Transcript BABAR Status and Outlook Marcello A. Giorgi on behalf of BaBar Collaboration EPAC meeting - SLAC SLAC 06/12/03 EPAC meeting Marcello A.

BABAR Status
and Outlook
Marcello A. Giorgi
on behalf of BaBar Collaboration
EPAC meeting - SLAC
SLAC 06/12/03
EPAC meeting
Marcello A. Giorgi
1
Canada
[4/18]
China
[1/5]
France
[5/55]
Germany
[3/30]
Italy
[11/101]
The Netherlands Norway
[1/2]
[1/3]
IFR
USA
[38/290]
United Kingdom
[10/66]
The BABAR
Collaboration
DIRC
10 Countries
75 Institutions
579 Physicists
DCH
EMC
SVT
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EPAC meeting
Russia
[1/9]
BABAR
COIL
Marcello A. Giorgi
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BaBar Physics GOALS
New environment: high luminosity asymmetric
collider
1)Search for CP violation in B meson decays largely predicted by
the Standard Model
2)Test extensively at this low energy scale the Standard Model
by measuring precisely enough quantities to impose constraints
on the Standard Model parameters
CP in b sector has been established by BaBar and
Belle
TRY to open windows on new Physics beyond Standard Model
More precise CKM measurements, Rare B decays, Charm study,
Tau rare decays .
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CP in Standard Model
Vud
V   Vcd
V
 td
Vus
Vcs
Vts
1 2

1




2
Vub  
1
Vcb   

1  2

2
Vtb   3
2
 A (1    i )  A

CKM quark
mixing matrix
bul
B() l
CP

A 3 (   i ) 

  O ( 4 )
A 2


1


Violating phase
Unitarity
B0 Mixing
B() 
bcl
BD(*)l
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Experimental ingredients: BaBar optimized
for time dependent CP asymmetries

z
b(4S) = 0.55
  4s 
e-
Flavor
Tagging
m

Btag
K
Tag vertex
reconstruction
e+

B0
m
Brec
B0
K
Coherent BB pair
Dz 1
Dt 
b c
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J/Y

m
0
s

Dz
Start the Clock
Marcello A. Giorgi

Exclusive B Meson and Vertex
Reconstruction
5
Time dependent rate,flavor mixing and CP,T,CPT
CPV in Mixing -Decay
CPV direct
Time dependent rate:
dN exp(–|Dt|/tB) ( 1 ± D (S sin(DmDt) - Ccos(DmDt)) )  R
D is the mis-tag dilution
R is the time resolution
___
S
q A cp
  cp
p Acp
q
1
p
1 
Dm  i 2D
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SM
2
1 
2
B0
mixing
M  i 2
C
2
CP and T Violation in mixing
mc2
q
 1  4 2 sin b  5 104
p
mt
z2
2 Im 
1 
AfCP
CP
AfCP
B0
z0 CP & CPT violation
Marcello A. Giorgi
f CP
Dt
6
Fit without the “usual assumptions”!
Fit BCP and B0flavor eigenstates (D/, q/p, z and CP left FREE)
sgn(Re CP ) D 
q p
(Re CP CP
Im z
 0.008  0.037(stat.)  0.018(syst.) [0.084, 0.068]

) Re z 
1.029  0.013(stat.)  0.011(syst.)
0.014  0.035(stat.)  0.034(syst.)
[1.001,1.057]
[0.072, 0.101]

0.038  0.029(stat.)  0.025(syst.)
[0.028, 0.104]
Preliminary
90% C.L.
 Direct limit on D/
 Test of CPT invariance
 Indirect CP in mixing
The “usual assumptions”
work!
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LOOK for N.P. in Loops?
sin(2b) = 0.741 ± 0.067stat ± 0.033syst
from charmonium channels
Results are so far CKM
compatible but…
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ss
ss
ss
dd
8
f
KS
B0  +-  sin2eff
With incomplete information
on Penguin contamination:
•
•
Measure S and Cfrom both
sinDmDt and cosDmDt terms .
Compare with predicted S
and C values for given , b,
|P/T|, and . Assume for

instance:   (97 30
21 )
BABAR
b  26
P / T  0.28
Belle 2
 2    2
From sin2eff to sin2?
isospin analysis, needs
B0 
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Belle 1
cf. Gronau and Rosner, Phys. Rev. D65, 093012 (2002)
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B0 K) :the CP fit
• Time integrated direct CP:
K
ACP
 0.28  0.17  0.08
Preliminary

