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Effect of the Breit interaction on spin polarization of Auger electrons following electron-impact excitation of Be-like ions
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Measurement of the production cross section of prompt baryons in p–Pb collisions at TeV
No full textThe transverse momentum () differential production cross section of the promptly produced charm-strange baryon (and its charge conjugate ) is measured at midrapidity via its hadronic decay into in p–Pb collisions at a centre-of-mass energy per nucleon–nucleon collision TeV with the ALICE detector at the LHC. The nuclear modification factor (), calculated from the cross sections in pp and p–Pb collisions, is presented and compared with the of baryons. The ratios between the -differential production cross section of baryons and those of mesons and baryons are also reported and compared with results at forward and backward rapidity from the LHCb Collaboration. The measurements of the production cross section of prompt baryons are compared with a model based on perturbative QCD calculations of charm-quark production cross sections, which includes only cold nuclear matter effects in p–Pb collisions, and underestimates the measurement by a factor of about 50. This discrepancy is reduced when the data is compared with a model that includes string formation beyond leading-colour approximation or in which hadronisation is implemented via quark coalescence. The -integrated cross section of prompt -baryon production at midrapidity extrapolated down to = 0 is also reported. These measurements offer insights and constraints for theoretical calculations of the hadronisation process. Additionally, they provide inputs for the calculation of the charm production cross section in p–Pb collisions at midrapidity
Total absorption spectroscopy for the β decay strength distribution of Ga
No full text-decay properties play an important role in most astrophysical processes. In the absence of experimental data, astrophysical models rely on global theoretical calculations to provide the relevant properties. It is therefore important to provide strong experimental constraints when possible. In the case of -decay, the most sensitive probe is the -decay strength distribution. We report here on the first measurement of the latter quantity for the + decay of 60 Ga using the total absorption spectroscopy technique. The experimental results are compared to theoretical calculations often used in astrophysical models, namely the shell model and the quasiparticle random phase approximation (QRPA), as well as an extension of QRPA that includes higher-order nucleonic calculations. Both models are in reasonable agreement with the experimental results
Directed and elliptic flow observations in Sn+Sn collisions with radioactive beams at 270 MeV/u
No full textHigher-order symmetry plane correlations in PbPb collisions at = 5.02 TeV
No full textThe correlations between event-by-event fluctuations of symmetry planes are measured in Pb--Pb collisions at a centre-of-mass energy per nucleon pair \fivenn~recorded by the ALICE detector at the Large Hadron Collider. This analysis is conducted using the Gaussian Estimator technique, which is insensitive to biases from correlations between different flow amplitudes. The study presents, for the first time, the centrality dependence of correlations involving up to five different symmetry planes. The correlation strength varies depending on the harmonic order of the symmetry plane and the collision centrality. Comparisons with measurements from lower energies indicate no significant differences within uncertainties. Additionally, the results are compared with hydrodynamic model calculations. Although the model predictions provide a qualitative explanation of the experimental results, they overestimate the data for some observables. This is particularly true for correlators that are sensitive to the non-linear response of the medium to initial-state anisotropies in the collision system. As these new correlators provide unique information --- independent of flow amplitudes --- their usage in future model developments can further constrain the properties of the strongly-interacting matter created in ultrarelativistic heavy-ion collisions.
Bayesian analysis of a (3 + 1) D hybrid approach with initial conditions from hadronic transport
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