Explore the vast range of titles available.

In this work we report the ongoing characterization of the Sos Enattos former mine (Sardinia, Italy), one of the two candidate sites for the Einstein Telescope (ET), the European third-generation underground interferometric detector of Gravitational Waves. The Sos Enattos site lies on a crystalline basement, made of rocks with good geomechanical properties, characterized by negligible groundwater. In addition, the site has a very low seismic background noise due to the absence of active tectonics involving Sardinia. Finally, the area has a low population density, resulting in a reduced anthropic noise even at the ground level. This location was already studied in 2012-2014 as a promising site for an underground detector. More recently, in March 2019, we deployed a new network of surface and underground seismometers at the site, that is currently monitoring the local seismic noise. Most of the energy carried by the seismic waves is due to the microseisms below 1 Hz, showing a significant correlation with the waves of the west Mediterranean sea. Above 1 Hz the seismic noise in the underground levels of the mine approaches the Peterson's low noise model. Exploiting mine blasting works into the former mine, we were also able to perform active seismic measurements to evaluate the seismic waves propagation across the area. In conclusion we also give a first assessment about the acoustic and magnetic noise in this underground site.

Third-generation gravitational wave observatories will extend the lower frequency limit of the observation band toward 2 Hz, where new sources of gravitational waves, in particular intermediate-mass black holes (IMBH), will be detected. In this frequency region, seismic noise will play an important role, mainly through the so-called Newtonian noise, i.e., the gravity-mediated coupling between ground motion and test mass displacements. The signal lifetime of such sources in the detector is of the order of tens of seconds. In order to determine whether a candidate site to host the Einstein Telescope observatory is particularly suitable to observe such sources, it is necessary to estimate the probability distributions that, in the characteristic time scale of the signal, the sensitivity of the detector is not perturbed by Newtonian noise. In this paper, a first analysis is presented, focused on the Sos Enattos site (Sardinia, Italy), a candidate to host the Einstein Telescope. Starting from a long data set of seismic noise, this distribution is evaluated considering both the presently designed triangular ET configuration and also the classical ”L” configuration.

Marmots are the largest extant representatives of the squirrel family (Sciuridae). Members of this clade are believed to have conservative skeletal characters and are inclined to convergence in species with similar size and ecology. However, this does not seem to hold for the mandible and cranium of marmots; instead, similarities reflect subgeneric classification or geographic distribution. To understand the pattern of morphological evolution in the genus Marmota, the ontogeny of the cranium is investigated in 7 of the 14 living marmot species. In particular, the role of allometry in producing intra- and interspecific differences is analyzed. Sexual dimorphism in allometric trajectories is found to be negligible, whereas shape traits that characterize a specific age are mostly allometric. Allometry accounts for an important proportion, although not for the majority, of shape variation during postnatal ontogeny of the cranium. Interspecific differences in allometric trajectories are generally small and the majority of shape differences in relation to phylogeny appear early in ontogeny. Thus, allometry might have had a limited role in producing the morphological variation of living marmot species or it might even have constrained the range of evolutionary changes in this clade. A very different role of allometry as a source of morphological novelties can be speculated to exist in earlier stages of marmot evolutionary history, when a highly distinctive cranial shape evolved concomitant with a 2-fold increase in size. Three sets of analyses are performed to investigate the ontogeny of cranial form in Marmota. Three-dimensional (3D) coordinates of anatomical landmarks are used to describe the whole marmot cranium in the first 3D geometric morphometric analysis of a sciurid taxon. Also, anatomical landmarks that describe the dorsal and lateral sides of the cranium are used for 2-dimensional (2D) analyses complementary to previous studies on the ventral cranium. Despite the complexity of the cranium, which makes it a poor candidate for 2D studies, results of 2D and 3D analyses are generally in good agreement.

A correction to this paper has been published: https://doi.org/10.1140/epjp/s13360-021-01561-2

A bstract The cross-sections of exclusive (coherent) photoproduction J/ψ and ψ (2S) mesons in ultra-peripheral PbPb collisions at a nucleon-nucleon centre-of-mass energy of 5 . 02 TeV are measured using a data sample corresponding to an integrated luminosity of 228 ± 10 μb − 1 , collected by the LHCb experiment in 2018. The differential cross-sections are measured separately as a function of transverse momentum and rapidity in the nucleus-nucleus centre-of-mass frame for J/ψ and ψ (2S) mesons. The integrated cross-sections are measured to be σ J / ψ coh = 5 . 965 ± 0 . 059 ± 0 . 232 ± 0 . 262 mb and σ ψ 2 S coh = 0 . 923 ± 0 . 086 ± 0 . 028 ± 0 . 040 mb, where the first listed uncertainty is statistical, the second systematic and the third due to the luminosity determination. The cross-section ratio is measured to be σ ψ 2 S coh / σ J / ψ coh = 0 . 155 ± 0 . 014 ± 0 . 003, where the first uncertainty is statistical and the second is systematic. These results are compatible with theoretical predictions.

