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This study emphasizes the importance of conducting a comprehensive analysis considering the C n 2 atmospheric parameter for a reliable assessment of the seeing value. It highlights the use of the ECMWF ERA5 model to simulate pressure, temperature, and humidity profiles, enabling the evaluation of optical degradation. Accurate modeling and monitoring of temperature and humidity variables are emphasized for precise data in optical communication and astronomical observations. It also discusses the significance of optical turbulence models in understanding the impact of atmospheric turbulence on optical system performance. The validation of the selected C n 2 models is thoroughly analyzed. To evaluate the impact of the boundary layer on seeing conditions, three factors are considered. First, ERA5 data is used to simulate surface C n 2 values using the PAMELA model. Second, typical C n 2 values for specific dates in Redu are obtained. Finally, the thickness of the boundary layer, denoted as hbl, is calculated. This finding highlights the significant influence of the boundary layer on atmospheric seeing conditions and by incorporating Ibl into the models, a more accurate representation of the effects of the boundary layer on seeing quality is achieved. [ABSTRACT FROM AUTHOR]

Perhaps the cosmological constant really is huge at the Planck scale, but is “hidden” by Planck scale quantum fluctuations of spacetime. I briefly review this proposal and provide some evidence, coming from a simplified midisuperspace model, that an appropriate “foamy” structure can do the job of hiding a large cosmological constant, and can persist under time evolution. [ABSTRACT FROM AUTHOR]

The Chinese-Uighur calendar, the so-called 'Qitai calendar', was used for a century in Mongol Ilkhanid (1256-1335). Nasir al-Din al-Tusi (1202-1274), a Persian astronomer of the 13th century, first introduced the Qitai calendar in his Īlkhānī-zij, which he compiled with Chinese astronomers at the Maragha Observatory under the order of Hulagu Khan (1215-1265). After his zij, the calender was described in a number of Islamic zijes in Iran and Central Asia. This calendar was used among the Mongols, Uighurs, and Turks of the ruling class in the Mongol Ulus. The Qitai calendar is a luni-solar calendar that combines the astronomical parameters and calculation methods of Chinese and Uighur calendars. It is known that the calendar is based on the Revised Daming-li (重修大明曆) of Jin (金) dynasty adopted in 1215 and the Futian-li (符天曆) of the Tang (唐) period. This paper, therefore, examines the contents and origins of the Qitai calendar through exploring its relationship with the Revised Daming-li and the Futian-li. Particularly, by comparing astronomical constants and calculation methods used in the both calendars, we trace the exchanges and reciprocal influence of astronomical knowledge between the East and the West during the Mongol period. As a result, we unravel how calendrical knowledge based on the Revised Daming-li had an exerted important influence on the compilation of the Qitai calendar in Mongol Ilkhan and the Shoushi-li (授 時曆) in Mongol Yuan (元). Moreover, we can see how long the Qitai calendar and the Shoushi-li influenced neighboring countries in the East and the West of Central Asia, respectively. [ABSTRACT FROM AUTHOR]

We study a natural generalization of the results given in K. Aoyama and Y. Sugawara, Prog. Theor. Exp. Phys. 2020 , 103B01 (2020) to heterotic strings. Namely, starting from the generic Gepner models for Calabi –Yau three-folds, we construct non-SUSY heterotic string vacua with vanishing cosmological constant at the one-loop level. We especially focus on asymmetric orbifolding based on some discrete subgroup of the chiral |$U(1)$| action which acts on both the Gepner model and the |$SO(32)$| or |$E_8\times E_8$| sector. We present a classification of the relevant orbifold models leading to the string vacua with the properties mentioned above. In some cases, the desired vacua can be constructed in a manner quite similar to those given in the previous paper for the type II string, in which the orbifold groups contain two generators with discrete torsions. On the other hand, we also have simpler models that are just realized as asymmetric orbifolds of cyclic groups with only one generator. [ABSTRACT FROM AUTHOR]

