The LHC physics programme involves a vast amount of Monte Carlo event simulation. This paper reviews current efforts towards sharing the generated events as Open Data. Open Event Generation helps reduce duplication of effort and resource consumption, and benefits the whole High Energy Physics community. We give examples of use cases and user experiences, discuss financial and environmental savings, and suggest future directions.

These recommendations are the result of reflections by scientists and experts who are, or have been, involved in the preservation of high-energy physics data. The work has been done under the umbrella of the Data Lifecycle panel of the International Committee of Future Accelerators (ICFA), drawing on the expertise of a wide range of stakeholders. A key indicator of success in the data preservation efforts is the long-term usability of the data. Experience shows that achieving this requires providing a rich set of information in various forms, which can only be effectively collected and preserved during the period of active data use. The recommendations are intended to be actionable by the indicated actors and specific to the particle physics domain. They cover a wide range of actions, many of which are interdependent. These dependencies are indicated within the recommendations and can be used as a road map to guide implementation efforts. These recommendations are best accessed and viewed through the web application, see https://icfa-data-best-practices.app.cern.ch/

Data preservation significantly increases the scientific output of high-energy physics experiments during and after data acquisition. For new and ongoing experiments, the careful consideration of long-term data preservation in the experimental design contributes to improving computational efficiency and strengthening the scientific activity in HEP through Open Science methodologies. This contribution is based on 15 years of experience of the DPHEP collaboration in the field of data preservation and focuses on aspects relevant for the strategic programming of particle physics in Europe: the preparation of future programs using data sets preserved from previous similar experiments (e.g. HERA for EIC), and the use of LHC data long after the end of the data taking. The lessons learned from past collider experiments and recent developments open the way to a number of recommendations for the full exploitation of the investments made in large HEP experiments.

QuarkNet is a U.S. program for professional development of high school teachers. In QuarkNet, teachers deepen their understanding of physics, pedagogy, and how to engage students through the use of authentic data from a diverse set of contemporary particle physics experiments. The LHC figures prominently in these efforts. QuarkNet promotes and manages International Particle Physics Masterclasses with Fermilab-moderated videoconferences, has partnered with physicists to develop and maintain the CMS masterclass used worldwide, and has created new masterclass opportunities such as World Wide Data Day. QuarkNet makes these masterclasses available not only in the U.S. but also throughout the world. These international collaborations enrich the teachers and students involved. QuarkNet teachers also participate in LHC Data Workshops and similar opportunities. QuarkNet staff and select teachers are currently building short masterclasses and workshops for the 10th anniversary of the discovery of the Higgs.

Using a data sample of $$\sqrt{s}=13\,\text {TeV}$$ proton-proton collisions collected by the CMS experiment at the LHC in 2017 and 2018 with an integrated luminosity of $$103\text {~fb}^{-1}$$ , the $$\text {B}^{0}_{\mathrm{s}} \rightarrow \uppsi (\text {2S})\text {K}_\mathrm{S}^{0}$$ and $$\text {B}^{0} \rightarrow \uppsi (\text {2S})\text {K}_\mathrm{S}^{0} \uppi ^+\uppi ^-$$ decays are observed with significances exceeding 5 standard deviations. The resulting branching fraction ratios, measured for the first time, correspond to $${\mathcal {B}}(\text {B}^{0}_{\mathrm{s}} \rightarrow \uppsi (\text {2S})K_\mathrm{S}^{0})/{\mathcal {B}}(\text {B}^{0}\rightarrow \uppsi (\text {2S})K_\mathrm{S}^{0}) = (3.33 \pm 0.69 (\text {stat})\, \pm 0.11\,(\text {syst}) \pm 0.34\,(f_{\mathrm{s}}/f_{\mathrm{d}})) \times 10^{-2}$$ and $${\mathcal {B}}(\text {B}^{0} \rightarrow \uppsi (\text {2S})\text {K}_\mathrm{S}^{0} \uppi ^{+} \uppi ^{-})/ {\mathcal {B}}(\text {B}^{0} \rightarrow \uppsi (\text {2S})\text {K}^{0}_{\mathrm{S}}) = 0.480 \pm 0.013\,(\text {stat}) \pm 0.032\,(\text {syst})$$ , where the last uncertainty in the first ratio is related to the uncertainty in the ratio of production cross sections of $$\hbox {B}^{0}_{\mathrm{s}}$$ and $$\hbox {B}^{0}$$ mesons, $$f_{\mathrm{s}}/f_{\mathrm{d}}$$ .

A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV.

In this paper we present the latest CMS open data release published on the CERN Oopen Data portal. Samples of collision and simulated datasets were released together with detailed information about the data provenance. The associated data production chains cover the necessary computing environments, the configuration files and the computational procedures used in each data production step. We describe data curation techniques used to obtain and publish the data provenance information and we study the possibility of reproducing parts of the released data using the publicly available information. The present work demonstrates the usefulness of releasing selected samples of raw and primary data in order to fully ensure the completeness of information about the data production chain for the attention of general data scientists and other non-specialists interested in using particle physics data for education or research purposes.

The CMS Experiment at the LHC has released many large datasets of proton-proton collision data as well as simulation to the public as part of its commitment to data preservation and open access. The collision data released totals around 2 $\mathrm{fb^{-1}}$ at 7 TeV and nearly 12 $\mathrm{fb^{-1}}$ at 8 TeV. Data preservation describes the efforts to not only preserve the data itself but the conditions in which it can be analyzed. This requires archiving and documenting information such as run environment and conditions and tools such as analysis software and workflows. Open access describes the efforts to share these tools and information with the public, including educators and researchers. These efforts present many challenges, partly due to the complexity and size of the CMS datasets and also to the knowledge required to make meaningful use of them. We describe here how we dealt with these challenges and the usage of CMS open data not only in public education and engagement but also in fundamental research. Furthermore we describe plans for future releases of data.

