A Polar-Nulceus Dark Lane in the Barred Spiral M83: Three-Dimensional Accretion in the Nucleus

The central region of the barred spiral galaxy M83 reveals a polar-nucleus dust lane, wh ich extends from the NE molecular bar and crosses the central bulge. Its SW counterpart is not visible, being hidden behind the bulge. This asymmetry, in spite of the galaxy's face-on orientation and the symmetric bar struct ure in the CO-line emission, indicates that the dark lane is an off-plane structure. Such a ``polar-nucleus'' structure can be formed by a non-coplanar, three-dimensional acc retion in a warped disk.Comment: (to appear in AJ), 5 pages, plainTeX, U-Tokyo Astro. No.93-2

Pi N sigma-term and chiral-odd twist-3 distribution function e(x) of the nucleon in the chiral quark soliton model

The isosinglet combination of the chiral-odd twist-3 distribution function $e^u(x)+e^d(x)$ of the nucleon has outstanding properties that its first moment is proportional to the well-known $\pi N$ sigma-term and that it contains a $\delta$-function singularity at $x=0$. These two features are inseparably connected in that the above sum rule would be violated, if there is no such a singularity in $e^u(x)+e^d(x)$. Very recently, we found that the physical origin of this $\delta$-function singularity can be traced back to the long-range quark-quark correlation of scalar type, which signals the spontaneous chiral symmetry breaking of the QCD vacuum. The main purpose of the present paper is to give complete theoretical predictions for the chiral-odd twist-3 distribution function $e^a(x)$ of each flavor $a$ on the basis of the chiral quark soliton model, without recourse to the derivative expansion type approximation. These theoretical predictions are then compared with the empirical information extracted from the CLAS data of the semi-inclusive DIS processes by assuming the Collins mechanism only. A good agreement with the CLAS data is indicative of a sizable violation of the $\pi N$ sigma-term sum rule, or equivalently, the existence of a $\delta$-function singularity in $e^u(x) + e^d(x)$.Comment: 35 pages, 10 figure

Generalized form factors, generalized parton distributions and the spin contents of the nucleon

With a special intention of clarifying the underlying spin contents of the nucleon, we investigate the generalized form factors of the nucleon, which are defined as the $n$-th $x$-moments of the generalized parton distribution functions, within the framework of the chiral quark soliton model. A particular emphasis is put on the pion mass dependence of final predictions, which we shall compare with the predictions of lattice QCD simulations carried out in the so-called heavy pion region around $m_\pi \simeq (700 \sim 900) {MeV}$. We find that some observables are very sensitive to the variation of the pion mass. It will be argued that the negligible importance of the quark orbital angular momentum indicated by the LHPC and QCDSF lattice collaborations might be true in the unrealistic heavy pion world, but it is not necessarily the case in our real world close to the chiral limit.Comment: Final version accepted for publication in Phys. Rev.

CO Observations of Luminous IR Galaxies at Intermediate Redshift

We present new measurement of $^{12}$CO($J=1-0$) emission from 16 luminous infrared galaxies (LIGs) at intermediate redshift ($cz \sim 10,000 - 50,000 {\rm km s^{-1}}$). These new data were selected by isolated and normal morphology. The CO observations were performed using the NRO 45-m telescope. Comparison of the CO and dust properties of the new result with those from other CO measurements revealed characteristics of this sample: (1) It is the deepest CO observations of IRAS galaxies at intermediate redshift without strong interaction features. (2) It has typical properties of normal IRAS galaxies in terms of star-formation efficiency, color-color diagrams and galactic nuclear activity. (3) It has smaller gas-to-dust ratio than normal IRAS galaxies. This can be explained by two-component dust model, and our sample consists of most of warm dust.Comment: To appear in PASJ, text 9 pages, 5 tables, and 12 figure

The nonperturbative origin of delta-function singularity in the chirally-odd twist-3 distribution function e(x)

We analytically prove that the existence of the delta-function singularity in the chirally-odd twist-3 distribution $e(x)$ of the nucleon is inseparably connected with the nonvanishing quark condensate as a signal of the spontaneous chiral symmetry breaking of the QCD vacuum. This singularity in $e(x)$, which would be observed as a sizable violation of the 1st moment sum rule, is then interpreted as giving a very rare case that the nontrivial vacuum structure of QCD manifests in an observable of a localized QCD excitation, i.e. the nucleon.Comment: 9 pages, 1 eps-figur

Distance Measurement of Galaxies to Redshift of 0.1 using the CO-Line Tully-Fisher Relation

We report on the first results of a long-term project to derive distances of galaxies at cosmological distances by applying the CO-line width-luminosity relation. We have obtained deep CO-line observations of galaxies at redshifts up to 29,000 km/s using the Nobeyama 45-m mm-wave Telescope, and some supplementary data were obtained by using the IRAM 30-m telescope. We have detected the CO line emission for several galaxies, and used their CO line widths to estimate the absolute luminosities using the line-width-luminosity relation. In order to obtain photometric data and inclination correction, we also performed optical imaging observations of the CO-detected galaxies using the CFHT 3.6-m telescope at high resolution. The radio and optical data have been combined to derive the distance moduli and distances of the galaxies, and Hubble ratios were estimated for these galaxies. We propose that the CO line width-luminosity relation can be a powerful method to derive distances of galaxies to redfhift of z = 0.1 and to derive the Hubble ratio in a significant volume of the universe. Key words: Cosmology - Galaxies: general - Distance scale - CO lineComment: To appear in PASJ, Plain Tex, 3 figures (in 10 ps files

On the physics behind the form factor ratio μpGEp(Q2)/GMp(Q2)\mu_p G_E^p (Q^2) / G_M^p (Q^2)

We point out that there exist two natural definitions of the nucleon magnetization densities : the density $\rho_M^K (r)$ introduced in Kelly's phenomenological analysis and theoretically more standard one $\rho_M (r)$. We can derive an explicit analytical relation between them, although Kelly's density is more useful to disentangle the physical origin of the different $Q^2$ dependence of the Sachs electric and magnetic form factors of the nucleon. We evaluate both of $\rho_M (r)$ and $\rho_M^K (r)$ as well as the charge density $\rho_{ch}(r)$ of the proton within the framework of the chiral quark soliton model, to find a noticeable qualitative difference between $\rho_{ch}(r)$ and $\rho_M^K (r)$, which is just consistent with Kelly's result obtained from the empirical information on the Sachs electric and magnetic form factors of the proton.Comment: 12 pages, 5 figures. version to appear in J. Phys. G.: Nucl. Part. Phy