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Electromagnetic probes such as photons and dielectrons (e+e− pairs) are a unique tool to study the space-time evolution of the hot and dense matter created in ultrarelativistic heavy-ion collisions. At low dielectron invariant mass (mee), thermal radiation from the hot hadronic phase contributes to the dielectron spectrum via decays of ρ mesons, whose spectral function is sensitive to chiral-symmetry restoration. At larger mee, thermal radiation from the quark–gluon plasma carries information about the early temperature of the medium. At LHC energies, it is nevertheless dominated by a large background from correlated heavy-flavor hadron decays affected by energy loss and flow in the medium. Complementary to the real photon measurements, dielectron data also allow the extraction of the real direct photon fraction, including thermal photons at low pair transverse momentum pT,ee. The latest ALICE results on dielectron studies in Pb-Pb, and in inelastic and high-multiplicity pp collisions, at √sNN = 5.02 TeV and at √s = 13 TeV, respectively, are presented and compared to simulations and expectations from theory. The status of the Run 3 analysis is also reported.
The production yields of antideuterons and antiprotons are measured in pp collisions at a center-of-mass energy of √s=13 TeV, as a function of transverse momentum (pT) and rapidity (y), for the first time up to |y|=0.7. The measured spectra are used to study the pT and rapidity dependence of the coalescence parameter B2, which quantifies the coalescence probability of antideuterons. The pT and rapidity dependence of the obtained B2 is extrapolated for pT>1.7 GeV/c and |y|>0.7 using the phenomenological antideuteron production model implemented in PYTHIA 8.3 as well as a baryon coalescence afterburner model based on EPOS 3. Such measurements are of interest to the astrophysics community, since they can be used for the calculation of the flux of antinuclei from cosmic rays, in combination with coalescence models.
Measurement of beauty production via non-prompt charm hadrons in p-Pb collisions at √sNN = 5.02 TeV
(2024)
The production cross sections of D0, D+, and Λ+c hadrons originating from beauty-hadron decays (i.e. non-prompt) were measured for the first time at midrapidity in proton−lead (p−Pb) collisions at the center-of-mass energy per nucleon pair of √sNN=5.02 TeV. Nuclear modification factors (RpPb) of non-prompt D0, D+, and Λ+c are calculated as a function of the transverse momentum (pT) to investigate the modification of the momentum spectra measured in p−Pb collisions with respect to those measured in proton−proton (pp) collisions at the same energy. The RpPb measurements are compatible with unity and with the measurements in the prompt charm sector, and do not show a significant pT dependence. The pT-integrated cross sections and pT-integrated RpPb of non-prompt D0 and D+ mesons are also computed by extrapolating the visible cross sections down to pT = 0. The non-prompt D-meson RpPb integrated over pT is compatible with unity and with model calculations implementing modification of the parton distribution functions of nucleons bound in nuclei with respect to free nucleons. The non-prompt Λ+c/D0 and D+/D0 production ratios are computed to investigate hadronisation mechanisms of beauty quarks into mesons and baryons. The measured ratios as a function of pT display a similar trend to that measured for charm hadrons in the same collision system.
Particle production as a function of charged-particle flattenicity in pp collisions at √s = 13 TeV
(2024)
This paper reports the first measurement of the transverse momentum (pT) spectra of primary charged pions, kaons, (anti)protons, and unidentified particles as a function of the charged-particle flattenicity in pp collisions at s√=13 TeV. Flattenicity is a novel event shape observable that is measured in the pseudorapidity intervals covered by the V0 detector, 2.8<η<5.1 and −3.7<η<−1.7. According to QCD-inspired phenomenological models, it shows sensitivity to multiparton interactions and is less affected by biases towards larger pT due to local multiplicity fluctuations in the V0 acceptance than multiplicity. The analysis is performed in minimum-bias (MB) as well as in high-multiplicity events up to pT=20 GeV/c. The event selection requires at least one charged particle produced in the pseudorapidity interval |η|<1. The measured pT distributions, average pT, kaon-to-pion and proton-to-pion particle ratios, presented in this paper, are compared to model calculations using PYTHIA 8 based on color strings and EPOS LHC. The modification of the pT-spectral shapes in low-flattenicity events that have large event activity with respect to those measured in MB events develops a pronounced peak at intermediate pT (2<pT<8 GeV/c), and approaches the vicinity of unity at higher pT. The results are qualitatively described by PYTHIA, and they show different behavior than those measured as a function of charged-particle multiplicity based on the V0M estimator.
