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Meson Lifetimes, Decays, Mixing and CPV in FOCUS. Sandra Malvezzi I.N.F.N. Milano. A new charm-physics era The high statistics and excellent quality of data allow for unprecedented sensitivity & sophisticated studies Investigation of decay dynamics both in the hadronic - PowerPoint PPT Presentation
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Sandra Malvezzi - Charm Meson Results in Focus
1
Sandra MalvezziI.N.F.N. Milano
Meson Lifetimes, Decays, Mixing and CPV in FOCUS
Sandra Malvezzi - Charm Meson Results in Focus
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A new charm-physics era
The high statistics and excellent quality of data allow for unprecedented sensitivity & sophisticated studies
Investigation of decay dynamics both in the hadronic and semileptonic sector Phases and Quantum Mechanics interference FSI role & CP studies
Lifetime measurements @ better than 1% non-spectator processes
Mixing possible window on physics beyond SM
Sandra Malvezzi - Charm Meson Results in Focus
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OutlineHadronic decays
Amplitude Analysis of three pseudoscalar channels
Semileptonic decays
Anomaly in decay
New BR of and
Lifetimes Precise measurements for and preliminary for
D K K K
D K sD K D K K
( )D K 0
*( )
( )
D K
D K
( )
( )s
s
D
D
0,D DsD
sD K K K First clear evidence (DSCD) First evidence (SCSD)
First Dalitz analysis New method for CPV
s-wave interference
Mixing0D K 0D K Prelimary results from and
Sandra Malvezzi - Charm Meson Results in Focus
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Over 1 million reconstructed!!
Successor to E687. Designed to study charm particles produced by ~200 GeV photons using a fixed target spectrometer with upgraded Vertexing, Cerenkov, E+M Calorimetry, and Muon id capabilities. Includes groups from USA, Italy, Brazil, Mexico, Korea
1 million charm particles reconstructed into DK , K2 , K3
FOCUS Spectrometer
Sandra Malvezzi - Charm Meson Results in Focus
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, sD D K K K
First observation
First clear observation
4
3
( )(9.49 2.17 0.22) 10
( )
( )(8.62 2.04 2.07) 10
( )s
s
D K K K
D K
D K K K
D K K
Yield = 65.515.0Yield = 31.4 7.4
hep-ex /0206049
R
Wc
ds
s
su
d
Intervention of resonances coupling both to and KK or annihilation
KKK MD
sD
Sandra Malvezzi - Charm Meson Results in Focus
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, sD D K
)()(cos 2121331 mBWPppFFA r
J
JJ
rD
j
j jj
Aia e M
)(
)(
02
2
12
12
0 pF
pF
m
M
p
p
r
rr
j
r
Spin 0
Spin 1
Spin 2
rr
rD
MimM
FFrBW
212
2)|12(and
)1cos3()(2
)2(
1
1322
13
13
ppP
ppP
P
J
J
J
Where2
1
21
)339(
)1(
1
4422
22
pRpRF
pRF
F
190 24
/ 1.0DY
S N
468 29
/ 2.4sD
Y
S N
Dalitz plot analysis of
K
Sandra Malvezzi - Charm Meson Results in Focus
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Yield D+ = 190 24
S/N D+ = 1.0
DCS D+K++-
Decay fractions and phases
NR = 9 5 % (-6 16) °
K*(892) = 43 7 % (208 16)°
K*(1410) = 12 8 % (133 23)°
K2(1430) = 6 3 % (48 27) °
K*(1680) = 22 10 % (2 20)°
(770) = 51 10 % (0 fixed)
f0(980) = 9 5 % (73 31) °
(1450) = 10 5 % (-113 15) °
K+ projection + projection
Preliminary 2Km
2m
r
j
2 2 2r r 12 13
r 22 2
j j 12 13j
A dm dmf
A dm dm
i
i
a e
a e
Sandra Malvezzi - Charm Meson Results in Focus
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Decay fractions and phases
NR = 18 4 % (34 7)°
K*(892) = 22 3 % (163 7) °
K*(1410) = 14 5 % (-10 7) °
K*0(1430) = 14 6 % (68 7)
°
(770) = 40 4 % (0 fixed)
f2(1270) = 2 1 % (33 21) °
(1450) = 8 2 % (219 14) °
