Risultati recenti di BaBar
[Una selezione dalle conferenze estive]
*
ud ub
V V
CSN1 Napoli 19/09/2005
Giuseppe Finocchiaro
Laboratori Nazionali di Frascati
a
g
VtdVtb*
b
VcdVcb*
The gold rush



(Where `gold’ is no
longer J/yKs)
Most analyses in
this talk used the
Run1-4 dataset
(~240fb-1)
KEKB delivered
~470fb-1 so far
19/09/2005
Run5
Run4
Run2
Run1
G. Finocchiaro @ CSN1 Napoli 2005
Run3
2
(The usual) disclaimer

Hard selection required in this talk
(75 BABAR abstracts @LP05, 57 @EPS05)
 In spite of ‘sub-optimal’ PEP-II
performance this year so far, still
competitive wrt Belle
 “Di necessità virtù”: BABAR‘s analysis
power generally (still) compensates for
smaller integrated statistics



19/09/2005
More physics channels
Better detector (PID, vtx)
More efficient analyses
G. Finocchiaro @ CSN1 Napoli 2005
3
Indice






Angoli (I): g, a
Lati (I): |Vub| da b→u ℓ n
sin2b: (persistenti) indizi di NP
Lati (II): |Vtd/Vts| da b→d/s g
Ancora nuovi stati: la Y(4260)
Non parlerò di:

6.8
95 ( 2005) 041802)
 e  [ 11
 108 @ 90%CL (PRL
]
( hepex / 0508012)
(SM:10-40)

B→tn
[<2.610-4@90%CL]
(SM:8.1±2.510-5)

B→Ksp0g
[hep-ex/0507038]
sin2b~0.04)
19/09/2005

G. Finocchiaro @ CSN1 Napoli 2005
Conclusioni, prospettive
(SM: L.H. g
4
UT angles: g


Vcd Vcb*
From direct CPV in the decay of charged B’s

Interfering tree amplitudes w/ CP-violating relative weak
phase g and CP-conserving relative strong phase d
b→cus

Vud Vub*
b→ucs
Interference if D0/D0 decay into identical final state



CP-eigenstate decay: Gronau-London-Wyler (GLW)
Doubly-Cabibbo-suppressed (DCS) decay: Atwood-DunietzSoni (ADS)
~
Dalitz plot analysis of 3-body decay, e.g., D 0  K S0   :
Giri-Grossman-Soffer-Zupan (GGSZ)
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
5
It all depends on rB…

A(b  u )
Sizable interference only if
rB 
~ 0.1  0.2
A(b  c )
large enough amplitude ratio
From CKM factors & color suppression


Unfortunately, BABAR finds small rB
Error on g vs. rB
 rB0.12  30o error on g
w/ current BABAR data
 need to add more
channels/data
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
6
New GLW
and ADS signals in
~

0 *
0 
B  D K [ K S  ]
CP-eigenstate decay
hep-ex/0507002,
submitted to PRL
DCS decay
Right Sign
D0→flavour non-CP
~90 events
hep-ex/0508001
Wrong Sign
~4 events
BB++
D0 CP+→K+K-,
p +p -
BB-
D0 CP-→KSp0, KSw, KSf
BB+
+
WS B+
WS B-
B-
B
NCP+=37.6±7.4
19/09/2005
mES (GeV/c²)
NCP-=14.8±5.9
G. Finocchiaro @ CSN1 Napoli 2005
7
GGSZ~DP analysis of
B   D (*)0 [ K S0   ]D~ K (*) ( K S0  ) K
D0
A(B-)=|A(B→D0K-)|×
D0
+rBei(-g+dB)
m2  m2 ( K S0  )

m2-
The idea in pictures:
m2+

*
m2-
m2+
CP-conjugate B- and B+ decay amplitudes

)  |A | A

(m , m )
A( B  )  |AB|  AD (m2 , m2 )  rB ei ei B AD (m2 , m2 )
A( B 
B

2
2
 i i B
(
m
,
m
)

r
e
e AD
D


B
 2
D

2

Assume D decays
conserve CP…
2

*
D
i
i B(*)

| A( B ) | | A | r | A | 2r  A A  e e
 g is the same, r(*) and d(*) depend on the mode
2
19/09/2005
 2
D
(*)2
B
(*)
B

