L.Lista
INFN - Napoli
Luca Lista, Napoli, 25/2/05
Outline
PEP-II and BaBar experiment
CP Violation:
Direct CP violation
Measurements of sin2 ,
and
Measurements of |Vub| and |Vcb|
Searches beyond the Standard Model
Conclusions
Many results skipped due to limited time
Luca Lista, Napoli, 25/2/05
PEP-II: Luminosity and Data Sample
Total: 244 fb-1 (Jul 31st 04)
Lpeak
9.2 1033 cm 2 s
PEP-II is SLAC e e
B factory running at the
Y(4S) c.m. energy
Y(4S) resonance decays
to charged and neutral
B-anti-B pairs
Luca Lista, Napoli, 25/2/05
1
BaBar Detector
EMC
6580 CsI(Tl) crystals
e+ (3.1GeV)
1.5T solenoid
DIRC (PID)
144 quartz bars
11000 PMs
Drift Chamber
40 layers
e- (9GeV)
Silicon Vertex Tracker
5 layers, double sided strips
Instrumented Flux Return
iron / 18/19 planes of RPCs
(muon / neutral hadrons)
Luca Lista, Napoli, 25/2/05
The Unitarity triangle
CKM matrix measures Quarks mixing in weak interactions
Unitarity relations lead to unitarity triangles in the complex
d
s
b
plane
W
Vij
(b
u
qi
u , c, t
qj
d , s,b
)
A=( , )
*
ud ub
*
cd cb
VV
VV
VtdVtb*
VcdVcb*
u
Vud
Vus
Vub
c
Vcd
Vcs
Vcb
t
Vtd
Vts
Vtb
B0 B 0
mixing
V ud V ub*
B=(1,0)
C=(0,0)
1
B
and
(b cl )
Luca Lista, Napoli, 25/2/05
V cd V cb*
V td V tb*
0
CP Violation (I, II)
CP violation in mixing
q and p are the
mass eigenstates
coefficients in the
flavor eigenstate
basis; M - i½ is
the 2 2 effective
Hamiltonian
f
q/p
q/p
B 0 B0
q
p
(M
*
12
i
( M 12 i
Direct CP violation in
the decay
*
12
2
12
2
CP first observed
in kaon decays
f
B0 B 0
SM prediction for B mesons
is very small:
)
1
q
p
)
mc2
1 4
sin
2
mt
A
B
0
5 10
A
2
f
If B decay amplitude to f is different
from anti-B decay amplitude to anti-f.
Requires a relative CP violating
phase 2 and a CP conserving
phase 2
Luca Lista, Napoli, 25/2/05
B
0
4
2
f
A/ A
1
CP Violation (III)
Time dependent
CP violation
Time dependent CP Asymmetry:
A fCP t
B0
fCP
AfCP
B0
B0
b
d
t
W
W
t
0
B phys
(t )
B
0
phys
t
t
f CP
0
B phys
t
f CP
f CP
0
phys
f CP
d
0
B
b
fCP
q AfCP
p AfCP
e
C fCP
2i
fCP
C fCP
B
t
C fCP cos( mt ) S fCP sin( mt )
For a single
amplitude
fCP
0
B phys
(t )
B
0
phys
S fCP
1 |
1 |
fCP
fCP
|2
|
2 Im
1 |
fCP
2
fCP
2
|
0 implies Direct CP Violation
Luca Lista, Napoli, 25/2/05
0
Im
fCP
B decay reconstruction and tagging
B kinematics
ee
(4S)
bb
1.1nb;
bb
0.28
had
BB
Inclusive tag (lepton, K,
tag(1-2w)
mES
mES
E
*2
Ebeam
E
*
B
pB*2
E
2
30%
Exclusive tag:
0.1 0.2%
tag
*
beam
tag
Typical resolutions:
(mES)
2.5 MeV
( E)
15 - 30 MeV
e
e
CP
signal
region
E
t
sideband
s
):
z(CP) z(tag)
c
< z > 260 m
150 m
z (RMS)
mES (GeV)
Luca Lista, Napoli, 25/2/05
rec
15 40%
Direct CP Violation
B0 K
hep-ex/0408057,
submitted to PRL on
Signal: 1606 51 events (227 106 BB pairs)
BBAABBAR
AR
B flavor is tagged by the kaon charge
B0
B0
K
K
AK = -0.133 0.030 0.009
(4.2 )
Tree + Penguin contributions
First observation of
direct CP violation in B
meson decays!
