Charm results overview 1

Charm ...the issues

• Lifetime • Rare decays• Mixing• Semileptonic sector• Hadronic decays (Dalitz plot)• Leptonic decays• Multi-body channels (4,5,6 bodies!) • Charm Baryons• D* spectroscopy

Charm results overview 2

A brief review of the measurements

for each topic:

• summary of the present experimental situation

• a comment about the next future reach

to be done

• a more precise picture of the experimental status within 5 and 10 years

– BaBar, Belle, Cleo-c, CDF, BEPC, LHC-b, BTeV

Charm results overview 3

Charm lifetimes

0

( )2.538 0.023

( )

D

D

Motivation: investigation of non-spectator processes

• FOCUS (*) produced new lifetimes results with precision better than the previous world average (○), PDG 2002.•Already at the level of comparison with theory.•Systematics will dominate

Charm results overview 4

Rare decays

( ,

,

)sD D h

h K

FOCUS improved results by a factor of 1.7 –14: approaching theoretical predictions for some of the modes but still far for the majority

CDF and D0 can trigger on dimuons promising

Motivation: lepton number violation studyinvestigation of long range effects and SM extention

CDF Br(D0+-)<2.4 x10-6 @ 90% C.L.is the best limit for this mode (65 pb-1 data)

Charm results overview 5

MixingMotivation: suppressed in the charm sector in the SM. If “measured”, would suggest SM extention

Future is @ Babar & Belle

;2

Mx y

Charm results overview 6

Summary of reach

• Where we are and where we go

Charm results overview 7

The semileptonic sector

FOCUS number is 1.59standard deviation below CLEO and 2.1 standard deviation above E691

All values consistent with their average value with a CL of 19%

Motivation: semileptonic decays are the easiest way to determine CKM elements

0*D K Branching ratio

Charm results overview 8

...and 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

2/GeV c2/GeV c

Nominal spectroscopicpole masses

v 1(0) (0)r V A 2 2 1(0) (0)r A A

3 3 1(0) (0)r A A

D+

d

d

uu

s

Charm results overview 9

form factors

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

FOCUS analysis is the first to include the effects on the acceptance due to changes in the angular distribution brought about the s-wave interference

Form Factor lattice calculations available!

0*D K

Charm results overview 10

Group electron muon

FOCUS 0.540.0330.048

CLEO2 0.540.050.04

E687 0.580.170.07

ARGUS 0.570.150.15

CLEO 0.490.100.12

Br(Ds / Ds

sD

Charm results overview 11

v 2

791 2.27 0.35 0.22 1.570 0.250 0.190

0.9 0.6 0.3 1.400 0.500 0.300

653 2.3 1.0 0.4 2.

1.549 0.250 0.145 0.713 0.202 0

100 0.550 0.

.26

0

6

2 0

Group r r

E

CLE

FOC

O

US

E

form factors

1. Most precise measurement to date2. very consistent with D+K03. very consistent with th. expectation

Cleo-c expects experimental error in most of the measurements in the sl sector in the range

1 to a few %

sD

Charm results overview 12

Hadronic decay investigation

A few slides follow about Dalitz plot analysis

Charm results overview 13

“Future” of hadronic decays

•Full observation of the decay (for three-body channels)•Learn about strong effects (but also a complicationfor the analysis!)•CP investigation (see example of D±K K±±)•Interplay between charm (and beauty) decays and light meson spectroscopy (very clean samples!)

Motivation: Investigation of decay dynamics via Dalitz plot analysis

The analysis is difficult, need an analysis strategy to keep under control the strong effects accompanying the weak decays of Heavy Flavours!

Charm results overview 14

An instructive example from FOCUS

Milano group

D

analogy with operatively:

complete Dalitz plot analysis (time-dependent) to deal withall interference with other () intermediate channels

B

crucial for determination of the angle of the SM unitarity triangle

Charm results overview 15

FOCUS D s +

++- analysis

Observe:

•f0(980)

•f2(1270)

•f0(1500) Sideband

Signal

Yield Ds+ = 1475 50

S/N Ds+ = 3.41

f0(980) signal is clean!

Charm results overview 16

First fits to charm Dalitz plots in the K-matrix approach!

