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The BaBar experiment

Flavor Physics at the B Factories

Present status

Future perspectives

L.Lanceri - INFN Seminar

July 7, 2009

July 7, 2009 L.Lanceri - INFN Seminar 2

Flavour physics, a discovery tool

Some past (Standard Model) successes:

Beyond SM with flavour physics?

1970: charm from K0 μ+μ (GIM)

1973: 3rd quark family from K (Kobayashi & Maskawa)

Early 90’s: heavy top from mB

2001: CP in B decays (BaBar & Belle)

2008: Nobel (Kobayashi & Maskawa)

Indirect searches: virtual effects, “loop” corrections

Large “New Physics” effects expected

(SM weak interactions CP, FCNC: in loops)


Electrons: E = 9.1 GeV, I = 2.0 A

Positrons: E = 3.0 GeV, I = 3.2 A

Peak luminosity:L = 12 1033 cm-2s-1 =

= 12 events nb-1s-1

Asymmetric-energy e+e- colliderECM = 10.26 GeV

e+e 4S( ) BB ( ) 1nb =10 33cm2


BaBar @ PEP-II, Belle @ KEK-B


DIRC (PID)

144 quartz bars

11000 PMs

1.5T solenoid

EMC

6580 CsI(Tl) crystals

Drift Chamber

24 stereo layers

16 axial layers

Instrumented Flux Return

iron / RPCs (muon / neutral hadrons)Silicon Vertex Tracker

5 layers, double sided strips

e+ (3.1GeV)

e- (9GeV)

BaBar Detector

Inner layer:

10μm resolution

Fish-eye view of “typical” event:( )


DIRC (PID)

144 quartz bars

11000 PMs

1.5T solenoid

EMC

6580 CsI(Tl) crystals

Drift Chamber

24 stereo layers

16 axial layers

Instrumented Flux Return

iron / RPCs (muon / neutral hadrons)Silicon Vertex Tracker

5 layers, double sided strips

e+ (3.1GeV)

e- (9GeV)

BaBar Detector

Inner layer:

10μm resolution

Fish-eye view of “typical” event:( )

Many topics in CP and flavor physics

B decays, CP asymmetries ACP

B decay rates & branching fractions

Charm decays, D0-D0 mixing

lepton decays

Spectroscopy of bound quark states, QCD

2001-2009: > 400 papers


Standard Model: CP 3 ”Flavors”

+W

ijgV

tcuqi

,,=

bsdq j ,,=

=

tbtstd

cbcscd

ubusud

VVV

VVV

VVV

V

+W

ub

W

b u

ubV

ubV

CP

“mirror”

a phase in the “CKM” matrix Vij violates CP !


CKM matrix: Unitarity Triangle

u

c

t

d s b 3 quark “families”

Mixing:3 3 unitary matrix

4 parameters

(1 complex phase)



u

c

t

d s b

=tdub

VV argarg



Just 4 parameters…

… predict

many observables

Observables:

Branching Fractions

and B-B Mixing ( “sides”)

example:

semi-leptonic decay rates

for B mesons

BF Bd0 D l+( ) Vcb

2

BF Bd0 l+( ) Vub

2

W +

b c Vcb

d d

l+




… predict

many observables

Observables:

Branching Fractions

and B-B Mixing ( “sides”)

example:

semi-leptonic decay rates

for B mesons

BF Bd0 D l+( ) Vcb

2

BF Bd0 l+( ) Vub

2

W +

b c Vcb

d d

l+




… predict

many observables

Observables:

CP Asymmetries( “angles” = phases)

interference needed ! Ex.:

“double slit” experiments

W +b c

Vcb

d d

cs

Wb d

Vtd

d b

JB0

W

t

tB0 B 0

K 0




… predict

many observables

Observables:

CP Asymmetries( “angles” = phases)

interference needed ! Ex.:

“double slit” experiments

W +b c

Vcb

d d

cs

Wb d

Vtd

d b

JB0

W

t

tB0 B 0

K 0

: KS , …

: , ,

: D( )K( ) , …


Unitarity Triangle: today

Statistically compatible with

the Standard Model (SM)

Cosmology, dark matter, etc.:

“new” physics beyond the SM !

Any hint in the data?

“Waiting for Godot”…a few 2 effects:

BF( ) vs. sin2 cc

ACP( K+ , K± 0)

(sin2 : KS vs. KS)

sin2 s from s (CDF)… Godot did not come yet!


Another example: charm mixingWilkinson, FPCP 2009:


BaBar-Trieste 1995-2009

Contributions from:

Marco Bomben, Cristiano Borean, Luciano Bosisio, Tina Cartaro,

Giuliano Castelli, Fabio Cossutti, Giuseppe Della Ricca, Selenia Dittongo,

Benigno Gobbo, Sergio Grancagnolo, Livio Lanceri, Alexis Pompili,

Paolo Poropat, Michela Prest, Cristiano Rastelli, Irina Rashevskaya,

Davide Scarabino, Erik Vallazza, Lorenzo Vitale, Gloria Vuagnin

(Theory advice: Nello Paver, Guido Michelon)

SVT

BF (B D l ), |Vcb|

sin2 : ACP (B D +D )

BF (B )

D mixing (D K )

sin2 : ACP (B DCP( )0h0)

detector physics


Flavour physics: what next?