Cross-predictability denotes the fact that some assets can predict other assets' returns. I propose a novel performance-based measure that disentangles the economic value of cross-predictability into two components: the predictive power of one asset's signal for other assets' returns (cross-predictive signals) and the amount of an asset's return explained by other assets' signals (cross-predicted returns). Empirically, the latter component dominates the former in the overall cross-prediction effects. In the crosssection, cross-predictability gravitates towards small firms that are strongly mispriced and difficult to arbitrage, while it becomes more difficult to cross-predict returns when market capitalization and book-to-market ratio rise.
This paper examines the dynamic relationship between firm leverage and risktaking. We embed the traditional agency problem of asset substitution within a multi-period model, revealing a U-shaped relationship between leverage and risktaking, evident in data from both the U.S. and Europe. Firms with medium leverage avoid risk to preserve the option of issuing safe debt in the future. This option is valuable because safe debt does not incur the expected cost of bankruptcy, anticipated by debt-holders due to future risk-taking incentives. Our model offers new insights on the interaction between companies' debt financing and their risk profiles.
Three Nearctic species of Episyron Schiødte (Hymenoptera: Pompilidae: Pompilinae: Pompilini) were examined morphologically, geographically, and ecologically with intent to infer an aposematic correlation with habitat type, protarsal digging rake morphology, and host spider association. Episyron quinquenotatus quinquenotatus (Say) and E. conterminus cressoni (Dewitz), two subspecies with extensive aposematic markings and more and longer protarsal comb spines, were associated with bare or sparsely vegetated sandy soils near water courses. Episyron biguttatus biguttatus (Fabricus), with few aposematic markings and less and shorter protarsal comb spines, was associated with more densely vegetated terrain and gravelly and loamy soils. Three subspecies of Anoplius apiculatus (Smith) (Hymenoptera: Pompilidae: Pompilinae: Pompilini) are discussed as an aposematic-habitat comparison.
ZooBank registration. urn:lsid:zoobank.org:pub:6A128918-F0FC-4B58-BDDF-992DEDCD2755
Therates tuberosus Fleutiaux, 1893 and Calochroa octogramma octogramma (Chaudoir, 1852) (Coleoptera: Cicindelidae) are newly recorded for Vietnam. Ten additional species are reported to have new provincial records in Vietnam.
ZooBank registration. urn:lsid:zoobank.org:pub:53ADD674-7C16-40E7-ADF2-D9766125867C
Pulchriphyllium anangu Cumming et al., 2023 is here reported for the first time from Maharashtra state, India. Also, this is the first record of a leaf insect (Phasmatodea: Phylliidae) for Phansad Wildlife Sanctuary, District Raigad, Maharashtra. This sighting represents the northernmost distribution in the Western Ghats for Pulchriphyllium anangu.
ZooBank registration. urn:lsid:zoobank.org:pub:7A6F51C4-A097-4C63-B4F7-81252007F055
Homocopris Burmeister, 1846 (Coleoptera: Scarabaeidae) is a small genus of South American dung beetles composed of four species distributed in Argentina, Brazil, and Chile. Recently, a neotype was designated for Copris torulosus Eschscholtz, 1822 (currently H. torulosus) based on the assumption that the original type series had been lost. However, this designation is invalid for failing to comply with articles 75.2, 75.3, 75.3.1, and 75.3.4. of the International Code of Zoological Nomenclature. Furthermore, even if it had been nomenclaturally valid, the neotype now loses its type status because we found a syntype in the material of the Johann Friedrich Eschscholtz collection, preserved in the collection of Zoological Museum, Moscow Lomonosov State University, Moscow, Russia. We present evidence supporting the recognition of this specimen as a syntype and newly designate it as the lectotype. Photographs of the lectotype and its labels are provided. Additionally, the geographic distributions of H. punctatissimus (Curtis, 1844) and H. torulosus (Eschscholtz, 1822) in Chile are corrected.
