HQL04 - Maria Chiara Simani (LLNL) B A B AR Measurements of the CKM angle  with the B A B AR experiment Maria Chiara Simani (Lawrence Livermore Nat. Lab) (for the B A B AR collaboration) HQL04, Puerto Rico - 1 st June 2004

HQL04 - Maria Chiara Simani (LLNL) 2 V ud V cd V td V us V cs V ts V ub V cb V tb ds b u c t The Cabibbo-Kobayashi-Maskawa Matrix In the SM, the CKM matrix describes “weak” interactions between the 3 quark generations. Quark mass eigenstates = weak interaction eigenstates area ~ |V ij | 2 Wolfenstein parameterization (  = sin  c = 0.22 is the Cabibbo angle )  is the only parameter contributing to CPV in the Standard Model V CKM = ~

HQL04 - Maria Chiara Simani (LLNL) 3 The Unitarity Triangle (1,0) (,)(,) (0,0) V ub * V ud V cb * V cd V tb * V td V cb * V cd Over-constrain UT  Measure all angles and all sides (in more than one way!) Test for new Physics The area of the triangle is  2 Using the unitarity property of the CKM matrix, we can graphically represent the CKM matrix as triangles in the complex plane. E.g. choosing  V ud V ub + V cd V cb + V td V tb = 0 *** Testing the Standard Model with B-factories      

HQL04 - Maria Chiara Simani (LLNL) 4 Measuring CPV in B decays mixing decay CP violation results from interference between decays with and without mixing At least 2 amplitudes with different phase are needed Time-dependent CP asymmetry Amplitude ratio B 0  f cp / B 0  f cp Example: in B 0  J/  K S 0 C=0 and S=sin2 

HQL04 - Maria Chiara Simani (LLNL) 5 Where do we stand today? In this talk: –Latest BABAR results for CP measurements of penguin dominated modes: B 0 →  K S B 0 → f 0 (980)K S B 0 →  0 K S B 0 → K + K - K S –Reduce 4-fold ambiguity on  to a 2-fold ambiguity: new method and first measure of cos2  sign with B 0 → J/  K *0 events sin(2  ) = ± (stat) WA for the “golden modes” sin2  measured with very high precision in B 0 → [J/ ,  (2S),  c1 ] K S (b → ccs decays)

HQL04 - Maria Chiara Simani (LLNL) 6 Principle of the measurement Fully reconstructed decay mode of defined CP state Determine time between decays Use second B decay to distinguish between B and B B-Flavor Tagging based on - particles content - event topology - kinematics Asymmetric energies produce boosted  (4s) (Z tag resolution ~ 180  m) l K-K-

HQL04 - Maria Chiara Simani (LLNL) 7 PEP-II collider at SLAC High Energy ring Low Energy ring - 9 GeV e- / 3.1 GeV e+ - Instantaneous luminosity L peak ≈ 9.2 x cm -2 s -1 ~ 9 bb events per second injector Results shown here based on: Run1+Run2: ~82 fb -1 Run1+Run2+Run3: ~113 fb -1 Run1 Run2 Run3 Run4 Asymmetric B Factory: Optimized for time-dependent asymmetries

HQL04 - Maria Chiara Simani (LLNL) 8 Cerenkov Detector (DIRC) 144 quartz bars K, separation > 3.5 Electromagnetic Calorimeter 6580 CsI crystals e + ID,   and reco Drift Chamber 40 layers Tracking + dE/dx Instrumented Flux Return 19 layers of RPCs   and K L ID Silicon Vertex Tracker 5 layers of double sided silicon strips e+e+ e-e- The BaBar Detector

HQL04 - Maria Chiara Simani (LLNL) 9 CP measurements from penguin dominated modes Modes dominated by penguin diagrams, e.g B 0   K s (b  s), provide the best possibility of observing new physics Sensitive to new particles in the loop. Most new physics scenarios incorporate CPV However, these decays measure a sin2  eff value which may differ from sin2  in SM depending on the mode… B0B0  KsKs “Naïve” expected deviation T/P |-  f S f – sin2  |  K s 0.0 < 0.3 [2] (<0.04)  ’ K s ~0.02 [1] < 0.4 [2] (<0.09)  0 K s ~0.04 [1] < 0.2 [3] [1] D.London and A.Soni, PLB 407,61-65 (1997). [2] Y.Grossman, Z.Ligeti,Y.Nir, H.Quinn, PRD68, (2003). [3] M.Gronau, Y.Grossman, J.Rosner, PLB579, (2004). Limitations: - Theoretical uncertainties from SM - Require a lot of data... s

HQL04 - Maria Chiara Simani (LLNL) 10 asymmetry B 0 →  K S and B 0 →  K L In SM, measure: - B 0 →  K S, for ~ +sin2  - B 0 →  K L, for ~ -sin2  Updated B A B AR ‘04 ( L=108fb -1 ) B A B AR B0→KSB0→KS B0→KLB0→KL tag B 0 →  K S 70±9 events B 0 →  K L 52±16 events tag All events Backgrd

