to superb or not to superb ? francesco forti infn-pisa ifae, torino, 14-16 aprile 2004 babar tm and...
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To SuperB or not to SuperB ?
Francesco FortiINFN-Pisa
IFAE, Torino, 14-16 Aprile 2004
BabarTM and © Nelvana
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 2
That is the SuperQuestion !
• What: – PEP-II/Babar and KEK-B/Belle operate currently at a
luminosity 1034 cm-2s-1 with – Integrated sample of about 1ab-1 for each machine by 2009– Upgrade ideas/proposals to increase luminosity by a factor 10 to 100,
for a sample size of 5-50 ab-1.• Why:
– High precision Standard Model Unitarity Triangle (UT) measurements– New Physics (NP) contributions to rare decays B.R. & ACP
– Distinctive patterns may discriminate between models• How:
– Different upgrade scenarios are being considered– Detector and machine complexity/cost undergo a phase transition
around a few x 1035 cm-2s-1 mainly because of backgrounds• When:
– in the era of LHCb, BTeV and LHC experiments.– Competitiveness and complementarity with hadron machines is a real
issue.
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 3
The Physics Menu• UT sides measurements
– From (semi)leptonic decays, inclusive or exclusive
– |Vub|, |Vcb|, |Vtd|• UT angles precision measurements
– bs penguin transitions very sensitive
– CPV Asymmetries in BKs, Ks0 compared with sin2.– Sin2 measurement with B and ; direct CPV– measurement with BDK or similar channels.
• Rare decays– Exclusive and inclusive b sBFs, direct asymmetries, photon
helicities– Exclusive and inclusive b sl+l- BFs, AT, AL, AFB, CP asymmetries– B decays to states with large missing energy, such as B(d,s) +-, B
K(*), b s, B D(*), B XC
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 4
NP in B physics
• In most cases the rates, particularly in hadronic decays, suffer from large theory uncertainties and not considered suitable for NP studies.
• The best NP observables in B physics seem to be:– Time-dependent CPV asymmetries in bsss(bar), bs
dd(bar), and bs– Direct CP asymmetries in some cases (e.g. b->s/d-
maybe)– Ratio of rates (maybe)– bsl+l-: CP asym., Forward-Backward asymmetry & its CP
asym.– Rate of very rare decays Bl+l-– BXrate and polarization– Other near zeros: e.g. CPV in mixing
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 5
Why – The Physics Case
• Find NP effects in flavour physics.– Strong endorsement from the B experts in the theory
community for the potential of direct NP studies with super b-factories.
– What is the scaleof NP ?
• NP is 1 TeV fromhierarchy problem.
• …But NP >1000TeVfrom flavor bounds.
– Model dependanceis unavoidable.
– Theoretical uncertaintycan be crucial.
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 7
Ingredients of the physics case
• Experimental sensitivities for B experiments (2 to 50 ab-1)– Statistical and systematical
• Theoretical uncertainties of the reference points based on SM. – Given these uncertainties, is there still any sensitivity to
NP? • Comparison with sensitivities from the planned hadron
collider experiments. – Can the super-B measurements compete and/or provide
better information than Hadron experiments?• If possible, range of expected (NP-SM) values for these
observables given the physics landscape in the LHC era (2010-2012?). – Very hard to do. What changes if NP is (or is not)
discovered at LHC ?
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 8
Sources
• A lot of activity has been going on in the past couple of years– Study groups, Workshops, Theorists involvement– Many detailed, in-depth studies.
• Try to summarize numbers and conclusions from– Several Belle workshopsbelle.kek.jp/workshops
– Two Babar workshopswww.slac.stanford.edu/BFROOT/www/Organization/1036_Study_Group
– Hawaii joint workshopwww.phys.hawaii.edu/~superb04
• In the following tables:– several empty spaces
• Different assumptions, missing studies, etc.– LHCb and BTeV numbers always come from their
presentations – Updating…
Standard Model ReferenceObservable SM: reference point SM: Expected range
Time dependent CP Measurementsbsss(bar) & bsdd(bar) & bs
S(Bs) ~Sin2 |sin2S|<0.25
S(B’Ks) ~Sin2 |sin2S|<0.3
S(Bs ) ~Sin2 |sin2S|<0.2
S(BK*0 (with K*s ) ~2(ms/mb) Sin2 |S|<0.1 (?)
bs/dbs/dl+l-): Rates and Acp(dir)
Acp(b->s Acp(b->d 0.6% [-16%] (?)
(BK*+ (BK*0 sum) ~0 (isospin breaking) 5 to 10% (?)
