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Constraints on Attractor Models of Inflation and Reheating from Planck, BICEP/Keck, ACT DR6, and SPT-3G Data
No full textWe analyze the latest cosmic microwave background (CMB) constraints on the scalar spectral index and tensor-to-scalar ratio from Planck 2018, BICEP/Keck 2018, the Atacama Cosmology Telescope Data Release 6 (ACT DR6), and the South Pole Telescope (SPT-3G) data, focusing on their implications for attractor models of inflation. We compare systematically observational bounds with theoretical predictions for both E-model (-Starobinsky) and T-model potentials. The observational constraints accommodate E-models with , with the canonical Starobinsky model () predicting for reheating temperatures between GeV, in good agreement with Planck 2018 data and within the 95% CL region determined by the Planck-ACT-SPT combination, but below the 95% confidence region of the Planck-ACT-DESI combination. Higher reheating temperatures from near-instantaneous reheating improve the compatibility. T-models predict slightly lower values (0.956-0.961), in some tension with Planck 2018 data, and we find an upper limit of in these models. We extend our analysis to generalized -attractors with monomial potentials near the minimum, demonstrating that models with naturally predict for typical number of -folds, in better agreement with the ACT DR6 data. We also consider deformed E- and T-models, which allow significantly higher values of for low values of
Heavy Neutral Lepton Searches at the LHCb Experiment
No full textHeavy Neutral Leptons (HNLs) are hypothetical long-lived particles that extend the Standard Model (SM) and provide a natural explanation for the non-zero neutrino masses. In addition, they could play a key role in addressing some of the most profound open questions in particle physics and cosmology, including the origin of the matter–antimatter asymmetry via baryogenesis. In this poster, we present the status and state-of-the-art of HNL searches at the LHCb experiment. We report the latest and most stringent LHCb limits on muon-coupled HNLs in the 1.6–5 GeV mass range, obtained from a Run 2 (2016–2018) analysis targeting displaced vertices corresponding to HNL flight distances of 0.02–0.5 m. Looking ahead, for Run 3 we introduce a novel reconstruction technique that exploits track segments downstream of the LHCb magnet, thereby extending the accessible displacement window to 0.5–8.0 m. This approach enhances sensitivity dramatically, providing a 40-fold increase in the number of accessible HNL events and extending the lifetime reach by a factor of 16 compared to the Run 2 analysis. A dedicated sensitivity study shows how these improvements translate into a significantly extended reach in the HNL mass–coupling parameter space, positioning LHCb to set world-leading constraints on HNLs
FEROCE: Front-End RDMA Over Converged Ethernet, a lightweight RoCE endpoint
No full textIn a DAQ system a large fraction of CPU resources is engaged in networking rather than in data processing. The common network stacks that take care of network traffic usually manipulate data through several copies performing expensive operations. Thus, when the CPU is asked to handle networking, the main drawbacks are throughput reduction and latency increase due to the overhead added to the data transmission process. Networking with zero-copy can be achieved by adding a Remote Direct Memory Access (RDMA) layer to the network stack and making dedicated hardware take care of the burden of the stack handling. Considering the ever-growing demand of larger bandwidth for big data systems, many works point in the direction of implementing network stacks on custom hardware. FPGAs are the natural target for reducing time to market and keeping a low entry-barrier. In this work implementation of RDMA directly on the front-end electronics is explored, in this way it is possible to free part of the computing farm’s CPU resources. RDMA over Converged Ethernet (RoCE) is the industry-standard Ethernet-based RDMA solution with a multi-vendor ecosystem, making it the natural choice. This work focuses on the hardware implementation of a stripped-down version of RoCEv2 implementing only the transmitter part of the protocol, enabling its deployment in small FPGA such as the rad-hard parts used in the detector front-end. Preliminary results of resource usage, latency and throughput will be shown
Infrastructure for deployment and evaluation of LHCb trigger configurations
