Rare and forbidden charm decays D10 → D0g motivation D0 → l+ l- motivation D10 → D0g method D0 → l+ l- method D10 → D0g results D0 → l+ l- results Rare and forbidden charm decays Boštjan Golob University of Ljubljana/Jožef Stefan Institute & Belle/Belle II Collaboration Introduction D10 → D0g D0 → l+ l- University of Ljubljana “Jožef Stefan” Institute Charm 2010, IHEP, Beijing, Oct 21 – 24, 2010

Introduction Experiments B-Factories BaBar @ PEPII SLAC Belle @ KEKB D10 → D0g motivation D0 → l+ l- motivation D10 → D0g method D0 → l+ l- method D10 → D0g results D0 → l+ l- results Introduction Experiments B-Factories BaBar @ PEPII SLAC Belle @ KEKB KEK on resonance production e+e- → U(4S) → B0B0, B+B- s(BB)  1.1 nb (~109 BB pairs) s(c c)  1.3 nb (~1.3x109 XcYc pairs) Nrec(D*+ → D0 p+ → K- p+ p+)  2.5x106 continuum production g* c B-factory= charm factory Belle Ldt  1020 fb-1 BaBar Ldt  550 fb-1

1P → 1S radiative transition L=1 D mesons: D10 → D0g motivation D0 → l+ l- motivation D10 → D0g method D0 → l+ l- method D10 → D0g results D0 → l+ l- results D10 → D0g M [GeV] D00 D1’ 0 D10 D20 Motivation 1P → 1S radiative transition L=1 D mesons: broad (j=1/2) doublet D00 → Dp, D1’0 → D*p S-wave decays narrow (j=3/2) doublet D10, D20 D-wave decays L=1 Ds mesons: “broad” doublet Ds0+ → DK, Ds1’+ → D*K narrow doublet Ds1+, Ds2+ exotic 4q states / convetional qq with corrections to q model/HQL ? 2.75 2.25 1.75    L=1 D mesons, D**  D*p Dp j=1/2 j=3/2 0+ 1+ 1+ 2+ JP M [GeV] Ds0+ Ds1’ + Ds1+ Ds2+ 2.6 2.4 2.2   D*K L=1 Ds mesons, Ds**  DK  j=1/2 j=3/2 0+ 1+ 1+ 2+ JP

1P → 1S radiative transition D10 → D0g motivation D0 → l+ l- motivation D10 → D0g method D0 → l+ l- method D10 → D0g results D0 → l+ l- results D10 → D0g M [GeV] D00 D1’ 0 D10 D20 Motivation 1P → 1S radiative transition use (not measured yet) D** radiative transitions as probes of internal structure; test the HQL, mixing between 1+ states; obvious 1st choice: D10 → gD0 (p0D0 forbidden) 2.75 2.25 1.75    L=1 D mesons, D**  Dg 0+ 1+ 1+ 2+ JP S. Godfrey, PRD72, 054029 (2005)

D10 → D0g Method D** from B decays B- →D10p - → (D0g)p - → (K-p+g) p - D10 → D0g motivation D0 → l+ l- motivation D10 → D0g method D0 → l+ l- method D10 → D0g results D0 → l+ l- results D10 → D0g B- p- DJ g, p0 D0 qJ Method D** from B decays B- →D10p - → (D0g)p - → (K-p+g) p - background from B- →D**0p - → (D0p0)p - (D00/D20) different helicity angle; simultaneous fit in bins of cosqJ: M(D0p0) for B- → (D0p0)p - decays; MC: feed-down shape & relative e for D0p0 reconstr. as D0g MC using results on D00/D20 properties from Belle, 605 fb-1, preliminary bins used in the measurement cosqJ B- → (D0p0)p - -1<cosqJ<-0.7 Belle, PRD69, 112002 (2004) 60 fb-1 M(D0p0)

D10 → D0g Method D** from B decays B- →D10p - → (D0g)p - → (K-p+g) p - D10 → D0g motivation D0 → l+ l- motivation D10 → D0g method D0 → l+ l- method D10 → D0g results D0 → l+ l- results D10 → D0g Method D** from B decays B- →D10p - → (D0g)p - → (K-p+g) p - simultaneous fit in bins of cosqJ: M(D0g) for B- → (D0g)p - decays; feed-down from D0p0 fixed Belle, 605 fb-1, preliminary -1<cosqJ <-0.7 -0.7<cosqJ <-0.4 -0.4<cosqJ <0 0<cosqJ <0.4 sum signal feed-down M(D0g)

D10 → D0g Result (first observation) D10 → D0g motivation D0 → l+ l- motivation D10 → D0g method D0 → l+ l- method D10 → D0g results D0 → l+ l- results D10 → D0g Result (first observation) using B(B- → D10p -)=(1.5±0.6) ∙10-3 from PDG  Belle, 605 fb-1, preliminary sum over cosqJ bins sum signal feed-down Ns=104 ±15 M(D0g) S. Godfrey, PRD72, 054029 (2005)

