Transcript No Slide Title

Fully leptonic and semileptonic decay
Jim Wiss
University of Illinois
CLEO-c and BESIII
Joint workshop on
charm, QCD and tau physics
Jan. 13-15, 2004 in Beijing, China
Acknowledgements and Full Disclosure
1. This talk is from the perspective of a brand new CLEO-c member
2. It borrows very heavily from an excellent longer talk of Ian Shipsey
3. I have worked on semileptonic decays from the Fermilab FOCUS
(fixed target) experiment with vastly different systematics and very
complementary techniques.
Allowed transition
BESIII-Cleo-c workshop J. Wiss
1
Hi impact leptonic and semileptonic physics
D+ mn
D0 pln
Vub / Vcb


Vtd / Vts


An impressive check of the
unitarity triangle.
BESIII-Cleo-c workshop J. Wiss
The most uncertain CKM
elements are |Vtd|and |Vub|.
Both uncertainties are dominated
by systematics on calculating
hadronic effects that can be
significantly reduced by
calibrating LQCD on related
charm decays.
2
D meson Decay Constants
|VCKM|2
|fD|2
In a pseudoscalar D meson decay:
c and q annihilate
Helicity

n
suppression
2
m

2
2
2
2

1
( Dq   )  8p GF M D m (1  2 ) f D | Vcq |
q
M D
B(D+ln)/
D+ : fD+|Vcd|
Q

VQq
M
B(DS ln)/ Ds : fDs|Vcs|


s
D ,D ,B
W*


q
* Charm meson lifetimes known 0.3-2%
* 3 generation unitarity
Vcs, (Vcd) known to 0.1% (1.1%)  fD+ fDs
BESIII-Cleo-c workshop J. Wiss
3
Improving knowledge Vtd using D+mn
 BB f B
d
d
1
M d  0.50 ps 
 200 MeV



2
 Vtd


3 
8
.
8

10


2
 (M d )  ( f B BB )
 ()
 0.5


M d
f B BB
d

d
1.2%
~15% (LQCD)
(ICHEP02)
f D
fD
 2.3%
Vub / Vcb 

Lattice predicts fB/fD with small errors
precision measurement of fD
precision estimates of fB
precision determination of Vtd
BESIII-Cleo-c workshop J. Wiss
Vtd / Vts


4
D meson Decay Constants Current Status
fDs Values from Dsm
Common systematic
error from B(Dsp)
fD+ < 290 MeV @ 90% CL
(Mark III)
Estimated BR using
fDs=260 fD=220 fB=200 MeV
B(mn)
B(n)
4.210-4
1.110-3
DS+ 5.710-3
5.510-2
3.210-7
7.110-5
D+
B+
BESIII-Cleo-c workshop J. Wiss
14% relative error
5
fD+ from Absolute Br(D+  mn)
MC
D+ mn
• Fully reconstruct
one D (tag)
• Require one
additional charged
track and no
additional photons
BESIII-Cleo-c workshop J. Wiss
Huge
improvement
over existing
knowledge!
mf Ds
f Ds
mf D+
PDG
3fb-1
17%
33%
UL
1.9%
1.6%
2.3%
6
Probing the hadronic current
W
b
l

Vub / Vcb 


c
B
D (*)
q
l
W
c
Vtd / Vts


q


c
D
K (*)
q
W
D f q2
( )
BESIII-Cleo-c workshop J. Wiss

l


K
q
D  Kln : f  ( q 2 ) and ml2  f  ( q 2 )


