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Hadronic production of a Higgs boson in association with two jets at ...

Hadronic production of a Higgs boson in association with two jets at ...

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4.2. Cut-Constructible Contributions 120211123φφφ4 C 3;φ34|1|2 C 3;φ4|12|3 C 3;φ4|1|23344(a) (b) 2 (c)12 31 123442334φC 3;φ|1|234C 3;φ|123|4C 3;φ|12|34φφ(d) (e) (f)Figure 4.2: The various triangle <strong>in</strong>tegral topologies th<strong>at</strong> appear for A (1)4 (φ, 1, 2, 3, 4).From the six topologies we must also <strong>in</strong>clude cyclic permut<strong>at</strong>ions <strong>of</strong> the four gluons.(a) has one <strong>of</strong>f-shell leg, (b)-(e) have <strong>two</strong> <strong>of</strong>f-shell legs while <strong>in</strong> (f) all legs are <strong>of</strong>f-shell.the correct <strong>in</strong>frared behaviour by comb<strong>in</strong><strong>in</strong>g <strong>with</strong> the box pieces to gener<strong>at</strong>e thefollow<strong>in</strong>g pole structure,A (1) (φ, 1 + , 2 − , 3 − , 4 − ) = −A (0) (φ, 1 + , 2 − , 3 − , 4 − ) c Γǫ 24∑( µ2i=1−s ii+1) ǫ+ O(ǫ 0 ). (4.18)This rel<strong>at</strong>ion holds for arbitrary external helicities [107,108,206]. We computed thecoefficients <strong>of</strong> all one- and <strong>two</strong>-mass triangles and explicitly verified eq. (4.18). Thenon-trivial rel<strong>at</strong>ionship between the triangle and box coefficients provides a strongcheck <strong>of</strong> our calcul<strong>at</strong>ion. However, s<strong>in</strong>ce we now wish to obta<strong>in</strong> compact results forthe four gluon amplitude, we f<strong>in</strong>d it more compact to present the f<strong>in</strong>al answer <strong>in</strong>a basis free <strong>of</strong> one- and <strong>two</strong>-mass triangles. Th<strong>at</strong> is, we choose to expand the box<strong>in</strong>tegral functions <strong>in</strong>to divergent and f<strong>in</strong>ite pieces, comb<strong>in</strong><strong>in</strong>g the divergent pieces<strong>with</strong> the one- and <strong>two</strong>- mass triangles to form (4.18) and giv<strong>in</strong>g explicit results forthe f<strong>in</strong>ite pieces <strong>of</strong> the box functions.A new fe<strong>at</strong>ure <strong>in</strong> the φ-NMHV amplitudes is the presence <strong>of</strong> three-mass triangles,shown <strong>in</strong> Fig. 4.2(f). In previous calcul<strong>at</strong>ions [106–109, 206] the external gluonhelicities prevented these contributions from occurr<strong>in</strong>g.

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