QCD 2 ’t Hooft model: Two-flavor mesons spectrum

We continue analytical study of the meson mass spectrum in the large- <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:msub> <a:mi>N</a:mi> <a:mi>c</a:mi> </a:msub> </a:math> two-dimensional QCD, known as the ’t Hooft model, by addressing the most general case of quarks with unequal masses. Based on our previous work, we develop nonperturbative methods to compute spectral sums and systematically derive large- <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mi>n</c:mi> </c:math> WKB expansion of the spectrum. Furthermore, we examine the behavior of these results in various asymptotic regimes, including the chiral, heavy quark, and heavy-light limits, and establish a precise coincidence with known analytical and numerical results obtained through alternative approaches.