BaBar Winter HighlightsJim Olsen

Princeton UniversityBaBar Physics Analysis Coordinator

SLAC Experimental Seminar

April 3, 2007

For the BaBar Collaboration

Data input and physics output

Peak luminosity

(cm-2s-1)1.201 x 1034

Best shift 329.7 pb-1

Best day 891.2 pb-1

Best week 5.25 fb-1

Best month 18.84 fb-1

BABAR logged 414 fb-1

BABAR Belle

Luminosity 413fb-1 710fb-1

Journal Papers

270 206

Publication “Luminosity”

Run 6

BaBar Publications

• Journal Publications– Submitted: 270 (15 in 2007)– Published: 248– About half PRL, half PRD

• Ongoing Analyses– New results for winter: > 30– Targeted for summer: > 100

Electron-Positron Annihilation @ s = 10.58 GeV

nb1))4(( BBSeenb3),,, ;( csduqqqee

ee → Cross-section (nb) Applications

ee(), () > 40 Luminosity, boost, calibration, control samples,…

0.9 Control samples, tau physics: LFV, spectral moments, form factors,…

hadrons + variable ISR physics: QED, QCD, a, quarkonia, new states,…

cc 1.3 Charm physics: production, decay, spectroscopy, D mixing, CPV,…

uu, dd, ss 2.1 Inclusive particle spectra, bkgs,…

Non-B physics accounts for ~25% of all BaBar publications

Bulk of BaBar effort is in B physics:

• CKM elements: Vub, Vcb, Vtd, Vts

• searches for CP, T, and CPT violation

• searches for rare and forbidden decays

• hadronic B decays, HQET,…

Publications by topic*

65

16

56

45

24

12

68

0

25

50

75

Angles Semilep Charmless B to charm Lept/RadPeng Mixing/Lifetime Non-B

*some papers cover multiple areas

BaBar Winter Results at a GlanceBeta • sin2 from (c cbar) K0

• sin2 with D*D and DD

• sin2 with D0(CP) h0 decays

• sin2b in B0 → KSKSK0

• sin2b in B → KS

Alpha • observation of CP violation in B0 → h+h-

• BF and Acp in B →

• Time-dep CP asymmetry in B →

•Time-dep Dalitz in B →

• Evidence for B0 →

• Time-dep CP asymmetry in B0 → a1

• BF(B → K1)

Semileptonic B Decays • Decay rates for B → (D, D*, D**)l

• Vcb and form factors in B → D*l

Gamma • Measurement of in B → D0(K

Radiative Penguins• Evidence for B →

• Search for B → l+l-

Charmless Hadronic B Decays• Observation of B → KS

• Angular analysis in B → K*

• Search for B → K*K

• Search for a0h and f0

Hadronic B Decays• Angular analysis of Charmonium K*

• Measurements of B → J/

• B → p

Non-B Physics• Evidence for D0 mixing

• Search for D0 mixing in semileptonic decays

• Measurement of c branching fractions

• Form factors in D → Ke

• Observation of e+e- →

• Observation of e+e- →

• → l(’

Outline

• D mixing• New results on CP violation• New results on spectroscopy and QCD

See SLAC seminar by Brian Petersen for details: https://www.slac.stanford.edu/exp/seminar/talks/2007/20070314_BrianPetersen_BaBar_Dmixing.pdf

Evidence for D0 Mixing

press release on D mixing

DOW plummets 200 points

Charm-Meson Mixing (SM)short distance ~ x ~ m long distance ~ y ~

O(10-5) O(10-3 - 10-2)

1%Most calculations give:

x,y < 1%

“D0-D0 mixing is expected to be too small to measure with BaBar if the Standard Model

is a complete description of physics.”

- BaBar Physics Book (1998) cf. A. Petrov, hep-ph/0611361, and references therein

Charm-Meson Mixing (NP)

1%

Signs of New Physics:

|x| >> |y|

CP violation

New particles enter primarily in the short distance contribution (x):

Suppression of new FCNCs via quark-squark alignment predicts “large” effects in D-D mixing: Y. Nir and N. Seiberg, hep-ph/9304307 (1993)Y. Nir, hep-ph/0206064 (2002) cf. A. Petrov, hep-ph/0611361, and references therein

Constraining the Squark Mass Matrix

Squark mass matrix (d sector)

LHC

B Factory,Tevatron

Observation of D-D mixing opens a new window on the off-diagonal elements of the squark matrix in the up-quark sector

Analysis of D0 → K

2

22

4t

yxtyRRe

dt

dNDD

t

KDD

KD00

0

Mixing modifies the exponential decay-time distribution:

Two paths to the “wrong-sign” state:

DCS

interference

mixing

sincos

sincos

xyy

yxx

Strong phase → 0 in SU(3) limit

(DCS decays)

(Mixing)

Evidence for MixingWrong-sign decay-time distribution

%31.044.097.0

%021.0030.0022.02

y

x

3.9hep-ex/0703020

Submitted to PRL on March 9

2/ndof = 50/282/ndof = 31/28

Mixing gives a better description of the data

No evidence for CP violation

2

22

4t

yxtyRRe

dt

dNDD

t

First assume no mixing:

