scholarly journals Fall to the centre in atom traps and point-particle EFT for absorptive systems

2018 ◽  
Vol 2018 (8) ◽  
Author(s):  
R. Plestid ◽  
C. P. Burgess ◽  
D. H. J. O’Dell
Keyword(s):  
Point Particle ◽  
Atom Traps

Best Matching: Technical Details

2018 ◽  
Author(s):  
Flavio Mercati
Keyword(s):  
Point Particle ◽  
Euclidean Group ◽  
Scale Invariant ◽  
Similarity Group ◽  
N Body Problem ◽  
Technical Details ◽  
Matching Procedure ◽  
Principal Fibre ◽  
Principal Fibre Bundle ◽  
Gauge Connection

The best matching procedure described in Chapter 4 is equivalent to the introduction of a principal fibre bundle in configuration space. Essentially one introduces a one-dimensional gauge connection on the time axis, which is a representation of the Euclidean group of rotations and translations (or, possibly, the similarity group which includes dilatations). To accommodate temporal relationalism, the variational principle needs to be invariant under reparametrizations. The simplest way to realize this in point–particle mechanics is to use Jacobi’s reformulation of Mapertuis’ principle. The chapter concludes with the relational reformulation of the Newtonian N-body problem (and its scale-invariant variant).

The kinematics of a point particle

2018 ◽  
Author(s):  
Nathalie Deruelle ◽  
Jean-Philippe Uzan
Keyword(s):  
Internal Structure ◽  
Proper Time ◽  
World Line ◽  
Point Particle ◽  
Material Point ◽  
Spatial Extent ◽  
Geometric Representation ◽  
Mathematical Result ◽  
Point Particles ◽  
The World

This chapter discusses the kinematics of point particles undergoing any type of motion. It introduces the concept of proper time—the geometric representation of the time measured by an accelerated clock. It also describes a world line, which represents the motion of a material point or point particle P, that is, an object whose spatial extent and internal structure can be ignored. The chapter then considers the interpretation of the curvilinear abscissa, which by definition measures the length of the world line L representing the motion of the point particle P. Next, the chapter discusses a mathematical result popularized by Paul Langevin in the 1920s, the so-called ‘Langevin twins’ which revealed a paradoxical result. Finally, the transformation of velocities and accelerations is discussed.

scholarly journals The Little-Bang and the femto-nova in nucleus-nucleus collisions

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Nu Xu ◽  
Kenji Fukushima ◽  
Bedangadas Mohanty
Keyword(s):  
Collision Energy ◽  
Particle Production ◽  
Gluon Plasma ◽  
Baryon Density ◽  
Point Particle ◽  
Current Status ◽  
Density Region ◽  
Qcd Critical Point ◽  
Qcd Phase Diagram ◽  
Lower Collision Energy

AbstractWe make a theoretical and experimental summary of the state-of-the-art status of hot and dense QCD matter studies on selected topics. We review the Beam Energy Scan program for the QCD phase diagram and present the current status of the search for the QCD critical point, particle production in high baryon density region, hypernuclei production, and global polarization effects in nucleus-nucleus collisions. The available experimental data in the strangeness sector suggests that a grand canonical approach in the thermal model at high collision energy makes a transition to the canonical ensemble behavior at low energy. We further discuss future prospects of nuclear collisions to probe properties of baryon-rich matter. Creation of a quark-gluon plasma at high temperature and low baryon density has been called the “Little-Bang” and, analogously, a femtometer-scale explosion of baryon-rich matter at lower collision energy could be called the “femto-nova”, which could possibly sustain substantial vorticity and a magnetic field for non-head-on collisions.

scholarly journals Experimental investigation of optical atom traps with a frequency jump

2006 ◽  
Vol 39 (5) ◽  
pp. 1159-1168 ◽  
Author(s):  
P Ahmadi ◽  
G Behinaein ◽  
B P Timmons ◽  
G S Summy
Keyword(s):  
Experimental Investigation ◽  
Frequency Jump ◽  
Atom Traps

A numerical study of the sedimentation of fibre suspensions

1998 ◽  
Vol 376 ◽  
pp. 149-182 ◽  
Author(s):  
MICHAEL B. MACKAPLOW ◽  
ERIC S. G. SHAQFEH
Keyword(s):  
Monte Carlo ◽  
Steady State ◽  
Monte Carlo Simulations ◽  
Numerical Study ◽  
Point Particle ◽  
Hydrodynamic Interactions ◽  
Dynamic Simulations ◽  
Slender Body Theory ◽  
Fibre Suspensions ◽  
The Mean

The sedimentation of fibre suspensions at low Reynolds number is studied using two different, but complementary, numerical simulation methods: (1) Monte Carlo simulations, which consider interparticle hydrodynamic interactions at all orders within the slender-body theory approximation (Mackaplow & Shaqfeh 1996), and (ii) dynamic simulations, which consider point–particle interactions and are accurate for suspension concentrations of nl3=1, where n and l are the number density and characteristic half-length of the fibres, respectively. For homogeneous, isotropic suspensions, the Monte Carlo simulations show that the hindrance of the mean sedimentation speed is linear in particle concentration up to at least nl3=7. The speed is well predicted by a new dilute theory that includes the effect of two-body interactions. Our dynamic simulations of dilute suspensions, however, show that interfibre hydrodynamic interactions cause the spatial and orientational distributions to become inhomogeneous and anisotropic. Most of the fibres migrate into narrow streamers aligned in the direction of gravity. This drives a downward convective flow within the streamers which serves to increase the mean fibre sedimentation speed. A steady-state orientation distribution develops which strongly favours fibre alignment with gravity. Although the distribution reaches a steady state, individual fibres continue to rotate in a manner that can be qualitatively described as a flipping between the two orientations aligned with gravity. The simulation results are in good agreement with published experimental data.

scholarly journals Nonadiabatic losses from radio-frequency-dressed cold-atom traps: Beyond the Landau-Zener model

2017 ◽  
Vol 96 (2) ◽  
Author(s):  
Kathryn A. Burrows ◽  
Hélène Perrin ◽  
Barry M. Garraway
Keyword(s):  
Radio Frequency ◽  
Cold Atom ◽  
Zener Model ◽  
Atom Traps

scholarly journals Analogues of glacial valley profiles in particle mechanics and in cosmology

FACETS ◽  
2017 ◽  
Vol 2 (1) ◽  
pp. 286-300 ◽  
Author(s):  
Valerio Faraoni ◽  
Adriana M. Cardini
Keyword(s):  
Differential Equation ◽  
Ordinary Differential Equation ◽  
Positive Curvature ◽  
Friedmann Equation ◽  
Theoretical Models ◽  
Point Particle ◽  
Relativistic Cosmology ◽  
Future Singularity ◽  
Particle Mechanics ◽  
Curvature Index

An ordinary differential equation describing the transverse profiles of U-shaped glacial valleys has two formal analogies, which we explore in detail, bridging these different areas of research. First, an analogy with point particle mechanics completes the description of the solutions. Second, an analogy with the Friedmann equation of relativistic cosmology shows that the analogue of a glacial valley profile is a universe with a future singularity of interest in theoretical models of cosmology. A Big Freeze singularity, which was not previously observed for positive curvature index, is also contained in the dynamics.

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