I am a physics undergraduate student hoping to apply to grad school in the future. While my current research professor of a year is wonderful and will no doubt provide a great letter of recommendation, my previous research professor has a negative reputation around the department (I thought he was fine but other professors complained about personality, apparently is often very rude) and, more importantly, I am unsure whether or not he will give me a good rec (initial work went okay, mentioned possible publication, but halfway through the semester he stopped contacting me and ceased work suddenly). I have others I could ask for a rec letter, but I have research credit with him on my transcript. Unsure of publication status. Should I ask him if he can provide a strong letter of recommendation?