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

7

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

9

~ 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

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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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