Tetraquark states in the bottom sector and the status of the Y_b(10890) state

We have performed an exploratory study of bottom tetraquarks ([bq anti b anti q]; q element of u, d) in the diquark. antidiquark framework with the inclusion of spin hyperfine, spin.orbit and tensor components of the one gluon exchange interaction. Our focus here is on the Y_b(10890) and other exotic states in the bottom sector. We have predicted some of the bottom counterparts to the charm tetraquark candidates. Our present study shows that if Z_b(10610) and Z_b(10650) are diquark.diantiquark states then they have to be first radial excitations only and we have predicted the Z_b(10650) state as first radial excitation of tetraquark state X_b(10.143-10.230). We have identified X_b state with J^PC = 1^+-/0⁺⁺ as being the analog of Z_c(3900). The observation of the X_b will provide a deeper insight into the exotic hadron spectroscopy and is helpful to unravel the nature of the states connected by the heavy quark symmetry. We particularly focus on the lowest P-wave [bq][ anti b anti q] states with J^PC = 1^-- by computing their leptonic, hadronic, and radiative decay widths to predict the status of the still controversial Y_b(10890) state. Apart from this, we have also shown here the possibility of mixing of P-wave states. In the case of mixing of the 1^-- state with different spin multiplicities, we found that the predicted masses of the mixed P states differ from the Y_b(10890) state only by ±20 MeV energy difference, which can be helpful to resolve further the structure of Y_b(10890). (orig.)