119516023
Lattice SU(2) gauge-Higgs system in analytic treatment
The phase diagrams of SU(2) gauge-Higgs model with Higgs field of arbitrary length in the fundamental representation in four and five dimension are studied analytically. A method for determining phase transition lines is proposed. All qualitative features of the phase diagram obtained by Monte Carlo simulations are obtained analytically, and the order of phase transitions can be determined definitely.
102331940
Assembly history and structure of galactic cold dark matter haloes
We use the Aquarius simulation series to study the imprint of assembly history on the structure of Galaxy-mass cold dark matter haloes. Our results confirm earlier work regarding the influence of mergers on the mass density profile and the inside-out growth of haloes. The inner regions that contain the visible galaxies are stable since early times and are significantly affected only by major mergers. Particles accreted diffusely or in minor mergers are found predominantly in the outskirts of haloes. Our analysis reveals trends that run counter to current perceptions of hierarchical halo assembly. For example, major mergers (i.e. those with progenitor mass ratios greater than 1:10) contribute little to the total mass growth of a halo, on average less than 20 per cent for our six Aquarius haloes. The bulk is contributed roughly equally by minor mergers and by ‘diffuse’ material which is not resolved into individual objects. This is consistent with modelling based on excursion-set theory which suggests that about half of this diffuse material should not be part of a halo of any scale. The simulations themselves suggest that a significant fraction is not truly diffuse, since it was ejected from earlier haloes by mergers prior to their joining the main system. The Aquarius simulations resolve haloes to much lower mass scales than are expected to retain gas or form stars. Thus, the fraction of diffuse dark matter accreted by haloes represents a lower limit to the fraction of diffuse baryons accreted by galaxies. Our results thus confirm that most of the baryons from which visible galaxies form are accreted diffusely, rather than through mergers, and they suggest that only relatively rare major mergers will affect galaxy structure at later times.
119289331
The Aquarius project: the subhaloes of galactic haloes
We have performed the largest ever particle simulation of a Milky Way sized dark matter halo, and present the most comprehensive convergence study for an individual dark matter halo carried out thus far. We have also simulated a sample of six ultrahighly resolved Milky Way sized haloes, allowing us to estimate the halo-to-halo scatter in substructure statistics. In our largest simulation, we resolve nearly 300 000 gravitationally bound subhaloes within the virialized region of the halo. Simulations of the same object differing in mass resolution by factors of up to 1800 accurately reproduce the largest subhaloes with the same mass, maximum circular velocity and position, and yield good convergence for the abundance and internal properties of dark matter substructures. We detect up to four generations of subhaloes within subhaloes, but contrary to recent claims, we find less substructure in subhaloes than in the main halo when regions of equal mean overdensity are compared. The overall substructure mass fraction is much lower in subhaloes than in the main halo. Extrapolating the main halo's subhalo mass spectrum down to an Earth mass, we predict the mass fraction in substructure to be well below 3 per cent within 100 kpc, and to be below 0.1 per cent within the solar circle. The inner density profiles of subhaloes show no sign of converging to a fixed asymptotic slope and are well fitted by gently curving profiles of Einasto form. The mean concentrations of isolated haloes are accurately described by the fitting formula of Neto et al. down to maximum circular velocities of 1.5 km s(-1), an extrapolation over some five orders of magnitude in mass. However, at equal maximum circular velocity, subhaloes are more concentrated than field haloes, with a characteristic density that is typically similar to 2.6 times larger and increases with decreasing distance from halo centre.
14197201
Alignment between galaxies and large-scale structure
Based on the Sloan Digital Sky Survey DR6 (SDSS) and the Millennium Simulation (MS), we investigate the alignment between galaxies and large-scale structure. For this purpose, we develop two new statistical tools, namely the alignment correlation function and the cos(2θ)-statistic. The former is a two-dimensional extension of the traditional two-point correlation function and the latter is related to the ellipticity correlation function used for cosmic shear measurements. Both are based on the cross correlation between a sample of galaxies with orientations and a reference sample which represents the large-scale structure. We apply the new statistics to the SDSS galaxy catalog. The alignment correlation function reveals an overabundance of reference galaxies along the major axes of red, luminous (L ≥ L ∗ ) galaxies out to projected separations of 60 h - 1 Mpc . The signal increases with central galaxy luminosity. No alignment signal is detected for blue galaxies. The cos(2θ) -statistic yields very similar results. Starting from a MS semi-analytic galaxy catalog, we assign an orientation to each red, luminous and central galaxy, based on that of the central region of the host halo (with size similar to that of the stellar galaxy). As an alternative, we use the orientation of the host halo itself. We find a mean projected misalignment between a halo and its central region of ∼ 25°. The misalignment decreases slightly with increasing luminosity of the central galaxy. Using the orientations and luminosities of the semi-analytic galaxies, we repeat our alignment analysis on mock surveys of the MS. Agreement with the SDSS results is good if the central orientations are used. Predictions using the halo orientations as proxies for central galaxy orientations overestimate the observed alignment by more than a factor of 2. Finally, the large volume of the MS allows us to generate a two-dimensional map of the alignment correlation function, which shows the reference galaxy distribution to be flattened parallel to the orientations of red luminous galaxies with axis ratios of ∼ 0.5 and ∼ 0.75 for halo and central orientations, respectively. These ratios are almost independent of scale out to 60 h - 1 Mpc .
