scholarly journals CHARGED PION PHOTOPRODUCTION FROM HYDROGEN AND DEUTERIUM AT JEFFERSON LAB

2003 ◽  
Vol 18 (02n06) ◽  
pp. 215-224
Author(s):  
◽  
HAIYAN GAO
Keyword(s):  
Cross Sections ◽  
Degrees Of Freedom ◽  
Charged Pion ◽  
Center Of Mass ◽  
Oscillatory Behavior ◽  
Color Transparency ◽  
Jefferson Lab ◽  
Glauber Theory ◽  
Nuclear Dependence ◽  
Exclusive Processes

The γn → π-p and γp → π+n reactions are essential probes of the transition from meson-nucleon degrees of freedom to quark-gluon degrees of feedom in exclusive processes. The cross sections of these processes are also, advantageous, for the investigation of oscillatory behavior around the quark counting prediction, since they decrease relatively slower with energy compared with other photon-induced processes. Moreover, these photoreactions in nuclei can probe the QCD nuclear filtering and color transparency effects. In this talk, I discuss the preliminary results on the γp → π+n and γn → π-p processes at a center-of-mass angle of 90° from Jefferson Lab experiment E94-104. I also discuss a new experiment in which singles γp → π+n measurement from hydrogen, and coincidence γn → π-p measurements at the quasifree kinematics from deuterium and 12 C for photon energies between 2.25 GeV to 5.8 GeV in fine steps at a center-of-mass angle of 90° are planned. The proposed measurement will allow a detailed investigation of the oscillatory scaling behavior in photopion production processes and the study of the nuclear dependence of rather mysterious oscillations with energy that previous experiments have indicated. The various nuclear and perturbative QCD approaches, ranging from Glauber theory, to quark-counting, to Sudakov-corrected independent scattering, make dramatically different predictions for the experimental outcomes.

Scattering and fusion phenomena of 6Li +209Bi system

2020 ◽  
Vol 29 (03) ◽  
pp. 2050016
Author(s):  
R. R. Swain ◽  
C. Dash ◽  
P. Mohanty ◽  
B. B. Sahu
Keyword(s):  
Elastic Scattering ◽  
Partial Wave ◽  
Cross Section ◽  
Cross Sections ◽  
Center Of Mass ◽  
Fusion Cross Section ◽  
Oscillatory Behavior ◽  
Energy Formula ◽  
Cross Section Formula ◽  
Scattering Cross Sections

In nucleus–nucleus collisions, the partial-wave scattering matrix, for the total effective complex potential is calculated, which explains the data of angular distribution of elastic scattering cross-sections. Furthermore the absorption cross-section is obtained from the arbitrarily small intervals which helps to derive the fusion cross-section ([Formula: see text]) data at different center-of-mass energies ([Formula: see text]) by collecting the absorption contributions in the interior region of the effective potential. Here, the potential is taken as energy independent and its weakly absorbing nature supports the resonance states in various partial-wave trajectories. Therefore, the resonances show oscillatory behavior changes with respect to energy [Formula: see text], which is the second derivative of the product [Formula: see text] with respect to [Formula: see text]. In this paper, we have successfully discussed the elastic scattering and fusion cross-sections simultaneously with the results of [Formula: see text].

scholarly journals A Dynamical Study of Fusion Hindrance with Nakajima-Zwanzig Projection Method

2021 ◽  
Author(s):  
Yasuhisa Abe ◽  
David Boilley ◽  
Quentin Hourdillé ◽  
Caiwan Shen
Keyword(s):  
Cross Sections ◽  
Degrees Of Freedom ◽  
Operator Method ◽  
Initial Distribution ◽  
Physical Parameters ◽  
Relaxation Processes ◽  
Fast Variable ◽  
Dynamical Study ◽  
Injection Point ◽  
Slow Variables

Abstract A new framework is proposed for the study of collisions between very heavy ions which lead to the synthesis of Super-Heavy Elements (SHE), to address the fusion hindrance phenomenon. The dynamics of the reaction is studied in terms of collective degrees of freedom undergoing relaxation processes with different time scales. The Nakajima-Zwanzig projection operator method is employed to eliminate fast variable and derive a dynamical equation for the reduced system with only slow variables. There, the time evolution operator is renormalised and an inhomogeneous term appears, which represents a propagation of the given initial distribution. The term results in a slip to the initial values of the slow variables. We expect that gives a dynamical origin of the so-called “injection point s” introduced by Swiatecki et al in order to reproduce absolute values of measured cross sections for SHE. A formula for the slip is given in terms of physical parameters of the system, which confirms the results recently obtained with a Langevin equation, and permits us to compare various incident channels.

scholarly journals Measurements of the differential cross sections of the production of Z + jets and γ + jets and of Z boson emission collinear with a jet in pp collisions at $$ \sqrt{s} $$ = 13 TeV

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
◽  
A. M. Sirunyan ◽  
A. Tumasyan ◽  
W. Adam ◽  
F. Ambrogi ◽  
...  
Keyword(s):  
Cross Sections ◽  
Differential Cross ◽  
Z Boson ◽  
Center Of Mass ◽  
Z Bosons ◽  
Differential Cross Sections ◽  
Pp Collisions ◽  
Center Of Mass Energy ◽  
Cms Experiment ◽  
Theoretical Predictions

Abstract Measurements of the differential cross sections of Z + jets and γ + jets production, and their ratio, are presented as a function of the boson transverse momentum. Measurements are also presented of the angular distribution between the Z boson and the closest jet. The analysis is based on pp collisions at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 35.9 fb−1 recorded by the CMS experiment at the LHC. The results, corrected for detector effects, are compared with various theoretical predictions. In general, the predictions at higher orders in perturbation theory show better agreement with the measurements. This work provides the first measurement of the ratio of the differential cross sections of Z + jets and γ + jets production at 13 TeV, as well as the first direct measurement of Z bosons emitted collinearly with a jet.

