Anatomy and kinematic evolution of an ancient passive margin involved into an orogenic wedge (Western Southern Alps, Varese area, Italy and Switzerland)

We make use of own geological mapping, interpretations of seismic reflection profiles and deep geophysical data to build a lithospheric-scale cross-section across the European Western Southern Alps (Varese area) and to model a progressive restoration from the end of Mesozoic rifting to present-day. Early phases of Alpine orogeny were characterized by Europe-directed thrusting, whereas post-Oligocene shortening led to basement-involving crustal accretion accompanied by backfolding, and consistent with the kinematics of the adjoining Ivrea Zone. Wedging was favored by a significant component of reactivation of the inherited Adriatic rifted margin. Our results also suggest that, during the collisional and post-collisional tectonics, lithosphere dynamics drove diachronically the onset of tectonic phases (i.e., wedging and slab retreat), from east to west, across the Western Southern Alps

Stability Analysis of a Landslide Scarp by Means of Virtual Outcrops: The Mt. Peron Niche Area (Masiere di Vedana Rock Avalanche, Eastern Southern Alps)

We investigated the Mt. Peron niche area of the Masiere di Vedana rock avalanche (BL), one of the major mass movements that affected the Eastern Southern Alps in historical times. So far, a geomechanical characterization and a stability analysis of the niche area, where potential rockfall sources are present, are lacking. The Mt. Peron niche area is a rocky cliff almost inaccessible to field-based measurements. In order to overcome this issue, we performed a geo-structural characterization of a sector of the cliff by means of a UAV-based photogrammetric survey. From the virtual outcrop, we extracted the orientation of 159 fractures that were divided into sets based on a K-means clustering algorithm and field-checked with some measurements collected along a rappelling descent route down to the cliff. Finally, with the aim of evaluating the stability of the volume under investigation, we performed a stability analysis of three rock pillars included in our survey by means of a distinct element numerical simulation. Our results indicate that two out of the three pillars are characterized by a stable state, under the simulation assumptions, whereas the third is close to failure, and for this reason, its condition needs further investigation

Quaternary capable folds and seismic hazard in Lombardia (Northern Italy): the Castenedolo structure near Brescia.

We identify evidence of late Quaternary compressive tectonics in the Northern sector of the Central Po Plain through a systematic revision of the literature, new field mapping, and a new study of seismic reflection data obtained by ENI E&P. In particular, the reinterpretation of ca. 18.000 km of seismic profiles clearly shows a belt of segmented, 10 to 20 km long, fault propagation folds, controlled by the Plio-Quaternary growth of several out-of-sequence thrusts. As an example of this active structural style, in this paper we focus on a buried fold located just south of the Castenedolo Hill, a few km SE of Brescia. Although the Castenedolo anticline has long ago been described as a young compressional structure (e.g., DESIO, 1965), no detailed structural analysis of this feature has been performed until now. We calculated the uplift rates of this fold through the analysis of its syntectonic sedimentary record as imaged by the extremely high quality ENI E&P subsurface data available in the area. The evolution of this anticline was a discontinuous process characterized by several tectonic uplift pulses (with rates of ca. 0.1 mm/yr) of different duration, separated by periods of variable extent in which no fold growth occurred. The Quaternary growth history of this anticline and the presence of faulted and folded late Pleistocene to Holocene deposits at nearby sites (Ciliverghe and Monte Netto) demonstrate that the significant seismicity of this area (e.g., the December 25, 1222, Io = IX MCS Brescia earthquake, MAGRI & MOLIN, 1986; GUIDOBONI, 1986) must be related to active compressional structures within the Brescia piedmont belt. Our regional investigations show that the structural and paleoseismic setting illustrated near Castenedolo is typical of the whole Lombardia domain of the Southern Alps. This implies that the currently accepted seismotectonic model for this region, and related seismic hazard assessment, should be thoroughly and carefully re-evaluated

Surface Faulting and Ground Deformation: Considerations on Their Lower Detectable Limit and on FDHA for Nuclear Installations

We performed a review of a representative data set on coseismic surface deformation, derived from both interferometric synthetic aperture radar imaging and from a traditional field survey of surface faulting. This analysis indicates a minimum threshold value of Mw 5.4\u20135.5 for earthquake-induced ground deformation and faulting, with an inherently lower limit of detection that makes it hard to recognize surface deformation caused by Mw < 4.5\u20135.0 events. Significant exceptions are represented by shallow (i.e., less than circa 5 km) events that occur in volcano-tectonic settings, where surface deformation and dislocation are also clearly detectable for Mw circa 4.0. Furthermore, a statistically significant regression between the areal extent of surface deformation and maximum slip at surface is proposed. This correlation is discussed in relation to fault displacement hazard analysis for nuclear power plants. In particular, the deformation area is used to find a potential solution for the second and third criterion for defining a capable fault

The Polarised Valence Quark Distribution from semi-inclusive DIS

The semi-inclusive difference asymmetry A^{h^{+}-h^{-}} for hadrons of opposite charge has been measured by the COMPASS experiment at CERN. The data were collected in the years 2002-2004 using a 160 GeV polarised muon beam scattered off a large polarised ^6LiD target and cover the range 0.006 < x < 0.7 and 1 < Q^2 < 100 (GeV/c)^2. In leading order QCD (LO) the asymmetry A_d^{h^{+}-h^{-}} measures the valence quark polarisation and provides an evaluation of the first moment of Delta u_v + Delta d_v which is found to be equal to 0.40 +- 0.07 (stat.) +- 0.05 (syst.) over the measured range of x at Q^2 = 10 (GeV/c)^2. When combined with the first moment of g_1^d previously measured on the same data, this result favours a non-symmetric polarisation of light quarks Delta u-bar = - Delta d-bar at a confidence level of two standard deviations, in contrast to the often assumed symmetric scenario Delta u-bar = Delta d-bar = Delta s-bar = Delta s.Comment: 7 pages, 3 figures, COMPASS, revised: details added, author list update

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The 10B(n,α) reaction cross-section is a well-established neutron cross-section standard for incident neutron energies up to 1 MeV. However, above this energy limit there are only scarce direct (n,α) measurements available and these few experimental data are showing large inconsistencies with each other. These discrepancies are reflected in the evaluated data libraries: ENDF/B-VII.1, JEFF-3.1.2 and JENDL-4.0 are in excellent agreement up to 100 keV incident neutrons, whereas the 10B(n,α) data in the different libraries show large differences in the MeV region. To address these inconsistencies, we have measured the cross section of the two branches of the 10B(n,α) reaction for incident neutron energies up to 3 MeV. We present here the 10B(n,α) and the 10B(n,α1γ) reactions cross section data, their branching ratio and the total 10B(n,α) reaction cross section. The measurements were conducted with a dedicated Frisch-grid ionization chamber installed at the GELINA pulsed neutron source of the EC-JRC. We compare our results with existing experimental data and evaluations

Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV

Probing effective field theory operators in the associated production of top quarks with a Z boson in multilepton final states at root s=13 TeV

Peer reviewe