B
E (GeV)
K
0
Pure Penguin
AK = 0.06 0.06 0.01
Luca Lista, Napoli, 25/2/05
CP Violation in Mixing-Decay interference
(cc) KS (CP odd) modes
S = sin2 = 0.722 0.040 0.023
C = | | = |A/A| = 0.950 0.031 0.013
Direct CP violation if
1
J/ KL (CP even) mode
7730 tagged CP events
on 227 106 BB pairs =205fb-1 on peak
Measured on a variety of cc decay modes
Luca Lista, Napoli, 25/2/05
sin2 in the Unitarity Triangle plane
cos2 > 0 at 87% C.L.
Using an s- and p-wave
interference in angular
analysis of B J/ K*0
(KS 0)
Luca Lista, Napoli, 25/2/05
sin2
channels probing new Physics
Decays dominated by loop diagrams can
exhibit contributions from new physics
B0
B0
K0S
B0 K0S 0
K0S
W
b
B0
u,c, t
s , ,( KK )
CP
s
g
d
b
B
0
Signal: 819 38 events
d
CP
C
K S0
S
0.27 0.14 0.03
0.21 0.10 0.03
K S0
3 deviation from
charmonium sin2
Luca Lista, Napoli, 25/2/05
s
d
KS0
s
s
s
d
, ,( KK )CP
K S0
Comparison of sin2 modes
2.7 from s-penguin
to sin2 (cc)
Luca Lista, Napoli, 25/2/05
2.4 from s-penguin
to sin2 (cc)
Measurement of sin2
Interference of suppressed
b u tree decay with mixing
B0 mixing
d
d
b
Vtb*Vtd VtbVtd
qA
pA
S
C
B0 decay: tree
b
q/ p
sin 2
0
Penguin diagrams
may be of the same magnitude.
A
Vub* Vud
e i2 e i2
B0 decay: penguin
A
3
ei 2
ei 2
S
C
Vtd*Vtb
1 C 2 sin 2
sin
Luca Lista, Napoli, 25/2/05
eff
3
T Pe i ei
T Pe i ei
Isospin analysis could
measure the amount of
correction to
sin2 with B
227 106 BB pairs
B0
S = -0.30
C = -0.09
0.17
0.15
0.03
0.04
C
(rad)
Particle
identification
is fundamental
p (GeV/c)
0) = (5.80
B(B
0.06 0.40) 10-6
A 0 = -0.01 0.10 0.02
B(B0 0 0) = (1.17 0.32 0.10) 10-6
C 0 0 = -0.12 0.56 0.06
Belle observes C
0 0
= -0.58
0.15
0.07
Luca Lista, Napoli, 25/2/05
| -
eff|
< 35°
90% C.L.
(Gronau, London)
sin2 with B
122 106 BB pairs
Similar to , but smaller penguin pollution
Not a CP eigenstate in principle, but observed
to be almost pure CP = +1
Signal: 314 34 events
flong 1.00 0.02
B0
Slong = -0.19
Clong = -0.23
B(B
B(B0
0.33
0.24
0.11
0.14
89 106 BB
= (22.5 +5.7-5.4 5.8) 10-6
0) < 1.1 10-6 (90% C.L.)
0)
0
277 106 BB
A
2
2
A0
= ( 96
A
peng
A0
A00
2
A00
10(stat) 4(sys) 11(peng) )°
2
sin
(Grossman, Quinn)
Luca Lista, Napoli, 25/2/05
peng
f L00 BF ( B 0
f L 0 BF ( B
0
0
)
0
)
Combined B
,
,
(Dalitz)
mirror solutions become
disfavored
From CKM
matrix fit (with
no meas.):
=( 98
Fit +
16 )°
,
,
:
=( 103 +10-11 )°
Luca Lista, Napoli, 25/2/05
Belle .
