Physics of the Charm QuarkWayne State University Physics

Physics of the Charm QuarkGene GolowichPhysics DepartmentUniv. of MassachusettsAmherst MAColloquiumWayne State Univ. September 22, 2005Rough Outline•Some Background Comments•Some Standard Model•Some New Physics‘Coals to Newcastle’•ExperimentCLEO: Bonvicini, Cinabro, Dubrovin CDF: Harr, Karchin •TheoryPetrov, Gabbiani, AlFikyDiscovery of CharmAge: c-quark will turn 31 on 11/11Birth: East Coast (BNL) West Coast (SLAC)SLAC Method:Narrow resonance at E = 3.1 GeV!Thereafter called the `J/ ’The Standard ModelNuTeV Anomaly?Three Years of TestsSpectrum of Quark MassesPredict this Spectrum: Easy/Hard?Quark Masses and Theory•Predict quark masses? No viable models exist•What about String Theory? String ground state huge! `Landscape’ description. Many-universes scenario. Elementary constants random! Lucky us! We EXIST!!•What about mc = 1.3 GeV? Difficult theoretically. Not heavy enough! Not light enough! Complications of QCD QED vs QCDQEDQCDProgress in Lattice QCDStandard Model Physics•D Meson Ground State• The spectator c-quark: Bc Mesons•D Decays: Leptonic, Semileptonic, Nonleptonic •Spectroscopy: Exotic states?D Meson Ground State Predict the States: Easy/Hard?D Meson Ground State q = u  D0 q = d  D+ q = s  Ds+Easy! 3* of SU(3)Flavored MesonsEach quark has its own ‘flavor’Quark composites are ‘flavored’s-quark: K’s = c-quark: D’s = b-quark: B’s = The t-quark decays too quickly!Bc Mesons!Leptonic Decay of D+Decay Amplitude:Decay Constant fD:Non-perturbative efect.Requires Lattice QCD! fD: Theory vs ExperimentSemileptonic DecaysDecay Amplitude:D0  K e+  eForm Factor SlopesNonleptonic DecaysDecay Amplitude:A = a ei Dalitz StudiesPhase InformationMore DalitzComparative LifetimesB: B- = b B0 = d  -/ 0 = 0.92 Comparative LifetimesB: B- = b B0 = d  -/ 0 = 0.92D: D0 = c D+ = c  -/ 0 = 2.55Comparative LifetimesB: B- = b B0 = d  -/ 0 = 0.92D: D0 = D+ =  -/ 0 = 2.55K: K- = K0 = -/ 0 = 139.Charm Productione+e- collisions produce charm.There are predictions for this.Not all data are understood!Heavy Meson SpectroscopyX(3872) Sighting Is X(3872) a Molecule? AlFiky, Gabbiani, Petrov (2005) [plus others]Interpret X(3872) as a bound state of hadrons ( )Analogous to the Deuteron!Similar molecular state predicted long ago.Beware: other interpretations possible. Y(3940) 2/d.o.f. = 15.6/8stat. sig. = 8.1 Øabove D*D thresholdØ not found in DD or D*D final statesIs Y(3940) a ‘Hybrid’?Hybrid Meson : Color-octet quark-antiquark couples to color-octet gluon to yield color-singlet hadron D0  K-  +Where are CP Violations?New Physics and Charm•Methodology?•Rare Decays of D Mesons•Flavor Oscillations•CP Violations (not discussed here)MethodologyHow to find ‘New Physics’?Study systems where SM signals are small. Ideal forcharm:A] Rare Decays B] Flavor OscillationsD0   +  - in the SMData and D0   +  -D0   0 e+ e-Flavor Oscillations Mixing Mixing also in K0,Bd and Bs.Each of these is different! Two Coupled PenduliThe ‘Spring’New Physics and MixingThe Normal ModesNormal ModesEffect of CP:CPEigenstatesMixing of Bd MesonsMixing of Bs MesonsMixing of K MesonsMixing of D0 MesonsRecent Work on D0 Mixing Theory:Effect of QCD incorporated intoanalysis of D0 mixing by Golowichand Petrov. Work continues.Experiment;Especially interesting are attemptsto measure D at the 1% level. Summary I•The c-quark is a remarkably spry 31 year old!•A very active social life: Spectroscopy Flavor oscillations Rare decays CP violation searches•After studies at CDF, CLEO, Belle and BaBar will come the long awaited LHC. Summary II•Flavor mixing of D mesons will be a hot topic for both experimenters and theorists.•Exotic charm states (hybrid and/or molecular) will continue to attract much attention.。