236,694 research outputs found

    The Intrinsic Coupling in Integrable Quantum Field Theories

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    The intrinsic 4-point coupling, defined in terms of a truncated 4-point function at zero momentum, provides a well-established measure for the interaction strength of a QFT. We show that this coupling can be computed non-perturbatively and to high accuracy from the form factors of an (integrable) QFT. The technique is illustrated and tested with the Ising model, the XY-model and the O(3) nonlinear sigma-model. The results are compared to those from high precision lattice simulations.Comment: 69 pages, Late

    A QUDA-branch to compute disconnected diagrams in GPUs

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    Although QUDA allows for an efficient computation of many QCD quantities, it is surprinsingly lacking tools to evaluate disconnected diagrams, for which GPUs are specially well suited. We aim to fill this gap by creating our own branch of QUDA, which includes new kernels and functions required to calculate fermion loops using several methods and fermionic regularizations.Comment: 7 pages, 4 figures. Proceedings of the talk given during the code session of the 31st International Symposium on Lattice Field Theory, July 29 - August 3, 2013, Mainz, Germany. Added a missing reference (number [4]

    Higher Derivative Terms from Threebranes in F Theory

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    The computation of higher derivative corrections to the low energy effective actions of N=2{\cal N}=2 gauge theories is considered. In particular, higher derivative corrections are computed for four dimensional N=2{\cal N}=2 super Yang-Mills theory with gauge group SU(2) and Nf=4N_f=4 hypermultiplets in the fundamental representation. The four derivative terms computed in an approach which realizes the gauge theory as the world volume theory of three branes in F theory are in agreement with the field theory result.Comment: 13 pages, uses harvmac, presentation improved, references adde
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