2010 - 2015: Tevatron LHC (LHCb, …)

sin2 s from s , down to SM value

BF ( s μ+μ ), down to SM value

UT angle down to 2-3o

… etc.

2015 - 2020: e+e “super flavour-factories” ?

physics case: “New Physics” reach

accelerator: lumi. 1036 cm-2 s-1

75 ab-1 in 5 yr, polarization

detector upgrades


Physics case in one slide

• New Physics (NP) expected beyond SM

– Scale ? 0.5, 1, 10, … 1016 TeV ?

– Quantum stabilization of EW scale suggests 1TeV

• Two scenarios

– LHC finds NP: SuperB measures couplings, flavour structure,

+ searches heavier states indirectly

– NP above LHC reach: SuperB looks for indirect signals, up to10 TeV or more

• Complementary to LHC

– Test CP, CPT and Lepton Flavour Violation (LFV) in decays

– Many rare B decays only accessible to SuperB

– Sensitive to off-diagonal terms in squark mixing matrix

– Search for CP and CPT violation in D decays


Backbone: CKM at 1%M.Ciuchini

Standard ModelStandard Model


Lepton Flavour Violation


Lepton Flavour Violation

superB

sensitivity

in 75 ab-1

an example:

Minimal Flavour Violation (MFV)

extensions of the SM


SUSY? MSSM parameters

the Brave New World


SUSY? squark mixing matrix


squark couplings: an example

M.Ciuchini


Just two rare B decays examples

B K μ+μ

B (μ)


B physics @ U(4S)

Possible also at LHCb

Similar precision at LHCb

As in CDR, some number updated on Valencia


physics

Bs at U(5S)

Charm at U(4S) and threshold

To be evaluated

at LHCb

Bs : not discussed today. Maybe to be

Revisited for next Workshops


“Golden” channels ?

The GOLDEN channel for the given scenario

Not the GOLDEN channel for the given scenario

but can show experimentally measurable deviations

from SM.

Where –CKM means that Lattice improvement are crucial

X

O

work ongoing

to extend and refine

this table

for the TDR


Complementarity with LHCb


SuperB: concepts

Design principles

Lumi 100 !?!


SuperB new features

“crab waist”

Sextupoles

on


SuperB parameters


Alternative LNF site


Detector: partially BaBar


SuperB collaboration: TDR


Luminosity Prospect

3636

Integrated Luminosity(1/ab)

0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

Year 0

Year 1

Year 2

Year 3

Year 4

Year 5

Year 6

Year 7

Year 8

L~2x1035

L~8x1035

50ab-1 by ~2020

10ab-1 ~ 2016

“brute force” “nano-beam”


Super

Flavour

Factory


The European Strategy for particle physics…

Scientific activities

…

8. Flavour physics and precision measurements at the high-luminosity

frontier at lower energies complement our understanding of particle

physics and allow for a more accurate interpretation of the results at

the high-energy frontier; these should be led by national or regional

collaborations, and the participation of European laboratories and

institutes should be promoted.

Back-up slides


Matter-Antimatter

asymmetry

Coming from a tiny

asymmetry of order 10-9:

1,000,000,001q +

1,000,000,000 q

1q + radiation

Origin ??

B

nB nB

n=

nB

n=

= 6.1± 0.3( ) 10 10

Now:

Baryons

photons

No antimatter now!


Matter-Antimatter

asymmetry

t 10-34 sec:

“baryogenesis”

Baryon number (B) violation

C and CP violation

Departure from thermal equilibrium

Several possible

mechanisms

All require the violation of the

CP symmetry

C = charge conjugation

P = parity


Example of “double-slit” experiment

e i2

B0 fCP

Af

AfB0

Flavor-tagged time-dependent decay rates expected to be different!

Asymmetries proportional to CKM phase differences through S

Interference between mixing and decay to a CP eigenstate CPf

B0 fCP

B0

Af

Afei2

CP“mirror”

B0 tag

B0 tag

t( ) e t 1+ CPS sin m t( )[ ]

t( ) e t 1 CPS sin m t( )[ ]

t/Challenges:

Rare decays: BF 10 4÷10 6

Flavor tagging by “other B”Time resolution: 1 ps


e

( )4S+

e

Coherent BB

production

(p-wave)

B0

B0

tagB

0recB

0

B-Flavor

tagging0.3Q

μ

K

Reconstruction of Bdecays to exclusive

final states

μμ+

+KS0

J

(4 )/S

z c t

z

An example of CP Asymmetry MeasurementB-flavor tagging efficiency and t resolution function are obtained from data(measurement of mixing, with exclusively reconstructed self-tagging flavorstates)


