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Physical Program of Tau-charm Factory

Physical Program of Tau-charm Factory. V.P.Druzhinin, Budker INP, Novosibirsk. Processes at tau-charm factory. . D s. D.    . Main topics. Physics of charmonia Light hadron spectroscopy Open charm hadrons Physics of -lepton. Current and future experiments.

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Physical Program of Tau-charm Factory

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  1. Physical Program of Tau-charm Factory V.P.Druzhinin, Budker INP, Novosibirsk

  2. Processes at tau-charm factory  Ds D 

  3. Main topics • Physics of charmonia • Light hadron spectroscopy • Open charm hadrons • Physics of -lepton

  4. Current and future experiments B-Factories produced about 1010 charmed hadrons and 109 -pairs

  5. Charmonium Vector states: J/  1012 (2S)  1011 (3770)  2109 Higher ’s  108 In decays: c(1S), cJ  1010 hc  108 ((2S)hc0) Comprehensive study of charmonium decays

  6. Charmonium states above open charm threshold • Recently observed new charmonium states: • C+: X(3872), X(3940), Y(3940) , Z(3930) • cJ(2P),c(3S) ? Study of radiative decays of (4040), (4160), (4415). • Search for hadronic transition X,Y,Z • 1--:X(4260),Y(4361),Y(4664) • (e+e- X)50 pb. • Scan of energy region 3.8-5 GeV with integrated luminosity 100 fb-1

  7. Rare J/ decay Number of J/’s  1012 • Weak decays: J/Ds(*)l, Ds*+-, Ds+ B(3-4)10-9 • SM for S=0 weak decays: J/D00, D00 B10-11. Probe for New Physics, FCNC cu transition. • ccss transition with W exchange: C-parity violation decay J/, B10-8 • Search for NP in Lepton Flavor Violation decays J/l+lB(--e+e- ) < 2.7 10-8 (5108  pairs)  B(J/+-)< (2-6)10-9 • CP-violation in J/ decays: 3 and more body decays to construct CP-odd observables or 2 body decays with polarization measurement, J/.

  8. Light meson spectroscopy • Low-lying charmonium states decay into light hadrons with relatively small multiplicity • Choosing specific cc-meson decay mode one can study states with practically any quantum numbers • Example: B(J/)=0.5% 5109 tagged  mesons. Recently CLEO performed precise measurement of  mass and observed decay  3. • Search for glueballs (gg) and hybrids (qqg)

  9. Search for glueballs and hybrids • Lattice QCD predicts glueball spectrum • Glueball states mix with ordinary mesons • Detailed study of the meson properties in different reactions and decay modes • Scalar glueball  (f0,a0,K0*) family • J/f0,f0,f0,a0, K*K0* • f0,a0 • For decays into PP,VP,VV,V • Lowest mass hybrid meson has exotic quantum numbers 1-+ • Its mass is expected in the range 1.3-2.2 GeV • Two possible candidates 1(1400), 1(1600) in N1N reaction • S-wave decay c11, P-wave decay J/1

  10. D-mesons Three types of D-mesons: D (cd), D0 (du), Ds (ds) Maximum cross section for D-pair production DJ states can be produced in reactions e+eD(*)DJ with 1 nb (4.3-5 GeV) Tau-charm factory can produce 6109 D-pairs and 109 Ds pairs per year. B-factories  1010 charmed hadrons

  11. Advantages of near threshold production • Particle multiplicity at 3.77 GeV is about two times lower than at 10.6 GeV • Two body production e+e-DD. This allows to use double tag method: • fully reconstruct one D • then either fully reconstruct the other D (absolute branching ratios) • or look for events with one missing particle (leptonic, semileptonic decays) • Coherent production of D pairs allows to use quantum correlations for D-meson mixing and CP violation studies

  12. Leptonic and semileptonic decays Measurement decay constants and form factors. Improve understanding of hadronization mechanisms. Validation of lattice QCD. With improved theoretical input  determination Vcs and Vcd. Important for B-physics  extracting Vub from semileptonic B decay. Current lattice values: fD=2074 MeV fDs=2413 MeV Experiment (CLEO): fD=2069 MeV fDs=2708 MeV Tau-charm factory can provide measurement of the decay constants with accuracy better than 0.5%.

