Investigation of high temperature superconductivity and magnetism in oxide compounds by muon method

Magnetic properties of oxide compounds - high temperature superconductors of a various chemical composition are considered in the paper aiming at the investigation of local magnetic fields in YBa_2Cu_3O_6_+_x compound with the variable content of oxigen and in a superconductor of 2.2.1.2. phase. As a result the mu SR-plant has been created, distributions of local fields, temperature dependences of the penetration depths, relative volumes of superconducting and magnetic phases have been measured. The search of transitions into the state of spin glass has been held. It has been shown, that HTSC and magnetism may co-exist on the microscopic levelAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

Excitation of the Delta(1232) isobar in deuteron charge exchange on hydrogen at 1.6, 1.8, and 2.3 GeV

The charge-exchange break-up of polarised deuterons pol{d}p -> {pp}n, where the final {pp} diproton system has a very low excitation energy and hence is mainly in the 1S0 state, is a powerful tool to probe the spin-flip terms in the proton-neutron charge-exchange scattering. Recent measurements with the ANKE spectrometer at the COSY storage ring at 1.6, 1.8, and 2.27 GeV have extended these studies into the pion-production regime in order to investigate the mechanism for the excitation of the Delta(1232) isobar in the pol{d}p -> {pp}X reaction. Values of the differential cross section and two deuteron tensor analysing powers, A_{xx} and A_{yy}, have been extracted in terms of the momentum transfer to the diproton or the invariant mass Mx of the unobserved system X. The unpolarised cross section in the high Mx region is well described in a model that includes only direct excitation of the Delta isobar through undistorted one pion exchange. However, the cross section is grossly underestimated for low Mx, even when Delta excitation in the projectile deuteron is included in the calculation. Furthermore, direct Delta production through one pion exchange only reproduces the angular dependence of the difference between the two tensor analysing powers

Software and computing for Run 3 of the ATLAS experiment at the LHC

International audienceThe ATLAS experiment has developed extensive software and distributed computing systems for Run 3 of the LHC. These systems are described in detail, including software infrastructure and workflows, distributed data and workload management, database infrastructure, and validation. The use of these systems to prepare the data for physics analysis and assess its quality are described, along with the software tools used for data analysis itself. An outlook for the development of these projects towards Run 4 is also provided

Search for the Higgs boson decay to a ZZ boson and a photon in pppp collisions at s=13\sqrt{s}=13 TeV and 13.613.6 TeV with the ATLAS detector

International audienceA search for the Higgs boson decay to a $Z$ boson and a photon in the $\ell\ellγ$ ($\ell = e, μ$) final state is performed using $pp$ collisions at $\sqrt{s}=13.6$ TeV recorded with the ATLAS detector at the Large Hadron Collider during 2022-2024, corresponding to an integrated luminosity of 165 fb$^{-1}$. The signal yield, normalised to the Standard Model prediction, is measured to be $μ=0.9^{+0.7}_{-0.6}$, compared to an expected value of $μ=1.0\pm0.7$. This corresponds to an observed (expected) signal significance of 1.4 (1.5) standard deviations for the background-only hypothesis. This result is combined with that of a similar search performed with 140 fb$^{-1}$ of $\sqrt{s}=13$ TeV $pp$ collisions to provide the most stringent expected sensitivity to date to this rare decay, namely an observed (expected) signal strength of $μ= 1.3^{+0.6}_{-0.5}$ ($μ= 1.0^{+0.6}_{-0.5}$), corresponding to an observed (expected) significance of 2.5 (1.9) standard deviations. The measurement is consistent with the Standard Model expectation

Search for heavy neutral leptons in decays of W bosons produced in 13 TeV pppp collisions using prompt signatures in the ATLAS detector

International audienceThe existence of right-handed neutrinos with Majorana masses below the electroweak scale could help address the origins of neutrino masses, the matter-antimatter asymmetry, and dark matter. In this paper, leptonic decays of W bosons from 140 fb$^{-1}$ of 13 TeV proton-proton collisions at the LHC, reconstructed in the ATLAS experiment, are used to search for heavy neutral leptons produced through their mixing with muon or electron neutrinos in a scenario with lepton number violation. The search is conducted using prompt leptonic decay signatures. The considered final states require two same-charge leptons or three leptons, while vetoing three-lepton same-flavour topologies. No significant excess over the expected Standard Model backgrounds is found, leading to constraints on the heavy neutral lepton's mixing with muon and electron neutrinos for heavy-neutral-lepton masses. The analysis excludes $|U_{e}|^2$ values above $8\times 10^{-5}$ and $|U_μ|^2$ values above $5.0 \times 10^{-5}$ in the full mass range of 8-65 GeV. The strongest constraints are placed on heavy-neutral-lepton masses in the range 15--30 GeV of $|U_{e}|^2 < 1.1 \times 10^{-5}$ and $|U_μ|^2 < 5 \times 10^{-6}$