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Search for emerging jets in collisions at TeV with the ATLAS experiment
No full textA search is presented for emerging jets using 140 fb of proton-proton collision data at TeV, collected by the ATLAS experiment between 2015 and 2018. The search looks for the existence of a dark sector with symmetries similar to those in quantum chromodynamics. This dark sector is populated with dark quarks, which undergo showering similar to quarks in the Standard Model, leading to a high multiplicity of long-lived dark hadrons within a dark jet. These dark hadrons subsequently decay to Standard Model particles via a new heavy scalar mediating particle . This results in jets which contain multiple displaced vertices, known as emerging jets. This analysis targets four-jet topologies, with two emerging jets and two Standard Model jets, resulting from the decay of pair-produced scalar mediators. No significant excess above the Standard Model background is observed. For dark pion proper decay lengths of 20 mm, mediator masses are excluded between 1 TeV and 2 TeV assuming a dark pion mass of 20 GeV
Bulk and Surface Reactivity of LiNiMnO in Contact with (Acidic) Water
No full textLithium-ion battery cathode materials such as LiNi0.5Mn1.5O4 (LNMO) are very sensitive to water, which has so far hindered the successful commercialization of aqueous electrode processing strategies. Herein, a detailed investigation of the surface and bulk reactivity of ordered LNMO with water and an aqueous solution of phosphoric acid to decipher the reaction mechanism and the impact on the eventual electrochemical behavior is presented. The comprehensive analysis via, for instance, neutron diffraction and synchrotron X-Ray diffraction, X-Ray absorption spectroscopy, magic-angle spinning nuclear magnetic resonance spectroscopy, thermogravimetric analysis coupled with mass spectrometry, high-resolution transmission electron microscopy, and X-Ray photoelectron spectroscopy reveals that the (acidic) water treatment particularly affects a very thin layer at the particle surface, while the bulk material remains largely unaffected. Nonetheless, when processed classically with N-methyl-2-pyrrolidone and polyvinylidene fluoride into electrodes, the significant impact of this layer on the electrochemical behavior highlights the important impact of the material surface on the eventually achievable performance in battery cells
HL-LHC prospects for the measurement of triple-Higgs production in the 6b final state at the ATLAS experiment
No full textProjection studies of the ATLAS Run 2 search for non-resonant triple Higgs production in the final state are presented to highlight the expected performance achievable at the High Luminosity LHC. Sensitivities are projected assuming a center-of-mass energy of 14 TeV for a variety of integrated luminosities ranging from 1000 to 3000 fb. Results are presented in terms of upper limits on the signal strength, as well as simultaneous constraints on the Higgs self-coupling modifiers. Constraints on the quartic Higgs self-coupling modifier , directly accessible via production at the LHC, are also presented when fixing the Higgs trilinear coupling modifier to the SM. Various scenarios of reduced systematic uncertainties are also considered, which highlight the impact of improvements in experimental modeling and theoretical predictions. Furthermore, the impact of improved -tagging algorithms on the analysis in the final state is studied. With (without) systematic uncertainties, the expected 95% CL exclusion limit on is set to 109 (99) times the SM prediction, while the 95% confidence interval for assuming is [-84, 96] ([-79, 90]), for a total integrated luminosity of 3000~fb. Simultaneous constraints on the Higgs self-coupling modifiers are reported in all extrapolation scenarios, showing that the HL-LHC dataset will allow the exclusion of an increasingly significant portion of the parameter phase space within the perturbative unitarity bounds
Projected sensitivity of measurements of Higgs boson pair production with the ATLAS experiment at the HL-LHC
No full textProspects for the sensitivity of measurements to Higgs boson pair production with the ATLAS detector at the High Luminosity LHC (HL-LHC) are presented, obtained from a statistical combination of extrapolated results from six analyses of the Run 2 dataset, that used 126–140 fb of data at = 13 TeV. Under the baseline extrapolation scenario for an integrated luminosity of 3000 fb at = 14 TeV, the discovery significance of Standard Model Higgs boson pair production is found to be 4.26, increasing to 5.98 if systematic uncertainties are neglected. In the baseline scenario, the self-coupling strength modifier, , is expected to be measured as , and the coupling modifier affecting the interaction between two Higgs bosons and two vector bosons is expected to be measured as . These results represent a substantially improved outlook for production at the HL-LHC compared to previous studies
Deriving constraints on long-lived axion-like particles from existing searches for exotic decays of the Higgs boson with the ATLAS detector
No full textTwo ATLAS searches for anomalous decays of the Higgs boson into pseudo-scalar particles are used to set exclusion limits for models containing decays to long-lived axion-like particles (ALPs). Both searches use the full Run~2 data set of of proton-proton collisions at a centre-of-mass energy of recorded by the ATLAS experiment. The first search involves the decay of the Higgs boson to a boson and a light pseudo-scalar particle promptly decaying to two photons, where in this note long-lived ALPs with masses in the range 2-33 GeV and effective ALP-photon couplings, , as small as are excluded. The second search involves the decay of the Higgs boson to a pair of pseudo-scalar particles with finite lifetimes each decaying to two photons, where in this note ALPs with low masses in the range 0.01-0.1 GeV and effective ALP-photon couplings as small as are excluded. Upper limits at 95% confidence level are provided on both the branching ratio of the Higgs boson to a boson and a non-promptly decaying ALP, and to a pair of non-promptly decaying ALPs, with values in the range 0.05%-20% depending on the ALP mass and couplings
