共查询到20条相似文献,搜索用时 31 毫秒
1.
Riazuddin 《The European Physical Journal C - Particles and Fields》2007,51(3):697-699
It is proposed that light neutrinos form a triplet in a global SU(3) symmetry in the mass eigenstate basis. Assuming that
the SU(3) symmetry is broken in the direction , and after going to the flavor basis, we predict the atmospheric mixing angles sin2θ23=0.5 and sinθ13=0, if νμ–ντ symmetry is assumed. In the flavor basis, the diagonal part of the matrix coefficient of b (the dominant part) is found to
transform like . Imposing the same condition on the matrix coefficient of a fixes the solar mixing angle, . The implications for neutrinoless double beta decay are discussed. 相似文献
2.
Pulak Ranjan Giri 《International Journal of Theoretical Physics》2008,47(7):2095-2100
We show that the total time of evolution from the initial quantum state to final quantum state and then back to the initial
state, i.e., making a round trip along the great circle over S
2, must have a lower bound in quantum mechanics, if the difference between two eigenstates of the 2×2 Hamiltonian is kept fixed.
Even the non-hermitian quantum mechanics can not reduce it to arbitrarily small value. In fact, we show that whether one uses
a hermitian Hamiltonian or a non-hermitian, the required minimal total time of evolution is same. It is argued that in hermitian
quantum mechanics the condition for minimal time evolution can be understood as a constraint coming from the orthogonality
of the polarization vector P of the evolving quantum state
with the vector
of the 2×2 hermitian Hamiltonians
and it is shown that the Hamiltonian H can be parameterized by two independent parameters
and Θ. 相似文献
3.
Shao-Long Chen Xiao-Gang He Xue-Peng Hu Yi Liao 《The European Physical Journal C - Particles and Fields》2009,60(2):317-321
An unparticle
with scaling dimension
has peculiar thermal properties due to its unique phase space structure. We find that the equation of state parameter
, the ratio of pressure to energy density, is given by
providing a new form of energy in our universe. In an expanding universe, the unparticle energy density
evolves dramatically differently from that for photons. For
, even if
at a high decoupling temperature T
D is very small, it is possible to have a large relic density
at present photon temperature T
γ
0, large enough to play the role of dark matter. We calculate T
D and
using photon–unparticle interactions for illustration. 相似文献
4.
In this work, we investigate the thermal entanglement for interacting spin systems , by varying the parameters of temperature T, direction and magnetic field B.
PACS numbers: 03.67.Mn, 03.65.Ud, 05.30.Cd, 73.43.Nq 相似文献
5.
Keitaro Nagata Atsushi Hosaka V. Dmitrašinović 《The European Physical Journal C - Particles and Fields》2008,57(3):557-567
We study the chiral transformation properties of all possible local (non-derivative) interpolating field operators for baryons
consisting of three quarks with two flavors, assuming good isospin symmetry. We derive and use the relations/identities among
the baryon operators with identical quantum numbers that follow from the combined color, Dirac and isospin Fierz transformations.
These relations reduce the number of independent baryon operators with any given spin and isospin. The Fierz identities also
effectively restrict the allowed baryon chiral multiplets. It turns out that the non-derivative baryons’ chiral multiplets
have the same dimensionality as their Lorentz representations. For the two independent nucleon operators the only permissible
chiral multiplet is the fundamental one,
. For the Δ, admissible Lorentz representations are
and
. In the case of the
chiral multiplet, the
Δ field has one
chiral partner; otherwise it has none. We also consider the Abelian (U
A(1)) chiral transformation properties of the fields and show that each baryon comes in two varieties: (1) with Abelian axial
charge +3; and (2) with Abelian axial charge −1. In case of the nucleon these are the two Ioffe fields; in case of the Δ, the
multiplet has an Abelian axial charge −1 and the
multiplet has an Abelian axial charge +3. 相似文献
6.
Omar Mustafa S. Habib Mazharimousavi 《International Journal of Theoretical Physics》2009,48(1):183-193
Non-Hermitian but
-symmetrized spherically-separable Dirac and Schr?dinger Hamiltonians are considered. It is observed that the descendant Hamiltonians
H
r
, H
θ
, and H
φ
play essential roles and offer some “user-feriendly” options as to which one (or ones) of them is (or are) non-Hermitian.
Considering a
-symmetrized H
φ
, we have shown that the conventional Dirac (relativistic) and Schr?dinger (non-relativistic) energy eigenvalues are recoverable.
