40 research outputs found
Extension of non-minimal derivative coupling theory and Hawking radiation in black-hole spacetime
We study the greybody factor and Hawking radiation with a non-minimal
derivative coupling between the scalar field and the curvature in the
background of the slowly rotating Kerr-Newman black hole.
Our results show that both the absorption probability and luminosity of
Hawking radiation of the scalar field increase with the coupling.
Moreover, we also find that for the weak coupling , the
absorption probability and luminosity of Hawking radiation decrease when the
black hole's Hawking temperature decreases; while for stronger coupling
, the absorption probability and luminosity of Hawking radiation
increase on the contrary when the black hole's Hawking temperature decreases.
This feature is similar to the Hawking radiation in a -dimensional static
spherically-symmetric black hole surrounded by quintessence \cite{chensong}.Comment: 17 pages, 6 figures, 1 table, Title changed, Appendix changed,
accepted by JHE
Complete off-shell effects in top quark pair hadroproduction with leptonic decay at next-to-leading order
Results for next-to-leading order QCD corrections to the pp(p\bar{p}) -> t
\bar{t} -> W^+W^- b\bar{b} -> e^{+} \nu_{e} \mu^{-} \bar{\nu}_{\mu} b \bar{b}
+X processes with complete off-shell effects are presented for the first time.
Double-, single- and non-resonant top contributions of the order
{\cal{O}}(\alpha_{s}^3 \alpha^4) are consistently taken into account, which
requires the introduction of a complex-mass scheme for unstable top quarks.
Moreover, the intermediate W bosons are treated off-shell. Comparison to the
narrow width approximation for top quarks, where non-factorizable corrections
are not accounted for is performed. Besides the total cross section and its
scale dependence, several differential distributions at the TeVatron run II and
the LHC are given. In case of the TeVatron the forward-backward asymmetry of
the top is recalculated afresh. With inclusive selection cuts, the
forward-backward asymmetry amounts to A^{t}_{FB} = 0.051 +/- 0.0013.
Furthermore, the corrections with respect to leading order are positive and of
the order 2.3% for the TeVatron and 47% for the LHC. A study of the scale
dependence of our NLO predictions indicates that the residual theoretical
uncertainty due to higher order corrections is 8% for the TeVatron and 9% for
the LHC.Comment: 35 pages, 39 figures, 3 tables. References and note added, version to
appear in JHE