scholarly journals Deeply Virtual Pseudoscalar Meson Production at Jefferson Lab and Transversity GPDs

2016 ◽  
Vol 40 ◽  
pp. 1660051 ◽  
Author(s):  
Valery Kubarovsky
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Pseudoscalar Meson ◽  
Meson Production ◽  
Form Factors ◽  
Theoretical Models ◽  
Text Data ◽  
Jefferson Lab ◽  
Wide Range ◽  
First Time

The cross section of the exclusive [Formula: see text] and [Formula: see text] electroproduction reaction [Formula: see text] was measured at Jefferson Lab with a 5.75-GeV electron beam and the CLAS detector. Differential cross sections [Formula: see text] and structure functions [Formula: see text] and [Formula: see text] as functions of [Formula: see text] were obtained over a wide range of [Formula: see text] and [Formula: see text]. The data are compared with the GPD based theoretical models. Analyses find that a large dominance of transverse processes is necessary to explain the experimental results. Generalized form factors of the transversity GPDs [Formula: see text] and [Formula: see text] were directly extracted from the experimental observables for the first time. It was found that GPD [Formula: see text] dominates in pseudoscalar meson production. The combined [Formula: see text] and [Formula: see text] data opens the way for the flavor decomposition of the transversity GPDs. The first ever evaluation of this decomposition was demonstrated.

scholarly journals Evaluation of the Compton (Incoherent) and Rayleigh (Coherent) Differential Cross Sections of Scattering for Rhodium 103Rh45 and Tantalum181Ta73 by Employing CSC model

2012 ◽  
Vol 9 (3) ◽  
pp. 554-558 ◽  
Author(s):  
Baghdad Science Journal
Keyword(s):  
Differential Cross Section ◽  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Form Factors ◽  
Differential Cross Sections ◽  
The Cross

The differential cross section for the Rhodium and Tantalum has been calculated by using the Cross Section Calculations (CSC) in range of energy(1keV-1MeV) . This calculations based on the programming of the Klein-Nashina and Rayleigh Equations. Atomic form factors as well as the coherent functions in Fortran90 language Machine proved very fast an accurate results and the possibility of application of such model to obtain the total coefficient for any elements or compounds.

scholarly journals ω AND η (η') MESONS FROM NN AND ND COLLISIONS AT INTERMEDIATE ENERGIES

2010 ◽  
Vol 19 (05n06) ◽  
pp. 894-902 ◽  
Author(s):  
L. P. KAPTARI ◽  
B. KÄMPFER
Keyword(s):  
Cross Sections ◽  
Good Description ◽  
Meson Production ◽  
Form Factors ◽  
Angular Distributions ◽  
Transition Form ◽  
Vector Meson Production ◽  
Intermediate Energies ◽  
Electron Production ◽  
Pseudo Scalar

The production of pseudo scalar, η, η′, and vector, ω, ρ, ϕ, mesons in NN collisions at threshold-near energies is analyzed within a covariant effective meson-nucleon theory. It is shown that a good description of cross sections and angular distributions, for vector meson production, can be accomplished by considering meson and nucleon currents only, while for pseudo scalar production an inclusion of nucleon resonances is needed. The di-electron production from subsequent Dalitz decay of the produced mesons, η′ → γγ* → γe+e- and ω → πγ* → πe+e- is also considered and numerical results are presented for intermediate energies and kinematics of possible experiments with HADES, CLAS and KEK-PS. We argue that the transition form factor ω → γ*π as well as η′ → γ*γ can be defined in a fairly model independent way and the feasibility of an experimental access to transition form factors is discussed.

Investigation of the synthesis of the unknown superheavy nuclei 309,312126

2019 ◽  
Vol 28 (07) ◽  
pp. 1950056 ◽  
Author(s):  
T. V. Nhan Hao ◽  
N. N. Duy ◽  
K. Y. Chae ◽  
N. Quang Hung ◽  
N. Nhu Le
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Charge Asymmetry ◽  
Evaporation Residue ◽  
Fission Process ◽  
Dinuclear System ◽  
Mass Asymmetry ◽  
Interacting Systems ◽  
First Time ◽  
Text Element

In this paper, we applied the method developed by Santhosh and Safoora in [Phys. Rev. C  94 (2016) 024623; 95 (2017) 064611] to theoretically investigate the fusion, evaporation-residue (ER) and fission cross-sections of the synthesis of the unknown superheavy [Formula: see text]126 nuclei produced by using the [Formula: see text]Ni + [Formula: see text]Cf and [Formula: see text]Zn + [Formula: see text]Cm combinations. The charge asymmetry, mass asymmetry and fissility of the DiNuclear System (DNS) in the synthesis of the mentioned combinations are also estimated. The calculated results show that the ER cross-sections for the synthesis of the [Formula: see text]126 nuclei are predicted to be much less than 1.0[Formula: see text]fb. In particular, it has been found that there may exist a valley of the ER cross-sections in the synthesis of a superheavy [Formula: see text] element, which produces the [Formula: see text]126 isotope. Subsequently, a model for the mass dependence of the ER cross-section in the synthesis of the [Formula: see text]126 isotopes has been proposed for the first time. On the other hand, the quasi-fission process strongly dominates over the fusion in the two concerned interacting systems. The present results, together with those reported in the previous studies, indicate that the investigated projectile–target combinations are not capable for the synthesis of the [Formula: see text]126 isotopes due to tiny fusion cross-sections (about 2–3[Formula: see text]zb), which go beyond the limitations of available facilities. Further studies are thus recommended to search for alternative interacting systems. In conclusion, this work provides useful information for the synthesis of the gap isotopes [Formula: see text]126, which have not been well studied up to date.

