Mayda M.Velasco Northwestern University Oct. 1, 2004

40 Years after Discovery of 40 Years after Discovery of Strangeness, Parity and CP Strangeness, Parity and CP

violations – Why are we still working violations – Why are we still working on Kaon Physics?on Kaon Physics?

Mayda M.VelascoMayda M.VelascoNorthwestern UniversityNorthwestern University

Oct. 1, 2004Oct. 1, 2004

From the biased point of view from a member of NA48@CERNFrom the biased point of view from a member of NA48@CERN

In order to put the subject in context, let’s In order to put the subject in context, let’s look at the main question of the particle look at the main question of the particle

physics community…physics community…● Where did the anti-matter go? … What caused the

matter-antimatter asymmetry of the Universe?● Can we explain the matter and energy composition of

the Universe? ● Why are there so many particles? … What causes

their masses to be so different? ● Where does mass come from?● Do all known forces unify as some large E scale?● Are there extra dimensions of space?

None of the above can be fully answered by the SMNone of the above can be fully answered by the SM2

Puzzles brought & Puzzles brought & answered by strange answered by strange

Kaon & Hyperon Kaon & Hyperon physics has revealed physics has revealed

many aspects of many aspects of “TODAY’s” “TODAY’s”

Standard Model of Standard Model of Particle PhysicsParticle Physics

More to come…More to come…

qqqqqqqqqq

Nevertheless we have a successful ModelNevertheless we have a successful Model

3

● 1944-47: Strangeness quark model

Original Puzzles from Kaon decaysOriginal Puzzles from Kaon decays

4

Strangeness

- produced by strong interaction

- conserved by strong interactions these strange particles produced in pairs

Puzzle #1Puzzle #1 -- Strange particles observed: -- Strange particles observed:Long lifetimes & HeavyLong lifetimes & Heavy

00 Kp

u s

d

su

u

dg

5


Basis for QCD gluon● 1956: Parity violation


6

Invariance under Lorentz Invariance under Lorentz transformation implies transformation implies

CPTCPT invariance invarianceTherefore… big impact on the foundation of the theory, if interactions behave in different ways under:

• Charge conjugation(C): reverses the electric charge & all the internal quantum numbers.

• Parity (P): space inversion; reversal of the space coordinates.

• Time reversal (T): replacing t by -t. This reverses time derivatives like momentum and angular momentum.

Particles and antiparticles have identical masses and lifetimes. Particles and antiparticles have identical masses and lifetimes. This arises from CPT invariance of physical theories and is used This arises from CPT invariance of physical theories and is used experimentally to test CPT.experimentally to test CPT. 77

● Kaons are mesons (Spin = 0; Parity = -1):

● K+ +0 P=(-1)(-1) Even

+-+ P=(-1)(-1)(-1) Odd

Puzzle #2Puzzle #2 – Parity violating Decays: – Parity violating Decays:V-A TheoryV-A Theory of Weak Interactions (WI)of Weak Interactions (WI)

•Strangeness not conserved WI

Puzzle

Extra confidence in the V-A theory(Spin-Flip) BR = 63%

Helicity suppressed due to low mass of e+ BR = 0.0015%

K0 = d s K+ = u s S = +1K0 = d s K- = u s S = -1

8


Basis for QCD● 1956: Parity violation

Chiral nature of weak interactions● 1964: Suppression of FCNC

Puzzels from Kaon decaysPuzzels from Kaon decaysOriginal Puzzles from Kaon decaysOriginal Puzzles from Kaon decays

9

Puzzle #3Puzzle #3 – Low rate of K – Low rate of KLL:: Predicts no mixing with ZPredicts no mixing with Z00 boson & boson &

existence of Charm Quarkexistence of Charm Quark

d

sc W

W_

-

KL

If possible should represent ~ 60% of the decays Not Observed

Consistent with observed rate ~10-5

FCNC not allowedFCNC not allowed Extra u like quark needed to Extra u like quark needed to get proper rateget proper rate Charm Charm

d

su W

W_

-

KL

10


Basis for QCD ● 1956: Parity violation


Properties of the weak neutral currents

Suggested charm quark● 1964: CP violation


11

•Flavor Eigenstate K0 - K0

Puzzle #4Puzzle #4 – CP violating Decays (CP): – CP violating Decays (CP): KK0 0 reveals a more intricate picture reveals a more intricate picture

d

su, c, t W

W_

s

d_u, c, t

d

su, c, t

W W

_

s

d_

u, c, t___ K0

K0

K0

K0

oscillations

12

KK00 - K - K00 Oscillation Oscillation quantified from quantified from leptonic decayleptonic decay

