Gagan Mohanty University of Warwick Dalitz Plot Analysis in the Charmless three-body B Representing 12/1/2006Gagan Mohanty2 Outline of the talk Introduction Theoretical Framework Experiment & Dataset Event Selection DP Analysis Methodology Results and Discussion Conclusions and Outlook (*) DP = Dalitz Plot 12/1/2006Gagan Mohanty3 Introduction: Timeline (1993) 1 st observation of charmless B decays by CLEO Since then PRL 71, 3922 (1993) 12/1/2006Gagan Mohanty4 Introduction: Timeline (2006) A vast amount of results in the charmless sector is pioneering: A natural extension: quasi-two-body B decays to three-body final states test of QCD factorization direct CP search for new physics BaBar: PRL 93, K+-K+- K-+K-+ 12/1/2006Gagan Mohanty5 Theoretical Framework b s penguin transition contributes only to final states with odd number of kaons due to presence s quark e.g. K, KKK b u tree and b d penguin transitions contribute mainly to final states with even number of kaons such as , KK. Contribution to odd number kaon states is Cabibbo suppressed [~ sin c ] wrong flavor final states such as K + K + - and K - + + are expected to be exceedingly small at o( ) in the Standard Model, and offer an excellent window for new physics The dominant contributions to charmless three-body final state: b u b s/d 12/1/2006Gagan Mohanty6 Typical final states Shall focus on the Dalitz Plot analysis of above five charmless three-body decay modes from BaBar 12/1/2006Gagan Mohanty7 PEP-II asymmetric B factory Daily luminosity Run 5 9 GeV e - (4S) 3.1 GeV e + = 0.56 ~ 260 m L int > 300 fb -1 (10% off-peak) This talk includes 12/1/2006Gagan Mohanty8 Design = 3x10 33 cm -2 sec -1 ~ 3x Design ~ 100 pb -1 12/1/2006Gagan Mohanty9 BaBar Detector Cerenkov Detector (DIRC) 144 Quartz bars and PMTs 1.5T solenoid Electromagnetic Calorimeter 6580 CsI(Tl) Crystals Drift Chamber 40 layers Instrumented Flux Return Resistive Plate Chamber Limited Streamer Tube Silicon Vertex Tracker 5 layers, double strip e + (3.1GeV) e - (9GeV) e ID reco. & K L ID High quality tracking (fiducial volume: 041 < < 2.54) (p T )/p T = 0.13% P T 0.45% E /E = 2.32% E -1/4 1.85% Particle ID 12/1/2006Gagan Mohanty10 Event Selection Wish to select B hhh (h=K/ ) event out of sea of continuum and other type B events Done in several steps: Continuum rejection (Event topology) vs. K vs. e/ (Particle flavour Identification) Reconstruct K s / 0 from their decay products on vs. off resonance (Kinematical variables) Veto on charmed resonances: D, J/ , (2S) 12/1/2006Gagan Mohanty11 Continuum Rejection B s are produced at rest (spherical) vs. jetty udcs events Cuts on event thrust & Fisher discriminant/NN constructed out of the topological variables BackgroundSignal 12/1/2006Gagan Mohanty12 Particle Identification PID is crucial for the analyses distinguish K vs. (DIRC) veto the electron (DCH/EMC) Reconstruct 0 [ ] (EMC) and K s [ ] 12/1/2006Gagan Mohanty13 Kinematical Variables Utilize precise beam energy information & (E,p) conservation B + K + + - Sideband Signal box Background DP fit 12/1/2006Gagan Mohanty14 DP Analysis Technique 1 Dalitz Plot is a powerful technique relying on Lorentz invariant phase-space variables in a three-body decay B B Resonance {13} s ij = m 2 ij 12/1/2006Gagan Mohanty15 DP Analysis Technique 2 Extract c i and i by performing a max likelihood fit i has two terms: CP violating weak phase (ve) CP conserving strong phase same Separate fit of B and B samples B B { 12/1/2006Gagan Mohanty16 Efficiency Variation B + + + - Smooth variation of efficiency across the DP Use 2D parameterization in the likelihood fit Combinatorics is very small (mostly ignored) D J/ (2S) 12/1/2006Gagan Mohanty17 Background Parameterization B + + + - Use 2D histogram to model the DP distribution Continuum = off res + on res data sideband and B bkg = Monte Carlo & subtracted from latter Square DP for better describing peaking edge Continuum D J/ (2S) 12/1/2006Gagan Mohanty18 B + + + - : fitting