B physics
BaBar/PEP-II
Belle/KEK-B
CDF & D0/Tevatron
LHCb, ATLAS & CMS/LHC
Super B Factory/???
ALL RESULTS ARE PRELIMINARY UNLESS PUBLISHED
Tim Gershon, IoP Particle Physics 2006
1
Apologies
Due to shortness of time, I will cover only a selection
of B physics, and skip entirely many other important
results
D physics: mixing & rare decays
Spectroscopy: observations & interpretations of new states
τ physics: new limits on lepton flavour violation
ISR physics, γγ physics, spin physics, ...
Theoretical developments
For details see review talks at (ongoing) FPCP
http://fpcp2006.triumf.ca/agenda.php
Tim Gershon, IoP Particle Physics 2006
2
The (SM) physics
Electroweak symmetry breaking
Higgs field acquires vacuum expectation value
diagonalization of quark mass matrix
charged current → flavour mixing (CKM)
no tree-level flavour changing neutral currents (GIM)
CKM matrix (3 mixing angles & 1 phase)
responsible for all quark mixing & CP violation
phenomena
Most of SM free parameters are in flavour sector
Tim Gershon, IoP Particle Physics 2006
3
CKM matrix
Tim Gershon, IoP Particle Physics 2006
4
Unitarity Triangle
Convenient method to illustrate (dis-)agreement
of observables with CKM prediction
Tim Gershon, IoP Particle Physics 2006
5
All measurements must agree
KM Prediction
Tim Gershon, IoP Particle Physics 2006
Im
α
γ J/2 β
Re
Picture by A.Hoecker
6
Overconstraining the UT
Test SM via multiple redundant measurements of
UT parameters
3 angles ((β,α,γ) = (φ1,φ2,φ3)) & 2 sides (Ru & Rt)
β : TDCPV in B0 → J/ψ KS, B0 → φKS, many others
0
α : TDCPV in B → hh' (h,h' = π/ρ/...)
γ : DCPV in B → hh' (h,h' = π/K/...);
DCPV in B → DK; TDCPV in B0 → D*π; and more
Ru : rates & spectra in B → Xulν; rates of B+ → l+ν
Rt : mixing (Δmd/Δms); rates of B → ργ, ...
Tim Gershon, IoP Particle Physics 2006
7
Direct CP Violation
B
B
A
A
Direct CP violation if
f
f
A
≠1
A
∣∣
Requires
A =∑ A i =∑ ∣ A i∣ e
i
i≥2
Tim Gershon, IoP Particle Physics 2006
i  i i 
i
i ≠ j
i ≠ j
8
Time Dependent CP Violation
0
0
B
=
p
∣
B
⟩

q
∣
B
⟩
∣ L⟩
∣BL ⟩ =p∣B0 ⟩ −q∣B0 ⟩
2
B
0
B
0
A
2
∣p∣ ∣q∣ =1
 m =m  B H −m  B L 
 =  B H −  BL 
A
f = ± f = f CP
q
≠1 (cf. εK)
CP violation in mixing if
p
q A
≠1
Time-dependent CP violation if ℑ
p A
(interference between mixing and decay)
∣∣
 
Tim Gershon, IoP Particle Physics 2006
9
Asymmetric B Factory Concept
PCP   t , q tag =
Direct CP violation
−∣t∣/ B
e
1± q tag  SCP sin  m  t −CCP cos  m  t  

