Recent CP violation results from BaBar

Recent CP violation results from BaBar

F. Martínez-VidalIFIC – Universitat de València-CSIC

Representing the BaBar Collaboration at

Supersymmetry 2011 (SUSY 2011)

FNAL, Batavia, Illinois (USA) 28th August to 2nd September 2011

CP violation

1Recent CP violation results from BaBarSUSY 2011, FNAL F. Martínez-Vidal, IFIC-Valencia

PRD 84, 033005 (2011)

CKM unitarity triangle Leading source of quark-sector CP violation

established (mostly by BaBar and Belle)o CKM mechanism

Overall good consistency between measurements and predictions within CKM o ~2.8s tension for sin2bB(cc)K and BF(B+t+n)

New physics (NP) can be revealed in low-energy flavor processes…especially in loops

Particularly fruitful are processes with (very) small effects predicted by the SM

NP in general induces (additional) FCNC and CP-violating phases

The particle can be very heavy…can probe NP at the multi-TeV scale, but need huge data sets…Luminosity frontier

Complementary to direct searches at energy frontier

The BaBar detector & data set CP violation in D decays

o D+ p+K0s

o D+(s)K+K0

sp+p- and D0K+K-p+p-

CP violation in t decayso t- p-K0

snt CP violation in Charmless B decays

o B+ (r0/f0)K*+ and B0 r-K*+ o B0 K+p-p0 and B+ K+p0p0

Conclusions

Outline


DIRC (PID)144 quartz bars

11000 PMs

1.5T solenoid EMC6580 CsI(Tl) crystals

Drift Chamber40 stereo layers

Instrumented Flux Returniron / RPCs / LSTs (muon / neutral hadrons)

Silicon Vertex Tracker5 layers, double sided strips

e+ (3.1 GeV)

e- (8-9 GeV)

BaBar detector

Asymmetric B-factory: Ecms = 10.58 GeV Performed a wide range of flavor physics results in B, Cham and t sectors General purpose detector in e+e- environment: precision tracking, photon/electron detection, particle

ID, muon/KL identification. Very stable over the 9 years of operation 3 3Recent CP violation results from BaBarSUSY 2011, FNAL F. Martínez-Vidal, IFIC-Valencia

B factoriesData set

≈ 470106 BB (0.5Belle)≈ 690106 cc≈ 500106 tt- ≈ 1.2108 (3S) (7Belle+Cleo)≈ 1.0108 (2S) (0.5Belle+Cleo)

530 fb-1 recorded in the 9 years of operation

430 fb-1 30.2 fb-1

14.5 fb-1

54 fb-1 Off-(nS) 4 fb-1 above (4S)


Recent CP violation results: D decays


Direct CP violation in D decays arises through interference between:

In the SM is CKM suppressed O(10-3) or less

NP can increase or reduce the effecto e.g. additional CP phase from charged Higgs bosono SCS decays are more likely to show the effect if present

Current experimental sensitivity O(10-3)

D decays: motivation

~ 0.23, ~ 0.8, ~ 0.2, ~ 0.4A r

1 12 3 22 2

1 2 2 4 2 22

3 2

1 ( )1 (1 )

(1 ) 1

ud us ub

cd cs cb

td ts tb

V V V A i iV V V i A A i

A i AV V V

r

r

- - - - -

- - -

PRD 75, 036008 (2007)

PRD 51, 003478 (1995)hep-ph/0104008 (2001)

Tree d , s

csud (CF) and cdus (DCS)c s , d

uW+

Vcs

Penguin

cudd (SCS) and cuss (SCS)W+c u

d , s

g d , s

sVcs


Due to CPV in mixing in the kaon sector, the direct CP asymmetry

is expected to be Signal yields from likelihood fit to m(p+K0

s), with selection based on a Boosted Decision Tree with 7 variables:

