babar status and future plans
DESCRIPTION
BABAR Status and Future Plans. Marcello A. Giorgi on behalf of BaBar Collaboration QCD@Work2003 Conversano (Ba)-Italy. BaBar Physics GOALS. 1)Search for CP violation in B meson decays largely predicted by the Standard Model - PowerPoint PPT PresentationTRANSCRIPT
Conversano(Ba) 17/106/03 QCD@Work2003
Marcello A. Giorgi 1
BABAR Status and Future
Plans
BABAR Status and Future
Plans Marcello A. Giorgi
on behalf of BaBar Collaboration
QCD@Work2003
Conversano (Ba)-Italy
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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 (2001)
TRY to open windows on new Physics beyond Standard Model
More precise CKM measurements, Rare B decays, Charm study, Tau rare decays .
BaBar Physics GOALS
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CP in Standard Model
CKM quark mixing matrix
2
2 4
3
23
2
( )
(
11
21
1 ( )2
11 )
ud us ub
cd cs cb
td ts tb
A iV V V
V V V V A O
V V VAA i
bulB() l
CP Violating phase
BD(*)lbcl
B() B0 Mixing
Unitarity
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O(2)
Representing unitarity relations as
Unitarity Triangles The unitarity condition of CKM matrix VV+=V+V=1 gives 6 relations between the matrix elements as :
VudV*ub + VcdV*cb + VtdV*tb =0
(in this relation the 3 terms have the
same order of magnitude ~O(3) and it can be graphically represented in a complex plane as a triangle with sides of comparable length. Other relations have terms of different order of magnitudes. E.g.:
VusV*ub + VcsV*cb + VtsV*tb =0
O(4) O(2)
Overconstrain and the 4 parameters of CKM , A
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Decaying amplitudes in SM
Tree
Penguin
Quarks Leading Term Secondary SampleBd Angle ccs Vcb Vcs* =A2 VubVus*=A4(i) J/ Ks
T+P(c-t) P(u-t)
sss VcbVcs*= A2 VubVus*=A4(-i) Ks P(c-t) P(u-t)
ccd Vcb Vcd* =A2 Vtb Vtd* =-A3 (1-+iD+D- (LT) T+P(c-u) P(t-u) uud/ddd VubVud*=A3(i) Vtb Vtd* =-A3 (1-+ia(LT)
T+P( u-c) P(t-c)
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Experimental ingredients: BaBar optimized for time dependent CP
asymmetries
+e-e
z
Brec
Btag 4s
(4S) = 0.55
Coherent BB pair
B0
B0
Start the Clock
zc
zt
1
Tag vertex reconstructio
n
Tag vertex reconstructio
n
FlavorTaggingFlavor
Tagging
Exclusive B Meson and Vertex Reconstruction
Exclusive B Meson and Vertex Reconstruction
0sK
J/
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PEP-II Asymmetric B-Factory
(4 )e e S BB B B production threshold
9 GeV e- on 3.1 GeV e+
(4s) boost in lab frame
= 0.55
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BABAR
DCH
EMC
DIRC
COIL
IFR
SVT
The The BBAABBARAR CollaborationCollaboration 10 Countries 75 Institutions 579 Physicists
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Silicon Vertex Tracker• dE/dx measurement for PID.• Measure the track parameters just outside the beam pipe.• 5 layers of double sided silicon stripsSingle hit resolutions in the inner
layers d0 55 m, z0 65 mSoft from the D* D s decays extends below pT< 150 MeV/c
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Detector of Internally Reflected Cherenkov light
K/ discrimination
144 fused silica bars (1.7 cm thick) Cherenkov light transported by internal reflection
11000 PMTs,
25-50 p.e./particle
10 mrad single
photon resolution
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ElectroMagnetic Calorimeter
6580 CsI(TI) crystals Barrel 48 rings in , 120 crystals per ring Forward Endcap 8 rings in , 80/100/120 crystals per ring Angular coverage: 126o in , 360o in reconstructed from mass width varying from 5 to 9 MeV/c2 for 0.2<EGeV
Electron i.d. efficiency up to 90% misidentification probability at the level of
1 10-3.
