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1.
M. van Leeuwen 《The European Physical Journal C - Particles and Fields》2009,61(4):569-574
We present selected recent results of multi-hadron correlation measurements in azimuth and pseudorapidity at intermediate
and high p
T
in Au+Au collisions at
, from the STAR experiment at RHIC. At intermediate p
T
, measurements are presented that attempt to determine the origin of the associated near-side (small Δφ) yield at large pseudo-rapidity difference Δη that is found to be present in heavy ion collisions. In addition, results are reported on new multi-hadron correlation measures
at high-p
T
that use di-hadron triggers and multi-hadron cluster triggers with the goal to constrain the underlying jet kinematics better
than in the existing measurements of inclusive spectra and di-hadron correlations. 相似文献
2.
Saskia Mioduszewski 《The European Physical Journal C - Particles and Fields》2009,61(4):741-745
Results on high-p
T
probes shown at the Hard Probes 2008 Conference are summarized, with an appreciation of the improvements in precision of
the measurements and experimental techniques since the beginning of RHIC operation. Particular attention is given to the latest
measurements of the nuclear modification factor of identified particles, photon-hadron correlation measurements, and full
jet reconstruction. 相似文献
3.
K. A. Shaykhutdinov S. I. Popkov A. N. Lavrov L. P. Kozeeva M. Yu. Kameneva V. V. Val’kov D. M. Dzebisashvili A. D. Fedoseev 《JETP Letters》2010,92(5):332-337
The behavior of the low-temperature specific heat C(T) for YBa2Cu3O6 + x
single crystals with the doping level corresponding to the normal phase has been studied by the relaxation technique at different
values of the applied magnetic field. It has been found that the C(T)/T plot exhibits such an anomaly as a steep increase with decreasing temperature from T about 4 K down to T ≤ 2 K (the minimum temperature value accessible in the experiment). The applied magnetic field as high as 9 T inverts this
anomaly and leads to a sharp drop in C(T)/T during cooling within the same temperature range. A model involving the Schottky-type centers formulated in this work and
the data on spin correlation functions has allowed us to calculate the temperature dependence of the specific heat, which
fits the experimental curves quite well. 相似文献
4.
N. K. Pruthi 《The European Physical Journal C - Particles and Fields》2009,62(1):165-167
In this paper we look for correlations between intermediate p
T
particle pairs and the v
2 of the remaining low p
T
particles. We find that the shape of the flow vector distribution, which is calculated from all low p
T
tracks, depends in a non-trivial way on the angular separation between the high p
T
particle pairs in the event. Our analysis is based on 200 GeV Au+Au collisions measured with the STAR detector. 相似文献
5.
V. I. Petinov 《Technical Physics》2017,62(6):882-889
Influence of temperature and magnetic field H on magnetism of spherical Gd nanoparticles of different sizes (89, 63, 47, 28, and 18 nm) was studied in the temperature range 250 K < T < 325 K. The particles were obtained by metal vapor condensation in the flow of helium. The particles with d = 18 nm did not show a magnetic transition; their structure is a combination of two cubic phases (FCC1 and FCC2). Large particles remained in the HCP phase and had an admixture of the FCC1 phase, the amount of which decreased as the particle sizes increased; magnetic transition took place at T c = 293 K. The admixture of O2 did not alter the structure but decreased the magnetization σ and magnetic permeability μ. An orientation transition in polycrystalline gadolinium initiated by the magnetic field H was proved in an experiment. The orientation transition in Gd particles smaller than 63 nm, the magnetic structure of which is close to the single-domain structure, occurred near T c without the influence of H. 相似文献
6.
M. Hamani Daouda Manuel E. Rodrigues M. J. S. Houndjo 《The European Physical Journal C - Particles and Fields》2011,71(11):1817
We consider the equations of motion of an anisotropic space-time in f(T) theory, where T is the torsion. New spherically symmetric solutions of black holes and wormholes are obtained with a constant torsion and
for the cases for which the radial pressure is proportional to a real constant, to some algebraic functions f(T) and their derivatives f
T
(T), or vanishes identically. 相似文献
7.
During the last decade, as the experimental and computing means and techniques have rapidly evolved, the experimental investigation of the f7/2-shell nuclei has gained renewed interest. TheN = Z nuclei studied with the GASP array range from 44Ti to 52Fe. The results extended the knowledge of their structure up to high spins and excitation energies, above band terminations, where the competition with the charged-particles emission was initially thought to obscure the possibility of gamma-ray spectroscopy investigation. The paper highlights some of the most outstanding properties of these nuclei such as the nuclear rotation and backbending effects, band termination states, yrast traps, non-natural parity bands, competition between T = 0 and T = 1 pn pairing modes.Received: 30 October 2002, Published online: 16 March 2004PACS:
21.10.-k Properties of nuclei; nuclear energy levels - 21.60.Cs Shell model - 23.20.Lv
transitions and level energies - 27.40. + z
C.A. Ur: On leave from NIPNE Bucharest, Romania 相似文献
8.