807K D± signal events Measure

0 0

0 0

( ) ( )( ) ( )

s s

sC

sP

D K D KD K D K

A p pp p

- -

- -

-

2 2| | | | ( 0.332 0.006)%SMCPA p q - -

D DC FB

DP

D

N NA A A

N NA

-

-

-

D+p+K0s: experimental technique

Forward-Backward asymmetry

Detector charge asymmetry

Data-driven method to correct for A o Use tracks from e+e-(4S)BB

decays (isotropic in rest frame) to map the ratio of p+/p- detection efficiencies

o Offset on ACP +0.05%


hep-ph/0104008 (2001)

D+p+K0s: results

Use data-driven method to extract AFB, and ACP in bins of polar angle

470 fb-1

( 0.44 0.13 0.10)%CPA -

Consistent with SM prediction (-0.332±0.006)%PRD 83, 071103(R) (2011)


Measure a T-odd observableo If we assume CPT invariance CP violation

Define T-odd triple products for D+(s) and D-

(s)

Define the T-odd asymmetries

FSI could introduce fake T-odd asymmetries.To remove, define

Signal selection optimized by means of likelihood ratio with 3 variables

Yields obtained from simultaneous likelihood fit to m(K+Ksp+p-) distributions for D+, D-, Ds

+, Ds-, for >0 and < 0 triple products (8 samples in total)

( T KC p p pp p -

D+(s)K+K0

sp+p- : experimental technique

( 0) ( 0)( 0) ( 0)

T TT

T T

C CAC C

- -

( 0) ( 0)( 0) ( 0)

T TT

T T

C CAC C

- - - - - -

1 ( )2 TT TA A -A

PRD 66, 094004 (2002)

PLB 538, 309 (2002)PRD 64, 116003 (2001)

Int.J.M.Phys. A24, 657 (2009)

T-violating asymmetry

( T KC p p pp p- -


D+(s)K+K0

sp+p-: results ~21K D± and 30K Ds

± signal events Results

Similar BaBar analysis using D0K+K-p+p-

o ~47K D0/D0 signal events0 3( ) ( 1.0 5.1 4.4) 10T D - APRD 81, 111103(R) (2010)

520 fb-1

0 3

0 3

( ) ( 68.5 7.3 5.8) 10

( ) ( 70.5 7.3 3.9) 10

T

T

A D

A D

-

-

-

-

3

3

( ) ( 11.2 14.1 5.7) 10

( ) ( 35.1 14.3 7.2) 10T

T

A D

A D

-

- -

3

3

( ) ( 99.2 10.7 8.3) 10

( ) ( 72.1 10.9 10.7) 10T s

T s

A D

A D

-

- -

-

-

3( ) ( 12.0 10.0 4.6) 10T D - - A 3( ) ( 13.6 7.7 3.4) 10T sD - - A

1107.1232 [hep-ph] (2011)

T-violating asymmetry consistent with 0 10 improvement wrt previous result

FSI seem to be larger in D+s than D+ decays

1105.4410 [hep-ex] (2011). Accepted by PRD(RC)


Recent CP violation results: t decays


SM model predicts the decay amplitude and its CP conjugate to be

the same no direct CP V is expected However, like in D+p-Ks, due to CPV in the

kaon sector, the CP asymmetry

is expected to be

A deviation of the measured AQ from AQSM would be a hint of NP

o e.g. an additional CP violating phase from an exotic charged Higgs boson

Can consider o p0s are expected not to change the asymmetry

t- p-K0snt: motivation

0K tt p n- -

0 0

0 0

( ) ( )( ) ( )

s sCP

s s

K KAK K

t t

t t

t p n t p nt p n t p n

- -

- -

-

2 2| | | | (0.332 0.006)%SMCPA p q - PLB 625, 47 (2005)

