flavour physics and cp violation

Gianluigi Boca, Flavour Physics and CP Violation 2003

Flavour Physics and CP violation

D0 mixingand

Charm lifetimesAn experimental review

Gianluigi BocaPavia University and INFN

Italy

Paris, June 3rd 2003


Outline

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 : c+ , c

+ , c0 , c

0


Experiments mainly considered in this reviewExperiments mainly considered in this review

experiment beam approx. Luminosity Average t

type type total charm

E791 fixed target 500 GeV 40 fsFocus fixed target up to 300 Gev 30 fsSelex fixed target 600 GeV , p 104 20 fsCleo collider e+eat Sfb140 fsBabar collider asym. e+e at (4S) >10 91 fb 160 fsBelle collider asym. e+e at (4S) >10 46.2 fb 160 fs

Event cleanliness1. e+ecollider2. on fixed target3. Hadrons on fixed target

Fixed target :Greater Lorentz boost, longer decay lengthsUse cut on detachment significanceUse reduced proper time : t’ ( L – N)/cand so smaller acceptance/resolution corrections

Collider : greater cleanliness of events


D0 decay formalism in shortD0 decay formalism in short

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

(D0phys → f )(t) = | f | Hi | D0 |2 et {¼ 2et2 + et2) 2 cos(mt) +

½ Re et2 et2 2isinmt }

with the definitions

Decay rate to a final state | f from an initially pure |D0state ( | f CP | f and |D0 CP |D0) :

(D0phys → f )(t) = | f | Hi | D0 |2 et {¼ 2et2 + et2) 2 cos(mt) +

½ Re et2 et2 2isinmt }

D0 weak effective hamiltonian eigenstates :

|D1 = p |D0 + q |D0 with eigenvalue m½

|D2 = p |D0 q |D0 with eigenvalue m2 ½ 2

( Convention : Re (q/p) )


D0 decay formalism in short cont.dD0 decay formalism in short cont.d

where

f | Hi | D0 f | Hi | D0

qp

f | Hi | D0 f | Hi | D0

pq

½2

m mm2

2

x m

y 2 (22


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

1) D0 lifetime ratios CF/CS to measure y1) D0 lifetime ratios CF/CS to measure y

If we assume CP conservation in D0 decays then

Same measurement is possible in channel

D0→ K

D0→ ycp

D0→ K

D0→ Kycp

D0→ K

D0→ Kycp

ycp = ycp = y =(CP even) – (CP odd)

(CP even) + (CP odd)


2) studies of Wrong Sign D0 hadronic decays

Existing examples :

a) D0 → K+ and c.c.b) D0 → K+ and c.c.c) D0 → K*Ks and c.c.d) D0 → K and c.c

All D0 must be tagged with D*

Experimentally one measures

ortotal RS

d WS(t)

dt

total RS

total WS


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

with the definitions (PDG 2002 = Cleo conventions):

total RS

d WS(t)

dt

etRD + (RD)y’t + ½RM2t2

total RS

WS(t)RD + (RD)y’ + RM

| Hi | D0 2

K+| Hi | D0 RD = | Hi | D0

2

K+| Hi | D0

x’ = x cos + y siny’ = y cos – x sin

Rotation by the strong phase }= arg ( ) | Hi | D0

K+| Hi | D0 arg ( ) | Hi | D0

K+| Hi | D0

RM ½(x2 + y2) = ½ (x’2 + y’2)


for D0 → K+

total RS

d WS(t)

dt

etRD(1+AD)2+ (RD)(1+AM)(1+AD)y’t + ½(1+AM)2RM2t2

)( ½ arg | Hi | D0 K+| Hi | D0

| Hi | D0 K+| Hi | D0

If we allow CP violation, RD , x’, y’, RM of D0 → K+ may differ from those ofD0 → K+ . There are various parametrizations for CP in literature;I adopt here PDG 2002 (8 parameters total ) :

total RS

d WS(t)

dt

= et{RD/(1+AD)2+ (RD)/(1+AM)(1+AD)y’t + ½RM2t2 /(1+AM)2} for D0 → K

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

| Hi | D0 K+| Hi | D0

AD | Hi | D0 K+| Hi | D0 ( )

| Hi | D0 K+| Hi | D0

RD | Hi | D0 K+| Hi | D0

AM | q/p |

and

y’+ y’ cos + x’ sin = x cos() – xsin()y’ y’ cos x’ sin = x cos() – xsin()

AD or AM or 0is signal of CP violation


3) studies of WS D0 semileptonic decays

in order to measure RM : a) D0 → K+ and c.c.b) D0 → K+e and c.c.

