119259613
Cosmological constant is probably adjustable in brane worlds
In the brane world scenario, possessing the self-tuning property of the cosmological constant, we study the probability amplitude for an initial state of the Universe to transform to final states with some curvatures. In the Kim, Kyae, and Lee model, there exists a finite range of parameters such that the transition amplitude to a near flat universe is exponentially dominated by the smallness of curvature, $\ensuremath{\gtrsim}{e}^{\mathrm{positive}\text{ }\mathrm{number}/{\overline{\ensuremath{\Lambda}}}^{2}}$, i.e., it is dominated by an almost flat universe of $|\overline{\ensuremath{\Lambda}}|lϵ$.
18138135
Neutrino masses from discrete gauge symmetries
Abstract We investigate a model with an extra Z 2 gauge symmetry in the Standard Model. The symmetry gives a structure to the mass matrix for the neutrinos. With two extra Higgs singlets and two extra singlet right-handed neutrinos we can build a model that fits the requirements of the MSW solution of the Solar neutrino problem. With a third singlet right-handed neutrino it is also possible to have a 10 eV neutrino.
15739165
SO(10)-like Superstring Standard Model with R-parity from the Heterotic String
We construct a supersymmetric standard model in the context of the Z_{12-I} orbifold compactification of the E_8 x E_8' heterotic string theory. The gauge group is SU(3)_c x SU(2)_L x U(1)_Y x U(1)^4 x [SO(10) x U(1)^3]' with sin^2\theta_W = 3/8. We obtain three families of SO(10) spinor-like chiral matter states, and Higgs doublets. All other extra states are exactly vector-like under the standard model gauge symmetry. There are numerous standard model singlets, many of which get VEVs such that only the standard model gauge symmetry survives and desired Yukawa couplings can be generated at lower energies. In particular, all vector-like exotic states achieve superheavy masses and the R-parity can be preserved.
119316975
GMSB at a stable vacuum and MSSM without exotics from heterotic string
Abstract We show that it is possible to introduce the confining hidden sector gauge group SU ( 5 ) ′ with the chiral matter 10 0 ′ plus 5 ¯ 0 ′ , which are neutral under the standard model gauge group, toward a gauge mediated supersymmetry breaking (GMSB) in a Z 12 − I orbifold compactification of E 8 × E 8 ′ heterotic string. Three families of MSSM result without exotics. We also find a desirable matter parity P (or R-parity) assignment. We note that this model contains the spectrum of the Lee–Weinberg model which has a nice solution of the μ problem.
119883211
Conflicts between B-violating phenomena in supergravity models
Abstract We show that there is an incompatibility between matter stability and cosmological baryon production in standard N = 1 supergravity models. This discrepancy emerges from the bound on the reheating temperature T rh ⩽ 10 10 GeV which comes from the restriction on the gravitino decay after inflation. Some weird possibilities to bypass the controversy are also analyzed.
14574575
Effective Gauss-Bonnet interaction in Randall-Sundrum compactification
The effective gravitational interaction below the Planck scale in the Randall-Sundrum world is shown to be the Gauss-Bonnet term. In this theory we find that there exists another static solution with a positive bulk cosmological constant. Also, there exist solutions for a positive visible sector cosmological constant, which is needed for a later Friedmann-Robertson-Walker universe.
118696062
Anomalous parity asymmetry of WMAP 7-year power spectrum data at low multipoles: Is it cosmological or systematics?
It is natural to assume a parity-neutral Universe and accordingly no particular parity preference in the cosmic microwave background sky. However, our investigation based on the WMAP 7-year power spectrum shows there exists a large-scale odd-parity preference with high statistical significance. We also find that the odd-parity preference in WMAP7 data is slightly higher than earlier releases. We have investigated possible origins, and ruled out various noncosmological origins. We also find that the primordial origin requires |Re[{Phi}(k)]|<<|Im[{Phi}(k)]| for k < or approx. 22/{eta}{sub 0}, where {eta}{sub 0} is the present conformal time. In other words, it requires translational invariance in the primordial Universe to be violated on scales larger than 4 Gpc. The Planck surveyor, which possesses wide frequency coverage and systematics distinct from the WMAP, may allow us to resolve the mystery of the anomalous odd-parity preference. Furthermore, polarization maps of large-sky coverage will reduce degeneracy in cosmological origins.
