606 research outputs found
Study of Meson Production in Diffractive Scattering at HERA
production in the diffractive interactions was measured with the
ZEUS detector at HERA using integrated luminosities of 44 pb in deep
inelastic scattering and 38 pb in photoproduction processes.
Diffractive interactions were identified by a large gap in the rapidity
distribution of final states. mesons were reconstructed from the
decay with {} (+c.c.). Integrated and
differential cross sections were compared to theoretical expectations.Comment: LaTeX2e, 2 pages, 8 Postscript figures. Talk given at the 9th
International Workshop on Deep-Inelastic Scattering DIS2001, Bologna, Italy,
April 27-May 1, 2001. To be published in Proceedings of the 9th International
Workshop on Deep-Inelastic Scattering DIS2001, Bologna, Italy, 200
THE NEED TO PREPARE INDUSTRY PROFESSIONALS WITH THE COMPETENCIES OF THE DIGITAL ECONOMY IN THE FIELD OF AGRICULTURE
В статье рассматривается о необходимости за короткий период перестроить систему подготовки специалистов для АПК с учетом требований внедрения цифровых технологийThe article discusses the need for a short period to rebuild the system of training for agriculture, taking into account the requirements of the introduction of digital technologie
An independent estimate of the triple-Pomeron coupling
The value of the important triple-Pomeron coupling is estimated by an
unorthodox procedure using the known diffractive parton distribution functions.
The result is g_{3P}\simeq 0.2g_N, where g_N is the Pomeron-nucleon coupling.
This is in excellent agreement with an independent determination, g_{3P}\simeq
0.2g_N, previously obtained by analysing the available data in the triple-Regge
region with absorptive effects taken into account.Comment: 7 pages, 5 figure
Diffractive charm photoproduction at HERA ep-collider
The cross section of the -meson diffractive photoproduction at the HERA
collider has been calculated in the framework of perturbatively motivated model
for the different kinematic regions. The camparison between the different
Pomeron models has been performed.Comment: 9 pages, 3 figure
A review of Caribbean Copepoda associated with reef-dwelling cnidarians, echinoderms and sponges
This review of copepod crustaceans associated with reef-dwelling cnidarians, sponges and echinoderms of the Greater Caribbean is based on published records, systematically arranged by the classification of symbiotic copepods and their hosts, sampling sites, coordinates, depth and date of sampling, literature sources, and three recent surveys (Cuba, St. Eustatius in the Eastern Caribbean and Curacao in the Southern Caribbean). This resulted in totals of 532 records of 115 species of symbiotic copepods (47 genera, 17 families, three orders) hosted by 80 species of invertebrates, representing scleractinians (47%), octocorals (9%), echinoderms (3%), and sponges (1%). Among ten Caribbean ecoregions, the Greater Antilles (with 64 species of symbiotic copepods) as well as the Southern and Eastern Caribbean (with 46 and 17 species of copepods, respectively) are the most studied and best represented, whereas only six species of copepods are known from Bermuda, one from Southwestern Caribbean and none from the Gulf of Mexico. The absence of poecilostomatoid copepods (Anchimolgidae, Rhynchomolgidae and Xarifidae) on Caribbean stony corals as noted by Stock (1988) is confirmed. The results indicate that the diversity and ecology of Caribbean symbiotic copepods are still poorly investigated
Measurement of D*+/- diffractive cross sections in photoproduction at HERA
The first measurement of D*+/- meson diffractive photoproduction cross
sections has been performed with the ZEUS detector at the HERA collider,
using an integrated luminosity of 38 pb^-1. The measurement has been performed
for photon--proton center-of-mass energies in the range 130 < W < 280 GeV and
photon virtualities Q^2 < 1 GeV^2. D*+/- mesons have been reconstructed with
p_T(D*)>2 GeV and -1.5 D^0 \pi^+_s
with D^0 --> K-\pi^+ (+c.c.). The diffractive component has been selected with
