Upper bounds to the impact parameter and cross section for atom–diatom exchange reactions

1982 ◽  
Vol 77 (6) ◽  
pp. 2988-2995 ◽  
Author(s):  
Walter J. Chesnavich
Keyword(s):  
Cross Section ◽  
Impact Parameter ◽  
Upper Bounds ◽  
Exchange Reactions ◽  
The Impact

scholarly journals TACHYON DYNAMICS OF THE BLACK DISC LIMIT IN THE HARD SMALL x PROCESSES IN QCD

2006 ◽  
Vol 21 (07) ◽  
pp. 549-558 ◽  
Author(s):  
B. BLOK ◽  
L. FRANKFURT
Keyword(s):  
Cross Section ◽  
Impact Parameter ◽  
High Energy ◽  
Black Disk ◽  
Black Disc ◽  
Energy Behavior ◽  
Small X ◽  
The Cross ◽  
The Impact ◽  
Black Disc Limit

We investigate the effective field theory (EFT) which gives the approximate description of the scattering of two hard small dipoles in the small x processes in QCD near the black disc limit (BDL). We argue that the perturbative QCD approaches predict the existence of tachyon and visualize it in the approximation where α′P=0. We demonstrate that the high energy behavior of the cross-section depends strongly on the diffusion law in the impact parameter plane. On the other hand, almost threshold behavior of the cross section of the hard processes and multiplicities, i.e. fast increase of cross sections (color inflation), melting of ladders into color network and softening of the longitudinal distributions of hadrons are qualitatively insensitive to the value of diffusion in the impact parameter space. We evaluate α′P near the black disk limit and find significant α′P as the consequence of the probability conservation.

Dynamically Screened Elastic Collisions in Nonideal Plasmas

2006 ◽  
Vol 61 (7-8) ◽  
pp. 330-334
Author(s):  
Dong-Man Chang ◽  
Won-Seok Chang ◽  
Young-Dae Jung
Keyword(s):  
Cross Section ◽  
Impact Parameter ◽  
Thermal Energy ◽  
Collision Energy ◽  
Debye Length ◽  
Parameter Analysis ◽  
Ion Collisions ◽  
Dynamic Screening ◽  
Nonideal Plasmas ◽  
The Impact

The dynamic screening effects on elastic electron-ion collisions are investigated in nonideal plasmas. The second-order eikonal method with the impact parameter analysis is employed to obtain the eikonal phase as a function of the impact parameter, collision energy, thermal energy, and Debye length. The result shows that the eikonal phase decreases with increasing the thermal energy. It is also found that the dynamic screening effects on the eikonal phase are more significant for large impact parameters. The total eikonal cross section is also found to be decreased with increasing the thermal energy. It is important to note that the eikonal cross section and the eikonal phase including the dynamic screening effects are found to be greater than those including the static screening effects.

scholarly journals The cos 2ϕ azimuthal asymmetry in ρ0 meson production in ultraperipheral heavy ion collisions

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Hongxi Xing ◽  
Cheng Zhang ◽  
Jian Zhou ◽  
Ya-Jin Zhou
Keyword(s):  
Transverse Momentum ◽  
Vector Meson ◽  
Cross Section ◽  
Impact Parameter ◽  
Heavy Ion Collisions ◽  
Decay Product ◽  
Heavy Ion ◽  
Azimuthal Asymmetry ◽  
Ion Collisions ◽  
The Impact

Abstract We present a detailed study of vector meson photoproduction in ultraperipheral heavy ion collisions (UPCs). Using the dipole model, we develop a framework for the joint impact parameter and transverse momentum dependent cross sections. We compute the unpolarized cross section and cos 2ϕ azimuthal angular correlation for ρ0 photoproduction with ϕ defined as the angle between the ρ0’s transverse momentum and its decay product pion meson’s transverse momentum. Our result on unpolarized coherent differential cross section gives excellent description to the STAR experimental data. A first compari- son between theoretical calculation and experimental measurement on the cos 2ϕ azimuthal asymmetry, which results from the linearly polarized photons, is performed and reasonable agreement is reached. We find out the characteristic diffractive patterns at both RHIC and LHC energies and predict the impact parameter dependent cos 2ϕ azimuthal asymmetries for ρ0 photoproduction by considering UPCs and peripheral collisions. The future experimental measurements at RHIC and LHC relevant to our calculations will provide a tool to rigorously investigate the coherent and incoherent production of vector meson in UPCs, as well as to probe the nuclear structure in heavy ion collisions.

scholarly journals Secondary dips and the asymptotics

2018 ◽  
Vol 33 (06) ◽  
pp. 1850040 ◽  
Author(s):  
S. M. Troshin ◽  
N. E. Tyurin
Keyword(s):  
Elastic Scattering ◽  
Differential Cross Section ◽  
Cross Section ◽  
Impact Parameter ◽  
Differential Cross ◽  
Energy Region ◽  
Proton Proton ◽  
Asymptotic Energy ◽  
The Impact

We point out how to detect experimentally the energy region where asymptotics start to manifest themselves by relating the appearance of the secondary dips in the differential cross-section of elastic scattering [Formula: see text] with the beginning of the asymptotic energy region. The consideration relies on differential characteristics. The impact parameter picture of proton–proton interactions is used.

