Exotic diboson $$Z'$$ decays in the U$$\mu \nu $$SSM

Searches for new leptophobic resonances at high energy colliders usually target their decay modes into pairs of light quarks, top quarks, or standard model bosons. Additional decay modes may also be present, producing signatures to which current searches are not sensitive. We investigate the performance of generic searches that look for resonances decaying into two large-radius jets. As benchmark for our analysis we use a supersymmetric $$\text {U}(1)'$$ U ( 1 ) ′ extension of the Standard Model, the so-called U$$\mu \nu $$ μ ν SSM, where all the SM decay modes of the $$Z'$$ Z ′ boson take place, plus additional (cascade) decays into new scalars. The generic searches use a generic multi-pronged jet tagger and take advantage of the presence of b quarks in the large-radius jets, and are sensitive to all these $$Z'$$ Z ′ decay modes (except into light quarks) at once. For couplings that are well below current experimental constraints, these generic searches are sensitive at the $$3\sigma -4\sigma $$ 3 σ - 4 σ level with Run 2 LHC data.

A Meso-Scale Approach to Estimating Vertical Mixing Induced by Wind–Waves

The aim of work is to derive an explicit expression for a function of vertical mixing induced by wind-waves. To this end, in the Navier-Stokes equations, a current is decomposed into four constituents: the mean flow, the wave-orbital motion, the wave-induced turbulent and the background turbulent currents. This decomposition allows separating the wave-induced Reynolds stress, Rw, from the background one, Rb. To make a statistical closure for Rw, the Prandtl approach for the background turbulent fluctuations is used that results in an implicit expression for the wave-induced vertical mixing function, Bv. Expression for Bv is specified based on the author’s results for the eddy viscosity found earlier in the frame of the three-layer concept for a wavy air–sea interface, used for modelling wind-drift currents [1]. Finally, the explicit parameterization for Bv(a, u*, z) is found as a linear function in both the wave amplitude at depth z, a(z), and the friction velocity in the air, u*. The linear dependence of function Bv(a) on the wave amplitude provides the enhanced vertical mixing induced by wind–waves in comparison with function Bv(a) having the cubic dependence found in [2], as far as the wind-wave amplitude a(z) decays exponentially with depth.

Tau-lepton Physics at the FCC-ee circular e$^+$e$^-$ Collider

The future FCC-ee collider is designed to deliver \boldsymbol{\mathrm{e^+e^-}}e+e− collisions to study with ultimate precision the Z, W, and Higgs bosons, and the top quark. In a high-statistics scan around the Z pole, \boldsymbol{1.3\times 10^{11}}1.3×1011 events \boldsymbol{\mathrm{Z}\to\tau\tau}Z→𝛕𝛕 will be produced, the largest sample of \boldsymbol{\tau\tau}𝛕𝛕 events foreseen at any lepton collider. With their large boost, \boldsymbol{\tau}𝛕 leptons from Z decays are particularly well suited for precision measurements. The focus of this report is on tests of lepton universality from precision measurement of \boldsymbol{\tau}𝛕 properties and on tests of charged lepton flavour violation in Z decays and in \boldsymbol{\tau}𝛕 decays. In both of these areas, FCC-ee promises sensitivities well beyond present experimental limits.