Articles

06/17/2001-- 06/17/2001

The [O III]4363 Emitting Region Obscured by Dusty Tori

The emission-line flux ratio of [O III]4363/[O III]5007 is a useful diagnostic for the ionization mechanism and physical properties of narrow-line regions in active galactic nuclei. However, it is known that simple photoionization models underpredict this ratio. In this contribution, we report on some pieces of evidence that a large fraction of the [O III]4363 emission arises from the dense gas, which can be obscured by dusty tori. Taking this dense component into account, we show that the flux ratio of [O III]4363/[O III]5007 can be explained by two-component photoionization models.
Tohru Nagao Takashi Murayama Yoshiaki Taniguchi
12/13/2012-- 11/30/2012

Correspondence between future-included and future-not-included theories

We briefly review the correspondence principle proposed in our previous paper, which claims that if we regard a matrix element defined in terms of the future state at time $T_B$ and the past state at time $T_A$ as an expectation value in the complex action theory whose path runs over not only past but also future, the expectation value at the present time $t$ of a future-included theory for large $T_B-t$ and large $t-T_A$ corresponds to that of a future-not-included theory with a proper inner product for large $t-T_A$. This correspondence principle suggests that the future-included theory is not excluded phenomenologically.
Keiichi Nagao Holger Bech Nielsen
04/28/2023-- 04/15/2022

A model explaining the new CDF II W boson mass linking to muon $g-2$ and dark matter

We propose a model to explain the W boson mass anomaly reported by the CDFII collaboration that would suggest new physics (NP). We introduce exotic fermions; one isospin doublet vector-like lepton, one isospin singlet singly-charged vector-like lepton, and an isospin doublet inert scalar. The proposed model provides sizable muon anomalous magnetic moment (muon $g-2$) due to no chiral suppression and nonzero mass difference between the real and imaginary parts of neutral inert scalar bosons. The inert scalar mass squared difference and vector-like exotic leptons ($L', E'$ in the main text) affect oblique parameters. Especially, the $T$-parameter shift from zero explains the W boson mass anomaly. We search for the allowed parameter region to explain both muon $g-2$ and W boson mass anomaly at the same time. We also discuss a dark matter (DM) candidate assuming the real part of the inert scalar field to be the one. We find that lighter DM mass is favored to be consistent with experimental constraints.
Keiko I. Nagao Takaaki Nomura Hiroshi Okada
05/23/2012-- 05/23/2012

Near-infrared spectroscopy of a nitrogen-loud quasar SDSS J1707+6443

We present near-infrared spectroscopy of the z=3.2 quasar SDSS J1707+6443, obtained with MOIRCS on the Subaru Telescope. This quasar is classified as a "nitrogen-loud" quasar because of the fairly strong NIII] and NIV] semi-forbidden emission lines from the broad-line region (BLR) observed in its rest-frame UV spectrum. However, our rest-frame optical spectrum from MOIRCS shows strong [OIII] emission from the narrow-line region (NLR) suggesting that, at variance with the BLR, NLR gas is not metal-rich. In order to reconcile these contradictory results, there may be two alternative possibilities; (1) the strong nitrogen lines from the BLR are simply due to a very high relative abundance of nitrogen rather than to a very high BLR metallicity, or (2) the BLR metallicity is not representative of the metallicity of the host galaxy, better traced by the NLR. In either case, the strong broad nitrogen lines in the UV spectrum are not indication of a chemically enriched host galaxy. We estimated the black hole mass and Eddington ratio of this quasar from the velocity width of both CIV and H_beta, that results in log(M_BH/M_sun) = 9.50 and log(L_bol/L_Edd) = -0.34. The relatively high Eddington ratio is consistent with our earlier result that strong nitrogen emission from BLRs is associated with high Eddington ratios. Finally, we detected significant [NeIII] emission from the NLR, implying a quite high gas density of n~10^6 cm^-3 and suggesting a strong coupling between quasar activity and dense interstellar clouds in the host galaxy.
N. Araki T. Nagao K. Matsuoka A. Marconi R. Maiolino H. Ikeda T. Hashimoto Y. Taniguchi T. Murayama
06/14/2001-- 06/14/2001

