Gauge singlet scalar as inflaton and thermal relic dark matter

We show that, by adding a gauge singlet scalar S to the standard model which is nonminimally coupled to gravity, S can act both as the inflaton and as thermal relic dark matter. We obtain the allowed region of the (m_s, m_h) parameter space which gives a spectral index in agreement with observational bounds and also produces the observed dark matter density while not violating vacuum stability or nonperturbativity constraints. We show that, in contrast to the case of Higgs inflation, once quantum corrections are included the spectral index is significantly larger than the classical value (n = 0.966 for N = 60) for all allowed values of the Higgs mass m_h. The range of Higgs mass compatible with the constraints is 145 GeV < m_h < 170 GeV. The S mass lies in the range 45 GeV < ms < 1 TeV for the case of a real S scalar with large quartic self-coupling lambdas, with a smaller upper bound for smaller lambdas. A region of the parameter space is accessible to direct searches at the LHC via h-->SS, while future direct dark matter searches should be able to significantly constrain the model.Comment: 13 pages, 7 figures. Published versio

Thurstonian Scaling of Compositional Questionnaire Data

To prevent response biases, personality questionnaires may use comparative response formats. These include forced choice, where respondents choose among a number of items, and quantitative comparisons, where respondents indicate the extent to which items are preferred to each other. The present article extends Thurstonian modeling of binary choice data (Brown & Maydeu-Olivares, 2011a) to “proportion-of-total” (compositional) formats. Following Aitchison (1982), compositional item data are transformed into log-ratios, conceptualized as differences of latent item utilities. The mean and covariance structure of the log-ratios is modelled using Confirmatory Factor Analysis (CFA), where the item utilities are first-order factors, and personal attributes measured by a questionnaire are second-order factors. A simulation study with two sample sizes, N=300 and N=1000, shows that the method provides very good recovery of true parameters and near-nominal rejection rates. The approach is illustrated with empirical data from N=317 students, comparing model parameters obtained with compositional and Likert scale versions of a Big Five measure. The results show that the proposed model successfully captures the latent structures and person scores on the measured traits

Bias, redshift space distortions and primordial nongaussianity of nonlinear transformations: application to Lyman alpha forest

On large scales a nonlinear transformation of matter density field can be viewed as a biased tracer of the density field itself. A nonlinear transformation also modifies the redshift space distortions in the same limit, giving rise to a velocity bias. In models with primordial nongaussianity a nonlinear transformation generates a scale dependent bias on large scales. We derive analytic expressions for these for a general nonlinear transformation. These biases can be expressed entirely in terms of the one point distribution function (PDF) of the final field and the parameters of the transformation. Our analysis allows one to devise nonlinear transformations with nearly arbitrary bias properties, which can be used to increase the signal in the large scale clustering limit. We apply the results to the ionizing equilibrium model of Lyman-alpha forest, in which Lyman-alpha flux F is related to the density perturbation delta via a nonlinear transformation. Velocity bias can be expressed as an average over the Lyman-alpha flux PDF. At z=2.4 we predict the velocity bias of -0.1, compared to the observed value of -0.13 +/- 0.03. Bias and primordial nongaussianity bias depend on the parameters of the transformation. Measurements of bias can thus be used to constrain these parameters, and for reasonable values of the ionizing background intensity we can match the predictions to observations. Matching to the observed values we predict the ratio of primordial nongaussianity bias to bias to have the opposite sign and lower magnitude than the corresponding values for the highly biased galaxies, but this depends on the model parameters and can also vanish or change the sign.Comment: 18 pages, 1 figur

Guide to financial statement analysis : basis for management advice

https://egrove.olemiss.edu/aicpa_guides/1457/thumbnail.jp

Cavity Light Bullets: 3D Localized Structures in a Nonlinear Optical Resonator

We consider the paraxial model for a nonlinear resonator with a saturable absorber beyond the mean-field limit and develop a method to study the modulational instabilities leading to pattern formation in all three spatial dimensions. For achievable parametric domains we observe total radiation confinement and the formation of 3D localised bright structures. At difference from freely propagating light bullets, here the self-organization proceeds from the resonator feedback, combined with diffraction and nonlinearity. Such "cavity" light bullets can be independently excited and erased by appropriate pulses, and once created, they endlessly travel the cavity roundtrip. Also, the pulses can shift in the transverse direction, following external field gradients.Comment: 4 pages, 3 figures, simulations files available at http://www.ba.infn.it/~maggipin/PRLmovies.htm, submitted to Physical Review Letters on 24 March 200