D
G. Finocchiaro @ CSN1 Napoli 2005
8
DP analysis of D0/D0 decays
hep-ex/0507101

Extract D0(bar) decay amplitudes from DP analysis
of independent cc sample with flavor-tagged
91fb 82k D s
D0  K S0   decays from D*   s D 0
New K-matrix model:
9 BW resonances +
K-matrix formalism
for  s-wave
-1


0
Deals with broad,
overlapping,
multi-channel
scalar resonances
m2  m2 ( K S0  )
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
9
~ (*)0 (*)
Signals in all B  D K modes

227×106 BB
~
D0K-
Signal
events
Mode
~
B-D0K−
~
~
D*0[D00]K-
~
~
D*0[D0]K-
282 ± 20
~ ~
B-D*0[D00] K−
90 ± 11
B-D*0[D0]K−
44 ± 8
B-D K* [K0Sp-]
42 ± 8
~ ~
~0 −
~
NEW B-D0K*−[KSp]
19/09/2005
hep-ex/0507101
G. Finocchiaro @ CSN1 Napoli 2005
10
(mES>5.27 GeV/c²)
g (deg)
GGSZ DP results: g vs. r(*)B
~0
~
D K-
~0
D*0K-
D K*-
hep-ex/0507101
2s CL
1s CL
(stat.+syst.
uncertainties)
2 fold (p)
ambiguities for
both g and dB
rB
r*B
.rs (<0.75@2s CL)
Mode
rB/r*B /rs
DK
all D()K() modes combined:
0.12±0.0
8±0.03±0.
04
g=(67±28stat±13syst±
D*K
0.17±0.
10±0.03±0
19/09/2005
.03
G. Finocchiaro @ CSN1 Napoli 2005
11
Putting it all together…


… we can measure g!!!!
3 theoretically clean (= w/o
penguins) methods to measure g




 CKM  (57 -137 )  W A  (63-1215 )
did not mention TD D(*)rp… (no
new measurement)
Small r()B  very hard
measurement, but no longer
“mission impossible”
No single channel dominates
To improve precision, need more
data/channels
23 
BABAR only::

  5118
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
12
UT angles from TD asymmetries
Preamble: CPV from interference of decay and mixing
B0B0 mixing
b
B
b
0
d
Vtb*
Tree decay
Vtd*
t
t

d
B
b
Vtb
Vtd
q / p  Vtb*Vtd / VtbVtd*
0
B
0
b
d
Penguin decay
Vud*
Vub
d


/

u
u


/

d

B
b
0 u,c,t
g
d
d
u
u
d
 / 
 / 
A  Vtd*Vtb
A  Vud* Vub
C 
1  |  |2
1  |  |2
S 
 2 Im 
1  |  |2
 Specific example is for b→uud , but valid in general
 Single CKM phase in decay ↔ Cf=0 (no direct CPV)
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
13
a and the penguins: more
triangles are needed
 i
 
a=p(b+g)

1 P e
q A
2 i eff
2 i
T

 e

|

|
e
pA
1  P ei
T
Difficult to reliably estimate how much penguins
contribute
 B(B0K+p-) (~ pure penguin) indicates they cannot be
neglected

Gronau/London analysis

Assuming isospin symmetry, these triangular
relations between the Bhh amplitudes hold:
κpp
B decays  A   2 A 0  2 A00
B decays  A   2 A  0  2 A00




The B and B triangles do not match, and 2aeff =
2a+κpp
Need to measure 5 BFs, including B(B0p0p0) from 0 0
BF(B    )
tagged samples
2
sin (eff  ) 
still a 8-fold ambiguity
Grossman/Quinn bound:
BF(B     0 )
14


