scholarly journals Structured 3D linear space–time light bullets by nonlocal nanophotonics

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Cheng Guo ◽  
Meng Xiao ◽  
Meir Orenstein ◽  
Shanhui Fan
Keyword(s):  
Angular Momentum ◽  
Degrees Of Freedom ◽  
Pulse Shaping ◽  
Propagation Distance ◽  
Space Time ◽  
Spatial Modulation ◽  
Simultaneous Control ◽  
Modulation Techniques ◽  
Light Bullets ◽  
Internal Degrees Of Freedom

AbstractWe propose the generation of 3D linear light bullets propagating in free space using a single passive nonlocal optical surface. The nonlocal nanophotonics can generate space–time coupling without any need for bulky pulse-shaping and spatial modulation techniques. Our approach provides simultaneous control of various properties of the light bullets, including the external properties such as the group velocity and the propagation distance, and internal degrees of freedom such as the spin angular momentum and the orbital angular momentum.

UNIFIED ELECTROWEAK MODEL BASED ON SPACE–TIME AND ISOSPIN SYMMETRIES

2005 ◽  
Vol 20 (01) ◽  
pp. 175-198 ◽  
Author(s):  
D. SPEHLER ◽  
G. C. MARQUES
Keyword(s):  
Degrees Of Freedom ◽  
Space Time ◽  
Scalar Particles ◽  
Symmetry Breakdown ◽  
Vector Bosons ◽  
Rank 2 ◽  
Electroweak Model ◽  
Spontaneous Symmetry Breakdown ◽  
Internal Degrees Of Freedom

We propose a spinorial approach to the unified electroweak interactions, in which no use is made of spontaneous symmetry breakdown. No scalar particles are needed in order to break the symmetry. No reference is made to gauge symmetry. Our approach stresses the role of space–time and isospin symmetries in the build up of the electroweak model. Internal degrees of freedom, such as isospin, are incorporated in the theory by using spinors carrying isospin indices. All vector bosons are described by a rank 2 field in the spinorial and the isospinorial indices. Leptons are accomodated in a rank 1 spinor field and in a rank 2 isospin field as well. The dynamical variables of the theory are the chiral and isochiral components of these fields.

Quantized Vibrational Motion

2020 ◽  
pp. 281-305
Author(s):  
Jochen Autschbach
Keyword(s):  
Angular Momentum ◽  
Harmonic Oscillator ◽  
Potential Function ◽  
Vibrational Spectroscopy ◽  
Degrees Of Freedom ◽  
Normal Modes ◽  
Atoms In Molecules ◽  
Vibrational Motion ◽  
Morse Oscillator ◽  
Internal Degrees Of Freedom

The harmonic oscillator of chapter 2 is visited again, now in its quantum theoretical version. The solution of the Schrodinger equation (SE) is shown step-by step, as it features steps that are very similar to those used in solving the equations for the angular momentum and hydrogen-like orbitals in later chapters. The Morse oscillator has a potential function that is much more representative of the vibrations of atoms in molecules as the harmonic potential. The solutions of the harmonic and Morse oscillator are compared. It is then shown how nuclear vibrations in poly-atomic molecules are treated at the harmonic level. This requires the separation of internal degrees of freedom from the overall translation and rotation of a molecule, leading to the normal modes. The chapter also discusses basic aspects of vibrational spectroscopy and the selection rules of infrared and Raman vibrational spectroscopy.

scholarly journals EXCEPTIONAL GROUPS IN STRING THEORY

1989 ◽  
Vol 04 (17) ◽  
pp. 4513-4533 ◽  
Author(s):  
DIETER LÜST ◽  
STEFAN THEISEN
Keyword(s):  
Gauge Symmetry ◽  
String Theory ◽  
Degrees Of Freedom ◽  
Space Time ◽  
Dual Role ◽  
World Sheet ◽  
Exceptional Groups ◽  
Internal Degrees Of Freedom

We review the occurrence of exceptional groups in string theory: their dual role as gauge symmetry and as a symmetry unifying space-time, superconformal ghost and internal degrees of freedom. In both cases the relation to the extended world-sheet supersymmetries is discussed in detail. This is used to construct the supermultiplet structure of the massless sectors of all supergravity theories possible in string theory, in even space-time dimensions between four and ten.

Reversibly Sampling Conformations and Binding Modes Using Molecular Darting

2020 ◽  
Author(s):  
Samuel C. Gill ◽  
David Mobley
Keyword(s):  
Monte Carlo ◽  
Ligand Binding ◽  
Binding Sites ◽  
Degrees Of Freedom ◽  
Dynamics Simulation ◽  
Hiv Integrase ◽  
Binding Modes ◽  
System A ◽  
Multiple Binding ◽  
Internal Degrees Of Freedom

<div>Sampling multiple binding modes of a ligand in a single molecular dynamics simulation is difficult. A given ligand may have many internal degrees of freedom, along with many different ways it might orient itself a binding site or across several binding sites, all of which might be separated by large energy barriers. We have developed a novel Monte Carlo move called Molecular Darting (MolDarting) to reversibly sample between predefined binding modes of a ligand. Here, we couple this with nonequilibrium candidate Monte Carlo (NCMC) to improve acceptance of moves.</div><div>We apply this technique to a simple dipeptide system, a ligand binding to T4 Lysozyme L99A, and ligand binding to HIV integrase in order to test this new method. We observe significant increases in acceptance compared to uniformly sampling the internal, and rotational/translational degrees of freedom in these systems.</div>

scholarly journals A novel class of translationally invariant spin chains with long-range interactions

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
B. Basu-Mallick ◽  
F. Finkel ◽  
A. González-López
Keyword(s):  
Long Range ◽  
Degrees Of Freedom ◽  
Spin Chains ◽  
Open Chain ◽  
New Class ◽  
Spin Interactions ◽  
Long Range Interactions ◽  
Spin Reversal ◽  
Twisted Yangian ◽  
Internal Degrees Of Freedom

Abstract We introduce a new class of open, translationally invariant spin chains with long-range interactions depending on both spin permutation and (polarized) spin reversal operators, which includes the Haldane-Shastry chain as a particular degenerate case. The new class is characterized by the fact that the Hamiltonian is invariant under “twisted” translations, combining an ordinary translation with a spin flip at one end of the chain. It includes a remarkable model with elliptic spin-spin interactions, smoothly interpolating between the XXX Heisenberg model with anti-periodic boundary conditions and a new open chain with sites uniformly spaced on a half-circle and interactions inversely proportional to the square of the distance between the spins. We are able to compute in closed form the partition function of the latter chain, thereby obtaining a complete description of its spectrum in terms of a pair of independent su(1|1) and su(m/2) motifs when the number m of internal degrees of freedom is even. This implies that the even m model is invariant under the direct sum of the Yangians Y (gl(1|1)) and Y (gl(0|m/2)). We also analyze several statistical properties of the new chain’s spectrum. In particular, we show that it is highly degenerate, which strongly suggests the existence of an underlying (twisted) Yangian symmetry also for odd m.

scholarly journals Dissipative dynamics of a particle coupled to a field via internal degrees of freedom

2021 ◽  
Vol 103 (5) ◽  
Author(s):  
Kanupriya Sinha ◽  
Adrián Ezequiel Rubio López ◽  
Yiğit Subaşı
Keyword(s):  
Degrees Of Freedom ◽  
Dissipative Dynamics ◽  
Internal Degrees Of Freedom
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