119410655
Exact Seiberg–Witten map, induced gravity and topological invariants in non-commutative field theories
Abstract We revisit the exact Seiberg–Witten (SW) map on Dirac–Born–Infeld actions, making a connection with the deformation quantization scheme. The picture on field dependent induced gravity from non-commutativity becomes more transparent in the context of deformation quantization. We also find an exact SW map for an adjoint scalar field, consistent with that deduced from RR couplings of unstable non-BPS D-branes. The dual description via the exact SW map can again be interpreted as the ordinary field theory coupling to gravity induced by gauge fields. Using the exact SW maps, we further discuss several aspects of topological invariants in non-commutative (NC) gauge theory. Especially, it is shown that the K-theory class on NC instantons is mapped to the usual second Chern class via exact SW map and it leads to an exact SW map between commutative and NC Chern–Simons terms.
16537756
Seiberg-Witten-type maps for currents and energy-momentum tensors in noncommutative gauge theories
We derive maps relating the currents and energy-momentum tensors in noncommutative (NC) gauge theories with their commutative equivalents. Some uses of these maps are discussed. Especially, in NC electrodynamics, we obtain a generalization of the Lorentz force law. Also, the same map for anomalous currents relates the Adler-Bell-Jackiw type NC covariant anomaly with the standard commutative-theory anomaly. For the particular case of two dimensions, we discuss the implications of these maps for the Sugawara-type energy-momentum tensor.
118961522
Comments on Instantons on Noncommutative R 4
We study U(1) and U(2) instanton solutions on noncommutative R 4 based on the noncommutative version of ADHM equation proposed by Nekrasov and Schwarz. It is shown that the anti-self-dual gauge fields on self-dual noncommutative R 4 correctly give integer instanton numbers for all cases we consider. We also show that the completeness relation in the ADHM construction is generally satisfied even for noncommutative spaces.
12060341
ALE spaces from noncommutative U(1) instantons via exact Seiberg-Witten map
The exact Seiberg–Witten (SW) map of a noncommutative (NC) gauge theory gives the commutative equivalent as an ordinary gauge theory coupled to a field dependent effective metric. We study instanton solutions of this commutative equivalent whose self-duality equation turns out to be the exact SW map of NC instantons. We derive general differential equations governing U(1) instantons and we explicitly get an exact solution corresponding to the single NC instanton. Remarkably the effective metric induced by the single U(1) instanton is related to the Eguchi–Hanson metric—the simplest gravitational instanton. Surprisingly the instanton number is not quantized but depends on an integration constant. Our result confirms the expected non-perturbative breakdown of the SW map. However, the breakdown of the map arises in a consistent way: the instanton number plays the role of a parameter giving rise to a one-parameter family of Eguchi–Hanson metrics.
18014891
Twisted bundles on noncommutative T4 and D-brane bound states
We construct twisted quantum bundles and adjoint sections on noncommutative $T^4$, and investigate relevant D-brane bound states with non-Abelian backgrounds. We also show that the noncommutative $T^4$ with non-Abelian backgrounds exhibits SO$(4,4|Z)$ duality and via this duality we get a Morita equivalent $T^4$ on which only D0-branes exist. For a reducible non-Abelian background, the moduli space of D-brane bound states in Type II string theory takes the form $\prod_a (T^4)^{q_a}/S_{q_a}$.
15769713
A Complete Classification of D-branes in Type IIB Plane Wave Background
We give a complete classification of D-branes in the type IIB plane wave background using Green-Schwarz superstring theory. We find all possible supersymmetric oblique and curved D-branes and consider their intersections. The supersymmetries preserved by various configurations of these D-branes are also identified. In particular, we show that D+-branes of type (+,−, n, n) for n = 1, 2, 3, 4 preserve 4 dynamical supersymmetries by introducing gauge field excitations and newly discovered oblique D5and D7-branes also preserve four or two dynamical supersymmetries with gauge field condensates. Furthermore we find new curved D-branes preserving four dynamical supersymmetries.
