[en] We study rolling radii solutions in the context of the four- and five-dimensional effective actions of heterotic M theory. For the standard four-dimensional solutions with varying dilaton and T modulus, we find approximate five-dimensional counterparts. These are new, generically nonseparating solutions corresponding to a pair of five-dimensional domain walls evolving in time. Loop corrections in the four-dimensional theory are described by certain excitations of fields in the fifth dimension. We point out that the two exact separable solutions previously discovered are precisely the special cases for which the loop corrections are time independent. Generically, loop corrections vary with time. Moreover, for a subset of solutions they increase in time, evolving into complicated, nonseparating solutions. In this paper we compute these solutions to leading, nontrivial order. Using the equations for the induced brane metric, we present a general argument showing that the accelerating backgrounds of this type cannot evolve smoothly into decelerating backgrounds

[en] We derive the five-dimensional effective action of strongly coupled heterotic string theory for the complete (1,1) sector of the theory by performing a reduction, on a Calabi-Yau three-fold, of M-theory on S¹/Z₂. A crucial ingredient for a consistent truncation is a non-zero-mode of the antisymmetric tensor field strength which arises due to magnetic sources on the orbifold planes. The correct effective theory is a gauged version of five-dimensional N = 1 supergravity coupled to Abelian vector multiplets, the universal hypermultiplet and four-dimensional boundary theories with gauge and gauge matter fields, The gauging is such that the dual of the four-form field strength in the universal multiplet is charged under a particular linear combination of the Abelian vector fields. In addition, the theory has potential terms for the moduli in the bulk as well as on the boundary. Because of these potential terms, the supersymmetric ground state of the theory is a multi-charged BPS three-brane domain wall, which we construct in general. We show that the five-dimensional theory together with this solution provides the correct starting point for particle phenomenology as well as early universe cosmology. As an application, we compute the four-dimensional N = 1 supergravity theory for the complete (1, 1) sector to leading non-trivial order by a reduction on the domain wall background. We find a correction to the matter field Kaehler potential and threshold corrections to the gauge kinetic functions

[en] The computerised control, safety and interlock system on the first JET Neutral Beam Injector is described

[en] This presentation discusses vortex hybrid system for the glove box and the research behind hybrid fire extinguishing systems for the glove box protection as well as pipe joining technology for critical areas. Water mist systems in this category are for protection in both working surfaces and enclosed spaces of wet benches and similar processing equipment (e.g. fume hoods and glove boxes). These special protection systems have been evaluated in ventilated and unventilated conditions. The systems are designed to provide at least two (2) minutes of protection. These systems are designed to provide protection within the occupancy-specific recommendations.

[en] We present a method for explicitly computing the non-perturbative superpotentials associated with the vector bundle moduli in heterotic superstrings and M-theory. This method is applicable to any stable, holomorphic vector bundle over an elliptically fibered Calabi-Yau threefold. For specificity, the vector bundle moduli superpotential, for a vector bundle with structure group G=SU(3), generated by a heterotic superstring wrapped once over an isolated curve in a Calabi-Yau threefold with base B=F₁, is explicitly calculated. Its locus of critical points is discussed. Superpotentials of vector bundle moduli potentially have important implications for small instanton phase transitions and the vacuum stability and cosmology of superstrings and M-theory

[en] A procedure for computing the dimensions of the moduli spaces of reducible, holomorphic vector bundles on elliptically fibered Calabi-Yau threefolds X is presented. This procedure is applied to poly-stable rank n+m bundles of the form V + pi* M, where V is a stable vector bundle with structure group SU(n) on X and M is a stable vector bundle with structure group SU(m) on the base surface B of X. Such bundles arise from small instanton transitions involving five-branes wrapped on fibers of the elliptic fibration. The structure and physical meaning of these transitions are discussed. (author)

[en] We construct smooth Calabi-Yau threefolds Z, torus-fibered over a dP₉ base, with fundamental group π₁=Z₂xZ₂. To do this, the structure of rational elliptic surfaces is studied and it is shown that a restricted subset of such surfaces admit at least a Z₂xZ₂ group of automorphisms. One then constructs Calabi-Yau threefolds X as the fiber product of two such dP₉ surfaces,demonstrating that the involutions on the surfaces lift to a freely acting Z₂xZ₂ group of automorphisms on X. The threefolds Z are then obtained as the quotient Z=X/(Z₂xZ₂). These Calabi-Yau spaces Z admit stable, holomorphic SU(4) vector bundles which, in conjunction with Z₂xZ₂ Wilson lines, lead to standard-like models of particle physics with naturally suppressed nucleon decay. (author)

[en] Torus-fibered Calabi-Yau three folds Z, with base dP₉ and fundamental group π ₁(Z) = Z₂ x Z₂, are reviewed. It is shown that Z = X/(Z₂ x Z₂), where X = BX_P1 B^' are elliptically fibered Calabi-Yau three folds that admit a freely acting Z₂ x Z₂ automorphisms group. B and B^' are rational elliptic surfaces, each with a Z₂ x Z₂ group of automorphisms. It is shown that the Z₂ x Z₂ invariant classes of curves of each surface have four generators which produce, via the fiber product, seven Z₂ x Z₂ invariant generators in H₄(X,Z). All invariant homology classes are computed explicitly. These descend to produce a rank seven homology group H₄(Z,Z) on Z. The existence of these homology classes on Z is essential to the construction of anomaly free, three family standard-like models with suppressed nucleon decay in both weakly and strongly coupled heterotic superstring theory. (author)

[en] We give the general prescription for calculating the moduli of irreducible, stable SU(n) holomorphic vector bundles with positive spectral covers over elliptically fibered Calabi-Yau threefolds. Explicit results are presented for Hirzebruch base surfaces B=F_r. The transition moduli that are produced by chirality changing small instanton phase transitions are defined and specifically enumerated. The origin of these moduli, as the deformations of the spectral cover restricted to the 'lift' of the horizontal curve of the M5-brane, is discussed. We present an alternative description of the transition moduli as the sections of rank n holomorphic vector bundles over the M5-brane curve and give explicit examples. Vector bundle moduli appear as gauge singlet scalar fields in the effective low-energy actions of heterotic superstrings and heterotic M-theory. (author)

[en] The non-perturbative superpotential generated by a heterotic superstring wrapped once around a genus-zero holomorphic curve is proportional to the Pfaffian involving the determinant of a Dirac operator on this curve. We show that the space of zero modes of this Dirac operator is the kernel of a linear mapping that is dependent on the associated vector bundle moduli. By explicitly computing the determinant of this map, one can deduce whether or not the dimension of the space of zero modes vanishes. It is shown that this information is sufficient to completely determine the Pfaffian and, hence, the non-perturbative superpotential as explicit holomorphic functions of the vector bundle moduli. This method is illustrated by a number of non-trivial examples. (author)