A. Bay LPHE EPF Lausanne1 Summary B factories and LHCb

A. Bay LPHE EPF Lausanne 1

Summary

B factories and LHCb


CP & T violation only in K0 system ???

Since 1964, CP and or T violation was searched for in othersystems than K0, other particles decays, EDM...

No other signal until 2001...


production of(4s) (10.58GeV/c2) = 0.425(4s) B0 B0

B+ B

BaBar (SLAC) and Belle (KEK)

in 2001: observation of CP violation in the B mesonsystem, using "asymmetric collider" B factories.KEKB machine:

8 GeVelectrons

3.5GeV positron


KEKB24% Y(4s)76% continuum

year 2003: crossing the(psychological) luminositybarrier of 1034 cm-2s-1

1.5807 1034

on 18-May-2005


Pea

k lu

min

osit

y cm

s

Luminosity trend in the last

30 years


BaBar and Belle

Study of the time dependent asymmetry in decay rates ofB0 and anti-B0

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

€

ACP(t) =N(B 0 → J /Ψ KS) − N(B0 → J /Ψ KS)

+(t) = S sin Δm t( )

CP violated S ≠ 0


CP measurements at B factories

Difficult: B0 mean life 1.54 10 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 z of the 2 vertices. r is small.

Δz cβγΔt ~ 200 m at Belle

(4s)

zz1 z2

z

J/Ks

e

Dr


CP measurements at B factories

(4s)

zz1 z2

z

J/Ks

fCP

B0 and anti-B0 oscillate coherently (QM entangled state).When the first decays, the other is known to be of the oppositeflavour use the other side to infer the flavour, B0 or anti-B0,of the fCP parent

e

D

€

e+ → B0

e− → B 0 ⎧ ⎨ ⎩

region of B0 & B0

coherentevolution


Belle experiment

Central Drift Chamber He/C2H5(Pt/Pt)2=(0.0019 Pt)2+(0.0030)2

CsI(Tl) 16X0

E/E ~ 1.8% @1GeV

Aerogel Cherenkov n=1.015~1.030

Si Vertex detector3 layers mid 2003now 4 layers Impact parameter resolution 55m for p=1GeV/c

TOF counter

SC solenoid 1.5T

8GeV e

3.5GeV e

Started in 1999~300 physicists from ~60 institutes in14 countries.

/ 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


Belle

ACC

Silicon Vertex Detector SVD Impact parameter resolution 55m for p=1GeV/c at normal incidenceCentral 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/cKL and : KLM (RPC) : efficiency > 90% <2% fake at p > 1GeV/c

~ 8 m

€

Ldt ≈∫ 400 fb

4 108 B pairs


spatial resolution for Blepton + Xz (lepton) ~ 100 m

Belle micro-vertex detector


Belle event


Particle ID in Belle

Particle ID uses information fromACC, TOF, dE/dx( CDC)

€

Prob to be a K{ } =L(K)

L(π) + L(K)

Barrel ACC

Endcap ACC

dE/dx

TOF

p (GeV/c)

cut


Experimental program: measure sides and anglesof the CKM matrix

* 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

~Vub ~Vtd

~Vcb

€

Vud Vus Vub

Vcd Vcs Vcb

Vtd Vts Vtb

⎛

⎝

⎜ ⎜ ⎜

⎞

⎠

⎟ ⎟ ⎟

Use B mesonsphenomenology

t quark

oscillations

CP asymmetries

b quark

decays


Analysis and results

•Continuum rejection•Kinematics at the Y(4s)

•The Unitary triangle: determination of Vub

" Vcb" Vtd" " "

•No time for other topics

~Vub ~Vtd

~Vcb


Continuum rejection24% Y(4s)76% continuumfrom event topology which

is ~spherical for BB, jet like for continuumand angular distributions

BB

qq

Build Likelihood L for B and qq hypothesisusing event shape variables and cos B

0 0.2 0.4 0.6 0.8 1

€

LB

LB + L qq

cut


How to find a B meson?Kinematics variables at the Y(4S)

Mbc

5.2 5.24 5.28 GeV/c2

0

E0.2

0.2

GeV/c2

€

Mbc = (E beam* )2 −

r p B

* 2

€

E = EB* − E beam

*

Gather candidates Band calculate (pB,EB).Boost to c.m. (pB

*,EB*)

