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Nuclear Physics and the New Standard Model. M.J. Ramsey-Musolf Wisconsin-Madison. NPAC. Theoretical Nuclear, Particle, Astrophysics & Cosmology. http://www.physics.wisc.edu/groups/particle-theory/. Taiwan , June 2008. - PowerPoint PPT Presentation
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Nuclear Physics and the New Standard ModelM.J. Ramsey-MusolfWisconsin-MadisonQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
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http://www.physics.wisc.edu/groups/particle-theory/
NPACTheoretical Nuclear, Particle, Astrophysics & Cosmology
Taiwan , June 2008
The Big Picture
Fifty years of PV in nuclear physics
Nuclear physics studies of s & fundamental symmetries played an essential role in developing & confirming the Standard Model
Our role has been broadly recognized within and beyond NP
Solar s & the neutrino revolution
The next decade presents NP with a historic opportunity to build on this legacy in developing the “new Standard Model”
The value of our contribution will be broadly recognized outside the field
Goals
• Show how studies of fundamental symmetries & neutrinos in nuclear physics can complement high energy searches for the “new Standard Model”
• Introduce some of the basic ideas & theoretical machinery, but leave details to your future reading
• Describe recent progress & open problems
• Encourage you to learn more and get involved in research !
Outline
I. Overview & Motivation
II. Illustrative Scenario: Supersymmetry
III. Neutrinos: Lepton Number &
IV. EDMs & the Origin of Matter
V. Electroweak Precision Observables
VI. Weak Decays
VII. Neutral Current Processes
References
• “ Low Energy Precision Test of Supersymmetry”, M.J. Ramsey-Musolf & S. Su, Phys.Rept.456:188, 2008, e-
Print: hep-ph/0612057Model”
• “Low energy tests of the weak interaction”, J. Erler & M. J. Ramsey-Musolf , Prog.Part.Nucl.Phys.54:351 442, 2005, e-Print: hep-ph/0404291
Plus many references therein…
• Why New Symmetries ?
• Why Low Energy Probes ?
I. Motivation
Fundamental Symmetries & Cosmic History
Beyond the SM SM symmetry (broken)
Electroweak symmetry breaking: Higgs ?
Fundamental Symmetries & Cosmic History
Standard Model puzzles Standard Model successes
to explain the microphysics of the present universe
It utilizes a simple and elegant symmetry principle
SU(3)c x SU(2)L x U(1)Y
• Big Bang Nucleosynthesis (BBN) & light element abundances
• Weak interactions in stars & solar burning
• Supernovae & neutron stars
Fundamental Symmetries & Cosmic History
Standard Model puzzles Standard Model successesHow is electroweak symmetry broken? How do elementary particles get mass ?
Puzzles the St’d Model may or may not solve:
SU(3)c x SU(2)L x U(1)Y
Electroweak symmetry breaking: Higgs ?
U(1)EM
• Non-zero vacuum expectation value of neutral Higgs breaks electroweak sym and gives mass:
• Where is the Higgs particle?
• Is there more than one?
Fundamental Symmetries & Cosmic History
Beyond the SM SM symmetry (broken)
Electroweak symmetry breaking: Higgs ?
Puzzles the Standard Model can’t solve
1. Origin of matter2. Unification & gravity
3. Weak scale stability4. Neutrinos
What are the symmetries (forces) of the early universe beyond those of the SM?
Fundamental Symmetries & Cosmic History
Beyond the SM SM symmetry (broken)
Electroweak symmetry breaking: Higgs ?
Cosmic Energy Budget
?
Baryogenesis: When? CPV? SUSY? Neutrinos?
WIMPy D.M.: Related to baryogenesis?
“New gravity”? Lorentz violation? Grav baryogen ?
• C: Charge Conjugation
• P: Parity
4πgi
2
log10(μ / μ0)
Standard Model
Present universe Early universe
Weak scale Planck scale
High energy desert
Fundamental Symmetries & Cosmic History
Unification?
Use gauge coupling energy-dependence look back in time
Energy Scale ~ T
€
e = e(μ)
g = g(μ)
€
+L
€
+
€
+
4πgi
2
log10(μ / μ0)
Standard Model
Present universe Early universe
Weak scale Planck scale
High energy desert
Gravity
Fundamental Symmetries & Cosmic History
4πgi
2A “near miss” for grand unification
Is there unification? What new forces are responsible ?
log10(μ / μ0)
Standard Model
Present universe Early universe
Planck scale
High energy desert
Weak scale
4πgi
2Weak scale unstable:
Why is GF
so large?
UnificationNeutrino mass Origin of matter
Fundamental Symmetries & Cosmic History
Weak Int Rates:Solar burningElement abundances
€
GF ~ 1 MWEAK2
There must have been additional symmetries in the earlier Universe to
• Unify all matter, space, & time
• Stabilize the weak scale
• Produce all the matter that exists
• Account for neutrino properties
• Give self-consistent quantum gravity
Supersymmetry, GUT’s, extra dimensions…
What are the new fundamental symmetries?
