Luca Lista, HEP-MAD 2004 Review of BaBar results L.Lista INFN - Napoli

Luca Lista, HEP-MAD 2004 Outline PEP-II and BaBar experiment CP Violation:  Direct CP violation  Measurements of sin2 ,  and  Measurements of |Vub| and |Vcb| Searches beyond the Standard Model Conclusions Many results skipped due to limited time…

Luca Lista, HEP-MAD 2004 PEP-II: Luminosity and Data Sample PEP-II is SLAC e  e  B factory running at the Y(4S) c.m. energy Y(4S) resonance decays to charged and neutral B-anti-B pairs Total: 244 fb -1 (Jul 31 st 04)

Luca Lista, HEP-MAD 2004 BaBar Detector DIRC (PID) 144 quartz bars PMs 1.5T solenoid EMC 6580 CsI(Tl) crystals Drift Chamber 40 layers Instrumented Flux Return iron / 18/19 planes of RPCs (muon / neutral hadrons) Silicon Vertex Tracker 5 layers, double sided strips e + (3.1GeV) e - (9GeV)

Luca Lista, HEP-MAD 2004 The Unitarity triangle CKM matrix measures Quarks mixing in weak interactions Unitarity relations lead to unitarity triangles in the complex plane B=(1,0) C=(0,0) A=( ,  )     B and  (b  cl ) 1

Luca Lista, HEP-MAD 2004 CP Violation (I, II) SM prediction for B mesons is very small: CP violation in mixing Direct CP violation in the decay CP first observed in kaon decays  q/p  A 2 2 If B decay amplitude to f is different from anti-B decay amplitude to anti-f. Requires a relative CP violating phase  2 and a CP conserving phase  2 q and p are the mass eigenstates coefficients in the flavor eigenstate basis; M - i½  is the 2  2 effective Hamiltonian

Luca Lista, HEP-MAD 2004 CP Violation (III) Time dependent CP Asymmetry: For a single amplitude Time dependent CP violation B0B0B0B0 f CP B0B0B0B0 b d WW d b t t B0B0 B0B0

Luca Lista, HEP-MAD 2004 B decay reconstruction and tagging m ES EE sideband s signal region m ES (GeV) Typical resolutions:  (m ES )  2.5 MeV  (  E)  MeV B kinematics tag Inclusive tag (lepton, K, …):  tag (1-2w) 2  30%  rec  15  40% Exclusive tag:  tag  0.1  0.2%  260  m   z (RMS)  150  m CP

Luca Lista, HEP-MAD 2004 Direct CP Violation hep-ex/ , submitted to PRL on B A B AR B flavor is tagged by the kaon charge B0KB0K A K  =   (4.2  ) BK0BK0 A K  = 0.06  0.06  0.01 Tree + Penguin contributions Pure Penguin Signal: 1606  51 events (227  10 6 BB pairs)  E (GeV) First observation of CP violation in B meson decays!

Luca Lista, HEP-MAD 2004 CP Violation in Mixing-Decay interference J/ψ K L (CP even) mode (cc) K S (CP odd) modes S = sin2  =   C = | | = |A/A| =   tagged CP events on 227  10 6 BB pairs =205fb -1 on peak Measured on a variety of cc decay modes Direct CP violation if  1

Luca Lista, HEP-MAD 2004 sin2  in the Unitarity Triangle plane cos2  > 0 at 87% C.L. Using an s- and p-wave interference in angular analysis of B  J/  K *0 (K S  0 )

Luca Lista, HEP-MAD 2004 ? “sin2  ” channels probing new Physics Decays dominated by loop diagrams can exhibit contributions from new physics B 0  K 0 S Signal: 819  38 events 3  deviation from charmonium sin2  B 0  K 0 S B 0  K 0 S  0

Luca Lista, HEP-MAD 2004 Comparison of sin2  modes 2.7  from s-penguin to sin2  (cc) 2.4  from s-penguin to sin2  (cc)

Luca Lista, HEP-MAD 2004 Measurement of sin2  Interference of suppressed b  u “tree” decay with mixing Penguin diagrams may be of the same magnitude. B 0 mixingB 0 decay: tree B 0 decay: penguin Isospin analysis could measure the amount of correction to 

