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Flavour Physics and CP violation

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Flavour Physics and CP violation

Paris, June 3rd 2003

D0 mixing

and

Charm lifetimes

An experimental review

Gianluigi Boca

Pavia University and INFN

Italy

Gianluigi Boca, Flavour Physics and CP Violation 2003

Experimental review of the D0 mixing measurements

- formalism in short

- review of lifetime ratios

- review of D0 DCS hadronic decays measurements

- review of D0 Wrong Sign semileptonics decays

Experimental review of charm particle lifetime measurements

- mesons : D+ , D0 , Ds

- baryons : Xc+ , Lc+ , Xc0 , Wc0

Gianluigi Boca, Flavour Physics and CP Violation 2003

Experiments mainly considered in this review

experiment beam approx. Luminosity Average st

type type total charm

E791 fixed target 500 GeV p 105 40 fs

Focus fixed target up to 300 Gev g 106 30 fs

Selex fixed target 600 GeV S, p, p 104 20 fs

Cleo collider e+e-at U(4S) 106 9 fb-1 140 fs

Babar collider asym.e+e- at U(4S) >106 91 fb-1 160 fs

Belle collider asym. e+e- at U(4S) >106 46.2 fb-1 160 fs

Fixed target :

Greater Lorentz boost, longer decay lengths

Use cut on detachment significance

Use reduced proper time : t’ ( L – Ns)/gbc

and so smaller acceptance/resolution corrections

- Event cleanliness
- e+e- collider
- g on fixed target
- Hadrons on fixed target

Collider : greater cleanliness of events

D° mixing measurements

Gianluigi Boca, Flavour Physics and CP Violation 2003

Decay rate to a final state | f from an initially pure |D0state ( | f CP | f

and |D0 CP |D0) :

G(D0phys→ f )(t) = | f | Hi | D0 |2 e-gt {¼ (1+|l|2)(eDgt/2 + e-Dgt/2 ) + (1-|l|2) cos(Dmt) +

+ ½ Re l eDgt/2+ e-Dgt/2+2isinDmt }

D0 decay formalism in short

D0 weak effective hamiltonian eigenstates :

|D1 = p |D0+ q |D0with eigenvaluem1 - ½ g1

|D2 = p |D0- q |D0 with eigenvaluem2- ½ g2

( Convention :Re (q/p) > 0)

Decay rate to a final state | f from an initially pure |D0state :

G(D0phys→ f )(t) = | f | Hi | D0 |2 e-gt {¼ (1+|l|2)(eDgt/2 + e-Dgt/2 ) + (1-|l|2) cos(Dmt) +

+ ½ Re l eDgt/2+ e-Dgt/2+2isinDmt }

with the definitions

Gianluigi Boca, Flavour Physics and CP Violation 2003

x Dm / g

f | Hi | D0

p

q

y Dg/ 2g (g1 - g2)/(g1 + g2)

f | Hi | D0

q

p

f | Hi | D0

f | Hi | D0

D0 decay formalism in short cont.d

where

g ½ ( g1 + g2 )

Dg g1 - g2

Dm m1 - m2

Gianluigi Boca, Flavour Physics and CP Violation 2003

t (D0→ K+p-)

-1 ycp

t (D0→ K-p+)

t (D0→ K+K-)

-1 ycp

t (D0→ K+K-)

t (D0→ K-p+)

-1 ycp

t (D0→ p+p-)

ycp = ycp = y=

g(CPeven) – g(CPodd)

g(CPeven) + g(CPodd)

Which are today the experimental possibilities to measure x and y ?