We have also witnessed an unavoidable change in the azimuthal part of the general wavefunction. Moreover, setting a possible
interaction V(θ)≠0 in the descendant Hamiltonian H
θ
would manifest a change in the angular θ-dependent part of the general solution too. Whilst some
-symmetrized H
φ
Hamiltonians are considered, a recipe to keep the regular magnetic quantum number m, as defined in the regular traditional Hermitian settings, is suggested. Hamiltonians possess properties similar to the
-symmetric ones (here the non-Hermitian
-symmetric Hamiltonians) are nicknamed as pseudo-
-symmetric. 相似文献
7.
J. Ellis F. Moortgat G. Moortgat-Pick J. M. Smillie J. Tattersall 《The European Physical Journal C - Particles and Fields》2009,60(4):633-651
We study the potential observation at the LHC of CP-violating effects in stop production and subsequent cascade decays,
,
,
, within the Minimal Supersymmetric Standard Model. We study T-odd asymmetries based on triple products between the different
decay products. There may be a large CP asymmetry at the parton level, but there is a significant dilution at the hadronic
level after integrating over the parton distribution functions. Consequently, even for scenarios where large CP intrinsic
asymmetries are expected, the measurable asymmetry is rather small. High luminosity and precise measurements of masses, branching
ratios and CP asymmetries may enable measurements of the CP-violating parameters in cascade decays at the LHC. 相似文献
8.
Chao-Hsi Chang Jiao-Kai Chen Zhen-Yun Fang Bing-Quan Hu Xing-Gang Wu 《The European Physical Journal C - Particles and Fields》2007,50(4):969-978
The light top-squark may be the lightest squark, and its lifetime may be ‘long enough’ in a kind of SUSY models that have not been ruled out yet
experimentally, so colorless ‘supersymmetric hadrons (superhadrons)’ (q is a quark excluding the t-quark) may be formed as long as the light top-squark can be produced. The fragmentation function of into heavy ‘supersymmetric hadrons (superhadrons)’ (Q̄=c̄ or b̄) and hadronic production of the superhadrons are investigated quantitatively. The fragmentation function is
calculated precisely. Due to the difference in spin of the SUSY component, the asymptotic behavior of the fragmentation function
is different from those of the existing ones. The fragmentation function is also applied to compute the production of heavy
superhadrons at the hadronic colliders Tevatron and LHC in the so-called fragmentation approach. The resultant cross-section
for the heavy superhadrons is too small to observe at Tevatron, but large enough at LHC, when all the relevant parameters
in the SUSY models are taken within the favored region for the heavy superhadrons. The production of ‘light superhadrons’
(q=u,d,s) is also roughly estimated with the same SUSY parameters. It is pointed out that the production cross-sections of
the light superhadrons may be much greater than those of the heavy superhadrons, so that even at Tevatron the light superhadrons may be produced
in great quantities.
PACS 12.38.Bx; 13.87.Fh; 12.60.Jv; 14.80.Ly 相似文献
9.
In this paper, we apply the method of “invariant eigen-operator” to study the Hamiltonian of harmonic oscillator with couplings
and derive their invariant eigen-operator. We first discuss decoupling of coupled harmonic oscillators with the two different
quality and frequencies. And then, we propose an operator Hamiltonian to describe the linear lattice chain with Born–von Karman
boundary condition. The vibrating spectrum is thus obtained. The results show that, for the system of coupled harmonic oscillators
by coordinate coupling or momentum coupling, the invariant eigen operator
of system always has the form of
or
. 相似文献
10.
11.
Liu Yong-Mei 《International Journal of Theoretical Physics》2009,48(8):2372-2378
In this paper, we apply the method of “invariant eigen-operator” to study the Hamiltonian of arbitrary number of coupled identical
oscillators and derive their invariant eigen-operator. The results show that, (1) for the system of arbitrary number of identical
harmonic oscillators by coordinate coupling or momentum coupling, the invariant eigen operator
of system always has the form of
or
; (2) the energy level gap of the system has two kinds of possibilities: one is that gap only related to ω that the frequency of oscillators; another one is that gap not only related to ω that the frequency of oscillators, but also related to the number of the coupling oscillators. 相似文献
12.
