function tminus = tminus(ld, b, prec)
arguments
    ld
    b
    prec = 32;
end
    ldb = ld*b;
    p = ld/(ld-1);
    q = (2-ld)/(2*ld-2);
    fun = @(x) (1 - x.^2).^q ./ ...
        sqrt(1 + p * ldb^2 * hypergeom([-p+1 1], 2, x.^2));
    tol = 10^(-prec);
    tminus = vpa(ldb * 2/(ld-1) * ...
        vpaintegral(fun, 0, 1, 'RelTol', tol, 'AbsTol', 0), prec);
end