1) D0 lifetime ratios CF/CS to measure y

If we assume CP conservation in D0 decays then

Same measurement is possible in pp channel

Gianluigi Boca, Flavour Physics and CP Violation 2003

d WS(t)

dt

total RS

total WS

total RS

2) studies of Wrong Sign D0 hadronic decays

Existing examples :

- D0 → K+p- and c.c.
- D0 → K+p+p-p- and c.c.
- D0 → K*+(Ksp+) p- and c.c.
- D0 → K+p-p0 and c.c

All D0 must be tagged with D*

Experimentally one measures

or

Gianluigi Boca, Flavour Physics and CP Violation 2003

= g e-gtRD + (RD)y’gt + ½RMg2t2

= RD + (RD)y’ + RM

}

K+p- | Hi | D02

x’ = x cosd + y sind

y’ = y cosd – x sind

1

d WS(t)

RD

K-p+ | Hi | D02

=

Rotation by the strong phase d

K+p-| Hi | D0

( )

dt

total RS

K+p- | Hi | D0

K-p+| Hi | D0

K-p+ | Hi | D0

d arg

K+p-| Hi | D0

K-p+| Hi | D0

WS(t)

total RS

If CP is conserved in these decays then (taking as an example D0→ K+p-) :

with the definitions (PDG 2002 = Cleo conventions):

( )

= arg

RM ½(x2 + y2) = ½ (x’2 + y’2)

Gianluigi Boca, Flavour Physics and CP Violation 2003

If we allow CP violation, RD , x’, y’, RM of D0 → K+p- may differ from those of

D0 → K-p+ . There are various parametrizations for CP in literature;

I adopt here PDG 2002 (8 parameterstotal ) :

- g e-gtRD(1+AD)2+ (RD)(1+AM)(1+AD)y’-gt
+ ½(1+AM)2RMg2t2

= g e-gt{RD/(1+AD)2+ (RD)/(1+AM)(1+AD)y’+gt

+ ½RMg2t2 /(1+AM)2}

for D0 → K-p+

K+p- | Hi | D0

RD

AM | q/p | - 1

K+p-| Hi | D0

1

1

d WS(t)

d WS(t)

K-p+ | Hi | D0

)

(

dt

dt

total RS

total RS

K+p- | Hi | D0

K-p+| Hi | D0

K-p+ | Hi | D0

( )

f ½ arg

K+p- | Hi | D0

K-p+ | Hi | D0

K+p-| Hi | D0

K-p+| Hi | D0

AD - 1

K+p-| Hi | D0

K-p+| Hi | D0

for D0 → K+p-

where RM , x, y, x’, y’ are defined as previously; AD, AM, fandRD are real :

and

y’+ y’ cosf + x’ sinf = x cos(d-f) – xsin(d-f)

ADor AMorf 0

is signal of CP violation

y’- y’ cosf- x’ sinf = x cos(d+f) – xsin(d+f)

= RM (1+AM)2

= RM / (1+AM)2

= RM

= ge-gt½ RM g2t2

= ge-gt½(1+AM)2 RMg2t2

1

1

1

d WS(t)

d WS(t)

d WS(t)

dt

dt

dt

total RS

total RS

total RS

total WS

total WS

total WS

total RS

total RS

total RS

3) studies of WS D0 semileptonic decays

in order to measure RM :

- D0 → K+m-n and c.c.
- D0 → K+e-n and c.c.

D0 must be tagged with D*

If CP is conserved then

for D0 → K+l-n

If we allow CP violation then

and for D0 → K-l+n

= ge-gt½ RMg2t2 /(1+AM)2

Gianluigi Boca, Flavour Physics and CP Violation 2003

review of the D0 lifetime ratios

H.Nelson, hep-ex/9908021 (1999)

Predictions on x and y 10-2

Gianluigi Boca, Flavour Physics and CP Violation 2003

D0 → K-p- 214260 562 evts

D0 → K+K- 18306 18 evts

from 23.4 fb-1 data set

t (D0→ K-p+)

-1 ycp = (0.5 1.0 +0.7-0.8 ) %

t (D0→ K+K-)

review of the D0 lifetime ratios

Gianluigi Boca, Flavour Physics and CP Violation 2003

Belle is still running and certainly will improve this result

Gianluigi Boca, Flavour Physics and CP Violation 2003

review of the D result0 lifetime ratios cont.d

Moriond Conference 2003

BaBar

Babar parametrizes lifetimes ratios allowing for possible CP violations

t+ for D0 → K+K- or D0 → K+K-

t0 from D0 → K-p+

t- for D0 → K+K- or D0 → K+K-

<> = (+ + -) / 2

- A = (+ - -) / ( + + -)

