1 Charm Semileptonic Decay • The importance of charm SL decay • Pseudoscalar l decay • Vector l decay – Analysis of DK*– The V/PS enigma: (D+K*/ K– The D s form factor enigma • The future of SL decay – Cleo-c / Bes III (3770) running Jim Wiss Univ of Illinois HQL2004 June 2 , 2004 Apologies for all the important and fascinating results that I had to skip Featuring results from
Charm Semileptonic Decay. Jim Wiss Univ of Illinois HQL2004 June 2 , 2004. The importance of charm SL decay Pseudoscalar l n decay Vector l n decay Analysis of D K* mn The V/PS enigma : G (D+ K* mn / K mn) The D s fmn form factor enigma The future of SL decay - PowerPoint PPT Presentation
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1
Charm Semileptonic Decay
• The importance of charm SL decay• Pseudoscalar l decay• Vector l decay
– Analysis of DK*– The V/PS enigma: (D+K* / K– The Dsform factor enigma
• The future of SL decay– Cleo-c / Bes III (3770) running
Jim Wiss Univ of IllinoisHQL2004June 2 , 2004
Apologies for all the important and fascinating results that I had to skip
Featuring results from
2
Charm semileptonic decay as tests of LQCD
Apart from form factors, these decays can be computed using perturbation theory and are first order in CKM elements
The form factors incorporate hadronic complications and can be calculated via non-perturbative Lattice QCD.
(*)KD
c W l
q
scsV
Charm SL decays provide a high quality lattice calibration crucial to reducing future systematic error in the Unitarity Triangle. The same techniques validated in charm can be applied to beauty.
3
Pseudoscalar l decays
22 3
2 3
22 2
2(
4( ) )
F cq P
lf q O mG V Pd D P
dq
Provides a way to either measure CKM elements or to verify f+(q2) calculations
...But a major disconnect exists between experiment and theory. Theory works best where experiment works worse.
0 0.5 1 1.5 2 2.5 3
3P
2q
cleanest theory
highest rate
D l
2 2pole
1f
q m
2expf q ISGW
Two forms are used to parameterize f+(q2)
pole
These should be among the first unquenched lattice calculations... is easiest for LQCD
c
q
2max
2 qq s
q
l
lattice daughtera Kaon at rest in D frame
4
Comparing pole versus ISGW form in De
De should provide a powerful test of future lattice predictions
dp
dLattice
hep-ph/0101023
better sys as P0
Unfortunately present LGT offers very little discrimination between the two common forms
dp
d
P (GeV)
2q
22f q
...where differences are dramatic.e decay gets quite
close to the D* pole...
2 2 ( )q GeV
But past esignals have severe backgrounds and poor q2 resolution. Thus requiring parameterizations.
The lattice can now calculate f+ as a function of q2.
5
De/Ke
(0)0.86 0.07 0.05
(00.01
)K
f
f
Consistent w/ SU(3) breaking
32
2
2
2
2
324( )
F cq P
d D P
dq
G Pf
Vq
•Look for D*D decays. The “signal” is in the m plot.
•3 bins in q2 to get form factor info.
•Include peaking and non peaking backgrounds
0.082 .006 0.005 CLEOe
Ke
A big advance in precision!
Kl l
6
q2 information in De/Ke
MK
3
E691
Cleo
91
Cleo
93
E687 tag
E687 in
c
Cleo
04
1.4
1.6
1.8
2.0
2.2
2.4
2.6
Ke
nu
po
le m
as
s
The Cleo 04 epole mass is
After correcting for smearing Cleo reports these corrected q2 fractions
e
Ke
Clearly the data does not favor the simple Ds* pole
1.90 0.05
Disfavors ISGW2 form by ~4.2
7
Dvector decays
H0(q2), H+(q2), H-(q2) are helicity-basis form factors computable by LQCD...