Impact Parameter Representation of the Scattering Amplitude

1971 ◽  
Vol 49 (14) ◽  
pp. 1885-1898 ◽  
Author(s):  
M. Razavy
Keyword(s):  
Elastic Scattering ◽  
Phase Shift ◽  
Differential Cross Section ◽  
Cross Section ◽  
Impact Parameter ◽  
Differential Cross ◽  
Scattering Amplitude ◽  
Potential Methods ◽  
Energy Dependent ◽  
The Impact

From the Lippmann–Schwinger equation, the exact and different approximate relations for the impact parameter form of the total scattering amplitude on- and off-the-energy shell are derived. The relation between the impact parameter phase shift and the range of potential is studied, and several methods of determining the potential from the impact parameter phase shift for local, nonlocal, and energy dependent interactions are obtained in Blankenbecler and Goldberger's approximation. By considering solvable examples it is shown that the Glauber's approximation, in certain cases, may be valid for all scattering angles. Finally for completely elastic scattering or for a purely absorptive potential, methods of finding the impact parameter phase shift from the differential cross section for scattering are given.

scholarly journals Factorization and transverse phase-space parton distributions

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Bin Wu
Keyword(s):  
Phase Space ◽  
Cross Section ◽  
Impact Parameter ◽  
Fourier Transforms ◽  
Distribution Functions ◽  
Glauber Model ◽  
Effective Theory ◽  
Factorization Formula ◽  
Parameter Dependent ◽  
The Impact

Abstract We first revisit impact-parameter dependent collisions of ultra-relativistic particles in quantum field theory. Two conditions sufficient for defining an impact-parameter dependent cross section are given, which could be violated in proton-proton collisions. By imposing these conditions, a general formula for the impact-parameter dependent cross section is derived. Then, using soft-collinear effective theory, we derive a factorization formula for the impact-parameter dependent cross section for inclusive hard processes with only colorless final-state products in hadron and nuclear collisions. It entails defining thickness beam functions, which are Fourier transforms of transverse phase-space parton distribution functions. By modelling non-perturbative modes in thickness beam functions of large nuclei in heavy-ion collisions, the factorization formula confirms the cross section in the Glauber model for hard processes. Besides, the factorization formula is verified up to one loop in perturbative QCD for the inclusive Drell-Yan process in quark-antiquark collisions at a finite impact parameter.

scholarly journals A note on the relations between elastic and inelastic interactions and increasing ratio σel(s)/σtot(s) at the LHC

2019 ◽  
Vol 34 (32) ◽  
pp. 1950259 ◽  
Author(s):  
S. M. Troshin ◽  
N. E. Tyurin
Keyword(s):  
Elastic Scattering ◽  
Energy Dependence ◽  
Impact Parameter ◽  
Cross Sections ◽  
Parameter Dependence ◽  
Slope Parameter ◽  
Short Notice ◽  
Inelastic Interactions ◽  
The Impact ◽  
Mode A

We comment briefly on relations between the elastic and inelastic cross-sections valid for the shadow and reflective modes of the elastic scattering. Those are based on the unitarity arguments. It is shown that the redistribution of the probabilities of the elastic and inelastic interactions (the form of the inelastic overlap function becomes peripheral) under the reflective scattering mode can lead to increasing ratio of [Formula: see text] at the LHC energies. In the shadow scattering mode, the mechanism of this increase is a different one, since the impact parameter dependence of the inelastic interactions probability is central in this mode. A short notice is also given on the slope parameter and the leading contributions to its energy dependence in both modes.

scholarly journals Charged current Drell-Yan production at N3LO

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Claude Duhr ◽  
Falko Dulat ◽  
Bernhard Mistlberger
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Production Cross Section ◽  
Production Cross ◽  
Hadron Collider ◽  
Charge Asymmetry ◽  
Charged Current ◽  
Leading Order ◽  
Neutrino Pair ◽  
The Impact

Abstract We present the production cross section for a lepton-neutrino pair at the Large Hadron Collider computed at next-to-next-to-next-to-leading order (N3LO) in QCD perturbation theory. We compute the partonic coefficient functions of a virtual W± boson at this order. We then use these analytic functions to study the progression of the perturbative series in different observables. In particular, we investigate the impact of the newly obtained corrections on the inclusive production cross section of W± bosons, as well as on the ratios of the production cross sections for W+, W− and/or a virtual photon. Finally, we present N3LO predictions for the charge asymmetry at the LHC.

scholarly journals Mechanical Properties of Spruce Wood Extracted from GLT Beams Loaded by Fire

2021 ◽  
Vol 13 (10) ◽  
pp. 5494
Author(s):  
Lucie Kucíková ◽  
Michal Šejnoha ◽  
Tomáš Janda ◽  
Jan Sýkora ◽  
Pavel Padevět ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Cross Section ◽  
Negative Impact ◽  
Tensile Tests ◽  
Thermal Recovery ◽  
Bending Test ◽  
Small Scale ◽  
Spruce Wood ◽  
The Impact

Heating wood to high temperature changes either temporarily or permanently its physical properties. This issue is addressed in the present contribution by examining the effect of high temperature on residual mechanical properties of spruce wood, grounding on the results of full-scale fire tests performed on GLT beams. Given these tests, a computational model was developed to provide through-thickness temperature profiles allowing for the estimation of a charring depth on the one hand and on the other hand assigning a particular temperature to each specimen used subsequently in small-scale tensile tests. The measured Young’s moduli and tensile strengths were accompanied by the results from three-point bending test carried out on two groups of beams exposed to fire of a variable duration and differing in the width of the cross-section, b=100 mm (Group 1) and b=160 mm (Group 2). As expected, increasing the fire duration and reducing the initial beam cross-section reduces the residual bending strength. A negative impact of high temperature on residual strength has also been observed from simple tensile tests, although limited to a very narrow layer adjacent to the charring front not even exceeding a typically adopted value of the zero-strength layer d0=7 mm. On the contrary, the impact on stiffness is relatively mild supporting the thermal recovery property of wood.

Sign in / Sign up

Export Citation Format

Share Document