This award provides travel funds and computational resources toward the project objective of investigating the properties and the quark substructure of the scalar meson below two gigaelectronvolts and their impacts on related issues in low-energy Quantum Chromodynamics (QCD). A well-known, and quite puzzling, aspect of the lightest scalar mesons is that there seems to be a reverse mass ordering of states containing strange and non-strange quarks: the putative K_0^*(800) meson (with a strange quark) is lighter than the a_0(980) meson (containing solely non-strange quarks). This has led to the speculation that these scalar mesons are predominantly tetraquark, and not quark-antiquark states.
The research will involve comparing different approximation schemes in strongly coupled regimes and interpreting exotic states in terms of diquarks and tetra quarks. The approach will be the method of effective field theories coming from chiral Langrangians whose parameters will be determined from experimental data found in the Particle Data Group publication from SLAC. Partial wave amplitudes that have been constructed from experimental data will be used to determine the usefulness of the diquark approach as well as different unitarization schemes. Using these methods the properties of the low mass scalar mesons will be better understood theoretically. The broader impacts are that it is hoped by better understanding the lower energy scalar mesons one will get some insight into the non-perturbative Higgs dynamics in the Standard Model. It is also hoped that this analysis can be helpful in understanding the decay of heavier mesons by the BaBar collaboration. The PI will make his research accessible for the undergraduates at his institution to take part in various aspects of his research project.