Comparison of BaBar and Belle

BaBarpreliminary

Belle Ks

Belle KK,

Full interpretation depends critically on the strong phase: “My call: SU(3) violation” – J. Rosner (Moriond QCD)

Assuming → and no CP violation

CP Violation

CP Violation and the Unitarity Triangle

0*** tbtdcbcdubud VVVVVV

*cbcdVV

*tbtdVV

Length of each side ~ O(3)

*ubudVV

),(

*cbcdVV *

cbcdVV

)0,1()0,0(

CP 0

“The” Unitarity Triangle

Sides are determined from the rates for various processesAngles are determined from CP-violating asymmetries

Area is proportional to the amount of CP violation

Goal of the B Factories is to overconstrain the apex

(,) and look for inconsistencies → New

Physics!

Observing CP violation at the (4S)

CP violation in mixing (|q/p| ≠ 1)0000 BBBB

(indirect) CP violation in the interference between mixing and decay: Im(q/p) ≠ 0

Three possible interference effects:

00

00

BqBpB

BqBpB

H

L

CP if q ≠ p

)cos()sin(

)()(

)()(00

00

tmCtmS

fBfB

fBfBA

CPCP ff

CPCP

CPCPCP

Indirect CPV Direct CPV

(direct) CP violation in decay:

CPCP fBfB 001/ AA

Indirect CP Violation: experimental method

)cos()sin(

)()(

)()(00

00

tmCtmS

fBfB

fBfBA

CPCP ff

CPCP

CPCPCP

t

0tagB

+e-e

0CPB

t = 0

K

e+

0SK

/J

(4S)

Lepton Tags: mistag rate ≈ 8%

Kaon Tags:mistag rate ≈ 18%

fS = sin2

Asy

mm

etr

y 1z

tc

m260 z

m180

~

~σ(Δz)

New results on sin2 in b → ccs

018.0025.0966.0

016.0035.0697.02sin

017.0022.0952.0

018.0032.0714.02sin

f = -1

f = +1

NBB = 383 million pairs

Golden modes (JK0)

BaBar Preliminary (hep-ex/0703021; submitted to PRL)

B Factory Average

0.13.21 0.17.68 Disfavored by J/K*, D*D*KS, D0h0

Latest on sin2 in Penguins

sin2 in b → cud: B0 → D(*)0(CP)h0

Interference between mixing and the b → cud decay tree amplitude when the D0 decays to a CP eigenstate

No penguin amplitude, NP must enter at tree level:

Ex. R-parity-violating SUSY with baryon number violation

Y. Grossman, Y. Worah, Phys. Lett. B 395 (1997) 241-249

Longterm goal: compare sin2 in charmonium, b → s penguin, and b → c tree

sin2 in b → cud: B0 → D(*)0(CP)h0

Decay modes:

• D*0 → D0

• D0 → KK, KS

• h0 →

BaBar Preliminary

BaBar Preliminary

CP even

CP odd

sin2 in b → cud: B0 → D(*)0(CP)h0

40.016.023.0

05.023.056.0

C

S

First measurement of sin2 in these modes

hep-ex/0703019, submitted to Phys. Rev. Lett.

Fully consistent with the world average

for sin2 in charmonium,

another victory for the standard model!

SM expects S = -sin2, C ~ 0

sin2 in b → ccd: B0 → D(*)+D(*)-

B0

D(*)+

D(*)-

B0

D(*)+

D(*)-

• Two decay amplitudes interfere– b → c tree diagram with S = -sin2– b → d penguin diagram with S ~ 0

• Penguin is expected to be small– ~2-10% (PRD 61, 014010, 2001)

Standard Model predicts:

%10~

2sin

C

S

Belle sin2 in b → ccd: B0 → D+D-

Belle @ CKM 2006

(NBB = 535 million pairs) )2.3( 06.023.091.0

09.037.013.1

A

S

B0 B0

BaBar sin2 in b → ccd: B0 → D+D-

BaBar @ Moriond EW

(NBB = 383 million pairs)

70.022.011.0

06.034.054.0

C

S

S consistent with sin2 in charmonium, no evidence for direct CP violation!

Note the sign flip: C = -A, C(BaBar) – C(Belle) = 1.02 ± 0.33!

BaBar Preliminary

@ICHEP06BaBar: 347 MBB

Belle: 535 MBB

CP Violation in B0 → h+h-

How to add data over a shutdown

Use dE/dx for tracks with no c

DCH DRC

+12% from forward coverage

+9% from cracks in barrel

+16% overall in B+ → h+X0

+35% overall in B0 → h+h-

dE/dx /K separation competitive in the forward region high momentum

Observation of CPV in B0 → h+h-

Belle

)5.5( 018.0107.0

)2.2( 02.009.021.0

)2.5( 03.011.060.0

007.0 004.0

KA

C

S

824372

491139

KN

NBaBar Preliminary (hep-ex/0703016; submitted to

PRL)

Now more events/fb-1 than Belle!

