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Summary. B factories and LHCb. CP & T violation only in K 0 system ???. Since 1964, CP and or T violation was searched for in other systems than K 0 , other particles decays, EDM. No other signal until 2001... . B a B ar (SLAC) and B elle (KEK). 8 GeV electrons. 3.5GeV positron.

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summary
Summary

B factories and LHCb

A. Bay LPHE EPF Lausanne

cp t violation only in k 0 system
CP & T violation only in K0 system ???

Since 1964, CP and or T violation was searched for in other

systems than K0, other particles decays, EDM...

No other signal until 2001...

A. Bay LPHE EPF Lausanne

b a b ar slac and b elle kek
BaBar (SLAC) and Belle (KEK)

8 GeV

electrons

3.5GeV positron

in 2001: observation of CP violation in the B meson

system, using "asymmetric collider" B factories.

KEKB machine:

 production of

(4s) (10.58GeV/c2)

 = 0.425

(4s)  B0 B0

 B+ B-

A. Bay LPHE EPF Lausanne

slide4
KEKB

24% Y(4s)

76% continuum

year 2003: crossing the(psychological) luminosity

barrier of 1034 cm-2s-1

1.5807 1034

on 18-May-2005

A. Bay LPHE EPF Lausanne

luminosity trend in the last 30 years
Luminosity trend in the last 30 years

Peak luminosity cm-2 s-1

A. Bay LPHE EPF Lausanne

b a b ar and b elle
BaBar and Belle

Study of the time dependent asymmetry in decay rates of

B0 and anti-B0

CP violated  S ≠ 0

Dm = mass difference of "mass eigenstates" ~ 0.49 1012h/s

A. Bay LPHE EPF Lausanne

cp measurements at b factories
CP measurements at B factories

Difficult: B0 mean life 1.54 10-12 s. Lorentz boost very small.

B factories are asymmetric: the c.m. is moving.

The two B decay at different position ~ on the z axis.

We measure de difference Dz of the 2 vertices. Dr is small.

Δz  cβγΔt ~ 200 m at Belle

e

(4s)

n

J/Y

Ks

D

Dr

Dz

z1

z2

z

A. Bay LPHE EPF Lausanne

cp measurements at b factories1
CP measurements at B factories

(4s)

J/Y

Ks

Dz

z1

z2

z

fCP

region of

B0 & B0

coherent

evolution

B0 and anti-B0 oscillate coherently (QMentangled state).

When the first decays, the other is known to be of the opposite

flavour  use the other side to infer the flavour, B0 or anti-B0,

of the fCP parent

e

n

D

A. Bay LPHE EPF Lausanne

belle experiment
Belle experiment

Started in 1999

~300 physicists from

~60 institutes in

14 countries.

Aerogel Cherenkov

n=1.015~1.030

SC solenoid 1.5T

3.5GeV e+

CsI(Tl) 16X0

E/E ~ 1.8% @1GeV

TOF counter

8GeV e-

Central Drift Chamber

He/C2H5

(Pt/Pt)2=(0.0019 Pt)2+(0.0030)2

m / KL detection

14/15 layers of

RPC+Fe

 : efficiency > 90%

<2% fake at p > 1GeV/c

Particle ID :

dE/dx in CDCdE/dx =6.9%

TOFTOF = 95ps

Aerogel Cerenkov ACC

Efficiency = ~90%,

Fake rate = ~6% 3.5GeV/c

Si Vertex detector

3 layers  mid 2003

now 4 layers

Impact parameter resolution

 55m for p=1GeV/c

A. Bay LPHE EPF Lausanne

b e l l e
Belle

ACC

Silicon Vertex Detector SVD

Impact parameter resolution

 55m for p=1GeV/c at normal incidence

Central Drift Chamber CDC

(Pt/Pt)2 = (0.0019 Pt)2 + (0.0030)2

K/ separation :

dE/dx in CDC dE/dx =6.9%

TOFTOF = 95ps

Aerogel Cerenkov ACC

Efficiency = ~90%,

Fake rate = ~6% 3.5GeV/c

, e : CsI crystals ECL

E/E ~ 1.8% @ E=1GeV

e : efficiency > 90%

~0.3% fake for p > 1GeV/c

KL and  : KLM (RPC)

