Physics & Engineering Physics Colloquia

Zeke Mohammed, FCRH 2026, Engineering Physics Major, will present “Meson Mass Calculations in Lattice QCD Using SU(2) Gauge Theory”.

Abstract: Quantum Chromodynamics (QCD) describes the strong nuclear force but
becomes strongly coupled at low energies where perturbative methods fail. Lattice QCD
resolves this by discretizing spacetime into a finite grid, transforming the quantum field
theory into a computationally tractable problem. This work implements SU(2) gauge
theory—a simplified two-color version of QCD that preserves essential non-perturbative
phenomena like confinement and asymptotic freedom—to calculate light meson masses
including the pion, rho, and sigma.

We employ Monte Carlo methods with the Wilson gauge action to generate thermalized
gauge field configurations and solve the discretized Dirac equation for quark
propagators. Meson masses are extracted from the exponential decay of correlation
functions, with statistical uncertainties determined through jackknife analysis.
Calculations span multiple lattice volumes (44 to 83×16) and quark mass parameters to
systematically study mass hierarchies and chiral symmetry breaking. Our results
successfully reproduce expected mass ordering (mπ < mρ) and demonstrate how
confinement emerges from gauge dynamics to bind quarks into hadrons, providing
quantitative insights into non-perturbative QCD phenomena.

Matthew Smith, FCRH 2027, Physics Major, will present: “Pion Masses and Taste Splitting at Coarse Lattice Spacings”.

Abstract: On the lattice taste splitting of pions should be degenerate at O(a2). It is shown,
however, that corrections of order O(a4 ) are required to describe the observed masses.
This project attempted to extract the masses of the pions on a coarse lattice by
uncorrelated, correlated, and blocked-correlated fits to evaluate discrepancies of the
theory. Data from 5001 configurations and a lattice temporal dimension of 48 was used.
While the pseudo-scalar pion’s mass was able to be extracted, the vector, scalar, axial
vector, and tensor tastes had significant errors. It is shown that these coarse lattices
introduced large errors as well as oscillatory “opposite-parity” contributions to the
correlators, complicating mass extractions. Newer lattice simulations, however, show
promising results for the non-goldstone pions while still having some complications from
large lattice spacings.