Quantum counterfactuality with identical particles

Quantum self-interference enables the counterfactual transmission of information, whereby the transmitted bits involve no particles traveling through the channel. In this work, we show how counterfactuality can be realized even when the self-interference is replaced by interference between identical particles. Interestingly, the facet of indistinguishability called forth here is associated with first-order coherence, and is different from the usual notion of indistinguishability associated with ...     

Kähler spinning particles

We construct the U(N) spinning particle theories, which describe particles moving on Kähler spaces. These particles have the same relation to the N = 2 string as usual spinning particles have to the NSR string. We find the restrictions on the target space of the theories coming from supersymmetry and from global anomalies. Finally, we show that the partition functions of the theories agree with what is expected from their spectra, unlike that of the N = 2 string in which there is an anomalous dependence on the proper time.     

Do supermembranes contain massless particles?

We compute the Casimir energy of an 11-dimensional Green-Schwarz supermembrane, generalizing the calculations of Kikkawa and Yamasaki for the bosonic membrane. We find a nonvanishing result. Assuming a simple relation between angular momentum and energy similar to that of the bosonic membrane, we conclude that such supermembranes do not contain massless particles.     

Charged particles in ℤ2 gauge theories

In the free charge phase of the ₂ gauge-Higgs model on a lattice charged particles are shown to exist.Supported by DAADHeisenberg fellow     

Bell’s inequality with Dirac particles

We study Bell’s inequality using the Bell states constructed from four component Dirac spinors. Spin operator is related to the Pauli-Lubanski pseudo vector which is relativistic invariant operator. By using Lorentz transformation, in both Bell states and spin operator, we obtain an observer independent Bell’s inequality, so that it is maximally violated as long as it is violated maximally in the rest frame. The article is published in the original.     

Why have supersymmetric particles not been observed?

If low-energy supersymmetry is the solution to the hierarchy problem, it is a puzzle why supersymmetric particles have not been observed experimentally to date. We show that supersymmetric particles in the TeV region can be explained if the fundamental cut-off scale of the theory is smaller than the 4-dimensional Planck scale and if thermal leptogenesis is the source of the observed baryon asymmetry. The supersymmetric particles such as sfermions and gauginos are predicted to be in the TeV region, while the gravitino is the LSP with mass of O(100) GeV$O(100)\text{GeV}$ and is a good candidate for dark matter. Interestingly, the cosmological moduli problem can be solved in the theory with the low cut-off scale.     

Chern–Simons particles with nonstandard gravitational interaction

The model of nonrelativistic particles coupled to nonstandard (2+1)-gravity is extended to include Abelian or non-Abelian charges coupled to Chern–Simons gauge fields. Equivalently, the model may be viewed as describing the (Abelian or non-Abelian) anyonic dynamics of Chern–Simons particles coupled, in a reparameterization invariant way, to a translational Chern–Simons action. The quantum 2-body problem is described by a nonstandard Schr?dinger equation with a noninteger angular momentum depending on energy as well as particle charges. Some numerical results describing the modification of the energy levels by these charges in the confined regime are presented. The modification involves a shift as well as splitting of the levels. Received: 16 March 2001 / Published online: 13 June 2001     

Magnetic properties of 2 nm α-Fe particles

Ultrafine metallic iron particles with a mean diameter of 2 nm have been prepared on a carbon support and were studied by in situ Mössbauer spectroscopy. It is found that even in these extremely small particles, containing on the average about 350 atoms, most of the atoms are in environments which are quite similar to those of iron atoms in bulk -Fe. The surface hyperfine field is larger than the bulk value at 5 K, but decreases rapidly with increasing temperature. The magnetic energy constant was found to beK (3.0±1.0)×10⁵ J m^–3.     

Charged particles bunch–accelerator extraction window matching

The criterion for matching the charged particle bunch with the accelerator beam extraction window, which consists in minimizing the emittance of the accelerated beam extracted through a metal foil, is derived using the distribution function for moving particles scattered on foil nuclei. A technique for constructing the phase portrait of the scattered bunch and the criterion for minimizing its area (emittance) are presented. The formula relating the emittances of incident and scattered bunches and the ellipse equation describing the phase portrait of the matched bunch are derived.     

