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Simon Davis

Publications and source records attributed to Simon Davis.

18 recordsLinked to original sources

A Proof of the Odd Perfect Number Conjecture

It is sufficient to prove that there is an excess of prime factors in the product of repunits with odd prime bases defined by the sum of divisors of the integer $N=(4k+1)^{4m+1}\prod_{i=1}^\ell ~ q_i^{2α_i}$ to establish that there do not exist any odd integers with equality between $σ(N)$ and 2N. The existence of distinct prime divisors in the repunits in $σ(N)$ follows from a theorem on the primitive divisors of the Lucas sequences $U_{2α_i+1}(q_i+1,q_i)$ and $U_{2α_j+1}(q_j+1,q_j)$ with $q_i,q_j,2α_i+1,2α_j+1$ being odd primes. The occurrence of new prime divisors in each quotient ${{(4k+1)^{4m+2}-1}\over {4k}}$, ${{q_i^{2α_i+1}-1}\over {q_i-1}}, i=1,...,\ell$ also implies that the square root of the product of $2(4k+1)$ and the sequence of repunits will not be rational unless the primes are matched. Although a finite set of solutions to the rationality condition for the existence of odd perfect numbers is obtained, it is verified that they all satisfy ${{σ(N)}\over N}\ne 2$ because the repunits in the product representing $σ(N)$ introduce new prime divisors. Minimization of the number of prime divisors in $σ(N)$ leads to an infinite set of repunits of increasing mangitude or prime equations with no integer solutions. It is proven then that there exist no odd perfect numbers.

hep-th

Effectively Closed Infinite-Genus Surfaces and the String Coupling

The class of effectively closed infinite-genus surfaces, defining the completion of the domain of string perturbation theory, can be included in the category $O_G$, which is characterized by the vanishing capacity of the ideal boundary. The cardinality of the maximal set of endpoints is shown to be $2^{\mit N}$. The product of the coefficient of the genus-g superstring amplitude in four dimensions by $2^g$ in the $g\to \infty$ limit is an exponential function of the genus with a base comparable in magnitude to the unified gauge coupling. The value of the string coupling is consistent with the characteristics of configurations which provide a dominant contribution to a finite vacuum amplitude.

hep-th

The Quantum Cosmological Wavefunction at Very Early Times for a Quadratic Gravity Theory

The quantum cosmological wavefunction for a quadratic gravity theory derived from the heterotic string effective action is obtained near the inflationary epoch and during the initial Planck era. Neglecting derivatives with respect to the scalar field, the wavefunction would satisfy a third-order differential equation near the inflationary epoch which has a solution that is singular in the scale factor limit $a(t)\to 0$. When scalar field derivatives are included, a sixth-order differential equation is obtained for the wavefunction and the solution by Mellin transform is regular in the $a\to 0$ limit. It follows that inclusion of the scalar field in the quadratic gravity action is necessary for consistency of the quantum cosmology of the theory at very early times.

gr-qc

The quantum theory of a quadratic gravity action for heterotic strings

The wave function for the quadratic gravity theory derived from the heterotic string effective action is deduced to first order in ${e^{-Φ}\over {g_4^2}}$ by solving a perturbed second-order Wheeler-DeWitt equation, assuming that the potential is slowly varying with respect to $Φ$. Predictions for inflation based on the solution to the second-order Wheeler-DeWitt equation continue to hold for this theory. It is shown how formal expressions for the average paths in minisuperspace $\{< a(t) >, < Φ(t)> \}$ determine the shifts from the classical solutions to $a_{cl}(t)$ and $Φ_{cl}(t)$, which occur only at third order in the expansion of the integrals representing the expectation values.

