# 2+1+1 Lattice QCD Calculations With HEX Smeared Clover Fermions

The strong nuclear force is one of the four known fundamental forces of nature. It is responsible for binding atomic nuclei and their constituents, protons and neutrons, together from elementary particles, the quarks. Quarks come in six flavors, named up, down, strange, charm, bottom, and top. Only the lightest three of them--the up, down, and strange quarks--are typically relevant for everyday life as atomic nuclei almost exclusively contain these three species only. The next lightest quark, the charm, is responsible for a multitude of very short-lived particles--some of which have been discovered--and for small corrections to the properties of more common particles, such as protons and neutrons.

Our current theory of quarks and their interaction via the strong nuclear force - quantum chromodynamics (QCD) - should in principle allow us to predict all these effects, to reproduce the masses of the observed short-lived particles containing a charm quark and to predict the masses of yet unobserved ones. In reality however, the computations underlying these predictions are extremely demanding: one has to discretize space and time on a grid or lattice and solve the equations of the theory (QCD) on it. The computational demands are even greater when one needs to accommodate the lightest quarks and the relatively heavy charm quark at the same time, because the light quarks require the volume to be large while the heavy charm quark requires the lattice to be fine at the same time. The cutting-edge supercomputer resources of GCS will enable us to solve the equations of QCD on a large enough and simultaneously fine enough lattice to accurately compute the effects of the charm quark and predict the masses of short-lived particles it is contained in, which will contribute to better understanding the strong nuclear force.

Source: © Bergische Universität Wuppertal, Theoretische Physik, Fachbereich C

Dr. Christian Hölbling

Theoretische Physik, Fachbereich C - Bergische Universität Wuppertal

D-42097 Wuppertal/Germany

e-mail: hch@physik.uni-wuppertal.de