Thermodynamics of charged Brans–Dicke AdS black holes

It is well known that in four dimensions, black hole solution of the Brans–Dicke–Maxwell equations is just the Reissner–Nordstrom solution with a constant scalar field. However, in n4 dimensions, the solution is not yet the (n+1)-dimensional Reissner–Nordstrom solution and the scalar field is not a constant in general. In this Letter, by applying a conformal transformation to the dilaton gravity theory, we derive a class of black hole solutions in (n+1)-dimensional (n4) Brans–Dicke–Maxwell theory in the background of anti-de Sitter universe. We obtain the conserved and thermodynamic quantities through the use of the Euclidean action method. We find a Smarr-type formula and perform a stability analysis in the canonical ensemble. We find that the solution is thermally stable for small α, while for large α the system has an unstable phase, where α is a coupling constant between the scalar and matter field.     

Phase transition in the spanning-hyperforest model on complete hypergraphs

By using our novel Grassmann formulation we study the phase transition of the spanning-hyperforest model of the k-uniform complete hypergraph for any k2. The case k=2 reduces to the spanning-forest model on the complete graph. Different k are studied at once by using a microcanonical ensemble in which the number of hypertrees is fixed. The low-temperature phase is characterized by the appearance of a giant hyperforest. The phase transition occurs when the number of hyperforests is a fraction (k−1)/k of the total number of vertices. The behaviour at criticality is also studied by means of the coalescence of two saddle points. As the Grassmann formulation exhibits a global supersymmetry we show that the phase transition is second order and is associated to supersymmetry breaking and we explore the pure thermodynamical phase at low temperature by introducing an explicit breaking field.     

Double-quantum NMR spectroscopy of P species submitted to very large CSAs

We introduce an original pulse sequence, , which is a block super-cycled sequence employing as basic element a π pulse sandwiched by ‘window’ intervals. This homonuclear dipolar recoupling method allows the efficient excitation of double-quantum coherences between spin-1/2 nuclei submitted to very large chemical shift anisotropy. We demonstrate that this technique can be employed in double-quantum ↔ single-quantum ³¹P homonuclear correlation experiment at high magnetic field (B₀  14 T) and high MAS frequencies (ν_R  30 kHz). The performances of are compared to those of the double-quantum recoupling methods, such as BABA and bracketed fp-RFDR, which were already employed at fast MAS rates. The sequence displays a higher robustness to CSA and offset than the other existing techniques.     

Modeling of supersonic plasma flow in the scrape-off layer

The substantial drop of the plasma temperature along magnetic field lines with increasing plasma density is one of the main features in tokamak divertors. As a result the temperature gradient at the divertor plates becomes very steep and the boundary condition normally applied for the parallel Mach number M at the target, M_t = 1, cannot be satisfied. In this case the value of M_t based on the general form of the Bohm criterion, M_t  1, has to be determined from the continuity of plasma parameters.In the present paper a new approach to resolve the Mach number at the target for such a situation is proposed. This method avoids the singularity problem that arises by treating the particle balance and parallel motion equations in a differential form. Instead, the integral representation of the equations is formulated for an arbitrary form of particle and momentum sources. The approach can also take into account transport perpendicular to the magnetic field lines.The proposed method is demonstrated on the example of a one-dimensional stationary model for the scrape-off layer (SOL) plasma and includes the continuity-, parallel momentum- and heat transfer equations. The recycled neutrals are described in the diffusion approximation. In the case of low density the normal condition M_t = 1 is satisfied and the results are in agreement with the two-point model. At high enough plasma density solutions with the supersonic flow at the divertor plates, M_t > 1, are found. These states correspond to a partially detached plasma with a temperature of a few eV.     