gr-qc

A Rationality Condition for the Existence of Odd Perfect Numbers

A rationality condition is derived for the existence of odd perfect numbers involving the square root of a product, which consists of a sequence of repunits, multiplied by twice the base of one of the repunits. This constraint also provides an upper bound for density of odd integers which could satisfy ${{σ(N)}\over N}=2$, where $N$ belongs to a fixed interval with a lower limit greater than $10^{300}$. Characteristics of prime divisors of repunits are used to establish whether the product containing the repunits can be a perfect square. It is shown that the arithmetic primitive divisors with different prime bases can be equal only when the exponents are different, with the exception of a set of cases derived from solutions of a solution prime equation. The proof of this result requires the demonstration of the non-existence of solutions of a more general prime equation, a problem which is equivalent to Catalan's conjecture. Results concerning the exponents of prime divisors of the repunits are obtained, and they are combined with the method of induction to prove to prove a general theorem on the non-existence of prime divisors satisfying the rationality condition.

math.NT

The Effect of Higher-Order Curvature Terms on String Quantum Cosmology

Several new results regarding the quantum cosmology of the quadratic gravity theory derived from the heterotic string effective action are presented. After describing techniques for solving the Wheeler-De Witt equation with appropriate boundary conditions, it is shown that this quantum cosmological model may be compared with semiclassical theories of inflationary cosmology. In particular, it should be possible to compute corrections to the standard inflationary model perturbatively about a stable exponentially expanding classical background.

gr-qc

Spin Structures on Riemann Surfaces and the Perfect Numbers

The equality between the number of odd spin structures on a Riemann surface of genus g, with $2^g - 1$ being a Mersenne prime, and the even perfect numbers, is an indication that the action of the modular group on the set of spin structures has special properties related to the sequence of perfect numbers. A method for determining whether Mersenne numbers are primes is developed by using a geometrical representation of these numbers. The connection between the non-existence of finite odd perfect numbers and the irrationality of the square root of twice the product of a sequence of repunits is investigated, and it is demonstrated, for an arbitrary number of prime factors, that the products of the corresponding repunits will not equal twice the square of a rational number.

math-ph

Higher-Derivative Quantum Cosmology

The quantum cosmology of a higher-derivative derivative gravity theory arising from the heterotic string effective action is reviewed. A new type of Wheeler-DeWitt equation is obtained when the dilaton is coupled to the quadratic curvature terms. Techniques for solving the Wheeler-DeWitt equation with appropriate boundary conditions shall be described, and implications for semiclassical theories of inflationary cosmology will be outlined.

gr-qc

Summability of Superstring Theory

Several arguments are given for the summability of the superstring perturbation series. Whereas the Schottky group coordinatization of moduli space may be used to provide refined estimates of large-order bosonic string amplitudes, the super-Schottky group variables define a measure for the supermoduli space integral which leads to upper bounds on superstring scattering amplitudes.

hep-th

Scalar Field Theory in Curved Space and the Definition of Momentum

Some general remarks are made about the quantum theory of scalar fields and the definition of momentum in curved space. Special emphasis is given to field theory in anti-de Sitter space, as it represents a maximally symmetric space-time of constant curvature which could arise in the local description of matter interactions in small regions of space-time. Transform space rules for evaluating Feynman diagrams in Euclidean anti-de Sitter space are initially defined using eigenfunctions based on generalized plane waves. It is shown that, for a general curved space, the rules associated with the vertex are dependent on the type of interaction being considered. A condition for eliminating this dependence is given. It is demonstrated that the vacuum and propagator in conformally flat coordinates in anti-de Sitter space are equivalent to those analytically continued from $H^4$ and that transform space rules based on these coordinates can be used more readily. A proof of the analogue of Goldstone's theorem in anti-de Sitter space is given, using a generalized plane wave representation of the commutator of the current and the scalar field. It is shown that the introduction of curvature in the space-time shifts the momentum by an amount which is determined by the Riemann tensor to first order, and it follows that there is a shift in both the momentum and mass scale in anti-de Sitter space.

hep-th

Symmetric Variations of the Metric and Extrema of the Action for Pure Gravity

Symmetries of generalized gravitational actions, yielding field equations which typically involve at most second-order derivatives of the metric, are considered. The field equations for several different higher-derivative theories in the first-order formalism are derived, and variations of a generic set of higher-order curvature terms appearing in string effective actions are studied. It is shown that there often exists a particular set of solutions to the field equations of pure gravity theories, consisting of different combinations of curvature tensors, which satisfies the vacuum equations with cosmological constant. Implications of generalized symmetries of the field equations derived from the superstring effective action for the cosmological constant problem are discussed.

