Kin-ya Oda, Osaka U
Minimal Higgs inflation
Meeting room 1, Kenkyu honkan 1F
We consider a possibility that the Higgs field in the Standard Model (SM) serves as an inflaton when its value is around the Planck scale. We assume that the SM is valid up to an ultraviolet cutoff scale Lambda, which is slightly below the Planck scale, and that the Higgs potential becomes almost flat above Lambda. Contrary to the ordinary Higgs inflation scenario, we do not assume the huge non-minimal coupling, of O(10^4), of the Higgs field to the Ricci scalar. We find that Lambda must be less than 5*10^{17}GeV in order to explain the observed fluctuation of the cosmic microwave background, no matter how we extrapolate the Higgs potential above Lambda. The scale 10^{17}GeV coincides with the perturbative string scale, which suggests that the SM is directly connected with the string theory. For this to be true, the top quark mass is restricted to around 171GeV, with which Lambda can exceed 10^{17}GeV. As a concrete example of the potential above Lambda, we propose a simple log type potential. The predictions of this specific model for the e-foldings N_*=50–60 are consistent with the current observation, namely, the scalar spectral index is n_s=0.977–0.983 and the tensor to scalar ratio 0
Richard Easther, The University of Auckland
Monodromy Inflation: Nonlinear Dynamics and Observational Status
Meeting room 3, Kenkyu honkan 1F
I will discuss the phenomenology and observational status of monodromy inflation. This apparently simple model is based on a stringy axion associated with a weakly broken shift-symmetry. I will show that the post-inflationary dynamics may naturally contain a phase where the universe is dominated by oscillons, pseudo-stable solutions of a nonlinear scalar field theories. Conversely, the inflationary perturbations can include a superimposed “modulation”, and I will discuss current constraints on the amplitude of these modulations, derived from the WMAP and Planck datasets.
Kunio Kaneta, Kavli IPMU
Higgs pair production at the LHC and ILC as a clue to new physics
Meeting room 3, Kenkyu honkan 1F
The measurement of the Higgs boson self-coupling is important to understand what kind of force makes the Higgs boson acquires a VEV. It is expected that Higgs cubic coupling is measured by Higgs pair production at the LHC and ILC, and the deviations from the SM in the Higgs pair production process can give us a hint of new physics beyond the SM. We consider this process from a general potential that achieves the suitable EW symmetry breaking. As an interesting example, we discuss non-perturbative Higgs model in which a runaway type of potential is used. In the model, the cross sections of pair production can be enhanced compared to the SM. We also discuss the Higgs pair production induced by a non-canonical kinetic term of Higgs field, which will be important for searching the pair production at the ILC.
Lu-Hsing Tsai, NTHU, Taiwan
Majorana neutrinos and multi-component Dark Matter Model from AMS-02 Result.
Meeting room 3, Kenkyu honkan 1F
Recently AMS-02 gives the most accurate measurement of positron fraction in cosmic rays. The traditional astrophysical sources can not explain the excess above 10 GeV in both spectrums of total fluxes of electron/ positron by Fermi-LAT and positron fraction by AMS-02. The extra contribution from dark matter decay or annihilation could provide a promising explanation. In this talk I will show how to simultaneously explain the anomalies of Fermi-LAT and AMS-02 results by a decaying dark matter model with two dark matter components, each of which has two-body leptonic decays as the main channels. In such scenarios there also exist substructures in these spectrums. This model satisfies the constraints by the observation of diffuse gamma-rays by Fermi-LAT. We also show that heavy Majorana neutrinos could be a possible candidate for dark matter in this scenario.
Hiroyuki Ishida, Tohoku U
Baryogenesis and Dark Mmatter with Sterile Neutrinos
Meeting room 3, Kenkyu honkan 1F
Sterile neutrinos below electroweak scale can solve baryon asymmetry of the universe, tiny neutrino masses and a candidate of dark matter at the same time. In this work, we derive the kinetic equations for density matrices with exact momentum dependence holding total lepton number conservation. We evaluate the amount of baryon number generation more accurately by these kinetic equations. Furthermore, X-ray observations give us very severe constraints on the magnitude of interaction and the range of mass of decaying strerile neutrino dark matter. However, the enough suppressed Yukawa couplings cannot be realized as long as seesaw is preserved. We call such requirement of fine tuning as “Longevity problem”. This problem can be solved by split flavor mechanism in which we introduced multiple B-L Higgs fields and a flavor symmetry. The predicted X-ray flux can be just below the current experimental bound naturally
Mitsutoshi Fujita 藤田充俊, Kavli IPMU
[Strings and Fields Group Seminar] From Maxwell-Chern-Simons theory in AdS3 towards hydrodynamics in 1 + 1 dimensions (AdS_3上のMaxwell-Chern-Simonsから1+1次元の流体力 学に向けて)
Meeting Room 3, Main Bldg. 1F We study Abelian Maxwell-Chern-Simons theory in three-dimensional AdS black hole backgrounds for both integer and non-integer Chern-Simons coupling. In particular we find exact solutions in the low-frequency, low-momentum limit, ω, k << T (hydrodynamic limit). Using the holographic principle, we translate our results into correlation functions of vector and scalar operators in the dual strongly coupled
We study Abelian Maxwell-Chern-Simons theory in three-dimensional AdS black hole backgrounds for both integer and non-integer Chern-Simons coupling. In particular we find exact solutions in the low-frequency, low-momentum limit, ω, k << T (hydrodynamic limit). Using the holographic principle, we translate our results into correlation functions of vector and scalar operators in the dual strongly coupled
1+1-dimensional quantum
field theory with a chiral anomaly at non-zero temperature T. Starting from the conformal case we show applicability of the hydrodynamic limit and discuss extensions to the non-conformal case.
