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Beyond the Standard Model: the clue from charm

Beyond the Standard Model: the clue from charm. y  D o D o , D o  K - p +. Marina Artuso, Syracuse University. K +. K -. p +. p -. K +. K -. Experimental strategies considered. Mixing Comparison between hadronic and lepton tagged modes from C= 1 D o D o pairs

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Beyond the Standard Model: the clue from charm

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  1. Beyond the Standard Model:the clue from charm yDoDo, DoK-p+ Marina Artuso, Syracuse University K+ K- p+ p- K+ K- Marina Artuso

  2. Experimental strategies considered • Mixing • Comparison between hadronic and lepton tagged modes from C=1 DoDo pairs • Study of “right-sign” leptons versus “wrong sign leptons” • CP violation • Direct CP violation in Do and D+ • Indirect CP violation in Do decays • CP violation measurements exploiting the quantum coherence of the DoDo pair • Rare and forbidden decays • Decay constants revisited Marina Artuso

  3. A glimpse into the world of new physics? } • Exploit quantum coherence of initial state at the y and gD0D0 • Study interference effects induced by strong phases (Dalitz plot analyses) • Mixing • CP violation Marina Artuso

  4. D0D0 mixing Experimental Situation (May/2001) Marina Artuso

  5. D0D0K+p- K+p- & rD • No rDCSD component because of quantum statistics • Sensitivity can be enhanced by adding other modes (such as K(*)+lnK(*)+ln). • Standard Model predictions quite uncertain. We will not span the full range of Standard Model predictions, but we may see “new physics driven”, possibly distinguishing x from y  UL(sqrt(rD))0.01 @95%CL Marina Artuso

  6. A COMPREHENSIVE MAPPING OF MIXING PARAMETERS - 1 hep-ph/0103110Gronau, Grossman & Rosner Comparison of CPeven and odd allows determination of cosd Linear in y Marina Artuso

  7. CP eigenstates Marina Artuso

  8. Phase d determination from C=-1 sample • We sum over all the CP eigenstates of a given sign to obtain =G(K-p+S+) • We can use MM technique to increase statistics • Expected accuracy in cosd is 0.05 Marina Artuso

  9. Lepton tagged samples 2 l - ~ l- l- l+ l+ l+ l+ CP even – CP odd asymmetries linear in y Marina Artuso

  10. CP Violation experimental search techniques • Direct CP violation in Ddecays • CP violation in the decay of a Do Do pair • CP violation in final state distributions (DVV) • Order of magnitude expected in Standard Model 10-3 • New physics can enhance CP asymmetries + in this scenario they can emerge in Cabibbo allowed modes Marina Artuso

  11. CP violation in charm decays • Present experimental data: • FOCUSAcp(D+K-K+p+)=-0.0010.0220.015, • FOCUS result Acp(K+K-)=-0.0010.022 0.015 • CLEO Acp(D0K-K+)=+0.050.02180.0084 • CLEO-C error 0.01 with 3 fb-1 with a variety of techniques. In some measurements b-factories are very competitive Marina Artuso

  12. CP asymmetries from flavor tagged decays • Necessary ingredients: • Flavor tag (lepton/kaon) • CP eigenstate • Obtain acp, for example: Marina Artuso

  13. dAcp with flavor tagged CP eigenstates Marina Artuso

  14. Mode dAcp(Lint=3 fb-1) SM predictions D+p+h 0.008 O(10-3) D+p+f 0.007 O(10-3) D+K+K*0 0.009 O(10-3) dAcp sensitivities • Self tagging modes (D+, Ds) Marina Artuso

  15. y(3770)DoDo f+ f+ or f- f-(f+=K+K-,p+p-,Ksh..) • A single background free event  CP violation • We can increase statistics x3-4 using MM technique discussed before Marina Artuso

  16. CP violation studies in the Dalitz Plot High statistics background free DalitzPlot analyses may turn out to be the most sensitive probes of CP violation in D decays Not only “Beyond SM”, also QCD etc.. Marina Artuso

  17. Rare and forbidden decays • Some D decays are forbidden: Standard Model expectations are several order of magnitude below any experimental reach laboratory for “Standard Model background free” searches for new physics • the charm threshold region has the advantage of high efficiency and low background both for charged particle final states and final states including g and po. • Sensitivities to branching fractions O(10-6) expected Marina Artuso

  18. Leptonic Decays: D l+n Introduction: Pseudoscalar decay constants Q and q can annihilate probability is  to wave function overlap Example p-: _ In general for all pseudoscalars: Marina Artuso

  19. fD and new physics We can probe violation of m-t universality Effect can be a few % with new physics 2HDM prediction Marina Artuso

  20. Summary on decay constant reach Marina Artuso

  21. Conclusions • CLEO-c can probe for physics beyond the Standard model with 4 different strategies • Mixing studies • CP violation studies • Rare decays • Precision decay constant measurements • Phenomenology is very rich, some measurements unique (quantum coherence of initial state) • Search for signatures of physics beyond the Standard Model in charm is very important and our studies will be complemented by other experiments (BaBar, BELLE, BTeV…) Marina Artuso

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