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排序方式: 共有717条查询结果,搜索用时 15 毫秒
711.
712.
Amrita Mandal Anindita Bose Sreemanta Mitra Anindya Datta Sourish Banerjee Dipankar Chakravorty 《Journal of magnetism and magnetic materials》2012
Nanoplates of NiS with thickness 0.6 nm were grown within the crystal channels of Na-4 mica. The thickness of the nanoplates is confirmed by atomic force microscopy. The nanocomposites exhibited multiferroic (both ferromagnetic and ferroelectric) behavior at room temperature. Ferromagnetism was adduced to an increase of surface defects as a result of the two-dimensional configuration of the sample. Ferroelectric behavior was explained as arising due to a small distortion in the crystal structure of NiS grown within the Na-4 mica channels. This was substantiated by the refined values of lattice constants as determined by profile matching of X-ray data by a computer program. A magnetodielectric effect was also observed in this nanocomposite with a change of 0.77% in the dielectric constant for a magnetic field of 0.6 T. 相似文献
713.
Abazov VM Abbott B Acharya BS Adams M Adams T Alexeev GD Alkhazov G Alton A Alverson G Alves GA Aoki M Arov M Askew A Asman B Atramentov O Avila C BackusMayes J Badaud F Bagby L Baldin B Bandurin DV Banerjee S Barberis E Baringer P Barreto J Bartlett JF Bassler U Bazterra V Beale S Bean A Begalli M Begel M Belanger-Champagne C Bellantoni L Beri SB Bernardi G Bernhard R Bertram I Besançon M Beuselinck R Bezzubov VA Bhat PC Bhatnagar V Blazey G Blessing S Bloom K Boehnlein A Boline D Boos EE 《Physical review letters》2012,108(2):021801
We present a search for pair production of doubly charged Higgs bosons in the processes qqˉ→H(++)H(--) decaying through H(±±)→τ(±)τ(±),μ(±)τ(±),μ(±)μ(±). The search is performed in ppˉ collisions at a center-of-mass energy of √s = 1.96 TeV using an integrated luminosity of up to 7.0 fb(-1) collected by the D0 experiment at the Fermilab Tevatron Collider. The results are used to set 95% C.L. limits on the pair production cross section of doubly charged Higgs bosons and on their mass for different H(±±) branching fractions. Models predicting different H(±±) decays are investigated. Assuming B(H(±±)→τ(±)τ(±))=1 yields an observed (expected) lower limit on the mass of a left-handed H(L)(±±) boson of 128 (116) GeV and assuming B(H(±±)→μ(±)τ(±))=1 the corresponding limits are 144 (149) GeV. In a model with B(H(±±)→τ(±)τ(±))=B(H(±±)→μ(±)τ(±))=B(H(±±)→μ(±)μ(±))=1/3, we obtain M(H(L)(±±))>130 (138) GeV. 相似文献
714.
We present some solutions of late time transition to an accelerating universe showing a quintessence or a de-Sitter era of
expansion at late time using Gauss-Bonnet interaction in a Jordan Brans-Dicke theory in FLRW spacetime. The Gauss-Bonnet term
yields an effective cosmological constant characterized by a de-Sitter era of late time expansion when the Gauss-Bonnet interaction
is equivalent with an ideal fluid. The quintessence era of late time expansion have been obtained assuming the evolution of
scalar field is a single valued function. The Chameleon mechanism shows that the correction to the Newton law could be small. 相似文献
715.
A. K. Pal I. Bose 《The European Physical Journal B - Condensed Matter and Complex Systems》2012,85(1):36
The transverse Ising Model (TIM) in one dimension is the simplest model which exhibits a quantum phase transition (QPT). Quantities
related to quantum information theoretic measures like entanglement, quantum discord (QD) and fidelity are known to provide
signatures of QPTs. The issue is less well explored when the quantum system is subjected to decoherence due to its interaction,
represented by a quantum channel, with an environment. In this paper we study the dynamics of the mutual information I(ρ
AB
), the classical correlations C(ρ
AB
) and the quantum correlations Q(ρ
AB
), as measured by the QD, in a two-qubit state the density matrix of which is the reduced density matrix obtained from the
ground state of the TIM in 1d. The time evolution brought about by system-environment interactions is assumed to be Markovian
in nature and the quantum channels considered are amplitude damping, bit-flip, phase-flip and bit-phase-flip. Each quantum
channel is shown to be distinguished by a specific type of dynamics. In the case of the phase-flip channel, there is a finite
time interval in which the quantum correlations are larger in magnitude than the classical correlations. For this channel
as well as the bit-phase-flip channel, appropriate quantities associated with the dynamics of the correlations can be derived
which signal the occurrence of a QPT. 相似文献
716.
717.