Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

Peer reviewe

Palaeontology from Australasia and beyond: Abstracts from Palaeo Down Under 3 Perth, Western Australia, July 2023

Palaeo Down Under 3 (PDU3), the now quadrennial conference of the Australasian Palaeontologists (AAP) association, was held in Perth, Western Australia, from the 10th-14th of July 2023. PDU3 showcased innovative research, outreach and education initiatives being conducted across Australasia and beyond by both local and international scientists. A total of 78 talks, 17 posters and 6 plenaries were presented across the five days, and covered a wide range of topics, geological timeframes, and fossil groups. AAP is proud to publish this compilation of PDU3 abstracts to illustrate the current and ongoing strength of Australasian palaeontology. Sarah K. Martin [ [email protected] ], Geological Survey of Western Australia, Department of Energy, Mines, Industry Regulation and Safety, 100 Plain St, East Perth, Western Australia 6004, Australia; Michael Archer [ [email protected] ], School of Biological, Earth & Environmental Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia; Heidi J. Allen [ [email protected] ], Geological Survey of Western Australia, Department of Energy, Mines, Industry Regulation and Safety, 100 Plain St, East Perth, Western Australia 6004, Australia; Daniel D. Badea [ [email protected] ], Faculty of Geography and Geology, "Alexandru Ioan Cuza" University, Bulevard "Carol I", Nr.11, 707006, Iași, Romania; Eleanor Beidatsch [ [email protected] ], Palaeoscience Research Centre, University of New England, Armidale, New South Wales 2351, Australia; Marissa J. Betts [ [email protected] ], Palaeoscience Research Centre/LLUNE, University of New England, Armidale, New South Wales 2351, Australia; Maria Blake [ [email protected] ], School of Earth, Atmosphere and Environment, Monash University, 9 Rainforest Walk, Clayton, Victoria 3800, Australia; Phillip C. Boan [ [email protected] ], University of California, Riverside, Geology 1242, 900 University Ave, Riverside, CA 92521, U.S.A.; Tory Botha [ [email protected] ], School of Biological Sciences, Molecular Life Sciences Building, North Terrace Campus, The University of Adelaide, Adelaide, South Australia 5005, Australia; Glenn A. Brock [ [email protected] ], School of Natural Sciences, Macquarie University, New South Wales 2109, Australia; Luke Brosnan [ [email protected] ], WA Organic and Isotope Geochemistry Centre, The Institute for Geoscience Research, School of Earth and Planetary Sciences, Building 500, Curtin University, Kent St, Bentley, Western Australia 6102, Australia; Jack Castle-Jones [ [email protected] ], School of Natural Sciences, Macquarie University, New South Wales 2109, Australia; Jonathan Cramb [ [email protected] ], Queensland Museum, PO Box 3300, South Brisbane BC, Queensland 4101, Australia; Vanesa L. De Pietri [ [email protected] ], School of Earth and Environment, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand; Sherri Donaldson [ [email protected] ], School of Geosciences, University of Edinburgh, Grant Institute, The King's Buildings, James Hutton Road, Edinburgh, EH9 3FE, Scotland, U.K.; Elizabeth M. Dowding [ [email protected] ], Friedrich-Alexander-Universität Erlangen-Nürnberg, Loewenichstraße 28 91054 Erlangen, Germany; Ruairidh Duncan [ [email protected] ], Evans EvoMorph Lab, Room 226, 18 Innovation Walk, School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia; Amy L. Elson [ [email protected] ], WA Organic and Isotope Geochemistry Centre, The Institute for Geoscience Research, School of Earth and Planetary Sciences, Building 500, Curtin University, Kent St, Bentley, Western Australia 6102, Australia; Roy M. Farman [ [email protected] ], School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia; Mahala A. Fergusen [ [email protected] ], School of Biological Sciences, Benham Building, North Terrace Campus, The University of Adelaide, Adelaide, South Australia 5005, Australia; Alyssa Fjeld [ [email protected] ], School of Biological Sciences, 18 Innovation Walk, Monash University, Clayton, Victoria 3800, and School of Natural Sciences, Macquarie University, New South Wales 2109, Australia; David Flannery [ [email protected] ], School of Earth and Atmospheric Sciences, Queensland University of Technology, 2 George St, Brisbane, Queensland 4000, Australia; Timothy G. Frauenfelder [ [email protected] ], University of New England, Armidale, New South Wales 2351, Australia; John D. Gorter [ [email protected] ], PO Box 711, Claremont, Western Australia 