No full textLHCb high-level trigger applications consist of components that run reconstruction algorithms and perform physics object selections, scaling from hundreds to tens of thousands depending on the selection stage. The configuration of the components, the data flow and the control flow are implemented in Python . The resulting application configuration is condensed in the basic form of a list of components with their properties and values.It is often required to change configuration without deploying new binaries. Moreover, it is essential to be able to reproduce a given production configuration and to be able to query it after it has been used. For these reasons, the basic form of the trigger configuration is captured and stored in a database via Git .This contribution describes a new infrastructure around generating and validating the configurations. The process is based on GitLab pipelines that are triggered by user defined specifications and run several steps ranging from basic checks to performance validation using dedicated runners. Upon merging, the configuration database is deployed on CVMFS. The process as implemented ensures consistency and reproducibility for the generated trigger configurations
Search for dijet resonances with data scouting in proton-proton collisions at 13 TeV
No full textA search is presented for narrow resonances, with a mass between 0.6 and 1.8 TeV, decaying to pairs of jets, in proton-proton collisions at 13 TeV. The search is performed using dijets that are reconstructed, selected, and recorded in a compact form by the high-level trigger in a technique referred to as ``data scouting'', from data collected in 2016-2018 corresponding to an integrated luminosity of 117 fb. The dijet mass spectra are well described by a smooth parameterization, and no significant evidence for the production of new particles is observed. Model-independent upper limits are presented on the product of the cross section, branching fraction, and acceptance for the individual cases of 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 limit on the coupling of a dark matter mediator to quarks is presented as a function of the mediator mass. The sensitivity of this search goes beyond what is expected from statistical scaling with the integrated luminosity alone, as a consequence of the use of fewer parameters in the background function within a more robust statistical procedure.A search is presented for narrow resonances, with a mass between 0.6 and 1.8 TeV, decaying to pairs of jets, in proton-proton collisions at = 13 TeV. The search is performed using dijets that are reconstructed, selected, and recorded in a compact form by the high-level trigger in a technique referred to as "data scouting", from data collected in 20162018 corresponding to an integrated luminosity of 177 fb. The dijet mass spectra are well described by a smooth parameterization, and no significant evidence for the production of new particles is observed. Model-independent upper limits are presented on the product of the cross section, branching fraction, and acceptance for the individual cases of 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 limit on the coupling of a dark matter mediator to quarks is presented as a function of the mediator mass. The sensitivity of this search goes beyond what is expected from statistical scaling with the integrated luminosity alone, as a consequence of the use of fewer parameters in the background function within a more robust statistical procedure
Experience with the CERN LINAC4 and its performance during the first four years of operation
No full textSince 2020 LINAC4 provides the protons for the entire CERN accelerator complex. It accelerates H- ions to a kinetic energy of 160 MeV and injects them into the Proton Synchrotron (PS) Booster using a charge exchange injection mechanism. The performance requirements have been successfully met since 2021. This paper presents the operational experience gained, together with availability and reliability statistics for LINAC4, during its first four years of operation, and details the key performance indicators for beam quality and stability. It also discusses the main issues encountered and the implemented solutions that have allowed further improvements to be made. Recent developments on the H- ion source have led to an increase of the beam current from the original 35 mA to 50 mA, opening the possibility to increase the intensity delivered to the PS Booster for the benefit of CERN's experimental programmes. Beam energy modulation in LINAC4 has also been developed to increase the PS Booster bunch intensity for which the results of beam tests are presented
QCD at the LHC
No full textThis talk summarizes recent progress in studying QCD at the LHC, covering the insights gained by detailed studies of various processes, such as single vector-boson production and Drell-Yan processes, associated production of vector boson and jets, inclusive and multijet production, processes that probe soft QCD and multi-parton interactions. These results collectively improve our understanding of QCD at a large range of energy scales, knowledge about parton density distributions, as well as precision in fundamental parameters such as the strong coupling constant
