Previously published and as yet unpublished QCD results obtained with the ALEPH detector at LEP1 are presented. The unprecedented statistics allows detailed studies of both perturbative and non-perturbative aspects of strong interactions to be carried out using hadronic Z and tau decays. The studies presented include precise determinations of the strong coupling constant, tests of its avour independence, tests of the SU(3) gauge structure of QCD, study of coherence eects, and measurements of single-particle inclusive distributions and two-particle correlations for many identied baryons and mesons.

A neutrino with energy ∼290 TeV, IceCube-170922A, was detected in coincidence with the BL Lac object TXS0506+056 during enhanced gamma-ray activity, with chance coincidence being rejected at ∼3σ level. We monitored the object in the very-high-energy (VHE) band with the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes for ∼41 hr from 1.3 to 40.4 days after the neutrino detection. Day-timescale variability is clearly resolved. We interpret the quasi-simultaneous neutrino and broadband electromagnetic observations with a novel one-zone lepto-hadronic model, based on interactions of electrons and protons coaccelerated in the jet with external photons originating from a slow-moving plasma sheath surrounding the faster jet spine. We can reproduce the multiwavelength spectra of TXS 0506+056 with neutrino rate and energy compatible with IceCube-170922A, and with plausible values for the jet power of 10 4 10 erg s 45 46 1 -´-. The steep spectrum observed by MAGIC is concordant with internal γγ absorption above ∼100 GeV entailed by photohadronic production of a ∼290 TeV neutrino, corroborating a genuine connection between the multi-messenger signals. In contrast to previous predictions of predominantly hadronic emission from neutrino sources, the gamma-rays can be mostly ascribed to inverse Compton upscattering of external photons by accelerated electrons. The X-ray and VHE bands provide crucial constraints on the emission from both accelerated electrons and protons. We infer that the maximum energy of protons in the jet comoving frame can be in the range ∼10 14 -10 18 eV.

Baryon Acoustic Oscillations (BAO) provide a "standard ruler" of known physical length, making it one of the most promising probes of the nature of dark energy. The detection of BAO as an excess of power in the galaxy distribution at a certain scale requires measuring galaxy positions and redshifts. "Transversal" (or "angular") BAO measure the angular size of this scale projected in the sky and provide information about the angular distance. "Line-of-sight" (or "radial") BAO require very precise redshifts, but provide a direct measurement of the Hubble parameter at different redshifts, a more sensitive probe of dark energy. The main goal of this paper is to show that it is possible to obtain photometric redshifts with enough precision (σ z ) to measure BAO along the line of sight. There is a fundamental limitation as to how much one can improve the BAO -2measurement by reducing σ z . We show that σ z ∼ 0.003(1 + z) is sufficient: a much better precision will produce an oversampling of the BAO peak without a significant improvement on its detection, while a much worse precision will result in the effective loss of the radial information. This precision in redshift can be achieved for bright, red galaxies, featuring a prominent 4000Å break, by using a filter system comprising about 40 filters, each with a width close to 100Å, covering the wavelength range from ∼ 4000Å to ∼ 8000Å, supplemented by two broad-band filters similar to the SDSS u and z bands. We describe the practical implementation of this idea, a new galaxy survey project, PAU * , to be carried out with a telescope/camera combination with an etendue about 20 m 2 deg 2 , equivalent to a 2 m telescope equipped with a 6 deg 2 -FoV camera, and covering 8000 sq. deg. in the sky in four years. We expect to measure positions and redshifts for over 14 million red, early-type galaxies with L > L ⋆ and i AB 22.5 in the redshift interval 0.1 < z < 0.9, with a precision σ z < 0.003(1 + z). This population has a number density n 10 −3 Mpc −3 h 3 galaxies within the 9 (Gpc/h) 3 volume to be sampled by our survey, ensuring that the error in the determination of the BAO scale is not limited by shot-noise. By itself, such a survey will deliver precisions of order 5% in the dark-energy equation of state parameter w, if assumed constant, and can determine its time derivative when combined with future CMB measurements. In addition, PAU will yield high-quality redshift and low-resolution spectroscopy for hundreds of millions of other galaxies, including a very significant high-redshift population. The data set produced by this survey will have a unique legacy value, allowing a wide range of astrophysical studies.Subject headings: large-scale structure of universe -cosmological parameters * Physics of the Accelerating Universe (PAU): http://www.ice.cat/

The PAU Survey (PAUS) is an innovative photometric survey with 40 narrow bands at the William Herschel Telescope (WHT). The narrow bands are spaced at 100Å intervals covering the range 4500Å to 8500Å and, in combination with standard broad bands, enable excellent redshift precision. This paper describes the technique, galaxy templates and additional photometric calibration used to determine early photometric redshifts from PAUS. Using bcnz2, a new photometric redshift code developed for this purpose, we characterise the photometric redshift performance using PAUS data on the COSMOS field. Comparison to secure spectra from zCOSMOS DR3 shows that PAUS achieves σ 68 /(1+z) = 0.0037 to i AB < 22.5 when selecting the best 50% of the sources based on a photometric redshift quality cut. Furthermore, a higher photo-z precision (σ 68 /(1 + z) ∼ 0.001) is obtained for a bright and high quality selection, which is driven by the identification of emission lines. We conclude that PAUS meets its design goals, opening up a hitherto uncharted regime of deep, wide, and dense galaxy survey with precise redshifts that will provide unique insights into the formation, evolution and clustering of galaxies, as well as their intrinsic alignments.

The flavour changing neutral current decay b-->sγ has been detected in hadronic Z decays collected by ALEPH at LEP. The signal is isolated in lifetime-tagged bb¯ events by the presence of a hard photon associated with a system of high momentum and high rapidity hadrons. The background processes are normalised from the data themselves. The inclusive branching ratio is measured to beconsistent with the Standard Model expectation via penguin processes