Search

We address a long standing problem concerning the scale behaviour of parton densities in the low $x$, low $Q^2$ domain. We emphasize the important role of absorptive corrections at low $x$ and use knowledge of diffractive deep inelastic scattering to exclude the absorptive effect from conventional deep inelastic data. In this way we obtain a significantly different low $x$ behaviour of the gluon density, which is now much better described by linear DGLAP evolution. Accounting also for a second power correction, which arises from the freezing of $\alpha_s$ at low $Q^2$, leads to an essentially flat behaviour of the low $x$ gluon density., Comment: 16 pages, 7 figures, 3 tables, text and 2 figures improved

In Brazil, 87% of N2O released into the atmosphere comes from agriculture, emphasizing the importance of assessing emissions in agricultural systems. The aim of this study was to evaluate N2O fluxes and emissions in agroecosystems and to identify how physical and chemical attributes of soil may affect the emissions. The study was carried out in the northeastern savannah (Cerrado), in an area under current agricultural expansion, in the municipality of Bom Jesus, State of Piauí. The treatments were composed of grain cultivation systems under no-tillage: exclusive soybean with biological nitrogen fixation (FBN), exclusive corn and corn intercropped with brachiaria. An adjacent area under native Cerrado was evaluated as reference ecosystem. N2O fluxes were monitored using manual static chambers between February 18 and April 22, 2017, covering the period from planting until the beginning of the harvest. Corn cultivation systems presented the highest N2O fluxes and the highest total emissions. Nitrogen fertilization significantly contributed to soil N2O fluxes as opposed to FBN. The soybean system and the native Cerrado had the lowest N2O emissions. Substantial amounts of N2O may be emitted during plant residue decomposition, however, it was not evaluated in this study. The concentrations of NH4+ and NO3-available in the soil were different among the cropping systems, presenting a positive correlation with N2O fluxes.

Despite not have been yet identified by the IceCube detector, events generated from ντ deep inelastic neutrino scattering in ice with varied topologies, such as double cascades (often called double bangs), lollipops, and sugardaddies, constitute a potential laboratory for low-x parton studies. Here we investigate these events, analyzing the effect of next-to-next-to-leading order parton distribution function in the total neutrino-nucleon cross section, as compared with the color dipole formalism, where saturation effects play a major role. Energy deposit profiles in the “bangs” are also analyzed in terms of virtual W-boson and tauon energy distributions and are found to be crucial in establishing a clear signal for gluon distribution determination at very small x. By taking the average (all flavor) neutrino flux (Φν∼Eν−2.3) into differential cross sections as a function of τ and W energies, we find significant deviations from pure Dokshitzer-Gribov-Lipatov-Altarelli-Parisi parton interactions for neutrino energies already at a few PeV. With these findings one aims at providing not only possible observables to be measured in large volume neutrino detectors in the near future, but also theoretical ways of unravelling QCD dynamics using unintegrated neutrino-nucleon cross sections in the ultrahigh-energy frontier.

We compare the rapidity, $y$, and the beam energy, $\sqrt{s}$, behaviours of the cross section of the data for $D$ meson production in the forward direction that were measured by the LHCb collaboration. We describe the observed cross sections using NLO perturbative QCD, and choose the optimal factorization scale for the LO contribution which provides the resummation of the large double logarithms. We emphasize the inconsistency observed in the $y$ and $\sqrt{s}$ behaviours of the $D$ meson cross sections. The $y$ behaviour indicates a very {\it flat} $x$ dependence of the gluon PDF in the unexplored low $x$ region around $x\sim 10^{-5}$. However, to describe the $\sqrt{s}$ dependence of the data we need a steeper gluon PDF with decreasing $x$. Moreover, an even steeper behaviour is needed to provide an extrapolation which matches on to the well known gluons found in the global PDF analyses for $x\sim 10^{-3}$. The possible role of non-perturbative effects is briefly discussed., 12 pages, 4 figures, this article supersedes arXiv:1705.08845, version to be published in PRD

