セミナー

木村元, Shibaura Institue of Technology

量子力学の原理探求をする意義と最近の進展

Seminar room, Kenkyu honkan 3F
量子力学を — アプリオリな数学ではなく — 物理原理に基づき構築する試みを紹介する.これは近年世界的に研究が進められる一方,国内での関心は高いとは言えない.そこで本セミナーの主目的を,物理理論を原理ベースで理解する意義を共有することとする.その上で,量子力学の原理探求の最適な舞台となる「操作主義的な確率論」を説明し,本研究に関する最新の成果を紹介する.

Ryuichiro Kitano, Tohoku University

Higgs mechanism and confinement

Meeting room 1, Kenkyu honkan, 1F
We take both phenomenological and theoretical approaches to this hypothesis, and find that the interpretation seems to show interesting consistencies. In particular, one can identify the rho and omega mesons as the magnetic gauge bosons which provide an explanation of the quark confinement via the dual Meissner effect.

Takayasu Sekihara, KEK

Branching ratios of stopped K^- absorption on light nuclei

Seminar room, Kenkyu honkan 3F
In this seminar we discuss the branching ratios of stopped K^- absorption on light nuclei in order to clarify the low-energy antikaon-nucleon interaction. We investigate the mesonic (K^- “N” -> pi Y) and non-mesonic (K^- “N N” -> Y N) absorption processes of the stopped K^- -light nucleus systems. Here we consider deuteron and helium-4 as the K^- absorption targets with realistic wave functions for them, and calculate the branching ratios to compare with the experimental results. We also give several theoretical interpretations of the branching ratios, especially from viewpoint of the Lambda(1405) structure.

Takumi Ito, KEK

Supersymmetric Model with Long-lived Stau at the LHC

Meeting room 1, Kenkyu honkan 1F
Supersymmetric extension of standard model of particle physics is an attractive candidate of TeV energy scale new physics, and an important target of the Large Hadron Collider.
So far, several techniques have been proposed to discover the new physics, and to measure properties of new particles.
Importantly, however, the strategy that we should take depends on the event topology, namely, details of the new physics; particle contents, mass spectrum, and so on.
In this talk, we study the case that the lightest superparticle (LSP) is the gravitino, and in this case, the next-to-lightest superparticle (NLSP) may have very long lifetime.
In addition, if the NLSP is charged particle, it may be possible to directly observe a track of the NLSP in the detectors; this is an characteristic event signal of such a model.
We discuss how we can probe the model by utilizing the charged track of NLSP, paying particular attention to the case that NLSP is the stau.

Naoki Yamamoto, University of Washington

Holography and anomaly matching for resonances

Meeting room 3, Kenkyu honkan 1F
We show a new universal relation for triangle anomalies, an “anomaly matching” for resonances, in a class of holographic models of QCD. We argue its possible realization and consequences in real QCD.

Jiro Arafune, National Institution for Academic Degrees and University Evaluation

Relic Neutrino の反射、屈折について

Seminar hall, 3 go-Kan
Relic Neutrinoの直接観測は大変困難だが、標的からのニュートリノのコヒーレントな反射、屈折によるrecoilを観測できないか、という理論的な考察が古くからなされてきた。そして、ほとんど不可能という結論がされてきている。主な理由は、コヒーレントな散乱では、ニュートリノが標的へ入射する際と、標的から脱出する際とで、recoilが相殺するからである。それを相殺しない工夫を考察しているのだが、まだよくわからないところがあって、確定的な結論に至っていない。議論していただけると幸いです。

Ken-ichi Nishikawa, UAH/CSAPR

Radiation from accelerated particles in shocks and reconnections

Meeting room 3, Kenkyu honkan 1F
We have investigated particle acceleration and shock structure associated with an unmagnetized relativistic jets propagating into an unmagnetized plasmas. Strong magnetic fields generated in the trailing shock contribute to the electronstransverse deflection and acceleration. We have calculated, self-consistently, the radiation from electrons accelerated in the turbulent magnetic fields. We found that the synthetic spectra depend on the Lorentz factor of the jet, its thermal temperature and strength of the generated magnetic fields. The properties of the radiation may be important for understanding the complex time evolutionand/or spectral structure in gamma-ray bursts, relativistic jets in general, and supernova remnants.

Laila Alabidi, Yukawa Institute for Theoretical Physics, Kyoto University

A further discriminatory signature of inflation

Meeting room 3, Kenkyu honkan 1F
In this talk I revise the current status of canonical single field models of inflation in light of the WMAP 7 data, using the observational bounds on the spectral index and tensor fraction, extracted using the large scale measurements of the Cosmic Microwave Background. I then extend this analysis to include models which predict a significant positive running of the spectral index, which can lead to the production of Primordial Black Holes (PBHs) towards the end of inflation. I then explain the concept of induced gravitational waves, which are gravitational waves induced by scalar perturbations re-entering the horizon during nucleosynthesis. I consider the case where the scalar perturbations are created by Hilltop-type and Running Mass Models, and where the gravitational waves are induced early on in the radiation phase of the Universe. I explore the impact a detection of such GWs would have on the field of Inflation Model Discrimination in general. I show that the Hilltop-type model can produce observable induced gravitational waves within the range of BBO and DECIGO for integral and fractional powers of the potential within a reasonable number of e−folds. I also show that the running mass model can produce a spectrum within the range of these detectors, but require that inflation terminates after an unreasonably small number of e−folds.

Yaroslav klopot, Dubna, JINR

Axial anomaly and transition form factors of pseudoscalar mesons

Meeting room 1, Kenkyu honkan 1F
We study photon-meson transition form factors of pseudoscalar mesons by means of anomaly sum rule, a relation which follows from dispersive representation of axial anomaly. As the anomaly sum rule is an exact relation (perturbative and nonperturbative corrections are absent), it allows us to study the interplay between possible corrections to continuum and to lower states within method which does not rely on QCD factorization hypothesis. We show, relying on the recent data of the BaBar Collaboration, that while the relative correction to continuum is quite small, the correction to continuum can dramatically change the pion form factor. In the octet channel, where a strong mixing between $eta$ and $eta’$ is present, the anomaly sum rule allows to get additional constraints for the mixing parameters. The notion of quark-hadron duality in our approach is discussed.

Hayato Motohashi, RESCEU, University of Tokyo

f(R) models for the early and the present acceleration of the Universe

Meeting room 1, Kenkyu honkan 1F
f(R) gravity is a simple and nontrivial extension of General Relativity. The idea was originally proposed in 1980 by Starobinsky, and now it is recognized as R^2 inflationary model. Several years ago, it was also applied to describe dark energy in the present Universe. Although some of f(R) models can satisfy laboratory, Solar system and cosmological tests, it was found that there are weak singularities and other problems in this class of models. Recently, it is found that we are able to cure the problem and describe both accelerating expansion in the early and the present Universe. I will talk about this class of f(R) models and the dynamics during inflation and reheating.

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