Sub Z0 Supersymmetry - UW-Madison Department of Physics
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Transcript Sub Z0 Supersymmetry - UW-Madison Department of Physics
Sub Z0 Supersymmetry
Precision Electroweak Physics
Below the Z0 Pole
M.J. Ramsey-Musolf
Fundamental Symmetries & Cosmic History
• What were the fundamental symmetries
that governed the microphysics of
the early universe?
The (broken) symmetries of the Standard Model of particle
physics work remarkably well at late times, but they leave
many unsolved puzzles pertaining to the early universe
• What insights can low energy (E << MZ)
precision electroweak studies
provide?
New forces and their symmetries generally imply the existence
of new particles. Looking for their footprints in low energy
processes can yield important clues about their character
Fundamental Symmetries & Cosmic History
Standard Model puzzles
Standard Model successes
Fundamental Symmetries & Cosmic History
It provides a unified framework
for understanding 3 of the 4
(known) forces of nature in the
present universe
Standard Model puzzles
Standard Model successes
Fundamental Symmetries & Cosmic History
It utilizes a simple and elegant
symmetry principle
SU(3)c x SU(2)L x U(1)Y
Standard Model puzzles
Standard Model successes
Fundamental Symmetries & Cosmic History
It utilizes a simple and elegant
symmetry principle
SU(3)c x SU(2)L x U(1)Y
Strong (QCD)
Scaling violations in DIS
Asymptotic freedom
R(e+e-)
Heavy quark
systems Model
Drell-Yan
Standard
puzzles
Chiral dynamics
Standard Model successes
Fundamental Symmetries & Cosmic History
It utilizes a simple and elegant
symmetry principle
SU(3)c x SU(2)L x U(1)Y
Electroweak
“Maximal” parity violation
CP violation in K & B mesons
Quark flavor mixing
Lepton universality
Conserved
Standard
Model vector
puzzles
current
Radiative corrections
Standard Model successes
Fundamental Symmetries & Cosmic History
Most of its predictions have
been confirmed
Parity violation in neutral
current interactions
Atomic transitions
& scattering
e
Z0
q
Standard Model puzzles
e
q
Standard Model successes
Fundamental Symmetries & Cosmic History
Most of its predictions have
been confirmed
New particles should be
found
• W, Z0 bosons
• 3rd fermion generation
(CP-violation)
• Higgs boson (LHC ?)
How is electroweak
Standard
Model puzzles
symmetry broken?
Standard Model successes
Fundamental Symmetries & Cosmic History
It gives a microscopic basis for
understanding astrophysical
observations
• Big Bang Nucleosynthesis
(BBN) & light element
abundances
• Weak interactions in stars
& solar burning
•Standard
Supernovae
& neutron
Model
puzzles
stars
Standard Model successes
Fundamental Symmetries & Cosmic History
1. Unification & gravity
2. Weak scale stability
3. Origin of matter
4. Neutrino mass
Standard Model puzzles
Standard Model successes
We need a new Standard Model
Two frontiers in the search
Collider experiments
(pp, e+e-, etc) at higher
energies (E >> MZ)
Large Hadron Collider
Ultra cold neutrons
CERN
High energy
physics
Indirect searches at
lower energies (E < MZ)
but high precision
LANSCE, SNS, NIST
Particle, nuclear
& atomic physics
Outline
I.
SM Radiative Corrections & Precision
Measurements
II.
Defects in the Standard Model
III. An Alternative: Supersymmetry
IV. Low-energy Probes of Supersymmetry
New
I. Radiative Corrections & Precision
Measurements in the SM
Weak Decays: Fermi Theory
ee
n pee
e
p
e
H
EFF
e
n
GF
1
GF
F
e
G
GF
L eL e
HEFF p (gV gA 5 )n eL e
2
2
gV 1, gA 1.26
(1 5 )
Fermi Theory: QED Corrections
e
e
e
e
QED radiative
corrections: finite
G m 25
2
1
3
192 2 4
1
2
F
5
Fermi Theory’s Stumbling Block:
Higher Order (Virtual) Weak Effects
e
e
e
e
e
e
e
e
Weak radiative corrections:
infinite
Can’t be absorbed through suitable
re-definition of GF in HEFF
e
The Standard Model (renormalizable):
Control of Virtual Weak Corrections
g
W
e
e
g
g
e
W e
Z0
e
Re-define g
e
0
Z
e
e
W
Finite
e
GF encodes the effects of all higher order
weak radiative corrections
g
W
e
g
e
2 5
G
1
F m
3
192
Z0
e
W
e
e
e
W
W
2
GF
g
1 r
2
2 8MW
rdepends on parameters
of particles inside loops
e
Comparing radiative corrections in different
processes can probe particle spectrum
Z
e
0
g
g
e
Z0
e
Z0
e
e
Z0
e
GFZ g2
2 1 rZ
2 8MW
rdiffers from rZ
Z0
e
Comparing radiative corrections in different
processes can probe particle spectrum
GFZ
1 rZ r
GF
Z
t
0
Z
0
W
b
W
t
t
m
rZ ~ ln
M
2
t
2
W
mt2
r ~
2
MW
Comparing radiative corrections in different
processes can probe particle spectrum
Direct
Measurements
Radiative
corrections
Probing Fundamental
• Precision
measurements
Symmetries
beyond
predicted
a range
for mt
the SM:
before
top quark discovery
low• mUse
mb !
