4,417 research outputs found
Quantum oscillations in topological superconductor candidate CuBiSe
Quantum oscillations are generally studied to resolve the electronic
structure of topological insulators. In CuBiSe, the prime
candidate of topological superconductors, quantum oscillations are still not
observed in magnetotransport measurement. However, using torque magnetometry,
quantum oscillations (the de Hass - van Alphen effect) were observed in
CuBiSe . The doping of Cu in BiSe increases the
carrier density and the effective mass without increasing the scattering rate
or decreasing the mean free path. In addition, the Fermi velocity remains the
same in CuBiSe as that in BiSe. Our results imply that
the insertion of Cu does not change the band structure of BiSe.Comment: 5 pages, 4 figure
-pairing interaction, number of states, and nine- sum rules of four identical particles
In this paper we study -pairing Hamiltonian and find that the sum of
eigenvalues of spin states equals sum of norm matrix elements within the
pair basis for four identical particles such as four fermions in a single-
shell or four bosons with spin . We relate number of states to sum rules of
nine- coefficients. We obtained sum rules for nine- coefficients
summing
over (1) even and , (2) even and odd , (3) odd and odd ,
and (4) both even and odd , where is a half integer and is an
integer.Comment: 6 pages, no figure, updated version, to be published. Physical Review
C, in pres
Fermionic Symmetries: Extension of the two to one Relationship Between the Spectra of Even-Even and Neighbouring Odd mass Nuclei
In the single j shell there is a two to one relationship between the spectra
of certain even-even and neighbouring odd mass nuclei e.g. the calculated
energy levels of J=0^+ states in ^{44}Ti are at twice the energies of
corresponding levels in ^{43}Ti(^{43}Sc) with J=j=7/2. Here an approximate
extension of the relationship is made by adopting a truncated seniority scheme
i.e. for ^{46}Ti and ^{45}Sc we get the relationship if we do not allow the
seniority v=4 states to mix with the v=0 and v=2 states. Better than that, we
get very close to the two to one relationship if seniority v=4 states are
admixed perturbatively. In addition, it is shown that the higher isospin states
do not contain seniority 4 admixtures.Comment: 11 pages, RevTex file and no figures, typos added, references changed
and changed content
Phosphorus adsorption, rice dry matter yield, and P use efficiency as influenced by phosphorus fertilizer rates in rainfed lowland soils in Togo
The study focused on improving phosphorus (P) fertilizer recommendation in rainfed lowland rice soils in Togo. Phosphorus adsorption was conducted on four soils to determine their P adsorption characteristics and standard phosphorus requirement (SPR). The adsorption maximum ranged from 143 to 200 mg P/kg. The amount of P adsorbed range from 62.70 to 74.85 mg P/kg. Greenhouse experiment was conducted to determine rice response to phosphorus rates based on the SPR values, and to assess rice P uptake and use efficiency. Five phosphorus rates, Control: 0 mg P kg−1, P recommended rate (RR): 5 mg P kg−1, 4 × RR: 20 mg P kg−1, 50% SPR and 100% SPR were used. Results indicated no significant difference between the Control treatment and the P recommended rate (RR), and between the 50% SPR and the 100% SPR with reference to shoot dry matter yield. P uptake and P use efficiency were significantly and positively influenced by the various P fertilizer rates. From the study, the blanket P recommended rate is inappropriate, however, site-specific P fertilizer rate of 50% SPR may be recommended to improve rainfed lowland rice yields in Togo
Isoscalar g Factors of Even-Even and Odd-Odd Nuclei
We consider T=0 states in even-even and odd-odd N=Z nuclei. The g factors
that emerge are isoscalar. We find that the single j shell model gives simple
expressions for these g factors which for even-even nuclei are suprisingly
close to the collective values for K=0 bands. The g factors of many 2+ in
even-even nuclei and 1+ and 3+ states in odd-odd nuclei have g factors close to
0.5
Particle Kinematics in Horava-Lifshitz Gravity
We study the deformed kinematics of point particles in the Horava theory of
gravity. This is achieved by considering particles as the optical limit of
fields with a generalized Klein-Gordon action. We derive the deformed geodesic
equation and study in detail the cases of flat and spherically symmetric
(Schwarzschild-like) spacetimes. As the theory is not invariant under local
Lorenz transformations, deviations from standard kinematics become evident even
for flat manifolds, supporting superluminal as well as massive luminal
particles. These deviations from standard behavior could be used for