Doubled haploid technology has been used by various private companies. However, information regarding chromosome duplication methodologies, particularly those concerning techniques used to identify duplication in cells, is limited. Thus, we analyzed and characterized artificially doubled haploids using microsatellites molecular markers, pollen viability, and flow cytometry techniques. Evaluated material was obtained using two different chromosome duplication protocols in maize seeds considered haploids, resulting from the cross between the haploid inducer line KEMS and 4 hybrids (GNS 3225, GNS 3032, GNS 3264, and DKB 393). Fourteen days after duplication, plant samples were collected and assessed by flow cytometry. Further, the plants were transplanted to a field, and samples were collected for DNA analyses using microsatellite markers. The tassels were collected during anthesis for pollen viability analyses. Haploid, diploid, and mixoploid individuals were detected using flow cytometry, demonstrating that this technique was efficient for identifying doubled haploids. The microsatellites markers were also efficient for confirming the ploidies preselected by flow cytometry and for identifying homozygous individuals. Pollen viability showed a significant difference between the evaluated ploidies when the Alexander and propionic-carmin stains were used. The viability rates between the plodies analyzed show potential for fertilization.

We show how it is possible to rewrite the BFKL equation for the unintegrated gluon distribution, in terms of integrated gluons, similar to that used in DGLAP. We add to our equation the next-to-leading log terms which provide exact energy-momentum conservation and account for the kinematic constraint in real gluon emission. In this way the equation includes the major part of the higher-order corrections to BFKL evolution. We discuss the possibility to obtain a unified BFKL-DGLAP evolution equation relevant to processes at the LHC where both log(1/x) and logQ^2 are large simultaneously., Comment: 11 pages, text clarified, version to be published in EPJC

We present an evolution equation which simultaneously sums the leading BFKL and DGLAP logarithms for the integrated gluon distribution in terms of a single variable, namely the emission angle of the gluon. This form of evolution is appropriate for Monte Carlo simulations of events of high energy pp (and p\bar{p}) interactions, particularly where small x events are sampled., 12 pages, 1 figure, version to be published in EPJC

We discuss the effects of a strong magnetic field on B and D mesons, focusing on the changes of the energy levels and the masses of the bound states. Using the Color Evaporation Model we discuss the possible changes in the production of J/ψ and Υ. We briefly comment the recent experimental data.

A oxcarbazepina é uma droga antiepiléptica de alta eficácia e poucos efeitos colaterais, mas pouco estudada quanto a seus efeitos durante a gestação humana e animal. OBJETIVO: Verificar se a administração de oxcarbazepine em ratas, nos quatro primeiros dias após a inseminação, altera a viabilidade ou o desenvolvimento do pré-embrião. MÉTODOS: Ratas Wistar foram tratadas com 20 ou 200 mg de oxcarbazepina/ Kg de peso corporal, via gástrica, nos dias 1, 2, 3, ou 4 a partir da inseminação ou, consecutivamente, do 1º ao 4º. Os pré-embriões foram coletados no quinto dia, visando verificar a quantidade e o desenvolvimento até a fase de blastocisto expandido. O peso corporal materno e sinais como pelos eriçados e alteração de atividade locomotora foram anotados para verificar indícios de toxicidade materna. Número de corpos lúteos e peso de ovários foram anotados com vistas à capacidade reprodutiva do animal. RESULTADOS: Não ocorreram perdas de pesos corporais maternos e nenhuma alteração física indicativa de desconforto para as ratas. Peso de ovários e número de corpos lúteos não diferiram entre tratados e controles. O número médio de pré-embriões por mães, o índice de perdas embrionárias, a proporção de blastocistos expandidos com relação ao total de pré-embriões e a média de blastocistos expandidos/mãe, não diferiram entre tratados e controles. CONCLUSÃO: A oxcarbazepina administrada em ratas, seguindo o esquema terapêutico mencionado, não apresentou efeito tóxico sobre a mãe e não alterou o desenvolvimento do pré-embrião.Oxcarbazepine is a highly efficcacious antiepileptic drug which has very few side effects and has been poorly investigated as to its effects during human and animal gestation. PURPOSE: To verify if the administration of oxcapazepine to female rats in the first four days ofter fertilization alters the viability or development of the pre-embryo. METHODS: Wistar rats were treated with 20 or 200mg oxcarbazepine/Kg body weight by oral gavage, 1,2,3,or 4 days after insemination or, consecutively, from the first to de fourth day aiming at veryfing the amount and the development up to the expanded blastocyst stage. Maternal body weight and signs such as hair bristling and alteration of the locomotion activity were observed in order to verify any signs of maternal toxicity. A number of corpora lutea and ovaries weight were noted for the analysis of the animal reproductive capacity. RESULTS: Neither maternal body weight losses nor any physical alteration indicative of discomfort to the rats was observed. Ovaries weight and number of corpora lutea did not differ between treated and control animals. The average of pre-embryos per mother, the index of embryonic losses, the proportion of expanded blastocysts in relation to the total number of pre-embryos and the average of expanded blastocyst/mother did not differ between treated and control animals. CONCLUSIONS: The data indicate that oxcarbazepine administered to female rats following the therapeutic procedure mentioned above, did not show any toxic effect on the mother and did not alter the pre-embryo development.