We introduce a family of real random polynomials of degree n whose coefficients a
k
are symmetric independent Gaussian variables with variance
, indexed by a real α≥0. We compute exactly the mean number of real roots 〈N
n
〉 for large n. As α is varied, one finds three different phases. First, for 0≤α<1, one finds that
. For 1<α<2, there is an intermediate phase where 〈N
n
〉 grows algebraically with a continuously varying exponent,
. And finally for α>2, one finds a third phase where 〈N
n
〉∼n. This family of real random polynomials thus exhibits a condensation of their roots on the real line in the sense that, for
large n, a finite fraction of their roots 〈N
n
〉/n are real. This condensation occurs via a localization of the real roots around the values
, 1≪k≤n. 相似文献
13.
The possible range of the η– mixing angle is determined from the transition form factors Fηγ(Q2) and with the help of up-to-date experimental data. For this purpose, the quark-flavor mixing scheme is adopted and the pseudoscalar
transition form factors are calculated in the framework of light-cone pQCD, in which the transverse-momentum corrections and
the contributions beyond the leading Fock state have been carefully taken into consideration. We construct a phenomenological
expression to estimate the contributions to the form factors beyond the leading Fock state, based on their asymptotic behavior
at Q2→0 and . By taking the quark-flavor mixing scheme, our results lead to , where the first error comes from the experimental uncertainty and the second error from the uncertainties of the parameters
of the wavefunction. The possible intrinsic charm component in η and is discussed, and our present analysis also disfavors a large intrinsic charm component in η and , e.g. .
PACS 13.40.Gp; 12.38.Bx; 14.40.Aq 相似文献
14.
M. Kreuzer R. C. Rashkov M. Schimpf 《The European Physical Journal C - Particles and Fields》2009,60(3):471-480
The non-linear nature of string theory on non-trivial backgrounds, related to the AdS/CFT correspondence, force one to look
for simplifications. Two such simplifications proved to be useful in studying string theory. These are the pp-wave limit,
which describes point-like strings, and the so-called “near-flat space” limit which connects two different sectors of string
theory—pp-wave and “giant magnons”. Recently another example of AdS/CFT duality emerged—AdS
4/CFT
3, which suggests duality between
CS theory and superstring theory on
. In this paper we study the “near-flat space” limit of strings on an
background and discuss possible applications of the limiting theory.
R.C. Rashkov is on leave from Department of Physics, Sofia University, Bulgaria. 相似文献
15.
Michalis Velegrakis Maria Massaouti Maria Jadraque 《Applied Physics A: Materials Science & Processing》2012,108(1):127-131
Titanium oxide cluster cations $\mathrm{Ti}_{x}\mathrm{O}_{y}^{+}$ are produced in a molecular beam by combining laser ablation of titanium with the supersonic expansion of oxygen into vacuum. The size distribution of the clusters produced is analyzed by time-of-flight reflectron mass spectrometry. The stable clusters appearing in the mass spectrum can be described by the general formula $(\mathrm{TiO})_{m}(\mathrm{TiO}_{2})_{n}(\mathrm{O}_{2})_{k}^{+}$ (with m,n=0,1,2,?? and k=0,1). Additionally, collision-induced dissociation studies of mass selected clusters colliding with Kr atoms in a gas cell have been performed. The results show that the clusters lose neutral O2, TiO and/or (TiO2) n units, and the remaining charged fragments are those with the lowest ionization potentials. From these results the fragmentation cross section of the selected clusters is obtained. 相似文献
16.
The identification of the fougerite mineral responsible for the bluish-green shade of gleysols in aquifers as being the FeII???III oxyhydroxycarbonate $\text{GR}(\text{CO}_{3}^{2-})^*$ of formula, $[\text{Fe}^{\rm II}_{6x}\text{Fe}^{\rm III}_{6(1 - x)}\text{O}_{12}\text{H}_{2(7-3x)}]^{2+}\bullet[\text{CO}_{3}^{2-}\bullet3\text{H}_{2}\text{O}]^{2-}$ where the ferric molar ratio x = [FeIII/Fetotal] is restricted to the domain [1/3–2/3] induces to study the reactivity of the synthetic green rust for reducing some major pollutants. The oxidation within the solid compound $\text{GR}(\text{CO}_{3}^{2-})^*$ in the presence of nitrates is followed by miniaturized Mössbauer spectrometer (MIMOS). Ratio x = [FeIII/Fetotal] increases up to 0.67 where $\text{GR}(\text{CO}_{3}^{2-})^*$ transforms gradually into magnetite. This could well explain the composition variability of fougerite occurrences. 相似文献
17.