"beam constrained mass"

€

Ebeam* ≡

s

2

Example:B D0

with


Determination of Vcb

€

l −

W

b c

Vcb

World Average: |Vcb| (inclusive) (42.0 0.6 0.8) 10-3

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

-1.8

€

Vcb = (40.2 ±1.9)10−3

D0

€

dΓ

dy=

GF

2

48π 3MD*

3 MB 0 − MD*( )

2g(y)Vcb

2F(y)2

g(y) known function of y

€

B 0 → D*+e−ν e

d

D*+B0

q

F(y) hadronic form factor

plus ~5% error on F(1)


Determination of Vub

€

l

W

b u

Vub

bc

bu

0 1 2 3 GeV/cLepton momentum

(in c.m.)

Exemple: use lepton momentum distributionfrom inclusive semileptonic decays

€

B → Xul ν

Less than 10% of thespectrum background free

hep-ex/0305037, with reconstruction

|Vub| (10-3) = 3.96 0.17(stat) 0.44(syst) 0.29(theo) 0.34(bc) 0.26(bu)

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


Determination of Vtd

B0 B0

t

d

b

tW W

b

d

Vtd

0 3 6 9 ps

Probability1

B0

B0

Starting from a pure sampleof B0, for instance,a B0 component builds upin a time scale of a few ps:

€

P(B0)∝ e−t /τ 1+ cos Δmd t( )[ ]

P(B 0)∝ e−t /τ 1− cos Δmd t( )[ ]

measure oscillation frequency

€

Vtd ∝ Δmd


region of B0 & B0

coherentevolution

md with di-lepton events

* KEK-B boost <Δz> cβγ ~ 200 m

(4s)

zz1 z2

z

e+

* Tag B flavour from semileptonic B0 X l B0 X l

X

Y

* B0 and B0 oscillate coherently (QM entangled state).When the first decays, the other is known to be of the oppositeflavour.

t ~ z/c


md from di-lepton events .2

-12 -8 -4 0 GeV2

NMissing mass

Background: B+ X l B X l

Selection strategy of the "soft pion tag"B0 D* l Br3%

D0 Br70%

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

2

(Frederic Ronga, PhD thesis, 2003)


md from di-lepton events .3

Get z distributionsfor "Same Sign"and "Opposite Sign"leptons couplesand fit for md...

OSSS

J/ l+ l toinfer resolution

-2 -1 0 1 2 z (mm)

SS

-2 -1 0 1 2 z (mm)

OS

0 1 2 z (mm)

€

Asymmetry(t) =OS −SS

OS + SS(t)


F. Ronga

average

md and Vtd HEP-PH/0206171

€

Vtd ∝ Δmd fB BB

Bagparameter

B decayconstant

|Vtd | ~ (8±2)10-3

~20% error !

{


UT sides

The UnitaryTriangle

inferred from its sides

and fromK0 data

Vub/Vcb

From K0

md & ms

10

Excluded area has <0.05 CL


from B0 J/ Ks

b

dB0

Vcb

cc

sKs

J/

d

B0

Vcbc

sKs

J/

Vtd

Vtb

VtdVtb

c

b

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

€

AsymCP (t) =N(B 0 → J /Ψ KS ) − N(B0 → J /Ψ KS )

N(B 0 → J /Ψ KS ) + N(B0 → J /Ψ KS )(t)∝ SCP sin Δmd t( )

CKM phase 0 !

CKM phase = 0

sin2

}

SM:

B0

d

Golden ChannelGolden Channel


Any "direct" CP violation ?

b

dB0

Vcb

cc

sKs

J/

dB0

Vtb c

K

s

J/c

b

s

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

CKM phase = 0

CKM phase = 0

t

Vts

€

AsymCP (t) =N (B

0→ J / Ψ KS ) − N (B

0→ J / Ψ KS )

+(t)∝ ACP cos Δmd t( ) + SCP sin Δmd t( )

sin2

}

SM:

}

0


Time dependent asymmetry measurement

(4s)

zz1 z2

z

J/Ks

fCP

e

D

€

e+ → B0

e− → B 0 ⎧ ⎨ ⎩

region of B0 & B0

coherentevolution

€

ACP (t) =N (B

0→ J / Ψ KS ) − N (B

0→ J / Ψ KS )

N (B 0

→ J / Ψ KS ) + N (B0

→ J / Ψ KS

(t)

Need to "tag" the flavour: B0 or B0.B0 and B0 oscillate coherently (QM entangled state) use the other side to infer the flavour

t ~ z/c

ftag


b ccs reconstruction

140 fb1, 152M BB pairs

B 0 J/KL

b ccs (J/KL excluded)

5417 events are used in the fit.pB GeV/c


A large CP asymmetry has been observed!

World average (October 2005): SCP = 0.726 ± 0.037

J/KL

ACP~ 0, compatible with no direct CPV

SM: SCP = sin(2) => or 66.3°)

J/KL is OK

€

AsymCP (t) =N (B

0→ J / Ψ KS ) − N (B

0→ J / Ψ KS )

+(t)∝ ACP cos Δmd t( ) + SCP sin Δmd t( )


SM & KM model is verified !

= 23.7°± 2.1° = 66.3°± 2.1°


UT with sin2

The UnitaryTriangle

fit including sides,

K0 data,and

sin2


b sss, a B0 Ks puzzle ?

b to s transition is second order

(gluonic penguin).Prediction from SM: ~

same value of sin(2) as in ccs because no additional

phase from the loop.

VtsV

tb*

B0

b

d

s

s

d Ks

s

W

t

??????

B0

b

d

s

s

d

s

squark

unless new physics entersthe loop. For instance:


B0 Ks .2

6811 signals106 candidates in the fitpurity = 0.640.10efficiency = 27.3%

B 0 KS

5.2 5.4 5.28 GeV/c2

€

SφKs = −0.96 ± 0.50−0.11+0.09

€

AφKs = −0.15 ± 0.29 ± 0.07

BaBar

€

SφKs = +0.45 ± 0.43± 0.07

Beam-Energy Constrained Masssin2(ccs)


from BD0K D0 Ks +-

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

u

uB+

bc

s

D0

Ks+

-

K+

u

B+

c

s

D0

Ks+

-

b u

K+

€

A1 ~ VcbVus* ~ Aλ3

€

A2 ~ VubVcs* ~ Aλ3 ρ + iη( ) ~ exp iγ{ }

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

€

˜ D 0 = D 0 + ae iθ D0

€

˜ D 0 = D 0 + ae i(δ +γ ) D0

Dalitz's analysis with variables and

€

m2(Ks,π +)

€

m2(Ks,π −)

a, , unknown


from BD0K D0 Ks +- .2

0.5 1 1.5 2 2.5 3

3

2

1

€

m2(Ks,π +)

€

m2(Ks,π −)D0 Ks +- as a sum of 2 body decays

Fit Dalitz plot witha, , as free parameters

a = 0.33±0.10±0.03±0.03 = 162° +20

-25 ±12°±24° = 95° +25

-20 ±13°±10°

90%CL: 61°< < 142° preliminary


Belle:very, verypreliminary


from B0

€

Asym t( ) = Aππ cos Δmd t( ) + Sππ sin Δmd t( )

0Bd

bW

d

uud

+

A = 0S = sin(2+2)= sin(2)

without penguin contributions:

Isospin analysis needed for the extraction of .Need to measure also B0 B+

d

b

W

tg

d

uu

d

0B

+

-

This is not the case: large"penguin pollution" expected(but intrinsically interesting..!)

Consider B0 first:


B0

Phys Rev

from ~231 : A = +0.58 0.15 0.07 S = 1.00 ± 0.21 ± 0.07

charmless 3-body B decay

K

continuum

syst. primarily frombackground fraction

BABAR:

A = 0.30 ± 0.25 ± 0.04

S = .02 ± 0.34 ± 0.05

A0

hep-ex/0401029


B0

Belle

BaBardirectCVP


First signal from B0

Mbc [GeV/c2]

using 152 M BB: Br(B0 ) = (1.7 ± 0.6 ± 0.2)10-6

B+

continuum

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

Phys. Rev. Lett. 91 (2003) 261801

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


Global fit of data from all sources


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 ?)