4 B
SJ / K
S
q A
=ℑ
= −CP sin 2  = sin 2 
pA
 
Formulation assumes
negligible ΔΓ & CPT conservation
Tim Gershon, IoP Particle Physics 2006
10
Asymmetric B Factories
PEPII at SLAC
9.0 GeV e- on 3.1 GeV e+
Tim Gershon, IoP Particle Physics 2006
KEKB at KEK
8.0 GeV e- on 3.5 GeV e+
11
B factory Luminosities
0.5 ab-1
PEP-II : Total 330.2 fb-1
~220 x 106 BB pairs
KEK-B : Total 563.3 fb-1
TODAYS RESULTS
Tim Gershon, IoP Particle Physics 2006
~385 x 106 BB pairs
12
Luminosity trends
34
2
L > 10 /cm /s
Tim Gershon, IoP Particle Physics 2006
13
BaBar Detector
1.5 T solenoid
DIRC (PID)
144 quartz bars
11000 PMs
e­ (9 GeV)
Instrumented Flux Return
iron / RPCs (muon / neutral hadrons)
2/6 replaced by LST in 2004
Rest of replacement in 2006
Tim Gershon, IoP Particle Physics 2006
EMC
6580 CsI(Tl) crystals
e+ (3.1 GeV)
Drift Chamber
40 stereo
layers
Silicon Vertex Tracker
5 layers, double sided
strips
14
Belle Detector
SC solenoid
1.5T
CsI(Tl)
16X0
Aerogel Cherenkov cnt.
n=1.015~1.030
3.5 GeV e+
TOF counter
8 GeV e−
Central Drift Chamber
small cell +He/C2H6
Si vtx. det.
- 3 lyr. DSSD
- 4 lyr. since summer 2003
Tim Gershon, IoP Particle Physics 2006
µ / KL detection
14/15 lyr. RPC+Fe
15
The Golden Mode
BaBar
PRL 94, 161803 (2005)
Tim Gershon, IoP Particle Physics 2006
BELLE-CONF-0569
16
Compilation of Results
Tim Gershon, IoP Particle Physics 2006
17
Constraint from β
Tim Gershon, IoP Particle Physics 2006
18
Other modes for β
B0 → J/ψ K* time-dependent angular analysis
determine sign of cos(2β)
B0 → D(*)+D(*)-KS time-dependent (amplitude) analysis
determine sign of cos(2β) (eventually)
B0 → J/ψ π0, D(*)+D(*)- TDCPV
β(b → ccd) = β(b → ccs) ?
B0 → Dπ0, etc. time-dependent amplitude analysis
β(b → cud) = β(b → ccs) ?
with D → KSπ+π-, determine sign of cos(2β)
B0 → φKS, etc. time-dependent analysis
β(b → sqq) = β(b → ccs) ? more later ...
Tim Gershon, IoP Particle Physics 2006
19
Other modes for β
B0 → J/ψ K* time-dependent angular analysis
r
determine sign of cos(2β)
a
aB
0
(*)+ (*)B
B → D D KS time-dependent (amplitude) analysis
m
o
r
f
s
t
determine sign of cos(2β) (eventually) resul
W
E
B0 → J/ψ π0, D(*)+D(*)- TDCPV
N
β(b → ccd) = β(b → ccs) ?
lle
e
B
0
0
B → Dπ , etc. time-dependent amplitude analysis
rom
f
s
t
l
u
β(b → cud) = β(b → ccs) ?
s
e
r
+ W
with D → KSπ π , determine sign of cos(2β)
NE
B0 → φKS, etc. time-dependent analysis
β(b → sqq) = β(b → ccs) ? more later ...
Tim Gershon, IoP Particle Physics 2006
20
Measurement of α
B0 → π+πboth tree and penguin contributions
large possible DCPV & S  ≠−sin 2
isospin ⇒ Grossman-Quinn type bounds

 S

−
−
− [ −sin 2 ]

0
0 0


B

B


max
y ary
c
n ss
a
p ce
e
r
c ne
s
i
d lts
e
u
s
m
e
So d r
e
t
da
p
U
Tim Gershon, IoP Particle Physics 2006
21
Measurement of α
B0 → π+π-π0
decays mainly via intermediate ρ resonances
time-dependent Dalitz plot analysis
⇒ separate penguin from tree contribution
B0 → ρ+ρalmost 100% longitudinal polarization (CP even)
small penguin contribution S  ≃−sin 2 
accuracy on α still limited by (lack of) knowledge
of B0 → ρ0ρ0 and B+ → ρ+ρ0

Tim Gershon, IoP Particle Physics 2006
−
22
Measurement of α
B0 → π+π-π0
decays mainly via intermediate ρ resonances
time-dependent Dalitz plot analysis
⇒ separate penguin from tree contribution
B0 → ρ+ρalmost 100% longitudinal polarization (CP even)
small penguin contribution S  ≃−sin 2 
r
accuracy on α still limited by (lack of)
aknowledge
B
Ba
0
0 0
+
+ 0
of B → ρ ρ and B → ρ ρ
rom
f
s

