4/8/3hobbs, usb colloquium1 the future is now: recent results from d run ii

4/8/3 Hobbs, USB Colloquium 1

The Future is Now:Recent Results from D Run II


The Standard Model: It really works…

Predicts: fermion couplings, spins, W/Z mass ratio, …

Global Fit 2’s: LEP+TeV 16.7/14 (27%) +NuTeV 25/15 (4.6%?)

H0

mas

s,


The Standard Model: It really works…

Predicts: force couplings, spins, vector boson masses,

Global Fit 2’s: LEP+TeV 16.7/14 (27%) +NuTeV 25/15 (4.6%?)

H0

mas

s,


Forbidden (WW cross section)

Forbidden (t coupling)

1 Tev = 103 Mp , new physics

Allowed

•Higgs?•ad hoc parameters:

– Fermion, H0 masses– CKM matrix elements

•Hierarchy problem•No mixing, enough CP?•No coupling unification•Effective theory?•others…

The Standard Model: Flawed?

Our task: 1. Measure SM parameters 2. SM internal consistency? 3. look for non-SM sources


Topics• A one page history of D• A D upgrade • Accelerator & Detector status

– Reappearance of older physics: mesons, baryons, W, Z (benchmark processes)

• Where are we now? – New measurements: W, Z, top

• The Future– Heading toward the Higgs?

Thanks to my colleagues for advice, explanation & plots


D History: Tevatron Run I • Tevatron

– Run I, ’92 – ‘96– s = 1.8 TeV, pp (world’s highest)– Data sample, = 0.125 fb-1

• Important physics results– Top quark observation!– W mass– Search limits (e.g., LQ)– …

L

500 collaborators > 120 publications > 130 theses


Tevatron Run II• When?

2001 to 2008 (LHC…)• s = 1.96 TeV (world’s highest)

, up 10%-30%•More data

Original plan10 – 15 fb-1 (100x Run I)

Current plan 6 – 11 fb-1 (60x)

Now, = 0.03-0.10 fb-1

Experimental issue: Bunch crossing time3600 ns to 396 ns (2.5 Mhz)

•Require significant detector upgrades

–Handle changed conditions (running in place)–More capabilities

LAp

proa

chin

g Ru

n I

tot

al e

xpos

ure


Fermilab & the Tevatron

Chicago

D

Main injector

sprawl

Tevatron


+ Trigger system Design goals L1, 10 khz L2, 1 khz l3, 50 hz+ DAQ system

+Additional upgrades: FPD (diffractive) STT (USB) more silicon (USB)

Magnetic spectrometer!!!

A D Upgrade


The Tracker UpgradeSide view Preshower

(USB)

Fiber tracker (8 doublet layers)

Silicon vertex

Magnet(800k channels)


4 jet event (w/4 b tags!)


Run Status: Where are we?

100

140

60

20 Theseresults

Current Trigger RatesL1: 1 kHzL2: 0.6 kHzL3: 50 Hz

Recent data taking:

= 90% / run 85% overall Record LINST,s 8x higher, 1yr


(Data-Theory)/Theory

Dominant uncertainty: physics calibration statistics should become <20% effect

Experiment Status through Physics:Di-jet Mass Cross-Section

10% luminosityerror not shown

DATA THEORY

Agrees w/Run I

after new ECM

q’

q’O O O O q

q

One of the diagrams…

g


Now restrict to old-style b-jets•Run I: 2x-3x theory•Use b X decays

–pTrel “high” from mass jet

+jetpT

Rel

e.g. 20 GeV < ET(jet)< 25 GeV

B fra

ctio

n

pTjet (GeV)


And the cross section…

Uncertainty due to•b quark mass•renormalization/factorization scale•pdf’s•fragmentation functionsBased on NLO calculations and applied to Pythia

(not fully correctedfor lepton losses andbranching ratio)

Consistent with Run I result


More specific: J/

Widths within 30% of expectation using 1st pass alignmentJ/ 75k decays

Peak -25 MeV calibrate!