Get positronGet positron::

OrOr electronelectron::

Kaon Interferometry

≈m

13

•Flavor Eigenstate K0 - K0

Puzzle #4Puzzle #4 – CP violating Decays (CP): – CP violating Decays (CP): KK0 0 reveals a more intricate picture reveals a more intricate picture

•CP Eigenstate

•Mass Eigenstate Before observation of CP violation

K1oo

K1+-

K2+-o

K2ooo

CP=+1

CP=-1

00

2

001

2

12

1

KKKK

KKKK

L

s

d

su, c, t W

W_

s

d_u, c, t

d

su, c, t

W W

_

s

d_

u, c, t___ K0

K0

K0

K0

= 0.9 x 10-10 s

= 5.2 x 10-8 s

oscillations

14

Puzzle #4Puzzle #4 – CP …Continues – CP …Continues

qg,

q

0

2nd:Direct NA48/KTEV

KKLL observed! observed! Violation of CP Violation of CP

Re(’/)

1st:Indirect – 19641-2 per mil effect

15

Puzzle #4 -Puzzle #4 -- CP: clasification - CP: clasification

CP violation in the decay amplitute

CP violation in the decay amplitute

CP eigenstates ≠ mass eigenstates

CP eigenstates ≠ mass eigenstates

CP violation from interference of “DIRECT and MIXING”

CP violation from interference of “DIRECT and MIXING”

DIRECT MIXING or INDIRECT

INTERFERENCE

Re(’/)

DIRECT CP firmly established after more than 30 yearsRe(’/) = (16.7±2.3)x10-4

Re(

e’/e

)(10

-3)

16




Suggested charm quark

Properties of the neutral currents● 1964: CP violation

Subtle connection to 3-generation structure of matter


17

in Kaons required a 3in Kaons required a 3rdrd generation generation of quarks to maintain Unitarityof quarks to maintain Unitarity

11

21

21

23

22

32

AλiηρAλ

Aλ/λλ

iηρAλλ/λ

VVV

VVV

VVV

tbtstd

cbcscd

ubusud

004.0)(

04.0

2.0

223

2

A

A

)1(52* AVV ttdts

If V*tdVts is complex CP is violated..

In shorthand:

CPCP

3X3 a complex phase possible Without giving up Unitarity

18







Absolute matter-antimatter asymmetry…

Summary of “s” puzzles and their Summary of “s” puzzles and their contribution to the SMcontribution to the SM

19

+ 2

Why Why Puzzle #4Puzzle #4 was so interesting? was so interesting? Potential Solution to the Baryon Potential Solution to the Baryon Asymmetry in the Early UniverseAsymmetry in the Early Universe

q

q

q q They basically have all annihilated away except a tiny difference between them

10,000,000,001 10,000,000,000

q

20

1

us

Baryon Asymmetry in the Baryon Asymmetry in the Current UniverseCurrent Universe

… … After 30 years of studying CP-violation in the quark sector:After 30 years of studying CP-violation in the quark sector:Now we know that the effect is too small to be source of the Now we know that the effect is too small to be source of the Baryon AsymmetryBaryon Asymmetry

…This is us TODAY!!!

21

Baryon Asymmetry in the Baryon Asymmetry in the Current UniverseCurrent Universe






Absolute matter-antimatter asymmetry…


Summary of “s” puzzles and their Summary of “s” puzzles and their contribution to the SMcontribution to the SM

> 30 Years Later

> 30 Years Later

22

So…What is So…What is currently going on currently going on in Kaon physics?in Kaon physics?

Let’s use NA48@CERN as Let’s use NA48@CERN as an examplean example 23

Basics of Kaon Experiments like NA48Basics of Kaon Experiments like NA48 450 GeV protons from the

CERN SPS hit a Be-target to produce the particles from which we make our beam line.

Neutral particles – not much can be done without destroying them.

