Relic density : dependence on MSSM parameters

1
Relic density dependence on MSSM parameters
B. Allanach, G. Belanger, F. Boudjema, A. Pukhov

• Introduction
• MSSM parameters in mSUGRA inspired models
• mSUGRA parameters and relic density
• Some remarks beyond mSUGRA

2
LC-Cosmology

• Cosmology (relic density of dark matter) strongly
  constrains SUSY models, in particular, in mSUGRA,
  points to specific scenarios for SUSY searches at
  colliders
• With WMAP
• .094 lt W h2 lt .128 (2 sigma)
• PLANCK expects precision of 2
• LHC will test SUSY Dark Matter hypothesis (can
  also have some LSP signal from direct detection
  experiments), with LC and precision measurements
  of SUSY parameters can one match the precision of
  the relic density measurement by PLANCK hence
  consistency check on cosmological model

3

• In mSUGRA one must appeal to very specific
  mechanisms to reach agreement with WMAP. The main
  reason
• The LSP is mostly bino
• A bino LSP annihilates into fermion pairs
  through
• t-channel exchange of right-handed slepton
• The coupling is U(1) strength ? annihilation
  cross section for neutralino pairs is not
  efficient enough ? too much relic density
• ?Need rather fine adjustment of parameters to
  meet WMAP
• Need very precise determination of
  parameters for an accurate prediction of relic
  density
• In mSUGRA the only possibilities
  coannihilation, Higgs resonance, or Higgsino LSP
  (in focus point)
• In more general MSSM
• Coannihilation can also occur (not necessarily
  with stau/stop)
• Higgs funnel regions are also found (even at low
  tanbeta)
• In addition to scenarios with Higgsino LSP, also
  possible to have wino LSP
• Examples AMSB, dilaton-dominated/moduli-dominated
  , non-universal SUGRA

4

• Consider mSUGRA inspired MSSM models
• In the WMAP favoured region of mSUGRA the relic
  density is very sensitive to
• ?M(NLSP-LSP)
• ?
• MA-2M ?
• How precisely do these parameters need to be
  measured at LHCLC colliders to have prediction
  for W h2 competitive with PLANCK
• ? Consistency check on cosmological model
• What is impact on W h2 of uncertainties in
  evaluation of sparticle spectra in mSUGRA, in
  particular
• Mt dependence in focus point region, Higgs
  annihilation
• Mb, tan ß dependence

5
mSUGRA
Mh111 Mt175
179

• Hardly any Bulk region
• Coannihilation with stau
• Higgs resonance
• Higgsino LSP focus point

114
.129
5
.094
6
NLSP-LSP mass difference in coannihilation region

• In mass range relevant for LC500,
• typical ?M(stau ?) 5-15 GeV, ?M(e?)12-20
  GeV
• Scenarios with smaller ?M allowed but require an
  additional component for darkmatter

7
NLSP-LSP mass difference and relic density
In the coannihilation region (Oh2 .1)
0.15-0.4GeV precision on ? M (stau-?) needed
for 2 prediction of Oh2
tanß10
Important to measure precisely mass of stau in
coannihilation region LC can make precise
measurements of sleptons with small ?M (Zhang et
al, LCWS)
tanß35
Allanach et al, LCWS
8
The focus point region
Sfermions are heavy difficult for
LHC Potential for LC in gaugino/Higgsino
sector LSP has Higgsino component ? ? is
important parameter for relic density
Coannihilation with charginos and/or heavier
neutralinos are important, mass difference
typically 50 GeV for relic density In WMAP range
In the focus point region (mt172GeV) (Oh2
.128)
0.2-0.3 precision on ? necessary for 2
prediction of O
9
Focus point region - observables

• In region where neutralino annihilate to WW-/ZZ
  typically 3 neutralinos chargino are accessible
  at LC500
• What precision can be reached on ??
• For SPS1a combined LHC-LC analysis level on ?
• Desch et al hep-ph/0312069
• Here light chargino/neutralino mass depend
  sensitively on ? expect good precision already
  from mass measurement

10
Heavy Higgs annihilation

• Heavy Higgs resonance (funnel)
• Heavy Higgs enhanced coupling to b quarks
• Large width
• Acceptable relic density if
• M(LSP)-MA/2 GA
• Most of Heavy Higgs annihilation region at large
  tanß is not accessible to LC500 (or LHC).
• Even at low M1/2, important contribution of
  diagram with heavy Higgs exchange (as well as
  slepton exchange) possible far from resonance
  even if M(LSP)lt200GeV
• Constraint from b-gts? important
• What are relevant parameters and how precisely
  should they be measured to get precise estimate
  of relic density (MA300-400GeV)

