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.
2581930
Non-Gaussianity and baryonic isocurvature fluctuations in the curvaton scenario
Abstract We discuss non-Gaussianity and baryonic isocurvature fluctuations in the curvaton scenario, assuming that the baryon asymmetry of the universe originates only from the decay products of the inflaton. When large non-Gaussianity is realized in such a scenario, non-vanishing baryonic isocurvature fluctuations can also be generated unless the baryogenesis occurs after the decay of the curvaton. We calculate the non-linearity parameter f NL and the baryonic isocurvature fluctuations, taking account of the primordial fluctuations of both the inflaton and the curvaton. We show that, although current constraints on isocurvature fluctuations are severe, the non-linearity parameter can be large as f NL ∼ O ( 10 – 100 ) without conflicting with the constraints.
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.
9788705
Non-Gaussianity, Spectral Index and Tensor Modes in Mixed Inflaton and Curvaton Models
We study non-Gaussianity, the spectral index of primordial scalar fluctuations, and tensor modes in models where fluctuations from the inflaton and the curvaton can both contribute to the present cosmic density fluctuations. Even though simple single-field inflation models generate only tiny non-Gaussianity, if we consider such a mixed scenario, large non-Gaussianity can be produced. Furthermore, we study the inflationary parameters such as the spectral index and the tensor-to-scalar ratio in this kind of models and discuss in what cases models predict the spectral index and tensor modes allowed by the current data while generating large non-Gaussianity, which may have many implications for model-buildings of the inflationary universe.
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.
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.
13428791
Open String Field Theory around Universal Solutions
We study the physical spectrum of cubic open string field theory around universal solutions, which are constructedusing the matter Virasoro operators andthe ghost andantighost fields. We find the cohomology of the new BRS charge around the solutions, which appear with a ghost number that differs from that of the original theory. Considering the gauge-unfixedstring fieldtheory, we conclud e that open string excitations perturbatively disappear after the condensation of the string field to the solutions.
10883259
Duality of a supersymmetric model with the Pati-Salam group
Recently one of the authors proposed a dual theory of a Supersymmetric Standard Model (SSM), in which it is naturally understood that at least one quark (the top quark) should be heavy, i.e., almost the same order as the weak scale, and the supersymmetric Higgs mass parameter $\mu$ can naturally be expected to be small. However, the model cannot have Yukawa couplings of the lepton sector. In this paper, we examine a dual theory of a Supersymmetric Model with the Pati-Salam gauge group $SU(4)_{PS}\times SU(2)_L\times SU(2)_R $ with respect to the gauge group $SU(4)_{PS}$. In this scenario, Yukawa couplings of the lepton sector can be induced. In this model the Pati-Salam breaking scale should be around the SUSY breaking scale.
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.
118580858
High-resolution search for the Theta(+) pentaquark via a pion-induced reaction at J-PARC
The pentaquark Theta(+) has been searched for via the pi(-) p --> K- X reaction with beam momenta of 1.92 and 2.01 GeV/c at J-PARC. A missing mass resolution of 2 MeV (FWHM) was achieved but no sharp peak structure was observed. The upper limits on the production cross section averaged over the scattering angle from 2 degrees to 15 degrees in the laboratory frame were found to be less than 0.28 mu b/sr at the 90% confidence level for both the 1.92- and 2.01- GeV/c data. The systematic uncertainty of the upper limits was controlled within 10%. Constraints on the Theta(+) decay width were also evaluated with a theoretical calculation using an effective Lagrangian. The present result implies that the width should be less than 0.36 and 1.9 MeV for the spin-parity of 1/2(+) and 1/2(-), respectively
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.