Collision Systems Research Articles

Geomorphological and geo/thermo-chronological responses of Indian plate’s deformation during neogene- quaternary time along the Eastern Himalayan Syntaxis: Formation of Manabhum anticline

India-Eurasia and India-Burma collision systems encircle Eastern Himalayan Syntaxis (EHS) in the north and the southeast. The main active structure responsible for the uplift of the Quaternary and Neogene rocks in the easternmost part of the EHS is the NW-SE trending Mishmi Thrust (MT). The spectacular antiformal Manabhum Hill developed during the Quaternary as a ramp antiform over a splay of Mishmi Thrust in its foreland region. The current work presents the deformation scenario, uplift rate, and landform development along the Mishmi Thrust from the Neogene to the Recent for the first time. The surface deformation and the rock and sediment deformation histories have been interpreted from the geomorphology, structure and petrology of the rocks and sediments. We use new (U + Th + Sm)/He low-temperature thermochronology (LTT) of zircon and apatite and Optically Stimulated Luminescence (OSL) dates to calculate the uplift rate for the Neogene to early Quaternary and late Quaternary time intervals, respectively. The Neogene uplift rate varies between 0.91 and 2.3 mm/yr, whereas the early Quaternary uplift rate is ∼3.1 mm/yr. The increased uplift rate during the Quaternary period with significant deformation of sediments indicates the non-rigid character of the Indian plate in this sector, which experienced compression and clockwise rotation.

Vertical tearing of subducting plates controlled by geometry and rheology of oceanic plates

Lateral non-uniform subduction is impacted by continuous plate segmentation owing to vertical tearing of the subducting plate. However, the dynamics and physical controls of vertical tearing remain controversial. Here, we employed 3D numerical models to investigate the effects of trench geometry (offset by a transform boundary) and plate rheology (plate age and the magnitude of brittle/plastic strain weakening) on the evolution of shear stress-controlled vertical tearing within a homogenous subducting oceanic plate. Numerical results suggest that the trench offset geometry could result in self-sustained vertical tearing as a narrow shear zone within the intact subducting oceanic plate, and that this process of tearing could operate throughout the entire subduction process. Further, the critical trench offset length for the maturation of vertical tearing is impacted by plate rheology. Comparison between numerical modelling results and natural observations suggests that vertical tearing attributed to trench offset geometry is broadly developed in modern subduction and collision systems worldwide.

Excitation function of thermal freeze-out parameters and their correlations from strange hadrons spectra in Au–Au collision at 54.4 GeV

We present a systematic study of Gold–Gold (Au–Au) collision system at 54.4 GeV conducted by the STAR Collaboration at RHIC. The transverse momentum spectra of the strange hadrons, namely KS0, Λ, Λ̄, Ξ̄+ and Ξ− are studied at mid-rapidity |y|<0.5 for seven centrality classes. We applied the blast wave model with Tsallis statistics (TBW) with two flow profiles (n0 = 1 and n0 = 2) in order to compare the results and to check the sensitivity of n0 to the freeze-out parameters. It is found that the TBW model with both the flow profiles can describe the particle spectra. In addition, the bulk properties in terms of kinetic freeze-out temperature (T0), transverse flow velocity (βT), the non-extensive parameter (q), the kinetic freeze-out volume (V), the mean transverse momentum (〈pT〉), and the multiplicity parameter (N0) are also extracted. All the parameters decrease with decreasing the event centrality, however, the non-extensive parameter q has the opposite behavior. There is an abrupt decrease seen in 0–5% to 30–40% centrality, while a slight decrease appears in 40–60% and 60–80% centrality in T0, βT, V, and 〈pT〉. On the other hand, the parameter q follows the same scenario with an opposite trend with centrality. T0 and 〈pT〉 are larger for massive particles while βT, q, V and N0 are larger for lighter particles. The larger T0 and 〈pT〉, and smaller βT, V, and q for the massive particles affirm that the heavy particles freeze-out early. Moreover, the multiple kinetic freeze-out and volume differential freeze-out scenarios are reported, as the former increase while the latter decrease with particle mass. In addition, T0, q, V, and N0 obtained from TBW model with n0 = 1 are compatible to that of n0 = 2. On the other hand, βT is slightly larger in n0 = 2, while 〈pT〉 is slightly larger in n0 = 1. Furthermore, we also reported some important correlations among the extracted parameters. Among these correlations, the positive correlation exist between T0 and βT, T0 and V, T0 and 〈pT〉, T0 and N0, βT and 〈pT〉, βT and V, βT and N0, V and N0, and 〈pT〉 and N0, while the negative correlation of T0 and q, and 〈pT〉 and q.