Mt175
11
MA dependence

• For given M0-M1/2 calculate MSSM spectrum and
  look at dependence on different MSSM parameters
  in particular MA,G(A), ?, tanß
• .2 (1GeV) precision on MA needed for 2
  prediction of Wh2
• This precision can be reached at LHC with
• H/A-gt ? ? (ATLAS-TDR 300fb-1 )
• Weaker dependence on ?, tanß (also induces shifts
  in LSP mass)
• 1 precision on ? needed, 5-10 on tanß
• The A width is not an important parameter (far
  enough from resonance)

12
Moving closer to Higgs resonance

• Closer to the Higgs resonance stronger
  dependence on MA
• MA700 GeV
• Need better than 0.1 measurement of mass
• LHC cannot use ? ? channel for mass
  determination
• Also need tanß level and A width (few percent)

13
Elucidating the symmetry breaking mechanismRGE
codes and relic density in mSUGRA

• In general RGE codes get rather good agreement
  for the sparticle spectra, but difficult regions
  are the ones interesting for relic density
• Focus point
• Higgsino/gaugino fraction determines coupling of
  ? to Z, fermions and determines main
  annihilation cross-section (? ? ?ff,
  WW)
• Large tanß (mass of Higgs)
• Coannihilation (need precise mass difference)
• Coannihilation channels are suppressed by factor

14
Large tan ß mSUGRA
Within mSUGRA very strong dependence on input
parameters top/bottom quark mass, tanß
With expected precision from LC ( ?mt .1GeV)
can predict O h2 with 2-3 precision within
mSUGRA But no hope of reaching sufficient
accuracy on mb(mb) or on tanß
2 accuracy on O would require determination of
tanß at per-mil level ? main problem shifts in
tanß induce shifts in MA / M(LSP)
Precise predictions of relic density within this
mSUGRA scenario not possible Much more reliable
predictions after determination of MSSM parameters
15
Focus point region and Mt

• Strong dependence on the top quark mass
• Increasing Mt pushes focus point towards heavier
  M0
• Dependence on the code used for evaluation of
  supersymmetric spectrum critical parameter is ?

Isajet7.69
Allanach et al., Les Houches
16
Relic density and MSSM parameters

• With expected precision from hadron Collider
  ?Mt1-2 GeV, prediction for O can vary by more
  than one order of magnitude
• With expected precision from LC ?mt0.1GeV still
  large corrections to Oh2 ( up to 100)
• Need to improve on theoretical predictions
• In terms of MSSM parameters rather than mSUGRA,
  prediction for Oh2 more stable (recall measuring
  ? few per-mil is needed to match PLANCK accuracy)

17
Some remarks
A0 -1700 GeV

• mSUGRA inspired models might seem too
  restrictive but even in other scenarios relic
  density from WMAP often imposes coannihilation
  /Higgs funnel/ Higgsino LSP Results presented are
  valid in more general MSSM models
• Other cases not considered yet
• stop NLSP, e.g. in mSUGRA with large A0
• ?M30-50GeV
• Mass difference should be critical parameter for
  relic density prediction
• In mSUGRA stop NLSP only consistent with b-gts?
  and Mh for large negative mixing
• Wino LSP
• scenario that cannot be realized in mSUGRA
• much easier to satisfy relic density constraint
  if LSP not bino,
• One example changing the gaugino mass relations
  at GUT scale

Main channels
18
Relaxing universality the wino LSP

• M1gtM2 at GUT scale increasing the wino content
  of the LSP makes for more efficient annihilation
  ? relic density constraint is easily satisfied
• Preferred channels
• WW
• M11.8M2 at GUT scale ?M1M2 at weak scale
• LSP is mixed wino/bino
• M(LSP)600GeV in WMAP range
• Relevant parameter at weak scale M1,M2,?
• Important to also consider this scenario

GB, Boudjema, Cottrant, Pukhov, Semenov
hep-ph/0407218
19
Summary

• Precision measurement of NLSP-LSP mass difference
  at LC essential to be competitive with PLANCK
  precision on relic density in coannihilation
  region
• In focus point region, need high precision
  determination of ? .
• At large tanß need precise determination of MA
  AND tanß .
• To go back to origin of supersymmetry breaking
  mechanism, high-precision determination of mt is
  needed in focus point region (also improvement in
  precision in RGE) and in heavy Higgs annihilation
  region. Also mb(mb) is needed.
• In progress sensitivity on various parameters in
  non-mSUGRA inspired models