57  US 9,323,150 B2  58  -continued  -continued  The presence of a substituent (Rb$_{2}$ )  on the portion of the  lactone structure is optional. As a preferred substituent (Rb$_{2}$ ),  there can be mentioned an alkyl group having  1  to 8 carbon  atoms, a monovalent aliphatic hydrocarbon ring group having  4  to 7 carbon atoms, an alkoxy group having  1  to 8 carbon  atoms, an alkoxycarbonyl group having  1  to 8 carbon atoms,  a carboxyl group, a halogen atom, a hydroxyl group, a cyano  group, an acid-decomposable group or the like. Of these, an  alkyl group having  1  to  4  carbon atoms, a cyano group and an  acid-decomposable group are more preferred. In the formu› lae, n$_{2 }$ is an integer of  O  to  4.  When n$_{2 }$ is 2 or greater, the  plurality of present substituents (Rb$_{2}$ )  may be identical to or  LCl-3  0  LCl-4  0  LCl-5  0  LCl-6  LCl-8  LCl-9  LCl-11  LCl-12  LCl-13  LCl-14  LCl-15  LCl-16  LCl-17 