Post on 03-Jan-2016
description
A. OyangurenA. Oyanguren
EPS 2003, AachenEPS 2003, Aachen
( IFIC -Valencia)( IFIC -Valencia)
IntroductionIntroduction
EPS 2003, AachenEPS 2003, Aachen A. OyangurenA. Oyanguren1
VVcbcb
q2
ccbb
Inclusive
Exclusive
Need lifetime measurements
Exclusive measurement limited by theory
Inclusive measurement analyzed using OPE
Study of moments
Study of form factors
sl =
IntroductionIntroduction
EPS 2003, AachenEPS 2003, Aachen A. OyangurenA. Oyanguren
-
D0B0
3mm
*+D*++
+
-
K-
bb / hadrons 22%
EB 0.7 Ebeam 30 GeV
D0
B semileptonic decays @ DELPHI:
B
Z Z qqqq
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EPS 2003, AachenEPS 2003, Aachen A. OyangurenA. Oyanguren3
LifetimesLifetimes
NN based
b-vertex D-vertex Int. point
Inclusive lifetime measurement:
World average:
b = 1.570 0.005stat. 0.008sys. ps
EPS 2003, AachenEPS 2003, Aachen A. OyangurenA. Oyanguren4
B+/B0 lifetimes:
B+ = 1.624 0.014stat. 0.018sys. ps
B0 = 1.531 0.021stat. 0.031sys. ps
B+/B0 = 1.060 0.021stat . 0.024sys. ps
LifetimesLifetimes
EPS 2003, AachenEPS 2003, Aachen A. OyangurenA. Oyanguren
|V|Vcbcb| (exclusive)| (exclusive)
From decays :
Known function(Phase space)
Form factor for B D* Normalized by HQET (mQ ) at q2
max (w = 1)
Finite mQ and QCD corrections FD*(1)=1
FD*(1)= 0.91 0.04
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EPS 2003, AachenEPS 2003, Aachen A. OyangurenA. Oyanguren
BBdd D* D*++
--
DD0 0 softsoft
D* - epton candidates:
00
K-+
K-++-
K-+(0)
DELPHI PLB510 (’01) 55
&
6
|Vcb| = 41.4 (1 ± 0.029expt. ± 0.051syst. ± 0.043theo. ) 10-3
DELPHI DELPHI averageaverage
FD*(1)
F(1)|Vcb| = (37.7 1.1 1.9) 10-3
2 = 1.39 0.10 0.33BR = (5.39 0.11 0.33)%
|V|Vcbcb| (exclusive)| (exclusive)
EPS 2003, AachenEPS 2003, Aachen A. OyangurenA. Oyanguren
Form factorsForm factors
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b form factor:0
pK-+
++-
pKs0
EPS 2003, AachenEPS 2003, Aachen A. OyangurenA. Oyanguren
sl =|Vcb|2
mmbb, m, mcc
Kinetic energy of the Kinetic energy of the bb inside the meson inside the meson
GG= = chromo-magnetic coupling chromo-magnetic coupling (M(MB*B*-M-MBB))
D D ,, LSLS
, , GG22 22DD ,, LSLS
3333
To be measured!
O.P.E.
Theory:Theory:
33
33
22
22
8
From inclusive decays : sl=(0.434 0.008)×10-10 MeV
|V|Vcbcb| (inclusive)| (inclusive)
EPS 2003, AachenEPS 2003, Aachen A. OyangurenA. Oyanguren
Signal:
Moments of the hadronic mass
Included info discriminant variableIncluded possible D**D decaysFurther studies on systematics
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~ 2.1%B D- D*- D**- +
~ 10.5 %
~ 5.5%
Hadronic Hadronic moments moments
D**D*+ -
From D**D(*)
EPS 2003, AachenEPS 2003, Aachen A. OyangurenA. Oyanguren
Hadronic Hadronic moments moments
<m<mnnHH>= p>= pDD m mnn
DD +p +pD*D* m mnnD*D* + (1-p + (1-pDD-p-pD* D* ) <m) <mnn
D**D**>>
Moments of the hadronic mass
Moments of the lepton energy spectrum(DELPHI 2002-070-CONF-604)
10
Measured
M1= <m2H - m2
D> = 0.647±0.046±0.093 (GeV/c2)2
M2= <(m2H - m2
D)2> =1.98±0.23±0.29 (GeV/c2)4
M2’=<(m2H- <m2
H>)2>=1.56±0.18±0.17 (GeV/c2)4
M3’=<(m2H- <m2
H>)3>=4.05±0.74±0.31 (GeV/c2)6
EPS 2003, AachenEPS 2003, Aachen A. OyangurenA. Oyanguren
Constraints on mb and mc:
mb = 4.57 0.10 GeVmc = 1.05 0.30 GeV
|Vcb| = 42.4 (1 ± 0.015expt. ± 0.019fit. ± 0.010theo. ) 10-3
4-parameter fit
s (mb/2, 2mb)
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mb (1GeV) = 4.56 0.15 GeV
mb(mb) = 4.21 0.14 GeV
Unconstrained masses:
kin
kin
kin
(MS)
Hadronic Hadronic moments moments
mb (1GeV) = 4.570 0.082 0.010 0.005 GeV
mc (1GeV) = 1.133 0.134 0.019 0.020 GeV
= 0.382 0.070 0.031 0.020 GeV2
D = 0.089 0.039 0.004 0.010 GeV3
2
3
kin
kin
mb, mc, , D, G, LS2 2 33LEPb,
Value error fit sys. mom. sys. theo.
And fixing:
G= 0.35 0.05 GeV2
LS= - 0.15 0.15 GeV3
2
3
EPS 2003, AachenEPS 2003, Aachen A. OyangurenA. Oyanguren
SummarySummary
Measurement of |Vcb| from
Measurement of moments
Determination of OPE parameters
Precise |Vcb| from inclusive decays
Most accurate value of b
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EPS 2003, AachenEPS 2003, Aachen A. OyangurenA. Oyanguren
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