1. Precision Probes for Physics Beyond the Standard Model
What can we learn about particles too massive to produce?

2. Why do we think the Standard Model is imcomplete?
Most compelling reason is dark matter!
Also Dark energy – or more generally combining it with gravity
Theoretical prejudice on
“technical naturalness”
Otherwise known as “the hierarchy problem”

3. Precision Constraints on Model Building
Flavor Physics
*** neutral K-meson mass differences
mu to e gamma rate limit
b to s gamma rate matching
CP Violation
*** Neutron electric dipole moment limit
CKM angles
Proton life time limit
(rules out simplest grand unified models)

4. More constraints Astrophysical limits e.g. lifetime of red giants
Cosmological limits
limits on neutrino mass from CMB
overclosing the Universe
Not so precise – but equally critical

5. How do low energy precision measurements test the TeV scale?
New heavy particles
appear as intermediate states in quantum processes, even though there is not enough energy to produce them directly
i.e. new loop diagrams

6. When are the new contributions significant?
They are higher order in small parameters, and maybe suppressed by heavy masses
i.e. small
Important where:
They allow processes otherwise forbidden OR
Precision calculations relate multiple measurements with few parameters

7. When do we have such precision calculations?
Weak and electromagnetic effects
But we calculate for quarks and measure hadrons
Ratios or other combinations of measurements that remove sensitivity to uncertainties of hadronic physics

8. Example –CKM parameter fits
Weak couplings of quarks
given by a 3x3 Unitary matrix
CKM – Cabibbo, Kobayashi and Maskawa
--4 parameters, one of which gives rise to CP violation
--- many measurements
Look for inconsistencies

9. CKM Fitter

10. Some next generation experiments
Super B Factory
–higher precision for B decays
Searches for specific rare processes
--“forbidden” decays
certain rare K decays
mu to e gamma
proton decay -- large scale deep underground detectors

11. Theory advances needed too
To “use” precise measurements need equally precise theory
Basic tool is Wilson’s operator product expansion
Q = C x M
Perturbative calculation for coefficients C
Lattice QCD calculations for matrix elements M
Symmetries (reduce number of independent M’s)
Careful scale matching!
Ongoing improvements and refinements of the techniques

12. Interpreting any high energy discovery
Many models with new heavy particles
Discovery and Identification are two different steps
Precision constraints aid identification