HQL04 - Maria Chiara Simani (LLNL) 11 B 0 → f 0 (980)K S Total Continuum All bgk. Quasi 2-body analysis: –Cut on the Dalitz plot to reduce contributions from  0 and f 0 (1370) B A B AR (L=111fb -1 ) 94±14(stat)±6(syst) events B 0 → f 0 (980)K S In this case, decay measures: Decay is dominated by b → sss penguin, the b → uus tree is doubly Cabbibo suppressed compared to leading penguin. ƒ 0 (980) is produced in ss peak and decays via uu peak:  B 0 → f 0 (980) K S 

HQL04 - Maria Chiara Simani (LLNL) 12 Consistency check by fitting  +  - mass spectrum of f 0 (980) with relativistic Breit-Wigner B A B AR Total Continuum All bgk. B A B AR Total Continuum All bgk. CP fit results for B 0 → f 0 (980)K S B A B AR ( L=111fb -1 ) tag asymmetry

HQL04 - Maria Chiara Simani (LLNL) 13 1 st measurement of sin2  from B 0     K s Special approach required for vertexing Constrain Ks in x-y to beam-spot B tag - Standard Method e+e+ 00 KsKs ++ -- y z Beam e-e- B A B AR 122  16 events None of the decay product come from the primary B 0 vertex Use K S direction to determine B 0 decay point Determine  t in the usual way

HQL04 - Maria Chiara Simani (LLNL) 14 CP fit measurement from B 0     K s B A B AR B A B AR ( L = 110fb -1 ) asymmetry tag BABAR established a new technique to extract CPV parameters from a decay channel thought to be experimentally inaccessible!

HQL04 - Maria Chiara Simani (LLNL) 15 B 0 → K + K - K S and B + → K + K S K S 3 body final state decay B 0 → K + K - K S (excluding B 0 →  K 0 events) B + → K + K S K S 122±14 events Measure both branching ratios to determine CP-even fraction, by using isospin symmetry: B A B AR (110fb-1) B 0 → K + K - K S 201±16 events B0B0 KsKs K-K- K+K+

HQL04 - Maria Chiara Simani (LLNL) 16 CP fit results for B → KKK S ƒ even determination: –Br(B 0 → K + K - K 0 )=(23.8±2.0±1.6)×10 -6 –Br(B + → K + K S K S )=(10.7±1.2±1.0)×10 -6 → ƒ even =0.98±0.15±0.04 –Consistency check with angular distribution decay measures ~ –sin2  Also, 1st measurement of CP-violating charge asymmetry with B + → K + K S K S : A CP (B + → K + K S K S ) = −0.042 ± (stat) ± 0.02 (syst) B A B AR ( L=110fb -1 ) B A B AR asymmetry tag SM assuming ƒ even =100%

HQL04 - Maria Chiara Simani (LLNL) 17 A recent picture of sin2  … No evidence of new physics yet Let’s wait for more data… b  s penguin: - average BaBar only: 0.63  0.18 Summary of sin2  measurements in penguin decay modes (including those not discussed in this talk) BABAR only PRELIMINARY !!!

HQL04 - Maria Chiara Simani (LLNL) Measurement of cos2  sign with B 0 →J/  K *0

HQL04 - Maria Chiara Simani (LLNL) 19 Measure cos2  with B 0 → J/  K *0 The CP content of the Scalar → Vector Vector B 0 → J/  K *0 (892) decay is both even and odd. cos2  appears through CP-even and CP-odd interferences in the observables of the time-dependent angular distribution terms where the coefficients P, S and C depends on the angular decay amplitudes and their strong phases  0,  ||,   : Time-dependent asymmetry: → →

HQL04 - Maria Chiara Simani (LLNL) 20 Measure cos2  with B 0 → J/  K *0 The two solutions makes cos(     ) and cos(     ) change sign  overall sign of cos2  is still ambiguous ! … with K*(892) alone. We can use neutral and charged B → J/   decays to determine the strong phases…… Up to the 2-fold ambiguity :

HQL04 - Maria Chiara Simani (LLNL) 21 1 st step: Measurement of amplitudes m ES (GeV/c 2 ) Note the 7.6  significance non-trivial strong phase:     = 0.597±0.077±0.017 Amplitudes measured by angular analysis of: B 0 → J/  (K +   ) *0 (+c.c.) B + → J/  (K S   ) *+ (+c.c.) B + → J/  (K +  0 ) *+ (+c.c.)  ||  0 = ± ±    0 = ± ± B A B AR (L=82fb -1 ) B 0 → J/  (K S  0 ) 131±14 events B 0 → J/  ( K +   ) 2376±51 events B + → J/  (K S  + ) 670±27 events B + → J/  (K S  0 ) 791±33 events solution I solution II      = ± ±     = 2.958± ± PRELIMINARY !!! value stat. syst. |A 0 | 2 = ± ± |A || | 2 = ± ± |A  | 2 = ± ± 0.004

HQL04 - Maria Chiara Simani (LLNL) 22 Accounting for a K  S-wave in m K  A broad K  S-wave is known to lie in the K*(892) mass spectrum region [Nucl. Phys. B296,493, (1988)]; This introduces a new amplitude to describe B → J/  (K  ) S-wave : –relative strengths of the relative P and S contributions; –and add a new relative phase : z  S   But the ambiguity on z can be solved ! B A B AR (L=82fb -1 ) K +   invariant mass The ambiguity now becomes (solutions I and II): P-wave S-wave …clearing the ambiguity on the strong phases too !

