17 research outputs found
Double collinear splitting amplitudes at next-to-leading order
We compute the next-to-leading order (NLO) QCD corrections to the 1 -> 2 splitting amplitudes in different dimensional regularization (DREG) schemes. Besides recovering previously known results, we explore new DREG schemes and analyze their consistency by comparing the divergent structure with the expected behavior predicted by Catani's formula. Through the introduction of scalar-gluons, we show the relation among splittings matrices computed using different schemes. Also, we extended this analysis to cover the double collinear limit of scattering amplitudes in the context of QCD+QED
Hadron plus photon production in polarized hadronic collisions at next-to-leading order accuracy
We compute the next-to-leading order QCD corrections to the polarized (and
unpolarized) cross sections for the production of a hadron accompanied by an
opposite-side prompt photon. This process, being studied at RHIC, permits us to
reconstruct partonic kinematics using experimentally measurable variables. We
study the correlation between the reconstructed momentum fractions and the true
partonic ones, which in the polarized case might allow us to reveal the
spin-dependent gluon distribution with a higher precision.Comment: 18 figures included. New version, discussion about polarized
asymmetries extended, 7 new figures, new reference
From five-loop scattering amplitudes to open trees with the Loop-Tree Duality
Characterizing multiloop topologies is an important step towards developing
novel methods at high perturbative orders in quantum field theory. In this
article, we exploit the Loop-Tree Duality (LTD) formalism to analyse multiloop
topologies that appear for the first time at five loops. Explicitly, we open
the loops into connected trees and group them according to their topological
properties. Then, we identify a kernel generator, the so-called NMLT
universal topology, that allow us to describe any scattering amplitude of up to
five loops. Furthermore, we provide factorization and recursion relations that
enable us to write these multiloop topologies in terms of simpler
subtopologies, including several subsets of Feynman diagrams with an arbitrary
number of loops. Our approach takes advantage of many symmetries present in the
graphical description of the original fundamental five-loop topologies. The
results obtained in this article might shed light into a more efficient
determination of higher-order corrections to the running couplings, which are
crucial in the current and future precision physics program.Comment: 14 pages, 6 figures, 2 table
Polarized triple-collinear splitting functions at NLO for processes with photons
We compute the polarized splitting functions in the triple collinear limit at next-to-leading order accuracy (NLO) in the strong coupling alpha(S), for the splitting processes gamma -> qq gamma, gamma -> qqg and g -> qq gamma. The divergent structure of each splitting function was compared to the predicted behaviour according to Catani's formula. The results obtained in this paper are compatible with the unpolarized splitting functions computed in a previous article. Explicit results for NLO corrections are presented in the context of conventional dimensional regularization (CDR)
Variational quantum eigensolver for causal loop Feynman diagrams and acyclic directed graphs
We present a variational quantum eigensolver (VQE) algorithm for the
efficient bootstrapping of the causal representation of multiloop Feynman
diagrams in the Loop-Tree Duality (LTD) or, equivalently, the selection of
acyclic configurations in directed graphs. A loop Hamiltonian based on the
adjacency matrix describing a multiloop topology, and whose different energy
levels correspond to the number of cycles, is minimized by VQE to identify the
causal or acyclic configurations. The algorithm has been adapted to select
multiple degenerated minima and thus achieves higher detection rates. A
performance comparison with a Grover's based algorithm is discussed in detail.
The VQE approach requires, in general, fewer qubits and shorter circuits for
its implementation, albeit with lesser success rates.Comment: 32 pages, 7 figures. Improved discussion and success rates of
multi-run VQ
Triple collinear splitting functions at NLO for scattering processes with photons
We present splitting functions in the triple collinear limit at next-to-leading order. The computation was performed in the context of massless QCD+QED, considering only processes which include at least one photon. Through the comparison of the IR divergent structure of splitting amplitudes with the expected known behavior, we were able to check our results. Besides that we implemented some consistency checks based on symmetry arguments and cross-checked the results among them. Studying photon-started processes, we obtained very compact results
Triple-collinear splittings with massive particles
Abstract We analyze in detail the most singular behaviour of processes involving triple-collinear splittings with massive particles in the quasi-collinear limit, and present compact expressions for the splitting amplitudes and the corresponding splitting kernels at the squared-amplitude level. Our expressions fully agree with well-known triple-collinear splittings in the massless limit, which are used as a guide to achieve the final expressions. These results are important to quantify dominant mass effects in many observables, and constitute an essential ingredient of current high-precision computational frameworks for collider phenomenology