Hadronic B DecaysTo Double-Charm Final States
SERGIO GRANCAGNOLOL.Lanceri – J.P.Lees
BINP Novosibirsk
Particle Physics Seminar
10 Feb 2006 Sergio Grancagnolo 2
Outline
• Introduction
• The BaBar Detector at PEP-II
• The DsJ observations
• Theoretical Interpretations of DsJ
• Analysis of BD(*)DsJ decays
• Results: branching fractions and angular distributions
• Comparison with models and conclusions
Introduction
10 Feb 2006 Sergio Grancagnolo 4
The Standard Model
• Fundamental particles:– 6 quark , 6 leptons– 4 interactions
• The model works well but there are several issues to be understood, for instance:– Higgs boson– Supersymmetry– Strong interactions
b
t
s
c
d
u
e
e
W,Z bosons
10 Feb 2006 Sergio Grancagnolo 5
Quantum Numbers Of The Quarks
d u s c b t
Q – electric charge -1/3 +2/3 -1/3 +2/3 -1/3 +2/3
Iz – isospin -1/2 +1/2 0 0 0 0
S - strangeness 0 0 -1 0 0 0
C - charm 0 0 0 +1 0 0
B - bottomness 0 0 0 0 -1 0
T - topness 0 0 0 0 0 +1
PropertyQuark
10 Feb 2006 Sergio Grancagnolo 6
CKM Matrix and Unitary Triangle
Unitary relationship VudVub*+VcdVcb
*+VtdVtb*=0
W+
Vijqj=d,s,b
qi=u,c,t
VcdVcb
*
Vtd V
tb *
V udV ub
*Unitary triangle
tbtstd
cbcscd
ubusud
VVV
VVV
VVV
V
A complex phase in the V matrix can be a source of CP violation in B decays
049.0736.0)2sin(
VV†=I
CKM
10 Feb 2006 Sergio Grancagnolo 7
Mesons in the Quark Model
• Quarks exist only in baryons and mesons
• Mesons are made of a quark-antiquark pair
• As an example:
• Mesons are not stable– Mass, charge and lifetime are main characteristics– Meson width ~ 1/lifetime
depends on the allowed decay modes
K+ D0 B- Sud us cu bu bb
__ _ _ _
10 Feb 2006 Sergio Grancagnolo 8
Heavy Quark Approximation
q
Q_
In the heavy quark approximation
mq<<mQ,, mQ
sQ, j conserved
However J, P good quantum numbers
ℓ
sQsq
sQ ,sq =+½,-½
Heavy and light quark spins
ℓ=0,1,… Orbital momentum
j=ℓ+sq
Light quark total angular momentum
P=(-1)ℓ+1 Parity
J=j+sQMeson total angular
momentum
10 Feb 2006 Sergio Grancagnolo 9
Charmed Mesons Spectroscopy
JP cu csExpected
width
(0,1) D,D* D,D*s narrow
(0+,1+) D*0,D´1 D*
s0,D´s1 broad
(1+,2+) D1,D*2 Ds1,D*
s2 narrow
• States with ℓ=1 can decay strongly with emission of a pseudoscalar meson– j=1/2 emission in s-wave– j=3/2 emission in d-wave
• D*0,D´1 observed by CLEO, Focus and Belle
– Broad resonances as expected
ℓ=0
ℓ=1 )21(Pj )23(Pj
_ _
broad ~100 MeV
narrow ~10 MeV
10 Feb 2006 Sergio Grancagnolo 10
The expected cs Meson Spectra
States expected but not observed
• Masses over threshold DK(*)
• Broad states (large widths)
*
_
2.51 GeV
2.36 GeV
M.Di Pierro, E.EichtenPhys. Rev. D64, 114004 (2001)
10 Feb 2006 Sergio Grancagnolo 11
• Spectator quark model
the other u,d quark enters the final state without participating to the interaction
• In hadronic decays, could be tested the factorization hypothesis:
the final hadrons are produced independently
B Meson Decay
Since mb >>mu,d
bcW* whereW* ℓ
W* qiqj
_semileptonic
hadronic
the B meson decay dominantly through
W* virtual boson
the disintegration of the b quark. The main transition
is the weak decay
10 Feb 2006 Sergio Grancagnolo 12
_ ___
_
Exclusive Hadronic B decays
• In exclusive decays all particles in final state are reconstructed
• Double charm decays contains two mesons with charm quarks
• Examples:
B,B0 D(*)0,D
Ds
B,B0 D(*)0,D
D(*)0
K(*)
_BDsD
B DDK
The BaBar Experiment
10 Feb 2006 Sergio Grancagnolo 14
The PEP-II B-factory at SLACPEP-II is a high luminosity, asymmetric, e+e collider
Lint=254 fb-1
Ldesign = 3 x 1033 cm-2s-1
Lpeak = 9.21 x 1033 cm-2s-1
Integrated luminosity
year
113fb-1
10 Feb 2006 Sergio Grancagnolo 15
B-factory Cross Sections
e+e cross-section (nb)
bb 1.05
cc 1.30
uu, dd, ss
2.09
0.94
1.16
e+e ~40
The boost allows a separation of the two B vertices.