QCD JETS AT HERA I.: O(αs) RADIATIVE CORRECTIONS TO ELECTROWEAK CROSS SECTIONS AND JET RATES

1989 ◽  
Vol 04 (07) ◽  
pp. 1781-1825 ◽  
Author(s):  
JÜRGEN G. KÖRNER ◽  
ERWIN MIRKES ◽  
GERHARD A. SCHULER
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Neutral Current ◽  
High Energy ◽  
Coupling Constant ◽  
Bjorken Scaling ◽  
Born Cross Section ◽  
Wide Range ◽  
Lepton Polarization ◽  
Jet Cross Sections

We present the complete O(αs) corrections to the electroweak cross sections of both neutral current and charged current deep inelastic e±p scattering including lepton polarization effects. Changes in the cross section due to the inclusion of next-to-leading-log (NLL) effects are parametrized by K factors, which are defined as the ratio of the NLL O(αs) cross sections and the Born cross section. Using the standard redefinition scheme of the parton densities, we find that the K factors deviate substantially from unity for small values of the Bjorken-Scaling variable x. We also elaborate on problems that arise when defining jet cross sections in ep scattering and present numerical results for the O(αs) 3-jet and 2-jet rates. We observe that the Q2-dependence of the 3-jet rate is dominated by the running strong coupling constant αs(Q2) allowing for its determination over a wide range in Q2 at high energy ep colliders.

OPEN b PRODUCTION IN TWO-PHOTON COLLISIONS IN DELPHI

2005 ◽  
Vol 20 (02n03) ◽  
pp. 661-663
Author(s):  
◽  
FRÉDÉRIC KAPUSTA
Keyword(s):  
Perturbative Qcd ◽  
Cross Section ◽  
Cross Sections ◽  
Semileptonic Decays ◽  
Two Photon ◽  
Delphi Detector ◽  
Quark Production ◽  
The Cross ◽  
First Time

Heavy b and c quark production in γγ collisions has been measured through semileptonic decays with the DELPHI detector at LEPII. The measured cross-sections are compared to NLO perturbative QCD calculations. The cross-section for b production is found to exceed QCD predictions. The K-lepton double tagging, used for the first time in γγ physics confirms this excess.

Electron energy distributions in uniform electric fields and the Townsend ionization coefficient

1958 ◽  
Vol 244 (1237) ◽  
pp. 166-185 ◽  
Keyword(s):  
Differential Equation ◽  
Cross Section ◽  
Electric Fields ◽  
Cross Sections ◽  
Collision Cross Section ◽  
Present Theory ◽  
Uniform Electric Field ◽  
Ionization Coefficient ◽  
Special Cases ◽  
Wide Range

The second-order differential equation which expresses the equilibrium condition of an electron swarm in a uniform electric field in a gas, the electrons suffering both elastic and inelastic collisions with the gas molecules, is solved by the Jeffreys or W.K.B. method of approximation. The distribution function F(ε) of electrons of energy ε is obtained immediately in a general form involving the elastic and inelastic collision cross-sections and without any restriction on the range of E/p (electric strength/gas pressure) save that introduced in the original differential equation. In almost all applications the approximation is likely to be of high accuracy, and easy to use. Several of the earlier derivations of F(ε) are obtained as special cases. Using the function F(ε) an attempt is made to relate the Townsend ionization coefficient a to the properties of the gas in a more general manner than hitherto, using realistic functions for the collision cross-section. It is finally expressed by the equation α/ p = A exp ( — Bp/E ) in which A and B are functions involving the properties of the gas and the ratio E/p . The important coefficient B is directly related to the form and magnitude of the total inelastic cross-section below the ionization potential and can be evaluated for a particular gas once the cross-section is known experimentally. The present theory shows clearly the influence of E/p on both A and B, a matter which has not been satisfactorily discussed previously. The theory is illustrated by calculations of F (ε) and a/p for hydrogen over a range of E/p from 10 to 1000. The agreement between the calculated results and recent reliable observations of α/ p is surprisingly good considering the nature of the calculations and the wide range of E/p .

