Flavor Physics

Gene GolowichPhysics (UMass)

NEPPSR-07 August 15, 2007

Goals of this Talk

1] Overview of Flavor Physics2] Update on Meson Mixing

Strong Physics

Flavor SpectroscopyParticles (‘hadrons’) with quarks

Flavor SymmetriesIsospin, Flavor SU(3)

Electroweak Physics

Flavor DecaysΔF = ± 1 transitions

Meson-antimeson MixingΔF = ± 2 transitions

Flavor Topics

Color:The charges on quarks and gluonsby which they interact strongly.

Flavor:A label that distinguishes the six different kinds of quarks.

Q=+2e/3 Q=-e/31] Up u Down d 2] Charm c Strange s 3] Top t Bottom b

Color vs Flavor

Mass Values (PDG)

1] Up (1.5→3.0 MeV) Down (3.0→7.0 MeV)

2] Charm (1.25 GeV) Strange (95 MeV)

3] Top (172→174 GeV) Bottom (4.2→4.7 GeV)

Explanation of Values

There is none. No known formula!Are quark masses random-valued?

The Quark Masses

Ordinary

P π+

Strange

Ω K+

Charm

D+ Ds

Bottom

Bd Bs

Flavor Hadrons

dc

bd

sss

du

su

sc

bs

duu

The D states are in blue and the Ds

states are in violet.

Spectra of D and Ds

A different perspective, now comparing experiment with theory.

Spectra of D and Ds

Alternative Explanations?

Maybe a molecule?

Or perhaps a four-quark state?

Ξb-(5774)

Ξb- is the only observed baryon formed

of quarks from all three families! Detected by the D0 collaboration at Fermilab.

A New Flavor Hadron

bsd

New Flavors via e+e-

The top quark was discovered in 1995 via proton-antiproton collisions at Fermilab.

Top Production via PP

Direct Searches (PDG)

m > 190 GeV (p p, quasi-stable b')m > 199 GeV (p p, nc decays) m > 128 GeV (p p, cc decays) m > 46.0 GeV (e+ e−, all decays)

Indirect Test (S Parameter)

Additional FamiliesIf NF more families, then S ~ 0.05 NF

Data and S = S(Mw,sw2)

SLD ALR: S = -0.11(9)(15) LEP AFB: S = +0.55(9)(15)

A Fourth Family?

Traditional Flavor Sectors An enormous database now exists for:

Strange (s-quark)Charm (c-quark)Bottom (b-quark)

Underlying Quark IssuesBut there is so much that is not yet understood:

Quark masses? A mystery! Quark substructure? None seen.Fourth family? No evidence.

Partial Summary

Top-proton Top-pion

PTOP π+TOP

A Basic Fact:

All the heavy quarks are unstable. The top-quark decays too quicklyfor a hadron to form!

Where are the Top-hadrons?

dtd

ut

Why test proton decay? Possible connection with ‘Grand Unification’.

Some Lifetimes

s10x4Wbt

s10x1...πDB

s10x4...πKD

s10x9...ππK

ePN

yr10to10eP

25

12d

130

110

e

33310

−+

−+−

−+−

−+−

−

+

→

+→

+→

+→

→

>+→

s7.885

...

ν

π

One Picture = 103 Words

Z0,W± Factories

Discover Z0,W± and study properties:

e+ e- → Z0 → X (Ecm = MZ)e+ e- → W+ W- (Ecm > 2MW)

B-Factories

Study B-meson properties, especiallyweak decays and CP-violations (CPV).

e+ e- → Υ(4S) → (Ecm ≈ 10.5 GeV)

Flavor Factories

bb

Weak Decays on Google

Weak decays are really important.22 million hits!

Weak Decays on Google

Weak decays are really important.22 million hits!

But Paris Hilton has 60 million hits!

Charged-current Decays

Flavor change occurs via W-bosons and involves products of factors {Vij}.

The collection of factors Vij forms a matrix.

Much effort has gone into studies of the matrix V, which is unitary V†V=1, but whose matrix elements are as unknown as quark masses.

The Weak Decay Matrix V

Matrix V and Experiment

The Standard Model

Constructed (1967-1974)

Experimentally Tested (1967-Now)

Remaining Issues?