D  K * ln : A1 ( q 2 ) , A2 ( q 2 ) ,V ( q 2 )
7
Exclusive Charm Semileptonic Signal Yields in 3 fb-1
B(%)
Detection
“efficiency”
N Detected
Xen
K-e+n
3.47
46%
K*-e+n
2.02
p-e+n
-e+n
D0 Modes
NDetected
Xen + Tag
CKM
559,500
77,670
Vcs
12%
28,200
3,900
Vcs
0.37
63%
81,000
11,190
Vcd
0.20
23%
15,600
2,190
Vcd
K0S e+n
3.40
37%
219,000
16,560
Vcs
K*0e+n
4.65
19%
151,500
11,250*
Vcs
p0e+n
0.31
44%
34,500
2,580
Vcd
0e+n
0.25
38%
24,000
1,770
Vcd
tagging
fraction
14%
yellow
book
yields
with 3 fb-1
D+ Modes
7.5%
*Focus
K*mn FF
sample
The BESIII yields are likely to be 5 to 10 times larger!
BESIII-Cleo-c workshop J. Wiss
8
Improvements in charm semileptonic branching ratios
from 3 fb-1
List of
Modes
PDG(2000)
B (%)
PDG(2000)
B/B (%)
(3fb-1)
B/B (%)
D0K-e+n
3.47  0.17
4.9
0.36
D0K*-e+n
2.02  0.33
16.3
1.60
D0p-e+n
0.37  0.06
16.2
0.95
D0-e+n
-
-
2.14
D+K0e+n
6.7  0.9
13.4
0.63
D+K*0e+n
4.7  0.4
9.4
0.94
D+p0e+n
0.31  0.15
48.4
1.97
D+0e+n
0.22  0.08
36.4
2.38
Threshold running can dramatically improve on the PDG value of dB/B
for every D+ and D0 semileptonic branching ratio.
BESIII-Cleo-c workshop J. Wiss
9
Importance of absolute charm
semileptonic decay rates.
G
d
2 3
2 2
2

|V
|
p
|f
(q
)|

m
Qq
daughter 
l (
2
3
dq 24p
2
F
|VCKM|2
)
|f(q2)|2
I. Absolute magnitude & shape of form factors are a stringent test of theory.
II. Absolute charm semileptonic rate gives direct measurements of Vcd and Vcs.
III Key input to precise Vub vital CKM cross check of sin2
B
B
B
~ 25%
D
b
c
u
d
p ln
p ln
1) Measure Dp form factor in Dpln. Calibrate LQCD uncertainties .
2) Extract Vub at BaBar/Belle using calibrated LQCD calc. of Bp form factor.
3) But: need absolute Br(D pln) and high quality f(q2) data and neither exist
BESIII-Cleo-c workshop J. Wiss
10
f(q2) models of the past
A major disconnect between experiment
and theory afflicts published data
2
q 2  qmax
is easiest for LQCD
c
l
n
s
daughter
alattice
d ( D  P n )
dq
2
P3

