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BaBar: Study of CP violation in B decays

BaBar: Study of CP violation in B decays. Hassan Jawahery Outline UMD people in BaBar A brief introduction to BaBar & its physics goals An overview of Maryland contribution to the experiment Future More details on our program in following talk by D. Roberts, H. J. UMD in BaBar. Faculty:

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BaBar: Study of CP violation in B decays

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  1. BaBar: Study of CP violation in B decays • Hassan Jawahery • Outline • UMD people in BaBar • A brief introduction to BaBar & its physics goals • An overview of Maryland contribution to the experiment • Future • More details on our program in following talk by D. Roberts, H. J.

  2. UMD in BaBar • Faculty: • H.Jawahery & D. Roberts • Research associates: • Wouter Hulsbergen (Since Sept. 2002-at SLAC) • BaBar vertexing coordinator (Dec. 2002- present) • BaBar Tracking coordinator (Jan. 2003- Jan. 2005) • Co-convener of Radiative Penguin working group (March 05- present) • Physics analysis projects with Jawahery and students • Chunhui Chen (Since Sept. 2003-at SLAC) • SVT operation manager • Physics analysis projects with Roberts and Students • Gabriele Simi (Since Feb. 2005-at UMD) • SVT operations • Physics analysis with Jawahery and students • Graduate students • Joe Tuggle (Started in summer 2004- at SLAC since summer 05) • Jake Anderson (Started summer 2005- at UMD) • Chung Khim Lae (To graduate in 2005-at SLAC) • Dmytro Kovalskyi (To graduate in 2005-at SLAC)

  3. BaBar’s Primary Physics Goals • CPV in B decays: • Is CP symmetry broken in B decays? Yes---- Done • Is the CKM the dominant source of CPV in the quark sector? Yes ---- Done • Is the CKM unitary? • More precise measurements of the angles and sides of the CKM unitarity triangle needed to settle this. • Search for physics beyond the SM: • Search for the effects of N.P. (new particles, new sources of CPV,..) through virtual processes. Is the NP flavor blind? Or the masses of the NP particles are too large to affect this sector? • The main focus is on CPV studies of the “pure” penguin ( bs) decays . • Rare Tau and Charm Decays • Bread and Butter Physics of Charm, Tau and B Decays, Spectroscopy, ..

  4. PEPII 3.1 GeV e+ on 9 GeV e- <bg> = 0.55 • Peak Luminosity ~3  1033 cm-2 s-1 reached >9x1033 cm-2 s-1 summer 2004 – down from July 04- March 05 due to upgrades and accident in Oct. 05. • Peak lumi back to 9x1033 cm-2 s-1- struggling to go up. Construction of the PEP-II asymmetric storage ring commenced in 1993 • Construction of the BABARdetector began in 1994 • PEP-II had first collisions in the Summer of 1998 • BABARwas rolled onto the beamline in Spring 1999 and saw its first events on May 26, 1999

  5. PEP-II Interaction Region and the BaBar Detector LER HER e+ e- BaBar Collision point

  6. Data sample collected: 287.89 fb –1 (as of Aug. 14, 05) 199920002001200220032004 2005  1.62  23.76   40.05   31.32   56.71   77.19 37.24

  7. Lately--

  8. PEP-II Upgrade Plans after Run 5 • Lower y* down to 8mm • Raise LER beam current from 3.3 to 4.5 A • Increase LER bunch current from 1.9 mA to 2.6 mA • Raise HER beam current from 1.8 to 2.2 A • Increase HER bunch current from 1.05 mA to 1.3 mA • Shorten bunch lengths to 9 mm • Reach peak luminosity by Summer 2006 • Increase luminosity to 2.41034 cm-2 sec-1

  9. Goals for PEP-II 2004-2009

  10. A Brief intro to BaBar physics

  11. Definitions CP The Unitarity Test f1=b f2=a f3=g

  12. cos2b < 0 ruled out @ 87% CL)

  13. The B meson system : A quantum inteferometer for CPV Studies u,c,t u,c,t W- W- sin 2b J/y K0s E.g. for the Golden modes =

  14. BaBar:sin2b = 0.722  0.040 (stat)  0.023 (syst) hcp=-1 hcp=+1 WA: sin2b = 0.685  0.032 (stat)

  15. Past UMD focus: Measurements of Bpp & Kp Decaysand determination of a & g Last year - 2004 Last year - 2004 Evidence Direct CPV ?

