3,374 research outputs found
Doubly Charged Higgs Production at Future Colliders
The Higgs sector of the standard model can be extended by introducing an
Higgs triplet to generate the tiny neutrino masses in the
framework of type-II seesaw mechanism. In this paper, we study the pair
production of the introduced Higgs triplet at future colliders. The
corresponding production cross sections via vector boson fusion process at
FCC-ep and ILCFCC are predicted, where the production of a pair of
doubly charged Higgs is found to be dominant and then used to investigate the
collider phenomenology of the Higgs triplet. Depending on the size of the Higgs
triplet vacuum expectation value, the doubly charged Higgs may decay into a
pair of same-sign charged leptons or a pair of same-sign bosons. In order
to explore the discovery potential of the doubly charged Higgs at future
colliders, we discuss these two decay scenarios in detail and show
respectively the detection sensitivity on the mass of the doubly charged Higgs.Comment: 21 pages, 9 figure
The next-to-next-to-leading order soft function for top quark pair production
We present the first calculation of the next-to-next-to-leading order
threshold soft function for top quark pair production at hadron colliders, with
full velocity dependence of the massive top quarks. Our results are fully
analytic, and can be entirely written in terms of generalized polylogarithms.
The scale-dependence of our result coincides with the well-known two-loop
anomalous dimension matrix including the three-parton correlations, which at
the two-loop order only appear when more than one massive partons are involved
in the scattering process. In the boosted limit, our result exhibits the
expected factorization property of mass logarithms, which leads to a consistent
extraction of the soft fragmentation function. The next-to-next-to-leading
order soft function obtained in this paper is an important ingredient for
threshold resummation at the next-to-next-to-next-to-leading logarithmic
accuracy.Comment: 34 pages, 9 figures; v2: added references, matches the published
versio
from the semileptonic decay and the properties of the meson distribution amplitude
The improved QCD light-cone sum rule (LCSR) provides an effective way to deal
with the heavy-to-light transition form factors (TFFs). Firstly, we adopt the
improved LCSR approach to deal with the TFF up to twist-4
accuracy. Due to the elimination of the most uncertain twist-3 contribution and
the large suppression of the twist-4 contribution, the obtained LCSR shall
provide us a good platform for testing the -meson leading-twist DA. For the
purpose, we suggest a new model for the -meson leading-twist DA
(), whose longitudinal behavior is dominantly determined by a
parameter . Moreover, we find its second Gegenbauer moment .
Varying within certain region, one can conveniently mimic the -meson DA
behavior suggested in the literature. Inversely, by comparing the estimations
with the experimental data on the -meson involved processes, one can get a
possible range for the parameter and a determined behavior for the
-meson DA. Secondly, we discuss the TFF at the maximum recoil
region and present a detailed comparison of it with the pQCD estimation and the
experimental measurements. Thirdly, by applying the LCSR on , we
study the CKM matrix element \Vcb together with its uncertainties by adopting
two types of processes, i.e. the -type and the -type.
It is noted that a smaller shows a better agreement with the
experimental value on \Vcb. For example, for the case of , we obtain
and , whose first (second)
uncertainty comes from the squared average of the mentioned theoretical
(experimental) uncertainties.Comment: 13 pages, 10 figures. Reference updated and discussion improved. To
be published in Nucl.Phys.
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