Searcharxiv⌕ Search

arXiv subjects

K. Khelifa-Kerfa

Publications and source records attributed to K. Khelifa-Kerfa.

10 recordsLinked to original sources
arXiv2026

$V/H$+Jet Production with the Cambridge/Aachen Algorithm

We present fixed-order perturbative calculations up to four-loop order for a generic non-global QCD observable in hadron-hadron collisions. Specifically, we study the invariant-mass distribution of the highest-$p_t$ jet produced in association with a vector boson or a Higgs boson, where jets are defined using the Cambridge/Aachen sequential recombination algorithm. This work is part of a series of papers~\cite{Khelifa-Kerfa:2015mma, Khelifa-Kerfa:2024hwx, Khelifa-Kerfa:2024dut, Khelifa-Kerfa:2025cdn, Khelifa-Kerfa:2024udm, Khelifa-Kerfa:2025jev} examining the impact of various jet algorithms on the perturbative structure of non-global observables across different collision environments. We find that at fixed order the Cambridge/Aachen algorithm suppresses the large non-global logarithms more effectively than the anti-$k_t$ and $k_t$ algorithms, while at all orders it performs comparably to the $k_t$ algorithm. Furthermore, comparisons of all-orders resummed form factors reveal that finite-$N_c$ corrections remain at the percent level, consistent with previous findings.

hep-ph↗
arXiv2026

Structure of non-global logarithms with Cambridge/Aachen clustering

We determine the structure of both Abelian and non-Abelian non-global logarithms up to four loops for $e^+e^-$ processes in perturbative QCD, where final-state jets are defined using the Cambridge--Aachen (C/A) clustering algorithm. The calculations are performed within the soft (eikonal) approximation using strong-energy ordering of the final-state partons for the case of the dijet invariant mass. The resulting expressions include full colour and complete jet-radius dependence. Compared to the anti-$k_t$ and $k_t$ clustering algorithms, the C/A distribution minimises the impact of these non-global logarithms, making it the preferred choice among the three algorithms.

hep-ph↗
arXiv2025

Analytical structure of k$_t$ clustering to any order

We present a general analytical expression for the fixed-order structure of the distribution of a generic non-global observable with the k$_t$ jet algorithm at any perturbative order. This novel formulation is obtained within the framework of the Eikonal approximation, assuming strong-energy ordering of emitted partons. The proposed formula is applicable to a wide range of processes at both lepton and hadron colliders.

hep-ph↗
arXiv2025

Hemisphere mass up to four-loops with generalised $k_t$ algorithms

We compute the fixed-order distribution of the non-global hemisphere mass observable in $e^+ e^-$ annihilation up to four loops for various sequential recombination jet algorithms. In particular, we focus on the $k_t$ and Cambridge/Aachen algorithms. Using eikonal theory and strong-energy ordering of the final-state partons, we determine the complete structure of both abelian (clustering) and non-abelian non-global logarithms through four loops in perturbation theory. We compare the resulting resummed expressions for both jet algorithms with the standard Sudakov form factor and demonstrate that neglecting these logarithms leads to unreliable phenomenological predictions for the observable's distribution.

hep-ph↗
arXiv2025

Dijet mass up to four-loops with(out) ${\boldsymbol k}_{\boldsymbol t}$ clustering

We compute the invariant mass of dijets produced in $e^+ e^-$ annihilation processes up to four loops in perturbation theory for both anti-$k_t$ and $k_t$ jet algorithms. The calculations, performed within the eikonal approximation and employing strong-energy ordering, capture the full analytic structure of the leading Abelian and non-Abelian non-global logarithms, including full colour and jet-radius dependence. We evaluate the significance of these logarithms and the convergence of the four loop perturbative expansion by comparing with all-orders numerical results.

hep-ph↗
arXiv2025

Jet-mass in V/H+jet up to four-loops with $k_t$ clustering

We extend the work of [1] to the case in which final-state jets, produced in association with a Higgs or vector boson, are defined using the $k_t$ algorithm. We thereby compute the full distribution of the invariant mass squared of the leading, highest-$p_t$ jet, including both clustering and non-global logarithms, up to four-loops in perturbation theory. Our results are derived within the eikonal approximation under the assumption of strong ordering in the momenta of the final-state partons, and are consequently valid up to single-logarithmic accuracy. The final semi-analytical expressions retain the complete dependence on both colour and the jet radius. The broad features of $k_t$ clustering observed in $e^+ e^-$ processes persist in hadronic collisions, together with novel characteristics that are absent in the $e^+ e^-$ environment.

hep-ph↗
arXiv2025

Clustering logarithms up to six loops

We compute the leading clustering (abelian non-global) logarithms, which arise in the distribution of non-global QCD observables when final-state partons are clustered using the $k_t$ jet algorithm, up to six loops in perturbation theory. Our calculations are based on the recently introduced formula for the analytic structure of $k_t$ clustering [1]. These logarithms exhibit a pattern of exponentiation and are subsequently resummed into an exponential form. We compare this resummed result with all-orders numerical calculations.

hep-ph↗
arXiv2024

Non-global logarithms up to four loops at finite-N$_c$ for V/H+jet processes at hadron colliders

We extend our previous work [1] on calculating non-global logarithms in $e^+ e^-$ annihilation to Higgs/vector boson production in association with a single hard jet at hadron colliders. We analytically compute non-global coefficients in the jet mass distribution up to four loops using the anti-k$_t$ jet algorithm. Our calculations are performed in the eikonal approximation, assuming strong energy ordering for the emitted gluons, thus capturing only the leading logarithms of the distribution. We compare our analytical results with the all-orders large-N$_c$ numerical solution. In general, the gross features of the non-global logarithm distribution observed in the $e^+ e^-$ case remain valid for the V/H+jet processes.

hep-ph↗
arXiv2022

Jet shapes in H/V boson + jet with $k_t$ clustering at hadron colliders

We present analytical calculations of the distribution of non-global jet shapes in Higgs/vector boson + jet production at hadron colliders. Within the eikonal-limit framework and implementing various jet algorithms, we compute the full distribution of the particular jet mass shape observable at 2-loops, including the large single-logarithms known as non-global logs and clustering logs. We compare our next-to-leading-log analytical resummation to parton showers and, after matching and including non-perturbative effects, to experimental data. A good agreement is shown for all comparisons.

hep-ph↗