Anna Hasenfratz, University of Colorado Boulder
Strongly coupled gauge theories in and out of the conformal window
Meeting room1, Kenkyu honkan 1F
Asymptotically free gauge systems with many fermionic degrees of freedom can develop a conformal infrared fixed point. Near the conformal window these strongly coupled systems can have unusual properties, and might contain a light scalar, a composite candidate for the Higgs boson. Lattice studies are particularly suited to study these strongly coupled models, though methods developed for QCD studies are not always effective. In this talk I will give a brief overview of our understanding of these systems. I will concentrate on two rather different methods, the Dirac operator spectral density, and a variant of finite size scaling, to illustrate the unusual properties of these intriguing systems.
Yoshimasa Hidaka, RIKEN
Generalization of the Nambu-Goldstone theorem
Seminar room, Kenkyu honkan 3F
Symmetry and its spontaneous breaking are of basic importance for understanding the low energy physics in many-body systems. When a continuum symmetry is spontaneously broken, there exist a zero mode called Nambu-Goldstone (NG) mode, which is well developed in Lorentz invariant systems. In contrast, in non-Lorentz invariant systems, the NG theorem has not been well developed. In this talk, we discuss the recent progress in generalization of NG theorem, and discuss the counting rule for NG modes using the Langevin equation derived from Mori’s projection operator method. We show that the number of NG modes is equal to the number of broken charges, Qa, minus half the rank of the expectation value of [Qa,Qb]. We also discuss the spontaneous breaking of space-time symmetries.
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