HQL04 - Maria Chiara Simani (LLNL) 23 Breaking the strong phases ambiguity S-wave intensity sol. I sol. II Phase of a resonance rotates counter-clockwise with increasing mass In the K*(892) region: –P-wave phase moves fast; –S-wave phase moves slow;  z  S  0 must rotate clockwise Fit for P and S wave intensities and z by K  mass bins, fixing     and     to: –Solution I : (2.729, 0.184) –Solution II : (3.554, 2.958) Physical behavior observed for solution II ! B A B AR P-wave intensity z  S  0 z/ 

HQL04 - Maria Chiara Simani (LLNL) 24 Comparison with LASS data Is this behaviour expected for a K  S-P phase ? Compare with LASS data; –Kp → K  (n) scattering –Only I=1/2 contribution; –Global phase  added to LASS data points; Evolution of z  is remarkably in agreement with LASS data ! Solution II is the physical solution sol. I sol. II B A B AR data compared to LASS data z/ 

HQL04 - Maria Chiara Simani (LLNL) 25 PRELIMINARY !!! 2 nd step: Measurement of cos2  sign cos2  measured by a time and angular analysis of the B 0 → J/  (K S   ) *0 sample: –104 tagged events (low statistics…) cos2  =3.32 cos2  =0.68 B A B AR Fit with sin2  free parameter: Fit with fixed sin2  = 0.731:

HQL04 - Maria Chiara Simani (LLNL) 26 Estimation of the significance of cos2  sign  Exclude cos2  % -3.1% ~ 89% CL Assuming that sin2  and cos2  come from the same angle 2 , there are two possible solutions: cos2  ±  sin 2 2    ± 0.68 Generate several thousand Toy MC with both solutions Estimate the heights, h + and h -, of the generated distributions at the measured value of cos2  for both soultions Probability for solution cos2  = is h - /(h + + h - )=( 8.1 ± 3.1 )% PRELIMINARY !!!

HQL04 - Maria Chiara Simani (LLNL) 27 Summary… CP -Violation has been well established in the B system: sin2  in b → ccs is a precision measurement –New updates ready this summer (book your plane to Beijing!) Measurements of sin2  in other decay modes, b → s penguin, are beginning to emerge, but need more data –Final result for  K 0 –First CP measurement of f 0 K S –CP measurement for K S  0 submitted to PRL –New measurement of K + K - K S and first measurement of K ± K S K S Interesting preliminary measurement of cos2  sign –New method to break the B→J/  K *0 strong phases and related cos2  sign ambiguities;

HQL04 - Maria Chiara Simani (LLNL) 28 …and conclusion From BABAR point ov view, with the current amount of data, CP measurements in penguin modes and cos2  sign measurement indicate that the angle  is Standard Model like.

HQL04 - Maria Chiara Simani (LLNL) 29 Backup Slides

HQL04 - Maria Chiara Simani (LLNL) 30 Old result: Fit to  Ks, Ks  +  - (80 fb -1 ) Old Ks  +  – only: S =  0.52 C =  0.41 Overlap between reprocessed (new) Run1+2 and old Ks  +  – set (80% overlap) Old Ks  +  – : S = 0.02  0.55 C =  0.44 New Ks  +  – : S = 0.05  0.51 C =  0.48 New+Run3 Ks  +  – : S = 0.45  0.43 (110 fb -1 ) C =  0.37  S ~ 0.0  C ~ 0.3 B 0 →  K S history

HQL04 - Maria Chiara Simani (LLNL) 31 K L modes CP=+1 sin2  = 0.72  0.16 B 0  J/  K L 0 -- Ks vs KL: different final CP mode K s modes CP=-1 sin2  = 0.76  0.07

HQL04 - Maria Chiara Simani (LLNL) 32 Value of C

HQL04 - Maria Chiara Simani (LLNL) 33 cos2  contour plots

HQL04 - Maria Chiara Simani (LLNL) 34 True  t, Perfect tagging True  t, imperfect tagging Measured  t, imperfect tagging Effect of experimental precision on CP measurement F(t) A CP (t) D = (1-2) where w is mistag fraction. Must measure t resolution properties. sin2 Dsin2 Must measure flavor tag Dilution.