We introduce the physical factorisation scheme, which is necessary to describe observables which are `not completely inclusive'. We derive the formulae for NLO DGLAP evolution in this scheme, and also for the `rotation' of the conventional MSbar PDFs into the physical representation. Unlike, the MSbar prescription, where, for example, the gluon PDF at NLO obtains an admixture of the quark-singlet PDF, and vice-versa, the physical approach does not mix parton PDFs of different types. That is, the physical approach retains the precise quantum numbers of each PDF. The NLO corrections to DGLAP evolution in the physical scheme are less than those in the MSbar case, indicating a better convergence of the perturbative series.

We show that the conventional prescription used for DGLAP parton evolution at NLO has an inconsistent treatment of the contribution from the infrared (IR) region. We illustrate the problem by studying the simple example of QED evolution, treating the electron and photon as partons. The deficiency is not present in a physical approach which removes the IR divergency and allows calculation in the normal 4-dimensional space., 15 pages, 2 figures, erratum at the end of the article

We study how unintegrated parton distributions in nuclei can be calculated from the corresponding integrated partons using the EPS09 parametrization. The role of nuclear effects is presented in terms of the ratio $R^A=\text{uPDF}^A/A\cdot \text{PDF}^N$ for both large and small $x$ domains., 9 pages, 4 figures

The measurement of the nuclear structure function $F_2^A (x,Q^2)$ at the future electron-ion collider (EIC) will be of great relevance to understand the origin of the nuclear shadowing and to probe gluon saturation effects. Currently there are several phenomenological models, based on very distinct approaches, which describe the scarce experimental data quite successfully. One of main uncertainties comes from the schemes used to include the effects associated to the multiple scatterings and to unitarize the cross section. In this paper we compare the predictions of three different unitarization schemes of the nuclear structure function which use the same theoretical input to describe the projectile-nucleon interaction. In particular, we consider as input the predictions of the Color Glass Condensate formalism, which reproduce the inclusive and diffractive $ep$ HERA data. Our results suggest that the experimental analysis of $F_2^A$ will be able to discriminate between the unitarization schemes.

It is well known that in noncentral heavy-ion collisions a transient strong magnetic field is generated in the direction perpendicular to the reaction plane. The maximal strength of this field is estimated to be $eB \sim m^2_{\pi} \sim 0.02 \text{GeV}^2$ at the RHIC and $eB \sim 15 m^2_{\pi} \sim 0.3 \text{GeV}^2$ at the LHC. We investigate the effects of a strong magnetic field on $B$ and $D$ mesons, focusing on the changes of the energy levels and the masses of the bound states. Using the Color Evaporation Model we discuss the possible changes in the production of $J/\psi$ and $\Upsilon$., Comment: 18 pages, 7 figures

We show how the AGBS model, originally developed for deep inelastic scattering applied to HERA data on the proton structure function, can also describe the RHIC data on single inclusive hadron yield for d + Au and p + p collisions through a new simultaneous fit. The single inclusive hadron production is modeled through the color glass condensate, which uses the quark(and gluon) condensate amplitudes in momentum space. The AGBS model is also a momentum space model based on the asymptotic solutions of the BK equation, although a different definition of the Fourier transform is used. This description entirely in transverse momentum of both processes arises for the first time. The small difference between the simultaneous fit and the one for HERA data alone suggests that the AGBS model describes very well both kind of processes and thus emerges as a good tool to investigate the inclusive hadron production data. We use this model for predictions at LHC energies, which agree quite well with available experiment...

