scholarly journals Vacuons and Quasi-phonons: The Hidden Side of Bogoliubov Collective Excitations

2018 ◽  
Vol 2 (1) ◽  
Keyword(s):  
Activation Energy ◽  
Low Energy ◽  
Collective Excitations ◽  
Cooper Pairs ◽  
Weakly Interacting ◽  
Energy Approximation

In a series of papers [1, 2, 3], the author exactly diagonalized the truncated Hamiltonian Hc , proposed by Bogoliubov [4, 5], as a low energy approximation for the weakly interacting boson gas. In addition to the well know collective excitations (CEs) resulting from the Bogoliubov Canonic Approximation (BCA) [6, 7], and denoted as quasi-phonons (QPs), the exact eigenstates of Hc exhibit a new kind of CEs (the `hidden side' which the title alludes to), that we denote as vacuons. Those CEs are created/annihilated by adsorp-tion/emission of a quantum of energy twice as large as the activation energy of a QP. Being momentless, they are reminiscent of Cooper pairs of bosons, with opposite moments. The e_ects of the vacuons on the dynamics of the gas are discussed, with their possible exper-imental evidence.

CHIRAL SYMMETRY BREAKING AND FORMULAS OF QUARK CONVERSION FOR LOW-ENERGY HADRONIC MATRIX ELEMENTS

1993 ◽  
Vol 08 (05) ◽  
pp. 853-872 ◽  
Author(s):  
ANDREI N. IVANOV
Keyword(s):  
Chiral Symmetry ◽  
Constituent Quark ◽  
Chiral Symmetry Breaking ◽  
Low Energy ◽  
Collective Excitations ◽  
Spontaneous Breaking ◽  
Matrix Elements ◽  
Energy Approximation ◽  
Meson States ◽  
Current Quark

By using the extended Nambu-Jona-Lasinio model for the low-energy approximation of QCD we derive the formulas, being due to spontaneous breaking of chiral symmetry and bosonization, and allowing to express matrix elements of any operator with current-quark fields in the definition in terms of matrix elements of this operator determined via constituent-quark fields interacting with low-lying meson states appearing as [Formula: see text]-collective excitations, which have the self-interactions too.

scholarly journals Detecting Cold Dark Matter Candidates

1987 ◽  
Vol 117 ◽  
pp. 490-490
Author(s):  
A. K. Drukier ◽  
K. Freese ◽  
D. N. Spergel
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Galactic Halo ◽  
Dark Matter Particle ◽  
Low Energy ◽  
The Sun ◽  
Background Rate ◽  
System Noise ◽  
Weakly Interacting ◽  
Massive Neutrinos

We consider the use of superheated superconducting colloids as detectors of weakly interacting galactic halo candidate particles (e.g. photinos, massive neutrinos, and scalar neutrinos). These low temperature detectors are sensitive to the deposition of a few hundreds of eV's. The recoil of a dark matter particle off of a superheated superconducting grain in the detector causes the grain to make a transition to the normal state. Their low energy threshold makes this class of detectors ideal for detecting massive weakly interacting halo particles.We discuss realistic models for the detector and for the galactic halo. We show that the expected count rate (≈103 count/day for scalar and massive neutrinos) exceeds the expected background by several orders of magnitude. For photinos, we expect ≈1 count/day, more than 100 times the predicted background rate. We find that if the detector temperature is maintained at 50 mK and the system noise is reduced below 5 × 10−4 flux quanta, particles with mass as low as 2 GeV can be detected. We show that the earth's motion around the Sun can produce a significant annual modulation in the signal.

scholarly journals Asymptotic expansion of low-energy excitations for weakly interacting bosons

2021 ◽  
Vol 9 ◽  
Author(s):  
Lea Boßmann ◽  
Sören Petrat ◽  
Robert Seiringer
Keyword(s):  
Asymptotic Expansion ◽  
Coulomb Potential ◽  
Mean Field ◽  
Low Energy ◽  
Energy Eigenstates ◽  
Bogoliubov Theory ◽  
Weakly Interacting ◽  
Repulsive Coulomb ◽  
The Mean

Abstract We consider a system of N bosons in the mean-field scaling regime for a class of interactions including the repulsive Coulomb potential. We derive an asymptotic expansion of the low-energy eigenstates and the corresponding energies, which provides corrections to Bogoliubov theory to any order in $1/N$ .