Spontaneous vortex phase in ErNi2B2C

Below T_{WFM} ~ 2.75K, a weak ferromagnetism and superconductivity coexist in ErNi2B2C. In the present paper, a possibility of a spontaneous vortex phase was examined directly by small angle neutron scattering technique. An external magnetic field was applied to align ferromagnetic domains so that the internal magnetic field induced by the weak ferromagnetism becomes uniform and uniaxial over the bulk sample. When the field is removed, the flux line lattice subsisted below T_{WFM} but disappeared above it. A pinning effect is also discussed. We conclude that the spontaneous vortex state is realized in ErNi2B2C.
H. Kawano-Furukawa E. Habuta T. Nagata M. Nagao H. Yoshizawa N. Furukawa H. Takeya K. Kadowaki
05/09/2000-- 05/09/2000

Massive random matrix ensembles at beta = 1 & 4 : QCD in three dimensions

The zero momentum sectors in effective theories of three dimensional QCD coupled to pseudoreal (two colors) and real (adjoint) quarks in a classically parity-invariant manner have alternative descriptions in terms of orthogonal and symplectic ensembles of random matrices. Using this correspondence, we compute finite-volume QCD partition functions and correlation functions of Dirac operator eigenvalues in a presence of finite quark masses of the order of the smallest Dirac eigenvalue. These novel correlation functions, expressed in terms of quaternion determinants, are reduced to conventional results for the Gaussian ensembles in the quenched limit.
T. Nagao S. M. Nishigaki
02/18/2004-- 02/18/2004

Commensurators of some non-uniform tree lattices and Moufang twin trees

Sh. Mozes showed that the commensurator of the lattice ${\rm PSL}_2 \bigl({\bf F}_p[t{}^{-1}] \bigr)$ is dense in the full automorphism group of the Bruhat-Tits tree of valency $p+1$, the latter group being much bigger than ${\rm PSL}_2 \bigl({\bf F}_p((t)) \bigr)$. By G.A. Margulis' criterion, this density is a generalized arithmeticity result. We show that the density of the commensurator holds for many tree-lattices among those called of Nagao type by H. Bass and A. Lubotzky. The result covers many lattices obtained via Moufang twin trees.
Peter Abramenko Bertrand Remy
02/15/2021-- 04/16/2020

Framed motivic Donaldson-Thomas invariants of small crepant resolutions

For an arbitrary integer $r\geq 1$, we compute $r$-framed motivic PT and DT invariants of small crepant resolutions of toric Calabi-Yau $3$-folds, establishing a "higher rank" version of the motivic DT/PT wall-crossing formula. This generalises the work of Morrison and Nagao. Our formulae, in particular their relationship with the $r=1$ theory, fit nicely in the current development of higher rank refined DT invariants.
Alberto Cazzaniga Andrea T. Ricolfi
06/23/2019-- 01/22/2019

Exact large deviation function of spin current for the one dimensional XX spin chain with domain wall initial condition

We investigate the fluctuations of the spin current for the one dimensional XX spin chain starting from the domain wall initial condition. The generating function of the current is shown to be written as a determinant with the Bessel kernel. An exact analytical expression for the large deviation function is obtained by applying the Coulomb gas method. Our results are also compared with DMRG calculations.
H. Moriya R. Nagao T. Sasamoto
03/25/2016-- 03/25/2016

Extinction Laws toward Stellar Sources within a Dusty Circimstellar Medium and Implications for Type Ia Supernovae

Many astronomical objects are surrounded by dusty environments. In such dusty objects, multiple scattering processes of photons by circumstellar (CS) dust grains can effectively alter extinction properties. In this paper, we systematically investigate effects of multiple scattering on extinction laws for steady-emission sources surrounded by the dusty CS medium, using a radiation transfer simulation based on the Monte Carlo technique. In particular, we focus on whether and how the extinction properties are affected by properties of CS dust grains, adopting various dust grain models. We {\bf confirm} that behaviors of the (effective) extinction laws are highly dependent on the properties of CS grains. Especially, the total-to-selective extinction ratio $R_{V}$, which characterizes the extinction law, can be either increased or decreased, compared to the case without multiple scattering. We find that the criterion for this behavior is given by a ratio of albedos in the $B$ and $V$ bands. We also find that either small silicate grains or polycyclic aromatic hydrocarbons (PAHs) are necessary for realizing a low value of $R_{V}$ as often measured toward Type Ia supernovae, if the multiple scattering by CS dust is responsible for their non-standard extinction laws. Using the derived relations between the properties of dust grains and the resulting effective extinction laws, we propose that the extinction laws toward dusty objects could be used to constrain the properties of dust grains in CS environments.
T. Nagao K. Maeda T. Nozawa


with thanks to arxiv.org/