queries with "&&" doesn't work but "AND" does

[Devi pulaparti]

In our search application, queries like  test && usage  do not return
correct results but  test AND usage works fine.  So queries with "&&"
doesn't work but "AND" does. We are using default queryparser with standard
analyzer. Could some one please help me resolving this. please let me know
if you need more details of implementation.