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Optimisation and validation of power delivery networks for multi-gigabit data links
No full textThe performance of ASICs for high-bandwidth communications is heavily influenced by the interconnection with the hosting module and paired devices, including the bonding scheme and the PCB layout. The recent validation campaign of the 25.6 Gbps DART28 transmitter has highlighted that a coordinated simulation and design of the power delivery network is required to achieve satisfactory performance. In this context, the results obtained from variants of the test-bench carrier boards are compared, examining how the optimisation of the layout and bondwire placement leads to improvements of the serial link characteristics. Electromagnetic simulations support the analysis and provide a framework for developing the subsequent versions
NNPDFpol2.0: a global determination of polarised PDFs and their uncertainties at next-to-next-to-leading order
No full textWe present NNPDFpol2.0, a new set of collinear helicity parton distribution functions (PDFs) of the proton based on legacy measurements of structure functions in inclusive neutral-current longitudinally polarised deep-inelastic scattering (DIS), and of W -boson, single-inclusive, and di-jet production asymmetries in longitudinally polarised proton-proton collisions. The determination is accurate to next-to-next-to-leading order in the strong coupling, and includes heavy quark mass corrections in the analysis of DIS data. Uncertainties due to missing higher-order corrections are systematically incorporated by means of a covariance matrix determined by scale variations. NNPDFpol2.0 is based on a machine learning methodology, that makes use of Monte Carlo sampling for the representation of uncertainties into PDFs, of a neural network for the parametrisation of PDFs, of stochastic gradient descent for the optimisation of PDF parameters, and of hyperoptimisation for the selection of the best fitting model. We study the impact on PDFs of higher-order corrections, of the positivity constraint, and of the data. We demonstrate two phenomenological applications of NNPDFpol2.0, specifically the determination of the proton spin fraction carried by gluons and quarks, and of theoretical predictions for single-hadron production in longitudinally polarised DIS and proton-proton collisions.We present NNPDFpol2.0, a new set of collinear helicity parton distribution functions (PDFs) of the proton based on legacy measurements of structure functions in inclusive neutral-current longitudinally polarised deep-inelastic scattering (DIS), and of W -boson, single-inclusive, and di-jet production asymmetries in longitudinally polarised proton-proton collisions. The determination is accurate to next-to-next-to-leading order in the strong coupling, and includes heavy quark mass corrections in the analysis of DIS data. Uncertainties due to missing higher-order corrections are systematically incorporated by means of a covariance matrix determined by scale variations. NNPDFpol2.0 is based on a machine learning methodology, that makes use of Monte Carlo sampling for the representation of uncertainties into PDFs, of a neural network for the parametrisation of PDFs, of stochastic gradient descent for the optimisation of PDF parameters, and of hyperoptimisation for the selection of the best fitting model. We study the impact on PDFs of higher-order corrections, of the positivity constraint, and of the data. We demonstrate two phenomenological applications of NNPDFpol2.0, specifically the determination of the proton spin fraction carried by gluons and quarks, and of theoretical predictions for single-hadron production in longitudinally polarised DIS and proton-proton collisions
Preliminary Design Considerations for the Forward Liquid Argon detector (FLArE) at the high luminosity LHC
No full textThis technical note describes the current status of the technical design and optimization of the FLArE detector in the Forward Physics Facility (FPF). It is a working document that summarizes the current studies including possible improvements and future items to investigate. This note should serve as the main reference to outline the contents already available or that need to be completed towards a conceptual design report. The note provides the scientific and technical requirements along with engineering constraints that have led to the current conceptual design. Some of the major design features have options that need to be investigated further. The note concludes with a preliminary summary of the core costs and labor estimates for constructing this detector. This note is accompanied by a separate note on simulation studies of FLArE and the FPF
Search for vector-like leptons with long-lived particle decays in the CMS muon system in proton-proton collisions at 13 TeV
No full textA first search is presented for vector-like leptons (VLLs) decaying into a light long-lived pseudoscalar boson and a standard model lepton. The pseudoscalar boson is assumed to have a mass of 2 GeV and to decay exclusively into a pair of photons. It is identified using the CMS muon system. The analysis is carried out using a data set of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment in 2016--2018, corresponding to an integrated luminosity of 138 fb. Selected events contain at least one pseudoscalar boson decaying electromagnetically in the muon system and at least one hadronically decaying lepton. No significant excess of data events is observed compared to the background expectation. Upper limits are set at 95% confidence level on the vector-like lepton production cross section as a function of the VLL mass and the pseudoscalar boson