CIPANP2003K. HonscheidOhio State
The Future of Flavor Physicsat Hadron Colliders
CIPANP 2003K. Honscheid
Ohio State University
CIPANP2003K. HonscheidOhio State
B Physics Today
CKM Picture okay
CP Violation observed
No conflict with SM
Vud Vus Vub
VCKM = Vcd Vcs Vcb
Vtd Vts Vtb
sin(2) = 0.734 +/- 0.054
CIPANP2003K. HonscheidOhio State
Surprising B Physics
Year
Item Theory Prediction ~Value
# B’s
1983 bToo small to be observed ~ < 0.1ps 1 ps 2x104
1987 Bo-Bo mixing
Too small to see (~ < 1%) as mtop is believed to be ~30 GeV
20% 2x105
2001 sin(2) No direct prediction, but consistent with other measurements
3/4 107
>1011 b hadrons
(including Bs)
CIPANP2003K. HonscheidOhio State
B Physics at Hadron Colliders
Energy 2 TeV 14 TeVb cross section ~100 b ~500 b
c cross section ~1000 b ~3500 bb fraction 2x10-3 6x10-3
Inst. Luminosity 2x1032 >2x1032
Bunch spacing 132 ns (396 ns) 25 nsInt./crossing <2> (<6>) <1>Luminous region 30 cm 5.3 cm
Tevatron LHC
Large cross sectionsTriggering is an issueAll b-hadrons produced (B, Bs, Bc, b-baryons)
CIPANP2003K. HonscheidOhio State
Detector Requirements
From F. Teubert
•Vertex, decay distance•Momentum•PID•Neutrals (, 0)
CIPANP2003K. HonscheidOhio State
CDF and D0
CDF pioneered B physics at hadron collider. New for Run II
TOF (Particle ID)Detached Vertex TriggerImproved tracking
D0 enters B physicsNew for Run II
TrackingDetached Vertex Trigger (soon)
CIPANP2003K. HonscheidOhio State
Acceptance || < 2.5
Particle ID ATLAS v.limited -K
separation, ~0.8s from TRD
Di-lepton trigger Vertexing
Special pixel B layer R~5cm
“Low” luminosity running Lumi 1033 cm-2s-1
Only 30fb-1 (3 years) Specialist B triggers
BUT : DAQ Bandwidthonly 100 evts/s totape for ALL
physics
ATLAS
Atlas and CMS
From N. Harnew
CIPANP2003K. HonscheidOhio State
Forward vs. Central Geometry
b production angle
b production angle
230b
100b
Multi-purpose experiments requirelarge solid angle coverage.
Central Geometry (CDF, D0, Atlas, CMS)
Dedicated B experiments can takeadvantage of
Forward geometry(BTeV, LHCb)
CIPANP2003K. HonscheidOhio State
LHCb Light No tracking stations in magnet region Reduced material budget (fringe) magnetic field in tracking
station(s)
CIPANP2003K. HonscheidOhio State
The Importance of Particle ID
Purity = 84% ; Efficiency = 90%
B0 h+h-
~17 MeV
For example: B-> +-
CIPANP2003K. HonscheidOhio State
The BTeV Detector
Beam Line
Pixel DetectorVacuum Vessel
• 60 pixel planes• inside magnet• = 5-10 m
Proper time resolution: 46 fs
PbWO4 EM Calorimeter
CLEO/BaBar/BELLE-like performance in a hadron Collider environment!
~ 5 MeV
~ 3 MeV
10500 crystals220 mm long, 28x28 mm2
Detached Vertex Trigger • Find the primary vertex• Identify tracks which miss it• Calculates the significance of detachment• For EVERY crossing
b,b/b
CIPANP2003K. HonscheidOhio State
Fully simulated bb event using Geant 3• incl. multiple scattering, hadronic interactions• decays in flight• Kalman fitter
CIPANP2003K. HonscheidOhio State
Efficiencies and TaggingFor a requirement of at least 2 tracks detached by more than 6, we trigger on only 1% of the beam crossings and achieve the following trigger efficiencies for these states (<2> int. per crossing):
efficiency; D Dilution or (Nright-Nwrong)/(Nright+Nwrong)
Effective tagging efficiency D2
Extensive study for BTeV usesOpposite sign K±
Jet ChargeSame side ± (for Bo) or K± for (Bs)
LeptonsConclusion: D2 (Bo) = 0.10, D2 (Bs) = 0.13(difference due to same side tagging)
Decay efficiency(%) Decay efficiency(%)
B +- 63 Bo K+- 63
Bs DsK 74 Bo J/ Ks 50
B- DoK- 70 Bs J/K* 68
B- Ks- 27 Bo K*
CIPANP2003K. HonscheidOhio State
The Physics Goals
There is New Physics out there: Baryon Asymmetry of Universe & by Dark MatterHierarchy problemPlethora of fundamental parameters…
B Experiments at Hadron Colliders are well positioned to:
Perform precision measurements of CKM Elements withsmall model dependence.Search for New Physics via CP phasesSearch for New Physics via Rare DecaysHelp interpret new results found elsewhere (LHC, neutrinos)Complete a broad program in heavy flavor physics
Weak decay processes, B’s, polarization, Dalitz plots, QCD…
Semileptonic decays including b
b & c quark ProductionStructure: B(s) spetroscopy, b-baryon statesBc decays
CIPANP2003K. HonscheidOhio State
Part 1: Is the CKM Picture correct?
