14 research outputs found
Constraining Spin-One Color-Octet Resonances Using CDF and ATLAS Data
In this paper, we study the production of spin-one color-octet resonances
(colorons) at hadron colliders in a model independent way. We use dijets data
measured by CDF (at \sqrt{s}=1.96 TeV and L=1.13 TeV and L=315 1/nb) collaborations at the Tevatron and the LHC
respetively to impose limits on the coupling of colorons to fermions. We show
that CDF data still produce the more stringent limits on the coloron coupling
constant.Comment: Version accepted for publication in EPJC. Two paragraphs expanded and
new references adde
Associate Higgs and Gauge Boson Production at Hadron Colliders in a Model with Vector Resonances
Motivated by new models of dynamical electroweak symmetry breaking that
predict a light composite higgs boson, we build an effective lagrangian which
describes the Standard Model (with a light Higgs) and vector resonances. We
compute the cross section for the associate production of a higgs and a gauge
boson. For some values of model parameters we find that the cross section is
significantly enhanced with respect to the Standard Model. This enhancement is
similar at the LHC and the Tevatron for the same range of resonance mass
Axigluon Couplings in the Presence of Extra Color-Octet Spin-One Fields
In this paper, we study how the interaction of the axigluon with quarks is
modified when we introduce new color-octet spin-one fields in a chiral color
model. We show that in this case the strength of this interaction is not
completely determined by the gauge symmetry any more and can be significantly
weaker than the one predicted in the original chiral color model. In this way,
we reinterpret the non-observability of the axigluon at the Tevatron, not as a
limit on the axigluon mass, but as a limit on the strength of the axigluon
coupling to quarks
Top quark effects in composite vector pair production at the LHC
In the context of a strongly coupled Electroweak Symmetry Breaking, composite
light scalar singlet and composite triplet of heavy vectors may arise from an
unspecified strong dynamics and the interactions among themselves and with the
Standard Model gauge bosons and fermions can be described by a Effective Chiral Lagrangian. In this framework, the
production of the and final states at the LHC by
gluon fusion mechanism is studied in the region of parameter space consistent
with the unitarity constraints in the elastic channel of longitudinal gauge
boson scattering and in the inelastic scattering of two longitudinal Standard
Model gauge bosons into Standard Model fermions pairs. The expected rates of
same-sign di-lepton and tri-lepton events from the decay of the
final state are computed and their corresponding backgrounds are estimated. It
is of remarkable relevance that the final state can only be
produced at the LHC via gluon fusion mechanism since this state is absent in
the Drell-Yan process. It is also found that the final state
production cross section via gluon fusion mechanism is comparable with the
Drell-Yan production cross section. The comparison of the
and total cross sections will be crucial for
distinguishing the different models since the vector pair production is
sensitive to many couplings. This will also be useful to determine if the heavy
vectors are only composite vectors or are gauge vectors of a spontaneously
broken gauge symmetry.Comment: 18 pages, 5 tables, 6 figures. Missing figures added. Matches
published versio
Top A_FB at the Tevatron vs. charge asymmetry at the LHC in chiral U(1) flavor models with flavored Higgs doublets
We consider the top forward-backward (FB) asymmetry at the Tevatron and top
charge asymmetry at the LHC within chiral U(1)^\prime models with
flavor-dependent U(1)^\prime charges and flavored Higgs fields, which were
introduced in the ref. [65]. The models could enhance not only the top
forward-backward asymmetry at Tevatron, but also the top charge asymmetry at
LHC, without too large same-sign top pair production rates. We identify
parameter spaces for the U(1)^\prime gauge boson and (pseudo)scalar Higgs
bosons where all the experimental data could be accommodated, including the
case with about 125 GeV Higgs boson, as suggested recently by ATLAS and CMS.Comment: 11 pages, 6 figures, figures and discussion adde
mixing in the neutral channel pion form factor and its role in comparing with spectral functions
We study the effect of rho^0-gamma mixing in e^+e^- to pi^+pi^- and its
relevance for the comparison of the square modulus of the pion from-factor
|F^(e)_pi|^2, as measured in e^+e^- annihilation experiments, and
|F^(tau)_pi|^2 the corresponding quantity obtained after accounting for known
isospin breaking effects by an isospin rotation from the tau-decay spectra.
After correcting the tau data for the missing rho-gamma mixing contribution,
besides the other known isospin symmetry violating corrections, the pi pi I=1
part of the hadronic vacuum polarization contribution to the muon g-2 are fully
compatible between tau based and e^+e^- based evaluations. tau data thus
confirm result obtained with e^+e^- data. Our evaluation based on all e^+e^-
data including more recent BaBar and KLOE data yields a_mu^(had)=690.75(4.72) x
10^{-10} (e^+e^- based), while including tau data we find
a_mu^(had)=690.96(4.65) X 10^{-10} (e^+e^-+tau based). This backs the ~3 sigma
deviation between theory and experiment. For the tau di-pion branching fraction
we find B^{CVC}_{pi pi^0}=25.20 \pm0.0.17\pm0.28 from e^+e^-+CVC, while B_{pi
pi^0}=25.34\pm0.0.06\pm0.08 is evaluated directly from the tau spectra.Comment: 18 pages, 18 figures, Fig.2 added,Refs. 3,12,14 added, text referring
to Refs. 13,14 corrected, typos correcte