515664 research outputs found
Sort by
LLWI2025 - Searches for Exotic Heavy Resonances with the ATLAS detector
No full textMany new physics models predict the existence of new, heavy particles. This talk summarises recent ATLAS searches for Beyond-the-Standard-Model heavy resonances which decay to pairs of quarks, or leptons, using Run 2 data collected at the LHC
Electroweak measurements of multiboson production with the ATLAS experiment
No full textElectroweak measurements of multiboson production provide a unique glance at the self-interactions of the electroweak gauge bosons, which are described by the electroweak symmetry breaking mechanism of the Standard Model. This proceeding reports the latest multiboson production measurements of the ATLAS Collaboration, making use of the proton-proton collision data at a center-of-mass energy of and obtained in Run-2 and early Run-3 of the Large Hadron Collider. Recent analyses include diboson production measurements of and production which particularly focus on the gauge boson polarization states. Further analyses of and production with two additional jets as well as the scattering of a boson and a photon constrain contributions of anomalous quartic gauge couplings. In the search for a doubly charged Higgs boson , a local excess of events over the Standard Model prediction is observed for a mass near , with a global significance of 2.5 standard deviations. Overall, all results are in good agreement with Standard Model predictions
Status and outlook of quark flavour physics
No full textIn recent years there has been impressive progress in quark flavour physics, with current efforts tackling complicated quantities such as for example inclusive decays, decays to QCD-unstable final states and radiative decays. At the same time current lattice flavour physics results are receiving a lot of attention from outside the lattice community. This requires careful scrutiny, even for well explored quantities. In this plenary contribution I review the status of flavour physics observables and, in the context of heavy flavours, suggest possible benchmark quantities that could allow to better compare intermediate results. These can in turn be used to investigate the origin of existing (and possible future) tensions
Heterogeneous reconstruction of hadronic particle flow clusters with the Alpaka Portability Library
No full textIn response to increasing data challenges, CMS has adopted the use of GPU offloading at the High-Level Trigger (HLT). However, GPU code is often hardware specific, and increases the maintenance burden on software development. The Alpaka (Abstraction Library for Parallel Kernel Acceleration) portability library offers a solution to this issue, and has been implemented into the CMS software (CMSSW) for use online at HLT. A portion of the final-state particle candidate reconstruction algorithm, Particle Flow, represented a target for increased performance through parallel operation. We discuss the port of hadronic Particle Flow clustering to Alpaka, and the validation of physics and performance at HLT for 2024 data taking
LumiDays 25
No full text• DCCT, FBCT, BSRL: performance, issues, new developments.
• also: BPTX @ IP1 & IP5, w/ applicable functionalities; BQM
• also: 1-2 slides on planned HL-LHC upgrades of the beam
instrumentation relevant to bunch-current measurements
LumiDays 25
No full text2-D vdM, beam-beam imaging and LRE analyses
• Including CMS results from the NF MD
LumiDays 25
No full text2-D vdM and LRE analyses
• Including ATLAS results from the NF MD?
• Include some ALICE LRE results if so requeste
LumiDays 25
No full textFor instance:
• in pp: Z-, but also J/psi- & Upsilon- counting
• in PbPb: UPC dimuons (CMS)
• in PbPb: photonuclear signatures in the ZDC
Evidence for longitudinally polarized bosons in the electroweak production of same-sign boson pairs in association with two jets in collisions at TeV with the ATLAS detector
No full textThis Letter reports the first evidence of production of same-sign boson pairs where at least one of the bosons is longitudinally polarized and the most stringent constraint to date for the production of two longitudinally polarized same-sign bosons. The data set used corresponds to an integrated luminosity of 140 fb of proton-proton collisions at a center-of-mass energy of 13 TeV, collected with the ATLAS detector during Run 2 of the Large Hadron Collider. The study is performed in final states including two same-sign leptons (electrons or muons), missing transverse momentum, and at least two jets with a large invariant mass and a large rapidity difference. Two independent fits are performed targeting the production of same-sign bosons with at least one, or two longitudinally polarized bosons. The observed (expected) significance of the production with at least one longitudinally polarized boson is 3.3 (4.0) standard deviations. An observed (expected) 95% confidence level upper limit of 0.45 (0.70) fb is reported on the fiducial production cross section of two longitudinally polarized same-sign bosons.This Letter reports the first evidence of electroweak production of same-sign W boson pairs where at least one of the W bosons is longitudinally polarized and the most stringent constraint to date for the production of two longitudinally polarized same-sign W bosons. The dataset used corresponds to an integrated luminosity of 140 fb-1 of proton-proton collisions at a center-of-mass energy of 13 TeV, collected with the ATLAS detector during run 2 of the Large Hadron Collider. The study is performed in final states including two same-sign leptons (electrons or muons), missing transverse momentum, and at least two jets with a large invariant mass and a large rapidity difference. Two independent fits are performed targeting the production of same-sign W bosons with at least one, or two longitudinally polarized W bosons. The observed (expected) significance of the production with at least one longitudinally polarized W boson is 3.3 (4.0) standard deviations. An observed (expected) 95% confidence level upper limit of 0.45 (0.70) fb is reported on the fiducial production cross section of two longitudinally polarized same-sign W bosons.This Letter reports the first evidence of production of same-sign boson pairs where at least one of the bosons is longitudinally polarized and the most stringent constraint to date for the production of two longitudinally polarized same-sign bosons. The data set used corresponds to an integrated luminosity of 140 fb of proton-proton collisions at a center-of-mass energy of 13 TeV, collected with the ATLAS detector during Run 2 of the Large Hadron Collider. The study is performed in final states including two same-sign leptons (electrons or muons), missing transverse momentum, and at least two jets with a large invariant mass and a large rapidity difference. Two independent fits are performed targeting the production of same-sign bosons with at least one, or two longitudinally polarized bosons. The observed (expected) significance of the production with at least one longitudinally polarized boson is 3.3 (4.0) standard deviations. An observed (expected) 95% confidence level upper limit of 0.45 (0.70) fb is reported on the fiducial production cross section of two longitudinally polarized same-sign bosons
, 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 140 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 .We 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