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 $(5, 4)$ 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 ($p$) 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 $p_{c1}$ and $p_{c2}$. All the points in the intermediate phase $(p_{c1} < p < p_{c2})$ are critical and there exist infinitely many infinite clusters in the intermediate phase. In this phase the corresponding fractal exponent continuously increases with $p$ 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