Charmonium-like resonances with JPC = 0++, 2++ in coupled $$ \mathrm{D}\overline{\mathrm{D}} $$, $$ {\mathrm{D}}_{\mathrm{s}}{\overline{\mathrm{D}}}_{\mathrm{s}} $$ scattering on the lattice
Sasa Prelovsek, Sara Collins, Daniel Mohler, M. Padmanath, Stefano Piemonte
Abstract
A bstract We present the first lattice investigation of coupled-channel $$ D\overline{D} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>D</mml:mi><mml:mover><mml:mi>D</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:math> and $$ {D}_s{\overline{D}}_s $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>D</mml:mi><mml:mi>s</mml:mi></mml:msub><mml:msub><mml:mover><mml:mi>D</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mi>s</mml:mi></mml:msub></mml:math> scattering in the J PC = 0 ++ and 2 ++ channels. The scattering matrix for partial waves l = 0 , 2 and isospin zero is determined using multiple volumes and inertial frames via Lüscher’s formalism. Lattice QCD ensembles from the CLS consortium with m π ≃ 280 MeV, a ≃ 0 . 09 fm and L/a = 24 , 32 are utilized. The resulting scattering matrix suggests the existence of three charmonium-like states with J PC = 0 ++ in the energy region ranging from slightly below 2 mD up to 4 . 13 GeV. We find a so far unobserved $$ D\overline{D} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>D</mml:mi><mml:mover><mml:mi>D</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:math> bound state just below threshold and a $$ D\overline{D} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>D</mml:mi><mml:mover><mml:mi>D</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:math> resonance likely related to χ c 0 (3860), which is believed to be χ c 0 (2 P ). In addition, there is an indication for a narrow 0 ++ resonance just below the $$ {D}_s{\overline{D}}_s $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>D</mml:mi><mml:mi>s</mml:mi></mml:msub><mml:msub><mml:mover><mml:mi>D</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mi>s</mml:mi></mml:msub></mml:math> threshold with a large coupling to $$ {D}_s{\overline{D}}_s $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>D</mml:mi><mml:mi>s</mml:mi></mml:msub><mml:msub><mml:mover><mml:mi>D</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mi>s</mml:mi></mml:msub></mml:math> and a very small coupling to $$ D\overline{D} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>D</mml:mi><mml:mover><mml:mi>D</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:math> . This resonance is possibly related to the narrow X (3915) /χ c 0 (3930) observed in experiment also just below $$ {D}_s{\overline{D}}_s $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>D</mml:mi><mml:mi>s</mml:mi></mml:msub><mml:msub><mml:mover><mml:mi>D</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mi>s</mml:mi></mml:msub></mml:math> . The partial wave l = 2 features a resonance likely related to χ c 2 (3930). We work with several assumptions, such as the omission of J/ψω , η c η and three-particle channels. Only statistical uncertainties are quantified, while the extrapolations to the physical quark-masses and the continuum limit are challenges for the future.