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Instrumented Flux Return
Number of active elements342 barrel RPC432 endcap RPC32 cylindrical inner RPC
Total surface covered2000 m2
Gas mixtureArgon 60.5%Freon 35%Isobutane 4.5%
Electronics50000 channels
Muon identification efficiency for tight criteria 65% for a misidentification at the level of 2%
Neutral hadrons (namely KL) are detected after their
interaction with iron.Only direction is measured
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Time dependent rate,flavor mixing and CP,T,CPT
Time dependent rate:dN exp(–|t|/B) ( 1 ± D (S sin(mt) - Ccos(mt)) ) R
2
2
21
1
1
Im2
CS
CPV in Mixing -DecayCPV direct
cp
cp
cp A
A
p
q___
D is the mis-tag dilution
R is the time resolution
0B
0B
CPfCP
mix
ing decay
CPfA
CPfA
t
2
22
im
iMz
z0 CP & CPT violation
1p
q CP and T Violation in mixing
42
2
105sin41 t
c
m
m
p
qSM
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Sin2 and decay
s
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Time dependent analysis B
*Assume no direct CPV
* From control sample B
Expect zero!
In SM Ss=sin 2
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LOOK for N.P. in Loops?
from charmonium channelsResults are so far CKM
compatible but…
s
s
s
d
KS
s
s
s
dsin(2) = 0.741 ± 0.067stat ± 0.033syst
?
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B0 +- sin2eff
With incomplete information on Penguin contamination:• Measure S and Cfrom
both sinmt and cosmt terms .
• Compare with predicted S and Cvalues for given , , |P/T|, and . Assume for instance:
From sin2eff to sin2?
isospin analysis, needs B0
22
3021
28.0/
26
)97(
TP
cf. Gronau and Rosner, Phys. Rev. D65, 093012 (2002)
BABAR
Belle 1
Belle 2
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B0 ) the CP fit• Time integrated direct CP:
• Time dependent CP:
• Asymmetry between rates:
08.017.028.0 KCPA
03.008.018.0 CPA
04.018.036.0 C
03.024.019.0 S
03.00.250.15 S
04.00.28 0.180.19-
C
First step towards in B. Full Dalitz analysis in progress.
Preliminary
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Toward : the BD0CP K approach
sin2 from the triangles (Gronau-Wyler method):
BaBar measurements:
2
DD
:seigenstate CP are Dwhere00
CP
0CP
D
)(2 0 KDBA CP
)(2 0 KDBA CP
)%20.035.031.8()(
)(0
0
DBBF
KDBBFR
)%5.06.18.8()()(
)()(00
00
CPCP
CPCP
CP DBBFDBBF
KDBBFKDBBFR
06.017.006.0)()(
)()(00
00
KDBBFKDBBF
KDBBFKDBBFA
CPCP
CPCP
CP
Preliminary
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|Vub| from fully tagged SL decays
Brecoil
BrecoD(*)
Y(4S) l
Xu
Recoil of fully reconstruted B (~4KB /fb-1)
bul signal:MX (< MD)( ~ 60-80%)
S/B 1.7: good!
Preliminary
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Rare B decays
b u : tree, CKM suppressed
b s,d: Radiative (QCD, EM, EW) Penguins FCNC
Leptonic decays: B0 l+l-, B , B l+, …
tree
QCDpenguin
EMpenguin
EWpenguin
probes b inside B
Possible New Physicssignatures: rates and phasesfrom virtual particlesin the loops
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Not only B Physics in BABAR !
A new state at m=2317 MeV decaying into D+
s(1970) and 0 has been discovered by us and recently confirmed by CLEO and BELLE !