Centrality and System Size Dependence among Freezeout Parameters and the Implications for EOS and QGP in High-Energy Collisions.

Utilizing the Modified Hagedorn function with embedded flow, we analyze the transverse momenta (pT) and transverse mass (mT) spectra of π+ in Au-Au, Cu-Cu, and d-Au collisions at sNN = 200 GeV across various centrality bins. Our study reveals the centrality and system size dependence of key freezeout parameters, including kinetic freezeout temperature (T0), transverse flow velocity (βT), entropy-related parameter (n), and kinetic freezeout volume (V). Specifically, T0 and n increase from central to peripheral collisions, while βT and V show the opposite trend. These parameters also exhibit system size dependence; T0 and βT are smaller in larger collision systems, whereas V is larger. Importantly, central collisions correspond to a stiffer Equation of State (EOS), characterized by larger βT and smaller T0, while peripheral collisions indicate a softer EOS. These insights are crucial for understanding the properties of Quark-Gluon Plasma (QGP) and offer valuable constraints for Quantum Chromodynamics (QCD) models at high temperatures and densities.

Measurements of H2O-O2 line shape parameters and the determination of the intermolecular potential for modified complex Robert-Bonamy calculations

A series of spectra, one pure H2O and four H2O-O2 mixtures, were measured for the ν2 band in the 1200–1950 cm−1 region at room temperature using a single-pass copper cell housed in the Bruker 125HR high-resolution Fourier transform spectrometer (FTS) at Jet Propulsion Laboratory (JPL). All the five spectra were fit simultaneously using a multispectrum non-linear least-squares fitting software, Labfit programme suite, which adopts a speed-dependent Voigt line shape profile using full line mixing taken into account through a relaxation matrix operation. O2-broadened half-width and O2-induced frequency shift coefficients were determined for more than 350 transitions of H2 16O. These data were then checked using the smooth variation and paring rules [Brown et al. J Mol Spectrosc. 2007;246:1-21, Ma et al. Mol Phys. 2011;109:1925-41] and 186 transitions that obey the rules with less than 3% difference were chosen. Using these selected data, Modified Complex Robert-Bonamy calculations were made to determine the intermolecular potential for the H2O-O2 collision system. Some 93 potential were investigated resulting in a final potential (potential 74) that agrees with the selected half-width measurements having an average percent difference of 0.052 and a standard deviation of 5.108% between measurement and calculations.

Hyperon Polarization along the Beam Direction Relative to the Second and Third Harmonic Event Planes in Isobar Collisions at sqrt[s_{NN}]=200 GeV.

The polarization of Λ and Λ[over ¯] hyperons along the beam direction has been measured relative to the second and third harmonic event planes in isobar Ru+Ru and Zr+Zr collisions at sqrt[s_{NN}]=200 GeV. This is the first experimental evidence of the hyperon polarization by the triangular flow originating from the initial density fluctuations. The amplitudes of the sine modulation for the second and third harmonic results are comparable in magnitude, increase from central to peripheral collisions, and show a mild p_{T} dependence. The azimuthal angle dependence of the polarization follows the vorticity pattern expected due to elliptic and triangular anisotropic flow, and qualitatively disagrees with most hydrodynamic model calculations based on thermal vorticity and shear induced contributions. The model results based on one of existing implementations of the shear contribution lead to a correct azimuthal angle dependence, but predict centrality and p_{T} dependence that still disagree with experimental measurements. Thus, our results provide stringent constraints on the thermal vorticity and shear-induced contributions to hyperon polarization. Comparison to previous measurements at RHIC and the LHC for the second-order harmonic results shows little dependence on the collision system size and collision energy.

