796 research outputs found
Physics with electroweak penguins at LHCb
Flavour changing neutral currents are only allowed via loop diagrams in the
Standard Model (SM). Electroweak penguin processes are therefore sensitive
probes for new physics, as physics beyond the Standard Model can enter via
virtual particles at the same level as SM physics. The LHCb detector at the LHC
with its forward geometry is ideally suited for the analysis of electroweak
penguin processes in meson decays. All analyses are performed with 1
fb of collision data recorded at a centre-of-mass energy of 7 TeV in
2011 and constrain new physics models.Comment: Proceedings of CKM 2012, the 7th International Workshop on the CKM
Unitarity Triangle, University of Cincinnati, USA, 28 September - 2 October
201
Fast and flexible data structures for the LHCb Run 3 software trigger
Starting in 2022, the upgraded LHCb detector will collect data with a pure
software trigger. In its first stage, reducing the rate from 30MHz to about
1MHz, GPUs are used to reconstruct and trigger on B and D meson topologies and
high-pT objects in the event. In its second stage, a CPU farm is used to
reconstruct the full event and perform candidate selections, which are
persisted for offline use with an output rate of about 10 GB/s. Fast data
processing, flexible and custom-designed data structures tailored for SIMD
architectures and efficient storage of the intermediate data at various steps
of the processing pipeline onto persistent media, e.g. tapes is essential to
guarantee the full physics program of LHCb. In this talk, we will present the
event model and data persistency developments for the trigger of LHCb in Run 3.
Particular emphasize will be given to the novel software-design aspects with
respect to the Run 1+2 data taking, the performance improvements which can be
achieved and the experience of restructuring a major part of the reconstruction
software in a large HEP experiment.Comment: Connecting The Dots (CTD 2022), Princeton, United States Of America,
31 May - 2 Jun 202
HEP Community White Paper on Software trigger and event reconstruction
Realizing the physics programs of the planned and upgraded high-energy
physics (HEP) experiments over the next 10 years will require the HEP community
to address a number of challenges in the area of software and computing. For
this reason, the HEP software community has engaged in a planning process over
the past two years, with the objective of identifying and prioritizing the
research and development required to enable the next generation of HEP
detectors to fulfill their full physics potential. The aim is to produce a
Community White Paper which will describe the community strategy and a roadmap
for software and computing research and development in HEP for the 2020s. The
topics of event reconstruction and software triggers were considered by a joint
working group and are summarized together in this document.Comment: Editors Vladimir Vava Gligorov and David Lang
A Roadmap for HEP Software and Computing R&D for the 2020s
Particle physics has an ambitious and broad experimental programme for the coming decades. This programme requires large investments in detector hardware, either to build new facilities and experiments, or to upgrade existing ones. Similarly, it requires commensurate investment in the R&D of software to acquire, manage, process, and analyse the shear amounts of data to be recorded. In planning for the HL-LHC in particular, it is critical that all of the collaborating stakeholders agree on the software goals and priorities, and that the efforts complement each other. In this spirit, this white paper describes the R&D activities required to prepare for this software upgrade.Peer reviewe
Les droits disciplinaires des fonctions publiques : « unification », « harmonisation » ou « distanciation ». A propos de la loi du 26 avril 2016 relative à la déontologie et aux droits et obligations des fonctionnaires
The production of tt‾ , W+bb‾ and W+cc‾ is studied in the forward region of proton–proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fb−1 . The W bosons are reconstructed in the decays W→ℓν , where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of , and is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 0.02 \mbox{fb}^{-1}. The bosons are reconstructed in the decays , where denotes muon or electron, while the and quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions
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Identification of carbon dioxide in an exoplanet atmosphere
Carbon dioxide (CO2) is a key chemical species that is found in a wide range of planetary atmospheres. In the context of exoplanets, CO2 is an indicator of the metal enrichment (that is, elements heavier than helium, also called ‘metallicity’), and thus the formation processes of the primary atmospheres of hot gas giants. It is also one of the most promising species to detect in the secondary atmospheres of terrestrial exoplanets. Previous photometric measurements of transiting planets with the Spitzer Space Telescope have given hints of the presence of CO2, but have not yielded definitive detections owing to the lack of unambiguous spectroscopic identification. Here we present the detection of CO2 in the atmosphere of the gas giant exoplanet WASP-39b from transmission spectroscopy observations obtained with JWST as part of the Early Release Science programme. The data used in this study span 3.0–5.5 micrometres in wavelength and show a prominent CO2 absorption feature at 4.3 micrometres (26-sigma significance). The overall spectrum is well matched by one-dimensional, ten-times solar metallicity models that assume radiative–convective–thermochemical equilibrium and have moderate cloud opacity. These models predict that the atmosphere should have water, carbon monoxide and hydrogen sulfide in addition to CO2, but little methane. Furthermore, we also tentatively detect a small absorption feature near 4.0 micrometres that is not reproduced by these models
A study of CP violation in B-+/- -> DK +/- and B-+/- -> D pi(+/-) decays with D -> (KSK +/-)-K-0 pi(-/+) final states
A first study of CP violation in the decay modes and , where labels a or meson and labels a or meson, is performed. The analysis uses the LHCb data set collected in collisions, corresponding to an integrated luminosity of 3 fb. The analysis is sensitive to the CP-violating CKM phase through seven observables: one charge asymmetry in each of the four modes and three ratios of the charge-integrated yields. The results are consistent with measurements of using other decay modes
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