A (2 m + 1) -dimensional Einstein–Gauss–Bonnet (EGB) model with the cosmological term Λ is considered. We find a class of solutions with exponential time dependence of two scale factors, governed by two Hubble-like parameters H > 0 and h , corresponding to two factor spaces of dimension m > 2 and obeying H ≠ ± h. We prove that the solutions, obeying h / H ≠ − m − 1 m − 2 , − m − 2 m − 1 , are stable (in a class of cosmological solutions with diagonal metrics) for h > − H and they are unstable for h < − H. A subclass of solutions with small enough variation of the effective gravitational constant G is considered. It is shown that all solutions from this subclass are stable. [ABSTRACT FROM AUTHOR]

The Cryogenic Underground Observatory for Rare Events (CUORE) is a bolometric experiment for neutrinoless double-beta decay in 130Te search, currently taking data at the underground facility of Laboratori Nazionali del Gran Sasso (LNGS). The CUORE cryostat successfully cooled down a mass of about 1 ton at ∼7mK, delivering a uniform and constant base temperature. This result marks a fundamental milestone in low-temperature detector techniques, opening the path for future ton-scale bolometric experiments searching for rare events. In this paper, we present the CUORE cryogenic infrastructure, briefly describing its critical subsystems. [ABSTRACT FROM AUTHOR]

Context. Umbral flashes (UF) and running penumbral waves (RPWs) in sunspot chromospheres leave a dramatic imprint in the intensity profile of the Ca II 8542 Å line. Recent studies have focussed on also explaining the observed polarization profiles, which show even more dramatic variations during the passage of these shock fronts. While most of these variations can be explained with an almost constant magnetic field as a function of time, several studies have reported changes in the inferred magnetic field strength during UF phases. These changes could be explained by opacity effects or by intrinsic changes in the magnetic field strength. Aims. In this study we investigate the origin of these periodic variations of the magnetic field strength by analyzing a time-series of high-temporal-cadence observations acquired in the Ca II 8542 Å line with the CRISP instrument at the Swedish 1-m Solar Telescope. In particular, we analyze how the inferred geometrical height scale changes between quiescent and UF phases, and whether those changes are enough to explain the observed changes in the magnetic field, B. Methods. We have performed non local thermodynamical equilibrium (non-LTE) data inversions with the NICOLE code of a time-series of very high spatio-temporal-resolution observations in the Ca II 8542 Å, Fe I 6301.5, and Fe I 6302.5 Å lines. We analyze in detail the variations of the different physical parameters of the model as a function of time. Results. Our results indicate that the Ca II 8542 Å line in sunspots is greatly sensitive to magnetic fields at log τ500 = −5 (hereafter log τ = −5) during UFs and quiescence. However this optical depth value does not correspond to the same geometrical height during the two phases. Our results indicate that during UFs and RPWs the log τ = −5 is located at a higher geometrical height than during quiescence. Additionally, the inferred magnetic field values are higher in UFs (up to ∼270 G) and in RPWs (∼100 G). Conclusions. Our results suggest that opacity changes caused by UFs and RPWs cannot explain the observed temporal variations in the magnetic field, as the line seems to form at higher geometrical heights where the field is expected to be lower. [ABSTRACT FROM AUTHOR]

Abstract We study low-scale gauge mediated supersymmetry breaking models with a very light gravitino of mass O (1) eV. The cosmological upper bound on the gravitino mass and the collider constraints on the sparticle masses give a significant impact on such models. We consider the weakly coupled gauge mediation models with (meta)stable SUSY breaking vacua and grand unification. We apply the latest results of the LHC to these models and obtain the current constraints. We find that perturbatively calculable classes of low-scale gauge mediation models can be largely excluded. [ABSTRACT FROM AUTHOR]

Abstract We use the non-Gaussian fixed points (NGFPs) appearing in the renormalization group flow of gravity and gravity–matter systems to construct models of NGFP-driven inflation via a renormalization group improvement scheme. The cosmological predictions of these models depend sensitively on the characteristic properties of the NGFPs, including their position and stability coefficients, which in turn are determined by the field content of the underlying matter sector. We demonstrate that the NGFPs appearing in gravity–matter systems where the matter content is close to the one of the standard model of particle physics are the ones compatible with cosmological data. Somewhat counterintuitively, the negative fixed point value of the dimensionless cosmological constant is essential for these findings. [ABSTRACT FROM AUTHOR]

