Lauren Beitler: -------------------------------------------------------------- (Lauren is an undergraduate student from the University of Chicago working with Henry Frisch) Lauren is looking for high mass bosons in events with electrons and muons. She has noticed a large tail in the transverse mass distribution in the W->mu nu events, which isn't present in W->e nu events. This tail comes from event with a very high pt muon. These events happen much less often when the muon has silicon hits. There are two hypothesis for these events: 1. Cosmics that pass the cosmic tagger. 2. Muon decay in flight. She looked at four ways to reject these events: 1. The fractional difference between the pt and the beam constrained track pt. 2. Ehad+Eem>0.1 GeV 3. (COT-only track) chisq/ndf < 2.0, as suggested by Alexei Varganov 4. (Number of SL with >= 6 hits) >= 7 i.e. Either 4 axial SL and 3 stereo SL, or 3 axial SL and 4 stereo SL. Cut 1 isn't very useful, but Lauren has decided to use all of the others in here analysis. We discussed if we should adopt any of these cuts as standard muon cuts. Here is a summary of our discussion: Ehad>0.1 --------- Lauren showed a plot of (eta vs phi) and (z0 vs eta) for muon with Ehad=0. There are two regions where the muons with Ehad=0 tend to cluster: z0=0 and (eta=+0.5,phi=1.2 rad). Mike Lingreen and Bob Wagner have looked at some drawings of the detector and there are (or, should be) no places in the detector where a CMU muon has not transversed at least one hadron tower. Victoria pointed out that some muon in Z->mu+mu- event have Ehad=0. So some good central muons do have Ehad=0, and so rejecting these events with a Ehad>0 would reduce the efficiency of the muon ID cuts. Ehad=0 muon are also make in Z->mu+mu- MC, which probably points to a geometrical effect. We all agreed that we should find out exactly why we have but the overall consensus was that we should not make a Ehad>0.1 GeV cut. Number of SL cuts. ------------------ Both Chris and Eric didn't like this cut because it constrains the tracks too much. Henry said that this was actually the most efficient of Laurens cut to reject the high transverse mass events. This probably because these events are muon decay in flight. Track Chisq cut ----------------- Eric said that this cut has been adopted in the W->mu nu analysis. The efficiency of this cut using Z->mu+mu- events is measured to be ~99%. In conclusion we decided that 1. We should adopt the track chisq cut. It is very efficient for real muons, and does reject some of these very high pt-muon tracks. 2. A muon decay in flight tagger based on the COT hit patterns is 3. We should investigate why we find muons with Ehad=0. 2. Victoria & Lucio: Muon News --------------------------------- 3 news items: 1. We finally have a tool for the trigger. MuonTriggerTool is the the MuonUser/ package. Currently it is only implemented for the CMUP18 and CMX18. It can be used to inquire: if a given event had a muon trigger at level 3 or at level 1, and if a given muon was responsible for the level 1 trigger. 2. DQM workshop on Friday. We need to have a set of histograms to see if the runs are good for the muon systems. Some comments: Look at Number of hits in a stub to see if part of the detector is dead. Delta-x and delta-z plots are important. 3. New Cosmic tagger is implemented. Not yet tagged. Now the cosmic tagger is somewhat version dependent. So we are recommending two ways of extracting the new COT-only di-cosmic fit tagger which are independent of the version being used: One: CosmicRayInfo_ch cosmic_ch; CosmicRayInfo::Error cosmicStatus = CosmicRayInfo::find(cosmic_ch); const CosmicRayInfo& cosmic = *cosmic_ch; CosmicCuts cuts; cuts.resetDefaultCuts(); bool diCosmic = cosmic.isNotOutgoingPair(cuts); Two (if the comsic ray bitword is already in your ntuple): CosmicRayInfo::bitword() & 0x00004000 There is also the third way using hasCosmicRay(). However this is now dependent on the version of the CosmicRayInfo you are using. So to be sure that you are extracting only the result of the cot di-cosmic fit we recommend you use one of the above. 3. Eric James: W->mu nu cross section over time ------------------------------------------------- Eric (with Alexei, Jian and Ken) has calculated the W->mu nu cross for CMUP muons for all periods of data. The resultant cross section is stable over time The reconstruction efficiency is the most unstable So we conclude there are no major problems with the muon data over time. Eric can/will repeat the analysis for CMX W->mu nu, as soon as Victoria calculates the CMX reconstruction efficiency.