p17 ZH -> mumu bb Analysis
w/ Neural Net Event Selection
Update

Andy Haas
Columbia University

V+jets Higgs Working Group Meeting

March 15, 2007

Analysis Updates

int N_zmumu_1560_0lp = 650250;

int N_zmumu_130250_0lp = 108000;

int N_zmumu_gt250_0lp = 106250;

int N_zmumu_0lp = 1469750;

int N_zmumu_1560_1lp = 512500;

int N_zmumu_130250_1lp = 100250;

int N_zmumu_gt250_1lp = 105750;

int N_zmumu_1lp = 874116;

int N_zmumu_1560_2lp = 205000;

int N_zmumu_130250_2lp = 100750;

int N_zmumu_gt250_2lp = 102250;

int N_zmumu_2lp = 413500;

int N_zmumu_1560_3lp = 100500;

int N_zmumu_130250_3lp = 99750;

int N_zmumu_gt250_3lp = 105750;

int N_zmumu_3lp = 317000;

int N_tt_incl = 1615030;

int N_wz_incl = 724250;

int N_zz_incl = 711000;

int N_zmumu_2b0lp = 342000;

int N_zmumu_2b1lp = 52750;

int N_zmumu_2b2lp = 25000;

int N_zh_mumubb_m105 = 50000;

int N_zh_mumubb_m115 = 50000;

int N_zh_mumubb_m125 = 50000;

int N_zh_mumubb_m135 = 52250;

int N_zh_mumubb_m145 = 49750;

int N_zh_mumubb_m155 = 50500;

before

M_01 (GeV)

M_01 (GeV)

after

Old QCD Fit

Used to assume QCD shape was exponential

– same as DY

Fit data to sum of Z (gaus) and

QCD/DY (exp) shapes

Got 32% QCD+DY from fit

-> 27% after subtracting

DY fraction (5%) from MC

WRONG!

Measure QCD shape in non-isolated data:

-> QCD shape is exponential, but falls off

faster than DY!

There is another background besides QCD/DY:

-> tt is significant in 2b channel!

New QCD Fit

Use QCD shape from non-isolated data

Smear muons properly in MC

to describe Z shape better

-> Add “ApplyMuonSmear” processor

Consider tt contribution while fitting

Result:

Much less QCD in 2b channel:

27% -> 2%

old
smearing

(and just

60-130)

2b fit

tt

0b fit

tt Cross-check

double-tag

single-tag

Train NN against tt as the signal

Some evidence for tt, consistent with expectations

tt Cross-check w/ Wider Acceptance

double-tag

single-tag

Widen Z mass window, 70-110 -> 40-500, accept more tt signal

Good evidence for tt, consistent with expectations

Andy Haas

2004-07-07T15:59:13