Abstract: Context. The detection of the highest energy neutrino observed to date by KM3NeT, with an estimated energy of 220 PeV, opens up new possibilities for the study and identification of the astrophysical sources responsible for a di ffuse flux of such ultra-high-energy neutrinos, among which gamma-ray bursts are longstanding candidates. Aims. Based on the event KM3-230213A, we derived constraints on the baryon loading and density of the surrounding environment in models of blast waves in long-duration gamma-ray bursts. Methods. We computed the di ffuse flux from gamma-ray burst blast waves, either expanding in a constant density interstellar medium or developing in a radially decreasing density of a wind-like environment surrounding the gamma-ray burst progenitor star, by taking into account the expected neutrino spectra and luminosity function. We used a Poisson likelihood method to constrain the blast wave model parameters by calculating the expected number of neutrino events within the 90% confidence level energy range of KM3-230213A and by using the joint exposure of KM3NeT/ARCA, IceCube, and Pierre Auger. Results. We constrain the baryon loading to be f(b) <= 51 at 90% confidence, with the best-fit and 68% confidence interval being f(b) = 26.9(-17.2)(+11.4) for a constant interstellar medium particle density of n(0) = 1 cm(-3). In the wind-like environment case, the baryon loading is fb similar to 1095 at 90% confidence, with the corresponding 68% confidence interval being f(b) is an element of [8, 231], which is proportional to the sixth power of a variable density parameter of A(*) = 0.1.

Abstract: Turbulence is indispensable to redistribute nutrients for all life forms larger than microbial, on land and in the ocean. Yet, the development of deep-sea turbulence was not studied in three dimensions to date. As a disproportionate laboratory, an array of nearly 3,000 high-resolution temperature sensors had been installed for three years on the flat 2,500-m deep bottom of the Mediterranean Sea. The time series from the half-cubic hectometer mooring-array allows for the creation of unique movies of deep-sea water motions. Although temperature differences are typically 0.001 degrees C, variable convection-turbulence is observed as expected from geothermal heating through the flat seafloor. During about 40% of the time, an additional turbulence, 3 times stronger in magnitude, is observed from slantwise advected warmer waters to pass in turbulent clouds. Besides turbulent clouds and seafloor heating, movies also reveal weakly turbulent interfacial-wave breakdown that commonly occurs in the open ocean far away from boundaries.

Abstract: The first measurements of the top- and antitop-quark differential production cross sections and the top-quark charge asymmetry in the forward region are presented, using proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 5.4 fb(-1). The total production cross sections of top and antitop quarks are also determined. Measurements are performed using the μ+ b-jet final state within a fiducial region defined by b-jet p(T, jet) > 50 GeV and pseudorapidity 2.2 < eta(jet) < 4.0, with the muon from the W-boson decay required to have p(T, mu) > 25 GeV and 2.0 < eta(mu) < 4.5. The muon and b-jet system must satisfy p(T)(mu + jet) > 20 GeV. The measured integrated production cross sections for the top and antitop quarks are sigma(t) = 0.95 +/- 0.04 +/- 0.08 +/- 0.02 pb, sigma((t) over bar) = 0.81 +/- 0.03 +/- 0.07 +/- 0.02 pb, where the first uncertainty is statistical, the second systematic, and the third accounts for the luminosity uncertainty. The top-quark charge asymmetry is measured to be A(C)(t) = 0.08 +/- 0.03 +/- 0.01, where the first uncertainty is statistical and the second is systematic. These results are consistent with next-to-leading order Standard Model predictions.