6910, Australia; Michelle Gray [ [email protected] ], School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3216, Australia; Nigel Gray [ [email protected] ], GPO Box 2902, Brisbane, Queensland 4001, Australia; Peter Haines [ [email protected] ], Geological Survey of Western Australia, Department of Energy, Mines, Industry Regulation and Safety, 100 Plain St, East Perth, Western Australia 6004, Australia; Lachlan J. Hart [ [email protected] ], Australian Museum Research Institute, 1 William Street, Sydney, New South Wales 2010, Australia; Brooke E. Holland [ [email protected] ], School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia; James D. Holmes [ [email protected] ], Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, Uppsala 752 36, Sweden; Lars Holmer [ [email protected] ], Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, Uppsala 752 36, Sweden; Ashleigh V.S. Hood [ [email protected] ], School of Geography, Earth and Atmospheric Sciences, University of Melbourne, Parkville, Victoria 3010, Australia; Alexey P. Ippolitov [ [email protected]] , School of Geography, Environment and Earth Sciences, Victoria University of Wellington | Te Herenga Waka, 21 Kelburn Parade, Wellington 6012, New Zealand; Christine M. Janis [ [email protected] ], Bristol Palaeobiology Group, School of Earth Sciences, University of Bristol, Wills Memorial Building, Bristol, BS8 1RJ, U.K.; Benjamin P. Kear [ [email protected] ], The Museum of Evolution, Uppsala University, Norbyvägen 16, SE-752 36 Uppsala, Sweden; Sophie Kelly [ [email protected] ], School of Earth and Environment, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand; Justin L. Kitchener [ [email protected] ], School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia; John R. Laurie [ [email protected] ], Geoscience Australia, Symonston, Australian Capital Territory 2601, and School of Natural Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia; Lucy G. Leahey [ [email protected] ], The University of Queensland, Brisbane, Queensland 4072, Australia; John A. Long [ [email protected] ], College of Science and Engineering, Flinders University, PO Box 2100, Adelaide, South Australia 5001, Australia; Daniel Mantle [ [email protected] ], MGPalaeo, Unit 1, 5 Arvida Street, Malaga, Western Australia 6090, Australia; David McB. Martin [ [email protected] ], Geological Survey of Western Australia, Department of Energy, Mines, Industry Regulation and Safety, 100 Plain St, East Perth, Western Australia 6004, Australia; Chris Mays [ [email protected] ], School of Biological, Earth and Environmental Sciences, Environmental Research Institute, University College Cork, Distillery Fields, Cork T23 N73K, Ireland; Matthew R. McCurry [ [email protected] ], Australian Museum, 1 William St, Sydney, New South Wales 2010, Australia; Peter McGoldrick [ [email protected] ], CODES, University of Tasmania, Locked Bag 66, Hobart, Tasmania 7001, Australia; Corinne L. Mensforth [ [email protected] ], Flinders University, GPO Box 2100, Adelaide, South Australia 5001, Australia; Rhys D. Meyerkort [ [email protected] ], University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia; Christina Nielsen-Smith [ [email protected] ], School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia; Ryan Nel [ [email protected] ], Geology Department, Rhodes University, Grahamstown, South Africa; Jake Newman-Martin [ [email protected] ], Curtin University, Kent St, Bentley, Western Australia 6102, Australia; Yeongju Oh [ [email protected] ], Division of Earth Sciences, Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, 21990 Incheon, Republic of Korea, and Polar Science, University of Science and Technology, Daejeon, 34113, Republic of Korea; John R. Paterson [ [email protected] ], Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia; Jacob Pears [ [email protected] ], School of Molecular and Life Sciences, Curtin University, Kent St, Bentley, Western Australia 6102, Australia; Stephen F. Poropat [ [email protected] ], Western Australian Organic and Isotope Geochemistry Centre, School of Earth and Planetary Science, Curtin University, Kent St, Bentley, Western Australia 6102, and Australian Age of Dinosaurs Museum of Natural History, Winton, Queensland 4735, Australia; Catherine M. Reid [ [email protected] ], School of Earth and Environment, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand; R. Pamela Reid [ [email protected] ], Department of Marine Geosciences, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, Miami, FL 33149, U.S.A., and Bahamas Marine EcoCentre, Miami, FL 3315

