Does a man's unintentional touching of a non-mahram woman while fasting invalidate his fast?

Touching a woman does not invalidate the fast unless it leads to the intentional emission of maniy (sperm), in which case it invalidates the fast by scholarly consensus. If it was by mistake, it does not invalidate it. As for the intentional emission of madhiy (pre-seminal fluid), there is a difference of opinion. A man must avoid touching non-mahram women, especially in Ramadan, as the warning against it is severe.