Recent results from the CMS Collaboration using top quarks are presented. These results are based on partial datasets collected by the CMS Collaboration during the LHC Run 2, at a center-of-mass ...energy of 13 TeV. This document includes the first measurement of tt‾ production in association with charm quarks, the first direct measurement of the third generation of the CKM matrix elements, the investigation of the running of the top quark mass, search for CP violation in top quark production, measurement of the forward-backward asymmetry in tt‾ production at the LHC, and the first global approach in constraining EFT operator coefficients using top quarks.
Abstract Knowledge distillation is a form of model compression that allows artificial neural networks of different sizes to learn from one another. Its main application is the compactification of ...large deep neural networks to free up computational resources, in particular on edge devices. In this article, we consider proton-proton collisions at the High-Luminosity Large Hadron Collider (HL-LHC) and demonstrate a successful knowledge transfer from an event-level graph neural network (GNN) to a particle-level small deep neural network (DNN). Our algorithm, DistillNet , is a DNN that is trained to learn about the provenance of particles, as provided by the soft labels that are the GNN outputs, to predict whether or not a particle originates from the primary interaction vertex. The results indicate that for this problem, which is one of the main challenges at the HL-LHC, there is minimal loss during the transfer of knowledge to the small student network, while improving significantly the computational resource needs compared to the teacher. This is demonstrated for the distilled student network on a CPU, as well as for a quantized and pruned student network deployed on an field programmable gate array. Our study proves that knowledge transfer between networks of different complexity can be used for fast artificial intelligence (AI) in high-energy physics that improves the expressiveness of observables over non-AI-based reconstruction algorithms. Such an approach can become essential at the HL-LHC experiments, e.g. to comply with the resource budget of their trigger stages.
This report presents a short summary of the activities of the "Standard Model" working group for the "Physics at TeV Colliders" workshop (Les Houches, France, 12-30 June, 2023).
Functional fluorescence microscopy imaging (fFMI), a time-resolved (21 μs/frame) confocal fluorescence microscopy imaging technique without scanning, is developed for quantitative characterization of ...fast reaction-transport processes in solution and in live cells. The method is based on massively parallel fluorescence correlation spectroscopy (FCS). Simultaneous excitation of fluorescent molecules in multiple spots in the focal plane is achieved using a diffractive optical element (DOE). Fluorescence from the DOE-generated 1024 illuminated spots is detected in a confocal arrangement by a matching matrix detector comprising 32 × 32 single-photon avalanche photodiodes (SPADs). Software for data acquisition and fast auto- and cross-correlation analysis by parallel signal processing using a graphic processing unit (GPU) allows temporal autocorrelation across all pixels in the image frame in 4 s and cross-correlation between first- and second-order neighbor pixels in 45 s. We present here this quantitative, time-resolved imaging method with single-molecule sensitivity and demonstrate its usefulness for mapping in live cell location-specific differences in the concentration and translational diffusion of molecules in different subcellular compartments. In particular, we show that molecules without a specific biological function, e.g., the enhanced green fluorescent protein (eGFP), exhibit uniform diffusion. In contrast, molecules that perform specialized biological functions and bind specifically to their molecular targets show location-specific differences in their concentration and diffusion, exemplified here for two transcription factor molecules, the glucocorticoid receptor (GR) before and after nuclear translocation and the Sex combs reduced (Scr) transcription factor in the salivary gland of Drosophila ex vivo.
The H1 Collaboration reports the first measurement of the 1-jettiness event shape observable \(\tau_1^b\) in neutral-current deep-inelastic electron-proton scattering (DIS). The observable ...\(\tau_1^b\) is equivalent to a thrust observable defined in the Breit frame. The data sample was collected at the HERA \(ep\) collider in the years 2003-2007 with center-of-mass energy of \(\sqrt{s}=319\,\text{GeV}\), corresponding to an integrated luminosity of \(351.1\,\text{pb}^{-1}\). Triple differential cross sections are provided as a function of \(\tau_1^b\), event virtuality \(Q^2\), and inelasticity \(y\), in the kinematic region \(Q^2>150\,\text{GeV}^{2}\). Single differential cross section are provided as a function of \(\tau_1^b\) in a limited kinematic range. Double differential cross sections are measured, in contrast, integrated over \(\tau_1^b\) and represent the inclusive neutral-current DIS cross section measured as a function of \(Q^2\) and \(y\). The data are compared to a variety of predictions and include classical and modern Monte Carlo event generators, predictions in fixed-order perturbative QCD where calculations up to \(\mathcal{O}(\alpha_s^3)\) are available for \(\tau_1^b\) or inclusive DIS, and resummed predictions at next-to-leading logarithmic accuracy matched to fixed order predictions at \(\mathcal{O}(\alpha_s^2)\). These comparisons reveal sensitivity of the 1-jettiness observable to QCD parton shower and resummation effects, as well as the modeling of hadronization and fragmentation. Within their range of validity, the fixed-order predictions provide a good description of the data. Monte Carlo event generators are predictive over the full measured range and hence their underlying models and parameters can be constrained by comparing to the presented data.
