ここ四半世紀、アハロノフの弱値 weak value という妖怪が、量子論界隈を徘徊してやむ事がなかった。「弱い測定 weak measurement」による実験的実現も得る一方、 数多くの論文の中で時に神秘的な装いで現れるこの弱値概念であるが、しかしこれを通常の量子力学の形式の中でどう理解すればいいのか、多くの研究家が頭を悩ませてきたのも事実である。今回の話では、この量子的弱値を、ヒルベルト空間の直交系を用いたごく普通の量子論の定式化の枠組みに、どう位置づけるかを考えてみたい。ここで鍵となるのが「量子演算子を完全に記述する弱値の一式」という考え方である。 さらにそのような一式を持ち出す利点を、「射影測定を行う時どのような場合に歴史を消せるか」という応用問題を取り上げて説明してみたい。

The inflaton must convert its energy into radiation after inflation, which, in a conventional scenario, is caused by the perturbative decay of inflaton.

However, the process of reheating would be much more complicated in some cases, since the decay products obtain masses from an oscillating inflaton and thermal environment. Hence, the conventional reheating scenario where the reheating takes place via the perturbative decay of inflaton can be modified. We study in detail processes of reheating: non-perturbative particle production from the inflaton and the subsequent evolution of inflaton/plasma system by taking account for the thermal dissipation of inflaton in a hot plasma.

In this talk, at first, I would like to explain general aspects of dynamics of oscillating scalar field in the early universe, and then, move on to its application to the reheating after inflation. In particular, I will show that the reheating temperature is significantly affected by the thermal dissipation; especially the deviation from the conventional reheating scenario becomes prominent for smaller inflaton mass.

n-DBI gravity is a gravitational theory motivated by Dirac-Born-Infeld type conformal scalar theory and designed to yield non-eternal inflation spontaneously without introducing any scalar field. It contains the space-time foliation provided by an everywhere time-like vector field n, which couples to the gravitational sector of the theory, but decouples in the small curvature limit. In my talk, I will explain some theoretical aspects of the model in detail by showing its interesting black hole solutions.

In the first talk, we will give an overview of string phenomenology.
In the second talk, we will argue cosmology in 4 dimensional N=1 supergravity which can be derived from type IIB supergravity in flux vacua. We will show that dark radiation, which is a reletivistic dark matter, is naturally generated from the decay of the overall volume modulus in the LARGE volume scenario. Then, the axionic superpartner of the modulus accounts for the dark radiation, which is constrained by the observation of CMB by the Planck satellite, while the modulus decay into Higgses through the Giudice-Masiero term gives the contribution to a reheating temperature of our sector. To obtain a viable reheating, we need, say, 9 Higgs doublet pairs; otherwise too much dark radiation is obtained. Hence, this illustrates a new type of moduli problem: Moduli-induced axion problem. Then, if viable, we can find also the candidates of cold (non-relativistic) dark matter, which are Wino and/or QCD axion.

This talk discusses a new method to combine NLO QCD calculations at the parton level with the resummation encoded in parton showers. First applications are presented, including W-boson + multi-jet production at the LHC and top-quark pair production at the Tevatron.

In this talk, we will discuss structure of Λ hypernuclei with mass number A ~ 20, so called p-sd shell Λ hypernuclei. One of the unique and interesting aspects of hypernuclei is structure change caused by hyperons as an impurity in nuclei. In p-shell Λ hypernuclei, experimental and theoretical studies have revealed a couple of interesting structure changes such as changes of deformation and shrinkage of the inter-cluster distance. In sd-shell Λ hypernuclei, we can expect various structure changes depending on the structure of the core nuclei, since sd-shell normal nuclei have various structure such as pronounced cluster structure, triaxial deformation and coexistence of shell-model like and cluster structure in ground and low-lying states. To reveal such phenomena, we have extended the antisymmetrized molecular dynamics (AMD) to hypernuclei. The AMD model can describe various nuclear structures without any assumption on clustering and deformation of nuclei. In this talk, we will discuss possible structure changes by adding Λ in Be and Ne hypernuclei based on the AMD calculation. Furthermore, we will show a possibility to study the nuclear (triaxial) deformation of Mg by using Λ as a probe.

We study general constraints on spontaneous R-symmetry breaking models. Firstly, we investigate a cosmic string associated with the R-symmetry breaking which can be viewed as a tube-like domain wall with a winding number interpolating a false vacuum and a true vacuum. Such string causes inhomogeneous decay of the false vacuum to the true vacuum via rapid expansion of the radius of the tube and hence its formation would be inconsistent with the present Universe. Secondary, we show general constraints coming from the cosmological effects of the pseudo Nambu-Goldstone bosons, R-axions. They are substantially produced in the early Universe and may cause several cosmological problems.
References: arXiv:1211.5662 [hep-ph], 1211.7237 [hep-th], 1303.2740 [hep-ph], 1304.0623 [hep-ph].

In this talk, feasibility of electroweak baryogenesis in the U(1)-prime extended MSSM (UMSSM) is examined in light of the recently observed 126 GeV Higgs boson. I will begin with a pedagogical review of electroweak baryogenesis. Then I will discuss a baryon number preservation criterion focusing especially on a sphaleron energy, and study strength of the 1st-order electroweak phase transition. Then I will estimate the baryon number density in a specific scenario in which Z’-ino plays an essential role. Finally, I will give a brief summary and outlook.

Recently triple-alpha thermonuclear reaction rate is discussed using some theoretical approaches at low temperature region (below 1 GK), where experimental date is not available. One of them, the calculation via CDCC (Continuum Discretized Coupled Channel) method, in particular, predicts much larger reaction rate by 10^{25} at 0.01 GK, than a standard estimation by NACRE compilation, which is usually utilized for investigating evolutions of stars. It is thus very important to give predictions from other theoretical methods to solve this discrepancy. For this purpose, we introduce a new theoretical approach based on an imaginary-time method, which has an advantage that the knowledge of three-body boundary condition is not required. We show that our results are consistent with the NACRE compilation for whole temperature region from 1 GK to 0.01 GK. We also discuss the reason why the coupled-channel approach gives the much larger reaction rate at low temperature region. This exists in truncation of the channel number adopted for continuum states of 8Be, giving a rise to a large enhancement of the reaction rate at low temperature region.

Vaccum decay is one of the most intriguing phenomena in field theory. It occurs via the nucleation of a vacuum bubble by quantum tunneling from a metastable vacuum. When gravity is included, the tunneling is mediated by an O(4)-symmetric solution of Euclidean Einstein-scalar field equations. Though there is no direct evidence that our part of the universe is inside one of those nucleated bubbles, there are theoretical reasons to believes that it may be actually the case. In this talk I discuss the possible observational signatures of the quantum tunneling. I specifically focus on two cases: the signatures in large angle CMB power spectrum, and spatially localized anisotropies.