We prove existence of large families of solutions of Einstein-complex scalar field equations with a negative cosmological constant, with a stationary or static metric and a time-periodic complex scalar field. [ABSTRACT FROM AUTHOR]

The thermal state of the post-reionization IGM is sensitive to the timing of reionization and the nature of the ionizing sources. We have modelled here the thermal state of the IGM in cosmological radiative transfer simulations of a realistic, extended, spatially inhomogeneous hydrogen reionization process, carefully calibrated with Ly α forest data. We compare these with cosmological simulations run using a spatially homogeneous ionizing background. The simulations with a realistic growth of ionized regions and a realistic spread in reionization redshifts show, as expected, significant spatial fluctuations in the temperature--density relation (TDR) of the post-reionization IGM. The most recently ionized regions are hottest and exhibit a flatter TDR. In simulations consistent with the average TDR inferred from Ly α forest data, these spatial fluctuations have a moderate but noticeable effect on the statistical properties of the Ly α opacity of the IGM at z ~ 4-6. This should be taken into account in accurate measurements of the thermal properties of the IGM and the free-streaming of dark matter from Ly α forest data in this redshift range. The spatial variations of the TDR predicted by our simulations are, however, smaller by about a factor of 2 than would be necessary to explain the observed large spatial opacity fluctuations on large (≥50 h-1 comoving Mpc) scales at z ... 5.5. [ABSTRACT FROM AUTHOR]

We present models for the dark and luminous mass structure of 12 strong lensing early-type galaxies. We combine pixel-based modelling of multiband Hubble Space Telescope imaging with Jeans modelling of kinematics obtained from Keck/ESI spectra to disentangle the dark and luminous contributions to the mass. Assuming a generalised NFW (gNFW) profile for the dark matter halo and a spatially constant stellar-mass-to-light ratio ϒ* for the baryonic mass, we infer distributions for ϒ* consistent with initial mass functions (IMFs) that are heavier than the Milky Way's (with a global mean mismatch parameter relative to a Chabrier IMF µac = 1.80 ± 0.14) and halo inner density slopes that span a large range but are generally cuspier than the dark-matter-only prediction (µγ = 2.01+0.19 -0.22).We investigate possible reasons for overestimating the halo slope, including the neglect of spatially varying stellar-mass-tolight ratios and/or stellar orbital anisotropy, and find that a quarter of the systems prefer radially declining stellar-mass-to-light ratio gradients, but that the overall effect on our inference on the halo slope is small. We suggest a coherent explanation of these results in the context of inside-out galaxy growth, and that the relative importance of different baryonic processes in shaping the dark halo may depend on halo environment. [ABSTRACT FROM AUTHOR]

We present a new method for constructing conformal Yano-Killing tensors in the five-dimensional Anti-de Sitter space-time. The found tensors are represented in two different coordinate systems. We also discuss, in terms of CYK tensors, global charges which are well-defined for asymptotically (five-dimensional) Anti-de Sitter space-time. Additionally, in Appendix A, we present our own derivation of conformal Killing one-forms in four-dimensional Anti-de Sitter space-time as an application of the Theorem 4. [ABSTRACT FROM AUTHOR]

The Reissner-Nordström black hole solution in a generic cosmological constant background in the context of Rastall gravity is obtained. It is shown that the cosmological constant arises naturally from the consistency of the non-vacuum field equations of the Rastall theory for a spherical symmetric space-time, rather than its ad hoc introduction in the usual Einstein and Einstein-Maxwell field equations. The usual Reissner-Nordström, Schwarzschild, and Schwarzschild - (anti-)de Sitter black hole solutions in the framework of this theory are also addressed as the special independent subclasses of the obtained general solution. [ABSTRACT FROM AUTHOR]

There are many factors that influence the change of the tidal constituent pattern. The factors can be classified as astronomical factors and nonastronomical factors. The astronomical factors involve the gravitational force attraction by the moon and sun. The distance of sun and moon influence the gravitational attractions that are produced by the moon and sun towards earth surface. Non-astronomical factors involved the movements of currents, waves, temperature and so on which is cause by the phenomenon such as El-Nino, La-Nina. This study was conducted to investigate the effect of these phenomena towards the pattern of tidal constituent during the phenomenon on several stations that have been chosen. The difference stations were chose due to the change in the position of celestial body. In addition, tidal data for several stations were processed using the UTM Tidal Analysis and Prediction Software (μ-TAPS). Based on the tidal data that has been processed, the graphs were plotted for the predicted data and observed data to compare the different pattern between the data. The tidal data that has been processed were used to analyse the pattern of tidal constituents based on the changing amplitude of M2, S2, K1, O1, Sa, Ssa, Mm, Mf and MSf. [ABSTRACT FROM AUTHOR]

