| Saturday 20 April 2024 | |
| Events for day: Wednesday 16 May 2018 |
| 13:30 - 15:00 Weekly Seminar Stellar Evolution in Chameleon Modified Gravity School ASTRONOMY In this talk, I review the impact of modified gravity theories on astrophysical objects, from very early stellar evolution when an interstellar cloud of molecular Hydrogen give birth to high and low mass stars up to the very late stage of stellar evolution when asymptotic giant branch (AGB) stars pulsate and loss of mass to planetary nebula. We have found that a simple modified gravity model like Chameleon with a Ratra-Peebles potential can modify fragmentation process and make a stellar cluster with different initial mass function. At the end of stellar evolution, extra force mediated by the scalar field could have a strong effect on the per ... 14:00 - 15:00 Weekly Seminar Condensed Matter and Statistical Physics Group Can novel crystal structures be predicted using machine learning potentials? School PHYSICS Seminar Room (classroom A), Farmanieh Building, IPM ... 14:00 - 15:00 Weekly Seminar Can novel crystal structures be predicted using machine learning potentials? School NANO SCIENCES Can novel crystal structures be predicted using machine learning potentials? Recent developments in computer power have enabled prediction of crystal structures using ground state energies based on density functional theory. This is done by means of global optimization techniques that explore low-lying energy structure in addition to the putative global minimum. The major obstacle to this approach is that the number of structures increases exponentially with respect to the number of atoms in the unit cell, therefore, a thorough exploration of energy landscape including large supercells is not computationally feasible. Rep ... 15:00 - 16:00 Weekly Seminar Asymptotic Symmetries in p-Form Theories School PARTICLES AND ACCELERATORS We consider (p+1)-form gauge fields in flat (2p+4)-dimensions for which the radiation and the Coulomb solutions have the same asymptotic falloff behavior. Imposing appropriate falloff behavior on fields and adopting a Maxwell-type action, we construct the boundary term which renders the action principle well-defined in the Lorenz gauge. We then compute conserved surface charges and the corresponding asymptotic charge algebra associated with nontrivial gauge transformations. We show that for p ? 1 cases we have three sets of conserved asymptotic charges associated with exact, coexact and zero-mode parts of the corresponding p-form gauge transf ... 15:30 - 17:00 Geometry and Topology Weekly Seminar On the Postulation of Scheme Theoretic Unions of Linear Subspaces of Projective Space School MATHEMATICS A fundamental problem in Algebraic Geometry for projective schemes X is postulation problem. In fact to understand the geometry of X as an embedded scheme, one of the first points of interest is considering the postulation problem, i.e. determining the number of conditions imposed by asking hypersurfaces of any degree to contain X. There is an expected number of conditions- in this situation the scheme X is said to have good postulation. So a natural question to ask is: when does X have good postulation, and if it is not, why not? In the case when X is a scheme supported on unions of generic linear subspaces of a projective space there is ... 16:00 - 17:00 Monthly Colloquium Optomechanical Arrays for quantum simulation of Non-equilibrium Dynamics School NANO SCIENCES Optomechanical Arrays for quantum simulation of Non-equilibrium Dynamics We propose a tunable quantum simulator based on Optomechanical arrays, which can exploit dynamical properties of Optomechanical arrays to simulate non-adiabatic evolution of many-body systems. We first investigate the non-equilibrium dynamics in Optomechanical arrays and find how driving the system out of equilibrium can generate excitations. We then propose a specific simulator for studying the quench dynamics and the topological phase-transition in the Su-Schrieffer-Heeger model (SSH). The applications of this simulator are not limited to this ... |