gr-qc

The Four-Point Function on a Surface of Infinite Genus

The four-point function arising in the scattering of closed bosonic strings in their tachyonic ground state is evaluated on a surface of infinite genus. The amplitude has poles corresponding to physical intermediate states and divergences at the boundary of moduli space, but no new types of divergences result from the infinite number of handles. The implications for the universal moduli space approach are briefly discussed.

hep-th

Modular Invariance and the Finiteness of Superstring Theory

The genus-dependence of multi-loop superstring amplitudes is bounded at large orders in perturbation theory using the super-Schottky group parametrization of supermoduli space. Partial estimates of supermoduli space integrals suggest an exponential dependence on the genus when the integration region is restricted to a single fundamental domain of the super-modular group in the super-Schottky parameter space. Bounds for N-point superstring scattering amplitudes are obtained for arbitrary N and are shown to be consistent with exact results recently obtained for special type II string amplitudes for orbifold or Calabi-Yau compactifications. It is suggested that the generic estimates, which imply the validity of superstring perturbation theory in the weak-coupling limit, might be used to determine scattering amplitudes at strong coupling because of the S-duality of type II and heterotic string theories. Non-perturbative effects are consistent with these estimates, based on a sum over closed surfaces, because they can be derived from an additional contribution to the sum over surfaces corresponding to the insertion of Dirichlet boundaries.

hep-th

Infinite-genus surfaces and the universal Grassmannian

Correlation functions can be calculated on Riemann surfaces using the operator formalism. The state in the Hilbert space of the free field theory on the punctured disc, corresponding to the Riemann surface, is constructed at infinite genus, verifying the inclusion of these surfaces in the Grassmannian. In particular, a subset of the class of $O_{HD}$ surfaces can be identified with a subset of the Grassmannian. The concept of flux through the ideal boundary is used to study the connection between infinite-genus surface and the domain of string perturbation theory. The different roles of effectively closed surfaces with Dirichlet boundaries in a more complete formulation of string theory are identified.

hep-th

Connections and Generalized Gauge Transformations

Elimination of the fibre coordinate dependence from the connection form transformation rule for a bundle with a coset manifold standard fibre reduces the structure group. The nonlinear SU(4) action on an $S^7$ bundle is applied to the dimensional reduction of eleven-dimensional supergravity and ten-dimensional superstring theory to four dimensions. A principle, consistent with higher-dimensional superstring theory, is suggested to explain the types of gauge interactions that arise in the standard model based on the geometry of the internal symmetry spaces. It is shown why a Lie group structure is required for vector bosons in pure gauge theories and that the application of division algebras to force unification must begin with the fermions comprising the elementary particle multiplets of the standard model. A suggestion is made for establishing a mechanism for the cancellation of anomalies within this approach to superstring theory.

hep-th

The Bosonic String Measure at Two and Three Loops and Symplectic Transformations of the Volume Form

Symplectic modular invariance of the bosonic string partition function has been verified at genus 2 and 3 using the period matrix coordinatization of moduli space. A calculation of the transformation of the holomorphic part of the differential volume element shows that an extra phase arises together with the factor associated with a specific modular weight; the phase is cancelled in the transformation of the entire volume element including the complex conjugate. An argument is given for modular invariance of the reggeon measure at genus twelve.

hep-th

Divergences in the Moduli Space Integral and Accumulating Handles in the Infinite-Genus Limit

The symmetries associated with the closed bosonic string partition function are examined so that the integration region in Teichmuller space can be determined. The conditions on the period matrix defining the fundamental region can be translated to relations on the parameters of the uniformizing Schottky group. The growth of the lower bound for the regularized partition function is derived through integration over a subset of the fundamental region.

hep-th

Configurations of Handles and the Classification of Divergences in the String Partition Function

The divergences that arise in the regularized partition function for closed bosonic string theory in flat space lead to three types of perturbation series expansions, distinguished by their genus dependence. This classification of infinities can be traced to geometrical characteristics of the string worldsheet. Some categories of divergences may be eliminated in string theories formulated on compact manifolds.

hep-th