Infrared (IR) spectra of solid cyclopropane (c -C 3 H 6) and ethylene oxide (c -C 2 H 4 O), two cyclic aliphatic compounds, have been recorded in their amorphous and crystalline states. The spectra have been combined with measurements of density and refractive index (λ = 670 nm) for each form of each solid to compute IR intensities (i.e., absorption coefficients and band strengths) and optical constants for use in laboratory experiments and astronomical observations. These are the first such measurements of absolute IR intensities and optical constants for each solid at temperatures relevant to the outer Solar System and the interstellar medium, with all results coming from a single laboratory. Two literature band strengths for ethylene oxide's strongest IR feature, one value a calculation and the other a gas-phase measurement, need to be increased by ∼25% to match the solid-phase value reported here. Suggestions are made for applications and future work related to the chemistry of icy bodies in the Solar System and beyond, including Pluto's surface, Titan's atmosphere, and the formation of cometary C 3. • Densities and refractive indices have been measured for amorphous and crystalline cyclopropane and ethylene oxide. • Infrared spectra have been recorded of each form of each compound. • Spectra, densities, and refractive indices have been used to calculate infrared band strengths. • Optical constants of each icy solid also have been calculated. • The results can lead to determinations of molecular abundances in extraterrestrial ices. [ABSTRACT FROM AUTHOR]

The Visible and near Infrared Hyperspectral Imager (VIHI) is the VIS-IR spectrometer with imaging capabilities aboard the ESA BepiColombo mission to Mercury. In this second paper, we report the instrument spectral characterization derived by the calibration campaign carried out before spacecraft integration. Complementary measurements concerning radiometric and linearity responses, as well as geometric performances, are described in Paper I [G. Filacchione et al., Rev. Sci. Instrum. 88, 094502 (2017)].We have verified the VIHI spectral range, spectral dispersion, spectral response function, and spectral uniformity along the whole slit. Instrumental defects and optical aberrations due to smiling and keystone effects have been evaluated, and they are lower than the design requirement (<1/3 pixel). The instrumental response is uniform along the whole slit, while spectral dispersion is well represented by a second order curve, rather than to be constant along the spectral dimension. [ABSTRACT FROM AUTHOR]

We show the kinematic equivalence between cosmological models driven by Dirac-Born-Infeld (DBI) fields with constant proper velocity of the brane and exponential potential , and interactive cosmological systems with modified holographic Ricci type fluids as dark energy (DE) in flat Friedmann-Robertson-Walker (FRW) cosmologies. [ABSTRACT FROM AUTHOR]

In the paper (Khugaev et al. in Phys Rev D94:064065. , 2016), we have shown that for perfect fluid spheres the pressure isotropy equation for Buchdahl-Vaidya-Tikekar metric ansatz continues to have the same Gauss form in higher dimensions, and hence higher dimensional solutions could be obtained by redefining the space geometry characterizing Vaidya-Tikekar parameter K. In this paper we extend this analysis to pure Lovelock gravity; i.e. a $$(2N+2)$$ -dimensional solution with a given $$K_{2N+2}$$ can be taken over to higher n-dimensional pure Lovelock solution with $$K_n=(K_{2N+2}-n+2N+2)/(n-2N-1)$$ where N is degree of Lovelock action. This ansatz includes the uniform density Schwarzshild and the Finch-Skea models, and it is interesting that the two define the two ends of compactness, the former being the densest and while the latter rarest. All other models with this ansatz lie in between these two limiting distributions. [ABSTRACT FROM AUTHOR]

