The Future of Flavor Physics
at Hadron Colliders
CIPANP 2003
K. Honscheid
Ohio State University
CIPANP2003
K. Honscheid
Ohio State
B Physics Today
CKM Picture okay
VCKM =
Vud
Vus
Vub
Vcd
Vcs
Vcb
Vtd
Vts
Vtb
CP Violation observed
sin(2b) = 0.734 +/- 0.054
No conflict with SM
CIPANP2003
K. Honscheid
Ohio State
Surprising B Physics
Year
Item
1983
tb
1987
2001
Theory Prediction
~Value
# B’s
Too small to be observed ~ < 0.1ps
1 ps
2x104
Bo-Bo
mixing
Too small to see (~ < 1%) as mtop is
believed to be ~30 GeV
20%
2x105
sin(2b)
No direct prediction, but consistent
with other measurements
3/4
107
a,b,g
>1011 b hadrons
(including Bs)
CIPANP2003
K. Honscheid
Ohio State
B Physics at Hadron Colliders
Energy
b cross section
c cross section
b fraction
Inst. Luminosity
Bunch spacing
Int./crossing
Luminous region
Tevatron
LHC
2 TeV
~100 mb
~1000 mb
2x10-3
2x1032
132 ns (396 ns)
<2> (<6>)
30 cm
14 TeV
~500 mb
~3500 mb
6x10-3
>2x1032
25 ns
<1>
5.3 cm
Large cross sections
Triggering is an issue
All b-hadrons produced (B, Bs, Bc, b-baryons)
CIPANP2003
K. Honscheid
Ohio State
Detector Requirements
CIPANP2003
K. Honscheid
Ohio State
•Vertex, decay distance
•Momentum
•PID
•Neutrals (g, p0)
From F. Teubert
CDF and D0
CDF pioneered B physics at
hadron collider.
New for Run II
TOF (Particle ID)
Detached Vertex Trigger
Improved tracking
D0 enters B physics
New for Run II
Tracking
Detached Vertex Trigger (soon)
CIPANP2003
K. Honscheid
Ohio State
Atlas and CMS






CIPANP2003
K. Honscheid
Ohio State
Acceptance
 |h| < 2.5
Particle ID
 ATLAS v.limited p-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 Bandwidth
only 100 evts/s to
tape for ALL physics
ATLAS
From N. Harnew
Forward vs. Central Geometry
Multi-purpose experiments require
large solid angle coverage.
Central Geometry
(CDF, D0, Atlas, CMS)
Dedicated B experiments can take
advantage of
Forward geometry
(BTeV, LHCb)
bg
CIPANP2003
K. Honscheid
Ohio State
100mb
230mb
LHCb Light



CIPANP2003
K. Honscheid
Ohio State
No tracking stations in magnet region
Reduced material budget
(fringe) magnetic field in tracking station(s)
The Importance of Particle ID
For example: B-> p+p-
B0  h+hs ~17 MeV
Purity = 84% ; Efficiency = 90%
CIPANP2003
K. Honscheid
Ohio State
The BTeV Detector
Pixel Detector
Detached Vertex Trigger
Vacuum Vessel
• Find the primary vertex
PbWO
Calorimeter
4 EM
• Identify
tracks
which miss it
• Calculates the significance of detachment
• For EVERY crossing
10500 crystals
220 mm long, 28x28 mm2
Beam Line
b,b/sb
s(h->gg) ~ 5 MeV
Proper time resolution: 46 fs
s(p->gg) ~ 3 MeV
CIPANP2003
K. Honscheid
Ohio State
CLEO/BaBar/BELLE-like performance
in a hadron Collider environment!