Particle physics has an ambitious and broad experimental programme for the coming decades. This programme requires large investments in detector hardware, either to build new facilities and experiments, or to upgrade existing ones. Similarly, it requires commensurate investment in the R D of software to acquire, manage, process, and analyse the shear amounts of data to be recorded. In planning for the HL-LHC in particular, it is critical that all of the collaborating stakeholders agree on the software goals and priorities, and that the efforts complement each other. In this spirit, this white paper describes the R D activities required to prepare for this software upgrade.

In modern High Energy Physics (HEP) experiments visualization of experimental data has a key role in many activities and tasks across the whole data chain: from detector development to monitoring, from event generation to reconstruction of physics objects, from detector simulation to data analysis, and all the way to outreach and education. In this paper, the definition, status, and evolution of data visualization for HEP experiments will be presented. Suggestions for the upgrade of data visualization tools and techniques in current experiments will be outlined, along with guidelines for future experiments. This paper expands on the summary content published in the HSF \emph{Roadmap} Community White Paper~\cite{HSF-CWP-2017-01}

A cornerstone of good scientific practice is to make results available to the public. This is especially true for experiments at the LHC at CERN where public investment in fundamental research is significant and long-standing. As part of their commitment to open access and public engagement the ATLAS and CMS collaborations have made several large datasets available to the public. There are many challenges posed in presenting complex and high-level data to the public in an accessible and meaningful way. We describe the solutions to these challenges, part of which is the creation and use of the CERN Open Data Portal and the content found therein. Furthermore we describe the impact and future plans of the ATLAS and CMS open access efforts including future releases of data and accompanying educational material.

QuarkNet is an educational program which brings high school teachers and their students into the particle physics research community. The program supports research experiences and professional development workshops and provides inquiry-oriented investigations, some using real experimental data.The CMS experiment at the LHC has released several thousand proton-proton collision events for use in education and outreach. QuarkNet, in collaboration with CMS, has developed a physics masterclass and e-Lab based on this data.A masterclass is a day-long educational workshop where high school students travel to nearby universities and research laboratories. There they learn from LHC physicists about the basics of particle physics and detectors. They then perform a simple measurement using LHC data, and share their results with other students around the world via videoconference.Since 2011 thousands of students from over 25 countries have participated in the CMS masterclass as organized by QuarkNet and the International Particle Physics Outreach Group (IPPOG). We describe here the masterclass exercise: the physics, the online event display and database preparation behind it, the measurement the students undertake, their results and experiences, and future plans for the exercise.

The CMS Collaboration, in accordance with its commitment to open access and data preservation, is preparing for the public release of up to half of the reconstructed collision data collected in 2010. Efforts at present are focused on the usability of the data in education. The data will be accompanied by example applications tailored for different levels of access, including ready-to-use web-based applications for histogramming or visualising individual collision events and a virtual machine image of the CMS software environment that is compatible with these data. The virtual machine image will contain instructions for using the data with the online applications as well as examples of simple analyses. The novelty of this initiative is two-fold: in terms of open science, it lies in releasing the data in a format that is good for analysis; from an outreach perspective, it is to provide the possibility for people outside CMS to build educational applications using our public data. CMS will rely on services for data preservation and open access being prototyped at CERN with input from CMS and the other LHC experiments.

The CMS experiment, in recognition of its commitment to data preservation and open access as well as to education and outreach, has made its first public release of high-level data under the CC0 waiver: up to half of the proton-proton collision data (by volume) at 7 TeV from 2010 in CMS Analysis Object Data format. CMS has prepared, in collaboration with CERN and the other LHC experiments, an open-data web portal based on Invenio. The portal provides access to CMS public data as well as to analysis tools and documentation for the public. The tools include an event display and histogram application that run in the browser. In addition a virtual machine containing a CMS software environment along with XRootD access to the data is available. Within the virtual machine the public can analyse CMS data; example code is provided. We describe the accompanying tools and documentation and discuss the first experiences of data use.

The CMS Masterclass enables high school students to analyse authentic CMS data. Students can draw conclusions on key ratios and particle masses by combining their analyses. In particular, they can use the ratio of W+ to W− candidates to probe the structure of the proton, they can find the mass of the Z boson, and they can identify additional particles including, tentatively, the Higgs boson. In the United States, masterclasses are part of QuarkNet, a long-term program that enables students and teachers to use cosmic ray and particle physics data for learning with an emphasis on data from CMS.

Implementation of the CMS policy on long-term data preservation, re-use and open access has started. Current practices in providing data additional to published papers and distributing simplified data-samples for outreach are promoted and consolidated. The first measures have been taken for analysis and data preservation for the internal use of the collaboration and for open access to part of the data. Two complementary approaches are followed. First, a virtual machine environment, which will pack all ingredients needed to compile and run a software release with which the legacy data was reconstructed. Second, a validation framework, maintaining the capability not only to read the old raw data, but also to reprocess them with an updated release or to another format to help ensure long-term reusability of the legacy data.

We have created 3D models of the CMS detector and particle collision events in Sketch Up, a 3D modelling program. Sketch Up provides a Ruby API which we use to interface with the CMS Detector Description to create 3D models of the CMS detector. With the Ruby API, we also have created an interface to the JSON-based event format used for the iSpy event display to create 3D models of CMS events. These models have many applications related to 3D representation of the CMS detector and events. Figures produced based on these models were used in conference presentations, journal publications, technical design reports for the detector upgrades, art projects, outreach programs, and other presentations.