We investigate static and spherically symmetric black hole solutions in the generalized Proca theory which corresponds to the generalization of the shift-symmetric scalar-tensor Horndeski theory to the vector-tensor theory. Any solution obtained in this paper possesses a constant spacetime norm of the vector field, $$X:=-\frac{1}{2}g^{\mu \nu }A_\mu A_\nu =X_0=\mathrm{constant}$$ . The solutions in the theory with generalized quartic coupling $$G_4(X)$$ generalize the stealth Schwarzschild and the Schwarzschild- (anti-) de Sitter solutions obtained in the theory with the nonminimal coupling to the Einstein tensor $$G^{\mu \nu } A_\mu A_\nu $$ . While in the vector-tensor theory with the coupling $$G^{\mu \nu }A_\mu A_\nu $$ the electric charge does not explicitly affect the spacetime geometry, in more general cases with nonzero $$G_{4XX}(X_0)\ne 0$$ this property does not hold in general. The solutions in the theory with generalized cubic coupling $$G_3(X)$$ are given by the Schwarzschild- (anti-) de Sitter spacetime, where the dependence on $$G_3(X)$$ does not appear in the metric function. [ABSTRACT FROM AUTHOR]

We model a radiating star undergoing dissipative gravitational collapse in the form of radial heat flux. The exterior of the collapsing star is described by the generalised Vaidya solution representing a mixture of null radiation and strings. Our model generalises previously known results of constant string density atmosphere to include inhomogeneities in the exterior spacetime. By utilising a causal heat transport equation of the Maxwell-Cattaneo form we show that relaxational effects are enhanced in the presence of inhomogeneities due to the string density. [ABSTRACT FROM AUTHOR]

In 5D relativity, the usual 4D cosmological constant is determined by the extra dimension. If the extra dimension is spacelike, one can get a positive cosmological constant Λ and a 4D de Sitter (dS) space. In this paper we present that, if the extra dimension is timelike oppositely, the negative Λ will be emerged and the induced 4D space will be an asymptotic Anti-de Sitter (AdS). Under the minimum assumption, we solve the Kaluza–Klein equation R A B = 0 in a canonical system and obtain the AdS solution in a general case. The result shows that an AdS space is induced naturally from a Kaluza–Klein manifold on a hypersurface (brane). The Lagrangian of test particle indicates the equation of motion can be geodesics if the 4D metric is independent of extra dimension. The causality is well respected because it is appropriately defined by a null higher dimensional interval. In this 5D relativity, the holographic principle can be used safely because the brane is asymptotic Euclidean AdS in the bulk. We also explore some possible holographic duality implications about the field/operator correspondence and the two-points correlation functions. [ABSTRACT FROM AUTHOR]

The scattering of spinning test particles by a Schwarzschild black hole is studied. The motion is described according to the Mathisson-Papapetrou-Dixon model for extended bodies in a given gravitational background field. The equatorial plane is taken as the orbital plane, the spin vector being orthogonal to it with constant magnitude. The equations of motion are solved analytically in closed form to first-order in spin and the solution is used to compute corrections to the standard geodesic scattering angle as well as capture cross section by the black hole. [ABSTRACT FROM AUTHOR]

In this paper, the photometric parameters (including the limited core and tidal radii, distances, luminosity and mass functions, total mass, and relaxation time) of the intermediate-aged open star cluster, NGC 2112, are estimated based on data collected from the PPMXL catalog. The kinematic properties of the cluster are also estimated. NGC 2112 lies nearby, at a distance of 898 ± 41 pc from the Sun, with an age of log(age) = 9.25 ± 0.05 assuming solar metallicity (Z = 0.019). The estimated relaxation time of the cluster is shorter than its estimated age, which indicates that the cluster may be dynamically relaxed. The position of the cluster convergent point or apex is computed using the AD diagram method and is found to have the equatorial coordinates 59.430, -19.398. Finally, the parameters of the cluster ellipsoidal velocity are also computed. [ABSTRACT FROM AUTHOR]