FCNC of uplike (c) quarks;  complementary constraints to B D10 → D0g motivation D0 → l+ l- motivation D10 → D0g method D0 → l+ l- method D10 → D0g results D0 → l+ l- results D0 → l +l - Motivation FCNC of D mesons FCNC of uplike (c) quarks;  complementary constraints to B (and K) rare decays; NP: enhancement of B(D0 →m+m-), B(D0 →e+e-), by orders of magnitude; possibility of LFVB(D0 →e+m-); example R SUSY: B(D0 →m+m-)~4∙10-6 B(D0 →e+e-)~10-10 B(D0 →e+m-)~10-6 short distance, B~10-18 long distance, B~few 10-13 G. Burdman et al., PRD66, 014009 (2002)

M(ll ), q=M(ll ps)-M(ll )-mp , Emiss , D10 → D0g motivation D0 → l+ l- motivation D10 → D0g method D0 → l+ l- method D10 → D0g results D0 → l+ l- results D0 → l +l - Method Normalization D0 →p+p - tagged D*+ →D0ps-; blind optimization of M(ll ), q=M(ll ps)-M(ll )-mp , Emiss , F.O.M.= ell /NUL comb. backgr. from q sideband, linear in M, q; D0 →p+p - control sample: same kinematic selection (except M); normalization; misid. background (p → m), using measured misid. probabilities w(p,cos q) Belle, PRD81, 091102 (2010), 660 fb-1 sideband signal region excluded sideband Npp  50·103

D0 → l +l - Results D0 →l +l - yield D10 → D0g motivation D0 → l+ l- motivation D10 → D0g method D0 → l+ l- method D10 → D0g results D0 → l+ l- results D0 → l +l - signal window Results D0 →l +l - yield U.L.’s calculated from N and Nbgexp including systematic uncertainties (negligible) U.L.’s @ 90% C.L. Belle, PRD81, 091102 (2010), 660 fb-1 channel D0 →mm D0 →ee D0 →em N 2 3 Nbgexp 3.1±0.1 1.7±0.2 2.6±0.2 signal @ 90% C.L. U.L.; comb. backg.; D0 →p+p - backg.; observed; acc. to PRD(RC)

D0 → l +l - Results Constraints on NP l R SUSY: D10 → D0g motivation D0 → l+ l- motivation D10 → D0g method D0 → l+ l- method D10 → D0g results D0 → l+ l- results D0 → l +l - Results Constraints on NP R SUSY: constraints on R couplings; leptoquarks: (genuine, coupling to l q; contribute to D(s) → mn, D0 → mm) B(D0 → mm)<1.4 ∙10-7 B(Ds → mn)=(0.590 ±0.033)% fDs(LQCD)=(248.0±2.5) MeV c u l J. Kamenik, private comm. G. Burdman et al., PRD66, 014009 (2002) 1.5 1.0 Ds → mn 0.5 KL → mm allowed 0.0 D → mn I. Dorsner et al., PLB682, 67 (2009) -0.5 -1.0 -1.5 1 2 3 4 5 x10-4 parametrization of leptoquark couplings

D0 → l +l - Results Constraints on NP l R SUSY: D10 → D0g motivation D0 → l+ l- motivation D10 → D0g method D0 → l+ l- method D10 → D0g results D0 → l+ l- results D0 → l +l - Results Constraints on NP R SUSY: constraints on R couplings; leptoquarks: (genuine, coupling to l q; contribute to D(s) → mn, D0 → mm) B(D0 → mm)<1.4 ∙10-7 B(Ds → mn)=(0.590 ±0.033)% fDs(LQCD)=(248.0±2.5) MeV c u l J. Kamenik, private comm. G. Burdman et al., PRD66, 014009 (2002) 1.5 1.0 D0 → mm Ds → mn 0.5 KL → mm allowed 0.0 D → mn I. Dorsner et al., PLB682, 67 (2009) -0.5 -1.0 -1.5 1 2 3 4 5 x10-4 parametrization of leptoquark couplings

B-factories active also in rare charm decays D10 → D0g motivation D0 → l+ l- motivation D10 → D0g method D0 → l+ l- method D10 → D0g results D0 → l+ l- results Summary B-factories active also in rare charm decays 1P → 1S charm meson radiative transition measured for the first time best UL’s on D0 →l +l - FCNC of charm: complementary constraints to rare B decays

Additional information D10 → D0g motivation D0 → l+ l- motivation D10 → D0g method D0 → l+ l- method D10 → D0g results D0 → l+ l- results Additional information D** from B decays B- →D10p - → (D0g)p - → (K-p+g) p - background from B- →D**0p - → (D0p0)p - (D00/D20) different helicity angle; simultaneous fit in bins of cosqJ: M(D0p0) for B- → (D0p0)p - decays

Additional information D10 → D0g motivation D0 → l+ l- motivation D10 → D0g method D0 → l+ l- method D10 → D0g results D0 → l+ l- results Additional information Normalization D0 →p+p - tagged D*+ →D0ps-; D0 →p+p - control sample F.O.M.= ell /NUL background estimated from tuned MC (6x data) UL’s FC w/o syst. 2.97