2,050 research outputs found
Towards open-closed string duality: Closed Strings as Open String Fields
We establish a translation dictionary between open and closed strings,
starting from open string field theory. Under this correspondence, (off-shell)
level-matched closed string states are represented by star algebra projectors
in open string field theory. Particular attention is paid to the zero mode
sector, which is indispensable in order to generate closed string states with
momentum. As an outcome of our identification, we show that boundary states,
which in closed string theory represent D-branes, correspond to the identity
string field in the open string side. It is to be remarked that closed string
theory D-branes are thus given by an infinite superposition of star algebra
projectors.Comment: 29 page
BRST, anti-BRST and their geometry
We continue the comparison between the field theoretical and geometrical
approaches to the gauge field theories of various types, by deriving their
Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST trasformation properties and
comparing them with the geometrical properties of the bundles and gerbes. In
particular, we provide the geometrical interpretation of the so--called
Curci-Ferrari conditions that are invoked for the absolute anticommutativity of
the BRST and anti-BRST symmetry transformations in the context of non-Abelian
1-form gauge theories as well as Abelian gauge theory that incorporates a
2-form gauge field. We also carry out the explicit construction of the 3-form
gauge fields and compare it with the geometry of 2--gerbes.Comment: A comment added. To appear in Jour. Phys. A: Mathemaical and
Theoretica
Notoph Gauge Theory: Superfield Formalism
We derive absolutely anticommuting Becchi-Rouet-Stora-Tyutin (BRST) and
anti-BRST symmetry transformations for the 4D free Abelian 2-form gauge theory
by exploiting the superfield approach to BRST formalism. The antisymmetric
tensor gauge field of the above theory was christened as the "notoph" (i.e. the
opposite of "photon") gauge field by Ogievetsky and Palubarinov way back in
1966-67. We briefly outline the problems involved in obtaining the absolute
anticommutativity of the (anti-) BRST transformations and their resolution
within the framework of geometrical superfield approach to BRST formalism. One
of the highlights of our results is the emergence of a Curci-Ferrari type of
restriction in the context of 4D Abelian 2-form (notoph) gauge theory which
renders the nilpotent (anti-) BRST symmetries of the theory to be absolutely
anticommutative in nature.Comment: LaTeX file, 12 pages, Talk delivered at SQS'09 (BLTP, JINR, Dubna
ANALYSIS OF THE FACTORS AFFECTING 3D MODELS RESOLUTION – APPLICATION TO THE RECORDING OF VAULTS IN SANGALLO'S HOUSE
The paper will present the extraction of information from a laser scanning survey aimed to support historical studies on the Sangallo's house in Florence. In order to verify some study's hypothesis related to the building history and constructive techniques, high resolution models were needed. The meaning of "resolution" applied to 3D scanning will be briefly discussed stressing the difference between resolution and accuracy. Starting from the analysis of technical specifications of the used instruments, the expected performance of the model is described. The results obtained from acquired data are shown and the paper will conclude proposing some answers to the historian's questions
Experimental measurement and model validation of COD in pipe under bending with off-centered circumferential crack
The leak area of circumferential through-thickness crack in pipe under bending depends on the position of the crack with respect to the bending plane. In leak-before-break (LBB) analysis, the assumption that the crack is symmetrically placed with respect to the bending plane is not necessarily conservative. In this work, the crack opening of circumferential cracks, off-centered with respect to the bending plane, was investigated experimentally. Here, three pipe geometries and two crack lengths were investigated. For each crack, the centred and two off-centered configuration were examined. The crack opening displacement (COD) distribution along the crack length was measured for two selected bending load levels using digital image correlation (DIC) technique. These measurements have been used for verifying the solution provided by the hodograph cone method (HCM) as proposed by Bonora [1]
Dressed Sliver solutions in Vacuum String Field Theory
We consider a new class of solutions (dressed slivers) in Vacuum String Field
Theory, which represent D25-branes. For each dressed sliver we introduce a
deformation parameter and define a family of states which are characterized by
new abelian star-subalgebras. We show that this deformation parameter can be
used as a regulator: it allows us to define for each such solution a finite
norm and energy density. Finally we show how to generalize these results to
parallel coincident and to lower dimensional branes.Comment: 39 pages, JHEP style. v2:minor corrections, references adde
Creep modelling of 316H stainless steel over a wide range of stress
Abstract Investigation of material creep behaviour in the diffusion controlled creep regime is often unfeasible because of the long duration associated with low stress levels. On the other side, extrapolation from higher creep rates usually provides inaccurate results because of the sharp change in the data trend as a result of the change in the governing deformation mechanism from dislocation to diffusion type controlled creep. Similarly, extrapolation based on creep models, which have been formulated and validated mainly for dislocation type creep (such power law creep with the creep exponent ranging from 6 to 9), underestimates the actual creep rate significantly. Recently, Bonora and Esposito (2010) developed a mechanism-based model (BE model) capable to account for deformation and damage mechanism occurring in creep. In this work the BE model was applied to AISI 316H stainless steel for which considerable creep data in both dislocation and diffusion temperature/stress controlled regime were available. Using the same data set, the predictive capabilities of several models were compared
Anomalies in noncommutative gauge theories, Seiberg-Witten transformation and Ramond-Ramond couplings
We propose an exact expression for the unintegrated form of the star gauge
invariant axial anomaly in an arbitrary even dimensional gauge theory. The
proposal is based on the inverse Seiberg-Witten map and identities related to
it, obtained earlier by comparing Ramond-Ramond couplings in different
decsriptions. The integrated anomalies are expressed in terms of a simplified
version of the Elliott formula involving the noncommutative Chern character.
These anomalies, under the Seiberg-Witten transformation, reduce to the
ordinary axial anomalies. Compatibility with existing results of anomalies in
noncommutative theories is established.Comment: 16 pages. LaTe
High-rate characterization of additively manufactured Ti-6Al-4V using Taylor cylinder impact test: Experiments
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