Higgs boson: TEVATRON, LHC

CP-violation [CPV]: BaBar, Belle

C, P and T

Parity

X = (t,x) (t,-x )Particle-type unaffected

Time-reversal

X = (t,x) (-t,x )Particle-type unaffected

Charge Conjugation

Particle AntiparticleSpacetime unaffected

Defining C, P and T

Spatial Momentum (P = mv)

P: p = mdx/dt -p

T: p = m dx/dt -p

Angular Momentum (L = x x p)

P: L = -x x -p L

T: L = x x -p -L

Effect on Classical Particles

C and P Violation:

Prediction: 1956Discovery: 1957

CP Violation:

Prediction: None!Discovery: 1964

A Bit of History

Predictions of CPT

Testing for CPT

The Product CPT

ΓΓandMM ==

Two families (Cabibbo)

V =

Three families (Kobayashi, Maskawa)

Called the ‘CKM matrix’.This notation due to Euler (1750)Phase δ indicates CP-violation.

Matrix V and CP Violation

⎥⎦

⎤⎢⎣

⎡− θcosθsin

θsinθcos

CKM is ‘Hierarchical’!

Wolfenstein combined the unitarity of Vwith its hierarchical form to show:

λ ≅ 0.22 is the smallness parameter. η is the CP-violating parameter.

It has been the goal of B-factories to determine ρ and η.

A Popular CKM Notation

ρ and η

Much learned, but can one do more?

The ‘Unitarity Triangle’

• The apex (ρ,η) of the unitarity triangle can be determined in independent ways– Only tree processes (no new physics)– Only loop processes (new physics

window)– Only CP violating processes– Only CP conserving processes– Only CKM angles

• Inconsistency would indicate New Physics

• More to the study of heavy flavor than precision determination of CKM parameters

Some Examples

Only Loop

Only Tree

Only Angles

Only CPV

Only CPC

There is much more to Flavor Physics, involving higher orders in weak effects:

Meson-antimeson Mixing

These involve two changes in flavor and have experienced much progress recently

Rare Decays

A well studied example (see S. Willocq) is the rare decay Bd → K + μ+μ-

Additional Flavor Topics

Uncoupled Pendulums

ω1 = ω2 Γ1 = Γ2

Math of Mixing I

Coupled Pendulums

Δω = ω1 – ω2 ΔΓ = Γ1 - Γ2

Math of Mixing II

The Standard Model allows matter to convert to antimatter spontaneously.

Get normal modes D1,2. The D0 is a combination of these. A D0 at t=0 will oscillate back and forth with its antiparticle until decay ends the process.

Ex: D0 Mixing

000

k/2)tΓiM(

k

,210000

DtfDtftD

1,2)(k(0)De(t)D

DD,D0D|H|D

kk

)()()( −+

−−

+=

==

→⇒≠><

The ‘Coupling Spring’

Mixing of K Mesons

Mixing of Bd Mesons

Mixing of Bs Mesons

Mixing of D0 Mesons

Status of D0 Mixing

At present, the meaured values are:

xD =

yD =

The above xD is a 2.4 σ effect.PRL discovery criteria are:a) ‘Observation’: >5σb) ‘Evidence’: 3σ-to-5σc) ‘Measurement’: <3σ

ΓΔM x =

2ΓΓ-Γy 21=

33.03.4 10)(8.7 −+

− ⋅

3102.1)(6.6 −⋅±

Our recent work on the subject:1] yD : PRL 98 (2007) 181808-1

2] xD: arXiv:0705.3650 [hep-ph]

Our Thoughts on yD and xD

NP can affect ΔΓ!Via the ΔC = ± 1 interaction vertex.Processes like

Golowich, Pakvasa, Petrov, PRL 98 (2007) 181801.[Comment]: Chen, Geng, Nam, PRL 99 (2007) 019101.

[Comment2]: Yeghiyan, arXiv 0707.3285 [hep-ph].