t >> precision
energy measurements
• mt is consistent with that
to probe virtual effects
range
of new symmetries &
• Itcompare
didn’t have
tocollider
be that
with
way
results
Stunning SM Success
J. Ellison, UCI
Global Analysis
c2 per dof
= 25.5 / 15
Agreement
with SM at
level of loop
effects ~ 0.1%
M. Grunenwald
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
Couplings depend on scale
Energy Scale ~ T
e e()
g g()
The early SM Universe had no unification
Early universe
Present universe
Standard Model
4
2
gi
High energy desert
Weak scale
log10 ( / 0 )
Planck scale
The early SM Universe had no unification
Early universe
Present universe
Standard Model
4 for
A “near miss”
2
grand unification
g
Gravity
i
Is there unification?
What new forces are
responsible ?
Weak scale
High energy desert
log10 ( / 0 )
Planck scale
The Fermi constant is too large
Early universe
Present universe
Standard Model
4
Weak scale
2
gi
unstable:
Why is GF
so large?
Weak scale
Unification
Neutrino
mass Origin of
matter
High energy desert
log10 ( / 0 )
Planck scale
The Fermi constant is too large
2
GF
g
2
2 8MW
g
M
4
2
2
W
2
WEAK
WEAK ~ 250 GeV GF ~ 10-5/MP2
NEW
H0
H0
2
WEAK
~ M
2
A smaller GF ,a different cosmos
The Sun would burn less brightly
p p d e e
G ~ GF2
Elemental abundances would change
p e n e
mn m p
n
exp
p
kT
Tfreeze out ~ GF-2/3
2n p
Y( He)
1 n p
4
Smaller GF
More 4He, C,
O…
There is too little matter - visible &
invisible - in the SM Universe
Visible Matter from Big Bang Nucleosynthesis & CMB
10
nB nB ~10 n
18
nB nB ~10 n
Measured abundances
& WMAP
SM baryogenesis
Insufficient CP violation in SM
There is too little matter - visible &
invisible - in the SM Universe
Invisible Matter
M M c
No SM candidate
Dark
Visible
Insufficient SM
CP violation
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
Supersymmetry, GUT’s, extra dimensions…
III. Supersymmetry
• Unify all forces
3 of 4
• Protect GF from shrinking
Yes
• Produce all the matter that exists
Maybe so
• Account for neutrino properties
Maybe
• Give self-consistent quantum gravity
Probably
necessary
SUSY: a candidate symmetry of the
early Universe
Supersymmetry
Fermions
Bosons
e L,R , q L,R
e˜ L,R , q˜ L,R
gauginos
˜ , Z˜ ,
˜, g
˜
W
W , Z , , g
Higgsinos
˜ ,H
˜
H
u
d
sfermions
Hu , H d
H
0
˜ , Z˜ ,
˜ c
˜, H
˜
˜
W
,
c
u, d
Charginos,
neutralinos
SUSY and R Parity
If nature conserves
PR
PR 1
3(BL)
1
2S
vertices have even
number of superpartners
Consequences
0
˜
Lightest SUSY particle c
is stable
viable dark matter candidate
Proton is stable
Superpartners appear only in loops
Couplings unify with SUSY
Early universe
Present universe
Standard Model
4
2
gi
Supersymmetry
High energy desert
Weak scale
log10 ( / 0 )
Planck scale
SUSY protects GF from shrinking
NEW
H0
˜ NEW
H0
H0
H0
2
WEAK
~ M M log terms
2
2
˜
=0 if SUSY is exact
SUSY may help explain observed
abundance of matter
Cold Dark Matter Candidate
c0
Lightest SUSY particle
Baryonic matter: electroweak phase transition
Unbroken
phase
Broken phase
CP Violation
t˜
H
SUSY must be a broken symmetry
Superpartners have
not been seen
M e˜ me
M q˜ mq
M c˜ MW ,Z ,
Can we test models of
SUSY breaking mediation ?
