5 research outputs found
Singular order parameter interaction at nematic quantum critical point in two dimensional electron systems
We analyze the infrared behavior of effective N-point interactions between
order parameter fluctuations for nematic and other quantum critical electron
systems with a scalar order parameter in two dimensions. The interactions
exhibit a singular momentum and energy dependence and thus cannot be
represented by local vertices. They diverge for all N greater or equal 4 in a
collinear static limit, where energy variables scale to zero faster than
momenta, and momenta become increasingly collinear. The degree of divergence is
not reduced by any cancellations and renders all N-point interactions marginal.
A truncation of the order parameter action at quartic or any other finite order
is therefore not justified. The same conclusion can be drawn for the effective
action describing fermions coupled to a U(1) gauge field in two dimensions.Comment: 18 pages, 1 figur
Slepton pair production in the POWHEG BOX
We present an implementation for slepton pair production at hadron colliders
in the POWHEG BOX, a framework for combining next-to-leading order QCD
calculations with parton-shower Monte-Carlo programs. Our code provides a SUSY
Les Houches Accord interface for setting the supersymmetric input parameters.
Decays of the sleptons and parton-shower effects are simulated with PYTHIA.
Focussing on a representative point in the supersymmetric parameter space we
show results for kinematic distributions that can be observed experimentally.
While next-to-leading order QCD corrections are sizable for all distributions,
the parton shower affects the color-neutral particles only marginally.
Pronounced parton-shower effects are found for jet distributions.Comment: 10 pages, 4 figure