Tim Gershon, IoP Particle Physics 2006
W
NE
−
ult
s
re
23
Constraint on α
α = (99+13-8)°
Tim Gershon, IoP Particle Physics 2006
24
DCPV in B decay
γ is the relative weak phase between tree and
penguin amplitudes in charmless B decays
0
+ DCPV in, eg., B → K π sensitive to γ
hadronic uncertainties ⇔ (only) model-dependent constraints
BaBar
ACP(K-π+) = (-11.5 ± 1.8)% (HFAG)
PRL 93 (2004) 131801
Belle
BELLE-CONF-0523
Tim Gershon, IoP Particle Physics 2006 CDF result not shown here – will be competitive soon
25
DCPV in 3 body B decay
Dalitz analysis → measure hadronic parameters
+
+ + Search for DCPV in B → K π π
Belle, hep-ex/0512066
mππ (GeV/c2)
Clear asymmetry in the ρ region
Dalitz analysis →
enhanced sensitivity to CPV
ACP(ρK+) = (30 ± 11 ± 2 +11-4)%
3.9σ significance
first evidence for CPV in any charged particle!
Tim Gershon, IoP Particle Physics 2006
BaBar result not shown here
26
CP violation in the B system
●
Time-dependent CP violation
–
Observed (>5σ)
●
–
Evidence (>3σ)
●
●
D*+π- [D*+D-, K+K-K0, f0KS] (BaBar,Belle combined)
Direct CP violation
–
Observed (>5σ)
●
–
K+π- (BaBar,Belle combined)
Evidence (>3σ)
●
●
J/ψ K0 (BaBar,Belle); π+π- (Belle); η'K0 (BaBar,Belle combined)
π+π- (Belle); ρ-K+ (Belle); ρ+π- (BaBar, Belle combined)
Kaon system: π+π-, π0π0, π+μ-ν, π+e-ν, π+π-e+e-, ε'/ε
Tim Gershon, IoP Particle Physics 2006
27
Clean measurement of γ
●
●
A theoretically clean measurement of γ can be
made using B → DK decays
Reconstruct neutral D mesons in states
accessible to both flavour eigenstates
B −  D0 K −  b  c u s 
–
–
–
–
B−  D0 K −  b  u c s 
relative weak phase is γ (strong phase δ)
relative magnitude is rB
various different B & D decays utilized
rom
f
ts
l
+ u
current most accurate: D→KSπ π
res
Tim Gershon, IoP Particle Physics 2006
lle
e
B
W
NE
28
B ±→
DK* ±
±
*K
D
→
B
±
±
DK
B→
±
Tim Gershon, IoP Particle Physics 2006
B ±→
DK* ±
BABA R-CONF-05/018
K±
*
D
B→
±
+15
−18
φ3 = (53
Warning: Different scale
IN P REPARATION
±
DK
B→
±
Belle
BaBar
γ = (67 ± 28 ± 13 ± 11)°
± 3 ± 9)°
Fit results:
(x±,y±) = (Re(rBei(δ±γ)),Im(rBei(δ±γ)))
29
Constraint on γ
γ = (65 ± 20)°
Tim Gershon, IoP Particle Physics 2006
30
Measurement of Ru
●
Require measurement of |Vub|
●
both experimentally and theoretically challenging
Two main approaches: inclusive & exclusive B → Xulν
Different theoretical treatment
–
Tim Gershon, IoP Particle Physics 2006
31
Alternative approach to |Vub|
●
decay constant ⇔ lattice QCD
Leptonic decays:
  B  l  l =


