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Petr Jakubčík

Publications and source records attributed to Petr Jakubčík.

10 recordsLinked to original sources
arXiv2026

All three-loop four-point massless integrals with one off-shell leg

We present the complete set of massless three-loop four-point master integrals with one off-shell external leg. These are essential building blocks for the three-loop virtual corrections to Higgs-boson or vector-boson production in association with a jet at the Large Hadron Collider, required for next-to-next-to-next-to-leading-order QCD predictions. We construct a complete basis of canonical integrals by identifying integrands with simple poles and unit leading singularities, solely by integrand analysis. This includes an integral family with 371 master integrals and a 19-dimensional top sector. The solutions for all relevant integrals are provided as a map to a minimal set of iterated integrals graded according to their analytic properties, together with high-precision series expansions.

hep-ph↗
arXiv2025

Jet production at electron-positron colliders at next-to-next-to-next-to-leading order in QCD

We present the first application of antenna subtraction at next-to-next-to-next-to-leading order (N$^3$LO) in QCD by computing fully differential predictions for two-jet production at electron-positron colliders. We illustrate the structure of the infrared counterterms and provide results for the N$^3$LO correction to the two-jet production rate and to the leading-jet energy. Our work constitutes the first direct calculation of jet production at electron-positron colliders at N$^3$LO and represents the first step in tackling arbitrary processes with jets at this perturbative order.

hep-ph↗
arXiv2024

Graded transcendental functions: an application to four-point amplitudes with one off-shell leg

Several recent works have demonstrated the powerful algebraic simplifications that can be achieved for scattering amplitudes through a systematic grading of transcendental quantities. We develop these concepts to construct a minimal basis of functions tailored to a scattering amplitude in a general way. Starting with formal solutions for all master integral topologies, we organise the appearing functions by properties such as their symbol alphabet or letter adjacency. We rotate the basis such that functions with spurious features appear in the least possible number of basis elements. Since their coefficients must vanish for physical quantities, this approach avoids complex cancellations. As a first application, we evaluate all integral topologies relevant to the three-loop $Hggg$ and $Hgq\bar{q}$ amplitudes in the leading-colour approximation and heavy-top limit. We describe the derivation of canonical differential equation systems and present a method for fixing boundary conditions without the need for a full functional representation. Using multiple numerical reductions, we test the maximal transcendentality conjecture for $Hggg$ and identify a new letter which appears in functions of weight 4 and 5. In addition, we provide the first direct analytic computation of a three-point form factor of the operator $\mathrm{Tr}(ϕ^2)$ in planar $\mathcal{N}=4$ sYM and find agreement with numerical and bootstrapped results.

hep-th↗
arXiv2024

Antenna subtraction for final-state radiation at N$^3$LO

I review some aspects of antenna subtraction at next-to-next-to-leading order (NNLO) in QCD and provide motivation for its extension to N$^3$LO. Next, I introduce the antenna functions required for the construction of infrared counterterms for final-state radiation at this order. Lastly, I describe the evaluation of the antenna functions and their phase-space integration, first presented in [1-3], and I elaborate on their application to precision observables in jet production at lepton colliders.

hep-ph↗
arXiv2023

Planar three-loop QCD helicity amplitudes for $V$+jet production at hadron colliders

We compute the planar three-loop Quantum Chromodynamics (QCD) corrections to the helicity amplitudes involving a vector boson $V=Z,W^\pm,γ^*$, two quarks and a gluon. These amplitudes are relevant to vector-boson-plus-jet production at hadron colliders and other precision QCD observables. The planar corrections encompass the leading colour factors $N^3$, $N^2 N_f$, $N N_f^2$ and $N_f^3$. We provide the finite remainders of the independent helicity amplitudes in terms of multiple polylogrithms, continued to all kinematic regions and in a form which is compact and lends itself to efficient numerical evaluation.

hep-ph↗
arXiv2023

Two-loop helicity amplitudes for $H+$jet production to higher orders in the dimensional regulator

In view of the forthcoming High-Luminosity phase of the LHC, next-to-next-to-next-to-leading (N$^3$LO) calculations for the most phenomenologically relevant processes become necessary. In this work, we take the first step towards this goal for H$+$jet production by computing the one- and two-loop helicity amplitudes for the two contributing processes, $H\to ggg$, $H\to q\bar{q}g$, in an effective theory with infinite top quark mass, to higher orders in the dimensional regulator. We decompose the amplitude in scalar form factors related to the helicity amplitudes and in a new basis of tensorial structures. The form factors receive contributions from Feynman integrals which were reduced to a novel canonical basis of master integrals. We derive and solve a set of differential equations for these integrals in terms of Multiple Polylogarithms (MPLs) of two variables up to transcendental weight six.

