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The inclusive production of the charm-strange baryon Ω0c is measured for the first time via its semileptonic decay into Ω−e+νe at midrapidity (|y| < 0.8) in proton–proton (pp) collisions at the centre-of-mass energy √s = 13 TeV with the ALICE detector at the LHC. The transverse momentum (pT) differential cross section multiplied by the branching ratio is presented in the interval 2 < pT < 12 GeV/c. The branching-fraction ratio BR(Ω0c → Ω−e+νe)/BR(Ω0c → Ω−π+) is measured to be 1.12 ± 0.22 (stat.) ± 0.27 (syst.). Comparisons with other experimental measurements, as well as with theoretical calculations, are presented.
The production of K∗(892)± meson resonance is measured at midrapidity (|y|<0.5) in Pb−Pb collisions at √sNN=5.02 TeV using the ALICE detector at the CERN Large Hadron Collider. The resonance is reconstructed via its hadronic decay channel K∗(892)±→K0Sπ±. The transverse momentum distributions are obtained for various centrality intervals in the pT range of 0.4−16 GeV/c . Measurements of integrated yields, mean transverse momenta, and particle yield ratios are reported and found to be consistent with previous ALICE measurements for K∗(892)0 within uncertainties. The pT-integrated yield ratio 2K∗(892)±/(K++K−) in central Pb−Pb collisions shows a significant suppression at a level of 9.3σ relative to pp collisions. Thermal model calculations result in an overprediction of the particle yield ratio. Although both hadron resonance gas in partial chemical equilibrium (HRG-PCE) and music + smash simulations consider the hadronic phase, only HRG-PCE accurately represents the measurements, whereas music + smash simulations tend to overpredict the particle yield ratio. These observations, along with the kinetic freeze-out temperatures extracted from the yields measured for light-flavored hadrons using the HRG-PCE model, indicate a finite hadronic phase lifetime, which decreases with increasing collision centrality percentile. The pT-differential yield ratios 2K∗(892)±/(K++K−) and 2K∗(892)±/(π++π−) are presented and compared with measurements in pp collisions at √s=5.02 TeV. Both pa rticle ratios are found to be suppressed by up to a factor of five at pT<2.0 GeV/c in central Pb−Pb collisions and are qualitatively consistent with expectations for rescattering effects in the hadronic phase. The nuclear modification factor (RAA) shows a smooth evolution with centrality and is found to be below unity at pT>8 GeV/c, consistent with measurements for other light-flavored hadrons. The smallest values are observed in most central collisions, indicating larger energy loss of partons traversing the dense medium.
A new species of the spider genus Latrodectus Walckenaer, 1805 from Mexico is described based on an integrative taxonomic approach. Latrodectus occidentalis Valdez-Mondragón sp. nov. is described using the molecular markers cytochrome c oxidase subunit 1 (CO1) and internal transcribed spacer 2 (ITS2), morphology of male and female specimens, and Species Distribution Models (SDM). Four molecular methods for species delimitation were implemented. The new species is characterized by having a unique dorsal coloration pattern on the abdomen. Latrodectus occidentalis sp. nov. is considered a distinct and valid species for four reasons: (1) it can be distinguished by morphological characters (genital and somatic); (2) the average interspecific genetic variation is > 2%; (3) 12 haplotypes were recovered within the species, being separated by the next close haplogroup of L. hesperus Chamberlin & Ivie, 1935 (30 mutations); and (4) congruence was observed among the four molecular methods. The number of recorded species of Latrodectus from Mexico increases to four: Latrodectus mactans (Fabricius, 1775), L. hesperus Chamberlin & Ivie, 1935, L. geometricus C.L. Koch, 1841 (introduced), and L. occidentalis sp. nov. The diversity of the genus Latrodectus from Mexico is surely underestimated, and more sampling is needed from the different biogeographical provinces and ecoregions to fill in these gaps.