scholarly journals INTRINSIC CHARM IN PROTON AND J/ψ PHOTOPRODUCTION AT HIGH ENERGIES

1994 ◽  
Vol 09 (12) ◽  
pp. 1083-1092 ◽  
Author(s):  
V. A. SALEEV
Keyword(s):  
Distribution Function ◽  
Quantum Chromodynamics ◽  
Cross Section ◽  
Gluon Fusion ◽  
Dominant Contribution ◽  
Charm Quarks ◽  
High Energies ◽  
Intrinsic Charm ◽  
Nonrelativistic Quark Model ◽  
Hera Collider

J/ψ and open charm photoproduction on charm quarks in a proton via partonic subprocess γc → J/ψc are discussed based on the perturbative theory of quantum chromodynamics and nonrelativistic quark model. It is shown that the value and energy dependence of the cross-section for such process depend remarkably on the choice of charm distribution function in a proton. In the region of small z = EJ/Eγ < 0.2 the contribution of the γc → J/ψc subprocess in the inelastic J/ψ photoproduction spectra is larger than the contribution of the photon-gluon fusion subprocess. At the energy range of HERA collider charm quarks contribution in the total inclusive J/ψ photoproduction cross-section may be equal to 60% of the dominant contribution of photon-gluon fusion mechanism.

scholarly journals Collinear expansion for color singlet cross sections

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Markus A. Ebert ◽  
Bernhard Mistlberger ◽  
Gherardo Vita
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Production Cross ◽  
Gluon Fusion ◽  
Building Blocks ◽  
Color Singlet ◽  
Final State ◽  
Beam Function ◽  
Kinematic Limit ◽  
State Radiation

Abstract We demonstrate how to efficiently expand cross sections for color-singlet production at hadron colliders around the kinematic limit of all final state radiation being collinear to one of the incoming hadrons. This expansion is systematically improvable and applicable to a large class of physical observables. We demonstrate the viability of this technique by obtaining the first two terms in the collinear expansion of the rapidity distribution of the gluon fusion Higgs boson production cross section at next-to-next-to leading order (NNLO) in QCD perturbation theory. Furthermore, we illustrate how this technique is used to extract universal building blocks of scattering cross section like the N-jettiness and transverse momentum beam function at NNLO.

SPECTRUM OF COSMIC RAYS WITH ENERGY ABOVE 1017 EV

2005 ◽  
Vol 20 (29) ◽  
pp. 6878-6880 ◽  
Author(s):  
V. P. EGOROVA ◽  
A. V. GLUSHKOV ◽  
A. A. IVANOV ◽  
S. P. KNURENKO ◽  
V. A. KOLOSOV ◽  
...  
Keyword(s):  
Distribution Function ◽  
Energy Spectrum ◽  
Cosmic Rays ◽  
Time Distribution ◽  
Arrival Time ◽  
Lateral Distribution ◽  
Arrival Time Distribution ◽  
Array Data ◽  
Lateral Distribution Function ◽  
High Energies

The energy spectrum of primary cosmic rays with ultra-high energies based on the Yakutsk EAS Array data is presented. For the largest events values of S600 and axis coordinates have been obtained using revised lateral distribution function. The effect of the arrival time distribution at several axis distance on estimated density for Yakutsk and AGASA is considered.

The probe particle scattering cross-section off the many-fermion systems in the impulse approximation

2021 ◽  
Author(s):  
Yahya Younesizadeh ◽  
Fayzollah Younesizadeh
Keyword(s):  
Experimental Data ◽  
Distribution Function ◽  
Spectral Function ◽  
Cross Section ◽  
Response Function ◽  
Momentum Distribution ◽  
Impulse Approximation ◽  
System Response ◽  
Probe Particle ◽  
Momentum Distribution Function

