128 research outputs found
Spin-dependent energy distribution of B-hadrons from polarized top decays considering the azimuthal correlation rate
In our previous work, we studied the polar distribution of the scaled energy
of bottom-flavored hadrons from polarized top quark decays
, using two different helicity
coordinate systems. Basically, the energy distributions are governed by the
unpolarized, polar and azimuthal rate functions which are related to the
density matrix elements of the decay . Here we
present, for the first time, the analytical expressions for the radiative corrections to the differential azimuthal decay rates
of the partonic process in two helicity
systems, which are needed to study the azimuthal distribution of the energy
spectrum of the B-hadron produced in polarized top quark decays. Our
predictions of the hadron energy distributions enable us to deepen our
knowledge of the hadronization process and to determine the polarization states
of top quarks
Charged Higgs production from polarized top-quark decay in the 2HDM considering the general-mass variable-flavor-number scheme
Charged Higgs bosons are predicted by some non-minimal Higgs
scenarios, such as models containing Higgs triplets and two-Higgs-doublet
models, so that the experimental observation of these bosons would indicate
physics beyond the Standard Model. In the present work, we introduce a new
channel to indirect search for the charged Higgses through the hadronic decay
of polarized top quarks where a top quark decays into a charged Higgs and
a bottom-flavored hadron via the hadronization process of the produced
bottom quark, . To obtain the energy
spectrum of produced -hadrons we present, for the first time, an analytical
expression for the corrections to the differential decay
width of the process in the presence of a massive b-quark
in the General-Mass Variable-Flavor-Number Scheme (GM-VFNS). We find that the
most reliable predictions for the B-hadron energy spectrum are made in the
GM-VFN scheme, specifically, when the Type-II 2HDM scenario is concerned
Hadron energy spectrum in polarized top quark decays considering the effects of hadron and bottom quark masses
We present the analytical expressions for the next-to-leading order
corrections to the partial decay width , followed
by , for nonzero b-quark mass () in the
fixed-flavor-number scheme (FFNs). To make the predictions for the energy
distribution of outgoing hadrons , as a function of the normalized
-energy fraction , we apply the general-mass variable-flavor-number
scheme (GM-VFNs) in a specific helicity coordinate system where the
polarization of top quark is evaluated relative to the b-quark momentum. We
also study the effects of gluon fragmentation and finite hadron mass on the
hadron energy spectrum so that hadron masses are responsible for the low-
threshold. In order to describe both the b-quark and the gluon hadronizations
in top decays we apply realistic and nonperturbative fragmentation functions
extracted through a global fit to annihilation data from CERN LEP1 and
SLAC SLC by relying on their universality and scaling violations
Next-to-leading order corrections to the spin-dependent energy spectrum of hadrons from polarized top quark decay in the general two Higgs doublet model
In recent years, searches for the light and heavy charged Higgs bosons have
been done by the ATLAS and the CMS collaborations at the Large Hadron Collider
(LHC) in proton-proton collision. Nevertheless, a definitive search is a
program that still has to be carried out at the LHC. The experimental
observation of charged Higgs bosons would indicate physics beyond the Standard
Model. In the present work, we study the scaled-energy distribution of
bottom-flavored mesons () inclusively produced in polarized top quark decays
into a light charged Higgs boson and a massless bottom quark at next-to-leading
order in the two-Higgs-doublet model; . This
spin-dependent energy distribution is studied in a specific helicity coordinate
system where the polarization vector of the top quark is measured with respect
to the direction of the Higgs momentum. The study of these energy distributions
could be considered as a new channel to search for the charged Higgs bosons at
the LHC. For our numerical analysis and phenomenological predictions, we
restrict ourselves to the unexcluded regions of the MSSM
parameter space determined by the recent results of the CMS \cite{CMS:2014cdp}
and ATLAS \cite{TheATLAScollaboration:2013wia} collaborations.Comment: 10 pages, 6 figures. arXiv admin note: text overlap with
arXiv:1611.0801
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