124130898
Study of the neutron-rich nucleus Si-36
Excited states of N=22 Si-36, populated in deep-inelastic processes produced by the interaction of a 215 MeV beam of S-36 ions with a Pb-208 target, were studied in the present work. gamma rays from the binary fragments detected using CLARA, an array of 25 Ge Clover detectors, were measured in coincidence with projectile-like fragments detected by PRISMA, a large solid angle magnetic spectrometer. Two new gamma-ray photopeaks at energies of 1442 and 842 keV were observed and tentatively assigned to the 4(+)-> 2(+) and 6(+)-> 4(+) transitions, respectively. The systematics of the level structures of N=22 isotones are presented, and a comparison is made of the behavior of Si, Mg, and S isotopes. The level structure of Si-36 is also compared with the results of sdpf shell model calculations.
3131664
ANOMALOUS SILICATE DUST EMISSION IN THE TYPE 1 LINER NUCLEUS OF M81
We report the detection and successful modeling of the unusual 9.7 μm Si-O stretching silicate emission feature in the type 1 (i.e., face-on) LINER nucleus of M81. Using the Infrared Spectrograph (IRS) instrument on Spitzer, we determine the feature in the central 230 pc of M81 to be in strong emission, with a peak at ~10.5 μm. This feature is strikingly different in character from the absorption feature of the galactic interstellar medium, and from the silicate absorption or weak emission features typical of galaxies with active star formation. We successfully model the high signal-to-noise ratio IRS spectra with porous silicate dust using laboratory-acquired mineral spectra. We find that the most probable fit uses micron-sized, porous grains of amorphous silicate and amorphous carbon. In addition to silicate dust, there is weak polycyclic aromatic hydrocarbon (PAH) emission present (particularly at 11.3 μm, arising from the C-H out-of-plane bending vibration of relatively large PAHs of ~500-1000 C atoms) whose character reflects the low-excitation active galactic nucleus environment, with some evidence that small PAHs of ~100-200 C atoms (responsible for the 7.7 μm C-C stretching band) in the immediate vicinity of the nucleus have been preferentially destroyed. Analysis of the infrared fine structure lines confirms the LINER character of the M81 nucleus. Four of the infrared H_2 rotational lines are detected and fit to an excitation temperature of T ~ 800 K. Spectral maps of the central 230 pc in the [Ne II] 12.8 μm line, the H_2 17 μm line, and the 11.3 μm PAH C-H bending feature reveal arc- or spiral-like structures extending from the core. We also report on epochal photometric and spectroscopic observations of M81, whose nuclear intensity varies in time across the spectrum due to what is thought to be inefficient, sub-Eddington accretion onto its central black hole. We find that, contrary to the implications of earlier photometry, the nucleus has not varied over a period of two years at these infrared wavelengths to a precision of about 1%.
4503009
High-Resolution Imaging of Warm and Dense Molecular Gas in the Nuclear Region of the Luminous Infrared Galaxy NGC 6240
We present ~2'' resolution CO (3-2), HCO+(4-3), and 880 μm continuum images of the luminous infrared galaxy NGC 6240 obtained at the Submillimeter Array. We find that the spatially resolved CO (3-2), HCO + (4-3), and the 880 μm emission peaks between the two nuclear components that are both known to harbor AGNs. Our large velocity gradient (LVG) analysis performed on each velocity channel suggests that the peak of the molecular gas emission traced in our observations is warm (T = 20-100 K), dense (nH2 = 105.0-105.4 cm-3), and moderately optically thin (τ = 0.2-2) in the central 1 kpc. We also find large column densities of ~1023 cm-2. Such extreme conditions are observed over ~300 km s-1 centered around the CO-derived systemic velocity. The derived molecular gas mass from the CO (3-2) emission and a CO-to-H2 conversion factor commonly used for ULIRGs is (6.9 ± 1.7) × 109 M☉, and this is consistent with the mass derived from previous CO (2-1) observations. The gas is highly turbulent in the central kpc (ΔvFWZI ~ 1175 km s-1). Furthermore, possible inflow or outflow activity is suggested from the CO (3-2) velocity distribution. We tentatively state that 3.5 × 108 M☉ of isolated CO (3-2) emission seen west of the northern disk may be associated with outflows from starburst superwinds, but the gas outflow scenario from one of the central AGN is not completely ruled out. Piecing all of the information together, the central region of NGC 6240 harbors 2 AGNs, ~1010 M☉ of molecular gas mass, 5 × 107 M☉ of dust mass, and has possible evidence of inflow and outflow activity.