The spatial variations of the velocity field of local stars provide direct evidence of Galactic differential rotation. The local divergence, shear and vorticity of the velocity field - the traditional Oort constants - can be measured based purely on astrometric measurements and in particular depend linearly on proper motion and parallax. I use data for 304 267 mainsequence stars from the Gaia DR1 Tycho-Gaia Astrometric Solution to perform a local, precise measurement of the Oort constants at a typical heliocentric distance of 230 pc. The pattern of proper motions for these stars clearly displays the expected effects from differential rotation. I measure the Oort constants to be: A=15.3±0.4 kms-1 kpc-1, B=-11.9±0.4 kms-1 kpc-1, C = -3.2 ± 0.4 kms-1 kpc-1 and K = -3.3 ± 0.6 kms-1 kpc-1, with no colour trend over a wide range of stellar populations. These first confident measurements of C and K clearly demonstrate the importance of non-axisymmetry for the velocity field of local stars and they provide strong constraints on non-axisymmetric models of the Milky Way. [ABSTRACT FROM AUTHOR]

Aims: We aim to study the possibility of a hadron-quark phase transition in the interior of neutron stars, taking into account different schematic evolutionary stages at finite temperature. We also discuss the strange quark matter stability in the quark matter phase. Furthermore, we aim to analyze the astrophysical properties of hot and cold hybrid stars, considering the constraint on maximum mass given by the pulsars J1614-2230 and J0348+0432. Methods: We have developed a computational code to construct semi-analytical hybrid equations of state at fixed entropy per baryon and to obtain different families of hybrid stars. An analytical approximation of the field correlator method is developed for the quark matter equation of state. For the hadronic equation of state we use a table based on the relativistic mean field theory, without hyperons. The phase transition was obtained imposing the Maxwell conditions, by assuming a high surface tension at the interface hadron-quark. We solved the relativistic structure equations of hydrostatic equilibrium and mass conservation for hybrid star configurations. Results: For the different equations of state obtained, we calculated the stability window for the strange quark matter, lepton abundances, temperature profiles and contours profiles for the maximum mass star depending on the parameters of the field correlator method. We also computed the mass-radius and gravitational mass-baryonic mass relationships for different hybrid star families. Conclusions: We have analyzed different stages of hot hybrid stars as a first approximation of the cooling evolution of neutron stars with quark matter cores. We obtain cold hybrid stars with maximum masses ≥2 M⊙ for different combinations of the field correlator method parameters. In addition, our study based on the gravitational mass - baryonic mass plane shows a late phase transition between hadronic and quark matter during the proto-hybrid star evolution, in contrast with previous studies of proto-neutron stars. [ABSTRACT FROM AUTHOR]

Context: The onset of star formation is intimately linked with the presence of massive unstable filamentary structures. These filaments are therefore key for theoretical models that aim to reproduce the observed characteristics of the star formation process in the Galaxy. Aims. As part of the filament study carried out by the Herschel Galactic Cold Cores Key Programme, here we study and discuss the filament properties presented in GCC VII (Paper I) in context with theoretical models of filament formation and evolution. Methods. A conservatively selected sample of filaments located at a distance D< 500 pc was extracted from the GCC fields with the getfilaments algorithm. The physical structure of the filaments was quantified according to two main components: the central (Gaussian) region of the filament (core component), and the power-law-like region dominating the filament column density profile at larger radii (wing component). The properties and behaviour of these components relative to the total linear mass density of the filament and the column density of its environment were compared with the predictions from theoretical models describing the evolution of filaments under gravity-dominated conditions. Results. The feasibility of a transition from a subcritical to supercritical state by accretion at any given time is dependent on the combined effect of filament intrinsic properties and environmental conditions. Reasonably self-gravitating (high Mline,core) filaments in dense environments (AV≳ 3 mag) can become supercritical on timescales of t ~ 1 Myr by accreting mass at constant or decreasing width. The trend of increasing Mline,tot (Mline,core and Mline,wing) and ridge AV with background for the filament population also indicates that the precursors of star-forming filaments evolve coevally with their environment. The simultaneous increase of environment and filament AV explains the observed association between dense environments and high Mline,core values, and it argues against filaments remaining in constant single-pressure equilibrium states. The simultaneous growth of filament and background in locations with efficient mass assembly, predicted in numerical models of filaments in collapsing clouds, presents a suitable scenario for the fulfillment of the combined filament mass-environment criterium that is in quantitative agreement with Herschel observations. [ABSTRACT FROM AUTHOR]

