Mikhail Mikhasenko
Mikhail Mikhasenko is a professor of experimental particle physics at Ruhr University Bochum and a member of the LHCb and COMPASS collaborations. His research focuses on hadron spectroscopy, with particular expertise in amplitude analysis and the study of exotic multiquark states.
He develops open scientific software and analysis tools for the computational and phenomenological study of exclusive hadronic processes, including methods for amplitude analysis and partial-wave modeling. A Julia user for about a decade.
Session
The spectroscopy of exotic hadrons enables probing the dynamics of the strong interaction beyond the conventional quark–antiquark and three–quark picture. Measurements at the LHCb experiment revealed the doubly charmed tetraquark Tcc⁺ and provided new high-precision data relevant for understanding the structure of the X(3872). Interpreting such near-threshold systems requires accurate modeling of threshold effects, multi-body dynamics, and technically advanced statistical inference.
We present a Julia-based analysis ecosystem developed for studies of these states using LHCb data. The workflow combines established Julia packages for statistical modeling and minimization with specialized tools tailored for hadron spectroscopy. Core functionality relies on packages such as Distributions.jl, NumericalDistributions.jl and Minuit2.jl, extended by domain-specific probability distributions implemented in DistributionsHEP.jl.
Several dedicated physics packages provide modular building blocks for amplitude models and line-shape calculations. These include X3872Flatte.jl, X3872ThreeBodyLineshape.jl, and xDDPhaseSpace.jl, implementing threshold line shapes, three-body kinematics, and phase-space constructions relevant for near-threshold charm systems. Complete analyses are developed in separate private repositories operating on collaboration-internal data and likelihood models; the software is released publicly once the corresponding analyses are published.
A key component of the workflow is BuildConstructors.jl, a framework providing long-awaited granular control over complex fitting strategies. It enables structured construction of likelihood fits with systematic parameter management, including controlled fixing and releasing of parameters during iterative block likelihood fits.
Together these packages support complex spectroscopy analyses while extending the Julia ecosystem with tools for amplitude modeling and likelihood-based inference. They simplify the development of advanced analysis strategies and make Julia more accessible for future analyses in experimental particle physics.