1,200 research outputs found
The intercept of the BFKL pomeron from Forward Jets at HERA
Recently the H1 and ZEUS collaborations have presented cross sections for DIS
events with a forward jet. The BFKL formalism is able to produce an excellent
fit to these data. The extracted intercept of the hard pomeron suggests that
when all higher order corrections are taken into account the cross section will
still rise very rapidly as expected for low dynamics.Comment: 10 pages, one figure, accepted for publication in PL
Influencia de la fertirrigación con agua regenerada y las labores de mantenimiento en la uniformidad de riego
El objetivo del trabajo ha sido estudiar el efecto de la fertirrigación y las labores de
mantenimiento en la uniformidad de distribución de caudal utilizando agua urbana
regenerada. El ensayo se desarrolló en un invernadero experimental en el Centro IFAPA La
Mojonera en La Cañada (Almería). Se estableció un diseño experimental factorial con dos
factores, manejo del riego y tipo de emisor. En lo que respecta al factor manejo de riego se
dispusieron tres tratamientos, AR-Riego con agua residual urbana regenerada; ARFRFertirriego
con agua residual urbana regenerada+equilibrio fertilizante estándar y ARFRMFertirriego
con agua residual urbana regenerada+equilibrio fertilizante estándar
+mantenimiento. En el factor tipo de emisor, se evaluaron 20 modelos comerciales de
goteros seleccionados en estudios previos de diferentes tipologías. Se determinó el
coeficiente de uniformidad de caudal y el porcentaje de obturación a las 0, 40, 60, 80 y 100 h
de funcionamiento. De los resultados obtenidos se puede concluir que el tratamiento de
riego afectó al porcentaje de obturación, siendo mayor en los tratamientos fertirrigados. Las
labores de mantenimiento predefinidas mejoraron la uniformidad pero no resultaron eficaces
para evitar la obturación, por lo que sería necesario redefinir las labores de mantenimiento
más adecuadas a este tipo de agua
Comparación de las medidas de humedad en suelo enarenado con diferentes sensores
Poster[ES] Una opción ambiciosa para gestionar el riego es emplear sensores como activadores del riego. El éxito de la
automatización del riego empleando sensores de humedad de suelo depende, entre otros factores, de la
adaptación del sensor a las características del suelo.
El objetivo de este trabajo es evaluar el comportamiento de tres equipos de medida de humedad en un
suelo enarenado característico de los cultivos hortícolas bajo abrigo desarrollados en el Sureste de España.El trabajo ha sido cofinanciado por Fondos Europeos (FSE y FEDER) y la Consejería de Agricultura y Pesca (IFAPA Junta de Andalucía) mediante el Proyecto Transforma Conecta SAR (PP.TRA.TRA201300.10).Baeza Cano, R.; Contreras París, J.; Alonso López, F.; Cánovas Fernández, G.; López Segura, J. (2014). Comparación de las medidas de humedad en suelo enarenado con diferentes sensores. En CONFERENCIA INTERNACIONAL INFOACES. UN SISTEMA DE INFORMACIÓN PARA LAS UNIVERSIDADES LATINOAMERICANAS. LIBRO DE ACTAS. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/94683OC
Ultra Long Period Cepheids: a primary standard candle out to the Hubble flow
The cosmological distance ladder crucially depends on classical Cepheids
(with P=3-80 days), which are primary distance indicators up to 33 Mpc. Within
this volume, very few SNe Ia have been calibrated through classical Cepheids,
with uncertainty related to the non-linearity and the metallicity dependence of
their period-luminosity (PL) relation. Although a general consensus on these
effects is still not achieved, classical Cepheids remain the most used primary
distance indicators. A possible extension of these standard candles to further
distances would be important. In this context, a very promising new tool is
represented by the ultra-long period (ULP) Cepheids (P \geq 80 days), recently
identified in star-forming galaxies. Only a small number of ULP Cepheids have
been discovered so far. Here we present and analyse the properties of an
updated sample of 37 ULP Cepheids observed in galaxies within a very large
metallicity range of 12+log(O/H) from ~7.2 to 9.2 dex. We find that their
location in the colour(V-I)-magnitude diagram as well as their Wesenheit (V-I)
index-period (WP) relation suggests that they are the counterparts at high
luminosity of the shorter-period (P \leq 80 days) classical Cepheids. However,
a complete pulsation and evolutionary theoretical scenario is needed to
properly interpret the true nature of these objects. We do not confirm the
flattening in the studied WP relation suggested by Bird et al. (2009). Using
the whole sample, we find that ULP Cepheids lie around a relation similar to