Luca Lista, HEP-MAD 2004 sin2  with B  B 0     227  10 6 BB pairs S  =  0.17  0.03 C  =  0.15  0.04 B(B      0 ) = (5.80  0.06  0.40 )  A  0 =  0.10  0.02 Particle identification is fundamental p (GeV/c)  C (rad) B(B 0   0  0 ) = (1.17  0.32  0.10 )  C  0  0 =  0.56  0.06 |  -  eff | < 35° 90% C.L. (Gronau, London) Belle observes C  0  0 =  0.15  0.07 …

Luca Lista, HEP-MAD 2004 sin2  with B  Similar to , but smaller penguin pollution Not a CP eigenstate in principle, but observed to be almost pure CP = +1 B 0     122  10 6 BB pairs S long =  0.33  0.11 C long =  0.24  0.14  = ( 96  10 (stat)  4 (sys)  11 (peng) )° (Grossman, Quinn) B(B     0 ) = (  5.8 )  B(B 0  0  0 ) < 1.1  (90% C.L.) 277  10 6 BB 89  10 6 BB

Luca Lista, HEP-MAD 2004 Combined Combined B , ,  (Dalitz) From CKM matrix fit (with no  meas.): Fit + , ,  : “mirror” solutions become disfavored  =( 98  16 )°  =( )°

Luca Lista, HEP-MAD 2004 Gronau, London, Wyler, 1991: use B -  D 0 CP  (small D 0 B.r., 8-fold ambiguity) Atwood, Dunietz, Soni, 2001: interference in D and anti-D dec. to same final state Giri, Grossman, Soffer, Zupan, 2003: B   D (*)0 K , D 0  K S     Dalitz analysis Different methods to measure  GLW The phase between b  c and b  u transitions is  BB DD Color suppressed BABAR measurement, Phys.Rev.Lett.91:171801,2003 input: Size of CP asymmetry depends on:

Luca Lista, HEP-MAD 2004 B   D (*)0 K , D 0  K    ADS method No signal observed in 227  10 6 BB pairs  A ADS not measured, limits on R ADS 90% C.L. Upper limit Any  D,  1  on r D, 48°<  <73° Any  68% C.L. area Small r B values make measuring  hard D*  D 0  0, D 0  R ADS rBrB rB*rB*

Luca Lista, HEP-MAD 2004 B   D (*)0 K , D 0  K S     Dalitz analysis B   D (*)0 K , D 0  K S     Dalitz analysis 68% 90%  [deg] Sensitivity depends on r B ( * ) A posteriori r B (r B *) with uniform a priori Dalitz model syst. D*  D 0  0, D 0 

Luca Lista, HEP-MAD 2004 sin(2  +  ) using B 0  D ( * )-  + /  + favored b  c amplitudesuppressed b  u amplitude Exclusive reconstruction of D -  +, D* -  +,D -  + Partial reconstruction of D* -  + Time-dependent asymmetry can be expressed in term of the parameters: ~  ~  Time-dependent CP violation in the mixing/decay interference a = 2rsin(2  )cos  c = 2rcos(2  )sin  No CP asymmetry observed yet…

Luca Lista, HEP-MAD 2004 Vcb inclusive measurement Inclusive B → Xc l decays: measure hadron mass moments and lepton energy moments B (b→ cl )=(10.61 ± 0.16 exp ± 0.06 th,HQE, )% Partial B.F. Lepton energy momenta HQE predicts the moments up to 8 parameters to be fitted (including |V cb |, m b and m c )

Luca Lista, HEP-MAD 2004 Vcb: HQE Fits to M X / E l moments M X moments E ℓ moments ● = used, ○ = unused in the nominal fit Red line Yellow band Red line: HQE fit Yellow band: theory errors B A B AR   2 /ndf = 20/15 M1xM1x M2xM2x M3xM3x M4xM4x M0lM0l M1lM1l M2lM2l M3lM3l

Luca Lista, HEP-MAD 2004 Vcb exclusive measurements Exclusive B → D *+ l Decays B (B0→ D* - l + )=(4.90 ± 0.07 stat ± 0.36 syst )% w = prod. B, D* 4-velocities

