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
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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 Xc , Lc , Xc0 , Wc0
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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
ee- at U(4S) 106 9
fb-1 140 fs Babar collider asym.
ee- at U(4S) gt106 91
fb-1 160 fs Belle collider asym.
ee- at U(4S) gt106
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
• ee- collider
• g on fixed target
• Hadrons on fixed target

Collider greater cleanliness of events
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Experimental review of the D mixing measurements
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D0 decay formalism in short
D0 weak effective hamiltonian eigenstates
D1? p D0? q D0? with eigenvalue
m1 - ½ g1
D2? p D0? - q D0? with eigenvalue
m2 - ½ g2
( Convention Re (q/p) gt 0 )
Decay rate to a final state f ? from an
initially pure D0? state G(D0phys ? f )(t)
? f Hi D0? 2 e-gt ¼ (1l2)(eDgt/2
e-Dgt/2 ) (1-l2) cos(Dmt)

½ Re ?l? eDgt/2 e-Dgt/2 ?2isin?Dmt??
with the definitions
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D0 decay formalism in short cont.d
where
g ? ½ ( g1 g2 )
Dg ? g1 - g2
Dm ? m1 - m2
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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
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2) studies of Wrong Sign D0 hadronic decays
Existing examples

• D0 ? Kp- and c.c.
• D0 ? Kpp-p- and c.c.
• D0 ? K(Ksp) p- and c.c.
• D0 ? Kp-p0
  and c.c

All D0 must be tagged with D
Experimentally one measures
or
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If CP is conserved in these decays then (taking
as an example D0 ? Kp-)
with the definitions (PDG 2002 Cleo
conventions)
( )
arg
RM ? ½(x2 y2) ½ (x2 y2)
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for D0 ? Kp-
where RM , x, y, x, y are defined as
previously AD, AM, f and RD are real
and
y ? y cosf x sinf x cos(d-f) xsin(d-f)
AD or AM or f ? 0 is signal of CP violation
y- ? y cosf - x sinf x cos(df) xsin(df)
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3) studies of WS D0 semileptonic decays
in order to measure RM

• D0 ? Km-n and c.c.
• D0 ? Ke-n and c.c.

D0 must be tagged with D
If CP is conserved then
for D0 ? Kl-n
If we allow CP violation then
and for D0 ? K-ln
ge-gt ½ RMg2t2 / (1AM)2
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review of the D0 lifetime ratios
H.Nelson, hep-ex/9908021 (1999)
Predictions on x and y ? 10-2
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review of the D0 lifetime ratios
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Belle is still running and certainly will improve
this result
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review of the D0 lifetime ratios cont.d
Moriond Conference 2003
BaBar
Babar parametrizes lifetimes ratios allowing for
possible CP violations
t for D0 ? KK- or D0 ? KK-
t0 from D0 ? K-p
t- for D0 ? KK- or D0 ? KK-
lt?gt (? ? -) / 2
A? (? - ? -) / (? ? -)
Y ? ? 0/lt?gt - 1 ?Y ? A? ? 0/ lt?gt
If CP is conserved Y coincides with ycp and y
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D0 Lifetime Samples
Moriond Conference 2003
BaBar

• 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

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D0 Lifetime Samples
Moriond Conference 2003
BaBar
Unbinned likelihood fit to (m, t, ?t) ! (lt?gt ,
?0, A?)
m(D0) Fits
?m mD?- mD
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Fit Results
Moriond Conference 2003
BaBar

• 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
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Summary of Lifetime Ratio Results
Moriond Conference 2003
BaBar
No CP violation
BaBar is still running and certainly will improve
this result
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review of the D0 lifetime ratios cont.d
Publication PRD 65 (2002)
CLEO II.V
ycp (-1.2 ? 2.5 ? 1.4)
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review of the D0 lifetime ratios cont.d
Focus
Publication PLB 485 (2000)
Data tagged or untagged with D
D0 ? K-p- 119738 evts D0 ? KK-
10331 evts
ycp (3.42 ? 1.39 ? 0.74)
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review of the D0 lifetime ratios cont.d
Publication PRL 83 (1998)
E791
D0 ? K-p- 35000 evts D0 ? KK-
3200 evts
tKK 0.410 ? 0.011 ? 0.006
tKp 0.413 ? 0.003 ? 0.004
ycp (0.73 ? 3.30)
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summary of D0 lifetime ratios
Also from BaBar first estimate of CP violation
parameter in lifetime ratio measurements -2.0
lt Dy lt 0.4 95 CL
Measurements already at the 1
level Certainly BaBar and Belle will improve
the precision when more data analysed
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review of the D0 WS hadronic decays
(D?p) D0 ? Kp-
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
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(D?p) D0 ? Kp-
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
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(D?p) D0 ? Kp-
BaBar
x? fit value is negative
x? value fixed at 0
All results consistent with no CP violation
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(D?p) D0 ? Kp-
BaBar
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review of the D0 WS hadronic decays cont.d
(D?p) D0 ? Kp-
Preliminary result ICHEP02
46.2 fb-1 120795 ? 371 RS evts 450?31 WS evts
Wrong sign
Analysis of time-integrated WS/RS ratio
RWS (0.372 ? 0.025 0.009 -0.014 )
Right sign
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review of the D0 WS hadronic decays cont.d
(D?p) D0 ? Kp-
Focus
Publication PRL 86 (2001)
36760 ? 195 RS evts 149?31 WS evts
Analysis of time-integrated WS/RS ratio
RWS (0.404 ? 0.085?0.025)
Focus is presently working on the time dependent
analysis
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review of the D0 WS hadronic decays cont.d
(D?p) D0 ? Kp-
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

