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No Shielding. D0 Shielding. D0 Interaction lengths. 0 10 20 l. Physics with Muons: D Ø Highlights. Exciting new results from analyses presented at Moriond 2004 on B Physics New Phenomena searches Electroweak & Top Studies Integrated Lum’y up to 250 pb -1 - PowerPoint PPT Presentation
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April 14, 20041
Physics with Muons: DØ Highlights
Exciting new results from analyses presented at Moriond 2004 on B Physics New Phenomena searches Electroweak & Top StudiesIntegrated Lum’y up to 250 pb-1
With emphasis on the strategy brought on because of the muon system.
Tom Diehl (FNAL)For D0 Collaboration
No Shielding
D0 Shielding
0 10 20
D0 Interaction lengths
April 14, 20042
Acknowledgements
Special thanks to S. Burdin, A. Nomerotski, J. Stark, G. Watts, M.
Verzocchi, and R. Kehoe for discussions and for many of the slides.
April 14, 20043
SMTSMT
SMT
Muon System and Tracker New muon system with ||<2 and good shielding 4-layer Silicon and 16-layer Fiber Trackers in 2 T magnetic field
April 14, 20044
Properties of a Good B Physics Detector*
* From “B Physics @ the Tevatron: Run 2 and Beyond” A high precision vertex detection Tracking w/ excellent momentum resolution Excellent particle ID capability Robust trigger integrated into a high bandwidth DAQ
No specific mention of importance of muons?
April 14, 20045
Properties of a Good B Physics Detector*
* From “B Physics @ the Tevatron: Run 2 and Beyond” A high precision vertex detection Tracking w/ excellent momentum resolution Excellent particle ID capability Robust trigger integrated into a high bandwidth DAQ
The point is, muon trigger and ID is only one of several required elements.
(BUT it turns out to be most advantageous to have powerful muon trigger and ID. Trigger on: J/ and/or
a tagging lepton. No Lifetime cuts in trigger.)
April 14, 20046
J/: Run 1 vs. Run 2
Run I: 407 62 J/ 6.6 pb-1 out of 13 pb-1
pT()>8 |eta()|<1 ~35% from B’s (1/p)= 0.18/p2 + 0.003
Run II: 1.2M J/ 250 pb-1
pT()>0.18 |eta()|<2ish [(pT)/pT]2 ~ 0.0152 + (0.0014pT)2
April 14, 20047
Why so many J/psi in Run II?
pT() of J/psi in B-decays Monte Carlo
16% have 2 pT >1.5 GeV/c 7% have 2 pT > 1.5 & 1
pT > 3.5 GeV/c 0.1% have 2 pT > 6.0 GeV/c
It’s the trigger that gets them onto tape.
It’s the solenoid & tracking that provides the skinny peak.
pT() (GeV/c)(G
eV/c
)pT
()
Run 1
April 14, 20048
Tracking Performance
pT spectrum of soft pion candidate in D*D0
Tracks are reconstructedstarting from pT = 180 MeV(Lower pT is better)!
Muon in J/psi events
Coverage of Muon system is matched by L3/offline tracking
“This greatly enhances our B-physics program.” - A.N.
Lower trig threshold in magnet corner
Data
April 14, 20049
Tracking Performance
Impact Parameter Resolution
NOT yet used for PIDP/K/ separation for some pT
SMT dE/dx
More tracking improvements under way
• (DCA) 16 m @ PT = 10 GeV (DCA) 54 m @ PT = 1 GeV• Resolution compares well with MC
April 14, 200410
X(3872) J/ + -
Last summer, Belle announced a new particle at 3872 MeV/c2, observed in B+ decays:B+ K+ X(3872), X(3872) J/ + -
Nature of X(3872) is not known• could be charmonium, meson molecule etc.
Belle’s discovery has been confirmed by CDF and DØ.
300 61 events, a 4.4 bump
(2S) (1S) w/ br (31%)M[(2S)] M[(1S)] = 589 MeV/c2
Compared properties of sample of X particles to sample of (2S): no differences seen in pT, d.l., isol, …
M = 0.7680.004(stat)0.004(syst) GeV/c2
April 14, 200411
Exclusive B Decays
Accumulated large exclusive samples of B+ and B0
Find in 250 pb-1:B+ J/K+ 4306 events
B0 J/K* 1900 events
B0 J/Ks 375 events
b J/ 52 events
Mb=5615 9 MeV/c2
Good S/B Lifetime cuts applied
lxy/(lxy)>4.5
April 14, 200412
The world largest sample of exclusive Bs J/ decays
Work in progress on Lifetime measurements Studies of Mixing & CP effects
Bs Exclusive Decays
250 pb-1
Some lifetime cuts applied
Bs Ds (
Bd D+ (
GeV/c2
Work in progress on Bs/Bd lifetime ratio and first results on Bs mixing
• need to fully understand time resolution
• if ms 15 ps-1 expect a measurement with 500 pb-1
+ cc
April 14, 200413
Semileptonic Bd sample
Collected by low pT single muon triggers
109k B+ D0 candidates 25k B0 D* candidates
D* yield 50% higher for looser selections
Plots below have (offline) lifetime cuts
Sample compositions:
“D0 sample”: 82% from B+ “D* sample”: 86% from B0
Estimates based on measuredbranching fractions and isospinrelations.
