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, mesons from lattice QCD in fully physical conditions
No full textWe determine masses and mixing parameters of the and meson in lattice QCD. The calculations are carried out on a set of 13 ETMC gauge ensembles with (maximally) twisted-mass Clover-improved quarks. These ensemble cover four values of the lattice spacing and pion masses from to , including three ensembles at physical quark masses and six ensembles with . The strange-quark contribution is treated in a mixed-action approach using Osterwalder-Seiler fermions to avoid complications due to flavor mixing in the heavy quark sector and to enable the use of the one-end trick in the computation of strange quark-disconnected diagrams. With the strange-quark mass tuned to its physical value and several ensembles having close-to-physical light-quark mass, uncertainties related to the chiral extrapolations are reduced significantly compared to earlier studies. Physical results are computed with fully controlled systematics from a combined chiral, continuum and infinite-volume extrapolation, and a full error budget is obtained from model averages over of various fit ansätze and data cuts. Our results for the masses are given by and , respectively, where statistical and systematic errors have been added in quadrature. For the mixing angle and decay-constant parameters the Feldmann-Kroll-Stech scheme is employed to compute them from pseudoscalar matrix elements in the quark-flavor basis. For the mixing angle we obtain and our results for the decay-constant parameters are given by and
Dead cone effect and charm quark mass effects in high-pT D-jets with the CMS experiment
No full textThe mass of heavy quarks modifies the radiation pattern of heavy-quark jets in comparison to their light quark counterparts, since the heavy quark mass effectively regularizes the soft and collinear divergences that would normally dominate the partonic cascade formation. This leads to the depletion of collinear gluon emissions relative to the heavy quark, an effect known as the dead cone effect. The dead cone of heavy-quark jets has been identified as a possible venue to isolate medium-induced radiation in a phase-space region where calculations are viable and where the large underlying event of a heavy-ion collision is absent. Previous measurements based on the construction of an angle-ordered tree of intrajet emissions have shown that it is possible to expose the dead cone experimentally. Novel jet substructure observables and algorithms are used to isolate hard and collinear emissions in the dead cone region with an improved sensitivity to charm quark mass effects using -tagged jets in pp collisions at 5.02 TeV. For the first time, the substructure of charm quark jets with a greater than 100 GeV is analyzed, in a regime that should be relatively insensitive to nonperturbative effects. It is shown that the sensitivity to quark mass effects is present even at high . This result also serves as a baseline for future measurements in heavy-ion collisions
Testing the QCD formation time with reconstructed parton splittings
No full textIn high-energy elementary collisions the space-time ordering of parton branching processes is not accessible experimentally. In contrast, in heavy-ion collisions, parton showers interact with a spatially extended dense medium. This sets a reference length scale with respect to which the space-time ordering may be analysed. Here, we explore the possibility of identifying experimental signatures of the QCD formation time, , on the level of a single parton splitting. Since heavy flavour offers an additional handle on tracing the propagation of individual quarks through the medium, we focus on the splitting. Combining adapted versions of the Cambridge-Aachen and FlavourCone jet finding algorithms with grooming techniques, we show how the kinematics of such splittings can be reconstructed with high fidelity using either final state partons or hadrons, and how the formation time distribution of parton splittings can be constructed therefrom. Medium modification leads to a characteristic modification of this distribution. This effect can be used to construct experimentally-accessible ratios of distributions, in which the sensitivity of the medium modification to the QCD formation time becomes measurable
Results on top quark physics from ATLAS and CMS
No full textsummary of recent top quark physics results from ATLAS and CM
Inverted CERN School of Computing 2025
No full textAbstract/Description:
"Welcome to web dev 101! In this lecture we will go over the fundamentals (HTML, CSS, JS), tooling, overview of common UI libraries and frameworks, teach you the fundamentals of React development and testing, tldr user experience design, APIs, highlight modern features such as web assembly and WebGL.
Development of graphical user interfaces (GUIs) are often serious and timely undertaking, throughout all the different phases from the requirement gathering, design, user experience to the complexities of cross platform development with native GUI libraries. Web apps to the rescue!
Building web apps can help speed up this process and provide a platform agnostic interface for your software, which can run locally or remotely. Utilising design systems can take the pain of user interface design away allowing you to build beautiful and accessibility friendly UI components quickly. API backends can enhance the web app with capabilities to use external databases, software and programs.
