Timelike Compton scattering: exclusive photoproduction of lepton pairs

We investigate the exclusive photoproduction of a heavy timelike photon which decays into a lepton pair, gamma p -> l+ l- p. This can be seen as the analog of deeply virtual Compton scattering, and we argue that the two processes are complementary for studying generalized parton distributions in the nucleon. In an unpolarized experiment the angular distribution of the leptons readily provides access to the real part of the Compton amplitude. We estimate the possible size of this effect in kinematics where the Compton process should be dominated by quark exchange.Comment: 31 pages, 17 figure

STUPANJ OBRAZOVANJA MLIJEČNIH FARMERA NA KOSOVU

A study was conducted to assess the impact of farmers’ education on dairy farming knowledge, national food safety standards, animal diseases, and farm production practices. Farmers’ lack of awareness is likely a contributing factor to food standards not being met in most cases. The data are collected from 150 respondents randomly selected from farmers’ municipality database, in two regions of Kosovo (Gjilan and Ferizaj). The data were collected through face to face interviews and personal visits based on a structured questionnaire. Significant differences were found among farmers (higher level of education compare with primary education) in regard with food safety standards, animal diseases, milk yield, use of milking machine, milk cooling tanks, animal identification, farm register, feeding the animals according to the production level, etc. Awareness, teaching and training programs for dairy farmers can improve: animals feeding, cows’ milk yield, diseases control in animals and reduce the public health risk of milk-borne zoonosis. Also public and donor support schemes for farmers should be strongly linked to food safety standard implementation.Provedeno je istraživanje radi procjene utjecaja obrazovanja farmera na poznavanje rada mliječne farme, nacionalnih standarda sigurnosti hrane, bolesti životinja i postupaka u proizvodnji farme. Pomanjkanje znanja farmera u većini slučajeva vjerojatno doprinosi nepoštivanju standarda hrane. Podaci su prikupljeni od 150 ispitanika nasumce izabranih iz općinskih podataka o farmerima u dva područja na Kosovu (Gjilan i Ferizaj). Podaci su dobiveni u osobnim razgovorima i osobnim posjetima na temelju pripremljenih anketa. Dobivene su značajne razlike među farmerima (viši stupanj obrazovanja u usporedbi s osnovnoškolskim obrazovanjem), s obzirom na standarde sigurnosti hrane, bolesti životinja, prinos mlijeka upotrebu strojeva za mužnju, posuda za hlađenje mlijeka, identifikaciju životinja, registar farme, hranidbu životinja prema stupnju proizvodnje, itd. Svijest, programi obrazovanja i prakse za mliječne farmere mogu poboljšati hranidbu životinja, prinos mlijeka krava, nadziranje bolesti životinja i smanjiti rizik zdravlja ljudi mlijekom prenosivim zoonozama. Također, planove za poticaje javnosti i darovatelje farmerima treba usko povezati s provođenjem standarda sigurnosti hrane

The Rosario dataset: Multisensor data for localization and mapping in agricultural environments

In this paper we present the Rosario dataset, a collection of sensor data for autonomous mobile robotics in agricultural scenes. The dataset is motivated by the lack of realistic sensor readings gathered by a mobile robot in such environments. It consists of six sequences recorded in soybean fields showing real and challenging cases: highly repetitive scenes, reflection, and burned images caused by direct sunlight and rough terrain among others. The dataset was conceived in order to provide a benchmark and contribute to the agricultural simultaneous localization and mapping (SLAM)/odometry and sensor fusion research. It contains synchronized readings of several sensors: wheel odometry, inertial measurement unit (IMU), stereo camera, and a Global Positioning System real-time kinematics (GPS-RTK) system. The dataset is publicly available from http://www.cifasis-conicet.gov.ar/robot/

Hard Exclusive Pion Electroproduction at Backward Angles With CLAS

We report on the first measurement of cross sections for exclusive deeply virtual pion electroproduction off the proton, ep → e\u27nπ+, above the resonance region at backward pion center-of-mass angles. The ϕ∗ π-dependent cross sections were measured, from which we extracted three combinations of structure functions of the proton. Our results are compatible with calculations based on nucleon-to-pion transition distribution amplitudes (TDAs). These non-perturbative objects are defined as matrix elements of threequark-light-cone-operators and characterize partonic correlations with a particular emphasis on baryon charge distribution inside a nucleon

