Hall 123

Nonrelativistic Effective Field Theory for XYZ Exotic Mesons

Abhishek Mohapatra

Technical University of Munich

The discovery of XYZ exotic mesons in the heavy quark sector poses a major challenge to the understanding of the spectrum of Quantum Chromodynamics (QCD). Since 2003, after the first observation of X(3872) exotic meson, around 30 XYZ states have been observed with no clear understanding of the nature and pattern of these states based on QCD. One of the many interpretations of these XYZ exotic mesons is Quarkonium hybrids. In my talk, I will discuss how the quarkonium hybrid states can be addressed in the nonrelativistic effective theory (EFT) framework: Born-Oppenheimer effective theory with inputs from lattice QCD. Based on this EFT framework, I will discuss the computation of the semi-inclusive decay rates of heavy quarkonium hybrids into conventional heavy quarkonia. The decay rates are computed at leading and subleading power in the inverse of the heavy-quark mass. Based on the decay rates, we will rule some of the XYZ mesons as hybrid candidates. I will also discuss how the Born-Oppenheimer effective theory framework can be extended to address the tetraquark, pentaquark, etc states and their decays to quarkonium and meson pair thresholds.