For the DecayDescriptor in CombineParticles in DaVinci, you need to know the name of the particles which can be used. This list can be dumped the following way:

SetupLHCb
dump_db_to_files.py -c sqlite_file:$SQLITEDBPATH/DDDB.db/DDDB -s /param/ParticleTable.txt

which will dump the file in the folder 'DDDB/param'.

Alternatively, you can also use the CondDBBrowser. Type:

CondDBBrowser

and then go to 'Database → Standard →DDDB' and look for 'param/ParticleTable.txt'