We show that to correctly describe the effects of the heavy-quark mass, m_h, in DGLAP evolution, it is necessary to work in the so-called `physical' scheme. In this way, we automatically obtain a smooth transition through the heavy-quark thresholds. Moreover, we show that to obtain NLO accuracy, it is sufficient to account for the heavy-quark mass, m_h, just in the LO (one-loop) splitting function. The use of the MS-bar factorisation scheme is not appropriate, since at NLO we deal with a mixture of quarks and gluon (that is, the mass of the heavy parton is not well-defined). The formulae for the explicit m_h dependence of the splitting functions, and for alpha_s, are presented., Comment: 14 pages, 3 figures, references updated, version to be published in EPJC

The dipole color approach is the framework that considers the quark-antiquark pair scattering off the target. The rapidity evolution of color dipoles is given by the nonlinear Balitsky-Kovchegov (BK) equation, for which analytical solutions are not yet known. A good way to explore the asymptotic BK solutions is through the traveling wave method of QCD, that uses a correspondence between the BK evolution equation in momentum space and reaction-diffusion physics. Using the traveling wave based AGBS model for the dipole amplitude in momentum space, and within the k{sub t}-factorization formalism, we describe the LHC data on single inclusive hadron yield for p-p collisions.

We show that the observation of the Drell-Yan production of low-mass lepton-pairs (M < 20 GeV) at high rapidities (Y > 3) at the LHC can make a direct measurement of parton distribution functions (PDFs) in the low x region, x < 10^{-4}. We describe a procedure that greatly reduces the sensitivity of the predictions to the choice of the factorization scale and, in particular, show how, by imposing a cutoff on the transverse momentum of the lepton-pair, the data are able to probe PDFs in the important low scale, low x domain. We include the effects of the Sudakov suppression factor., 14 pages, 5 figures, version to be published in EPJC, with expanded explanation

First, we show how to reduce the sensitivity of the NLO predictions of the Drell-Yan production of low-mass, lepton-pairs, at high rapidity, to the choice of factorization scale. In this way, observations of this process at the LHC can make direct measurements of parton distribution functions in the low x domain; x < 10^{-4}. Second, we find an inconsistency in the conventional NLO treatment of the infrared region. We illustrate the problem using the NLO coefficient function of Drell-Yan production., 5 pages, 1 figure, contribution to the Proceedings of "Diffraction2012", Puerto del Carmen, Lanzarote, Spain, Sept. 10-15th, 2012

Within the framework of a (1+1)--dimensional model which mimics high energy QCD, we study the behavior of the cross sections for inclusive and diffractive deep inelastic $\gamma^*h$ scattering cross sections. We analyze the cases of both fixed and running coupling within the mean field approximation, in which the evolution of the scattering amplitude is described by the Balitsky-Kovchegov equation, and also through the pomeron loop equations, which include in the evolution the gluon number fluctuations. In the diffractive case, similarly to the inclusive one, the suppression of the diffusive scaling, as a consequence of the inclusion of the running of the coupling, is observed., Comment: 10 pages, 8 figures, submitted to Eur. Phy. J. C

Within the framework of a (1+1)--dimensional model which mimics high energy QCD, we study the behavior of the cross sections for inclusive and diffractive deep inelastic $\gamma^*h$ scattering cross sections. We analyze the cases of both fixed and running coupling within the mean field approximation, in which the evolution of the scattering amplitude is described by the Balitsky-Kovchegov equation, and also through the pomeron loop equations, which include in the evolution the gluon number fluctuations. In the diffractive case, similarly to the inclusive one, the suppression of the diffusive scaling, as a consequence of the inclusion of the running of the coupling, is observed.