119245195
CMB map derived from the WMAP data through harmonic internal linear combination
We are presenting an internal linear combination CMB map, in which the foreground is reduced through harmonic variance minimization. We have derived our method by converting a general form of pixel-space approach into spherical harmonic space, maintaining full correspondence. By working in spherical harmonic space, spatial variability of linear weights is incorporated in a self-contained manner and our linear weights are continuous functions of position over the entire sky. The full correspondence to pixel-space approach enables straightforward physical interpretation on our approach. In variance minimization of a linear combination map, the existence of a cross term between residual foregrounds and CMB makes the linear combination of minimum variance differ from that of minimum foreground. We have developed an iterative foreground reduction method, where perturbative correction is made for the cross term. Our CMB map derived from the WMAP data is in better agreement with the WMAP best-fit {lambda}CDM model than the WMAP team's internal linear combination map. We find that our method's capacity to clean foreground is limited by the availability of enough spherical harmonic coefficients of good signal-to-noise ratio.
118530966
How accurately can we measure the hydrogen 2S->1S transition rate from the cosmological data?
Recent progress in observational cosmology, and especially the forthcoming PLANCK mission data, open new directions in so-called precision cosmology. In this paper we illustrate this statement considering the accuracy of cosmological determination of the two-quanta decay rate of 2s hydrogen atom state. We show that the PLANCK data will allow us to measure this decay rate significantly better than in the laboratory experiments.
119074604
Removing the ISW-lensing bias from the local-form primordial non-Gaussianity estimation
The Integrated Sachs-Wolfe (ISW) effect produces a secondary temperature aniso\-tropy of the cosmic microwave background (CMB), as CMB photons travel through time-varying potentials along the line-of-sight. The main contribution comes from redshifts z2, where dark energy leads to a decay of potentials. As the same photons are gravitationally lensed by these decaying potentials, there exists a high degree of correlation between the ISW effect and CMB lensing, leading to a non-zero three-point correlation (bispectrum) of the observed temperature anisotropy. This ISW-lensing bispectrum, whose shape resembles that of the so-called ``local-form'' primordial bispectrum parametrized by fNL, is known to be the largest contamination of fNL. In order to avoid a spurious detection of primordial non-Gaussianity, we need to remove the ISW-lensing bias. In this work, we investigate three debiasing methods: (I) subtraction of an expected, ensemble average of the ISW-lensing bispectrum; (II) subtraction of a measured ISW-lensing bispectrum; and (III) direct subtraction of an estimated ISW signal from an observed temperature map. One may use an estimation of the ISW map from external non-CMB data or that from the CMB data themselves. As the methods II and III are based on fewer assumptions about the nature of dark energy, they are preferred over the method I. While the methods I and II yield unbiased estimates of fNL with comparable error bars, the method III yields a biased result when the underlying primordial fNL is non-zero and the ISW map is estimated from a lensing potential reconstructed from the observed temperature map. One of the sources of the bias is a lensing reconstruction noise bias which is independent of fNL and can be calculated precisely, but other fNL-dependent terms are difficult to compute reliably. We thus conclude that the method II is the best, model-independent way to remove the ISW-lensing bias of fNL, enabling us to test the physics of inflation with smaller systematic errors.
122236431
A telescope for observation from space of extreme lightnings in the upper atmosphere
A new type of telescope with a wide field-of-view and functions of fast zoom-in has been introduced. Two kinds of MEMS (Micro-Electro-Mechanical Systems) micromirrors, digital and analog, are used for reflectors of the telescope, placed at different focal lengths. We apply this technology to the observation from space of TLE (Transient Luminous Events), extremely large transient sparks occurring at the upper atmosphere. TLE are one type of important backgrounds to be understood for future space observation of UHECR (Ultra-High Energy Cosmic Rays). The launch of the payload carried by a Russian microsatellite is foreseen in the middle of 2008.