Belle 275M
~2.3 difference between
Belle and BABAR
BABAR 227M
Luca Lista, Napoli, 25/2/05
Belle: evidence of CP violation
Large CP Violation,
(A,S)=(0,0)
1-C.L.=5.62x10-8, 5.4
(A,S)=(0, 0.62)
1-C.L.=5.13x10-5, 4.0
Large Direct CP
violation, confirmation
of the previous Belle
results
S
Luca Lista, Napoli, 25/2/05
C.L. = Confidence Level
Belle:
0
0
Belle measurement with 275M BB pairs
0
Br (
0
0
ACP (
) (2.3
0
)
0. 4 0. 2
0.5 0.3
0.44
) 10
0.53
0.52
6
0.17
hep-ex/0408101
submitted to PRL
BABAR measurement with 227M BB pairs
Br (
0
ACP (
0
) (1.17 0.32 0.10) 10
0
0
)
0.12 0.56 0.06
Luca Lista, Napoli, 25/2/05
6
hep-ex/0412037
submitted to PRL
Belle: constraints on
2
( )
(degrees)
95.4% confidence interval
19 and 71
2
2
2
0
Luca Lista, Napoli, 25/2/05
180
Different methods to measure
GLW
The phase between b c and b u transitions is
Vus*
Vub
Size of CP asymmetry depends on:
Vcb
*
cs
(*)
B
V
r
Color
suppressed
A
VcbVus*
3
A VubVcs*
Gronau, London, Wyler, 1991:
Atwood, Dunietz, Soni, 2001:
3
2
2
(*) 0
A( B
D
K )
A( B
D (*)0 K )
0.1 0.3
ei
use B- D0CP (small D0 B.r., 8-fold ambiguity)
interference in D and anti-D dec. to same final state
input:
B
D
Giri, Grossman, Soffer, Zupan, 2003: B
rD
| A( D 0
| A( D 0
D(*)0K , D0
Luca Lista, Napoli, 25/2/05
KS
K
K
)|
)|
0.060 0.003
BABAR measurement,
Phys.Rev.Lett.91:171801,2003
Dalitz analysis
B
D(*)0K , D0 K
RADS
rD2
Br ([ K
Br ([ K
rB2
]K ) Br ([ K
]K ) Br ([ K
2rB rD cos(
D
B
ADS method
]K )
]K )
Br ([ K
Br ([ K
2rB rD sin( D
) cos
RADS
No signal observed in 227 106 BB pairs
From limit on
D0 K
K
]K ) Br ([ K
]K ) Br ([ K
B ) sin / R ADS
AADS
]K )
]K )
AADS not measured, limits on RADS
Any D,
1 on rD,
48°< <73°
From limit on
D *0 K
K
Any
D* D0 0, D0
68% C.L.
area
rB
0.23 (90% CL )
90% C.L.
Upper limit
rB
68% C.L.
area
rB*
0.21 (90% CL ) rB*
Small rB values make measuring hard
Luca Lista, Napoli, 25/2/05
B
D(*)0K , D0
KS
68% 90%
Dalitz analysis
A posteriori rB(rB*) with uniform a priori
D0 K
D*0 K
D0 K
rB
rB
rB 0.18 (90% CL)
B
*
B
D*0 K
rB*
rB*
0.24 (90% CL)
(130 45 8 10( model ) ) o
(311 52 23 10( model ) ) o
(88 41 19 10( model ) ) o
Dalitz model syst.
D* D0 0, D0
rB*
Sensitivity depends on rB(*)
Luca Lista, Napoli, 25/2/05
Belle:
Updated with 275M BB events:
Luca Lista, Napoli, 25/2/05
sin(2 + ) using B0
D(*)- +/
+
Time-dependent CP violation in the mixing/decay interference
Vud
B
0 b
d
Vcb*
u
d
c
d
favored b c amplitude
Vcd*
D
*
B
~
| A2 || VubVcd* | ei e
B0
2
)cos
)sin
Exclusive reconstruction of D- +, D*- +,DB0
D*
0
Partial reconstruction of D*- +
D
D*
suppressed b u amplitude
Time-dependent asymmetry can be expressed in term
a = 2rsin(2
c = 2rcos(2
Vub
0 b
d
| A1 || Vcb* Vud |
of the parameters:
d
c
u
d
+
soft
X
Luca Lista, Napoli, 25/2/05
i
D (*)
B
0
No CP asymmetry
observed yet
~
Vcb inclusive measurement
Inclusive B
Xc l decays: measure
hadron mass moments and
lepton energy moments
(b
c
)
b
2
Vcb
Vcb mb2 (mb mc )3
Lepton energy momenta
Partial B.F.
