On-shell recursion for massive fermion currents
We analyze the validity of BCFW recursion relations for currents of n − 2 gluons and two massive quarks, where one of the quarks is off shell and the remaining particles are on shell. These currents are gauge-dependent and can be used as ingredients in the unitarity-based approach to computing one-l...
| Main Authors: | , |
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| Format: | Journal article |
| Language: | English |
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Springer Science and Business Media LLC
2013
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| _version_ | 1797057916666118144 |
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| author | Ochirov, A Britto, R |
| author_facet | Ochirov, A Britto, R |
| author_sort | Ochirov, A |
| collection | OXFORD |
| description | We analyze the validity of BCFW recursion relations for currents of n − 2 gluons and two massive quarks, where one of the quarks is off shell and the remaining particles are on shell. These currents are gauge-dependent and can be used as ingredients in the unitarity-based approach to computing one-loop amplitudes. The validity of BCFW recursion relations is well known to depend on the so-called boundary behavior of the currents as the momentum shift parameter goes to infinity. With off-shell currents, a new potential problem arises, namely unphysical poles that depend on the choice of gauge. We identify conditions under which boundary terms are absent and unphysical poles are avoided, so that there is a natural recursion relation. In particular, we are able to choose a gauge in which we construct a valid shift for currents with at least n − 3 gluons of the same helicity. We derive an analytic formula in the case where all gluons have the same helicity. As by-products, we prove the vanishing boundary behavior of general off-shell objects in Feynman gauge, and we find a compact generalization of Berends-Giele gluon currents with a generic reference spinor. |
| first_indexed | 2024-03-06T19:43:08Z |
| format | Journal article |
| id | oxford-uuid:21592179-2014-4201-a645-9586d0172ff3 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T19:43:08Z |
| publishDate | 2013 |
| publisher | Springer Science and Business Media LLC |
| record_format | dspace |
| spelling | oxford-uuid:21592179-2014-4201-a645-9586d0172ff32022-03-26T11:32:57ZOn-shell recursion for massive fermion currentsJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:21592179-2014-4201-a645-9586d0172ff3EnglishSymplectic ElementsSpringer Science and Business Media LLC2013Ochirov, ABritto, RWe analyze the validity of BCFW recursion relations for currents of n − 2 gluons and two massive quarks, where one of the quarks is off shell and the remaining particles are on shell. These currents are gauge-dependent and can be used as ingredients in the unitarity-based approach to computing one-loop amplitudes. The validity of BCFW recursion relations is well known to depend on the so-called boundary behavior of the currents as the momentum shift parameter goes to infinity. With off-shell currents, a new potential problem arises, namely unphysical poles that depend on the choice of gauge. We identify conditions under which boundary terms are absent and unphysical poles are avoided, so that there is a natural recursion relation. In particular, we are able to choose a gauge in which we construct a valid shift for currents with at least n − 3 gluons of the same helicity. We derive an analytic formula in the case where all gluons have the same helicity. As by-products, we prove the vanishing boundary behavior of general off-shell objects in Feynman gauge, and we find a compact generalization of Berends-Giele gluon currents with a generic reference spinor. |
| spellingShingle | Ochirov, A Britto, R On-shell recursion for massive fermion currents |
| title | On-shell recursion for massive fermion currents |
| title_full | On-shell recursion for massive fermion currents |
| title_fullStr | On-shell recursion for massive fermion currents |
| title_full_unstemmed | On-shell recursion for massive fermion currents |
| title_short | On-shell recursion for massive fermion currents |
| title_sort | on shell recursion for massive fermion currents |
| work_keys_str_mv | AT ochirova onshellrecursionformassivefermioncurrents AT brittor onshellrecursionformassivefermioncurrents |