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Article
Report number	arXiv:1206.6064 ; SLAC--PUB--15096 ; UCLA-12-TEP-103 ; CERN-PH-TH-2012-170 ; IPPP-11-42
Title	Missing Energy and Jets for Supersymmetry Searches
Author(s)	Bern, Z (UCLA) ; Diana, G (IPhT, Saclay) ; Dixon, L J (SLAC) ; Cordero, F Febres (Simon Bolivar U.) ; Hoeche, S (SLAC) ; Ita, H (UCLA ; Bohr Inst.) ; Kosower, D A (IPhT, Saclay) ; Maitre, D (CERN ; Durham U.) ; Ozeren, K J (UCLA)
Publication	2013
Imprint	27 Jun 2012
Number of pages	15
Note	Comments: 32 pages, 10 figures, 8 tables, RevTeX 32 pages, 10 figures, 8 tables, RevTeX
In:	Phys. Rev. D 87 (2013) 034026
DOI	10.1103/PhysRevD.87.034026
Subject category	Particle Physics - Phenomenology
Abstract	We extend our investigation of backgrounds to new physics signals, following CMS's data-driven search for supersymmetry at the LHC. The aim is to use different sets of cuts in gamma + 3-jet production to predict the irreducible Z + 3-jet background (with the Z boson decaying to neutrinos) to searches with missing transverse energy + 3-jet signal topologies. We compute ratios of Z + 3-jet to gamma + 3-jet production cross sections and kinematic distributions at next-to-leading order (NLO) in alpha_s. We compare these ratios with those obtained using a parton shower matched to leading-order matrix elements (ME+PS). This study extends our previous work [arXiv:1106.1423 [hep-ph]] on the Z + 2-jet to gamma + 2-jet ratio. We find excellent agreement with the ratio determined from the earlier NLO results involving two instead of three jets, and agreement to within 10% between the NLO and ME+PS results for the ratios. We also examine the possibility of large QCD logarithms in these processes. Ratios of Z + n-jet to gamma + n-jet cross sections are plausibly less sensitive to such corrections than the cross sections themselves. Their effect on estimates of Z + 3-jet to gamma + 3-jet ratios can be assessed experimentally by measuring the gamma + 3-jet to gamma + 2-jet production ratio in search regions. We partially address the question of potentially large electroweak logarithms by computing the real-emission part of the electroweak corrections to the ratio using ME+PS, and find that it is 1% or less. Our estimate of the remaining theoretical uncertainties in the Z to gamma ratio is in agreement with our earlier study.
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