1. BTeV Physics Reach LHC 2003 Symposium K. Honscheid
Ohio State University
LHC2003 K. Honscheid
Ohio State

2. B Physics Today CKM Picture okay CP Violation observed
No conflict with SM
Vud
Vus
Vub
VCKM =
Vcd
Vcs
Vcb
Vtd
Vts
Vtb
sin(2b) = /
LHC2003 K. Honscheid
Ohio State

3. Surprising B Physics tb Year Item Theory Prediction ~Value # B’s 1983
Too 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(2b)
No direct prediction, but consistent with other measurements
3/4
107
a,b,g
>1011 b hadrons
(including Bs)
LHC2003 K. Honscheid
Ohio State

4. B Physics at Hadron Colliders
The Tevatron as b (and c) source
b cross section ~100 mb, c cross section ~1000 mb
b fraction 2x10-3
Inst. Luminosity 2x1032
Bunch spacing 132 ns (396 ns)
Int./crossing <2> (<6>)
Luminous region sz = 30 cm
Forward Geometry
2x1011 b pairs/year bg
b production angle
b production angle
LHC2003 K. Honscheid
Ohio State

5. The BTeV Detector Pixel Detector RICH Detector PbWO4 EM Calorimeter
Beam Line
Pixel Detector
Vacuum Vessel
60 pixel planes
inside magnet
s = 5-10 mm
Proper time resolution: 46 fs
RICH Detector
Gas (C4F10) + Liquid Radiator (C5F12)
HPD + PMT read-out
p/K/p separation up to 70 GeV/c
e/m separation at low momenta
PbWO4 EM Calorimeter
CLEO/BaBar/BELLE-like performance
in a hadron Collider environment!
s(h->gg) ~ 5 MeV
s(p->gg) ~ 3 MeV
10500 crystals
220 mm long, 28x28 mm2
LHC2003 K. Honscheid
Ohio State

6. Efficiencies and Tagging
For a requirement of at least 2 tracks detached by more than 6s, we trigger on only 1% of the beam crossings and achieve the following trigger efficiencies for these states (<2> int. per crossing):
e  efficiency; D  Dilution or (Nright-Nwrong)/(Nright+Nwrong)
Effective tagging efficiency  eD2
Extensive study for BTeV uses
Opposite sign K±
Jet Charge
Same side p± (for Bo) or K± for (Bs)
Leptons
Conclusion: eD2 (Bo) = 0.10, eD2 (Bs) = 0.13, difference due to same side tagging
Decay efficiency(%) Decay efficiency(%)
B  p+p Bo  K+p
Bs  DsK Bo  J/y Ks
B-  DoK Bs  J/yK*
B-  Ksp Bo  K*g
B->pipi efficiency = 0.04 (reconstruction) x 0.82 (PID) x 0.55 (L1+L2) = 1.8%
LHC2003 K. Honscheid
Ohio State

7. The Physics Goals There is New Physics out there:
Baryon Asymmetry of Universe & by Dark Matter
Hierarchy problem
Plethora of fundamental parameters …
BTeV is in a unique position to:
Perform precision measurements of CKM Elements with small model dependence.
Search for New Physics via CP phases
Search for New Physics via Rare Decays
Help 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 Lb
b & c quark Production
Structure: B baryon states
Bc decays
LHC2003 K. Honscheid
Ohio State

8. Part 1: Is the CKM Picture correct?
Use different sets of measurements to define apex of triangle
(adopted from Peskin)
Also have eK (CP in KL system)
Bd mixing phase
Magnitudes
Bs mixing phase
Can also measure g via B-DoK-
LHC2003 K. Honscheid
Ohio State

9. Measuring a Using Borp  p+p-po
A Dalitz Plot analysis gives both sin(2a) and cos(2a) (Snyder & Quinn)
Measured branching ratios are:
B(B-rop-) = ~10-5
B(Bor-p+ + r+p-) = ~3x10-5
B(Boropo) <0.5x10-5
Snyder & Quinn showed that tagged events are sufficient
Not easy to measure
p0 reconstruction
Not easy to analyze
9 parameter likelihood fit
Nearly empty
(r polarization)
Slow p0’s
Dalitz Plot for Borp
LHC2003 K. Honscheid
Ohio State

10. Yields for Borp Signal Background Based 9.9x106 background events
Bor+p events, S/B = 4.1
Boropo events, S/B = 0.3
Boropo
Background
Signal
Get updated plots, to have better S/B numbers po g g
LHC2003 K. Honscheid
Ohio State
mB (GeV)
mB (GeV)

11. Our Estimate of Accuracy on a
Geant simulation of Borp, (for 1.4x107 s)
a (gen)
Rres
Rnon
a (recon) Da
77.3o
0.2
77.2o
1.6o
0.4
77.1o
1.8o
93.0o
93.3o
1.9o
2.1o
111.0o
111.7o
3.9o
110.4o
4.3o
minimum c2
non-resonant
non-rp bkgrd
resonant
Example:
1000 Borp signal + backgrounds
With input a=77.3o
LHC2003 K. Honscheid
Ohio State