Exceptional sensitivity to neutrino parameters with a two-baseline Beta-beam set-up

We examine the reach of a Beta-beam experiment with two detectors at carefully chosen baselines for exploring neutrino mass parameters. Locating the source at CERN, the two detectors and baselines are: (a) a 50 kton iron calorimeter (ICAL) at a baseline of around 7150 km which is roughly the magic baseline, e.g., ICAL@INO, and (b) a 50 kton Totally Active Scintillator Detector at a distance of 730 km, e.g., at Gran Sasso. We choose ⁸B and ⁸Li source ions with a boost factor γ of 650 for the magic baseline while for the closer detector we consider ¹⁸Ne and ⁶He ions with a range of Lorentz boosts. We find that the locations of the two detectors complement each other leading to an exceptional high sensitivity. With γ=650 for ⁸B/⁸Li and γ=575 for ¹⁸Ne/⁶He and total luminosity corresponding to 5×(1.1×10¹⁸) and 5×(2.9×10¹⁸) useful ion decays in neutrino and antineutrino modes respectively, we find that the two-detector set-up can probe maximal CP violation and establish the neutrino mass ordering if sin²2θ₁₃ is 1.4×10⁻⁴ and 2.7×10⁻⁴, respectively, or more. The sensitivity reach for sin²2θ₁₃ itself is 5.5×10⁻⁴. With a factor of 10 higher luminosity, the corresponding sin²2θ₁₃ reach of this set-up would be 1.8×10⁻⁵, 4.6×10⁻⁵ and 5.3×10⁻⁵ respectively for the above three performance indicators. CP violation can be discovered for 64% of the possible δ_CP values for sin²2θ₁₃10⁻³ (8×10⁻⁵), for the standard luminosity (10 times enhanced luminosity). Comparable physics performance can be achieved in a set-up where data from CERN to INO@ICAL is combined with that from CERN to the Boulby mine in United Kingdom, a baseline of 1050 km.     

Hetero-/homogeneous combustion of hydrogen/air mixtures over platinum at pressures up to 10 bar

The hetero-/homogeneous combustion of fuel-lean hydrogen/air premixtures over platinum was investigated experimentally and numerically in the pressure range 1 bar  p  10 bar. Experiments were carried out in an optically accessible channel-flow catalytic reactor and included planar laser induced fluorescence (LIF) of the OH radical for the assessment of homogeneous (gas-phase) ignition, and 1-D Raman measurements of major gas-phase species concentrations for the evaluation of the heterogeneous (catalytic) processes. Simulations were performed with a full-elliptic 2-D model that included detailed heterogeneous and homogeneous chemical reaction schemes. The predictions reproduced the measured catalytic hydrogen consumption, the onset of homogeneous ignition at pressures of up to 3 bar and the diminishing gas-phase combustion at p  4 bar. The suppression of gaseous combustion at elevated pressures bears the combined effects of the intrinsic homogeneous hydrogen kinetics and of the hetero/homogeneous chemistry coupling via the catalytically produced water over the gaseous induction zone. Transport effects, associated with the large diffusivity of hydrogen, have a smaller impact on the limiting pressure above which gaseous combustion is suppressed. It is shown that for practical reactor geometrical confinements, homogeneous combustion is still largely suppressed at p  4 bar even for inlet and wall temperatures as high as 723 and 1250 K, respectively. The lack of appreciable gaseous combustion at elevated pressures is of concern for the reactor thermal management since homogeneous combustion moderates the superadiabatic surface temperatures attained during the heterogeneous combustion of hydrogen.     

Anomalous discrete chiral symmetry in the Gross–Neveu model and loop gas simulations

We investigate the discrete chiral transformation of a Majorana fermion on a torus. Depending on the boundary conditions the integration measure can change sign. Taking this anomalous behavior into account we define a chiral order parameter as a ratio of partition functions with differing boundary conditions. Then the lattice realization of the Gross–Neveu model with Wilson fermions is simulated using the recent ‘worm’ technique on the loop gas or all-order hopping representation of the fermions. An algorithm is formulated that includes the Gross–Neveu interaction for N fermion species. The critical line m_c(g) is constructed for a range of couplings at N=6 and for N=2, the Thirring model, as examples.     

