Heavy Quarkonium Potential Model and the 1P1{}^1P_1 State of Charmonium

A theoretical explanation of the observed splittings among the P~states of charmonium is given with the use of a nonsingular potential model for heavy quarkonia. We also show that the recently observed mass difference between the center of gravity of the ${}^3P_J$ states and the ${}^1P_1$ state of $c\bar{c}$ does not provide a direct test of the color hyperfine interaction in heavy quarkonia. Our theoretical value for the mass of the ${}^1P_1$ state is in agreement with the experimental result, and its E1 transition width is 341.8~keV. The mass of the $\eta_c'$ state is predicted to be 3622.3~MeV.Comment: 15 page REVTEX documen

21-cm absorption from galaxies at z ~ 0.3

We report the detection of 21-cm absorption from foreground galaxies towards quasars, specifically z_gal = 0.3120 towards SDSS J084957.97+510829.0 (z_qso = 0.584; Pair-I) and z_gal = 0.3714 towards SDSS J144304.53+021419.3 (z_qso = 1.82; Pair-II). In both the cases, the integrated 21-cm optical depth is consistent with the absorbing gas being a damped Lyman-\alpha (DLA) system. In the case of Pair-I, strong Na I and Ca II absorption are also detected at z_gal in the QSO spectrum. We identify an early-type galaxy at an impact parameter of b ~ 14 kpc whose photometric redshift is consistent with that of the detected metal and 21-cm absorption lines. This would be the first example of an early-type galaxy associated with an intervening 21-cm absorber. The gas detected in 21-cm and metal absorption lines in the outskirts of this luminous red galaxy could be associated with the reservoir of cold H I gas with a low level of star formation activity in the outer regions of the galaxy as reported in the literature for z ~ 0.1 early-type galaxies. In the case of Pair-II, the absorption is associated with a low surface brightness galaxy that, unlike most other known quasar-galaxy pairs (QGPs) i.e. QSO sight lines passing through disks/halos of foreground galaxies, is identified only via narrow optical emission lines detected on top of the QSO spectra. Using SDSS spectra we infer that the emission lines originate within ~ 5 kpc of the QSO sight line, and the gas has metallicity [12+O/H] ~ 8.4 and star formation rate ~ 0.7-0.8 M_sun per yr. The measured 21-cm optical depth can be reconciled with the N(H I) we derive from the measured extinction (A_V=0.6) if either the H I gas is warm or the extinction per hydrogen atom in this galaxy is much higher than the mean value of the Small Magellanic Cloud. (Abridged)Comment: 8 pages, 7 figures, 3 tables (A&A in press

Quantum-Chromodynamic Potential Model for Light-Heavy Quarkonia and the Heavy Quark Effective Theory

We have investigated the spectra of light-heavy quarkonia with the use of a quantum-chromodynamic potential model which is similar to that used earlier for the heavy quarkonia. An essential feature of our treatment is the inclusion of the one-loop radiative corrections to the quark-antiquark potential, which contribute significantly to the spin-splittings among the quarkonium energy levels. Unlike $c\bar{c}$ and $b\bar{b}$, the potential for a light-heavy system has a complicated dependence on the light and heavy quark masses $m$ and $M$, and it contains a spin-orbit mixing term. We have obtained excellent results for the observed energy levels of $D^0$, $D_s$, $B^0$, and $B_s$, and we are able to provide predicted results for many unobserved energy levels. Our potential parameters for different quarkonia satisfy the constraints of quantum chromodynamics. We have also used our investigation to test the accuracy of the heavy quark effective theory. We find that the heavy quark expansion yields generally good results for the $B^0$ and $B_s$ energy levels provided that $M^{-1}$ and $M^{-1}\ln M$ corrections are taken into account in the quark-antiquark interactions. It does not, however, provide equally good results for the energy levels of $D^0$ and $D_s$, which indicates that the effective theory can be applied more accurately to the $b$ quark than the $c$ quark.Comment: 17 pages of LaTeX. To appear in Physical Review D. Complete PostScript file is available via WWW at http://gluon.physics.wayne.edu/wsuhep/jim/heavy.p

Geochemistry of K/T boundaries in India and contributions of Deccan volcanism

Three possible Cretaceous/Tertiary (K/T) boundary sections in the Indian subcontinent were studied for their geochemical and fossil characteristics. These include two marine sections of Meghalaya and Zanskar and one continental section of Nagpur. The Um Sohryngkew river section of Meghalaya shows a high iridium, osmium, iron, cobalt, nickel and chromium concentration in a 1.5 cm thick limonitic layer about 30 cm below the planktonic Cretaceous-Palaeocene boundary identified by the characteristic fossils. The Bottaccione and Contessa sections at Gubbio were also analyzed for these elements. The geochemical pattern at the boundary at the Um Sohryngkew river and Gubbio sections are similar but the peak concentrations and the enrichment factors are different. The biological boundary is not as sharp as the geochemical boundary and the extinction appears to be a prolonged process. The Zanskar section shows, in general, similar concentration of the siderophile, lithophile and rare earth elements but no evidence of enrichment of siderophiles has so far been observed. The Takli section is a shallow inter-trappean deposit within the Deccan province, sandwiched between flow 1 and flow 2. The geochemical stratigraphy of the inter-trappeans is presented. The various horizons of ash, clay and marl show concentration of Fe and Co, generally lower than the adjacent basalts. Two horizons of slight enrichment of iridium are found within the ash layers, one near the contact of flow 1 and other near the contact of flow 2, where iridium occurs at 170 and 260 pg/g. These levels are lower by a factor of 30 compared to Ir concentration in the K/T boundary in Meghalaya section. If the enhanced level of some elements in a few horizons of the ash layer are considered as volcanic contribution by some fractionation processes than the only elements for which it occurs are REE, Ir and possibly Cr

Parsec-scale structures and diffuse bands in a translucent interstellar medium at z 0.079

We present a detailed study of the QSO-galaxy pair [SDSS J163956.35+112758.7 (zq = 0.993) and SDSS J163956.38+112802.1 (zg = 0.079)] based on observations carried out using the Giant Meterwave Radio Telescope (GMRT), the Very Large Baseline Array (VLBA), the Sloan Digital Sky Survey (SDSS) and the ESO New Technology Telescope (NTT). We show that the interstellar medium of the galaxy probed by the QSO line of sight has near-solar metallicity (12+log(O/H) = 8.47+/-0.25) and dust extinction (E(B-V) 0.83+/-0.11) typical of what is usually seen in translucent clouds. We report the detection of absorption in the \lambda 6284 diffuse interstellar band (DIB) with a rest equivalent width of 1.45+/-0.20\AA. Our GMRT spectrum shows a strong 21-cm absorption at the redshift of the galaxy with an integrated optical depth of 15.70+/-0.13 km/s. Follow-up VLBA observations show that the background radio source is resolved into three components with a maximum projected separation of 89 pc at the redshift of the galaxy. One of these components is too weak to provide useful HI 21-cm absorption information. The integrated HI optical depth towards the other two components are higher than that measured in our GMRT spectrum and differ by a factor 2. By comparing the GMRT and VLBA spectra we show the presence of structures in the 21-cm optical depth on parsec scales. We discuss the implications of such structures for the spin-temperature measurements in high-z damped Lyman-alpha systems. The analysis presented here suggests that this QSO-galaxy pair is an ideal target for studying the DIBs and molecular species using future observations in optical and radio wavebands.Comment: 10 pages, 8 figures, 2 tables, accepted for publication in MNRA