# Publications by Luca Rottoli

## Maximal Entanglement in High Energy Physics

SciPost Physics Stichting SciPost **3** (0) 036

<jats:p>We analyze how maximal entanglement is generated at the fundamental level in QED by studying correlations between helicity states in tree-level scattering processes at high energy. We demonstrate that two mechanisms for the generation of maximal entanglement are at work: <jats:italic>i)</jats:italic><jats:inline-formula><jats:alternatives><jats:tex-math>s</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>s</mml:mi></mml:math></jats:alternatives></jats:inline-formula>-channel processes where the virtual photon carries equal overlaps of the helicities of the final state particles, and <jats:italic>ii)</jats:italic> the indistinguishable superposition between <jats:inline-formula><jats:alternatives><jats:tex-math>t</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>t</mml:mi></mml:math></jats:alternatives></jats:inline-formula>- and <jats:inline-formula><jats:alternatives><jats:tex-math>u</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>u</mml:mi></mml:math></jats:alternatives></jats:inline-formula>-channels. We then study whether <jats:italic>requiring</jats:italic> maximal entanglement constrains the coupling structure of QED and the weak interactions. In the case of photon-electron interactions unconstrained by gauge symmetry, we show how this requirement allows to reproduce QED. For <jats:inline-formula><jats:alternatives><jats:tex-math>Z</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Z</mml:mi></mml:math></jats:alternatives></jats:inline-formula>-mediated weak scattering, the maximal entanglement principle leads to non-trivial predictions for the value of the weak mixing angle <jats:inline-formula><jats:alternatives><jats:tex-math>\theta_W</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>θ</mml:mi><mml:mi>W</mml:mi></mml:msub></mml:math></jats:alternatives></jats:inline-formula>. Our results are a first step towards understanding the connections between maximal entanglement and the fundamental symmetries of high-energy physics.</jats:p>

## Three loop soft function for N3LL′ gluon fusion Higgs boson production in soft-collinear effective theory

Physical Review D American Physical Society **91** (2015) 1-6

We derive the three loop soft function for inclusive Higgs production in gluon fusion, and use it to perform the resummation of the Higgs cross section at N3LL′ in soft-collinear effective theory. We improve the accuracy of the resummation by including contributions of collinear origin. We include finite top, bottom and charm mass effect where available. These results are available through the public code ResHiggs.

## Resummation prescriptions and ambiguities in SCET vs. direct QCD: Higgs production as a case study

Journal of High Energy Physics Springer **46** (2015) 1-23

We perform a comparison of soft-gluon resummation in SCET vs. direct QCD (dQCD), using Higgs boson production in gluon fusion as a case study, with the goal of tracing the quantitative impact of each source of difference between the two approaches. We show that saddle-point methods enable a direct quantitative comparison despite the fact that the scale which is resummed in the two approaches is not the same. As a byproduct, we put in one-to-one analytic correspondence various features of either approach: specifically, we show how the SCET method for treating the Landau pole can be implemented in dQCD, and how the resummation of the optimal partonic scale of dQCD can be implemented in SCET. We conclude that the main quantitative difference comes from power-suppressed subleading contributions, which could in fact be freely tuned in either approach, and not really characteristic of either. This conclusion holds for Higgs production in gluon fusion, but it is in fact generic for processes with similar kinematics. For Higgs production, everything else being equal, SCET resummation at NNLL in the Becher-Neubert implementation leads to essentially no enhancement of the NNLO cross-section, unlike dQCD in the standard implementation of Catani et al.

## Parton distributions with threshold resummation

Journal of High Energy Physics Springer **2015** (2015) 1-45

We construct a set of parton distribution functions (PDFs) in which fixed-order NLO and NNLO calculations are supplemented with soft-gluon (threshold) resummation up to NLL and NNLL accuracy respectively, suitable for use in conjunction with any QCD calculation in which threshold resummation is included at the level of partonic cross sections. These resummed PDF sets, based on the NNPDF3.0 analysis, are extracted from deep-inelastic scattering, Drell-Yan, and top quark pair production data, for which resummed calculations can be consistently used. We find that, close to threshold, the inclusion of resummed PDFs can partially compensate the enhancement in resummed matrix elements, leading to resummed hadronic cross-sections closer to the fixed-order calculations. On the other hand, far from threshold, resummed PDFs reduce to their fixed-order counterparts. Our results demonstrate the need for a consistent use of resummed PDFs in resummed calculations.

## Les Houches 2017: Physics at TeV Colliders Standard Model Working Group Report

ArXiv (0)

This Report summarizes the proceedings of the 2017 Les Houches workshop on Physics at TeV Colliders. Session 1 dealt with (I) new developments relevant for high precision Standard Model calculations, (II) theoretical uncertainties and dataset dependence of parton distribution functions, (III) new developments in jet substructure techniques, (IV) issues in the theoretical description of the production of Standard Model Higgs bosons and how to relate experimental measurements, (V) phenomenological studies essential for comparing LHC data from Run II with theoretical predictions and projections for future measurements, and (VI) new developments in Monte Carlo event generators.

## Higgs transverse momentum with a jet veto: a double-differential resummation

ArXiv (0)

We consider the simultaneous measurement of the Higgs ($p_t^{\tiny{\mbox{H}}}$) and the leading jet ($p_t^{\tiny{\mbox{J}}}$) transverse momentum in hadronic Higgs-boson production, and perform the resummation of the large logarithmic corrections that originate in the limit $p_t^{\tiny{\mbox{H}}}\,,p_t^{\tiny{\mbox{J}}} \ll m_{\tiny{\mbox{H}}}$ up to next-to-next-to-leading-logarithmic order. This work constitutes the first resummation for a double-differential observable involving a jet algorithm in hadronic collisions, and provides an important milestone in the theoretical understanding of joint resummations. As an application, we provide precise predictions for the Higgs transverse-momentum distribution with a veto $p_t^{\tiny{\mbox{J}}} \leq p_{t}^{\tiny{\mbox{J,v}}}$ on the accompanying jets, whose accurate description is relevant to the Higgs precision programme at the Large Hadron Collider.

## Threshold resummation in SCET vs. direct QCD: a systematic comparison

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We perform a systematic comparison of soft-gluon resummation in SCET and in a standard "direct" QCD (dQCD) approach, both from an analytical and a phenomenological point of view. In particular, we concentrate on Higgs boson production in gluon-gluon fusion at a hadron collider. Using specifically a saddle point argument, we arrive at a detailed understanding of the quantitative differences between these two approaches.