hadronic b decays to double-charm final states
DESCRIPTION
Hadronic B Decays To Double-Charm Final States. SERGIO GRANCAGNOLO L.Lanceri – J.P.Lees BINP Novosibirsk Particle Physics Seminar. Outline. Introduction The BaBar Detector at PEP-II The D sJ observations Theoretical Interpretations of D sJ Analysis of B D (*) D sJ decays - PowerPoint PPT PresentationTRANSCRIPT
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Hadronic B DecaysTo Double-Charm Final States
SERGIO GRANCAGNOLOL.Lanceri – J.P.Lees
BINP Novosibirsk
Particle Physics Seminar
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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
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Introduction
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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
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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
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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
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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
__ _ _ _
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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
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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
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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)
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• 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
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_ ___
_
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
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The BaBar Experiment
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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
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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
_
_ _
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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
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The DsJ observations
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• 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
_
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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
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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)
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Theoretical Interpretations of DsJ
Standard interpretations
Exotic interpretations
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• 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
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• 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
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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
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Analysis of BD(*)DsJ decays
Branching ratios: Method
Event selection
Signal and Backgrounds
Efficiency and “cross-feed”
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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
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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
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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
*
_
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• 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*
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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)
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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”:
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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
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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)
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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
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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
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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
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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.
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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
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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
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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
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Results
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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
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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
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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
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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)
_
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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
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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
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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
_
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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
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Backup
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10 Feb 2006 Sergio Grancagnolo 53
BaBar run 5
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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
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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
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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
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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)
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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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10 Feb 2006 Sergio Grancagnolo 59
Low energytrack efficiency
from slow
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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
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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
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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
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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()
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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
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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
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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
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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%
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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
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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
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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
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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
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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
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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
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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
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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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10 Feb 2006 Sergio Grancagnolo 76
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
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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
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10 Feb 2006 Sergio Grancagnolo 78
Comparison with old Belle resultsPhys.Rev.Lett.91:
262002,2003
Experimental results
compatible within errors
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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)