the signal PRD 72, (2005) B+B+ B-B- Phase-space Coupled BW (770) f 2 (1270) 210 fb -1 12/1/2006Gagan Mohanty19 B + + + - : Summary PRD 72, (2005) 0 (770) is the dominant component 3 indication for f 2 (1270) & NR mode Little evidence for (seen by BES) Can be utilized to measure PRL 81, 4067 (1998) 12/1/2006Gagan Mohanty20 B + + + - : prospect for proposes to use B c0 , which carries a null weak phase, as the reference mode However, no indication of the c0 mode new reference mode needs to be studied Iso-scalar resonances e.g. f 0 (980) are proposed as alternatives Again statistics disallows any meaningful conclusion L int is the need of the hour! PRL 81, 4067 (1998) 12/1/2006Gagan Mohanty21 B + K + + - : fitting the signal PRD 72, (2005) B+B+ B+B+ B-B- B-B- qq BB Fit 205 fb -1 12/1/2006Gagan Mohanty22 B + K + + - : Summary PRD 72, (2005) Total BF differs significantly from Belle (K)* 0 => K* 0 (1430) resonance + Effective range NR component (again different in Belle) Evidence for direct CP violation in 0 (770)K mode 12/1/2006Gagan Mohanty23 Belle BABAR CP in charged B decays? PRD 72, (2005) hep-ex/ (2005) Large A CP in agreement with predictions based on global SU(2) fits |T/P|~0.3 PRD 69, (2004) Eagerly looking forward to more data 12/1/2006Gagan Mohanty24 B 0 + - 0 : time-dependent DP Parameterize B 0 (B 0 ) + - 0 amplitude in terms of + ( + 0 ) -, - ( - 0 ) + and 0 ( + - ) 0 } Time-dependent decay rate: f ( = +,-,0) are BW functions dependent on the DP variables PRD 48, 2139 (1993) Determine U and I (27 16 parameters for small 0 0 contribution) in the likelihood fit { 12/1/2006Gagan Mohanty25 B 0 + - 0 : DP fit and result Likelihood built using PDFs for the discriminating variables: E, m ES, NN, t & DP variable (square) Extract physics parameters from the fitted U and I : { Event yield = 1184 58 m hep-ex/ (2004) 192 fb -1 12/1/2006Gagan Mohanty26 B 0 + - 0 : and direct CP { Direct CP 2.9 level hep-ex/ (2004) 11 22 12/1/2006Gagan Mohanty27 Overall from BaBar from , and from a full CKM fit K, V ub, m d,s, sin(2 )) Mirror solutions being disfavored! mode particularly plays an important role From , , (combined) : (preliminary) 12/1/2006Gagan Mohanty28 B 0 K + - 0 : fitting the signal Gounaris-Sakurai LASS shape Uniform phase-space PRL 21, 244 (1968) NP B296, 493 (1988) Fit qq BB hep-ex/ (2004) 12/1/2006Gagan Mohanty29 B 0 K + - 0 : Summary hep-ex/ (2004) 4.2 evidence of K* 0 (892) mode, UL from Belle Negligible non-resonant contribution 90% CL UL Measured BF of the benchmark process B 0 D 0 0 in agreement with current world average: (270 80)x10 -6 No significant A CP observed in any of the modes 193 fb -1 12/1/2006Gagan Mohanty30 B 0 K + K - K s : fitting the signal 1 st attempt to study the K + K - K s Dalitz plot Narrow (1020) signal => use convoluted BW Handful events to claim any other resonances Try combinations of known 0 ++ and non-flat NR model to best parameterize the data f 0 (980) X(1500) NR 210 fb -1 12/1/2006Gagan Mohanty31 B 0 K + K - K s : Summary X(1500) NR c0 D +,D s + reflections hep-ex/ (2005) Ad hoc model to describe S-wave Need theory hand & more data 12/1/2006Gagan Mohanty32 Summary Charmless three-body decays move to the era of Dalitz plot analysis Branching fractions of many quasi-two-body decays are measured, some are the 1 st time measurements Evidence of large CP asymmetry in the 0 (770)K mode of the K final state Time-dependent Dalitz measurement of B 0 () 0 direct CP violation at 2.9 level and measured Mostly covered from BaBar, competitive results are available from Belle for many modes 12/1/2006Gagan Mohanty33 Backup Slides 12/1/2006Gagan Mohanty34 Future Prospects Double again from 2006 to 2008 ~ 1 ab -1 Double from 2004 to 2006 L int [fb -1 ] 12/1/2006Gagan Mohanty35 Square Dalitz Plot blow up bands & interference regions Jacobian ++ -- 00 12/1/2006Gagan Mohanty36 B : nominal fit results PRD 72, (2005) 12/1/2006Gagan Mohanty37 B K : nominal fit results PRD 72, (2005)