Renormalisation-group evolution enters PDF determinations through the running coupling and the splitting functions. At fixed perturbative order, the solution of the evolution equations is not unique beyond the nominal accuracy, and this residual freedom can be probed through resummation-scale variations. This contribution summarises an NNLO study of this effect in inclusive HERA DIS fits performed with the xFitter fitting framework. The induced shifts are sizeable in a low-scale baseline fit, especially for the gluon and sea PDFs, and can affect LHC and FCC top-quark pair predictions at the few-percent level. Raising the PDF starting scale and applying a higher DIS virtuality cut considerably reduces the effect, a conclusion also supported by treating the resummation scale as a free parameter constrained directly by the data.
We investigate the impact of resummation-scale variations on parton distribution function (PDF) determinations. These variations introduce an additional source of theoretical uncertainty related to the evolution of PDFs and strong coupling $\alpha_s$ that has never previously been accounted for in PDF fits. Using the o...
H. Abdolmaleki, Valerio Bertone, G. Bozzi et al.· 0 citations
We analyze Higgs production at the LHC with a jet veto at central rapidities and present the first next-to-leading logarithmic resummation of non-global logarithms for this process. The resummation combines one-loop hard and soft matching functions with two-loop anomalous dimensions in the large-$N_c$ limit. To perform...
T. Becher, Rebecca von Kuk, Xin-Yu Qin et al.· 0 citations
To make full use of the HL-LHC, especially in the search for BSM physics, all Standard Model backgrounds have to be understood with increased precision. This is especially difficult for Double Parton Interactions (DPIs) and more generally Multi Parton Interactions (MPIs), which are very difficult to isolate precisely i...
Daniel Reitinger, C. Zimmermann, A. Schäfer· 0 citations
We present an overview of the MSHT family of global PDF fits. We describe the underlying methodology, including parameterisation choice, theoretical inputs and datasets included in the fit. We describe the impact of recent theoretical advances in the inclusion of higher order QCD and EW corrections on the fit and their...
T. Cridge, L. A. Harland-Lang, M. Reader et al.· Physics reports· 0 citations
Generalized Parton Distributions (GPDs) encode the three-dimensional structure of hadrons, yet their modification in nuclear matter remains largely unconstrained. We report the first derivation of resummed QCD power corrections to deeply virtual Compton scattering on nuclei. Extending techniques from inclusive deep ine...
We address the breakdown of fixed-order perturbation theory due to logarithms in $s/p_t^2$ for processes involving two jets or more at the energies currently explored at the LHC. The problem manifests itself in various ways: an obvious breakdown of the perturbative series for some kinematic distributions, highly asymme...
Jeppe R. Andersen, Sebastian Jaskiewicz, A. Maier et al.· 0 citations
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