(bd(bs |Vtd/Vts| (from mixing)
cp(Bs l+l-)
cp(Bd l+l-)
<0.5% (0.05% for K* l+l-)~(4.4+/-4 )%
B(BKB(BKe+e-) 1 1.0+/-0.0001
AFB(K*l+l-):s0(zero crossing) 0.162+/-0.008 (5%)
AFB(K*l+l-):CP asymmetry ~0
CPV in mixing: (|q/p|) ~1
Very rare decays: B B
XRate and polarization ~2%
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 11
Unitarity Triangle - Sides
Unitarity Triangle - Sides e+e- Precision 1 YearPrecision
Measurement Goal 3/ab 10/ab 50/ab LHCb BTeV
Vub (inclusive) syst =5-6% 2% 1.3%
Vub (exclusive) () syst=3% 5.5% 3.2%
Vcb (inclusive)
Vcb (exclusive)
fb (B) SM: ~5x10-7
fb B(Btn) SM: ~5x10-5 3.3 6 13fb to
Vtd /Vts ( Theory 12% ~3% ~1%
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 12
Unitarity Triangle - Angles
Unitarity Triangle - Angles e+e- Precision 1 Year Precision
Measurement 3/ab 10/ab 50/ab LHCb BTeV
SBR’s isospin) 6.7 3.9 2.1 - -
() (Isospin, Dalitz) (syst 3) 3, 2.3 1.6, 1.3 1, 0.6 2.5 -5 4
() (penguin, isospin, stat+syst) 2.9 1.5 0.72
(J/ KS) (all modes) 0.3 0.17 0.09 0.57 0.49
(BD(*)K) (ADS) 2-3 ~10 <13
(all methods) 1.2-2
Theory: ~5%, ~ 1% ~0.1%
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 13
CP Violation in bs penguins
Rare Decays – New Physics – CPV e+e- Precision 1 Year Precision
Measurement Goal 3/ab 10/ab 50/ab LHCb BTeV
S(B0fKS) SM: <0.25 16% 8.7% 3.9% 16%? 7%?
S(B0KS+KL) SM:<0.25
S(B'Ks )SM:<0.3 5.7% 3% 1%
S(BKs)SM:<0.2 8.2% 5% 4% (?)
S(BKspg) SM:<0.1 11.4% 6% 4% (?)
ACP (bs SM: <0.6% 2.4% 1% 0.5% (?)
ACP(BK*) SM: <0.5% 0.59% 0.32% 0.14% - -
CPV in mixing (|q/p|) <0.6% X X
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 14
More Rare decays precision
Rare Decays – New Physics e+e- Precision 1 Year Precision
Measurement Goal 3/ab 10/ab 50/ab LHCb BTeV
bd / (bs - -
B(BD(*)tn) SM: : 8x10-3 10.2% 5.6% 2.5% - -
B(Bsnn) (K-,0, K*-,0) SM:Theory ~5%1 excl: 4x10-6
~3 - -
Binvisible) <2x10-6 <1x10-6 <4x10-7 - -
Bd ) - - 1/2 1/2
Bd ) - - - -
) <10-8 - -
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 15
bsl+l- precision
New Physics – Kl+l-, sl+l- e+e- Precision 1 YearPrecision
Measurement Goal 3/ab 10/ab 50/ab LHCb BTeV
(BK/(BKe+e-) SM: 1 ~8% ~4% ~2% X X
ACP(BK* +-) (all) (high mass)
SM: < 0.05%
~6%
~12%
~3%
~6%
~1.5%
~3%
~1.5%
~3% (?)
~2%
~4% (?)
AFB(BK*l+l-) : s0
AFB(BK*+-) : ACP
SM: ±5%
~20% ~9% 9% ~12%
AFB(Bs+-) : ŝ0 27% 15% 6.7%
AFB (Bs+-) : C9 , C10 36-55% 20-30% 9-13%
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 16
Bd- unitarity m(Bs) B->Ks B->Ms indirect CP
b->s direct CP
mSUGRA closed small small small small small
SU(5) SUSY, GUT + R
(degenerate)closed large small small small small
SU(5) SUSY, GUT + R
(nondegenerate)closed small large large large small
U(2) Flavor symmetry large large large large large sizable
Unitarity triangle Rare decay
Pattern of Deviation from SM Predictions
• In most cases SM predictions are sufficiently under control as to motivate these highly sensitive measurements
• NP effects on B and physics are model-dependent– In this context, model-dependent is not a dirty word– In fact, the pattern of New Physics effects in the flavor sector is
diagnostic of the type of SUSY-breaking
Y.Okada
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 17
The international scene
• KEK-B/Belle: A letter of intent has been put forward in February 2004 for a Super KEK-B machine and a Super Belle detector.– Luminosity ranges from 1x1035 to 5x1035
– Detector upgrades include:
• PEP-II/Babar: A “Roadmap committee” is preparing a report summarizing discussions and studies done over the past couple of years. – Current direction is to propose a “upgradable platform”:
• Start with 2x1035 machine and detector, but already include an upgrade path to 7-8x1035 for the 10ab-1/year goal.