21769631
The population of Milky Way satellites in the LambdaCDM cosmology
We present a model for the satellites of the Milky Way in which galaxy formation is followed using semi-analytic techniques applied to the six high-resolution N-body simulations of galactic halos of the Aquarius project. The model, calculated using the Galform code, incorporates improved treatments of the relevant physics in the LambdaCDM cosmogony, particularly a self-consistent calculation of reionization by UV photons emitted by the forming galaxy population, including the progenitors of the central galaxy. Along the merger tree of each halo, the model calculates gas cooling (by Compton scattering off cosmic microwave background photons, molecular hydrogen and atomic processes), gas heating (from hydrogen photoionization and supernova energy), star formation and evolution. The evolution of the intergalactic medium is followed simultaneously with that of the galaxies. Star formation in the more massive progenitor subhalos is suppressed primarily by supernova feedback, while for smaller subhalos it is suppressed primarily by photoionization due to external and internal sources. The model is constrained to match a wide range of properties of the present day galaxy population as a whole, but at high redshift it requires an escape fraction of UV photons near unity in order completely to reionize the universe by redshift z ~ 8. In the most successful model the local sources photoionize the pre-galactic region completely by z ~ 10. In addition to the luminosity function of Milky Way satellites, the model matches their observed luminosity-metallicity relation, their radial distribution and the inferred values of the mass within 300 pc, which in the models increase slowly but significantly with luminosity. There is a large variation in satellite properties from halo to halo, with the luminosity function, for example, varying by a factor of ~ 2 among the six simulations.
124150385
Variational Treatment with the Third Order Corrections for SU(2) Lattice Gauge Theory
The variational method in Lagrangian formalism in lattice gauge theory in cumulant expansion is discussed. For SU(2) pure gauge Wi1son model to the third order corrections we show that there is no phase transition in four dimensions, but there exists the first order phase transition in five dimensions at βC=0.838 in agreement with the Monte Carlo results. The physical meaning of higher order corrections is discussed.
17594084
RF systems for the NLCTA
This paper describes an X-band RF system for the Next Linear Collider Test Accelerator. The RF system consists of a 90 MeV injector and a 540 MeV linac. The main components of the injector are two low-Q single-cavity prebunchers and two 0.9-m-long detuned accelerator sections. The linac system consists of six 1.8-m-long detuned and damped detuned accelerator sections powered in pairs. The RF power generation, compression, delivery, distribution and measurement systems consist of klystrons, SLED-II energy compression systems, rectangular waveguides, magic-T's, and directional couplers. The phase and amplitude for each prebuncher is adjusted via a magic-T type phase shifter/attenuator. Correct phasing between the two 0.9 m accelerator sections is obtained by properly aligning the sections and adjusting two squeeze type phase shifters. Bunch phase and bunch length can be monitored with special microwave cavities and measurement systems. The design, fabrication, microwave measurement, calibration, and operation of the sub-systems and their components are briefly presented.
17435025
Blob Ejection from Advection-dominated Accretion Flow: Observational Consequences
There is increasing evidence for the presence of an optically thin advection-dominated accretion flow (ADAF) in low-luminosity active galactic nuclei and radio-loud quasars. The present Letter is devoted to exploring the fate of a blob ejected from an ADAF and to discussing its observational consequences. It is inevitable for the ejected blob to drastically expand into its surroundings. Consequently, it is expected that a group of relativistic electrons will be accelerated, which may lead to nonthermal flares since a strong shock will be formed by the interaction between the blob and its surroundings. Then the blob cools down efficiently, leading to the appearance of recombination lines about 105 s after its ejection from an ADAF. We apply this model to NGC 4258 for some observational prediction and to PKS 2149-306 for the explanation of observational evidence. Future simultaneous observations of recombination X-ray lines and continuum emission are strongly desired for testing the present model.
37724150
FDCSUSYDecay: An MSSM decay package
FDCSUSYDecay is a FORTRAN program package generated by FDC (Feynman Diagram Calculation) system fully automatically. It is dedicated to calculate at tree-level all the possible 2-body decays of SUSY and Higgs particles in the Minimal Supersymmetric extension of the Standard Model (MSSM). The format of its output files complies with SUSY Les Houches Accord and can be easily imported by other package.
122796602
Performance of the CMS cathode strip chambers with cosmic rays
The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in 
the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray 
run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 
1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 µm to 
243 µm. The efficiencies for local charged track triggers, for hit and for segments reconstruction 
were measured, and are above 99%. The timing resolution per layer is approximately 5 ns.
5947961
Meeting Tight Frequency Requirement of Rounded Damped Detuned Structure
Following successful design and fabrication of damped detuned structures, the R and D for the accelerating structures of the NLC/JLC linear collider project proceeded to studies of Rounded Damped Detuned Structure with curved cross section of the cavity shape for increased shunt impedance. The important features of the structure are the accurately tuned accelerating mode frequency and the distribution of the first dipole modes smooth and close to the design distribution. These requirements were met based on the high-accuracy diamond turning with its capability to realize the periphery tolerance of two microns. The lowest dipole mode frequencies scattered by 0.6 MHz RMS. The error in the accelerating mode frequency averaged over a structure was 0.1 MHz by applying a feed-forward method.