Charged particles – can be momentum selected, transported and accelerated, if needed.

p p (n) X1,X2,X3,X4,…

@ NA48 we study the decay of both neutrals and charged Kaons@ NA48 we study the decay of both neutrals and charged Kaons24

Is there anything interesting in our Is there anything interesting in our NA48 neutral kaon beam lines?NA48 neutral kaon beam lines?

BentCrystal

25

Beam instrumentation Beam instrumentation development based on development based on

aligned crystalsaligned crystals

•Our NA59-Northwestern Our NA59-Northwestern group used coherent group used coherent phenomena & birefringence in phenomena & birefringence in aligned crystals to make:aligned crystals to make:

– polarimeterspolarimeters– /4 plates for 100 GeV /4 plates for 100 GeV –Polarized positron sourcesPolarized positron sources

26

Apyan,Velasco

Relevant Beam lines in 2002 & 2003-4Relevant Beam lines in 2002 & 2003-4

KS beam line

K± beam line

27

Decay region:Decay region:Join HE Physics & you might find Join HE Physics & you might find

your self doing “archeological” workyour self doing “archeological” work

Our decay tank is not Our decay tank is not a passive devicea passive device

Northwestern:Northwestern: measure unexpected measure unexpected magnetic fields insidemagnetic fields insidethis vacuum tankthis vacuum tank

Remember the Remember the Gargamelle experiment?Gargamelle experiment? The ghost is still in our The ghost is still in our experimental hallexperimental hall 28

and stay fit…while fixing the and stay fit…while fixing the reconstruction of the charged tracksreconstruction of the charged tracks

Gargamelle Gargamelle magnet was magnet was around thisaround thislocation!location!

29

Muon system:Muon system:s(t) s(t) 350 ps 350 ps

M(00) ~ 2.5 MeVM(+-) ~ 2.5 MeV

Spectrometer:pT kick ~250 MeV/c

(P)/P (P)/P 0.48% 0.48% 0.009 P[GeV/c]% 0.009 P[GeV/c]%

LKr Calorimeter:(E)/E (E)/E 3.2%/√E 3.2%/√E 9%/E 9%/E 0.42% 0.42%s(t) s(t) 265 ps for 50 GeV e- 265 ps for 50 GeV e-

NA48 DetectorNA48 Detector

30

Liquid Krypton Liquid Krypton Calorimeter (LKr)Calorimeter (LKr)

Electron / pion separation:Electron / pion separation:E(LKr)/Momentum trackE(LKr)/Momentum track

(spectrometer)(spectrometer)

> 13,000 cells of 2> 13,000 cells of 2XX2 cm2 cm22 filled filled with ~10 mwith ~10 m33 of liquid Krypton of liquid KryptonNorthwestern Northwestern responsibilityresponsibility

- readout - readout - calibration- calibration- corresponding trigger - corresponding trigger

31

So… What are the new puzzles & what So… What are the new puzzles & what are we doing to understand them?are we doing to understand them?

● Anomalous B decay rates – Enhance weak penguins? Physics beyond the SM

Teresa’s thesis (NA48 data 2002, KS)● Violation of unitarity?

– More than 3 generations Physics beyond the SM

Anne’s Thesis (NA48 data 2003, K±)● Anomalous ee rate

– Tensor interactions Physics beyond the SM

NA48 took special data sample this summer… (new students welcome !)

32

Note on penguin diagramsNote on penguin diagrams

Example, KL Not a good mode to look

for New Physics… gluon hard to calculate!

qg,

q

?l-)

l+)

l-)

l+)

Z, ()

Z, () Z0 penguin diagrams well understood, therefore a

better mode to look for deviations from the SM.

Example, KL e+e-

33

???

http://www.dex.ne.jp/mantan/search/std2_search_preview.jhtml?start=10&lastServiceTime=1090676093961&number=1

Not only K ! NP sensitivity of KL0ll

system :Buras,Fleisher,Recksiegel,Schwab : hep-ph/0402112

34

11stst puzzle: New Physics(NP) in K puzzle: New Physics(NP) in KLL00ll ? ll ?

