67 results match your criteria: "Stefan Meyer Institute for Subatomic Physics[Affiliation]"

Article Synopsis
  • The CMS experiment conducted a search for charge-parity violation in decays using proton-proton collision data from 2018, analyzing around 10 billion events with b hadrons decaying into charm hadrons.
  • The flavor of the neutral D meson was determined through the charge of pions in the reconstructed decays, and an asymmetry measurement in the decays was reported, taking into account various uncertainties.
  • This research marks the first asymmetry measurement by the CMS in the charm sector and the first to use a fully hadronic final state in such analyses.
View Article and Find Full Text PDF

The mechanism of antiproton-nucleus annihilation at rest is not fully understood, despite substantial previous experimental and theoretical work. In this study we used slow extracted antiprotons from the ASACUSA apparatus at CERN to measure the charged particle multiplicities and their energy deposits from antiproton annihilations at rest on three different nuclei: carbon, molybdenum and gold. The results are compared with predictions from different models in the simulation tools Geant4 and FLUKA.

View Article and Find Full Text PDF
Article Synopsis
  • * The motivation for this research lies in the higher densities expected from hydrogen, as well as its accessibility for studying potential short-range interactions.
  • * The article reports on advancements in methods that reduce background noise and enhance detection of low-velocity atoms, providing results such as improved beam collimation and successful atom detection for the experiment.
View Article and Find Full Text PDF

Using proton-proton collision data corresponding to an integrated luminosity of collected by the CMS experiment at , the decay is observed for the first time, with a statistical significance exceeding 5 standard deviations. The relative branching fraction, with respect to the decay, is measured to be , where the first uncertainty is statistical, the second is systematic, and the third is related to the uncertainties in and .

View Article and Find Full Text PDF

Testing the Pauli Exclusion Principle across the Periodic Table with the VIP-3 Experiment.

Entropy (Basel)

September 2024

Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare (INFN), Via E. Fermi 54, I-00044 Rome, Italy.

The Pauli exclusion principle (PEP), a cornerstone of quantum mechanics and whole science, states that in a system, two fermions can not simultaneously occupy the same quantum state. Several experimental tests have been performed to place increasingly stringent bounds on the validity of PEP. Among these, the series of VIP experiments, performed at the Gran Sasso Underground National Laboratory of INFN, is searching for PEP-violating atomic X-ray transitions in copper.

View Article and Find Full Text PDF
Article Synopsis
  • Demand for computing power in major scientific experiments, like the CMS at CERN, is expected to significantly increase over the coming decades.
  • The implementation of coprocessors, particularly GPUs, in data processing workflows can enhance performance and efficiency, especially for machine learning tasks.
  • The Services for Optimized Network Inference on Coprocessors (SONIC) approach allows for improved use of coprocessors, demonstrating successful integration and acceleration of workflows across various environments without sacrificing throughput.
View Article and Find Full Text PDF

A measurement is presented of a ratio observable that provides a measure of the azimuthal correlations among jets with large transverse momentum . This observable is measured in multijet events over the range of - based on data collected by the CMS experiment in proton-proton collisions at a centre-of-mass energy of 13 , corresponding to an integrated luminosity of 134 . The results are compared with predictions from Monte Carlo parton-shower event generator simulations, as well as with fixed-order perturbative quantum chromodynamics (pQCD) predictions at next-to-leading-order (NLO) accuracy obtained with different parton distribution functions (PDFs) and corrected for nonperturbative and electroweak effects.

View Article and Find Full Text PDF

A study of the anomalous couplings of the Higgs boson to vector bosons, including -violation effects, has been conducted using its production and decay in the WW channel. This analysis is performed on proton-proton collision data collected with the CMS detector at the CERN LHC during 2016-2018 at a center-of-mass energy of 13 TeV, and corresponds to an integrated luminosity of 138 . The different-flavor dilepton final state is analyzed, with dedicated categories targeting gluon fusion, electroweak vector boson fusion, and associated production with a W or Z boson.