0.001<x_Pom<0.018. The measured diffractive cross section in this kinematic
range is: \sigma_(ep --> e'D*Xp') =
0.74 +/- 0.21 (stat.)^{+0.27}_{-0.18} (syst.) +/-0.16 (p. diss.) ~nb (ZEUS
preliminary). Measured integrated and differential cross sections have been
compared to theoretical expectations.Comment: LaTeX2e, 10 pages, 6 Postscript figures. Talk given at the Russian
Academy of Science (RAS) Nuclear Physics 2000 Conference, Moscow, Russia,
November 27-December 2, 2000. To be published in Rus. Nucl. Phys. (Ya.F.),
Proceedings of RAS Nucl. Phys. 2000 Con
Combined QCD and electroweak analysis of HERA data
A simultaneous fit of parton distribution functions (PDFs) and electroweak
parameters to HERA data on deep inelastic scattering is presented. The input
data are the neutral current and charged current inclusive cross sections which
were previously used in the QCD analysis leading to the HERAPDF2.0 PDFs. In
addition, the polarisation of the electron beam was taken into account for the
ZEUS data recorded between 2004 and 2007. Results on the vector and
axial-vector couplings of the Z boson to u- and d-type quarks, on the value of
the electroweak mixing angle and the mass of the W boson are presented. The
values obtained for the electroweak parameters are in agreement with Standard
Model predictions.Comment: 32 pages, 10 figures, accepted by Phys. Rev. D. Small corrections
from proofing process and small change to Fig. 12 and Table
Search for a narrow baryonic state decaying to and in deep inelastic scattering at HERA
A search for a narrow baryonic state in the and
system has been performed in collisions at HERA with the ZEUS detector
using an integrated luminosity of 358 pb taken in 2003-2007. The search
was performed with deep inelastic scattering events at an centre-of-mass
energy of 318 GeV for exchanged photon virtuality, , between 20 and 100
. Contrary to evidence presented for such a state around 1.52
GeV in a previous ZEUS analysis using a sample of 121 pb taken in
1996-2000, no resonance peak was found in the invariant-mass
distribution in the range 1.45-1.7 GeV. Upper limits on the production cross
section are set.Comment: 16 pages, 4 figures, accepted by Phys. Lett. B. Minor changes from
journal reviewing process, including a small correction to figure
Limits on the effective quark radius from inclusive scattering at HERA
The high-precision HERA data allows searches up to TeV scales for Beyond the
Standard Model contributions to electron-quark scattering. Combined
measurements of the inclusive deep inelastic cross sections in neutral and
charged current scattering corresponding to a luminosity of around 1
fb have been used in this analysis. A new approach to the beyond the
Standard Model analysis of the inclusive data is presented; simultaneous
fits of parton distribution functions together with contributions of "new
physics" processes were performed. Results are presented considering a finite
radius of quarks within the quark form-factor model. The resulting 95% C.L.
upper limit on the effective quark radius is cm.Comment: 10 pages, 4 figures, accepted by Phys. Lett.
Measurement of the cross-section ratio sigma_{psi(2S)}/sigma_{J/psi(1S)} in deep inelastic exclusive ep scattering at HERA
The exclusive deep inelastic electroproduction of and
at an centre-of-mass energy of 317 GeV has been studied with the ZEUS
detector at HERA in the kinematic range GeV,
GeV and GeV, where is the photon virtuality, is the
photon-proton centre-of-mass energy and is the squared four-momentum
transfer at the proton vertex. The data for GeV were taken in
the HERA I running period and correspond to an integrated luminosity of 114
pb. The data for GeV are from both HERA I and HERA II
periods and correspond to an integrated luminosity of 468 pb. The decay
modes analysed were and for the
and for the . The cross-section ratio
has been measured as a function of
and . The results are compared to predictions of QCD-inspired
models of exclusive vector-meson production.Comment: 24 pages, 8 figure
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