Calculation of axial optical forces exerted on medium-sized particles by optical trap

Optical trapping has become an efficient technique of trapping and manipulating micrometer and sub-micrometer dimension particles. Particles in the range between the applicable regime of ray optics theory (ROT) and the Rayleigh regime (so-called medium-sized particles) are focused on. By using ROT and the generalized Lorenz–Mie theory (GLMT), axial optical forces and their dependences on particle sizes and beam waists are presented. Furthermore, by comparing the numerical results of these two theories, the applicability of the GLMT to particles of arbitrary size and the limit of ROT in the region of small particles are analyzed. A new criterion of the applicable region of ROT is obtained, i.e. the relative particle size β=2πa/λ20, where a is the particle radius and λ is the wavelength of light. The theoretical results will be of great help to the design and optimization of the most efficient optical trap.     

Critical Casimir amplitudes for n-component models with -symmetry breaking quadratic boundary terms

Euclidean n-component ⁴ theories whose Hamiltonians are O(n) symmetric except for quadratic symmetry breaking boundary terms are studied in the film geometry . The boundary terms imply the Robin boundary conditions at the boundary planes at z=0 and at z=L. Particular attention is paid to the cases in which m_j of the n variables associated with plane take the special value corresponding to critical enhancement while the remaining ones are larger and hence subcritically enhanced. Under these conditions, the semi-infinite system with boundary plane has a multicritical surface–bulk point, called m_j-special, at which an O(m_j) symmetric critical surface phase coexists with the O(n) symmetric bulk phase, provided d is sufficiently large. The L-dependent part of the reduced free energy per cross-section area behaves asymptotically as Δ_C/L^d−1 as L→∞ at the bulk critical point. The Casimir amplitudes Δ_C are determined for small =4−d in the general case where m_c,c components _α are critically enhanced at both boundary planes, m_c,D+m_D,c components are enhanced at one plane but satisfy asymptotic Dirichlet boundary conditions at the respective other, and the remaining m_D,D components satisfy asymptotic Dirichlet boundary conditions at both . Whenever m_c,c>0, the corresponding small- expansions involve, besides integer powers of , also fractional powers ^k/2 with k3 modulo powers of logarithms. Results to order ^3/2 are given for general values of m_c,c, m_c,D+m_D,c, and m_D,D. These are used to estimate the Casimir amplitudes Δ_C of the three-dimensional Heisenberg systems with surface spin anisotropies for the cases with (m_c,c,m_c,D+m_D,c)=(1,0), (0,1), and (1,1).     

Wave properties of an annular periodic multilayer structure containing the single-negative materials

The optical properties of an annular periodic multilayer structure containing two kinds of single-negative materials are theoretically investigated based on the transfer matrix method of the cylindrical waves. At the azimuthal mode number m1 and near the magnetic plasma frequency and the electronic plasma frequency for the TE wave and TM wave, respectively, we find that there is an additional high-reflectance band and some reflection dips exist when the plasma frequency is located in the photonic band gap. These two special features arising from the higher order azimuthal mode of the cylindrical waves are not seen in the planar one-dimensional Bragg reflector consisting of the single-negative materials. Such filtering responses provide a feasible way of designing a narrowband resonator without physically introducing any defect layer in the structure.     

Interrelation between electronic structure and interatomic distances for compounds

The heat capacity was studied for LaMn₂Si₂, La_0.75Y_0.25Mn₂Si₂, La_0.7Y_0.3Mn₂Si₂, YMn₂Si₂ and LaFe₂Si₂ isostructural intermetallic compounds in the temperature range 1.8–360 K. The electronic, magnetic and lattice contributions to the heat capacity of the compounds were determined and analyzed. The interrelation was found between values of the electronic contribution to the heat capacity (density of states at the Fermi level) and crystal lattice parameters of R(Mn,Fe,Ni)₂Si₂ compounds. The electronic contribution and the density of states at Fermi level increase with increasing lattice parameters of the compounds. The change of interlayer Mn–Mn exchange interactions with change of Y concentration in La_1-xY_xMn₂Si₂ compounds is not accompanied by considerable changes in the electronic contribution to the heat capacity and density of states at the Fermi level. The performed analysis of the magnetic contribution shows that no essential differences exist between the behavior of the heat capacity of the compounds with d_Mn–Mnd_c and with d_Mn–Mn<d_c upon various types of the magnetic phase transitions.     

