stephen l. olsen seoul national university

Stephen L. OlsenSeoul National University

From: http://luchins.com/what-were-they-thinking/insanely-bad-science/

2008 Nobel Physics Prize

Kobayashi & Maskawa explained CP violation within the framework of the Standard Model, but required that the Model be extended to three doublets of quarks. These predicted, hypothetical new quarks have recently appeared in physics experiments. As late as 2001, the two particle detectors BaBar at Stanford, USA and Belle at Tsukuba, Japan, both detected CP violations independently of each other. The results were exactly as Kobayashi and Maskawa had predicted almost three decades earlier.

Kobayashi Maskawa

Thread of this talk

CP violation

three doublets of

quarks

B mesons(BaBar & Belle experiments)

Stockholm

What is it?

Why three?

Why B mesons?

CP Violations

Differences between matter & antimatterantimatter

P+

e-

P-

e+

hydrogen antihydrogenDifferent?

Dilemma

Laws of physics are very symmetric between matter & antimatter

Nature is very asymmetric between matter & antimatter

no antimatter here

Then:a“no-hair” Universematter = antimatter

Now: people

Big-Bang Cosmology

no antipeople

Only mass, electric charge & angular momentum

Where are the antipeople?

Need to study violations of “CP” symmetry

P = Parity(x,y,z) (-x,-y,-z)

Field (& rules) of footballare parity symmetric

Rules of baseball arenot parity symmetric

Parity violation in physics-a nano history-

Parity Conservation in QM

1927: Nature is Parity symmetric Laporte rule = Parity conservation

Otto Laporte1902-1971

Eugene Wigner1902-1995

1924: Atomic Wave functions are either even or odd.

Laporte rule: dipole transitions connect evenodd (& not eveneven or oddodd)

q-t puzzle

q+ p+p0

mq ≈ mp/2G.D. Rochester & C.C.Butler,Nature 160, 855 (1947)

q+

p+

cloud chamber

p has odd parity: P(p) = -p

P(q+) =+ q+

q has even parityP(t+) = -t+t has odd parity

same mass,same lifetime,

opposite P

t+ p+p+p-

mt = 970 me (495 MeV)R.Brown et al., Nature 163, 47,82 (1949)

photographic emulsion

1947 1949

Lee and Yang

C.N.Yang

T.D.Lee

Phys Rev 104, 254 (1956)

The q+ and t+ are the same particle,and its decays violate Parity.

(now known as the K+ meson)

Parity violation discoveredCo60 Ni60 e- nmore electrons are emittedopposite to the nuclear spindirection than along it

WU, Chien Shiung1912-97

The mirror image, where electrons are emittedparallel to the spin, doesn’t occur in Nature.

J J

C. S. Wu et al., Phys. Rev. 105 (1957), 1415.

_

1957 Nobel Prize

Lee, Tsung-DaoYang, Chen-NingWU, Chien Shiung

P-violations in m- & m+ decay

m-

e-

m- e-n n decays:e- emission opposite tospin direction preferred

m+

e+

m+ e+n n decays:e+ emission parallel tospin direction preferred

C is violated

ParticleAntiparticle operator

Phys. Rev. 105, 1415 (1957)R L Garwin, L M Lederman and M Weinrich

_

_

C x P in m decay

m-

e-

m+

e+

CPMirrored antimatter

case does occur in Nature

“charge conjugate”mirror

CP symmetry is OKViolated

Violated

CP in the neutral K meson system

00

21

002

1

KKK

KKK

CPodd

CPeven

-

+0

0

K

K

“Flavor”eigenstates

CP (Hamiltonian?) eigenstates

d s

s d

-+

-+

ppp

pp0

CPodd

CPeven

K

K-+

-+

pp

ppp

CPodd

CPeven

K

K 0

Violate CP

Short life-timeKShort

Long life-timeKLong

-+

-+

ppp

pp0

Long

Short

K

K

Christenson-Cronin-Fitch-Turlay Experiment (1964)

Long-livedneutral Kaons

p+

p-

Search for long-lived neutral kaon p+p-

Long-lived neutral Kp+p-

(~2 parts in 103)

Small CP violation(2x10-3) is seen

J. H. Christenson et al.,PRL 13 (1964), 138.

No prizes for Christenson or Turlay

1980 Nobel Prize

Incorporating CPV into QM

A A’Particle process

amplitude = Aantiparticle process

amplitude = A’

CPT theorem: |A|2 = |A’|2

A & can differ at most by a complex phaseA ‘

It‘s difficult to generate matter-antimatter differences in QM

Time-re

versa

l

(t-t)

A

+fCP

-fCP

In QM, processes are |Amp|2

Still no matter-antimatter difference(even though there is a CPV phase)A’

|A |2 = |A’|2

A

A’

+fCP

-fCP

Phase measurement needs interference(a second way to get to the same final state)

X

Still no matter-antimatter difference(even though there is a CPV phase

& an interfering process)