CP violation observed!383 106 4S( ) BB events

12677 events with b cc s (7 modes)

75% purity

S = sin2 = 0.714 ± 0.032 ± 0.018

B and B behave differently!

beautiful interference pattern observed,

as predicted by the Standard Model

383 106 4S( ) BB events

340 ± 32 B DCP0(*)h0 events

S = 0.56 ± 0.23± 0.05

“new physics”? (i.e. SUSY models)

should appear in rare suppressed decays

Example:


Integrated luminosity

(4S):

466,000,000 BB

recorded

Y(3S): 30.2 fb-1 Y(2S): 14.5 fb-1

above Y(4S): ~5 fb-1


SpectroscopySpectroscopy

M(M

eV)

JPC

(2S+1)LJ

Open charm thr. (3770)

(4040)

(4160)

(pot. Models)c

’c

J/

’c2

c1

c0

hc

X Z

X,YX(3872) the

best

tetraquark

candidate

Updated properties

(4415)

The 1-- family:

Charmonia,

tetraquarks,

molecules,

hybrids?!?

News on the

3940 family

+ updates on

Y(nS) Y(mS)

transitions

Yet

another

particle:

X(4160)[ c(3S)?]

Z(4430): the first

charged state


The observation matrixThe observation matrix

J/J/ ++ DD(*)(*)DD(*)(*) J/J/ J/J/ ++ 00 (2S)(2S) J/J/ K,K, (2(2SS)) J/J/ ,, J/J/

NotesNotes MassMass

rangerange

for Bfor B

LowLow

statstatOnlyOnly

B decB decMassMass

range!range!

No ISRNo ISR

No ISRNo ISR

No No 00

NoNo

SearchSearchNo B-No B-

decdecOnly BOnly B

decdecMassMass

windowindo

ww

X(3872)X(3872) SeenSeen SeenSeen NotNot

seenseenNot seenNot seen Not seenNot seen NoNo

searchsearchN/AN/A NotNot

seenseenSeenSeen

Y(3940)Y(3940) NoNo

searchsearchX(3940)X(3940)

??SeenSeen No searchNo search Not seenNot seen NoNo

searchsearchNoNo

searchsearchNo FitNo Fit No fitNo fit

Y(4260)Y(4260) SeenSeen No fitNo fit No fitNo fit No searchNo search NoNo

searchsearchNoNo

searchsearchNot seenNot seen No fitNo fit N/AN/A

Y(4350)Y(4350) NotNot

seenseenNo fitNo fit No fitNo fit No searchNo search NoNo

searchsearchNoNo

searchsearchSeenSeen No fitNo fit N/AN/A

Z(4430)Z(4430) NoNo

searchsearchNoNo

searchsearchNo fitNo fit No searchNo search SeenSeen NoNo

searchsearchNoNo

searchsearchNo FitNo Fit NoNo

searcsearc

hh

Y(4660)Y(4660) NotNot

seenseenNo fitNo fit No fitNo fit No searchNo search NoNo

searchsearchNoNo

searchsearchSeenSeen No FitNo Fit N/AN/A


Flavor factories in the future?

Physics: 100 increase in luminosity would give access to quantum

effects (loops) of new particles and couplings in the TeV range, with

information complementary to LHC

Accelerator: very challenging!

INFN is evaluating a “SuperB”

Project for a “regional” lab with

an asymmetric 1036 “flavor factory”

Lepton Flavor Violation


Mini-MAC requirements

Parameter Requirement Comment

Luminosity (top-

up mode)

1036 cm-2s-1 @ (4S)

Integrated

luminosity

75 ab-1 Based on a “New Snowmass

Year” of 1.5 x 107 seconds

(PEP-II experience-based)

CM energy range From just below charm threshold to (5S)

For a better study of CP violation

in Charm and for BS

measurements.

Minimum boost = 0.28 (4x7 GeV) 1 cm beampipe radius. First

measurement at 1.5 cm

e- Polarization 60-85% Enables CP and T violation

studies, measurement of g-2

and improves sensitivity to

lepton flavor-violating decays.

Detailed simulation, needed to

ascertain a more precise

requirement, are in progress.


2007 2008 2009 2010 2011 2012

KEKB

ILC R&D

Photon Factory& upgradeoperation

LHC

J-PARC

ERL R&D


Physics Case

..en pillule…

SuperB+Lattice improvements

tan

tan

SuperB

MH~1.2-2.5 TeVfor tan ~30-60

23| |LR

1 10

1

10-1

10-2

(TeV)gluinom

In the red regions the

are measured with a

significance >3 away

from zero

23| |LR

Arg( 23)LR=(44.5± 2.6)o

= (0.026 ± 0.005)

1 TeV

10

7 BR

(μ)

M1/2

SuperB

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