D+s 0
D+sK+K- + D+
sK+K- + 0
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An example: D mixingVery small in the S.M. 2 additional suppression
A window for new physics
Charm, tau discovery potential
limit3
005.0 222
SU
mmm Wds
lepton number is violated inmany extensions of the S.M.(present limits, O(10-6) are not far from some model predictions)
D0
c
c
u
ud,s d,s
W-
W+
Vcd,cs
V*cd,csV*
ud,us
Vud,us
D0
“long distance” -iy
“short distance” x
D0 D0
K-,
K+,+
Another example: lepton flavour violation
S.M., extended to include mixing and mass:
BR( O(10 - 34)
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An Example: D0 Mixing
• y parameter from ratios of D0 K, KK, lifetimes:Comparison with previous
Measurements:
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• Wrong sign (WS) decays D0! K+- can occur directly DCS or through mixing followed by the right sign (RS) CF decay:
• WS decays are not exponential:
… and D0 Mixing from Wrong Sign Decays
MixingDCS Interference
CFMixing
DCS
units of 0
Preliminary
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Luminosity: Present and Future with PEPII “adiabatic scenario”
FY2002
FY2003
Longerterm
So far in Run 3: On peak 30.02 fb-1
Off peak 2.57 fb-1
Present peak 6.5 10 33 L/day=370 pb-1
Before end of the decade: 12 ab-1
Summer 2002 and Winter 2003:Run 1 + Run 2On peak 83.9 fb-1
Off peak 9.6 fb-1
92 M BB pairs
Summer 2003:Run 3add 40 fb-1
By 2006: 500 fb-1
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Path to higher PEP-II luminosity
Luminosity 4.6E331E34 2E34 4E34 UnitsI+ 1800 2700 3600 4500 mAI- 950 1400 1760 2000 mABeta y* 11.5 9 7 4.5 mmBeta x* 50 50 50 50 cmBunch Length 1.3 1.0 0.8 0.5 cm# bunches 792 1300 1500 1600Vert. Emitt. 2.5 1.4 1.1 0.7 nmHoriz. Emittance 40/50 30/45 32/47 40/48 nm (+/-)Crossing angle 0 0 0 ~+/-8 mradTune shifts (x/y) 7.5/4.58.0/5.78.2/6.08.4/6.3x100Number RF stations 7 10 13 15Date hardware ready Jan 02 Dec 02Dec 04Nov 06Date for luminosity Jun 02 July 03 Dec 05Dec 07
(J.Seeman, BaBar Collaboration meeting, Sept.2002)
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What about the BaBar Detector?BABAR is a VERY good detector: very difficult to improve it!!
No problem expected to the performance for L up to 4 1034 cm-2 s –1
Look at the innermost and outermost systems.
SVT IFR
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SVTSVT is 98% efficient. No degradation due to irradiation has
been observed
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 total has been built and are on the shelf.
Instrumented Flux Return
Efficiency for muon and Klong detection has decreased since the beginning in 2002 the endcap has been upgraded using new RPC and thicker absorber
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Absorber Segmentation
7 layers 2 cm
1 layer 7 cm
2 layers 9 cm
2 layers 13 cm
2 layers 10cm
total 85 cm
New Forward EndCap from nov 2002
Terminology: 19 slots and 15 RPC layers
RPC belt
Slot18/195 brass layers(slot 8,10,12,14,16)
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IFR Barrel Upgrade
Muon selectors losing efficiency
Decision taken to increase the thickness of the absorber and to replace the bakelite RPC with a more robust detector (Limited StreamerTube).