Interplanetary flow systems associated with cosmic ray modulation in 1977 - 1980

The hydromagnetic flow configurations associated with cosmic ray modulation in 1977 to 1980 were determined using solar wind plasma and magnetic field data from Voyagers 1 and 2 and Helios 1. The modulation was related to two types of large scale systems of flows: one containing a number of transients such as shocks, post shock flows and magnetic clouds; the other consisting primarily of a series of quasi-stationary flows following interaction regions containing a stream interface and often bounded by a forward reverse shock pair. Each of the three major episodes of cosmic ray modulation was characterized by the passage of the system of transient flows. Plateaus in the cosmic ray intensity time profile were associated with the passage of systems of corotating streams

Investigation of multi-phase tubular permanent magnet linear generator for wave energy converters

In this article, an investigation into different magnetization topologies for a long stator tubular permanent magnet linear generator is performed through a comparison based on the cogging force disturbance, the power output, and the cost of the raw materials of the machines. The results obtained from finite element analysis simulation are compared with an existing linear generator described in [1]. To ensure accurate results, the generator developed in [1] is built with 3D CAD and simulated using the finite-element method, and the obtained results are verified with the source.The PRIMaRE project

Measuring the Cosmological Geometry from the Lyman Alpha Forest along Parallel Lines of Sight

We discuss the feasibility of measuring the cosmological metric using the redshift space correlation function of the Lya forest in multiple lines of sight, as a function of angular and velocity separation. The geometric parameter that is measured is f(z) = H(z) D(z)/c, where H(z) is the Hubble constant and D(z) the angular diameter distance at redshift z. The correlation function is computed in linear theory. We describe a method to measure it from observations with the Gaussianization procedure of Croft et al (1998) to map the Lya forest transmitted flux to an approximation of the linear density field. The effect of peculiar velocities on the shape of the recovered power spectrum is pointed out. We estimate the error in recovering the f(z) factor from observations due to the variance in the Lya absorbers. We show that ~ 20 pairs of quasars (separations < 3') are needed to distinguish a flat \Omega_0=1 universe from a universe with \Omega_0=0.2, \Omega_\Lambda=0.8. A second parameter that is obtained from the correlation function of the Lya forest is \beta \simeq \Omega(z)^{0.6}/b (affecting the magnitude of the peculiar velocities), where b is a linear theory bias of the Lya forest. The statistical error of f(z) is reduced if b can be determined independently from numerical simulations, reducing the number of quasar pairs needed for constraining cosmology to approximately six. On small scales, where the correlation function is higher, f(z) should be measurable with fewer quasars, but non-linear effects must then be taken into account. The anisotropy of the non-linear redshift space correlation function as a function of scale should also provide a precise quantitative test of the gravitational instability theory of the Lya forest.Comment: submitted to Ap

The Unique Frequency Spectrum of the Blazhko RRc Star LS Her

The Blazhko effect in RR Lyrae stars is still poorly understood theoretically. Stars with multiple Blazhko periods or in which the Blazhko effect itself varies are particularly challenging. This study investigates the Blazhko effect in the RRc star LS Her. Detailed VRI CCD photometry has been performed on 63 nights during six months. LS Her is confirmed to have a Blazhko period of 12.75+/-0.02 days. However, where normally the side frequencies of the Blazhko triplet are expected, an equidistant group of three frequencies is found on both sides of the main pulsation frequency. As a consequence the period and amplitude of the Blazhko effect itself vary in a cycle of 109+/-4 days. LS Her is a unique object turning out to be very important in the verification of the theories for the Blazhko effect.Comment: Accepted for publication in MNRA

Cosmological Effects of Radion Oscillations

We show that the redshift of pressureless matter density due to the expansion of the universe generically induces small oscillations in the stabilized radius of extra dimensions (the radion field). The frequency of these oscillations is proportional to the mass of the radion and can have interesting cosmological consequences. For very low radion masses $m_b$ ($m_b\sim10-100 H_0\simeq10^{-32} eV$) these low frequency oscillations lead to oscillations in the expansion rate of the universe. The occurrence of acceleration periods could naturally lead to a resolution of the coincidence problem, without need of dark energy. Even though this scenario for low radion mass is consistent with several observational tests it has difficulty to meet fifth force constraints. If viewed as an effective Brans-Dicke theory it predicts $\omega=-1+\frac{1}{D}$ ($D$ is the number of extra dimensions), while experiments on scales larger than $1mm$ imply $\omega>2500$. By deriving the generalized Newtonian potential corresponding to a massive toroidally compact radion we demonstrate that Newtonian gravity is modified only on scales smaller than $m_b^{-1}$. Thus, these constraints do not apply for $m_b>10^{-3} eV$ (high frequency oscillations) corresponding to scales less than the current experiments ($0.3mm$). Even though these high frequency oscillations can not resolve the coincidence problem they provide a natural mechanism for dark matter generation. This type of dark matter has many similarities with the axion.Comment: Accepted in Phys. Rev. D. Clarifying comments added in the text and some additional references include