2
2
F
G Vcq PP3
24p
D  p ln
3
2
f  (q )
0.5
1
BESIII-Cleo-c workshop J. Wiss
1.5
2
2
f 
cleanest
theory
highest
rate
0
Previous data had low rates and
terrible q2 resolution which
required a parametric form for
meaningful measurement
q
q
An incisive test of LQCD requires
one to measure f(q2) where there is
still rate and compare in a
theoretically controlled q2 region
2.5
3
q
2
ISGW
1
2
q 2  mpole
f   exp ( q 2 )
11
Measuring q2 evolution
At present, K*ln data fits to the
pole form return poles slightly
lower than Ds*. But past studies
were compromised by poor q2
resolution and control of
backgrounds at low visible mass
and K*ln is not an optimal state...
pln probe q2 dependence nearly
up to the spectroscopic pole!
DK*ln
Signals at the
y (3770) will be
clean , copious,
and well resolved
in q2
BESIII-Cleo-c workshop J. Wiss
MC
“yellow
book”
1 fb-1
12
Pole versus ISGW form in Dpen
d
dpp
hep-ph/0101023
Lattice
better sys
The lattice can now calculate f+ as a function
of q2. Dpen provides a powerful test of the
lattice predictions. Once validated, the lattice
can be used with confidence in the extraction
of CKM matrix. for both B’s and D’s
f (q
16
14
2
)
2
pole
ISGW
12
10
8
6
4
2
d
dpp
MC
yellow
book
1 fb-1
BESIII-Cleo-c workshop J. Wiss
q 2 (GeV/c)2
0
0
0.5
1
1.5
2
2.5
3
3.5
d
dpp
Pp (GeV/c)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
13
Dvector l n decays
A 4-body decay requires 5
kinematic variables: Three
angles and two masses.
MKp MW2  q2
ìï
ïï
ic
ïï (1 + cos ql ) sin qV e H +
ï
1 2
2
2 ï
A = (q - m l ) í - (1 - cos ql ) sin qV e - i c H ïï
8
ïï - 2 sin ql cos qV H 0
ïï
îï
Two amplitude sums
over W polarization
left-handed m+
right-handed m+
Wigner D-matrices
sin ql sin qV e i c H +
2
+
- ic
m m2 + sin ql sin qV e H -
q 2 + 2 cos ql cos qV H 0
+ 2 cos qV H t
(“mass terms”)
2
ü
ïï
ïï
ïï
ïý
ïï
ïï
ïï
ï
þ
H0(q2), H+(q2), H-(q2) are helicity-basis form factors computable by LQCD
These evolve according to vector and axial pole forms
BESIII-Cleo-c workshop J. Wiss
14
( D  K *0 m n ) Form Factor Ratios
The H+ , H- , and H0 form factors are various combinations of vector and axial pole
forms which are parameterized as spectroscopic poles.
0.0
1.0
0.8
BESIII-Cleo-c workshop J. Wiss
0.6
0.4
0.2
0.0
-0.2
E653
E691
0.827  0.055
r2
E691
1.2
time
E653
1.4
0.5
E687
YB 1 fb-1 stat
1.0
E687
 rV / rV  2%
 r2 / r2  3%
E791
2.0
1.5
Although ratios of form factors are known
precisely, A1(0) , A2(0) and V(0) measurement
requires knowledge of (1) absolute BR (2)
charm lifetimes (3) reliance on q2 model
Nominal spectroscopic
pole masses
1.66  0.060
rV
E791
Focus sys+stat
2.5
BEAT
rv/ rv= 4.6%
r2/ r2 = 9.2%
3.0
BEAT
just 2 numbers
rv  V (0) A1 (0)
r2  A2 (0) A1 (0)
M A  2.5 GeV / c 2
MV  2.1 GeV / c 2
FOCUS
The intensity is
then described by
V (0)
V (q ) 
1  q 2 M 2V
2
FOCUS
Ai (0)
Ai (q ) 
1  q2 M 2 A
2
Latest LGT: Becirevic (ICHEP02)
RV = 1.55  0.11
15
Hadronic complications in K*l n
Yield
31,254
Data
MC
constant
s-wave
dG
µ 1 + a cos2 qV
dW
BESIII-Cleo-c workshop J. Wiss
The Kpln process consists of both
K* ln and an interfering, s-wave
component which creates a forwardbackward asymmetry in the K*
decay angle with a distinctive mass
variation.
16
Both good news and bad news
A very naive calculation
eventsCosV
|amp|2
Estimated errors
for a 31 000 event
sample
const amp
LASS amp
Phase (deg)
M(Kp)
Adds additional complications such as
amplitude and phase variation, an additional
helicity form factor etc.
But allows additional handles on the relevant
hadronic physics such as:
1. Studies of the I=1/2 s-wave phase variation
BESIII-Cleo-c workshop J. Wiss
2. Detailed studies of the K* line shape
17
Great to extend data to D ln
Kinematic
projections
from 1 fb-1
MC
1 Very clean
2 Great resolution
3 Good efficiency
MC
K* l n
ln
 en
K *e n