  16. First observation of Direct CPV in B decays BABAR BABAR 4.2s Belle Confirmation at ICHEP04 3.9s New Belle Result: -0.113+/- 0.022+/- 0.008 -0.115+/- 0.018 Average

  17. Measuring a For a full Isospin analysis need: Still some constraint can be set using the measured average Branching fraction: Da With WA Br(B p0 p0 ) and direct CPV |a-aeff |<35o at 90% c.l. Brr comes to the rescue: |a-aeff |<11o at 90% c.l. a = 100+/- 13 degrees

  18. Searches for Deviation from the Standard Model

  19. u,c,t u,c,t W- W- B0D*+D*- + B0D*+D*- • Time-dependent CP asymmetry In SM expect the sine coefficient: -sin2b Details in D. Roberts’ talk. Within the SM This is sin2b but New Physics may show up through loop diagrams

  20. b  sss Standard Model New Physics & b sdd penguins & CPV in Bsg Jawahery et al

  21. Directly copied from L. Silvestrini at Lepton-Photon 2005

  22. No Significant deviation from SM yet

  23. UMD’s effort in the study of New Physics search with b->s measurement • Time dependent CPV measurements of the decays (Jawahery,Hulsbergen, Jawahery, Kovalskyi, Simi, Tuggle) • BKsp0 (gluinic penguin process) • BKsp0 g (EW penguin process b->sg) • B Ksh g, Ksh’ g, Ksf g, .. (New effort) Pioneered the analysis technique that made these measurements possible (Beam constrained Vertexing for modes with no charged partilces at the B vertex.) • Hulsbergen is Co-convener of Radiative penguin analysis working group

  24. Measuring Dt for TDCP analysis: y x p+ p- p0 Ks ~30 mm ~4 mm Beam ~200 mm Inflated Beam Problem: No charged particle in final state Solution: Extrapolate Ks to the beam position Short B lifetime and small transverse motion of B makes this possible, when Ks’s are measures in Silicon Vertex tracker Same technique that we invented for BKsp0 + KS - BCP 0  Btag

  25. The Method Validated using BJ/Y Ks events: Measured sin2b ignoring J/Y in Dt caclulation

  26. Helicity Flip Suppressed by ~ ms/mb mixing TDCP asymmetry in bsg: Within SM: g is polarized (bs gL ,, b(bar) s(bar) gR) (to ~ ms/mb) Beyond SM may be different  g helicity serves as a NP observable :(A. Atwood, M. Gronau & A. Soni (1997)) AGS also prescribe the method to measure it via the usual BB interferometery The value of SK*g as a NP observable of course depends on SM uncertainties - Expect:

  27. TDCP analysis requires modes common to B0 and B0(bar): • The most significant mode: BK*(890)g with Br=(40.1 +/- 2.0) x10-6 with K*K0p0 , K0 Ks  13.4x10-6 • BK2*(1430) g [ Br=(12.4 +/- 2.4) x10-6 ] Others and &non-resonant BKsp0 g ( 1.25<M(Kp)<1.6 Br<2.6 x10-6 ) • Also: BKs h g Br =(8.4 +3.6-3.1) x10-6 (Belle) B0Ks fg, Br <8.3x 10-6 [B+K+ fg, Br=(3.4+/- 1.0) x10-6 ] Belle BKs h’ g, Br (?)

