(3770) and D physics at BESII
Ma HaiLong[For BES Collaboration]
CCAST & IHEP
中国物理学会 2006 年秋季会议(北京)2006.9.15-17
Outline
Purely and semi leptonic decay of D meson
Summary
BF[(3770) → D0D0,D+D-,DD and non-DD]
Motivation
Df
2
2
22
221
8
D
lDlDD
cdF
m
mmmf
|V|GνlD(
)
Df
The effect of strong interaction can be parameterized by
Lattice gauge, potential models bag model, QCD sum rule …, calculation predict the value of
The fD measurement will allow comparison with the theoretical calculation to improve the theory
Lattice predicts fB/fD with small errors. Precision measurement of fD precision estimate of fB and precision determination of Vtd
Df Bf00 BB Mixing
experiment
It is very difficult to measure the fD due to |Vcd|
Df
D
Motivation
2041)()/(00 ..eKDeKD ee
PDG04 BF
1)()( 0 ll KlD/KlD The called
“Longstanding puzzle” in Charm decay! 00( ) / ( )l lD K l D K l
0
0
, , D K l l
D K l
The decay rates can be related to the CKM matrix elements and form factors
0Dc
u)(d
)( D
s ][d
)(d
K ][
)( 0K][ || ||VV cdcs
)]0([ )0( ff K
Ratio of partial widths of vector to pseudoscalar semileptonic decays of D mesons
*0 0( ) / ( )D K e D K e
Branching fractions
Isospin conservation implies
There are controversies from both experiment and theoretical prediction
Early theories: 0.9-1.3Measurements: smallerRecent theories:0.5-0.7
Motivation
Motivation
Long-standing puzzle of (3770) production and decays
(3770) is thought to decay almost entirely to pure DDbar, but there is large discrepancy between and )3770( DD
1, Systematic shift in the measured cross sections2, There may be some other effects
3, There may be substantial non-DDbar decays
nb 8.16.11))3770((12
2)3770(
)3770( eeBFM
prd
nb 0.50.5)( DDeeobs (Mark-III)nb 7.01.7)( DDeeprd
before BES-II & CLEO-c
Cross section at peak (PDG04 parameters)
Simultaneously measusing both and )3770(DD
Precisely measuring the energy dependent cross sections for both inclusive hadrons and DDbar events production simutanmeously, directly measure and00[ (3770) , , ]BF D D D D DD [ (3770) ]BF non DD
Motivation Search for some exclusive non-DDbar decays
No final answer from experiments. It is assumed
S-D mixing,
puzzle,
Re-scattering mode,
What is the total branching fraction for non-DDbar decays?
Interference…
BES observed 12 signal events for the decay DD non)3770(measured the branching fraction to be
)%09.014.034.0()/)3770(( JBF
CLEO confirmed BES observation of the decay, and measured the branching fractions to be
)%022.0189.0()/)3770(( 007.0004.0
JBF
PLB 605(2005)63
CLEO also observed some other non-DD-bar decay modes such as , … ( 0,1,2)CJ J
More works is being done……
PRL96(2005)082004
(3770) data sample
~17.3 pb-1 data taken at 3.773 GeV
~7 pb-1 data taken at the region from 3.768 GeV to 3.778 GeV
~8 pb-1 data taken in the energy region from 3.665 to 3.878 GeV
The total Luminosity is about 33 pb-1
Near DD-bar production threshold region
π–
e+
e-
D
D
K+
π–tag
D+
D-π–
e-e+
D
D
K+
tag
Singly tagged D sample
Absolute Measurements
0D
0D
X+ X0
Throughout the talk, charge conjugation is implied
Singly tagged D samples
Singly tagged D- modes: (a)K+π -π -;(b) K0 π -; (c) K0 K-; (d) K+K-π -;(e) K0π -π -π+; (f) K+π -π -π0;(g) K0π -π0;(h) K+π -π -π -π+;(i) π -π -π+; (j) Sum
Singly tagged D0 modes: (a)K+π -; (b) K+
π -π -π +; (c) K0 π -π +; (d) K+ π -π 0
ND-Tag=5321±125±160 ND
0Tag=7584±198±241
Singly tagged D samples
Mass[mKnπ]
e+0.1110.053( ) (0.122 0.010)%,BF D
D
129119(371 25) MeV
Df
Purely leptonic decay
e-
D+
K+
D+
D-
missmissmiss PEU
Neutrino carries energy and momentum away
Should be around zero
5321 125 160TagD
N
Fully reconstruct one D-
Require one additional charged track and no additional photons
tagπ-
π-D-
0.33±0.11 background events is estimated from 3 candidate events, 2.67±1.74 is
retained
background estimation
Theory Comparison[from Matt Shepherd’s Meson06 Talk]
PLB610(2005)283
PRL95(2005)251801
Should be around zero due to the mass of the missing neutrino is zero
Semileptonic DecaysSemileptonic Decays
Umiss=Emiss-pmiss
|Umiss|<2[3]σ Umiss
No surplus charged track and good photon on the recoiling side
π–
e-e+
D
D
K+
tag
Singly tagged D sample
0D
0D
Ke
e
0 (found in REC of D tags.)eK e
0 (found in REC of D tags.)ee
CKM matrix elments
Form factors
PLB597(2004)39
)( 0eeKDBr
)( 0eeDBr
BESII(%) CLEO(%)
3.83±0.40±0.27 3.44±0.10±0.10
0.33±0.13±0.03 0.262±0.025±0.008PRL95(2005)181802
0 (found in REC of D tags.)K 0
(found in REC of D tags.)
