271 research outputs found
Tricritical point of J1-J2 Ising model on hyperbolic lattice
A ferromagnetic-paramagnetic phase transition of the two-dimensional
frustrated Ising model on a hyperbolic lattice is investigated by use of the
corner transfer matrix renormalization group method. The model contains
ferromagnetic nearest-neighbor interaction J_1 and the competing
antiferromagnetic interaction J_2. A mean-field like second-order phase
transition is observed when the ratio \kappa = J_2 / J_1 is less than 0.203. In
the region 0.203 < \kappa < 1/4, the spontaneous magnetization is discontinuous
at the transition temperature. Such tricritical behavior suggests that the
phase transitions on hyperbolic lattices need not always be mean-field like.Comment: 7 pages, 13 figures, submitted to Phys. Rev.
CERN Axion Solar Telescope as a probe of large extra dimensions
We explore the potential of the CERN Axion Solar Telescope (CAST) for testing
the presence of large extra dimensions. The CAST experiment has originally been
proposed to search for solar axions with a sensitivity supposed to provide a
limit on the axion-photon coupling g_{a\gamma\gamma}<5x10^{-11} GeV^{-1} or
even lower. The expected bound on the coupling constant is by a factor of ten
more stringent than the current experimental results. This bound extends for
the first time beyond the limit dictated by astrophysical considerations. As a
tuning experiment planning to explore the axion mass region up to about 1 eV,
CAST would also be sensitive to the existence of Kaluza-Klein massive states.
Therefore, the detection of X-rays at least at two pressures may be the
signature of large extra dimensions. From this requirement we find that CAST
may test (two) large extra dimensions with a (common) compactification radius R
down to around 250 nm if m_{PQ}<1/(2R), and down to around 370 nm if
1/(2R)<m_{PQ}, where m_{PQ} is the Peccei-Quinn mass.Comment: Version to appear in Phys. Rev. D. Changes to the total rate formula
in Sec. III. Conclusions remain essentially unchanged; 5 pages, 2 figures,
revtex
Phase transition of clock models on hyperbolic lattice studied by corner transfer matrix renormalization group method
Two-dimensional ferromagnetic N-state clock models are studied on a
hyperbolic lattice represented by tessellation of pentagons. The lattice lies
on the hyperbolic plane with a constant negative scalar curvature. We observe
the spontaneous magnetization, the internal energy, and the specific heat at
the center of sufficiently large systems, where the fixed boundary conditions
are imposed, for the cases N>=3 up to N=30. The model with N=3, which is
equivalent to the 3-state Potts model on the hyperbolic lattice, exhibits the
first order phase transition. A mean-field like phase transition of the second
order is observed for the cases N>=4. When N>=5 we observe the Schottky type
specific heat below the transition temperature, where its peak hight at low
temperatures scales as N^{-2}. From these facts we conclude that the phase
transition of classical XY-model deep inside the hyperbolic lattices is not of
the Berezinskii-Kosterlitz-Thouless type.Comment: REVTeX style, 4 pages, 6 figures, submitted to Phys. Rev.
IoT as PSS Enabler: Exploring Opportunities for Conceptualization and Implementation
Nowadays, product-service systems (PSS) as an integrated system of physical products and services play a crucial role in sustainable economies. In addition to high competitive global economy, emergence of new digital paradigms is supporting the shift towards servitization. Although the great potential of such paradigms are recognized by both practice and research, their implications for PSS is not clear yet. Particularly, features of Internet-of-Things (IoT) such as total connectedness and ubiquity of smart sensors and actuators provide various new opportunities for PSS. This study explores such opportunities by conducting structured literature review and 13 interviews. We formulate the findings into two folds. First, we introduce four degrees of IoT involvement in PSS business models and we elaborate the opportunities that they create for different types of PSS. Second, we present the key technologies and approaches, which IoT provides with regard to PSS lifecycle management
Phase Transition of the Ising model on a Hyperbolic Lattice
The matrix product structure is considered on a regular lattice in the
hyperbolic plane. The phase transition of the Ising model is observed on the
hyperbolic lattice by means of the corner-transfer-matrix
renormalization group (CTMRG) method. Calculated correlation length is always
finite even at the transition temperature, where mean-field like behavior is
observed. The entanglement entropy is also always finite.Comment: 4 pages, 3 figure
Monte-Carlo simulation study of the two-stage percolation transition in enhanced binary trees
We perform Monte-Carlo simulations to study the Bernoulli () bond
percolation on the enhanced binary tree which belongs to the class of
nonamenable graphs with one end. Our numerical results show that the system has
two different percolation thresholds and . All the points in
the intermediate phase are critical and there exist
infinitely many infinite clusters in the intermediate phase. In this phase the
corresponding fractal exponent continuously increases with from zero to
unity.Comment: 4 pages, 6 figure
The large system asymptotics of persistent currents in mesoscopic quantum rings
We consider a one-dimensional mesoscopic quantum ring filled with spinless
electrons and threaded by a magnetic flux, which carries a persistent current
at zero temperature. The interplay of Coulomb interactions and a single on-site
impurity yields a non-trivial dependence of the persistent current on the size
of the ring. We determine numerically the asymptotic power law for systems up
to 32000 sites for various impurity strengths and compare with predictions from
Bethe Ansatz solutions combined with Bosonization. The numerical results are
obtained using an improved functional renormalization group (fRG) method. We
apply the density matrix renormalization group (DMRG) and exact diagonalization
methods to benchmark the fRG calculations. We use DMRG to study the persistent
current at low electron concentrations in order to extend the validity of our
results to quasi-continuous systems. We briefly comment on the quality of
calculated fRG ground state energies by comparison with exact DMRG data.Comment: REVTex, 12 pages, 12 figs, accepted in Phys. Rev.
Heat flow of the Earth and resonant capture of solar 57-Fe axions
In a very conservative approach, supposing that total heat flow of the Earth
is exclusively due to resonant capture inside the Earth of axions, emitted by
57-Fe nuclei on Sun, we obtain limit on mass of hadronic axion: m_a<1.8 keV.
Taking into account release of heat from decays of 40-K, 232-Th, 238-U inside
the Earth, this estimation could be improved to the value: m_a<1.6 keV. Both
the values are less restrictive than limits set in devoted experiments to
search for 57-Fe axions (m_a<216-745 eV), but are much better than limits
obtained in experiments with 83-Kr (m_a<5.5 keV) and 7-Li (m_a<13.9-32 keV).Comment: 8 page
Irreducible Representations of Diperiodic Groups
The irreducible representations of all of the 80 diperiodic groups, being the
symmetries of the systems translationally periodical in two directions, are
calculated. To this end, each of these groups is factorized as the product of a
generalized translational group and an axial point group. The results are
presented in the form of the tables, containing the matrices of the irreducible
representations of the generators of the groups. General properties and some
physical applications (degeneracy and topology of the energy bands, selection
rules, etc.) are discussed.Comment: 30 pages, 5 figures, 28 tables, 18 refs, LaTex2.0
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