The formula for Lorentzian Function, Lorentz(x, y0, xc, w, A), is:
y = y0 + (2*A/PI)*(w/(4*(x-xc)^2 + w^2))
y0 is the baseline offset.
xc is the center of the peak.
w equals the width of the peak at half height.
A is the area under the peak.