E(e+) = 3.1 GeV E(e) = 9.0 GeV
_
_
_
_ _[
e+e
h
adro
ns](
nb)
√s(GeV)
Ecm=10.58 GeV
boost: =0.56
(4S) BB_
e+e bb on-resonance BB
“coontinuum” e+e cc high momentum charmed particles
_
_ _
10 Feb 2006 Sergio Grancagnolo 16
Cerenkov Detector (DIRC)
1.5 T solenoid Electromagnetic Calorimeter
Drift Chamber
Instrumented Flux ReturnSilicon Vertex
Tracker
e+ (3.1 GeV)
e- (9 GeV)
BABAR Detector%85.1%32.2 4/1 E
EE
%45.0%13.0)(
TT
T pp
p
The DsJ observations
10 Feb 2006 Sergio Grancagnolo 18
• BaBar discovered a new particle decaying into Ds0
– c and s quarks– Mass < DK threshold– Width < 10 MeV
• Seen by Belle and CLEO• Is this the expected Ds0 ?
DsJ(2317) Discovery*
BaBar collaborationPhys.Rev.Lett.
90, 242001 (2003)
_
*+
+
+
Ds0 Invariant mass
GeV
m=2.317GeV
+
Inclusive selection of high momentum charmed meson from coontinuum e+e cc
_
10 Feb 2006 Sergio Grancagnolo 19
DsJ(2460) Discovery
• CLEO observed another state decaying to Ds 0!
– c and s quarks– Mass < (DK)* threshold– Width < 10 MeV
• Observed also decay modes:– Ds, Ds+
• Is this the expected Ds1?
+
2.25 2.5 2.75
Eve
nts/
7 M
eV/c
2
*+
++
+
CLEO collaborationPhys. Rev. D68, 032002 (2003)
Seen by BaBar and Belle
m=2.460 GeV
Ds 0 Invariant mass *+_
GeV
80
60
40
20
0
10 Feb 2006 Sergio Grancagnolo 20
The Observed cs Meson Spectra
New states observed
• Masses below threshold DK(*)
• Narrow states
*
_
2.51 GeV
2.36 GeV
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• Isospin symmetry is not exact
• Violation already observed in Ds* Ds0 decay
Isospin Violation in These Decaysmeson Ds,Ds
*,DsJ D0 K+ 0
qq cs cu us uu+dd
Isospin (I,Iz) (0,0) (½,-½) (½,+½) (1,0)
Invoked oscillation
DK Ds0
Energy forbidden
Energy conserving
Isospin allowed
Isospin violating
DsJ Ds0
_ __ _ _ __
P.L.Cho, M.B.Wise
Phys.Rev.D49: 6228-6231,1994
ss
(0,0)
Theoretical Interpretations of DsJ
Standard interpretations
Exotic interpretations
10 Feb 2006 Sergio Grancagnolo 23
• Quark models– Potential: coulombian
• (0-,1-),(0+,1+) chiral partners– doublets mass splitting via chiral symmetry breaking
– transitions via scalar meson
Standard interpretationsEntia non sunt multiplicanda praeter necessitatem (G.Occam)
Cahn, Jackson
need to adjust a posteriori input parameters, predict mass higher than observed or not reproduce non-strange charmed mesons spectra
hyperfine splitting for charmed mesons (D, D*, etc.) marginally compatible with experiments
Bardeen, Eichten, Hill
Lucha, Schoberl
+ linear
+ spherical not linear
10 Feb 2006 Sergio Grancagnolo 24
• Unitarized chiral models– generalization replacing a light quark with an
heavy quark
• Non-perturbative methods– lattice QCD
– QCD sum rules
Standard interpretations
several new mesons predicted not observed
initial difficulties to reproduces masses, reproduces mass splitting
low accuracy
Dai, Huang, Liu, Zhu
Bali
Beveren, Rupp
10 Feb 2006 Sergio Grancagnolo 25
Exotic Interpretations
cs DK 4-qmixing
di-quark pairs
Ds molecule
Ds
DK molecule
D
K
qq qqqq
D
K
qq_
_
_ __
_
Maiani, Piccinini, Polosa, Riquer
Barnes, Close, Lipkin
Szczepaniak
Browder, Pakvasa, Petrov
Analysis of BD(*)DsJ decays
Branching ratios: Method
Event selection