NPSM

21qquc →

New Physics and yD

New Physics and xD

As the LHC era begins,many extraspossible (21 models in GHPP)*

• Extra gauge bosons(LR models, etc)

• Extra scalars(Multi-Higgs models, etc)

• Extra fermions(Little Higgs, etc)

• Extra dimensions(Universal extra dimensions, etc)

• Extra global symmetries(SUSY, etc)

*GHPP: arXiv 0705.3650 [hep-ph]

List of NP Models

Fourth GenerationQ=-1/3 Singlet QuarkQ=+2/3 Singlet QuarkLittle HiggsGeneric Z’Family SymmetriesLeft-Right SymmetriesAlternate L-R SymmetriesVector Leptoquark BosonsFl-Cons Two-Higgs DbltFl-Chnge Neutral Higgs IFl-Chnge Neutral Higgs II Scalar Leptoquark BosonsHigglessUniversal Extra DimsSplit FermionWarped GeometriesMinimal SUSY StandardSUSY AlignmentSUSY with RPVSplit SUSY

Of the 21 NP models, how many turn out to yield contributions too small for D0

mixing at the observed 10-2 level?

Comment: Note many NP models have been on the market for years (e.g., SUSY has been studied for over 30 yrs)and their parameter spaces have been steadily constrained.

* If you have already seen the paper, please keep quiet.

Challenge to the Audience*

Ineffective Models:

Four yield no constraints:1. Split supersymmetry2. Universal Extra Dimensions3. Left-right symmetric4. FC two-Higgs doublet

Constrainable Models:

There are 17 which can, in principle, exceed the observed xD. For these, we can get constraints on masses and mixing parameters.

Answer to Challenge

What ‘is’ Split SUSY?:

• New variant of SUSY (2003-4)• SUSY breaks at mS >> 1000 TeV• Scalars (except Higgs) have mass ~ mS

• Fermions have usual weak scale mass

Why So Small in D0 Mixing?:

Large D0 mixing in SUSY involves squark (i.e.scalar quarks) amplitudes. But squark masses are huge in Split SUSY. Thus the mixing is suppressed.

Split SUSY – Why So Small?

What ‘are’ Universal Extra Dimensions?

• Variant (2000) of having TeV-1-sized extra dimensions

• No branes in this approach• All SM fields reside in the bulk• Usually one extra dimension

Why So Small in D0 Mixing?:

Each SM field has an infinity of KK excitations. GIM cancellations affect all save a few b-quark KK terms, but these are CKM suppressed.

UEDs – Why So Small?

Plot xD(2/3) vs λuc:

D0-mixing limit on λuc is about 102 better than that from 4x4 CKM unitarity.

Limit on Q=2/3 Quark Singlet

Fourth GenerationQ=-1/3 Singlet QuarkQ=+2/3 Singlet QuarkLittle Higgs

Generic Z’Family SymmetriesLeft-Right SymmetriesAlternate L-R Symmetries

Vector Leptoquark BosonsFl-Cons Two-Higgs DoubletFl- Change Neutral Higgs IFl-Change Neutral Higgs II Scalar Leptoquark BosonsHigglessUniversal Extra DimensionsSplit FermionWarped GeometriesMinimal SUSY Standard

SUSY AlignmentSUSY with RPVSplit SUSY

|Vub’ Vcb’| mb’ < 0.5 GeVs2 ms < 0.27 GeV|λuc| < 2.4 10-4

Tree: Same as Q=-1/3 Singlet QkBox: Can reach observed xDMZ’/C > 2.2 103 TeVm1/f > 1.2 103 TeVNo ConstraintMR > 1.2 TeV (mD1 = 0.5 TeV)(Δm/mD1)/MR > 0.4 TeV-1

MVLQ > 55 (λPP/0.1) TeVNo ConstraintmH/C > 2.4 103 TeVmH/|Δuc| > 600 GeVSee RPV SUSYM > 100 TeVNo ConstraintM/Δy| >600 GeVM1 > 3.5 TeV|(δu

12)LR,LR| < 0.035 |(δu

12)LL,RR| < 0.25M > 2 TeVλ’12kλ’11k/m < 1.8 10-4/100 GeVNo Constraint

Results of xD Analysis

The Past: Many wonderful studies of flavor physics!Great success for the Standard Model.But more sensitivity desired.Super-flavor factories under consideration.

The Future: A] Unexplained issues in the Higgs sector. Most believe the LHC will be a discovery machine for New Physics at the 1-10 TeV Scale, perhaps Supersymmetry

B] A few (Anthropic types) quietly expect LHC to find nothing but the SM Higgs. Horrors!But at least LHC would be a formidable flavor machine (LHC-B detecting ~1012 B’s/year).

Concluding Remarks

S