Direct observation of the dead-cone effect in quantum chromodynamics

The direct measurement of the QCD dead cone in charm quark fragmentation is reported, using iterative declustering of jets tagged with a fully reconstructed charmed hadron

Direct observation of the dead-cone effect in quantum chromodynamics

At particle collider experiments, elementary particle interactions with large momentum transfer produce quarks and gluons (known as partons) whose evolution is governed by the strong force, as described by the theory of quantum chromodynamics (QCD) [1]. The vacuum is not transparent to the partons and induces gluon radiation and quark pair production in a process that can be described as a parton shower [2]. Studying the pattern of the parton shower is one of the key experimental tools in understanding the properties of QCD. This pattern is expected to depend on the mass of the initiating parton, through a phenomenon known as the dead-cone effect, which predicts a suppression of the gluon spectrum emitted by a heavy quark of mass m and energy E, within a cone of angular size m/E around the emitter [3]. A direct observation of the dead-cone effect in QCD has not been possible until now, due to the challenge of reconstructing the cascading quarks and gluons from the experimentally accessible bound hadronic states. Here we show the first direct observation of the QCD dead-cone by using new iterative declustering techniques [4, 5] to reconstruct the parton shower of charm quarks. This result confirms a fundamental feature of QCD, which is derived more generally from its origin as a gauge quantum field theory. Furthermore, the measurement of a dead-cone angle constitutes the first direct experimental observation of the non-zero mass of the charm quark, which is a fundamental constant in the standard model of particle physics.The direct measurement of the QCD dead cone in charm quark fragmentation is reported, using iterative declustering of jets tagged with a fully reconstructed charmed hadron.In particle collider experiments, elementary particle interactions with large momentum transfer produce quarks and gluons (known as partons) whose evolution is governed by the strong force, as described by the theory of quantum chromodynamics (QCD). These partons subsequently emit further partons in a process that can be described as a parton shower which culminates in the formation of detectable hadrons. Studying the pattern of the parton shower is one of the key experimental tools for testing QCD. This pattern is expected to depend on the mass of the initiating parton, through a phenomenon known as the dead-cone effect, which predicts a suppression of the gluon spectrum emitted by a heavy quark of mass $m_{\rm{Q}}$ and energy $E$, within a cone of angular size $m_{\rm{Q}}$/$E$ around the emitter. Previously, a direct observation of the dead-cone effect in QCD had not been possible, owing to the challenge of reconstructing the cascading quarks and gluons from the experimentally accessible hadrons. We report the direct observation of the QCD dead cone by using new iterative declustering techniques to reconstruct the parton shower of charm quarks. This result confirms a fundamental feature of QCD. Furthermore, the measurement of a dead-cone angle constitutes a direct experimental observation of the non-zero mass of the charm quark, which is a fundamental constant in the standard model of particle physics

Rapidity and transverse momentum dependence of inclusive J/ψ production in pp collisions at √s=7 TeV