A

+ X

A’

|A + X|2 = | +X|2

A’+ X

A

A’

+fCP

-fCP

X must have a “common” phasesame phase for particle & antiparticle

XFinally an matter-antimatter difference

A + X

+ X

A’

|A + X|2 = | +X|2

A’d

Matter-antimatter differences in QM

• Amplitude needs a complex phase– Opposite sign for matter & antimatter

• Need an interfering amplitude– Competing process same final state

• Interfering amplitude needs a “common” phase– Same sign for matter & antimatter

Incorporating a CPV phase into the Standard Model for Particle Physics

Quark mixing

In the late 1973, there were 3 known quarks (u,d,s):

duq=+2/3

q=-1/3

K & M were convinced of the existence of a 4th quark: the hypothesized “charmed” quark (c):

scsc

In the Weak Int. the s & d quarks mix

Mass (& flavor) eigenstates

-

sd

sd

-

sdsd

sd

quark-flavor-mixingMatrix

Weak-interaction eigenstates

The weak interaction quark doublets

+ sdu

+- sd

c

The CPV KLongp+p- decayscorrespond to this transition

Incorporate CP violation by making complex?

d

s

d

udu

KLong

p -

p +

: Not so simple

a 2x2 matrix has 8 parameters

unitarity: 4 conditions

4 quark fields: 3 free phases

# of irreducible parameters: 1 Cabibboangle

1001

**

**

d

d

- CC

CC

cossinsincos

N.CabibboCabibbo 1st proposed quark flavor-mixing in 1963

Phys.Rev.Lett.10:531-533,1963

A complex phase cannot be includedin a 4-quark mixing matrix

Kobayashi-Maskawa paper (1973)Prog. of Theor. Phys. Vol. 49 Feb. 2, 1973

1 CP-violating phase3 “Euler” angles

4 irreducible parameters

a 3x3 matrix has 18 parameters

unitarity: 9 conditions

6 quark fields: 5 free phases

# of irreducible parameters: 4

100010001

***

***

***

d

d

Why were K&M so sure of the c quark?In 1972, they both were in Nagoya,where Kiyoshi Niu was on theExpt’l Particle Physics Faculty

2mm

2009: mD=1.87 GeV, mLc=2.29 GeV

K.Niu

HistoryNovember 1974: Charmed (4th) quark “discovered”@ Brookhaven & SLAC

1976 Nobel prize

Sam Ting Burt Richter

Phys.Rev.Lett.33:1404-1406,1974.Phys.Rev.Lett.33:1406-1408,1974

ppJ/y + X; J/ye+e-

M(e+e-) Ecm(e+e-)

e+e- hadrons

J/y = c c

Kiyoshi Niu

More History

November 1977: Bottom (5th) quark discovered@ Fermilab

February 1995: Top (5th) quark discovered@ Fermilab

Phys.Rev.Lett.39:252-255,1977. CDF: Phys.Rev.Lett.74:2626-2631,1995D0: Phys.Rev.Lett.74:2632-2637,1995

= b bpp t t X_ _

ℓ+n

bc_

Now there are 6 quarksas required by Kobayashi-Maskawa CPV mechanism

du

sc

bt

d

u

s

c

b

tWeak-interaction

eigenstatesMass (& flavor)

eigenstates

Related by a 3x3mixing matrix

Cabibbo-Kobayashi-Maskawa 6-quark mixing matrix

bsd

VVVVVVVVV

bsd

tbtstd

cbcscd

ubusud

'''

CKM

V

d s b

u

c

t

Nearly (but not exactly) diagonal

du

sc

bt

V≈1

du

sc

bt

V≈0.2

du

sc

bt

V≈0.04

du

sc

bt

V≈0.004

CKM hierarchy

The KM phases are in the corners

bsd

VVVVVVVVV

bsd

tbtstd

cbcscd

ubusud

'''

f3

t

d

W+

Vtd

b

u

W+

Vub

f1

The experimental challenge

bVub

W+

*

td

W+

Vtd

Measure a complex phase for bu

u

or, even better, both

or in td

Use B mesonsi.e. mesons containing the b- (5th) quark

B0 = B0 = b dd b

B0/B0 similar to K0/K0

Why B mesons?

1) B0 B0 mixing is strong

_

N(B

) – N

(B)

--

------

------

------

------

------

N(B

) + N

(B) _ _

If you start with a B0, it changes to a B0 (& vice versa) with a ¼-period (1/Dm≈2ps) that is comparable to the B0 lifetime (≈1.5ps)

_

2) b quarks are sensitive to CPV phases - they probe the corners of the CKM matrix

2 ps

B0

B0_

B0_

B0B0

eiDmt

B0

td+

td

B0

Vtb

V*

Vcb

KS

J/y

J/y

KS

V*2

Vtb

V*td

td

Vcb

B0B0

Sanda, Bigi , Carter technique for f1

+sin2f1

eiDmt

mixing provides the “common” phase

Phys.Rev.D23:1567,1981Nucl.Phys.B193:85,1981

Interfere BfCP with BBfCP _

What do we measure?

t Dz/c

“Flavor-tag” decay(B0 or B0 ?)