Correlation functions in the conformal case are confirmed by comparison to an exact field-theoretic computation. Also a top-down string construction is provided as the ultraviolet completion for our Maxwell-Chern-Simons actions.
Tomoya Takiwaki, National Astronomical Observatory
Three dimensional simulations of core-collapse supernovae
Meeting room 1, Kenkyu honkan 1F
Star’s multimillion-year life is terminated abruptly and violently within seconds and then announced over months via the brilliant optical emission by the supernova explosion. How does this process proceed? That is long mystery and attractive frontier of astrophysics. Neutrino heating mechanism seem to be promising scenario, however, theoretical modeling is still controversial since the simulations of neutrino radiation transport are extremely difficult. The master equation of the neutrino transport is 6 dimensional Boltzmann equation and that require extraordinary expensive computational resources. Supernovae modeling have been done with the limitation of special and phase dimension of the system to economize computational resources. Now we open the door of 3 dimensional, “Natural” simulations of core-collapse supernovae with a help of recent development of numerical techniques and enlarged computational resources provided by K-computer and XC30 in NAOJ. In this seminar, we report our recent effort for realistic supernovae modeling.
Satoshi Nakamura, Osaka University
[Paricle and Nuclear Physics Seminar at J-PARC] Neutrino-induced meson productions off nucleon in resonance region
Tokai 1st building 115
Future neutrino experiments are planned to address questions such as leptonic CP violation and mass hierarchy. For this purpose, it is essential to have more quantitative understanding of the neutrino-nucleus scattering. The neutrino energy spans rather wide range including the nucleon resonance region for which we have been working. We have developed a dynamical coupled-channels (DCC) model that describes piN, gamma N -> piN, etaN, KLambda, KSigma reactions. We extend the DCC model to work on the neutrino reactions. In this presentation, I explain the DCC model, and show the quality of the fit to the piN and gammaN data. Then I discuss our strategy for extending the DCC model to the neutrino reactions. As a first step, we study the forward neutrino-induced meson productions using the PCAC hypothesis, for which I present numerical results.
Yoichi Iwasaki, KEK
Global Structure of Conformal Theories in the SU(3) Gauge Theory
Meeting room1, Kenkyu honkan 1F
We investigate SU(3) gauge theories in four dimensions with N_f fundamental fermions, on a lattice using the Wilson fermion. We first introduce a new concept “conformal theories with an IR cutoff’, after pointing out that the following two categories in SU(3) gauge theories with fundamental N_f fermions possess an IR fixed point: Large N_f (N_f^c ≦ N_f ≦ 16) QCD within the conformal window (referred as Conformal QCD) and small N_f (1 ≦ N_f ≦ N_f^c-1) QCD at temperature T/T_c > 1 (referred as High Temperature QCD). In the case of Conformal QCD in the continuum limit, the compact space and/or time gives an IR cutoff. In the case of High Temperature QCD, the temperature T plays a role of an IR cutoff together with a cutoff due to possible compact space, depending on how to take the continuum limit. We note any lattice calculation is performed on a finite lattice. Thus any calculation on a lattice possesses an IR cutoff. In the conformal theories with an IR cutoff there exists the “conformal region” together with the confining region and the deconfining region. We verify numerically on a lattice of the size 16^3×64 the existence of the conformal region and the non-trivial Z(3) structure of the vacuum and the Yukawa-type decay form of meson propagators in the conformal region. We stress that High Temperature QCD is intrinsically accompanied with an IR cutoff. Therefore the understanding the vacuum structure and the property of correlation functions is the key to resolve long standing issues in High Temperature QCD. We further argue that there is a precise correspondence between Conformal QCD and High Temperature QCD in the temporal propagators under the change of the parameters N_f and T/T_c respectively: the one boundary is close to meson states and the other is close to free quark states. In particular, we find the correspondence between Conformal QCD with N_f = 7 and High Temperature QCD with N_f=2 at T～2, T_c being in close relation to a meson unparticle model. From this we estimate the anomalous mass dimension γ* = 1.2 (1) for N_f=7.
Shion Chen, University of Tokyo
コライダー実験における崩壊粒子の運動量エンタング ルメントを用いたベル不 等式検証
Seminar Room, Kenkyu Honkan 3F ベルの不等式は 2 粒子間の相関について、古典論が満たすべき上限を与える式である。量子論の下では、 エンタングル状態など特定の条件下で不等式が破れることが知られており、いわば古典論と量子論の判別式のようなものである。これまで既に多数の光学実験において破れが報告され、量子論の「勝利」はほぼ確定したが、フェルミオンや質量のある粒子系での実験例は依然として少ない。しかし量子力学の普遍性検証という観点において、また一般に重い粒子は古典性が強いという点で、これらの系での検証は非常に興味深い。また、未だよく理解されてない量子力学の非局所性などの性質を探る上でも重要である。