12. Bs Mixing (Vtd/Vts) BTeV reaches sensitivity to xs of 80 in 3.2 years6 5 4 3 2 1
LHC2003 K. Honscheid
Ohio State

13. c is the phase of Vts -> Bs Mixing
Measuring c
In the SM the phases and magnitudes are correlated:
l = |Vus| = ±0.0018
c is the phase of Vts -> Bs Mixing
Good: Bs->J/yf plus non-trivial angular analysis
Better: Bs -> CP eigenstate such as BsJ/yh() , hgg, hrg
Silva & Wolfenstein (hep-ph/ ) Aleksan, Kayser & London
LHC2003 K. Honscheid
Ohio State

14. Measuring c II BTeV can reconstruct h and h’ Yield in one year
BsJ/y h: 2,800 events with S/B = 15
BsJ/y h: 9,800 events with S/B = 30
Error on sin(2c) = 0.024
With c ~ 2o a precision measurement will require a few years.
LHC2003 K. Honscheid
Ohio State

15. 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
g - 2c 8o
Bs Ds p-
3000
59,000 3 xs
(75)
BoJ/y KS J/y l+ l -
445
168,000 10
sin(2b)
0.017
BoJ/y Ko, Ko  p l n
250
2.3
cos(2b)
~0.5
B-Do (K+p-) K-
0.17
170 1
B-Do (K+K-) K-
1.1
1,000
>10 g
13o
BsJ/y h,
330
2,800 15
BsJ/y h
670
9,800 30
sin(2c)
0.024
Bor+p- 28
5,400
4.1
Boropo 5
780
0.3 a
~4o
Point out that there are several ways to measure gamma, so can resolve ambiguities; other ways of resolving ambiguities in beta.
Error estimate on alpha is a guess. Can do better on chi by using electron modes.
Reaction
B(B) (x10-6)
# of Events
S/B
Parameter
Error
B-KS p-
12.1
4,600 1
<4o +
BoK+p-
18.8
62,100 20 g
Theory err.
Bop+p-
4.5
14,600 3
Asymmetry
0.030
BoK+ K- 17
18,900
6.6
0.020
LHC2003 K. Honscheid
Ohio State

16. Part II: Search for New Physics
For a nice overview see: S. Stone “BTeV Physics” at
LHC2003 K. Honscheid
Ohio State

17. First Example: Supersymmetry
Supersymmetry: In general 80 constants & 43 phases
MSSM: 2 phases (Nir, hep-ph/ )
New Physics in Bo mixing: qD , Bo decay: qA, Do mixing: fKp
Process
Quantity SM
New Physics
BoJ/yKs
CP asym
sin(2b)
sin2(b+qD)
BofKs
sin2(b+qD+qA)
DoK-p+
~sin(fKp)
Difference
 NP
New Physics
LHC2003 K. Honscheid
Ohio State

18. Rare b Decays g, l+l- Search for New Physics in Loop diagrams
New fermion like objects in addition to t, c or u
New Gauge-like objects in addition to W, Z or g
Inclusive Rare Decays including
bsg
bdg
bsl+l-
Exclusive Rare Decays such as
Brg, K*g
BK*l+l- Dalitz plot & polarization
g, l+l-
LHC2003 K. Honscheid
Ohio State
BoK*g

19. Yield, S/B for Rare b Decays
Reaction
B (10-6)
Signal
S/B
Physics
BoK*om+m-
1.5
2530 11
Polarization; Rate
B-K-m+m-
0.4
1470
3.2
Rate
bsm+m-
5.7
4140
0.13
Rate;
Wilson coefficents
Discovery potential here
LHC2003 K. Honscheid
Ohio State

20. Polarization in BoK*om+m-
BTeV data compared to Burdman et al calculation
Dilepton invariant mass distributions, forward-backward asymmetry discriminate among the SM and various supersymmetric theories. (Ali, Lunghi, Greub & Hiller, hep-ph/ )
One year for K*l+l-, enough to determine if New Physics is present
Ali et. al, hep-ph/
LHC2003 K. Honscheid
Ohio State

21. Second Example: Extra Dimensions
Aranda & Lorenzo Diaz-Cruz, “Flavor Symmetries in Extra Dimensions” (hep-ph/ ) (Buras et al. hep-ph/ )
Extra spatial dimension is compactified at scale 1/R = 250 GeV on up
No effect on |Vub/Vcb|, DMd/DMs , sin(2b)
Bs -> mm
–100
–8% g
+72%
|Vtd|
LHC2003 K. Honscheid
Ohio State

22. 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 dependence
discover 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 detector like BTeV with
an efficient, unbiased trigger and a high performance DAQ
a superb charged particle tracking system
good particle identification
excellent photon detection
LHC2003 K. Honscheid
Ohio State

23. Changes wrt Proposal in Event Yields & Sensitivities
We lost one arm, factor = 0.5
We gained on dileptons
From RICH ID
in proposal we used only m+m-, now we include e+e-
factor = 2.4 (or 3.9), depending on whether analysis used single (dilepton) id
We gained on DAQ bandwidth, factor = 1.15
Gained on eD2 for Bs only, factor = 1.3
Mode
Yield
proposal
factor
one-arm
Quantity
Err(prop) (eD2)
Err(1arm) (eD2)
BoJ/y Ks
80,500
0.5*3.9*
1.15=2.24
168,000
sin(2b)
(0.10)
0.017 (0.10)
BsJ/yh()
9,940
0.5*2.4*
1.15=1.38
12,600
sin(2c)
0.033 (0.10)
0.024 (0.13)
Bs Ds K-
13,100
0.5*1.15
=0.58
7,500 g
6o (0.10)
8o (0.13)
LHC2003 K. Honscheid
Ohio State