• 05.07.2018
  • Medienmitteilung
  • Meldung
  • CHIPP

NEWS from ICHEP2018, SEOUL, Korea

Maxime Schubiger (EPFL) on behalf of the LHCb collaboration at ICHEP2018
Bild: Maxime Schubiger, EPFL, Switzerland
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Maxime Schubiger (EPFL) on behalf of the LHCb collaboration at ICHEP2018
Maxime Schubiger (EPFL) on behalf of the LHCb collaboration at ICHEP2018 (Bild: Maxime Schubiger, EPFL, Switzerland)

Many Swiss physicists are now in Seoul (Korea) for the very prestigious conference ICHEP2018. We report here their latest findings and contributions to the conference.

TODAY:

Steven Schramm (University of Geneva) on behalf of the ATLAS collaboration presents the POSTER:


Triggering on hadronic signatures in ATLAS

Steven presents the updated status of triggers for jets, b-jets, and missing transverse momentum (ideally corresponding to invisible particles) with the ATLAS detector. All areas have been significantly improved since the 2016 running period, including new developments which are sufficient to keep up with the excellent LHC performance and its luminosity two times larger than the design value.

In addition to handling the higher than expected input rate of interesting physics processes, new techniques have improved the trigger performance and capabilities. Triggers for difficult topologies have been improved and their excellent performance has increased the physics capabilities of the ATLAS experiment.

The full presentation can be found in: link

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Maxime Schubiger (EPFL) on behalf of the LHCb collaboration:

Direct CP violation in charm at LHCb

Maxime presents the CP violation meausurement and searches in LHCb. CP violation is needed to explain our matter dominated universe, it has already been observed in kaons and B mesons, but not yet in charm mesons. Since its prediction from the Standard Model is really small, any observation could be a hint for physics beyond the Standard Model. A highlight of three recent searches for CPV in charm at LHCb has been presented.

The full presentation can be found in: link

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Laura Molina Bueno on behalf of the LArTPC group of ETHZ

Performance of the 3x1x1 m3 Dual Phase Liquid argon TPC

Laura presents the Liquid Argon Time Projection Chamber (LAr TPC) that is currently the most attractive technology for neutrino oscillations studies. Not only LAr TPCs are cost-effective and scalable to multi-ton scales, but they are also excellent calorimeters and are able to 3D reconstruct the tracks of ionising particles arising from neutrinos decay products. Future giant liquid Argon TPCs, at the ten-kiloton level, are now at the design and prototyping stage in the context of the Deep Underground Neutrino Experiment (DUNE). DUNE will comprise four 10 kton LAr TPC modules placed at the Sanford Underground Research Facility (SURF) in South Dakota (USA). Two different technologies will be tested: single phase and dual phase. The dual phase operation allows to amplify and readout the signal offering several advantages over the single phase. The first step towards large scale Dual-Phase LAr TPCs has been the commissioning and operation of a 3x1x1 m3 detector at CERN with 4.2 tons of Argon. The construction, commissioning, performance and first results achieved with this detector will be addressed in this talk.

The full presentation can be found in: link

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Vittorio Raoul Tavolaro (ETH Zurich) on behalf of the CMS collaboration:

Fiducial inclusive and differential Higgs boson cross sections at CMS

Vittorio presents the measurement of fiducial inclusive and differential Higgs boson cross sections allows the study of its properties under a minimal set of assumptions. By defining a fiducial phase-space, the uncertainties due to model dependence and extrapolations are minimized. A new, extended set of measurements performed using 35.9/fb of pp collisions collected by the CMS experiment at LHC in 2016 is presented. The measurements, obtained in the diphoton and ZZ decay channels, cover a wide range of differential observables, describing the kinematic properties of the Higgs boson, of its decay products and of particles produced in association with it. Fiducial measurements targeting individual production mechanisms are also presented.

The full presentation can be found in:link

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Luca Pescatore (EPFL) on behalf of the LHCb collaboration presents:

Status of outreach activities at LHCb

Luca presents the many efforts done by the LHCb collaboration to interest the general public to physics with the public page news, Instagram, Facebook and online event display.

