"The European Physical Journal C"

Deriglazov, Alexei A.;Pupasov-Maksimov, Andrey M.

doi: 10.1140/epjc/s10052-014-3101-2pmid: N/A

Abstract We construct a relativistic spinning-particle Lagrangian where spin is considered as a composite quantity constructed on the base of a non-Grassmann vector-like variable. The variational problem guarantees both a fixed value of the spin and the Frenkel condition on the spin-tensor. The Frenkel condition inevitably leads to relativistic corrections of the Poisson algebra of the position variables: their classical brackets became noncommutative. We construct the relativistic quantum mechanics in the canonical formalism (in the physical-time parametrization) and in the covariant formalism (in an arbitrary parametrization). We show how state vectors and operators of the covariant formulation can be used to compute the mean values of physical operators in the canonical formalism, thus proving its relativistic covariance. We establish relations between the Frenkel electron and positive-energy sector of the Dirac equation. Various candidates for the position and spin operators of an electron acquire clear meaning and interpretation in the Lagrangian model of the Frenkel electron. Our results argue in favor of Pryce’s (d)-type operators as the spin and position operators of Dirac theory. This implies that the effects of non-commutativity could be expected already at the Compton wavelength. We also present the manifestly covariant form of the spin and position operators of the Dirac equation. A preprint version of the article is available at ArXiv.

Yu, H.;Wang, F. Y.

doi: 10.1140/epjc/s10052-014-3090-1pmid: N/A

Abstract Many dark energy models fail to pass the cosmic age test. In this paper, we investigate the cosmic age problem associated with nine extremely old Global Clusters (GCs) and the old quasar APM 08279+5255 in the \(R_\mathrm{h}=ct\) universe. The age data of these oldest GCs in M31 are acquired from the Beijing–Arizona–Taiwan–Connecticut system with up-to-date theoretical synthesis models. They have not been used to test the cosmic age problem in the \(R_\mathrm{h}=ct\) universe in previous literature. By evaluating the age of the \(R_\mathrm{h}=ct\) universe with the observational constraints from the type Ia supernovae and the Hubble parameter, we find that the \(R_\mathrm{h}=ct\) universe can accommodate five GCs and the quasar APM 08279+5255 at redshift \(z=3.91\). But for other models, such as \(\Lambda \)CDM, the interacting dark energy model, the generalized Chaplygin gas model, and holographic dark energy model, cannot accommodate all GCs and the quasar APM 08279+5255. It is worthwhile to note that the age estimates of some GCs are controversial. So, unlike other cosmological models, the \(R_\mathrm{h}=ct\) universe can marginally solve the cosmic age problem, especially at high redshift. A preprint version of the article is available at ArXiv.

Banerjee, Aritra;Biswas, Sagar;Panigrahi, Kamal L.

doi: 10.1140/epjc/s10052-014-3115-9pmid: N/A

Abstract Puff field theory (PFT) is an example of a non-local field theory which arises from a novel embedding of D-branes in a Melvin universe. We study several rotating and pulsating string solutions of the F-string equations of motion in the supergravity dual of the PFT. Further, we find a PP-wave geometry from this non-local spacetime by applying a Penrose limit and comment on its similarity with the maximally supersymmetric PP-wave background. A preprint version of the article is available at ArXiv.

Azizi, K. ;Sarac, Y.;Sundu, H.

doi: 10.1140/epjc/s10052-014-3106-xpmid: N/A

Abstract The strong \(D_{2}^{*}(2460)^{0}\rightarrow D^+ \pi ^- \) and \(D_{s2}^{*}(2573)^{+}\rightarrow D^{+} K^{0}\) transitions are analyzed via three-point QCD sum rules. First we calculate the corresponding strong coupling constants \(g_{D_2^*D\pi }\) and \(g_{D_{s2}^*DK}\). Then we use them to calculate the corresponding decay widths and branching ratios. Making use of the existing experimental data on the ratio of the decay width in the pseudoscalar \(D\) channel to that of the vector \(D^*\) channel, finally, we estimate the decay width and branching ratio of the strong \(D_2^*(2460)^0 \rightarrow D^*(2010)^+\pi ^-\) transition. A preprint version of the article is available at ArXiv.

