Outline

2. Outline • Find a signal, have champagne • Signal of what? • Is it the dark matter? • Calculating the (relic) density • What we need from colliders, detectors, and theory • Calculating the wimp mass from dark matter data alone • A General method to place bounds on the relic density of the LSP given any available knowledge of the MSSM • Summary and outlook

3. A WIMP is Discovered • A wimp discovery has enormous implications for particle physics • May be the first observation of supersymmetry • Unprecedented triumph of astroparticle physics • Could possibly (hopefully) explain the dark matter mystery • What is its relevance to cosmology? • There is no reason to suspect that dark matter is entirely composed of a single particle

4. wimp only a small piece of the dark matter wimp only a small piece of the dark matter No-Lose Theorem vs. Our Ability to Win • 'No lose theorem': we may be able to directly detect a very small wimp component of the dark matter. • Therefore, we will not know the cosmological relevance of a wimp until we know its relic density [Dūda, Gelmini, Gondolo, Edsjö, Silk, etc.] wimp is the dark matter wimp is the dark matter ~reach of experiments tomorrow (?) ~reach of experiments tomorrow (?) (each point corresponds to a general MSSM consistent with all current data) emphasized by BCK in hep-th/0005158

5. Local and Relic Density • We will assume that it is sufficient to know the local density of a wimp to deduce its relic density: • The local density of 'dark matter', dm~0.3 GeV/cm3, is known independent of cosmological data: this is known by the velocities of stars near the sun • This agrees roughly with dmh2~0.1 and so • Therefore, if the wimp density is ~0.3 GeV/cm3, we will conclude that almost all of the dark matter is made of  • This introduces subtleties about the halo • If the halo is clumpy, then the ambient density—not in clumps—may be less than 0.3 GeV/cm3 • This can be determined from direct detection data alone • It will be easy to see if the wimp density fluctuates in time • If the sun is located in a dark matter stream (e.g. Sgr) or caustic • May only be corrected with DRIFT or other directional dark matter experiments • For this work, we will assume the halo is isothermal

6. halo model nuclear physics Deducing the Local Density • Detection rates are proportional to the local density of wimps: • Unknown parameters: unknown physics (the particle physics of )

7. Density Calculation Prerequisites • Particle identification: • Without any quantum numbers, it is not possible to distinguish between the LSP, lightest Kaluza-Klein particle, wimpzillas, etc. • The only way (so far) to identify the wimp is to determine its mass from direct detection alone and then observe this particle at colliders • The wimp mass: • Calculable from direct detection alone (at least two methods) • Annual modulation crossing energy (robust, if applicable) • Kinematical consistency constraints (work in progress) • Single detector if sensitive to spin-dependent interactions • Multiple detectors required if nuclei have no spin (or nuclear physics unknown) • Maybe calculable at colliders (at least for most reasonable wimps) • May not be easy: If the wimp is the LSP, for example, it is not clear that there exists any way to determine its mass (model independently) at the LHC better than ~20-30% • If you assume mSUGRA (which you aren't allowed to do), then the LSP mass could be determined to about 10% with 1 year of high-luminosity data

8. Density Calculation Prerequisites • Interaction parameters: • These cannot be determined from any dark matter experiment alone • Requires detailed knowledge of the wimp couplings to quarks and gluons • For example, if the wimp is the neutralino, then you must have • Spin-dependent: squark masses & mixing, tanb, and content of the neutralino • Spin-independent: squark masses & mixing, higgs masses, tanb, and content of the neutralino • May require years of collider data (if possible at all) • However, we can estimate these given partial data and (even current) parameter limits • Halo model • All analysis may be plagued by caustics or dark matter streams until experiments like DRIFT determine the isotropy of the local halo • Could introduce (large) errors in the relic density calculation and • Some halo models may preclude mass estimates (e.g. no annual modulation crossing)

9. Determining the Wimp Mass • Recall that the annual modulation amplitude changes sign at some particular energy Notice that there is always some point at which there is no annual modulation this is the 'crossing energy'

10. Determining the Wimp Mass • This crossing energy directly determines the wimp mass! ~2 keV resolution on crossing energy corresponds to ~10 GeV resolution on the wimp mass Notice the clear functional dependence

11. Determining the Wimp Mass • However, this fails for detectors composed of several different-mass elements

12. Consistency Function Mass Calculation • Notice that  f2p,n and a2p,n are constants. • For each independent set of data, we can compute these constants independently for given the mass. • Define a consistency function where i,j represent a minimal set of data used to compute the constants using the assumed value for m • Clearly, (m) should have a minimum at the true mass. (Independent determinations of the constants should agree)

13. Alternative Method for the Mass If we plot the 'kinematical consistency function' (m), we see *Note: this algorithm does not take into account uncertainties in the data

14. Using Multiple Experiments • If we know the wimp mass and halo profile, then given measurements • at different energies • from different detector materials, we can solve for

15. Wimp Interaction Parameters • We can generally solve for • an upper bound on any single parameter is equivalent to a lower bound for the density • a lower bound on any single parameter is equivalent to an upper bound for the density • Easier to estimate one of the parameters than all 4 • Multiple density estimates are relatively independent

16. LSP Interaction Bounds • For the most general MSSM, given bounds on tanb and a lower bound on the lightest squark mass, one obtains an upper bound for ap,n: (some subtleties exist about scaling quark to nucleon interactions, see our coming paper for details) where the expression is maximized relative to the 6 unknown, bounded parameters • It is clear how this type of approach can be iteratively improved given more specific data and bounds • Note: the expression above is greatly simplified for less general MSSMs (e.g. mSUGRA, GMSB, or AMSB)

17. LSP Relic Density Lower Bound Using the upper bound for ap,n, we get a lower bound on  a perfect density estimate The bound is robust: for no model does it overestimate the density Bound calculated for 6050 randomly generated (physically allowable) MSSMs

18. Summary and Outlook • One cannot compute the relic density of wimps from direct detection alone • Given collider data and bounds, one can (at least)estimate the local neutralino density • It is possible to learn about the wimp from direct detection alone (e.g. its mass, scaled couplings, etc.) • These are powerful tests for colliders and the MSSM • The only way to identify the wimp • Data from multiple detector materials greatly simplifies and strengthens our ability to compute the density

19. MSSMs with ~Same Signals and Different Models with the very similar direct and indirect detection signals but different relic densities (many are easy to find) Notice that the lighter squark mass gives a larger coupling—hence, a stronger signal. This also gives a hint about the importance of knowing the lightest squark mass: 180 GeV difference corresponds to a factor of 3 in the local density calculation