nuclear physics and the new standard model m.j. ramsey-musolf wisconsin-madison npac theoretical...

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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?

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