62  US 8,546,063 B2  61  -continued  (All)  ~ $_{COO-Ab-V }$ In formula (All), Rb$_{0 }$ represents a hydrogen atom, a halo› gen atom, or an alkyl group having from 1 to 4 carbon atoms.  As the examples of preferred substituents that the alkyl group  represented by Rb$_{0 }$may have, a hydroxy  1  group and a halogen  atom are exemplified. As the halogen atom represented by  Rb  0, a fluorine atom, a chlorine atom, a bromine atom, and an  iodine atom are exemplified. Rb$_{0 }$ preferably represents a  hydrogen atom, a methyl group, a hydroxymethyl group, or a  trifluoromethyl group, and especially preferably a hydrogen  atom or a methyl group.  Ab represents a single bond, an alkylene group, a divalent  linking group having a monocyclic or polycyclic alicyclic  hydrocarbon structure, an ether bond, an ester bond, a carbo› nyl group, or a divalent group of combining these groups, and  preferably a single bond or a linking group represented by  -Ab$_{1}$ -C0$_{2}$ -.  Ab $_{1 }$represents a straight chain or branched alkylene group,  or a monocyclic or polycyclic cycloalkylene group, and pref› erably a methylene group, an ethylene group, a cyclohexylene  group, an adamantylene group, or a norbomylene group.  V represents a group having a lactone structure. Specifi› cally, V represents a group having a structure represented by  any of formulae  (LCl-1) to (LCl-17).  The lactone structural part may have or may not have a  substituent (Rb$_{2}$ ). As preferred substituents (Rb 2 ), an alkyl  group having from 1 to 8 carbon atoms, a cycloalkyl group  having from 4 to 7 carbon atoms, an alkoxyl group having  from 1 to 8 carbon atoms, an alkoxycarbonyl group having  from 2 to 8 carbon atoms, a carboxyl group, a halogen atom,  a hydroxyl group, a cyano group, and an acid-decomposable  group are exemplified, and more preferred substituents are an  alkyl group having from 1 to 4 carbon atoms, a cyano group,  and an acid-decomposable group. n$_{2 }$ represents an integer of  0 to 4. When n$_{2 }$is 2 or more, each substituent may be the same  with or different from every other substituent. A plurality of  substituents (Rb$_{2}$ )  may be bonded to each other to form a ring.  As repeating unit having a lactone structure, a repeating  unit represented by the following formula (All) is preferred.  LCl-12  LCl-17  Of the repeating units represented by formula (All), as  repeating units having an especially preferred lactone group  when Ab represents a single bond, the following repeating  units are exemplified. In the specific examples, Rx represents  H, CH$_{3}$ ,  CH$_{2}$0H,  or  CFy  LCl-15  LCl-14 