D0 must be tagged with D*If CP is conserved then

If we allow CP violation then

total RS

d WS(t)

dt

= et ½ RM 2t2

total RS

total WS= RM

total RS

d WS(t)

dt

= et ½(+AM)2 RM2t2

for D0 → K+l

total RS

d WS(t)

dt

= et ½ RM2t2 / (1+AM)2

and for D0 → Kl

total RS

total WS= RM (+AM)2

total RS

total WS= RM / (1+AM)2


review of the D0 lifetime ratios review of the D0 lifetime ratios

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

Predictions on x and y 102


review of the D0 lifetime ratios review of the D0 lifetime ratios

D0 → K 214260 562 evtsD0 → K+K 18306 18 evts

from 23.4 fb data set

publication : PRL88 (2002)

D0→ K

D0→ Kycp = (0.5 1.0 +0.7 0.8 ) %


Belle is still running and certainly will improve this result


review of the D0 lifetime ratios cont.d review of the D0 lifetime ratios cont.d

Moriond Conference 2003BaBar

Babar parametrizes lifetimes ratios allowing for possible CP violations

+ for D0 → K+K or D0 → K+K 0 from D0 → K

for D0 → K+K or D0 → K+K

A = ( + - ) / ( + + ) <> = ( + + ) / 2

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

If CP is conserved Y coincides with ycp and y


D0 Lifetime Samples• 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

BaBar

Moriond Conference 2003


A B

C D

GeV/c2

D0 Lifetime Samples

m(D0) Fits m = mD+- mD

A B

C

MeV/c2

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

BaBar



Fit Results• 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).

BaBar


background


Summary of Lifetime Ratio ResultsBaBar

BaBar is still running and certainly will improve this result


No CPviolation



Publication : PRD 65 (2002)CLEO II.V

D0 → K 20272 178 evtsD0 → K+K 2463 65 evtsD0 → 930 37 evts

from 9.0 fb data setdata tagged with D*

ycp = .22.. %



Publication : PLB 485 (2000)

D0 → K 119738 evtsD0 → K+K 10331 evts

Data tagged or untagged with D*

ycp = .2.. %

Focus



Publication PRL 83 (1998)E791

D0 → K 35000 evtsD0 → K+K 3200 evts

ycp = .. %

KK = .. 0.006 K = .. 0.004


summary of D0 lifetime ratios summary of D0 lifetime ratios

Measurements already at the 1 % levelCertainlyBaBar and Bellewill improve theprecision when moredata analysed

Also from BaBar first estimateof CP violation parameter in lifetime

ratio measurements :2. < y < 0.4% 95% CL


review of the D0 WS hadronic decays review of the D0 WS hadronic decays

Publication: BaBar preprint,submitted to PRL 83 (2003)

(D*→+) D0 → K(D*→+) D0 → K

BaBar 57.1 fb

120000 RS evts430 WS evts

WS M(K) (GeV/c2) WS m (GeV/c2)

Open histogram : signal from fitShaded : backgrounds


BaBar

total RS

d WS(t)

dt

Performed fit to

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

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

total RS

d WS(t)

dt

etRD

+ (RD )y’ t + ½RM

2t2

where + is for D0 and – for D0

BaBar definition of CP violating parameters :

(D*→+) D0 → K(D*→+) D0 → K


BaBar

x’ fit value is negative x’ value fixed at 0

(D*→+) D0 → K(D*→+) D0 → K

All resultsconsistent

with no CPviolation


BaBar (D*→+) D0 → K(D*→+) D0 → K


review of the D0 WS hadronic decays cont.d review of the D0 WS hadronic decays cont.d