Measuring a in B→rr
decays
0 +
0 -
Tough analysis [VV state, (p p )(p p ), r’s are
wide]
However:
B( B 0      )  (30  4  5) 106
232M BB

B(~6
( B 0 times
  0 x 0B→pp)
)  1.1106 @ 90% CL

(isospin triangle collapses to a line)
 Small penguin contribution:
0.021
|a-aeff|<11o
@
f L  0.978  0.0140.029
68%CL

(almost pure CP-even state)
PRL 95 041805 (2005)
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
15
 from
B→pp/rr/rp
decays

All three modes give consistent
and complementary
measurements of 

 constraint rather weak due to

rr yields single most precise

large penguin contamination
constraint
TD analysis of 3 Dalitz plot in
rp. Weak constraint at
90% CL, but disfavors rr
mirror solution near 170o
19/09/2005
CKM  (95-1310 )
 [hh]  (99-912 )
G. Finocchiaro @ CSN1 Napoli 2005
16
UT sides: |Vub|
Tree-level process (charmless semileptonic)


VudVub* α
γ
VtdVtb*
β
VcdVcb*
NP free
‘complementary’ (opposite in the UT) to sin2b
BF(b→u l n) measured from inclusive and exclusive s.l. branching fractions

From inclusive (partial) s.l. BFs using O.P.E.




reliable prediction of total B→Xuℓn decay rate
experiment measures partial BFs (hard cuts against B→Xcℓn)
biggest uncertainty in extrapolation of BF(b→u l n) to full phase space from
motion of b quark in B meson
Parameters measured e.g. from E*g in b→sg
19/09/2005
PRD72 052004 (2005)
G. Finocchiaro @ CSN1 Napoli 2005
17
Inclusive |Vub| measurements

Electron endpoint spectrum
| Vub | (4.44  0.25 exp
0.42
0.38 SF
88M BB
 0.22 th )  103
hep-ex/0408075, being submitted to PRD

Electron and n momentum
| Vub | (3.95  0.26 exp
0.58
0.42 HQ
hep-ex/0506036 submitted to PRL

89M BB
 0.25 th )  103
q  El
2
signal
region
sideband
region
Lepton and hadronic system recoiling against
fully-reconstructed B mesons
232M BB
| Vub | (4.65  0.34 exp
hep-ex/0507017
19/09/2005
0.46
0.38 SF
 0.23 th )  103
q2  mX
G. Finocchiaro @ CSN1 Napoli 2005
signal
18
|Vub| from exclusive measurements:
untagged Bpℓn 83M BB, hep-ex/0507003, subm. to PRD
Exclusive s.l. BFs  |Vub| using form factors (FFs)
in bins of q2


several approaches LCSRs, LQCD, quark models …
FF uncertainties affect measurement twice
FF shape  acceptance  try and measure on data
2. FF normalisation in extraction of |Vub| from pBF (~10-15%)
1.
| Vub | B /( B0  )
LCSR
LQCD
for -0.15<DE<0.25 GeV
-3
|Vub|=(3.82±0.14stat±0.22syst±0.11FF–+0.88
0.52FFnorm)x10
19
Incl. vs. Excl. : which wins?
Inclusive


Improved expt. error: 4%
Very much improved theory
error ( OPE parameters): 6%
Indirect |Vub| determination
3
VubCKM  (3.5600..25
)

10
22
| Vub | (4.38  0.19 exp  0.27 mb ,th )  103 [ HFAG ]

Exclusive


Improved expt. error: 4%
Theory error still dominant: ≥15%

Experimental input, i.e., FF shape,
will reduce theory error in the future
| Vub | (3.76  0.16 exp

0.87
0.51 LQCD
)  103 [ HFAG ]
Measurements now compatible
within errors
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
20
Why this is relevant
UTfit JHEP 0507:028,2005
• constraints from TREE
process only
• Gauge the UT in any
extension of the SM
• Firm starting point for
NP searches
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
21
sin2b from charmonium
[to find NP, must know OP]

Reference point for NP




C=0 (only 1 phase)
S=-hfsin2b
Precise! sin 2b EPS'05  0.687  0.032
Validation of SM predictions