Two frontiers in the search
Collider experiments (pp, e+e-, etc) at higher energies (E >> MZ)
Indirect searches at lower energies (E < MZ) but high precision
High energy physics
Particle, nuclear & atomic physics
CERN
Ultra cold neutronsLarge Hadron Collider
LANSCE, NIST, SNS, ILL
Precision Probes of New Symmetries
Beyond the SM SM symmetry (broken)
Electroweak symmetry breaking: Higgs ?
New Symmetries
1. Origin of Matter2. Unification & gravity
3. Weak scale stability4. Neutrinos
€
μ−
€
μ
€
˜ χ 0
€
˜ μ −
€
˜ ν μ
€
e
€
W −
€
e−
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QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
?
LHC: energy frontier
Low-energy: precision frontier
Precision & Energy Frontiers
Radiative corrections
Direct Measurements
Stunning SM Success
J. Ellison, UCI
€
GFZ
GFμ
≈ 1+ ΔrZ − Δrμ( )
€
t
€
t
€
Z 0
€
Z 0
€
t
€
b
€
W +
€
W +
• Precision measurements predicted a range for mt
before top quark discovery
• mt >> mb !
• mt is consistent with that range
• It didn’t have to be that way
Probing Fundamental Symmetries beyond the SM:
Use precision low-energy measurements to probe virtual effects of new symmetries & compare with collider results
Precision Frontier:
• Precision ~ Mass scale
• Look for pattern from a variety of measurements
• Identify complementarity with collider searches
• Special role: SM suppressed processes
Precision, low energy measurements can probe for new symmetries in the desert
Precision ~ Mass Scale
€
δNEW =ΔONEW
OSM≈
α
π
M˜ M
⎛
⎝ ⎜
⎞
⎠ ⎟2 M=mμ δ ~ 2 x 10-9
δexp ~ 1 x 10-9
M=MW δ ~ 10-3
Interpretability
• Precise, reliable SM predictions
• Comparison of a variety of observables
• Special cases: SM-forbidden or suppressed processes
• Why Supersymmetry ?
• Key Features of SUSY
II. Illustrative Case: SUSY
4πgi
2
log10(μ / μ0)
Standard Model
Present universe Early universe
Weak scale Planck scale
Couplings unify with SUSY
Supersymmetry
High energy desert
GF is Too Large
€
GF
2=
g2
8MW2
=1
2 μWEAK2
GF ~ 10-5/MP2 μWEAK ~ 250 GeV
€
H 0
€
H 0
€
ϕ NEW
€
ΔμWEAK2 ~ Mϕ
2
€
mh2 = 2λ μWEAK
2
SUSY protects GF
€
H 0
€
H 0
€
˜ ϕ NEW
€
ΔμWEAK2 ~ Mϕ
2 − M ˜ ϕ 2 + log terms
=0 if SUSY is exact
€
H 0
€
H 0
€
ϕ NEW
GF & the “hierarchy problem”
SUSY Relation:
Quadratic divergence ~ UV2 cancels
After EWSB:
SUSY may help explain observed abundance of matter
Cold Dark Matter Candidate
0 Lightest SUSY particle
Baryonic matter: electroweak phase transition
˜ t HUnbroken phase
Broken phase
CP Violation
SUSY: a candidate symmetry of the early Universe
• Unify all forces
• Protect GF from shrinking
• Produce all the matter that exists
• Account for neutrino properties
• Give self-consistent quantum gravity
3 of 4
Yes
Maybe so
Maybe
Probably necessary
Minimal Supersymmetric Standard Model (MSSM)
Supersymmetry
eL,R , qL,R
W,Z,γ,g
˜ W , ˜ Z ,˜ γ , ˜ H u,d ⇒ ˜ χ ±, ˜ χ 0Charginos, neutralinos
Fermions Bosons
˜ e L,R , ˜ q L,R sfermions
˜ W , ˜ Z ,˜ γ , ˜ g gauginos
˜ H u,˜ H dHiggsinos
€
Hu,Hd
No new coupling constants
Two Higgs vevs
Supersymmetric Higgs mass, μ
SUSY and R Parity PR = −1( )3(B−L)
−1( )2S
If nature conserves PR vertices have even number of superpartners
Consequences
Lightest SUSY particle˜ χ 0( ) is stable
viable dark matter candidate
Proton is stable
Superpartners appear only in loops
WRPV = ijk LiLjEk + ijk LiQjDk +μ/
i LiHu
+ ijkUiDjDk
ΔL=1
ΔB=1
Li, Qi
Ei, Ui, Di
SU(2)L doublets
SU(2)L singlets
proton decay: Set
ijk =0
R-Parity Violation (RPV)“Superpotential” : a convenient way to derive supersymmetric interactions by taking derivatives w.r.t. scalar fields
Four-fermion Operators
μ−
ν e e−
νμ
˜ e Rk
12k 12k
e−
d e−
d
˜ q Lj
1j1
1j1
ΔL=1 ΔL=1
Δ12k =λ12k
2
4 2GF M˜ e Rk
2 Δ1j1/ =
λiji/ 2
4 2GFM˜ q Lj
2
SUSY must be a broken symmetry
Visible World
Hidden World
Flavor-blind mediation
SUSY Breaking
€
M ˜ e >> me
M ˜ q >> mq
M ˜ χ >> MW ,Z ,γ
Superpartners have not been seen
Theoretical models of SUSY breaking
How is SUSY broken?