ACP
 0.18  0.08  0.03
• Time dependent CP:
C  0.36  0.18  0.04
S  0.19  0.24  0.03
• Asymmetry between rates:
0.18
DC  0.28-0.19
 0.04
DS  0.15 0.25 0.03
First step towards  in B.
Full Dalitz analysis in progress.
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Toward : the BD0CP K approach
sin2 from the triangles (Gronau-Wyler method):
0
2 A( B  DCP
K)
where D0CP are CP eigenstates :
0
2 A( B  DCP
K )
BaBar measurements:
Preliminary
DCP
D0  D 0

2
BF ( B   D 0 K  )
R
 (8.31  0.35  0.20)%

0 
BF ( B  D  )
RCP
BF ( B   D0CP K  )  BF ( B   D0CP K  )

 (8.8  1.6  0.5)%
0
0
BF ( B   DCP
  )  BF ( B   DCP
 )
ACP
BF ( B   D0CP K  )  BF ( B   D0CP K  )

 0.06  0.17  0.06

0


0

BF ( B  DCP K )  BF ( B  DCP K )
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Preliminary
|Vub| from fully tagged SL decays
Recoil of fully
reconstruted B
(~4KB /fb-1)
bul signal:
MX (< MD)
( ~ 60-80%)
S/B  1.7: good!
D(*)

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Breco
Xu
Brecoil
Y(4S)
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l

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Rare B decays
b  u : tree, CKM suppressed
tree
QCD
penguin
Possible New Physics
signatures:
rates and phases
from virtual particles
in the loops
b  s,d: Radiative (QCD, EM, EW) Penguins FCNC
EM
penguin
EW
penguin
 probes b inside B
Leptonic decays: B0  l+l-, B  , B  l+, …
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Not only B Physics in BABAR !
A new state decaying into D+s(1970) and 0 has
been discovered by us and recently confirmed by
CLEO!
D+s 0
D+sK+K- + 0
D+sK+K- +
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Charm, tau discovery potential
An example: D mixing
Very small in the S.M.
 2  additional suppression

0.05 m  m
2
s
2
d
m
Another example:
lepton flavour violation
S.M., extended to include 
mixing and mass:
0
2
W
SU 3 limit
BR(t  m~ O(10
- 34)
 A window for new physics
“short distance”  x
Vcd,cs W- Vud,us
c
D0
d,s
u
D0
d,s
u
c
V*
ud,us
“long distance”  -iy
W+
V*
cd,cs
K-,
D0
D0
K+,+
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lepton number is violated in
many extensions of the S.M.
(present limits, O(10-6) are
not far from some model
predictions)
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Luminosity: Present and Future
So far in Run 3: On peak 30.02 fb-1
Off peak 2.57 fb-1
Summer 2002 and FY2002
Winter 2003:
Run 1 + Run 2
On peak 83.9 fb-1
Off peak 9.6 fb-1
92 M BB pairs
Summer 2003:
Run 3
add 40 fb-1
By end 2006:
500 fb-1
FY2003
Longer
term
By the end of the decade:
12 ab-1
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Next about sin2b
•
Extrapolated statistical and systematic uncertainties
Param.
Channel
sin2b
J/KS
Golden
D*D*
J/0
f KS
’ KS
Im( +)
S
S
S
Statistical uncertainty
(stat)/(syst)
0.08 ab-1
0.08 / 0.03
0.07 / 0.03
0.43 / 0.13
0.49 / 0.16
0.50 / 0.09
0.34 / 0.03
 L1 2
(stat)/(syst)
0.5 ab-1
0.037 / 0.018
0.031 / 0.018
0.16 / 0.07
0.20 /
0.20 /
0.14 /
Golden modes
(stat)/(syst)
2.0 ab-1
0.018 / 0.018
0.015 / 0.018
0.08 / 0.03
0.10 /
0.10 /
0.07 /
 stat   syst
(*)
at L  2 ab1
(*) This syst error of 0.018 is
dominated by DCS decays of
charm in K tagged events.
Lepton tag is not affected !
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What next for Sin 2b
Pure penguin process
B
FKs
NEW PHYSICS ?
New quanta in the loop?
The present value with 80 /fb is:
S=sin2b=-0.19-0.50+0.52 stat.±0.09syst.
With 2/ab (S) goes down to 0.1
But also B
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’ K and B
KKK
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Extapolations for sin2eff
Results (0.08 ab-1) for BFactories
Param.
S
C
BaBar
Belle
0.02  0.34  0.05 -1.23  0.41 (+ 0.05-0.07)
-0.30  0.25  0.04 -0.77  0.27  0.08
Extrapolated errors (BaBar)
Param.
Channel
S
C
+-
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(stat)/(syst)
0.08 ab-1
0.34 / 0.05
0.25 / 0.04
(stat)/(syst)
0.5 ab-1
0.12 / 0.03
0.10 / 0.03
Marcello A. Giorgi
(stat)/(syst)
2.0 ab-1
0.06 /
0.05 /
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 from B-gD0(CP)K-: projections
Recent experimental results (BaBar)
( B   D1K  )
n1 
 1.02  0.29  0.02
( B   D0 K  )


