Flavor Physicsphysics.bu.edu/NEPPSR/2007/TALKS-2007/Flavor_Golowich.pdfFlavor Physics Gene Golowich...
Transcript of Flavor Physicsphysics.bu.edu/NEPPSR/2007/TALKS-2007/Flavor_Golowich.pdfFlavor Physics Gene Golowich...
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