physical program of tau-charm factory
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
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Physical Program of Tau-charm FactoryV.P.Druzhinin,Budker INP, Novosibirsk
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Processes at tau-charm factory)μμeσ(e
hadrons)eσ(eR
DD DD ss DD
ss DD cc
cc
D Ds
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Main topics
Physics of charmonia Light hadron spectroscopy Open charm hadrons Physics of -lepton
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Current and future experiments
CLEO-C BES-III/ year
-charm/year
J/ 10109
100(2S) 54 pb-1 27106 3109
(3770)
818 pb-1
5106 D-pair
3107
4.17 GeV
586 pb-1
7105 Ds-pair
2106
+ 4106 2107 B-Factories produced about 1010 charmed hadrons and 109 -pairs
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CharmoniumVector states:J/ 1012
(2S) 1011
(3770) 2109
Higher ’s 108
In decays:c(1S), cJ 1010
hc 108 ((2S)hc0)
Comprehensive study of charmonium decays
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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
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Rare J/ decayNumber of J/’s 1012
Weak decays: J/Ds(*)l, Ds
*+-, Ds+ B(3-4)10-9
SM for S=0 weak decays: J/D00, D00 B10-11. Probe for New Physics, FCNC cu transition. ccss transition with W exchange: C-parity violation decay J/, B10-8
Search for NP in Lepton Flavor Violation decays J/l+l B(--e+e- ) < 2.7 10-8 (5108 pairs) B(J/+-)< (2-6)10-9
o CP-violation in J/ decays: 3 and more body decays to construct CP-odd observables or 2 body decays with polarization measurement, J/.
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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% 5109 tagged mesons. Recently CLEO performed precise measurement of mass and observed decay 3.• Search for glueballs (gg) and hybrids (qqg)
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Search for glueballs and hybrids
oLattice QCD predicts glueball spectrumo Glueball states mix with ordinary mesonsoDetailed 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 GeVTwo possible candidates 1(1400), 1(1600) in N1
N reactionS-wave decay c11, P-wave decay J/1
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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+eD(*)DJ
with 1 nb (4.3-5 GeV) Tau-charm factory can produce 6109 D-pairs and 109 Ds pairs per year. B-factories 1010 charmed hadrons
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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
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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=2074 MeVfDs=2413 MeV
Experiment (CLEO):fD=2069 MeVfDs=2708 MeV
Tau-charm factory can provide measurement of the decay constants with accuracy better than 0.5%.
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Semileptonic decays
o.5% accuracy of BF 106 events
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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*0D0D0 (C-even)
)])(([
)])(([
)])(([
)])(([00
00
00
00
,
eKeKDDN
eKeKDDN
KKDDN
KKDDN
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 510-6
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D-mixing at C-tau factoryProbabilities of inclusive decays are proportional to (1 y). S+ or S- are CP-even or CP-odd final states.
XSDD 00
);();();();(
);();();();(
41
SXSl
SXSlSXSlSXSly
For 109 D-pairs sensitivity for y is about 810-4
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
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Search for CP-violationDirect CP violation in D decays is expected to be small in SM.
For CF and DCS decays direct CP violation requires New Physics.Exception: DKS,L with ACP=3.310-3.
For Singly Cabibbo Suppressed (SCS) decays SM CPV could reach 10-3.
)()(
)()(
fDfD
fDfDCPA
Best limits:
Belle: D0K+K-,+-
ACP(K+K-)=(0.430.300.11)%ACP(+-)=(0.430.520.12)%
CLEO: D+KS+, KS+0
ACP(KS+)=(-0.61.00.3)%ACP(KS+0)=(0.30.90.3)%
At Tau-charm factory CP asymmetry can be tested with 10-3 sensitivity for many final states.
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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 0.860.16
Use of quantum correlations:At (3770) : f1 and f2 are CP eigenstates of the same CP-parity.The decay D0D0f1f2 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 ine+e- D0Do reaction.
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Search for CP-violation
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
Using quantum correlations allows to separate contributions from direct CPV and CPV in mixing
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Rare D decay•Flavor Changing Neutral Current (cu l+l-)
•D0+- SM ~10-12 NP - 10-6 • CDF B< 4.310-7
•DXul+l- SM ~10-6 NP - 10-6 •D0 B(D+++-)< 3.910-6
•CLEO B(D++e+e-)< 7.410-6
•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
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Rare D decay
SM: short distance B(cull)~10-8 long distance
B(Dll )10-6
New physics can introduce new particles into loop B10-6
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-physics
•1010 -pairs ▫B-factories 109
▫Super-B ~ 51010
•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
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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 :
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LFV decaysSuper-B, 75 ab-1
71010 -pairs • decay •Current best limit:
4.510-8 by Belle with 5108
•At Y(4S): ISR background from e+e-+-Upper Limit 1/L
• tau-charm factory with 1010 has similar or better sensitivity
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Search of CP-violation in decays • CP-violation new physics, charged Higgs• Two amplitudes with different weak and strong phases • -KS-, ACP=310-3
• -K-0• Observables
▫ Rate asymmetry: (+f+)-(-f)~sin sin▫ Modified rate asymmetry ~sin sin▫ Triple product asymmetry (p1p2)~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
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Polarization
•Michel parameters•CP-violation in -decays
▫Increase sensitivity by several times ?▫Decrease luminosity ?
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Tau-charm physics
CharmoniaSpectroscopy, BFsLight hadron spectroscopyJ/ rare decays…
CharmSpectroscopy(Semi)leptonic decaysRare decaysMixingCP violaton…
TauSpectral functions, BFsLorentz structureCP violationLFV decays…
Charm baryonsBFsSemileptonic decays…