MC
It would very interesting to compare
form factors in  l n to K* l n and
search for s-wave interference in  l n
BESIII could study S-wave
interference in ln interference with
half the (tagged) statistics as used
in the Focus K*mn study
BESIII-Cleo-c workshop J. Wiss
MC
18
Enigma #1:  (DK*ln)
Form factor ratios were well
predicted but the scales were not.
circa 1993
Quark models predicted a
 ( D   K *o m n )  A1 (0)
2
 twice as high as older data.
The 2002 CLEO result tended
to resolve this discrepancy.
The 2002 FOCUS result tended
to reinstated it.
0.9
Cleo 2
(K*l n)/(Kpp)
0.8
Cleo 2
Omega
0.620.02
0.7
0.6
Focus
Cleo 1
0.5
E691
E687
0.4
muons
0.3
BESIII-Cleo-c workshop J. Wiss
E653
electrons
Argus
A1 follows from  (K*mn)
measured from K*ln/ Kpp
using the Kpp BF and D+
lifetime. This can then be
compared with LGT
prediction
19
2.0
2.5
2.0
2
E687
3
4
5
6
7
8
LMMS
1.0
9
0.5
BKS
LMMS
1
BKS
1.5
0
1
E687
3.0
CL (rV) = 44.3% CL(r2) = 21.5%
E653
0
1.5
0.5
CLEO
0.0
CLEO
ISGW2
E653
R2
CLEO
E687
2
circa 1999
E791
2.5
0.5
R2
E791
0
1.0
Focus
CLEO
0.5
3
E687
1
1.5
ISGW2
LMMS
1.5
ISGW2
2
BKS
2.5
LMMS
E653
E791
RV
3.0
Focus
ISGW2
2.5
BKS
E653
E791
3
RV
Enigma #2: Dsln form factors
0.0
0
1
2
3
4
5
6
7
8
9
It was anticipated that the form factor ratios for Dsln should be within
10% of those for D K*ln . Until just recently, it looked like rV values
were consistent but r2 for Dsln was  a factor of two higher than that
for D K*ln . The new Focus data (hep-ex/0401001) challenges this.
BESIII-Cleo-c workshop J. Wiss
20
Determining Vcs and Vcd
combine semileptonic and leptonic decays eliminating V CKM
(D+ pln) / (D+ ln) independent of Vcd
Test rate predictions at ~4%
(Dsln) / (Dsln) independent of Vcs
Test rate predictions at ~ 4.5%
Test amplitudes at 2%
Stringent test of theory!
I
If theory passes the test…..
D0  K e  Vcs /Vcs = 1.6% (now: 11%)
D0  p e Vcd /Vcd = 1.7% (now: 7%)
II Use CLEO-c validated lattice to calc. B semileptonic
form factor, then B factories can use B/p//lv for precise Vub
BESIII-Cleo-c workshop J. Wiss
21
Improving unconstrained CKM elements
(Snowmass E2 WG)
Without invoking powerful unitarity constraints, many
CKM elements are relatively poorly known.
PDG
CLEO-c
data and
LQCD
Vcd
Vcs
Vcb
Vub
Vtd
Vts
7%
11%
5%
25%
36%
39%
1.7% 1.6% 3%
5%
5%
5%
PDG
B Factory/Tevatron
Data & CLEO-c
With lattice validation from threshold e+erunning allows for much better unitarity tests
Lattice Validation
|Vcd|2 + |Vcs|2 + |Vcb|2 = 1 ??
CLEO –c: test to ~3%
(if theory D K/pln good to few %)
BESIII-Cleo-c workshop J. Wiss
22
Summary
•
Leptonic Decay
– Dramatic improvements in fDs and first measurements of fD+ at 2%
• Plays a crucial role in Vtd when combined with mixing
•
Pseudoscalar semileptonic decay
– Unparalleled cleanliness in f+ form factor measurement in D pln
• Remove reliance of f(q2) models to bridge theory and experiment
• Pole dominance and ISGW forms can be easily distinguished
• Provide clean calibration of f+ : Both value and q2 evolution predicted by LQCD
– Provides crucial calibration f+ to use B  pln to measure Vub
•
Vector semileptonic decay
– Improvement in rV and r2 parameters
– Unique advantages in determining A1(q2), A2(q2) , V(q2)
• q2 dependence for the first time
– Hadronic complications / opportunities due to s-wave interference
– Settle two long term experimental enigmas
• The K*ln/Kln problem
• The Ds  ln versus D+  K*ln r2 inconsistency
•
Direct measurements of Vcs , Vcd and incisive unitarity tests
BESIII-Cleo-c workshop J. Wiss
23
Interplay between semileptonic , leptonic
charm and improved beauty data and LQCD
• Crucial Validation of Lattice QCD: Lattice QCD will be able to calculate with
accuracies of 1-2%. The CLEO-c decay constant and semileptonic data will provide
a “golden,” & timely test.
B Factories
only ~2005
Imagine a world
Where we have
theoretical
mastery of nonperturbative QCD
at the 2% level
BESIII-Cleo-c workshop J. Wiss
Theory
errors = 2%
24
Question slides
?
?
BESIII-Cleo-c workshop J. Wiss
25
Inclusive Semileptonic Decays
 Currently SL of all D mesons are consistent with being equal:
 Threshold: the best place to measure inclusive semileptonic branching ratios
B%
PDG2000
B /B %
PDG2000
B / B(%)
CLEO-c (3fb-1)
D0e+X
6.80.3
4.4
0.8
D+e+X
17.21.9
11.0
0.8
DSe+X
8 5
63
1.7
Mode
(10-2ps-1)
/ (%)
Mode
/ (%)
CLEO-c (3fb-1)
D0e+X
16.40.7
4.4
1.4
D+e+X
16.41.8
11.0
1.1
DSe+X
16.110.1
62.7
2.8
Hadronic
tag
e
30 improvement !
HQE predicts the near equality of SL for D+, D0 and Ds but large 1/mc
corrections and duality violations are a concern. CLEO-c inclusive rate and
spectral shape provide precision test of 1/mc expansion
BESIII-Cleo-c workshop J. Wiss
26
CLEO-c Yellow Book Run Plan
Year 1 y(3770) – 3 fb-1
30 million DD events, 6 million tagged D decays
(310 times MARK III)
Year 2 S ~ 4140 MeV – 3 fb-1
1.5 million DsDs events, 0.3 million tagged Ds decays
(480 times MARK III, 130 times BES)
Year 3 y(3100), 1 fb-1 –1 Billion J/y decays
(170 times MARK III, 20 times BES II)
C
L
E
O
c
A 3 year
…and about to begin the year 1 program with 50 pb-1
program
@ y(3770) X5 Mark III with a state of the art detector that is
understood at a precision level, and has proven itself with
pioneering measurements of Vub, Vcb, & radiative penguins, discovery of the Y
D states and DsJ(2463) and many more.
BESIII-Cleo-c workshop J. Wiss
27
Unique Opportunities at Charm
Thresholds
y(3770)  DD
s ~4140  DsDs
(DoDo) = 5.8 nb
(D+D-) = 4.2 nb
(Ds Ds) = 0.5 nb
R (units of (m+m))
(m+m)= 5.4 nb at 4 GeV
BESIII-Cleo-c workshop J. Wiss
28
Decay constants are important in many processes
Q