 : efficiency > 90%

<2% fake at p > 1GeV/c

400 fb-1

4 108 B pairs

~ 8 m

A. Bay LPHE EPF Lausanne

belle micro vertex detector
Belle micro-vertex detector

spatial resolution

for Blepton + X

sz (lepton) ~ 100 mm

A. Bay LPHE EPF Lausanne

belle event
Belle event

A. Bay LPHE EPF Lausanne

particle id in belle
Particle ID in Belle

dE/dx

TOF

Barrel ACC

cut

Endcap ACC

p (GeV/c)

Particle ID uses information from

ACC, TOF, dE/dx( CDC)

A. Bay LPHE EPF Lausanne

experimental program measure sides and angles of the ckm matrix
Experimental program: measure sides and anglesof the CKM matrix

a

b quark

t quark

~Vub

g

b

~Vtd

decays

~Vcb

oscillations

CP asymmetries

* CP violated in the SM => the area of triangle 0

* Any inconsistency could be a signal of the existence of phenomena

not included in the SM

Use B mesons

phenomenology

A. Bay LPHE EPF Lausanne

analysis and results
Analysis and results

a

~Vub

~Vtd

g

b

~Vcb

  • Continuum rejection
  • Kinematics at the Y(4s)
  • The Unitary triangle:
  • determination of Vub
  • " Vcb
  • " Vtd
  • " b
  • " a
  • " g
  • No time for other topics

A. Bay LPHE EPF Lausanne

continuum rejection
Continuum rejection

24% Y(4s)

76% continuum

Build Likelihood L for B and qq hypothesis

using event shape variables and cos qB

BB

cut

qq

from event topology which

is ~spherical for BB,

jet like for continuum

and angular distributions

0 0.2 0.4 0.6 0.8 1

A. Bay LPHE EPF Lausanne

how to find a b meson kinematics variables at the y 4s
How to find a B meson?Kinematics variables at the Y(4S)

GeV/c2

0.2

DE

0

-0.2

Mbc

5.2 5.24 5.28

GeV/c2

Gather candidates B

and calculate (pB,EB).

Boost to c.m. (pB*,EB*)

with

Example:

B- D0p-

"beam constrained mass"

A. Bay LPHE EPF Lausanne

determination of vcb
Determination of Vcb

B0

World Average:

|Vcb| (inclusive) (42.0  0.6  0.8) 10-3

|Vcb| (exclusive) (40.2 +2.1) 10-3

-1.8

D0p+

Vcb

W-

q

c

b

D*+

d

g(y) known function of y

F(y) hadronic form factor

plus ~5% error

on F(1)

A. Bay LPHE EPF Lausanne

(Moriond excl. D*:

CLEO: 46.9 10-3

BABAR: 48.2 10-3)

determination of vub
Determination of Vub

Vub

W

b

u

hep-ex/0305037, with n reconstruction

|Vub| (10-3) = 3.960.17(stat) 0.44(syst)

0.29(theo) 0.34(bc) 0.26(bu)

bc

bu

Exemple: use lepton momentum distribution

from inclusive semileptonic decays

0 1 2 3

Lepton momentum

(in c.m.)

GeV/c

Less than 10% of the

spectrum background free

Average(inclusive) Vub=(4.12±0.13±0.60)10-3

A. Bay LPHE EPF Lausanne

determination of vtd
Determination of Vtd

Vtd

B0

Starting from a pure sample

of B0, for instance,

a B0component builds up

in a time scale of a few ps:

t

b

d

B0

B0

W

W

t

d

b

Probability

1

B0

measure oscillation frequency

0 3 6 9 ps

A. Bay LPHE EPF Lausanne

d m d with di lepton events
Dmd with di-lepton events

* B0 and B0 oscillate coherently (QMentangled state).

When the first decays, the other is known to be of the opposite

flavour.

* Tag B flavour from semileptonic B0 X-l+n B0 X+l-n

region of

B0 & B0

coherent

evolution

t ~ Dz/cbg

* KEK-B boost  <Δz>  cβγt ~ 200 m

e+

n

(4s)

m-

X

n

Y

Dz

z

z1

z2

A. Bay LPHE EPF Lausanne

d m d from di lepton events 2
Dmd from di-lepton events .2

Missing mass

N

GeV2

-12 -8 -4 0

Background: B+ X0l+n B- X0l-n

Selection strategy of the "soft pion tag"

B0 D*-l+n Br3%

 D0p- Br70%

(Frederic Ronga, PhD thesis, 2003)

  • Event selection:
  • - 1st lepton P*> 1.8 GeV
  • 1 pion of opposite sign P* < 1 GeV
  • 2nd lepton P*> 1.3 GeV
  • - cut on Mn2

A. Bay LPHE EPF Lausanne

d m d from di lepton events 3
Dmd from di-lepton events .3

SS

OS

-2 -1 0 1 2

-2 -1 0 1 2

Dz (mm)

Dz (mm)

Dz (mm)

0 1 2

Get Dz distributions

for "Same Sign"

and "Opposite Sign"

leptons couples

and fit for Dmd...