View Article and Find Full Text PDF

A search for and production in the final state is presented, where H is the standard model (SM) Higgs boson. The search uses an event sample of proton-proton collisions corresponding to an integrated luminosity of 133 collected at a center-of-mass energy of 13 with the CMS detector at the CERN LHC. The analysis introduces several novel techniques for deriving and validating a multi-dimensional background model based on control samples in data.

View Article and Find Full Text PDF

VIP-2 with modulated current: pathfinder for enhanced Pauli exclusion principle violation studies.

Eur Phys J C Part Fields

March 2024

Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare, Via Enrico Fermi 54, 00044 Frascati, Italy.

Fermions are subject to the Pauli Exclusion Principle (PEP), which is grounded on the spin-statistics theorem and, hence, related to the very same structure of the underlying symmetries. The VIP-2 (VIolation of Pauli exclusion principle - 2) experiment has been performing extreme sensitivity tests of the PEP, up to its current and final configuration, exploiting several experimental setups designed to study different theoretical models of PEP violation, looking for a faint signal of physics Beyond the Standard Model.A current is introduced in the copper target to bring new electrons into the system and, hence, fulfill the requirements of the Messiah-Greenberg Super-Selection rule.

View Article and Find Full Text PDF

A search for exotic decays of the Higgs boson () with a mass of 125 to a pair of light pseudoscalars is performed in final states where one pseudoscalar decays to two quarks and the other to a pair of muons or leptons. A data sample of proton-proton collisions at corresponding to an integrated luminosity of 138 recorded with the CMS detector is analyzed. No statistically significant excess is observed over the standard model backgrounds.

View Article and Find Full Text PDF
Article Synopsis
  • - The study investigates the strange quark content of protons by measuring the production cross section of W bosons and charm quarks in proton-proton collisions at 13 TeV, using data from the CMS detector at the LHC.
  • - W bosons are identified through their decays into leptons (electrons or muons) and neutrinos, while charm quarks are tagged by detecting muons or secondary vertices in jets.
  • - The measurements, which reach a precision of 1%, include both inclusive and differential analyses based on the transverse momentum and pseudorapidity of the leptons, and the results are compared with advanced theoretical predictions in quantum chromodynamics.
View Article and Find Full Text PDF

The measurement of Z boson production is presented as a method to determine the integrated luminosity of CMS data sets. The analysis uses proton-proton collision data, recorded by the CMS experiment at the CERN LHC in 2017 at a center-of-mass energy of 13. Events with Z bosons decaying into a pair of muons are selected.

View Article and Find Full Text PDF

Experimental perspectives on the matter-antimatter asymmetry puzzle: developments in electron EDM and [Formula: see text] experiments.

Philos Trans A Math Phys Eng Sci

February 2024

Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Université, Collège de France, Paris 75252, France.

In the search for clues to the matter-antimatter puzzle, experiments with atoms or molecules play a particular role. These systems allow measurements with very high precision, as demonstrated by the unprecedented limits down to [Formula: see text] e cm on electron EDM using molecular ions, and relative measurements at the level of [Formula: see text] in spectroscopy of antihydrogen atoms. Building on these impressive measurements, new experimental directions offer potential for drastic improvements.

View Article and Find Full Text PDF

The mass of the top quark is measured in 36.3 of LHC proton-proton collision data collected with the CMS detector at . The measurement uses a sample of top quark pair candidate events containing one isolated electron or muon and at least four jets in the final state.

View Article and Find Full Text PDF

A search for decays to invisible particles of Higgs bosons produced in association with a top-antitop quark pair or a vector boson, which both decay to a fully hadronic final state, has been performed using proton-proton collision data collected at by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138. The 95% confidence level upper limit set on the branching fraction of the 125 Higgs boson to invisible particles, , is 0.54 (0.