Proof of chiral symmetry breaking in lattice gauge theory

Using the method of infrared bounds and partial-integration formulas, we prove that there is a chiral phase transition in four-dimensional strongly coupled lattice gauge theory with gauge group U(N) and staggered fermions for all N5.     

Baxterization of ther-matrix for the adjoint representation of U q [D(2, 1;α)]

The Baxterization procedure is applied to the Braid group representation arising from the adjoint representation of the quantum supergroup U _q [D(2, 1;)]. This yields a two-parameter family of solutions to the (parameter dependent) Yang-Baxter equation of interest in supersymmetric lattice models.     

Development of surface-textured hydrogenated ZnO:Al thin-films for μc-Si solar cells

This study addresses the optimization of rf magnetron-sputtered hydrogenated ZnO:Al (HAZO) films as front contacts in microcrystalline silicon solar cells. The front contact of a solar cell has to be highly conductive and highly transparent to visible and infrared radiation. Furthermore, it has to scatter the incident light efficiently in order for the light to be effectively trapped in the underlying silicon layers. In this research, HAZO films were rf-magnetron-sputtered on glass substrates from a ceramic (98 wt% ZnO, 2 wt% Al₂O₃) target. Various compositions of AZO films on glass substrates were prepared by changing the H₂/(Ar + H₂) ratio of the sputtering gas. The resulting smooth films exhibited high transparencies (T  85% for visible light including all reflection losses) and excellent electrical properties (ρ = 2.7 × 10⁻⁴ Ω · cm). Depending on their structural properties, these films developed different surface textures upon post-deposition etching using diluted hydrochloric acid. The light-scattering properties of these films could be controlled simply by varying the etching time. Moreover, the electrical properties of the films were not affected by the etching process. Therefore, within certain limits, it is possible to optimize the electro-optical and light-scattering properties separately. The microcrystalline silicon (μc-Si:H)-based p–i–n solar cells prepared using these new texture-etched AZO:H substrates showed high quantum efficiencies in the long wavelength range, thereby demonstrating effective light trapping. Using the optimum AZO:H thin-film textured surface, we achieved a p–i–n μc-Si solar cell efficiency of 7.78%.     

Degradation behavior and products of malathion and chlorpyrifos spiked in apple juice by ultrasonic treatment

Apple juice (13 °Brix) spiked with malathion and chlorpyrifos (2–3 mg l⁻¹ of each compound) was treated under different ultrasonic irradiations. Results showed that ultrasonic treatment was effective for the degradation of malathion and chlorpyrifos in apple juice, and the output power and treatment time significantly influenced the degradation of both pesticides (p < 0.05). The maximum degradations were achieved for malathion (41.7%) and chlorpyrifos (82.0%) after the ultrasonic treatment at 500 W for 120 min. The degradation kinetics of both pesticides were fitted to the first-order kinetics model well (R²  0.90). The kinetics parameters indicated that chlorpyrifos was much more labile to ultrasonic treatment than malathion. Furthermore, malaoxon and chlorpyrifos oxon were identified as the degradation products of malathion and chlorpyrifos by gas chromatography–mass spectrometry (GC–MS), respectively. The oxidation pathway through the hydroxyl radical attack on the PS bond of pesticide molecules was proposed.     

