High Energy Physics

The goal of high energy physics (also known as particle physics) is to determine the most fundamental building blocks of matter and to understand the interactions between these particles. The underlying theoretical construct in particle physics is called the Standard Model and it contains 6 quarks, 6 leptons, 4 gauge bosons, and one scalar boson (the Higgs boson), which interact through three interactions (strong force, weak force, and electromagnetism). Further knowledge can be gained by trying to understand what happens at higher energies (corresponding to smaller distances), where we may produce new particles or identify discrepancies in the Standard Model. We can also investigate the existing array of particles in more depth at lower energies in search of clues to what lies beyond the Standard Model. These results will provide a better understanding of how the universe works, potentially answering questions like why is the Higgs mass so light, what is dark matter made of, are all the forces unified into one force at high energy, what happened to the antimatter in the early universe, etc.

The at the University of Colorado conducts a variety of experimental and theoretical high energy physics research.

The have two main groups, one working on the energy frontier as part of the experiment at and one working on the intensity frontier studying neutrinos as part of the the experiment at , the experiment at , and the program at .

The major research areas of the include lattice gauge theory (mostly about strongly coupled systems potentially appropriate to dark matter or to beyond-standard model phenomenology) and string theory and quantum gravity (mostly about the AdS/CFT correspondence).

High Energy Physics Research Groups

Experimental Research

The  is located inside the Large Hadron Collider (LHC) at  in Geneva, Switzerland. The two main goals of the experiment are to understand the origin of electroweak symmetry breaking and to search for physics beyond the standard model. The Higgs boson discovery announcement on July 4, 2012 was a great leap forward in meeting the first goal and completes the discovery of the standard model particles. In the search for new physics, we have ruled out many possibilities and continue to search for what lies beyond. The  has four current faculty members: John Cumalat, Kevin Stenson, Keith Ulmer and Steve Wagner as well as an emeritus faculty member: Bill Ford. Cumalat’s research focus is on searches for Z′ decays to Ď„ pairs and rare decays of Z bosons. Ford, Stenson and Ulmer are working together on searches for supersymmetry in hadronic modes. Cumalat and Wagner collaborate on research for R&D of silicon sensors and electronics for an upgraded CMS pixel detector, while Stenson and Ulmer work on R&D for an upgraded trigger and data acquisition system based on charged particle tracking. Colorado also hosts a Tier-3 CMS computing site.

The T2K group at CU is lead by Professors  and .  is a neutrino oscillation experiment located in Japan. It studies a beam of neutrinos, produced at  (near Tokai, 100 km northeast of Tokyo), and sees how the neutrinos have changed when they reach the  detector, 295 km away in the Kamioka mine. Recently, the T2K experiment discovered conclusive evidence for the  in a beam of muon neutrinos. This indicates a non-zero value of theta13. The CU group built one of the pion focusing horn magnets and is involved in many areas of physics analysis for both the near and far detectors. Colorado hosts a T2K computing center.

The NA61/SHINE Group at CU is lead by Professors  and . NA61/SHINE is a large-acceptance detector located at . The detector allows researchers to make precise measurements of the production of hadrons from high-energy protons interactions. These measurements can help us to better understand the neutrino fluxes for accelerator-generated neutrino beams such as those used for T2K and other experiments.

DUNE is a proposed long-baseline neutrino oscillation experiment that would involve a new neutrino beam from  to South Dakota. The CU group (led by Professors Eric Zimmerman and Alysia Marino) is primarily focused on making in-situ and ex-situ measurements of the hadrons in the neutrino beam, to improve predictions for the neutrino flux.

Overview

The  explores the mathematical and theoretical nature of high-energy physics, including: string theory and quantum gravity, lattice QCD and lattice studies of related systems as beyond Standard Model candidates, and phenomenology associated with potential new physics at the Large Hadron Collider.

Senarath de Alwis

I'm interested in String theory, Supersymmetry breaking and Cosmology. My main interest at this point is in understanding beyond the standard model physics and cosmology from the vantage point of string theory. The latter is the only consistent theory of all the fundamental interactions that we have today and I believe it is important to understand its consequences for both TeV scale particle physics phenomenology (soon to be explored at the LHC) and cosmology.

Tom DeGrand

I study the properties of strongly-interacting systems, most of which appear in the context of elementary particle physics, with a combination of analytic and numerical techniques. I am interested in the physics of strongly interacting quantum fields. The prototype of such system is Quantum Chromodynamics, the theory of quarks and gluons which describes the strong nuclear force. Recently, I have become more interested in similar systems, which might be candidates for new beyond Standard Model physics

I am interested in string theory and supergravity, their applications to other phenomena via holography, particle physics, cosmology and quantum field theory.

Anna Hasenfratz

I am interested in the properties of quantum field theoretical models. My research concentrates on the non-perturbative properties quantum field theories, mainly QCD. Non-perturbative studies frequently require computer simulations but the emphasis is always on the physical picture and understanding of the physical phenomena.

My group works at the interface of theoretical condensed matter, high energy, mathematical and atomic physics. We specialize in the study of dynamics in strongly interacting quantum many-body systems.

Ethan Neil

My research interests are in physics beyond the standard model, particularly its signatures in collider and dark matter experiments, and more generally in the physics of strongly-coupled elementary particles, which I study numerically using large-scale computing. My particular interests include composite Higgs and composite dark-matter models, precision calculations of heavy-quark properties (which are an important input to experimental searches for new physics), and the dynamics of many-fermion gauge theories.