A broad pseudovector glueball from holographic QCD

Abstract

We study the decay of a pseudovector glueball with quantum numbers JPC=1+−, the lightest glueball with spin different from zero or two, in the top–down holographic Witten–Sakai–Sugimoto model. This glueball is dual to the string-theoretic Kalb–Ramond tensor field, which completely fixes all its couplings by gauge invariance and D-brane anomaly inflow. The dominant decay channels are determined by a Chern–Simons-like action for the flavor branes; couplings from the Dirac–Born–Infeld action turn out to be subdominant. While the resulting width is parametrically of order Nc−2λ−1 for Nc colors and 't Hooft coupling λ, when extrapolated to Nc=3 and with λ matched to experimental data, the prediction is that the pseudovector glueball is an extremely broad resonance.