Constraining the top-quark mass within the global MSHT PDF fit

Abstract

AbstractWe examine the ability of experimental measurements of top-quark pair production to constrain both the top-quark mass and the strong coupling within the global MSHT parton distribution function (PDF) fit. Specifically, we consider ATLAS and CMS measurements of differential distributions taken at a centre-of-mass energy of 8 TeV, as well as $$ t\bar{t}$$ t t ¯ total cross section data taken at a variety of experiments, and compare to theoretical predictions including next-to-next-to-leading order corrections. We find that supplementing the global fit with this additional information results in relatively strong constraints on the top-quark mass, and is also able to bound the strong coupling in a limited fashion. Our final result is $$m_t=173.0\pm 0.6~\textrm{GeV}$$ m t = 173.0 ± 0.6 GeV and is compatible with the world average pole mass extracted from cross section measurements of $$172.5\pm 0.7~\textrm{GeV}$$ 172.5 ± 0.7 GeV by the Particle Data Group. We also study the effect of different top-quark masses on the gluon parton distribution function, finding changes at high x which nonetheless lie within the large PDF uncertainties in this region.