Based on our Teresa’s results

SS→ → 00llll must be measured must be measured before looking for NP inbefore looking for NP in

LL→ → 00llll

Direct CPV

Indirect CPVCPC

J=2: Br(KLee) < 3x10-12

J=0: Br(KL ~ 5.2x10-12

?35

Br(KL0ee) = 5x10-12

Br(KL) = 1x10-12

Teresa’s thesis:Teresa’s thesis: First observation of First observation of KKSS0 0 l l ++l l --

BR(KS ee) = 2.8 92.3(5.8 0.8 ) x 10syststat

[PLB576 (2003)]M

K(G

eV)

M(GeV)

7 signal events

M(GeV)M

(G

eV)

6 signal events

BR(KS =1.4 91.2(2.9 0.2 ) x 10syststat

KS0e+e- KS0+-

CERN-PH-EP/2004-025

36

Implications for KImplications for KL L llllB

R(K

L

0

l l

)C

PV ×

10

12

BR

(KL

0

l l

)C

PV ×

10

12

BR(KL 0 ee)CPV × 1012 =

Constructive Destructive

37

BR(KL0 e+ e-)SM x 1011 = (3.1 or 1.3)

±1.0

BR(KL0 + -)SM x 1011 = (1.8 or 1.2)

±0.3

So can we look for NP inSo can we look for NP in LL→ → 00llll

Direct CPV

Indirect CPVCPC

?OK!OK! OK!OK!

Now we check for Now we check for NP in the EW NP in the EW PenguinsPenguins

38

Recent rearches for KRecent rearches for KLL00ll++ll-- ? ? Answer 1 Answer 1stst puzzle puzzle

Interf (-)

Interf (+)

BR(KL → 0 ee ) < 2.8 × 10-10 @ 90%CL

BR(KL→ ) < 3.8 × 10-10 @90%CL

2 event (0.87 expected background)

1 event (1 expected background)

KTeV results

Accessible from data currently being taken in Japan

39

22ndnd Puzzle: CKM matrix – Unitary Puzzle: CKM matrix – Unitary Problem?Problem?

• Unitarity of CKM matrix requires:Unitarity of CKM matrix requires:

|V|Vudud||2 2 +|V+|Vusus||22+ |V+ |Vubub||22 = 1 = 1• PDG 2004 data:PDG 2004 data:

|V|Vudud| = 0.9738 ± 0.0005 - | = 0.9738 ± 0.0005 - Neutron Neutron -decay-decay

|V|Vubub| = (3.67 ± 0.47).10| = (3.67 ± 0.47).10-3 -3 - ( |Vub|- ( |Vub|22 ≈ 10 ≈ 10-5-5 negligiblenegligible))• SM prediction SM prediction

|V|Vusus| = 0.2274 ± 0.0021| = 0.2274 ± 0.0021• Experimental value (begining 2003)Experimental value (begining 2003)

|V|Vusus| = 0.2200 ± 0.0026 | = 0.2200 ± 0.0026 |V|Vusus|| = 0.0074 ± 0.0033 ~2.2 = 0.0074 ± 0.0033 ~2.2 discrepancy discrepancy

1 % Measurement needed 1 % Measurement needed (limited by theory)(limited by theory)

40

Anne’s Thesis:Anne’s Thesis: Precise measurement of V Precise measurement of Vusus

16 π3/2 Γ(Ke3)1/2

|Vus| |f+(0)| = ————————

GF MK5/2 SEW

1/2 I1/2

KKe3e3 Br measurement: Br measurement:• Normalize KNormalize Ke3e3 events to events to π π ±±ππ00

eventseventsBr(Br(π π ±±ππ00) = 0.2113) = 0.2113±±0.00140.0014

• Selected EventsSelected Events::

KKe3e3++ ..... 59k K ..... 59k Ke3e3

-- ..... 33k ..... 33k

π π ±±ππ00 .... 468k .... 468k π π ±±ππ00....260k....260k

New Determinations of Vus

CKM unitarity ‘crisis’ has disappeared

Vu

s x f

+(0

)

•PDG02

Conference Summary ICHEP 2004, Beijing -- John Ellis

Anne’s Thesis

42

2nd Analysis Also from

NUMichal Szleper

So what was wrong? Radiative So what was wrong? Radiative CorrectionsCorrections

Without radiative Without radiative correctionscorrections

Data/MC Data/MC

Ginsberg Ginsberg (Phys. Rev. 162, 1570 (1967) Phys. Rev. 187, 2280 (1969)) (Phys. Rev. 162, 1570 (1967) Phys. Rev. 187, 2280 (1969))

