BRS Invariance of Unoriented Open-Closed String Field Theory.
We present the full action for the unoriented open-closed string field theory which is based on the \alpha=p^+ HIKKO type vertices. The BRS invariance of the action is proved up to the terms which are expected to cancel the anomalous one-loop contributions. This implies that the system is invariant under the gauge transformations with open and closed string field parameters up to the anomalies.

title: Closed string amplitudes in open string field theory
abstract: We investigate gauge invariant operators corresponding to on-shell closed string states in open string field theory. Using both oscillator representation and conformal mapping techniques, we calculate a two closed string tachyon amplitude that connects two gauge invariant operators by an open string propagator. We find that this amplitude is in a complete agreement with the usual disc amplitude.

title: Level truncation analysis of exact solutions in open string field theory
abstract: 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.

title: On the Generalized Gluing and Resmoothing Theorem
abstract: The generalized gluing and resmoothing theorem originally proved by LeClair, Peskin and Preitschopf, gives a powerful formula for the fused vertex obtained by contracting any two vertices in string field theories. Although the theorem is naturally expected to hold for the vertices at any loop level, the original proof was restricted to the vertices at tree level. Here we present a simplified proof for the tree level theorem and then prove explicitly the extended version at one-loop level. We also find that a non-trivial sign factor, which depends on the string states to be contracted, appears in the theorem. This sign factor turns out to be essential for reproducing correctly the conformal field theory correlation function on the torus.

title: Marginal deformations and closed string couplings in open string field theory
abstract: 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.

title: Tachyon condensation and universal solutions in string field theory
abstract: We investigate a non-perturbative vacuum in open string field theory expanded around the analytic classical solution which has been found in the universal Fock space generated by matter Virasoro generators and ghost oscillators. We carry out level-truncation analyses up to level (6,18) in the theory around one-parameter families of the solution. We observe that the value of the vacuum energy cancels the D-brane tension as the approximation level is increased, but this non-perturbative vacuum disappears at the boundary of the parameter space. These results provide strong evidence for the conjecture that, although the universal solutions are pure gauge in almost all the parameter space, they are regarded as the tachyon vacuum solution at the boundary.

title: Spectator field models in light of spectral index after Planck
abstract: We revisit spectator field models including curvaton and modulated reheating scenarios, specifically focusing on their viability in the new Planck era, based on the derived expression for the spectral index in general spectator field models. Importantly, the recent Planck observations give strong preference to a red-tilted power spectrum, while the spectator field models tend to predict a scale-invariant one. This implies that, during inflation, either (i) the Hubble parameter varies significantly as in chaotic inflation, or (ii) a scalar potential for the spectator field has a relatively large negative curvature. Combined with the tight constraint on the non-Gaussianity, the Planck data provides us with rich implications for various spectator field models.

title: 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.

title: Mixed inflaton and spectator field models after Planck
abstract: We investigate the possibility that the primordial perturbation has two sources: the inflaton and a spectator field, which is not dynamically important during inflation but which after inflation can contribute to the curvature perturbation. We derive the constraints on the model by using recent Planck results on the spectral index, tensor-to-scalar ratio and nonlinearity parameters fNL and τNL for the cases with and without specifying the inflation and spectator models. If one chooses the spectator to be the curvaton with a quadratic potential, non-Gaussianities can be computed and imply restrictions on possible values of the ratio of the spectator-to-inflaton power R. We also consider a mixed curvaton and chaotic inflation model and show that even quartic chaotic inflation is still feasible in the context of mixed models even with Planck data.

title: Primordial non-Gaussianity in models with dark matter isocurvature fluctuations
abstract: We investigate primordial non-Gaussianity and dark matter isocurvature fluctuations in the modulated reheating and the curvaton scenarios. In these scenarios, a large non-Gaussianity can be generated; on the other hand, depending on how dark matter is produced, too large isocurvature fluctuations can also arise, which is inconsistent with current observations. In this paper, we study this issue in a mixed scenario where the curvature fluctuations can also be produced from the inflaton fluctuations as well as those from a light scalar field such as the modulus and the curvaton. We show that primordial fluctuations can be highly non-Gaussian without conflicting with the current constraint on isocurvature fluctuations for such mixed scenarios. However, if the constraint on isocurvature fluctuations becomes severer as expected by the Planck satellite, f{sub NL}, a nonlinearity parameter for adiabatic fluctuations, should be very small as f{sub NL} < or approx. 3, which would give interesting implications for the generation mechanism of dark matter. Non-Gaussianity from isocurvature fluctuations is also discussed in these scenarios.

title: Large tensor-to-scalar ratio in small-field inflation.
abstract: We show that density perturbations seeded by the inflaton can be suppressed when having additional light degrees of freedom contributing to the production of perturbations. The inflaton fluctuations affect the light field dynamics by modulating the length of the inflationary period and, hence, produce additional density perturbations in the postinflationary era. Such perturbations can cancel those generated during inflation as both originate from the same inflaton fluctuations. This allows production of large gravitational waves from small-field inflation, which is normally forbidden by the Lyth bound on the inflaton field excursion. We also find that the field bound is taken over by the light scalar when the inflaton-induced perturbations are suppressed and, thus, present a generalized form of the Lyth bound that applies to the total field space. The novel mechanism allows violation of the usual consistency relation r≤-8n(T) for the tensor spectral index.