Analysis of multi-jet events in electron - positron annihilation
M. E. Zomorrodian
author
A. Mahmoodabadi
author
text
article
2019
per
Analysis of electron – positron annihilation into hadrons in the range of energies above 60 GeV shows that apart from two jet events, there are evidence for three jet events that according to the QCD theory interpreted as a gluon radiation by a quark. However, the higher order diagrams lead to four jet events. In this paper, we study the fragmentation of quarks and gluons into hadronic jets . Acoplanarity(AC), is a parameter for our analysis of four jet events.We expect that four jet events have AC values opposite to zero. This result is consistent with results obtained from the Monte Carlo studies as well as the results obtained at lower energies. Possible explanation for all these features will be explained in this paper .
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
6
v.
4
no.
2019
239
243
http://ijpr.iut.ac.ir/article_527_f9e4f97f03073a01238b45f1c37258cb.pdf
Stability of solitary solutions to the cubic-quintic coupled nonlinear SchrÃ¶dinger equation(CQCNLSE)
M. Moradi
author
M. M. Golshan
author
text
article
2019
per
In this article we report the results of an investigation on the stability of solitary solutions to the Cubic-Quintic Coupled Nonlinear Schr ö dinger Equations.Using the theory of linear operators (here,2×2 matrics), we show that under a perturbation ui→ui + δui(δui= (αi(T) + ibi(T))eµδ)(i=1,2) the solitary solutions are stable. Moreover,we include the perturbation into the corresponding Hamiltonian and calculate the first and second order variations. Stability of the solitary solutions to the Coupled equations is then verified by the fact that the first- order variation vanishes and the second- order one is positive.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
6
v.
4
no.
2019
245
251
http://ijpr.iut.ac.ir/article_528_445d356f41aa51cca17edeffeb62da7c.pdf
Numerical study of electronic density of states and conductance of a molecular wire coupled with an external molecule
S. A. Ketabi
author
N. Shahtahmasebi
author
R. Pilevar
author
text
article
2019
per
There is a great interest in the electronic properties of conjugated polymers. Numerous works on the electronic and conduction properties of single-chain conjugated polymers have been published. From an electronic conduction point of view, these systems are quasi-one dimensional. The aim of this paper is to try to investigate corresponding properties in conducting polymers in higher of one-dimension. We study the electronic properties of a polyacetylene chain connected to other molecules. The effect of the size of the molecule and the strength of the coupling to the molecular wire is investigated. The results show that with the increase of the strength of the molecular wire/molecule coupling, the band gap of the system decreases and causes high electronic conduction.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
6
v.
4
no.
2019
253
260
http://ijpr.iut.ac.ir/article_529_e4f70925a0f4c1c0862e8d05c278a330.pdf
Optical properties and electronic structure of ceramics tetragonal PbTiO3 by using full-potential linearized augmented plane wave
H
Salehi
author
text
article
2019
per
The electronic structure and optical properties in tetragonal ceramics PbTiO3 are studied by using full-potential linearized augmented plane wave (FP-LAPW) method in density functional theory (DFT) with the generalized gradient approximation (GGA) by WIEN2K package. The theoretical calculated optical properties and energy loss (EEL) spectrum yield a static refractive index of 2.59 and a plasmon energy of 22.7eV for the tetragonal phase. The effective electron number at low energy saturates near 22-23eV with the value of 50 for the effective electron number. The results show a indirect band gap of 2.2eV at the Γ point in the Brillouin zone. The calculated band structure and density of states of PbTiO3 agree with previous experimental and theoretical results.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
6
v.
4
no.
2019
261
266
http://ijpr.iut.ac.ir/article_530_d41d8cd98f00b204e9800998ecf8427e.pdf
Recognizing chaotic states in stadium billiard by calculating gyration radius
M. Barezi
author
H. Mosadegh
author
B. Mirza
author
text
article
2019
per
Nowadays study of chaotic quantum billiards because of their relation to Nano technology. In this paper distribution of zeros of wave function on the boundary of two circular and stadium billiards are investigated. By calculating gyration radius for these points chaotic and non-chaotic states are distinguished.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
6
v.
