Results 1 - 10 of 3741
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[en] In this paper we investigate the possibility whether, in the extreme limit of high energies and large transverse distances, reggeon field theory might serve as an effective theory of high energy scattering for strong interactions. We analyse the functional renormalization group equations (flow equations) of reggeon field theory and search for fixed points in the space of (local) reggeon field theories. We study in complementary ways the candidate for the scaling solution, investigate its main properties and briefly discuss possible physical interpretations.
[en] We study the possibility that hot Jupiters (HJs) are formed through the secular gravitational interactions between two planets in eccentric orbits with relatively low mutual inclinations () and friction due to tides raised on the planet by the host star. We term this migration mechanism Coplanar High-eccentricity Migration (CHEM) because, like disk migration, it allows for migration to occur on the same plane in which the planets formed. CHEM can operate from the following typical initial configurations: (i) the inner planet in a circular orbit and the outer planet with an eccentricity for ; (ii) two eccentric () orbits for . A population synthesis study of hierarchical systems of two giant planets using the observed eccentricity distribution of giant planets shows that CHEM produces HJs with low stellar obliquities (), with a semi-major axis distribution that matches the observations, and at a rate that can account for their observed occurrence. A different mechanism is needed to create large obliquity HJs, either a different migration channel or a mechanism that tilts the star or the protoplanetary disk. CHEM predicts that HJs should have distant ( AU) and massive (most likely ∼1–3 times more massive than the HJ) companions with relatively low mutual inclinations () and moderately high eccentricities ().
[en] Nutrients from a flowering plant are shared by its pollinators, giving rise to competition in the latter. Such exploitative competition of pollinators can limit their abundance and affect the global organization of the mutualistic partnership in the plant-pollinator mutualistic community. Here we investigate the effects of the exploitative competition between pollinators on the structure and the species abundance of the mutualistic networks which evolve by changing mutualistic partnership towards higher abundance of species. Simulations show different emergent network characteristics between plants and animals; hub plants connected to many pollinators are very rare while a few super-hub pollinators appear with the exploitative competition included, in contrast to equally many hubs of both types without the exploitative competition. More interestingly, the abundance of plant species increases with increasing the exploitative competition strength. We analyze the inverse of the generalized interaction matrix in the weak-interaction limit to identify the leading structural factors relevant to the species abundance, which are shown to be instrumental in optimizing the network structure to increase the mutualistic benefit and lower the cost of exploitative competition. (paper: biological modelling and information)
[en] We study the dynamics of the non-classical correlations for few atom systems in the presence of strong interactions for a number of recently developed adiabatic state preparation protocols. We show that entanglement can be created in a controlled fashion and can be attributed to two distinct sources, the atom–atom interaction and the distribution of atoms among different traps. (author)
[en] Highlights: • Amyloid β oligomers are more toxic than the fibrils and more difficult to target. • One critical interactions which stabilizes the oligomers has been discovered recently. • We have designed a short peptide to target this interaction. • It causes a remarkable change in the ability of the oligomers to attach to lipid bilayers. Small oligomers are the major toxic species in many amyloid related diseases, but they are difficult to characterize and target. Here we construct tetra-peptides FXFX (X = F/K), designed to exploit cation-π, π-π and hydrophobic interactions to disrupt the critical F19-L34 contact recently found in Aβ40 oligomers. FRFR accelerates Aβ40 aggregation, and strongly inhibits its binding to lipid membranes, which is important in the context of toxicity. FKFK lacks both of these effects, which correlates with the weaker interaction of K with aromatic residues. Thus it appears possible to tune specific contacts in the oligomer and effectively change its properties.
[en] We study disformal transformations in the context of scalar extensions to teleparallel gravity, in which the gravitational interaction is mediated by the torsion of a flat, metric compatible connection. We find a generic class of scalar–torsion actions which is invariant under disformal transformations, and which possesses different invariant subclasses. For the most simple of these subclasses we explicitly derive all terms that may appear in the action. We propose to study actions from this class as possible teleparallel analogues of healthy beyond Horndeski theories.
[en] The recent theoretical and experimental studies show that the Breit interaction plays a dominant role in the dielectronic recombination for some particular transitions. The detailed mechanism of why the Breit interaction is dominant for such a process is still unknown. In this work, we performed a simulation and decomposed each individual term in the transition matrix level and found that the Breit interaction is dominant when the leading term ( with the larger of r1 and r2) contribution of the two-electron Coulomb interaction is vanished. Based on this mechanism, we explained why the dielectronic capture strength to state is much stronger than the one to as well as why the Breit interaction plays a dominant role in the anisotropic parameters. Furthermore, the present finding may guide us to search some physical processes in which the Breit interaction is dominant by simply analyzing the coupling coefficients for a given isoelectronic sequence. (paper)
[en] We investigate the Demkov–Kunike transition in a nonlinear two-level system. We find that nonlinearity can dramatically affect the transition dynamics. We show the asymmetry of transition probability in different initial modes. For the weak interaction, the transition probability could be quickly stabilized at 100% in the initial state and could be optionally obtained from zero to 100% over a very wide range of external parameters in the initial state . For the strong interaction, the quantum transition of the two states could be completely blocked. In the adiabatic case, for different initial modes we analyze the asymmetry of transition probability by the eigenenergy level structure of the system. We also show the influence of static detuning on transition probability. Possible applications of our theory to actual physical systems are discussed.
[en] It is currently believed that there is no experimental evidence on possibly quantum features of gravity or gravity-motivated modifications of quantum mechanics. Here we show that single-atom interference experiments achieving large spatial superpositions can rule out a framework where the Newtonian gravitational interaction is fundamentally classical in the information-theoretic sense: it cannot convey entanglement. Specifically, in this framework gravity acts pairwise between massive particles via classical channels, which effectively induce approximately Newtonian forces between the masses. The experiments indicate that if gravity does reduce to the pairwise Newtonian interaction between atoms at low energies, this interaction cannot arise from the exchange of just classical information, and in principle has the capacity to create entanglement. We clarify that, contrary to current belief, the classical-channel description of gravity differs from the model of Diosi and Penrose, which is not constrained by the same data. (paper)
[en] A variant of central interaction of bodies which at short distances describes more powerful, comparing with Newton one, gravitational interaction, is established. Conditions, under which the trajectory of the movement is a conic section, are derived. The connection of the central interaction with the gravitational radius R_g of 'dark body' ('black holes') is established. It is shown that the gravitational radius R_g of the 'dark body' can be arbitrarily big. There may be a lot of 'black holes'