9.
V. V. Zubenko I. S. Tereshina I. V. Telegina E. A. Tereshina D. O. Luchev N. Yu. Pankratov 《Physics of the Solid State》2001,43(7):1273-1277
Thermal expansion and its anomalies in the vicinity of spin-reorientation phase transitions in single crystals of RFe11Ti (R=Y, Tb, Dy, Ho, and Er) compounds are investigated by the tensometric technique in the temperature range 77–400 K. The temperature dependences of the thermal expansion coefficient α(T) are obtained. It is found that the YFe11Ti and HoFe11Ti uniaxial magnetic materials exhibit pronounced anomalies in the α coefficient at T=200 and 290 K. For the TbFe11Ti single crystal, the α coefficient is close to zero in the vicinity of the spin-reorientation phase transition (at T=325 K). For the DyFe11Ti single crystal, which is characterized by two spin-reorientation phase transitions (at T=120 and 250 K), no features in the α(T) dependence are revealed in the region of the low-temperature spin-reorientation phase transition. In the ErFe11Ti single crystal, the specific feature of thermal expansion is observed at T ~ 220 K. 相似文献
10.
The theory of symmetries of systems of coupled, ordinary differential equations (ODE) is used to develop a concise algorithm
in order to obtain the entire space of solutions to vacuum Bianchi Einstein’s field equations (EFEs). The symmetries used
are the well known automorphisms of the Lie algebra for the corresponding isometry group of each Bianchi Type, as well as
the scaling and the time re-parametrization symmetry. The application of the method to Type V I I
h
results in (a) obtaining the general solution of Type V I I
0 with the aid of the third Painlevé transcendental P
I I I
; (b) obtaining the general solution of Type V I I
h
with the aid of the sixth Painlevé transcendental P
V I
; (c) the recovery of all known solutions (six in total) without a prior assumption of any extra symmetry; (d) The discovery
of a new solution (the line element given in closed form) with a G
3 isometry group acting on T
3, i.e., on time-like hyper-surfaces, along with the emergence of the line element describing the flat vacuum Type V I I
0 Bianchi Cosmology. 相似文献
11.
M. Hamani Daouda Manuel E. Rodrigues M. J. S. Houndjo 《The European Physical Journal C - Particles and Fields》2012,72(2):1890
In previous work, we undertook to study static and anisotropic content in f(T) theory and obtained new spherically symmetric solutions considering a constant torsion and some particular conditions for
the pressure. In this paper, still in the framework of f(T) theory, new spherically symmetric solutions are obtained, first considering the general case of an isotropic fluid and later
the anisotropic content case in which the generalized conditions for the matter content are considered such that the energy
density, the radial and tangential pressures depend on the algebraic f(T) and its derivative f
T
(T). Moreover, we obtain the algebraic function f(T) through the reconstruction method for two cases and also study a polytropic model for the stellar structure. 相似文献
12.
Using the theory of high-temperature superconductivity based on the idea of the fermion-condensation quantum phase transition (FCQPT), we show that neither the d-wave pairing symmetry, the pseudogap phenomenon, nor the presence of the Cu-O2 planes is of decisive importance for the existence of high-T c superconductivity. We analyze recent experimental data on this type of superconductivity in different materials and show that these facts can be understood within the theory of superconductivity based on the FCQPT. The latter can be considered as a universal cause of high-T c superconductivity. The main features of a room-temperature superconductor are discussed. 相似文献
13.
Y. Xiao Y. Su C. M. N. Kumar C. Ritter R. Mittal S. Price J. Perßon Th. Brückel 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,82(2):113-121
The physical and structural properties of Fe1.11Te and
Fe1.11Te0.5Se0.5 have been investigated by means of
X-ray and neutron diffraction as well as physical property
measurements. For the Fe1.11Te compound, the structure
distortion from a tetragonal to monoclinic phase takes place at 64 K
accompanied with the onset of antiferromagnetic order upon cooling.
The magnetic structure of the monoclinic phase was confirmed to be
of antiferromagnetic configuration with a propagation vector
k = (1/2, 0, 1/2) based on Rietveld refinement of neutron
powder diffraction data. The structural/magnetic transitions are
also clearly visible in magnetic, electronic and thermodynamic
measurements. For superconducting Fe1.11Te0.5Se0.5
compound, the superconducting transition with T
c
= 13.4 K
is observed in the resistivity and ac susceptibility measurements.
The upper critical field H
c2 is obtained by measuring
the resistivity under different magnetic fields. The Kim’s critical
state model is adopted to analyze the temperature dependence of the
ac susceptibility and the intergranular critical current density is
calculated as a function of both field amplitude and temperature.
Neutron diffraction results show that
Fe1.11Te0.5Se0.5 crystalizes in tetragonal structure
at 300 K as in the parent compound Fe1.11Te and no structural
distortion is detected upon cooling to 2 K. However an anisotropic
thermal expansion anomaly is observed around 100 K. 相似文献
14.