SCS
Yield Ds+ = 468 29
S/N Ds+ = 2.4
Ds+K++-First Dalitz
analysis
Preliminary
K+ projection + projection2Km
2m
Sandra Malvezzi - Charm Meson Results in Focus
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Ds , D+ KK
Ds+ K+ K+
D+ K+ K+
DsD
2Km
2KKm 2
KKm
2Km
KKm
Sandra Malvezzi - Charm Meson Results in Focus
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Interference term
Sandra Malvezzi - Charm Meson Results in Focus
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+ -2
K Km
- +2
K πm
K+ Kprojection K projection
Yield D+ = 7106 92
S/N D+ = 8.62
Decay Fraction and phases
K*(892) = 20.7 1.0 % (0 fixed)
(1020) = 27.8 0.7 % (243.1 5.2)°
K*(1410) = 10.7 1.9 % (-47.4 4.9)°
K* (1430) = 66.5 6.0 % (61.8 3.8)°
f0(1370) = 7.0 1.1 % (60.0 5.3) °
a0(980) = 27.0 4.8 % (145.6 4.3)°
f2(1270) = 0.8 0.2 % (11.6 7.0) °
(1680) = 1.6 0.4 % (-74.3 7.5) °
Preliminary
Sandra Malvezzi - Charm Meson Results in Focus
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CP violationFor a two amplitude decay
ii = strong phase
CP asymmetry:
2 different amplitudes strong phase-shift
AAtottot = g1M1ei1 + g2M2ei2
CP conjugate
AAtottot = g1M1ei1 + g2M2ei2** **
aaCPCP==2Im(2Im(gg2 2 gg11**) sin() sin(11--22)M)M11MM22
|g|g11||22MM1122+|g+|g22||22MM22
22+2Re(+2Re(gg2 2 gg11**)cos()cos(11--22)M)M11MM22
|Atot|2- |Atot|2
|Atot|2+ |Atot|2==
Sandra Malvezzi - Charm Meson Results in Focus
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Dalitz plot = FULL OBSERVATION FULL OBSERVATION of the decay
COEFFICIENTS and PHASES for each amplitude
Measured phase: =+CP conserving CP violating
CP conjugate =
=-=-
E831
aCP=0.006±0.011±0.005Measure of direct CP violation:asymmetrys in decay rates of DDKKK K
CP violation:Dalitz analysis
Sandra Malvezzi - Charm Meson Results in Focus
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Coefficients: D±,, DD++,, DD--
Phases: DD±±,, DD++,, DD--
D+/D- split sample analysisPreliminary!
No evidence of CPV
K-matrix approach to improve the quality of the analysis
Sandra Malvezzi - Charm Meson Results in Focus
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New results on D K
Our K spectrum lookslike 100% K*(892)
This has been known for about20 years
...but a funny thing happened when we tried to measure the form factor ratios by fitting the angular distributions
Sandra Malvezzi - Charm Meson Results in Focus
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An unexpected asymmetry in the K* decay
forward-backwardasymmetry incos below the K*pole but almost noneabove the pole
V
Vd
d 2cos1
Sounds like QM interference
A 4-body decays requires 5 kinematics variables: 3 angles and 2 masses
KM
2
2
WM q t
Sandra Malvezzi - Charm Meson Results in Focus
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Try an interfering spin-0 amplitude
2
2 2
0
(1 cos )sin
2 2(1 cos ) sin
( )2 2
sin (cos )
2
il V
il V
iδl V
B
B
e H
M t m e H
AeB H
will produce 3 interference terms
iAe
(plus mass terms)
02 2
0 0
mB
m m im
iAeWe simply add a constant amplitude in the place where
the K* couples to an m=0 W+ with amplitude 0H
Phys.Lett.B535,43,2002
Sandra Malvezzi - Charm Meson Results in Focus
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Studies of the acoplanarity-averaged interference
2 20*8cos sin Re( )V KV
iA e B H
Extract this interference term by weighting data by
Since all other averaged terms in the decay intensity are constant or
2cos V
cos V
We begin with the mass dependence: *Re( )i
Ke B
A constant 45ºphase worksgreat.......but the solution is notunique.KM
Sandra Malvezzi - Charm Meson Results in Focus
