Search results for "Field theory"
showing 10 items of 1188 documents
Analytical solution of 1D Ising-like systems modified by weak long range interaction
1999
It is well-known that 1D systems with only nearest neighbour interaction exhibit no phase transition. It is shown that the presence of a small long range interaction treated by the mean field approximation in addition to strong nearest neighbour interaction gives rise to hysteresis curves of large width. This situation is believed to exist in spin crossover systems where by the deformation of the spin changing molecules, an elastic coupling leads to a long range interaction, and strong bonding between the molecules in a chain compound leads to large values for nearest neighbour interaction constants. For this interaction scheme an analytical solution has been derived and the interplay betwe…
Polymer mixtures in confined geometries: Model systems to explore phase transitions
2005
While binary (A,B) symmetric polymer mixtures ind = 3 dimensions have an unmixing critical point that belongs to the 3d Ising universality class and crosses over to mean field behavior for very long chains, the critical behavior of mixtures confined into thin film geometry falls in the 2d Ising class irrespective of chain length. The critical temperature always scales linearly with chain length, except for strictly two-dimensional chains confined to a plane, for whichT; c ∝N; 5/8 (this unusual exponent describes the fractal contact line between segregated chains in dense melts in two spatial dimensions, d = 2). When the walls of the thin film are not neutral, but preferentially attract one …
The ATLAS Inner Detector commissioning and calibration
2010
The ATLAS Inner Detector is a composite tracking system consisting of silicon pixels, silicon strips and straw tubes in a 2 T magnetic field. Its installation was completed in August 2008 and the detector took part in data-taking with single LHC beams and cosmic rays. The initial detector operation, hardware commissioning and insitu calibrations are described. Tracking performance has been measured with 7.6 million cosmic-ray events, collected using a tracking trigger and reconstructed with modular pattern-recognition and fitting software. The intrinsic hit efficiency and tracking trigger efficiencies are close to 100%. Lorentz angle measurements for both electrons and holes, specific energ…
199 Causal Classes of Space-Time Frames
1992
It is shown that from the causal point of view Minkowskian space-time admits 199, and only 199, different classes of frames.
$\texttt{HEPfit}$: a Code for the Combination of Indirect and Direct Constraints on High Energy Physics Models
2020
The European physical journal / C Particles and fields C80(5), 456 (2020). doi:10.1140/epjc/s10052-020-7904-z
Cutoff dependence of the thrust peak position in the dipole shower
2020
We analyse the dependence of the peak position of the thrust distribution on the cutoff value in the Nagy-Soper dipole shower. We compare the outcome of the parton shower simulations to a relation of the dependence from an analytic computation, derived within soft-collinear effective theory. We show that the result of the parton shower simulations and the analytic computation are in good agreement.
Analytic evaluation of first-order properties within the mean-field variant of spin-free exact two-component theory.
2019
We present a scheme for the calculation of energies and analytic energy gradients within spin-free exact two-component (SFX2C) theory in its mean-field variant, which we refer to as SFX2C-mf. In the presented scheme, the Foldy-Wouthuysen transformation is carried out after the spin-free four-component Hartree-Fock treatment such that in electron-correlated calculations only the non-mean-field part of the two-electron interactions is handled in an untransformed manner. The formulation of analytic gradients requires some adjustments in comparison with the nonrelativistic case, i.e., the additional solution of the spin-free Dirac Coulomb coupled-perturbed Hartee-Fock equations together with a …
γ-Ray Spectroscopy at the Limits: First Observation of Rotational Bands inLr255
2009
The rotational band structure of Lr-255 has been investigated using advanced in-beam gamma-ray spectroscopic techniques. To date, Lr-255 is the heaviest nucleus to be studied in this manner. One ro ...
C15 : From halo effective field theory structure to the study of transfer, breakup, and radiative-capture reactions
2019
Background: Aside from being a one-neutron halo nucleus, $^{15}\mathrm{C}$ is interesting because it is involved in reactions of relevance for several nucleosynthesis scenarios.Purpose: The aim of this work is to analyze various reactions involving $^{15}\mathrm{C}$, using a single structure model based on halo effective field theory (halo EFT) following the excellent results obtained in [P. Capel et al., Phys. Rev. C 98, 034610 (2018)].Method: To develop a halo-EFT model of $^{15}\mathrm{C}$ at next to leading order (NLO), we first extract the asymptotic normalization coefficient (ANC) of its ground state by analyzing $^{14}\mathrm{C}(d,p)^{15}\mathrm{C}$ transfer data at low energy using …
2018
Abstract We show that a Wilson-type discretization of the Gross–Neveu model, a fermionic N -flavor quantum field theory displaying asymptotic freedom and chiral symmetry breaking, can serve as a playground to explore correlated symmetry-protected phases of matter using techniques borrowed from high-energy physics. A large- N study, both in the Hamiltonian and Euclidean formalisms, yields a phase diagram with trivial, topological, and symmetry-broken phases separated by critical lines that meet at a tri-critical point. We benchmark these predictions using tools from condensed matter and quantum information science, which show that the large- N method captures the essence of the phase diagram…