Evaporite sinkholes in the Friuli Venezia Giulia Region (NE Italy)

4noreservedmixedStefano, Devoto; Chiara, Calligaris; Luca, Zini; Franco, CucchiDevoto, Stefano; Calligaris, Chiara; Zini, Luca; Cucchi, Franc

Soft-parton contributions to heavy-quark production at low transverse momentum

We consider QCD radiative corrections to the production of a heavy-quark pair in hadronic collisions. We present the computation of the soft-parton contributions at low transverse momentum of the heavy-quark pair up to second order in the QCD coupling α$_{S}$. These results complete the evaluation at the next-to-next-to-leading order (NNLO) of the transverse-momentum resummation formula for this process. Moreover, they give all the ingredients that are needed for the NNLO implementation of the q$_{T}$ subtraction formalism for heavy-quark production. We discuss the details of the computation and we provide a code that can be used to obtain the relevant results in numerical form

Top-quark pair hadroproduction at NNLO: differential predictions with the MSbar mass

We consider top-quark pair production at the LHC within the MSbar scheme for the renormalisation of the top-quark mass, and we present predictions for total and differential cross sections at next-to-next-to-leading order (NNLO) in QCD. Our state-of-the-art calculation extends the available differential results by one order in the perturbative expansion, and it is relevant for a precise determination of the top-quark mass, including possible effects of the running mass in the MSbar scheme. We consider variations of the scale at which the MSbar mass of the top quark is evaluated, extending the usual 7-point to a 15-point scale variation. This additional variation is crucial for a reliable estimate of the theoretical uncertainties, especially at low perturbative orders and close to the production threshold of the top-quark pair. We also compute, for the first time, the invariant-mass distribution of the top-quark pair by using a running mass, evaluated at a dynamic scale. Our predictions for the invariant-mass distribution in the MSbar scheme are compared with a recent measurement performed by the CMS Collaboration. We observe that the inclusion of the NNLO corrections improves the agreement with the data, and we discuss effects due to the QCD running of the MSbar mass of the top quark.Comment: 29 pages, 6 figure

Soft-gluon effective coupling: perturbative results and the large-nF limit to all orders

We consider extensions of the soft-gluon effective coupling that generalize the Catani-Marchesini-Webber (CMW) coupling in the context of soft-gluon resummation beyond the next-to-leading logarithmic accuracy. Starting from the probability density of correlated soft emission in d dimensions we introduce a class of soft couplings relevant for resummed QCD calculations of hard-scattering observables. We show that at the conformal point, where the d-dimensional QCD β function vanishes, all these effective couplings are equal and they are also equal to the cusp anomalous dimension. We present explicit results in d dimensions for the soft-emission probability density and the soft couplings at the second-order in the QCD coupling α$_{S}$. In d = 4 dimensions we obtain the explicit relation between the soft couplings at $$\mathcal{O}$$($${\alpha}_{\textrm{S}}^3$$). Finally, we study the structure of the soft coupling in the large-n$_{F}$ limit and we present explicit expressions to all orders in perturbation theory. We also check that, at the conformal point, our large-n$_{F}$ results agree with the known result of the cusp anomalous dimension

Higgs boson production in association with a top-antitop quark pair in next-to-next-to leading order QCD

The associated production of a Higgs boson with a top-antitop quark pair is a crucial process at the LHC since it allows for a direct measurement of the top-quark Yukawa coupling. We present the computation of the radiative corrections to this process at the next-to-next-to-leading order (NNLO) in QCD perturbation theory. This is the very first computation for a $2 \to 3$ process with massive coloured particles at this perturbative order. We develop a soft Higgs boson approximation for loop amplitudes, which enables us to reliably quantify the impact of the yet unknown two-loop contribution. At the centre-of-mass energy $\sqrt{s}=13$ TeV the NNLO corrections increase the next-to-leading order result for the total cross section by about 4% and lead to a significant reduction of perturbative uncertainties.Comment: 8 pages, 2 tables, 1 figure. Version published on PR

Landslide susceptibility analysis exploiting Persistent Scatterers data in the northern coast of Malta

During the last decade a pressing need for more adequate tools to manage the considerable increasing number of hydrogeological emergencies arose among land planning and civil protection authorities. As a consequence, both development and testing of different qualitative and quantitative methods for landslide displacements detection become fundamental in order to provide the best analysis performance in terms of cost-benefit and scientific reliability. Lately quantitative methods to measure deformations of unstable slopes had great advances. In this context, remotely sensed radar techniques, such as PSI (Persistent Scatterers Interferometry), can assist traditional landslide investigations in assessing ground and infrastructure deformations caused by large landslides. The main purpose of this study is exploiting the results of PSI analysis conducted over the Island of Malta to train a Bayesan model for evaluating active landslide susceptibility. This approach has been applied in the NW coast of Malta, where outstanding coastal landslides, such as rock spreads and block slides, have been recognized and mapped. The outcomes of the statistical analysis have been validated through specific field check and GNSS measurements. The results show that the developed susceptibility model predicts an acceptable percentage of landslides and can be considered reliable even if in areas without PSI data

Top-quark pair hadroproduction at next-to-next-to-leading order in QCD

We report on a new calculation of the next-to-next-to-leading order (NNLO) QCD radiative corrections to the inclusive production of top-quark pairs at hadron colliders. The calculation is performed by using the $q_T$ subtraction formalism to handle and cancel infrared singular contributions at intermediate stages of the computation. We present numerical results for the total cross section in $pp$ collisions at $\sqrt{s}=8$ TeV and $13$ TeV, and we compare them with those obtained by using the publicly available numerical program Top++. Our computation represents the first complete application of the $q_T$ subtraction formalism to the hadroproduction of a colourful high-mass system at NNLO.Comment: 9 pages, 1 figur

Higgs Boson Production in Association with a Top-Antitop Quark Pair in Next-to-Next-to-Leading Order QCD

The associated production of a Higgs boson with a top-antitop quark pair is a crucial process at the LHC since it allows for a direct measurement of the top-quark Yukawa coupling. We present the computation of the radiative corrections to this process at the next-to-next-to-leading order (NNLO) in QCD perturbation theory. This is the very first computation for a 2→3 process with massive colored particles at this perturbative order. We develop a soft Higgs boson approximation for loop amplitudes, which enables us to reliably quantify the impact of the yet unknown two-loop contribution. At the center-of-mass energy √s=13  TeV, the NNLO corrections increase the next-to-leading order result for the total cross section by about 4% and lead to a significant reduction of perturbative uncertainties

Reply to comment by C. Morhange, C. Flaux, P. A. Pirazzoli, M. B. Carre on Holocene sea level change in Malta

The pits of Birzebbugia are located near the present-day mean sea level, and some are partially submerged. They were dated using pottery discovered in an archaeological site close to the coast, dated to the Bronze Age (Zammit, 1928; Abela, 1999). As they have been interpreted as sites for the retting of flax, during their utilization they should have remained dry and the sea could not submerge them. This is the reason why these structures are not directly related to the sea level, as suggested by Biolchi et al. (2011), so they represent an upper limit.peer-reviewe