118394011
Runnings in the Curvaton
We investigate the scale-dependence, or the runnings, of linear and second order density perturbations generated in various curvaton scenarios. We argue that the second order perturbations, i.e. non-Gaussianity, can strongly depend on the scale, even when the linear perturbations are nearly scale-invariant. We present analytic formulae for the runnings from curvatons with general energy potentials, and clarify the conditions under which fNL becomes strongly scale-dependent. From the point of view of the fNL running, curvaton potentials can be classified into roughly two categories by whether the potential flattens or steepens compared to a quadratic one. As such examples, we study pseudo-Nambu-Goldstone curvatons, and self-interacting curvatons, respectively. The dynamics of non-quadratic curvatons and the behaviors of the resulting density perturbations are clarified by analytical methods. Then we also study models where multiple source can be responsible for density perturbations such as the multi-curvaton, and mixed curvaton and inflaton models where the running of fNL can also be large due to their multi-source nature. We make quantitative analysis for each curvaton scenario and discuss in what cases the scale-dependence, in particular, of fNL can be large enough to be probed with future CMB experiments.
14635411
Bigger Rip with no dark energy
Abstract By studying a modified Friedmann equation which arises in an extension of general relativity which accommodates a time-dependent fundamental length L ( t ), we consider cosmological models where the scale factor diverges with an essential singularity at a finite future time. Such models have no dark energy in the conventional sense of energy possessing a simple pressure–energy relationship. Data on supernovae restrict the time from the present until the Rip to be longer than the current age of the Universe.
11074877
Constraining SuperWIMPy and Warm Subhalos with Future Submillilensing
Abstract We propose to observe QSO-galaxy strong lens systems to give a new constraint on the damping scale of the initial fluctuations. We find that the future observation of submilliarc scale astrometric shifts of the multiple lensed images of QSOs would find ∼ 10 ( 3 – 9 ) M ⊙ subhalos inside the macrolens halo. The superweakly interacting massive particles (superWIMPs) produced from a WIMP decay and the warm dark matter (WDM) particles that predict a comoving damping scale larger than ∼ 2 kpc can be constrained if ∼ 10 3 M ⊙ subhalos are detected.
19015148
Correlated Isocurvature Fluctuation of Quintessence and Curvaton Scenario
We consider cosmic microwave background (CMB) anisotropy in models with quintessence taking into account of isocurvature fluctuation in the quintessence. It is shown that, if the primordial fluctuation of the quintessence has a correlation with the adiabatic density fluctuations, CMB angular power spectrum $C_l$ at low multipoles can be suppressed. Possible scenario of generating correlated mixture of the quintessence and adiabatic fluctuations is also discussed.
8518266
On the determination of neutrino masses and dark energy evolution from the cross-correlation of CMB and LSS
We discuss the possibilities of the simultaneous determination of the neutrino masses and the evolution of dark energy from future cosmological observations such as cosmic microwave background (CMB), large scale structure (LSS) and the cross-correlation between them. Recently it has been discussed that there is a degeneracy between the neutrino masses and the equation of state for dark energy. It is also known that there are some degeneracies among the parameters describing the dark energy evolution. We discuss the implications of these for the cross-correlation of CMB with LSS in some detail. Then we consider to what extent we can determine the neutrino masses and the dark energy evolution using the expected data from CMB, LSS and their cross-correlation.
