Charm Meson Spectroscopy

Abstract

Heavy quark physics gives a unique opportunity to test the prediction of QCD and standard model. Within the framework of heavy quark effective theory and chiral perturbation theory, masses of heavy mesons are studied. The approximate symmetries of Quantum Chromo- Dynamics in the infinite heavy quark (Q = c) mass limit ( 0) Q m → and in the chiral limit for the light quarks ( 0, , , ) q m → q = u d s can be used together to build up an effective chiral Lagrangian for heavy and light mesons describing strong interactions among effective meson fields. Expanding about a symmetry limit (Λ~1GeV) provides us with a means for describing nonperturbative effects by a series of low energy parameters (effective coupling) which can be determined from experimental data. In our thesis, we use the well-determined masses of the ground states, P 0 ( 0 , , ), S J = − D D+ D+ 1 ( *0 , * , * ) S − D D + D + and the strange first excited states, 0 0 0 0 P 0 ( , , ), S J = + D D+ D+ 0' ' 1 1 1 1 ( , , ) S + D D+ D+ to predict the masses of the non-strange first excited state in the framework of heavy hadron chiral perturbation theory. A mass formula is developed for the charm mesons and comprehensive analysis is done for the low lying charm meson states including the O(1/mC ) corrections, The key differences is that we have constrain the values of the parameters g,g’ ,h to the values that are determined from the decays. Furthermore, we have imposed the requirement that ms = 90 MeV and have required the parameters determining the tree-level hyperfine structure to be in a range determined by the well-established states. This approach points to values for the masses of those states that are smaller than the experimental determinations.