• 60 pixel planes
• inside magnet
• s = 5-10 mm
Fully simulated bb event using Geant 3
• incl. multiple scattering, hadronic interactions
• decays in flight
• Kalman fitter
CIPANP2003
K. Honscheid
Ohio State
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):
Decay
efficiency(%)
B  p+p63
Bs  DsK
74
B-  DoK70
B-  Ksp27
CIPANP2003
K. Honscheid
Ohio State
Decay efficiency(%)
Bo  K+p63
Bo  J/y Ks
50
Bs  J/yK*
68
Bo  K*g
40
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)
The Physics Goals
There is New Physics out there:
Baryon Asymmetry of Universe & by Dark Matter
Hierarchy problem
Plethora of fundamental parameters
…
B Experiments at Hadron Colliders are well positioned 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(s) spetroscopy, b-baryon states
Bc decays
CIPANP2003
K. Honscheid
Ohio State
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-
,
CIPANP2003
K. Honscheid
Ohio State
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-)
Nearly empty
(r polarization)
~10-5
=
B(Bor-p+ + r+p-) = ~3x10-5
B(Boropo) <0.5x10-5
Snyder & Quinn showed that
1000-2000 tagged events are
sufficient
Not easy to measure
p0 reconstruction
Not easy to analyze
9 parameter likelihood fit
CIPANP2003
K. Honscheid
Ohio State
Slow p0’s
Dalitz Plot for Borp
Yields for Borp
Based 9.9x106 background events
Bor+p5400 events, S/B = 4.1
Boropo
780 events, S/B = 0.3
Background
p
o
CIPANP2003
K. Honscheid
Ohio State
g
Boropo
Signal
g
mB (GeV)
mB (GeV)
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
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
minimum c2
Example:
1000 Borp signal + backgrounds
With input a=77.3o
CIPANP2003
K. Honscheid
Ohio State
non-resonant
non-rp bkgrd
resonant
non-rp bkgrd
Bs Mixing (Vtd/Vts)
Dms (~xs) = DG·C where C can be calculated inside the S. M.
CDF sensitive to xs ~ 30
DG/G: Bs->yf seen
Expect s(DG/G) ~ 2% after Run II
6
5
4
BTeV reaches sensitivity to xs of 80
in 3.2 years
CIPANP2003
K. Honscheid
Ohio State
3
2
1
One of several ways to determine g: BsDs±K
• Theoretically clean, BR ~ 10-4
s ~ 6.5
MeV/c2
s = 168
mm
CIPANP2003
K. Honscheid
Ohio State
Ds mass (GeV)
Bs vtx resolution (mm)
s = 418
mm
Ds vtx resolution (mm)
g from
Bs  D-s K+ , D+s K- (II)
Needed:
 Hadronic trigger
 K/p separation
 Good proper time
resolution
 From the measurement of 4 time-dependent
asymmetries one gets g-2dg
 2 same order tree level amplitudes (3) :
large asymmetries, NP contributes unlikely
Sensitivity depends upon
• relative amplitudes
• strong phase difference
• values of g, Dms , DGs /Gs
For Dms=20 ps–1:
s(g) ~ 10o
For Dms=30 ps–1:
s(g) ~ 12o
CIPANP2003
K. Honscheid
Ohio State
In one year: 8k BsDsK reconstructed events
From M. Musy
Measuring c
In the SM the phases and magnitudes are correlated:
sinb sing
sin c = 
sin(b+g )
2
Silva & Wolfenstein (hep-ph/9610208)
Aleksan, Kayser & London
 = |Vus| = 0.2205±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
CIPANP2003
K. Honscheid
Ohio State
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.
CIPANP2003
K. Honscheid
Ohio State
Physics Reach (CKM) in 107 s
Reaction
B(B)
(x10-6)
S/B
Parameter
Error or
(Value)
Bs Ds K-
300
7500
7
g - 2c
8o
Bs Ds p-
3000
59,000
3
xs
(75)
445
168,000
10
7
250
2.3
B-Do (K+p-) K-
0.17
170
1
B-Do (K+K-) K-
1.1
1,000
>10
BoJ/y KS
J/y l+ l -
BoJ/y Ko, Ko  p l n
BsJ/y h,
330
2,800
15
BsJ/y h
670
9,800
30
Bor+p-
28
5,400
4.1
Boropo
5
780
0.3
Reaction
B(B)
(x10-6)
CIPANP2003
K. Honscheid
Ohio State
# of
Events
# of
Events
S/B
sin(2b)
0.017
cos(2b)
~0.5
13o
g
sin(2c)
0.024
a
~4o
Parameter
Error
B-KS p-
12.1
4,600
1
BoK+p-
18.8
62,100
20
Bop+p-
4.5
14,600
3
Asymmetry
0.030
BoK+ K-
17
18,900
6.6
Asymmetry
0.020
<4o +
g
Theory err.
