eff. determination WANG Zheng Mar. 2008

Feb.2008WANG Zheng2 The method  Eff. Determined from MC sample.  Eff. Determined from data. Object id/efficiency: Data Driven methods (Tag and Probe). The eff. Factorization. s We try our best to determine eff. by method 2. eff determined by method 1 also need to be corrected or introduce error sys. error. by method 2

Feb.2008WANG Zheng3 Eff. From MC sample  N(B + obs ): Fit the Inv. mass of J/  and K spec., subtracting the background.  Br(B +  J/  K + )=(1.008  0.035)×10 -3 ; Br(J/  )=(5.93  0.06)×10 -2 ;  L: Int. luminosity.   tri = N pass HLT / N init.   sel : B meson reconstruction efficiency after the corrections. (35%)

Feb.2008WANG Zheng4  Efficiency can be divided into two parts: trigger eff. and acceptance; B meson reconstruction eff.  The first eff. is B meson Pt dependent, while the later in Pt independent. CDF|

Feb.2008WANG Zheng5 Eff. In trigger. L1L2L3

Feb.2008WANG Zheng6 Muon eff. Global MuonStandalone Muon

Feb.2008WANG Zheng7 Trigger efficiency VS B Pt

Feb.2008WANG Zheng8 Diff. cross section at LHC The detector acceptances in different Pt bin here have stat. errors from 6.0% to 18.6% because the limited sample we used.

Feb.2008WANG Zheng9 The diff. cross section at LHC Errors only include the stat. errors of trigger eff. determination and observed B meson number.

Feb.2008WANG Zheng10 Eff. Determination from Data Firstly, We must factorize the efficiency, for this measurement:

Feb.2008WANG Zheng11 Tag and probe  Relies on a special decay channel (such as Z  ee, J/  ?) to provide an unbiased, high-purity sample with which to measure the eff. of a particular cut or trigger  including the bg to analysis.  In Z  ee, a single electron trigger sample is used, from which a subset of di-electron events are selected.  The tight criteria imposed on the tag coupled with the inv. Mass requirement is sufficient to ensure high electron purity.  The Probe criteria will vary depending in the specifics of the efficiency that is being measured and how the overall efficiency has been factorized.  Present the validation of the tools by comparing the eff. obtained by them with that expected from MC truth information.

Feb.2008WANG Zheng12 A "tag" is a well identified muon. The existing of a tag muon usually indicates the existence of the other leg from the same Z. A "probe" is a standalone or tracker track that is likely from the other muon coming from the Z. Classify the probe candidates into five disjoint categories. The first type of probe is the one that also meets the criteria to be a tag candidate. This type of probe is labeled a ``G'' for gloden. The second type of probe is the one that is identified as a global muon, but does not satisfy the golden criteria to be a tag candidate. It is labeled as ``M'' for matched. The third type of probe is a standalone (tracker) muon that has a corresponding tracker (standalone) muon in a small window around it. When a pair of standalone and tracker candidates does not constitute a global muon, it contributes to the ``matching'' inefficiency, and the probe is labeled as ``U'' for unmatched. If there is no standalone muon counterpart in the cone around the probe, the probe is labeled as ``T'' for tracker only. Finally, if only a standalone muon is found, the probe is labeled as ``S'' for stand- alone only.

Feb.2008WANG Zheng13 Muon efficiency  Muon tracking efficiency:  Standalone Mu efficiency:  Match efficiency: Global muon efficiency

Feb.2008WANG Zheng14

Feb.2008WANG Zheng15

Feb.2008WANG Zheng16 T & P One object (tag) has strict ID criteria imposed on it. Second object (probe) has looser ID criteria. Additional property that links it to the Tag object to ensure a pure sample. An example Z  e e T&P Z  ee e rec. efficiency from T&P: 94.36±0.24 e rec. efficiency from MC truth: 94.63±0.24

Feb.2008WANG Zheng17 Another talk/measurement “Towards a W/Z  +X cross section measurement at CMS” J.Alcaraz(CIEMAT) EW-Muon task force subgroup, CMS week, 13, Dec. 2007

Feb.2008WANG Zheng18 Another talk/measurement The strategy:

Feb.2008WANG Zheng19 The muon-ID in they Z  Analysis ---  This will increase the eff. In the analysis 2 global muons: mu mu with isolation cuts; 1 global muon + 1 track in the central tracker: mu + (unmatched) track with isolation cut; 1 global muon + 1 standalone muon track: mu + (unmatched) standalone with isolation cut.

Feb.2008WANG Zheng20 T & P : id/matching

Feb.2008WANG Zheng21 T & P : id/matching 匹配 eff. 寻迹 eff: sa eff. Matching eff. And global muon eff. As a function of  and Pt have been produced.

Feb.2008WANG Zheng22 T & P : isolation Isolation 效率：

Feb.2008WANG Zheng23 T & P : trigger 触发 eff. Muon trigger eff..vs.  and Pt have been produced.

Feb.2008WANG Zheng24 Electron Efficiency: Analysis Note  AN 2007/019: “Measuring Electron Efficiencies with Early Data”  Tag + probe using Z  ee (C. Hill et. Al. ):  Tag electron defined using tight criteria. Z mass constraint used to identify a looser Probe electron - unbiased w.r.t efficiency to be measured.  PAS: Cumulative Efficiency (reconstruction, ID, isolation, trigger) Electron track reconstruction efficiency

Feb.2008WANG Zheng25 Note AN 2007/019  Relies upon Z  ee decay to provide an unbiased, high-purity electron sample with which to measure the eff. of a particular cut or trigger.  In this method, a single electron trigger sample is used, from which a subset of di-electron events are selected.  The tight criteria imposed on the tag coupled with the inv. Mass requirement is sufficient to ensure high electron purity.  The Probe criteria will vary depending in the specifics of the efficiency that is being measured and how the overall efficiency has been factorized.  Present the validation of the tools by comparing the eff. obtained by them with that expected from MC truth information.

Feb.2008WANG Zheng26 Description of Tag & Probe Tools  The T&P tools are implemented within CMSSW as a series of EDProducers. Inherit from Candidate