With With correctionscorrections

43

Physics misconceptions cleared…Physics misconceptions cleared…

Ke3

Ke3K3

K3

EXAMPLE BASED ON NEUTRAL KAONS – T. Andre

44

Fine!Fine!Kaon Physics is Kaon Physics is still producing still producing

interesting results…interesting results…

What is next?What is next?45

Original list Original list new era to open new era to open up with the LHC programup with the LHC program

● Where did the anti-matter go? … What caused the matter-antimatter asymmetry of the Universe?

● Can we explain the matter and energy composition of the Universe?

● Why are there so many particles? … What causes their masses to be so different?

● Where does mass come from?● Do all known forces unify as some large E

scale?● Are there extra dimensions of space?

46

We are already getting ready for theWe are already getting ready for theLarge Hadron Collider (LHC)Large Hadron Collider (LHC)

PP collisions at s = 14 TeV

4 experiments

25 ns bunch spacing 2835 bunches 1011 p/bunch

Design Luminosity:1033cm-2s-1 (1034cm-2s-1)10 (100) fb-1/year

23 inelastic eventsper bunch crossing

In LEP/LHC tunnel(circonf. 26.7 km)

Planned Startup in April 200747

However the LHC program will probably However the LHC program will probably will not be enough…will not be enough…

We will probably need a Multi-TeV e+e- ASAP 2015

Rocky Kolb:Rocky Kolb:"physicists have long known that "physicists have long known that "empty""empty" space is not empty; space is not empty; it is filled by a field that gives quarks and leptons their mass. it is filled by a field that gives quarks and leptons their mass. In the Standard Model, this field is called the Higgs... In the Standard Model, this field is called the Higgs... Dark Dark energyenergy may have relationships to both supersymmetry and may have relationships to both supersymmetry and the Higgs sector, implying a new emphasis on the quantum the Higgs sector, implying a new emphasis on the quantum consistency of Higgs physics, including Higgs consistency of Higgs physics, including Higgs self-interactions."self-interactions."

Cosmologies abundanceParticle Physics properties

48

CLIC Dual beam scheme – Only viable CLIC Dual beam scheme – Only viable multi-TeV Technologymulti-TeV Technology

With superconducting cavities:Requires 33 km for 0.5 TeVCannot go beyond 0.8 TeV

CLIC150 MV/m

3TeV vs 0.5TeVCLIC vs TESLA

49

Aiming at having adesign by 2008-10

50

Exotics...One example only Exotics...One example only (TeV Machines)(TeV Machines)

Desert

New Physics at~TeV

extra dimensions could bring MPl down to TeV51

MS

Why do not see extra dimensions?Why do not see extra dimensions?

52

Only gravity propagatesOnly gravity propagatesThrough this large extra Through this large extra

dimensiondimension

Light-by-Light ScatteringLight-by-Light Scattering

53

GravitonGravitonSpin-2 Spin-2 TensorTensor

X-sections in presence X-sections in presence of gravitonsof gravitons

54

Conclusions…Conclusions…

55

Future is:

Plenty of fundamental questions to be answered

So… let’s go back to work!!!

Backup for CLICBackup for CLIC

New Preliminary NA48/2 Br(KNew Preliminary NA48/2 Br(Ke3e3))

Br(KBr(Ke3e3) = (5.14 ) = (5.14 ±± 0.02 0.02 statstat ± ± 0.06 0.06 systsyst)%)%

57

Total bckg events in signal region:

KKss eeee Backgrounds Backgrounds

Physical: conversions (mee> 0.165 GeV/c2) KL ee(irreducible)decays (momentum asymmetry cut)

Accidental: Study of out of time events

< 0.01 (KS D D ) 0.08 negligible

0 0

0.07

Signal region

0.100.040.15

58

KKss Backgrounds Backgrounds

Total bckg events in signal region:

Physical: KL (cut on KS c) KL (irreducible)decays (Momentum asymmetry cut)

Accidental: Study of out of time events

negligible 0.04 negligible

0.18

Signal region

0.190.120.22

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Documents

Mayda M.Velasco Northwestern University Oct. 1, 2004