Production of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>η</mml:mi> <mml:mi>b</mml:mi> </mml:msub> </mml:math> in ultraperipheral Pb-Pb collisions

Very recently, the two-photon decay width of the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:msub> <a:mi>η</a:mi> <a:mi>b</a:mi> </a:msub> </a:math> meson was computed with lattice QCD methods. This decay has not yet been measured. The knowledge of this width allows for the calculation of the <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:msub> <b:mi>η</b:mi> <b:mi>b</b:mi> </b:msub> </b:math> production cross section through photon-photon interactions in ultraperipheral (UPC) <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:mrow> <c:mi>P</c:mi> <c:mi>b</c:mi> <c:mtext>−</c:mtext> <c:mi>P</c:mi> <c:mi>b</c:mi> </c:mrow> </c:math> collisions. In this work we present this calculation, which is the first application of the lattice result. Since UPCs are gaining increasing attention of the heavy-ion community, we take the opportunity to perform a comprehensive study of the different ways of defining ultraperipheral collisions and of the different ways to treat the equivalent photon flux.