Transcript Document 7479901

Probing the Connection
Between
Supersymmetry
and Dark Matter
Bhaskar Dutta
University of Regina, Canada
Physics Colloquium, TAMU, January 27, 2005
TALK OUTLINE
My Research Pie
B Decays
B. Dutta, C.S. Kim, and S. Oh, PRL 90, 011801 (2003) …
Anomalies in B0  f KS and B+  h' K+ Decays
CP
K.S. Babu, B. Dutta, and R.N. Mohapatra, PRD 65, 016005
(2001) … Strong CP and the SUSY Phase Problems
K.S. Babu, B. Dutta, and R.N. Mohapatra, PRL 85, 5064 (2000)
… Electric Dipole Moment of the Muon with Large
Neutrino Mixing
Neutrinos
B. Dutta, Y. Mimura, and R.N. Mohapatra, PRD 69, 115014
(2004) … CP Violation in SO(10) Model for Neutrinos
String Models and Phenomenology
R. Arnowitt, J. Dent, and B. Dutta, PRD 70, 126001 (2004) …
Five Dimensional Cosmology in Horava-Witten M-Theory
TALK OUTLINE
My Research Pie
Dark Matter
R. Arnowitt, B. Dutta, and Y. Santoso, NP B606, 59 (2001) …
Coannihilation Effects in Supergravity and D-Brane Models
Collider Physics
B. Dutta, R.N. Mohapatra and D.J. Muller, PRD 60,
(1999) 095005 … Doubly Charged Higgsino of SUSY
Left-Right Models at the Tevatron
R. Arnowitt, B. Dutta, T. Kamon, and M. Tanaka, PLB 538, 121
(2002) … Detection of Bsm+m- at the Tevatron Run II and
Constraints of the SUSY Parameter Space
TALK OUTLINE
Today’s Talk
Recent works on “Collider Physics”
and “Dark Matter Physics.”
Introduction to Standard Model (SM)
Reasons for going beyond the SM
Supersymmetric (SUSY) SM
Existing experimental constraints
Prospects of discovering SUSY in the
future dark matter experiments
Prospects of discovering SUSY in the
future Linear Collider (LC) and Large
Hadron Collider (LHC)
Conclusion
http://www.damtp.cam.ac.uk/user/gr/public/bb_history.html
t
t = 14 billion years
500 M yrs
Galaxy Formation
Relic Radiation
Decouples: WMAP
1s
10-7 s
SUSY Relic
10-11 s
10-43 s
Quantum Gravity
Road Map to Unified Theory
E
String Theory
SUSY
GUT
x
Standard Model (SM)
Glashow ’62, Weinberg ’67, Salam ’68
Underlying theory: a gauge theory (e.g., QED)
Quantum Mechanics + Special Relativity
6 quarks, 6 leptons and gauge particles
How can we see them?
One way to see quarks and leptons
“Quarks. Neutrons. Mesons. All those particles
You can’t see. That’s what drove me to drink.
But now I can see them!”
Real way to see Top (or Heavy Particles)
Standard Model
SU(3)  SU(2)  U(1)
  
s
2
1
Predictions were tested in experiments.
1973
B.S. - Neutral current
@ CERN SPS (400 GeV p)
1983
M.S. – “W/Z discovery”
_
@ CERN SppS (540 GeV pp )
1995
Ph.D. – “Top discovery”
@ Fermilab Tevatron (1.8 TeV pp )
Remarkable accuracy:
MZ
exp
 91.1876  0.0021 GeV
MZ
theory
 91.1874  0.0021 GeV
Explains most of the data!
Too Heavy t and Non-Zero 
QUARK MASSES
M top  178  10 9 eV
M up ~ 5  10 6 eV
h Yet to be
discovered
NEUTRINO MASSES
M  1 eV
Neutrino masses are non zero! The SM can not
accommodate nonzero neutrino mass!!! See recent
results from SuperKamiokande, SNO, KamLAND,
K2K, MACRO (Webb et al.). For future results,
see MINOS (Webb et al.), MiniBoone, T2K, …
Beyond the SM
The SM works very well at ~100 GeV.
(Strength of Force)-1
Three gauge couplings
do not meet at a single
point.
But we want to build a theory which
goes to a higher scale.
Grand Unified Theory
Structural Defect in the SM
Problem
a. The Higgs mass becomes too large at
scale of a few TeV (1000 x Mproton).
b. There should be some new theory at this
energy scale and this theory would keep
the Higgs mass under control.
The contribution to the Higgs mass
Boson
loop
Fermion
loop
 B 
2
  