OS

SS

J/  l+ l- to

infer resolution

A. Bay LPHE EPF Lausanne

d m d and vtd
Dmd and Vtd

average

F. Ronga

HEP-PH/0206171

B decay

constant

Bag

parameter

{

~20% error !

 |Vtd | ~ (8±2)10-3

A. Bay LPHE EPF Lausanne

ut sides
UT sides

Excluded area has <0.05 CL

The

Unitary

Triangle

inferred from its sides

and from

K0 data

From K0

Dmd & Dms

0

1

Vub/Vcb

A. Bay LPHE EPF Lausanne

b from b 0 j y ks
bfrom B0J/y Ks

c

J/y

c

Vcb

b

s

B0

Ks

d

c

b

B0

d

}

SM:

sin2b

Golden Channel

CKM phase = 0

J/y

c

Vcb

Vtd

Vtb

d

s

CKM phase  0 !

B0

Ks

Vtb

Vtd

Interference between the 2 amplitudes gives a "time-dependent CPV"

A. Bay LPHE EPF Lausanne

any direct cp violation
Any "direct" CP violation ?

c

J/y

c

Vcb

b

s

B0

Ks

d

c

b

s

}

}

SM:

0

sin2b

CKM phase = 0

J/y

t

Vtb

c

Vts

CKM phase = 0

B0

d

Ks

No "direct CPV" expected in SM in B J/y Ks, but who knows ?...

A. Bay LPHE EPF Lausanne

time dependent asymmetry measurement
Time dependent asymmetry measurement

Need to "tag" the flavour: B0 or B0.

B0 and B0 oscillate coherently (QMentangled state)

 use the other side to infer the flavour

(4s)

J/Y

Ks

Dz

z1

z2

z

e

fCP

n

D

region of

B0 & B0

coherent

evolution

ftag

t ~ Dz/cbg

A. Bay LPHE EPF Lausanne

b ccs reconstruction
b ccsreconstruction

b ccs(J/KL excluded)

B 0 J/KL

140 fb-1, 152MBB pairs

5417 events are used in the fit.

pB GeV/c

A. Bay LPHE EPF Lausanne

a large cp asymmetry has been observed
A large CP asymmetry has been observed!

World average (October 2005):

SCP = 0.726 ± 0.037

ACP~ 0, compatible with no direct CPV

SM: SCP = sin(2b) =>b =23.7° (or 66.3°)

J/KL

J/KL is OK

A. Bay LPHE EPF Lausanne

sm km model is verified
SM & KM model is verified !

b = 23.7°± 2.1°

= 66.3°± 2.1°

A. Bay LPHE EPF Lausanne

ut with sin2 b
UT with sin2b

The

Unitary

Triangle

fit including sides,

K0 data,

and

sin2b

A. Bay LPHE EPF Lausanne

b sss a b 0 f ks puzzle
b sss, a B0f Ks puzzle ?

s

s

B0

B0

d

d

d

d

b to s transition is second order

(gluonic penguin).

Prediction from SM: ~ same value of sin(2b) as in ccs because no additional phase

from the loop.

s

Vts

W

Vtb*

f

b

t

s

Ks

s

???

???

f

c

b

unless new physics enters

the loop. For instance:

squark

s

A. Bay LPHE EPF Lausanne

b 0 f ks 2
B0f Ks .2

sin2b(ccs)

5.2 5.4 5.28 GeV/c2

B0 fKS

6811 signals

106 candidates in the fit

purity = 0.640.10

efficiency = 27.3%

Beam-Energy Constrained Mass

BaBar

A. Bay LPHE EPF Lausanne

g from b d 0 k d 0 ks p p
gfrom BD0K D0 Ksp+p-

Ks

u

K+

u

p+

D0

s

s

p-

Ks

b

b

B+

p+

c

c

K+

B+

u

D0

u

p-

D0 and D0 decay to same final state  mixed state is produced:

