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1 Highlights from Belle Jolanta Brodzicka (NO1, Department of Leptonic Interactions) SAB 2009 Slide 2 2 Plan CPV studies Nobel Prize for Kobayashi and Maskawa B decays with missing energy: New Physics probe D s meson spectroscopy D 0 - D 0 mixing: charm highlight B s Physics: also possible at Belle The Future Belle experiment at KEKB KEKB: asymmetric e + e - collider e + : 3.5 GeV e - : 8.0 GeV s = 10.58 GeV = (4S) mass e + e - (4S) BB Operating since 1999 Peak luminosity: 1.71 10 34 cm -2 s -1 1M BB/day Integ. luminosity: 860 fb -1 @ (4S) Upgrade to Super KEKB approved Super Belle collaboration formed Slide 3 3 The Nobel Prize for Kobayashi and Maskawa: the crown of CPV studies K-M idea: 3 rd quark family (b,t) introduced irreducible phase in quark mixing matrix (complex couplings between quarks) CP violation (in processes with interference sensitive to the complex phase) B-Factories have verified predictions of the K-M mechanism CPV in B system: observed in several processes Relations between CKM parameters: tested CPV studies: goal reached d u V ud W + V ud V us V ub d L ~ ( u c t ) L V cd V cs V cb s W + V td V ts V tb b L V CKM V ub V td: complex Slide 4 4 CPV: observations, out of many K-M predicted two types of CPV violations: both observed Time dependent CPV. Golden mode: B 0 J/Ks + B 0 - B 0 mixing: time dependent B 0 K - + Direct CP violation: difference in decay rates for B 0 K + - and B 0 K - + + A CP = -0.094 0.018 (stat) 0.008 (syst) B 0 K _ B 0 K A CP ( t) = S sin( m d t) S= 0.642 0.031 (stat) 0.017 (syst) Slide 5 5 V CKM is unitary matrix: V CKM V CKM =1 From unitarity relation: Angles and sides of the Untarity Triangle: fundamental SM parameters Measure both angles and sides UT over-constrained consistency Confirmed: UT is a triangle (within ~10% accuracy) Next step: any effects beyond KM mechanism? Tests of Unitarity Triangle A CP in B 0 J/ K 0 A CP in B 0 , , A CP in B D (*) K (*) semileptonic B decays B - B oscillations UT sides Directly measured: = (21 1) o = (92 7) o = (78 12) o From UT sides: = (24 2) o = (92 4) o = (64 4) o 2008 Slide 6 6 Theoretically clean (small hadronic effects) Sensitive to New Physics: charged Higgs effects at tree level Experimentally challenging: multiple neutrinos in final states B decays with missing energy beyond SM amplitudes Slide 7 7 Decay chain: B 0 D* - + D* D 0 D 0 K , K 0 e e , Signal side Tagging side First observation of exclusive semi-tauonic B decay Analysis performed entirely in Krakow Study continued: other channels B D , polarization analysis Important topic at SuperB Factory B 0 D* - + : highlight of B decays 2007 A. Matyja, M. Raska et al. PRL 98, 211803 (2007) Signal yield: 60 +12 (5.2 with syst.) -11 BF(B 0 D *- + )=(2.02 +0.40 (stat) 0.37 (syst) ) 10 -2 -0.37 Slide 8 8 Study of B + D 0 D 0 K + Dalitz plot Observation of new meson: D sJ (2700) + D 0 K + Radial excitation of D s * or L=2 orbital excitation? Toward interpretation: resonances in D*K studied D s spectroscopy J. Brodzicka, H. Paka et al. PRL 100, 092001 (2008) J P =1 - cos hel D sJ (2700) M(D 0 K + ) D sJ (2700) ? M(D* + K s 0 ) Signal yield / 40 MeV On the PRL cover M = 2708 9 11 MeV = 108 23 +36 MeV -31 Slide 9 9 D 0 - D 0 mixing : most unexpected result of 2007 Mixing observed in K 0 (1958), B 0 d (1987) and B 0 s (2006) Unique for D 0 : only d,s,b quarks enter the box mixing suppressed New Physics can enlarge x and y Mixing modifies decay time distribution perform time dependent study of produced D 0 and D 0 Measure D 0 lifetime from its decay length D 1, D 2 : mass eigenstates D 0, D 0 : flavor eigenstates Mixing governed by x and y |x|, |y| ~ O (10 -2 )|x| ~ O (10 -5 ) Slide 10 10 D 0 K + K - and + - : CP even eigenstates D 1 =1/ 1 D 0 K - + : not CP eigenstate =f(1/ 1, 1/ 2 ) Lifetime difference between non-CP and CP eigenstates access to mixing if y CP 0 D 0 - D 0 mixing Measured proper decay time distributions: y CP from D 0 K + K -, + - Significance:3.2 First evidence for D 0 mixing no CPV found Belle PRL 98, 211803 (2007) y CP = -1 = y (K - + ) (K + K - or + - ) + = t (fs) t (fs) if no CPV (in SM: CPV