mean proper decay length. The observed and expected exclusion ranges of the VLL mass extend up to 700 and 670 GeV, respectively, depending on the pseudoscalar boson lifetime.A first search is presented for vector-like leptons (VLLs) exclusively decaying into a light long-lived pseudoscalar boson and a standard model τ lepton. The pseudoscalar boson is assumed to have a mass below the ττ threshold, so that it decays exclusively into two photons. It is identified using the CMS muon system. The analysis is carried out using a data set of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment in 2016–2018, corresponding to an integrated luminosity of 138 fb. Selected events contain at least one pseudoscalar boson decaying electromagnetically in the muon system and at least one hadronically decaying τ lepton. No significant excess of data events is observed compared to the background expectation. Upper limits are set at 95% confidence level on the vector-like lepton production cross section as a function of the VLL mass and the pseudoscalar boson mean proper decay length. The observed and expected exclusion ranges of the VLL mass extend up to 700 and 670 GeV, respectively, depending on the pseudoscalar boson lifetime.[graphic not available: see fulltext]A first search is presented for vector-like leptons (VLLs) decaying into a light long-lived pseudoscalar boson and a standard model lepton. The pseudoscalar boson is assumed to have a mass below the threshold, so that it decays exclusively into two photons. It is identified using the CMS muon system. The analysis is carried out using a data set of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment in 2016-2018, corresponding to an integrated luminosity of 138 fb. Selected events contain at least one pseudoscalar boson decaying electromagnetically in the muon system and at least one hadronically decaying lepton. No significant excess of data events is observed compared to the background expectation. Upper limits are set at 95% confidence level on the vector-like lepton production cross section as a function of the VLL mass and the pseudoscalar boson mean proper decay length. The observed and expected exclusion ranges of the VLL mass extend up to 700 and 670 GeV, respectively, depending on the pseudoscalar boson lifetime
Classification of Electron and Muon Neutrino Events for the ESSSB Near Water Cherenkov Detector using Graph Neural Networks
No full textIn the effort to obtain a precise measurement of leptonicCP-violation with the ESSνSB experiment, accurate and fastreconstruction of detector events plays a pivotal role. In thiswork, we examine the possibility of replacing the currently proposedlikelihood-based reconstruction method with an approach based onGraph Neural Networks (GNNs). As the likelihood-based reconstructionmethod is reasonably accurate but computationally expensive, one ofthe benefits of a Machine Learning (ML) based method is enablingfast event reconstruction in the detector development phase,allowing for easier investigation of the effects of changes to thedetector design. Focusing on classification of flavour andinteraction type in muon and electron events and muon- and electronneutrino interaction events, we demonstrate that the GNNreconstructs events with greater accuracy than the likelihood methodfor events with greater complexity, and with increased speed for alltypes of events. The GNN flavour classification of neutrinointeraction events results in a true positive rate of 85.87 %(57.90 %) for muon (electron) neutrinos, compared to 35.55 %(0.21 %) for the likelihood-based method with identicalconstraints on the false positive rate, while the reconstructionspeed is increased by a factor of 10. Additionally, weinvestigate the key factors impacting reconstruction performance,and demonstrate how separation of events by pion production usinganother GNN classifier can benefit flavour classification.In the effort to obtain a precise measurement of leptonic CP-violation with the ESSSB experiment, accurate and fast reconstruction of detector events plays a pivotal role. In this work, we examine the possibility of replacing the currently proposed likelihood-based reconstruction method with an approach based on Graph Neural Networks (GNNs). As the likelihood-based reconstruction method is reasonably accurate but computationally expensive, one of the benefits of a Machine Learning (ML) based method is enabling fast event reconstruction in the detector development phase, allowing for easier investigation of the effects of changes to the detector design. Focusing on classification of flavour and interaction type in muon and electron events and muon- and electron neutrino interaction events, we demonstrate that the GNN reconstructs events with greater accuracy than the likelihood method for events with greater complexity, and with increased speed for all events. Additionally, we investigate the key factors impacting reconstruction performance, and demonstrate how separation of events by pion production using another GNN classifier can benefit flavour classification
Les Dieux et le Père Noël : vers une solution quantique
No full textLes Dieux et le Père Noël : vers une solution quantique
Comédie quantique
« Des chercheurs qui cherchent, on peut en trouver. Des chercheurs qui trouvent des choses, on en cherche ! Vous trouvez que c’est drôle ? Eh bien, non ! Un chercheur qui a trouvé quelque chose, c’est d’abord et avant tout un chercheur qui n’a plus de travail. Il se retrouve au chômage, bien sûr, parce qu’il a trouvé quelque chose ! En plus, il faut voir ce qui a été découvert... Vous croyez que le gars qui a inventé la bombe atomique est heureux ? Je ne suis pas un “trouveur”, je suis un chercheur !
