Soft-gluon corrections in FCNC top-quark production via anomalous gluon couplings

We present a calculation of soft-gluon corrections in flavor-changing neutral current top-quark production via anomalous $t$-$q$-$g$ couplings. The soft anomalous dimension matrix is explicitly calculated at one-loop accuracy. This calculation allows threshold resummation at next-to-leading-logarithm accuracy. We also derive expressions for the soft-gluon corrections at next-to-leading order and at next-to-next-to-leading order.

Figure 1

The six diagrams represent the various tree-level processes for $gu\to tg$. There are two $s$-channel interactions and three $t$-channel interactions. The final diagram represents an atypical four-point interaction.

Figure 2

One-loop eikonal diagrams 1 (left) and 2 (right).

Figure 3

One-loop eikonal diagrams 3 (left) and 4 (right).

Figure 4

One-loop eikonal diagrams 5 (left) and 6 (right).

Figure 5

The scale dependence for $gu\to tg$ in $pp$ collisions at 7 TeV LHC energy.

Figure 6

The scale dependence for $gu\to tg$ in $pp$ collisions at 14 TeV LHC energy.

Figure 7

Eikonal rules for incoming (top four graphs) and for outgoing (bottom four graphs) quarks and antiquarks.

Figure 8

Eikonal rules for incoming (top four graphs) and for outgoing (bottom four graphs) gluons.