1,354,364 research outputs found
Membrane Vacuum as a Type II Superconductor
No full textWe study a functional field theory of membranes coupled to a rank-three tensor gauge potential. We show that gauge field radiative corrections lead to membrane condensation which turns the gauge field into a massive spin-0 field. This is the Coleman-Weinberg mechanism for membranes. An analogy is also drawn with a type-II superconductor. The ground state of the system consists of a two-phase medium in which the superconducting background condensate is “pierced” by four-dimensional domains, or “bags”, of non-superconducting vacuum. Bags are bounded by membranes whose physical thickness is of the order of the inverse mass acquired by the gauge field
Hausdorff dimension of a quantum string
No full textIn the path integral formulation of quantum mechanics, Feynman and Hibbs noted that the trajectory of a particle is continuous but nowhere differentiable. We extend this result to the quantum-mechanical path of a relativistic string and find that the “trajectory,” in this case, is a fractal surface with Hausdorff dimension three. Depending on the resolution of the detecting apparatus, the extra dimension is perceived as “fuzziness” of the string world surface. We give an interpretation of this phenomenon in terms of a new form of the uncertainty principle for strings, and study the transition from the smooth to the fractal phase
String propagator: A loop space representation
No full textThe string quantum kernel is normally written as a functional sum over the string coordinates and the world-sheet metrics. As an alternative to this quantum field-inspired approach, we study the closed bosonic string propagation amplitude in the functional space of loop configurations. This functional theory is based entirely on the Jacobi variational formulation of quantum mechanics, without the use of a lattice approximation. The corresponding Feynman path integral is weighed by a string action which is a reparametrization invariant version of the Schild action. We show that this path integral formulation is equivalent to a functional ‘‘Schrödinger’’ equation defined in loop space. Finally, for a free string, we show that the path integral and the functional wave equation are exactly solvabl
Conformal p-branes as a source of structure in spacetime
No full textWe discuss a model of a conformal p-brane interacting with the world volume metric and connection. The purpose of the model is to suggest a mechanism by which gravity coupled to p-branes leads to the formation of structure rather than homogeneity in spacetime. Furthermore, we show that the formation of structure is accompanied by the appearance of a multivalued cosmological constant, i.e., one which may take on different values in different domains, or cells, of spacetime. The above results apply to a broad class of nonlinear gravitational Lagrangians as long as metric and connection on the p-brane manifold are treated as independent variables
Membrane pregeometry and the vanishing of the cosmological constant
No full textThe authors suggest a model of induced gravity in which th fundamental object is a relativistic membrane minimally coupled to a background metric and to an external three-index gauge potential. They compute the low-energy limit of the two-loop effective action as a power expansion in the surface tension. A generalized bootstrap hypothesis is made in order to identify the physical metric and gauge field with the lowest-order terms in the expansion of the vacuum average of the composite operators conjugate to the background fields. They find that the large-distance behaviour of these classical fields is described by the Einstein action with a cosmological term plus a Maxwell-type action for the gauge potential. The Maxwell term enables one to apply the Hawking-Baum (1983,1984) argument to show that the physical cosmological constant is 'probably' zero
p-Branes Electric-Magnetic Duality and Stueckelberg/Higgs Mechanism: A Path-Integral Approach
No full textWe study the vacuum functional for a system of p-branes interacting with Maxwell fields of higher rank. This system represents a generalization of the usual electrodynamics of point particles, with one essential difference: the world-history of a p-brane, due to the spatial extension of the object, may possess a physical boundary. Thus, the objective of this study is twofold. First, we wish to exploit the breaking of gauge invariance due to the presence of a physical boundary in order to generate mass as an alternative to the Higgs mechanism. Second, we wish to investigate how the new mechanism of mass generation is affected by the duality transformation between electric and magnetic branes. The entire analysis is performed using the path-integral method, as opposed to the more conventional canonical approach. The advantage of the path-integral formulation is that it enables us to Fourier transform the field strength (rather than the gauge potential) directly. To our knowledge, this field strength formulation represents a new application of the path-integral method, and it leads, in a straightforward way, to the dual representation of the vacuum functional. We find that the effect of the dual transformation is essentially that of exchanging the roles of the gauge fields defined respectively on the “bulk” and “boundary" of the p-brane history
Type III Ehlers-Danlos syndrome: correlations among clinical signs, ultrasound, and histologic findings in a study of 35 cases
No full textParticle propagator in elementary quantum mechanics: a new path integral derivation
No full textThis paper suggests a new way of computing the path integral for simple quantum mechanical systems. The new algorithm originated from previous research in string theory. However, its essential simplicity is best illustrated in the case of a free non relativistic particle, discussed here, and can be appreciated by most students taking an introductory course in quantum mechanics. Indeed, the emphasis is on the role played by the entire family of classical trajectories in terms of which the path integral is computed exactly using a functional representation of the Dirac delta distribution. We argue that the new algorithm leads to a deeper insight into the connection between classical and quantum systems, especially those encountered in high-energy physics
Touring the Planck Scale Antonio Aurilia Memorial Volume
No full textThis book in honor of Antonio Aurilia provides an overview of one of the most mysterious research fields in theoretical physics, namely the fundamental interactions at energies between the electroweak scale and the Planck scale. The latter includes physics beyond the Standard Model, strings and p-branes, quantum gravity, quantum black holes and early Universe cosmology. A related goal of the work is to present the physical conditions upon which some piece of evidence of new physics at extreme energies can be exposed at current (or near future) experimental facilities. The work is organized in three parts. The first part schematically introduces the problem of fundamental interactions and summarizes the life and work of Prof. Aurilia. The second part forms the body of the book. It contains contributions from internationally recognized specialists who collaborated with Prof. Aurilia, such as R. Balbinot, B. Carr, G. Dvali, A. Fabbri, P. Gaete, J. A. Helayël-Neto, R. Mann, J. Mureika, D. Singleton, A. Smailagic, E. Spallucci and P. Townsend. The third part summarizes the work and draws the conclusions with particular attention to future developments
Vacuum bubbles nucleation and dark matter production through gauge symmetry rearrangement
No full textModern particle physics and cosmology support the idea that a background of invisible material pervades the whole universe, and identify in the cosmic vacuum the ultimate source of matter—energy, both seen and unseen. Within the framework of the theory of fundamental relativistic membranes, we suggest a self-consistent, vacuum-energy-driven mechanism for dark matter creation through gauge symmetry rearrangement
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