Using a momentum space model for the dipole scattering amplitude we present an analysis of the saturation effects at LHC energies, describing the data on proton-proton and proton-lead collisions. The model is based on the asymptotic solutions of the Balitsky-Kovchegov equation, being ideal in the saturation domain where the target wave function has a high occupation number. We also make predictions for the nuclear modification ratios on charged hadron and prompt photon production in the forward region, where the high parton density effects are important., Comment: New section added and typos corrected. To be published in PRD

The predictions of Drell-Yan production of low-mass, lepton-pairs, at high rapidity at the LHC, are known to depend sensitively on the choice of factorization and renormalization scales. We show how this sensitivity can be greatly reduced by fixing the factorization scale of the LO contribution based on the known NLO matrix element, so that observations of this process at the LHC can make direct measurements of parton distribution functions in the low x domain; x less than about 10^{-4}., Comment: 11 pages, 5 figures

We show how the AGBS model, originally developed for deep inelastic scattering applied to HERA data on the proton structure function, can also describe the RHIC data on single inclusive hadron yield for $d+Au$ and $p+p$ collisions through a new simultaneous fit. The single inclusive hadron production is modeled through the color glass condensate, which uses the quark(and gluon)--condensate amplitudes in momentum space. The AGBS model is also a momentum space model based on the asymptotic solutions of the BK equation, although a different definition of the Fourier transform is used. This aspect is overcome and a description entirely in transverse momentum of both processes arises for the first time. The small difference between the simultaneous fit and the one for HERA data alone suggests that the AGBS model describes very well both kind of processes and thus emerges as a good tool to investigate the inclusive hadron production data. We use this model for predictions at LHC energies, which agree very well with available experimental data., 10 pages, 7 figures

Departamento de Petrologia e Metalogenia Instituto de Geociencias e Ciencias Exatas-UNESP, Rio Claro

We study open b\bar{b} production at large rapidity at the LHC in an attempt to pin down the gluon distribution at very low x. For the LHC energy of 7 TeV, at next-to-leading order (NLO), there is a large factorization scale uncertainty. We show that the uncertainty can be greatly reduced if events are selected in which the transverse momenta of the two B-mesons balance each other to some accuracy, that is |\vec p_{1T}+\vec p_{2T}| < k_0. This will fix the scale ��_F \simeq k_0, and will allow the LHCb experiment, in particular, to study the x-behaviour of gluon distribution down to x ~ 10^{-5}, at rather low scales, ��~ 2 GeV. We evaluate the expected cross sections using, for illustrative purposes, various recent sets of Parton Distribution Functions., 13 pages, 5 figures

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 figures

Among the dipole models of deep inelastic scattering at small values of the Bjorken variable $x$, one has been recently proposed which relates the virtual photon-proton cross section to the dipole-proton forward scattering amplitude in momentum space. The latter is parametrized by an expression which interpolates between its behavior at saturation and the travelling wave, ultraviolet, amplitudes predicted by perturbative QCD from the Balitsky-Kovchegov equation. Inspired by recent developments in coordinate space, we use this model to parametrize the proton structure function and confront it to HERA data on $ep$ deep inelastic scattering. Both event-by-event and the physical amplitudes are considered, the latter used to investigate the effect of gluon number fluctuations, beyond the mean-field approximation. We conclude that fluctuations are not present in DIS at HERA energies., 9 pages, 2 figures

We show that ${\ensuremath{\Sigma}}^{+}$ hyperons produced by 800 GeV/c protons on targets of Be and Cu have significant polarizations (15--20%). These polarizations persist at values of ${p}_{t}\ensuremath{\approx}2\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}/\mathrm{c}$ and a wide range of ${x}_{F}$. The polarizations from the Cu target are consistently less than from Be. The average ratio of the ${\ensuremath{\Sigma}}^{+}$ polarization from Cu to that from Be is $0.68\ifmmode\pm\else\textpm\fi{}0.08$.

We intend to use experimental data to apply the helicity formalism to calculate the spin dependent amplitudes for the following Λc+ three body decays: Λc+ → Σ+π−π+ and Λc+ → Σ+π−π+. Because these decays involve baryons with non‐zero spin, the Dalitz study of these decays no longer deals with a simple two dimensional problem, but it is a five dimensional problem.

