K 0 ? ( 800 ) as a companion pole of K 0 ? ( 1430 )

摘要

We study the light scalar sector up to 1.8 GeV by using a quantum field theoretical approach which includes a single kaonic state in a Lagrangian with both derivative and non-derivative interactions. By performing a fit to πK phase shift data in the I = 1 / 2 , J = 0 channel, we show that K 0 ? ( 800 ) (or κ ) emerges as a dynamically generated companion pole of K 0 ? ( 1430 ) . This is a result of investigating quantum fluctuations with one kaon and one pion circulating in the loops dressing K 0 ? ( 1430 ) . We determine the position of the poles on the complex plane in the context of our approach: for K 0 ? ( 1430 ) we get ( 1.413 ± 0.002 ) ? i ( 0.127 ± 0.003 ) (in GeV), while for κ we get ( 0.746 ± 0.019 ) ? i ( 0.262 ± 0.014 ) (in GeV). The model-dependence of these results and related uncertainties are discussed in the paper. A large- N c study confirms that K 0 ? ( 1430 ) is predominantly a quarkonium and that K 0 ? ( 800 ) is a molecular-like dynamically generated state.