Signal and Backgrounds
Efficiency and “cross-feed”
10 Feb 2006 Sergio Grancagnolo 27
BD(*)DsJ Decays• Exclusive DsJ production: expected to be dominant
• Allow to measure DsJ quantum numbers
• In principle, allow to discriminate between conventional and multi-quark scenarios compared with other B decays such as BD(*)Ds and BD(*)D(*)K
• If the DsJ is the conventional cs state should be produced in the following graph:
Weak external W emission
_ _
_
B,B0 D(*)0,D
DsJ
___
Same graph as BD(*)Ds similar branching ratios could be expected
_
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• We search for DsJ particles looking at the 12 combinations:
• With DsJ decays:
• We measure branching ratios, quantum numbers JP
BD(*)DsJ Decays (II)
ssJ
ssJ
DD
DD
)2460(
)2460( 0*0* )2317( ssJ DD
sJsJ
sJsJ
DDBDDB
DDBDDB0*0
*00
10 Feb 2006 Sergio Grancagnolo 29
Subdecay Modes
Intermediate particles are reconstructed in the following modes:
ss DD*
KD
0* DD
K
sD
0 K K
KD0
KK KK 0*
)892(
Total: 60 different submodes combined to
give the 12 combinations
0D
000* DD Green::clean modes
10 Feb 2006 Sergio Grancagnolo 30
Analysis Goal and Method• We aim to measure branching ratios Bri (i=1…12) of
the exclusive double charm two body production of DsJ(2317)+
and DsJ(2460)+ in B0 and B+
• nisig number of signal candidates for mode i
– after combinatorial background subtraction
• nixfd number of crossfeed events for mode i
– contains background from other signal modes
• ireconstruction efficiency from simulation• NBB = [122.0 ± 0.6(stat) ± 1.3(syst)] 106 (113 fb-1)
BBi
ixfd
isigi
N
nnBr
*
_
10 Feb 2006 Sergio Grancagnolo 31
• Reconstruct the chain:
• Reconstruct tracks (K,) and photons ()
• Select D0, Ds , , 0 computing invariant masses
• Use beam energy kinematic constraint
• Fit nisig in Ds invariant mass distribution
A specific example: B0D*DsJ(2460)+
B0
K+
D0_
DsJ(2460)+*
Ds
+
K+
K
*
D*
10 Feb 2006 Sergio Grancagnolo 32
Event Selection: Invariant MassesInvariant mass: 2
212
21 ||)( ppEEm
D0 K Ds
D* D0 KK
0.99 1.02 1.04
40000
20000
0
m(GeV/c2)
Particles masses are set to their nominal values (mass constraint)
10 Feb 2006 Sergio Grancagnolo 33
Event Selection: B candidates• Compute p*
B and E*B
from selected D*, Ds,
• Use the B-factory constraint E*beam to compute:
5.272<mES<5.288 GeV
E|<32MeV
better resolution
uncorrelation
Sidebands to estimate background outside signal box
mES
ΔE
**beamB EEE 2*2* )()( BbeamES pEm
Use of beam kinematic variables
“Signal box”:
10 Feb 2006 Sergio Grancagnolo 34
E resolution
• Same resolution for all the submodes
• A systematic error will take in account differences between data and simulation
Missing energy effect
Simulation of signal events
Data candidates in mES signal region
(E)=16.1 (E)=18.9
Cross-hatched background from sidebands
10 Feb 2006 Sergio Grancagnolo 35
E resolution (II)
(E) simulation data
0 12 16
16 20
Final values used in selection
(MeV)
Better resolution for modes with a 0 (mass
constraint)
10 Feb 2006 Sergio Grancagnolo 36
Background Rejection
• Reduction of the combinatorial background• Simulated signal events selected in signal region• Background from data events selected in DsJ mass
