a. oyanguren ph.d. thesis
DESCRIPTION
A. Oyanguren Ph.D. thesis. 26/03/2004. Contents. Introduction. Theory. The DELPHI experiment. Analysed data samples. |V cb | from. Eur. Phys. J. C33 (2004) 213. Phys.Lett. B556 (2003) 41 DELPHI Paper 340/draft 1. |V cb | from inclusive decays. Summary and Conclusions. Contents. 2. - PowerPoint PPT PresentationTRANSCRIPT
A. OyangurenA. Oyanguren
Ph.D. thesis.Ph.D. thesis.
26/03/2004
Theory Theory
Introduction Introduction
|V|Vcbcb| from| from
Analysed data samplesAnalysed data samples
The DELPHI experimentThe DELPHI experiment
|V|Vcbcb| from inclusive decays | from inclusive decays
Summary and Conclusions Summary and Conclusions
ContentsContents
Contents 2
Eur. Phys. J. C33 (2004) 213
Phys.Lett. B556 (2003) 41DELPHI Paper 340/draft 1
The CKM matrixThe CKM matrix
Introduction
VVcbcb
q2
ccbb
Vud Vus Vub
Vcd Vcs Vcb
Vtd Vts Vtb
CKM =
3
VVcbcb is a fundamental parameter of the is a fundamental parameter of the SMSM
From tree level From tree level processesprocesses
=sinC 0.22DeterminesDetermines AA
, A, , A, , ,
PDG PDG ’02’02
5%5% accuracyaccuracy
Measurement of |VMeasurement of |Vcbcb||
Introduction 4
by means of:by means of:
Exclusive processes
Inclusive processes
Theory 5
Heavy quark expansionsHeavy quark expansions
Heavy Quark Effective Theory (HQET)
Operator Product Expansion (OPE)
Inclusive decays:
Exclusive decays:
sl sl = = |V|Vcbcb||22 f f (theory)(theory)
Decoupling of heavy quark spin Decoupling of heavy quark spin (doublets)(doublets)Universal form factorsUniversal form factors
F(qF(q22maxmax)=1)=1
Non perturbative corrections in inverse powers Non perturbative corrections in inverse powers of mof mbbExpected small ( Expected small ( no term 1/mno term 1/mbb ))
DELPHIDELPHI
The DELPHI experiment
6
RICH
TPC
ToFmagnet
ID
HPC
Muon chambers HCAL
OD
VD
B decays B decays @@ DELPHI DELPHI
7
HPC + muon chambers
bb / hadrons 22%
EB 0.7 Ebeam 30 GeV
3mm
D0
-
B0
Fragmentationparticles
Other B
+D*+ K-
+RICH
Tracking(VD)
Missing energy
Analysed data samples
Z → qq 3.4 M
c 3mm
Event reconstructionEvent reconstruction
8Analysed data samples
Exclusive reconstruction:Exclusive reconstruction:
9|Vcb| from
|V|Vcbcb| from | from
Known function (Phase space)
Form factor of the B D* transition Normalized by HQET (mQ ) at q2
max (w= 1) (1/ mQ )n and QCD corrections
FD*(1)=1
FD*(1)= 0.91 0.04 *
* PDG ‘02
From the s.l. decay width:From the s.l. decay width:
D*D*
Selected candidatesSelected candidates
10|Vcb| from
D0 K-+ D0 K- + - + D0 K-+(0)
D*D*++ - - -- candidates candidates 1688 48
m= m(D0) -m(D0) ~ m(soft)DD0 0 softsoft
B B D* D* --
qq2 2 measurementmeasurement
11|Vcb| from
Measured
From missing energy
E, p conservation
, vertex info...
From decay products
Efficiency (q2):
q2 resolution:
(q2s) = (0.9850.026) + (0.00240.0043)q2
s
Sample compositionSample composition
12|Vcb| from
• Combinatorial background
• b D**-
D*+X
• b D*+DX- Y
• Z cc
• Events with fake leptons
• b D*+ -X
- Y
Real or fake D*+ candidates can come, apart from signal Bd→D*+
- events, from :
Main source of background
m distribution
Discriminant variables based on the event
topology
QX< 0
QX= 0
Isospin
2313
(Cascade)
(d±)
FitFit
13|Vcb| from
Event by event Event by event likelihood:likelihood:
d+d-
dN
dq2 |Vcb|2 F2(w) K(w) eff(q2)
res(q2)
F(w) as function of other form factors: R1 and R2, and the slope 2
(I. Caprini, L. Lellouch, M. Neubert, [Nucl. Phys. B530(1998)153])Fit F(1)|Vcb| and 2
meas.
q2 m
Results on real dataResults on real data
14|Vcb| from
Fitted D** Fitted D** contribution: contribution:
Systematic uncertaintiesSystematic uncertainties
15|Vcb| from
DELPHI averageDELPHI average
16|Vcb| from
DELPHI average:DELPHI average:
Goals:Goals:Increased statistics ( 4)Improvements in the reconstruction (Eb, mD*)
Control on background
Comparison with other measurementsComparison with other measurements
17|Vcb| from
World averageWorld average |Vcb|=0.0402 0.0009 0.0018
(excl.)
|V|Vcbcb| from inclusive decays | from inclusive decays
18|Vcb| from inclusive decays
Measured sl=(0.434 0.008)×10-10 MeV
Error on |VError on |Vcbcb| ~ 1 %| ~ 1 %
sl =|Vcb|2
Theory:Theory:
1+O(1/mb) 2
ci=f(mb,mc,s)
O.P.E.O.P.E.
