6,439 research outputs found
On Asymmetric Orbifolds and the D=5 No-modulus Supergravity
We examine whether any type II asymmetric orbifolds have the same massless
spectrum as the dimensional reduction of D=5 simple supergravity, which,
besides the eleven-dimensional supergravity, is the only known supergravity
above four dimensions with no moduli. We attempt to construct such models by
further twisting the orbifolds which yield D=4, N=4 pure supergravity to find
that, unfortunately, none of the models have that spectrum. We provide
supergravity arguments explaining why this is so. As a by-product, we list all
possible momentum-winding lattices that give D=4, N=4 pure supergravity.Comment: 10 page
Duality Symmetry of String Theory: A Worldsheet Perspective
We study duality and local symmetries of closed bosonic string from the
perspectives of worldsheet approach in the phase space path integral formalism.
It is shown that the Ward identities reflecting the local symmetries associated
with massless excitations such as graviton and antisymmetric tensor can be cast
in a duality covariant form. It is shown how the manifestly O(d,d) invariant
Hamiltonian can be obtained in the Hassan-Sen toroidal compactification scheme,
d being the number of compact dimensions. It is proposed that massive excited
states possess a T-duality symmetry for constant (tensor) backgrounds. This
conjecture is verified for the first massive level.Comment: 14 page
Synthetic Grey Water Treatment Through FeCl3-Activated Carbon Obtained from Cotton Stalks and River Sand
The research objective was to reclaim greywater through simple, easily available, and cost-effective methods. For this purpose, an activated charcoal was prepared from biomass (cotton stalk) through the pyrolysis process and sand collected from river Indus. Both materials were subjected to separate columns and applied as filters. Whereas, the efficiency of both materials as filter media was analyzed on the synthetic grey water (SGW). The formulation of synthetic greywater was a complicated process because the selection of ingredients and their amount should not exceed from the real grey water. So, for the presence of fecal contamination, a small amount (10 ml L-1) of settled sewage was added to the distilled water, while to mimic the organic load, several chemical products of technical grade were also added. The physicochemical and microbiological characteristics of this SGW were tested before and after treatment. The results show that both mediums (AC and river sand) were very effective in the greywater treatment. The removal efficiency for BOD and COD was up to 91.2%, and 70% respectively. Similarly, the removal measure for turbidity was 91.3%. While the pH showed that the synthetic grey water was alkaline in nature with a value of 10 because the washing detergents used during the preparation of SGW, but after passing through both filter columns, pH was observed in between 7 and 8 units. Furthermore, the removal value examined after passing SGW from both columns for total coliforms was 46.87 CFU/100 ml from1500 CFU/100 ml
Noncompact Symmetries in String Theory
Noncompact groups, similar to those that appeared in various supergravity
theories in the 1970's, have been turning up in recent studies of string
theory. First it was discovered that moduli spaces of toroidal compactification
are given by noncompact groups modded out by their maximal compact subgroups
and discrete duality groups. Then it was found that many other moduli spaces
have analogous descriptions. More recently, noncompact group symmetries have
turned up in effective actions used to study string cosmology and other
classical configurations. This paper explores these noncompact groups in the
case of toroidal compactification both from the viewpoint of low-energy
effective field theory, using the method of dimensional reduction, and from the
viewpoint of the string theory world sheet. The conclusion is that all these
symmetries are intimately related. In particular, we find that Chern--Simons
terms in the three-form field strength play a crucial role.Comment: 40 pages, phyzzx, CALT-68-179
Duality Transformations in Supersymmetric Yang-Mills Theories coupled to Supergravity,
We consider duality transformations in N=2, d=4 Yang--Mills theory coupled to
N=2 supergravity. A symplectic and coordinate covariant framework is
established, which allows one to discuss stringy `classical and quantum duality
symmetries' (monodromies), incorporating T and S dualities. In particular, we
shall be able to study theories (like N=2 heterotic strings) which are
formulated in symplectic basis where a `holomorphic prepotential' F does not
exist, and yet give general expressions for all relevant physical quantities.
Duality transformations and symmetries for the N=1 matter coupled Yang--Mills
supergravity system are also exhibited. The implications of duality symmetry on
all N>2 extended supergravities are briefly mentioned. We finally give the
general form of the central charge and the N=2 semiclassical spectrum of the
dyonic BPS saturated states (as it comes by truncation of the N=4 spectrum).Comment: 41 pages, harvmac, no figures. References added, and minor printing
error corrected
Maria del Refugio Corral
Illustration: Monika Narain / Narration: Brandon Smith, Archan Das, Monika Narain, Hannah Xu and Krisha Patelhttps://digitalcommons.imsa.edu/spanish_v/1000/thumbnail.jp
Peri-urbanism in globalizing India: a study of pollution, health and community awareness
This paper examines the intersection between environmental pollution and people's acknowledgements of, and responses to, health issues in Karhera, a former agricultural village situated between the rapidly expanding cities of New Delhi (India's capital) and Ghaziabad (an industrial district in Uttar Pradesh). A relational place-based view is integrated with an interpretive approach, highlighting the significance of place, people's emic experiences, and the creation of meaning through social interactions. Research included surveying 1788 households, in-depth interviews, participatory mapping exercises, and a review of media articles on environment, pollution, and health. Karhera experiences both domestic pollution, through the use of domestic waste water, or gandapani, for vegetable irrigation, and industrial pollution through factories' emissions into both the air and water. The paper shows that there is no uniform articulation of any environment/health threats associated with gandapani. Some people take preventative actions to avoid exposure while others do not acknowledge health implications. By contrast, industrial pollution is widely noted and frequently commented upon, but little collective action addresses this. The paper explores how the characteristics of Karhera, its heterogeneous population, diverse forms of environmental pollution, and broader governance processes, limit the potential for citizen action against pollution
Summary of the Activities of the Working Group I on High Energy and Collider Physics
This is a summary of the projects undertaken by the Working Group I on High
Energy Collider Physics at the Eighth Workshop on High Energy Physics
Phenomenology (WHEPP8) held at the Indian Institute of Technology, Mumbai,
January 5-16, 2004. The topics covered are (i) Higgs searches (ii)
supersymmetry searches (iii) extra dimensions and (iv) linear collider.Comment: summary of Working Group I at the Eighth Workshop on High Energy
Physics Phenomenology (WHEPP8), I.I.T., Mumbai, January 5-16, 200
The D0 Run II Impact Parameter Trigger
Many physics topics to be studied by the D0 experiment during Run II of the
Fermilab Tevatron ppbar collider give rise to final states containing
b--flavored particles. Examples include Higgs searches, top quark production
and decay studies, and full reconstruction of B decays. The sensitivity to such
modes has been significantly enhanced by the installation of a silicon based
vertex detector as part of the DO detector upgrade for Run II. Interesting
events must be identified initially in 100-200 microseconds to be available for
later study. This paper describes custom electronics used in the DO trigger
system to provide the real--time identification of events having tracks
consistent with the decay of b--flavored particles.Comment: To be submitted to Nucl. Instrum. Methods A. 56 pages, 31 figure
- …