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!