51,659 research outputs found
The low energy expansion of the one-loop type II superstring amplitude
The one-loop four-graviton amplitude in either of the type II superstring
theories is expanded in powers of the external momenta up to and including
terms of order s^4 log s R^4, where R^4 denotes a specific contraction of four
linearized Weyl tensors and s is a Mandelstam invariant. Terms in this series
are obtained by integrating powers of the two-dimensional scalar field theory
propagator over the toroidal world-sheet as well as the moduli of the torus.
The values of these coefficients match expectations based on duality relations
between string theory and eleven-dimensional supergravity.Comment: harvmac (b), 25 pages, 3 eps figures. v2: Factors of 2 corrected.
Conclusion unchange
D-Instanton Corrections as (p,q)-String Effects and Non-Renormalization Theorems
We discuss higher derivative interactions in the type IIB superstring in ten
dimensions. From the fundamental string point of view, the non-perturbative
corrections are due to D-instantons. We argue that they can alternatively be
understood as arising from -strings. We derive a non-renormalization
theorem for eight-derivative bosonic interactions, which states that terms
involving either NS-NS or R-R fields occur at tree-level and one-loop only. By
using the symmetry of M-theory on , we show that in order for
the possible interactions in M-theory to have a
consistent perturbative expansion in nine dimensions, must be odd. Thus,
only terms can be present in M-theory and their string
theory counterparts arise at and loops. Finally, we treat an example
of fermionic term.Comment: 24 pages, latex, additional arguments for the perturbative form of
the eight-derivative interaction
Nondecoupling of Maximal Supergravity from the Superstring
We consider the conditions necessary for obtaining perturbative maximal supergravity in d dimensions as a decoupling limit of type II superstring theory compactified on a (10-d) torus. For dimensions d=2 and d=3, it is possible to define a limit in which the only finite-mass states are the 256 massless states of maximal supergravity. However, in dimensions d>=4, there are infinite towers of additional massless and finite-mass states. These correspond to Kaluza-Klein charges, wound strings, Kaluza-Klein monopoles, or branes wrapping around cycles of the toroidal extra dimensions. We conclude that perturbative supergravity cannot be decoupled from string theory in dimensions >=4. In particular, we conjecture that pure [script N]=8 supergravity in four dimensions is in the Swampland
Supersymmetry Constraints on Type IIB Supergravity
Supersymmetry is used to derive conditions on higher derivative terms in the
effective action of type IIB supergravity. Using these conditions, we are able
to prove earlier conjectures that certain modular invariant interactions of
order alpha' **3 relative to the Einstein-Hilbert term are proportional to
eigenfunctions of the Laplace operator on the fundamental domain of SL(2,Z). We
also discuss how these arguments generalize to terms of higher order in alpha',
as well as to compactifications of supergravity.Comment: 31 pages, harvmac (b); minor correction
Light-cone Quantum Mechanics of the Eleven-dimensional Superparticle
The linearized interactions of eleven-dimensional supergravity are obtained
in a manifestly supersymmetric light-cone gauge formalism. These vertices are
used to calculate certain one-loop processes involving external gravitini,
antisymmetric three-form potentials and gravitons, thereby determining some
protected terms in the effective action of M-theory compactified on a
two-torus.Comment: 31 pages, harvmac (b); A minor TeX error correcte
D-instanton partition functions
Duality arguments are used to determine D-instanton contributions to certain
effective interaction terms of type II supergravity theories in various
dimensions. This leads to exact expressions for the partition functions of the
finite N D-instanton matrix model in d=4 and 6 dimensions that generalize our
previous expression for the case d=10. These results are consistent with the
fact that the Witten index of the T-dual D-particle process should only be
non-vanishing for d=10.Comment: 20 pages, harvmac, typos corrected, reference adde
Thermal -Brane Boundary States from Green-Schwarz Superstrings
In this paper we thermalize the type II superstrings in the GS formulation by
applying the TFD formalism. The thermal boundary conditions on the thermal
Hilbert space are obtained from the BPS -brane boundary conditions at zero
temperature. We show that thermal boundary states can be obtained by
thermalization from the BPS -branes at zero temperature. These new states
can be interpreted as thermal -branes. Next, we discuss the supersymmetry
breaking of the thermal string in the TFD approach. We identify the broken
supersymmetry with the -transformation while the
-transformation is preserved. Also, we compute the thermal partition
function and the entropy of the thermal string.Comment: 23 pages, LATeX fil
Relativistic Harmonic Oscillator Revisited
The familiar Fock space commonly used to describe the relativistic harmonic
oscillator, for example as part of string theory, is insufficient to describe
all the states of the relativistic oscillator. We find that there are three
different vacua leading to three disconnected Fock sectors, all constructed
with the same creation-annihilation operators. These have different spacetime
geometric properties as well as different algebraic symmetry properties or
different quantum numbers. Two of these Fock spaces include negative norm
ghosts (as in string theory) while the third one is completely free of ghosts.