  13. Semileptonic decays o.5% accuracy of BF 106 events

  14. D-mixing at tau-charm factory • Only time integrated measurements • Study of quantum correlations in e+e-D0D0(0) (C-odd) and e+e-D0D*0D0D0 (C-even) At (3770) RM=(x2+y2)/2 can be measured using the ratios For 109 D-pairs about 150 events will be detected. Sensitivity to RM is about 510-6

  15. D-mixing at C-tau factory Probabilities of inclusive decays are proportional to (1  y). S+ or S- are CP-even or CP-odd final states. For 109 D-pairs sensitivity for y is about 810-4 Fit of the inclusive and exclusive rates for decays of DDbar system into different final states allows to determine x, y, rf and f . Expected sensitivity to mixing parameters: 1 ab-1 at tau-charm factory = 10 ab-1 at Super B-factory

  16. Search for CP-violation Direct CP violation in D decays is expected to be small in SM. For CF and DCS decays direct CP violation requires New Physics. Exception: DKS,L with ACP=3.310-3. For Singly Cabibbo Suppressed (SCS) decays SM CPV could reach 10-3. Best limits: Belle: D0K+K-,+- ACP(K+K-)=(0.430.300.11)% ACP(+-)=(0.430.520.12)% At Tau-charm factory CP asymmetry can be tested with 10-3 sensitivity for many final states. CLEO: D+KS+, KS+0 ACP(KS+)=(-0.61.00.3)% ACP(KS+0)=(0.30.90.3)%

  17. Search for CP-violation CV violation in mixing: With 109 D-pairs about 30 (K+e-)(K+e-) events will be detected. |q/p| can be measured with 6% accuracy. Current value is 0.860.16 Use of quantum correlations: At (3770) : f1 and f2 are CP eigenstates of the same CP-parity. The decay D0D0f1f2 is forbidden by CP-invariance. The rate is proportional to difference CP-breaking parameters for f1 and f2. 109 D pairs  10-3 difference between +- and K+K- final states. Similar approach can be used for final states with different CP-parities in e+e- D0Do reaction.

  18. Search for CP-violation Using quantum correlations allows to separate contributions from direct CPV and CPV in mixing For C-odd D0D0 state CPV in mixing does not contribute to asymmetry, for C-even state it contributes with twice intensity. For multibody final states the analysis of Dalitz plots and T-odd moments distribution can increase sensitivity to CPV effects. Tau-charm factory can provide 10-3 sensitivity for CPV in D-decays

  19. Rare D decay • Flavor Changing Neutral Current (cul+l-) • D0+- SM ~10-12 NP - 10-6 • CDF B< 4.310-7 • DXul+l- SM ~10-6 NP - 10-6 • D0 B(D+++-)< 3.910-6 • CLEO B(D++e+e-)< 7.410-6 • Lepton Flavor Violation NP - 10-6 • BABAR B(D0 +e-) <0.81 10-6 • BABAR B(D++e+-) <1.1 10-5 C-tau factory can provide 10-8 sensitivity

  20. Rare D decay New physics can introduce new particles into loop B10-6 SM: short distance B(cull)~10-8 long distance B(Dll )10-6

  21. -physics • 1010-pairs • B-factories  109 • Super-B ~ 51010 • Special run near threshold • 2E=3.55 GeV, =0.1 nb, N=108 • ’s are produced at rest  kinematic constraint for hadronic decay  very clean data sample • Non- background measured below threshold

  22. Physical goals • High precision measurement BF and structure function for hadronic decays • e///K  lepton universality • s • ms,Vus • Study of Lorentz structure of leptonic decay • Lepton energy spectrum  4 Michel parameters, two depend on  polarization • Polarized initial beam • Measured via decay of second : 

  23. LFV decays Super-B, 75 ab-1 71010 -pairs •  decay • Current best limit: • 4.510-8 by Belle with 5108  • At Y(4S): • ISR background from e+e-+- • Upper Limit  1/L • tau-charm factory with 1010  has similar or better sensitivity

  24. Search of CP-violation in  decays • CP-violation  new physics, charged Higgs • Two amplitudes with different weak and strong phases • -KS-, ACP=310-3 • -K-0 • Observables • Rate asymmetry: (+f+)-(-f)~sin sin • Modified rate asymmetry ~sin sin • Triple product asymmetry (p1p2)~cos sin • For complete description of matrix element , polarization and direction of  should be known • Threshold production – low statistics • Polarization may increase sensitivity by several times

  25. Polarization • Michel parameters • CP-violation in -decays • Increase sensitivity by several times ? • Decrease luminosity ?

  26. Tau-charm physics • Charm • Spectroscopy • (Semi)leptonic decays • Rare decays • Mixing • CP violaton • … • Charmonia • Spectroscopy, BFs • Light hadron spectroscopy • J/ rare decays • … • Tau • Spectral functions, BFs • Lorentz structure • CP violation • LFV decays • … • Charm baryons • BFs • Semileptonic decays • …

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