J/y

KS

B - B B + B

e- e+

more B tags

more B tags

Dz

t=0

fCP

(tags)

sin2f1

This is for fCP=+1; for fCP=-1, the asymmetry is opposite

Asymmetric energies

_B0 & B 0 in an “entangled”

quantum state

_

t

The Belle experiment at KEK

KEK laboratory in JapanTsukuba Mountain

KEK laboratory

KEKB Collider

elle

A magnetic spectrometer based on a huge superconducting solenoid

Find B0(B0?)J/y KS decays

B0(B0?) J/y Ks event

Tracking chamber onlym+m-

p+p-

_

Check the other tracks to see if the accompanying meson is a B0 or a B0

?

?

??

??

The K- in the remaining tracks means the other meson is (probably) a B0

(not a B0)

p-

p- p-

p+

K-p+

B D K-

&B D K+

are dominantdecay chains

_

Check the other tracks to see if the accompanying meson is a B0 or a B0

_

Determine the time sequence of the 2 decaysSilicon micro-vertex detector m+ track

tracks from accompanying B meson

m- track

Resolution ≈ 150mm

BJ/y KS decay occurs before the tag decay

Make the plot & fit itBelle 2007

sin2f1 = 0.681 ± 0.025

CP=+1 CP=-1

f1 = 21.50 ± 1.00 Similar results from the BaBar experiment at SLAC

Belle, Phys.Rev.Lett.87:091802,2001

BaBar, Phys.Rev.Lett.87:091801,2001

~7500 evts ~6500 evtsPRL 98: 003802 (2007) B0 tag

B0 tag_

B0 tag

B0 tag_

Compare with KM theory constraints from other processes

-

---

f

1tan

1

1 A

iViV

td

ub

f1

Nobel committee:“The results were exactly as Kobayashi and Maskawa had predicted…”

|

BaBar & Bellemeasurement

Vtd

Vcb

_

Stockholm, December 2008

Does this explain why there are no antipeople?

CP violation in the early Universe dueto the KM mechanism is too small

No! Not by more than10 orders-of-magnitude!

There must be another CPV source-one that’s not in the current Standard Model for particle physics-

Fourth generation of quarks?

New particles -- SUSY?, Technicolor?...

CPV in the neutrino sector?

…

How to find New Physics particles:1) Produce them in very high energy collisions

Go to CERN LHCworld’s highest energies

Join a 2000 physicist team Look for signs of NP particlesburied in very complex events

Or2) Look for effects of Virtual NP particles in B decays

(also: ’, K+K-, etc.)

For example BKf:virtual heavy NP particles could

contribute to the loop

so-called “Penguin processes”

, x

,YVtb Vts

*

Sensitivity

b st

Vtb Vts* HSM

VtbVts

Mt2

0.04Mt

2

*SM bs “penguin”

structure of the CKMmatrix suppresses FCNC

X= heavy NP particle

b sX

g g

heaviest of allknown particles

HNP |g|2

MX2

For “generic” NP (i.e. g 1): MX ≈ 5Mt can produce O (1) deviations from SM predictions

1 TeV, the largest mass accessible at LHC

example: sin2f1 with SM bs penguins

Vtb& Vts: no SM CPV phases in B0Kf ,…

SM prediction: sin2f1 = sin2f1 from BJ/y K0

Any difference new particles in the loop

penguin

Vtd

Vtd

+

f1

B0 B0

, ’, K+K-

f1

, ’, K+K-

*

*

Interfere with B0B0Kf, …_

Same measurement that we did for B0J/y K0

-except now the decays are much less common-

Vtb Vts*

sin2f1 from B0 → K0f & K0’penguin

sin2f1penguin

=0.67±0.22 sin2f1penguin

=0.64±0.11

sin2f1 = 0.681 ± 0.025 very near SM expectation of:

Belle, PRL 98: 003802 (2007)

~200 evts ~1400 evts

BaBar, PRD 79, 052003 (2009)BaBar, arXiv 0808.0700

~2000 evts~200evts

No evidence yet for new heavy particles

Different penguindecay modes

SM expectation

sin2f1

No O(1) NP effects: MX > 1TeV (g2)

What’s next?

Super-KEKB & Belle II50x increase in data

Make these error regions

as small as this one

Sensitivity for new physics increases to 10TeV or higher

well beyond the reach of the LHC

sin2f1

?

Summary1927: Nature is Left-Right symmetric Parity is an important symmetry

1956: Weak Interactions violate Parity, but CP symmetry is preserved

1964: CP is violated too

1973: CP violations require 6 quark flavors

20??: New non-SM CPV source found in B decays?

Laporte Wigner

Yang Lee

Kobayashi Maskawa

Cronin Fitch

Thank you감사합니다