MSSM SUSY Breaking
Superpartners have not been seen
Theoretical models of SUSY breaking
How is SUSY broken?
~ 100 new parameters40 new CPV phasesFlavor mixing parameters
Gaugino mass
Sfermion mass
Triscalar interactions
O(1) CPV phases & flavor mixing ruled out by expt: “SUSY CP” & “SUSY flavor” problems
One solution: af ~ Yf
MSSM: SUSY Breaking Models I
Flavor-blind mediation
Visible Sector: Hidden Sector: SUSY-breakingMSSM
Gravity-Mediated (mSUGRA)
M1/2 M02 A0 b0
˜ W , ˜ Z ,˜ γ , ˜ g ˜ f
˜ f ˜ f
HHu Hd
MSSM: SUSY Breaking Models II
Flavor-blind mediation
Visible Sector: Hidden Sector: SUSY-breakingMSSM
Gauge-Mediated (GMSB)
˜ W , ˜ Z ,˜ γ , ˜ g
M1/2 ≈αa
4πΛ M0
2 ≈Λ2 αa
4π⎛ ⎝
⎞ ⎠ Ca∑
˜ f W,Z,...
A0 ≈0b0 ≈0
messengers
MSSM: SUSY Breaking Models III
Flavor-blind mediation
Visible Sector: Hidden Sector: SUSY-breakingMSSM
dM˜ f
2
dt=− αaCa
˜ f
a=1
3
∑ ˜ M a2
Parameter evolution: mass
M˜ q >M˜ l
at the weak scale
Gaugino-Higgsino Mixing
Neutralino Mass Matrix
M1
-μ
M2
-mZ cos sin W mZ cos cos W
mZ sin sin W -mZ sin sin W 0
0
0
0
-μ
-mZ cos sin W mZ cos cos W
mZ sin sin W -mZ sin sin WMN =
Chargino Mass Matrix
M2
μMC =
cos2mW
sin2mWT << TEW : mixing
of H,W to ~ ~ ~ ~
T ~TEW : scattering
of H,W from
background field
~~CPV
B W Hd Hu
BINO WINO HIGGSINO
T << TEW
Relic Abundance of SUSY DM
Neutralino Mass Matrix
M1
-μ
M2
-mZ cos sin W mZ cos cos W
mZ sin sin W -mZ sin sin W 0
0
0
0
-μ
-mZ cos sin W mZ cos cos W
mZ sin sin W -mZ sin sin WMN =
T << TEW : mixing
of H,W to ~ ~ ~ ~
B W Hd Hu
BINO WINO HIGGSINO
€
˜ χ 10
€
˜ χ 10
€
˜ t
€
t
€
t
+ res0
1~
01
~±ji χχ ~,~0
ZW ,
ZW ,+ coannihilation
Sfermion Mixing
Sfermion mass matrix
€
ˆ M 2 =˜ M ̃ f L
2 MLR2
MLR2 ˜ M ̃ f R
2
⎡
⎣ ⎢ ⎢
⎤
⎦ ⎥ ⎥
MLR2 =
mf (μtanβ −Af )
mf (μcotβ −Af )⎧ ⎨ ⎩
Qf < 0
Qf > 0
T << TEW : mixing
of fL, fR to f1, f2
~ ~ ~ ~
T ~TEW : scattering
of fL, fR from
background field
~~
Test
€
H 0
€
H 0
€
˜ ϕ NEW
€
H 0
€
H 0
€
ϕ NEW
No new coupling constants
Two Higgs vevs
Supersymmetric Higgs mass, μ
~ 100 new parameters40 new CPV phasesFlavor mixing parameters
“Superpotential” : a convenient way to derive supersymmetric interactions by taking derivatives w.r.t. scalar fields
Neutral Current Interactions II
Neutral current l+f --> l+f at one loop:
Normalization:
Vector & axial vector couplings:
Normalize to Gμ: Remove Δrμ
Weak mixing:
Vertex & ext leg
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The parameter:
Weak mixing:
Can impose constraints from global fits to EWPO via S,T,U-dependence of these quantities