Inclusive s.l. decay width:Inclusive s.l. decay width:
Non-perturbative corrections 5%
Perturbative corrections 10%
OPEOPE formalism formalism
19
, , GG22 22 DD ,, LSLS 33 33
|Vcb| from inclusive decays
Kinetic massKinetic mass scheme scheme ( (=1=1 GeV)GeV)
Can be measured?
Not rely on mNot rely on mcc expansionexpansion
sl =|Vcb|2
Quark massesQuark masses
Kinetic energy of the b quark inside the Kinetic energy of the b quark inside the mesonmeson: : chromo-magnetic exp. value chromo-magnetic exp. value (MB*-MB)22GG
22
mmbb, m, mcc
Darwin term:Darwin term:
Spin-orbit term:Spin-orbit term:
33DD
33LSLS
Phys.Lett. B556 (2003) 41
Moments of the Moments of the D** D** distributiondistribution
|Vcb| from inclusive decays
Moments of the total hadronic mass distribution in bc -
Inclusive |Vcb| determination
22%
50%
28%D
D*
D**
Inclusive observables Inclusive observables O O
Known
Measurements of OPE parameters
b c -
q2
ccbb
D** properties ?
20
D** spectroscopyD** spectroscopy
D** properties 21
Ground state Broad resonances
Narrow resonances
D** decays into D and D*
possible D** D(*)
In addition to resonant states, D** includesnon resonant D(*)
(not measured)
D** signalD** signal
22D** properties
Definition of signal and background regions
23D** properties
Fit to wrong sign candidates:
signal
**, 1ary and 2ary
vertices, and other
topological info
D** production ratesD** production rates
Fit to right sign candidates:
24
D** D(*) limits:
D** properties
Results onResults on production rates production rates
Main syMain systematicstematics:s: discr. variables & cascade modelling(RS BR’s 4% each)
From wrong sign candidatesFrom wrong sign candidates
Comparison with other measurements:Comparison with other measurements:
Increased statisticsImproved systematics
D** mass distributionD** mass distribution
25D** properties
Fit to m = m(D(*)**) - m(D(*)) and R (>0.25)
From right sign candidates
Considering D** 11 parameters
(19±13)%
26
D** mass distributionD** mass distribution
D** properties
m = m(D(*)**) - m(D(*))
D0+ D+- D*+ -
D** production characteristicsD** production characteristics
27D** properties
Total D** rate:
Main systematics due to the possible D(*) contribution
Compatible results with measure-ments from B →D** decays :
CLEOCLEO
BELLEBELLE
First measurement of D* properties in B semileptonic decays
1
Moments of the mass distributionMoments of the mass distribution
28Moments
From previous results:
Combining information from momentsCombining information from moments
29Moments
Fixing Constraining+
DELPHI hadronic mass + lepton energy moments
Fit resultsFit results
30Moments
Unconstraining the b quark mass:
The c quark mass corresponds to:
G (BPS limit) 2 2
D small 0.1 GeV 3
3
|V|Vcbcb| determination | determination
31Moments
Including electroweak, (s)2 and (1/mb)3 corrections:
In the kinetic mass scheme, mqkin(1 GeV)
s (mb/2, 2mb)mb, mc, , D, G, LS
2 2 33
LEPb,
Comparison with other measurementsComparison with other measurements
32Moments
Amsterdam, Amsterdam, ICHEP ‘02ICHEP ‘02
Aachen, ICHEP ‘03Aachen, ICHEP ‘03
New theoretical calculations: hadron + lepton moments within the kinetic mass formalism.
BABAR result seems not to fit with theoretical expectations
First measurement at low p
New analysis from BABAR
Summary and conclusions Summary and conclusions
33Summary and conclusions
|Vcb| from exclusive BdD*+
Measurement of Measurement of BR(bBR(bD*D*++XX
|Vcb| from inclusive decays
D** properties, measurements of:D** properties, measurements of: -- production rates production rates -- production characteristicsproduction characteristics -- hadronic mass momentshadronic mass moments
Development of a new OPE formalism:Development of a new OPE formalism: -- measurement of non-perturbative measurement of non-perturbative
parameters parameters up to O(1/mup to O(1/mbb))
33
00
Precise |VPrecise |Vcbcb| determination| determination-- Measured Measured sl.sl. ~ 1%~ 1%
-- Theory Theory ~ 1-1.4%~ 1-1.4%-- Non-pert. parameters Non-pert. parameters ~ 1.4%~ 1.4%