J. Hewett, HEP2010

Signatures of Supersymmetry Without Prejudice

Berger, Conley, Cotta, Gainer, JLH, Le, Rizzo arXiv:0812.0980, 0903.4409, in progress

Supersymmetry at the LHC

SUSY discovery generally ‘easy’ at LHC

q~

Cut: ETmiss > 300

GeV

LHC Supersymmetry Discovery Reach

mSUGRA - Model where gravity mediates SUSY breaking – 5 free parameters at high energiesSquark and Gluino mass reach is2.5-3.0 TeV @ 300 fb-1

at 14 TeV

Reconstruction of Sparticle Masses at LHC

Main analysis tool: dilepton edge in 02 01l+ l-

Proportional to Sparticle mass differences

Introduces strong mass correlations

Squarks and Gluinos have complicated decay chains

ATLAS SUSY Analyses with a Large Model Set

• We are running our ~70k MSSM models through the ATLAS SUSY analysis suite, essentially designed for mSUGRA , to explore its sensitivity to this far broader class of SUSY models

• We first need to verify that we can approximately reproduce the ATLAS results for their benchmark mSUGRA models with our analysis techniques

• By necessity there are some differences between the two analyses….

• This is extremely CPU intensive!

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ATLAS has already made use of some of these models!

ATLAS

ISASUGRA generates spectrum & sparticle decays

NLO cross section using PROSPINO & CTEQ6M

Herwig for fragmentation & hadronization

GEANT4 for full detector sim

FEATURE

SuSpect generates spectra with SUSY-HIT# for decays

NLO cross section for ~85 processes using PROSPINO**& CTEQ6.6M

PYTHIA for fragmentation & hadronization

PGS4-ATLAS for fast detector sim

** version w/ negative K-factor errors corrected# version w/o negative QCD corrections & with 1st & 2nd generation fermion masses included as well as explicit small m chargino decays

The ATLAS SUSY analyses:

• 2,3,4-jet +MET

• 1l, ≥4-jet +MET

• SSDL

• OSDL

• Trileptons + (0,1)-j +MET

• +≥ 4j +MET • ≥4j w/ ≥ 2btags + MET

• Stable particle search

We do a good job at reproducing the mSUGRA benchmark points in this channel !

4-jet +MET - Benchmark Points

FeatureATLAS

Sample Feature Model Results

1l+4j+MET – Benchmark Points

ATLAS Feature

Single Lepton Analysis: Sample Feature Models

b-jet analysis – Benchmark Points

ATLAS Feature

b-jet analysisSample Feature Models

Some Results From the First 20k Models @ 14 TeV & 1fb-1

• ‘Remove’ some possibly difficult models which may require some specialized analyses (note PYSTOP issues)

• Determine how many models are visible or not in each analysis @ the 5 level allowing for a 20% systematic un-certainty in the ATLAS generated SM backgrounds

• The results are still HIGHLY PRELIMINARY!!!

Some Results From the First 20k Models

*

* ID & reconstruction in PGS is a bit too optimistic & needs to be reaccessed

Some Results From the First 20k Models

Sample Difficult Models

Some Dark Matter Candidates

• The observational constraints are no match for the creativity of theorists

• Masses and interaction strengths span many, many orders of magnitude, but not all candidates are equally motivated

• Weakly Interacting Massive Particle (WIMP)

HEPAP/AAAC DMSAG Subpanel (2007)

SUSY

The WIMP ‘Miracle’

(1)Assume a new (heavy) particle is initially in thermal equilibrium:

cc ↔ f f

(2) Universe cools:

cc f f

(3) cs “freeze out”:

cc f f

(1)

(2)

(3)→←/

→←//

Zeldovich et al. (1960s)

• The amount of dark matter left over is inversely proportional to the annihilation cross section:

WDM ~ <sAv>-1

Remarkable “coincidence”: DM ~ 0.1 for m ~ 100 GeV – 1 TeV!

particle physics independently predicts particles with about the

right density to be dark matter !

HEPAP LHC/ILC Subpanel (2006)

[band width from k = 0.5 – 2, S and P wave]

A ~ 2/ m2

photons, positrons , anti-protons…. ‘in the sky’ right now may be seen by FERMI & other experiments

N N (elastic) scattering may be detected on earth in deep underground experiments

If is really a WIMP it may be directly produced at the LHC !

Of course, does not come by itself in any new physics model& there is usually a significant accompanying edifice of other interesting particles & interactions with many other observational predictions

So this general picture can be tested in many ways….

Predictions for Relic Density

WMAP

Correlation Between Dark Matter Density & the LSP-nLSP Mass Splitting

Small mass differences can lead to rapid co-annihilations reducing the dark matter density….

Direct Detection Expectations

Spin Dependent

Spin Independent

Predictions span orders of magnitude…Far smaller than mSUGRA expectations

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Distinguishing Dark Matter Models

Flat Priors

Barger etal

What fraction of the space is covered as, e.g., CDMS/XENON improve their search reaches??

The parameter space ‘coverage’ improves rather slowly…

Cosmic Ray Positron/Electron Flux

• χ2 fit to 7 highest energy PAMELA data points

• Vary boost for best fit (take Boost ≤ 2000)Positron Spectrum Boost Factor

Preliminary!

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flat

Annihilation Cross Section Channels

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Fermi/LAT Photon Measurements

Constraints from Dwarf Galaxies

Do the Model Points Cluster in the 19-Dimensional Parameter Space?

• New data mining procedure based on Gaussian

potentials

• Full Model Set before constraints is random – no

clustering

M. Weinstein

Clustering of Models (12000 Points)

Dimensions 1,2,3 Dimensions 4,5,6

Gainer, JLH, Rizzo, Weinstein, in progress

Summary• Studied the pMSSM, without GUT & SUSY

breaking assumptions, subject to experimental constraints

• We have found a wide variety of model properties not found in mSUGRA/CMSSM– Colored sparticles can be very light– NLSP can be basically any sparticle– NLSP-LSP mass difference can be very small

• Wider variety of SUSY predictions for Dark Matter & Collider Signatures than previously thought

• Things to keep in mind for LHC analyses– MSSM mSUGRA: a more general analysis is

required– Stable charged particle searches are very

important– Many models can lead to soft particles + MET – Mono-jet search is important

This new decade promises to be exciting, full of discoveries with a revolution in humanity’s exploration of the fundamental nature of the Universe!

CDMS

<133 GeV

133-183

133-243

>243 GeV

Models with Large SI Direct Detection Cross Sections wrt CDMSII

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