Determination of the jet energy corrections for b-jets using Z+b events (JME-13-001)

Abstract

We present an estimation of residual corrections to the b-jet energy scale using data from proton-proton collisions at a centre-of-mass energy of 8 TeV recorded by the CMS detector in 2012. We consider events where a b-jet and a Z boson with leptonic decay are balanced in the transverse plane. Making use of this balance and the precise measurement of leptons in CMS, the jet energy scale is calculated using two independent methods. The correction is obtained by comparing the jet energy scale in data and Monte Carlo simulation to account for possible differences. The final correction is calculated on top of the correction inclusive to all jet flavors. We obtain a final value of C_corr = 0.998 +/- 0.004 (stat) +/- 0.004 (sys) and we conclude no additional correction is needed for the b-jet energy scale.}

List of approved figures

Figures	Caption
	Fig. 1 Z boson p_T distribution for the b-tagged (left) and inclusive (right) selections. The MC distribution is normalized to the total number of events in data.
	Fig. 1 Z boson p_T distribution for the b-tagged (left) and inclusive (right) selections. The MC distribution is normalized to the total number of events in data.
	Fig 2. R_pT (left) and R_MPF (right) distributions for the b-tagged case; the mean of this distribution is extracted for data and Monte Carlo simulation to compute the response. The MC distribution is normalized to the total number of events in data.
	Fig 2. R_pT (left) and R_MPF (right) distributions for the b-tagged case; the mean of this distribution is extracted for data and Monte Carlo simulation to compute the response. The MC distribution is normalized to the total number of events in data.
	Fig 3. The alpha distribution for the b-tagged case; the bin at zero is populated by events containing only one jet according to the selection criteria. The MC distribution is normalized to the total number of events in data.
	Fig 4. Overview of the result for C^inc (left), C^b (center), and the final result, C_corr (right), with all three cross-checks: MPF at face value (final result), MPF using a fit to extrapolate to alpha=0, R_pT (face value), and using a fit to extrapolate to \alpha=0 with R_pT. Systematic uncertainties for the b-tagged and inclusive only cases are extracted from CMS-DP-2013-033.
	Fig 4. Overview of the result for C^inc (left), C^b (center), and the final result, C_corr (right), with all three cross-checks: MPF at face value (final result), MPF using a fit to extrapolate to alpha=0, R_pT (face value), and using a fit to extrapolate to \alpha=0 with R_pT. Systematic uncertainties for the b-tagged and inclusive only cases are extracted from CMS-DP-2013-033.
	Fig 4. Overview of the result for C^inc (left), C^b (center), and the final result, C_corr (right), with all three cross-checks: MPF at face value (final result), MPF using a fit to extrapolate to alpha=0, R_pT (face value), and using a fit to extrapolate to \alpha=0 with R_pT. Systematic uncertainties for the b-tagged and inclusive only cases are extracted from CMS-DP-2013-033.
	Fig 5. Inclusive and b-tagged jet energy correction (left) and their ratio (right) as a function of Z boson momentum.
	Fig 5. Inclusive and b-tagged jet energy correction (left) and their ratio (right) as a function of Z boson momentum.

List of approved tables

	Tab 1. Summary of the measurements performed using the different methods and techniques for protecting against the secondary jet activity.\label{tab:measurements.
	Tab 2.Overview of systematic uncertainties.
	Tab 3. Summary of results obtained with the different methods for the MADGRAPH+PYTHIA MC sample. The first uncertainty is the statistical uncertainty while the second is systematic.
	Tab 4. Jet energy scale (MPF, face value) for the inclusive and b-tagged case and the final correction separately for data, MADGRAPH+PYTHIA MC and HERWIG++ MC.

-- PabloMartinez - 26 Sep 2014