– Detector upgrades include
– Base detector possible with current technology, while full upgrade will require significant R&D
•Silicon striplets•Small cell drift chamber•Pure CsI calorimeter endcap
•Silicon striplets thin pixels•Small cell drift chamber all silicon tracker•Pure CsI calorimeter endcap Liquid
Xenon or LSO xtals
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 18
The OSBF Principle
• a.k.a. “One Super B Factory”• It is unlikely that the HEP community has enough
resources to build more than one Super B Factory– Encourage collaboration between Babar and Belle
communities (and others) to join efforts– Joint workshop in January 2004 (Hawaii), second of a
series, more to comehttp://www.phys.hawaii.edu/~superb04/
• Approval process lengthy– Connected to global funding political decisions:
• ITER, NLC– Unlikely to have serious funds before 2008– Only if there is overall community agreement and
support
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 19
Conclusion and outlook
• A 10ab-1/year Super B Factory has a real discovery potential– NP effects in loops are significant and accessible– In the LHC era
• The LHC experiments will measure the NP masses• The B experiments will measure couplings
– Precision UT measurements can help sort out things• It is fully competitive with LHCB/BTeV
– No Bs, but same or better precision with almost anything else
– Very clean sample (including recoil technique)– Accessibility of channels with 0
• Are there enough resources ?– Need to design new collaboration form between Belle and
Babar– External input/additions are welcome
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 21
Exclusive Charmless Decays
BF measurement S/B
tot) 500fb-1
tot) 10ab-1
B B ll >10 ~14% ~4%
B B ll ~4 ~15% ~5%
B B ll ~2.5 ~16% ~6%
B B ll >10 ~11% ~3%
B B ll ~2 ~15% ~6%
*Assumes negligible systematic error from FF and uses rough estimate of exp. syst. error
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 23
Toy MC Study for 2
0.5 ab-1 1 ab-1
2 ab-1 10 ab-1
0 0 0 0
6
,
2.5,1.5 10
BF B B
Assumes
BABAR meas
Scaled from present efficiencies/backgrounds
Isospin analysis in
channel
BABAR Long-Range Task
Force
BF(B0π0 π0) = 2.1 ± 0.6 ± 0.3 x 10-6
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 24
Measurement
sin2 in BD0K (GW, ADS)
Recent developments• BD0
(CP)K
• BD0(non-CP)K, D0K
sin(2+) • B0D(*(*))(*)
• B0DK• D0K0
• Use all methods
– Will measure to ~ 2° (%) (stat) or less at 10 ab-1
– Only ambiguity is left• Excluded theoretically?
– The error is so small that ambiguities won’t matter
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 25
Error on angles
0.5 ab-1
5 ab-1
50 ab-1
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 26
Intriguing Hint from Penguins?
Present average for
.b sss0.24 0.15
~3.1 sigma below charmonium
modesIf central value
remains as is, this would become ~5
sigma by 2005
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 27
Error projection for ACP
0SK
* *D D0,SK
0/ SJ K
10-2 10-1 1 10 10210-2
10-1
1.02009
Integrated Luminosity
Err
or
on
ACP 2006
PEP-II, KEKB Super B-Factory >2010
sin 2
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 28
Use TDCP to probe the helicity structure: (but limited to K*0Ks ~
David Atwood, Michael Gronau, Amarjit Soni (1997)
PRL 79 ,185(1997)
W
t
b s
* 2 sin 2 0sK
b
mS
m
*LK
mixing
CPfA
CPfA
*RK
Helicity Flip Suppressed by ms/mb
Expect:
0.1 ab-1 2 ab-1 5 ab-1 10 ab-1 50 ab-1 LHCB BTEV
S(Ks 0.6 0.14 0.09 (0.12)
0.06 0.04(?) X X
Soni: ms is the “current” mass: ms ~150 +/- 50 MeV), mb ~5 GeV
Theory error ~0.01 to 0.02 (??) (~30% of SM value of S)
~0.042B0 (bar)
B0
The dominant SM amplitude gives: bsL, b(bar)sR
NP can modify helicity structure: e.g. LR symmetry, higgs in loops
BKs
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 29
Recoil Physics
The final efficiency is ~0.4% (per bbbar pair) ~4000 B/fb-1 (at 30% purity) 1500 B0/fb-1
2500 B+/fb-1
> 107 recoil Bs in 10ab-1
Recoil cinematics well knownRecoil flavor and charge is determinedEvent closure needed with neutrinos
IFAE, April 14, 2004 F.Forti - To SuperB or not to SuperB ? 31
SM:S0 NNLO error = 5%
S0 = 0.162+/-0.008 ~ C7/C9
In SM: ACPFB~ 0
Determination of sign of AFB very important.
cp(Bs l+l-) SM: <0.5% (0.05% for K* l+l)
cp(Bd l+l-) SM: -~(4.4+/-4 )%
B(BsB(Bse+e-) SM: ~1
AFB(K*l+l-):s0(zero crossing) SM predicts with ~5% accuracy
AFB(K*l+l-):CP asymmetry Very small in SM
NP observables in s/d l+l- decay
In dilepton rest frameNF = when l+ along b dirNB = when l+ opposite b dir