R. K. Niven 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,70(1):49-63
We examine the combinatorial or probabilistic definition (“Boltzmann’s principle”) of the entropy or cross-entropy function
H ∝ or D ∝ - , where is the statistical weight and the probability of a given realization of a system. Extremisation of H or D, subject to any constraints, thus selects the
“most probable” (MaxProb) realization. If the system is multinomial, D converges asymptotically (for number of entities N
↦∞) to the Kullback-Leibler cross-entropy DKL; for equiprobable categories in a system, H converges to the Shannon entropy HSh. However, in many cases or is not multinomial and/or does not satisfy an asymptotic limit. Such systems cannot meaningfully be analysed with DKL or HSh, but can be analysed directly by MaxProb. This study reviews several examples, including (a) non-asymptotic systems; (b)
systems with indistinguishable entities (quantum statistics); (c) systems with indistinguishable categories; (d) systems represented
by urn models, such as “neither independent nor identically distributed” (ninid) sampling; and (e) systems representable in
graphical form, such as decision trees and networks. Boltzmann’s combinatorial definition of entropy is shown to be of greater
importance for “probabilistic inference” than the axiomatic definition used in information theory. 相似文献
18.
Andrei A. Zagorodni German Salazar-Alvarez Mamoun Muhammed 《Journal of nanoparticle research》2008,10(2):377-381
Formation of elongated nanoparticles was observed when was precipitated from solutions containing excess of Fe2+. The average diameter of the particles was 23 nm; the length to diameter ratio was up to 14. This shape was an unexpected
phenomenon because bar- or needle-like nanoparticles have been earlier reported only for Fe(III)-based materials. Chemical
analysis revealed Fe(OH)2 nature of the obtained particles. In addition, this conclusion was verified with a new simple method for quantitative evaluation
of the particle morphology. Application of this method to the mixed samples allowed to distinguish between the two different compounds and to attribute different morphologies to Fe(OH)2 or Results indicate that bars are frequent shapes of nano-sized iron oxides/hydroxides. 相似文献
19.
T. I. Milenov T. Tenev I. Miloushev G. V. Avdeev C. W. Luo W. C. Chou 《Optical and Quantum Electronics》2014,46(4):573-580
The theoretical calculations indicated that the monoclinic low-temperature phase of silver telluride $(\upbeta \hbox {-Ag}_{2}\hbox {Te})$ is a new binary topological insulator with highly anisotropic single Dirac cone surface. We obtained $\upbeta \hbox {-Ag}_{2}\hbox {Te}$ crystal ingots containing few grains by the Bridgman method. We also deposited thin films of tellurium, $\hbox {Ag}_{5}\hbox {Te}_{3}\hbox { and }(\hbox {Te+Ag}_{5}\hbox {Te}_{3})$ by thermal evaporation method. The Raman spectra of $\upbeta \hbox {-Ag}_{2}\hbox {Te}$ , tellurium and $\hbox {Ag}_{5}\hbox {Te}_{3}$ were measured at three excitation wave lengths: 633, 515 and 488 nm. The Raman active modes of $\upbeta \hbox {-Ag}_{2}\hbox {Te}$ , tellurium and $\hbox {Ag}_{5}\hbox {Te}_{3}$ are situated at frequencies below 300 $\hbox {cm}^{-1}$ while vibrations of other phases appear at higher frequencies. 相似文献
20.
In terms of the
loop algebra and the algebraic Bethe-ansatz method, we derive the invariant subspace associated with a given Ising-like spectrum
consisting of 2
r
eigenvalues of the diagonal-to-diagonal transfer matrix of the superintegrable chiral Potts (SCP) model with arbitrary inhomogeneous
parameters. We show that every regular Bethe eigenstate of the τ
2-model leads to an Ising-like spectrum and is an eigenvector of the SCP transfer matrix which is given by the product of two
diagonal-to-diagonal transfer matrices with a constraint on the spectral parameters. We also show in a sector that the τ
2-model commutes with the
loop algebra,
, and every regular Bethe state of the τ
2-model is of highest weight. Thus, from physical assumptions such as the completeness of the Bethe ansatz, it follows in the
sector that every regular Bethe state of the τ
2-model generates an
-degenerate eigenspace and it gives the invariant subspace, i.e. the direct sum of the eigenspaces associated with the Ising-like
spectrum. 相似文献