To SuperB or not to SuperB ? Francesco Forti INFN-Pisa IFAE, Torino, 14-16 Aprile 2004 Babar TM and © Nelvana.

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.


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


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


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.


Neubert


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 ?


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%


Theoretical uncertainties


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%


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%


CP Violation in bs penguins

Rare Decays – New Physics – CPV e+e- Precision 1 Year Precision


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


More Rare decays precision

Rare Decays – New Physics e+e- Precision 1 Year Precision


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 - -


bsl+l- precision

New Physics – Kl+l-, sl+l- e+e- Precision 1 YearPrecision


(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%


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


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


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


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

--- Detailed slides on physics processes ---


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


Bt+nut


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


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


Error on angles

0.5 ab-1

5 ab-1

50 ab-1


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


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


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


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


BD

• Sensitive to NP


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


Universal extra dimension effects


--- END ---

To SuperB or not to SuperB ? Francesco Forti INFN-Pisa IFAE, Torino, 14-16 Aprile 2004 Babar TM and © Nelvana.

Documents

b experiments

b experts

b physicsin

b xctnt f

inclusive b sl

scale of np

super bfactories

superb measurements