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Sandra Malvezzi - Charm Meson Results in Focus
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*0( )0.602 0.01( ) 0.021( )
( )
D Kstat sys
D K
New FOCUS semileptonic BRs & Form Factors
All values consistent with their average value with a CL of 19%
Our number is 1.59standard deviation below CLEO and 2.1 standard deviation above E691
Sandra Malvezzi - Charm Meson Results in Focus
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*0( )D K Form Factors The vector and axial form factors are generally parametrized by a pole dominance form
22 2
(0)( )
1i
iA
AA q
q M
2
2 2
(0)( )
1 V
VV q
q M
2.5
2.1A
V
M
M
Nominal spectroscopicpole masses Decay intensity (including s-wave amplitude)
parametrized by
v 1(0) (0)r V A 2 2 1(0) (0)r A A3 3 1(0) (0)r A A
v 1.504 0.057 0.039r
2 0.875 0.049 0.064r
hep-ex /0207049
New FOCUS results
2/GeV c2/GeV c
Sandra Malvezzi - Charm Meson Results in Focus
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Form Factor Ratios v 2
1.45 0.23 0.07 1.00 0.15 0.03
791( ) 1.90 0.11 0.09 0.71 0.08 0.09
791( ) 1.84 0.11 0.09 0.75 0.08 0.09
687 1.74 0.27 0.28 0.78 0.18 0.11
653 2.0
1.504 0.057 0.039 0.875 0.049 0.06
0 0 3
4
. 3
Group r rFOCUS
BEATRICE
E e
E
E
E
0.16 0.82 0.22 0.11
691 2.0 0.6 0.3 0.0 0.5 0.2E
Our analysis is the first to include the effects on the acceptance due to changes in the angular distribution brought about the s-wave interference
0.330 0.022 0.015A 1GeV
0.68 0.07 0.05 rad
Sandra Malvezzi - Charm Meson Results in Focus
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( )0.54 0.033( ) 0.048( )
( )s
s
Dstat sys
D
sD sD
sD
Baseline cuts
a) 2682 evtsb) 4695 evts
Baseline, out-of-material.isolation cuts
c) 793 evtsd) 2192 evts
hep-ex /0206056
Sandra Malvezzi - Charm Meson Results in Focus
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Charm Meson Lifetimes
0D K
0D K
D K
0 ,D D Lifetime fitsSignal0 ,D D
139433520 evts
68274360 evts
109877385 evts
Sandra Malvezzi - Charm Meson Results in Focus
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0( ) 409.6 1.1( ) 1.5( )D stat sys
( ) 1039.4 4.3( ) 7.0( )D stat sys
0
( )2.538 0.023
( )
D
D
0 0
0
( ) ( ) ( )1.01 0.13
( ) ( ) ( )
D eX B D eX D
D eX B D eX D
0
(17.2 1.9)%
(6.87 0.28)%
D eX
D eX
PDG2002........difference in the hadronic sector
0 12 12
0.0035 0.00990.0034 0.0127
( 10 ) ( 10 )
0.413 0.004 0.003 1.048 0.015 0.011
0.4085 0.0041 1.0336 0.0221
0.413 0.003 0.004
0.4096 0.0011 0.0015 1.0394 0.0043 0.0070
687
791
Exp D
E
CLEOII
E
FOC
s
US
D s
Phys.Lett.B537,192 ,2002
FOCUS
fs
fs
Sandra Malvezzi - Charm Meson Results in Focus
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Lifetime 506 8 fs5668 95 events (50% FOCUS data)
sD signal
0
( )1.23 0.02
( )sD
D
PDG 2002 4909 fs
Theoretical prediction (Bigi Uraltsev)1.00-1.07 (no WA/WX)
0.8-1.27 (different process interference) 4 x statistics including *0K K
Preliminary
Sandra Malvezzi - Charm Meson Results in Focus
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Mixing
;2
Mx y
Direct comparison of CP final state lifetime
0
1 2
1 1( & )2 2
1( ) ( )
2
D K CP CP
K
02( )D K K CP
0
0
( )1
( )CP
D Ky
D KK
(3.42 1.39 0.74)%CPy
Phys.Lett.B485,62,2000
Sandra Malvezzi - Charm Meson Results in Focus
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' cos sin
' cos sin
x x y
y y x
is the relative strong phase
2 22' '
( ) ( ' )2
tDCS DCS
x yR t e R R y t t
only statistical error ! FOCUS K+ -
New Mixing Results
0D K
0D K v
Preliminary
....towards CLEO & a big relative phase
0.0012mixr @ 95% C.L.
