• Issue front cover thumbnail

      Volume 80, Issue 3

      March 2013,   pages  369-557

    • The Standard Model with one universal extra dimension

      A Cordero-Cid M Gómez-Bock H Novales-Sánchez J J Toscano

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      Effects of universal extra dimensions on Standard Model observables first arise at the one-loop level. The quantization of this class of theories is therefore essential in order to perform predictions. A comprehensive study of the $SU_{C}(3) \times SU_{L}(2) \times U_{Y}(1)$ Standard Model defined in a space-time manifold with one universal extra dimension, compactified on the oribifold $S^{1}/Z_{2}$, is presented. The fact that the four-dimensional Kaluza–Klein theory is subjected to two types of gauge transformations is stressed and its quantization under the basis of the BRST symmetry discussed. $A SU_{C}(3) \times SU_{L}(2) \times U_{Y}(1)$-covariant gauge-fixing procedure for the Kaluza–Klein excitations is introduced. The connection between gauge and mass eigenstate fields is established in an exact way. An exhaustive list of the explicit expressions for all physical couplings induced by the Yang–Mills, Currents, Higgs, and Yukawa sectors is presented. The one-loop renormalizability of the standard Green’s functions, which implies that the Standard Model observables do not depend on a cut-off scale, is stressed.

    • Solutions and conservation laws of Benjamin–Bona–Mahony–Peregrine equation with power-law and dual power-law nonlinearities

      Chaudry Masood Khalique

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      In this paper, exact solutions of Benjamin–Bona–Mahony–Peregrine equation are obtained with power-law and dual power-law nonlinearities. The Lie group analysis as well as the simplest equation method are used to carry out the integration of these equations. The solutions obtained are cnoidal waves, periodic solutions and soliton solutions. Subsequently, the conservation laws are derived for the underlying equations.

    • Is quantum theory compatible with special relativity?

      M Bahrami A Shafiee M Saravani M Golshani

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      How a proposed quantum nonlocal phenomenon could be incompatible with the requirements of special relativity is studied. To show this, the least set of assumptions about the formalism and the interpretation of non-relativistic quantum theory is considered. Then, without any reference to the collapse assumption or any other stochastic processes, an experiment is proposed, involving two quantum systems, that interacted at an arbitrary time, with results which seem to be in conflict with requirements of special relativity.

    • Spherically symmetric scalar field collapse

      Koyel Ganguly Narayan Banerjee

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      It is shown that a scalar field, minimally coupled to gravity, may have collapsing modes even when the energy condition is violated, that is, for $(𝜌 + 3p) < 0$. This result may be useful in the investigation of the possible clustering of dark energy. All the examples dealt with have apparent horizons formed before the formation of singularity. The singularities formed are shell focussing in nature. The density of the scalar field distribution is seen to diverge at singularity. The Ricci scalar also diverges at the singularity. The interior spherically symmetric metric is matched with exterior Vaidya metric at the hypersurface and the appropriate junction conditions are obtained.

    • Q-S synchronization of the fractional-order unified system

      Yi Chai Liping Chen Rancho Wu Juan Dai

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      Concept of Q-S synchronization for fractional-order systems is introduced and Q-S synchronization of the fractional-order unified system is investigated in this paper. On the basis of the stability theory of the fractional-order system, two suitable control schemes are designed to achieve Q-S synchronization of the fractional-order unified systems under the given observable variables of drive system and the response system. Theoretical analysis and numerical simulations are shown to demonstrate the validity and feasibility of the proposed method.

    • Peakons and compactons on the background of periodic wave

      Chao-Qing Dai Cui-Yun Liu

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      In this paper, the extended tanh-function method (ETM) based on the mapping equation is further improved by generalizing the Riccati equation. The new variable separation solutions of the (2+1)-dimensional Broer–Kaup–Kupershmidt (BKK) system are derived. From the periodic wave solution and by selecting appropriate functions, the evolutional behaviours of peakons and compactons on the background of Jacobian elliptic wave are investigated.

    • Double compactons in the Olver–Rosenau equation

      Aiyong Chen Shuangquan Wen

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      It is showed that the fully nonlinear evolution equations of Olver and Rosenau can be reduced to Hamiltonian form by transformation of variables. The resulting Hamiltonian equations are treated by the dynamical systems theory and a phase-space analysis of their singular points is presented. The results of this study demonstrate that the equations can support double compactons. The new Olver–Rosenau compactons are different from the well-known Rosenau–Hyman compacton and Cooper–Shepard–Sodano compacton, because they are induced by a singular elliptic instead of singular straight line on phase-space.

    • Mass shift of 𝜎-meson in nuclear matter

      J R Morones-Ibarra Mónica Menchaca Maciel Ayax Santos-Guevara Felipe Robledo Padilla

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      The propagation of 𝜎-meson in nuclear matter is studied in the Walecka model, by assuming that the sigma couples to a pair of nucleon–antinucleon states and to particle–hole states. The in-medium effect of $\sigma -\omega$ mixing is also studied. For completeness, the coupling of sigma to two virtual pions was also considered. It is found that the 𝜎-meson mass decreases with respect to its value in vacuum and that the contribution of the $\sigma -\omega$ mixing effect on the mass shift is relatively small.