In 2013 the Nobel Prize in Physics was awarded to Francois Englert and Peter Higgs for their work in 1964 along with the late Robert Brout on the mass generation mechanism (the Higgs mechanism) in local gauge theories. This mechanism requires the existence of a massive scalar particle, the Higgs boson, and in 2012 the Higgs boson was finally discovered at the Large Hadron Collider after being sought for almost half a century. In this article we review the work that led to the discovery of the Higgs boson and discuss its implications. We approach the topic from the perspective of a dynamically generated Higgs boson that is a fermion–antifermion bound state rather than an elementary field that appears in an input Lagrangian. In particular, we emphasize the connection with the Bardeen–Cooper–Schrieffer theory of superconductivity. We identify the double-well Higgs potential not as a fundamental potential but as a mean-field effective Lagrangian with a dynamical Higgs boson being generated through a residual interaction that accompanies the mean-field Lagrangian. We discuss what we believe to be the key challenge raised by the discovery of the Higgs boson, namely determining whether it is elementary or composite, and through study of a conformal invariant field theory model as realized with critical scaling and anomalous dimensions, suggest that the width of the Higgs boson might serve as a suitable diagnostic for discriminating between an elementary Higgs boson and a composite one. We discuss the implications of Higgs boson mass generation for the cosmological constant problem, as the cosmological constant receives contributions from the very mechanism that generates the Higgs boson mass in the first place. We show that the contribution to the cosmological constant due to a composite Higgs boson is more tractable and under control than the contribution due to an elementary Higgs boson, and is potentially completely under control if there is an underlying conformal symmetry not just in a critical scaling matter sector (which there would have to be if all mass scales are to be dynamical), but equally in the gravity sector to which the matter sector couples. [ABSTRACT FROM AUTHOR]

We consider the Bradlow equation for vortices which was recently found by Manton and find a two-parameter class of analytic solutions in closed form on nontrivial geometries with non-constant curvature. The general solution to our class of metrics is given by a hypergeometric function and the area of the vortex domain by the Gaussian hypergeometric function. [ABSTRACT FROM AUTHOR]

In the background of a homogeneous and isotropic space-time with zero spatial curvature, we consider interacting scenarios between two barotropic fluids, one is the pressureless dark matter and the other one is dark energy (DE), in which the equation of state (EoS) in DE is either constant or time-dependent. In particular, for constant EoS in DE, we show that the evolution equations for both fluids can be analytically solved. For all these scenarios, the model parameters have been constrained using the current astronomical observations from Type Ia supernovae, Hubble parameter measurements and baryon acoustic oscillation distance measurements. Our analysis shows that both for constant and variable EoS in DE, a very small but non-zero interaction in the dark sector is favoured while the EoS in DE can predict a slight phantom nature, i.e. the EoS in DE can cross the phantom divide line '-1'. On the other hand, although the models with variable EoS describe the observations better, the Akaike Information Criterion supports models with minimal number of parameters. However, it is found that all the models are very close to the ⋀ cold dark matter cosmology. [ABSTRACT FROM AUTHOR]

We present a framework which unifies a large class of noncommutative spacetimes that can be described in terms of a deformed Heisenberg algebra. The commutation relations between spacetime coordinates are up to linear order in the coordinates, with structure constants depending on the momenta plus terms depending only on the momenta. The possible implementations of the action of Lorentz transformations on these deformed phase spaces are considered, together with the consistency requirements they introduce. It is found that Lorentz transformations in general act nontrivially on tensor products of momenta. In particular the Lorentz group element which acts on the left and on the right of a composition of two momenta is different, and depends on the momenta involved in the process. We conclude with two representative examples, which illustrate the mentioned effect. [ABSTRACT FROM AUTHOR]

An analysis to determine solutions with constant orbit elements has been carried out through a vectorial formulation of the perturbation equations, under the long-term influence due to the attraction of a disturbing body moving over an inclined elliptical orbit. After having gained a frozen orbital plane by assuming an orbital pole parallel or perpendicular to the perturbing body pole, the feasibility to get a frozen condition also on eccentricity or argument of pericentre has been demonstrated and several solutions have been proposed. Moreover, when the orbital pole is perpendicular to the perturbing body pole, a prime integral of motion, linking orbit eccentricity and argument of pericentre, has been retrieved. This prime integral has permitted the identification of solutions characterised by slow variations of eccentricity. A study to obtain orbits at constant eccentricity or argument of pericentre has also been carried out, regardless of the orbital plane evolution. This has highlighted how, while the solutions with a frozen apsidal line have to be determined by means of numerical methods, not pursued in this paper, the ones characterised by a null variation of eccentricity can be retrieved analytically. Examples, for a probe orbiting Mercury, have also been presented. [ABSTRACT FROM AUTHOR]

