124 research outputs found
The renormalized Hamiltonian truncation method in the large expansion
Hamiltonian Truncation Methods are a useful numerical tool to study strongly
coupled QFTs. In this work we present a new method to compute the exact
corrections, at any order, in the Hamiltonian Truncation approach presented by
Rychkov et al. in Refs. [1-3]. The method is general but as an example we
calculate the exact and some of the contributions for the
theory in two dimensions. The coefficients of the local expansion calculated in
Ref. [1] are shown to be given by phase space integrals. In addition we find
new approximations to speed up the numerical calculations and implement them to
compute the lowest energy levels at strong coupling. A simple diagrammatic
representation of the corrections and various tests are also introduced.Comment: JHEP version, typos fixed in Appendix and eq. (23
Higgs Couplings in Composite Models
We study Higgs couplings in the composite Higgs model based on the coset
SO(5)/SO(4). We show that the couplings to gluons and photons are insensitive
to the elementary-composite mixings and thus not affected by light fermionic
resonances. Moreover, at leading order in the mixings the Higgs couplings to
tops and gluons, when normalized to the Standard Model (SM), are equal. These
properties are shown to be direct consequences of the Goldstone symmetry and of
the assumption of partial compositeness. In particular, they are independent of
the details of the elementary-composite couplings and, under the further
assumption of CP invariance, they are also insensitive to derivative
interactions of the Higgs with the composite resonances. We support our
conclusions with an explicit construction where the SM fermions are embedded in
the 14 dimensional representation of SO(5).Comment: 13 pages, 3 figures, 2 tables; v2: small improvements in the
discussion, results unchanged; typos corrected; one reference added. Matches
version submitted to PR
Manejo integrado de Bromus diandrus. Resultados de tres años de ensayos
En el presente trabajo se aportan los resultados obtenidos
tras tres años de ensayos sobre estrategias de control de Bromus diandrus
en una zona en la que se cultivan principalmente cereales en siembra
directa. Se han rotado, durante los tres años, tres cultivos diferentes
con diversos herbicidas para cada uno, lo cual ha permitido diversificar
tanto las fechas de siembra, de octubre a enero, como los herbicidas utilizados.
El guisante y la cebada, por la siembra tardía, han permitido disminuir
las infestaciones de bromo. Además, la eficacia de los herbicidas
selectivos del guisante es significativamente superior a la de los autorizados
en trigo. El rendimiento del trigo en “rotación” ha sido muy superior
al del trigo en “monocultivo” considerado como estándar. El rendimiento
del guisante ha sido aproximadamente del 55% del trigo en rotación, lo
que garantiza su rentabilidad económica. También el rendimiento de la
cebada, sembrada tras guisante, ha sido muy superior al del trigo.In this paper the results of a
three year experiment for Bromus diandrus management strategies, carried
out in a winter cereal area under no-tillage, are provided. The managements
combine three different crops during three years with various
herbicides for each crop. Sowing dates have been diversified from October
to January, as well as the herbicides. Field pea and barley, by the
fact that are sown late in the season, have reduced Brome infestations.
Moreover, the efficacy of selective herbicides for field pea is significantly
higher than those authorized in wheat. Wheat yield in “rotation” has
been much higher than in “monocrop”. Field pea yield was about 55%
of wheat in rotation, ensuring its profitability. Yield for barley sown after
pea, was also much higher than for wheat
Bromoxynil sensitivity study of a "Papaver rhoeas" L. biotype
“Papaver rhoeas” es la única mala hierba dicotiledónea que presenta resistencia múltiple en España. Se han detectado biotipos resistentes a tribenuron-metil (inhibidor de la acetolactato sintasa) y 2,4-D (auxina sintética). En la zona cerealista del norte de España ha habido problemas en el control de esta mala hierba con mezclas que contenían bromoxinil. En el presente trabajo se ha ensayado, con curvas dosis-respuesta, el efecto de este producto en dos lotes de semillas de un biotipo que no fue controlado en campo por mezclas con bromoxinil en dos años consecutivos. Los lotes B-0313 y B-0314 fueron controlados cuando el bromoxinil se aplicó a la fenología recomendada. Se observó cierto desplazamiento de la curva cuando las plantas de amapola se aplicaron a fenologías más avanzadas.“Papaver rhoeas” is the unique dicot weed that has multiple
resistance in Spain. Resistant biotypes have been detected to tribenuron-
methyl (acetolactate synthase inhibitor) and 2,4-D (synthetic auxin).
