Searching for Two Half-Brothers - GERMANY

Hello, my name is Gnther, I am searching for my two half-brothers who were (same as I) illegitimately born in Mainz Germany and then released for adoption. According to our birth mother, Elisabeth ARNDT, born March 7th, 1934 in Siersleben Germany, both boys were adopted by American (soldier?) families, initiated by Mainz Youth Welfare Office (by Mr. Axt). My first brother was born Nov 24th, 1956 as Joachim ARNDT, my second brother was born Nov 13th, 1960 as Reimund ARNDT. I am aware that both of them probably have different names now and might not even know of their adoption, or of the others' existence. So please, if you have any kind of information or your birthday matches, or if you know anybody whose birthday matches, please check back with me. Thanks.