J. Gasser B. Kubis N. Paver M. Verbeni 《The European Physical Journal C - Particles and Fields》2005,40(2):205-227
Motivated by recent experimental results and ongoing measurements, we review the chiral perturbation theory prediction for
decays. Special emphasis is given to the stability of the inner bremsstrahlung-dominated relative branching ratio versus the K
e3 form factors, and on the separation of the structure-dependent amplitude in differential distributions over the phase space. For the structure-dependent terms, an assessment of the order p
6 corrections is given, in particular, a full next-to-leading order calculation of the axial component is performed. The experimental analysis of the photon energy spectrum is discussed, and other potentially useful distributions are introduced.Received: 9 December 2004, Published online: 21 February 2005PACS:
13.20.Eb, 11.30.Rd, 12.39.Fe 相似文献
15.
We analyze anew experiments on the NMR in cuprates and find an important information on their phase separation and its strip character hidden in the dependence of 1/63T1 on the degree of doping. In a broad class of materials, 1/63T1 is the sum of two terms: the temperature-independent one attributed to “ incommensurate” strips that occur at external doping and a “universal” temperature-dependent term ascribed to moving metallic and antiferromagnetic subphases. We argue that the frustrated first-order phase transition in a broad temperature interval bears a dynamical character. 相似文献
16.
I. V. Ovchinnikov T. A. Ivanova A. N. Turanov R. R. Garipov 《Physics of the Solid State》2009,51(10):2058-2063
Significant differences in the manifestation of spin-crossover properties of the mesogen compounds [FeL
2]X with oxysalicylidene-N′-ethyl-N-ethylenediamine ligands L and anions X = PF6− and SCH− have been found by means of electron paramagnetic resonance. The electron paramagnetic resonance data and the quantum-chemical
calculation within the density functional theory enables us to establish that the observed specific features are associated
with the incorporation of the SCH− ion into the first coordination sphere of the Fe(III) ion. The role of the transition of the material to the liquid-state
phase in the formation of a low-dimensional (two-dimensional) structure with stronger intermolecular interactions has been
revealed. 相似文献
17.
E. R. Podolyak 《Journal of Experimental and Theoretical Physics》2011,113(6):1035-1039
The emergence of surface superconductivity in a type I superconductor is considered taking into account the surface free energy
of the superconducting phase. It is shown that the disregard of the surface energy leads to a substantial error in determining
the Ginzburg-Landau parameter from the measurements of the H
c3 field. 相似文献
18.
I. R. Shein 《Physics of the Solid State》2018,60(10):2012-2018
The energies of formation of vacancies in the carbon and silicon sublattices, the independent elastic constants, the all-round compression, shear and Young’s moduli, and the anisotropy coefficients are determined for the complete and nonstoichiometric cubic phases of 3C-SixCy (x, y = 1.0–0.75) by ab initio methods of the band theory. In the formalism of the density functional perturbation theory (DFPT), the phonon dispersion dependences are obtained for these phases (the comparison with the experiment is given for the complete phase). It is shown that the mechanical characteristics of the phases become strongly anisotropic upon the transition from 3C-SiC0.875 to 3C-SiC0.75. It is established from the analysis of the phonon dispersion curves that the 3C-SiC0.875 and 3C-SiC0.75 phases, in contrast to the complete 3C-SiC phase, are dynamically unstable at T = 0 K. 相似文献
19.
The ground state degeneracy of an SU(N)
k
topological phase with n quasiparticle excitations is a relevant quantity for quantum computation, condensed matter physics, and knot theory. It is
an open question to find a closed formula for this degeneracy for any N >2. Here we present the problem in an explicit combinatorial way and analyze the case N = 3. While not finding a complete closed-form solution, we obtain generating functions and solve some special cases. 相似文献
20.
For a given crystal structure, say body-centred-cubic, the many-body Hamiltonian H in which nuclear and electron motions are to be treated from the outset on the same footing, has parameters, for the elements, which can be classified as (i) atomic mass M, (ii) atomic number Z, characterizing the external potential in which electrons move, and (iii) bcc lattice spacing, or equivalently one can utilize atomic volume,
. Since the thermodynamic quantities can be determined from H, we conclude that T
c
, the superconducting transition temperature, when it is non-zero, may be formally expressed as T
c
=
. One piece of evidence in support is that, in an atomic number vs. atomic volume graph, the superconducting elements lie in a well defined region. Two other relevant points are that (a) T
c
is related by BCS theory, though not simply, to the Debye temperature, which in turn is calculable from the elastic constants C
11, C
12, and C
44, the atomic weight and the atomic volume, and (b) T
c
for five bcc transition metals is linear in the Cauchy deviation C
* = (C
12 - C
44 )/(C
12 + C
44 ). Finally, via elastic constants, mass density and atomic volume, a correlation between C
* and the Debye temperature is established for the five bcc transition elements.Received: 13 May 2004, Published online: 23 July 2004PACS:
74.62.-c Transition temperature variations - 74.70.Ad Metals; alloys and binary compounds 相似文献