Search results for "Small systems"
showing 7 items of 7 documents
ALICE overview
2016
Recent results from the ALICE experiment are presented with a particular emphasis on particle identification, the nuclear modification factor ($R_{AA}$) and azimuthal anisotropy ($v_2$). Comparison of lead-lead and proton-lead results reveals evidence of collectivity in small systems.
Correlated gluonic hot spots meet symmetric cumulants data at LHC energies
2019
We present a systematic study on the influence of spatial correlations between the proton constituents, in our case gluonic hot spots, their size and their number on the symmetric cumulant SC(2, 3), at the eccentricity level, within a Monte Carlo Glauber framework [1]. When modeling the proton as composed by 3 gluonic hot spots, the most common assumption in the literature, we find that the inclusion of spatial correlations is indispensable to reproduce the negative sign of SC(2, 3) in the highest centrality bins as dictated by data. Further, the subtle interplay between the different scales of the problem is discussed. To conclude, the possibility of feeding a 2+1D viscous hydrodynamic sim…
Calculation of size‐intensive transition moments from the coupled cluster singles and doubles linear response function
1994
Coupled cluster singles and doubles linear response (CCLR) calculations have been carried out for excitation energies and dipole transition strengths for the lowest excitations in LiH, CH+, and C4and the results compared with the results from a CI-like approach to equation of motion coupled cluster (EOMCC). The transition strengths are similar in the two approaches for single molecule calculations on small systems. However, the CCLR approach gives size-intensive dipole transition strengths, while title EOMCC formalism does not. Thus, EOMCC calculations can give unphysically dipole transition strengths, e.g., in EOMCC calculations on a sequence of noninteracting LiH systems we obtained a neg…
Variational Cluster Methods in Coordinate Space for Small Systems: Center of Mass Corrections Made Easy
1991
A reexamination of the center of mass problem for light systems in the context of coupled cluster theory has produced a new variational version of the method which is developed entirely in coordinate space. It involves independent cluster functions which depend only on the relative coordinates of the subclusters of the system. In applications to the 4He nucleus described via a number of phenomenological and quasirealistic microscopic Wigner potentials, the method is shown to be quantitatively rather accurate, producing in all cases almost exact results for the ground-state energies at the SUB(3) level of approximation.
Quantum rings for beginners II: Bosons versus fermions
2012
The purpose of this overview article, which can be viewed as a supplement to our previous review on quantum rings, [S. Viefers {\it et al}, Physica E {\bf 21} (2004), 1-35], is to highlight the differences of boson and fermion systems in one-dimensional (1D) and quasi-one-dimensional (Q1D) quantum rings. In particular this involves comparing their many-body spectra and other properties, in various regimes and models, including spinless and spinful particles, finite versus infinite interaction, and continuum versus lattice models. Our aim is to present the topic in a comprehensive way, focusing on small systems where the many-body problem can be solved exactly. Mapping out the similarities a…
Kirkwood-Buff Integrals for Finite Volumes.
2012
Exact expressions for finite-volume Kirkwood−Buff (KB) integrals are derived for hyperspheres in one, two, and three dimensions. These integrals scale linearly with inverse system size. From this, accurate estimates of KB integrals for infinite systems are obtained, and it is shown that they converge much better than the traditional expressions. We show that this approach is very suitable for the computation of KB integrals from molecular dynamics simulations, as we obtain KB integrals for open systems by simulating closed systems.
Light polarization measurements in tests of macrorealism
2018
According to the world view of macrorealism, the properties of a given system exist prior to and independent of measurement, which is incompatible with quantum mechanics. Leggett and Garg put forward a practical criterion capable of identifying violations of macrorealism, and so far experiments performed on microscopic and mesoscopic systems have always ruled out in favor of quantum mechanics. However, a macrorealist can always assign the cause of such violations to the perturbation that measurements effect on such small systems, and hence a definitive test would require using non-invasive measurements, preferably on macroscopic objects, where such measurements seem more plausible. However,…