scholarly journals Two-pole structures in a relativistic Friedrichs–Lee-QPC scheme

2021 ◽  
Vol 81 (6) ◽  
Author(s):  
Zhi-Yong Zhou ◽  
Zhiguang Xiao

AbstractA general appearance of two-pole structures is exhibited in a relativistic Friedrichs–Lee model combined with a relativistic quark pair creation model in a consistent manner. This kind of two-pole structure could be found when a $$q\bar{q}$$ q q ¯ state couples to the open-flavor continuum state in the S partial wave. We found that many enigmatic states, such as $$f_0(500)/\sigma $$ f 0 ( 500 ) / σ , $$K_0^*(700)/\kappa $$ K 0 ∗ ( 700 ) / κ , $$a_0(980)$$ a 0 ( 980 ) , $$f_0(980)$$ f 0 ( 980 ) , $$D_0^*(2300)$$ D 0 ∗ ( 2300 ) , $$D_{s0}^*(2317)$$ D s 0 ∗ ( 2317 ) , and X(3872), together with another higher state for each, all result from this kind of two-pole structures. Furthermore, an interesting observation is that this kind of two-pole structure will contribute roughly a total of $$180^\circ $$ 180 ∘ phase shift for the scattering process in a single channel approximation. This relativistic scheme may provide more insights into the understanding of the properties of non-$$q\bar{q}$$ q q ¯ state. It is also suggested that such two-pole structure could be a common phenomenon which deserves studying both from theoretical and experimental perspectives.

2021 ◽  
Vol 81 (9) ◽  
Author(s):  
Zhong-Yu Wang ◽  
Hiwa A. Ahmed ◽  
C. W. Xiao

AbstractTo understand the nature of two poles for the $$\varLambda (1405)$$ Λ ( 1405 ) state, we revisit the interactions of $${\bar{K}}N$$ K ¯ N and $$\pi \Sigma $$ π Σ with their coupled channels, where two-pole structure is found in the second Riemann sheet. We also dynamically generate two poles in the single channel interaction of $${\bar{K}}N$$ K ¯ N and $$\pi \Sigma $$ π Σ , respectively. Moreover, we make a further study of two poles’ properties by evaluating the couplings, the compositeness, the wave functions, and the radii for the interactions of four coupled channels, two coupled channels and the single channel. Our results show that the nature of two poles is unique. The higher-mass pole is a pure $${\bar{K}} N$$ K ¯ N molecule, and the lower-mass one is a composite state of mainly $$\pi \Sigma $$ π Σ with tiny component $${\bar{K}} N$$ K ¯ N . From our results, one can conclude that the $$\varLambda (1405)$$ Λ ( 1405 ) state may be overlapped with two different states of the same quantum numbers.


Respuestas ◽  
2017 ◽  
Vol 22 (1) ◽  
pp. 37
Author(s):  
Yhon Edinson Estevez-Mendoza ◽  
Byron Medina-Delgado ◽  
Luis Leonardo Camargo-Ariza

