WNPPC Prep 2

Mon., Feb. 10, 2020 3:30 p.m. - Mon., Feb. 10, 2020 4:30 p.m.

Location: RI 208

Charged pi-Meson Studies at Jefferson Lab

Abstract: It is experimentally proven that the mass of the hadron is significantly larger than the combined
mass of its constituents (quarks and gluons). The reason for this lies in the inner structure of
hadrons and the interactions between the constituent quarks and gluons. Quantum
Chromodynamics (QCD) is the theory that explains the interaction of hadrons, but it does not
provide a clear picture of their inner structure. The pion is a simple system, consisting only of two
valence quarks (up and down), making it an ideal candidate to study in order to understand
hadronic structure. Experimentally, the inner structure of hadrons can be studied in detail by
scattering electrons off nuclei. One of the easiest and most abundant exclusive reactions after such
scattering produces charged pions (i.e. p(e,e’,𝜋")n ). The cross-section for this reaction largely
depends on the exchange of a virtual photon between an incident electron and the target nucleon.
This cross-section then allows us to extract the pion form factor, a key parameter in the
understanding of pion sub-structure, which indicates the momentum and spatial distribution of
constituent particles. These studies are being conducted at the Thomas Jefferson National
Accelerator Facility (JLab) in Newport News, VA, USA. JLab has recently undergone a major
upgrade; our pion structure studies are one of the flagship experiments enabled by this upgrade.
In this talk, I will outline the physics motivation behind these studies, as well as providing an outline
of the experimental facility. Preliminary results from the analysis of experimental data and a future
outlook will also be presented.

Speaker: Ali Usman, Department of Physics, University of Regina

Kaon Electromagnetic Form Factor

Abstract: It is well understood that hadrons are composed of smaller, more fundamental particles,
quarks and gluons. The internal structure of hadrons is determined by the interaction
between these constituent quarks and gluons. The simplest hadronic systems we can
analyse to understand this internal structure are the pion and kaon. The electromagnetic
form factor of pions and kaons plays a unique role in understanding of their internal
structure. Experimental measurements of the LT (longitudinal and transverse) cross
sections for the kaon and pion have been carried out at the Thomas Jefferson National
Accelerator Facility (Jlab) in Newport News, Virginia, USA. Data for the reactions p(e,
e’K+)⋀ and p(e, e’K+)Σ0 have been measured at various kinematic points. The precision
measurements of LT separated cross-sections are of particular interest. They allow us to
extract the form factor which is a measure of the spatial distribution of the mesons’
constituents. The Rosenbluth separation technique is used to separate the longitudinal
and transverse cross sections from the experimental measurements. In this talk, I will
outline some of the experimental details, including the detector systems in use and the
Rosenbluth separation technique. I will also briefly outline how the data will be used to
extract the kaon electromagnetic form factor.

Speaker: Vijay Kumar, Department of Physics, University of Regina