New scalar resonance <i>X</i> ₀ (2900) as a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow> <mml:mover> <mml:mrow> <mml:mi>D</mml:mi> </mml:mrow> <mml:mo></mml:mo> </mml:mover> </mml:mrow> <mml:mrow> <mml:msup> <mml:mrow/> <mml:mrow> <mml:mo>*</mml:mo> </mml:mrow> </mml:msup> </mml:mrow> </mml:msup> <mml:msup> <mml:mrow> <mml:mi>K</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>*</mml:mo> </mml:mrow> </mml:msup> </mml:math> molecule: mass and width

Abstract

Abstract We explore features of the scalar structure X 0 (2900), which is one of the two resonances discovered recently by LHCb in the D − K + invariant mass distribution in the decay B + → D + D − K + . We treat X 0 (2900) as a hadronic molecule composed of the conventional mesons <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:msup> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mi>D</mml:mi> </mml:mrow> <mml:mo>̄</mml:mo> </mml:mover> </mml:mrow> <mml:mrow> <mml:msup> <mml:mrow/> <mml:mrow> <mml:mo>*</mml:mo> <mml:mn>0</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:msup> </mml:math> and K ∗0 and calculate its mass, coupling and width. The mass and coupling of X 0 (2900) are determined using the QCD two-point sum rule method by taking into account quark, gluon, and mixing vacuum condensates up to dimension 15. The decay of this structure to final state D − K + is investigated in the context of the light-cone sum rule approach supported by a soft-meson technique. To this end, we evaluate strong coupling G corresponding to vertex X 0 D − K + , which allows us to find width of the decay X 0 (2900) → D − K + . Obtained predictions for the mass of the hadronic molecule <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:msup> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mi>D</mml:mi> </mml:mrow> <mml:mo>̄</mml:mo> </mml:mover> </mml:mrow> <mml:mrow> <mml:msup> <mml:mrow/> <mml:mrow> <mml:mo>*</mml:mo> <mml:mn>0</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:msup> <mml:msup> <mml:mrow> <mml:mi>K</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>*</mml:mo> <mml:mn>0</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.3333em"/> <mml:mi>m</mml:mi> <mml:mo>=</mml:mo> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mrow> <mml:mn>2868</mml:mn> <mml:mo>±</mml:mo> <mml:mn>198</mml:mn> </mml:mrow> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mspace class="nbsp" width="0.3333em"/> <mml:mi mathvariant="normal">M</mml:mi> <mml:mi mathvariant="normal">e</mml:mi> <mml:mi mathvariant="normal">V</mml:mi> </mml:math> and for its width Γ = (49.6 ± 9.3) MeV can be considered as arguments in favor of molecule interpretation of X 0 (2900).

Topics & Concepts