Theoretical models
of SUSY breaking
SUSY Breaking
Visible
World
Hidden
World
Flavor-blind mediation
IV. Low Energy Probes of SUSY
• J Erler (UNAM)
• V Cirigliano (Caltech)
• How is SUSY broken? M SUSY M SM
• C Lee (INT)
• How viable is SUSY dark matter ?
• S• Su
(Arizona)
Is there
enough SUSY CP violation to
• Saccount
Tulin (Caltech)
for the matter-antimatter
• Sasymmetry?
Profumo (Caltech)
• A Kurylov
Precision, low energy measurements can
probe for new symmetries in the desert
Precision ~ Mass Scale
SUSY
O
M
SM ˜
O
M
SUSY
2
M=m ~ 2 x 10-9
M=MW
exp ~
1 x 10-9
~ 10-3
Interpretability
• Precise, reliable SM predictions
• Comparison of a variety of observables
• Special cases: SM-forbidden or suppressed processes
Weak decays
Vud
u c t Vcd
Vtd
d u e e
s u e e
b u e e
2
2
Vud Vus Vub
2
=
Vus Vub d
Vcs Vcb s
Vts Vtb b
1
SM
0.9968 0.0014
Expt
0.94870.0010 0.04820.0008 0.000010.000007
Weak decays
Vud
u c t Vcd
Vtd
d u e e
s u e e
b u e e
-decay
n p e e
A(Z,N) A(Z 1,N 1) e e
0 e e
Vus Vub d
Vcs Vcb s
Vts Vtb b
GF
Vud 1 r r
GF
SUSY Loops
Weak decays
Vud
u c t Vcd
Vtd
d u e e
s u e e
b u e e
kaon decay
0
K e e
Value of Vus important
Vus Vub d
Vcs Vcb s
Vts Vtb b
GFK
Vus 1 rK r
GF
SUSY Loops: Too small
Weak decays & SUSY
Vud
u c t Vcd
Vtd
d u e e
s u e e
b u e e
˜
c
0
n p e e
˜
SUSY
e
A(Z,N) A(Z 1,N
1) e e
˜
0 ˜
e e
˜0
c
GF
Vud 1 r r
GF
e
O
~ 0.001
OSM
W
-decay
˜
e
Vus Vub d
Vcs Vcb s
Vts Vtb b
e
˜
c
e
SUSY
SUSY loops
r
SUSY Radiative Corrections
W
Propagator
Vertex &
External
leg
˜
W
˜0
c
W
˜
˜
˜
e
˜
c
e
e
e˜
W
˜
e
˜
c
˜
e
e
e
0
W
˜
c
e
˜0
c
Box
˜
c
˜0
c
W
e
e
e
e
Weak decays & SUSY
R Parity Violation
R-M,
V Flavor-blind
dSu
VKurylov,
VSUSY-
d u e e
ud
us
breaking
u c t Vcd
Vtd
M
s u e e
b u e e
e
O
˜
~ 0.001
SM
c12k ˜
12k
n p e e e O
e
-decay
e˜
˜
0
e
W
k
W
R
SUSY
d
e
A(Z,N)
A(Z
1,N
1)
e
e
˜
q
˜
0 ˜
1j1
e e 1j1
˜0
c
e
e
˜
c
Vcs Vcb s
CKM
Unitarity
Vts Vtb b
CKM, (g-2),
MW, Mt ,…
F
F
APV
l2
G
Vud 1 r r
G
e
j
L
ub
e d
M˜ L Mq˜ L
Kurylov,
No
long-lived LSPSUSY
or SUSY
loops
DMR-M
SUSY
RPV
UCNA
CKM Summary: PDG04
CKM Summary: New Vus & n ?
New n !!
Vus & Vud
theory ?
UCNA
New 0+
info
Probing SUSY with Lepton Scattering
Parity-Violating electron scattering
e
e
Z
0
e , p
e
e , p
e , p
e
e , p
2
GF Q
2
A
QW F(Q , )
4 2
LR
“Weak Charge” ~ 1 - 4 sin2 W ~ 0.1
Probing SUSY with Lepton Scattering
Neutrino-nucleus deep inelastic scattering
X
N
Z
0
Cross section ratios
W
X
N
W 2
R 1 2sin
2
Neutral currents mix
JZ =
JEM
J0 + 4 Q sin2W
g()
sin W
2
2
g() g()Y
2
Y
2
SU(2)L
U(1)Y
Weak mixing depends on scale
Weak Mixing Angle: Scale Dependence
Czarnecki, Marciano
Erler, Kurylov, MR-M
Atomic PV
N deep inelastic
sin2W
e+e- LEP, SLD
SLAC E158 (ee)
JLab Q-Weak (ep)
(GeV)
SUSY Radiative Corrections
e
Z
Propagator
e
e
Vertex &
Externalleg
0
˜
c
e˜
˜
c
Z
e
e
˜
c
e
f
f˜
f
˜
e
˜
c
˜e
˜e
e
f
f
e
˜
c
0
e
f
0
e˜
Z
˜0
c
Box
e˜
e
f
˜
c
f
f
Z0
f
f
Comparing
Qwe
and
˜q˜
c
QWp
Z
105 parameters:
What
about
RPV ?
random
scan
0
˜q˜
c
SUSY
SUSY
loopsloops
QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.