19/09/2005
J/y
BO
KS
New Belle meas. (357M BB):
sin2b=0.652±0.044
sin2b[UTFit]=0.793±0.033 (sides) [0.734±0.024 (all)]
In fact, a big success…
G. Finocchiaro @ CSN1 Napoli 2005
22
Why b→s penguins are
good for NP




Small effects (e.g. from
propagators of heavy particles
circulating in the loop) more
easily detectable since Tree is
missing
CKM factors same as J/yKs
If single phase, SM predicts:
Speng=Scharmonium=sin2b
Cpeng=Ccharmonium=0
Naïve [HFAG] average of
penguin modes 2.7s below
charmonium
19/09/2005
note: BABAR and Belle
have ~same precision
G. Finocchiaro @ CSN1 Napoli 2005
23
To find NP, must know OP (II)
In fact, we know that > 1
amplitude/phase is (usually) involved

e.g., b→uus CS tree (g) in channels

involving non-strange neutral mesons
Even J/yKs could have penguins

[hep-
Is there a dominant one? Intense
theoretical work lately





DS=0.000±0.017
ph/0507290]
Dsin2b always >0 (contrary to
experiment)
some predictions quite precise
theory parameters constrained to
measured BF (will further improve)
QCD factorization:
[Cheng,Chua,Soni, hep-ph/0506268]
[Beneke, hep-ph/0505075]

Averaging still not meaningful
Dsin2b
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
24
hK0 and K+K-K0 have largest BF
among b→s modes



hep-ex/0507087
New signals (~230M BB) in
[h,K+K-]KL0
hKS0 has smallest stat. error on sin 2b
hKL0 adds 50% more events
(1245±67 total)
ShK0 =0.36±0.13±0.04, ChK0
=-0.16±0.09±0.03


SK+K-K0L =0.07±0.28±0.12, CK+K-K
Using fCP-even =0.89±0.08±0.06
sin2bK+K-K0 =0.41±0.18±0.
hep-ex/0507016
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
25
CPV in b→s penguins

Intriguing difference from b→c remains
2.7s?
This could be one of the greatest discoveries of the century,
depending, of course, on how far down it goes…
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
26
b→d



Large background
Only accessible through exclusive modes B, w
Simultaneous fit to B+→r+g, B0→r0g, B+→wg assuming
Belle claim observation
Channel
BF(10 -6 )
 
 0
w
 / w
 1.8

 0.4
211 M B B
hep-ex/0408034
 1.0
 1.2
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
27
UT sides: |Vtd/Vts|

Constraint used to come entirely from Dmd/Dms


VudVub* α
γ
(smaller theoretical uncertainty on
VtdVtb*
β
VcdVcb*
f d2 Bd / f s2 Bs )
Now radiative penguins sufficiently precise to start providing
meaningful UT constraints, using:
FF ratio z2=0.85±0.1
Ali et al.,
Eur.Phys.J.C23:89-112,2002

difference in
dynamics DR 
0.10.1
Low B→r/w g BF favors small |Vtd|
md and
md
ms
B( B   )
B( B  K * )
DR=0 in this plot
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
28
New States:
X(3872)→J/yp+p-


Discovered by Belle in 2003 in
B   X (3872) K  , X (3872)  J    

3872 is just above open-charm threshold

Confirmed by D0, CDF, BABAR
isovector  charged partner(s) must exist


6.1σ
ruled out @10-4CL by BABAR in B0(+)→X+K-(0)
searched in B0(+)→X0(J/yp+p-)K0(+) decays
2.5 σ
R=BF(B0→XKS)/BF(B±→XK±)=0.50.
30.05

Dm=2.71.30.2
MeV/c2 among different models
Need
more data to discriminate




Does not fit in standard charmonium spectroscopy

why does not decay onto DD?

