Keywords ======== Current keywords are ``cmenergies`` (in units of GeV), ``observables``, ``phrases``, and ``reactions``. Individual keywords can be omitted if they are not relevant. Each keyword is associated with a list of possibly multiple values, e.g. .. code-block:: yaml keywords: # used for searching, possibly multiple values for each keyword - {name: reactions, values: [P P --> Z0 Z0 X]} - {name: observables, values: [SIG]} - {name: cmenergies, values: [7000.0]} - {name: phrases, values: [Inclusive, Integrated Cross Section, Cross Section, Proton-Proton Scattering, Z Production, Z pair Production]} Each *reaction* should consist of initial- and final-state particles separated by ``-->``, with particles on each side of the arrow separated by spaces. The right-hand side should usually have an ``X`` to indicate an inclusive reaction (as opposed to exclusive where all final-state particles are known, e.g. elastic proton scattering). A standard :doc:`notation ` should preferably be used for each particle. Omit the decay products or give them as a separate reaction. Each *observable* should consist of only a single word, for example, use ``SIG`` for a cross section, ``DSIG/DPT`` for a differential cross section, ``N`` for number of events, etc., again preferably using a standard :doc:`notation `. Each *phrase* should be preferably be selected from a :doc:`list `. Note that the linked lists of :doc:`particles `, :doc:`observables ` and :doc:`phrases ` were created several years ago from the old HepData site and may not be relevant. Assigning keywords unique to a particular HEPData record is of little value, therefore keywords should be omitted if in doubt. It is an open issue (`HEPData/hepdata#60 `_) to make it easier to select keywords by developing appropriate software.