A collinear shower algorithm for NSL non-singlet fragmentation
Journal of High Energy Physics Springer 2025:3 (2025) 209
Abstract:
We formulate a collinear partonic shower algorithm that achieves next-to-single-logarithmic (NSL, αsnLn−1) accuracy for collinear-sensitive non-singlet fragmentation observables. This entails the development of an algorithm for nesting triple-collinear splitting functions. It also involves the inclusion of the one-loop double-collinear corrections, through a z-dependent NLO-accurate effective 1 → 2 branching probability, using a formula that can be applied more generally also to future full showers with 1 → 3 splitting kernels. The specific NLO branching probability is calculated in two ways, one based on slicing, the other using a subtraction approach based on recent analytical calculations. We close with demonstrations of the shower’s accuracy for non-singlet partonic fragmentation functions and the energy spectrum of small-R quark jets. This work represents an important conceptual step towards general NNLL accuracy in parton showers.Investigating the universality of five-point QCD scattering amplitudes at high energy
Journal of High Energy Physics Springer 2025:3 (2025) 129
Abstract:
We investigate 2 → 3 QCD scattering amplitudes in multi-Regge kinematics, i.e. where the final partons are strongly ordered in rapidity. In this regime amplitudes exhibit intriguing factorisation properties which can be understood in terms of effective degrees of freedom called reggeons. Working within the Balitsky/JIMWLK framework, we predict these amplitudes for the first time to next-to-next-to-leading logarithmic order, and compare against the limit of QCD scattering amplitudes in full colour and kinematics. We find that the latter can be described in terms of universal objects, and that the apparent non-universality arising at NNLL comes from well-defined and under-control contributions that we can predict. Thanks to this observation, we extract for the first time the universal vertex that controls the emission of the central-rapidity gluon, both in QCD and N = 4 super Yang-Mills.Observation of Cosmic-Ray Anisotropy in the Southern Hemisphere with 12 yr of Data Collected by the IceCube Neutrino Observatory
The Astrophysical Journal American Astronomical Society 981:2 (2025) 182
Search for Neutrino Emission from Hard X-Ray AGN with IceCube
The Astrophysical Journal American Astronomical Society 981:2 (2025) 131
Search for Neutrino Doublets and Triplets Using 11.4 yr of IceCube Data
The Astrophysical Journal American Astronomical Society 981:2 (2025) 159