3,716 research outputs found
Implications for and Modes from Observed Large
The unexpectedly large branching ratios for decays
could be of gluonic origin. We study the implications for and , where is the pseudoscalar glueball. In the
mechanism proposed by Fritzsch, large branching ratios are predicted for these
modes. The rate is barely within the experimental limit, and
, could be at the 0.1% and 1% level, respectively. Smaller but
less definite results are found for the mechanism of via the
gluon anomaly.Comment: 11 pages, revtex, no fig
Bounds on charged higgs boson in the 2HDM type III from Tevatron
We consider the Two Higgs Doublet Model (2HDM) of type III which leads to
Flavour Changing Neutral Currents (FCNC) at tree level. In the framework of
this model we can use an appropriate form of the Yukawa Lagrangian that makes
the type II model limit of the general type III couplings apparent. This way is
useful in order to compare with the experimental data which is model dependent.
The analytical expressions of the partial width are
derived and we compare with the data available at this energy range. We examine
the limits on the new parameters from the validness of
perturbation theory.Comment: 14 pages, 4 figures, Universidad Nacional de Colombia. typos
correcte
CP Nonconservation in at the Tevatron
The reaction is found to be rather rich in exhibiting
several different types of CP asymmetries. The spin of the top quark plays an
important role. Asymmetries are related to form factors arising from radiative
corrections of the production vertex due to non-standard physics. As
illustrations, effects are studied in two Higgs Doublet Models and in
Supersymmetric Models; asymmetries up to a few percent may be possible.Comment: 14 pages, 3 figures. Note: replaced due to minor problems that
appeared on some postscript previewers. No change in conten
Implications of a W^+W^- (ZZ) - Higgs - t c-bar$ Interaction for e^+e^- -> t c-bar \nu_e \nu_e-bar, t c-bar e^+ e^-, t c-bar Z and for t -> cW^+W^-, cZZ in a Two Higgs Doublet Model
The Standard Model with one extra Higgs doublet may give rise to enhanced
TREE-LEVEL flavor-changing-scalar coupling of a neutral Higgs to a pair of
top-charm quarks. This coupling may drive a large TREE-LEVEL effective
W^+W^-(ZZ) - Higgs - t c-bar interaction. As a result we find that the
reactions e^+e^- -> t c-bar \nu_e \nu_e-bar, t c-bar e^+ e^-, t c-bar Z and the
two rare top decays t -> cW^+W^-, t -> cZZ become very sensitive probes of such
an effective interaction. The most promising ones, e^+e^- -> t c-bar \nu_e
\nu_e-bar, t c-bar e^+ e^-, may yield several hundreds and up to thousands of
such events at the Next Linear Collider with a center of mass energy of
\sqrt{s}=0.5 - 2 TeV if the mass of the lightest neutral Higgs is a few hundred
GeV. The rare decays t -> cW^+W^- and t -> cZZ may be accessible at the LHC if
the mass of the lightest neutral Higgs lies in the narrow window 150 GeV < m_h
< 200 GeV.Comment: 18 pages, plain latex, 12 figures embadded in the text using epsfi
Putting a Squeeze on PubMed
How do you squeeze a 13-hour professional development class on PubMed into a 1-hour staff development workshop? This was the challenge that we, the workshop organizers, faced after completing the PubMed for Trainers class in the summer of 2013.
Although the University hosted the class, there were several UVM librarians who could not attend. The issue facing us was how to effectively pass along the valuable information from the workshop to those absent colleagues.
Our solution was to distill the most essential information from the class into a series of micro-presentations and deliver them using a modified Pecha Kucha format. This poster outlines that process
Discrete Ambiguities in the Measurement of the Weak Phase Gamma
Several time-independent methods have been devised for measuring the phase
gamma of the Cabibbo-Kobayashi-Maskawa unitarity triangle. It is shown that
such measurements generally suffer from discrete ambiguity which is at least
8-fold, not 4-fold as commonly stated. This has serious experimental
implications, which are explored in methods involving B->DK decays. The
measurement sensitivity and new physics discovery potential are estimated using
a full Monte Carlo detector simulation with realistic background estimates.Comment: 15 pages, 2 figures, fixed typ
Lepton Flavor Violation in the Two Higgs Doublet Model type III
We consider the Two Higgs Doublet Model (2HDM) of type III which leads to
Flavour Changing Neutral Currents (FCNC) at tree level in the leptonic sector.
