International Linear Collider
Not a member yet
509047 research outputs found
Sort by
Search for vector-like leptons with long-lived particle decays in the CMS muon system in proton-proton collisions at 13 TeV
No full textA first search is presented for vector-like leptons (VLLs) decaying into a light long-lived pseudoscalar boson and a standard model lepton. The pseudoscalar boson is assumed to have a mass of 2 GeV and to decay exclusively into a pair of photons. It is identified using the CMS muon system. The analysis is carried out using a data set of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment in 2016--2018, corresponding to an integrated luminosity of 138 fb. Selected events contain at least one pseudoscalar boson decaying electromagnetically in the muon system and at least one hadronically decaying lepton. No significant excess of data events is observed compared to the background expectation. Upper limits are set at 95% confidence level on the vector-like lepton production cross section as a function of the VLL mass and the pseudoscalar boson mean proper decay length. The observed and expected exclusion ranges of the VLL mass extend up to 700 and 670 GeV, respectively, depending on the pseudoscalar boson lifetime.A first search is presented for vector-like leptons (VLLs) decaying into a light long-lived pseudoscalar boson and a standard model lepton. The pseudoscalar boson is assumed to have a mass of 2 GeV and to decay exclusively into a pair of photons. It is identified using the CMS muon system. The analysis is carried out using a data set of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment in 2016-2018, corresponding to an integrated luminosity of 138 fb. Selected events contain at least one pseudoscalar boson decaying electromagnetically in the muon system and at least one hadronically decaying lepton. No significant excess of data events is observed compared to the background expectation. Upper limits are set at 95% confidence level on the vector-like lepton production cross section as a function of the VLL mass and the pseudoscalar boson mean proper decay length. The observed and expected exclusion ranges of the VLL mass extend up to 700 and 670 GeV, respectively, depending on the pseudoscalar boson lifetime
Visit by Representatives of the US Congress, in the frame of a Présence Suisse Study Tour
No full textVisit by Representatives of the US Congress, in the frame of a Présence Suisse Study Tour, United States of Americ
With Gratitude: Christoph Greub’s Impact and Legacy
No full textAs Christoph Greub embarks on a well-deserved retirement, we take this opportunity to celebrate his remarkable career and lasting contributions. Over the years, Christoph has been a pillar of excellence, known for his unwavering commitment and expertise in physics. This tribute reflects on his professional journey, the impact he has had on colleagues, young collaborators and the legacy he leaves behind. With deep appreciation, we honor Christoph’s accomplishments and wish him the best in this exciting new chapter of life
Benchmarking of CST and Trak in the simulation of an electron gun for a future C ion source
No full textThis study benchmarks the CST Studio Suite and Trak codes in simulating an electron gun for a future C hadrontherapy installation. CST Studio Suite offers 3D simulation capabilities, allowing detailed modelling of complex geometries and electromagnetic fields. Trak, on the other hand, offers efficient 2D simulations, which can significantly reduce computational time while still providing valuable results.These studies are being conducted in the framework of a project dedicated to the design of the initial stage of a C hadrontherapy linac. The electron gun studied is based on the MEDeGUN developed at CERN. This study provides an overview of the results obtained so far and outlines plans for future improvements and development
The SiPM-on-tile system of the CMS HGCAL
No full textFor the CMS High-Granularity Calorimeter (HGCAL) for HL-LHC, scintillator tiles, readout with individual on-tile silicon photomultipliers (SiPMs), will be used where the radiation levels are expected to be less than 5 × 1013 neq/cm2. The scintillator tiles will be mounted on highly-integrated “tile-boards” (typical area 30 × 30 cm2) that host up to 108 tiles and their SiPMs, as well as front-end electronics, control and powering components. A dedicated LED system will be implemented to monitor stability e↵ects. We present recent developments for the HGCAL scintillator material and SiPMs, including quantification of the scintillator and SiPM radiation-damage impact, modelling of SiPM noise and its evolution with time, SiPM production testing and quality control plans, and tests of tile-boards in laboratories and beam tests
Neutrino physics
No full textThis is an update of the lectures previously published in arXiv:1708.01046. The topics discussed in this lecture include: general properties of neutrinos in the SM, the theory of neutrino masses and mixings (Dirac and Majorana), neutrino oscillations both in vacuum and in matter, as well as an overview of the experimental evidence for neutrino masses and of the prospects in neutrino oscillation physics. We also briefly comment on the relevance of neutrinos in leptogenesis and in beyond-the- Standard-Model physics
Inverted CERN School of Computing 2025
No full text# Proposal: Reinforcement Learning for Particle Accelerator control: A real-world example
## Hour 1: Introduction to Reinforcement Learning for Particle Accelerators
- **Basic Concepts**:
- Overview of Reinforcement Learning (RL) fundamentals.
- Definitions and distinctions:
- Model-free vs. model-based.
- Off-policy vs. on-policy approaches.
- **Applications and Considerations**:
- Discussion of problem types and environmental variables affecting model selection in practical scenarios.
- Analysis of drawbacks and benefits of different RL architectures.
- **Practical examples**:
- Real-world examples of RL in particle accelerators (e.g., CERN).
- Case study introduction: Optimization of RF triple splittings in the Proton Synchrotron (PS).
## Hour 2: Optimizing RF Triple Splittings with Reinforcement Learning
- **Problem Definition**:
- Explanation of PS RF operations and the triple splitting optimization challenge for LHC-type beams.
- Overview of the physics and parameters involved in optimization.
- **Optimization Approach**:
- Justification for choosing RL and specific RL architectures.
- Step-by-step walkthrough:
- Initial simulations and trials.
- Challenges and lessons learned.
- Final operational solution deployed in the control room.
## Exercise Session: Training RL Agents for RF Optimization (1 hour)
- **Objective**:
- Train RL agents to optimize RF double splitting settings in simulation for improved beam quality.
- **Implementation**:
- Use SWAN notebooks with provided skeleton code.
- Define a custom gymnasium environment for the double splitting problem, given:
- Pre-implemented simulation data loaders.
- Basic loss function for optimization
Pseudorapidity density of charged particles at midrapidity in Pb-Pb collisions at = 5.36 TeV
No full textSearch for dijet resonances with data scouting in proton-proton collisions at
No full textA search is presented for resonances decaying to dijet final states in proton-proton collisions at . This search, for narrow resonances with a mass between and , is performed using dijets that are reconstructed from calorimeter information in the trigger, in so-called data scouting, from data corresponding to an integrated luminosity of . The dijet mass spectra are well described by a smooth parameterization and no significant evidence for the production of new particles is observed. Generic upper limits are presented on the product of the cross section, the branching fraction, and the acceptance for narrow quark-quark, quark-gluon, and gluon-gluon resonances, and are compared to the predictions from a variety of models of narrow dijet resonance production. The upper limits at confidence level on the coupling strength of a dark matter mediator are presented as a function of the mediator mass. These limits are significantly more constraining than those previously published by CMS