Sub Z Supersymmetry M.J. Ramsey-Musolf Precision Electroweak Studies in Nuclear Physics

Sub Z Supersymmetry

M.J. Ramsey-Musolf

Precision Electroweak Studies in Nuclear Physics

NSAC Long Range Plan

• What is the structure of the nucleon?

• What is the structure of nucleonic matter?

• What are the properties of hot nuclear matter?

• What is the nuclear microphysics of the universe?

• What is to be the new Standard Model?

Neutrino physics

Precision measurements: -decay, -decay, parity violating electron scattering, EDM’s…

What can they teach us about the new Standard Model?

The Standard Model of particle physics is a triumph of late 20th century physics

• It provides a unified framework for 3 of 4 (known) forces of nature in context of renormalizable gauge theory


• Utilizes a simple & elegant symmetry principle to organize what we’ve observed

SU(3)C SU(2)L U(1)Y



SU(3)C SU(2)L U(1)Y

Strong (QCD)

Scaling violations in DIS Asymptotic freedomR(e+e-)Heavy quark systems Drell-Yan



SU(3)C SU(2)L U(1)Y

Electroweak(=weak + QED)

“Maximal” parity violation Conserved Vector Current CP-Violation in K, B mesons Quark flavor mixingLepton universality…..


• Most of its predictions have been confirmed

e

e

q

q

Z 0

Parity violation in neutral current processes: deep inelastic scattering, atomic transitions



Neutral currents mix

J0

f

f

f

fJ

Y

J

JZ

sin2W



New particles should be found

• W, Z0

• 3rd fermion generation (CP violation, anomaly)

• Higgs boson Not yet!

We need a new Standard Model

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, SNS, NIST

Outline

I. SM Radiative Corrections & Precision Measurements

II. Defects in the Standard Model

III. An Example Scenario: Supersymmetry

IV. Low-energy Probes of Supersymmetry

• Precision measurements

• “Forbidden processes”

• Weak decays• lepton scattering

Outline

I. SM Radiative Corrections & Precision Measurements

II. Defects in the Standard Model

III. An Example Scenario: Supersymmetry

IV. Low-energy Probes of Supersymmetry

• Precision measurements

• “Forbidden processes”

• EDM’s• 0 decay• !e, !e…

I. Radiative Corrections & Precision Measurements in the SM

The Fermi Theory of weak decays gave a successful, leading-order account

ee

n pee

e

e

n

p

e

e

HEFF

GF

2

L e L e

HEFF

GF

2p (gV gA5)n e L e

(1 5)

gV 1, gA 1.26

GF

GF 1

Fermi’s theory could incorporate higher order QED contributions

QED radiative corrections: finite

1

GF

2 m5

192 31

2

25

4 2

e

e

e

e

The Fermi theory has trouble with higher order weak contributions

e

e

e

e

e

e

e

e

e

Weak radiative corrections: infinite

Can’t be absorbed through suitable re-definition of GF in HEFF

All radiative corrections can be incorporated in the Standard Model with a finite number of terms

e

e

W

e

e

e

e

W

Z 0

e

e

e

W

Z 0

g g g Re-define g

Finite

GF encodes the effects of all higher order weak radiative corrections

GF

2

g2

8MW2 1 r

e

e

W

e

e

e

W

Z 0

e

e

W

W

gg

rdepends on parameters of particles inside loops

1

GF

2 m5

192 3

Comparing radiative corrections in different processes can probe particle spectrum

GFZ

2

g2

8MW2 1 rZ

rdiffers from rZ

e

Z 0

Z 0

gg

Z 0

e

Z 0

Z 0

e

e

e

e

e


t

t

Z 0

Z 0

t

b

W

W

GFZ

GF 1 rZ r

rZ ~

lnmt

2

MW2

r ~

mt2

MW2


• 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

Radiative corrections

Direct Measurements

Stunning SM Success

J. Ellison, UCI

Global Analysis

per dof = 25.5 / 15

M. Grunenwald

Agreement with SM at level of loop effects ~ 0.1%

Collider Studies

R. Clare, UCR

LEPSLDTevatron

Collider Studies

Collider Studies

MW

Mt

A

had

Tevatron

Collider Studies

Collider Studies

Collider Studies“Blue Band”

Global Fit: Winter 2004

per dof = 16.3 / 13

II. Why a “New Standard Model”?

• There is no unification in the early SM Universe

• The Fermi constant is inexplicably large

• There shouldn’t be this much visible matter

• There shouldn’t be this much invisible matter

The early SM Universe had no unification

e e()

g g()

Couplings depend on scale

Energy Scale ~ T

4gi

2

log10 ( / 0 )