Yan, H.;Sun, G. A.;Gong, J.;Pang, B. B.;Wang, Y.;Yang, Y. W.;Zhang, J.;Zhang, Y.

doi: 10.1140/epjc/s10052-014-3088-8pmid: N/A

Abstract Experiments using polarized \(^{3}\)He atom beams to search for short range spin dependent forces are proposed. High intensity, high polarization, small beam size \(^{3}\)He atom beams have been successfully produced and used in surface science researches. By incorporating background reduction designs as combination shielding by \(\upmu \)-metal and superconductor and double beam paths, the precision of spin rotation angle per unit length could be improved by a factor of \(\sim \!10^{4}\). By this precision, in combination with a high density and low magnetic susceptibility sample source mass, and reversing one beam path if necessary, sensitivities on three different types of spin dependent interactions could be improved by as much as \(\sim \!\!10^{2}\) to \(\sim \!\!10^{8}\) over the current experiments at the millimeter range. A preprint version of the article is available at ArXiv.

Hatefi, Ehsan

doi: 10.1140/epjc/s10052-014-3116-8pmid: N/A

Abstract We obtain the closed form of the correlation function of one current and four spin operators (with different chiralities) in type IIA superstring theory. The complete form of the S-matrix of one gauge, two fermions (with different chiralities) and one closed string Ramond–Ramond for all order \(\alpha '\) type IIA has been explored. Moreover, we make use of a different gauge fixing to be able to find all the closed forms of \(\langle V_{C} V_{A}V_{{\bar{\psi }}}V_{\psi }\rangle \) correlators. An infinite number of \(t,s\)-channel fermion poles of this S-matrix in the field theory of IIA is generated. Unlike the closed form of the correlators of the same amplitude of IIB, for various \(p,n\) cases in type IIA we do have different double poles in \(t,(t+s+u)\) and in \(s,(t+s+u)\) channels and we produced them. We also find new Wess–Zumino couplings of IIA with their third order \(\alpha ' \) corrections as well as a new form of higher derivative corrections (with different coefficient from its IIB one) to SYM couplings at third order of \(\alpha ' \). Using them, we are able to produce a \((t+s+u)\) channel scalar pole of the \(\langle V_{C} V_{A}V_{{\bar{\psi }}}V_{\psi }\rangle \) amplitude for the \(p+2=n\) case. Finally we make some comments on \(\alpha '\) corrections to IIA superstring theory. A preprint version of the article is available at ArXiv.

Kaparulin, D. S.;Lyakhovich, S. L.;Sharapov, A. A.

doi: 10.1140/epjc/s10052-014-3072-3pmid: N/A

Abstract We observe that a wide class of higher-derivative systems admits a bounded integral of motion that ensures the classical stability of dynamics, while the canonical energy is unbounded. We use the concept of a Lagrange anchor to demonstrate that the bounded integral of motion is connected with the time-translation invariance. A procedure is suggested for switching on interactions in free higher-derivative systems without breaking their stability. We also demonstrate the quantization technique that keeps the higher-derivative dynamics stable at quantum level. The general construction is illustrated by the examples of the Pais–Uhlenbeck oscillator, higher-derivative scalar field model, and the Podolsky electrodynamics. For all these models, the positive integrals of motion are explicitly constructed and the interactions are included such that they keep the system stable. A preprint version of the article is available at ArXiv.

Mohammadi, Rohollah

doi: 10.1140/epjc/s10052-014-3102-1pmid: N/A

Abstract The primordial anisotropies of the cosmic microwave background are linearly polarized via Compton-scattering. On the other hand, a primordial degree of circular polarization of the Cosmic Microwave Background is not observationally excluded. In this work, we discuss the generation of the circular polarization of CMB via their scattering on the cosmic neutrino background since the epoch of recombination. We show that the photon–neutrino interaction can transform plane polarization into circular polarization through processes \(\gamma +\nu \rightarrow \gamma +\nu \) and the Stokes-\(V\) parameter of CMB has a linear dependence on the wavelength and square dependence on the average bulk velocity of the cosmic neutrino background and also the maximum value of \(C^V\) is estimated in range of a few nK square. A preprint version of the article is available at ArXiv.

