Photon and axion splitting in an inhomogeneous magnetic field

The axion–photon system in an external magnetic field, when the direction of propagation of axions and photons is orthogonal to the direction of the external magnetic field, displays a continuous axion–photon duality symmetry in the limit the axion mass is neglected. The conservation law that follow in this effective (2+1)$(2+1)$-dimensional theory from this symmetry is obtained. The magnetic field interaction is seen to be equivalent to first order to the interaction of a complex charged field with an external electric potential, where this fictitious “electric potential” is proportional to the external magnetic field. This allows one to solve for the scattering amplitudes using already known scalar QED results. From the scalar QED analog the axion and the photon are symmetric and antisymmetric combinations of particle and antiparticle. If one considers therefore scattering experiments in which the two spatial dimensions of the effective theory are involved nontrivially, one observes that both particle and antiparticle components of photons and axions are preferentially scattered in different directions, thus producing the splitting or decomposition of the photon and axion into their particle and antiparticle components in an inhomogeneous magnetic field. This observable in principle effect is of first order in the axion–photon coupling, unlike the “light shining through a wall phenomena”, which is second order.     

Chirality-dependent macroscopic force between chiral molecules and achiral matter

A non-zero macroscopic chirality-dependent force between achiral matter and homochiral molecules due to the exchange of light particles is shown theoretically. It has the opposite sign for molecules with opposite chirality. As an example, this force between a copper block and a vessel of chiral molecules (methyl phenyl carbinol nitrite) is calculated in the crystal field theory. The magnitude of the force is estimated with the published limits of scalar and pseudo-scalar coupling constants. Its possible influence to the gravitational experiments testing the equivalence principle is discussed as well.     

Gauge independence and chiral symmetry breaking in a strong magnetic field

The gauge independence of the dynamical fermion mass generated through chiral symmetry breaking in QED in a strong, constant external magnetic field is critically examined. We present a (first, to the best of our knowledge) consistent truncation of the Schwinger-Dyson equations in the lowest Landau level approximation. We demonstrate that the dynamical fermion mass, obtained as the solution of the truncated Schwinger-Dyson equations evaluated on the fermion mass shell, is manifestly gauge independent.     

Revisiting the QCD Corrections to the R-Parity Violating Processes pp/pp → eμ ＋ X

We present the theoretical predictions up to QCD next-to-leading order for the cross section of high-mass electron-muon pair production at the Tevatron and at the Large Hadron Collider （LHC）, considering only the dominant contributions from the third-generation sneutrino. The dependence of the renormalization and factorization scales on the total cross section, and the effects on the K-factor due to the uncertainty of parton distribution function are carefully investigated. By considering soft-gluon resummation effects to all orders in as of leading logarithm, we present the transverse momentum distributions of the final eμ pair.     

Axion electrodynamics in a waveguide

The interaction of axion and electromagnetic waves is studied in the presence of a magnetic field threading a waveguide. This interaction, which vanishes in free space, is found to induce transverse magnetic waves with frequency spectra associated with transverse electric waves in the absence of the axion.     

Impact of spin-zero particle-photon interactions on light polarization in external magnetic fields

If the recent PVLAS results on polarization changes of a linearly polarized laser beam passing through a magnetic field are interpreted by an axion-like particle, it is almost certain that it is not a standard QCD axion. Considering this, we study the general effective interactions of photons with spin-zero particles without restricting the latter to be a pseudo-scalar or a scalar, i.e., a parity eigenstate. At the lowest order in effective field theory, there are two dimension-5 interactions, each of which has previously been treated separately for a pseudo-scalar or a scalar particle. By following the evolution in an external magnetic field of the system of spin-zero particles and photons, we compute the changes in light polarization and the transition probability for two experimental set-ups: one-way propagation and round-trip propagation. While the first may be relevant for astrophysical sources of spin-zero particles, the second applies to laboratory optical experiments like PVLAS. In the one-way propagation, interesting phenomena can occur for special configurations of polarization where, for instance, transition occurs but light polarization does not change. For the round-trip propagation, however, the standard results of polarization changes for a pseudoscalar or a scalar are only modified by a factor that depends on the relative strength of the two interactions.     

Lifshitz-like argument for low-lying states in a strong magnetic field

Localization of an electron moving in two dimensions, submitted to a strong magnetic field and scattered by randomly distributed zero-range impurities is investigated. Considering the explicit expression for the density of states obtained by Brézin, Gross and Itzykson, the Lifshitz argument is adapted in order to analyze the unusual power-law behavior of the low energy spectrum. When the impurity density is smaller than the Landau degeneracy, typical configurations of disorder responsible for low energy states are identified as cluster of impurities of well defined form. This allows for an interpretation of low-lying states, localized around these clusters, whose size diverges logarithmically as the energy goes to zero. Received 5 January 2000     

Off-shell photon light-cone wave functions with odd chirality

Based on a more reasonable simulation method for dealing with the Λ-parameter characterizing the pole form for the form factor (the Fourier transform of the instanton zero mode), and a unified way for regularizing the integrals appearing in the expressions of the light-cone photon wave functions, the transverse photon wave function (u, P ²) at the leading twist with the on-shell or off-shell momentum have been re-examined in the effective low-energy theory derived from the instanton vacuum, and the twist-two parts of the other two photon wave functions, h ^{(s), twisttwo} _{γ ||} (u, P ²) and h ^{(t), twisttwo} _{γ ||} (u, P ²), with odd chirality are calculated based on the Wandzura-Wilczek-like relations as well. A brief discussion of the dependence of the coupling f _γ ^⊥(P ²) and the light-cone photon wave functions with respect to P² and the end-point behavior of the photon wave functions are given.     