Antecedentes: la información en un canal de fibra óptica sufre distorsiones debido a la aparición de efectos lineales y no lineales, restringiendo la velocidad de transmisión. En este documento se analiza el error no lineal denominado automodulación de fase (SPM),el cual genera un desfase en los pulsos trasmitidos, ocasionando errores de bits en la comunicación. Objetivo: el proyecto está orientado a evaluar el comportamiento del error no lineal SPM en una comunicación monocanal de fibra óptica utilizando Matlab. Métodos: su desarrollo parte del modelado matemático del error SPM, para ser codificado en Matlab y evaluar su desempeño en el canal para condiciones específicas. Para realizar las simulaciones se implementó un canal de comunicaciones en fibra óptica, teniendo en cuenta los parámetros que rigen las redes XGPON o 10GPON que son la siguiente generación de Red Óptica Pasiva con Capacidad de Gigabit (GPON). Para simular el canal de fibra óptica se definieron las distancias de 20, 40 y 60 km, y las potencias de 4, 10 y 20 mW, con velocidades de transmisión de 10 Gbps, en las longitudes de onda de 1550 y 1310 nm, usando la modulación QPSK. Los parámetros para desarrollar la simulación consideraron las recomendaciones de la Unión Internacional de Telecomunicaciones (ITU). Resultados: mediante un análisis gráfico se identificaron los parámetros que afectan el error SPM, como la potencia, el área efectiva, la distancia y el tipo de fibra, entre otros. Conclusión: el error SPM por sí solo no es perjudicial para las redes XGPON en la modulación QPSK, considerando que el máximo desfase obtenido en el proyecto fue  de 28.8°, siempre y cuando se tengan en cuenta la potencia, la distancia y los tipos de fibra, de acuerdo con las recomendaciones de la ITU (G652, G987, G691 y G957). Palabras clave: Automodulación de fase, fibra óptica monomodo estándar, modulación por desplazamiento cuaternario de fase, red óptica pasiva con capacidad de gigabit.AbstractBackground: the information transmitted by optical fiber channels is distorted due to the appearance of linear and nonlinear effects, which restrict the transmission rate, this paper  analyzes the nonlinear error selfphase modulation (SPM) Objective: the project aims to evaluate the behavior of nonlinear error SPM in a single channel fiber optic communication using Matlab. Methods: development of the mathematical modeling of error SPM to be coded in Matlab and evaluate their performance in the channel for specific conditions. To perform simulations a communications channel is implemented in fiber optics taking into account the parameters governing XGPON or 10GPON networks or which are the next generation of Gigabit Passive Optical Network (GPON). To perform simulations three distances 20, 40 and 60 km, and three power values of 4, 10 and 20 mW were defined, with transmission speeds of 10 Gbps wavelengths 1550 and 1310 nm, respectively; using QPSK modulation. The parameters to simulate were defined taking into account the recommendations of the International Telecommunication Union (ITU). Results: using a  graphical analysis we identified the parameters that affect the error SPM, such as potency, the effective area, the distance, the fiber type, among others. Conclusion: the error SPM alone is not harmful to the GPON networks in QPSK modulation, considering that the maximum phase shift obtained in the project was 28.8°, provided that the power, the distance and the types of fiber are taken into account according to the recommendations of the ITU (G652, G987, G691 y G957).Keywords: Gigabit passive optical network, quaternary phase shift keying, self phase modulation, standar singlemode fiber.


1955 ◽  
Vol 100 (3) ◽  
pp. 777-790 ◽  
Author(s):  
Harry Lustig ◽  
J. M. Blatt

2015 ◽  
Vol 36 (3) ◽  
Author(s):  
Nitu Syed ◽  
Mohammad Faisal

AbstractAdvanced modulation schemes, particularly the phase-modulated signals, have already drawn huge research interests for ultra-high speed long-haul lightwave transmission systems. We have considered 40 Gbit/s optical RZ pulse propagating in a periodically dispersion managed (DM) single channel system with negative residual dispersion. We investigate the effects of negative residual dispersion on intra-channel cross-phase modulation (IXPM)-induced phase shift. Analytical estimation for phase shift has been deduced using perturbed variational formulation. We therefore explore the impact of variation of various parameters such as transmission distance, duty cycle, bit rate, etc. on phase shift. The outcome of our work is to explore the performance of the dispersion compensated system with some negative residual dispersion so that the IXPM-induced phase shift remains low in optical fiber communication.


1973 ◽  
Vol 26 (1) ◽  
pp. 1
Author(s):  
WK Bertram ◽  
JL Cook

A method is given for solving the inverse reaction problem to obtain complex potentials as in the optical model of the nucleus. The method reproduces reaction data to the accuracy with which the reaction matrix can be least squares fitted to a sum of simple poles. The method couples multichannel phase shifts in such a way as to give the correct complex single-channel phase shift.


1973 ◽  
Vol 26 (4) ◽  
pp. 561
Author(s):  
JL Cook

It is shown that a method proposed for determining one single-channel potential from a real scattering phase shift using resonance parameters allows the determination of an energy-independent potential.


2015 ◽  
Vol 17 (4) ◽  
pp. 045022 ◽  
Author(s):  
Anne Crubellier ◽  
Rosario González-Férez ◽  
Christiane P Koch ◽  
Eliane Luc-Koenig

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