J/yr isospin violating (but is a r?)
[qq][qq] [Maiani et al. PRD71, 014028 (2005)]: R=1, Dm=7±2MeV/c2
D*0D0 molecule [PRD71, 074005 (2005)]: R<0.1
Search in ISR events
19/09/2005
JPC= 1
G. Finocchiaro @ CSN1 Napoli 2005
y(2S),
:
y(3770), …29
...no sign of X(3872) in ISR, but...

Discover Y(4260)→J/yp+p-!!
hep-ex/0506081
232fb-1
y(
2S)
Peak cross section ~50pb


Just above DSDS threshold
Could be two states
Very robust signal. Among other tests:
 Use y(2S) for optimisation/validation
 fit for null signal with
 different bkgd shapes
 bin sizes
 check for reflections





Split by run, J/y decay mode
search in J/y sidebands
require gISR (25% of events)
change/reverse selection
feed-down e.g. from undetected p0
Where else?
Y(4260)
No trace in R-scan



shad=(14.2±0.6)
nb
sY~50pb
accuracy of R~4%

no surprise it‘s not
seen in R
But why a dip?
• And why does not
decay to DD?
•
√s (GeV)
Feeble signal (so far) in
B-→J/yp+p-K• 3.1s, assuming mISR, wISR
• need more data
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
31
Summary & outlook



CPV in mixing↔decay (and decay) well established
Precision in measurements of CKM parameters steadily improving
The Standard Model resists (surprisingly well…)
2008 (?)
2005

New states keep popping up in unexpected places


Finding NP is the name of the game now



renewed interest in spectroscopy, new models proposed and being scrutinized
Deviations from sin2b in b→s penguin getting smaller (~1s for most modes)
In general, processes with clear SM predictions are good candidates
B→tn
around the corner?
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
32
The next few years



Statistical uncertainties have scaled so far faster than 1 / L
(adding new channels)
Even for J/yKs systematics not an issue, for several ab-1 yet
Theory often feeded by exptl. measurements
 also improves with more data

Expected precision on UT angles vs. time:
sin2b in
penguins
g from B→DK
a from
rr
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
33
Our analysis commitments
BaBar in Italia
Milano: analisi dipendenti dal tempo in decadimenti
senza charm e misure di BF (h()K/p,
h()KS/L, h()w, h()f, hh,
hh,a1p, h()K/Ksg)
Torino: decadimenti senza
charm a due corpi (pp, Kp,
KK), Vub (recoil)
°
Genova: charmonio
°
(B cc  adroni,
o
B cc[hCg]K), t  mg
Pisa: sin2b/CP/CPT, vita media del t,
°
°
°
°
Trieste: B→D*D*, Vcb (B→D*l n),
BD(*)DsJ
Padova: Vcb (B→D*l n), Vub, vita
media e mixing del B, t→mg, CPV nel mixing
°
t→Ks
DK Dalitz per l'estrazione di g,
°°
b→sg inclusivo, B→D*l n, B→D0CPK(p0),
B→D*tn
°
Roma I: sin(2b+g), BDSp/K, DKS, b→sg sul
rinculo, mixing del B, X(3872), Vub, DK Dalitz per
l'estrazione di g, decadimenti senza charm e analisi
dipendenti dal tempo per l'estrazione di a (pp, Kp,
KK), t→mg, sin2b dai pinguini (fKS, fKL, KSKSKS
,K+K-KL,KSp0, K*g), B→fK+
pp0n,
19/09/2005
Ferrara: Vub, Vcb e
charmonio sul rinculo
Perugia: BD*DS*,
DSfp,
° tmg,
CPV dal lato di
tag,
LN nel
Frascati:
BD*D*,
CPV
mixing
*
*
BD DS , DSfp,
gISRK*+K-,
gISRfh/p0, CPV nel
Napoli:
Vcb (B→D*l n),
mixing
B→J/yK/p, B→tn,
decadimenti semileptonici
Bari: decadimenti a 3 corpi della D,
DsJ*(2317)+, DsJ*(2460)+ (analisi di Dalitz)
G. Finocchiaro @ CSN1 Napoli 2005
34
Backup slides
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
35
L-scaling of channels for angles
measurements
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
36
How NP would be constrained

