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Road map for the tuning of hadronic interaction models with accelerator-based and astroparticle data
No full textIn high-energy and astroparticle physics, event generators play an essential role, even in the simplest data analyses. As analysis techniques become more sophisticated, e.g. based on deep neural networks, their correct description of the observed event characteristics becomes even more important. Physical processes occurring in hadronic collisions are simulated within a Monte Carlo framework. A major challenge is the modeling of hadron dynamics at low momentum transfer, which includes the initial and final phases of every hadronic collision. QCD-inspired phenomenological models used for these phases cannot guarantee completeness or correctness over the full phase space. These models usually include parameters which must be tuned to suitable experimental data. Until now, event generators have been developed and tuned mainly on the basis of data from high-energy physics experiments at accelerators. The wealth of data available from the latest generation of astroparticle experiments has not yet been fully exploited, and in many cases is not satisfactorily described. Both kinds of data sets are complementary as astroparticle experiments provide sensitivity especially to hadrons produced nearly parallel to the collision axis and cover center-of-mass energies up to several hundred TeV, well beyond those reached at colliders so far. In this report, we provide an overview of state-of-the-art event generators and their tuning, including the most relevant inputs from high-energy accelerator and astroparticle experiments. We present a road map that shows, for the first time, how the unified tuning of event generators with accelerator-based and astroparticle data can be performed
Testing the Heterotic String with the Axion-Photon Coupling
No full textThe discovery of an axion-like particle above the QCD line would rule out Grand Unified Theories, including the perturbative heterotic string with the Standard Model embedded in a single factor or . In this work we study a possible loophole to this observation, given by compactifications of the heterotic string with a non-standard embedding of the Standard Model into the 10-dimensional gauge group. If electromagnetism is embedded into both factors, axions can couple to photons via the anomaly without coupling to QCD. We obtain upper bounds to the coupling-to-mass ratio for these axion-like particles as a function of the supersymmetry breaking scale and the unified gauge coupling. To be compatible with the measured gauge couplings and the weak mixing angle at low-energies, phenomenologically viable models with non-standard embedding require sizeable one-loop threshold corrections from string states and/or charged matter at intermediate energy scales. We study how these effects modify the tree-level upper bounds to and show that, in the perturbative regime, they reduce the leading order estimates. Axion-like particles far above the QCD line are only possible in certain models where perturbation theory is lost. The main conclusion is that the discovery of an axion violating the bounds found in this work would be incompatible with large classes of otherwise phenomenologically viable string models, including the perturbative heterotic and string, the type-I string, and certain heterotic M-theories. The role of small gauge instantons and worldsheet instantons in making some of the axion-like particles heavy and cosmologically relevant is briefly discussed
Measurement of Dependent Bending Angles in the CMS GE1/1-ME1/1 system and GE1/1 Alignment Result using 2025 p-p collision data
No full textThe Gas Electron Multiplier (GEM) subdetector system was designed for three stations in the endcap region. GEM
(GE1/1) chambers were installed in the first muon station and first ring during the second long shutdown (2019-
2021) to achieve acceptable first level trigger rates for muons with reasonably low transverse momentum ()
thresholds.
The performance of the standalone muon trigger is driven by the -dependent bending angles measured between
the GEM and Cathode Strip Chamber (CSC) detectors. The first measurements of bending angles are reported in a
detector performance (DP) report, CMS DP-2022/069, validating the use of GEM for muon triggering, as proposed
by Monte Carlo simulation studies in the Technical Design Report 2015.
The alignment of the GEM is mandatory for correct muon transverse momentum assignment, thus for muon
triggering and reconstruction. We report the comparison of two GEM alignment methods: tracker-propagation
method using muon tracks in the CMS tracker system, and back-propagation method using CSC as a reference to
reduce the muon momentum dependence due to the multiple scatterings.