that of the LMC, although with a large spread (~0.4 mag).Comment: 8 pages, 4 figures, accepted for publication in Astrophysics & Space
Scienc
Next-to-leading BFKL phenomenology of forward-jet cross sections at HERA
We show that the forward-jet measurements performed at HERA allow for a
detailed study of corrections due to next-to-leading logarithms (NLL) in the
Balitsky-Fadin-Kuraev-Lipatov (BFKL) approach. While the description of the
d\sigma/dx data shows small sensitivity to NLL-BFKL corrections, these can be
tested by the triple differential cross section d\sigma/dxdk_T^2dQ^2 recently
measured. These data can be successfully described using a
renormalization-group improved NLL kernel while the standard
next-to-leading-order QCD or leading-logarithm BFKL approaches fail to describe
the same data in the whole kinematic range. We present a detailed analysis of
the NLL scheme and renormalization-scale dependences and also discuss the
photon impact factors.Comment: 15 pages, 9 figures, new title, NLL-BFKL saddle-point approximation
replaced by exact integratio
Light-cone QCD Sum Rules for the Baryon Electromagnetic Form Factors and its magnetic moment
We present the light-cone QCD sum rules up to twist 6 for the electromagnetic
form factors of the baryon. To estimate the magnetic moment of the
baryon, the magnetic form factor is fitted by the dipole formula. The numerical
value of our estimation is , which is in
accordance with the experimental data and the existing theoretical results. We
find that it is twist 4 but not the leading twist distribution amplitudes that
dominate the results.Comment: 13 page, 7 figures, accepted for publication in Euro. Phys. J.
Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy
We review HB stars in a broad astrophysical context, including both variable
and non-variable stars. A reassessment of the Oosterhoff dichotomy is
presented, which provides unprecedented detail regarding its origin and
systematics. We show that the Oosterhoff dichotomy and the distribution of
globular clusters (GCs) in the HB morphology-metallicity plane both exclude,
with high statistical significance, the possibility that the Galactic halo may
have formed from the accretion of dwarf galaxies resembling present-day Milky
Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the
second-parameter problem is presented. A technique is proposed to estimate the
HB types of extragalactic GCs on the basis of integrated far-UV photometry. The
relationship between the absolute V magnitude of the HB at the RR Lyrae level
and metallicity, as obtained on the basis of trigonometric parallax
measurements for the star RR Lyrae, is also revisited, giving a distance
modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are
studied. Finally, the conductive opacities used in evolutionary calculations of
low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and
Space Scienc
Forward pi^0 Production and Associated Transverse Energy Flow in Deep-Inelastic Scattering at HERA
Deep-inelastic positron-proton interactions at low values of Bjorken-x down
to x \approx 4.10^-5 which give rise to high transverse momentum pi^0 mesons
are studied with the H1 experiment at HERA. The inclusive cross section for
pi^0 mesons produced at small angles with respect to the proton remnant (the
forward region) is presented as a function of the transverse momentum and
energy of the pi^0 and of the four-momentum transfer Q^2 and Bjorken-x.
Measurements are also presented of the transverse energy flow in events
containing a forward pi^0 meson. Hadronic final state calculations based on QCD
models implementing different parton evolution schemes are confronted with the
data.Comment: 27 pages, 8 figures and 3 table
Search for Doubly-Charged Higgs Boson Production at HERA
A search for the single production of doubly-charged Higgs bosons H^{\pm \pm}
in ep collisions is presented. The signal is searched for via the Higgs decays
into a high mass pair of same charge leptons, one of them being an electron.
The analysis uses up to 118 pb^{-1} of ep data collected by the H1 experiment
at HERA. No evidence for doubly-charged Higgs production is observed and mass
dependent upper limits are derived on the Yukawa couplings h_{el} of the Higgs
boson to an electron-lepton pair. Assuming that the doubly-charged Higgs only
decays into an electron and a muon via a coupling of electromagnetic strength
h_{e \mu} = \sqrt{4 \pi \alpha_{em}} = 0.3, a lower limit of 141 GeV on the
H^{\pm\pm} mass is obtained at the 95% confidence level. For a doubly-charged
Higgs decaying only into an electron and a tau and a coupling h_{e\tau} = 0.3,
masses below 112 GeV are ruled out.Comment: 15 pages, 3 figures, 1 tabl
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