The ALICE experiment at the LHC has studied inclusive J/ψ production at central and forward rapidities in pp collisions at √s=7 TeV. In this Letter, we report on the first results obtained detecting the J/ψ through the dilepton decay into e+e− and μ+μ− pairs in the rapidity ranges |y|<0.9 and 2.5<y<4, respectively, and with acceptance down to zero pT. In the dielectron channel the analysis was carried out on a data sample corresponding to an integrated luminosity Lint=5.6 nb−1 and the number of signal events is NJ/ψ=352±32(stat.)±28(syst.); the corresponding figures in the dimuon channel are Lint=15.6 nb−1 and NJ/ψ=1924±77(stat.)±144(syst.). The measured production cross sections are σJ/ψ(|y|<0.9)=10.7±1.0(stat.)±1.6(syst.)−2.3+1.6(syst.pol.)μb and σJ/ψ(2.5<y<4)=6.31±0.25(stat.)±0.76(syst.)−1.96+0.95(syst.pol.)μb. The differential cross sections, in transverse momentum and rapidity, of the J/ψ were also measured

Suppression of charged particle production at large transverse momentum in central Pb–Pb collisions at √sNN=2.76 TeV

Inclusive transverse momentum spectra of primary charged particles in Pb–Pb collisions at √sNN=2.76 TeV have been measured by the ALICE Collaboration at the LHC. The data are presented for central and peripheral collisions, corresponding to 0–5% and 70–80% of the hadronic Pb–Pb cross section. The measured charged particle spectra in |η|<0.8 and 0.3<pT<20 GeV/c are compared to the expectation in pp collisions at the same sNN, scaled by the number of underlying nucleon–nucleon collisions. The comparison is expressed in terms of the nuclear modification factor RAA. The result indicates only weak medium effects (RAA≈0.7) in peripheral collisions. In central collisions, RAA reaches a minimum of about 0.14 at pT=6–7 GeV/c and increases significantly at larger pT. The measured suppression of high-pT particles is stronger than that observed at lower collision energies, indicating that a very dense medium is formed in central Pb–Pb collisions at the LHC

Two-pion Bose–Einstein correlations in central Pb–Pb collisions at √sNN=2.76 TeV

The first measurement of two-pion Bose–Einstein correlations in central Pb–Pb collisions at √sNN=2.76 TeV at the Large Hadron Collider is presented. We observe a growing trend with energy now not only for the longitudinal and the outward but also for the sideward pion source radius. The pion homogeneity volume and the decoupling time are significantly larger than those measured at RHIC

Heavy flavour decay muon production at forward rapidity in proton–proton collisions at √s=7 TeV

The production of muons from heavy flavour decays is measured at forward rapidity in proton–proton collisions at √s=7 TeV collected with the ALICE experiment at the LHC. The analysis is carried out on a data sample corresponding to an integrated luminosity Lint=16.5 nb−1. The transverse momentum and rapidity differential production cross sections of muons from heavy flavour decays are measured in the rapidity range 2.5<y<4, over the transverse momentum range 2<pt<12 GeV/c. The results are compared to predictions based on perturbative QCD calculations

Neutral pion and η meson production in proton–proton collisions at √s=0.9 TeV and s=√7 TeV

he first measurements of the invariant differential cross sections of inclusive π0 and η meson production at mid-rapidity in proton–proton collisions at s=0.9 TeV and s=7 TeV are reported. The π0 measurement covers the ranges 0.4<pT<7 GeV/c and 0.3<pT<25 GeV/c for these two energies, respectively. The production of η mesons was measured at s=√7 TeV in the range 0.4<pT<15 GeV/c. Next-to-Leading Order perturbative QCD calculations, which are consistent with the π0 spectrum at s=0.9 TeV, overestimate those of π0 and η mesons at s=√7 TeV, but agree with the measured η/π0 ratio at s=√7 TeV