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SUSY Dark Matter Collider – direct – indirect search bridge.
Sabine KramlLaboratoire de Physique Subatomique et de Cosmologie
Grenoble, France
●
43. Rencontres de Moriond
La Thuile, 1-8 March 2008
Moriond EW 2008 2S. Kraml: SUSY dark matter
WIMP paradigm DM should be stable, electrically neutral,
weakly and gravitationally interacting
WIMPs ― weakly interacting massive particles
WIMPs are predicted by most theories beyond the Standard Model (BSM)
Stable as result of discrete symmetries
Thermal relic of the Big Bang
Testable at colliders!
Neutralino, gravitino, axino, lightest KK state, T-odd little Higgs, etc., ...
BSM-DM
c.f. talk by M. Tytgat
Moriond EW 2008 3S. Kraml: SUSY dark matter
let‘s go SUSY ...
Moriond EW 2008 4S. Kraml: SUSY dark matter
What is SUSY? Supersymmetry (SUSY) is a symmetry between fermions and bosons.
The SUSY generator Q changes a fermion into a boson & vice versa
Extension of space-time to include anticommuting coordinates
x → (x, ) with
This combines the relativistic “external” symmetries (such as Lorentz invariance) with the “internal” symmetries such as weak isospin.
Actually the unique extension of the Poincare algebra *
* (the algebra of space-time translations, rotations and boosts)
Moriond EW 2008 5S. Kraml: SUSY dark matter
space-time symmetry
(special relativity)
Antiparticles
space-time
supersymmetry
Superpartners
doubling of
the spectrum
Moriond EW 2008 6S. Kraml: SUSY dark matter
The beauties of SUSY Unique extension of relativistic symmetries
Solution to gauge hierarchy problem
Radiative EW symmetry breaking, light Higgs
Gauge coupling unification
Ingredient of string theories
Very rich collider phenomenology
Cold dark matter candidate ....
Moriond EW 2008 7S. Kraml: SUSY dark matter
SUSY as a local gauge theory includes a spin-2 state,
the graviton (!) and its superpartner the gravitino.
Minimal Supersymmetric Standard Model(MSSM)
gluino
2 charginos ±
4 neutralinos
If SUSY comes with a new conserved parity, RP,
then the lightest SUSY particle (LSP) is stable
DARK MATTER CANDIDATE
Gravitino, sneutrino or
lightest neutralino
Moriond EW 2008 8S. Kraml: SUSY dark matter
I am concentrating on the neutralino case.
For gravitino DM, see talk by F. Steffen tomorrow morning
Moriond EW 2008 9S. Kraml: SUSY dark matter
SUSY searches at the LHC
CMS
Moriond EW 2008 10S. Kraml: SUSY dark matter
01
Z
q
q
02
q~g~
jet
jet
jets, l+l−
missing energy
Large cross sections ~100 events/day for M ~ 1 TeV
Spectacular signatures SUSY could be found early on
gggqqq ~~ ,~~ ,~~
Cascade decays into LSP
lead to typical signature:
multi-jets / multi-leptons
plus large missing energy
SUSY @ LHC
Every SUSY event → 2 LSPs.
Abundant production!
LHC as DM factory
Moriond EW 2008 11S. Kraml: SUSY dark matter
Mass measurements: cascade decaysET
miss → no peaks → mass reconstruction through kinematic endpoints
[ATLAS, G. Polesello]
Typical precisions: a few %
Moriond EW 2008 12S. Kraml: SUSY dark matter
Neutralino annihilation:
LSP as thermal relic: relic density computed as thermally avaraged
cross section of all annihilation channels → h2 ~ v −1
Moriond EW 2008 13S. Kraml: SUSY dark matter
Consequences
1. 0.094 < h2 < 0.136 puts strong constraints on the parameter space of any model variant
CMSSM: GUT-scale
boundary conditions:
m0, m1/2, A0,
plus tanb, sgn()
Moriond EW 2008 14S. Kraml: SUSY dark matter
Consequences
1. 0.094 < h2 < 0.136 puts strong constraints on the parameter space of any model variant
good h2
Simple SO(10) SUSY GUTs:
dual requirement of Yukawa
unification and DM relic density
is extremley predictive
→ Very distinct LHC signatures:
~500-600 GeV gluinos
50-75 GeV 1
talk by S. Sekmen in YSF2
Moriond EW 2008 15S. Kraml: SUSY dark matter
Consequences
1. 0.094 < h2 < 0.136 puts strong constraints on the parameter space of any model variant
2. If we can measure the properties of the SUSY particles precisely enough, then we can compute v of the LSP
→ „collider prediction“ of h2
→ compare with cosmological observations
Note: this means measuring (or at least putting limits on)
masses and couplings of most of the SUSY spectrum to infer
Moriond EW 2008 16S. Kraml: SUSY dark matter
Consequences
1. 0.094 < h2 < 0.136 puts strong constraints on the parameter space of any model variant
2. If we can measure the properties of the SUSY particles precisely enough, then we can compute v → h2
3. We can also compute the direct and indirect
detection rates
direct detection: m, Nv, local DM density
indir. det.: <v >v→0, density profile, propagation model
Moriond EW 2008 17S. Kraml: SUSY dark matter
However, uncertainties in N calculation are large (~50%)
Direct detection: limits and predictions
Xenon10new CDMS result!
Predictions of various SUSY models
Moriond EW 2008 18S. Kraml: SUSY dark matter
Indirect searches:high energetic positrons or gamma rays from annihilation
Moriond EW 2008 19S. Kraml: SUSY dark matter
Indirect detection: EGRET signal?
[W. DeBoer, arXiv:0711.1912]
50–70 GeV neutralino?EGRET
Moriond EW 2008 20S. Kraml: SUSY dark matter
Higgs?
SUSY?
1 GeV ~ 1.3 * 1013 K
„It is impossible to overestimate the importance of discovering dark matter at the LHC. Such a discovery will imply a revision of the SM, it will strenghten the connection between particle physics, cosmology and astrophysics, and it will enormously enlarge our understanding of the present and past universe.“
G.F. Giudice, Theories for the Fermi Scale (2007)