8 research outputs found
Non-universal gauge boson and the spin correlation of top quark pair production at colliders
In the off-diagonal basis, we discuss the contributions of the non-universal
gauge boson predicted by the topcolor-assisted technicolor () model
to the spin configurations and the spin correlation observable of the top quark
pair production via the process . Our numerical results
show that the production cross sections for the like-spin states, which vanish
in the standard model, can be significantly large as .
With reasonable values of the mass and the coupling parameter
,
exchange can generate large corrections to the spin correlation
observable.Comment: 16 pages, 5 figure
l W nu production at CLIC: a window to TeV scale non-decoupled neutrinos
We discuss single heavy neutrino production e+ e- -> N nu -> l W nu, l = e,
mu, tau, at a future high energy collider like CLIC, with a centre of mass
energy of 3 TeV. This process could allow to detect heavy neutrinos with masses
of 1-2 TeV if their coupling to the electron V_eN is in the range 0.004-0.01.
We study the dependence of the limits on the heavy neutrino mass and emphasise
the crucial role of lepton flavour in the discovery of a positive signal at
CLIC energy. We present strategies to determine heavy neutrino properties once
they are discovered, namely their Dirac or Majorana character and the size and
chirality of their charged current couplings. Conversely, if no signal is
found, the bound V_eN < 0.002-0.006 would be set for masses of 1-2 TeV,
improving the present limit up to a factor of 30. We also extend previous work
examining in detail the flavour and mass dependence of the corresponding limits
at ILC, as well as the determination of heavy neutrino properties if they are
discovered at this collider.Comment: LaTeX 32 pages. Added comments and references. Matches version to
appear in JHE
Unparticle physics in top pair signals at the LHC and ILC
We study the effects of unparticle physics in the pair productions of top
quarks at the LHC and ILC. By considering vector, tensor and scalar unparticle
operators, as appropriate, we compute the total cross sections for pair
production processes depending on scale dimension d_{\U}. We find that the
existence of unparticles would lead to measurable enhancements on the SM
predictions at the LHC. In the case of ILC this may become two orders of
magnitude larger than that of SM, for smaller values of d_\U, a very striking
signal for unparticles.Comment: 19 pages, 9 figures, analysis for ILC has been adde
Unparticle Physics in Single Top Signals
We study the single production of top quarks in and
collisions in the context of unparticle physics through the Flavor Violating
(FV) unparticle vertices and compute the total cross sections for single top
production as functions of scale dimension d_{\U}. We find that among all,
LHC is the most promising facility to probe the unparticle physics via single
top quark production processes.Comment: 14 pages, 10 figure
Unparticle Searches Through Compton Scattering
We investigate the effects of unparticles on Compton scattering, e gamma -> e
gamma based on a future e^+e^- linear collider such as the CLIC. For different
polarization configurations, we calculate the lower limits of the unparticle
energy scale Lambda_U for a discovery reach at the center of mass energies
sqrt(s)=0.5 TeV- 3 TeV. It is shown that, especially, for smaller values of the
mass dimension d, (1 <d <1.3), and for high energies and luminosities of the
collider these bounds are very significant. As a stringent limit, we find
Lambda_U>80 TeV for d<1.3 at sqrt(s)=3 TeV, and 1 ab^(-1) integrated luminosity
per year, which is comparable with the limits calculated from other low and
high energy physics implications.Comment: Table 1 and 2 have been combined as Table 1, references updated,
minor typos have been correcte