Predictions of ρ meson cross-sections between AdS/QCD and boosted Gaussian wave functions in the color glass condensate model

2017 ◽  
Vol 32 (14) ◽  
pp. 1750081
Author(s):  
Jianquan Xie ◽  
Hui Peng
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Light Cone ◽  
Gaussian Model ◽  
Meson Production ◽  
Wave Functions ◽  
Dipole Model ◽  
Color Glass ◽  
Color Glass Condensate ◽  
Dipole Cross Section

Exclusive [Formula: see text] meson production is computed in dipole model using two different light-cone wave functions in this paper. The Color-Glass-Condensate (CGC) model is implemented to compute the dipole cross-section. The two light-cone wave functions are AdS/QCD model and boosted Gaussian model. It can be seen that the predictions using the two light-cone wave functions are close to each other.

On Non-Boussinesq Gravity Currents in Non-Rectangular Cross-Section Channels

2014 ◽  
Author(s):  
T. Zemach
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Rectangular Cross Section ◽  
Gravity Current ◽  
Classical Formulation ◽  
Wide Range ◽  
Front Condition ◽  
Significant Generalization ◽  
Self Similar ◽  
Cross Section Geometry

We consider the propagation of a gravity current of density ρc from a lock length x0 and height h0 into an ambient fluid of density ρa in a horizontal channel of height H along the horizontal coordinate x. The bottom and top of the channel are at z = 0, H, and the cross-section is given by the quite general −f1(z) ≤ y ≤ f2(z) for 0 ≤ z ≤ H. When the Reynolds number is large, the resulting flow is governed by the parameters R = ρc/ρa, H* = H/h0 and f(z) = f1(z) + f2(z). We show that the shallow-water one-layer model, combined with a Benjamin-type front condition, provides a versatile formulation for the thickness h and speed u of the current. The results cover in a continuous manner the range of light ρc/ρa ≪ 1, Boussinesq ρc/ρa ≈ 1 and heavy ρc/ρa ≫ 1 currents in a fairly wide range of depth ratio in various cross-section geometries. We obtain analytical solutions for the initial dam-break stage of propagation with constant speed, which appears for any cross-section geometry, and derive explicitly the trend for small and large values of the governing parameters. For large time, t, a self-similar propagation is feasible for f(z) = bzα cross-sections only, with t(2+2α)/(3+2α). The present approach is a significant generalization of the classical non-Boussinesq gravity current problem. The classical formulation for a rectangular (or laterally unbounded) channel is now just a particular case, f(z) = const., in the wide domain of cross-sections covered by this new model.

scholarly journals THE MESON PRODUCTION IN PROTON–PROTON COLLISIONS IN NEXT-TO-LEADING ORDER AND INFRARED RENORMALONS

2011 ◽  
Vol 20 (05) ◽  
pp. 1243-1270 ◽  
Author(s):  
A. I. AHMADOV ◽  
R. M. BURJALIYEV
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Production Cross ◽  
Meson Production ◽  
Leading Order ◽  
Proton Proton ◽  
Proton Collisions ◽  
Running Coupling ◽  
Coupling Approach ◽  
Proton Proton Collisions

In this paper, we investigate the next-to-leading order contribution of the higher-twist Feynman diagrams to the large-pT inclusive pion production cross-section in proton–proton collisions and present the general formulae for the higher-twist differential cross-sections in the case of the running coupling and frozen coupling approaches. We compared the resummed next-to-leading order higher-twist cross-sections with the ones obtained in the framework of the frozen coupling approach and leading-twist cross-section. The structure of infrared renormalon singularities of the higher-twist subprocess cross-section and its resummed expression (the Borel sum) are found. It is shown that the resummed result depends on the choice of the meson wave functions used in the calculations. We discuss the phenomenological consequences of possible higher-twist contributions to the meson production in proton–proton collisions in next-to-leading order at RHIC.

The absolute photoionization cross sections of helium, neon, argon and krypton in the extreme vacuum ultraviolet region of the spectrum

1976 ◽  
Vol 349 (1658) ◽  
pp. 397-421 ◽  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Vacuum Ultraviolet ◽  
Theoretical Calculations ◽  
Critical Evaluation ◽  
Inert Gases ◽  
Ultraviolet Region ◽  
Section Data ◽  
Wide Range ◽  
Helium Neon

An experiment has been set up at the Daresbury Synchrotron Radiation Facility to make absolute absorption cross section measurements over a wide range of photon energies. New data are reported for helium, neon, argon and krypton over the range 340-40 Å which are believed to be reliable to ± 5%. A critical evaluation of published cross section data has been carried out to produce best value data from the ionization thresholds throughout the vacuum ultraviolet and X-ray region. Agreement with theoretical calculations on helium is demonstrated to be within ± 2-3% from threshold down to the double ionization threshold at 79 eV. Comparison with recent calculations of photoionization cross sections has shown that the effect of electron correlations is significant for the heavier inert gases. Contrary to previous claims, the position of the M shell maximum in krypton is located at 184 + 10 eV in good agreement with r. p. a. e. calculations. Oscillator strength sum rules have been examined and their moments calculated. Discrepancies developing towards the heavier inert gases suggests a decrease in polarizabilities and other atomic factors from those predicted by Hartree-Fock calculations.

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