Suzuki, Atsuto

doi: 10.1140/epjc/s10052-014-3094-xpmid: N/A

Abstract The primary goal of KamLAND is a search for the oscillation of \({\bar{\nu }}_\mathrm{e}\)’s emitted from distant power reactors. The long baseline, typically 180 km, enables KamLAND to address the oscillation solution of the “solar neutrino problem” with \({\bar{\nu }}_{e} \)’s under laboratory conditions. KamLAND found fewer reactor \({\bar{\nu }}_{e} \) events than expected from standard assumptions about \(\overline{\nu }_e\) propagation at more than 9\(\sigma \) confidence level (C.L.). The observed energy spectrum disagrees with the expected spectral shape at more than 5\(\sigma \) C.L., and prefers the distortion from neutrino oscillation effects. A three-flavor oscillation analysis of the data from KamLAND and KamLAND + solar neutrino experiments with CPT invariance, yields \(\Delta m_{21}^2 \)= [\(7.54_{-0.18}^{+0.19} \times \)10\(^{-5}\) eV\(^{2}\), \(7.53_{-0.18}^{+0.19} \times \)10\(^{-5}\) eV\(^{2}\)], tan\(^{2}\theta _{12}\) = [\(0.481_{-0.080}^{+0.092} \), \(0.437_{-0.026}^{+0.029} \)], and sin\(^{2}\theta _{13}\) = [\(0.010_{-0.034}^{+0.033} \), \(0.023_{-0.015}^{+0.015} \)]. All solutions to the solar neutrino problem except for the large mixing angle region are excluded. KamLAND also demonstrated almost two cycles of the periodic feature expected from neutrino oscillation effects. KamLAND performed the first experimental study of antineutrinos from the Earth’s interior so-called geoneutrinos (geo \({\bar{\nu }}_{e} \)’s), and succeeded in detecting geo \({\bar{\nu }}_{e} \)’s produced by the decays of \(^{238}\)U and \(^{232}\)Th within the Earth. Assuming a chondritic Th/U mass ratio, we obtain \(116_{-27}^{+28} {\bar{\nu }}_{e}\) events from \(^{238}\)U and \(^{232}\)Th, corresponding a geo \({\bar{\nu }}_{e}\) flux of \(3.4_{-0.8}^{+0.8}\times \) 10\(^{6}\) cm\(^{-2}\) s\(^{-1}\) at the KamLAND location. We evaluate various bulk silicate Earth composition models using the observed geo \({\bar{\nu }}_{e} \) rate. A preprint version of the article is available at ArXiv.

Nashed, G. G. L.;Hanafy, W. El

doi: 10.1140/epjc/s10052-014-3099-5pmid: N/A

Abstract In the present work we derive an exact solution of an isotropic and homogeneous Universe governed by \(f(T)\) gravity. We show how the torsion contribution to the FRW cosmology can provide a unique origin for both early and late acceleration phases of the Universe. The three models (\(k=0, \pm 1\)) show a built-in inflationary behavior at some early Universe time; they restore suitable conditions for the hot Big bang nucleosynthesis to begin. Unlike the standard cosmology, we show that even if the Universe initially started with positive or negative sectional curvatures, the curvature density parameter enforces evolution to a flat Universe. The solution constrains the torsion scalar \(T\) to be a constant function at all time \(t\), for the three models. This eliminates the need for dark energy (DE). Moreover, when the continuity equation is assumed for the torsion fluid, we show that the flat and closed Universe models violate the conservation principle, while the open one does not. The evolution of the effective equation of state (EoS) of the torsion fluid implies a peculiar trace from a quintessence-like DE to a phantom-like one crossing a matter and radiation EoS in between; then it asymptotically approaches a de Sitter fate. A preprint version of the article is available at ArXiv.