Bc mesons
CDF: mBc = 6.4 +/- 0.4 GeV
tBc ~ 0.5 ps
BTeV/LHCb: Precision
measurements of mass, lifetime
Search for CPV in Bc -> J/yD+
or Bc -> DsD
LHCb acceptance ~30%
p (GeV)
LHCb preliminary study
s(ppBc) ~300 nb  109 Bc/ year
Bc  J/y p (BR ~10-2)
e ~ 2%
CIPANP2003
K. Honscheid
Ohio State
12k events/year
Background from B  J/y X and prompt
J/y reduced cutting on the distance
between primary vertex and Bc vertex
M( J/y(mm) p) GeV/c2
Part II: Search for New Physics
CIPANP2003
K. Honscheid
Ohio State
For a nice overview see: S. Stone “BTeV Physics” at
http://doe-hep.hep.net/P5StoneMarch2003.pdf
First Example: Supersymmetry
Supersymmetry: In general 80 constants & 43 phases
MSSM: 2 phases (Nir, hep-ph/9911321)
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
CP asym
sin(2b)
sin2(b+qD+qA)
DoK-p+
CP asym
0
~sin(fKp)
New Physics
CIPANP2003
K. Honscheid
Ohio State
Difference
 NP
Rare b Decays
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
g, l+l-
bsg
bdg
bsl+l-
Exclusive Rare Decays such as
Brg, K*g
BK*l+lDalitz plot & polarization
CIPANP2003
K. Honscheid
Ohio State
BoK*g
Yield, S/B for Rare b Decays
Reaction
CIPANP2003
K. Honscheid
Ohio State
B (10-6)
Signal
S/B
11
BoK*om+m-
1.5
2530
B-K-m+m-
0.4
1470
3.2
bsm+m-
5.7
4140
0.13
Physics
Polarization; Rate
Rate
Rate;
Wilson coefficents
Polarization in BoK*om+mBTeV data compared to Burdman et al calculation
Dilepton invariant mass distributions,
forward-backward asymmetry
discriminate among the SM and
various supersymmetric theories.
Ali et. al, hep-ph/9910221
(Ali, Lunghi, Greub & Hiller, hep-ph/0112300)
CIPANP2003
K. Honscheid
Ohio State
One year for K*l+l-, enough to determine if New Physics is present
Rare Leptonic Decays
Bs0  m+mStandard Model BR ~ 4x10-9
Here the General Purpose Detectors
have an advantage : high pT di-muon
triggering at high (1x1034) luminosity.
CMS : 100 fb-1 (107s at 1034 cm-2s-1)
~26 signal events
6.4 events background
Muon trigger :
2 m’s with pT > 4 GeV
| h| < 2.4
CIPANP2003
K. Honscheid
Ohio State
Search also for Bd0  m+mStandard Model BR ~ 1x10-10
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
up
No effect on |Vub/Vcb|, DMd/DMs , sin(2b)
Bs -> mm
–8%
|Vtd|
CIPANP2003
K. Honscheid
Ohio State
–100
g
+72%
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 B detector like
BTeV and LHCb with
an efficient, unbiased trigger and a high performance DAQ
a superb charged particle tracking system
good particle identification
excellent photon detection
CIPANP2003
K. Honscheid
Ohio State
Additional Transparencies
from BTeV and LHCb Studies
CIPANP2003
K. Honscheid
Ohio State
dg (= c) from B
s
 J/y f
 In SM fS = -2dg = -22h ~10-2
 Sensitive to New Physics effects
in the Bs-Bs system
In one year:
109 k events Bs J/y (m+m-) f
19 k events Bs J/y (e+e-) f
J/y f is not CP eigenstate:
needs fit to angular distributions
of decay final states as a function
of proper time
s =36±1 fs
Assuming Dms=20 ps–1:
s (2dg) ~ 2o
CIPANP2003
K. Honscheid
Ohio State
From M. Musy
Current status of LHCb Physics Reach in 1 year (2fb–1)
Channel
Yield
Precision*
119 k
s(b)  0.6o
8k
27 k, 35 k
s(g) 10o
s(g)  3o
b
Bd  J/y Ks
g
Bs  Ds K
Bd  pp, Bs  KK
a
Bd  p+p-
27 k
s(a)  5o- 10o
2dg
Bs  J/y f
128 k
s(2dg)  2o
|Vtd/Vts|
Bs  Ds p
72 k
Dms up to 58 ps-1
rare decays
Bd  K * g
20 k
All numbers will be updated together with more channels
in the re-optimization LHCb TDR (September 2003)
CIPANP2003
K. Honscheid
Ohio State
From M. Musy
A simplified trigger comparison
CIPANP2003
K. Honscheid
Ohio State
From U. Egede
Unitarity Triangles
Bd0  p+ pBd0  r p
BS0  DS p
Bd0  DK*0
BS0  DSK
Bd0  D* p, 3p
Bd0  J/y KS0
dg = c
CIPANP2003
K. Honscheid
Ohio State
BS0  J/y f
From N. Harnew