119397253
Evidence for superdeformation in Dy-149,Dy-150: Onset of the collapse of the Z=66 deformed shell closure?
An experiment has been performed to search for superdeformed (SD) states in Dy-149,Dy-150. While no evidence for discrete superdeformed states has been observed, a superdeformed ridge with a separation of Delta E-gamma=52 keV with a total intensity of 1.8+/-0.5% that of Dy-150 has been observed. An upper limit of 0.8% (0.9%), of the intensity of Dy-150 (Dy-149), is placed for observation of the most intense discrete line states. The relative weakness in the SD population is suggested to be due to a rapid decrease in the depth of the superdeformed minimum, as one moves away from doubly magic Dy-152.
115875551
Cosmological Vacuum Configuration in Superstring Theories with only Three-Space Expanding
Cosmological compactification of superstring theories is studied in the field theory limit, with the quadratic Euler-Gauss-Bonnet term included in the gravitational action. We find a vacuum configuration, which is of the Robertson-Walker parameter k = -1, of three-space scale factor R (t) ~ t and of constant internal-space scale factor (R (t) — const.); otherwise, it is the same as the static Candelas-Horowitz-Stominger-Witten (CHSW) configuration. While the CHSW configuration is unstable, our three-space expanding configuration is stable against time-dependent purturbations in R3 (t) and R6 (t). These results indicate the existence of cosmological models (with the presence of matter) in superstring theories which predict, asymptotically in the limit of infinitely dilute matter, no time variation for the coupling constants in four dimensions.
2081456
Numerical solution for cosmological evolution of Newton's gravitational constant in superstring theories.
By using a computer to solve the ten-dimensional Einstein equations in superstring theories, we find that the present value for the time variation of Newton's gravitational constant is in the range of -1 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}11}$ to -6 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}12}$ ${\mathrm{yr}}^{\ensuremath{-}1}$ in the case of the flat internal potential, which confirms the previous perturbative estimate.
121208627
Subthreshold production of strange hadrons in relativistic heavy ion collisions
We report on preliminary measurements of subthreshold antikaons produced in relativistic heavy ion collisions. Comparison with hadrochemical and transport models show that while the total level of antikaon production may be accounted for, important difficulties remain in describing their momentum and angular distributions.
118829634
Analysis of the X(1835) and related baryonium states with Bethe-Salpeter equation
Abstract.In this article, we study the mass spectrum of the baryon-antibaryon bound states p$ \bar{{p}}$ , $ \Sigma$$ \bar{{\Sigma}}$ , $ \Xi$$ \bar{{\Xi}}$ , $ \Lambda$$ \bar{{\Lambda}}$ , p$ \bar{{N}}$(1440) , $ \Sigma$$ \bar{{\Sigma}}$(1660) , $ \Xi$$ \bar{{\Xi}}^{{\prime}}_{}$ and $ \Lambda$$ \bar{{\Lambda}}$(1600) with the Bethe-Salpeter equation. The numerical results indicate that the p$ \bar{{p}}$ , $ \Sigma$$ \bar{{\Sigma}}$ , $ \Xi$$ \bar{{\Xi}}$ , p$ \bar{{N}}$(1440) , $ \Sigma$$ \bar{{\Sigma}}$(1660) , $ \Xi$$ \bar{{\Xi}}^{{\prime}}_{}$ bound states maybe exist, and the new resonances X(1835) and X(2370) can be tentatively identified as the p$ \bar{{p}}$ and p$ \bar{{N}}$(1440) (or N(1400)$ \bar{{p}}$ bound states, respectively, with some gluon constituents, and the new resonance X(2120) may be a pseudoscalar glueball. On the other hand, the Regge trajectory favors identifying the X(1835) , X(2120) and X(2370) as the excited $ \eta^{{\prime}}_{}$(958) mesons with the radial quantum numbers n = 3 , 4 and 5, respectively.
