6,431 research outputs found
LFV couplings of the extra gauge boson Z' and leptonic decay and production of pseudoscalar mesons
Considering the constraints of the lepton flavor violating (LFV) processes
and on the LFV couplings
, in the contexts of the models, the left-right
(LR) models, the "alternative" left-right (ALR) models and the 331 models, we
investigate the contributions of the extra gauge boson to the decay rates
of the processes ,
and with and
. Our numerical results show that the maximal values of the branching
ratios for these processes are not dependent on the mass at
leader order. The extra gauge boson predicted by the models
can make the maximum value of the branching ratio
reach . All
models considered in this paper can produce significant contributions to the
process . However, the value of
is far below its corresponding experimental upper bound.Comment: 14 pages, 2 figures; matches published versio
Understanding the internal structures of the , , and
We investigate the newly observed and based on the
diquark-antidiquark configuration within the framework of QCD sum rules. Both
of them may be interpreted as the -wave tetraquark states
of , but with opposite color structures, which is remarkably similar
to the result obtained in Ref.~\cite{Chen:2010ze} that the and
can be both interpreted as the -wave tetraquark
states of , also with opposite color structures. However, the
extracted masses and these suggested assignments to these states do depend
on these running quark masses where m_s (2 \mbox{ GeV}) = 95 \pm 5 MeV and
GeV. As a byproduct, the masses of the
hidden-bottom partner states of the and are extracted to be
both around 10.64 GeV, which can be searched for in the
invariant mass distribution.Comment: 6 pages, 4 figures. Accepted by Eur. Phys. J.
QCD sum rule Study of the
We systematically construct six-quark local interpolating
currents without derivative operators. We discuss the best choice of operator,
and select three - like operators to perform QCD sum rule
analyses to calculate the mass of the . The mass extracted from this
analysis is GeV, consistent with the mass
observed by the WASA detector at COSY. We also obtain a sum-rule lower mass
bound GeV. We also consider the effect of mixing of singlet
dibaryon fields with the same quantum numbers, and perform the QCD sum rule
analysis of the mixed interpolating current and extract the mass of the
and its lower mass bound. With optimized mixing parameters, we find
that the mixed current does not change the numerical result significantly.Comment: 9 pages, 4 figure
- …