120967321
REPLY TO THE COMMENT ON "NONCOMMUTATIVITY AS A POSSIBLE ORIGIN OF THE ULTRAHIGH-ENERGY COSMIC RAY AND THE TEV PHOTON PARADOXES"
A cogitative comment on Ref. 1 was given by the author of Ref. 2 arguing that the Lorentz-noninvariant modification of the kinematic dispersion law does not follow from deformed oscillator systems, and it cannot evade ultrahigh energy threshold anomalies by raising the respective thresholds. It is pointed out that the dispersion relations of a q-deformed boson and fermion are derived heedlessly and further study on noncommutative theories is necessary. However if such dispersion relations are assumed tenable, the tachyonic propagation and photon instability do not exist at all because the deviation from 1 in q must be imaginary.
17776491
Noncommutativity as a possible origin of the ultrahigh energy cosmic ray and the TeV-photon paradoxes
In this paper, we present a general modified dispersion relation derived from q-deformed noncommutative theory and apply it to the ultrahigh energy cosmic ray and the TeV-photon paradoxes — threshold anomalies. Our purpose is not only trying to solve these puzzles by noncommutative theory but also to support noncommutative theory through the coincidence of the region in the parameter space for resolving the threshold anomalies with the one from the q-deformed noncommutative theory.
11090952
Cosmic ray threshold anomaly and kinematics in the dS spacetime
We present a covariant framework of kinematics in the dS spacetime, which is a natural postulate of recent astronomical observations ($\Lambda>0)$. One-particle states are presented explicitly. It is noticed that the dispersion relation of free particles is dependent on the degrees of freedom of angular momentum and spin. This fact can be referred to as the effects of the cosmological constant on kinematics of particles. The kinematics in dS spacetime is used to investigate the phenomenon of ultra high energy cosmic rays. We emphasize the possibility of solving the threshold anomalies of the interactions between ultra high energy cosmic rays and soft photons in the covariant framework of kinematics in the dS spacetime.
195378147
Effects of cosmological constant on motion of UHECR particles
Recent astronomical observations manifest that about two-thirds of the whole energy in the Universe is contributed by a small positive cosmological constant Λ (>0). Then, an asymptotically de Sitter spacetime is premised naturally. However, physics in the de Sitter spacetime is very different from that in the Minkowski spacetime. As the first step, a covariant formalism of the kinematics in the de Sitter spacetime is presented here. By solving exactly the equations of motion for a field, we obtain the dispersion relation of a free particle. It is noticed that the dispersion relation is dependent on the degree of freedom of angular momentum of the particle. We show the threshold anomaly of the ultra high energy cosmic ray disappears naturally in the framework of the de Sitter kinematics.
120446208
Construction and commissioning of the first wiggler at BEPC
Abstract The SRW1 at BEPC is under normal operation now. This article describes the construction and commissioning of the wiggler. Some experimental results are reported and suggestions for improvement are discussed.
14192602
Vacuum energy density and cosmological constant in dS brane-world
We discuss the vacuum energy density and the cosmological constant of dS5 brane-world with a dilaton field. It is shown that a stable AdS4 brane can be constructed and gravity localization can be realized. An explicit relation between the dS bulk cosmological constant and the brane cosmological constant is obtained. The discrete mass spectrum of the massive scalar field in the AdS4 brane is used to acquire the relationship between the brane cosmological constant and the vacuum energy density. The vacuum energy density in the brane gotten by this method is in agreement with astronomical observations.
119299977
Dynamical evolution of a scalar field coupling to Einstein’s tensor in the Reissner-Nordström black hole spacetime
We study the dynamical evolution of a scalar field coupling to Einstein's tensor in the background of a Reissner-Nordstrom black hole. Our results show that the coupling constant η imprints in the wave dynamics of a scalar perturbation. In the weak coupling, we find that with the increase of the coupling constant η the real parts of the fundamental quasinormal frequencies decrease and the absolute values of imaginary parts increase for fixed charge q and multipole number l. In the strong coupling, we find that for l ≠ 0 the instability occurs when η is larger than a certain threshold value η c which deceases with the multipole number l and charge q. However, for the lowest l = 0, we find that there does not exist such a threshold value and the scalar field always decays for arbitrary coupling constant.
117444261
The effect of high-order multipole imperfections on the LEP dynamic aperture
119215629
Strong gravitational lensing in a squashed Kaluza-Klein Gödel black hole
We investigate the strong gravitational lensing in a squashed Kaluza-Klein black hole immersed in the G\"{o}del universe with global rotation. Our result show that the strong gravitational lensing in the squashed Kaluza-Klein G\"{o}del black hole spacetime has some distinct behaviors from that in the Kerr case. In the squashed Kaluza-Klein G\"{o}del black hole spacetime, the photon sphere radius, the minimum impact parameter, the coefficient $\bar{a}$, $\bar{b}$ and the deflection angle $\alpha(\theta)$ in the $\phi$ direction are independent of whether the photon goes with or against the global rotation of the G\"{o}del Universe. While in the Kerr black hole, the values of these quantities for the prograde photons are different from those for the retrograde photons. Moreover, the coefficient of $\bar{b}$ increases with $j$ in the squashed Kaluza-Klein G\"{o}del black hole, but decreases with $a$ in the Kerr case. We also probe the influence of the squashed effect on the strong gravitational lensing in this black hole and find that in the extremely squashed case $\rho_0=0$, the coefficient $\bar{a}$ is a constant 1 and is independent of the global rotation of the G\"{o}del Universe. Furthermore, we assume that the gravitational field of the supermassive central object of the Galaxy can be described by this metric and estimate the numerical values of the coefficients and the main observables in the strong gravitational lensing.
119110851
THE PULSAR SEARCH COLLABORATORY: DISCOVERY AND TIMING OF FIVE NEW PULSARS
We present the discovery and timing solutions of five new pulsars by students involved in the Pulsar Search Collaboratory, a NSF-funded joint program between the National Radio Astronomy Observatory and West Virginia University designed to excite and engage high-school students in Science, Technology, Engineering, and Mathematics (STEM) and related fields. We encourage students to pursue STEM fields by apprenticing them within a professional scientific community doing cutting edge research, specifically by teaching them to search for pulsars. The students are analyzing 300?hr of drift-scan survey data taken with the Green Bank Telescope at 350?MHz. These data cover 2876?deg2 of the sky. Over the course of five years, more than 700 students have inspected diagnostic plots through a web-based graphical interface designed for this project. The five pulsars discovered in the data have spin periods ranging from 3.1?ms to 4.8?s. Among the new discoveries are PSR?J1926?1314, a long period, nulling pulsar; PSR?J1821+0155, an isolated, partially recycled 33?ms pulsar; and PSR?J1400?1438, a millisecond pulsar in a 9.5?day orbit whose companion is likely a white dwarf star.
118628016
Is the CMB asymmetry due to the kinematic dipole
Parity violation found in the Cosmic Microwave Background (CMB) radiation is a crucial clue for the non-standard cosmological model or the possible contamination of various foreground residuals and/or calibration of the CMB data sets. In this paper, we study the directional properties of the CMB parity asymmetry by excluding the $m=0$ modes in the definition of parity parameters. We find that the preferred directions of the parity parameters coincide with the CMB kinematic dipole, which implies that the CMB parity asymmetry may be connected with the possible contamination of the residual dipole component. We also find that such tendency is not only localized at $l=2,3$, but in the extended multipole ranges up to $l\sim 22$.