ROOT has use particle physics
ROOT is an object-oriented computer program and library developed by CERN. It was originally designed for particle physics data analysis and contains several features specific to the field, but it is also used in other applications such as astronomy and data mining.  The latest minor release is 6.28, as of 2023-02-03.Histogramming and graphing to view and analyze distributions and functions,
curve fitting (regression analysis) and minimization of functionals,
statistics tools used for data analysis,
matrix algebra,
four-vector computations, as used in high energy physics,
standard mathematical functions,
multivariate data analysis, e.g. using neural networks,
image manipulation, used, for instance, to analyze astronomical pictures,
access to distributed data (in the context of the Grid),
distributed computing, to parallelize data analyses,
persistence and serialization of objects, which can cope with changes in class definitions of persistent data,
access to databases,
3D visualizations (geometry),
creating files in various graphics formats, like PDF, PostScript, PNG, SVG, LaTeX, etc.
interfacing Python code in both directions,
interfacing Monte Carlo event generators.A key feature of ROOT is a data container called tree, with its substructures branches and leaves. A tree can be seen as a sliding window to the raw data, as stored in a file. Data from the next entry in the file can be retrieved by advancing the index in the tree. This avoids memory allocation problems associated with object creation, and allows the tree to act as a lightweight container while handling buffering invisibly.
ROOT is designed for high computing efficiency, as it is required to process data from the Large Hadron Collider's experiments estimated at several petabytes per year. As of 2009 ROOT is mainly used in data analysis and data acquisition in particle physics (high energy physics) experiments, and most current experimental plots and results in those subfields are obtained using ROOT.
The inclusion of a C++ interpreter (CINT until version 5.34, Cling from version 6.00) makes this package very versatile as it can be used in interactive, scripted and compiled modes in a manner similar to commercial products like MATLAB.
On July 4, 2012 the ATLAS and CMS LHC's experiments presented  the status of the Standard Model Higgs search. All data plotting presented that day used ROOT.