In the cereal area of northern Spain there have been problems to
control this weed with mixtures containing bromoxynil. In the present
work we have tested the effect of this product in one biotype that was
not controlled in the field by herbicide mixtures with bromoxynil. The lots B-0313 and B-0314 were controlled with bromoxynil applied at the
recommended phenology. A shift in the curve was observed when corn
poppy plants were applied in more advanced phenologies
Validación durante cuatro años de un sistema experto para optimizar el uso de herbicidas en cereales de invierno en condiciones agronómicas españolas
CPOWeeds is a version of Danish Crop Protection online adjusted to conditions in North-eastern Spain. The predicted efficacies and the yield obtained with CPOWeeds were validated in winter cereal field trials from 2010 to 2013. The predictions from CPOWeeds were compared to the actually achieved efficacies in the field trials for the nine weed species at different developmental stages and for 84.2% of the comparisons the obtained efficacies were equal to or higher than predicted. It was concluded that the use of CPOWeeds allowed optimisation of the herbicide application with a very high robustness. The recommendations were satisfactorily for the conditions of the Northeast of Spain and have the potential to decrease the amount of applied herbicides by at least 30%. Therefore, it can be an important tool in Integrated Weed Management.El CPOWeeds es una versión del Crop Protection Online danés puesto a punto para las condiciones del noroeste (NE) de España. Las eficacias predichas por el programa se han validado en ensayos en cereal de invierno desde 2010 a 2013. Las predicciones dadas por el CPOWeeds se han comprobado para nueve especies de malas hierbas en diferentes estadios fenológicos y en el 84,2% de los casos las eficacias han sido iguales o superiores a las predichas. Se concluye que el uso del CPOWeeds permite optimizar la aplicación de herbicidas con una gran robustez. Las recomendaciones son satisfactorias para el NE de España y se puede disminuir la cantidad de herbicidas aplicados hasta en un 30%. Por tanto, se trata de una herramienta muy importante en el Manejo Integrado de Malas Hierbas
Emergent Gauge Fields in Holographic Superconductors
Holographic superconductors have been studied so far in the absence of
dynamical electromagnetic fields, namely in the limit in which they coincide
with holographic superfluids. It is possible, however, to introduce dynamical
gauge fields if a Neumann-type boundary condition is imposed on the
AdS-boundary. In 3+1 dimensions, the dual theory is a 2+1 dimensional CFT whose
spectrum contains a massless gauge field, signaling the emergence of a gauge
symmetry. We study the impact of a dynamical gauge field in vortex
configurations where it is known to significantly affect the energetics and
phase transitions. We calculate the critical magnetic fields H_c1 and H_c2,
obtaining that holographic superconductors are of Type II (H_c1 < H_c2). We
extend the study to 4+1 dimensions where the gauge field does not appear as an
emergent phenomena, but can be introduced, by a proper renormalization, as an
external dynamical field. We also compare our predictions with those arising
from a Ginzburg-Landau theory and identify the generic properties of Abrikosov
vortices in holographic models.Comment: 19 pages, 14 figures, few comments added, version published in JHE
Non-Equilibrium Field Dynamics of an Honest Holographic Superconductor
Most holographic models of superconducting systems neglect the effects of
dynamical boundary gauge fields during the process of spontaneous
symmetry-breaking. Usually a global symmetry gets broken. This yields a
superfluid, which then is gauged "weakly" afterwards. In this work we build
(and probe the dynamics of) a holographic model in which a local boundary
symmetry is spontaneously broken instead. We compute two-point functions of
dynamical non-Abelian gauge fields in the normal and in the broken phase, and
find non-trivial gapless modes. Our AdS3 gravity dual realizes a p-wave
superconductor in (1+1) dimensions. The ground state of this model also breaks
(1+1)-dimensional parity spontaneously, while the Hamiltonian is
parity-invariant. We discuss possible implications of our results for a wider
class of holographic liquids.Comment: 32 pages, 12 figures; v3: string theory derivation of setup added
(section 3.1), improved presentation, version accepted by JHEP; v2: paragraph
added to discussion, figure added, references added, typos correcte
Scanning the Parameter Space of Holographic Superconductors
We study various physical quantities associated with holographic s-wave
superconductors as functions of the scaling dimensions of the dual condensates.
A bulk scalar field with negative mass squared , satisfying the
Breitenlohner-Freedman stability bound and the unitarity bound, and allowed to
vary in unit intervals, were considered. We observe that all the physical
quantities investigated are sensitive to the scaling dimensions of the dual
condensates. For all the , the characteristic lengths diverge at the
critical temperature in agreement with the Ginzburg-Landau theory. The
Ginzburg-Landau parameter, obtained from these length scales indicates that the
holographic superconductors can be type I or type II depending on the charge
and the scaling dimensions of the dual condensates. For a fixed charge, there
exists a critical scaling dimension, above which a holographic superconductor
is type I, below which it becomes a type II.Comment: 24 pages 47 figure
Holographic Superfluids and Superconductors in Dilaton-Gravity
We investigate holographic models of superfluids and superconductors in which
the gravitational theory includes a dilatonic field. Dilaton extensions are
interesting as they allow us to obtain a better description of low temperature
condensed matter systems. We focus on asymptotically AdS black hole
configurations, which are dual to field theories with conformal ultraviolet
behavior. A nonvanishing value of the dilaton breaks scale invariance in the
infrared and is therefore compatible with the normal phase being insulating (or
a solid in the fluid mechanical interpretation); indeed we find that this is
the case at low temperatures and if one appropriately chooses the parameters of
the model. Not only the superfluid phase transitions, but also the response to
external gauge fields is analyzed. This allows us to study, among other things,
the vortex phase and to show that these holographic superconductors are also of
Type II. However, at low temperatures they can behave in a qualitatively
different way compared to their analogues without the dilaton: the critical
magnetic fields and the penetration depth can remain finite in the small T/T_c
limit.Comment: 20 pages, 8 figures; few comments and references added, a typo fixed
in the equation below eq. (16), article accepted for publication in JHE
Holographic superfluids as duals of rotating black strings
We study the breaking of an Abelian symmetry close to the horizon of an
uncharged rotating Anti-de Sitter black string in 3+1 dimensions. The boundary
theory living on R^2 x S^1 has no rotation, but a magnetic field that is
aligned with the axis of the black string. This boundary theory decribes
non-rotating (2+1)-dimensional holographic superfluids with non-vanishing
superfluid velocity. We study these superfluids in the grand canonical ensemble
and show that for sufficiently small angular momentum of the dual black string
and sufficiently small superfluid velocity the phase transition is 2nd order,
while it becomes 1st order for larger superfluid velocity. Moreover, we observe
that the phase transition is always 1st order above a critical value of the
angular momentum independent of the choice of the superfluid velocity.Comment: 9 pages including 5 figures: v2: 12 pages including 7 figures; 2
figures added, discussion on free energy added; accepted for publication in
JHE
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