Stefan Hoeche, SLAC
Combining Matrix Elements and Parton Showers at NLO
Meeting Room 1, Kenkyu Honkan 1F
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.
Masahiro Isaka, RIKEN
Structure of p-sd shell Λ hypernuclei modified and probed by Λ hyperon
Meeting Room 1, Kenkyu Honkan 1F
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.
Yutaka Ookouchi, Kyoto U
Cosmic R-tube, Vacuum Instability and R-axion Cosmology
Meeting Room 1, Kenkyu Honkan 1F 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.
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].
Eibun Senaha, Nagoya U
Z'-ino driven electroweak baryogenesis
Meeting Room 1, Kenkyu-Honkan 1F
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.
Yasuro Funaki, RIKEN
[cancelled] A new theoretical approach to triple-alpha thermonuclear reaction rate
Meeting Room 1, Kenkyu Honkan 1F
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.
Daisuke Yamauchi, RESCUE
Open inflation in the Landscape
Meeting Room 1, Kenkyu Honkan 1F
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.
伊藤憲二, The Graduate University for Advanced Studies
日本における量子物理学研究の始まりと量子力学の解釈
Room 322, Kenkyu Honkan 3F
日本の物理学は量子力学の導入を契機に、１９３０年代に国際的な研究水準に達した。 本セミナーでは、 この時期の日本の物理学研究がどのように変化をし、日本で量子物理学の研究が始まったのかについてお話する。 とくに、その過程で、量子力学の概念的な側面、不確定性関係、相補性、波動関数の確率解釈等に対して、 日本の物理学者やその他の知識人がどのように反応し、どのような議論が生じたのかについて述べる。
Shinji Shimasaki, Kyoto U
[Strings and Fields Group Seminar] Exact results of theories with SU(2|4) symmetry and gauge/gravity correspondence
Meeting room 1, Kenkyu honkan 1F
We study the theories with SU(2|4) symmetry which consist of the plane wave matrix model (PWMM), super Yang-Mills theory (SYM) on RxS^2 and SYM on RxS^3/Z_k. The last two theories can be realized as theories around particular vacua in PWMM, through the commutative limit of fuzzy sphere and Taylor’s T-duality. We apply the localization method to PWMM to reduce the partition function and the expectation values of a class of supersymmetric operators to matrix integrals. By taking the commutative limit and performing the T-duality, we then obtain the matrix integrals for SYM on RxS^2 and SYM on RxS^3/Z_k. We also discuss some applications of our results to gauge/gravity correspondence and little string theory on RxS^5.
Natsumi Nagata, Nagoya University
Minimal SUSY SU(5) GUT in the high-scale SUSY scenario
Meeting Room 1, Kenkyu Honkan 1F
We revisit the minimal supersymmetric SU(5) grand unified theory (SUSY SU(5) GUT) in the high-scale SUSY scenario. Although the model has been believed to be excluded due to the too short lifetime of proton, we have found that it is possible to evade the experimental constraints on the proton decay rate if the supersymmetric particles have masses much heavier than the electroweak scale. With such heavy sfermions, the 126GeV Higgs boson is naturally explained, while they do not spoil the gauge coupling unification and the existence of dark matter candidates. Since the resultant proton lifetime lies in the regions which may be reached in the future experiments, proton decay searches may give us a chance to verify the scenario as well as the supersymmetric grand unified models.
Kohta Murase, Hubble Fellow, Institute for Advanced Study
Cascade Gamma rays: Revealing the Obscured Universe
Seminar room, Kenkyu honkan 3F
