James H. Ettle
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Research Subjects
James H. Ettle has a total of 2 co-authors. Here are the top co-authors by number of shared publications:
- David C. Dunbar
Swansea University
6 shared publications - Warren B. Perkins
Swansea University
6 shared publications
Latest Publications
- 23 July 2012
- Published by American Physical Society (APS) in Physical Review D
- Vol. 86 (2)
Constructing gravity amplitudes from real soft and collinear factorization
Soft and collinear factorizations can be used to construct expressions for amplitudes in theories of gravity. We generalise the “half-soft” functions used previously to “soft-lifting” functions and use these to generate tree and one-loop amplitudes. In particular we construct expressions for maximally helicity-violating tree amplitudes and the rational terms in one-loop amplitudes in the specific context of supergravity. To completely determine the rational terms collinear factorization must also be used. The rational terms for have a remarkable diagrammatic interpretation as arising from algebraic link diagrams. DOI: http://dx.doi.org/10.1103/PhysRevD.86.026009 © 2012 American Physical Society- 23 July 2012
- Published by American Physical Society (APS) in Physical Review D
- Vol. 86 (2)
Constructing gravity amplitudes from real soft and collinear factorization
Soft and collinear factorizations can be used to construct expressions for amplitudes in theories of gravity. We generalise the “half-soft” functions used previously to “soft-lifting” functions and use these to generate tree and one-loop amplitudes. In particular we construct expressions for maximally helicity-violating tree amplitudes and the rational terms in one-loop amplitudes in the specific context of supergravity. To completely determine the rational terms collinear factorization must also be used. The rational terms for have a remarkable diagrammatic interpretation as arising from algebraic link diagrams. DOI: http://dx.doi.org/10.1103/PhysRevD.86.026009 © 2012 American Physical Society- 23 December 2011
- Published by American Physical Society (APS) in Physical Review D
- Vol. 84 (12)
Obtaining one-loop gravity amplitudes using spurious singularities
The decomposition of a one-loop scattering amplitude into elementary functions with rational coefficients introduces spurious singularities which afflict individual coefficients but cancel in the complete amplitude. These cancellations create a web of interactions between the various terms. We explore the extent to which entire one-loop amplitudes can be determined from these relationships starting with a relatively small input of initial information, typically the coefficients of the scalar integral functions as these are readily determined. In the context of one-loop gravity amplitudes, of which relatively little is known, we find that some amplitudes with a small number of legs can be completely determined from their box coefficients. For increasing numbers of legs, ambiguities appear which can be determined from the physical singularity structure of the amplitude. We illustrate this with the four-point and five-point (super)gravity one-loop amplitudes. DOI: http://dx.doi.org/10.1103/PhysRevD.84.125029 © 2011 American Physical Society- 23 December 2011
- Published by American Physical Society (APS) in Physical Review D
- Vol. 84 (12)
Obtaining one-loop gravity amplitudes using spurious singularities
The decomposition of a one-loop scattering amplitude into elementary functions with rational coefficients introduces spurious singularities which afflict individual coefficients but cancel in the complete amplitude. These cancellations create a web of interactions between the various terms. We explore the extent to which entire one-loop amplitudes can be determined from these relationships starting with a relatively small input of initial information, typically the coefficients of the scalar integral functions as these are readily determined. In the context of one-loop gravity amplitudes, of which relatively little is known, we find that some amplitudes with a small number of legs can be completely determined from their box coefficients. For increasing numbers of legs, ambiguities appear which can be determined from the physical singularity structure of the amplitude. We illustrate this with the four-point and five-point (super)gravity one-loop amplitudes. DOI: http://dx.doi.org/10.1103/PhysRevD.84.125029 © 2011 American Physical Society- Open Access
Perturbative expansion of N<8 Supergravity
We characterise the one-loop amplitudes for N=6 and N=4 supergravity in four dimensions. For N=6 we find that the one-loop n-point amplitudes can be expanded in terms of scalar box and triangle functions only. This simplification is consistent with a loop momentum power count of n-3, which we would interpret as being n+4 for gravity with a further -7 from the N=6 superalgebra. For N=4 we find that the amplitude is consistent with a loop momentum power count of n, which we would interpret as being n+4 for gravity with a further -4 from the N=4 superalgebra. Specifically the N=4 amplitudes contain non-cut-constructible rational terms.
Open AccessPerturbative expansion of N<8 Supergravity
We characterise the one-loop amplitudes for N=6 and N=4 supergravity in four dimensions. For N=6 we find that the one-loop n-point amplitudes can be expanded in terms of scalar box and triangle functions only. This simplification is consistent with a loop momentum power count of n-3, which we would interpret as being n+4 for gravity with a further -7 from the N=6 superalgebra. For N=4 we find that the amplitude is consistent with a loop momentum power count of n, which we would interpret as being n+4 for gravity with a further -4 from the N=4 superalgebra. Specifically the N=4 amplitudes contain non-cut-constructible rational terms.
- 9 March 2011
- Published by American Physical Society (APS) in Physical Review D
- Vol. 83 (6)
Perturbative expansion ofSupergravityWe characterize the one-loop amplitudes for N=6 and N=4 supergravity in four dimensions. For N=6 we find that the one-loop n-point amplitudes can be expanded in terms of scalar box and triangle functions only. This simplification is consistent with a loop momentum power count of n-3, which we would interpret as being n+4 for gravity with a further -7 from the N=6 superalgebra. For N=4 we find that the amplitude is consistent with a loop momentum power count of n, which we would interpret as being n+4 for gravity with a further -4 from the N=4 superalgebra. In contrast to previous studies we find that the N=4 amplitudes contain noncut-constructible rational terms.
- 9 March 2011
- Published by American Physical Society (APS) in Physical Review D
- Vol. 83 (6)
Perturbative expansion ofSupergravityWe characterize the one-loop amplitudes for N=6 and N=4 supergravity in four dimensions. For N=6 we find that the one-loop n-point amplitudes can be expanded in terms of scalar box and triangle functions only. This simplification is consistent with a loop momentum power count of n-3, which we would interpret as being n+4 for gravity with a further -7 from the N=6 superalgebra. For N=4 we find that the amplitude is consistent with a loop momentum power count of n, which we would interpret as being n+4 for gravity with a further -4 from the N=4 superalgebra. In contrast to previous studies we find that the N=4 amplitudes contain noncut-constructible rational terms.
- 7 June 2010
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2010 (6) , 1-24
Augmented recursion for one-loop gravity amplitudes
- 7 June 2010
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2010 (6) , 1-24
Augmented recursion for one-loop gravity amplitudes
- Open Access
Augmented Recursion For One-loop Gravity Amplitudes
We present a semi-recursive method for calculating the rational parts of one-loop gravity amplitudes which utilises axial gauge diagrams to determine the non-factorising pieces of the amplitude. This method is used to compute the one-loop amplitudes M(1-,2+,3+,4+,5+) and M(1-,2+,3+,4+,5+,6+).
Open AccessAugmented Recursion For One-loop Gravity Amplitudes
We present a semi-recursive method for calculating the rational parts of one-loop gravity amplitudes which utilises axial gauge diagrams to determine the non-factorising pieces of the amplitude. This method is used to compute the one-loop amplitudes M(1-,2+,3+,4+,5+) and M(1-,2+,3+,4+,5+,6+).