Future Circular Collider Feasibility Study Report Volume 2: Accelerators, technical infrastructure and safety
No full textIn response to the 2020 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) Feasibility Study was launched as an international collaboration hosted by CERN. The FCC ‘integrated programme’, described in this report, in a first stage consists of a highest-luminosity electron-positron collider, FCC-ee, serving as Higgs, top and electroweak factory, with a subsequent energy-frontier proton-proton collider, FCC-hh, as the second stage. The FCC-ee is designed to operate at four baseline centre-of-mass energies, corresponding to the Z pole, the WW pair production threshold, the ZH production peak, and the top/anti-top production threshold, always delivering the highest possible luminosities to four experiments. Over a span of 15 years, FCC-ee will produce more than 6 trillion Z bosons, 200 million WW pairs, almost 3 million Higgs bosons, and 2 million top anti-top pairs. On the Z pole and at the WW pair threshold, the collision energy can be precisely calibrated by frequent resonant depolarisation of pilot bunches. The sequence of operation modes and beam energies is flexible, between the Z, WW and ZH substages. The hadron collider, FCC-hh, will operate at a centre-of-mass energy of about 85 TeV, extending the energy frontier by almost an order of magnitude compared with the LHC, and providing integrated luminosity 5-10 times higher than that of the upcoming High-Luminosity LHC. The mass reach for direct discovery at the FCC-hh amounts to several tens of TeV. The FCC-hh can also accommodate ion-ion, ion-hadron, and lepton-hadron collision options. This second volume of the Feasibility Study Report covers the complete design of the FCC-ee collider, the operation and staging concepts, the design of the full-energy booster and of the FCC-ee injector complex, the accelerator technologies required, safety concepts, and technical infrastructures, along with the design of the FCC-hh hadron collider, the associated high-field magnet developments, hadron injector options, and FCC-hh key technical systems
Performance of the CMS GE1/1 system at LHC Run-3 and prospects of the future ME0 system
No full textWe report on the operational performance and reliability of GE1/1, a new muon tracking and triggering station made of Triple-GEM detectors installed in the most forward region of the CMS muon spectrometer as part of the Phase-2 upgrades for LHC Run-3. The GE1/1 station, comprising 144 Triple-GEM detectors, has been collecting data since 2022. We detail its front-end electronics architecture, including VFAT3, GBTx, and VTRx components, and discuss issues encountered with VTRx transceiver outgassing and the mitigation strategies implemented. By optimizing the front-end electronics, we achieved significant improvements in time resolution, reaching 12 ns, and stabilized detector performance with 94% detection efficiency. Additionally, we provide insights into the planned ME0 station, focusing on the design advancements that will improve background rejection and timing capabilities in the forward region. These results contribute to the ongoing efforts to enhance the CMS muon detection and triggering system as the LHC luminosity increases
CERN Tape Archive Workshop : CTA 2025
No full textIn 2024, the CTA Tape Daemon was updated to address issues in deployments with multiple drives per tape server. This was a first step towards a major refactoring of the daemon, as in its current state, its multi-process architecture presents problems such as logging information unrelated to the current process and inter-process communication bugs. It also causes confusion in internal discussions and in external bug reports.
In this session, we will provide an update on the current state of the CTA Tape Daemon, explore the upcoming changes designed to reduce the daemon's complexity by removing its parent-child process architecture, and promoting the maintenance process to an independent daemon, as it doesn't perform any drive related tasks. We will conclude with a discussion of possible future developments
Diboson Measurements
No full textRecent diboson measurements are presented, including ATLAS Zy nTGC measurement and CMS WZ measurement
ATLAS Event Display: Displaced vertex search
No full textA 13 TeV collision event recorded by the ATLAS experiment in 2016, featuring two candidate muons (red lines) and tracks reconstructed in the muon spectrometer (light blue lines). Barrel and endcap monitored drift tube elements traversed by tracks are shown in blue and green, respectively. The event characteristics align with expectations from a Z-boson-associated displaced ALP decay: The Z-boson decays into a pair of muons while the ALP travels through the inner detector and calorimeters without leaving a signal. It then decays in the muon system, resulting in multiple tracks that share a common origin and are isolated from activity in more inward detector subsystems