Measurement
of W(->lv)+charm Production Cross-Section
with SLTmu c-tagging
![]()
The
previous results with the old kinematic cuts on the charm quark
The Analysis:
|
In this analysis we measure the W(->lv)+charm production cross section using lepton + 1 & 2jets events. In the lepton plus jets events resulting from the W+charm production, we look for events that the W boson decays semileptonically to an electron/muon plus neutrino (taus are not included) and the charm decays semileptonically to muons, resulting in a topology of one high-Pt electron or muon (referred as Tight Lepton, TL), missing transverse energy and one charm jet, where the lepton from the W decay and the muon from the charm semileptonic decay have opposite signs. The charm jet is tagged by the Soft Muon Tagger (SLT). We require 0 or 1 generic jet other than the charm jet to maximize the statistic power. The charge anti-correlation in the W(->lv)+charm events gives a large charge asymmetry in the Wc sample. The charge asymmetry is defined as [N(OS)-N(SS)]/[N(OS)+N(SS)], where N(OS) is the number of the opposite sign events and N(SS) is the number of the same sign events. We found the charge asymmetry is 0.720+/-0.011 from Alpgen Monte Carlo W(->lv)+charm samples. The MC sample has requirements of charm pT>20GeV and pseudorapidity of charm within [-1.5,1.5]. The backgrouonds of this analysis include QCD production of W+jets, Non-W events and DY events. They have smaller charge asymmetries except DY events. This analysis first counts in data sample the difference between the number of opposite sign events and the number of same sign events, i.e. N(OS)-N(SS). The background events are then properly deducted. The acceptance of the signal events (opposite sign minus same sign events) is determined from MC sample to be (0.833+/- 0.010)x10-2, including the charge asymmetry implicitly. The measurement is based on 1.8 fb-1 of proton-antiproton collision data, the measured Wc cross section is
sigma_{Wc}(ptc>20 GeV ,
|eta|<1.5)*BR(W->e nu) where the first uncertainty is statistical, the second is systematic and the last is uncertainty from the luminosity uncertainty.
|
SLTm tagger
& c-tagging |
||
|
|
Systematic Uncertainty Table. |
|
|
|
||
|
|
The pT distribution of SLT tagged muon. |
|
|
|
||
|
|
|
|
|
|
The SLT pT relative to
the SLT tagged jet axis.
|
|
Signed impact parameter.
|
||
|
Track multiplicity of the SLT tagged jet. |
||
|
|
Uncorrected jet energy of the SLT tagged
jet. |
|
|
|
SLTm efficiency for the central muon detector (CMUP) as a function of pT measure from JPsi & Z0 | |
|
|
SLTm efficiency for the extended muon
detector (CMX) as a function of pT measure from JPsi & Z0 |
![]()

Last Updated : Wednesday, 11/02/2007, 11:21pm by Xiaojian