NP (assuming only in
loops) parameterised
as SM  NP  Cd dei
d
SM
From tree
measurements
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
37
(*)  
BK l l
• sensitive to relative contribution of
-, Z-penguin and box diagram
• new physics can show up in any of
these
Event yields in 229M BBbar
B  Kl  l 
B  K *l  l 
RK = 1.06  0.48  0.05 [SM:~1]
RK*= 0.93  0.46  0.12 [SM:~0.75]
N=45±10
N=57±14
hep-ex/0507005,
preliminary
19/09/2005
smallest BF from
B’s measured to date!
ACP(K) =-0.08 0.22
0.11 [SM:~0]
ACP(K*) =+0.03 0.23
soon
to come: forward-backward asymmetry
0.12
[SM:~0]
G. Finocchiaro @ CSN1 Napoli 2005
38
B→Ksp0g


hep-ex/0507038,
submitted to PRL
232M BB
Phase in B→K*0 g between mixed and
unmixed decay is 2b
W couples only to left-handed quark: b→sL
interference suppressed in SM:
Smix  -2ms/mb sin2b -0.04 sin2b

possibly large enhancement from NP
can use Ks0 even if not from resonance
(Atwood et al (2004))


K*(890) 
S ( K *0 )  0.21  0.40  0.05
S ( K S0 0 )  0.9  1.0  0.2
non-K* 
Compatible w/ SM
Errors still large
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
39
B→tn

CKM fit predicts



o
Β( B  n )  (8.1  2.5)  105
Direct measurement of fB (currently only from
LQCD)
B→tn /Dmd constraints |Vub/Vtd|
> 2 n in the event. Analysis:
o Use hadronic or semileptonic tag
o 1 or 3 prong topology
Can constrain SUSY parameters
232 M B B
We’re almost there!
Β( B  n )  2.6 104 @ 90%C.L.
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
40
(NP in) b→d/s
g
• FCNC
• sensitive to NP @ EW scale
• solid SM predictions:
• BF(B→Xs
g)=(3.6±0.30)10-4
• ACP~0
• Huge backgrounds
• cuts on g or Xs spectra ↔ model
dependence
• Fully inclusive (no requirement on Xs/d)
• lepton tag [/1200 on Bkg (/20 on Sig)]
• topology cuts, p0 h vetoes
N sig  1504  85
19/09/2005
• Exclusive (semi-inclusive) b→sg
• reconstruct Xs→K+np+mp0 (n,m<5)
• 38 states,55% of all possible
G. Finocchiaro @ CSN1 Napoli 2005
41
b→d/s g spectra, BF, ACP
Inclusive
Semi-inclusive
Partial Branching Fractions
(PBF)
(4s) frame
B rest frame
Method, cut
ACP(b s   b d ) =
(  0.010  0.115  0.017 )
19/09/2005
88 M B B
BF(10-4)
Inclusive, 1.9 GeV
3.67  0.29  0.34  0.29
hep-ex/0506043
Exclusive, 1.6 GeV
 0.07
3.38  0.19 00..64
41 0.08
LP Paper-100
Inclusive, 1.8 GeV 3.55  0.32 0.30 0.11
153
MBB
 0.31 0.07
G. Finocchiaro
@ CSN1 Napoli 2005
hep-ex/0403004
42
g from B-[K+p-]K-: ADS
method

Equalize the interfering amplitudes (PRL 78, 3257)
favored
suppressed
B  D0K , D0  K  
suppressed
favored
B  D 0K , D 0  K  

B [K  ]D K 
Extract g from decay rates measurements
rD=0.060±0.003, from
D*+[K± p] p+
(B  [K  ]K )  (B [K  ]K ) Nsuppressed fav. 2 2
RK 

 rD  rB  2rDrB cos cos

 


 

(B  [K  ]K )  (B [K  ]K ) Nfavoured sup.
0.93±0.04
19/09/2005
G. Finocchiaro @ CSN1 Napoli 2005
rB~0.1÷0.3
43