Use different sets of measurements to define apex of triangle
(adopted from Peskin)
Also have K (CP in KL system)
Magnitudes
Bd mixing phase
Bs mixing phase
Can also measure via B-DoK-
,
CIPANP2003K. HonscheidOhio State
Measuring Using Bo
A Dalitz Plot analysis gives both sin(2) and cos(2)(Snyder & Quinn)
Measured branching ratios are:
(B = ~10-5
(B + = ~3x10-5
(B <0.5x10-5
Snyder & Quinn showed that 1000-2000 tagged events are sufficient
Not easy to measure0 reconstruction
Not easy to analyze9 parameter likelihood fit
Slow 0’s
Nearly empty( polarization)
Dalitz Plot for Bo
CIPANP2003K. HonscheidOhio State
Yields for BoBased 9.9x106 background events
Bo+-
5400 events, S/B = 4.1
Booo
780 events, S/B = 0.3
o
Background Signal
mB (GeV) mB (GeV)
Booo
CIPANP2003K. HonscheidOhio State
Our Estimate of Accuracy on
Geant simulation of Bo(for 1.4x107 s)
Example:1000 Bo signal + backgroundsWith input =77.3o
minimum 2
non-resonantnon- bkgrd
resonantnon- bkgrd
(gen)
Rres Rnon(recon)
77.3o 0.2 0.2 77.2o 1.6o
77.3o 0.4 0 77.1o 1.8o
93.0o 0.2 0.2 93.3o 1.9o
93.0o 0.4 0 93.3o 2.1o
111.0o 0.2 0.2 111.7o 3.9o
111.0o 0.4 0.2 110.4o 4.3o
CIPANP2003K. HonscheidOhio State
Bs Mixing (Vtd/Vts)
ms (~xs) = ·C where C can be calculated inside the S. M.
CDF sensitive to xs ~ 30
: Bs-> seen Expect ~ 2% after Run II
BTeV reaches sensitivity to xs of 80
in 3.2 years
6
5
4
3
2
1
CIPANP2003K. HonscheidOhio State
One of several ways to determine
BsDsK
Dsmass (GeV)
~ 6.5 MeV/c2
= 168 m
= 418 m
Bs vtx resolution (mm) Ds vtx resolution (mm)
±
• Theoretically clean, BR ~ 10-4
CIPANP2003K. HonscheidOhio State
Needed:
Hadronic trigger
K/ separation
Good proper time resolution
Sensitivity depends upon
• relative amplitudes
• strong phase difference• values of , ms s s
For ms=20 ps–1:
1010oo
For ms=30 ps–1:
1212oo
In one year: 8k BsDsK reconstructed
events
from Bs D-s K+ , D+
s K-
(II)
From the measurement of 4 time-dependent asymmetries one gets
same order tree level amplitudes (3) : large asymmetries, NP contributes unlikely
From M. Musy
CIPANP2003K. HonscheidOhio State
Measuring In the SM the phases and magnitudes are correlated:
|Vus| = 0.2205±0.0018
is the phase of Vts -> Bs Mixing
Good: Bs->J/ plus non-trivial angular analysisBetter: Bs -> CP eigenstate such as
BsJ/
2 sin sinsin
sin( + )
Silva & Wolfenstein (hep-ph/9610208)Aleksan, Kayser & London
CIPANP2003K. HonscheidOhio State
Measuring II
BTeV can reconstruct and ’
Yield in one yearBsJ/2,800 events with S/B = 15
BsJ/9,800 events with S/B = 30
Error on sin(2 = 0.024
With ~ 2o a precision measurement will require a few years.
CIPANP2003K. HonscheidOhio State
Physics Reach (CKM) in 107 s Reaction B(B)
(x10-6)# of Events
S/B Parameter Error or (Value)
Bs Ds K- 300 7500 7 - 8o
Bs Ds- 3000 59,000 3 xs (75)
BoJ/KS J/+ - 445 168,000 10 sin(2) 0.017
BoJ/Ko, Ko 7 250 2.3 cos(2) ~0.5
B-Do (K+-) K- 0.17
170 1
B-Do (K+K-) K- 1.1 1,000 >10 13o
BsJ/ 330 2,800 15
BsJ/ 670 9,800 30 sin(2 0.024
Bo+- 28 5,400 4.1
Booo 5 780 0.3 ~4o Reaction B(B)
(x10-6)# of Events
S/B Parameter Error
B-KS -
12.1 4,600 1 <4o +
BoK+- 18.8
62,100 20 Theory err.