The neutrinos,massive or massless particles?

Neutrino properties, and specially their masses, are a central problem for the grand-unified theories of particle physics and for cosmology (structure formation and dark matter). After an historical introduction, we review the main experimental efforts on the ν mass determination: direct measurements, search for neutrinoless double β decays, and finally the search for neutrino flavor oscillations, for which some evidences already exist.     

Modelling čerenkov radiation of relativistic particles in crystals

From the aspects of classical mechanics and electrodynamics, an analysis has been performed of the possible influence of the kind of charged particle trajectory on the erenkov radiation spectrum in a crystal. Results of the analytical computation are compared with the data of a computer experiment. It is shown that the influence of the particle trajectory on the erenkov radiation spectrum is insignificant in the optical frequency band. The expected effect is possible when utilizing crystals with a superlattice and by observation of radiation in the xray frequency range.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 62–67, February, 1988.The authors are grateful to S. A. Vorob'ev for supporting the research and to Yu. L. Pivovarov for stimulating and useful discussions.     

Acceleration of particles by nonrotating charged black holes?

Recently, in the series of works a new effect of acceleration of particles by black holes has been found. Under certain conditions, the energy in the center-of-mass system can become infinitely large. The essential ingredient of such effect is the rotation of a black hole. In this work, it has been argued that the similar effect exists for a nonrotating but charged black hole even for the simplest case of radial motion of particles in the Reissner-Nordström background. All main features of the effect under discussion due to rotating black holes have their counterpart for the nonrotating charged ones.     

Creation of fundamental particles in Wesson’s IMT

Fundamental particles, regarded as possible constituents of quarks and leptons, are described classically in the framework of the Weyl-Dirac version of Wesson’s Induced Matter Theory (IMT). There are neutral particles and particles having charge \(\pm \frac{1}{3}e\). The particles appear on the 4D brane, our universe, and are filled with an induced by the 5D bulk substance. This substance is taken to have mass density, pressure, and (if charged) charge density, and is characterized by the equation of state ρ + P = 0. The interior is separated from the surrounding vacuum by a spherical boundary surface where the components of the 4D metric tensor h ₀₀ = 1/h ₁₁ = 0. Outside of the boundary holds the Schwarzschild, or the Reissner–Nordstrøm metric, while the particles are characterized by Mass, Radius, Charge.     

Could primary particles of ultrahigh energy be neutral?

Results are presented that were obtained from an analysis of the nuclear-physics and astrophysical features of extensive air showers of energy in the region E ₀≥10¹⁵ eV that were recorded at the Yakutsk array and other arrays over the world. It is shown that, at some values of E ₀, different data sets display local irregularities that are correlated in energy and which are interpreted as a manifestation of neutral particles of an extragalactic origin. The directions of their arrival point to the Supergalaxy plane (Local Supercluster of galaxies).     

Probing the mass degeneracy of particles with different spins

The spin is an important property of a particle. Although it is unlikely, there is still a possibility that two particles with di erent spins share similar masses. In this paper, we propose a method to probe this kind of mass degeneracy of particles with di erent spins. We use the cascade decay B⁺→X(3872)K⁺, X(3872)→D⁺D^- to illustrate our method. It can be seen that the possible mass degeneracy of X(3872) can lead to interesting behavior in the corresponding cascade decay.     

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 A (> 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.     

Triviality pursuit: Can elementary scalar particles exist?

Great effort is presently being expended in the search for elementary scalar “Higgs” particles. These particles have yet to be observed. The primary justification for this search is the theoretically elegant Higgs-Kibble mechanism, in which the interactions of elemetary scalars are used to generate gauge boson masses in a quantum field theory. However, strong evidence suggests that at least a pure φ⁴ scalar field theory is trivial or noninteracting. Should this triviality persist in more complicated systems such as the standard model of the weak interaction, the motivation for looking for Higgs particles would be seriously undermined. Alternatively, the presence of gauge and fermion fields can rescue a pure scalar theory from triviality. Phenomenological constraints (such as a bounded or even predictable Higgs mass) may then be implied. In this report the evidence for triviality in various field theories is reviewed, and the implications for high energy physics are discussed.