In the framework of this model we can have, in principle, two situations: the
case (a) when both doublets acquire a vacuum expectation value different from
zero and the case (b) when only one of them is not zero. In addition, we show
that we can make two types of rotations for the flavor mixing matrices which
generates four types of lagrangians, with the rotation of type I we recover the
case (b) from the case (a) in the limit , and with the
rotation of type II we obtain the case (b) from (a) in the limit Moreover, two of the four possible lagrangians correspond to the models
of types I and II plus Flavor Changing (FC) interactions. The analitical
expressions of the partial lepton number violating widths and are derived for the cases (a) and (b) and both
types of rotations.In all cases these widths go asymptotically to zero in
the decoupling limit for all Higgses. We present from our analysis upper bounds
for the flavour changing transition and we show that such bounds
are sensitive to the VEV structure and the type of rotation utilized.Comment: 7 pages RevTeX4, 4 figures postscript, new section added and some new
reference
Texture of Yukawa coupling matrices in general two-Higgs-doublet model
We discuss possible parallel textures of the Yukawa coupling matrices in the
generaltwo-Higgs-doublet model (2HDM). In those textures the flavor changing
neutral currentsare naturally suppressed. Motivated by a phenomenologically
successful texturewith four texture zeros in the standard model, we propose a
predictive ansatz for the Yukawa coupling matrices with the same texture in the
general 2HDM. Compared with the six texture-zero based ansatz proposed by Cheng
and Sher, it is in a better agreement with the data of quark mixings and CP
violation. The four texture-zero based ansatz predicts a different hierarchy in
the Yukawa coupling matrix elements. As a consequence, in the lepton sector,
the related Yukawa couplings are less constrained by the experimental upper
bound of , which allows significantly larger predictions for
other processes. The contributions from neutral scalar interactions to the
lepton number violation decay modes are
calculated in both ansatz. It is shown that the predictions from the four
texture-zero based ansatz could be two order of magnitude greater than that
from the six texture-zero based one. The branching ratio of and
can reach and 1.3\tiems 10^{-10}
respectively. The predicted ratio of is also
larger and almost parameter independent. Those differences make the two ansatz
to be easily distinguished by the future experiments.Comment: 12 pages, 2 figure
Time dependent CP asymmetry in decay to probe the origin of CP violation
Since the CP violation in the system has been investigated up to now only
through processes related to the -- mixing, urgently required is
new way of study for the CP violation and establishing its origin in the
system independent of the mixing process. In this work, we explore the
exclusive decay to obtain the time-dependent CP
asymmetry in decay process in the standard model and the
supersymmetric model. We find that the complex RL and RR mass insertion to the
squark sector in the MSSM can lead to a large CP asymmetry in
decay through the gluino-squark diagrams, which is not predicted in the
Standard Model induced by the -- mixing.Comment: 10 pages, 4 eps figure
Polarized Single Top Production at Leptonic Colliders from Broken R Parity Interactions Incorporating CP Violation
The contribution from the R parity violating interactions in the associated
production of a top quark with a charm antiquark is examined for high energy
leptonic colliders. We concentrate on the reactions associated with the
semileptonic top decay. A set of characteristic dynamical distributions for the
signal events is evaluated and the results contrasted against those from the
standard model W-boson pair production background. Next, we turn to a study of
a CP-odd observable, associated with the top spin, which leads to an asymmetry
in the energy distribution of the emitted charged leptons for the pair of
CP-conjugate final states, and . A
non vanishing asymmetry arises from a CP-odd phase, embedded in the R parity
violating coupling constants, through interference terms between the R parity
violating amplitudes at both the tree and loop levels.Comment: revtex file. 17 pages. 7 postscript figures. 1 table. The revised
version includes an estimate of experimental uncertainties. Submitted to
Phys. Rev.
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