sideband region• Curves represent
fraction of events cut bym(D0)> mcut(D0)
• Optimal cut set at themaximum separationbetween two samples
Gev/c2
Events rejected:
25% signal
75% backgrd
m(D*) cut
m(D*)>2.4GeV/c2
10 Feb 2006 Sergio Grancagnolo 37
Optimization• Maximized the significance ratio:
S = simulated signal events in signal region
B = background from data in m(DsJ) sidebands
BS
S
Tried different cut levels for D and Ds using PID, vertexing and helicity cut
Tried different numbers of cut for variables: E, m(Ds), m(D)
1.94 2.0m()
5000
200002500
40000
cos(hel)-1 1
cos(hel) mass
Cleaner modes require less stringent cuts
10 Feb 2006 Sergio Grancagnolo 38
Fit nisig in DsJ(2460)+ Ds
+
• Finally, in selected candidates: m(Ds)
• Fit the background shape with a polynomial
• Fit the signal peak with a Gaussian of fixed width– =12 MeV
– estimated in data
• Events in the signal peak: ni
sig = 53.0±7.7
Ent
ries
/10
Mev
/c2
GeV/c2
m(Ds)
significance=11.7
10 Feb 2006 Sergio Grancagnolo 39
Efficiency and Cross-feed
• From gi=60k simulated signal events for each mode i
– Efficiency:
nisim = number of B0D*DsJ(2460)+ events reconstructed in
the corresponding simulated sample
– Total cross-feed:
nijsim = number of B0D*DsJ(2460)+ events reconstructed in
the simulated sample (mode j)
fij = cross-feed from the mode j to the mode i
i
isimi
g
n
j
j
ijev
ixfd BrfNn
j
ijsimij
g
nf ;
Typical efficiency range: 1-10%
depending on the presence of photons, soft tracks, stringent cuts, etc.
10 Feb 2006 Sergio Grancagnolo 40
m(DsJ)
GeV/c2
Efficiency
i=(4.63±0.08)%
fij=(0.82±0.04)%
nisim = 2778
gi=60000
nijsim = 24
gj=60000
Cross-feed
Generated mode: B0D*Ds1
Ds
Generated mode: B0D*Ds1
Ds+
Narrow Cross-feed
Narrow:xfdsig
Reconstructed mode: B0D*Ds1
Ds
10 Feb 2006 Sergio Grancagnolo 41
Cross-feed
m(DsJ)
GeV/c2
Efficiency
i=(2.25±0.07)%
Generated mode: B0DDs1
Ds*
Cross-feed
fij=(0.24±0.02)%
Generated mode: B0DDs0
Ds
fij=(0.27±0.02)%
Generated mode: B0DDs0
Ds
Wide Cross-feed
nisim = 1350
gi=60000
nisim = 144
gi=60000
nisim = 162
gi=60000
Wide:xfd 2.5 sig
Reconstructed mode: B0DDs1
Ds
10 Feb 2006 Sergio Grancagnolo 42
Branching Ratios and Cross-feedAn iterative procedure is needed:
• Compute for each mode i without considering cross-feed
• Estimate nixfd using Brj and the cross-feed fij
from all the modes• Subtract the number of cross-feed events• Compute the corrected branching ratio
• Recompute the cross-feed iterating point 2-4 until convergence.
iev
isigi
N
nBr
iev
ixfd
isigi
N
nnBr
__
ixfd
isig nn
Results
10 Feb 2006 Sergio Grancagnolo 44
s=3.1
s=5.5
s=5.2
s=2.5
s=5.1
s=4.2
s=7.4
s=7.7
s=4.3
s=5.0
s=11.7
s=6.0
Fit Results And Significance
10 Feb 2006 Sergio Grancagnolo 45
Main Systematic Errors• Tracking efficiency 9%• /0 efficiency 5%• Background fitting model 5%
– Tried exponential instead of polynomial to fit background
• E width 5%– Changed the width of the E
signal region by ±3 MeV
• DsJ width 3%– Varied by ±1 MeV the of the
Gaussian (12 MeV) that fit the signal
Depends on the tracks or photons number
Modes with D*0 more affected
10 Feb 2006 Sergio Grancagnolo 46
Branching Ratios Results
NEW!