Multiplicity Dependence of the Freeze-Out Parameters in Symmetric and Asymmetric Nuclear Collisions at Large Hadron Collider Energies

Strange hadron transverse momentum spectra are analyzed in symmetric pp and PbPb and asymmetric pPb collision systems for their dependence on rapidity and event charged-particle multiplicity. The thermodynamically consistent Tsallis models with and without flow velocity are used to reproduce the experimental data, extracting the freeze-out parameters to gain insights into the underlying physics of the collision processes by looking into the parameters change with different multiplicities, particle types, and collision geometries. We found that with an increase in the event multiplicity, the average transverse flow velocity, effective, and kinetic freezeout temperatures increase, with heavier strange particle species exhibiting a more significant increase. The value of the non-extensivity parameter decreases with an increase in the multiplicity of the particles. For heavier particles, larger Teff and T0 and smaller q have been observed, confirming the quick thermalization and equilibrium for massive particles. Furthermore, the differences in parameter values for particle species are more significant in pp and pPb collisions than in PbPb collisions. In addition, in symmetric pp and PbPb collisions, parameter values (q,T0,βT) show more significant shifts for heavier particles compared to the lighter ones. In contrast, in asymmetric pPb collisions, both heavier and lighter particles display uniform linear progression.

State-selective charge exchange cross sections in collisions of highly-charged sulfur ions with helium and molecular hydrogen

The state-selective cross section data are useful for understanding and modeling the x-ray emission in celestial observations. In the present work, using the cold target recoil ion momentum spectroscopy, for the first time we investigated the state-selective single electron capture processes for S q+–He and H2 (q = 11–15) collision systems at an impact energy of q × 20 keV and obtained the relative state-selective cross sections. The results indicate that only a few principal quantum states of the projectile energy level are populated in a single electron capture process. In particular, the increase of the projectile charge state leads to the population of the states with higher principal quantum numbers. It is also shown that the experimental averaged n-shell populations are reproduced well by the over-barrier model. The database is openly available in Science Data Bank at 10.57760/sciencedb.j00113.00091.

Jet modification in absence of QGP-medium: the role of multiparton interactions and color reconnection* *D. Banerjee acknowledges the Inspire Fellowship research grant (DST/INSPIRE Fellowship/2018/IF180285)

Recent studies on high-multiplicity events in small collision systems (proton-proton and proton-lead) have drawn considerable research interest toward the possibility of the formation of partonic medium in such systems. One of the important consequences of the formation of dense partonic medium is the quenching of high-momentum final-state particles, resulting in several experimental observations such as suppression in nuclear modification factor , modification of jet shape observable and jet fragmentation ( ) distributions, etc. In this work, we study and for inclusive charged-particle jets in proton-proton (pp) collisions at = 13 TeV using the PYTHIA 8 Monash 2013 Monte Carlo simulation. We show that the color reconnection (CR) and multiparton interaction (MPI) mechanisms in PYTHIA 8 can lead to an increased rate of jet production. We also find that the mechanisms of MPI and CR and change in the gluonic contribution in high-multiplicity events result in significant modification of and compared to those in minimum bias events for 10 20 GeV/c. We notice a direct connection of and gluonic contribution with the amount of modification in : the larger the number of MPIs and/or gluonic contribution, the larger the amount of modification of .

Pseudo-rapidity distributions of charged particles in asymmetric collisions using Tsallis thermodynamics

The pseudo-rapidity distributions of the charged particles produced in the asymmetric collision systems p+Al, p+Au and 3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^3$$\\end{document}He+Au at sNN=200\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sqrt{s_\ ext {NN}} = 200$$\\end{document} GeV are evaluated in the framework of a fireball model with Tsallis thermodynamics. The fireball model assumes that the experimentally measured particles are produced by fireballs following the Tsallis distribution and it can effectively describe the experimental data. Our results as well as previous results for d+Au collisions at sNN=200\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sqrt{s_\ ext {NN}} = 200$$\\end{document} GeV and p+Pb collisions at sNN=5.02\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sqrt{s_\ ext {NN}} = 5.02$$\\end{document} TeV validate that the fireball model based on Tsallis thermodynamics can provide a universal framework for pseudo-rapidity distribution of the charged particles produced in asymmetric collision systems. We predict the centrality dependence of the total charged particle multiplicity in the p+Al, p+Au and 3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^3$$\\end{document}He+Au collisions. Additionally, the dependences of the fireball model parameters (y0a\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$y_{0a}$$\\end{document}, y0A\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$y_{0A}$$\\end{document}, σa\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sigma _{a}$$\\end{document} and σA\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sigma _{A}$$\\end{document}) on the centrality and system size are studied.

