Physics reach of a Super B-Factory

Riccardo FacciniUniversita’ “La Sapienza” e INFN Roma

CSNI , 4 Febbraio 2003

Motivations PEP-II/BABAR and KEK-B/Belle have provided the first evidence

that the CKM phase is indeed the source of CP violation in B meson (and, by extension) K meson weak decays

Since the matter-antimatter asymmetry of the universe cannot be accounted for by Standard Model CP violation, we had a reasonable expectation that the Standard Model would fail this unique test

The Standard Model passed the test The unitarity triangle construction is self-consistent

It is now time to test the higher orders (loops) and this requires a luminosity of 1036 cm-2s-1

Overconstrain the unitary triangles with much smaller errors Study decay distributions of loop dominated, rare, decays

How high the luminosity?!?

today SuperBFactory (SBF)

New physics and flavor physics

CP violation is an excellent probe of new physics: The CKM mechanism has a single source of CPV and

makes quantitative predictions New sources of flavor and CP violation can induce

large deviations from the Standard Model predictions, many of which are not obscured by hadronic uncertainties

Henceforth in this discussion, I will use the supersymmetric SM :The supersymmetric SM has 124 independent parameters, 44 of which are CP-violating

SBF can probe the CP violating part of Susy and resolve the ambiguities in the new particles zoology

High precision B physics involves reducing the systematic errors It can be achieved at expense of stat error. Fully reconstruct one B and look at the recoil in an

inclusive way 4 M Bs /ab-1 (~0.2%) Advantages:

All the remaining tracks come from the other B possibility to apply partial reconstruction (e.g.

BD* (D0)sin a clean way

Heavily used in sys error reduction in the following

Physics with single B-beams

?

Recoil physics is cleaner

Inclusive lepton analysis

Single-B beams

Vub

Vcb

BXl

Precision Measurement of the sides of the Unitary Triangle

CKM Analysis stat

(2007)%

stat

(2011)%

sys

(2011)%

th

(>2010) %

Vcb D(*,**)l 0.4 0.1 1 1-2

b cl 1 0.5 0.5 5

Vub bul 3 0.7 2.5 5

B Xul 9 2 2.5 1-2

Vtd Md* 0.2 0.05 0.5 5

Vub,Vtd B 5% on Vub?

Md/Ms would be more interesting but not doable by Y(4S) SBF

r r r

Precise measurement of the angles: impact of SUSY

MSSM phase

SM phase

Ratio of amplitudes in SM

Ratio of MSSM/SM amplitudes

Precision Measurement of the angles :

0.001

0.01

0.1

1

10 100 1000 10000 100000

I nt egr ated lum inosi ty ( /f b)

0/ SJ Ky

rppp

0 /J y p0SKf

* *D D+ -

0/ SJ Ky

rppp

* *D D+ -

0/J y p0SKf

Sys err

Sys err lepton tags

(stat err. ~70% larger)

Only J/Ks will be syst. Limited, but one can use only the cleaner tags to reduce the error. All comparisons still stat. Limited.

Precision Measurement of the angles :

2

’

(sin2eff) ~ .03 in 10 ab-1with 2eff = 2

Current precision on ACP(B0+-) yields Isolating penguin pollution requires measurement of tagged and decay branching fractions, which can only be done at a B Factory

0 0 0B 0 0 0B

L = 10 ab-1

(rad)(rad)

L = 2 ab-1

… but there is a 4-fold ambiguity! (revert triangle and )

)1.0(

)(

)(

0

0

O

KDBA

KDBAr

2ab-1, actual detectorr sin2

0.3

0.2

0.1 unreliable unreliable

• Crucially depends on r (breaks down for r < 0.1?)