B D0 X
April 14, 200414
(B+)/(B0): Result
one example : VPDL bin [0.10 - 0.15 cm]
Preliminary result:(B+)/(B0) = 1.093 0.021 (stat) 0.022 (syst)
(among the most precise of this quantity)
Use binned c2 fit of event ratios to
determine (B+)/(B0)
VPDL=LT/pT(D0)*Mb
April 14, 200415
B0
B0/B0 Mixing: Milestone !
Preliminary results:
md=0.5060.055(stat)0.049(syst) ps-1
Tagging efficiency: 4.8 0.2 % Tagging purity: 73.0 2.1 %
Tagging procedure• opposite side tight muon • muon pT > 2.5 GeV/c• cos < 0.5
Fit procedure• Binned 2 fit
• Already one of the best measurements at hadron collider • Good prospects to improve accuracy
• work in progress to decrease systematic uncertainty• use other tagging methods: jet charge, same side tagging, electron tagging• add more D0 decay channels
April 14, 200416
Observation of B D** X
• Start from B D*X sample, add another +
• Look at invariant mass of D*- + system• Observed merged D1
0(2420) and D2*0(2460)
Two interfering Breit-Wigner D** states with mass/width as measured by Belle (no resolution effects included) Work in progress: extract separate amplitude for each state and relative phase of interference
wrong-sign combinations
Unique observation at hadron colliderPreliminary result on product branching ratio
Br(B {D10,D2*0} X) Br({D1
0,D2*0} D*+ -) = 0.280 0.021 (stat) 0.088 (syst) % measured by normalizing to known Br (B D*+ X)
D** are orbitally excited D meson states
April 14, 200417
Properties of a Good High pT Muon Detector
High pT > 10 GeV/c e.g. Top Pairs
Most high-pT physics is centralish
Don’t need to cover past ||=2
TTbarbb
Moderate Coverage
Low Background
The Physics is cross-section limited Require a robust high-pT unprescaled trigger. Rejection against low pT muons, cosmics, meson in-
flight decay.
Accep’ for both muons
April 14, 200418
W & Z to Muons in Run 1
13 pb-1 (Run 1a) 1665 W’s 77 Z’s
Muons + jets or EM was much better off at trigger level.
April 14, 200419
W and ZCross Sections
Zin 117 pb-1. 2 opposite-charged tracks w/
pT>15 GeV/c At least one is isolated Scintillator timing, DCA,
acolinearity cuts to remove small backgrounds
In 150 pb-1 we have ~ 15,000 of these due to improvements in the trigger. In 250 pb-1…
Testing our understanding of the systematics (Update soon).
# E
vent
s \ n
s
Br = 261.8 ± 5.0 (stat) ± 8.9 (sys) ± 26.2 (lum) pb(prior to reduction in L)
Cut at 16 ns
117 pb-1
6126 events
April 14, 200420
W and ZCross Section
Win 17.3 pb-1. An isolated muon w/ pT>20
GeV/c in ||<1.6
Bkgd is Z, WQCD Veto if additional muons. F(bkgd.)=0.118
8305 Candidates after background subtraction
In 104 pb-1 we have ~73,000 WIn 250 pb-1…
Br = 3226 ± 128 (stat) ± 100 (sys) ± 322 (lum) pbR is high in these early results.