NEW!
NEW!
NEW!
NEW!
NEW!
Phys.Rev.Lett.93:181801,2004
Measurements with significance>5
10 Feb 2006 Sergio Grancagnolo 47
DsJ(2460)+ Angular Analysis (I)
• Use B0DsJ+D and B+ DsJ
+D0 with DsJ+Ds
• B DDsJ+ is a transition 0 0 JP so DsJ is polarized
• Compute the helicity angle h of DsJ+Dsand compare
with the predictions for JP=1+ and JP=2+ (0+ forbidden)
_
10 Feb 2006 Sergio Grancagnolo 48
DsJ(2460)+ Angular Analysis (II)
Simulation is used to correct for detector acceptance
DsJ events are fitted separately in 5 cos(h) bins
not used cut m(D)>2.3
10 Feb 2006 Sergio Grancagnolo 49
DsJ(2460)+ Angular Analysis (III)
• Expected distribution for JP=1+ is:
1-cos2(h)• Distribution compatible
with this case– 2/d.o.f.=3.9/4– Supporting the Ds1
+ hypothesis for this state
• Comparison with JP=2+ hypothesis is also provided– 2/d.o.f.=34.5/4
10 Feb 2006 Sergio Grancagnolo 50
Some Comparisons With Models
• Branching ratios smaller than the corresponding BD(*)Ds
(*)
– Factorization effects could be important and could not cancel in the ratios RD0,1
– support a multiquark hypothesis
• Observation of electromagnetic DsJ(2460)+ decay– supports a conventional cs picture
• In agreement with prediction from chiral multiplets we measure:
Colangelo, De Fazio, Ferrandes: Mod.Phys.Lett.
A19:2083,2004
Godfrey Phys.Lett.
B568:254,2003
Bardeen, Eichten, Hill: Phys.Rev.
D68:054024,2003
_
10 Feb 2006 Sergio Grancagnolo 51
Conclusions
• We combine 60 different final states to obtain 12 branching ratios BD(*)DsJ measurement with
– The modes BD*DsJ with a D* or a D*0 are first observations
– Extraction of JP=1+ quantum numbers of DsJ(2460)+
sssJ DDD ,)2460( 0*
0* )2317( ssJ DD
Backup
10 Feb 2006 Sergio Grancagnolo 53
BaBar run 5
10 Feb 2006 Sergio Grancagnolo 54
Inner Tracking and Vertexing: SVT
• Extrapolation of secondary vertex
• Standalone tracking capability for low pt tracks
Double side silicon microstrips
layers resolution (m)
1-3 10-15
4-5 40
High pT track
Low pT track
10 Feb 2006 Sergio Grancagnolo 55
The Detector of Internal Reflected Cherenkov light
)βn1(cos)( 1Ec
A charged particle traversing the DIRC produces Cherenkov
light if n>1
10 Feb 2006 Sergio Grancagnolo 56
Particle IDentification:dE/dx, DIRC
For tracks with p<700MeV: dE/dx from
DCH and SVT
For tracks with p>700MeV:
Cerenkov angle from DIRC
10 Feb 2006 Sergio Grancagnolo 57
Photons: EMC
• Projective geometry
• Discriminate between hadron and electromagnetic showers
• Contribute to triggerm=134.5MeV
=6.4MeV
m (MeV)
10 Feb 2006 Sergio Grancagnolo 58
Theoretical DsJ Interpretation References
• Cahn, Jackson: Phys.Rev.D68, 037502 (2003) • Lucha, Schoberl: Mod.Phys.Lett. A18, 2837 (2003)• Bardeen, Eichten, Hill: Phys.Rev.D68,054024 (2003)• Beveren, Rupp: Phys.Rev.Lett.91, 012003 (2003)• Bali: Phys.Rev.D68, 071501 (2003)• Dai, Huang, Liu, Zhu: Phys.Rev.D68,114011 (2003)• Szczepaniak: Phys.Lett.B567, 23(2003)• Browder, Pakvasa, Petrov: Phys.Lett.B578, 365 (2004)• Barnes, Close, Lipkin: Phys.Rev.D68,054006(2003)• Maiani, Piccinini, Polosa, Riquer: Phys.Rev.D71.014028