• 8-fold ambiguity spoils the extraction of

• But ACP = 2r sin sin is accessible: (ACP) ~ 0.03 with 2 ab-1

= f --++ (, , r)

)()(

0

++

KDB KDB

)()(

0

--

KDB KDB

)()(

0

--

KDB KDB

)()(

0

++

KDB KDB

= f ----

= f ++--

= f ++++

Measure:

2 A (B- D0+ K

-) = A (B- D0 K-) + A (B- D0 K-)

Precision Measurement of angles :

Precision Measurement of the angles :

Interference between Vcb and Vub diagrams in bcud transitions exploited to measure sin2

The biggest limitation comes from the knowledge of the amplitude of oscillations (~0.02). Theoretical uncertainty ~30%

Initial idea involved only B0D(*), now extended to B0D(*),a1,Ks This reduces th. Error Expected asymptotic error

~0.05b

c

W d

u

d dD

bu

W

cD(d

d d

Expected Errors 1 year of SBF

(sin2)~0.008

(sin2eff)~0.032 (BR(00))~6%

((DK))~2o

(sin())~0.05

Rare decays and New Physics:

bs single-B beams reduce the model dependence and allow time dependent measurements. B.F., CP asymmetries sensitive to NP.

Bdirect CP asymmetry and Br()/Br(K*) sensitive to MSSM

BXsll CP asymmetry small in SM and large in MSSM

Bll BF are very small, but could become non negligible with NP contributions

Blrelative ratio of the channels (l= vs l=)

CPV in exclusive radiative decays

Probe SUSY in K*ll

M2ll (GeV2)

Comparison on rare decays

Super-BF: design considerations

Change boost to optimize cost/physics Smaller lifetimes continuous injection More and shorter bunches

X-ing angle ~ 1.5 mrad (impact on backgrounds) Redesign HER lattice

Focussing Magnets closer to I.P. to get smaller functions Vacuum system will have to dissipate 16 KW/m of syncrotron

radiation RF system, same as B-Factory but scaled up 1 O.o.M. Cost of power, 100 times higher than now Planned workshops:

– February 2003: SBF Workshop– October 14-17, 2003 SLAC: ICFA Workshop on e+e- Factories

Super B-Factory % B-Factory

Beam e+ e- e- e+

E(GeV) 8.0 3.5 9.0 3.1

#bunches 7000 800

lifetime (min) 7 5 200

Current (A) 10.3 23.5 1.0 1.8

*(mm) x=15/y=1.5 x=450/y=10

Emittance(nm)

x= 44/y=0.44 40/2.5

Beam spot (m)

x= 81/y=0.8 x= 147/y=5

Tune shift 0.10 0.07

Boost optimization

0 high lepton tagB pp p+ -®

Nor

mal

ized

lum

inos

ity

degr

adat

ion

fact

or

Lifetime details Luminosity: interacting particles get

lost Vacuum: beam-gas scattering Touschek: intra-beam scattering Beam-beam: optimize tune shifts Dynamic aperture: due to beta

functions

Injection details

Interaction region

PEP-II 1036 B-Factory +/- 12 mrad xing angle Q2 septum at 2.5 m

30

20

10

0

-10

-20

-30

cm

-7.5 -5 -2.5 0 2.5 5 7.5m 31-JAN-2002

M. Sullivan

Q1

Q1Q1

Q1

Q2

Q4

Q5Q2

Q4Q5 e+

e-

With increasing luminosity beam beam interactions increase wrt syncrotron radiation/vacuum loss extrapolations from PEP very rough

X-ing angle

Close Q1

Super BaBar: detector issues

Background considerations will drive detector design. The vacuum/luminosity background should be ~600 larger than PEP, but other sources should take place. Radiation resistant and fast smaller Smaller detector higher magnetic field

Crucial point is the calorimeter (sensitivity to background & reconstruction).

Trigger rates: LV1 ~ 100KHz ; 5GB/s LV2 ~ 6Khz; 300 MB/s

Computing ~50 times more challenging than BaBar Will have to wait for better machine design before

being able to make detector strawman

Calorimeter design choises

A potential upgrade path from BABAR to SuperBABAR

DIRC

IFR with same design

New EMC –Liquid Xe, YAP,

LSO?

New tracker –Two inner pixelLayers

Thin double-sided Si-strip arch layers

New DIRC(s) with compact readout

Summary Physics case for SuperBaBar : precise

measurements in the flavor sectors: Sensitivity to new physics :

Probe CP violation parameters of new physics Resolve ambiguities in NP zoology

Reduce systematics (e+e- machines more suited: single beam approach)

Select high number of events in penguin dominated processes Workshop at SLAC 20-22 March 2003

Design of SuperBFactory First set of parameters released in May Workshop in February 2003

Design of SuperBaBar Waiting for physics case and B factory Working group within BaBar will report by fall 2003