We discuss a gauge symmetry in a worldline theory approach that supplies
appropriate constraints to remove all the ghosts from all Fock sectors of the
single oscillator. The resulting ghost free quantum spectrum in d+1 dimensions
is then classified in unitary representations of the Lorentz group SO(d,1).
Moreover all states of the single oscillator put together make up a single
infinite dimensional unitary representation of a hidden global symmetry
SU(d,1), whose Casimir eigenvalues are computed. Possible applications of these
new results in string theory and other areas of physics and mathematics are
briefly mentioned.Comment: 41 pages, 2 figures, LaTe
The Food Retailing Structure of the Northwest Territories
Food retailers in the Northwest Territories face dramatically different conditions from those of southern food retailers. There are three main differences: (1) small market size, (2) limited geographical access to suppliers and (3) different types of competitors. These differences have resulted in higher food prices and smaller, more general, stores with a wider variety of merchandise than southern supermarkets. Resupply is much less frequent than in southern supermarkets because resupply must be made via either air or barge shipment rather than truck delivery. The N.W.T. food retailing structure comprises three types of food retailers: the independently operated stores, the cooperatives and chain stores. This first examination of the similarities and differences between the store types is drawn from a mail survey of all the food retailers in the N.W.T. The food retailers have adapted to the small, isolated northern markets by expanding their merchandise line well beyond food products. The Hudson's Bay Company stores carry the widest variety of merchandise, while the others carry a more limited product line. Inventory management varies among the store types. The cooperatives generally fail to use the cheaper alternative transportation modes (road or water) where possible. This is not due to location but may reflect poor managerial skills or simply a lack of profit motivation.Key words: food retailing, Northwest Temtories, mode, retail structure, management, Hudson’s Bay Company, cooperatives, independentsLes détaillants en alimentation des Territoires du Nord-Ouest font face à des conditions radicalement différentes de celles des détaillants en alimentation du Sud. Il y a trois différences principales: (1) le marché est plus petit, (2) l’accès géographique aux fournisseurs est limité et (3) les concurrents sont d’un genre différent. Ces différences font que le prix de la nourriture est plus élevé, que les magasins sont plus petits et qu’ils ressemblent plus à un magasin général, offrant une plus grande variété de marchandises que les supermarchés du Sud. La fréquence du réapprovisionnement est moindre que pour ces derniers, car l’approvisionnement doit se faire par avion ou par péniche plutôt que par camion. La structure de l’alimentation de détail dans les T.N.-O. comprend trois types de détaillants les magasins indépendants, les coopératives et les magasins appartenant à des chaînes. Ce premier examen des ressemblances et des différences entre les types de magasins a été obtenu à partir d’une enquête postée à tous les détaillants en alimentation des T. N.-O. Les détaillants en alimentation se sont adaptés aux petits marchés isolés du Nord en élargissant la gamme de leurs produits bien au-delà des produits alimentaires. Les magasins de la Compagnie de la Baie d’Hudson ont la plus grande variété de marchandises, tandis que les autres ont une gamme de produits plus limitée. La gestion des inventaires varie entre les différents types de magasins. En général, les coopératives ne profitent pas des autres moyens de transport (routiers et par voie d’eau) là où elles le pourraient. Cela n’est pas dû à leur situation géographique, mais c’est plutôt le reflet d’un manque d’expérience en gestion ou simplement d’un manque de motivation à réaliser des profits.Mots clés: vente d’alimentation au détail, Territoires du Nord-Ouest, moyen, structure de vente de détail, gestion, Compagnie de la Baie d’Hudson, coopératives, magasins indépendant
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