 500 D0 K  K   
( B   D1K  )
p1 
 (0.72  0.26  0.02)
( B   D0 K  )
ACP  0.17  0.23 0.08
A( B   D0 K  )
r
A( B   D0 K  )
 O (0.1)
Toy MC projections: (Fit unreliable for r = 0.1)
r=0.3 (0.5 ab-1), sin2.75 fit:sin2.72.2359.91.2o
r=0.2 (2ab-1),
sin2.75 fit: sin2.71.1458.57.4o
r=0.2 =60o D=30o
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(2ab-1) ACP=0.174 0.031
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projected errors for |Vub|
Selection:
One B reconstructed in D(*)X
Lepton momentum and neutrino mass
Kaon veto, charge balance
Fit Mx with constraints
MX distribution fit:
bul, bcl, background
Errors:
Statistical
L(ab-1) = 0.08 0.5 2.0
stat(%) = 7.0
2.8 1.4
10
0.6
Mx (GeV)
Experim. Systematic ~5% (now)  2.5%
(bcl bkgd)
Theoretical ~ 9%
(b ulabove cut)
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((mb)=90MeV)  5%
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B beam method
B factories present an unique peculiarity.
Events are pure B B and a full reconstruction
of one side allow to treat the other as a
pseudo B-beam. The study of rare decays
with neutrinos are becoming possible with
very high integrated luminosity.
h
D(*)

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“B – beam”
Breco
Y(4S)
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
l
22
Integrated luminosity vs physics
2002
2006
BaBar
 2009 ?
t  m
0 .1
Continuous
improvement
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0 .5
1 .0
2 .0
10 .  Ldt ab 1 
 sin 2
Vub Vcb sin 2 b
X sl l  , K *l l 
X s , K *
t , m
  