Survival probability of large rapidity gaps in QCD and N=4 SYM motivated model

In this paper we present a self consistent theoretical approach for the calculation of the Survival Probability for central dijet production . These calculations are performed in a model of high energy soft interactions based on two ingredients:(i) the results of N=4 SYM, which at the moment is the only theory that is able to deal with a large coupling constant; and (ii) the required matching with high energy QCD. Assuming, in accordance with these prerequisites, that soft Pomeron intercept is rather large and the slope of the Pomeron trajectory is equal to zero, we derive analytical formulae that sum both enhanced and semi-enhanced diagrams for elastic and diffractive amplitudes. Using parameters obtained from a fit to the available experimental data, we calculate the Survival Probability for central dijet production at energies accessible at the LHC. The results presented here which include the contribution of semi-enhanced and net diagrams, are considerably larger than our previous estimates.Comment: 11 pages, 10 pictures in .eps file

Indication of asymptotic scaling in the reactions dd→p3dd\to p^3H, dd→n3dd\to n^3He and dp→dpdp\to dp

It is shown that the differential cross sections of the reactions $dd\to ^3He n$ and $dd\to ^3H p$ measured at c.m.s.scattering angle$\theta_{cm}=60^\circ$ in the interval of the deuteron beam energy 0.5 - 1.2 GeV demonstrate the scaling behaviour,$d\sigma/d t\sim s^{-22}$, which follows from constituent quark counting rules. It is found also that the differential cross section of the elastic $dp\to dp$ scattering at $\theta_{cm}=125^\circ-135^\circ$ follows the scaling regime $\sim s^{-16}$ at beam energies 0.5 - 5 GeV. These data are parameterized here using the Reggeon exchange.Comment: 6 pages, Latex, 2 eps figures; final version accepted by Pis'ma v ZHETF, corrected and completed reference

Hadron Helicity Violation in Exclusive Processes: Quantitative Calculations in Leading Order QCD

We study a new mechanism for hadronic helicity flip in high energy hard exclusive reactions. The mechanism proceeds in the limit of perfect chiral symmetry, namely without any need to flip a quark helicity. The fundamental feature of the new mechanism is the breaking of rotational symmetry of the hard collision by a scattering plane in processes involving independent quark scattering. We show that in the impulse approximation there is no evidence for of the helicity violating process as the energy or momentum transfer $Q^2$ is increased over the region 1 GeV^2 < Q^2 < 100 GeV^2. In the asymptotic region Q^2> 1000 GeV^2, a saddle point approximation with doubly logarithmic accuracy yields suppression by a fraction of power of Q^2. ``Chirally--odd" exclusive wave functions which carry non--zero orbital angular momentum and yet are leading order in the high energy limit, play an important role.Comment: uuencoded LaTeX file (21 pages) and PostScript figure

Generalized parton distributions in the deuteron

We introduce generalized quark and gluon distributions in the deuteron, which can be measured in exclusive processes like deeply virtual Compton scattering and meson electroproduction. We discuss the basic properties of these distributions, and point out how they probe the interplay of nucleon and parton degrees of freedom in the deuteron wave function

Description of LHC data in a soft interaction model

We show in this paper that we have found a set of parameters in our model for the soft interactions at high energy, that successfully describes all high energy experimental data, including the LHC data. This model is based on a single Pomeron with large intercept \Delta_\pom = 0.23 and slope \alpha'_\pom = 0, that describes both long and short distance processes. It also provides a natural matching with perturbative QCD. All features of our model are similar to the expectations of N=4 SYM, which at present is the only theory that is able to treat srong interactions on a theoretical basis.Comment: 11 pages with 7 figures in eps format

Pedagogic model for Deeply Virtual Compton Scattering with quark-hadron duality

We show how quark-hadron duality can emerge for valence spin averaged structure functions, and for the non-forward distributions of Deeply Virtual Compton Scattering. Novel factorisations of the non-forward amplitudes are proposed. Some implications for large angle scattering and deviations from the quark counting rules are illustrated.Comment: Version accepted by Phys. Rev.