Franchement, est-ce qu’on peut faire preuve d’ouverture d’esprit sans avoir à se prendre la tête avec l’obligation de résultat ? »
Le comédien Luc Chareyron, trublion mi-savant mi-poète, s’interroge sur le surnaturel et la pensée rationnelle. Que savons-nous ? Qui devons-nous croire ? Dans son spectacle, le comédien nous propose son interprétation personnelle de la mécanique quantique, nous expliquant par exemple comment le Père Noël parvient à livrer plus de 300 000 tonnes de cadeaux en une nuit ! La superposition quantique peut-elle expliquer cet incroyable tour de force ?
Informations pratiques
Horaires : Ouverture des portes à 19:30, début de l'événement à 20:00. Durée: 1h30
Lieu : Portail de la science, Auditorium Sergio Marchionne
Langue : français
Inscription : événement gratuit, inscription obligatoire via ce lien.
Petite restauration
Avant le début de l’événement, le Big Bang Café sera ouvert et vous accueillera jusqu'à 20h00. Profitez d’une petite restauration avec sandwichs et boissons pour bien démarrer la soirée.
'Les Dieux et le Père Noël : vers une solution quantique'
Quantum Comedy
‘Researchers who seek, we can find. Researchers who find things, we look for them! Do you think that's funny? Well, it's not! A researcher who has found something is first and foremost a researcher who no longer has a job. He's unemployed, of course, because he's found something! What's more, you have to see what you find... Do you think the guy who found the atomic bomb is happy? I'm not a ‘finder’, I'm a researcher!
Frankly, can we still open our minds without banging our heads against the obligation to achieve results?'
As a scientific-poetic troublemaker, comedian Luc Chareyron asks questions about supernatural vs rational thinking. What do we know? Who should we believe? He does so through his own interpretation of quantum mechanics, such as his explanation about how Santa can deliver over 300,000 tonnes of presents in one night! Can quantum superposition explain this incredible achievement?
Practical information
Time: Doors opening at 19.30, event starts at 20.00. Duration: 1h30.
Location: CERN Science Gateway, Auditorium Sergio Marchionne
Language: French
Registration: Free of charge, mandatory registration by clicking here.
Refreshments
Prior to the event, the Big Bang café will stay open until 20.00. Enjoy a light meal with sandwiches and drinks for a great start to the evening.
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Heavy Neutral Lepton summary plots
No full textThis note presents plots summarizing the latest ATLAS 95% confidence level exclusion limits on a Majorana Heavy Neutral Lepton mixing with a single lepton flavour. Plots for both the electron and muon mixing scenarios are shown
LHCb A nuclei identification and production programme at LHCb
No full textLeveraging on the excellent performance of the LHCb spectrometer and on the flexibility of its online reconstruction, new methods for the identification of deuteron and helium nuclei have been developed at LHCb. These innovative methods, based on LHCb time of flight capabilities and on energy loss discrimination in the LHCb detectors, open a new window of possible measurements at LHCb. A nearly background-free sample of more than helium candidates is identified and used to reconstruct (anti)hypertriton production, while (anti)helium from (anti)Lambda-b decays are also studied. In fixed-target beam-gas collisions, deuterons at low momentum are identified with high precision. In both cases, a rich programme of QCD and astrophysics interest, exemplifying LHCb flexibility in exploring new research fields, is foreseen