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The HL-LHC run is anticipated to start at the end of this decade and will pose a significant challenge for the scale of the HEP software and computing infrastructure. The mission of the U.S. CMS Software & Computing Operations Program is to develop and operate the software and computing resources necessary to process CMS data expeditiously and to enable U.S. physicists to fully participate in the physics of CMS. We have developed a strategic plan to prioritize R&D efforts to reach this goal for the HL-LHC. This plan includes four grand challenges: modernizing physics software and improving algorithms, building infrastructure for exabyte-scale datasets, transforming the scientific data analysis process and transitioning from R&D to operations. We are involved in a variety of R&D projects that fall within these grand challenges. In this talk, we will introduce our four grand challenges and outline the R&D program of the U.S. CMS Software & Computing Operations Program.

As the Large Hadron Collider (LHC) enters its future development phase, one of the key objectives is to increase its nominal luminosity, with the ultimate aim of achieving peak luminosities that would lead to up to 200 simultaneous proton collisions on average (pileup), presenting substantial hurdles for the CMS detector reconstruction process. The process of reconstructing the primary vertex (PV) in CMS involves two steps, namely vertex finding and fitting. Initially, the tracks originating from the same interaction vertex are clustered using the Deterministic Annealing algorithm. Subsequently, the Adaptive Vertex Fit is utilized to determine the most accurate estimate of the vertex position in either three or four dimensions. Due to the challenging conditions of High Luminosity LHC (HL-LHC), the PV reconstruction process can be extremely time-consuming, accounting for up to 6% of the overall reconstruction time. To address this issue, this study explores the feasibility of rethinking and adapting the PV reconstruction algorithms for heterogeneous architectures, taking advantage of parallelization techniques to reduce processing time significantly. The results of this study demonstrate improvements in both computing and physics performance, particularly for HL-LHC conditions.

The HL-LHC run is anticipated to start at the end of this decade and will pose a significant challenge for the scale of the HEP software and computing infrastructure. The mission of the U.S. CMS Software & Computing Operations Program is to develop and operate the software and computing resources necessary to process CMS data expeditiously and to enable U.S. physicists to fully participate in the physics of CMS. We have developed a strategic plan to prioritize R&D efforts to reach this goal for the HL-LHC. This plan includes four grand challenges: modernizing physics software and improving algorithms, building infrastructure for exabyte-scale datasets, transforming the scientific data analysis process and transitioning from R&D to operations. We are involved in a variety of R&D projects that fall within these grand challenges. In this talk, we will introduce our four grand challenges and outline the R&D program of the U.S. CMS Software & Computing Operations Program.

The standard model of particle physics can explain most measurements of elementary particle properties and interactions performed to date. However, it does not naturally explain the relatively light Higgs boson mass or the existence of small neutrino masses, and has no explanation for the dark matter observed in the universe. Many extensions to the standard model have been proposed to attempt to address these questions, and several predict the existence of heavy charged gauge bosons, usually referred to as W' bosons. The Large Hadron Collider at CERN is the largest and most powerful particle accelerator in the world and offers the opportunity to search for W' bosons using the CMS experiment, a large multi-purpose particle detector. Results are presented from a search for a W' boson produced in proton-proton collisions at a center of mass energy sqrt(s)=8 TeV and decaying into a top and a bottom quark, using a dataset collected by the CMS experiment corresponding to an integrated luminosity of 19.5 fb-1. Various models of W' boson production are studied by allowing for an arbitrary combination of left- and right-handed fermionic couplings. The analysis is based on the detection of events with an electron or muon, jets and missing transverse energy in the final state. No evidence for W' boson production is found and 95% confidence level upper limits are obtained on the production cross section for several mass hypotheses and compared to theoretical predictions. For W' bosons with purely right-handed couplings, and for those with left-handed couplings when ignoring interference effects, the observed 95% confidence level limit on the W' boson mass is M(W')>2.05 TeV. These are the most stringent limits obtained to date in this channel.

This paper presents performance measurements of a new readout electronics system based on silicon photomultipliers for the PHENIX electromagnetic calorimeter. Installation of the lead-scintillator Shashlik style calorimeter into the SeaQuest/SpinQuest spectrometer has been proposed to broaden the experiment's dark sector search program, an upgrade known as DarkQuest. The calorimeter and electronics system were subjected to testing and calibration at the Fermilab Test Beam Facility. Detailed studies of the energy response and resolution, as well as particle identification capabilities, were performed. The background rate in the actual experimental environment was also examined. The system is found to be well-suited for a dark sector search program on the Fermilab 120 GeV proton beamline.

