Search results for "Vector"
showing 10 items of 2660 documents
Systematic derivation of hydrodynamic equations for viscoelastic phase separation
2021
(abridged) We present a detailed derivation of a simple hydrodynamic two-fluid model, which aims at the description of the phase separation of non-entangled polymer solutions, where viscoelastic effects play a role. It is directly based upon the coarse-graining of a well-defined molecular model, such that all degrees of freedom have a clear and unambiguous molecular interpretation. The considerations are based upon a free-energy functional, and the dynamics is split into a conservative and a dissipative part, where the latter satisfies the Onsager relations and the Second Law of thermodynamics. The model is therefore fully consistent with both equilibrium and non-equilibrium thermodynamics.…
Supersymmetric associated vector coherent states and generalized Landau levels arising from two-dimensional supersymmetry
2008
We describe a method for constructing vector coherent states for quantum supersymmetric partner Hamiltonians. The method is then applied to such partner Hamiltonians arising from a generalization of the fractional quantum Hall effect. Explicit examples are worked out.
Viability of light-Higgs strongly-coupled scenarios
2013
Contrary to what is sometimes stated, the current electroweak precision data easily allow for massive composite resonance states at the natural EW scale, i.e., well over the TeV. The oblique parameters S and T are analyzed by means of an effective Lagrangian that implements the $SU(2)_L\otimes SU(2)_R\to SU(2)_{L+R}$ pattern of electroweak symmetry breaking. They are computed at the one-loop level and incorporating the newly discovered Higgs-like boson and possible spin-1 composite resonances. Imposing a proper ultraviolet behaviour is crucial and allows us to determine S and T at next-to-leading order in terms of a few resonance parameters. Electroweak precision data force the vector and a…
Topological Hamiltonian as an exact tool for topological invariants
2012
We propose the concept of `topological Hamiltonian' for topological insulators and superconductors in interacting systems. The eigenvalues of topological Hamiltonian are significantly different from the physical energy spectra, but we show that topological Hamiltonian contains the information of gapless surface states, therefore it is an exact tool for topological invariants.
Study of the dynamic growth of wetting layers in the confined Ising model with competing surface fields
2006
A two-dimensional magnetic Ising system confined in an L × D geometry () in the presence of competing magnetic fields (h) acting at opposite walls along the D-direction exhibits an interface between domains of different orientation that runs parallel to the walls. In the limit of infinite film thickness () this interface undergoes a wetting transition that occurs at the critical curve Tw(h), so that for T<Tw(h) such an interface is bound to the walls, while for Tw(h)≤T≤Tcb the interface is freely fluctuating around the centre of the film, where Tcb is the bulk critical temperature. Starting from a monodomain structure with the interface bound to one wall, we study the onset of the interface…
Three-prong τ decays with charged kaons
1998
Final states with charged kaons in three-prong τ decays are studied by exploiting the particle identification from the dE/dx measurement. The results are based on a sample of about 1.6 × 105 detected τ pairs collected with the ALEPH detector between 1991 and 1995 around the Z peak. The following branching ratios have been measured: B(τ- → K−K+π−ντ) = (1.63 ± 0.21 ± 0.17) × 10−3, B(τ− → K−π+π−ντ) = (2.14 ± 0.37 ± 0.29) × 10−3, B(τ− → K−K+π−π0ντ) = (0.75 ± 0.29 ± 0.15) × 10−3, and B(τ− → K−π+π−π0ντ) = (0.61 ± 0.39 ± 0.18) × 10−3. The first two measurements are more precise than the current world averages, while the last two channels are investigated for the first time. The 95% C.L. upper limi…
Cosmological Applications of Extended Electromagnetism
2013
Extended electromagnetism (EE) has been applied to cosmology in various papers. In all of them, the zero order energy density of the EE vector field plays the same role as vacuum energy. Perturbations of this field have been studied by using different approaches. Firstly, some basic equations and ideas are summarized and, then, the CMBFAST code is used to calculate the cosmic microwave background angular power spectrum for appropriate values of the EE parameters. Comparisons of the resulting spectra with a good observational one compatible with WMAP7 (Wilkinson map anisotropy probe 7 years data) seem to be promising. We are currently looking for a set of parameters leading to the best fitti…
Measurement of the tt¯Z and tt¯W cross sections in proton-proton collisions at s=13 TeV with the ATLAS detector
2019
A measurement of the associated production of a top-quark pair (tt) with a vector boson (W, Z) in proton-proton collisions at a center-of-mass energy of 13 TeV is presented, using 36.1 fb-1 of integrated luminosity collected by the ATLAS detector at the Large Hadron Collider. Events are selected in channels with two same- or opposite-sign leptons (electrons or muons), three leptons or four leptons, and each channel is further divided into multiple regions to maximize the sensitivity of the measurement. The ttZ and ttW production cross sections are simultaneously measured using a combined fit to all regions. The best-fit values of the production cross sections are σttZ=0.95±0.08stat±0.10syst…
Pattern selection in the 2D FitzHugh–Nagumo model
2018
We construct square and target patterns solutions of the FitzHugh–Nagumo reaction–diffusion system on planar bounded domains. We study the existence and stability of stationary square and super-square patterns by performing a close to equilibrium asymptotic weakly nonlinear expansion: the emergence of these patterns is shown to occur when the bifurcation takes place through a multiplicity-two eigenvalue without resonance. The system is also shown to support the formation of axisymmetric target patterns whose amplitude equation is derived close to the bifurcation threshold. We present several numerical simulations validating the theoretical results.
Isovector spin-multipole strength distributions in double- β -decay triplets
2017
In this work the energetics and strength distributions of isovector spin-dipole and spin-quadrupole transitions from the ground states of the pairs ($^{76}\mathrm{Ge}, ^{76}\mathrm{Se}$), ($^{82}\mathrm{Se}, ^{82}\mathrm{Kr}$), ($^{96}\mathrm{Zr}, ^{96}\mathrm{Mo}$), ($^{100}\mathrm{Mo}, ^{100}\mathrm{Ru}$), ($^{116}\mathrm{Cd}, ^{116}\mathrm{Sn}$), ($^{128}\mathrm{Te}, ^{128}\mathrm{Xe}$), ($^{130}\mathrm{Te}, ^{130}\mathrm{Xe}$), and ($^{136}\mathrm{Xe}, ^{136}\mathrm{Ba}$), of double-$\ensuremath{\beta}$-decay initial and final nuclei, to the ${J}^{\ensuremath{\pi}}={0}^{\ensuremath{-}},{1}^{\ensuremath{-}},{2}^{\ensuremath{-}},{1}^{+},{2}^{+}$, and ${3}^{+}$ excited states of the interm…