14484648
A possible disk mechanism for the 23-day QPO in Mkn 501
Optically, thin two-temperature accretion flows may be thermally and viscously stable, but acoustically unstable. Here, we propose that the O-mode instability of a cooling-dominated optically thin two-temperature inner disk may explain the 23-day quasi-periodic oscillation (QPO) period observed in the TeV and X-ray light curves of Mkn 501 during its 1997 high state. In our model the relativistic jet electrons Compton upscatter the disk soft X-ray photons to TeV energies, so that the instability-driven X-ray periodicity will lead to a corresponding quasi-periodicity in the TeV light curve and produce correlated variability. We analyse the dependence of the instability-driven quasi-periodicity on the mass ( M ) of the central black hole, the accretion rate ( M ˙ ) and the viscous parameter ( α ) of the inner disk. We show that in the case of Mkn 501 the first two parameters are constrained by various observational results, so that for the instability occurring within a two-temperature disk where α  = 0.05–1.0, the quasi-period is expected to lie within the range of 8–100 days, as indeed the case. In particular, for the observed 23-day QPO period our model implies a viscosity coefficient α  ⩽ 0.28, a sub-Eddington accretion rate M ˙ ≃ 0.02 M ˙ Edd and a transition radius to the outer standard disk of r 0  ∼ 60 r g , and predicts a period variation δ P / P  ∼ 0.23 due to the motion of the instability region.
18317704
Measurement of Tau branching ratios
Using the data accumulated at LEP in 1989 and 1990 with the ALEPH detector, the inclusive and exclusive branching ratios of the τ lepton have been measured assuming lepton universality inZ0 decays. The inclusive branching fractions for the τ decay into one, three, and five charged particles have been determined to be (85.45±0.97)%, (14.35±0.48)%, and (0.10±0.05)%, respectively, in agreement with the world averages. New undetected decay modes are determined to have a branching fraction of less than 2.1% at 95% CL. The measured branching ratios for quasi-exclusive channels are slightly larger than, but consistent with the world averages, except for the modes τ→3 hadrons+vτ andτ→hadron+2π0vτ, which are significantly larger. These latter branching ratios have been found to be (9.5±0.7)% and (10.2±1.1)%, respectively. The sum of all the measured quasi-exclusive branching ratios is (100.4±1.8)%. A fully exclusive analysis of modes with neutral pions shows no evidence for new photonic decay modes with a branching fraction limit of 3.4% at 95% CL.
120548922
EXPERIMENTAL LIMITS ON THE PRODUCTION OF EXCITED LEPTONS AND STABLE HEAVY-LEPTONS
The results are reported of a search for excited muons (..mu..*) and electrons (e*) and for a stable charged heavy lepton by measurements of the e/sup +/e/sup -/..--> mu../sup +/..mu../sup -/, ..mu../sup +/..mu../sup -/..gamma.., ..mu../sup +/..mu../sup -/..gamma gamma.., and ..gamma gamma.. final states. Excluded are large regions of the lambda (coupling constant), M (mass) planes for spin-(1/2) ..mu..* and e*, and a new stable charged heavy lepton with mass<14 GeV.
123029043
Evidence of soft and collinear gluon emission ine+e− hadronic events
In the study of rapidity distributions of charged pions produced ine+e− annihilation at 29 GeV, we observe a significant dip in the rapidity distributions aty≈0 for events with low sphericity. A comparison of data with several QCD-based phenomenological models strongly suggests that this structure is related to the emission of multiple soft and/or collinear gluons.
140089864
Critical current, electro-mechanical properties and specific heat of bronze Nb-3_Sn conductors
125293645
EXPERIMENTAL STUDY OF HEAVY CHARGED LEPTONS AT PETRA
16037890
Supersymmetric black rings and non-linear sigma models
In this paper we investigate the non-linear sigma model arising in the reduction of D=5 supergravity to D=3, and present the application of this sigma model to supersymmetric black ring solutions in five-dimensional minimal supergravity. With the ansatz of stationary solutions with R×U(1)×U(1) isometry, we obtain a two-dimensional Lagrangian corresponding to geodesic motion of a string-like object on the coset G2(+2)/SO(4), and study the algebra of conserved charges and supersymmetry constraints of supersymmetric black ring.
12040637
Is the energy generation rate of nuclear reactions in hot accretion flows important
The temperature of hot accretion flows around black holes is sufficiently high for the ignition of nuclear reactions. This is potentially an important nucleosynthesis mechanism in the universe. As the first step in studying this problem, we need to measure physical quantities such as density and temperature of the accretion flow. In usual studies of the hot accretion flow, viscous dissipation is considered to be the only heating mechanism, while the heating caused by nuclear reactions is not considered. In this paper, we investigate whether the energy generation rate of nuclear reaction is important compared to the viscous heating. Our calculation indicates that the former is at most one percent of the latter and thus is not important. The dynamics of accretion flow can be therefore calculated in the usual way, without the need to consider heating due to nuclear reactions.
122974986
A GEANT4-based simulation model for the BESIII endcap time-of-flight system
A GEANT4-based full Monte-Carlo model is developed to simulate the performance of the endcap time-of-flight (TOF) system of the BESIII detector with high accuracy and sufficient speed. Experimental data of e(+)e(-) collisions collected at BESIII are used to test this model, which can also be applied to other cases for precisely simulating optical photons propagating in scintillators with an irregular geometry. (C) 2010 Elsevier B.V. All rights reserved.
118651701
STRONG FIELD EFFECTS ON EMISSION LINE PROFILES: KERR BLACK HOLES AND WARPED ACCRETION DISKS
If an accretion disk around a black hole is illuminated by hard X-rays from non-thermal coronae, fluorescent iron lines will be emitted from the inner region of the accretion disk. The emission line profiles will show a variety of strong field effects, which may be used as a probe of the spin parameter of the black hole and the structure of the accretion disk. In this paper, we generalize the previous relativistic line profile models by including both the black hole spinning effects and the non-axisymmetries of warped accretion disks. Our results show different features from the conventional calculations for either a flat disk around a Kerr black hole or a warped disk around a Schwarzschild black hole by presenting, at the same time, multiple peaks, rather long red tails, and time variations of line profiles with the precession of the disk. We show disk images as seen by a distant observer, which are distorted by the strong gravity. Although we are primarily concerned with the iron K-shell lines in this paper, the calculation is general and is valid for any emission lines produced from a warped accretion disk around a black hole.
119158957
DISTRIBUTION OF SATELLITE GALAXIES IN HIGH-REDSHIFT GROUPS
We use galaxy groups at redshifts between 0.4 and 1.0 selected from the Great Observatories Origins Deep Survey to study the color-morphological properties of satellite galaxies and investigate possible alignment between the distribution of the satellites and the orientation of their central galaxy. We confirm the bimodal color and morphological-type distribution for satellite galaxies at this redshift range: the red and blue classes correspond to the early and late morphological types, respectively, and the early-type satellites are on average brighter than the late-type ones. Furthermore, there is a morphological conformity between the central and satellite galaxies: the fraction of early-type satellites in groups with an early-type central is higher than those with a late-type central galaxy. This effect is stronger at smaller separations from the central galaxy. We find a marginally significant signal of alignment between the major axis of the early-type central galaxy and its satellite system, while for the late-type centrals no significant alignment signal is found. We discuss the alignment signal in the context of shape evolution of groups.