Strong collective excitations in low energy neutron scattering from transitional nuclei

1977 ◽  
Vol 16 (6) ◽  
pp. 2223-2237 ◽  
Author(s):  
D. F. Coope ◽  
S. N. Tripathi ◽  
M. C. Schell ◽  
J. L. Weil ◽  
M. T. McEllistrem
Keyword(s):  
Neutron Scattering ◽  
Low Energy ◽  
Collective Excitations ◽  
Energy Neutron

Faceting in dilute oxygen atmospheres of group VIA metals

1972 ◽  
Vol 331 (1586) ◽  
pp. 429-443 ◽  
Keyword(s):  
Activation Energy ◽  
Electron Diffraction ◽  
Smooth Surface ◽  
High Energy ◽  
Low Energy ◽  
Energy Electron ◽  
High Energy Electron ◽  
Ordered Structures ◽  
Surface Parameters ◽  
Chemisorbed Oxygen

Certain planes of the group VIA metals, Cr, Mo and W, which are stable in ultra high vacua, readily develop facets when heated at low homologous temperatures in oxygen pressures as low as 10 -6 Pa. We have investigated the (100) and (110) surfaces of these metals by both low energy and reflexion mode high-energy electron diffraction. The (100) surfaces of tungsten and molybdenum readily develop facets which are of {110} and {211} type. The faceting is preceded by the formation of various ordered structures characteristic of chemisorbed oxygen. The (100) surface of chromium is stable in oxygen; however, the (110) surface develops {100} facets. No simple ordered structures are observed on the (110) surface of chromium before faceting and the facets soon disappear beneath epitaxially grown oxide. On all three metals the faceting process is reversible. The smooth surface may be regenerated by heating in the absence of oxygen. The activation energy for this process is high. The effect of faceting on surface parameters is discussed with particular reference to the growth of oxide.

scholarly journals A ‘Dysonization’ scheme for identifying quasi-particles using non-Hermitian quantum mechanics

2013 ◽  
Vol 371 (1989) ◽  
pp. 20120056 ◽  
Author(s):  
Katherine Jones-Smith
Keyword(s):  
Quantum Mechanics ◽  
High Temperature ◽  
High Temperature Superconductivity ◽  
Spin Waves ◽  
Low Energy ◽  
Inner Product ◽  
Inner Products ◽  
Weakly Interacting

Dyson analysed the low-energy excitations of a ferromagnet using a Hamiltonian that was non-Hermitian with respect to the standard inner product. This allowed for a facile rendering of these excitations (known as spin waves) as weakly interacting bosonic quasi-particles. More than 50 years later, we have the full denouement of the non-Hermitian quantum mechanics formalism at our disposal when considering Dyson’s work, both technically and contextually. Here, we recast Dyson’s work on ferromagnets explicitly in terms of two inner products, with respect to which the Hamiltonian is always self-adjoint, if not manifestly ‘Hermitian’. Then we extend his scheme to doped anti-ferromagnets described by the t – J model, with hopes of shedding light on the physics of high-temperature superconductivity.

Complex geometry of space–time motivated by gravity’s rainbow

2019 ◽  
Vol 97 (5) ◽  
pp. 558-561
Author(s):  
Faizan Bhat ◽  
Mussadiq H. Qureshi ◽  
Manzoor A. Malik ◽  
Asif Iqbal
Keyword(s):  
Imaginary Part ◽  
Complex Space ◽  
Complex Geometry ◽  
Planck Scale ◽  
Space Time ◽  
Low Energy ◽  
Gravity’S Rainbow ◽  
Gravity's Rainbow ◽  
Energy Approximation ◽  
Planck Energy

In this paper, we generalize the formalism of gravity’s rainbow to complex space–time. The resulting geometry depends on the energy of the probe in such a way that the usual real manifold is the low energy approximation of the Planck scale geometry of space–time. So, our formalism agrees with all the observational data about our space–time being real, as at the scale these experiments are preformed, the imaginary part of the geometry is suppressed by Planck energy. However, the imaginary part of the geometry becomes important near the Planck energy, and so it cannot be neglected near the Planck scale. So, the Planck scale geometry of space–time is described by a complex manifold.

Diffusion in High Occupancy Zeolites

1987 ◽  
Vol 111 ◽  
Author(s):  
James Wei
Keyword(s):  
Activation Energy ◽  
Random Walk ◽  
Small Molecules ◽  
Irreversible Thermodynamics ◽  
Low Energy ◽  
The Other ◽  
Diffusion Region ◽  
Channel Diameter ◽  
One Dimensional ◽  
Activation Energy Of Diffusion

AbstractDiffusion of small molecules in zeolites most often takes place in the configurational diffusion region, where the molecular diameter is approximately the same or slightly greater than the channel diameter. Since two molecules may not pass each other in a pore, the random walk based diffusion equation does not apply under high occupancy conditions in zeolites with one-dimensional pores.For zeolites with multi-dimensional pores, such as ZSM-5 and A, one sometimes encounters the counter-intuitive result that diffusivity dramatically rises with occupancy. There are two explanations for this behavior: one from irreversible thermodynamics and the Darken equation, which predicts that diffusivity will always rise with occupancy; the other from a Markov model of random activated jumps between low energy positions, such as pore crossings, which predicts that diffusivity will increase with occupancy if the activation energy of diffusion decreases with occupancy– such as due to swelling.

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