INSTALLATION 2004 &2005
Many RPCs die since 1999. Fraction effectively dead is now almost 40%
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Next about sin2• Extrapolated statistical and systematic uncertainties
Statistical uncertainty Golden modes
Param. Channel (stat)/(syst) 0.08 ab-1
(stat)/(syst) 0.5 ab-1
(stat)/(syst) 2.0 ab-1
sin2 Im(+) S S S
J/KS Golden D*D* J/0 KS ’ KS
0.08 / 0.03 0.07 / 0.03 0.43 / 0.13 0.49 / 0.16 0.50 / 0.09 0.34 / 0.03
0.037 / 0.018 0.031 / 0.018 0.16 / 0.07 0.20 / 0.20 / 0.14 /
0.018 / 0.018 0.015 / 0.018 0.08 / 0.03 0.10 / 0.10 / 0.07 /
21 L
1syststat ab2at L
(*)
(*) 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 2
Pure penguin process B Ks
The present value with 80 /fb is:
S=sin2=-0.19-0.50+0.52 stat.±0.09syst.
With 2/ab (S) goes down to 0.1
But also B ’ K and B K K K
NEW PHYSICS ?
New quanta in the loop?
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Results (0.08 ab-1) for BFactories
Param. Channel (stat)/(syst) 0.08 ab-1
(stat)/(syst) 0.5 ab-1
(stat)/(syst) 2.0 ab-1
S C
+-
0.34 / 0.05 0.25 / 0.04
0.12 / 0.03 0.10 / 0.03
0.06 / 0.05 /
Extapolations for sin2eff
Extrapolated errors (BaBar)
Param. BaBar Belle S C
0.02 0.34 0.05 -0.30 0.25 0.04
-1.23 0.41 (+ 0.05-0.07) -0.77 0.27 0.08
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r=0.2 (2ab-1), sin2fit: sin2
from B-D0(CP)K-: projections
Recent experimental results (BaBar)
Toy MC projections: (Fit unreliable for r = 0.1)
02.029.002.1)(
)(
0
11
KDB
KDBn
)02.026.072.0()(
)(
0
11
KDB
KDBp
r=0.3 (0.5 ab-1), sin2fitsin2
08.023.017.0 CPA
ACP=0.174 0.031
r=0.2 =60o =30o
(2ab-1)
KKD0500
)1.0(
)(
)(
0
0
O
KDBA
KDBAr
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projected errors for |Vub|
Selection:One B reconstructed in D(*)XLepton momentum and neutrino massKaon veto, charge balanceFit Mx with constraints
MX distribution fit:
bul, bcl, backgroundErrors:
Statistical L(ab-1) = 0.08 0.5 2.0 10 stat(%) = 7.0 2.8 1.4 0.6
Experim. Systematic ~5% (now) 2.5% (bcl bkgd)
Theoretical ~ 9% ((mb)=90MeV) 5% (b ulabove cut)
Mx (GeV)
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B beam method
“B – beam”
BrecoD(*)
Y(4S) l
h
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.
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Integrated luminosity vs physics
2sin
1 abLdt1.0 0.1 .105.0 0.2
BaBar2006 2009 ?
cbub VV 2sin2sin llKllX s
*, *, KX s
,
2002
Continuous improvement
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Some comments about comparison with Hadron machine expts.
Lumi(10 33) bb(10-33) bb(107/year) bb /qq
Bfactories 10 1.1 11 3 10-1
BTeV 0.2 100000 20000 1 10-3
LHC-B 0.15 500000 75000 5 10-3
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Some comments about comparison with Hadron machine expts.
CKM parameters BABAR/Belle BTeV/LHC-B 2 ab-1 107 s
Sin(charmonium) 0.015stat/0.018syst 0.025/0.014Sin (penguins bsss) 0.10 stat ----in S eff(B0 0.06 stat 0.024/0.056
eff – ( B0 ) <10° ----Sin() (B0 D* ) 0.15 ---- (B DK) 7° <10°/<19°|Vub| 1.4%+ Th. Unc.(now better 10%) ----
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 - SummaryChannel BF BTeV/LHC-B (107 s) BABAR/BELLE (2 ab-1)
bs 3.3±0.3 10-4 ---- 44.0K 6.8K(Btagged)
BK*10-5 25K 24.0KB ()10-6 ---- 1.2K
bs±1.5 10-6 3.6K 1.2Kbse+e- 1.4KBK*±1 10-6 2.2K/4.5K 0.5KBK*e+e- 0.6K
bs±0.9 10-5 ---- 30BK*10-6 ---- 6
B10-5 ---- 70B10-735
Limit< 10-8
Bfactory and hadron machine measurements are complementary !