April 14, 200421
W Cross Section:
Small cross section in SMSensitive to new Physics
Signaturee or and and photon w/ (ET>8 GeV) & R(l>0.7)
We W
Luminosity (pb-1)
Background Expected
Bkgd + SM Signal Expected (events)
162
87.1 ± 7.5
142 ±17
82
37 ± 10
67 ±13
Observed (events) 146 77
A First Step to Trilinear Gauge Couplings
(ppW l+X)19.3 ± 6.7 ± 1.2(lumi)
pb
April 14, 200422
New Phenomena Searches SUSY
Search for Squarks and Gluinos in the Jets+MET Topology Search for mSUGRA SUSY in the Like-Sign Muon ChannelSearch for Chargino/Neutralino in ee(+l) Final State Search for Chargino/Neutralino in Trilepton Final StateSearch for GMSB SUSY in Di-photon Events with Large MET
LeptoquarksSearch for the First Generation Leptoquark
Extra DimensionsSearch for LED in Jets+MET Topology Search for Large and TeV-1 ED in Di-electron Channel LED in Di-electron and Di-photon Channels
Z’Search for Heavy Z' Bosons in Di-electron Channel
HiggsHWWdileptonsHSearch Submitted to PRL (First D0 Run II Publication)
SM is safe for another day
April 14, 200423
Top Quark
Run 1 World Average Top MassRun 2 Cross Sections
All jets, dilepton, l+jets
Precision Measurement in Run 2
Top Cross SectionsCross Check SM with MTop
Single topRare Decays
Top MassConstrain MHiggs
+ soft muon tags
April 14, 200424
Di-Lepton Top Cross Section
Lore: “Small cross section.Relatively free of SM backgrounds.”
SM Backgrounds
jjllWW jjllZ /
ALPGEN+Pythia
Instrumental Fakes
TE FakesIsolated Lepton Fakes
Estimated on data
Working on optimizing the selection criteria
April 14, 200425
Lepton + Jets
April 14, 200426
Top Cross Section Summary
Leptons + jets
April 14, 200427
Run 1 Top Mass Combination
DØ New Run I Top Mass = 180.1 ± 5.3 GeV/c2
(see Juan Estrada April 25 W&C)
“Old” Mt was 174.333 ± 5.141 GeV/c2.Role for muon is to trigger & ID (low background).
April 14, 200428
Summary/Conclusions
Details on all recent results can be found at http://www-d0.fnal.gov/Run2Physics/WWW/results.htm
B-physics at DØ is online* with world class results X(3782) seen Record semileptonic & exclusive B samples B Mixing & a precise measurement of B+/B0 lifetime ratio
High pT physics W, Z, & WCross Section and big samples in the can top cross section at 1960 GeV & Run 1 Mass
The powerful muon detector and trigger is a key contributor.
April 14, 200429
Back-up slides&
Unused slide storage
April 14, 200430
Winter Conference Dataset
Thanks to all for the data!
Thanks to all for the data!
All Data Reprocessed by December 2003 with improved reconstruction
~170 pb-1 for these analyses
April 14, 200431
LAr in gap 2.3 mm
Ur absorber
Readout CellCu pad readout on 0.5 mm G10 with
resistive coat epoxy
Drift time ~430 ns
North End CapSouth End Cap Central Cal.
ICD
EM
FH
CH OH
MH
IHEM
MG
FPS
CalorimetersCalorimeters
• Liquid Argon sampling• uniform response, rad. hard, fine spatial segmentation• LAr purity important
• Uranium absorber (Cu/Steel CC/EC for coarse hadronic)• nearly compensating, dense compact
• Uniform, hermetic with full coverage • || < 4.2 ( 2o), int ~ 7.2 (total)
• Single particle energy resolution• e: /E = 15% / E 0.3% : /E = 45% / E 4%
50k readout cells (< 0.1% bad) Fine segmentation 5000 pseudoprojective towers ( 0.1 0.1 ) 4 EM layers, shower-max (EM3): 0.05 0.05 4/5 Hadronic ( FH + CH )
L1/L2 fast Trigger readout 0.2 0.2 towers Fully commissioned
April 14, 200432
Triggers for B physics
Robust and quiet single- and di-muon triggers Large coverage |<2 Variety of triggers based on
L1 Muon & L1 CTT (Fiber Tracker) L2 & L3 filters
Typical total rates at medium luminosity (40 1030 s-1cm-2) Di-muons : 50 Hz / 15 Hz / 4 Hz @ L1/L2/L3 Single muons : 120 Hz / 100 Hz / 50 Hz @ L1/L2/L3
Rates before prescaling: typically single muon triggers are prescaled or/and used with raised pT threshold at L1
Muon purity 90% - all physics! Current total trigger bandwidth
1600 Hz / 800 Hz / 60 Hz @ L1/L2/L3
B-physics semi-muonic yields are limited by L3 filters and L3 bandwidth
April 14, 200433
Observation of B D** X
Figure from Belle, hep-ex/0307021D10, D2*0 have been observed and studied
in several experiments, most recently by BaBar and Belle in B- D**0 -
We study D10, D2*0 produced in semileptonic B decays.
D** are orbitally excited D meson states, see diagram
In heavy quark limit expect two sets of doublet states Two broad (decay through S-wave) Two narrow (decay through D-wave)
Narrow D** D0
1(2420) -> D*+ -
D*02(2460) -> D*+
-
One of decay channels
April 14, 200434
End Back Up Slides