See A.Giri, Yu.Grossman, A.Soffer, J.Zupan hep-ph/0303187

a, d, g unknown

Dalitz's analysis with variables and

A. Bay LPHE EPF Lausanne

g from b d 0 k d 0 ks p p 2
gfrom BD0K D0 Ks p+p- .2

3

2

1

0.5 1 1.5 2 2.5 3

D0Ksp+p- as a sum of 2 body decays

a = 0.33±0.10±0.03±0.03

d = 162° +20-25 ±12°±24°

g = 95° +25-20 ±13°±10°

Fit Dalitz plot with

a, d, g as free parameters

90%CL: 61°< g < 142°

preliminary

A. Bay LPHE EPF Lausanne

slide37

Belle:

very, very

preliminary

A. Bay LPHE EPF Lausanne

a from b 0 pp
afromB0pp

d

p

-

u

W

W

d

-

p

t

g

Consider B0p+p- first:

without penguin contributions:

App= 0

Spp= sin(2b+2g)= -sin(2a)

This is not the case: large

"penguin pollution" expected

(but intrinsically interesting..!)

Isospin analysis needed for the extraction of a.

Need to measure alsoB0p0p0, B+p+p0,...

A. Bay LPHE EPF Lausanne

b 0 p p
B0p+p-

App0

continuum

p+p-

Kp

syst. primarily from

background fraction

charmless 3-body B decay

Phys Rev

from ~231 p+p- : App= +0.58 0.15 0.07

Spp= -1.00 ± 0.21 ± 0.07

BABAR:

App = 0.30 ± 0.25 ± 0.04

Spp = 0.02 ± 0.34 ± 0.05

hep-ex/0401029

A. Bay LPHE EPF Lausanne

b 0 p p 2
B0p+p-.2

Belle

BaBar

direct

CVP

A. Bay LPHE EPF Lausanne

first signal from b 0 p 0 p 0
First signal from B0p0p0

B+r+p0

p+p0

Mbc [GeV/c2]

continuum

using 152 M BB:

Br(B0p0p0) = (1.7 ± 0.6 ± 0.2)10-6

Phys. Rev. Lett. 91 (2003) 261801

BABAR: Br(B0p0p0) = (2.1 ± 0.6 ± 0.3)10-6

(hep-ph/0306058 gives 74° < a < 132°... )

A. Bay LPHE EPF Lausanne

global fit of data from all sources
Global fit of data from all sources

A. Bay LPHE EPF Lausanne

test of sm in quark sector check the triangle
Test of SM in quark sector:check the triangle !

Does SM give a coherent picture of CP violation ?

Unitary triangle can be build using its sides

or the angles.

Other information comes form CPV with Kaons and B.

All the information must be consistent (else  new physics ? or measurement error ? or bad supporting theory ?)

A. Bay LPHE EPF Lausanne

test of sm in quark sector
Test of SM in quark sector

sin(2) = 0.687 ± 0.032 from J/K0

sin(2) = 0.793 ± 0.033 from sides

sin(2) = 0.726 ± 0.037 from J/K0

sin(2) = 0.734 ± 0.043 from sides

2.3

from sides

Summer 2005

Summer 2004

2005 test not so

good...

Compare unitarity triangle from CP-violating processes

K CPV in K sector and sin(2) CPV in B sector

with unitarity triangle measured from the sides only

i.e.from

CP-conserving processes

(|Vub| and md, ms)

(68% and 95% CL contours)

A. Bay LPHE EPF Lausanne

test of sm in quark sector 2
Test of SM in quark sector .2

Measure unitarity triangle only from the angles in B decays:

sin(2) from B0  (cc)K0 interference of bc amplitude with B0_B0 mixing

 (or +) from B  , ,  interference of bu amplitude with B0 _B0 mixing

 from B  D(*)K interference of bc and bu amplitudes

Compare again with trianglefrom (CP conserving) side measurements

Test passed.