Signal +
background
GFmB m
8
2
l
m
2
l
2
B
2
 
1−
m
f B2∣ V ub∣2
W
NE
rom
f
s
t
l
u
s
e
r
+
lle
e
B
+
Evidence for B →τ ν
Background
B→τν Signal
Tim Gershon, IoP Particle Physics 2006
hep-ex/0604018
21.2 +6.7-5.7 signal events (4.2σ)
[cf. CLEO-c D+→μ+ν; BaBar Ds+→μ+ν]
32
Measurement of Rt
●
In principle, Δmd measures Rt
–
large theoretical uncertainty
–
can be controlled in the ratio Δmd/Δms
2
 V
m
f
B
 md
B B
B
td
=
 ms m B f 2B BB V ts
d
d
d
s
s
s
2
∣ ∣
rom
f
s
W
E
N
Tim Gershon, IoP Particle Physics 2006
D0
t
l
u
res
33
All UT Constraints
Different statistical
approaches
Tim Gershon, IoP Particle Physics 2006
34
Beyond the UT
●
Now have measurements of all three angles and two
sides of UT
–
highly constraining values of β and Ru
●
–
●
slight tension between these constraints
interpretation of this & other possible NP hints obscured
by hadronic uncertainties
Beyond overconstraining the UT, ∃ numerous additional
possible NP signatures in B physics
loop diagrams (FCNCs) probe very high mass scales
through virtual particles
Historically, extremely successful for
both NP discovery and quantification
Tim Gershon, IoP Particle Physics 2006
–
35
The FCNC Matrix
From G.Isidori, via O.Schneider
Tim Gershon, IoP Particle Physics 2006
36
The FCNC Matrix
From G.Isidori, via O.Schneider
Tim Gershon, IoP Particle Physics 2006
kaon physics
37
FCNC Matrix phenomenology
●
Generic NP can effect each loop independently
– particular models ⇔ correlations
also with other observables (eg. τ LFV, CPV, EDMs, ...)
probing for new physics in the flavour sector
↕NP discovery ↕
probing the flavour sector of the new physics
●
Flavour physics is essential to understand NP at the
TeV scale (or higher)
Tim Gershon, IoP Particle Physics 2006
38
Key measurements
●
ΔF = 2 :
Δms, ACP(Bs → J/ψ φ), εBd, εBs
●
gluon penguin
ACP(Bs → φφ), ACP(Bd → φKS), etc.
●
γ penguin
[Γ, ACP, polarisation] Bs → φγ, Bd → Xsγ, Bd → Xdγ
●
Z0 penguin
[Γ, AFB, ACP] Bs → φl+l-, Bu,d → K*ll, Bu,d → Xsl+l-, Bu,d → Xdl+l-
●
H0 penguin
Bs,d → μ+μ-, Bd → τ+τ-
Tim Gershon, IoP Particle Physics 2006
39
D0 Δms result
untagged
tagged
hep-ex/0603029
17/ps < Δms < 21/ps
assumes Gaussian errors
Bd → D-μ+X
Bs → Ds-μ+X
SIGNIFICANCE
Tim Gershon, IoP Particle Physics 2006
40
Δms World Average
Results presented as amplitude scans
~2.5σ from zero
Future updates (CDF, D0)
keenly anticipated
Tim Gershon, IoP Particle Physics 2006
(HFAG)
Δms > 16.6/ps (95% CL)
41
Measurement of εBd
●
Belle (hep-ex/0505017)
|q/p|-1 = 0.0005 ± 0.0040 ± 0.0043
●
BaBar (hep-ex/0603053)
rom
f
s
|q/p|-1 = -0.0008 ± 0.0027 ± 0.0019
●
D0 (D0note-5042-CONF)
W
E
N
lt
u
s
re
WARNING: ADMIXTURE OF Bd & Bs
“|q/p|-1” = 0.0022 ± 0.0020 ± 0.0014
ar
B
Ba
W
E
N
ts
l
u
res
m
o
r
f
D0
Challenging control of systematic errors at sub % level
Tim Gershon, IoP Particle Physics 2006
42
Measurement of ACP(Bd → φKS), etc.
W
E
N
rom
f
ts
l
u
res
ar
B
Ba
SM expectations : ~same as B0 → J/ψ KS
Tim Gershon, IoP Particle Physics 2006
~0
43
(*) + -
90% CL
allowed
rom
f
s
W
E
N
ar
B
Ba
t
l
u
res
Tim Gershon, IoP Particle Physics 2006
Belle
hep-ex/0603018
hep-ex/0604007
Studies of Bu,d → K l l
44
+ -
Measurement of Bs,d → μ μ
BR( Bs → μ+μ- ) < 1.0 x 10-7 @95% CL
BR( Bd → μ+μ- ) < 3.0 x 10-8 @95% CL
SM predictions: O(10-9) & O(10-10)
Bd → e+e- limits from BaBar
Bd → τ+τ- limits from BaBar
rom
f
s
W
NE
Tim Gershon, IoP Particle Physics 2006
t
l
u
res
F
CD
CDF Public note 8176
45
Probing the FCNC Matrix
●
●
Good constraints in some corners, but mostly still only
loose bounds on possible NP contributions
LHC will provide copious b production
– but also copious backgrounds
●
ATLAS/CMS can measure SM Bs,d → μ+μ-
●
Dedicated experiment necessary for most other modes
⇒ LHCb
–
Excellent sensitivity for (among others):
Δms, ACP(Bs → J/ψ φ), Bs → φγ, Bu,d → K*γ,
Bs → φl+l-, Bu,d → K*ll, γ(Bs → DsK), γ(Bu,d → DK), ...
Tim Gershon, IoP Particle Physics 2006
46
LHCb Detector
Tim Gershon, IoP Particle Physics 2006
47
Motivation for Super B Factory
●
How to beat theoretical (hadronic) uncertainties?
–
–
–
–
Measure ratios, asymmetries, etc.
Exploit flavour symmetries (isospin, U-spin, SU(3))
●
these approaches key to LHCb program
Avoid hadrons in the final state
●
neutrinos
← impossible in hadronic environment
●
photons
← difficult in hadronic environment
●
charged leptons
– e, μ, τ
← e difficult, τ impossible
Use inclusive final states
● X , X
← impossible in hadronic environment
s
d
Tim Gershon, IoP Particle Physics 2006
48
Pros and Cons
LHCb
Super B Factory
Huge b cross-section
Use “simple” hadronic trigger
All b hadrons produced
Only Bu & Bd at Υ(4S)
(other ECM possible)
Large boost
Reconstruct “any” decay
Measure production vtx
Coherent production at Υ(4S)
Together, provide complete coverage of B sector
Tim Gershon, IoP Particle Physics 2006
49
Super B Factory design
Requirements:
–
–
–
–
–
–
–
Extremely high luminosity
7
2
Low backgrounds
26
l
i
pr
Small beam energy spread ( < Γ(Υ(4S)))
A
y,
r
o
t
a
Boost + vertexing
r
o
b
a
L
y
Hermiticity
r
bu
s
re
Timeliness
a
D
Affordability! (construction & operation)
Possible designs:
–
–
SuperKEKB
“linear” SuperB
upgrade of conventional B factory
use ILC technology
(damping rings, compressor, final focus, SC-cavities(?))
Tim Gershon, IoP Particle Physics 2006
50
T. Browder, FNAL Seminar, 2006
“Unified and Unbiased
Attack on New Physics”
En
erg
y
tor
sec
ton
Lep
mass spectrum
interactions
fro
nti
er
LHC, ILC
New
physics
ν experiments,
gµ–2, µ →eγ, EDM, …
ν mass and mixing
CPV and LFV
Quark sector
τ LFV
τ CPV
flavour mixing
CPV phases
Super B factory, LHCb, K experiments …
Tim Gershon, IoP Particle Physics 2006
51
BACK UP MATERIAL
Tim Gershon, IoP Particle Physics 2006
52
Tim Gershon, IoP Particle Physics 2006
53
Belle DK Dalitz Result
PRD journal submission in preparation
±
*K
D
→
B
B ±→
DK* ±
±
K±
D
B→
±
81±8 events
331±17 events
B-
B+
Tim Gershon, IoP Particle Physics 2006
B-
54±8 events
B+
B-
B+
54
|Vub| from exclusive modes
Current best measurement: PRD 72, 051102 (2005)
B0 → π- l+ ν
B0 → ρ- l+ ν
Tim Gershon, IoP Particle Physics 2006
55
|Vub| from exclusive modes
Tim Gershon, IoP Particle Physics 2006
Different theoretical approaches
|Vub|
56
D0 Δms : Dilution Calibration
Tim Gershon, IoP Particle Physics 2006
Increasing dilution
Increasing dilution
Using Bd→D*±μνX
ΔmHFAG = 0.507 ± 0.004 ps-1
57
D0 Δms : Amplitude Scan for Δmd
(using Bd→D±μνX)
Tim Gershon, IoP Particle Physics 2006
58
D0 Δms : Asymmetry plot
Weighted asymmetry
Does not represent full
statistical power
Indication of oscillation clear
Tim Gershon, IoP Particle Physics 2006
59
Alternate probe of Rt
●
*
tb td
Access |V V | through b → d penguins
–
Belle
hep-ex/0506079
–
hadronization ⇔ theoretical uncertainty
cleanest measurement with exclusive modes:
B(B0→ρ0γ)/B(B0→K*0γ)
Tim Gershon, IoP Particle Physics 2006
60
KEK-B Υ(5S) Engineering Run

