UCSB Top Quark Analyses On CDF

J.Lamb, C.Hill, J. Incandela, C. Mills

DOE Visit

January 20, 2004

UCSB CDF Top Group January 20, 2003, J. Incandela 2

CDF Top Quark Physics

• An interesting particle• Few events ever seen. Much to explore with higher statistics.

• Some run 1 results were a little bit provocative.

• Di-lepton channel cross-section

• Is the top quark special?t = 21/2 mt/v = 21/2 (174.1)/(246) = 1

• Top mass is an extremely important SM parameter.

• An interesting data sample• Leptons, jets, missing ET, and possibly tagged b jets

• Many of the ingredients of new physics

• We want to understand this sample well, vis-à-vis the SM

• Any discrepancies would be extremely interesting

• Relevant for LHC

• Background reference point for ttH

UCSB CDF Top Group January 20, 2003, J. Incandela 3

CDF CDF Silicon

• UCSB played well known lead roles in ISL and L00• Stuart & Incandela proposed and built ISL for slightly different motives

• Stuart – extend lepton coverage for new physics

• Incandela – extend b tagging for top, higgs and new physics

• UCSB took early advantage of the ISL for leptons

• CDF is near to taking full advantage of ISL and L00 for b tagging

UCSB CDF Top Group January 20, 2003, J. Incandela 4

CDF Top Di-lepton Cross Section

• Top cross section in Di-lepton channel• In less than one year we went from cold start to a lead role in

what will now be the first top result to be published by CDF

• Detailed in talks by Chris Hill and Corrinne Mills

• Extremely high quality analyses

• UCSB a key player

• Brought forward leptons (Phoenix) to the top group

• substantial effort

• Strong contributions helped get this measurement done in record time.

• PRL draft under review by a panel of “godparents”

UCSB CDF Top Group January 20, 2003, J. Incandela 5

CDF MW versus Mtop

W mass corrections depend on top mass (quadratically) and SM Higgs mass (logarithmically)

Run 1 Final

Tevatron Run 1 Final Measurements:

M(W)=80.456 0.059 GeV

M(t)=174.3 5.1 GeV

UCSB CDF Top Group January 20, 2003, J. Incandela 6

CDF Electroweak Prospects for 2 fb-1

With 2 fb-1:• Mw = 30 MeV/exp • Mtop = 3 GeV/exp

Tevatron upgrades:• luminosity is rising

in several years

• – (W), (Z) ~10% higher– (tt) ~ 35% higher

1-fb 2 dt L

TeV 1.96s

Detector upgrades: • increased b-jet and lepton ID acceptance and triggering

• detector performance is meeting most expectations

2 fb-1 of Run 2(per

experiment)

The UCSB top group has just begun work on the top mass

UCSB CDF Top Group January 20, 2003, J. Incandela 7

CDF A possible path to new physics ?

W & Z decay asymmetry (extending lepton ID to forward regions)

W and Z plus b & c jets

Top cross section in di-leptons + b jets

New physics searches in multi-leptonic final states

(Possibly with missing ET, b or c tags…)

Tools are complete

CDF has large data samples

UCSB playing A key role here.

UCSB top group mulling possibilities

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CDF Low Mass Higgs at LHC

•Two main channels • H • ttH with H bb

• Both are challenging and could be a lot more difficult than advertised

• UCSB group will use Tevatron data to help understand ttH channel

UCSB CDF Top Group January 20, 2003, J. Incandela 9

CDF ttH without full reconstruction?

• Studied for the Tevatron

• Despite extremely low rate, could potentially dig it out from huge ttjj background by novel techniques that skirted top reconstruction

• Not expected to work as well for LHC but may gain something

• Also want to measure ttjj cross-section to calibrate LHC bkd expectations

K factor ~ 1.3 and 18% Mbb resolution

UCSB CDF Top Group January 20, 2003, J. Incandela 10

CDF Summary

• Our initial entry into top group has been very strong• First top publication: Di-lepton cross section

• Beginning new top analyses • Top mass

• Analysis of di-lepton sample

• ttjj cross-section in preparation for LHC

• Excellent synergy with CMS for students