sin2b   
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Some comments about comparison with
Hadron machine expts.
CKM parameters
BABAR/Belle
2 ab-1
Sin2b(charmonium)
0.015stat/0.018syst
Sin2b (penguins bsss)
0.10 stat
in 2S eff(B0 
0.06 stat
eff –  ( B0   )
<10°
Sin(2b) (B0 D* )
0.15
 (B DK)
7°
|Vub|
1.4%+ Th. Unc.(now better 10%)
BTeV/LHC-B
107 s
0.025/0.014
---0.024/0.056
------<10°/<19°
----
Of course Bs mixing and decay can be studied well at hadron
machines ( and a lot of good physics from Bs)
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Rare decays - Summary
Channel
BF
bs
3.3±0.3 10-4
BK*
B  ()
510-5
210-6
25K
----
bsmm
bse+eBK*mm
BK*e+e-
6.±1.5 10-6
3.6K
bs
BK*
4.1±0.9 10-5
5.10-6
Bt
Bm
510-5
510-7
2.±1 10-6
BTeV/LHC-B (107 s)
----
2.2K/4.5K
----------
BABAR/BELLE (2 ab-1)
44.0K
6.8K(Btagged)
24.0K
1.2K
1.2K
1.4K
0.5K
0.6K
Asymmetries!
30
6
70
35
Limit< 10-8
tm
Rates…
Fully
reconstructed
B on the other
side are used
The so called
B beam
option
Bfactory and hadron machine measurements are complementary !
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What about Detector?
SVT!
BABAR is a VERY good detector: very difficult to improve it!! (On IFR barrel is the only
major intervention needed)
SVT is 98% efficient. No degradation due to irradiation has been observed so far
SVT so far tested
for rad hardness up
to 4 Mrad (OK!) rad
tests are going on.
Partial SVT
replacement is
considered by
2005. Almost 50%
of modules built as
spare.
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Instrumented Flux Return
• Instrumented Flux Return
– 2000 m2
– 342 barrel RPCs
– 432 endcap RPCs
– 32 cylindrical RPCs
• Electronics
– 3300 Front end cards
• ~ 40 mV threshold
• 16 channels connected to
alternate strips
• Gas
– 35% Freon 134a, 4.5%
iso-butane, 60.5% Argon
– 1-3 volume changes/day
• High Voltage
– > 50 10 kV HV pods
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•
•
•
•
•
BABAR RPC
Operates in limited streamer mode
Parallel high resistivity plates
(Bakelite  1011 -1012  cm )
Graphite ~100 k/
RPCs were filled 3 times with a
mixture of 70% linseed oil and 30%
n-pentane and dried by air for
several days.
Changes from L3 RPCs
– Polycarbonate buttons with lip
replaced G10 cylindrical button
– Thicker oil layer
– Single layer with strips on both
sides
– No mechanical envelope
– Nonflammable gas - low isobutane %, CBrF3 replaced by
Freon 134a C2H2F4
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Efficiency of
barrel RPCs after
production ~97%
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1999
•
•
IFR complete May 99
RPC efficiencies good
• Warning signs
– Some RPCs with > 100 mA
were disconnected
• With collision data
– HV current limitations force
reduction in # of RPCs
• Average Efficiency low ~85%
•
•
•
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Barrel is about 50% of total IFR
coverage
Forward Endcap about 40%
Decision was taken in 2000 to
upgrade the Forward Endcap
with new RPC (higher QA/QC
level) and with more absorber.
29
New Forward EndCap from
nov 2002
RPC belt
Terminology:
19 slots
and 15 RPC layers
Slot18/19
5 brass layers
(slot 8,10,12,14,16)
Absorber Segmentation
7 layers 2 cm
1 layer 7 cm
2 layers 9 cm
2 layers 13 cm
2 layers 10cm
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total 85 cm
30
RPC problems
(post mortem photo)
Linseed oil – uncured oils
move under HV and warm
temperatures
Excess oil
Graphite layer develops
high resistance
Gas inlet Debris
Internal debris and
whiskers
5% of barrel has HV
problems before New HV
distribution
Whiskers
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~50% of the barrel
modules leak (many have
normal efficiency)
Front End electronics
problems
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Opposite
side
31
IFR Barrel Upgrade
Many RPCs die since 1999.
Fraction effectively dead is now
almost 40%
Muon selectors losing efficiency
A committee was setup in
september 2002 to evaluate
physics motivation for a IFR
upgrade and technology.
B.Ratcliff and C.Hearty were
chairing the committee.
After 3 months the committee
Presented its
recommendations to BaBar.
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32
FINAL DOCUMENT May22,2003
Committee proposes to increase the thickness of the absorber
and to replace the bakelite RPC with a more robust detector
(Limited StreamerTube).
INSTALLATION
in 2004 & 2005
We have submitted a proposal and ask for your approval .
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33
Summary
Babar apparatus is generally very robust and can cope with high
luminosity environment above 10 34 . Decision has been taken
to upgrade the IFR Barrel with a different technology well
established and robust (LST).
Preliminary measurements of pure penguin processes for
sin2b, measurements of Vub, B->DK, B->including Dalitz
plot analysis.
FUTURE –
In 2005 complete the installation of the IFR
Barrel. Install the Spare modules of SVT, to replace the heavily
irradiated modules on horizontal plane.
Approach the precision measurement with 0.5/ab of integrated
luminosity . Towards more than 1.0/ab explore possible openings
for new physics.
Study of CP asymmetries but also rare decays in b, c and tau
sectors.
Profit from full reconstruction of one B :
SLAC 06/12/03
EPAC meeting
“ Pseudo B beam”
Marcello A. Giorgi
34
BACKUP
SLIDES
SLAC 06/12/03
EPAC meeting
Marcello A. Giorgi
35
Flavour mixing and CP,T,CPT
Dm=mH-m L  2|M12|  0.5ps-1
D=H-L  |M12|Re (12/M12)
1/ 1.6 ps
D
SM
q
1
p
CP and T Violation in mixing
As in K sector where k=(p-q)/(p+q)
mc2
q
 1  4 2 sin b  5 104
p
mt
SLAC 06/12/03
EPAC meeting
~O(10-3)
SM
Marcello A. Giorgi
36
Flavour mixing and CP,T,CPT
CP an CPT conservation if H11=H22
z2
M  i 2
Dm  i 2D
 
