Experimental Implications on Neutrino Cross-Sections Around 1 GeV

title: Measurement of triple gauge-boson couplings at 172 GeV
abstract: The triple gauge-boson couplings, αWΦ, αW and αBΦ, have been measured using 34 semileptonically and 54 hadronically decaying W+W− candidate events. The events were selected in the data recorded during 1996 with the ALEPH detector at 172 GeV, corresponding to an integrated luminosity of 10.65 pb−1. The triple gauge-boson couplings have been measured using optimal observables constructed from kinematic information of W+W− events. The results are in agreement with the Standard Model expectation.

title: Mass limit for the lightest neutralino
abstract: AbstractIndirect limits on the mass of the lightest neutralino are derived from the results of searches for charginos, neutralinos, and sleptons performed with data taken by the ALEPH Collaboration at centre-of-mass energies near the Z peak and at 130 and 136 GeV. Within the context of the Minimal Supersymmetric Standard Model and when
$$M_{\tilde \nu } \geqslant 200 GeV/c^2 $$
, the boundMx> 12.8 GeV/c2 at the 95% confidence level applies for any tanβ. The impact of lighter sneutrinos is presented in the framework of SUSY grand unified theories; a massless neutralino is allowed only for a narrow range of tanβ,μ, and the scalar mass parameterm0. Finally, by including Higgs mass constraints and requiring that radiative electroweak symmetry breaking occur, more stringent bounds onMx as a function of tanβ are derived.

title: Architecture of the HERA-B data acquisition system
abstract: The HERA-B experiment was dedicated for the measurement of CP-violation in decays of neutral B-mesons and for investigating the physics of charmed particles. One of the experimental requirements is a highly selective on-line filtering of data due to high interaction rates and a low signal-to-background ratio. This demands a hierarchical trigger and a high bandwidth data acquisition system. The challenge for the DAQ system is a readout free of deadtime, which requires an unprecedent speed of storing and processing the data. In this paper we will outline the general architecture and hardware implementation of the HERA-B DAQ.

title: Search for neutrino-induced charged current coherent pion production with carbon in a 1.3 GeV wide band muon neutrino beam
abstract: The search for charged-current coherent pion production induced by neutrinos with a mean energy of 1.3 GeV is discussed. The data are collected with a fully active scintillator detector in the K2K long-baseline neutrino oscillation experiment. No evidence for coherent pion production is observed and an upper limit of 0.60 × 10−2 is set on the cross section ratio of coherent pion production to the total charged current interaction at the 90% confidence level.

title: Improved measurement of the $\bar{B}^0$ and $B^{-}$ meson lifetimes

title: MOLECULAR GAS STREAMERS FEEDING AND OBSCURING THE ACTIVE NUCLEUS OF NGC 1068
abstract: We report the first direct observations of neutral, molecular gas streaming in the nucleus of NGC 1068 on scales of <30 pc using SINFONI near-infrared integral field spectroscopy. At a resolution of 0075, the flux map of 2.12 μm 1-0 S(1) molecular hydrogen emission around the nucleus in the central arcsec reveals two prominent linear structures leading to the active galactic nucleus from the north and south. The kinematics of the gas in these features are dominated by noncircular motions and indicate that material streams toward the nucleus on highly elliptical or parabolic trajectories, whose orientations are compatible with that of the disk plane of the galaxy. We interpret the data as evidence for fueling of gas to the central region. The radial transport rate from ~30 pc to a few parsecs from the nucleus is ~15 M ☉ yr–1. One of the infalling clouds lies directly in front of the central engine. We interpret it as a tidally disrupted streamer that forms the optically thick outer part of an amorphous clumpy molecular/dusty structure which contributes to the nuclear obscuration.

title: SINFONI’s take on Star Formation, Molecular Gas, and Black Hole Masses in AGN
abstract: We present some preliminary (half-way) results on our adaptive optics spectroscopic survey of AGN at spatial scales down to 0.085”. Most of the data were obtained with SINFONI which provides integral field capability at a spectral resolution of R ∼ 4000. The themes on which we focus in this contribution are: star formation around the AGN, the properties of the molecular gas and its relation to the torus, and the mass of the black hole.

