Added AK as author

paper.tex

@@ -21,6 +21,7 @@
   M.~Balzer$^a$,
   M.~Caselle$^a$,
   S.~Chilingaryan$^a$,
+  A.~Kopmann$^a$,
   T.~Dritschler$^a$,
   M.~Weber$^a$\\
   N.~Zilio$^a$,