Sandra Malvezzi - Charm Meson Results in Focus
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Conclusion Charm physics is revealing itself a rich source of new results
FOCUS is playing a crucial role in understanding the charm phenomenology
new suppressed decay modes
decay dynamics of three-body hadronic channels via quasi two-body decays semileptonic sector very precise lifetime measurements (will dominate PDG)
mixing 0D K 0D K
Sandra Malvezzi - Charm Meson Results in Focus
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R
Wc
ds
s
su
d
Intervention of resonances coupling both to and KK
DsD
KNot obvious evidence of
QUESTION SLIDES
Sandra Malvezzi - Charm Meson Results in Focus
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Five observables are studied A 4-body decays requires 5 kinematics variables: 3 angles and 2 masses
KM
22
WM q t
)(),(),( 2220 qHqHqH
Left-handed
2
0
2
2
0
22
cos2
coscos
sinsin
sinsin
cossin2
sin)cos1(
sin)cos1(
)(8
1||
tV
Vl
iVl
iVl
W
Vl
iVl
iVl
l
H
H
He
He
t
m
H
He
He
mtA
Two amplitude sumsover W polarization
Right-handed
Wigner D-matrices (“mass terms”)
are helicity-basis form factors
Sandra Malvezzi - Charm Meson Results in Focus
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Since interference will dominate.....
here will be only three terms as 0m
2 20
(*
)0
)*
*(
0
8cos sin Re( )
. 4(1 cos )sin Re( )
4(1 cos )sin Re( )
V Vi
l Vi
l V
K
K
K
i B H
Inte B
B
rf e H H
e
A
A H
A
H
e
If we average over acoplanarity we only get the first term
2 20*8cos sin Re( )V KV
iA e B H
his is the term creating forward-backward asymmetry!
If our model is right:•The asymmetry will have a particular mass dependence•The asymmetry should be proportional to •The asymmetry should have a dependence from q given by
*Re( )iKe B
2sin l2 2 2
0 ( )q H q
Sandra Malvezzi - Charm Meson Results in Focus
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Sandra Malvezzi - Charm Meson Results in Focus
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Sandra Malvezzi - Charm Meson Results in Focus
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Sandra Malvezzi - Charm Meson Results in Focus
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Sandra Malvezzi - Charm Meson Results in Focus
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Sandra Malvezzi - Charm Meson Results in Focus
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All values consistent with an average of 0.54 0.04
Group electron muon
This work 0.540.0330.048
CLEO2 0.540.050.04
E687 0.580.170.07
ARGUS 0.570.150.15
CLEO 0.490.100.12
Sandra Malvezzi - Charm Meson Results in Focus
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2000 picture
2002 new measurements:
BELLE
BaBar preliminary
0.70.8( 0.5 1.0 )%CPy
0.60.7(1.4 1.0 )%CPy
(0.8 2.9 1)%CPy E791:
CLEO: 5.8% ' 1%y
3.8 1.13.5 2.1(1.0 )%CPy
BELLE:
(preliminary)
Very preliminry FOCUS result on
from semileptonic
3 times better than E791
2 2
2mix
x yr
The comparison with CLEO is valid only if there is a small strong phase difference
Sandra Malvezzi - Charm Meson Results in Focus
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Sandra Malvezzi - Charm Meson Results in Focus
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Inner muon
0.001000.000910.00117mixr
preliminary
Sandra Malvezzi - Charm Meson Results in Focus
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outer muon
0.003250.002810.00226mixr
preliminary
Sandra Malvezzi - Charm Meson Results in Focus
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