Correlation function for the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>n</mml:mi> <mml:msubsup> <mml:mover accent="true"> <mml:mi>D</mml:mi> <mml:mo stretchy="false">¯</mml:mo> </mml:mover> <mml:mrow> <mml:mi>

We study the interaction of a neutron with the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:msubsup> <a:mover accent="true"> <a:mi>D</a:mi> <a:mo stretchy="false">¯</a:mo> </a:mover> <a:mrow> <a:mi>s</a:mi> <a:mn>0</a:mn> </a:mrow> <a:mo>*</a:mo> </a:msubsup> <a:mo stretchy="false">(</a:mo> <a:mn>2317</a:mn> <a:mo stretchy="false">)</a:mo> </a:math> resonance and look at the amplitude below threshold and close above threshold. The study is done from the perspective that the <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:msubsup> <g:mi>D</g:mi> <g:mrow> <g:mi>s</g:mi> <g:mn>0</g:mn> </g:mrow> <g:mo>*</g:mo> </g:msubsup> <g:mo stretchy="false">(</g:mo> <g:mn>2317</g:mn> <g:mo stretchy="false">)</g:mo> </g:math> resonance is a molecular state of <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"> <k:mi>D</k:mi> <k:mi>K</k:mi> </k:math> in <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"> <m:mi>I</m:mi> <m:mo>=</m:mo> <m:mn>0</m:mn> </m:math> . To study this interaction, we use the fixed center approximation to Faddeev equations that considers the <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"> <o:mi>D</o:mi> <o:mi>K</o:mi> </o:math> molecule as the cluster and the neutron as the external particle. We improve the fixed center approach to implement elastic unitarity around threshold, which is needed to obtain scattering parameters and to evaluate the <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"> <q:mi>n</q:mi> <q:msubsup> <q:mover accent="true"> <q:mi>D</q:mi> <q:mo stretchy="false">¯</q:mo> </q:mover> <q:mrow> <q:mi>s</q:mi> <q:mn>0</q:mn> </q:mrow> <q:mo>*</q:mo> </q:msubsup> <q:mo stretchy="false">(</q:mo> <q:mn>2317</q:mn> <q:mo stretchy="false">)</q:mo> </q:math> correlation function that we determine here. One interesting result of the study is the appearance of a resonant state below threshold with a binding of about 130 MeV and a width of about 80 MeV, which we suggest to look at in reactions measuring the invariant mass of <w:math xmlns:w="http://www.w3.org/1998/Math/MathML" display="inline"> <w:mi>π</w:mi> <w:mi mathvariant="normal">Σ</w:mi> <w:mover accent="true"> <w:mi>D</w:mi> <w:mo stretchy="false">¯</w:mo> </w:mover> </w:math> . The ALICE collaboration has initiated studies of this type, by looking at the <bb:math xmlns:bb="http://www.w3.org/1998/Math/MathML" display="inline"> <bb:mi>p</bb:mi> <bb:msub> <bb:mi>f</bb:mi> <bb:mn>1</bb:mn> </bb:msub> <bb:mo stretchy="false">(</bb:mo> <bb:mn>1285</bb:mn> <bb:mo stretchy="false">)</bb:mo> </bb:math> correlation function, and we can only encourage work in this direction, which should provide much valuable information on the nature of many resonant states.