I am trying to fit a distribution as attached. I tried a single gaussian function. But it is not fitting properly. The fitting plot is also attached. Could you please tell me which function should I take to fit the distribution?
that’s a question for your supervisor. A really simple attempt could be to add a polynomial.
From the labels I extract that you seem to be fitting a mass peak, where one could expect some losses due to not reconstructing the full energy of all particles. In that case try a crystal ball function.
No, I mean fit with crystal ball. The crystal ball is a Gaussian that goes over into an exponential tail. If your data have an offset (such as a constant baseline because of combinatorial background), use crystal ball + polynomial of low order.
When you succeed, would you post results here? This way, others might profit from what was discussed here.