Precision Calculations in Hadron and Beyond the Standard Model phyics

H.K. Dreiner (UB) / C.-D. Lü (IHEP)


The Standard Model of particle physics (SM), despite being extremely successful, is also
incomplete. The baryon asymmetry and the dark matter of the universe, the neutrino masses, and
the hierarchy problem remain open questions. A widely considered extension of the SM, based on
a fundamental external symmetry is supersymmetry, which solves the hierarchy problem, and
offers solutions to the other shortcomings of the SM. With the minimal particle content,
supersymmetry comes in two versions distinguished by a multiplicative discrete symmetry: R-parity
conserving (RPC) and R-parity Violating (RPV) supersymmetry. RPC naturally solves the dark
matter puzzle via the stable lightest neutralino. RPV naturally includes light neutrinos via the
lepton-number violating interactions, with an additional heavy see-saw scale for the Majorana
mass. RPC and RPV have the same particle content, but RPV has 45 additional Yukawa-like
operators: L L E, L Q D, U D D, as well as corresponding soft supersymmetry breaking terms.
These all violate lepton- or baryon-number. RPV models are not as widely studied in the literature,
but as we have extensively discussed, they are at least as well motivated. The purpose of project
A.7 is to set the best possible limits on the RPV parameters using the latest developments in
hadron physics.