16109424
Frequency scanned interferometry for ILC tracker alignment
In this paper, we report high-precision absolute distance and vibration measurements performed with frequency scanned interferometry using a pair of single-mode optical b ers. Absolute distance was determined by counting the interference fringes produced while scanning the laser frequency. A high-nesse Fabry-Perot interferometer was used to determine frequency changes during scanning. A dual-laser scanning technique was used to cancel drift errors to improve the absolute distance measurement presicion. Under realistic conditions, a precision of 0.16 microns was achieved for absolute distance of 0.41 meters. Numerical simulation of an optical alignment system for a single silicon ladder, cylinder is also presented. The motivation for this project is to design a novel optical system for quasi-real time alignment of tracker detector elements used in High Energy Physics (HEP) experiments. A.F. Fox-Murphy et.al. from Oxford University reported their design of a frequency scanned interferometer (FSI) for precise alignment of the ATLAS Inner Detector [1, 2]. Given the demonstrated need for improvements in detector performance, we plan to design and prototype an enhanced FSI system to be used for the alignment of tracker elements in the next generation of electron-positron Linear Collider detectors. Current plans for future detectors require a spatial resolution for signals from a tracker detector, such as a silicon microstrip or silicon drift detector, to be approximately 7-10 m [3]. To achieve this required spatial resolution, the measurement precision of absolute distance changes of tracker elements in one dimension should be on the order of 1 m . Simultaneous measurements from hundreds of interferometers will be used to determine the 3-dimensional positions of the tracker elements. The University of Michigan group has constructed several demonstration Frequency Scanned Interferometer (FSI) systems with the laser light transported by air or single-mode optical b er, using single-b er and dual-laser scanning techniques for initial feasibility studies. Absolute distance was determined by counting the interference fringes produced while scanning the laser frequency. The main goal of the demonstration systems was to determine the potential accuracy of absolute distance measurements that could be achieved under both controlled and realistic conditions. Secondary goals included estimating the eects of vibrations and studying error sources crucial to the absolute distance accuracy. Two multiple-distance-measurement analysis techniques were developed to improve distance precision and to extract the amplitude and frequency of vibrations. Under laboratory conditions, a measurement precision of 50 nm was achieved for absolute distances ranging from 0.1 meters to 0.7 meters by using the rst multipledistance-measurement technique. The second analysis technique has the capability to measure vibration frequencies ranging from 0.1 Hz to 100 Hz with amplitude as small as a few nanometers, without a priori knowledge[4]. The multiple-distance-measurement analysis techniques are well suited for reducing vibration eects and uncertainties from fringe & frequency determination, but do not handle well the drift errors such as from thermal eects. In this paper, we describe a dual-laser system intended to reduce the drift errors and show some results under realistic conditions. Numerical simulation of an optical alignment system for a single silicon ladder and for cylinders is also presented.
8948467
High-precision absolute distance and vibration measurement with frequency scanned interferometry.
We report high-precision absolute distance and vibration measurements performed with frequency scanned interferometry using a pair of single-mode optical fibers. Absolute distance was determined by counting the interference fringes produced while scanning the laser frequency. A high-finesse Fabry-Perot interferometer was used to determine frequency changes during scanning. Two multiple-distance-measurement analysis techniques were developed to improve distance precision and to extract the amplitude and frequency of vibrations. Under laboratory conditions, measurement precision of approximately 50 nm was achieved for absolute distances ranging from 0.1 to 0.7 m by use of the first multiple-distance-measurement technique. The second analysis technique has the capability to measure vibration frequencies ranging from 0.1 to 100 Hz with an amplitude as small as a few nanometers without a priori knowledge.
18986664
Discovery Potential of the Standard Model Higgs Boson Through H -> WW Decay Mode with the ATLAS Detector at LHC
We report results of a study of the Standard Model Higgs boson discovery potential through the W-pair leptonic decay modes with the ATLAS detector at LHC at 14 TeV center-of-mass energy. We used MC samples with full detector simulation and reconstruction of the ATLAS experiment to estimate the ATLAS detection sensitivity for the reaction of pp -> H -> WW -> e\nu \mu\nu with no hard jet or two hard jets in the final states. The prospects for the Higgs boson searches at ATLAS are presented, including trigger efficiencies and data-driven methods to estimate the backgrounds using control samples in data. With 10/fb of integrated luminosity, one would expect to discover a Standard Model Higgs boson with ATLAS detector in Higgs boson mass range 135 < m_H < 190 GeV. If the Higgs boson does not exist, we will extend and confirm the exclusion produced by the Tevatron Higgs boson search result, which has ruled out the Higgs boson mass range of 160 < m_H < 170 GeV at 95% confidence level. If Higgs boson would be discovered, ATLAS could measure its mass with a precision of about 2 and 7 GeV for Higgs boson mass around 160 GeV and 130 GeV, respectively.
55601550
Fermion's Tunnelling with Effects of Quantum Gravity
In this paper, using Hamilton-Jacobi method, we address the tunnelling of fermions in a 4-dimensional Schwarzschild spacetime. Based on the generalized uncertainty principle, we introduce 
the influence of quantum gravity. After solving the equation of motion of the spin-1/2 field, we 
derive the corrected Hawking temperature. It turns out that the correction depends not only on 
the black hole’s mass but also on the mass (energy) of emitted fermions. It is of interest that, in 
our calculation, the quantum gravity correction decelerates the temperature increase during the radiation 
explicitly. This observation then naturally leads to the remnants in black hole evaporation. 
Our calculation shows that the residue mass is , where is the Planck mass and is a dimensionless parameter accounting for quantum gravity effects. The evaporation singularity is 
then avoided.
119200112
Double field theory inspired cosmology
Double field theory proposes a generalized spacetime action possessing manifest T-duality on the level of component fields. We calculate the cosmological solutions of double field theory with vanishing Kalb-Ramond field. It turns out that double field theory provides a more consistent way to construct cosmological solutions than the standard string cosmology. We construct solutions for vanishing and non-vanishing symmetry preserving dilaton potentials. The solutions assemble the pre- and post-big bang evolutions in one single line element. Our results show a smooth evolution from an anisotropic early stage to an isotropic phase without any special initial conditions in contrast to previous models. In addition, we demonstrate that the contraction of the dual space automatically leads to both an inflation phase and a decelerated expansion of the ordinary space during different evolution stages.