Theoretical investigation of electron capture processes in slow O7+–H collisions

Aims. The total and n-, l-, and S -resolved single-electron-capture cross sections for the collisions of O7+ with atomic hydrogen are studied in the energy region from 10−3eV u−1−5keV u−1. Methods. These state-selective cross sections were calculated by employing the full quantum-mechanical molecular-orbital close-coupling (QMOCC) method. The ab initio multireference single- and double-excitation configuration interaction approach, with optimized atomic basis sets to accurately describe the highly excited states, was used to obtain the adiabatic potentials and the radial and rotational coupling matrix elements that are required in the QMOCC calculation. Results. Our results are compared with other available theoretical and experimental data. The n = 5 manifold is the dominant reaction channel for the chasrge-transfer process for this collision system over the entire energy range, and our results agree better with the experimental data than the other theoretical results in the energy region in which they overlap because we included the necessary highly excited states in the expansion basis set. These charge-exchange cross-section data are useful for understanding and modeling the X-ray emission in astrophysical environments.

Theoretical study of inelastic processes in collisions of Y and Y+ with hydrogen atom

ABSTRACT Utilizing a simplified quantum model approach, the low-energy inelastic collision processes between yttrium atoms (ions) and hydrogen atoms have been studied. Rate coefficients corresponding to the mutual neutralization, ion-pair formation, excitation, and de-excitation processes for the above collision systems have been provided in the temperature range of 1000–10 000 K. Three ionic states and 73 covalent states are considered in calculations for the collisions of yttrium atoms with hydrogen atoms, which include six molecular symmetries and 4074 partial inelastic reaction processes. For the collisions of yttrium ions with hydrogen atoms, one ionic state and 116 covalent states are included, which are related to three molecular symmetries and 13 572 partial inelastic collision processes. It is found that the rate coefficients for the mutual neutralization process have a maximum at T = 6000 K, which is an order of magnitude higher than those of other processes. Notably, the positions of optimal windows for the collisions of yttrium atoms and ions with hydrogen atoms are found near electronic binding energy −2 eV (Y) and −4.4 eV (Y+), respectively. The scattering channels located in or near these optimal windows have intermediate-to-large rate coefficients (greater than 10−12 cm3 s−1). The reported data should be useful in the study of non-local thermodynamic equilibrium modelling.

Continental subduction of Adria in the Apennines and relation with seismicity and hazard

The subduction of continental lithosphere is a complex process because the buoyancy of the crust is higher than the oceanic and should resist sinking into the mantle. Anyway, studies on the Alpine-Himalayan collision system indicate that a large portion of the continental crust is subducted, while some material is accreted in the orogens. The Apennine is a perfect case for studying how such processes evolve, thanks to high quality seismic images that illuminate a critical depth range not commonly resolved in many collisional settings. In this paper, we show the structure of the Apennines orogen, as jointly revealed by seismicity and deep structure from regional and teleseismic tomography and receiver function profiles. The westward subducting Adria lithosphere is well defined along the orogen showing a mid-crustal delamination. Seismicity within the underthrusting lower crust and velocity anomalies in the mantle wedge highlight how the subduction evolution is entangled with the liberation of fluids. The eclogitization of subducted material enhances the fluid release into the wedge, the delamination and retreat of the Adria plate. This delamination/subduction generates a coupled compression and extension system that migrates eastward following the retreat of the lithosphere, with broad sets of normal faults that invert or interfere with pre-existing compressional structures all over the roof plate. The sparseness and non-ubiquity of intermediate depth earthquakes along the subduction panel suggest that the brittle response of the subducting crust is governed by its different composition and fluid content. Therefore, the lower crust composition appears essential in conditioning the evolution of continental subduction.

New paleomagnetic data from the central Tethyan Himalaya refine the size of Greater India during the Campanian