Preliminary result: ICHEP02

(D*→+) D0 → K(D*→+) D0 → K

46.2 fb

120795 371 RS evts45031 WS evts

Right sign

Wrong sign

RWS = (0.372 0.025 +0.009 . ) %

Analysis of time-integrated WS/RS ratio



Publication : PRL 86 (2001)

(D*→+) D0 → K(D*→+) D0 → K

36760 195 RS evts14931 WS evts

RWS = (0.404 0.0850.025) %

Focus

Analysis of time-integrated WS/RS ratio

Focus is presently working on the time dependent analysis




(D*→+) D0 → K(D*→+) D0 → K

9 fbdataset13527 116 RS evts

44.8 +9.7 . WS evts

CLEO II.V

three types of fit :a) Fit allowing CP violation termsb) Fit assuming CP conservationc) Fit assuming no mixing allowing CP violating terms

total RS

d WS(t)

dt

Performed fit of:


(D*→+) D0 → K(D*→+) D0 → KCLEO II.V

All resultsconsistent

with no CPviolation and

no mixing


summary of WS : D0 → K+ summary of WS : D0 → K+

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


summary of WS : D0 → K+ summary of WS : D0 → K+

Summary of mixing result of E791, CLEO (2000) and preliminary BaBar (2003)

BaBar preliminary

Focus semileptonicsexpected sensitivity

%

%



Publication : PRD 64 (2001)

(D*→+) D0 → K(D*→+) D0 → K

9 fbdataset13735 RS evts

44.8 14 WS evts

CLEO II.V

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

Analysis of time-integrated WS/RS ratio(phase space averages

MC uncertainties)




(D*→+) D0 → KsDalitz analysis(D*→+) D0 → KsDalitz analysis

9 fbdatasetDalitz analysis 5299 evts

CLEO II.V


( )

(D*→+) D0 → Ks(D*→+) D0 → KsCLEO II.V

Rich resonant substructure shows WS D0→ K*+(890) + c.c. contributions.

First measure of strong phase between CF D0→ K890)

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

K | Hi | D0 K*+| Hi | D0

arg arg( ) | Hi | D0 K*+| Hi | D0


(D*→+) D0 → Ks(D*→+) D0 → KsCLEO II.V

From table (neglecting error correlations) :

B(D0 → )B(D0 → K*+ )

..2..

..

= 1800 – ( 2222

) = 90 150

Strong phase consistent with zero

Also measured

Also performed analysis separately D0 and D0 samples. NO statistically significant CP violation effect.


BaBarAlso Babar recently (Moriond Conference 2003)showed the Dalitz plot of this channel

(D*→+) D0 → Ks(D*→+) D0 → Ks


K*(890) ! K0+

K*(890) ! K0- ?




(D*→+) D0 → K+(D*→+) D0 → K+

9 fbdataset389 WS evts

CLEO II.V

RWS = (0.43+0.11.0.07)%


a useful measurement from Bellea useful measurement from Belle

from 23.4 fb data setD* tagged sample

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

(2002)

D0→ Kl

D0→ Ks= (0.88 0.9 0.9 ) %

A is consistent with 0

(D0 → Ks0)D0→ Kl

(D0 → Ks0) + D0→ Ks= (0.06 0.05 0.05 ) %A

If precision will improve in this measure in the future, it will be possibleimpose constraints on K strong phase *

* Golowich and Pakvasa, PLB 505 (2001)


review of the D0 WS semileptonic decays review of the D0 WS semileptonic decays

Publication : PRL 77 (1988)Believe it or not,thist is still theonly result in

literature!