PLB 398, 407 (1997)0 0( 0 )sK tt p p n- -

Tree

t- nt

uW-

d

s d

p-

K0


Note: the sign of the asymmetry is opposite to that of D+p+K0s

Reconstruct up to 3p0s

Electron and muon tagso pl

* > 4 GeV to reduce background from non-t-pairs

Reconstructed hadronic mass < 1.8 GeVo Rejects qq background

t- p-K0snt: experimental technique

0 0( 0 )sK tt p p n- -

Invariant mass of the hadronic final state (0p0s)

e+ or m+

Remaining qq and K0s

background further reduced using likelihood ratio techniqueo Visible energy, number of

neutral clusters, thrust, total transverse momentum

o Displaced vertex, invariant mass, momentum and polar angle of the K0

s candidate

Selected event topology


Preliminary

Measured raw ACP value (after subtraction of qq background and non-K0s t

decays) has to be corrected byo Different nuclear reaction cross-section of K0 and K0 with material detector

o (0.14±0.03)% for e-tag, (0.14±0.02)% for m-tago Errors include uncertainties from kaon-nucleon cross-sections and isospin

o Dilution from background modes including K0s

Result

t- p-K0snt: results

437x106 t+t- pairs

( 0.45 0.24 0.11)%CPA -

3s from the SM prediction Preliminary. To be submitted to PRD(RC)

Source Fraction e-tag (%) Fraction m-tag (%) SM expected ACP

t-p-K0S(0p0)nt 78.4 ± 4.0 77.4 ± 4.0 (0.33±0.01)%

t-K-K0S(0p0)nt 4.2 ± 0.3 4.0 ± 0.3 (-0.33±0.01)%

t-p-K0K0(0p0)nt15.6 ± 3.7 15.7 ± 3.7 0

Systematic uncertainties


Recent CP violation results: Charmless B decays


Many such decays are dominated by bs penguinso Tree amplitudes subdominant in SMo Time-dependence and FSI (intermediate states)

allow to measure the CKM angles NP can change CP asymmetries, branching fractions

and polarizations in BVV decays

Use kinematic constraints from beam energies

Event shape variables combined into a linear (Fisher) or non linear (NN) combination. Tagging (other “B”) information often used

Charmless B decays


( 2*2/ 2ES Bsm p -

* / 2B sE E -

Tree

Penguin

o Apply selection to reject continuumo As variable in ML fit

B+r0K*+ and B+f0K*+

B+r0K*+ is a VV decay. QCDF o Predicts longitudinal polarization fL~0.9o Works for Brr, not for other VV decays

where fL~0.5 (“polarization puzzle”)

Reconstruct r0/f0p+p- , K*+ Ksp+,K+p0

ML fit with 7 variables: mES, E, NN, invariant masses, cosq

Measure simultaneously BFs, ACPs, fLso First observation of B+r0K*+ with 5.3so Consistent with QCDF, BF (5±1)10-6

fL compatible with other bs decays


Decay Nsignal BF(10-6) ACP fL

B+r0K*+ 85±24 (Ksp+)67±31 (K+p0)

4.6±1.0±0.4 0.31±0.13±0.03 0.78±0.12±0.03

B+f0(pp-)K*+ 69±14 (Ksp+)91±20 (K+p0)

4.2±0.6±0.3 -0.15±0.12±0.03 …

ρ0K*+ signal

f0K*+ signal

467x106 BB pairs

PRD 79, 039903 (2009)NPB 774, 64 (2007)

PRD 83, 051101 (2011)

B0r0/f0K*0 and B0r-K*+

Very similar to previous analysis f2(1270)K*0 events extrapolated from mpp sideband First 5s observations of B0r-K*+ and B0f0K*0

o BF consistent with QCDF, BF 510-6 o fL inconsistent with QCDF, but consistent with experimental

results from other bs decaysExperiment:QCDF:


471x106 BB pairs

* 0 *0 *0 0 *( ) ( ) ( ) ( )L L L Lf K f K f K f Kr r r r- 0 *0 *0 * 0 *( ) ( ) ( ) ( )L L L Lf K f K f K f Kr r r r -

