Production mechanism of doubly charmed exotic mesons T c c

We investigate the production mechanism for doubly charmed tetraquark mesons within a coupled-channel formalism. The two-body Feynman kernel amplitudes are constructed using effective Lagrangians that respect heavy quark symmetry, chiral symmetry, SU(3) flavor symmetry, and hidden local symmetry. The fully off-shell coupled scattering equations are solved within the Blankenbecler-Sugar reduction scheme. We find three positive-parity and one negative-parity tetraquark states with total spin <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>J</a:mi> <a:mo>=</a:mo> <a:mn>1</a:mn> </a:math> . Among them, two positive-parity states appear as bound states in the isoscalar and isovector <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mi>D</c:mi> <c:msup> <c:mi>D</c:mi> <c:mo>*</c:mo> </c:msup> </c:math> channels, while another appears as a resonance in the <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:msup> <e:mi>D</e:mi> <e:mo>*</e:mo> </e:msup> <e:msup> <e:mi>D</e:mi> <e:mo>*</e:mo> </e:msup> </e:math> channel. A negative-parity resonance is also predicted in the isoscalar channel. We analyze the coupling strengths of these tetraquark states to various channels. The dependence of the results on the reduced cutoff mass <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:msub> <g:mi mathvariant="normal">Λ</g:mi> <g:mn>0</g:mn> </g:msub> </g:math> is examined. The most significant tetraquark state remains stable within the range of <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"> <j:mrow> <j:msub> <j:mrow> <j:mi mathvariant="normal">Λ</j:mi> </j:mrow> <j:mrow> <j:mn>0</j:mn> </j:mrow> </j:msub> <j:mo>=</j:mo> <j:mo stretchy="false">(</j:mo> <j:mn>600</j:mn> <j:mi>–</j:mi> <j:mn>700</j:mn> <j:mo stretchy="false">)</j:mo> <j:mtext> </j:mtext> <j:mtext> </j:mtext> <j:mi>MeV</j:mi> </j:mrow> </j:math> .