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

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”

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)

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

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

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

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

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

CKM Fitter

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

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

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