Knowledge of the size of Greater India is critical to deciphering the geodynamic processes of the India-Asia collision, as the size of this landmass primarily determines the amount of continental subduction and crustal shortening. Recently, paleomagnetic data revealed the rapid drift of a Himalayan microcontinent (i.e., the Tibetan Himalaya) during ca. 75–61 Ma, which resulted in a triple-stage India-Asia collision scenario. This scenario implies a relatively small Greater India at 75 Ma (Late Cretaceous), but this hypothesis is only based on one high quality Campanian paleomagnetic pole from the eastern part of the Tethyan Himalaya. Here we report comprehensive petrographic, rock magnetic and paleomagnetic studies on Upper Cretaceous oceanic affinity red beds (CORBs) of the Chuangde Formation from the central part of the Tethyan Himalaya at 83.6°E longitude. These CORBs are characterized by multi-component magnetizations carried dominantly by detrital hematite, which retains a primary remanent magnetization. Accordingly, the high temperature magnetization components (585−690°C) were isolated by high-resolution thermal demagnetization. The new paleomagnetic data provide, after applying an inclination shallowing correction, a Campanian paleopole of 43.3°N/258.3°E, which places the central part of the Tethyan Himalaya at a paleolatitude of 16.7° ± 1.8°S at ca. 75 Ma. Comparison of this paleolatitude with the expected paleolatitude of India, using its apparent polar wander path, shows that the N-S extent of central Greater India was ∼910 km during the middle Campanian. Our paleomagnetic data are in agreement with balanced cross section reconstructions and seismologic interpretations of the India-Asia collision zone and provide additional support for the North India Sea hypothesis. The improved estimate of the size of Greater India has several implications for Indian continental crust behavior and results in an updated reconstruction of the India-Asia collision system in the Campanian.

Metamorphic and geochronological constraints on the final assembly of West Gondwana: an Ediacaran-Cambrian collisional setting in the northern Araguaia Orogen, central Brazil

ABSTRACT The Araguaia Orogen, located in Central Brazil, represents an Ediacaran-Cambrian collisional orogen associated with the final assembly of West Gondwana. Two contrasting tectonic models have been proposed for the evolution of this orogen, involving different histories for the Amazonian palaeocontinent drift: (i) subduction of a large ocean and final collision of the Amazonian palaeocontinent with Gondwana between ~ 560 and 500 Ma and (ii) intracontinental orogeny after early amalgamation of the Amazonian palaeocontinent at ca. 620 Ma. Detailed tectono-metamorphic studies in this key locality for the evolution of Gondwana are also still scarce. Hence, in this study we present a detailed metamorphic investigation of two metapelite samples (schists) and one garnet amphibolite aiming to unravel the pressure-temperature-time (P-T-t) paths for the higher grade rocks exposed in this orogen. Pressure-temperature estimates based on thermodynamic modelling using isochemical phase diagrams in the MnNCKFMASHTO system for the schists constrained a single and continuous prograde metamorphic path (burial and heating) from ~ 4–6 kbar and ~ 450–500°C to ~ 7–8 kbar and ~ 580–650°C. The near-peak metamorphic conditions of the garnet amphibolite were estimated from classic geothermobarometry at 7.5 ± 0.8 kbar and 552 ± 40°C. Lutetium-hafnium garnet dating constrained an average age for the prograde metamorphism at around 537–533 Ma. These results show that the Araguaia Orogen records one single metamorphic event during the late Ediacaran-early Cambrian, and likely represents part of a collisional system developed between the Amazonian Craton and Parnaíba Block after the closure of the Clymene Ocean.

Understanding Heavy-ion Fusion Cross Section Data Using Novel Artificial Intelligence Approaches

An unprecedentedly extensive dataset of complete fusion cross section data is modeled via a novel artificial intelligence approach. The analysis was focused on light-to-medium-mass nuclei, where fission-like phenomena are more difficult to occur. The method used to derive the models exploits a state-of-the-art hybridization of genetic programming and artificial neural networks and is capable to derive, in a data-driven way, an analytical expression that serves to predict integrated cross section values. We analyzed a comprehensive set of nuclear variables, including quantities related to the nuclear structure of projectile and target. In this paper, we describe the derivation of two computationally simple models that can satisfactorily describe, with a reduced number of variables and only a few parameters, a large variety of light-to-intermediate-mass collision systems in an energy domain ranging approximately from the Coulomb barrier to the oncet of multi-fragmentation phenomena. The underlying methods are of potential use for a broad domain of applications in the nuclear field.

Study of the Bose-Einstein correlations of same-sign pions in proton-lead collisions

Correlations of same-sign charged pions are analysed using proton-lead collision data collected by the LHCb experiment at a nucleon-nucleon centre-of-mass energy of 5.02 TeV, corresponding to an integrated luminosity of 1.06 nb−1. Bose-Einstein correlations are observed in the form of an enhancement of pair production for same-sign charged pions with a small four-momentum difference. The dependence of the correlation radius and the intercept parameter on the reconstructed charged-particle multiplicity is investigated. The measured correlation radii scale linearly with the cube root of the reconstructed charged-particle multiplicity, being compatible with predictions of hydrodynamic models on the collision system evolution.

