S. Shulha

The work proposes a new method for measuring the gluon jet fraction in jet sample produced at the hadron collider. This method uses model quark/gluon templates - distributions of quark and gluon jets over the jet macro parameter. Within the framework of this method, it is possible to find a model uncertainty of measurement associated with the deviation of model quark/gluon templates from the true ones. The issue of data-motivated corrections to the model quark/gluon templates is discussed.

To measure the characteristics of quark and gluon jets in hadron-hadron collisions, two samples of jets are used. Given the large statistics of jets at the LHC, the two-sample method requires taking into account the following corrections: (1) use of measured fractions of quark and gluon jets instead of the model ones, (2) amendment for the contribution of jets with an unidentified flavour, (3) taking into account the dependence of the distributions of quark and gluon jets on the conditions for jet sample selections. The paper presents an improved two-sample method that takes into account these corrections.

The difference in properties of jets initiated by quarks and gluons as a result of hadron–hadron collisions, opens up the possibility of their recognition. Special quark-gluon discriminators of jets are built for this purpose. This paper discusses methods for measuring the fractions of quark and gluon jets in jet sample using the quark-gluon jet discriminator. This opens up the possibility of measuring various characteristics of quark and gluon jets. The technique of such measurements for modern hadron colliders is discussed.