Soumis par Anonymous le Juin 18, 2013 - 8:51am

In the past few years, optical cooling and manipulating of macroscopic objects, such as micro-mirrors and cantilevers has developed into an active field of research. In mechanical systems, the oscillator is attached to its suspension, a thermal contact that limits the motion isolation. On the other hand, when these small objects are levitated using the radiation pressure force of lasers, the excellent thermal isolation even at room temperatures helps produce very sensitive force detectors, and eventually quantum transducers for quantum computation purposes.

Soumis par Anonymous le Juin 13, 2013 - 11:13am

Hexagon functions are a class of iterated integrals, depending on three variables (dual conformal cross ratios) which have the correct branch cut structure and other properties to describe the scattering of six gluons in planar N=4 super-Yang-Mills theory. We classify all hexagon

functions through transcendental weight five, using the coproduct for their Hopf algebra iteratively, which amounts to a set of first-order differential equations. As an example, the three-loop remainder function is a particular weight-six hexagon function, whose symbol was determined

previously.

Soumis par Anonymous le Mai 9, 2013 - 1:31pm

Given two lattice Hamiltonians H_1 and H_2 that are identical everywhere except on a local region R of the lattice, we propose a relationship between their ground states psi_1 and psi_2. Specifically, assuming the states can be represented as multi-scale entanglement renormalization ansatz (MERA), we propose a principle of directed influence which asserts that the tensors in the MERA’s that represent the ground states can be chosen to be identical everywhere except within a specific, localized region of the tensor network. The validity of this principle is justified by demonstratin

Soumis par Anonymous le Mai 6, 2013 - 8:57am

We show that the recent AMS02

positron fraction measurement is perfectly consistent with a secondary origin for positrons, and does not require additional primary sources such as pulsars or dark matter. Within the secondary model the AMS02 data imply a cosmic ray propagation time in the

Galaxy of about one Myr and an average traversed interstellar matter density of about 1/cc at a rigidity of 300 GV. These results may hint that high energy cosmic rays are confined to a thin halo of scale height similar to the gaseous disk.

Soumis par Anonymous le Mai 1, 2013 - 8:57am

In this talk, I will start with

briefly introducing some universal physics behind quantum hall and topological

insulator , which inspired a BSM flavor model. It intimately relates

deconstructed little Higgs to flavor structure: fermion masses, CKM etc.

This new cousin of little Higgs, we call it little flavor, shares a 10-20

Tev cut-off scale with little Higgs, so as to explain flavor structure at

surprisingly low scale without rising FCNC problem.

Soumis par Anonymous le Avril 29, 2013 - 9:13am

In this talk I will briefly review the polaron physics, which has helped theorists to conceive the BCS theory of conventional superconductors as well as experimentalists to discover high temperature superconductors in the cuprates. Specifically I will talk about how charge carriers obtain their

masses from coupling to the phonon field in one, two, three or higher dimensions. More recently, there is increasing interest in topological insulators where a gap can be opened which may suggest new version of Higgs mechanism in condensed matter.

Soumis par Anonymous le Avril 17, 2013 - 5:00pm

Physics beyond the standard model: theories of elementary particles with extra space dimensions (large, small, warped and flat); supersymmetry; grand unification; dark matter; inflation and dark energy; as well as relationships between the different subjects.

Soumis par Anonymous le Avril 17, 2013 - 5:00pm

Particle physics, cosmology, and the study of a wide variety of theoretical models – most notably ones involving extra dimensions of space. Randall works on several of the competing models of string theory in the quest to explain the fabric of the universe.

Soumis par Anonymous le Avril 17, 2013 - 5:00pm

String theory, the high energy frontier of elementary particle physics, grand unifications into a single framework, mathematical beauty and supersymmetries, and uncovering the quantum structures of space and time.

Soumis par Anonymous le Avril 17, 2013 - 5:00pm

Mathematical aspects of modern theories of elementary particles and gravitation. Replacing the notion of particles with fundamental abstract fields (magnetic monopoles, vortices and Skyrmions) in an attempt to approach a formulation for quantum gravity.