Eocene–Miocene tectonic reworking of the southeastern Tibetan Plateau: Geochronological and geochemical records from granitoids along the Ailao Shan–Red River Shear Zone

The convergence of the Indian Plate and Eurasia shaped the Earth’s broadest and highest-elevation collisional system and topographic growth, which is not simply illustrated by ongoing contractional deformation. The Cenozoic magmatism along the Ailao Shan-Red River Shear Zone (ARSZ), linking surface geology with deep lithospheric processes, provides additional information regarding the age and progressive deformation of the India-Asia collision. In this study, we present new zircon U–Pb geochronological, elemental geochemical and zircon Hf isotopic data for the Eocene–Miocene granitoid to resolve the southeastern Tibetan Plateau deformation history. The Jinping granitoids in the southern ARSZ were dated at 37.5–33.6 Ma. They show similar geochemical characteristics (whole-rock major oxides, trace element, Sr–Nd–Pb isotopic and zircon in-situ Hf isotopic data) with respect to coeval potassic granitoids in NW Yunnan, suggesting their origination from partial melting of thickened lower crust with additional contribution from enriched mantle-derived magmas. Leucogranite samples within the ARSZ yielded distinctive zircon U–Pb ages of 28.3 Ma and 18.5 Ma. Geochemical features suggest that they were derived from a heterogeneous crustal source consisting of metasediments and metabasites. Our results, along with those previous studies, suggest that the widespread potassic magmatism in the central and southeastern Tibetan Plateau is related to lithospheric mantle upwelling, which resulted in the partial melting of the thickened lower crust and a short-lived crustal extension during a period of decreased convergence rate. Subsequently, the orogenic-scale sinistral strike-slip movement provided shearing heat for generating leucogranites within the shear zones during the late Oligocene–Miocene. The plateau-wide shift in stress reorganization and tectonic reworking led to the lateral extrusion of the SE Tibetan Plateau and its attainment of modern high elevation.

Measurement of the production of (anti)nuclei in p–Pb collisions at [formula omitted

Measurements of (anti)proton, (anti)deuteron, and (anti)3He production in the rapidity range −1<y<0 as a function of the transverse momentum and event multiplicity in p–Pb collisions at a center-of-mass energy per nucleon–nucleon pair sNN=8.16TeV are presented. The coalescence parameters B2 and B3, measured as a function of the transverse momentum per nucleon and of the mean charged-particle multiplicity density, confirm a smooth evolution from low to high multiplicity across different collision systems and energies. The ratios between (anti)deuteron and (anti)3He yields and those of (anti)protons are also reported as a function of the mean charged-particle multiplicity density. A comparison with the predictions of the statistical hadronization and coalescence models for different collision systems and center-of-mass energies favors the coalescence description for the deuteron-to-proton yield ratio with respect to the canonical statistical model.

Measurements of azimuthal anisotropies at forward and backward rapidity with muons in high-multiplicity p–Pb collisions at [formula omitted] TeV

The study of the azimuthal anisotropy of inclusive muons produced in p–Pb collisions at sNN=8.16 TeV, using the ALICE detector at the LHC is reported. The measurement of the second-order Fourier coefficient of the particle azimuthal distribution, v2, is performed as a function of transverse momentum pT in the 0–20% high-multiplicity interval at both forward (2.03<yCMS<3.53) and backward (−4.46<yCMS<−2.96) rapidities over a wide pT range, 0.5<pT<10 GeV/c, in which a dominant contribution of muons from heavy-flavour hadron decays is expected at pT>2 GeV/c. The v2 coefficient of inclusive muons is extracted using two different techniques, namely two-particle cumulants, used for the first time for heavy-flavour measurements, and forward–central two-particle correlations. Both techniques give compatible results. A positive v2 is measured at both forward and backward rapidities with a significance larger than 4.7σ and 7.6σ, respectively, in the interval 2<pT<6 GeV/c. Comparisons with previous measurements in p–Pb collisions at sNN=5.02 TeV, and with AMPT and CGC-based theoretical calculations are discussed. The findings impose new constraints on the theoretical interpretations of the origin of the collective behaviour in small collision systems.