Speaker
Description
We study the $Z_b$ tetraquark channel, $\bar{b}b\bar{d}u$, with quantum numbers $J^{PC}=1^{+-}$. Our approach involves calculating correlators among three operator classes: (i) static-light meson pair, (ii) quarkonium plus pion, and (iii) the novel interpolator based on BOEFT (Born–Oppenheimer Effective Field Theory) proposed in Ref. [1]. We use the GEVP variational approach to extract the preliminary eigenenergies and overlap factors from the correlation matrix. At short distances, at leading order, this novel interpolator has zero overlap with quarkonium and pions due to the $Q\bar{Q}$ pair being in a color-octet configuration. In contrast, at large distances it evolves into a static-light meson pair, making it a suitable choice to calculate the tetraquark static energies on the lattice. To achieve this, we employ the distillation technique on a CLS ensemble with $N_f=2+1$ and $m_{\pi}=290$ MeV.
[1] Matthias Berwein, Nora Brambilla, Abhishek Mohapatra, and Antonio Vairo. Hybrids, tetraquarks, pentaquarks, doubly heavy baryons, and quarkonia in Born–Oppenheimer effective theory. Phys. Rev. D 110(9):094040, 2024.