    • Analysis of thermal distribution in two end pumping Nd:YAG laser rod using bacterial foraging optimization algorithm

      Mohammed A Minshed

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      There is a strong need for the optimized management of the thermal problem in Nd:YAG laser rod and for a powerful, fast, and accurate modelling tool capable of treating the heat source distribution very close to what it actually is. In this paper, a new optimization algorithm called bacterial foraging optimization algorithm (BFOA) is proposed for simulation of the radial heat distribution. A BFOA discloses a simulation method which delivers the exact temperature distribution in a circularly cylindrical structure with a circularly symmetrical, longitudinally, and transversally non-uniform heat source distribution and circularly symmetrical cooling means. The output power is obtained and compared with previously published experimental measurements for different pump power and a good agreement has been found.

    • Generation of uniform atmospheric pressure argon glow plasma by dielectric barrier discharge

      Raju Bhai Tyata Deepak Prasad Subedi Rajendra Shrestha Chiow San Wong

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      In this paper, atmospheric pressure glow discharges (APGD) in argon generated in parallel plate dielectric barrier discharge system is investigated by means of electrical and optical measurements. Using a high voltage (0–20 kV) power supply operating at 10–30 kHz, homogeneous and steady APGD has been observed between the electrodes with gap spacing from 0.5 mm to 2 mm and with a dielectric barrier of thickness 2 mm while argon gas is fed at a controlled flow rate of 11/min. The electron temperature and electron density of the plasma are determined by means of optical emission spectroscopy. Our results show that the electron density of the discharge obtained is of the order of 1016 cm-3 while the electron temperature is estimated to be 0.65 eV. The important result is that electron density determined from the line intensity ratio method and stark broadening method are in very good agreement. The Lissajous figure is used to estimate the energy deposited to the glow discharge. It is found that the energy deposited to the discharge is in the range of 20 to 25 $\\mu$J with a discharge voltage of 1.85 kV. The energy deposited to the discharge is observed to be higher at smaller gas spacing. The glow discharge plasma is tested to be effective in reducing the hydrophobicity of polyethylene film significantly.

    • Head-on collision of dust-ion-acoustic solitons in electron-dust-ion quantum plasmas

      Prasanta Chatterjee Malay Kumar Ghorui Rajkumar Roychoudhury

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      In this paper, we study the head-on collision between two dust-ion-acoustic (DIA) solitons in quantum electron-dust-ion plasma. Using the extended Poincaré–Lighthill–Kuo (PLK) method, we obtain the Korteweg–de Vries (KdV) equations, the phase shifts and the trajectories after the head-on collision of the two DIA solitons. We investigate the effect of quantum diffraction parameters for electrons and ions $(H_{e}, H_{i})$, the Fermi temperature ratio $(\sigma)$ and the dust charged number density $(n_{\text{d0}})$ on the phase shifts. Different values of $\mu = z_{\text{d0}}(n_{\text{d0}}/n_{\text{i0}})$ and $\mu_{\text{d}} = z_{\text{d0}}(m_{\text{i}}/m_{\text{d}})$ are taken to discuss the effects on phase shifts, where $z_{\text{d0}}$ denotes the dust charge number, $n_{\text{j0}}$represents the equilibrium number density and $m_{j}$ is the mass of the jth species ($j = e, i , d$ for electrons, ions and dust particles, respectively). It is observed that the phase shifts are significantly affected by the plasma parameters.

    • On the sharp front-type solution of the Nagumo equation with nonlinear diffusion and convection

      M B A Mansour

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      This paper is concerned with the Nagumo equation with nonlinear degenerate diffusion and convection which arises in several problems of population dynamics, chemical reactions and others. A sharp front-type solution with a minimum speed to this model equation is analysed using different methods. One of the methods is to solve the travelling wave equations and compute an exact solution which describes the sharp travelling wavefront. The second method is to solve numerically an initial-moving boundary-value problem for the partial differential equation and obtain an approximation for this sharp front-type solution.

    • Real gauge singlet scalar extension of the Standard Model: A possible candidate for cold dark matter

      Anirban Biswas Debasish Majumdar

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      The simplest extension of Standard Model (SM) is considered in which a real SM gauge singlet scalar with an additional discrete symmetry $Z_{2}$ is introduced to SM. This additional scalar can be a viable candidate of cold dark matter (CDM) since the stability of 𝑆 is achieved by the application of $Z_{2}$ symmetry on 𝑆. Considering 𝑆 as a possible candidate of CDM, Boltzmann’s equation is solved to find the freeze-out temperature and relic density of 𝑆 for Higgs mass 120 GeV in the scalar mass range 5 GeV to 1 TeV. As HHSS coupling $\delta_{2}$ appearing in Lagrangian depends upon the value of scalar mass $m_{S}$ and Higgs mass $m_{h}$, the $m_{S} − \delta_{2}$ parameter space has been constrained by using the Wilkinson microwave anisotropy probe (WMAP) limit on the relic density of DM in the Universe and the results of recent ongoing DM direct search experiments, namely CDMS-II, CoGeNT, DAMA, EDELWEISS-II, XENON-10 and XENON-100. From such analyses, two distinct mass regions are found (a lower and higher mass domain) for such a DM candidate that satisfy both the WMAP limit and the experimental results considered here. The possible differential direct detection rates and annual variation of total detection rates have been estimated for this scalar DM candidate 𝑆 for two detector materials, namely Ge and Xe. Finally, the 𝛾-ray flux has been calculated from the galactic centre due to annihilation of two 130 GeV scalar DM into two monoenergetic 𝛾-rays.

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