String Theory is believed to have a landscape of 10 500 vacua with properties that resemble those of our Universe. The existence of these vacua can be combined with anthropic reasoning to explain some of the hardest problems in cosmology and high-energy physics: the cosmological constant problem, the hierarchy problem, and the un-natural almost-flatness of the inflationary potential. We will explain the construction of these vacua, focusing on the challenges of obtaining vacua with a positive cosmological constant. [ABSTRACT FROM AUTHOR]

The black hole information problem and the firewall problem can be addressed by assuming an extra local symmetry: conformal invariance. It must be an exact symmetry, spontaneously broken by the vacuum, in a way similar to the Brout-Englert-Higgs (BEH) mechanism. We note how this symmetry formally removes the horizon and the singularity inside black holes. For the Standard Model this symmetry is severely restrictive, demanding all coupling constants, masses and even the cosmological constant to be computable, in principle. Finally, this symmetry suggests that the Weyl action (the square of the Weyl curvature) should be added to the Einstein-Hilbert action. The ensuing indefinite metric states are briefly studied, and we conclude with some remarks concerning the interpretation of quantum mechanics. [ABSTRACT FROM AUTHOR]

We study a classical, noncommutative (NC), Friedmann-Robertson-Walker (FRW) cosmological model. The spatial sections may have positive, negative or zero constant curvatures. The matter content is a generic perfect fluid. The initial noncommutativity between some canonical variables is rewritten, such that, we end up with commutative variables and a NC parameter. Initially, we derive the scale factor dynamic equations for the general situation, without specifying the perfect fluid or the curvature of the spatial sections. Next, we consider two concrete situations: a radiation perfect fluid and dust. We study all possible scale factor behaviors, for both cases. We compare them with the corresponding commutative cases and one with the other. We obtain, some cases, where the NC model predicts a scale factor expansion which may describe the present expansion of our universe. Those cases are not present in the corresponding commutative models. Finally, we compare our model with another NC model, where the noncommutativity is between different canonical variables. We show that, in general, it leads to a scale factor behavior that is different from our model. [ABSTRACT FROM AUTHOR]

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It is shown that for every multidimensional metric in the multiply-warped product form with warp functions , , associated to the submanifolds , of dimensions , respectively, one can find the corresponding Einstein equations , with cosmological constant , which are reducible to the Einstein equations and on the submanifolds , , with cosmological constants and , respectively, where , and are functions of , and , . [ABSTRACT FROM AUTHOR]

Our aim is to study five-dimensional spherically symmetric anisotropic collapse with a positive cosmological constant (PCC). For this purpose, five-dimensional spherically symmetric and Schwarzschild-de Sitter metrics are chosen in the interior and exterior regions respectively. A set of junction conditions is derived for the smooth matching of interior and exterior spacetimes. The apparent horizon is calculated and its physical significance is studied. It comes out that the whole collapsing process is influenced by the cosmological constant. The collapsing process under the influence of cosmological constant slows down and black hole size also reduced. [ABSTRACT FROM AUTHOR]

We report the results of a polarimetric and photometric study of the cool white dwarf WD1748+508. Observations were performed during four consecutive nights on the telescopes of the Crimean Astrophysical Observatory. As a result, polarization was detected in the V band at the level of −0.36 ± 0.087% and the star was found to be photometrically variable with a period ranging from five hours to about two days. Throughout the entire observing set the variability amplitude was constant and equal to about 10 ± 1 mmag. Non-zero circular polarization directly indicates that the white dwarf has a global magnetic field with a strength of 10 MG or higher.We interpret the photometric variations found in this study in terms of rotationally modulated variability of magnetic properties of the star's atmosphere. [ABSTRACT FROM AUTHOR]