The low-energy γ + / E T regime has never before been explored at the LHC. This phase space is particularly challenging compared to other searches because of the much larger background rate as well as the importance of understanding the systematic uncertainties, rather than the statistical uncertainty, which dominates in the high-energy regime. In this search, I have utilized multiple techniques based on control samples in data to describe various backgroun...