Title Gabriella Sciolla Massachusetts Institute of Technology Representing the BaBar Collaboration Beauty Assisi, June 20-24, 2005 Searching for New Physics at the B factories: Measurements of sin2  at BaBar

2 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar BaBar and PEP-II BaBar detector 4  collider detector PEP-II asymmetric B factory 9.0 GeV e - beam 3.1 GeV e + beam Peak luminosity 9.1 x cm -2 s -1 Integrated luminosity Delivered: >268 fb -1 e+e+ e+e+ Most results in this talk are based on 227 M BB events

3 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar The Beauty of the Unitarity Triangle       Two ways of looking for New Physics: Compare measurement of sides and angles Measure angles in channels with different sensitivity to New Physics

4 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar The three roads to  Charmonium modes: J/ ψ K S, ψ(2S) K S, χ c1 K S, η c K S J/ψ K L J/ψ K* 0 (K* 0 → K S π 0 ) Open-charm modes: D* + D* −, D* + D −, D + D − Penguin-dominated modes: φ K 0, K + K − K S, K S K S K S η′ K S K S π 0, ω K S, f 0 (980) K S

5 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar CP violation in interference between mixing and decays mixing decay (f)(f) When only one diagram contributes to the final state: Example: B 0  J/  K S :

6 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar Exclusive B reconstruction How to measure the CP asymmetry. e-e- Flavor tagging Q=(30.5  0.5)%  (4S) B0B0 B0B0 e-e- ++ -- e+e+ ++ -- Precise  t determination  z~  c  t

7 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar The golden mode for sin2  : B 0  charmonium K 0 Theoretically clean Experimentally clean Relatively large BF (~10 -4 ) CP sample: m ES [GeV] Phys. Rev. Lett. 94, (2005)  E [MeV]

8 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar CP=+1CP=-1 sin(2  ) = ± stat ± syst Unbinned maximum likelihood fit to  t distribution Phys. Rev. Lett. 94, (2005) The golden mode for sin2  : CP fit in B  charmonium K 0

9 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar SM test in B 0  charmonium K 0 Compare sides and angles Both BaBar and Belle results used Ambiguity resolved measuring sign(cos2  ) in B 0  J/  K* cos(2  )=-0.68 excluded at 86.6%CL [PRD 71 (2005)032005] Excellent agreement with constraints from the sides Another SM triumph?. cos(2β)<0 cos(2β)>0 SM test #2: Compare  in various channels Measurements of angles NOT included in fit

10 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar The b  ccd trees: B 0  open charm Tree measures sin2  from b  ccd transitions Penguin expected to be small in SM (< few %) D*D*: as large as  = 0.6 [Grossman and Worah, 1997] New Physics could have large effects u,c,t

11 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar Vector-vector final state: CP-even and CP-odd admixture Transversity analysis measures f CP-even The open charm trees: Recent update: B 0  D* + D* - C CP+ = ± 0.17 ± S CP+ = 0.75 ± 0.25 ± 0.03 New BaBar Preliminary In good agreement with SM f CP+ = (87.5  4.4  0.7)%

12 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar The open charm trees: B 0  D ( * )  D  hep-ex/ S 0.54  0.35   0.33   0.63  0.06 C 0.09  0.25   0.24   0.35  0.06 D *+ D - D *- D + D+D-D+D- Updated New

13 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar The key to New Physics: The Penguin Modes Decays dominated by gluonic penguin diagrams The typical example: B 0   K S No tree level contributions In SM, top quark dominates the loop: C~0; S~sin2  Impact of New Physics could be significant New particles could participate in the loop  new CPV phases Low branching fractions Measure A CP in as many b  sqq penguins as possible! φ K 0, K + K − K S, η′ K S, K S π 0, K S K S K S, ω K S, f 0 (980) K S SM NP

14 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar The golden penguin: B 0   K 0 Combined  K S and  K L fit: Phys. Rev. D 71, (R) (2005)

15 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar For non resonant B 0  K + K - K S decays,  CP = 2 f even - 1 f even measured from angular moment analysis of the K + K - system Related channel: B 0  K + K - K S Phys. Rev. D 71, (R) (2005)

16 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar A new golden penguin: B 0  K S K S K S hep-ex/ (accepted by PRL) Theoretically clean Penguin dominated CP=+1 eigenstate Experimentally challenging B decay vertex uses K S pseudo-particles and beam spot constraint

17 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar The silver penguin: B 0   ’K S Relative large BF ~ 6 x Theoretically less clean than  K S Tree diagram possible … but Cabibbo and color suppressed… |  S| =|S  K -S Penguin |~ 0.01 QCDFact  0.1 SU(3) Phys. Rev. Lett. 94, (2005) S η′K s = 0.30 ± 0.14 ± 0.02 C η′K s = −0.21 ± 0.10 ± 0.02

18 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar The challenging penguins: B 0   0 K S, f 0 K S,  K S B 0   0 K S : dominated by tree contribution are non negligible (  S ~ 0.1 – 0.2) Experimental challenge: B CP decay vertex reconstruction (   t ~1ps) B 0  f 0 K S : In SM dominated by B 0   K S : In SM dominated by But tree can be relatively large hep-ex/ hep-ex/ hep-ex/ B00KSB00KS B0f0KSB0f0KS B0KSB0KS -  f S 0.35    0.02 C 0.06  0.18   0.31   0.03

19 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar “sin2  ” in penguins: BaBar only Although each measurement is compatible with J/  K S, a trend is visible  ’K S has the most significant shift (~2.9  if theory uncertainties neglected) … but statistical errors are still large…

20 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar Average of BaBar and Belle results Boxes are SM expected ranges for -  f S f from Beneke, hep-ph/ Shift still significant… S J/   - S penguins > 3  “sin2  ” in penguins: BaBar + Belle Statistical fluctuation or first signs of New Physics?

21 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar Summary and Conclusion Precision measurements of sin2  in many different channels are a powerful probe for New Physics B 0  charmonium K 0 : our calibration point (  sin2  ~ 0.04) B 0  open charm: no smoking guns so far B 0  penguin modes: intriguing shifts observed New Physics or statistical fluctuations? Time and data will tell… Goals for BaBar luminosity Summer 2006: 500 fb -1 Summer 2008: 1 ab -1

22 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar Backup slides

23 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar Transversity analysis D* + D* - is not a CP eigenstate sum of L=0, 2 (CP even) and L=1 (CP odd) CP odd fraction R  determined by transversity analysis

24 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar D*D analysis SM expectations D+D- D*D

25 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar cos and sin fits in penguin modes

26 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar The challenging penguins: B 0   0 K S In SM these decays are dominated by tree contribution are non negligible  S ~ 0.1 in model dependent QCD calculations  S ~ 0.2 in SU(3) Experimentally challenging B CP decay vtx from K S and beam spot K S tracks with > 3 SVT:   t ~1ps Unbinned max likelihood fit: N sig = 300 ± 23 hep-ex/

27 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar Two more penguins: B 0  f 0 K S and B 0   K S B 0  f 0 K S dominated by b  sss hep-ex/ hep-ex/ B 0  ωK S : dominated by b → sdd Tree contamination can be relatively large

28 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar The Other Trees: Recent update: B  D* + D* - Vector-vector final state: CP-even and CP-odd admixture Transversity analysis measures f odd f odd = (12.5  4.4  0.7)% C CP+ = ± 0.14 ± S CP+ = 0.65 ± ± 0.04 Results presented at Moriond 2005  Good agreement with SM BaBar Preliminary

29 G. Sciolla – M.I.T. Measurements of sin(2  ) at BaBar Penguins vs tree