97 research outputs found
One-loop effective lagrangians after matching
We discuss the limitations of the covariant derivative expansion prescription
advocated to compute the one-loop Standard Model (SM) effective lagrangian when
the heavy fields couple linearly to the SM. In particular, one-loop
contributions resulting from the exchange of both heavy and light fields must
be explicitly taken into account through matching because the proposed
functional approach alone does not account for them. We review a simple case
with a heavy scalar singlet of charge to illustrate the argument. As two
other examples where this matching is needed and this functional method gives a
vanishing result, up to renormalization of the heavy sector parameters, we
re-evaluate the one-loop corrections to the T--parameter due to a heavy scalar
triplet with vanishing hypercharge coupling to the Brout-Englert-Higgs boson
and to a heavy vector-like quark singlet of charged mixing with the top
quark, respectively. In all cases we make use of a new code for matching
fundamental and effective theories in models with arbitrary heavy field
additions.Comment: 22 pages; v2: comments and references added; v3: published version,
typos correcte
Tau Custodian searches at the LHC
The tau lepton can be more composite than naively expected in models of
strong electroweak symmetry breaking with tri-bimaximal lepton mixing. New
leptonic resonances required by custodial symmetry, the tau custodians, can
then be the first signal of this lepton flavor realization. Tau custodians can
be very light, decaying almost exclusively into taus. The LHC reach for these
new leptons is up to masses of 240, 480 and 720 GeV for sqrt{s}=14 TeV and an
integrated luminosity of 30, 300 and 3000 fb^{-1}, respectively. Our analysis
can be extended to any pair produced particles decaying mostly into taus and
Standard Model bosons.Comment: 12 pages, 2 figure
Four and two-lepton signals of leptophilic gauge interactions at large colliders
Many Standard Model extensions can contribute to four-lepton signals at large
colliders. We review the particular case of leptophilic interactions eventually
observable at the LHC and the ILC, paying special attention to the addition of
a new vector boson coupled to muon minus tau lepton number, ,
and emphasizing the prospects at a very large hadron collider with
100 TeV. We also discuss in this case the new contribution to two-lepton
(Drell-Yan) production when the new leptophilic interaction has a non-vanishing
kinetic mixing with the SM.Comment: 12 pages, 5 figures, Contribution to the Proceedings of the Corfu
Summer Institute 201
Light neutrino propagation in matter without heavy neutrino decoupling
We review the propagation of light neutrinos in matter assuming that
their mixing with heavy neutrinos is close to present experimental limits.
The phenomenological implications of the non-unitarity of the light neutrino
mixing matrix for neutrino oscillations are discussed. In particular we
show that the resonance effect in neutrino propagation in matter persists,
but for slightly modified values of the parameters and with the maximum
reduced by a small amount proportional to the mixing between light and
heavy neutrinos squared
Effective description of brane terms in extra dimensions
We study how theories defined in (extra-dimensional) spaces with localized
defects can be described perturbatively by effective field theories in which
the width of the defects vanishes. These effective theories must incorporate a
``classical'' renormalization, and we propose a renormalization prescription a
la dimensional regularization for codimension 1, which can be easily used in
phenomenological applications. As a check of the validity of this setting, we
compare some general predictions of the renormalized effective theory with
those obtained in a particular ultraviolet completion based on deconstruction.Comment: 28 page
Heavy neutrino signals at large hadron colliders
We study the LHC discovery potential for heavy Majorana neutrino singlets in
the process pp -> W+ -> l+ N -> l+ l+ jj (l=e,mu) plus its charge conjugate.
With a fast detector simulation we show that backgrounds involving two
like-sign charged leptons are not negligible and, moreover, they cannot be
eliminated with simple sequential kinematical cuts. Using a likelihood analysis
it is shown that, for heavy neutrinos coupling only to the muon, LHC has 5
sigma sensitivity for masses up to 200 GeV in the final state mu+- mu+- jj.
This reduction in sensitivity, compared to previous parton-level estimates, is
driven by the ~ 10^2-10^3 times larger background. Limits are also provided for
e+- e+- jj and e+- mu+- jj final states, as well as for Tevatron. For heavy
Dirac neutrinos the prospects are worse because backgrounds involving two
opposite charge leptons are much larger. For this case, we study the
observability of the lepton flavour violating signal e+- mu-+ jj. As a
by-product of our analysis, heavy neutrino production has been implemented
within the ALPGEN framework.Comment: Latex 36 pages, 49 PS figures. Major extension incorporating analysis
for e+- e+-, e+- mu+- and e+- mu-+ final states. Final version to appear in
JHE
Bulk fields with general brane kinetic terms
We analyse the effect of general brane kinetic terms for bulk scalars,
fermions and gauge bosons in theories with extra dimensions, with and without
supersymmetry. We find in particular a singular behaviour when these terms
contain derivatives orthogonal to the brane. This is brought about by
divergences arising at second and higher order in perturbation
theory. We argue that this behaviour can be smoothed down by classical
renormalization.Comment: 31 pages, v2 few typos correcte
Similarity of sediment transport by water and air currents.
Massachusetts Institute of Technology. Dept. of Civil Engineering. Thesis. 1970. Civ.E.MICROFICHE COPY ALSO AVAILABLE IN BARKER ENGINEERING LIBRARY.Bibliography: leaves 98-104.Civ.E
Lepton number violation and scalar searches at the LHC
We review the SM extensions with scalar multiplets including doubly-charged components eventually observable as di-leptonic resonances at the LHC. Special emphasis is paid to the limits on LNV implied by doubly-charged scalar searches at the LHC, and to the characterization of the multiplet doubly-charged scalars belong to if they are observed to decay into same-sign charged lepton pairs
Diseño de adoquines de arcilla, con adición de fibras de bambú para mejorar la resistencia a la compresión, Lamas 2020
Esta investigación “Diseño de adoquines de arcilla, con adición de fibras de bambú
para mejorar la resistencia a la compresión, Lamas 2020” tiene como objeto utilizar
proporciones de fibra de bambú, para tener como resultado un diseño óptimo con
mejor resistencia a compresión, se utilizó material de la ciudad de Tarapoto, con
arcilla de la cantera “Lagartococha”, los bambús se utilizaron de las zonas aledañas
a la ciudad de Tarapoto. Para poder obtener el diseño del adoquín de arcilla, se
diseñó un molde de acero, de 20x10x6 cm, establecidas por la norma para tránsito
peatonal y vehicular liviano, con la fibra de bambú se cortó y seco, pasando por
procesos de molido hasta obtener fibra vegetal; como muestra patrón se hicieron
10 adoquines con 0% de adición de fibra de bambú y 40 adoquines con adición de
fibra de bambú al 0.5%,1%, 1.5% y 2%, haciendo los estudios y análisis de estas
muestras a los 7 y 14 días. Para el proceso de elaboración del diseño del adoquín
de arcilla se mezcló de forma homogénea la arcilla con el agua para luego agregar
la fibra de bambú, colocarlo en el molde y por último pasar por el proceso de
cocción
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