E791measure of RM without complications of DCS decays

(D*→+) D0 → K 1.8 +12.1–11.0 WS evts

1267 44 RS evts

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

1237 45 RS evts


review of the D0 WS semileptonic decays cont.d review of the D0 WS semileptonic decays cont.d

RM < 0.50% at 90 % CL

(D*→+) D0 → Kl(D*→+) D0 → KlE791

Simultaneous fit to the Q plot and the proper time that has a t2 et dependence.CP violation NOT allowed in this fit

RM = (0.16+0.42.)% for D0 → K+e

RM = (0.06+0.44.)% for D0 → K

RM = (0.11+0.30.2)% }


review of the D0 WS semileptonic decays cont.d review of the D0 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 ?


here I will show only plots of results after 2000


Theory mini-summaryTheory mini-summary

c

s

u

d

W-annihilation

In the context ofOPE and /mc

expansiondifferent diagramscan contribute tothe total decay width

D+

D0

Ds

BARYON

S

destructiveinterference

term

constructiveinterference

term

spectatorterm


Charm meson lifetimesCharm meson lifetimes

D+D+Focus


D+ →

= 1039.4 4.3 7.0 fs

Background subtractedacceptance corrected

Definition of reduced proper time :t’ ( L – N)/c

L primary-secondary detachment event by event error on LN detachment cut ( L/ > N )


Charm meson lifetimes cont.dCharm meson lifetimes cont.d

D+ summaryD+ summaryMy average : 1042.7 7.0


K+


D0D0Focus


D0 →

= 409.6 1.1 1.5 fs


K+

D0 →



D0D0Selex


= 407.9 6.0 4.3 fs


D0 →

D0 →

Total sample Total sample

} 10210 evts



D0 summaryD0 summary



DsDs


Ds+ →

= 472.5 17.2 6.6 fs

Ds+ →K*0

Selex



Focus DsDs

Preliminary value (50% data sample ) and no systematics yet : = 508.7 ± 5.1 fs

Preliminary value (50% data sample ) and no systematics yet : = 508.7 ± 5.1 fs

Background subtracted,acceptance corrected data

Acceptance corrected sidebands

Reduced proper time (ps)

Y = 5668 95 evts

D+D+

s

sidebands

signal region

Ds+ →



Ds summaryDs summary


Charm meson lifetime summaryCharm meson lifetime summary

MyDs

/D0 = 1.230.01

MyD+/D0 = 2.540.02

We are now at the % levelin these ratios


Charm baryon lifetimesCharm baryon lifetimes

c+c+Focus

Publication : PLB 523 (2001)c

+ →300 evtsc

+ →130 evts

c+ → pK45 evts

c+ →58 evts = 439 22 9 fs


Charm baryon lifetimes cont.dCharm baryon lifetimes cont.d

c+c+ Publication : PRD 65 (2002)CLEO II.V

c+ →250 18 evts 9 fb data set

= 503 47 18 fs



c+ summaryc+ summary



c+c+Focus

Publication : PRL (2002)

= 204.6 3.4 2.5 fs

c+ → pK




c+c+

Publication PRL 86 (2001)CLEO II.V

c+ →p4749 124 evts 9 fb data set

= 179.6 6.9 4.4 fs



c+c+Selex Publication : PRL 86 (2001)

= 198.1 7.0 5.6 fs

c+ →p1630 evts

Reduced proper time



c+summaryc+summary



c0c0Focus



= 118+142 5 fs

c0 →

c0 →

} 110 7 evts total



c0summaryc0summary



c0c0Focus



= 72 11 11 fs

c0 →

c0 →

} 64 14 evts total



c0 summaryc0 summary


Charm baryon lifetime summaryCharm baryon lifetime summary

Charm baryons lifetime hierarchyreasonably established now even for

c0 and c

0


Summary ID0 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 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 Rws have been measured for other DCS D0 decays very interesting Dalitz analysis give direct information of strong phase

- D0 Wrong Sign semileptonics decays : E791 glorious old measure still resisting ... New results should come shortly


Summary II

Charm particle lifetime measurements- mesons : precision has reached the 1% level in the worst case ( Ds ) or few per mils for D0 and D+ thus challenging and constraining theory calculations- baryons : lifetime hierarchy established with c

0 as most short lived

flavour physics and cp violation

Documents

p d0 q d0

p d0 q d0

example d0

cp violation thenfor

flavour physics

d0 lifetime ratiosh

pure d0 state

cp conservation