2
2
F
 = Scale of new physics
Structural Defect in the SM
Possible Solutions (= New Physics)
a. Technicolor: Higgs is not a fundamental
particle. Experimental data do not allow
this theory any more. It only exists in a
movie entertainment world.
b. Extra dimension (ED) at (~)TeV scale.
EDs appear at around TeV scale. These
theories are not well developed to have
clear predictions.
c. Supersymmetric SM
Supersymmetric SM
The fundamental law(s) of nature is
hypothesized to be symmetric between
bosons and fermions.
Fermion (S = ½ )  Boson (S = 0 or 1)
Have they been observed?
➩ Not yet.
☹
Feynman Diagrams for SUSY
Supersymmetric partner of W boson
Supersymmetric partner of Z boson
Lightest neutralinos are always in the final
state! This neutralino is the dark matter
candidate!!
What do we gain if the theory is
supersymmetric?
Supersymmetric Unification
Grand Unified Picture!
MSUSY~TeV
Higgs mass does not become large at
any scale.
The top quark mass is predicted to be
150 to 200 GeV. D0 and CDF
measured:
Mtop = 178  4 GeV
Supersymmetry: Elegant Solution
Many new particles (100 GeV – a few TeV) and
many new parameters.
Whatever happened to elegant solutions?
Minimal Supergravity Model
SUSY model with two Higgs fields in
the framework of unification:
1) All SUSY masses are unified at the
grand unified scale.
m1/2 for gaugino masses
m 0 for squarks and sleptons
2) Two more parameters:
A0
tanb <H1> , <H2>  <H> , tanb
Astrophysics
Probing the Crucial Connection
CDM = The matter which is present
without any electromagnetic interaction.
SUSY
~0)
CDM = Neutralino ( 
1
To explain the amount of the CDM,
there must be another SUSY particle
whose mass must be closer to the
neutralino.
Is it possible to observe these features
in other experiments?
Dark matter detection?
Collider experiments?
Existing Bounds from Experiments
[1] Higgs Mass (Mh):
114 GeV < Mh < 130 GeV
(The Higgs mass depends on the mass
parameters m0 and m1/2, and A0 and tanb.)
[2] Branching Ratio b  sg :
CLEO: (3.21  0.47) x 10-4
SM : (3.62  0.33) x 10-4



Br 



• Excluding parameter space
the SUSY particle masses.



1
 2
 m SUSY


based on
Excluded
Mass of Squarks and Sleptons
Excluded Region in SUSY World
Mass of Gauginos
Existing Bounds from Experiments
[3] Magnetic Moment of Muon:
Excluded
Mass of Squarks and Sleptons
Excluded Region in SUSY World
Mass of Gauginos
Existing Bounds from Experiments
[4] Dark Matter:
Allowed region
The relic density is expressed as W where
WCDM = 0.23  0.04.
~0

Neutralino ( 1 ) constitutes the dark matter
in this model. It is the lightest and stable
particle in our model.
In order to calculate WCDM, we need to know
the density of the remaining neutralinos
when they stopped annihilating each other,
“neutralino annihilation,” i.e.
-2







W 






2
WCDM  m SUSY
WCDM can be expressed in terms of our
mSUGRA parameters.
Co-annihilation [Griest and Seckel ’92]: An
accidental near degeneracy occurs naturally
for light stau ~1 in mSUGRA.
 ~




 ~1

0
1
2


 - M
 e 20



Here M  M ~ - M ~ 0 . This diagram also
1
1
contributes to the relic density along with the
other neutralino annihilation diagrams. This
is a generic feature of any SUSY model.
Other regions (focus point, annihilation
funnel): mostly beyond the LHC – But, can
be observed at a possible energy upgrade of
the LHC - Tripler.
P. McIntyre, Proceedings of DARK2004
Excluded Region in SUSY World
Excluded
Mass of Squarks and Sleptons
Allowed region
Mass of Gauginos
Small tanb Region
Mass of Squarks and Sleptons
narrow co-annihilation corridor
Mass of Gauginos
Large tanb Region
narrow co-annihilation corridor
R. Arnowitt, B.D., T. Kamon, M. Tanaka, Phys. Lett. B538, 121 (2002)
R. Arnowitt, B.D., B. Hu, hep-ph/0310103 (talk at BEYOND '03)
A. Lahanas, D.V. Nanopoulos, Phys. Lett. B568, 55 (2003)
J. Ellis et al., Phys. Lett. B565,176 (2003)
H. Baer et al., JHEP 0207, 050 (2002)
Dark Matter Experiments
The neutralinos can be detected in the
dark matter detectors by scattering:
~10
~10
nucleus
recoil
This recoil can be detected in various
ways such as ionization and
scintillation.
The existence of SUSY in the nature
can be proved in these experiments.
R. Arnowitt, B.D. Y. Santoso, B.Hu, Phys. Lett. B505, 177 (2001)
J. Ellis, D. Nanopoulos, K. Olive, Phys. Lett. B508, 65, (2001)
H. Baer et al., JCAP 0309, 007 (2003)
Various ongoing experiments such as
a. DAMA group (Italy) – claiming to
have observed some events.
b.CDMS (USA) group – disputing
their claim.
Ongoing/future projects: ZEPLIN,
GENIUS, Cryoarray, CUORE etc.
Edelweiss
DAMA
10-6 pb
CDMS
J. White et al., Proceedings of DARK2004
Neutralino-Proton Cross Section
1-2 order of magnitude below the current
experimental sensitivity
Collider Experiments
Questions:
a. What are the signals from the
narrow co-annihilation corridor?
Small M