119138174
On Metaplectic Modular Categories and Their Applications
For non-abelian simple objects in a unitary modular category, the density of their braid group representations, the #P-hard evaluation of their associated link invariants, and the BQP-completeness of their anyonic quantum computing models are closely related. We systematically study such properties of the non-abelian simple objects in the metaplectic modular categories SO(m)2 for an odd integer m ≥ 3. The simple objects with quantum dimensions $${\sqrt{m}}$$m have finite image braid group representations, and their link invariants are classically efficient to evaluate. We also provide classically efficient simulations of their braid group representations. These simulations of the braid group representations can be regarded as qudit generalizations of the Knill–Gottesmann theorem for the qubit case. The simple objects of dimension 2 give us a surprising result: while their braid group representations have finite images and are efficiently simulable classically after a generalized localization, their link invariants are #P-hard to evaluate exactly. We sharpen the #P-hardness by showing that any sufficiently accurate approximation of their associated link invariants is already #P-hard.
15474993
Analysis of the Y(4140) with QCD sum rules
AbstractIn this article, we assume that there exists a scalar 
$D_{s}^{\ast}{\bar{D}}_{s}^{\ast}$ 
molecular state in the J/ψφ invariant mass distribution, and we study its mass using the QCD sum rules. The predictions depend heavily on the two criteria (pole dominance and convergence of the operator product expansion) of the QCD sum rules. The value of the mass is about 
$M_{D_{s}^{\ast}{\bar{D}}_{s}^{\ast}}=(4.43\pm0.16)$
 GeV, which is inconsistent with the experimental data. The 
$D_{s}^{\ast}{\bar{D}}_{s}^{\ast}$ 
is probably a virtual state and is not related to the meson Y(4140). Another possibility, such as a hybrid charmonium, is not excluded.
119069538
Search for gamma-ray emission from four accreting millisecond pulsars with Fermi/LAT
We report our search for -ray emission in the energy range from 100 MeV to 300 GeV from four Accreting Millisecond Pulsars (AMPs), SAX J1808.4 3658, IGR J00291+5934, XTE J1814 338, and XTE J0929 314. The data are from four-year observations carried out by Large Area Telescope (LAT) onboard the Fermi -ray Space Telescope. The AMPs were not detected, and their -ray luminosity upper limits we obtain are 5.1 × 10 33 ergs s −1 for SAX J1808.4 3658, 2.1 × 10 33 ergs s −1 for IGR J00291+5934, 1.2 × 10 34 ergs s −1 for XTE J1814 338, and 2.2 × 10 33 ergs s −1 for XTE J0929 314. We compare our results with -ray irradiation luminosities required for producing optical modulations seen from the companions in the AMPs, which has been suggested by Takata et al. (2012), and our upper limits have excluded -ray emission as the heating source in these systems except XTE J0929 314, the upper limit of which is not deep enough. Our results also do not support the model proposed by Takata et al. (2012) that relatively strong -ray emission could arise from the outer gap of a high-mass neutron star controlled by the photon-photon pair-creation for the AMPs. Two AMPs, SAX J1808.4 3658 and IGR J00291+5934, have the measurements of their spin-down rates, and we derive the upper limits of their -ray conversion efficiencies, which are 57% and 3%, respectively. We discuss the implications to the AMP systems by comparing the efficiency upper limit values with that of 20 -ray millisecond pulsars (MSP) detected by Fermi and the newly discovered transitional MSP binary J1023+0038. Subject headings: pulsars: general – stars: neutron – binaries: close – gamma rays: stars