(2005)
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Low energytrack efficiency
from slow
10 Feb 2006 Sergio Grancagnolo 60
Reconstruction of Soft Pions• Fundamental to understand our capability of
reconstruct D*
• Estimate tracking efficiency from data itself
We reconstruct: D*+ D0 +
m = m(D*+)-m(D0)=140.6 MeV
m()=139.6 MeV Energy available for the is
very low
Expected symmetric angular distribution of the events in
the D* frameD* direction
of flight
Helicity angle
1 00
Angular analysis
JP K
10 Feb 2006 Sergio Grancagnolo 61
Soft Pion studies
Separation of pion sample based on D* momentum
p(D*) GeV/c
)cosβ(γ *** ssspEE
For a given D* momentum:
linear relationship
Slow
er D*
Critical regions
p(D*) bins
10 Feb 2006 Sergio Grancagnolo 62
Background subtraction• Use of two kinematic
variables: m(D0), m
• Four categories of events:
1. Signal
2. Real-D0+bad-s
3. Bad-D0+real-s
4. Combinatoric background
• Use of kaon and pion PID to distinguish between different contributions m
m(D
0 )
Background removal within each p(D*) bin, that cover the same soft pion kinematic range of the signal
10 Feb 2006 Sergio Grancagnolo 63
Efficiency of Soft Pion
-1.0 1.00
Convolute the helicity distributions with an efficiency function parameterized as:
0
00
01)(
11
)(pp
ppppp
Low p(D*)
High p(D*)
cos(*)
)cos1(cos
*2*
Nd
d
Efficiency estimate from asymmetries in the helicity angle distributions
Asymmetric distribution
Expected distribution (symmetric)
Low cos()
10 Feb 2006 Sergio Grancagnolo 64
Soft Pion Efficiency Results
• Convoluting function parameters obtained minimizing a 2
• Relative efficiency raise over 90% already at 100Mev/c
• From the differences between data and simulation: a systematic uncertainty of 1.4% per track in the efficiency
SimulationData
DataSimulatio
n
170 ± 7 148 ± 16
p0 65.5 ± 0.2 65.0 ± 0.4
p() GeV/c
Efficiency
10 Feb 2006 Sergio Grancagnolo 65
Event Selection (I): tracks
“very loose” 50MeV<p<10GeV d0<1.5cm |z0|<10cm
Tracks:
Kaon PID:
Photons and 0:
“loose”E()>30Me
VLAT<0.8
115<m()<150MeV
Invariant mass:
“not a pion” PID and p(K)>250MeV
use dE/dxefficiency
95%mis-id<20%
“loose” 1005<m()<1020 MeV helicity cut |cos(h)|>0.3
221
221 ||)( ppEEm
10 Feb 2006 Sergio Grancagnolo 66
Event Selection (II): D0, Ds
m0 (MeV) (MeV) n cut other modes
D0 1863.1 6.3 3 K0,KDs 1966.1 5.3 3 K*K
Measure invariant mass m, and resolution in data:
Apply the request: - n < m-m0 < n
10 Feb 2006 Sergio Grancagnolo 67
Another example
• B0->D*-DsJ(2460)+, DsJ->Ds*pi0– We have D*->D0pi
(soft +)
– Ds*->Dsgamma
– D0,Ds as before
• Pi0 veto on gamma
tight PIDand p>250MeV
use DIRC for p>0.6GeV
efficiency 85% mis-id<5%
10 Feb 2006 Sergio Grancagnolo 68
Gev/c2
Background from BD(*)Ds(*)
• Identical D(*),Ds(*) selection
• B candidates selected in mES, E signal region
Events rejected
Eve
nts/
10 M
eV/c
2
200
02.0 2.7
m(Ds)
2.35
Reject events with at least a candidate
compatible with BD(*)Ds
(*)