The HL-LHC run is anticipated to start at the end of this decade and will pose a significant challenge for the scale of the HEP software and computing infrastructure. The mission of the U.S. CMS Software & Computing Operations Program is to develop and operate the software and computing resources necessary to process CMS data expeditiously and to enable U.S. physicists to fully participate in the physics of CMS. We have developed a strategic plan to prioritize R&D efforts to reach this goal for the HL-LHC. This plan includes four grand challenges: modernizing physics software and improving algorithms, building infrastructure for exabyte-scale datasets, transforming the scientific data analysis process and transitioning from R&D to operations. We are involved in a variety of R&D projects that fall within these grand challenges. In this talk, we will introduce our four grand challenges and outline the R&D program of the U.S. CMS Software & Computing Operations Program.

Expanding the mass range and techniques by which we search for dark matter is an important part of the worldwide particle physics program. Accelerator-based searches for dark matter and dark sector particles are a uniquely compelling part of this program as a way to both create and detect dark matter in the laboratory and explore the dark sector by searching for mediators and excited dark matter particles. This paper focuses on developing the DarkQuest experimental concept and gives an outlook on related enhancements collectively referred to as LongQuest. DarkQuest is a proton fixed-target experiment with leading sensitivity to an array of visible dark sector signatures in the MeV-GeV mass range. Because it builds off of existing accelerator and detector infrastructure, it offers a powerful but modest-cost experimental initiative that can be realized on a short timescale.

Dark matter (DM) simplified models are by now commonly used by the ATLAS and CMS Collaborations to interpret searches for missing transverse energy (\\(E_T^miss\\)). The coherent use of these models sharpened the LHC DM search program, especially in the presentation of its results and their comparison to DM direct-detection (DD) and indirect-detection (ID) experiments. However, the community has been aware of the limitations of the DM simplified models, in particular the lack of theoretical consistency of some of them and their restricted phenomenology leading to the relevance of only a small subset of \\(E_T^miss\\) signatures. This document from the LHC Dark Matter Working Group identifies an example of a next-generation DM model, called \\(2HDM+a\\), that provides the simplest theoretically consistent extension of the DM pseudoscalar simplified model. A~comprehensive study of the phenomenology of the \\(2HDM+a\\) model is presented, including a discussion of the rich and intricate pattern of mono-\\(X\\) signatures and the relevance of other DM as well as non-DM experiments. Based on our discussions, a set of recommended scans are proposed to explore the parameter space of the \\(2HDM+a\\) model through LHC searches. The exclusion limits obtained from the proposed scans can be consistently compared to the constraints on the \\(2HDM+a\\) model that derive from DD, ID and the DM relic density.

This work focused on the experimental study of grease lubrication mechanisms around contacts in radial ball bearing 6314. The main objective of this work was to show the influence of conformities and their impact on grease lubrication in ball bearings. For the experiments, a tribometer of ball-on-ring configuration was used and fluorescence microscopy was chosen as the observation method. The results showed that, under starvation conditions, a conformity of 0.52 at velocities around 2 m/s produces a 50% thicker lubricating film than a conformity of 0.58. The available amount of lubricant around the contact area for conformity 0.52 was approximately three times less than that for conformity 0.58, and the same ratio was observed for the amount of lubricant on the rolling track. Experiments show that a realistic tribometer geometry allows a more accurate experimental study of the lubrication mechanisms of greases in ball bearings.

This paper deals with the experimental study of an elastohydrodynamic contact under conditions of insufficient lubricant supply. Starvation level of this type of the contact may be experimentally determined based on the position of the meniscus, but this way can't determine all levels of starvation. Consequent development in the field of tribology achieved theoretical model that can determine all levels of starvation by dependency on the thickness of the lubricant film entering the contact, but it is difficult for experimental verification. The main goal of this work is an experimental study and description of the behavior of the elastohydrodynamic contact with controlled thickness of the lubricant film at the contact input. Contact was lubricated by the base oil and the grease and compared. Results were surprising because the only differences between oil and grease were observed for more viscous lubricants at thicker film layer entering to the contact.