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(D?p) D0 ? Kp-
CLEO II.V
All results consistent with no CP violation and
no mixing
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summary of WS D0 ? K p-
Summary of RDCS in D0 ? K p- assuming no CP
violation, no mixing
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summary of WS D0 ? K p-
Summary of mixing result of E791, CLEO (2000)
and preliminary BaBar (2003)
BaBar preliminary

Focus semileptonics expected sensitivity

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review of the D0 WS hadronic decays cont.d
(D?p) D0 ? Kpp-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 (0.410.12-0.11 ?0.04) (1.07 ?0.10)
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review of the D0 WS hadronic decays cont.d
(D?p) D0 ? Kspp- Dalitz analysis
9 fb-1 dataset Dalitz analysis 5299 evts
CLEO II.V
Publication PRL 89 (2002)
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(D?p) D0 ? Kspp-
CLEO II.V
Rich resonant substructure shows WS D0?
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
( )
( )
? Kp- Hi D0?
? K-p- Hi D0?
d ? arg
1800 - arg
? Kp- Hi D0?
? Kp- Hi D0?
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(D?p) D0 ? Kspp-
CLEO II.V
From table (neglecting error correlations)
d 1800 ( 321?10?315-3 - 150 ? 2?22-5)
90 ? 150
Strong phase consistent with zero
Also measured
Also performed analysis separately D0 and D0
samples. NO statistically significant CP
violation effect.
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review of the D0 WS hadronic decays cont.d
(D?p) D0 ? Kspp-
Also Babar recently (Moriond Conference
2003) showed the Dalitz plot of this channel
BaBar
K(890) ! K0?
K(890) ! K0?- ?
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review of the D0 WS hadronic decays cont.d
(D?p) D0 ? Kpp0
9 fb-1 dataset 38?9 WS evts
CLEO II.V
Publication PRL 87 (2001)
RWS (0.430.11-0.10?0.07)
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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)
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review of the D0 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 ? Km-n 1.8 12.111.0 WS evts
1267 ? 44 RS
evts
(D?p) D0 ? Ke-n 4.4 11.810.5 WS evts
1237 ? 45 RS
evts
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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 lt 0.50 at 90 CL
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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 ?
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Experimental review of the charm particle
lifetime measurements
here I will show only plots of results after 2000
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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
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Charm meson lifetimes
D
Focus
Publication PLB 537 (2002)
D ?K-pp
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 gt N )
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Charm meson lifetimes cont.d
D summary
My average 1042.7 ? 7.0
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Charm meson lifetimes cont.d
D0
Focus
D0 ?K-p
Publication PLB 537 (2002)
D0 ?K-pp-p
t 409.6 ? 1.1 ? 1.5 fs
Background subtracted acceptance corrected
K-p
K-ppp-
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Charm meson lifetimes cont.d
D0
Selex

D0 ?K-p
Publication PRL 86 (2001)
10210 evts
D0 ?K-pp-p
t 407.9 ? 6.0 ? 4.3 fs
Total sample
Total sample
Background subtracted acceptance corrected
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Charm meson lifetimes cont.d
D0 summary
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Charm meson lifetimes cont.d
Ds
Selex
Ds ?K0K
Publication PLB 523 (2001)
Ds ? f p
t 472.5 ? 17.2 ? 6.6 fs
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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
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Charm meson lifetimes cont.d
Ds summary
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Charm meson lifetime summary
My tDs/tD0 1.23?0.01
My tD/tD0 2.54?0.02
We are now at the 1 level in these ratios
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Charm baryon lifetimes
Xc
Xc ?X-pp 300 evts
Publication PLB 523 (2001)
Xc ? S K-p 130 evts
Xc ? LK-pp 58 evts
t 439 ? 22 ? 9 fs
Xc ? pK-p 45 evts
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Charm baryon lifetimes cont.d
Publication PRD 65 (2002)
Xc
CLEO II.V
9 fb-1 data set
Xc ?X-pp 250 ? 18 evts
t 503 ? 47 ? 18 fs
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Charm baryon lifetimes cont.d
Xc summary
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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
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Charm baryon lifetimes cont.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
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Charm baryon lifetimes cont.d
Publication PRL 86 (2001)
Lc
Selex
Lc ? pK-p 1630 evts
Reduced proper time
t 198.1 ? 7.0 ? 5.6 fs
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Charm baryon lifetimes cont.d
Lcsummary
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Charm baryon lifetimes cont.d
Xc0

Xc0 ? X-p
110 ? 7 evts total
Publication PLB 541 (2002)
Xc0 ? W-K
t 11814-12 ? 5 fs
Background subtracted, acceptance corrected data
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Charm baryon lifetimes cont.d
Xc0summary
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Charm baryon lifetimes cont.d
Wc0

Wc0 ? X-K-pp
64 ? 14 evts total
Publication PLB 561 (2003)
Wc0 ? W-p
t 72 ? 11 ? 11 fs
Background subtracted, acceptance corrected data
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Charm baryon lifetimes cont.d
Wc0 summary
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Charm baryon lifetime summary
Charm baryons lifetime hierarchy reasonably
established now even for Xc0 and Wc0
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Summary I
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 ?Kp- 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 d - D0 Wrong Sign
semileptonics decays E791 glorious
old measure still resisting ...
New results should
come shortly
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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 Wc0 as
most short lived