4
no.
2019
275
281
http://ijpr.iut.ac.ir/article_531_55e61134aa41f824efdb8697181cf2a3.pdf
The study of scale in Persian music according to notes spectrums
A. Nadji
author
text
article
2019
per
In this paper we have extracted the notes of Iranian scale from the traditional music played by the great musician Shahnazi on the TAR. Then, by analyzing the spectrum of the notes and by using our special averaging we have found the pitch attributed to the components’ frequency and found the interval between the notes. The results are in comple agreement with Pythagorean scale. Pitch is a subjective quantity that attribute auditory sensation in terms of which sounds maybe ordered on a scale extending from low to high. For a pure tone pitch depends mainly on the frequency of the sound stimulus, but for complex tones or musical sounds pitch depends on partials of the complex tone and when the partials of a complex tone are not harmonic however the determination of pitch is more subtle. Indeed the vibrations of string instruments give rise to overtones which are not exactly multiples of fundamental, so the pitch of musical sound that we perceive is a subjective quantity related to frequencies of the overtones. In this paper we study the effect of partials in pitch of musical notes and by averaging between partials we introduce a subjective quantity which represents the pitch of musical note which is in quite agreement with experiments. As we know there are two famous scales for music, Aristoxenuss and Pythagoraean scale. The intervals in Aristoxenuss scale are and in Pythagorean scale are Farabi, the well-known philosopher, based Iranian traditional music on Pythagorean scale and our measurements of pitch and intervals of the notes show this scale has remained unchanged for a thousand years.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
6
v.
4
no.
2019
283
288
http://ijpr.iut.ac.ir/article_532_1163f9f30ef0259c65d0caf67a3c6e79.pdf
Design and fabrication of optical thin film layers with variable thickness profile for producing variable reflectivity mirrors
Hamid R fallah
author
A. Mobasheri
author
H. Saghafifar
author
text
article
2019
per
The design method and fabrication of mirrors with variable reflectivity are presented. To fabricate such a mirror a fixed mask with a circular aperture is used. The circular aperture is considered as an extended source with cosx(θ)as its diffusion distribution function and is the parameter for the distribution function of the particles through the aperture. The thickness profile of deposited layer is a function of this distribution. In this work, the coating system is calibrated for the materials which are used and then the parameter of the diffusion distribution function of the particles through the circular aperture is defined by experiments. Using these results, a graph is presented which connects the parameter of the circular aperture to the parameters of the thickness profile. It is then possible to deposit any type of variable reflectivity mirror using this graph. Finally, the effect of the uncertainty in measuring layer thicknesses on the phase of reflected wave and transmitted wave is investigated.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
6
v.
4
no.
2019
289
297
http://ijpr.iut.ac.ir/article_533_35025367fd26935712d84da2c48e8691.pdf
The properties of electron transport through CNT/trans-PA/CNT system
H
Milani Moghaddam
author
S A
Ketabi
author
N
Shahtahmasebi
author
text
article
2019
per
Using a tight-binding model and a tranfer-matrix technique, we numerically investigate the effects of the coupling strength, and the length of the molecule on the electronic transmission through a CNT/(single) molecule/CNT system. With trans-polyacetylene (trans-PA) as the molecule sandwiched between two semi-infinite carbon nanotube(CNT), we rely on Landauer formalism as the basis for studying the conductance properties of this system. Our calculations show that the conductance is sensitive to the CNT/molecule coupling and that it exponentially decreases with the increase in the length of the molecule, as expected.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
6
v.
4
no.
2019
298
298
http://ijpr.iut.ac.ir/article_534_a8d12f6674357768fafde89bf5c08f95.pdf