  Processes involving bottom quarks play a crucial role in the LHC
phenomenology, from flavour physics to Higgs characterisation and as a window
to new physics, appearing both as signals and irreducible background in BSM
searches. These processes can be described in QCD either in a 4-flavor or
5-flavor scheme. In the former, $b$ quarks appear only in the final state and
are considered massive. In 5-flavor schemes, calculations include $b$ quarks in
the initial state. Possibly large logarithms originating from the collinear
splitting of gluons into bottom pairs are resummed into the $b$ parton
distribution function (PDF). In this contribution, I describe a simple method
to assess the size of the logarithms in processes initiated by bottom quarks
and show how a substantial and justified agreement between calculations in the
two schemes can be achieved. As a consequence both calculations can be used in
different context. To conclude, an overview of the current studies aiming to
generalise the current appraisal is given and some preliminary results are
discussed.
