I found two sources of the discrepancy between Dan’s and my limits.  There was a problem with my signal modeling (I hadn’t included all of the available signal MC) and with Dan’s background modeling (he had too high of a QCD fraction.)  Also, I took out the ht cut that I added a while ago, since it actually gives a worse expected limit. (I had added it in an attempt to cut down some of the conversion background)

Here are my newest plots:

TCE W:

CMUP W:

CMX W:

TCE Z:

CMUP Z:

CMX Z:

Clearly, there is a problem with the modeling in the Z channel. (It’s most noticable in the muon-triggered Z + 1 soft muon bin, where the background is low by a factor of 5.  Since this issue causes problems in mclimit, I’m currently only using the W channel to set a limit.  The limit is:

Observed : 0.439 +- 0.0000000
Expected : mean=0.273 +1sig=0.381 -1sig=0.209 +2sig=0.509 -2sig=0.180

If I include the Z, I get:

Observed : 0.532 +- -1.9805458
Expected : mean=0.216 +1sig=0.299 -1sig=0.164 +2sig=0.421 -2sig=0.137

With these current plots, I’m getting a worse limit than Dan has, even though he ignores the information from the electrons.  I’m currently running jobs to calculate the tag rates exactly, (as Dan does it) instead of throwing random numbers.  This should improve my systematics, but it also vastly increases the running time. (I have to go through all the combinations, so it runs in factorial time.  I could probably speed this up if some wants to prove that P==NP.)

Here are the plots of number of electrons and muons with systematics included.  The systematics include both a 10% error in the electron and muon tag rates and the uncertainty due to the random method I’m using to tag leptons.

TCE:

CMUP:

CMX:

-Scott

After speaking with Henry  on Friday, I’m using the W+jets instead of W+heavy samples to get the 2-to-1 soft lepton ratios.  Here’s the newest table:

The numbers are much closer than they were before, but there are still issues to fix:

• The e+mu predictions seem too high, (at least in the TCE trigger) and I just fixed a problem that will, I expect, increase them further.
• I believe the expected contribution from two conversion electrons is still two low:

• The soft electron parameterization needs to be tweaked (or I could just cut off the soft electrons at 1.5 GeV):

-Scott

I’ve found the reason the predictions are high in the 2-lepton categories.  The problem is in the 2-lepton to 1-lepton ratios, but I’m not sure how to fix it.

In order to calculate the expected contribution from a particular 2-lepton process, say e+ from a heavy jet and e- from a light jet (abbreviated ePh and eNl) we find N(ePh)_data from the pTrel/d0 fit, and multiply that by the ratio found in the MC: N(ePh + eNl)/N(ePh)

N(ePh)_data * N(ePh + eNl)_MC / N(ePh)_MC = N(ePh + eNl)_predicted

Currently, we’re using the W+heavy MC to calculate N(ePh + eNl)_MC / N(ePh)_MC.  Naively, I would expect that using the W+jet MC would give the same answer, but with larger error bars, since there is some W+heavy in the W+jet sample.  However, as it turns out, the two samples give a ratio that differs by a factor of two.  They agree on the number of expected ePh + eNl events, but the W+jet has significantly more ePh events. (remember that the categories are exclusive)

In the following plots, the X-axis is the number of e+ from heavy jets in the event, and the Y-axis is the number of e- from light jets.  Look at the (1,1) and (1,0) bins.  The top plot is W+jets, and the bottom one is W+heavy.

The N(ePh) is twice as large in the W+jets sample as in the W+heavy sample.  We’re currently using the W+heavy numbers in our calculations, (on the assumption that the error bars would be smaller) but the W+jets numbers seem to agree better with the data.  Is there a reason the two should be so wildly discrepant?

-Scott

Here are the new expected and observed numbers in e+e and e+mu:

Old Track Quality:

New Track Quality: (tighter silicon requirements for electrons)

The most dramatic change between these two was the reduction in the predicted contribution from (e+e-, both from conversions).  That contribution was reduced by a factor of two, but that’s the one that we aren’t currently getting a good estimate for. (a reduction from 12 to 6 doesn’t show up very well)

-Scott

Here are the expected and observed numbers for the various e+e and e+mu dilepton bins.  The background estimate is too high in many of the cases, but the same-sign same-flavor categories are reasonably close.  There are some problems with the code that stacks all the background contributions together, and I believe that that is where the differences are coming from.

DILEP_TCE_eP_eP nbg=550.536 data=469
DILEP_TCE_eP_eN nbg=12044.3 data=439
DILEP_TCE_eN_eN nbg=583.46 data=428
DILEP_CMUP_eP_eP nbg=331.307 data=302
DILEP_CMUP_eP_eN nbg=6261.74 data=284
DILEP_CMUP_eN_eN nbg=342.74 data=315
DILEP_CMX_eP_eP nbg=189.794 data=170
DILEP_CMX_eP_eN nbg=3783.66 data=173
DILEP_CMX_eN_eN nbg=185.485 data=201
DILEP_TCE_eP_mP nbg=65.4135 data=19
DILEP_TCE_eP_mN nbg=63.8633 data=26
DILEP_TCE_eN_mP nbg=58.6098 data=36
DILEP_TCE_eN_mN nbg=64.9233 data=30
DILEP_CMUP_eP_mP nbg=32.5401 data=12
DILEP_CMUP_eP_mN nbg=30.2969 data=24
DILEP_CMUP_eN_mP nbg=31.4779 data=16
DILEP_CMUP_eN_mN nbg=32.2473 data=14
DILEP_CMX_eP_mP nbg=16.3119 data=14
DILEP_CMX_eP_mN nbg=20.3123 data=8
DILEP_CMX_eN_mP nbg=15.8709 data=12
DILEP_CMX_eN_mN nbg=22.3682 data=13

-Scott

Here are a couple of the new dilepton (e+mu) plots. Specifically, these are the dilepton mass plots.

e+ mu+:

Continue reading Some e+mu plots →

Here are the fits to the various background sources in pTrel and d0.  This is only the first fb^{-1}.

TCE sele negative:

Continue reading pTrel and d0 fits for electrons and muons →

Here are some plots about the fake rate in the jet sample.  I added the cleanup cuts we talked about, and everything makes sense now.

-Scott