BaBar: 383 MBB

Time Evolution of S

2000 2001 2002 2003 2004 2005 2006 2007

The problem with …S sin2eff = sin2( )All modes suffer from “penguin

pollution” due to b → d transition

Use isospin to relate the decay amplitudes for the various modes and set a bound on the shift in

Optimal Case: 000 ,

B → o

hep-ex/0612021; accepted by PRL

B → o

hep-ex/0607106

A New Direction: B → a1

0B

0BFirst observation of B → a1

+

Phys. Rev. Lett. 97, 051802 (2006)

BaBar

hep-ex/0612050; accepted by PRL

First time-dep CP asymmetry in B → a1+

Similar to , but no overlapping regions in phase space where a1

+, a1

-, and a10 can interfere directly

Possible solution: Use SU(3) to relate a1a1K, and K1

BaBar

?,779eff

First Step: B → K1

effeffeff 2

1

SU(3) relates K and a1 K1A:

related to K1 related to a1K

Experimental problem: • K1A is an admixture ( ~ 33o)

)1270(sin)1400(cos 111 KKK A

Wide overlapping resonances

First pass: quasi-two-body approach

Gronau & Zupan, Phys. Rev. D73, 057502 (2006)

Results for B → K1

Evidence for K1(1400), but large correlation with K1(1270) complicates the interpretation• Full analysis, including interference term, is underway

• next step: a1K

BaBar preliminary

sPlot constructed from a fit using mES, E, and event-shape info:

• data points do not use MK

• curves are the result of the full fit

Spectroscopy and QCD

Spectroscopic Mysteries

DsJ(2700)

Open CharmCharmonium-like

New BaBar results using B → D(*)D(*)K

DsJ(2700) @ BelleFirst observed by Belle (hep-ex/0608031)

KDDB 00

Potential model: cs(23S1)(expected mass @ 2720)

M. A. Nowak, M. Rho, I. Zahed, Acta Phys.Polon. B 35, 2377 (2004)

Chiral symmetry: 1+ - 1- doubletpaired with DsJ(2536)

S. Godfrey and N. Isgur, Phys. Rev. D 32, 189 (1985)

DsJ(2700) @ BaBar

KDDB 0(*)0(*)

BaBar confirms a broad enhancement near 2.7 GeV, but is it one resonance or two? Possible low-mass structure in DK.

Next step: full Dalitz analysis

X(3872)

JXKXB )3872(,)3872(

X(3872) first observed by Belle JXKXB )3872(,)3872(

Observation of J/ mode → C = +1

Belle angular analysis → JPC = 1++

Inconsistent with expected charmonium states

Search for X(3872) in D*D

24.07.1 cVM9.0 7.04.3875 eM

PRL 97, 162002(2006)

000*

*

DD

DKDB

KDDB 000 Belle: BaBar:

24.15.1 cVM 7.06.3875 eM

X(3875)?

Observation of ee →

Exclusive reactions allow fundamental tests of QCDSingle photon (JPC = 1--)

e-

e+

For vector gluons:

d/dcos ~ sin2*

Two-Virtual Photon Annihilation (C = +1) followed by FSI → unlikely?

In the CM frame:

u

u

u

u

d

u

d

u

BaBar observation of TVPA process in , → good agreement with theory:B. Aubert et al., Phys. Rev. Lett. 97, 112002 (2006); G. Bodwin et al., Phys. Rev. D74, 074014 (2006)

Observation of ee →

0 m

0 mFit in (m-, m+) plane:

• signal = p-wave relativistic BW

• = threshold function

• comb = linear

N = 308 ± 25 signal events (> 5)e+e- → = (20.0 ± 1.6 ± 3.6 ± 1.7)fb (stat) (syst) (ampl)

Angular Distributions

2

00

2

11

2

10 01.0~ FFF

Use mass fit to produce sPlots for various angular distributions, then perform fit over the sPlot bins

± = ± helicity angle

± = azimuthal angle of in frame

scattering angle in the CM frame

Prediction (single :

Brodsky and Lepage, PRD 24, 2848 (1981)

Angular Distributions: Results

(syst)00.0(stat)03.004.0

(syst)01.0(stat)04.010.0

(syst)02.0(stat)14.051.0

2

11

2

10

2

00

F

F

F

Results:

BaBar PreliminaryFit normalization constraint:

1242

11

2

10

2

00 FFF

|F00|2 ≠ 1

(e+e- → ) > (e+e- → )

No evidence for Y(4S) →

Are we seeing TVPA + FSI?

Summary and Outlook

• BaBar did not hibernate this winter– >30 fresh results for the winter workshops/confs– Highlights

• First evidence for D0 mixing• Many new results on CP violation, including first observation

in from BaBar• New results in spectroscopy and QCD

• We are approaching 300 papers submitted!– Wide range of physics topics, no signs of slowdown

• Looking forward to ~500fb-1 and >100 new results for the summer season!