Bo+- 4.5 14,600 3 Asymmetry 0.030
BoK+ K- 17 18,900 6.6 Asymmetry 0.020
CIPANP2003K. HonscheidOhio State
LHCb preliminary study
(ppBc) ~300 nb 109 Bc/ year
Bc J/BR ~10-2)
~ 2% 12k events/year
Background from B J/X and prompt
J/reduced cutting on the distance between primary vertex and Bc vertex
BBc c mesons mesons
CDF: mBc = 6.4 +/- 0.4 GeV tBc ~ 0.5 ps
BTeV/LHCb: Precisionmeasurements of mass, lifetimeSearch for CPV in Bc -> J/D+
or Bc -> DsD
LHCb acceptance ~30%
M( J/GeV/c2
p (GeV)
CIPANP2003K. HonscheidOhio State
Part II: Search for New Physics
For a nice overview see: S. Stone “BTeV Physics” athttp://doe-hep.hep.net/P5StoneMarch2003.pdf
CIPANP2003K. HonscheidOhio State
First Example: Supersymmetry
Supersymmetry: In general 80 constants & 43 phasesMSSM: 2 phases (Nir, hep-ph/9911321)
New Physics in Bo mixing: D , Bo decay: A, Do
mixing: K
Process Quantity SM New Physics
BoJ/Ks CP asym sin(2) sin2(D)
BoKs CP asym sin(2) sin2(DA)
DoK-+ CP asym 0 ~sin(K)
New Physics
Difference NP
CIPANP2003K. HonscheidOhio State
Rare b Decays Search for New Physics in Loop diagrams
New fermion like objects in addition to t, c or uNew Gauge-like objects in addition to W, Z or g
Inclusive Rare Decays including bs bd bs+
Exclusive Rare Decays such as BBK*+ Dalitz plot & polarization
+-
BoK*
CIPANP2003K. HonscheidOhio State
Yield, S/B for Rare b Decays
Reaction B (10-6) Signal S/B Physics
BoK*o+- 1.5 2530 11 Polarization; Rate
B-K-+- 0.4 1470 3.2 Rate
bs+- 5.7 4140 0.13 Rate; Wilson coefficents
CIPANP2003K. HonscheidOhio State
BTeV data compared to Burdman et al calculation
Dilepton invariant mass distributions,forward-backward asymmetrydiscriminate among the SM and various supersymmetric theories.(Ali, Lunghi, Greub & Hiller, hep-ph/0112300)
One year for K*+-, enough to determine if New Physics is present
Polarization in BoK*o+-
Ali et. al, hep-ph/9910221
CIPANP2003K. HonscheidOhio State
Search also for Bd0
Standard Model BR ~ 1x10-10
Bs0
Standard Model BR ~ 4x10-9
Here the General Purpose Detectorshave an advantage : high pT di-muontriggering at high (1x1034) luminosity.
CMS : 100 fb-1 (107s at 1034 cm-2s-
1) ~26 signal events6.4 events background
Muon trigger :2 ’s with pT > 4 GeV< 2.4
Rare Leptonic Decays
CIPANP2003K. HonscheidOhio State
Another Example: Extra Dimensions
Aranda & Lorenzo Diaz-Cruz, “Flavor Symmetries in Extra Dimensions” (hep-ph/0207059) (Buras et al. hep-ph/0212143) Extra spatial dimension is compactified at scale 1/R = 250 GeV on upNo effect on |Vub/Vcb|, Md/Ms , sin(2)
–8%–100
+72%|Vtd|
Bs ->
CIPANP2003K. HonscheidOhio State
Summary
Heavy quark physics at hadron colliders provides a unique opportunity to
measure fundamental parameters of the Standard Model with no or only small model dependencediscover new physics in CP violating amplitudes or rare decays.interpret new phenomena found elsewhere (e.g. LHC)
Some scenarios are clear others will be a surprise
This program requires a general purpose B detector like BTeV and LHCb with
an efficient, unbiased trigger and a high performance DAQa superb charged particle tracking systemgood particle identificationexcellent photon detection
CIPANP2003K. HonscheidOhio State
Additional Transparenciesfrom BTeV and LHCb Studies
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from Bfrom Bss J/J/
In SM S 10-
2 Sensitive to New Physics effects
in the Bs-Bs system In one year:
109 k events Bs J/
19 k events Bs J/e+e
J/is not CP eigenstate:
needs fit to angular distributions of decay final states as a function of proper time
Assuming ms=20 ps–1:
22oo
36±1 fs
From M. Musy
CIPANP2003K. HonscheidOhio State
Current status of LHCb Physics Reach in 1 year (2fb–1)
Channel Yield Precision*
Bd J/Ks 119 k 0.6o
Bs DsK
Bd , Bs KK8 k
27 k, 35 k 10o
3o
Bd 27 k 5o- 10o
Bs J/ 128 k 2o
|Vtd/Vts Bs Ds 72 k ms up to 58 ps
rare decays Bd K 20 k
All numbers will be updated together with more channels in the re-optimization LHCb TDR (September 2003)
From M. Musy
CIPANP2003K. HonscheidOhio State
A simplified trigger comparison
From U. Egede
CIPANP2003K. HonscheidOhio State
Unitarity TrianglesUnitarity Triangles
Bd0
Bd0
Bd0 DK*0
BS0 DSK
Bd0 D*
BS0 DS
Bd0 J/ KS
0
BS0 J/
From N. Harnew
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