Background events that enter marginally in the DsJ signal region
easily combine with low energy or 0 to
give a DsJ
350
10 Feb 2006 Sergio Grancagnolo 69
Gev/c2
Ent
ries
/10
Mev
/c2
Background Events
• Simulated ~220 fb-1 of generic events– No peaking background
observed
m(Ds0)
Gev/c2 2.62.2 2.4
Ent
ries
/10
Mev
/c2
50
100
m(Ds0)
2.62.2 2.4
200
400• Simulated ~60k events
for each mode BD(*)Ds(*)
– No peaking background observed
10 Feb 2006 Sergio Grancagnolo 70
Reconstruct B candidates
B candidates must enter in the signal box: mES, E
Determine selection criteria using a simulation60k signal
events for each submode
Resolution:=16 MeV
If more than one B candidate is found, the one with the smaller difference E-E0 is retained
E
GeV
Eve
nts/
5 M
eV/c
2
10000
5000
10 Feb 2006 Sergio Grancagnolo 71
nisig = 32.7±10.8
nisig = 34.8±7.9
nisig = 15.3±6.8
nisig = 23.6±6.1
s=3.1
s=5.5
s=5.2
s=2.5
10 Feb 2006 Sergio Grancagnolo 72
nisig = 28.0±5.8
nisig = 17.4±5.1
nisig = 30.5±6.4
nisig = 26.5±5.6
s=5.1
s=4.2
s=7.4
s=7.7
10 Feb 2006 Sergio Grancagnolo 73
nisig = 32.0±8.2
nisig = 24.8±6.5
nisig = 34.6±7.5
nisig = 53.0±7.7
s=4.3
s=5.0
s=11.7
s=6.0
10 Feb 2006 Sergio Grancagnolo 74
Other Efficiency and Cross-feed
• In B+D0DsJ(2317)+ cross-feed is dominated by DK D0K0
D0 K0
D K reconstructed as D0 K0
m(DsJ)m(DsJ)
GeV/c2 GeV/c2
250
10
Efficiency Cross-feed
i=(1.93±0.06)% fij=(0.04±0.01)%
nisim = 1160 , gi=60000 nij
sim = 24 , gj=60000
10 Feb 2006 Sergio Grancagnolo 75
Isospin averaged branching ratios
• Combine D+ and D0 and D*+ and D*0
measurements
• Average with statistical weight w=1/i2
• To compare two measurements x1 and x2 with variance 1 and 2 we use the variable z:
n
iii Bw
wΒ
1
1
22
21
21
xxz
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Ratios of Branching Ratios
• Compare BD(*)Ds and BD(*)DsJ measurements is possible through ratios:
• Neglecting phase space we expect:
• We know BD(*)Ds from PDG (1-5%)
• Final results to be revised
)(
)( 00
s
sD DDBBr
DDBBrR
)(
)(*1
1s
sD DDBBr
DDBBrR
)(
)(*
0*
0*s
sD DDBBr
DDBBrR
)(
)(**1
*
1*s
sD DDBBr
DDBBrR
Datta, O’donnell
Phys.Lett. B568:254,2003
110 DD RR and similarly for RD*0 and RD*1
10 Feb 2006 Sergio Grancagnolo 77
Comparison with Belle
Decay channel BaBar Br(10-4) Belle Br(10-4) z
8.08.37.129.25.26.18][)2460(
1.09.18.04.69.03.17.6][)2460(
0.26.87.283.128.97.61][)2460(
2.14.48.146.43.56.27][)2460(
)5.8(1.32.22.39.12][)2317(
6.00.35.11.108.17.25.13][)2317(
2.20.2
4.69.3
**
4.24.1
*
4.74.6
9.209.12
0***
8.25.2
4.98.5
0**
1.27.1
4.47.2
0**
7.49.2
0*
ssJ
ssJ
ssJ
ssJ
ssJ
ssJ
DDDB
DDDB
DDDB
DDDB
DDDB
DDDB
Phys.Rev.Lett.93, 181801 (2004)
J.Phys.Conf.Ser.9:115-118,2005
10 Feb 2006 Sergio Grancagnolo 78
Comparison with old Belle resultsPhys.Rev.Lett.91:
262002,2003
Experimental results
compatible within errors
10 Feb 2006 Sergio Grancagnolo 79
Conclusions
“no compelling evidence that a non-standard scenario is required … neverthless unanswered questions remain …” (Review by P.Colangelo, F.De Fazio, R.Ferrandes, hep-ph/0407137)