119229900
Neutrino mass from cosmology: impact of high-accuracy measurement of the Hubble constant
Non-zero neutrino mass would affect the evolution of the Universe in observable ways, and a strong constraint on the mass can be achieved using combinations of cosmological data sets. We focus on the power spectrum of cosmic microwave background (CMB) anisotropies, the Hubble constant H0, and the length scale for baryon acoustic oscillations (BAO) to investigate the constraint on the neutrino mass, mν. We analyze data from multiple existing CMB studies (WMAP5, ACBAR, CBI, BOOMERANG, and QUAD), recent measurement of H0 (SHOES), with about two times lower uncertainty (5 %) than previous estimates, and recent treatments of BAO from the Sloan Digital Sky Survey (SDSS). We obtained an upper limit of mν < 0.2eV (95 % C.L.), for a flat ΛCDM model. This is a 40 % reduction in the limit derived from previous H0 estimates and one-third lower than can be achieved with extant CMB and BAO data. We also analyze the impact of smaller uncertainty on measurements of H0 as may be anticipated in the near term, in combination with CMB data from the Planck mission, and BAO data from the SDSS/BOSS program. We demonstrate the possibility of a 5σ detection for a fiducial neutrino mass of 0.1 eV or a 95 % upper limit of 0.04 eV for a fiducial of mν = 0 eV. These constraints are about 50 % better than those achieved without external constraint. We further investigate the impact on modeling where the dark-energy equation of state is constant but not necessarily -1, or where a non-flat universe is allowed. In these cases, the next-generation accuracies of Planck, BOSS, and 1 % measurement of H0 would all be required to obtain the limit mν < 0.05−0.06 eV (95 % C.L.) for the fiducial of mν = 0 eV. The independence of systematics argues for pursuit of both BAO and H0 measurements.
11103294
Level truncation analysis of exact solutions in open string field theory
We evaluate vacuum energy density of Schnabl's solution using the level truncation calculation and the total action including interaction terms. The level truncated solution provides vacuum energy density expected both for tachyon vacuum and trivial pure gauge. We discuss the role of the phantom term to reproduce correct vacuum energy.
17896390
PRODUCTION OF NEUTRON-RICH LAMBDA HYPERNUCLEI AT J-PARC
We discuss the usefulness of the double charge-exchange reactions (DCX) for the production of the neutron-rich Λ-hypernuclei. We believe the (π-, K+) reaction is one of the most promising DCX reactions, and propose to produce the neutron-rich Λ-hypernuclei, and , at the J-PARC 50 GeV PS by the reaction (J-PARC E10 experiment). The design of the experiment is presented.
14584078
Classical Solutions and Order of Zeros in Open String Field Theory
Earlier an analytic approach is proposed for classical solutions describing tachyon vacuum in open string field theory. Based on the approach, we construct a certain class of classical solutions written in terms of holomorphic functions with higher order zeros. Taking the simplest among the new classical solutions, we study the cohomology of the new BRS charge and make a numerical analysis of the vacuum energy. The results indicate that the new non-trivial solution is another analytic candidate for the tachyon vacuum.
120125275
Applications and Imaging Techniques of a Si/CdTe Compton Gamma-Ray Camera
Abstract By using a new Compton camera consisting of a silicon double-sided strip detector (Si-DSD) and a CdTe doublesided strip detector (CdTe-DSD), originally developed for the ASTRO-H satellite mission, an experiment involving imaging radioisotopes was conducted to study their feasibility for hotspot monitoring. In addition to the hotspot imaging already provided by commercial imaging systems, identification of various radioisotopes is possible thanks to the good energy resolution obtained by the semiconductor detectors. Three radioisotopes of 133 Ba (356 keV), 22 Na (511 keV) and 137 Cs (662 keV) were individually imaged by applying event selection in the energy window and the gamma-ray images were correctly overlapped by an optical picture. Detection efficiency of 1.68 ×10 −4 (effective area: 1.7×10 −3 cm 2 ) and angular resolution of 3.8 degrees were obtained by stacking five detector modules for a 662 keV gamma ray. The higher detection efficiency required in specific use can be achieved by stacking more detector modules.
7284952
Marginal deformations and closed string couplings in open string field theory
We investigate analytic classical solutions in open string field theory which are constructed in terms of marginal operators. In the classical background, we evaluate a coupling between an on-shell closed string state and the open string field. The resulting coupling exhibits periodic behavior as expected from the marginal boundary deformation of background Wilson lines or a marginal tachyon lump. We confirm that the solutions in open string field theory correspond to a class of marginal deformations in conformal field theory.