This project will extract the lowest lying flavor singlet 0++ states in a model that could serve as an example of how electroweak symmetry is broken dynamically (technicolor). This will be the first analysis of flavor singlet 0++ states built from fermions in the lattice technicolor field of study. These are important objects, since they can be identified with the effective Higgs particle (sigma) or perhaps the dilaton of the theory. Obviously, understanding the mass of this state relative to the scale of electroweak symmetry breaking, given by the technipion decay constant f(pi) of the theory, is of phenomenological relevance. We will also obtain an estimate of the width of this particle, which determines whether or not it is experimentally detectable. Based on studies of Minimal Walking Technicolor, the 0++ glueball may be anomalously light in the theory we propose to study; we will be able to extract its mass. It might even be able to be identified as the dilaton of the theory, depending on how small its mass is compared to f(pi).
The method used will be lattice gauge theory. To perform this task, we will extend the QUDA library (NVIDIA-based multi-GPU code developed for quantum chromodynamics, the theory of the nuclear strong interaction) to address SU(2) gauge theory with fermions in the adjoint (triplet) representation. On top of QUDA we will write software layers for simulation and for analysis. In the analysis stage we will estimate disconnected diagrams by exploiting dilution. We will also extract the glueball state by utilizing smearing, blocking and variational techniques. Our experience and software layers will enable us to rapidly take on other theories besides SU(2) gauge theory with adjoint fermions in the future. We will use clover improved lattice fermions with stout smeared gauge links, in order to reduce lattice artifacts.
Because our code will be made public, the scientific community will benefit by being able to use our code for other studies. Our analysis code will be flexible and in fact not tied to the gauge group and representation. Thus it can be used for studying 0++ states in other theories, including quantum chromodynamics. As a result, a significant outcome of the present project is reusable code with wide application.
We will train students in theoretical and supercomputing skills, providing a path toward careers in scientific computing. We will create increased interest in "beyond the standard model" physics at Rensselaer, broadening the exposure of students to current trends in high energy physics. We will perform outreach to a middle school, and develop lesson plans built around activities that teach concepts associated with our research.