A bstract Measurements are reported of the central exclusive production of J/ψ and ψ (2 S ) mesons in pp collisions at a centre-of-mass energy of 13 TeV. Backgrounds are significantly reduced compared to previous measurements made at lower energies through the use of new forward shower counters. The products of the cross-sections and the branching fractions for the decays to dimuons, where both muons are within the pseudorapidity range 2 . 0 < η < 4 . 5, are measured to be σ J / ψ → μ + μ − = 435 ± 18 ± 11 ± 17 p b σ ψ 2 S → μ + μ − = 11.1 ± 1.1 ± 0.3 ± 0.4 p b . The first uncertainties are statistical, the second are systematic, and the third are due to the luminosity determination. The cross-sections are also measured differentially for meson rapidities between 2.0 and 4.5. Good agreement is observed with theoretical predictions. Photoproduction cross-sections are derived and compared to previous experiments, and a deviation from a pure power-law extrapolation of lower energy data is observed.

A bstract The ϒ (1 S ) μ + μ − invariant-mass distribution is investigated for a possible exotic meson state composed of two b quarks and two b ¯ quarks, X b b ¯ b b ¯ . The analysis is based on a data sample of pp collisions recorded with the LHCb detector at centre-of-mass energies s = 7 , 8 and 13 TeV, corresponding to an integrated luminosity of 6.3 fb −1 . No significant excess is found, and upper limits are set on the product of the production cross-section and the branching fraction as functions of the mass of the X b b ¯ b b ¯ state. The limits are set in the fiducial volume where all muons have pseudorapidity in the range [2 . 0 , 5 . 0], and the X b b ¯ b b ¯ state has rapidity in the range [2 . 0 , 4 . 5] and transverse momentum less than 15 GeV/ c .

A bstract Production cross-sections of prompt charm mesons are measured using data from pp collisions at the LHC at a centre-of-mass energy of 5 TeV. The data sample corresponds to an integrated luminosity of 8 . 60 ± 0 . 33 pb −1 collected by the LHCb experiment. The production cross-sections of D 0 , D + , D s + , and D ∗+ mesons are measured in bins of charm meson transverse momentum, p T , and rapidity, y . They cover the rapidity range 2 . 0 < y < 4 . 5 and transverse momentum ranges 0 < p T < 10 GeV /c for D 0 and D + and 1 < p T < 10 GeV /c for D s + and D ∗+ mesons. The inclusive cross-sections for the four mesons, including charge-conjugate states, within the range of 1 < p T < 8 GeV /c are determined to be σ pp → D 0 X = 1004 ± 3 ± 54 μ b , σ pp → D + X = 402 ± 2 ± 30 μ b , σ pp → D s + X = 170 ± 4 ± 16 μ b , σ pp → D ∗ + X = 421 ± 5 ± 36 μ b , where the uncertainties are statistical and systematic, respectively.

A search is presented for massive long-lived particles decaying into a muon and two quarks. The dataset consists of proton-proton interactions at centre-of-mass energies of 7 and 8 TeV, corresponding to integrated luminosities of 1 and 2 fb - 1 , respectively. The analysis is performed assuming a set of production mechanisms with simple topologies, including the production of a Higgs-like particle decaying into two long-lived particles. The mass range from 20 to 80  GeV / c 2 and lifetimes from 5 to 100 ps are explored. Results are also interpreted in terms of neutralino production in different R-Parity violating supersymmetric models, with masses in the 23–198 GeV/ c 2 range. No excess above the background expectation is observed and upper limits are set on the production cross-section for various points in the parameter space of theoretical models.

A search is presented for long-lived particles with a mass between 25 and 50 GeV / c 2 and a lifetime between 2 and 500 ps, using proton–proton collision data corresponding to an integrated luminosity of 2.0 fb - 1 , collected by the LHCb detector at centre-of-mass energies of 7 and 8 TeV. The particles are assumed to be pair-produced in the decay of a 125 GeV / c 2 Standard-Model-like Higgs boson. The experimental signature is a single long-lived particle, identified by a displaced vertex with two associated jets. No excess above background is observed and limits are set on the production cross-section as a function of the mass and lifetime of the long-lived particle.