Meson Lifetimes, Decays, Mixing and CPV in FOCUS

Sandra Malvezzi - Charm Meson Results in Focus

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Sandra MalvezziI.N.F.N. Milano

Meson Lifetimes, Decays, Mixing and CPV 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


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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


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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


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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


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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


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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


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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


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Ds , D+ KK

Ds+ K+ K+

D+ K+ K+

DsD

2Km

2KKm 2

KKm

2Km

KKm


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Interference term


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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


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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==


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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


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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


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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


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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


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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


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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


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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


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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


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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


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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


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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


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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


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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


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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


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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.


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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


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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


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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


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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


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36


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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


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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


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Inner muon

0.001000.000910.00117mixr

preliminary


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outer muon

0.003250.002810.00226mixr

preliminary


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Meson Lifetimes, Decays, Mixing and CPV in FOCUS

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