hep-ph↗
arXiv2023

Radiation from a gluon-gluino colour-singlet dipole at N$^3$LO

We compute the quantum chromodynamics (QCD) corrections to the decay of a neutralino to gluinos and partons at next-to-next-to-next-to-leading order (N$^3$LO) in the strong coupling constant $α_s$, integrated separately over the phase-space of two, three, four or five particles in the final state. The resulting matrix elements are related to the quark-gluon antenna functions, completing the set of integrated antenna functions in final-final kinematics required for the extension of the antenna subtraction scheme to N$^3$LO. For a model with massless partons (quarks and gluons) and an arbitrary number of adjoint fermions, we obtained the following new results to $\mathcal{O}(α_s^3)$: the inclusive cross section for the decay of a neutralino, the renormalization of the effective coupling of a neutralino to a gluino and gluon(s), the gluino collinear anomalous dimension, the gluino contribution to the parton collinear anomalous dimensions and the neutralino-gluino-gluon(s) vertex form factors. A special case of this model is the $\mathcal{N}=1$ super Yang-Mills theory, where we can relate some of our findings to known results.

hep-ph↗
arXiv2023

The parton-level structure of Higgs decays to hadrons at N$^3$LO

We present the quantum chromodynamics (QCD) corrections for Higgs boson decays to hadronic final states at next-to-next-to-next-to-leading order (N$^3$LO) in the strong coupling constant $α_s$. In particular, we consider the Higgs boson decay to massless bottom quarks and the Higgs boson decay to a pair of gluons in the limit of a heavy top quark. The tree-level five-parton, the one-loop four-parton, the two-loop three-parton, and the three-loop two-parton matrix elements are integrated separately over the inclusive phase space and classified by partons appearing in the final state and by colour structure. As a check, we reproduce known results for the hadronic $R$-ratios at N$^3$LO. We study patterns of infrared singularity cancellation within the colour layers of the integrated expressions and observe an agreement in the highest trascendental weight terms in the decay of different colour singlets to quarks. We anticipate that our result will be an essential ingredient for the formulation of N$^3$LO subtraction schemes.

hep-ph↗
arXiv2023

Two-loop helicity amplitudes for $V+$jet production including axial vector couplings to higher orders in $ε$

We compute the two-loop Quantum Chromodynamics (QCD) corrections to all partonic channels relevant for the production of an electroweak boson $V=Z,W^\pm,γ^*$ and a jet at hadron colliders. We consider the decay of a vector boson $V$ to three partons $ V \to q\bar{q}g$, $ V \to ggg$ with a vector and axial vector coupling in both channels, including singlet and non-singlet contributions. For the quark channel, we use a recent tensor decomposition and extend the calculation to $\mathcal{O}(ε^2)$. For the gluonic channel, we define a new tensor decomposition which allows us to compute the vector and the axial vector amplitudes at once and to perform the computation of the amplitudes to $\mathcal{O}(ε^2)$. We provide finite remainders of the helicity amplitudes analytically continued to all relevant scattering regions $q\bar{q} \to V g$, $q g \to V q$ and $gg \to V g$. The axial vector contribution to the gluon-induced channel completes the set of two-loop amplitudes for this process, while the extension to $\mathcal{O}(ε^2)$ represents the first step in the calculation of next-to-next-to-next-to-leading-order (N$^3$LO) QCD corrections to $Z$+jet production at hadron colliders.

hep-ph↗
arXiv2023

The parton-level structure of $e^+e^-$ to 2 jets at N$^3$LO

We investigate the quantum chromodynamics (QCD) corrections to hadronic final states in electron-positron collisions at $\mathcal{O}(α_s^3)$ in the strong coupling constant $α_s$. Namely, we analytically compute the total cross section for this process by separately integrating the tree-level five-parton, the one-loop four-parton, the two-loop three-parton, and the three-loop two-parton matrix elements over the respective phase space. All the contributions to the calculation are treated in a common framework whereby phase space integrals are expressed as physical cuts of the four-loop two-point function. We check the cancellation of infrared poles at all colour levels and we reproduce the known result for the $R$-ratio at order $α_s^3$.

hep-ph↗