View Article and Find Full Text PDF

A compact low energy proton source.

Rev Sci Instrum

October 2023

Stefan-Meyer-Institute for Subatomic Physics, Austrian Academy of Sciences, Kegelgasse 27, 1030 Wien, Austria.

A low energy proton source for non-neutral plasma experiments was developed. Electrons from a hot filament ionize H2 gas inside a geometrically compensated Penning trap to produce protons via dissociative ionization. A rotating wall electric field destabilizes the unwanted H2+ and H3+ generated in the process while concentrating protons at the center of the trap.

View Article and Find Full Text PDF

Multijet events at large transverse momentum () are measured at using data recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of . The multiplicity of jets with that are produced in association with a high- dijet system is measured in various ranges of the of the jet with the highest transverse momentum and as a function of the azimuthal angle difference between the two highest jets in the dijet system. The differential production cross sections are measured as a function of the transverse momenta of the four highest jets.

View Article and Find Full Text PDF

The production of Z bosons associated with jets is measured in collisions at with data recorded with the CMS experiment at the LHC corresponding to an integrated luminosity of 36.3. The multiplicity of jets with transverse momentum is measured for different regions of the Z boson's , from lower than 10 to higher than 100.

View Article and Find Full Text PDF

Production cross sections of the standard model Higgs boson decaying to a pair of W bosons are measured in proton-proton collisions at a center-of-mass energy of 13. The analysis targets Higgs bosons produced via gluon fusion, vector boson fusion, and in association with a W or Z boson. Candidate events are required to have at least two charged leptons and moderate missing transverse momentum, targeting events with at least one leptonically decaying W boson originating from the Higgs boson.

View Article and Find Full Text PDF

The double differential cross sections of the Drell-Yan lepton pair (, dielectron or dimuon) production are measured as functions of the invariant mass , transverse momentum , and . The observable, derived from angular measurements of the leptons and highly correlated with , is used to probe the low- region in a complementary way. Dilepton masses up to 1 are investigated.

View Article and Find Full Text PDF

New sets of parameter tunes for two of the colour reconnection models, quantum chromodynamics-inspired and gluon-move, implemented in the pythia  8 event generator, are obtained based on the default CMS pythia  8 underlying-event tune, CP5. Measurements sensitive to the underlying event performed by the CMS experiment at centre-of-mass energies and 13, and by the CDF experiment at 1.96 are used to constrain the parameters of colour reconnection models and multiple-parton interactions simultaneously.

View Article and Find Full Text PDF

A measurement of the jet mass distribution in hadronic decays of Lorentz-boosted top quarks is presented. The measurement is performed in the lepton + jets channel of top quark pair production () events, where the lepton is an electron or muon. The products of the hadronic top quark decay are reconstructed using a single large-radius jet with transverse momentum greater than 400.

View Article and Find Full Text PDF

A search is reported for pairs of light Higgs bosons () produced in supersymmetric cascade decays in final states with small missing transverse momentum. A data set of LHC collisions collected with the CMS detector at and corresponding to an integrated luminosity of 138 is used. The search targets events where both bosons decay into pairs that are reconstructed as large-radius jets using substructure techniques.

View Article and Find Full Text PDF

Topological charge-sharing background reduction for the Silicon Drift Detectors used by the VIP experiment at LNGS.

Appl Radiat Isot

July 2023

Laboratori Nazionali di Frascati, INFN, Frascati (Rome), Italy; IFIN-HH, Institutul National pentru Fizica si Inginerie Nucleara Horia Hulubei, Măgurele, Romania.

Large area Silicon Drift Detectors are employed in high sensitivity tests of the Pauli Exclusion Principle by the VIP-2 Collaboration. The experiment is operated in the extremely low cosmic background environment of the Gran Sasso underground National Laboratory of INFN. In this work an off-line analysis method is proposed which provides an additional background reduction, as well as a better calibration procedure.

View Article and Find Full Text PDF