119171094
Hyperbolic positive energy theorem with electromagnetic fields
We establish a type of positive energy theorem for asymptotically anti-de Sitter Einstein?Maxwell initial data sets by Witten?s spinoral techniques.
119741134
Positive energy theorem for (4+1)-dimensional asymptotically anti-de Sitter spacetimes
We define the total energy-momenta for (4+1)-dimensional asymptotically anti-de Sitter spacetimes, which comes from the boundary terms at infinity in the integral form of the Weitzenböck formula. Then we prove the positive energy theorem for such spacetimes, following Witten’s original arguments for the positive energy theorem in asymptotically flat spacetimes.
64031671
EXPLORATION OF PARALLEL OPTIMIZATION TECHNIQUES FOR ACCELERATOR DESIGN
Optimization through simulation is one of the most timeconsuming tasks in accelerator design, especially for highdimensional problems. We explored several parallel optimization techniques, including parallel genetic algorithm (PGA), parallel hybrid simplex (PHS), and parallel particle swarm optimization (PPSO), to solve some real-world optimization problems. The serial version of the simplex method in elegant [1] is used as a benchmark to compare with the newly developed parallel optimization algorithms in Pelegant [2]. Our experimental results show almost all of the tested parallel optimization methods converge to an equal or better optimization result compared with the serial simplex method, which indicates the serial version of the simplex method could be easily trapped to a local optimum for some applications. The PPSO method is reliable for global optimization and is well suited for parallel computing. The optimization time for a coupling minimization problem was reduced significantly from more than six hours with serial simplex to about twenty minutes on a BlueGene/P supercomputer at the Argonne Leadership Computer Facility (ALCF). The HPS method requires much less time than other optimization algorithms for an experiment where the optimal solution is very close to the initial point for the optimization. These parallel optimization methods not only make the optimization result more reliable but also provide a feasible approach to on-demand accelerator optimization.
121568193
Energy determination at BEPC-II
The BEPC-II collider beam energy calibration system is discussed. The system is based on the Compton backscattering method. The expected precision of the electron and positron beam energy e determination is δ e / e ≈ 3 ⋅ 10 − 5 .
118324520
LINEAR DARK ENERGY EQUATION OF STATE REVEALED BY SUPERNOVAE
In this paper, we propose a test to detect the linearity of the dark energy equation of state, and apply it to the SNLS3 Type Ia Supernova (SN Ia) data set. We find that: (a) current SN Ia data are well described by a dark energy equation of state linear in the cosmic scale factor a, at least up to a redshift z = 1, independent of the pivot points chosen for the linear relation; (b) there is no significant evidence of any deviation from linearity. This apparent linearity may reflect the limit of dark energy information extractable from current SN Ia data.
119181888
LSST Science Book, Version 2.0
A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of the exciting science opportunities of the next decade. The Large Synoptic Survey Telescope (LSST) will have an effective aperture of 6.7 meters and an imaging camera with field of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over 20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a total point-source depth of r~27.5. The LSST Science Book describes the basic parameters of the LSST hardware, software, and observing plans. The book discusses educational and outreach opportunities, then goes on to describe a broad range of science that LSST will revolutionize: mapping the inner and outer Solar System, stellar populations in the Milky Way and nearby galaxies, the structure of the Milky Way disk and halo and other objects in the Local Volume, transient and variable objects both at low and high redshift, and the properties of normal and active galaxies at low and high redshift. It then turns to far-field cosmological topics, exploring properties of supernovae to z~1, strong and weak lensing, the large-scale distribution of galaxies and baryon oscillations, and how these different probes may be combined to constrain cosmological models and the physics of dark energy.
55999663
An Experimental Exploration of the QCD Phase Diagram: The Search for the Critical Point and the Onset of De-confinement
The QCD phase diagram lies at the heart of what the RHIC Physics Program is
all about. While RHIC has been operating very successfully at or close to its
maximum energy for almost a decade, it has become clear that this collider can
also be operated at lower energies down to 5 GeV without extensive upgrades. An
exploration of the full region of beam energies available at the RHIC facility
is imperative. The STAR detector, due to its large uniform acceptance and
excellent particle identification capabilities, is uniquely positioned to carry
out this program in depth and detail. The first exploratory beam energy scan
(BES) run at RHIC took place in 2010 (Run 10), since several STAR upgrades,
most importantly a full barrel Time of Flight detector, are now completed which
add new capabilities important for the interesting physics at BES energies. In
this document we discuss current proposed measurements, with estimations of the
accuracy of the measurements given an assumed event count at each beam energy.