Test of SM in quark sector

Summer 2004

sin(2) = 0.726 ± 0.037 from J/K0

sin(2) = 0.734 ± 0.043 from sides

(68% and 95% CL contours)

from sides

Summer 2005

sin(2) = 0.687 ± 0.032 from J/K0

sin(2) = 0.793 ± 0.033 from sides 2.3

2005 test not sogood...

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)


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 bc amplitude with B0_B0 mixing (or +) from B , , interference of bu amplitude with B0 _B0 mixing from B D(*)K interference of bc and bu amplitudes

Test passed.

Compare again with trianglefrom (CP conserving) side measurements


sin(2) from bs penguin

Naive average of all bs modesdeviated from B(cc)K0 modesby 3.8 in 2003, now only 2.6

sin(2)eff=0.43±0.07to be comparedwith all charmoniumresult 0.726±0.036


Other topics (a few hep-ex)

• sin(2) from J/ hep-ex/0308053

• from BD* hep-ex/0308048

Rare B decays:•B hh {, K, KK, } hep-ex/0307077, hep-ex/0306007

•BKhh {K } hep-ex/0307082

•B pph, p hep-ex/0302024

•BK(*), K(*) K(*)ll hep-ex/0308044

•B K hep-ex/0305068

•B cp Phys. Rev . Lett. 90 (2003) 121802

CPV results:

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

Phys. Rev. Lett. 91 (2003) 262001New charmonium X(3871):

http://arxiv.org/abs/hep-ex/0308053









down strange beauty up 0.1% 1% 5%charm 2% 2% 3% top 5% 5% 29%

CKM matrix 2007

* Vij)/Vij ~€

Vud Vus Vub

Vcd Vcs Vcb

Vtd Vts Vtb

⎛

⎝

⎜ ⎜ ⎜

⎞

⎠

⎟ ⎟ ⎟

CDF + D0: 4 fb-1 eachBABAR + Belle: ~1000 fb-1

CLEO-C

(sin(2)) ≈ 0.03 from B0 J/ KS

* no precise measurement of other angles


CKM triangle in 2007 (SM)

Picture will be already inconsistent ?

from m

from bc

from bu from B J/ Ks


BEYOND 2007 QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor



Landscapecancelledproposed

under constr.running

2000 2002 2004 2006 2008 2010 2012

BES II BES IIICLEO-ccharm factories

CLEO IIIBABAR

Belle Super-B

B factoriese+e–, √s = m(4S)

ATLASCMSLHCb

LHCpp, √s = 14 TeV We

are here

K experiments BNL E949

KOPIONA48/3CKM

KAMIKEK E391a

CDF IID0

BTeVTevatronpp, √s = 2 TeV

From O.SchneiderInternational WE Heraeus Summer School, Dresden


Experiments in hadronic flavour physics

Physics Exp. Machine LaboratoryOperation

dates

B and charm

BABAR PEP-II, ee (4S) SLAC (USA) 1999–2008

Belle KEKB, ee (4S) KEK (Japan) 1999–2009

CDF IITevatron, pp √s = 2 TeV

Fermilab (USA)

2001–2009D0

charm CLEO-c CESR-c, ee (3770), …Cornell (USA)

2003–2008

K E391a 12 GeV PS KEK (Japan) 2004–2006

B

(and high pT)

ATLAS

LHC, pp √s = 14 TeV CERN 2007–CMS

B and charm LHCb

charm BES III BEPC II, ee (3770), … IHEP (China) 2007–B and charm

Super-Belle

Super-KEKB, ee (4S) KEK (Japan) 2011–

K NA48/3 SPS CERN 2009–

K (proposals expected end 2005) JPARC ?

Proposed

Coming soon

Running


~Vub

from BXu+l

B0B0

B0

J Ks

W Wt

t

CP Asym ~ sin{ 2 }

t

d

b

tW W

b

d

~

~Vtd

SM view of the unitary triangle from m:


~Vub

from BXu+l

new

B0B0

B0

J Ks

W Wt

t

CP Asym ~ sin{2(new)}

t

d

b

tW W

b

d

~

d

b

b

dNEWFCNC

Unchanged

rnew

NEW

Im

Re

~Vtd

SM + New FCNC from m:


~Vub

from BXu+l

new

B0B0

B0

J Ks

W Wt

t

CP Asym ~ sin{2(new)}

t

d

b

tW W

b

d

~

d

b

b

dNEWFCNC

Unchanged

rnew

NEW

Im

Re

~Vtd

SM + New FCNC (bis) from m:


and new physics from Bd D*n+, D*+n, etc.

