I have a need to use a search filter in SASL mappings where it looks like something

(&(uid=\1)(|(objectclass=x)(objectclass=y)))

the & is being substituted like \1 as seen with tracing turned on.  I have tried escaping it as \& and \\&.  I can't find any documentation on how the substitution is handled with the filter.  Is it not possible to utilize a normal ldap search filter like this in SASL mappings?

thanks for answers and/or pointers.