- Y 0/<> - 1 Y A 0/ <>

If CP is conserved Y coincides with ycp and y

Gianluigi Boca, Flavour Physics and CP Violation 2003

Moriond Conference 2003 result

D0 Lifetime SamplesBaBar

- All BaBar data from 2000-2002 runs - 91 fb-1 were used.
- Four independent samples were isolated, three of which were tagged as D0 or D0

Gianluigi Boca, Flavour Physics and CP Violation 2003

A result

B

A

B

C

D

C

MeV/c2

GeV/c2

Moriond Conference 2003

D0 Lifetime SamplesBaBar

Unbinned likelihood fit to (m, t, t) ! (<> , 0, A)

m(D0) Fits

m = mD+- mD

Gianluigi Boca, Flavour Physics and CP Violation 2003

Moriond Conference 2003 result

Fit ResultsBaBar

- The fit uses all the data
Events within 15 MeV/c2 of D0 mass shown here.

- Background estimated from mass and lifetime fits.
- Statistical uncertainty small, e.g. for K-+ it is »0.9 fsec (»0.5% in y).

background

Gianluigi Boca, Flavour Physics and CP Violation 2003

Moriond Conference 2003 result

Summary of Lifetime Ratio ResultsBaBar

No CP

violation

BaBar is still running and certainly will improve this result

Gianluigi Boca, Flavour Physics and CP Violation 2003

D result0 → K-p- 20272 178 evts

D0 → K+K- 2463 65 evts

D0 → p+p- 930 37 evts

from 9.0 fb-1 data set

data tagged with D*

review of the D0 lifetime ratios cont.d

Publication : PRD 65 (2002)

CLEO II.V

ycp = (-1.2 2.5 1.4) %

Gianluigi Boca, Flavour Physics and CP Violation 2003

review of the D result0 lifetime ratios cont.d

Focus

Publication : PLB 485 (2000)

Data tagged or untagged with D*

D0 → K-p- 119738 evts

D0 → K+K- 10331 evts

ycp = (3.42 1.39 0.74) %

Gianluigi Boca, Flavour Physics and CP Violation 2003

review of the D result0 lifetime ratios cont.d

Publication PRL 83 (1998)

E791

D0 → K-p- 35000 evts

D0 → K+K- 3200 evts

tKK = 0.410 0.011 0.006

tKp= 0.413 0.003 0.004

ycp = (0.73 3.30) %

Gianluigi Boca, Flavour Physics and CP Violation 2003

summary of D result0 lifetime ratios

Also from BaBar first estimate

of CP violation parameter in lifetime

ratio measurements :

-2.0% < Dy < 0.4% 95% CL

Measurements already

at the 1 % level

Certainly

BaBar and Belle

will improve the

precision when more

data analysed

Gianluigi Boca, Flavour Physics and CP Violation 2003

review of the D result0 WS hadronic decays

(D*→p+) D0→ K+p-

Publication: BaBar preprint,

submitted to PRL 83 (2003)

BaBar

57.1 fb-1

120000 RS evts

430 WS evts

WS M(Kp) (GeV/c2)

WS dm (GeV/c2)

Open histogram : signal from fit

Shaded : backgrounds

= g resulte-gtRD + (RD )y’ gt + ½RM g2t2

1

1

d WS(t)

d WS(t)

dt

dt

total RS

total RS

(D*→p+) D0→ K+p-

BaBar

Performed fit to

- Four types of fit :
- Fit allowing CP violation terms ( D0 and D0 samples separately)
- Fit assuming CP conservation (D0 and D0 samples together)
- Fit assuming no mixing allowing CP violating terms
- Fit assuming CP conservation and no mixing

In their fit they defined the CP violating terms differently from PDG 2002

where + is for D0 and – for D0

BaBar definition of CP violating parameters :

(D*→ resultp+) D0→ K+p-

BaBar

x’ fit value is negative

x’ value fixed at 0

All results

consistent

with no CP

violation

review of the D result0 WS hadronic decays cont.d

(D*→p+) D0→ K+p-

Preliminary result: ICHEP02

46.2 fb-1

120795 371 RS evts

45031 WS evts

Wrong sign

Analysis of time-integrated WS/RS ratio

RWS = (0.372 0.025 +0.009-0.014 ) %

Gianluigi Boca, Flavour Physics and CP Violation 2003

Right sign

review of the D result0 WS hadronic decays cont.d

(D*→p+) D0→ K+p-

Focus

Publication : PRL 86 (2001)