Masterclasses activities for school boys and girls cover the whole planet. The surface exhibition above the LHCb proton-proton collision point is being constantly developed. Cameras in the control room allow Virtual Visits of the LHCb experiment. Laser scan of LHCb detector is performed to archive its 3D images as an important heritage for humanity. These images will also be used to develop 3D Virtual Reality files for visitors and schools. New film covering a major LHCb discovery is finalized.

The full presentation can be found in: link

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Leonora Vesterbacka (ETH Zurich (CH)) on behalf of the CMS collaboration:

Performance of missing transverse momentum reconstruction at the CMS detector in 13 TeV data

The precise measurement of the missing transverse momentum (MET) observable is critical for standard model measurements involving W, Z, and the Higgs bosons, and top quarks. In addition, MET is one of the most important kinematic observable used in searches for physics beyond the standard model targeting new weakly interacting neutral particles. A detailed understanding of various effects due to the high collision rate at the CMS detector during the 13 TeV data-taking period of the LHC both in data and simulation is important to achieve the most optimal MET performance. In this talk, we will present the studies of MET reconstruction algorithms using the CMS detector at the LHC.

The full presentation can be found in: link

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5th July 2018

Today a talks for Steven Schramm who was directly invitated by the conference organizers and his poster:

Steven Schramm (University of Geneva) on behalf of the ATLAS and LHCb collaborations presents:


Machine learning at CERN

Steven presents the rapidly evolving field of Machine Learning as applied to particle physics, with a primary emphasis on the ATLAS and LHCb collaborations. Both collaborations are developing ever more advanced techniques to exploit their growing datasets, with machine learning used in all of their recent significant discoveries, from the Higgs boson and its properties at ATLAS to pentaquarks at LHCb.

Machine learning usage is also diversifying in both collaborations, including applications in triggering, reconstruction, calibration, object identification/tagging, data quality monitoring, and more! The breadth of machine learning techniques is growing, and the "deep learning" revolution is underway. Machine learning usage is only expected to increase as the datasets grow and machine learning techniques continue to improve.

The full presentation can be found in: link

Andrea Mauri (U. Zurich) on behalf of the LHCb collaboration:

Towards establishing New Physics in B0→K∗0ℓ+ℓ− decays

Andrea presents the work done in LHCb to study rare semileptonic b→sℓ+ℓ− transitions, this provides some of the most promising framework to search for New Physics effects.
Recent analyses have indicated an anomalous pattern in measurements of lepton-flavour-universality observables.
We propose a novel approach to independently and complementary clarify the nature of these effects
by performing a simultaneous amplitude analysis of B0→K∗0μ+μ− and B0→K∗0e+e− decays.
This method allows the direct determination of the difference of the Wilson Coefficients 9 and 10 between electrons and muons, and are found to be insensitive to both local and non-local hadronic contributions.
We show that considering the current preferred New Physics scenario a first observation of LFU breaking in a single measurement is possible with LHCb Run-II dataset.

The full presentation can be found in: link

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Searches for Lepton Flavour Violating decays at LHCb

Luca Pescatore (EPFL) on behalf of the LHCb collaboration

Luca presents the recent hints for lepton-universality violation in b->clnu and b->sll transitions that could imply the existence of lepton-flavour violating B decays. The LHCb experiment is well suited for the search for these decays due to its large acceptance and trigger efficiency, as well as its excellent invariant mass resolution and particle identification capabilities. Recent results on searches for lepton-flavour violating decays from the LHCb experiment will be presented.

The Full presentation can be found in: link

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CMS electron and photon performance at 13 TeV

Francesco Micheli (ETHZ) on behalf of the CMS collaboration

Francesco presents the full process of electron and photon reconstruction in CMS, starting from tracker hits and energy deposits in the electromagnetic calorimeter, the method to achieve the ultimate precision in Run II energy measurements, the trigger and identification strategies (based both on cut based approach and on multivariate analysis) to discriminate prompt electrons and photons from background, and the methods to estimate the associated systematic uncertainties. Finally, he shows the performance on benchmark channels (such as H->gamma gamma and Z->ee).

The Full presentation can be found in: link

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