In this work, we study the differential scattering cross-section (DSCS) in the first-order Born approximation. It is not difficult to show that the DSCS can be simplified in terms of the system response function. Also, the system response function has this property to be written in terms of the spectral function and the momentum distribution function in the impulse approximation (IA) scheme. Therefore, the DSCS in the IA scheme can be formulated in terms of the spectral function and the momentum distribution function. On the other hand, the DSCS for an electron off the [Formula: see text] and [Formula: see text] nuclei is calculated in the harmonic oscillator shell model. The obtained results are compared with the experimental data, too. The most important result derived from this study is that the calculated DSCS in terms of the spectral function has a high agreement with the experimental data at the low-energy transfer, while the obtained DSCS in terms of the momentum distribution function does not. Therefore, we conclude that the response of a many-fermion system to a probe particle in IA must be written in terms of the spectral function for getting accurate theoretical results in the field of collision. This is another important result of our study.

scholarly journals Electron Transport in Argon - Hydrogen Mixtures

1980 ◽  
Vol 33 (6) ◽  
pp. 975 ◽  
Author(s):  
GN Haddad ◽  
RW Crompton
Keyword(s):  
Experimental Data ◽  
Distribution Function ◽  
Cross Section ◽  
Transport Coefficients ◽  
Velocity Distribution Function ◽  
Significant Error ◽  
Cross Section Data ◽  
Section Data ◽  
Hydrogen Mixtures ◽  
Legendre Expansion

The transport coefficients υdr and D⊥/μ have been measured in mixtures of 0.5 % and 4 % hydrogen in argon. All measurements were made at 293 K. It is shown that for these mixtures the use of the solution of the Boltzmann equation based on the two-term Legendre expansion of the velocity distribution function introduces no significant error in the analysis of the transport data. All the experimental data have been predicted to within � 3.5 % using previously published cross section data.

Electron Energy Dependence of Amorphization in Zr3Fe

1993 ◽  
Vol 316 ◽  
Author(s):  
A.T. Motta ◽  
L.M. Howe ◽  
P.R. Okamoto
Keyword(s):  
Electron Energy ◽  
Cross Section ◽  
Sharp Increase ◽  
Low Dose ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
High Energies ◽  
Intermediate Energies ◽  
Low Energies ◽  
Order Of Magnitude

ABSTRACTThis paper reports the results from a study conducted to determine the effect of electron energy on the dose-to-amorphization of Zr3Fe at 23-30 K. Zr3Fe samples were irradiated in the HVEM at Argonne National Laboratory, at energies ranging from 200 to 900 keV. Amorphization occurred at electron energies from 900 keV down to 250 keV. Three distinct regions were observed: between 900 and 700 keV amorphization occurred at a constant low dose of ~ 4 × 1021 e cm-2; a higher plateau at 1022 was observed between 600 and 400 keV, and finally there was a sharp increase in the dose-to-amorphization below 400 keV, so that at 250 keV the necessary dose was an order of magnitude higher than that at 900 keV. In the region below 400 keV there was evidence of a dependence of the dose-to-amorphization on the orientation of the sample with respect to the electron beam. The results can be analyzed in terms of a composite displacement cross section dominated at high energies by displacements of Zr and Fe atoms, by displacements of Fe atoms at intermediate energies and of secondary displacements of lattice atoms by recoil impurities at low energies.

INSTANTON-INDUCED CROSS-SECTION AT HIGH ENERGIES: LEADING ORDER AND BEYOND

1990 ◽  
Vol 05 (24) ◽  
pp. 1983-1991 ◽  
Author(s):  
S. YU. KHLEBNIKOV ◽  
V. A. RUBAKOV ◽  
P. G. TINYAKOV
Keyword(s):  
Total Cross Section ◽  
Explicit Form ◽  
Cross Section ◽  
High Energy ◽  
Electroweak Theory ◽  
Leading Order ◽  
Instanton Action ◽  
High Energies ◽  
High Energy Collisions ◽  
The One

We study the total cross-section of high energy collisions in the one-instanton sector of purely bosonic theories with instantons. We find that in the limit g2 → 0, E/E sph = fixed , the leading behavior of the total cross-section is σ lot ~ exp [1/g2(−2S0 + F(E/E sph ))], where S0 is the instanton action. In the electroweak theory at E/E sph ≪ 1, the function F(E/E sph ) is determined by the gauge boson part of the instanton configuration and its explicit form is found.

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