Rates…Fully
reconstructed B on the other side are used
The so called
B beam option
Asymmetries!
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SummaryBabar apparatus is generally very robust and can cope with
high luminosity environment above 10 34 (2004). 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 sin2, measurements of Vub, B->DK, B->includingDalitz 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 (in a more aggressive scenario 4 10 34 after 2007) 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 : “ Pseudo B beam”
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BACKUP SLIDES
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3-body (+-0) Dalitz analysis for
B0+ – - B00 0 Interference
Region
B0+ – - B0 – + Interference
Region
00
00
, ,
, ,
A A A
A A A
11 parameters (“fundamental”):
remove overall phase & normalization: 9 parameters
00, , , , ,T P T P T
Suffers from mirror solutions
No mirror solutions. Does not depend on particular weak phase decomposition
10 parameters (“amplitudes”):
remove overall phase & normalization: 8 parameters
obtain fundamental parameters from subsequent fit.
…work in progress
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Flavour mixing and CP,T,CPT
m=mH-m L 2|M12| 0.5ps-
1
1/ 1.6 ps
=H-L |M12|Re (12/M12)
SM
1p
q CP and T Violation in mixing
42
2
105sin41 t
c
m
m
p
q
As in K sector where k=(p-q)/(p+q) ~O(10-3)
SM
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Flavour mixing and CP,T,CPTCP an CPT conservation if H11=H22
2
22
im
iMz
2
2211 MMM
2
2211
t)),BB((Probt)),BB((Prob_
0_
000
0z
CP and CPT VIOLATION
Assumptions made in the usual sin2 analysis:0H L
12 122
12 122
1i
i
Mq
p M
11 22 11 222
2
( )0
i
i
M Mz
m
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Search for B+ +
B candidate Semileptonic tagD0
Y(4S)
cosB,Dlfor B D0X tags
Total signal-side neutral energy
Semileptonic tags: BF(B+ +) < 4.910-4 (90% CL)Fully reco tags: BF(B+ + ) < 7.710-4 (90% CL)
combined: < 4.1 10-4
Preliminary
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Upper bounds on = 2eff-2
0
0002
BF
BFsin
B
B
Grossman-Quinn bound: BaBar, present data:051
BaBar, extrapolations:vs BF(00), at fixed Luminosity
Small gainwith lumi
Most powerful at small BF
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0 2.5 5 7.5-2.5-5-7.5
0
10
20
30
-10
-20
-30
Meters
Ce
ntim
ete
rs
2x1034 Interaction Region with a ±3.25 mrad Xangle
M. Sullivan Jun. 14, 2000
QD1
QD4QF5
QF2
QD4 QF5
QD1 QD1
QD1
QF2
Extra focusing
Extra focusing
3.1 G
eV
3.1 G
eV
9 GeV
9 GeV
100 kW
100 kW
20 kW
20 kW
E36 B-Factory +/- 12 mrad xing angle Q2 septum at 2.5 m 8 GeV
30
20
10
0
-10
-20
-30
cm
-7.5 -5 -2.5 0 2.5 5m
Q1
Q1Q1
Q1
Q2
Q4Q5
Q2
Q4Q5
2 cm radius and 1 cm radius beam pipes
The 1 cm radius beam pipe intercepts about 5 kW of power from the LER and nearly the same amount from HER
Minimum amount of material in the detector beampipeThis conflicts with having enough SR shielding (usually a thin coating of Au) to keep detector occupancy at acceptable levelsMinimum radius for the beam pipe
This must be balanced with the requested thickness of the beam pipe. The smaller the beam pipe the more power it must be able to handle (kW).