Bs signals are identified with Mbc and ∆E
Bs  Ds+ π-
Bs  Ds*+ π-
9 events in Bs* Bs*
4 events in Bs* Bs*
Bs  Ds(*)+ ρ-
Bs  J/ψ φ/η
BsBs , Bs*Bs , Bs*Bs*
Mbc vs ∆E
BsBs, Bs*Bs, Bs*Bs* signals can
be separated well
- 0.08<∆E<- 0.02 MeV
Bs* Bs*
7 events in Bs* Bs*
3 events in Bs* Bs*
Clear Bs signals seen in Bs*Bs* region
Tim Gershon, IoP Particle Physics 2006
61
KEK-B Υ(5S) Engineering Run

Bs → γ γ

0 candidates
Exp. BG: 0.5
B(Bsγγ )<0.56x10-4(90% CL)
PDG :<1.48x10-4
SM: 0.5-1.0x10-
Bs →K+ K-
2 candidates
Exp. BG: 0.14
B(BsK+K-)<3.4x10-4(90% CL)
PDG :<0.59x10-4
Tim Gershon, IoP Particle Physics 2006

Bs → φ γ
1 candidates
Exp. BG: 0.15
B(Bsφγ )<4.1x10-4(90% CL)
PDG :<1.2x10-4
62