Idem with Bs decays:Idem with Bs decays:

snew from CP in Bs J

snew from CP in Bs Ds

K, Ds

K

comparethe two determinations(then combinethem)

Bd D* n vs Bd D* n

Bd D* n vs Bd D* n

From 2( new) +

CP in BJ/ Ks ~ 2( + new)

need to trigger and select hadronic decay channels,

need to study the Bs system, have K/ separation, access to Br < 107….


B physics at LHC(b)

• bb ~500 b, 1012 bb / year at L=21032 cm2s

• Bu (40%), Bd (40%), Bs (10%), Bc, and b-baryons (10%)• Many primary particles to determine b production vertex

bb / inelastic ~ 0.6% => triggering problem

Many particles not associated to b hadrons

No B0-B0 entangled states: mixing dilutes tagging

good things:

not so good:


LHCb

Forward detector (1.9 4.9)~ 50% acceptance for bb pairs

3 2 1b [rad] 0 1 2 3

b [rad]

B shieldingremoved !


LHCb

— RICH detectors for PID—vertex detectors inside beam vacuum


VErtex LOcator (VELO)

21 stations, ~200k channels, analogue R/O (Beetle)r- and -measuring stations with Si “striplets”

IP= 14 + 35 /pT

From tracking: p/p = 0.35% – 0.55%

can observe 5 signal if ms < 68 ps1

ms = 25 ps1

BBss oscillation oscillation from Bs Ds

sample

0 1 2 3 4 5 6 [ps]

QuickTime™ and aTIFF (Uncompressed) decompressor



LHCbATLAS

0 20 40 60 80 GeV/c

ParticleID

€

B0 → π +π−

RICH1 RICH2

Aerogel& C4F10

CF4

prob ( K)

K efficiency


Triggers

1 MHz

40 MHz

Detached vertex

+ IP of pT

candidate

Medium pT hadron,,e,

+ pileup veto

(12.4 MHz of inelastic interactions)

LHCb

40 kHz

L0

L1

B0 J/ KS Bs DsK+ B0

0.88 0.54 0.76 0.90 0.70 0.72

0.79 0.38 0.55

Efficiencies for signal eventsaccepted by offline selection

ln pT ln pT

ln

IP/

IP

ln

IP/

IP

L1L1Signal

Min.Bias

B0 Bs DsK+

Final statereconstruction

~2 kHz

HLT


LHCb after 107 seconds

Parameter Channels N untagged

Bd+ 20k @P/T = 30°, |P/T|=0.200.02, =90° 2-5

Bd0 4k @ =50° 5

2+ Bd D* 200k @2+=0 12

BdJ/Ks 200k <0.6

-2 Bs DsK 5400 @ ms=20ps-1 14

Bd D(KK)K* 600 =55°-105° <8

Bs J/ 120k 0.6

Bd + / K+K- 20k/30k @=55°-105° <6 BdKs 0.8k <20 ? ms Bs Ds 80k s/b~3, up to 68 ps-1 (5)

A few penguins : Bs 1.2k Bd K+- 135k Bs K+K- 37k Bd K*0 35k

Bs 9.3k Bd K*0 4.4k(Using PDG branching ratios or SM predictions)

not possibleat B factory


CKM triangle in 2007+107 s ?

from B J/ Ks

from md, ms

from bu

from LHCb

Re

Im


Key contributions expected from charm factories

• Improve determination of from BDK tree processes:– Measure more precisely D0KS+– 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 fDs

from 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

€

Γ(D+ → l +ν) =GF

2

8πVcd

2fD+

2 ml2M

D+ 1−ml

2

MD+2

⎛

⎝ ⎜

⎞

⎠ ⎟

2


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 …

Documents

A. Bay LPHE EPF Lausanne1 Summary B factories and LHCb