Topology of quantum gauge fields and duality (I): Yang-Mills-Higgs system in 2 + 1 dimensions

The basic role of the representation of the gauge group in characterizing the topological excitations of the vacuum is pointed out. For SU(N) gauge fields on a lattice, the topological excitations are monopoles in the adjoint representation of the dual group ¹SU(N). This leads to a dual representation of the Yang-Mills-Higgs system in 2 + 1 dimensions. For SU(3) the deal theory in a scalar theory with discrete Weyl symmetry S₃. In the presence of adjoint Higgs fields the Weyl symmetry is broken in the Higgs phase but restored by pseudo-particles in the confinement phase.     

Spectrum of orientifold QCD in the strong coupling and hopping expansion approximation

We use the strong coupling and hopping parameter expansions to calculate the pion and rho meson masses for lattice Yang–Mills gauge theories with fermions in irreducible two-index representations, namely the adjoint, symmetric and antisymmetric. The results are found to be consistent with orientifold planar equivalence, and leading order 1/Nc$1/N_c$ corrections are calculated in the lattice phase. An estimate of the critical bare mass, for which the pion is massless, is obtained as a function of the bare coupling. A comparison to data from the two-flavour SU(2)$\mathit{SU}(2)$ theory with adjoint fermions gives evidence for a bulk phase transition at βc∼2${\beta }_c\sim 2$, separating a pure lattice phase from a phase smoothly connected to the continuum.     

Conformal invariance in incommensurate phases

We study finite-size corrections to the free energy of free-fermion models on a torus with periodic, twisted, and fixed boundary conditions. Inside the critical (striped-incommensurate) phase, the free energy densityf(N, M) on anN×M square lattice with periodic (or twisted) boundary conditions scales asf(N, M)=f _–A(s)/(NM)+.... We derive exactly the finite-size-scaling (FSS) amplitudesA(s) as a function of the aspect ratios=M/N. These amplitudes are universal because they do not depend on details of the free-fermion Hamiltonian. We establish an equivalence between the FSS amplitudes of the free-fermion model and the Coulomb gas system with electric and magnetic defect lines. The twist angle generates magnetic defect lines, while electric defect lines are generated by competition between domain wall separation and system size. The FSS behavior of the free-fermion model is consistent with predictions of the theory of conformal invariance with the conformal chargec=l. For instance, the FSS amplitude on an infinite cylinder with fixed boundary conditions is found to be one-quarter of that with periodic boundary conditions. Finally, we conjecture the exact form of the FSS amplitudes for an interacting-fermion model on a torus. Numerical calculations employing the Bethe Ansatz confirm our conjecture in the infinite-cylinder limit.     

Dark matter from the SU(4) model

The left-right symmetric Pati-Salam model of the unification of quarks and leptons is based on the SU(4) and SU(2)×SU(2) symmetry groups. These groups are naturally extended to include the classification of families of quarks and leptons. We assume that the family group (the group which unites the families) is also the SU(4) group. The properties of the fourth generation of fermions are the same as those of the ordinary-matter fermions in the first three generations except for the family charge of the SU(4)_F group: F=(1/3, 1/3, 1/3, ?1), where F=1/3 for fermions of ordinary matter and F=?1 for the fourth-generation fermions. The difference in F does not allow mixing between ordinary and fourth-generation fermions. Because of the conservation of the Fcharge, the creation of baryons and leptons in the process of electroweak baryogenesis must be accompanied by the creation of fermions of the fourth generation. As a result, the excess n _B of baryons over antibaryons leads to the excess n_4ν=N?N? of neutrinos over antineutrinos in the fourth generation with n_4ν=n _B . This massive neutrino may form nonbaryonic dark matter. In principle, the mass density of the fourth neutrino n_4νm _N in the Universe can make the main contribution to dark matter, since the lower bound on the neutrino mass m _N from the data on decay of the Z bosons is m _N <m _Z /2. The straightforward prediction of this model leads to the amount of cold dark matter relative to baryons, which is an order of magnitude higher than allowed by observations. This inconsistency may be avoided by nonconservation of the F charge.