C.L fit 3 %

sD

Low mass projection High mass projection

+

+20 +

(S - wave)π 87.04 ± 5.60 ± 4.17 0(fixed)

f (1275)π 9.74 4.49 2.63 168.0 18.7 2.5

ρ (1450)π 6.56 ± 3.43 ± 3.31 234.9 ±19.5 ±13.3

decay channel phase (deg)fit fractions (%)

r

j

2iδ 2 2r r 12 13

r 2iδ 2 2j j 12 13j

a e A dm dmf =

a e A dm dm

Projections of the f0(980) signal

Charm results overview 17

sD

•No significant direct three-body-decay component

•No significant (770) contribution

sD

Marginal role of annihilation in charm hadronic decays A reliable measurements of the annihilation processes in the hadronic sector is still missing.... need more data!

Charm results overview 18

Yield DYield D++ = 1527 = 1527 5151

S/N DS/N D++ = 3.64 = 3.64

FOCUS D+ ++- analysis

Sideband Signal

Charm results overview 19

2lowm

2highm

D

C.L fit 7.7 %

K-matrix fit results

Low mass projection High mass projection

18 11.7

+

+2

0 +

(S - wave)π 56.00 ± 3.24 ± 2.08 0(fixed)

f (1275)π 11.74 1.90 0.23 -47.5 .7

ρ (770)π 30.82 ± 3.14 ± 2.29 -139.4 ±16.5 ± 9.9

decay channel phase (deg)fit fractions (%)

Good channel to investigatethe nature of the meson(aka the puzzle).No new ingredient (resonance)

required not present in the scattering!

Charm results overview 20

With

Without

C.L. ~ 7.5%

Isobar analysis of D+ ++would instead require a new scalar meson:

C.L. ~ 10-6

m = 442.6± 27.0 MeV/c = 340.4 ± 65.5 MeV/c preliminary

Charm results overview 21

Another interesting example from FOCUS D+, Ds KK

Ds+ K+ K+ D+ K+ K+

D sD

2Km

2KKm 2

KKm

2Km

KKm

Charm results overview 22

+ -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

Possible investigation of a0(980) & the f0 series

Charm results overview 23

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==

Charm results overview 24

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 via D+ K-K++ Dalitz analysis

Charm results overview 25

phi(1020) K*(1430) a0(980) K1(1410) f2(1270) f0(1370) phi(1680)

K*(1430)phi(1020) a0(980) K1(1410) f2(1270) f0(1370) phi(1680)

Coefficients: D±,, DD++,, DD--

Phases: DD±±,, DD++,, DD--

Preliminary!

No evidence of CPV

Charm results overview 26

Other Dalitz plot analyses

• The Ks0+- channel could contribute to mixing studies

– D0 is tagged from D* so CF decay makes K0 . DCS or mixing make K0 .

– These interfere and it may be possible to determine + from Dalitz plot.

• In any case, it contains much physics - a real challenge to fit well.

15,753 events 23 fb-1

Scale to the full sample!

BaBar & Belle have the statistics to make it! The problem is the formalism!

In Cleo-c there is a dedicated working group consisting of experimentalists and theoreticians

BaBar

Charm results overview 27

Leptonic decays

Motivations: decay constants

present future

Charm results overview 28

for the future...

• Multi-body charm decays• Charmed baryon spectroscopy• D* spectroscopy

– Statistics is still limited: some results from BaBar, Belle, FOCUS

– More data necessary: CDF, Cleo-c, B-factory, LHC-B, BTeV

Charm results overview 29

Some slides of general interest

• Why charm at a B factory

• How is Tevatron working

• Cleo-c run plan

• Comparison among experiments

• BEPC future

Charm results overview 30

Charm at B Factory?

• Cross section is large

Present BaBar sample of 91 fb-1 contains

• Compare with earlier charm experiments:– E791 - 35,400 1

– FOCUS - 120,000 2

– CDF - 56,320 (new number available soon)

Charm results overview 31

Temperature of Tevatron

Charm results overview 32

Cleo-c

Charm results overview 33

comparison

Charm results overview 34

BEPC future

• Program and schedule