36760 195 RS evts

14931 WS evts

Analysis of time-integrated WS/RS ratio

RWS = (0.404 0.0850.025) %

Focus is presently working on the time dependent analysis

Gianluigi Boca, Flavour Physics and CP Violation 2003

Performed fit of: result

1

d WS(t)

dt

total RS

review of the D0 WS hadronic decays cont.d

(D*→p+) D0→ K+p-

9 fb-1 dataset

13527 116 RS evts

44.8+9.7-8.7 WS evts

CLEO II.V

Publication : PRL 84 (2000)

- three types of fit :
- Fit allowing CP violation terms
- Fit assuming CP conservation
- Fit assuming no mixing allowing CP violating terms

Gianluigi Boca, Flavour Physics and CP Violation 2003

(D*→ resultp+) D0→ K+p-

CLEO II.V

All results

consistent

with no CP

violation and

no mixing

Gianluigi Boca, Flavour Physics and CP Violation 2003

summary of WS : D result0→ K+p-

Summary of RDCS in D0 → K+p- assuming no CP violation, no mixing

Gianluigi Boca, Flavour Physics and CP Violation 2003

summary of WS : D result0→ K+p-

Summary of mixing result of E791,

CLEO (2000) and

preliminary BaBar (2003)

BaBar preliminary

%

Focus semileptonics

expected sensitivity

%

review of the D result0 WS hadronic decays cont.d

(D*→p+) D0→ K+p+p-p-

9 fb-1 dataset

13735 RS evts

44.8 14 WS evts

CLEO II.V

Publication : PRD 64 (2001)

Analysis of time-integrated WS/RS ratio

(phase space averages

MC uncertainties)

RWS = (0.41+0.12-0.11 0.04) % * (1.07 0.10)

Gianluigi Boca, Flavour Physics and CP Violation 2003

review of the D result0 WS hadronic decays cont.d

(D*→p+) D0→ Ksp+p- Dalitz analysis

9 fb-1 dataset

Dalitz analysis 5299 evts

CLEO II.V

Publication : PRL 89 (2002)

Gianluigi Boca, Flavour Physics and CP Violation 2003

(D*→ resultp+) D0→ Ksp+p-

CLEO II.V

Rich resonant substructure shows WSD0→ K*+(890)p- + c.c. contributions.

First measure of strong phase d between CF D0→ K*-(890) p+

and DCS D0→ K*+(890)p- . Assuming CP conservation then :

( )

( )

K*+p- | Hi | D0

K*-p- | Hi | D0

d arg

= 1800 - arg

K*+p-| Hi | D0

K*+p-| Hi | D0

Gianluigi Boca, Flavour Physics and CP Violation 2003

B result(D0 →K*+p-)

= (0.50.2+0.5-0.1+0.4-0.1)%

B(D0→K*+p- )

(D*→p+) D0→ Ksp+p-

CLEO II.V

From table (neglecting error correlations) :

d = 1800 – ( 321103+15-3 - 150 22+2-5) = 90 150

Strong phase consistent with zero

Also measured

Also performed analysis separately D0 and D0 samples.

NO statistically significant CP violation effect.

Gianluigi Boca, Flavour Physics and CP Violation 2003

review of the D result0 WS hadronic decays cont.d

(D*→p+) D0→ Ksp+p-

Also Babar recently (Moriond Conference 2003)

showed the Dalitz plot of this channel

BaBar

K*(890) ! K0+

K*(890) ! K0- ?