Axion as a cold dark matter candidate

Here we generally prove that the axion as a coherently oscillating scalar field acts as a cold dark matter in nearly all cosmologically relevant scales. The proof is made in the linear perturbation order. Compared with our previous proof based on solutions, here we compare the equations in the axion with the ones in the cold dark matter, thus expanding the valid range of the proof. Deviation from purely pressureless medium appears in very small scale where axion reveals a peculiar equation of state. Our analysis is made in the presence of the cosmological constant, and our conclusions are valid in the presence of other fluid and field components.     

Charged Top-Pion Production Associated with a Gluon Jet at the LHC

The charged top-pions have been predicted by the topcolour-assisted technicolour （TC2） model and the observation of the charged top-pions can be regarded as the robust evidence of the model. We study the charged top-pion and gluon associated production at the LHC, i.e., pp → gIIe^＋. The cross section of this process can reach tens of pb, even hundreds ofpb, and there will be enough gIIt^＋ events produced at the LHC. Because the gIIt^＋ production is a flavour-changing （FC） process, the SM background can be greatly depressed. Furthermore, there exists an FC decay mode cb for the charged top-pions, and such decay mode can provide us with the typical signals to detect the charged top-pions. Therefore, it is hopeful to find the charged top-pions via the gIIe^＋ production at the LHC.     

Sodium in a strong magnetic field

We investigate the effects of a magnetic field with low to intermediate strength on several spectroscopic properties of the sodium atom. A model potential is used to describe the core of sodium, reducing the study of the system to an effective one-particle problem. All states with principal quantum numbers n = 3, 4, 5, 6 and 7 are studied and analysed. A grid of twenty values for the field strength in the complete regime B = 0 - 0.02 a.u. is employed. Ionisation energies, transition wavelengths and their dipole oscillator strengths are presented. Received 5 November 2002 Published online 4 February 2003     

Resonant axion generation in a strong magnetic field as a mechanism of forming a cold latent mass

It is demonstrated that considering vacuum polarization in superstrong magnetic field B ≫B₀ = m² / e = 4.41∙10¹³ G leads to giant (by 13 orders of magnitude) intensification of axion generation processes. In this case, for example, the probability of resonant axion radiation is about 10^-12 (B / B₀ ) of the probability of photon radiation, which is by many orders of magnitude greater than usually. In this regard, it is assumed that this mechanism plays the main role in the formation of an axion component of cold latent mass in the Universe.     

Relativistic analysis of magnetoelectric crystals: Extracting a new 4-dimensional P odd and T odd pseudoscalar from Cr2O3 data

Earlier, the linear magnetoelectric effect of chromium sesquioxide Cr₂O₃ has been determined experimentally as a function of temperature. One measures the electric field-induced magnetization on Cr₂O₃ crystals or the magnetic field-induced polarization. From the magnetoelectric moduli of Cr₂O₃ we extract a 4-dimensional relativistic invariant pseudoscalar . It is temperature dependent and of the order of ∼¹⁰⁻⁴Y₀, with Y₀ as vacuum admittance. We show that the new pseudoscalar is odd under parity transformation and odd under time inversion. Moreover, is for Cr₂O₃ what Tellegen's gyrator is for two port theory, the axion field for axion electrodynamics, and the PEMC (perfect electromagnetic conductor) for electrical engineering.     

Instability in magnetic materials with a dynamical axion field

It has been pointed out that axion electrodynamics exhibits instability in the presence of a background electric field. We show that the instability leads to a complete screening of an applied electric field above a certain critical value and the excess energy is converted into a magnetic field. We clarify the physical origin of the screening effect and discuss its possible experimental realization in magnetic materials where magnetic fluctuations play the role of the dynamical axion field.     

Theoretical Study of Quantum Bit Rate in Free-Space Quantum Cryptography

The quantum bit rate is an important operating parameter in free-space quantum key distribution. We introduce the measuring factor and the sifting factor, and present the expressions of the quantum bit rate based on the ideal single-photon sources and the single-photon sources with Poisson distribution. The quantum bit rate is studied in the numerical simulation for the laser links between a ground station and a satellite in a low earth orbit. The results show that it is feasible to implement quantum key distribution between a ground station and a satellite in a low earth orbit.     

A massive photon in a strong magnetic field: Generation and decay channels

The conditions for the formation of an effective photon mass in a strong magnetic field are considered. It is shown that massless photons are sterile. The channels γ* → e⁺e⁻ and γ* → v_iv_i for the decay of a massive photon and their possible contribution to the mechanism of energy losses by collapsing astrophysical objects are discussed. Moscow State Industrial University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 35–39, February, 1997.     

Gap generation for Dirac fermions on Lobachevsky plane in a magnetic field

We study symmetry breaking and gap generation for fermions in the 2D space of constant negative curvature (the Lobachevsky plane) in an external covariantly constant magnetic field in a four-fermion model. It is shown that due to the magnetic and negative curvature catalyses phenomena the critical coupling constant is zero and there is a symmetry breaking condensate in the chiral limit even in free theory. We analyze solutions of the gap equation in the cases of zero, weak, and strong magnetic fields. As a byproduct, we calculate the density of states and the Hall conductivity for noninteracting fermions that may be relevant for studies of graphene.     

Axion-like particles,cosmic magnetic fields and gamma-ray astrophysics

Axion-like particles (ALPs) are predicted by many extensions of the Standard Model and give rise to characteristic dimming and polarization effects in a light beam travelling in a magnetic field. In this Letter, we demonstrate that photon-ALP mixing in cosmic magnetic fields produces an observable distortion in the energy spectra of distant gamma-ray sources (like AGN) for ranges of the ALP parameters allowed by all available constraints. The resulting effect is expected to show up in the energy band 100 MeV–100 GeV, and so it can be searched with the upcoming GLAST mission.