VERITAS and Multiwavelength Observations of the Blazar B3 2247+381 in Response to an IceCube Neutrino Alert
No full textWhile the sources of the diffuse astrophysical neutrino flux detected by the IceCube Neutrino Observatory are still largely unknown, one of the promising methods to improve our understanding of them is investigating the potential temporal and spatial correlations between neutrino alerts and the electromagnetic radiation from blazars. We report on the multiwavelength target-of-opportunity observations of the blazar B3 2247+381, taken in response to an IceCube multiplet alert for a cluster of muon neutrino events compatible with the source location between 2022 May 20 and 2022 November 10. B3 2247+381 was not detected with VERITAS during this time period. The source was found to be in a low-flux state in the optical, ultraviolet, and gamma-ray bands for the time interval corresponding to the neutrino event, but was detected in the hard X-ray band with NuSTAR during this period. We find the multiwavelength spectral energy distribution is described well using a simple one-zone leptonic synchrotron self-Compton radiation model. Moreover, assuming the neutrinos originate from hadronic processes within the jet, the neutrino flux would be accompanied by a photon flux from the cascade emission, and the integrated photon flux required in such a case would significantly exceed the total multiwavelength fluxes and the VERITAS upper limits presented here. The lack of flaring activity observed with VERITAS, combined with the low multiwavelength flux levels, as well as the significance of the neutrino excess being at a 3σ level (uncorrected for trials), makes B3 2247+381 an unlikely source of the IceCube multiplet. We conclude that the neutrino excess is likely a background fluctuation
Measurements and interpretation of the Higgs boson differential and production mode cross sections in the channel at TeV with the ATLAS detector
No full textHiggs boson production cross-sections are measured in the decay channel based on 56 fb of proton-proton collision data produced at the Large Hadron Collider at a centre-of-mass energy of 13.6 TeV and recorded by the ATLAS detector in 2022 and 2023. Inclusive fiducial and total cross-sections are measured in addition to differential cross-sections for the four-lepton transverse momentum and rapidity, the invariant mass of the off-shell lepton pair and the jet multiplicity. Furthermore, production cross-sections for individual Higgs boson production modes are probed for the first time at this centre-of-mass energy. All measurements are in agreement with the Standard Model predictions. The results are interpreted within the frameworks of Higgs boson coupling modifiers and the Standard Model Effective Field Theory. Notably, a statistical combination with TeV Run 2 data is performed for the first time within the coupling modifier framework
Investigating a two-level algorithm for fermionic observables
No full textWe investigate the combination of a two-level sampling algorithm with distillation techniques to compute disconnected fermionic correlation functions. The method relies on a factorization of the quark propagator into domain-local contributions that depend only on the gauge fields within overlapping temporal regions, enabling independent submeasurements of each term through a two-level sampling strategy. The two-level estimators exhibit the expected scaling of the variance, up to exponential boundary effects, and achieve an exponential reduction of statistical errors at a modest additional computational cost, which is negligible compared to the resulting gain in statistical precision. The method is tested on pure gauge ensembles, providing a controlled benchmark for its forthcoming application to dynamical QCD studies of glueball and isosinglet meson correlation functions
Seasonal variations of the atmospheric muon neutrino spectrum measured with IceCube
No full textThis study presents an analysis of seasonal variations in the atmospheric muon neutrino flux, using 11.3 years of data from the IceCube Neutrino Observatory. By leveraging a novel spectral unfolding method, we explore the energy range from 125 GeV to 10 TeV for zenith angles from to , corresponding to the Antarctic atmosphere. Our findings reveal that the differential measurement of the amplitudes of the seasonal variation is consistent with an energy-dependent decrease reaching ( ± 1.2)% during Austral winter and increase to (+ 3.9 ± 1.3)% during Austral summer relative to the annual average at 10 TeV. While the unfolded flux exceeds the model predictions by up to 30%, the differential measurement of the seasonal to annual average flux remains unaffected. The measured seasonal variations of the muon neutrino spectrum are consistent with theoretical predictions using the MCEq code and the NRLMSISE-00 atmospheric model
A Modern Reconstruction and Analysis Framework for the ILD ZHH Study
No full textMeasuring the Higgs potential represents one of the main goals of the physics programs of future colliders. At center-of-mass energies of , direct access to the self-coupling is enabled through the ZHH process. The ongoing update of the ILD ZHH analysis focuses on the final state . In our contribution, we discuss recent advancements in event reconstruction, namely in the identification of heavy-quark jets as well as the kinematic reconstruction using corrections of semileptonic decays, kinematic fits and observables based on matrix elements. By basing our analysis on a modern distributed pipelining system (luigi+law), we achieve a highly scalable, automated and fast workflow. Composed of the full chain from event generation, fast simulation, reconstruction and analysis, the workflow can be executed in one go. Through columnar analysis, the event selection is greatly accelerated. We could process O(100M) events in a few hours with O(1000) available nodes