Publications

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PMC$_\infty$: Infinite-Order Scale-Setting method using the Principle of Maximum Conformality and preserving the Intrinsic Conformality

Leonardo Di Giustino, Stanley J. Brodsky, Xing-Gang Wu, Sheng-Quan Wang

SciPost Phys. Proc. 7, 038 (2022) · published 21 June 2022 | · pdf

We show results for Thrust and C-parameter in $e^+ e^-$ annihilation to 3 jets obtained using the recently developed new method for eliminating the scale ambiguity and the scheme dependence in pQCD namely the Infinite-Order Scale-Setting method using the Principle of Maximum Conformality (PMC$_\infty$). This method preserves an important underlying property of gauge theories: intrinsic Conformality (iCF). It leads to a remarkably efficient method to eliminate the conventional renormalization scale ambiguity at any order in pQCD. A comparison with Conventional Scale Setting method (CSS) is also shown.
Recent progress on two-loop massless pentabox integrals with one off-shell leg

D. Canko, A. Kardos, C. G. Papadopoulos, A. V Smirnov, N. Syrrakos, C. Wever

SciPost Phys. Proc. 7, 037 (2022) · published 21 June 2022 | · pdf

Analytic expressions in terms of polylogarithmic functions for all three families of planar two-loop five-point Master Integrals with one off-shell leg are presented. The Simplified Differential Equations approach is the only known way to fulfil this task due to its unique factorisation property of the symbols of the canonical differential equation. The results are relevant to the study of many $2\to 3$ scattering processes of interest at the LHC.
Two-Loop renormalization of High-Dimensional QCD operators and Higgs EFT amplitudes

Qingjun Jin, Ke Ren, Gang Yang, Rui Yu

SciPost Phys. Proc. 7, 036 (2022) · published 21 June 2022 | · pdf

We consider two-loop renormalization of high-dimensional operators in QCD and the relevant Higgs EFT amplitudes. Efficient unitarity-IBP strategy is used to compute the two-loop minimal form factors of length-3 operators up to dimension sixteen. From the ultraviolet divergences of form factor results, we extract the renormalization matrices and compute anomalous dimensions. We also obtain the analytic finite remainder functions which exhibit several universal transcendentality structures. The form factors we compute are equivalent to Higgs plus three-gluon amplitudes that capture high-order top mass corrections in Higgs effective field theory.
W+c-jet production at the LHC with NNLO QCD accuracy

Michal Czakon, Alexander Mitov, Mathieu Pellen, Rene Poncelet

SciPost Phys. Proc. 7, 035 (2022) · published 21 June 2022 | · pdf

In these proceedings, we highlight some aspects of the recent computation of NNLO QCD corrections for W production in association with a charm jet at the LHC. The results are presented in the form of cross sections and differential distributions and are compared to ATLAS data.
Applications of the Perturbative Gradient Flow

Fabian Lange

SciPost Phys. Proc. 7, 033 (2022) · published 21 June 2022 | · pdf

Over the last decade the gradient flow formalism became an important tool for lattice simulations of Quantum Chromodynamics. It offers remarkable renormalization properties which pave the way for cross-fertilization between perturbative and lattice calculations. In this contribution we discuss the perturbative approach. As first application we compute vacuum expectation values of flowed operators which could help to extract parameters like the strong coupling constant from lattice simulations. Afterwards, we apply the flowed operator product expansion to the time-ordered product of two currents which could be employed for an alternative first-principle evaluation of vacuum polarization functions on the lattice.
Top quark mass corrections to single and double Higgs boson production in gluon fusion

Joshua Davies

SciPost Phys. Proc. 7, 031 (2022) · published 21 June 2022 | · pdf

In this talk we discuss recent computations of the top quark mass dependence of QCD amplitudes describing Higgs boson production in gluon fusion. We compute terms in the expansion for a large top quark mass, which reduces the Feynman diagrams to products of massless integrals and massive tadpole integrals which contain the top mass dependence. In particular we discuss the real and virtual corrections to double Higgs production at NNLO, and the virtual corrections to single Higgs production at N3LO.
Multiscale pentagon integrals to all orders

Dhimiter D. Canko, Costas G. Papadopoulos, Nikolaos Syrrakos

SciPost Phys. Proc. 7, 030 (2022) · published 21 June 2022 | · pdf

We present analytical results for one-loop five-point master integrals with up to three off-shell legs. The method of canonical differential equations along with the Simplified Differential Equations approach is employed. All necessary boundary terms are given in closed form, resulting to solutions in terms of Goncharov Polylogarithms of arbitrary weight. Explicit results up to weight six will be presented.
Cover your bases: asymptotic distributions of the profile likelihood ratio when constraining effective field theories in high-energy physics

Florian Urs Bernlochner, Daniel C. Fry, Stephen Burns Menary, Eric Persson

SciPost Phys. Core 6, 013 (2023) · published 16 March 2023 | · pdf

We investigate the asymptotic distribution of the profile likelihood ratio (PLR) when constraining effective field theories (EFTs) and show that Wilks' theorem is often violated, meaning that we should not assume the PLR to follow a $\chi^2$-distribution. We derive the correct asymptotic distributions when either one or two real EFT couplings modulate observable cross sections with a purely linear or quadratic dependence. We then discover that when both the linear and quadratic terms contribute, the PLR distribution does not have a simple form. In this case we provide a partly-numerical solution for the one-parameter case. Using a novel approach, we find that the constants which define our asymptotic distributions may be obtained experimentally using a profile of the Asimov likelihood contour. Our results may be immediately used to obtain the correct coverage when deriving real-world EFT constraints using the PLR as a test-statistic.
Probing a leptophobic top-colour model with cross section measurements and precise signal and background predictions: A case study

Mohammad Mahdi Altakach, Jonathan Mark Butterworth, Tomáš Ježo, Michael Klasen, Ingo Schienbein

SciPost Phys. Core 6, 014 (2023) · published 17 March 2023 | · pdf

The sensitivity of particle-level fiducial cross section measurements from ATLAS, CMS and LHCb to a leptophobic top-colour model is studied. The model has previously been the subject of resonance searches. Here we compare it directly to state-of-the-art predictions for Standard Model top quark production and also take into account next-to-leading order predictions for the new physics signal. We make use of the Contur framework to evaluate the sensitivity of the current measurements, first under the default Contur assumption that the measurement and the SM exactly coincide, and then using the full SM theory calculation for $t\bar{t}$ at next-to-leading and next-to-next-to-leading order as the background model. We derive exclusion limits, discuss the differences between these approaches, and compare to the limits from resonance searches by ATLAS and CMS.
$N^3LO$ calculations for $2 \to 2$ processes using simplified differential equations

Dhimiter D. Canko, Federico Gasparotto, Luca Mattiazzi, Costas G. Papadopoulos, Nikolaos Syrrakos

SciPost Phys. Proc. 7, 028 (2022) · published 21 June 2022 | · pdf

We present the computation of the massless three-loop ladder-box family with one external off-shell leg using the Simplified Differential Equations (SDE) approach. We also discuss the methods we used for finding a canonical differential equation for the two tennis-court families with one off-shell leg, and the application of the SDE approach on these two families.

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