Research and Education with GlueX

University Of Connecticut, Storrs CT

Investigators

Abstract

The GlueX experiment at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) searches for evidence of a new class of particles called hybrid mesons, which are expected to exist based on the Standard Model of particle physics. The best existing theory calculations for hybrid mesons predicts that 27 such mesons should exist within the mass between 1.8 and 2.5 GeV/c. GlueX has been built to study this full mass region with excellent sensitivity, using a high-intensity polarized photon beam and a state-of-the-art detector capable of identifying these new particles from the momentum distributions of their decay products. The GlueX group at University of Connecticut consists of the PI, one PhD student, and two undergraduate student researchers. This team is responsible for producing the diamond targets that generate the polarized high-energy photon beam from electrons accelerated in the Jefferson Lab accelerator, making sure they meet the stringent requirements in terms of crystal quality and flatness. The group also constructed and maintains the tagging "microscope" detector that is used to measure the photon beam energy. Support received under this grant enables the UConn team to travel to Newport News to support the operation of the GlueX experiment over the next three years, and to work on the analysis of GlueX data. Experimental searches for hybrid mesons over the past 20 years have mostly come up empty, except for one or two outstanding candidates. One plausible reason for this is that prior searches have focused on the wrong mass region, guided by older model calculations which indicated that the masses of the lightest hybrids might be less than 1.5 GeV. Within the past decade, improved predictions have emerged, pointing to a higher mass region 1.8 - 2.5 GeV for the lightest 3 hybrid nonets. GlueX has been built to study this full mass region, with excellent mass resolution and high statistics, in photo production by polarized 9 GeV photons. During the past three years, GlueX has completed commissioning and initial physics data-taking phases. Over the next three years, the experiment will collect a major part of the full dataset required to complete its primary physics mission, and will complete an initial survey of the resonance landscape over the mass range of interest, focusing initially on a small number of exclusive final states that are favored for hybrid decays. The UConn group supports the analysis effort by authoring and maintaining the physics simulation package for GlueX, managing shared computer resources for physics simulation, and participating in the shared data analysis effort. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.