In this note, improved measurements of the muon-track bending angle for muons ( GeV) and GEM
alignment results from 13.6 TeV collisions in 2025 are reported
Deep Learning for Primary Vertex Identification in the ATLAS Experiment
No full textThe exponential time scaling of traditional primary vertex reconstruction algorithms raises significant performance concerns for future high-pileup environments, particularly with the upcoming High Luminosity upgrade to the Large Hadron Collider. In this talk, we introduce PV-Finder, a deep learning-based approach that leverages reconstructed track parameters to directly predict primary vertex positions and track-to-vertex associations. Primary Vertex identification is achieved using a multi-layer perceptron (MLP) that converts track data into one-dimensional probability distributions, known as kernel density estimations (KDEs). These KDEs then serve as inputs to a convolutional neural network (CNN), specifically utilizing UNet and UNet++ architectures, to refine vertex position predictions. More recently, we have also explored the integration of graph neural networks (GNNs) to enhance track-vertex association. Preliminary results demonstrate that PV-Finder offers improved vertex reconstruction efficiency and accuracy, making it a compelling alternative to traditional methods
Optimized physics performance evaluation of monochromatization interaction region optics for direct -channel Higgs production at FCC-ee
No full textThe measurement of electron Yukawa coupling () via direct -channel Higgs production at 125 GeV centre-of-mass (CM) energy is significantly facilitated at the FCC-ee, provided that the CM energy spread can be reduced to a level comparable to the natural width of the Higgs boson. This reduction is possible through the “monochromatization” concept, which involves generating opposite correlations between spatial position and energy deviation in the colliding beams. Following initial parametric studies for this collision mode, three different interaction region optics designs, each featuring nonzero horizontal, vertical, or combined dispersion at the interaction point, have been proposed based on the Version 2022 of the FCC-ee Global Hybrid Correction optics. In this paper, we benchmark the upper limits contours on with simulated CM energy spread and luminosity using Guinea-Pig, in order to assess, optimize, and compare their physics performances
Functional design of a wideband RF system for helics synchrotron
No full textWithin the framework of the NIMMS (Next Ion Medical Machine Study) initiative at CERN, a comprehensive study is being performed for the Helium Light Ion Compact Synchrotron (HeLICS), a compact accelerator for hadron therapy. A key component of this facility is the radiofrequency (RF) cavity. Its proposed design is based on the wideband technology successfully implemented in the CERN PS Booster. It comprises four cells filled with Finemet material that enable the acceleration of protons and He over a broad energy range. The cavity, designed to deliver a peak voltage of up to 2 kV within a frequency range from 0.88 to 10 MHz, features a compact design to meet the stringent requirements of the medical accelerator. It operates in double-harmonic mode, to effectively reduce longitudinal line density of the beam bunch and mitigate space-charge effects at low energy. The combination of compactness and operational flexibility positions this RF cavity as an optimal solution for compact synchrotrons, enabling more efficient, precise, and accessible hadron therapy for cancer treatment
Emittance tuning of the FCC-ee High Energy Booster ring
No full textPrevious studies for the electron-positron version of the Future Circular Collider (FCC-ee) have highlighted the need to define tolerances on magnet imperfections and develop correction strategies. This is crucial for ensuring the performance of one of the main elements in the acceleration chain: the High Energy Booster (HEB) ring. The efficiency and overall performance of these correction strategies, as well as the magnet field quality and misalignment tolerances, directly influence the specifications of correction magnets. This, in turn, affects key parameters such as beta functions, dispersion, transverse coupling, and emittance. Horizontal and vertical orbit corrections utilize horizontal and vertical kickers, respectively. Skew quadrupoles address vertical dispersion, introduced by normal dipole roll, and transverse coupling. Normal quadrupoles corrects the horizontal and vertical phase advances. This study simulates the distribution of these four corrector types to minimize equilibrium emittance at the extraction energy of 45.6 GeV. The computed strengths of these correctors and the associated misalignments are presented
Open Science Fair 2025
No full textThroughout history, scientists have been both influenced by and constrained by the societal context in which they conduct their research. Scientific practices evolve as societies evolve. Who conducts scientific research, what tools and methods are available to them, what norms there are for dissemination of scientific knowledge, and how the society at large views the importance and trustworthiness of scientific results all have an effect on the scientific culture of the time. Major scientific and technological innovations can and do disrupt many aspects of society, including scholarly research. Whether we, as scientists, embrace these disruptors, ignore them, or even condemn them can have a direct impact on scientific progress, either accelerating or restraining our ability to address important societal challenges of the era.
Extraordinary scientific and technological advances in the latter part of the twentieth century and the first quarter of this century have led to profound and transformative changes in almost every facet of life. This talk will discuss some of these advances and consider the impact they have had and continue to have on scientific culture as we know it today. The talk will conclude with thoughts on some of the unintended consequences of these enormous changes, and how scientists themselves can work to ensure that their practices lead to the best possible science in service of the greater public good
Move more, eat better campaign
No full textDr Florence Somers, Endocrinologist, therapeutic education unit / endocrinologue, unité d’éducation thérapeutique