M GeV/c232.6 3.42.2 3.8

’

• Useful for calibration/alignment• Tag for reconstructing B decays


Detector Performance II: New trackerx-y vertex location of e+e-

Beams perp. to page


Detector Performance II: New trackerx-y vertex location of e+e-

Data -ray of the detector

Point resolution: 12 m r-10 0 10x, cm

10

y, c

m

-10

0

Beams perp. to page


p

And other resonances too…

K

K


b distribution

b = 468 7(stat) 22(sys) m

mm-2 -1 0 1 2 3 4

Inclusive B Lifetime

(sys)074.0 (stat)024.0561.1 ps

014.0564.1 ps (PDG)

B fraction 17.3 0.5 % Fraction of outliers = 1x10-3

±±

14.0Fitting Bias15.9Correction factor

Error (m)SourceDominant Sys Errors

( ) states (prompt)B J/ X (lifetime)

ccJ/ Sources


J/ Ks

Towards Physics: CP and sin(2)Combine J/ with Ks and require decay lengthsignificance >3.0

Expect sin(2) = 0.04w/2 fb-1

A = = sin(2) sin(mt)

(B0JK0s) - (B0JK0

s)(B0JK0

s) + (B0JK0s)


New Measurements: @ s = 2.0 TeV

• 1st measurements of W/Z cross sections– Expect 10% increase from beam

energy• Top quark

– Is it still there?– Cross section; expect 30% increase


*BR*BR(W l) and *BR*BR(Z l+l-)• EW process, e.g. pp(qq) Z • Requires a complete analysis chain

Z

z = mcL12(2L2-L2

2)loose2track

2fzoppositeisol

Br = 263.8 ± 6.6 (stat) ± 17.3 (sys) ± 26.4 (lum) pb

1st time at = 1.96 TeVs

Some dirty laundry ad hoc pT smearing, 3x (USB student nearly to solution)

(ultimately, 4%)


Add W e, Z ee

1st measurements of *BR of W&Z at s = 2.0 TeV


Recent Physics Revisited: Top quark

•Is it still there?– LTOT = 30 – 50 pb-1

•Run II , up 30%*•Assume S.M., tWb•Decays considered

– or e + 2 jets (4%)–e/ + 4 jets (no b-ID) (30%)–e/ + jets(+ for b-ID)

•Analyses ala Run I

*6.7-7.5 pb

t

t

W

W

?

?

b

bO O O O

q

q


Top quark: lepton+jets channels• One W e; other W qq’• Method = normalize from data

– Select W-enriched sample– Determine W-free component

(essentially mis ID jet as e/isolated )– Normalize W+3, 4 jets bkg using s power

law– Topology & kinematic selection: final

answer


Top quark: W-less background• Detector mis-identification

– dominant non-W background– Highly EM jets (multi 0) or

in jet from “b”, but jet not reconstructed

• Separate using loose(L) vs tight(T)– Loose dominated by background– Tight dominated by real W leptons

For e’s: a track match (E/p)!For ’s: hadronic isolation


Top quark: QCD background•Signal

–Measure using Z evts

•Background–Measure w/low MET

•Also need P(L->T)

QCDttWL NNN ~~

QCDQCDttWT NNNttW

~~

DØ Run II Preliminary


P(L->T), signalP(L->T), bkg


Top quark: W+jets background•Jets from gluon rad.,•Use scaling

–Each gluon, “s” –Fit jet multiplicity

•Signal region, NJ >= 4


e+jets:

)())1((

jets

jets

nWnW

4~WN

24.2

11.94~

QCDN11.9

12.54

obsN38 (+jets)

22 (e+jets)


Top quark: Further Selection•2 branches

–Tag b-jets, b->X–Use kinematics

•Kinematic Selection–Aplanarity–HT, Total hadronic energy perp. to beam

e+jetsDØ Run II Preliminary

•Tag Selection–Require low pT –Near a jet (b mass)–Only 3 jets needed


Top quark: l+jets Results

TagChannel Bkg. Tot. Pred.

Signal Nobs

e+jets 0.20.1 0.5 2

+jets 0.60.3 0.4 0

Topological

ChannelNW NQCD Bkg. Tot. Pred.

