flavour physics and dark matter introduction selected experimental results impact on dark matter...
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Flavour Physics and Dark Matter
Introduction
Selected Experimental Results
Impact on Dark Matter Searches
Conclusion
Matthew HerndonUniversity of Wisconsin
Dark Side of the Universe 2007, Minneapolis Minnesota
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Why Beyond Standard Model?Standard Model predictions validated to high precision, however
Connection between collider based physics and
astrophysics becomes more interesting each year
M. Herndon
Gravity not a part of the SM
What is the very high energy
behaviour?
At the beginning of the universe?
Dark Matter?
Astronomical observations of indicate that
there is more matter than we see
Where is the Antimatter?
Why is the observed universe mostly matter?
Standard Model fails to answer many fundamental questions
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Many of those questions come from Astrophysics and Cosmology
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Searches For New PhysicsHow do you search for new physics at a collider?
Direct searches for production of new particles
Particle-antipartical annihilation: top quark
Indirect searches for evidence of new particles
Within a complex process new particles can occur virtually
Rare Decays, CP Violating Decays and Processes such as Mixing
Present unique opportunity to find new physicsM. Herndon
Tevatron is at the energy frontier
Tevatron and b factories are at a data volume frontier
billions B and Charm events on tape
So much data that we can look for some very unusual processes
Where to look
Many weak processes involving B hadrons are very low probability
Look for contributions from other low probability processes – Non Standard Model
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B Physics Beyond the SMLook at processes that are suppressed in the SM
Excellent place to spot small contributions from non SM contributions
The Main Players:
Bs(d) →μμ-
SM: No tree level decay
b s
Penguin decay
New Players
Bs Oscillations
B
M. Herndon
Same particles/vertices occur in both B decay diagrams
and in dark matter scattering or annihilation diagrams
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˜ χ
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˜ χ
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˜ χ
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˜ χ
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The B Factories
EXCELLENT MUON DETECTIONEXCELLENT TRACKING:
TIME RESOLUTIONEXCELLENT PARTICLE ID
CDF
D0
BABAR
BELLE
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b → sLook at decays that are suppressed in the
Standard Model: b → s
Classic b channel for searching for new physics
Inclusive decay easier to calculate but still difficult
New physics can enter into the
loop(penquin)
Decay observed
Now a matter of precision
measurement and precision
calculation of the SM rate
New calculation by Misiak et. al.
NNLO calucation - 17 authors
and 3 years of effort
BR(b → s) = 3.15 0.23 x 10-4
M. Herndon One of the best indirect search channels at the b factrories
PRL 98 022002 2007
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b → sMeasure the inclusive branching ratio from
the photon spectrum
Backgrounds from continuum production
and other B decaysContinuum backgrounds suppressed using event shapes or reconstruction the other B
o and reconstructed and suppressed
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Bs(d) → μ+μ-
Look at decays that are suppressed in the
Standard Model: Bs(d) →μμ-
Flavor changing neutral currents(FCNC) to leptons
No tree level decay in SM
Loop level transitions: suppressed
CKM , GIM and helicity(ml/mb): suppressed
SM: BF(Bs(d) →μμ-) = 3.5x10-9(1.0x10-10)G. Buchalla, A. Buras, Nucl. Phys. B398,285
New physics possibilities
Loop: MSSM: mSugra, Higgs Doublet
3 orders of magnitude enhancement
Rate tan6β/(MA)4
Babu and Kolda, Phys. Rev. Lett. 84, 228
Tree: R-Parity violating SUSY
Small theoretical uncertainties. Easy to spot new physics
M. Herndon One of the best indirect search channels at the Tevatron
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Bs(d) → μ+μ- Method
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Relative normalization search
Measure the rate of Bs(d) → μ+μ- decays
relative to B J/K+
Apply same sample selection criteria
Systematic uncertainties will cancel out in
the ratios of the normalization
Example: muon trigger efficiency same for
J/ or Bs s for a given pT
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BF(Bs → μ +μ−) =(Ncand − Nbg )
α BsεBs
•α
B +εB +
NB +
•fu
f s
•
BR(B+ → J /ψK +) • BR(J /ψ → μ +μ−)
400pb-1
9.8 X 107 B+ events
N(B+)=2225
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Discriminating Variables
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Mass M
CDF: 2.5σwindow: σ = 25MeV/c2
DØ: 2σwindow: σ = 90MeV/c2
CDF λ=cτ/cτBs, DØ Lxy/Lxy
α : |φB – φvtx| in 3D
Isolation: pTB/( trk + pTB
)
CDF, λ, α and Iso:
used in likelihood ratio
D0 additionally uses B and
impact parameters and vertex
probability
Unbiased optimization
Based on simulated signal and data
sidebands
4 primary discriminating variables
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CDF 1 Bs result: 3.010-6
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Bs(d) → μ+μ- Search Results
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CDF Result: 1(2) Bs(d) candidates observed
consistent with background expectation
Worlds Best Limits!
Decay
Total Expected Background
Observed
CDF Bs
1.27 ± 0.36 1
CDF Bd
2.45 ± 0.39 2
D0 Bs
0.8 ± 0.2 1.5 ± 0.3
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BF(Bs +- ) < 10.0x10-8 at 95% CL
BF(Bd +- ) < 3.0x10-8 at 95% CL
D0 Result: First 2fb-1 analysis!