3000 randomly chosen
SUSY parameters but
effects are correlated
Effects in sin2W dominate
Kurylov, Su, MR-M
Negligible SUSY
loop impact on
cesium weak
charge
Comparing Qwe and QWp
SUSY loops
SUSY
dark matter
c ->
QuickTime™ and a TIFF (Uncompressed)
e+e decompressor are needed to see this picture.
is Majorana
RPV 95% CL fit to
weak decays, MW, etc.
Kurylov, Su, MR-M
Comparing Qwe and QWp
Can be a diagnostic tool to determine
whether or not
• the early Universe was supersymmetric
• there is supersymmetric dark matter
The weak charges can serve a similar
diagnostic purpose for other models for
high energy symmetries, such as leftright symmetry, grand unified theories
with extra U(1) groups, etc.
Additional PV electron scattering ideas
Czarnecki, Marciano
Erler et al.
Atomic PV
Linear
Collider e-e-
N deep inelastic
DIS-Parity, JLab
sin2W
e+e- LEP, SLD
SLAC E158 (ee)
JLab Q-Weak (ep)
Moller, JLab
(GeV)
What is the origin of baryonic matter ?
Cosmic Energy Budget
E
d dS
Dark Matter
Baryons
EDM
Dark Energy
dS E
h
T-odd , CP-odd
by CPT theorem
Searches for permanent electric dipole
moments (EDMs) of the neutron, electron,
and neutral atoms probe SUSY CP-violation
EDM Probes of SUSY CP Violation
CKM
f
e
n
199
Hg
dSM
dexp
dfuture
1040
1030
1.6 1027
6.3 1026
1031
1029
1033
1028
2.11028
1.11018
1032
1024
Also 225Ra, 129Xe, d
If new EWK CP violation is responsible for abundance
of matter, will these experiments see an EDM?
Present n-EDM limit
Proposed n-EDM limit
?
Matter-Antimatter
Asymmetry in
the Universe
Better theory
M. Pendlebury
B. Filippone
Riotto; Carena et al.;
Lee, Cirigliano, R-M, Tulin
“n-EDM has killed more theories than any other single experiment”
EDMs & Baryogenesis
Present universe
Early universe
Sakharov Criteria
• B violation
• C & CP violation
Y1
• Nonequilibrium
dynamics
Sakharov, 1967
1
L
Weak scale (SUSY)
baryogenesis can be
tested experimentally
1
S
?
?
log10 ( / 0 )
Weak scale
Planck scale
SUSY Baryogenesis
90’s:
Weak Scale Baryogenesis
• B violation
Cohen, Kaplan, Nelson
Joyce, Prokopec, Turok
Unbroken phase
Topological transitions
new
• C & CP violation
• Nonequilibrium
dynamics
(x)
Broken phase
1st order phase
transition
CP Violation
Sakharov, 1967
e˜
• Is it viable?
• Can experiment constrain it?
• How reliably can we compute it?
c0
e˜
e
EDM constraints & SUSY CPV
Lee et al
Near degeneracies
resonances
BBN
WMAP
(x)
new
de
A
de
199Hg
A
199Hg
BAU
BAU
new
new
Different choices for SUSY parameters
new
e
EDM constraints & SUSY CPV
Future: EDMs & LHC
Dark Matter Constraints
A
de
BBN
WMAP
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
dn
Cirigliano,
Profumo, MR-M
in preparation
BAU-DM
LargeHadron
HadronCollider
Collider
Large
Lee et al
Conclusions
• The Standard Model is triumph of 20th century physics,
but we know it is far from a complete theory
Lack of unification, size of the Fermi constant,
abundance of matter, neutrino mass, gravity,…
• Supersymmetry is a leading candidate theory that might
address many of these SM shortcomings
Future high-energy collider experiments may discover it
• Precision measurements in particle, nuclear, and atomic
physics at energies below MZ can provide important
indirect information about what form of SUSY - if
any - is viable
Weak decays, lepton scattering, electric dipole moments
Conclusions
• The interface between high-energy collider physics and
precision low-energy physics involves a rich and
stimulating “synergy” between many sub-fields
of physics
Sub-Z0 : A working group on precision electroweak
physics below the Z-pole
http://krl.caltech.edu/~subZ