Luca Lista, HEP-MAD 2004 Vub measurements Inclusive: measure total Br(b  ul ) Exclusive: measure selected decays (B  l,  l, …) Innovative technique: fully reconstruct one of the B Electron endpoint spectrum extrapolation using b  s  photon spectrum (CLEO) using HQET p (GeV/c) B(B  X u e )=(1.73  0.22 exp  0.33 extr.syst )  |V ub | = ( 3.94  0.25 exp  0.37 extr.syst  0.19 th )  B(B 0  - l + )=(1.08  0.28  0.16)  B(B 0  - l + )=(2.57  0.52  0.59)  B(B +  0 l + )=(0.91  0.28  0.14)  10 -4

Luca Lista, HEP-MAD 2004 Vcb and Vub averages |Vub| avg. = (4.70  0.44 stat+sys )  Exclusive modes LEP Inclusive studies |Vcb| avg. = (41.4  0.4  0.4  0.6 th )  10 -3

Luca Lista, HEP-MAD 2004 Radiative penguin decays Radiative penguin decays: b → s  and b → d  are FCNC transitions BF(b→s  ) TH = 3.57 ± 0.30 x (SM NLO) BF(b→s  ) EXP = 3.54 ± 0.30 x (HFAG average) Sum of 12 exclusive, self-tagging B → X s  final states X s = K/K s pions E   > 2.14 GeV b→sb→s b→sb→s A CP, b  s  = ± ± A CP, B  K*  = ± ± (prelim.) W could be replaced in the loop by new particles b → s  rate agrees with SM prediction: No evidence of direct CP violation: b→d  at discovery limits: BF(B →  ) < 1.2  |Vtd/Vts| < 0.19 (90% CL)

Luca Lista, HEP-MAD 2004 Studies of D sJ properties D sJ *(2317) + and D sJ (2460) + discovered in 2003 Detailed studies properties and mass meas.  B  D sJ ( * )+ D ( * ) angular analysis  spin  Branching fraction measurements J=1J=2 D sJ (2460) +  D s +  elicity D sJ (2460) + D s1 (2536) + D sJ* (2317) + m(D sJ* (2317) +  D s +  0 ) =  0.3  0.9 MeV/c² m(D sJ (2460) +  D s + , D s +  0 , D s +  +  - ) =  0.3  1.0 MeV/c² m(D s1 (2536) +  D s +  +  - ) =  0.4  1.2 MeV/c² m(D s +  +  - ), GeV/c²

Luca Lista, HEP-MAD 2004 Conclusions BaBar is exploring different aspects of CP violation in B meson  Recent first evidence of direct CP violation  sin2  is becoming a precision measurement  First quantitative estimates of   Technology for extracting  is being established Some channels may probe new physics  b  sss penguins? The increase of statistics in the following years will improve the experimental precision and will make more rare channels accessible

Luca Lista, HEP-MAD 2004 Pentaquark searches No evidence of pentaquarks in high statistics samples Cross section limits well below expectations      c + (2285) No signal for  5 -- No signal for  fb -1 m(pK S ) (GeV/c 2 )  5 + (1540)  5 -- (1862)  5 0 (1862) No signal for  5 + nK + pK S

Luca Lista, HEP-MAD 2004 Backup

Selex D sJ (2632) + state SELEX claims evidence of a state D sJ (2632) + decaying to D s +  and D 0 K + (hep-ex/ ) BaBar doesn’t observe such signal p * > 4.0 GeV/c M(D 0 K + ) GeV/c 2 Events/5 MeV/c 2 SELEX  m = M(K -   K + )  – M(K -  + ) MeV/c 2 D sJ (2573) + D sJ (2632) +

Luca Lista, HEP-MAD 2004 Selex D sJ (2632) + state (  D s +  ) No evidence of D sJ (2632) + in D s + , D 0 K +, D* + K S in 125 fb -1

Luca Lista, HEP-MAD 2004  (2S) X(3782) hchchchc J/     resonance at 3782 MeV/c 2 m X(3782) =3873.4±1.4 MeV/c 2 (B - →X(3872)K - ) ∙ (X(3872)→J/  +  - )=(1.28±0.41) ∙ B (B - →X(3872)K - ) ∙ B (X(3872)→J/  +  - )=(1.28±0.41) ∙   (2S) =556±30 No evidence of h c found Set an upper limit (B - →h c K - ) ∙ (h c →J/  +  ) B (B - →h c K - ) ∙ B (h c →J/  +  ) <3.4 ∙ (90% C.L.)