Preliminary Results The first error is statistical, the second systematic, and the third arises from PDG branching fractions for the normalizing modes
030100110)(
)(0
0
...KDBr
DBr
606063 ... 100310380 ... CLEO
E687-1
E687-2
E653
FOCUS
PDG06
BESII
0 -e (found in REC of D tags.)K e
Preliminary Results
0
0
( )1.08 0.22 0.07
( )
e
e
D K e
D K e
0
0
( )0.87 0.24 0.15
( )
D K
D K
Support isospin conservation holds in the D semileptonic decays!
040050001)(
)(0
0
...eKD
eKD
e
e
PLB608(2005)24
PRL95(2005)181801
0BF( ) 8.95 1.59 0.67eD K e
0 - (found in REC of D tags.)K
0BF( ) 10.3 2.3 0.8eD K e
Candidates for
eeKD 0*eeKD
eeKD 00eeKD *0
Mass[mKn] Mass[Kπ]
*00 0 *, , ,e e e eD K e K e D K e K e
Branching fractions
Decay modes
BES MARKIII PDG04
*0
0
( )0.57 0.17 0.02
( )
D K e
D K e
support smaller ratio of D to V/P semileptonic decay of D mesons
EPJC47(2006)31
eeD
D
No signal event is observed
90%CL
Candidates for
EPJC47(2006)39
Measurement of R
BornhadR
had
hadobshad L
N
)1(
obshadBorn
had
R -
e+
e-
+
h a d ro n s-e
e+
q-
q
f la v o rc o lo r
= Qf2
lowestorder
R is one of the most fundamental quantities in particle physics, which counts directly the charges, the flavors and the colors of quarks involved.
pQCD calculates the R ratio Experimentally, one measures
: # of hadronic hadN
: Luminosity L
: Eff.had
events
: radiative correction factor
)1(
22 (GeV)
nb 8.86
cmee E
)( & hadrons)( DDeeee
ECM [GeV]
σobshad(nb) σ0
had(nb) R
3.650
3.665
3.773
18.983 0.087 0.182
18.299 0.199 0.176
27.680 0.056 0.266
14.578 0.067 0.141 0.588
14.128 0.158 0.139 0.580
22.855 0.046 0.220 1.144
2.236 0.010 0.022 0.089
2.185 0.024 0.022 0.087
3.746 0.008 0.036 0.187
3.746 0.008 0.036 0.187@ 3.773 GeVR
WA| 2.218 0.019 0.089udsR
(3686) (3770)fit to &| 2.262 0.054 0.109uds σR
PRL in press, hep/0605107
Obtaining by fitting to the R values measured by BES in the range from 2.0 to 3.0 GeV
14.026.2| GeV 3.0 to 2.0 udsR
PLB641(2006)145, hep-ex/0605105
Born σ )3770((3770) & R
udsRRR )3770(
Taking the R for light hadron production to be a constant, then
(3770) 1.528 0.042 0.131R We obtain
(3770) 9.323 0.253 0 801 nbBorn .