Decay Nsignal BF(10-6) ACP fL

B0r0K*0 365±37 5.1±0.6+0.6-0.8 -0.06±0.09±0.02 0.40±0.08±0.11

B0r-K*+ 167±27 10.3±2.3±1.3 0.21±0.15±0.02 0.38±0.13±0.03

B0f0K*0 220±23 5.7±0.6±0.3 0.07±0.10±0.02 …

Also measure scalar (Kp)*0 and tensor K*

2(1430) states in a (Kp) “high-mass” region (not shown here)

Preliminary

B0K+p-p0 and B+K+p0p0

We expect ACP(B0K+p-) ACP(B+K+p0)

Experimentallyo ACP(B+K+p0) = 0.050 ± 0.025o ACP(B0K+p-) = -0.098 ± 0.012

Is there a similar K*p puzzle? Have to measure B0K*+p- and B+K*+p0

o P/T predicted to be 2-3 larger than in Kp Many resonances interfere

full amplitude (Dalitz plot) analysis Large backgrounds

o qq + many different BB categories + large amount of signal misreconstructed (especially for K+p0p0), all accounted for 19Recent CP violation results from BaBarSUSY 2011, FNAL F. Martínez-Vidal, IFIC-Valencia

5s difference SM or NP? “Kp puzzle”

Mod.Phys.Lett.A 24, 1983 (2009)

B0K+p-p0 and B+K+p0p0: results Perform ML fit with mES and NN, and for K+p-p0 only, also E and DP For B0K+p-p0

o BF(B0K+p-p0) = (38.5 ± 1.0 ± 3.9)10-6

o ACP(K*+p-) = -0.29 ± 0.11 ± 0.02o When combined with B0Kspp- :

For B+K+p0p0

o First inclusive measurement

o Measure resonances in a two-body fashion

More statistics is needed to better test ACP(K*+p-) ACP(K*+p0) 20Recent CP violation results from BaBarSUSY 2011, FNAL F. Martínez-Vidal, IFIC-Valencia

Preliminary

Decay Nsignal BF(10-6) ACP

B+K+p0p0 7427±518 16.2±1.2±1.5 -0.06±0.06±0.04B+K*+p0 1078±197 8.2±1.5±1.1 -0.06±0.24±0.04B+f0(p0p0)K+ 1186±241 2.8±0.6±0.5 0.18±0.18±0.04

B+cc0K+ 245±105 182±78±32±8 -0.96±0.37±0.04

PRD 83, 112010 (2011) 454x106 BB pairs

471x106 BB pairs

3.1s evidence for direct CPVACP(K*+p-) = -0.24 ± 0.07 ± 0.02

10s significanceTo be compared to -0.24 ± 0.07 ± 0.02

ended data-taking in 2008 but continues to produce many new physics results on CP violation in D, t and B decays

Only the most recent new results shown in this talk

Most results agree with SM predictions but some puzzles remaino Charmless BVV “polarization” puzzle o “Kp” puzzle

…and a 3s effect has just appearedo Direct CP violation in t- p-K0

snt

A larger data sample is required to perform stringent tests and searches We look forward for many interesting flavor results from present and future

flavor facilities

Conclusions


Bonus slides


BffK

PLB 583, 285 (2004)


o Interference at mff ~mc

o SM tree and penguin have the same weak phase

o NP in the penguin could induce large direct CPV

Bc(ff)K (Tree) BffK (Penguin)

ML fit in mES, E, Fisher (and 2 f masses for BF) Use (mf1,mf2) sidebands to extract peaking backgrounds from BfKKK, 5K,

f0fK, f0KKK decays

Decay Nsignal BF(10-6) ACP

B+ffK+ 178±15 5.6±0.5±0.3 0.10±0.08±0.02-0.09±0.10±0.02

B0ffK0 40±7 4.5±0.8±0.3 …

First 5s observation of B0ffK0

ACP consistent with 0 (SM expectation)

mff<2.85 GeV region

PRD 84, 012001 (2011)

464x106 BB pairs

Recent CP violation results from BaBar

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