Standard Model

Present universe Early universe

Weak scale Planck scale

High energy desert


4gi

2

log10 ( / 0 )

Standard Model



High energy desert

4gi

2A “near miss” for grand unification


Gravity

log10 ( / 0 )

Standard Model


Planck scale

High energy desert

The Fermi constant is too large

Weak scale

4gi

2GF would shrink

UnificationNeutrino mass Dark Matter

The Fermi constant is too large

GF

2

g2

8MW2

MW2

g2WEAK2

4

WEAK2 ~ M

2

H 0

H 0

NEW

WEAK ~ 250 GeV GF ~ 10-5/MP2

A smaller GF would mean disaster

The Sun would burn less brightly

p p d e e ~ GF2

Elemental abundances would change

p e n eTfreeze out ~ GF

-2/3

Y (4He) 2n p

1 n p

n

pexp

mn mp

kT

Smaller GF

More 4He, C, O…

There is too much matter - visible & invisible - in the SM Universe

Visible Matter from Big Bang Nucleosynthesis

nB nB

~ 10 10 n Measured abundances

nB nB

~ 10 18 nSM baryogenesis

Insufficient CP violation in SM

There is too much matter - visible & invisible - in the SM Universe

Invisible Matter

Visible

Dark

M M c

Insufficient SM CP violation

No SM candidate

S. Perlmutter

There must have been additional symmetries in the earlier Universe to

• Unify all forces

• Protect GF from shrinking

• Produce all the matter that exists

• Account for neutrino properties

• Give self-consistent quantum gravity

III. Supersymmetry

• 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

SUSY may be one of the symmetries of the early Universe

Supersymmetry

eL,R , qL,R

W ,Z ,, g

˜ W , ˜ Z , ˜ , ˜ H u, d ˜ , ˜ 0Charginos, neutralinos

Fermions Bosons

˜ e L,R , ˜ q L,R sfermions

˜ W , ˜ Z , ˜ , ˜ g gauginos

˜ H u , ˜ H dHiggsinos

H

Hu,Hd

4gi

2

log10 ( / 0 )

Standard Model



Couplings unify with SUSY

Supersymmetry

High energy desert

SUSY protects GF from shrinking

H 0

H 0

NEW

H 0

H 0

˜ NEW

WEAK2 ~ M

2 M ˜ 2 log terms

=0 if SUSY is exact

SUSY may help explain observed abundance of matter

Cold Dark Matter Candidate

0 Lightest SUSY particle

Baryonic matter

˜ t HUnbroken phase

Broken phase

CP Violation

SUSY must be a broken symmetry

Visible World

Hidden World

Flavor-blind mediation

SUSY Breaking

M ˜ e me

M ˜ q mq

M ˜ MW ,Z ,

Superpartners have not been seen

Theoretical models of SUSY breaking

Minimal Supersymmetric Standard Model (MSSM)

˜ M M

Lsoft gives ˜ M Mcontains 105 new parameters

How is SUSY broken?

LSM LSM LSUSY + Lsoft+

How is SUSY broken?


Visible Sector: Hidden Sector: SUSY-breakingMSSM

Gravity-Mediated (mSUGRA)

M1 / 2 M02 A0 b0

˜ W , ˜ Z , ˜ , ˜ g ˜ f

˜ f ˜ f

HHu Hd

How is SUSY broken?


Visible Sector: Hidden Sector: SUSY-breakingMSSM

Gauge-Mediated (GMSB)

˜ W , ˜ Z , ˜ , ˜ g

M1 / 2 a

4 M0

2 2 a

4

Ca

˜ f

W ,Z ,...

A0 0

b0 0

messengers

Mass evolution

˜ M a gaugino mass

Ca

f 0 group structure

t

ln

M f increases as decreases

M q M increases faster than (C3 q 0,C3

0)

dM f

2

dt aCa

f

a1

3

˜ M a2

M q M at the weak scale

Sfermion Mixing

ˆ M 2 ˜ M f L

2 MLR2

MLR2 ˜ M f R

2

MLR2

m f ( tan A f )

m f ( cot A f )

Qf < 0

Qf > 0

˜ f L , ˜ f R ˜ f 1,˜ f 2

MSSM and R Parity

PR 1 3(B L) 1 2S

Matter Parity: An exact symmetry of the SM

SM Particles:

Superpartners:

PR 1PR 1

MSSM and R Parity

MSSM conserves PR vertices have even number of superpartners

Consequences

Lightest SUSY particle˜ 0 is stable

viable dark matter candidate

Proton is stable

Superpartners appear only in loops

Documents

Sub Z Supersymmetry M.J. Ramsey-Musolf Precision Electroweak Studies in Nuclear Physics