title: SINFONI adaptive optics integral field spectroscopy of the Circinus Galaxy
abstract: We investigate the star formation activity and the gas and stellar dynamics on scales of a few parsecs in the nucleus of the Circinus Galaxy.  Using the adaptive optics near infrared integral field spectrometer SINFONI on the VLT, we have obtained observations of the Circinus galaxy on scales of a few parsecs and at a spectral resolution of 70 km s −1 FWHM. The physical properties of the nucleus are analyzed by means of line and velocity maps extracted from the SINFONI datacube. Starburst models are constrained using the Brγ flux, stellar continuum (as traced via the CO absorption bandheads longward of 2.3 µm), and radio continuum.  The similarity of the morphologies of the H2 1−0S (1) 2.12 µ ma nd Brγ 2.17 µm lines to the stellar continuum and also their kinematics, suggest a common origin in star formation. Within 8 pc of the AGN we find there has been a recent starburst in the last 100 Myr, which currently accounts for 1.4% of the galaxy’s bolometric luminosity. The similarity of the spatial scales over which the stars and gas exist indicates that this star formation is occuring within the torus; and comparison of the gas column density through the torus to the maximum possible optical depth to the stars implies the torus is a clumpy medium. The coronal lines show asymmetric profiles with a spatially compact narrow component and a spatially extended blue wing. These characteristics are consistent with some of the emission arising in clouds gravitationally bound to the AGN, and some outflowing in cloudlets which have been eroded away from the bound clouds.

title: Ultrahigh Energy Neutrinos at the Pierre Auger Observatory
abstract: The observation of ultrahigh energy neutrinos (UHE nu s) has become a priority in experimental astroparticle physics. UHE nu s can be detected with a variety of techniques. In particular, neutrinos can interact in the atmosphere (downward-going nu) or in the Earth crust (Earth-skimming nu), producing air showers that can be observed with arrays of detectors at the ground. With the surface detector array of the Pierre Auger Observatory we can detect these types of cascades. The distinguishing signature for neutrino events is the presence of very inclined showers produced close to the ground (i.e., after having traversed a large amount of atmosphere). In this work we review the procedure and criteria established to search for UHE nu s in the data collected with the ground array of the Pierre Auger Observatory. This includes Earth-skimming as well as downward-going neutrinos. No neutrino candidates have been found, which allows us to place competitive limits to the diffuse flux of UHE nu s in the EeV range and above.

title: A close look at star formation around active galactic nuclei
abstract: We analyze star formation in the nuclei of nine Seyfert galaxies at spatial resolutions down to 0.085'', corresponding to length scales of order 10 pc in most objects. Our data were taken mostly with the near-infrared adaptive optics integral field spectrograph SINFONI. The stellar light profiles typically have size scales of a few tens of parsecs. In two cases there is unambiguous kinematic evidence for stellar disks on these scales. In the nuclear regions there appear to have been recent, but no longer active, starbursts in the last 10-300 Myr. The stellar luminosity is less than a few percent of the AGN in the central 10 pc, whereas on kiloparsec scales the luminosities are comparable. The surface stellar luminosity density follows a similar trend in all the objects, increasing steadily at smaller radii up to ~1013 L☉ kpc−2 in the central few parsecs, where the mass surface density exceeds 104 M☉ pc−2. The intense starbursts were probably Eddington limited and hence inevitably short lived, implying that the starbursts occur in multiple short bursts. The data hint at a delay of 50-100 Myr between the onset of star formation and subsequent fueling of the black hole. We discuss whether this may be a consequence of the role that stellar ejecta could play in fueling the black hole. While a significant mass is ejected by OB winds and supernovae, their high velocity means that very little of it can be accreted. On the other hand, winds from AGB stars ultimately dominate the total mass loss, and they can also be accreted very efficiently because of their slow speeds.