BF(Bs +- ) < 9.3x10-8 at 95% CL
PRD 57, 3811 1998
Combined:
BF(Bs +- ) < 5.8x10-8 at 95% CL
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Bs → μ+μ-Physics Reach
Strongly limits specific SUSY models: SUSY SO(10) models
Allows for massive neutrino
Incorporates dark matter results
BF(Bs +- ) < 5.8x10-8 at 95% CL
Excluded at 95% CL
(CDF result only)
BF(Bs +- ) = 1.0x10-7
Dark matter constraints
L. Roszkowski et al. JHEP 0509 2005 029
A close shave for the
theorists
Typical example of SUSY Constraints
However, large amount of recent work
specifically on dark matter DSU 2007
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B Physics and Dark MatterB Physics constraints impact dark matter in two ways
Dark matter annihilation rates
Interesting for indirect detection experiments
Annihilation of neutralinos
Dark matter scattering cross sections
Interesting for direct detection experiments
Nucleon neutralino scattering cross sections
Models are (n,c)MSSM models with constraints to simplify the parameter space:
Key parameters are tanβ and MA as in the flavour sector along with m1/2
Two typical programs of analysis are performed
Calculation of a specific property: Nucleon neutralino scattering cross sections
Constraints from Bs(d) →μμ- and b s as well as g-2, lower bounds on the Higgs mass, precision
electroweak data, and the measured dark matter density.
General scan of allowed SUSY parameter space from which ranges of allowed
values can be extracted
M. Herndon Results can then be compared to experimental sensitivitiesDSU 2007
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˜ χ
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˜ τ
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SUSY and Dark Matter
M. Herndon Informs you about what types of dark matter Interactions are interesting
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2m ˜ χ ≈ mA
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m ˜ χ ≈ m ˜ τ
H. Baer et. al.
What’s consistent with the constraints?
There are various areas of SUSY
parameter space that are allowed by
flavour, precision electroweak and WMAP
Stau co-annihilation
Funnel
Bulk Region
Low m0 and m1/2, good for LHC
Focus Point
Large m0 neutralino becomes higgsino like
Enhanced Higgs exchange scattering diagrams
Disfavoured by g-2, but g-2 data is controversial
TeV
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Flavour Constraints on mNew analysis uses all available flavour constraints
Bs →μμ-, b s,Bs Oscillations, B
Later two results only 1 year old
CMSSM - constrained so that
SUSY scalers and the Higgs
and the gauginos have a
common mass at the GUT scale:
m0 and m1/2 respectively
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J. Ellis, S. Heinemeyer, K. Olive, A.M Weber and G. Weiglein hep-ph/0706.0652
Focus Point
Stau co-annihilation
Definite preferred
neutralino masses
~
This region favoured because of g-2
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Bs → μ+μ- and Dark MatterBs →μμ- correlated to dark matter searches
CMSSM supergravity model
Bs →μμ- and neutralino scattering cross sections are both a strong
functions of tanβ
In high tanβ(tanβ ~ 50), positive μ, CDM allowed
Current bounds on Bs →μμ- exclude parts of
the parameter space for direct dark matter detection
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More general scan in m0, m1/2 and A0, allowed region
S. Baek, D.G. Cerdeno Y.G. Kim, P. Ko, C. Munoz, JHEP 0506 017, 2005
CDF Paper Seminar 2007
R. Austri, R. Trotta, L. Roszkowski, hep-ph/0705.2012
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B Physics and Dark MatterPutting everything together including most recent theory work on b s
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R. Austri, R. Trotta, L. Roszkowski, hep-ph/0705.2012
Current experiments starting to probe interesting regions
Analysis shows a preference for the Focus Point
region, g-2 deweighted
Higgsino component of Neutralino is enhanced.
Enhances dominant Higgs exchange scattering
diagrams
Interesting relative to light Higgs searches at
Tevatron and LHC
Probability in some regions has gone down
However…
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Current Xenon 10 ResultsLiquid Xenon detector
Multiple modules
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Xenon 10 Preliminary
R. Austri, R. Trotta, L. Roszkowski Current best limits
Excluding part of the high probability
region - 60 live day run!
Excluded by new Bs →μμ-
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Dark Matter ProspectsFrom dmtools.brown.edu
Just considering upgrades of
the two best current
experiments and LUX.
Prospects for dark matter
detection look good in CMSSM
models constrained by collider
data!
M. Herndon
Perhaps find both Dark
Matter and Bs → μ+μ-
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Excluded by new Bs →μμ-
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ConclusionsCollider experiments are providing a wealth of data on Flavour physics
as well as direct searches and precision electroweak data
These data can be used to constrain the masses and scattering cross
sections of dark matter candidates
Constrained MSSM models indicate that dark matter observation may
be within reach for current or next generation experiments! If Bs →μμ-
is there as well.
M. Herndon
A simulations observation of direct(or indirect) evidence
for new physics at a collider and Cold Dark Matter would
reveal much about the form of the new physics
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