A. Bay LPHE EPF Lausanne

sin 2 from b s penguin
sin(2) from bs penguin

Naive average of all bs modesdeviated from B(cc)K0 modesby 3.8 in 2003, now only 2.6 

sin(2)eff=0.43±0.07

to be compared

with all charmonium

result 0.726±0.036

A. Bay LPHE EPF Lausanne

other topics a few hep ex
Other topics (a few hep-ex)

CPV results:

  • sin(2b) from J/y p0 hep-ex/0308053
  • g from BD* p hep-ex/0308048

Rare B decays:

  • B hh {pp, Kp, KK, rp, rr} hep-ex/0307077,hep-ex/0306007
  • BKhh {Kpp, KKK, KKp} hep-ex/0307082
  • B pph, pLp hep-ex/0302024
  • BK(*)g, fK(*)g, K(*)ll hep-ex/0308044
  • B ffK hep-ex/0305068
  • B LcpPhys. Rev . Lett. 90 (2003) 121802

EPR & Bell test of QM: hep-ex/0310192

New charmonium X(3871):

Phys. Rev. Lett. 91 (2003) 262001

A. Bay LPHE EPF Lausanne

ckm matrix 2007
CKM matrix 2007
  • CDF + D0: 4 fb-1 each
  • BABAR + Belle: ~1000 fb-1
  • CLEO-C
  • * s(sin(2b)) ≈ 0.03 from B0 J/ KS

* no precise measurement of other angles

* s(|Vij|)/|Vij| ~

down strange beauty

up 0.1% 1% 5%

charm 2% 2% 3%

top 5% 5% 29%

A. Bay LPHE EPF Lausanne

ckm triangle in 2007 sm
Picture will be already

inconsistent ?

CKM triangle in 2007 (SM)

from Dm

b from B J/y Ks

from bu

from bc

A. Bay LPHE EPF Lausanne

beyond 2007
BEYOND 2007

A. Bay LPHE EPF Lausanne

landscape
Landscape

running

proposed

under constr.

cancelled

KAMI

KOPIO

KEK E391a

K

experiments

BNL E949

NA48/3

CKM

BES II

BES III

charm factories

CLEO-c

CLEO III

B factories

e+e–,√s = m(4S)

BABAR

Belle

Super-B

Tevatron

pp, √s = 2 TeV

CDF II

BTeV

D0

ATLAS

LHC

pp, √s = 14 TeV

CMS

We are here

LHCb

2002

2004

2006

2008

2010

2012

2000

From O.Schneider

International WE Heraeus

Summer School, Dresden

A. Bay LPHE EPF Lausanne

experiments in hadronic flavour physics
Experiments in hadronic flavour physics

Running

Coming soon

Proposed

A. Bay LPHE EPF Lausanne

sm view of the unitary triangle
SM view of the unitary triangle

t

b

d

W

W

t

d

b

~ (1-r)2 + h2

from Dm:

r2+h2

from BXu+ln

B0

J/Y

Ks

~Vtd

B0

~Vub

t

W

W

t

B0

b

CP Asym ~ sin{ 2 b }

A. Bay LPHE EPF Lausanne

sm new fcnc
SM + New FCNC

t

b

d

W

W

t

d

b

b

d

NEW

FCNC

+

d

b

~ (1-r)2 + h2

NEW

from Dm:

Im

+ rnew

r2+h2

from BXu+ln

B0

J/Y

Ks

~Vtd

Unchanged

B0

~Vub

t

W

W

t

B0

b+fnew

Re

CP Asym ~ sin{2(b+fnew)}

A. Bay LPHE EPF Lausanne

sm new fcnc bis
SM + New FCNC (bis)

t

b

d

W

W

t

d

b

b

d

NEW

FCNC

+

d

b

~ (1-r)2 + h2

g

NEW

from Dm:

Im

+ rnew

r2+h2

from BXu+ln

B0

J/Y

Ks

~Vtd

B0

Unchanged

~Vub

t

W

W

t

B0

b+fnew

Re

CP Asym ~ sin{2(b+fnew)}

A. Bay LPHE EPF Lausanne

g and new physics from b d d n p d n p etc
g and new physicsfrom Bd D*-np+, D*+np-, etc.

CP in BJ/Y Ks ~ 2(b +fnew)

Bd D*+ np vs Bd D*+ np

Bd D*- np vs Bd D*- np

2(b + fnew) + g

From

g

Idem with Bs decays:

compare

the two g

determinations

(then combine

them)

2 ( dg + fsnew) from CP in BsJ/Y F

2 ( dg + fsnew) - gfrom CP in BsDs-K+, Ds+K-

g

 need to trigger and select hadronic decay channels,

need to study the Bs system, have K/p separation, access to Br < 10-7….

A. Bay LPHE EPF Lausanne

b physics at lhc b
 B physics at LHC(b)

sbb / s inelastic= ~ 0.6% => triggering problem

 Many particles not associated to b hadrons

 No B0-B0 entangled states: mixing dilutes tagging

good things:

  • sbb = ~500 mb, 1012 bb / year at L=21032 cm-2s-1
  • Bu (40%), Bd (40%), Bs (10%), Bc, and b-baryons (10%)
  • Many primary particles to determine b production vertex

not so good:

A. Bay LPHE EPF Lausanne

slide58
LHCb

3 2 1

3

2

qb [rad]

1

0

qb [rad]

B shielding

removed !