VQq
fp
b
W
M
u
d
c
t
b
fB
u
u
fM
W


BESIII-Cleo-c workshop J. Wiss
W*
D  , Ds , B 
v
d
W
fB
b
t
q
u
d, s
q
W
d
W
t
Mb

fM

e
s

e
q
29
CKM Facts
sin 2  0.78  0.08
M D  0.489  0.008 ps
BESIII-Cleo-c workshop J. Wiss
30
Precision Quark Flavor Physics
Goal for the decade: high precision measurements of Vub, Vcb, Vts, Vtd,
Vcs, Vcd, & associated phases. Over-constrain the “Unitarity Triangles”
- Inconsistencies  New physics !
Vud/Vud 0.1%
CKM
Matrix
Current
Status:
e
n
n
p
Vcd/Vcd 7%
l
n
K
n
D
nNcm p
Vtd/Vtd =36%
D
p
l
n
Wcs
K
Vts/Vts 39%
Bd Bs
Vub/Vub 25%
l
B
Vcs/Vcs =16%
l
Bd
Vus/Vus =1%
Bs
n
p
Vcb/Vcb 5%
l
B
n
D
Vtb/Vtb 29%
t
W
b
Many experiments will contribute. Measurement of absolute charm branching ratios
At CLEO-c will enable precise new measurements at Bfactories/Tevatron to be
translated into greatly improved CKM precision.
BESIII-Cleo-c workshop J. Wiss
31
Charm Facilities
Future charm data sets
Experiment
Current
Full
K-p+
BABAR
91 fb-1
500 fb-1
6.6 x 106
Belle
46.2 fb –1
500 fb-1
6.6 x 106
CDF(Run II-a)
65 pb –1
2 fb-1
14 x 106
CLEO-c
-
3 fb-1
5.5 x 105
BESIII
-
30 fb-1
5.5 x 106
Super Charm
-
500 fb-1
9.2 x 108/ 107s
SuperKEKB
-
2 ab-1
2.5 x 107/ 107s
SuperBABAR
-
10 ab-1
1.3x 108/ 107s
BTeV
-
BESIII-Cleo-c workshop J. Wiss
~6 x 108/ 107s
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