z0
11  22 
2
M  M 22 
M  11
_
_
Prob(( B  B ),t)  Prob(( B  B 0 ),t)
0
0
0
2
CP and CPT VIOLATION
Assumptions made in the usual sin2b analysis:
D  H   L  0
q

p

i
M 12  2i 12
M

M

(11  22 )
11
22
2

1
z

0
i
M 12  2i 12
Dm  2 D
SLAC 06/12/03
EPAC meeting
Marcello A. Giorgi
37
Time Dependent CP asymmetries
CPV in mixing-decay interference
direct CPV
dN exp(–|Dt|/tB) ( 1 ± D (S sin(DmDt) - C cos(DmDt)) )  R
S
2
1 
2
C
1 
2
1 
2
Flavour tag
Amplitude ratio
B0fcp/B0fcp
CP eigenvalue
B mixing
D mis-tag dilution
R time resolution
q Vtb*Vtd
2ifM


e
p VtbVtd*
Measured from data (Flavour sample)!
SLAC 06/12/03
EPAC meeting
Marcello A. Giorgi
38
Search for B+ t+
Preliminary
Semileptonic tags: BF(B+ t+) < 4.910-4 (90% CL)
Fully reco tags:
BF(B+ t+ ) < 7.710-4 (90% CL)
cosqB,Dl for B  D0X tags
combined:
< 4.1  10-4
Total signal-side neutral energy


D0
t
Y(4S)
B t candidate
Semileptonic tag
SLAC 06/12/03
EPAC meeting
Marcello A. Giorgi

39
RPC efficiency 00
Gas change
-1.4% /month
-0.56%/month
-1.4% /month
SLAC 06/12/03
EPAC meeting
Marcello A. Giorgi
40
•
Detector
studies
Realization that the RPC
efficiencies did not recover
after cooling spurred
detector studies
A wide spread of plateau curves
were measured.
– Efficiency was computed as a
function of position
• Limited tests were carried
out during accesses or on a
few chambers
– Lowered barrel temp. to 17
C.
– Reversed HV
– Increased gas flow
– Lowered discriminator
threshold
SLAC
06/12/03
Marcello A. Giorgi
– Put
weights over inefficient
EPAC meeting
regions
41
D. Piccolo
RPC radiography
The RPC efficiency
was mapped in 2D
showing irregular
regions of reduced
efficiency.
SLAC 06/12/03
EPAC meeting
Marcello A. Giorgi
42
Occupancy
plots for run
38637
Brick shields ~.8
m from L 16
SLAC 06/12/03
EPAC meeting
Marcello A. Giorgi
43