Forward detector (1.9    4.9)

~ 50% acceptance for bb pairs

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slide59
LHCb
  • RICH detectors for PID
  • vertex detectors inside beam vacuum

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vertex locator velo
VErtex LOcator (VELO)

Bs oscillation from

BsDs sample

ms = 25 ps1

0 1 2 3 4 5 6 [ps]

21 stations, ~200k channels, analogue R/O (Beetle)

r- andf-measuring stations with Si “striplets”

IP= 14 + 35 /pT

From tracking:

p/p = 0.35% – 0.55%

can observe 5 signal if ms < 68 ps1

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particle id
ParticleID

K efficiency

prob (p K)

ATLAS

LHCb

CF4

Aerogel

& C4F10

RICH1

0 20 40 60 80 GeV/c

RICH2

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triggers
Triggers

L1

ln IP/IP

ln IP/IP

ln pT

ln pT

40 MHz

(12.4 MHz of inelastic interactions)

Efficiencies for signal events

accepted by offline selection

LHCb

B0 J/ KS Bs Ds-K+ B0p+p-

0.88 0.54 0.76

0.90 0.70 0.72

0.79 0.38 0.55

L0

Medium pThadron,m,e,

+ pileup veto

1 MHz

L1

Detached vertex

+ IP of pT candidate

B0p+p-

Bs Ds-K+

40 kHz

HLT

Final state

reconstruction

Signal

Min.

Bias

~2 kHz

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lhcb after 10 7 seconds
LHCb after 107 seconds
  • Parameter Channels N untagged 
  •  Bd+-20k@P/T = 30°, |P/T|=0.200.02, =90° 2-5
  • Bd0  r  4k @=50° 5
  • 2+ Bd  D* 200k @2+=0 12
  •  BdJ/Ks200k <0.6
  • -2 Bs DsK 5400 @ Dms=20ps-1 14
  •  Bd  D(KK)K* 600 =55°-105° <8
  •  Bs  J/ 120k 0.6
  • g Bd  +-/ K+K- 20k/30k @=55°-105° <6
  • BdfKs 0.8k <20 ?

Dms Bs  Ds 80k s/b~3, up to 68 ps-1 (5s)

A few penguins :

Bs  ff1.2k Bd K+-135k

Bs  K+K-37k Bd K*0g35k

Bs  fg9.3k Bd K*0mm4.4k

not possible

at B factory

(Using PDG branching ratios or SM predictions)

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ckm triangle in 2007 10 7 s
CKM triangle in 2007+107 s ?
  • from

LHCb

Im

from Dmd, Dms

from bu

b from B J/y Ks

Re

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key contributions expected from charm factories
Key contributions expected from charm factories
  • Improve determination of  from BDK tree processes:
    • Measure more precisely D0KS+– Dalitz plot
    • Measure D meson strong phase differences appearing in ADS analyses of B+DK+
  • Improve extraction of right side of UT from B oscillations measurements:
    • Measure decay constants fD+ and fDsfrom purely leptonic decays:
    • Compare with lattice QCD calculations: reduce uncertainty on theory predictions for fB0 and fBs (e.g. rely on LQCD only to predict ratio between B and D constants) reduce theory error in extraction of |Vtd|/|Vts| from md/ms

new,50 evts

new,201±3±17 MeV

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charm factories
Charm factories
  • CLEO-c experiment (Cornell):
    • Taking data above charm threshold since 2003:
      • e+e– (3770)  D+D– or D0D0 (281 pb–1 so far)
    • Plan to go also above Ds threshold (s=4.1 GeV):
      • e+e– (…)  Ds+Ds–, …
    • May still spend one year on J/ or (2S)
    • End in 2008
  • BES III experiment (Beijing):
    • BES II stopped in 2004
      • 27.7 pb–1 recorded at (3770)
    • Old BEPC storage ring dismantled this summer to install a new double-ring machine, BEPCII
      • design luminosity 1033 cm–2s–1 at (3770) (= 100 times BEPC)
    • Major detector upgrade: BESII  BESIII
    • Start of physics commissioning in 2007
    • Will run on J/, (2S), (3770), etc …

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