HQE predicts the moments up to 8 parameters
to be fitted (including |Vcb|, mb and mc)
B (b
cl )=(10.61 ± 0.16exp ± 0.06th,HQE,)%
| Vcb | (41.4 0.4ex 0.4 HQE
0.6th ) 10
3
Luca Lista, Napoli, 25/2/05
c
Vcb: HQE Fits to MX / El moments
BABAR
M1x
MX moments
M2x
M0l
2/ndf
= 20/15
= used, = unused
in the nominal fit
M1l
M3x
M4x
M2l
M3l
E moments
Luca Lista, Napoli, 25/2/05
Red line:
line HQE fit
Yellow band:
band theory errors
Vcb exclusive measurements
Exclusive B
D*+ l
Decays
w = prod. B, D* 4-velocities
B (B0
D*- l+ )=(4.90 ± 0.07stat ± 0.36syst)%
| Vcb | (38.7 0.3stat 1.7 syst
1.5
1.3 th ,lattice
) 10
3
Luca Lista, Napoli, 25/2/05
Vub measurements
Inclusive: measure total
Br(b ul )
Exclusive: measure selected decays (B
l , l , )
Innovative technique: fully reconstruct one of the B
0
B
l
B(B0
-l+
)=(1.08 0.28 0.16) 10-4
B(B+
0l+
)=(0.91 0.28 0.14) 10-4
B(B0
-l+
)=(2.57 0.52 0.59) 10-4
B0
l
Electron endpoint spectrum extrapolation
using b s photon spectrum (CLEO) using HQET
B(B Xue )=(1.73 0.22exp 0.33extr.syst) 10-3
p (GeV/c)
|Vub| = (3.94 0.25exp 0.37extr.syst 0.19th) 10-3
Luca Lista, Napoli, 25/2/05
Inclusive
studies
LEP
Exclusive
modes
Vcb and Vub averages
|Vub|avg. = (4.70 0.44stat+sys) 10-3
|Vcb|avg. = (41.4 0.4 0.4 0.6th) 10-3
Luca Lista, Napoli, 25/2/05
Radiative penguin decays
Radiative penguin decays: b
s and b
d are FCNC transitions
b
W could be
replaced in the loop
by new particles
BF(b
BF(b
s rate agrees with SM prediction:
s )TH = 3.57 ± 0.30 x 10-4 (SM NLO)
s )EXP = 3.54 ± 0.30 x 10-4 (HFAG average)
b d at discovery limits:
BF(B
) < 1.2 10-6
|Vtd/Vts| < 0.19 (90% CL)
Sum of 12 exclusive,
self-tagging
B Xs final states
b s
b s
No evidence of direct CP violation:
ACP, b
ACP, B
s
K*
= 0.025 ± 0.050 ± 0.015
= -0.013 ± 0.036 ± 0.010 (prelim.)
Luca Lista, Napoli, 25/2/05
Xs = K/Ks + 1-3 pions
E > 2.14 GeV
Studies of DsJ properties
*(2317)+
(2460)+
DsJ
and DsJ
discovered in 2003
Detailed studies properties and mass meas.
DsJ(2460)+ Ds+ elicity
J=2
J=1
B DsJ(*)+D(*) angular analysis
spin
Branching fraction measurements
Ds1(2536)+
DsJ(2460)+
DsJ*(2317)+
m(Ds+
+
-),
GeV/c²
m(DsJ*(2317)+ Ds+ 0) =
2318.9 0.3 0.9 MeV/c²
m(DsJ(2460)+ Ds+ , Ds+ 0 , Ds+ + -) =
2459.4 0.3 1.0 MeV/c²
m(Ds1(2536)+
D s+ + - ) =
2534.3 0.4 1.2 MeV/c²
Luca Lista, Napoli, 25/2/05
Pentaquark searches
5
--(1862)
123fb-1
c
No signal for
5
+(2285)
-5
0(1862)
5
No signal for
0
5
+(1540)
nK+
No signal for
+
5
m(pKS) (GeV/c2)
No evidence of pentaquarks in high
statistics samples
Cross section limits well below expectations
Luca Lista, Napoli, 25/2/05
pKS
Conclusions
BaBar is exploring different aspects of CP
violation in B meson
Recent first evidence of direct CP violation
sin2 is becoming a precision measurement
First quantitative estimates of
Technology for extracting is being established
Some channels may probe new physics
b sss penguins?
The increase of statistics in the following years
will improve the experimental precision and will
make more rare channels accessible
Luca Lista, Napoli, 25/2/05
Backup
Luca Lista, Napoli, 25/2/05
Selex DsJ(2632)+ state
SELEX claims evidence of a state DsJ(2632)+
decaying to Ds+ and D0K+(hep-ex/0406045)
BaBar doesn t observe such signal
DsJ(2573)+
Events/ 5 MeV/ c2
Events/ 5 MeV/ c2
DsJ(2632)+
M(D0K+ ) GeV/c2
SELEX
m = M(K- K+ )
p* > 4.0 GeV/c
Luca Lista, Napoli, 25/2/05
M(K-
+)
MeV/c2
Selex DsJ(2632)+ state ( Ds+ )
No evidence of DsJ(2632)+ in Ds+ ,
D0K+, D*+KS in125 fb-1
Luca Lista, Napoli, 25/2/05
2
(2S)= 556± 30
mX(3782)=3873.4±1.4 MeV/c2
No evidence of hc found
Set an upper limit
(B- hcK-)
hc
(2S)
(B- X(3872)K-)
X(3782)
(X(3872) J/
(hc J/
<3.4 10-6 (90% C.L.)
+ -)=(1.28± 0.41) 10-5
Luca Lista, Napoli, 25/2/05
+
)
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