ZooBank registration. urn:lsid:zoobank.org:pub:2E05482A-282E-4206-8FE5-D3C59C5F149A
Fifteen new species of longhorned beetles (Coleoptera: Cerambycidae, Disteniidae) from Hispaniola (the Dominican Republic and Haiti) are diagnosed, described, and illustrated: Novantinoe pilithorax Lingafelter, new species (Disteniini); Eburiola ciferrii Lingafelter, new species (Eburiini), Eburiola konstantinovi Lingafelter, new species (Eburiini), Elaphidion jaragua Lingafelter, new species (Elaphidiini), Linsleyonides guerreroi Lingafelter, new species (Elaphidiini), Compsibidion iviei Lingafelter, new species (Tropidini: Subtribe Neoibidionina), Hormathus albisetosus Lingafelter, new species (Tropidini: Subtribe Compsina), Trichrous eryphoides Lingafelter, new species (Dichophyiini), Plectrocerum woodruffi Lingafelter, new species (Dichophyiini), Oreodera nearnsi Lingafelter, new species (Acrocinini/Acanthoderini), Acrepidopterum fuscum Lingafelter, new species (Apomecynini), Acrepidopterum giesberti Lingafelter, new species (Apomecynini), Estola touroulti Lingafelter, new species (Desmiphorini), Eupogonius baorucensis Lingafelter, new species (Desmiphorini), and Eupogonius nigroapicalis Lingafelter, new species (Desmiphorini). Callidium biguttatum Sallé, 1856 is transferred to Calliclytus Fisher, 1932 new combination. The tribe Callidiini is thus removed from the West Indian fauna. Smodicum miserum Thomson, 1878 is a new synonym of Enosmaeus cubanus Thomson, 1878. Heterops hispaniolae Fisher, 1932 is a new synonym of Eburiola geminata (Fabricius, 1787) and the Dominican Republic is a new country record for the species. Linsleyonides portoricensis (Fisher, 1932) is newly recorded for Hispaniola and the Dominican Republic, new country and island record. Mallosoma bicolor Sallé, 1856 (formerly Trichrous) is transferred to Pseudothonalmus Guerrero in Lingafelter and Micheli, 2004, new combination. Trichrous bicolor Fisher, 1932 (now Trichrous fisheri Monné and Giesbert, 1992 due to homonymy) is a new synonym of Trichrous jaegeri Chevrolat, 1858. Rhopalophora baracoana Zayas, 1975 is transferred to Plectrocerum Dejean, 1835, new combination, and this removes Rhopalophorini from the West Indian fauna. Plectrocerum cribratum Sallé, 1856 is a new synonym of Plectrocerum spinicorne (Olivier, 1800). Plinthocoelium virens (Linnaeus, 1758) is reestablished as the proper name for the West Indian species previously known as Plinthocoelium columbinum (Guérin-Méneville, 1838). The African species called Philematium virens (Linnaeus) should use the senior-most synonym and be called Philematium sansibaricum (Gerstaecker, 1871). Plinthocoelium domingoensis (Fisher, 1922) is a new synonym of Plinthocoelium virens (Linnaeus, 1758). Neoclytus pallidicornis Fisher, 1932 is a new synonym of Neoclytus podagricus White, 1855.
ZooBank registration. urn:lsid:zoobank.org:pub:B6A71A8B-0730-4ECA-B0EC-6128421D40AB
Based on the examination of an extensive series of specimens and available type material, three out of the six species of Aleyrodes Latreille (Hemiptera: Sternorrhyncha: Aleyrodidae) described from California, A. diasemus Bemis, 1904, A. essigi Penny, 1922, and A. osmaroniae Sampson, 1945, are newly synonymized under A. spiraeoides Quaintance, 1900. The species of Aleyrodes reported from California are keyed and diagnosed based on characters from puparia and male genitalia, and character variability is documented and illustrated.
ZooBank registration. urn:lsid:zoobank.org:pub:EE1FB0AE-45B7-40D6-8B6F-4B2509A08FDC