25 research outputs found
KK-parity non-conservation in UED confronts LHC data
Kaluza-Klein (KK) parity can be violated in five-dimensional universal extra
dimensional model with boundary-localized (kinetic or mass) terms (BLTs) at the
fixed points of orbifold. In this framework we study the resonant
production of Kaluza-Klein excitations of the neutral electroweak gauge bosons
at the LHC and their decay into an electron-positron pair or a muon-antimuon
pair. We use the results (first time in our knowledge) given by the LHC
experiment to constrain the mass range of the first KK-excitation of the
electroweak gauge bosons (). It is interesting to
note that the LHC result puts an upper limit on the masses of the
KK-leptons for positive values of BLT parameters and depending upon the mass of
resonance.Comment: 14 pages, 4 figures, minor changes in the text and references added,
to appear in EPJ
Looking for in non-minimal Universal Extra Dimensional model
Non-vanishing boundary localised terms significantly modify the mass spectrum
and various interactions among the Kaluza-Klein excited states of 5-Dimensional
Universal Extra Dimensional scenario. In this scenario we compute the
contributions of Kaluza-Klein excitations of gauge bosons and third generation
quarks for the decay process incorporating
next-to-leading order QCD corrections. We estimate branching ratio as well as
Forward Backward asymmetry associated with this decay process. Considering the
constraints from some other observables and electroweak precision
data we show that significant amount of parameter space of this scenario has
been able to explain the observed experimental data for this decay process.
From our analysis we put lower limit on the size of the extra dimension by
comparing our theoretical prediction for branching ratio with the corresponding
experimental data. Depending on the values of free parameters of the present
scenario, lower limit on the inverse of the radius of compactification
() can be as high as GeV. {Even this value could slightly be
higher if we project the upcoming measurement by Belle II experiment.}
Unfortunately, the Forward Backward asymmetry of this decay process would not
provide any significant limit on in the present model.Comment: 47 pages, 6 Figures, 3 Tables, typos corrected, references added,
remarks added, version accepted in Physical Review
A note on gauge-fixing in the electroweak sector of nmUED
Electroweak observables are highly sensitive to the loop corrections.
Therefore, a proper gauge-fixing mechanism is always needed to define the
propagators which are involved in Feynman loop amplitude. With this spirit we
compute gauge-fixing mechanism in five dimensional (5-D) Universal
Extra-Dimensional (UED) model with boundary localised terms (BLTs). These BLTs
are not 5-D operators in four-dimensional (4-D) effective theory but some sort
of boundary conditions on the respective fields at the fixed points of
orbifold. Furthermore, these BLTs non-trivially modify the
Kaluza-Klein (KK) spectra and some of the interactions among the KK-excitations
compared to the minimal UED (mUED), in which, these BLTs are absent. In this
note we calculate the gauge-fixing mechanism in the electroweak sector of such
non-trivial UED scenario. Moreover, we discuss the composition and masses of
Goldstone and any physical scalar that emerge after the symmetry breaking in
this set up with different choices of gauge.Comment: 9 pages, title has been changed, matched with the published versio
The impact of nonminimal Universal Extra Dimensional model on transitions
We measure the impact of nonvanishing boundary localised terms on transitions in five-dimensional Universal Extra Dimensional scenario where
masses and coupling strengths of several interactions of Kaluza-Klein modes are
significantly modified with respect to the minimal counterpart. In such
scenario we estimate the Kaluza-Klein contributions of quarks, gauge bosons and
charged Higgs by evaluating the one-loop box diagrams that are responsible for
the transitions. Using the loop function (obtained from one-loop
box diagrams) we determine several important elements that are involved in
Wolfenstein parametrisation. Moreover, with these elements we also study the
geometrical shape of unitarity triangle. Besides, we compute the quantity
scaled by the corresponding Standard Model value. Outcomes of our
theoretical predictions have been compared to the allowed ranges of the
corresponding observables simultaneously. Our current analysis shows that,
depending on the parameters in this scenario the lower limit on the inverse of
the radius of compactification can reach to an appreciable large value
( TeV or even higher).Comment: A table added, some clarifying remarks added and version accepted for
publication in The European Physical Journal