TISB TISB: Gruppo del Tau1 TISB 18.Maggio.2001 Sesto Fiorentino Gruppo di lavoro sul : Status report Giuseppe Bagliesi Simone Gennai Giacomo Sguazzoni

TISB TISB: Gruppo del Tau2 Motivations –H is an important channel for SUSY Higgs and probably(?) also for light SM Higgs ! –Why is important to select tau hadronic decays? –We can recover good part of signal events

TISB TISB: Gruppo del Tau3 Signal events and Bkg samples ORCA_4_5_1 Same samples used for LVL3 studies HI Luminosity (10 34 cm -2 s -1 ) Benchmark SIGNAL gg bb A/H bb –M H =200, 500 GeV Background samples: –2 jets samples –most dangerous P T bins: 50-80, , GeV

TISB TISB: Gruppo del Tau4 L1, L2 and L3pxl L1 and L2 are calorimetric trigger optimized for tau events –Ref. A. Nikitenko et al. CMS NOTE 2000/055 –See talks from A. Nikitenko on this subject L3pxl is an isolation criteria based on pixel detector only –Ref. D. Kotlinski CMS IN 2001/017 –See talks from Danek on this subject L3tk is a new algo developed with the full tracker info in order to improve bkg rejection after L3pxl. Final goal is to achieve Bkg rate < 10 Hz with good signal efficiency regardless of Higgs mass value (200, 500 GeV).

TISB TISB: Gruppo del Tau5 L3pxl ~0.1 ~0.05 ~0.3 T-jet candidate from LVL-2 calo towers Max P T track (P T >3GeV) within blue cone N TK RED CONE = N TK BLACK CONE LVL3 OK Only 3-layer PIXELs From the same Pixel PV!!! P T >1GeV

TISB TISB: Gruppo del Tau6 A. Nikitenko 07/03/2001 jetmet

TISB TISB: Gruppo del Tau7 Guardando un solo jet… h L1 Tau (calo) L2 Tau (calo) L3pxl Tau (iso) L3tk Tau 1 o jet 2 o jet Catena di trigger 1 o jet Qui sta il nostro contributo Questa configurazione + L3tk = taglio in P T Riduzione del fondo non sufficiente!!!

TISB TISB: Gruppo del Tau8 Guardando due jet… h L1 Tau (calo) L2 Tau (calo) L3pxl Tau (iso) 1 o jet 2 o jet Catena di trigger 1 o jetCatena di trigger 2 o jet Qui sta il nostro contributo L1 Tau (calo) L3tk Tau.OR.

TISB TISB: Gruppo del Tau9 L3tk sul 2 o jet: Tracking regionale o=(0,0,0) Z 1st tau jet PV in p=(0,0,z0) 2nd tau jet: L1 2nd tau jet candidate Reg Tk reconstructs tk in the 2nd jet cone with tk (0,0,z0)

TISB TISB: Gruppo del Tau10 Possible L3tk selections applied to 2nd jet: 1. Isolation criteria similar to L3pxl with full reco Tk (A) 2. Cut on the number of reconstructed Tk in the cone (B) –there are still some parameters to be optimised –Very low P T cut is applied at L3Tk (~ 1 GeV) –Both algorithms have good signal efficiency and achieve the desired bkj rejection L3tk sul 2 o jet: selezione eventi

TISB TISB: Gruppo del Tau11 L3tk: Isolation in the 2 nd jet mH=200 GeV Bkg50-80 Bkg Bkg # Tk in isolation cone R s = 0.1 R m = 0.4

TISB TISB: Gruppo del Tau12 L3tk: Number of Reco Tk in 2 nd jet mH=200 GeV Bkg50-80 Bkg Bkg # Full Reco Tk (P T >1 GeV) 0 < Ntk < 4 Jet cone = 0.4

TISB TISB: Gruppo del Tau13 Global eff and bkg Rate PRELIMINARY ! Really near to our goal ! 1. Isolation criteria of L3pxl with full reco Tk (A) 2. Cut on the number of reconstructed Tk in the cone (B) Need more statistics !

TISB TISB: Gruppo del Tau14 SIG Eff vs. QCD Rate 0 < PT cut < 40 GeV R s = ( Isolamento ).AND. ( Numero di tracce )

TISB TISB: Gruppo del Tau15 Concludiamo… We have analysed 2nd L1 tau jet in the event reconstructing tracks with regional Tk. –2 L3Tk selection criteria studied: Full Tk isolation of tracks inside the cone (A). Number of reconstructed tracks in jet cone (B). –We achieve to get a Rate of about 10 Hz after all Trigger Levels with a global signal eff 25% –All cuts are not yet optimised

TISB TISB: Gruppo del Tau16 To do list –Increase statistics to reduce bkg uncertainties. –Optimise trigger parameters to increase global signal eff. –Try to combine L3tk criteria to get better performances.

TISB TISB: Gruppo del Tau17 Extras

TISB TISB: Gruppo del Tau18 L3tk sul 1 o jet M H =200GeV M H =500GeV Eff vs. Rej (wrt L3pxl) with the full Tk reconstruction: is really hard to get good signal efficiency and good Bkg rej looking only at 1st jet. 0 < PT cut < 40 GeV