experimental tests of this modified theory of gravity.Comment: Added references, corrected a typing erro
Dotted and Undotted Algebraic Spinor Fields in General Relativity
We investigate using Clifford algebra methods the theory of algebraic dotted
and undotted spinor fields over a Lorentzian spacetime and their realizations
as matrix spinor fields, which are the usual dotted and undotted two component
spinor fields. We found that some ad hoc rules postulated for the covariant
derivatives of Pauli sigma matrices and also for the Dirac gamma matrices in
General Relativity cover important physical meaning, which is not apparent in
the usual matrix presentation of the theory of two components dotted and
undotted spinor fields. We also discuss some issues related to the the previous
one and which appear in a proposed "unified" theory of gravitation and
electromagnetism which use two components dotted and undotted spinor fields and
also paravector fields, which are particular sections of the even subundle of
the Clifford bundle of spacetime.Comment: some new misprints have been correcte
Gauge Formalism for General Relativity and Fermionic Matter
A new formalism for spinors on curved spaces is developed in the framework of
variational calculus on fibre bundles. The theory has the same structure of a
gauge theory and describes the interaction between the gravitational field and
spinors. An appropriate gauge structure is also given to General Relativity,
replacing the metric field with spin frames. Finally, conserved quantities and
superpotentials are calculated under a general covariant form.Comment: 18 pages, Plain TEX, revision, explicit expression for superpotential
has been adde
Zettawatt-Exawatt Lasers and Their Applications in Ultrastrong-Field Physics: High Energy Front
Since its birth, the laser has been extraordinarily effective in the study
and applications of laser-matter interaction at the atomic and molecular level
and in the nonlinear optics of the bound electron. In its early life, the laser
was associated with the physics of electron volts and of the chemical bond.
Over the past fifteen years, however, we have seen a surge in our ability to
produce high intensities, five to six orders of magnitude higher than was
possible before. At these intensities, particles, electrons and protons,
acquire kinetic energy in the mega-electron-volt range through interaction with
intense laser fields. This opens a new age for the laser, the age of nonlinear
relativistic optics coupling even with nuclear physics. We suggest a path to
reach an extremely high-intensity level W/cm in the coming
decade, much beyond the current and near future intensity regime W/cm, taking advantage of the megajoule laser facilities. Such a laser at
extreme high intensity could accelerate particles to frontiers of high energy,
tera-electron-volt and peta-electron-volt, and would become a tool of
fundamental physics encompassing particle physics, gravitational physics,
nonlinear field theory, ultrahigh-pressure physics, astrophysics, and
cosmology. We focus our attention on high-energy applications in particular and
the possibility of merged reinforcement of high-energy physics and ultraintense
laser.Comment: 25 pages. 1 figur
Dirac-Hestenes spinor fields in Riemann-Cartan spacetime
In this paper we study Dirac-Hestenes spinor fields (DHSF) on a
four-dimensional Riemann-Cartan spacetime (RCST). We prove that these fields
must be defined as certain equivalence classes of even sections of the Clifford
bundle (over the RCST), thereby being certain particular sections of a new
bundle named Spin-Clifford bundle (SCB). The conditions for the existence of
the SCB are studied and are shown to be equivalent to the famous Geroch's
theorem concerning to the existence of spinor structures in a Lorentzian
spacetime. We introduce also the covariant and algebraic Dirac spinor fields
and compare these with DHSF, showing that all the three kinds of spinor fields
contain the same mathematical and physical information. We clarify also the
notion of (Crumeyrolle's) amorphous spinors (Dirac-K\"ahler spinor fields are
of this type), showing that they cannot be used to describe fermionic fields.
We develop a rigorous theory for the covariant derivatives of Clifford fields
(sections of the Clifford bundle (CB)) and of Dirac-Hestenes spinor fields. We
show how to generalize the original Dirac-Hestenes equation in Minkowski
spacetime for the case of a RCST. Our results are obtained from a variational
principle formulated through the multiform derivative approach to Lagrangian
field theory in the Clifford bundle.Comment: 45 pages, special macros kapproc.sty and makro822.te
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