nb 74.108.11))3770(()1(
122
)3770(VP)3770(
eeBF
MBorn
)024.0047.1()1( VP obtained based on PDG04 (3770) resonance parametersPLB 603(2004)130
My
calc
ula
tio
n It is consistent with
(3770) cross section
e+
e-
D
D
K-
tag
D-
D+
X
π+
π+
Using Kinematic fit method to improve momentum resolution and select the singly tagged D meson
Xfit MM Requiring
2 BrL
NtagDobs
DD
of data @ 3.773 GeV Single tag method
DD cross section
KD0
KD0
KD
nb 0.260.082.56 obs
DD
nb 0.500.126.14 obsDD
Observed cross sections for DD-bar production at 3.773 GeV
nb 0.310.093.58 00 obs
DD
PLB 603(2004)130
1pb 3.17 L
Near DD-bar production threshold region
e+
e-
D
D
K-
π+tag
D-
D+X
e-e+
D
D
K-
tag
D0
D0
Using ‘double tag’ method, pioneered by MARK-III, to identified DD-bar pair
tagged one D meson
tagged another D
π+ π+
Double tag method
K+π- -
π- -
K+π- -
π- -
π+
Absolute measurement, does not depend on branching fractions of D meson decays
117.3 pbL of data
DD cross section
nb 0.210.323.47 00 obs
DD
nb 0.200.332.46 obs
DD
nb 0.350.465.93 obsDD
An
ab
solu
te
mea
sure
men
t
KvsK ..
KvsK ..
0.. KvsK
00 .. KvsK
KvsK ..0 KvsK ..
KvsK ..
0.. KvsK
0.. SKvsK
KKvsK S0..
0.. SKvsK
00.. SKvsK
KKvsK ..
00 KD
KD0
KD0
0SKD
KD
0SKD
KKD KKD S0
0 KD00 SKD
NPB727(2005)395
D0D0(nb) D+D-(nb) DD(nb)
BES single
3.58±0.09±0.31 2.56±0.08±0.26 6.14±0.12±0.50
BES double
3.47±0.32±0.21 2.46±0.33±0.20 5.93±0.46±0.35
MARKIII 2.90±0.25±0.30 2.10±0.30±0.15 5.00±0.39±0.34
CLEO
Comparison of observed cross sections
+0.07-0.053.60 0.07 +0.10
-0.042.79 0.07 +0.17-0.086.39 0.10
Radiative correction factor B
obs
g
Born
obsDD
Born
BornDDDD
σgN
NDDBF
)3770(IIBES)3770(prd
(3770)
prd
))3770((
Obtained from analysis of R
Determination of
BES II 0.770 0.014g
Some systematic uncertainties can be canceled out
Radiative correction factor obtained based on new (3770) resonance parameters measured by BES-II, hep/0605107.
BF[(3770) → D0D0,D+D-,DD and non-DD]
( (3770) ) (35.7 1.1 3.4)%BF D D
0 0( (3770) ) (49.9 1.3 3.8)%BF D D
( (3770) ) (85.5 1.7 5.8)%BF DD ( (3770) ) (14.5 1.7 5.8)%BF non DD
PLB641(2006)145, hep-ex/0605105
Measurement of branching fractions for DDDDDD ,,)3770(
00 DD non)3770(and
The data were collected at 49 energy points from 3.66 to 3.89 GeV, which begin from off-resonance, cover (2S), (3770) and stop at DD* threshold .
Cross section scan experiment
Separated beam collision data at 3 energy points were collected to study beam associated background.
Some J/, (2S) data were also taken to calibrate BEPC energy and determine trg
Integrated luminosities
Luminosities were measured by using large angle Bhabha scattering eventsAbout 5.4 pb-1 of data were collected for the experiment (for hadron events)
Monte CarloDeveloped a inclusive hadronic event generator with high order ISR corrections to simulate the hadronic event production (including Lorentz boost due to initial state photon emission) in the full energy region
When scan over 3.770 GeV
Just before the scan experiment
Mass [MeV]
PDG04
BEPC
BEPC
BEPC
011.0916.3096
05.030.3095
034.0093.3686
01.090.3684
02.050.3684
BEPC energy calibration
'
'
'J/
J/
3095.33684.8
MM3095.3)(EME
PDGJ/ψ
PDG
ψBEPCPDG02J/ψ
true '
EBEPC is the energy of BEPC set in the experiment,
Etrue is the true energy
01.070.3684
8.36842
9.36847.3684
MC generator & simulationFull energy range ISR Generatorhadronsee
GeV 783.s )3770(
)3686(
/J
)1700(
[GeV] energy Effective
Nch KNOφ
Thrust Oblatenesscosθ
Sphericity