The H1 Collaboration at HERA reports the first measurement of groomed event shape observables in deep inelastic electron-proton scattering (DIS) at \(\sqrt{s}=319\) GeV, using data recorded between ...the years 2003 and 2007 with an integrated luminosity of \(351\) pb\(^{-1}\). Event shapes provide incisive probes of perturbative and non-perturbative QCD. Grooming techniques have been used for jet measurements in hadronic collisions; this paper presents the first application of grooming to DIS data. The analysis is carried out in the Breit frame, utilizing the novel Centauro jet clustering algorithm that is designed for DIS event topologies. Events are required to have squared momentum-transfer \(Q^2 > 150\) GeV\(^2\) and inelasticity \( 0.2 < y < 0.7\). We report measurements of the production cross section of groomed event 1-jettiness and groomed invariant mass for several choices of grooming parameter. Monte Carlo model calculations and analytic calculations based on Soft Collinear Effective Theory are compared to the measurements.
The Breit frame provides a natural frame to analyze lepton-proton scattering events. In this reference frame, the parton model hard interactions between a quark and an exchanged boson defines the ...coordinate system such that the struck quark is back-scattered along the virtual photon momentum direction. In Quantum Chromodynamics (QCD), higher order perturbative or non-perturbative effects can change this picture drastically. As Bjorken-\(x\) decreases below one half, a rather peculiar event signature is predicted with increasing probability, where no radiation is present in one of the two Breit-frame hemispheres and all emissions are to be found in the other hemisphere. At higher orders in \(\alpha_s\) or in the presence of soft QCD effects, predictions of the rate of these events are far from trivial, and that motivates measurements with real data. We report on the first observation of the empty current hemisphere events in electron-proton collisions at the HERA collider using data recorded with the H1 detector at a center-of-mass energy of 319 GeV. The fraction of inclusive neutral-current DIS events with an empty hemisphere is found to be \(0.0112 \pm 3.9\,\%_\text{stat} \pm 4.5\,\%_\text{syst} \pm 1.6\,\%_\text{mod}\) in the selected kinematic region of \(150< Q^2<1500\) GeV\(^2\) and inelasticity \(0.14< y<0.7\). The data sample corresponds to an integrated luminosity of 351.1 pb\(^{-1}\), sufficient to enable differential cross section measurements of these events. The results show an enhanced discriminating power at lower Bjorken-\(x\) among different Monte Carlo event generator predictions.
The radiation pattern within high energy quark- and gluon-initiated jets (jet substructure) is used extensively as a precision probe of the strong force as well as an environment for optimizing event ...generators with numerous applications in high energy particle and nuclear physics. Looking at electron-proton collisions is of particular interest as many of the complications present at hadron colliders are absent. A detailed study of modern jet substructure observables, jet angularities, in electron-proton collisions is presented using data recorded using the H1 detector at HERA. The measurement is unbinned and multi-dimensional, using machine learning to correct for detector effects. All of the available reconstructed object information of the respective jets is interpreted by a graph neural network, achieving superior precision on a selected set of jet angularities. Training these networks was enabled by the use of a large number of GPUs in the Perlmutter supercomputer at Berkeley Lab. The particle jets are reconstructed in the laboratory frame, using the \(k_{\mathrm{T}}\) jet clustering algorithm. Results are reported at high transverse momentum transfer \(Q^2>150\) GeV\({}^2\), and inelasticity \(0.2 < y < 0.7\). The analysis is also performed in sub-regions of \(Q^2\), thus probing scale dependencies of the substructure variables. The data are compared with a variety of predictions and point towards possible improvements of such models.
The Electron-Ion Collider (EIC), a state-of-the-art facility for studying the strong force, is expected to begin commissioning its first experiments in 2028. This is an opportune time for artificial ...intelligence (AI) to be included from the start at this facility and in all phases that lead up to the experiments. The second annual workshop organized by the AI4EIC working group, which recently took place, centered on exploring all current and prospective application areas of AI for the EIC. This workshop is not only beneficial for the EIC, but also provides valuable insights for the newly established ePIC collaboration at EIC. This paper summarizes the different activities and R&D projects covered across the sessions of the workshop and provides an overview of the goals, approaches and strategies regarding AI/ML in the EIC community, as well as cutting-edge techniques currently studied in other experiments.
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