SCATTERING AND DISSOCIATION OF DEUTERONS AND 3H-NUCLEI BY NUCLEI AT INTERMEDIATE ENERGIES

1995 ◽  
Vol 04 (03) ◽  
pp. 563-586 ◽  
Author(s):  
YU. A. BEREZHNOY ◽  
V. YU. KORDA
Keyword(s):  
Elastic Scattering ◽  
Closed Form ◽  
Cross Sections ◽  
Differential Cross ◽  
Particle System ◽  
Center Of Mass ◽  
Scattering Angle ◽  
Intermediate Energies ◽  
Oscillating Functions ◽  
Analytical Expressions

We present a closed-form description that enables us to obtain the analytical expressions for the elastic scattering and dissociation differential cross-sections of deuterons and 3H-nuclei by heavy target nuclei. The resulting expressions are used to analyze the data for the 110 MeV deuterons elastically scattered on 208Pb-nuclei. The dissociation cross-sections of deuterons and 3H-nuclei are the oscillating functions of the scattering angle of the released two- and three-nucleon-particle system center-of-mass.

THE STEREODYNAMICS STUDY OF THE C(3P) + OH (X2 Π) → CO(X1Σ+) + H(2S) REACTION

2010 ◽  
Vol 09 (05) ◽  
pp. 935-943 ◽  
Author(s):  
PENG SONG ◽  
YONG-HUA ZHU ◽  
JIAN-YONG LIU ◽  
FENG-CAI MA
Keyword(s):  
Angular Momentum ◽  
Cross Sections ◽  
Collision Energy ◽  
Energy Surface ◽  
Center Of Mass ◽  
Title Reaction ◽  
High Collision Energy ◽  
Dependency Relationship ◽  
Energy Dependency ◽  
Mass Frame

The stereodynamics of the title reaction on the ground electronic state X2A' potential energy surface (PES)1 has been studied using the quasiclassical trajectory (QCT) method. The commonly used polarization-dependent differential cross-sections (PDDCSs) of the product and the angular momentum alignment distribution, P(θr) and P(Φr), are generated in the center-of-mass frame using QCT method to gain insight of the alignment and orientation of the product molecules. Influence of collision energy on the stereodynamics is shown and discussed. The results reveal that the distribution of P(θr) and P(Φr) is sensitive to collision energy. The PDDCSs exhibit different collision energy dependency relationship at low and high collision energy ranges.

scholarly journals Measurement of cross sections for e+e−→μ+μ− at center-of-mass energies from 3.80 to 4.60 GeV

2020 ◽  
Vol 102 (11) ◽  
Author(s):  
M. Ablikim ◽  
M. N. Achasov ◽  
P. Adlarson ◽  
S. Ahmed ◽  
M. Albrecht ◽  
...  
Keyword(s):  
Cross Sections ◽  
Center Of Mass

Nonlinear Six-Degree-of-Freedom Dynamic Model for Risers, Pipelines, and Beams

1986 ◽  
Vol 30 (03) ◽  
pp. 177-185
Author(s):  
Michael M. Bernitsas ◽  
John E. Kokarakis
Keyword(s):  
Cross Sections ◽  
Degrees Of Freedom ◽  
Nonlinear Effects ◽  
Nonlinear Formulation ◽  
Marine Risers ◽  
Internal Fluid ◽  
Rotational Degrees Of Freedom ◽  
Six Degree Of Freedom ◽  
Structural Imperfections ◽  
Inertia Forces

A nonlinear model for the dynamic behavior of tubular beams such as marine risers, pipelines, legs of tension leg platforms, and drill strings is developed. The formulation includes three translational degrees of freedom of the riser cross section and three rotational degrees of freedom for shear and torsion. Nonlinear constitutive equations for cross sections of unequal principal stiffnesses and extensible material are derived. Initial structural imperfections which are inherent in long risers are modeled in the form of initial curvature and geometric torsion which do not induce strains. The inertia forces due to the motion of the riser and internal fluid motions are formulated. The external hydrodynamic and hydrostatic forces are integrated on the riser surface as pressure and traction forces. The model is a comprehensive consistent nonlinear formulation of the riser dynamics and can be used for evaluation of the significance of nonlinear effects.

scholarly journals The Use of Integrals in Numerical Integrations of theN-Body Problem

1971 ◽  
Vol 10 ◽  
pp. 40-51
Author(s):  
Paul E. Nacozy
Keyword(s):  
Angular Momentum ◽  
Numerical Integration ◽  
Degrees Of Freedom ◽  
Body Problem ◽  
Center Of Mass ◽  
Integration Step ◽  
Gravitational System ◽  
Systems Of Differential Equations ◽  
Numerical Integrations ◽  
Original Number

AbstractThe numerical integration of systems of differential equations that possess integrals is often approached by using the integrals to reduce the number of degrees of freedom or by using the integrals as a partial check on the resulting solution, retaining the original number of degrees of freedom.Another use of the integrals is presented here. If the integrals have not been used to reduce the system, the solution of a numerical integration may be constrained to remain on the integral surfaces by a method that applies corrections to the solution at each integration step. The corrections are determined by using linearized forms of the integrals in a least-squares procedure.The results of an application of the method to numerical integrations of a gravitational system of 25-bodies are given. It is shown that by using the method to satisfy exactly the integrals of energy, angular momentum, and center of mass, a solution is obtained that is more accurate while using less time of calculation than if the integrals are not satisfied exactly. The relative accuracy is ascertained by forward and backward integrations of both the corrected and uncorrected solutions and by comparison with more accurate integrations using reduced step-sizes.

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