Aplanarity
Jet axis cosθ
x η Y
Pt <PTin2>
<PTout2>
Den
sity
[n
b/G
eV]
D.Zhang,G.Rong,J.C.Chen, PRD74(2006)054012
trgcmhadcm
hadcm
obshad EEL
nE
)( )()(
1
0
exp ))1(( ),( )( xssxfdxs Becthad
)()(
)(12)(
2222 sMMs
ss
tot
feeB
(Kuraev and Fadin)
functionsampling issxf ),(
Hadron efficiency vs C.M. energy
Energy dependent hadron cross sections
had
hadobshad L
N
: # of hadronic
: Luminosity L: Eff.had
eventshadN
Inclusive hadrons
Inclusive hadrons
Ob
serv
ed c
ross
sec
tio
n f
or
had
ron
pro
du
ctio
n [
nb
]
)mode(2
)()(
tag single
tag single
D
D
DBL
ENE
cm
cmobs
DD
KD0
KD
Distributions of invariant masses of combinations at different c.m.energyies
mKn
Energy dependent DDbar cross sections
KD0
00DD
DD
DD
Line shape of the cross sections for hadron and DD-bar production
( (3770) ) (36.9 3.7 3.1)%BF D D
0 0( (3770) ) (46.7 4.7 2.3)%BF D D
( (3770) ) (83.6 7.3 4.7)%BF DD ( (3770) ) (16.4 7.3 4.7)%BF non DD
Branching fractions
Simultaneously.fitting to the inclusive hadron and the DD-bar production cross sections
00DD
DD
Inclusive hadrons
Inclusive hadrons
Inclusive hadrons
PRL in press, hep/0605107
Experiment
MARK-I
DELCO
MARK-II
PDG06
BES-II
(MeV) Γ tot (eV) Γee
63772
63770
3771.1 2.4
3772.2 0.7 0.3
528
524
90370
60180
50276+27-24242
251 26 11
388
286
280
(MeV) M
85.0 2.4
524
23.0 2.7
53764
Comparison of (3770) resonance parameters
26.9 2.4 0.3 86.7 0.7
(MeV) )3770(M
(3686) (3770)fit to &| 2.263 0.058 0.091uds σR
(3770) 9.63 0.66 0 35 nbBorn .
PRL in press, hep/0605107
Comparison of (3686) Resonance Parameters
Experiment
This measurement
BES-II published
(PLB550(2002)24)
PDG2006
(MeV) M '(keV) '
tot
(keV) 'ee
3685.5 0.0 0.3 331 58 2 2.330 0.036 0.110
..AN 27264 21.044.2
034.0093.3686 337 13 2.48 0.06
The measured partial width is consistent with PDG06 partial width of (3686).
PRL in press, hep/0605107
CKM matrix elments and form factors
SummarySummary
The ratio of
0
0
( )0.87 0.24 0.15
( )
D K
D K
0
0
( )1.08 0.22 0.07
( )
e
e
D K e
D K e
Support isospin conservation holds in the D semileptonic decays.
support smaller ratio of D to V/P semileptonic decay of D mesons
*0
0
( )0.57 0.17 0.02
( )
D K e
D K e
BES measured branching fractions of exclusive semileptonic decays of D mesons
The ratio of
Preliminary
BES search for and eeD
D
BES measured branching fraction for pure leptonic decay D
129119(371 25) MeV
Df
0.1110.053( ) (0.122 0.010)%,BF D
nb 0.500.126.14 obsDD
nb 0.350.465.93 obsDD
Singly tagged D analysis
Doubly tagged D analysis
BES measured DDbar cross sections at 3.773 GeV
BES measured R at 3.773 GeV and Ruds around 3.65 and 3.6648 GeV
(3686) (3770)fit to &| 2.262 0.054 0.109uds σR
3.746 0.008 0.036 0.187@ 3.773 GeVR
WA| 2.218 0.019 0.089udsR
In the range from 3.67 to 3.89 GeV, obtained from fitting to (3686) and (3770)
SummarySummary
SummarySummary BES measured the branching frations for inclusive non-DDbar decays of (3770) using two different data sample and two different methods
( (3770) ) (36.9 3.7 3.1)%BF D D
0 0( (3770) ) (46.7 4.7 2.3)%BF D D
( (3770) ) (83.6 7.3 4.7)%BF DD ( (3770) ) (16.4 7.3 4.7)%BF non DD
( (3770) ) (35.7 1.1 3.4)%BF D D
0 0( (3770) ) (49.9 1.3 3.8)%BF D D
( (3770) ) (85.5 1.7 5.8)%BF DD ( (3770) ) (14.5 1.7 5.8)%BF non DD
These are first measurements.
Determined from analysis of R values and DD-bar cross sections
Obtained from fitting to the inclusive hadron and the DD-bar production cross sections simultaneously.
Thank You !