1,728 research outputs found
The parameter at three loops and elliptic integrals
We describe the analytic calculation of the master integrals required to
compute the two-mass three-loop corrections to the parameter. In
particular, we present the calculation of the master integrals for which the
corresponding differential equations do not factorize to first order. The
homogeneous solutions to these differential equations are obtained in terms of
hypergeometric functions at rational argument. These hypergeometric functions
can further be mapped to complete elliptic integrals, and the inhomogeneous
solutions are expressed in terms of a new class of integrals of combined
iterative non-iterative nature.Comment: 14 pages Latex, 7 figures, to appear in the Proceedings of "Loops and
Legs in Quantum Field Theory - LL 2018", 29 April - 4 May 2018, Po
Arkiv og Publikum. Indledning til en Diskussion i Personalhistorisk Samfund den 4. Marts 1919.
Perturbative dynamics of matrix string for the membrane
Recently Sekino and Yoneya proposed a way to regularize the world volume
theory of membranes wrapped around by matrices and showed that one
obtains matrix string theory as a regularization of such a theory. We show that
this correspondence between matrix string theory and wrapped membranes can be
obtained by using the usual M(atrix) theory techniques. Using this
correspondence, we construct the super-Poincare generators of matrix string
theory at the leading order in the perturbation theory. It is shown that these
generators satisfy 10 dimensional super-Poincar\'e algebra without any anomaly.Comment: 23 pages, 1 figur
The process gg -> WW as a background to the Higgs signal at the LHC
The production of W pairs from the one-loop gluon fusion process is studied.
Formulas are presented for the helicity amplitudes keeping the top mass finite,
but all other quark masses zero. The correlations among the leptons coming from
the W bosons are kept. The contribution of this background to the Higgs boson
search in the WW decay mode at the LHC is estimated by applying the cuts
foreseen in experimental searches using the PYTHIA Monte Carlo program.
Kinematic distributions for the final state leptons are compared to those of
the Higgs boson signal and of the q qbar -> WW background. After applying final
cuts, the gg background is found to be large, at the level of 35% of the q qbar
background.The characteristics of the gg background are very similar to those
of the signal. Therefore, an experimental normalization of this background
component appears to be very difficult and the uncertainty must largely be
determined by theory. As a result, the significance of a Higgs signal in the gg
-> H -> WW mode at the LHC is reduced.Comment: 24 pages, 4 figure
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