26th June 2007RAL1 Signal and Background Separation in ttH Resham Sarkar Indian Institute of Technology, Kharagpur

26th June 2007RAL2 Introduction:  The backgrounds are  ttjj  Electroweak ttbb  ttbb QCD The Event ttH

26th June 2007RAL3 Variables used: (ref. Janice Drohan’s thesis) combinatorial likelihood chi squared distribution difference of the phi angles of the two top quarks lowest mass combination Higgs scalar sum of transverse momentum of the two top quarks b-tagged likelihood

26th June 2007RAL4 We are yet to try: The lowest-but-one combination Higgs mass The difference in eta between the two jets The difference in eta between the reconstructed Higgs and nearest top-quark......

26th June 2007RAL5

26th June 2007RAL6

26th June 2007RAL7 The likelihood variable This has been designed to do combinatorics in ttH All the backgrounds have 'tt' in them, but they are being rejected

26th June 2007RAL8 The b-tagged likelihood

26th June 2007RAL9 a) b) c) d)

26th June 2007RAL10 The Combinatorial Likelihood The mass window ranges from 90 to 150

26th June 2007RAL11 The b-tagged likelihood

26th June 2007RAL12 The difference of phi angles of the two tops

26th June 2007RAL13 The Higgs lowest mass combination

26th June 2007RAL14 Negativity of ttjj The monte-carlo simulation produces some negative weighted events –These are derived from interference terms Complicates the total, smoothing, taking ratios and other functions

26th June 2007RAL15 Total ttjj Total ttbbEW Total ttQCD Total poslep Total neglep Selected ttjj Selected ttbbEW Selected ttQCD Selected poslep Selected neglep The better significance is obtained due to the absence of a mass window

26th June 2007RAL16 The Higgs raw mass has been cut at a value where the total shows a peak i.e. -22 At around a mass of 120GeV the highest number is achieved

26th June 2007RAL17 Shoot all questions towardsBill Thank you