6685102
Effects of cosmological moduli fields on cosmic microwave background
Abstract We discuss effects of cosmological moduli fields on the cosmic microwave background (CMB). If a modulus field φ once dominates the universe, the CMB we observe today is from the decay of φ and its anisotropy is affected by the primordial fluctuation in the amplitude of the modulus field. Consequently, constraints on the inflaton potential from the CMB anisotropy can be relaxed. In particular, the scale of the inflation may be significantly lowered. In addition, with the cosmological moduli fields, correlated mixture of adiabatic and isocurvature fluctuations may be generated, which results in enhanced CMB angular power spectrum at higher multipoles relative to that of lower ones. Such an enhancement can be an evidence of the cosmological moduli fields, and may be observed in future satellite experiments.
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.
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.
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.
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.
118368386
Homotopy Operators and One-Loop Vacuum Energy at the Tachyon Vacuum
We construct homotopy operators for the BRST operator in the theory around identitybased solutions, which are believed to represent the tachyon vacuum in the cubic bosonic open string field theory. Using the homotopy operators, we find that the one-loop vacuum energy at the tachyon vacuum is independent of moduli such as interbrane distances, which are included in the BRST operator. We also revisit the cohomology problem, which was solved earlier without the homotopy operators. Subject Index: 126, 128
15573623
Gauge Invariant Overlaps for Classical Solutions in Open String Field Theory
Abstract We calculate gauge invariant observables for Schnabl's solution with analytic method and with the level truncation approximation. We also compute them for the numerical solution initially obtained by Sen and Zwiebach in the level truncation approximation to compare with the one for Schnabl's solution. The results are consistent with the expectation that they may be gauge equivalent. We briefly discuss the gauge invariant observables and the action for a marginal solution with a nonsingular current.
14617932
CONFORMAL ANOMALY OF STRING THEORY IN THE HARMONIC GAUGE
Considering the conformal anomaly in an effective action, the critical dimension of string theory can be determined in the harmonic gauge, in which it had been previously reported to be indefinite. In this gauge, there is no anomaly for the ghost number symmetry. This can be naturally understood in terms of the Faddeev-Popov conjugation in the theory.
8004895
Open string field theory on noncommutative space
We study Witten's open string field theory in the presence of a constant B field. We construct the string field theory in the operator formalism and find that, compared to the ordinary theory with no B field, the vertices in the resulting theory has an additional factor. The factor makes the zero modes of strings noncommutative. This is in agreement with the results in the first-quantized formulation. We also discuss background independence of the purely cubic action derived from the above string field theory and then find a redefinition of string fields to remove the additional factor from the vertex. Furthermore, we briefly discuss the supersymmetric extension of our string field theory.
15814466
Dilaton Condensation in Cubic Open String Field Theory
We construct an exact and finite classical solution in cubic open string field theory. The classical solution has a well-defined Fock space expression. Through the redefinition of a string field, the string field theory expanded around the classical solution can be transformed into the theory with a different coupling constant, where other backgrounds are unchanged. Therefore, the classical solution represents the condensation of the dilaton in cubic open string field theory. E-mail address: tomo@asuka.phys.nara-wu.ac.jp E-mail address: tanimoto@asuka.phys.nara-wu.ac.jp