Gianluigi Boca, Flavour Physics and CP Violation 2003

review of the D result0 WS hadronic decays cont.d

(D*→p+) D0→ K+p+p0

9 fb-1 dataset

389 WS evts

CLEO II.V

Publication : PRL 87 (2001)

RWS = (0.43+0.11-0.100.07)%

Gianluigi Boca, Flavour Physics and CP Violation 2003

publication : result

Int. J. Mod., Phys A:17 n.22

(2002)

B(D0→ Klp0)

= (0.88 0.9 0.9) %

B(D0→ Ksp0)

A

G(D0 → Ksp0) - G(D0→ Klp0)

= (0.06 0.05 0.05) %

G(D0 → Ksp0) + G(D0→ Ksp0)

a useful measurement from Belle

from 23.4 fb-1 data set

D* tagged sample

A is consistent with 0

If precision will improve in this measure in the future, it will be possible

impose constraints on dKp strong phase *

* Golowich and Pakvasa, PLB 505 (2001)

Gianluigi Boca, Flavour Physics and CP Violation 2003

review of the D result0 WS semileptonic decays

measure of RM without complications of DCS decays

Publication :

PRL 77 (1988)

Believe it or not,

thist is still the

only result in

literature!

E791

(D*→p+)D0 → K+m-n1.8 +12.1–11.0 WS evts

1267 44 RS evts

(D*→p+)D0 → K+e-n 4.4 +11.8–10.5 WS evts

1237 45 RS evts

(D*→ resultp+) D0→ K+l-n

}

RM = (0.16+0.42-0.37)% for D0 → K+e-n

RM = (0.11+0.30-0.27)%

RM = (0.06+0.44-0.40)% for D0 → K+m-n

review of the D0 WS semileptonic decays cont.d

E791

Simultaneous fit to the Q plot and the proper time that has a gt2 e-gt dependence.

CP violation NOT allowed in this fit

RM < 0.50% at 90 % CL

Gianluigi Boca, Flavour Physics and CP Violation 2003

review of the D result0 WS semileptonic decays cont.d

Future

Focus has a large sample of D0 semileptonic decays

and they are working to extract RM They expect

a sensitivity of 0.1 % at 95% CL

BaBar and Belle ?

Gianluigi Boca, Flavour Physics and CP Violation 2003

Experimental review of the result

charm particle

lifetime measurements

here I will show only plots of results after 2000

Gianluigi Boca, Flavour Physics and CP Violation 2003

u result

c

s

d

W-annihilation

Theory mini-summary

D+

D0

Ds

destructive

interference

term

B

A

R

Y

O

N

S

In the context of

OPE and 1/mc

expansion

different diagrams

can contribute to

the total decay width

constructive

interference

term

spectator

term

Charm meson lifetimes result

D+

Focus

Publication : PLB 537 (2002)

D+→K-p+p+

t = 1039.4 4.3 7.0 fs

Background subtracted

acceptance corrected

Definition of reduced proper time :

t’ ( L – Ns)/gbc

L primary-secondary detachment

s event by event error on L

N detachment cut ( L/s > N )

Gianluigi Boca, Flavour Physics and CP Violation 2003

Charm meson lifetimes resultcont.d

D+summary

My average : 1042.7 7.0

Gianluigi Boca, Flavour Physics and CP Violation 2003

Charm meson lifetimes resultcont.d

D0

Focus

D0→K-p+

Publication : PLB 537 (2002)

D0→K-p+p-p+

t = 409.6 1.1 1.5 fs

Background subtracted

acceptance corrected

K-p+

K-p+p+p-

Charm meson lifetimes resultcont.d

Selex

D0

}

D0→K-p+

Publication : PRL 86 (2001)

10210 evts

D0→K-p+p-p+

t = 407.9 6.0 4.3 fs

Total sample

Total sample

Background subtracted

acceptance corrected

Charm meson lifetimes resultcont.d

Selex

Ds

Ds+→K*0K+

Publication : PLB 523 (2001)

Ds+→ f p+

t = 472.5 17.2 6.6 fs

Gianluigi Boca, Flavour Physics and CP Violation 2003

Focus result

Y = 5668 95 evts

D+s

D+

signal region

sidebands

Charm meson lifetimes cont.d

Ds

Background subtracted,

acceptance corrected data

Ds+→ f p+

Acceptance

corrected

sidebands

Reduced proper time (ps)