  28. Data BaBar(232 M BB’s) BK*(Ks p0) g Nsig:157 +/- 16 events Nqq_bkg~50 events NBB_bkg =9+/- 13 events (fit) ~30 (estimated)( 50% from b->sg) BKs p0 g Nsig: 59 +/- 13 NBB_bkg=130+/- 40 (fit) ~110 (estimated) (50% from b->sg) 275 M BB’s

  29. BaBar(232 M BB’s)

  30. - 232 M BB 275 M BB’s SK*g =-0.21 +/- 0.40 +/- 0.05 CK*g = -0.40 +/- 0.23 +/- 0.04 SK*g =0.01 +/- 0.51 +/- 0.11 CK*g = -0.11 +/- 0.33 +/- 0.09 SKsp0g =-0.21 +/- 0.40 +/- 0.05 CKp0g = -0.40 +/- 0.23 +/- 0.03 HFAG Average: SK*g =-0.13 +/- 0.32 & CK*g = -0.31 +/- 0.19 SM: ~0

  31. Comments on systematic Errors & Prospects ~ 4 ab-1 For combined BaBar and Belle data at ~2010 ~ requires super B factory

  32. UMD contributions to BaBar • Detector: • Silicon Vertex Tracker: System Management, Operation, Alignment (Roberts,Chen, Lae) (Also Lillard and Schieck in the past) • Drift Chamber: Environmental monitoring system (Jawahery, Kovalskyi) (also Bard, Olsen and Farbin in the past ) • BaBar Detector Control: Coordinator (Olsen) • Reconstruction software: • Tracking: Coordination (Hulsbergen), (Also efficiency and performance studies: Jawahery & Dallapiccola in the past) • SVT alignment (Roberts, Lillard, Lae and Schieck) • Particle Identification: Corrections to DIRC theta-c measurements at high momenta (Dallapiccola, Farbin and Jawahery in the past) • BaBar computing: • Contribution to Implementation of the New computing model (Lae, Farbin, Hulsbergen, Roberts) • Co-chair of BaBar computing model 2 (Jawahery in 2002)

  33. Analysis: • Study of the decays BDD: Measurement of rates, polarization and CPV effects. Deviations from SM could signal Physics beyond SM. • Study of Penguin Dominated decays: BK0p0 & BK*0g, fKg,.. Search for Physics Beyond the SM through deviation of CPV parameters from the SM expectation • Study of charmless B decays with the goal of measuring the angles a and g :CPV measurements in Bpp & Kp, KK • Study Rare Leptonic Charm decays: De+ e- & Dm+ m-, ..

  34. Other responsibilities & leadership positions • Roberts: • Co-system manger of Silicon Vertex Tracker (SVT) (June 2003- present) • Co-led and developed the SVT alignment software (with LBL group) • Jawahery: • Served as Physics analysis coordinator of BaBar(2001-2002) • Was resident at SLAC Sept. 2001-Sept. 2002 • Initiated and convened the charmless physics group in BaBar • Convener of B&C Physics group (2000) • Served as co-chair of computing model working group (re-design of BaBar computing & analysis system.) (Fall 2002) • Elected member of BaBar executive board (2003-2006) • Member of BaBar physics advisory group (2003-present) • Member of Roadmap group- studies and planning for super-B experiment at SLAC (2003-Present). Co-organizer of workshop on super-B at Hawaii (Spring 05) • Member of Physics reach steering committee • Hulsbergen: • BaBar tracking coordinator (July 2003- Dec. 2004) • Coordinator of BaBar vertexing software and validation studies (Dec. 2002- present) • Co-convener of Radiative Penguin analysis working group (April 2005- present) • Chen: Operation manager of SVT (Sept. 2004- Present). • Olsen (while at UMD) • Co-convener of charmless working group • Coordinator of BaBar detector control

  35. Past postdocs and graduate students • Jim Olsen  (Princeton Assist. Professor/ on BaBar) • Carlo Dallapiccola  (U. of Mass Assist. Professor/on BaBar) • Jochen Schieck  (Max Planck Institute) • Amir Farbin(graduated May 2003- postdoc at UMD 2004 -> U. Of Chicago CERN Fellow in 2005). • Bram Lillard (Graduated May 2004)

  36. Conclusion We expect many years of fruitful (& likely) exciting physics with BaBar. Now at around 300 fb-1 going for 1 fb-1. We will either end up with a very precisely known SM charged weak sector, which could help constrain the phase-space of the models of NP, or find a deviation from SM – to be confirmed directly at LHC.

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