Signal Nobs

e+jets 1.30.5

1.40.4 2.70.6 1.8 4

+jets 2.10.9

0.60.4 2.71.1 2.4 4

And then calculate cross section (with efficiencies ala W, Z cross section)…


Top quark: Summary

Combined cross section: 3 effect…

10 30 50-10(pb)

pb (lumi) 0.8 (syst) (stat) 8.4σ 5.33.5

4.53.7


Towards the Unknown: HiggsIndirect EW fitconstraints

LEP EWWG

•The Higgs boson has not been observed

– Direct: M > 114.4 GeV…– Indirect: M = 91 GeV M < 211 GeV (95% CL)

•Run II needs >2 fb-1

–It’s gonna’ be 2 years

•Background rates poorly known. Begin here…

+58-37


Higgs: Background studies•Low Mass region

–Hbb–Produced w/W or Z

•Backgrounds:–W or Z + bb–tt (dileptons)*–tb–WZ, ZZ*

•High mass region–H WW (ZZ)–direct production or with W, Z

•Backgrounds:–WW* run I 2? evts–tt*, 30 evts–tb ? evts

*Best known


Low Mass Higgs: Dijet Studies•1st step, look at

W+jets, Z+jets–Sim. = Pythia (for now)

•Normalize by area–Shape comparison– Rate: large theory uncertainty

Cannot use scaling for Higgs and for top

• Uncertainty–Statistical (data)–Energy calibration (MC)

2nd leading jets

1st leading jets W(e)+jets

Dot : DataBar : MC

Dot : DataBar : MC


Low mass Higgs: dijet Shapes• Reconstructed di-jet mass and R(= 2 +

2 ) between di-jet– MC represents jet distributions well, so far– Normalized to same areas (’s, OK…)

MJJ

Re &

combined


Low Mass Higgs: Z+jetsDi-jet Mass R between di-jets#jets in Z+jets

Combined Z(ee)+jets and Z()+jets

See the significantly lower statistics in Z compared with W’s (10x)


Resolution

b enhanced

+ jet sample

Low Mass Higgs: Next steps•Then to W+bb, Z+bb•Different 2b tagging

–No explicit decay req’d–Tuning

•Technicolor: fall ‘03

SHW Operating point

OptimumOperating point

Sign

al E

fficie

ncy

Background Efficiency

IP>0Jet

track

Interaction point

IP<0Compare W+bb with W+u,d,s,c

S. Towers


High Mass and Non-SM Higgs• Protoype is HWW; W e, • Has higher rate, non-SM possibilities• Can we predict event yields?WW ee

ee ee

Signal, x50


High mass Higgs: H WWWW ee Channel Expected

background DATA

Lepton ID, pT>20 GeV/c

2748 42 245 2753

mee < mH/2 264 18.6 4.3 262

ET > 20 GeV/c2 12.3 2.5 0.7 11

Transverse mass 3.6 1.4 0.2 1ee < 2.0 0.7 1.4 0.1 0WW e Channel Expected

background DATA

Lepton ID, pT>20 GeV/c

22 2.1 2.2 22

ET > 20 GeV/c2 3.1 1.7 0.1 4Anti W 1.4 1.5 0.1 2

e < 2.0 0.9 1.5 0.1 1

Background Z/* mis-ID WW

Background: Z mis-ID WW

also


Non SM Search: H •In SM, BR = 10-4

•LHC, discovery mode•But for some models

–Technicolor–Fermiophobic– 0.01 < BR < 1

•Background– Z/*–Mis-ID

•Final state, no MET

M

M[GeV/c2]

Even

ts/1

0 Ge

V


Non SM Search: H -> Upper Limits

!


Conclusions• D has significant new capabilities

– Magnetic tracking– Detector basically working (calib/align/algos)

• Outlines of a rich physics program– Initial physics results: W, Z, top, ….– Begun studies for Higgs backgrounds…

• Many search results available, not shown– Including SUSY h at high tan (soon…)– No suprises. Reasonable data vs. pred.

Soon into a new luminosity regime!• Run, run, run, …

4/8/3hobbs, usb colloquium1 the future is now: recent results from d run ii

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