 ~0
~
  1
Collider Experiments
Questions:
a. What are the signals from the
narrow co-annihilation corridor?
~     ~10
b.What is the accuracy of the
measurement on M?
M  M~1 - M ~0  5 ~ 15 GeV
1
Collider Experiments:
1. Tevatron (2 TeV pp)
2. LHC (14 TeV pp)
3. LC (500 or 800 GeV e+e–)
The reach of the Tevatron is not high
enough.
V. Krutelyov, R. Arnowitt, B.D., T. Kamon, P. McIntyre, Y. Santoso, Phys. Lett.
B505, 161 (2001); R. Arnowitt, B.D., T. Kamon, M. Tanaka, Phys. Lett. B538, 121
(2002)
We will first discuss the LC since it
measures the mass very accurately.
Study of SUSY Signals at LC
 ( ~10 ~20 ) [500 GeV]
 ( ~10 ~20 ) [800 GeV]
Kinematical
limits
 (~1~1- ) [800 GeV]
 (~1~1- ) [500 GeV]
Develop event selection cuts and
extract signal from the background
Discovery
significance
of
the
parameter space
M = Accuracy of measuring the most
crucial parameter
SUSY Signals at LC
Stau-pair production
  - ~10 ~10
M  M~ - M ~  5 ~ 15 GeV
1
0
1
~ 0 ~ 0
Neutralino-pair production   - 
1 1
E( ) is small
because M is small.
SM Backgrounds at LC
4-fermion WW, ZZ, Z production
e.g., e  e -  W W -     -
RH beams
e–
e+
Suppressed by RH polarized electron beams
N4f(500 fb–1)  10k @ 90% RH
Two-photon (gg) process
e  e -  gg e  e -    - e  e Lower energy ’s
N2g(500 fb–1)  13M events!
We need to detect e– and e+ going very close
to the beam direction (down to 2o or 1o).
Number of Events vs. M
Number of SUSY events for 500 fb-1 of
luminosity as a function of M for m0
= 203~220 GeV with all the event
selection cuts
N2g = 249 for 2o
N2g =
4 for 1o
We can discover SUSY at LC with 1o!
R. Arnowitt, B.D., T. Kamon, V. Khotilovich, hep-ph/0411102
Accuracy of Mass Determination
m1/2=360
M (m0)
N~1~1
M (“500 fb–1 experiment”)
[GeV]
(500 fb–1)
2o Detector
1o Detector
4.76 (205)
122
Not determined
4.7 -11..00 GeV
9.53 (210)
787
9.5 -11..10 GeV
9.5 -11..00 GeV
12.37 (213)
1027
12.5 -11..44 GeV
12.5 -11..14 GeV
14.27 (215)
1138
14.5 -11..14 GeV
14.5 -11..14 GeV
NEED: 1o coverage at 500-GeV LC
d(M)/M ~ 10%
R. Arnowitt, B.D., T. Kamon, V. Khotilovich, hep-ph/0411102
Study of SUSY Signals at the LHC
The LHC is powerful enough to
produce many SUSY particles.
Can we detect the co-annihilation
signal (small M)?
~     ~10
Measurement of M at the LHC
Squark-gluino
production
section is very large.
cross
~ 0     ~        ~ 0
Key decay:
2
1
Signal: >3 (two high and one low
energy) + jets (q’s, g’s) + missing
energy ( ~10)
Backgrounds: SM tt and other SUSY
processes
A. Arusano, R. Arnowitt, B.D., T. Kamon, D. Toback, P. Wagner
SUSY Signals at the Tevatron
Direct searches
The reach is 200 GeV for m1/2
V. Krutelyov, R. Arnowitt, B.D., T. Kamon, P. McIntyre, Y. Santoso, Phys. Lett.
B505, 161 (2001)
Promising search: Bs  m+ m SM branching ration: 10-9
SUSY: 10-7~10-8
R. Arnowitt, B.D., T. Kamon, M. Tanaka, Phys. Lett. B538, 121 (2002)
V. Krutelyov, Ph.D. thesis, May 2005 (expected)
Conclusion
SUSY cures the problems of the SM.
It fulfills the dream of Grand
Unification and explains the dark
matter (DM) content.
The minimal supergravity (mSUGRA)
model, based on the unification
framework, is already constrained by
many experiments.
The DM content of the universe
requires some specific features of the
mSUGRA parameter space e.g. coannihilation.
The signal of the co-annihilation at the
colliders will confirm the model.
 A linear collider will be able to probe this
signal and accurately measure the mass.
 We think that the LHC will also be able
to probe this signal.