RESUMO ¾ A oxcarbazepina é uma droga antiepiléptica de alta eficácia e poucos efeitos colaterais, mas pouco estudada quanto a seus efeitos durante a gestação humana e animal. OBJETIVO: Verificar se a administração de oxcarbazepine em ratas, nos quatro primeiros dias após a inseminação, altera a viabilidade ou o desenvolvimento do pré-embrião. MÉTODOS: Ratas Wistar foram tratadas com 20 ou 200 mg de oxcarbazepina/ Kg de peso corporal, via gástrica, nos dias 1, 2, 3, ou 4 a partir da inseminação ou, consecutivamente, do 1º ao 4º. Os pré-embriões foram coletados no quinto dia, visando verificar a quantidade e o desenvolvimento até a fase de blastocisto expandido. O peso corporal materno e sinais como pelos eriçados e alteração de atividade locomotora foram anotados para verificar indícios de toxicidade materna. Número de corpos lúteos e peso de ovários foram anotados com vistas à capacidade reprodutiva do animal. RESULTADOS: Não ocorreram perdas de pesos corporais maternos e nenhuma alteração física indicativa de desconforto para as ratas. Peso de ovários e número de corpos lúteos não diferiram entre tratados e controles. O número médio de pré-embriões por mães, o índice de perdas embrionárias, a proporção de blastocistos expandidos com relação ao total de pré-embriões e a média de blastocistos expandidos/mãe, não diferiram entre tratados e controles. CONCLUSÃO: A oxcarbazepina administrada em ratas, seguindo o esquema terapêutico mencionado, não apresentou efeito tóxico sobre a mãe e não alterou o desenvolvimento do pré-embrião.

With previously defined criteria of inclusion and previous consent, twenty six consecutive patients (19 to 64 years old), with upper digestive symptoms, were submitted to endoscopy, with biopsy, constant of eight samples of the antropyloric region (four of the anterior aspect and four of the posterior aspect). Two samples were been for culture; two for free urease test, two for smears; all gathered in adequate transport medium over refrigeration. Two samples immersed in formaline to 10% for histopathologic exam. 25/26 (96%) of the patients showed infection by H. pylori by means of one or more methods utilized. In 16/26 (61%), alterations were observed in endoscopy (gastric inflammation in eleven, peptic ulcer in two and ulcer scars in three cases). Of the patients with endoscopic gastric inflammation, presented positive as well as all (100%) bearers of scar or peptic ulcer. A close relationship was observed between the presence of H. pylori and chronic gastric inflammation 24/25 (96%). Histopathologic slices stained by hematoxilin-eosin was the test of highest diagnostic sensitivity 24/25 (96%), followed by urease test 23%25 (92%), stained smears 19/25 (76%) and culture 18/25 (72%). Our conclusion is that the prevalence of gastric infection for H. pylori in symptomatic patients is high, correlated with chronic gastric inflammation and ulcers. Histopathologic slices stained by hematoxilin-eosin and free urease test are the most sensitive indicators of the presence of H. pylori. This study should proceed for further elucidation of questions realised and include a control group of symptomatics individuals paired for sex and age.

The ‘optimal’ factorization scale $$\mu _0$$ is calculated for open heavy quark production. We find that the optimal value is $$\mu _F=\mu _0\simeq 0.85\sqrt{p^2_T+m_Q^2} $$ ; a choice which allows us to resum the double-logarithmic, $$(\alpha _s\ln \mu ^2_F\ln (1/x))^n$$ corrections (enhanced at LHC energies by large values of $$\ln (1/x)$$ ) and to move them into the incoming parton distributions, PDF $$(x,\mu _0^2)$$ . Besides this result for the single inclusive cross section (corresponding to an observed heavy quark of transverse momentum $$p_T$$ ), we also determined the scale for processes where the acoplanarity can be measured; that is, events where the azimuthal angle between the quark and the antiquark may be determined experimentally. Moreover, we discuss the important role played by the $$2\rightarrow 2$$ subprocesses, $$gg\rightarrow Q\bar{Q}$$ at NLO and higher orders. In summary, we achieve a better stability of the QCD calculations, so that the data on $$c{\bar{c}}$$ and $$b{\bar{b}}$$ production can be used to further constrain the gluons in the small x, relatively low scale, domain, where the uncertainties of the global analyses are large at present.