Preliminary value (50% data sample )and no systematics yet :

t = 508.7 ± 5.1 fs

Gianluigi Boca, Flavour Physics and CP Violation 2003

Charm meson lifetime summary result

My

tDs/tD0 = 1.230.01

My

tD+/tD0 = 2.540.02

We are now at the 1 % level

in these ratios

Gianluigi Boca, Flavour Physics and CP Violation 2003

Focus result

Charm baryon lifetimes

Xc+

Xc+→X-p+p+ 300 evts

Publication : PLB 523 (2001)

Xc+→ S+ K-p+ 130 evts

Xc+→ LK-p+p+ 58 evts

t = 439 22 9 fs

Xc+→ pK-p+ 45 evts

Gianluigi Boca, Flavour Physics and CP Violation 2003

Charm baryon lifetimes resultcont.d

Publication : PRD 65 (2002)

Xc+

CLEO II.V

9 fb-1 data set

Xc+→X-p+p+ 250 18 evts

t = 503 47 18 fs

Gianluigi Boca, Flavour Physics and CP Violation 2003

Charm baryon lifetimes resultcont.d

Xc+ summary

Gianluigi Boca, Flavour Physics and CP Violation 2003

Focus result

Charm baryon lifetimes cont.d

Lc+

Lc+→ pK-p+

Publication : PRL (2002)

t = 204.6 3.4 2.5 fs

Background subtracted,

acceptance corrected data

Gianluigi Boca, Flavour Physics and CP Violation 2003

Charm baryon lifetimes resultcont.d

Lc+

CLEO II.V

Publication PRL 86 (2001)

9 fb-1 data set

Lc+→pK-p+ 4749 124 evts

t = 179.6 6.9 4.4 fs

Gianluigi Boca, Flavour Physics and CP Violation 2003

Charm baryon lifetimes resultcont.d

Publication : PRL 86 (2001)

Lc+

Selex

Lc+→pK-p+ 1630 evts

Reduced proper time

t = 198.1 7.0 5.6 fs

Gianluigi Boca, Flavour Physics and CP Violation 2003

Charm baryon lifetimes resultcont.d

Lc+summary

Gianluigi Boca, Flavour Physics and CP Violation 2003

Focus result

Charm baryon lifetimes cont.d

Xc0

}

Xc0→ X-p+

110 7 evts total

Publication : PLB 541 (2002)

Xc0→ W-K+

t = 118+14-12 5 fs

Background subtracted,

acceptance corrected data

Gianluigi Boca, Flavour Physics and CP Violation 2003

Charm baryon lifetimes resultcont.d

Xc0summary

Gianluigi Boca, Flavour Physics and CP Violation 2003

Focus result

Charm baryon lifetimes cont.d

Wc0

}

Wc0→ X-K-p+p+

64 14 evts total

Publication : PLB 561 (2003)

Wc0→ W-p+

t = 72 11 11fs

Background subtracted,

acceptance corrected data

Charm baryon lifetimes resultcont.d

Wc0 summary

Gianluigi Boca, Flavour Physics and CP Violation 2003

Charm baryon lifetime summary result

Charm baryons lifetime hierarchy

reasonably established now even for

Xc0 and Wc0

Gianluigi Boca, Flavour Physics and CP Violation 2003

Summary I result

D0 mixing measurements

- lifetime ratios :

measure of y at the level of 1 % , no indication of

CP violation

- D0 DCS hadronic decays measurements :

in D0→K+p- error in RD is at 10% level

time dependent analysis are constraining

more and more y’ and x’

more statistics allows fits including the CP violation

terms that in charm might be signal for new physics

Rwshave been measured for other DCS D0

decays

very interesting Dalitz analysis give direct

information of strong phase d

- D0Wrong Sign semileptonics decays : E791 glorious

old measure still resisting ... New results

should come shortly

Gianluigi Boca, Flavour Physics and CP Violation 2003

Summary II result

Charm particle lifetime measurements

- mesons : precision has reached the 1% level in the worst case

( Ds) or few per mils for D0and D+ thus challenging

and constraining theory calculations

- baryons : lifetime hierarchy established with Wc0as most

short lived

Gianluigi Boca, Flavour Physics and CP Violation 2003

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