On possible existence of the dibaryon resonance d1∗d^*_1 and its role in the npγnp\gamma and pdγpd\gamma processes below the pion threshold

We give reasons for the existence of the NN decoupled dibaryon resonance $d^*_1$(1956). Strong evidence for its presence has first been found in the energy spectrum of coincident photons emitted at $\pm 90^0$ from the $pp \to \gamma\gamma X$ process at 216 MeV measured by the DIB2$\gamma$ collaboration at JINR. As further experimental indications of the $d^*_1$(1956) existence we present those found in the available photon energy spectra of $np\gamma$, $pd\gamma$, and $pA\gamma$ reactions below the pion threshold. It is noted that serious discrepancies between the $np\gamma$ and $pd\gamma$ experimental cross sections and theoretical calculations can reasonably be explained by the fact that latter did not take into account the $d^*_1$ effect.Comment: 4 pages, LaTex, 4 eps-figures, Talk presented at the XVI International Conference on Particle and Nuclei (PANIC02), Osaka, Japan, Sep. 30 - Oct. 4, 200

Quantization and holomorphic anomaly

We study wave functions of B-model on a Calabi-Yau threefold in various polarizations.Comment: 15 page

The Accidental Terrorist: Okhrana Connections to the Extreme-Right and the Attempt to Assassinate Sergei Witte in 1907

This article represents a case study in the relationship between the tsarist secret police (commonly known as the Okhrana in the West and okhranka in Russia) and acts of political terror perpetrated by the extreme-right in late imperial Russia. This specific case concerns the tangled web of conspiracy, propaganda and controversy that surrounded the attempted assassination of former-Chairman of the Council of Ministers, Sergei Witte, in 1907

The Hitchin functionals and the topological B-model at one loop

The quantization in quadratic order of the Hitchin functional, which defines by critical points a Calabi-Yau structure on a six-dimensional manifold, is performed. The conjectured relation between the topological B-model and the Hitchin functional is studied at one loop. It is found that the genus one free energy of the topological B-model disagrees with the one-loop free energy of the minimal Hitchin functional. However, the topological B-model does agree at one-loop order with the extended Hitchin functional, which also defines by critical points a generalized Calabi-Yau structure. The dependence of the one-loop result on a background metric is studied, and a gravitational anomaly is found for both the B-model and the extended Hitchin model. The anomaly reduces to a volume-dependent factor if one computes for only Ricci-flat Kahler metrics.Comment: 33 pages, LaTe

Gauge Invariance and Tachyon Condensation in Cubic Superstring Field Theory

The gauge invariance of cubic open superstring field theory is considered in a framework of level truncation, and applications to the tachyon condensation problem are discussed. As it is known, in the bosonic case the Feynman-Siegel gauge is not universal within the level truncation method. We explore another gauge that is more suitable for calculation of the tachyon potential for fermionic string at level (2,6). We show that this new gauge has no restrictions on the region of its validity at least at this level.Comment: 21 pages, 2 figures, LaTeX 2e; references added, typos correcte

Dynamics with Infinitely Many Derivatives: The Initial Value Problem

Differential equations of infinite order are an increasingly important class of equations in theoretical physics. Such equations are ubiquitous in string field theory and have recently attracted considerable interest also from cosmologists. Though these equations have been studied in the classical mathematical literature, it appears that the physics community is largely unaware of the relevant formalism. Of particular importance is the fate of the initial value problem. Under what circumstances do infinite order differential equations possess a well-defined initial value problem and how many initial data are required? In this paper we study the initial value problem for infinite order differential equations in the mathematical framework of the formal operator calculus, with analytic initial data. This formalism allows us to handle simultaneously a wide array of different nonlocal equations within a single framework and also admits a transparent physical interpretation. We show that differential equations of infinite order do not generically admit infinitely many initial data. Rather, each pole of the propagator contributes two initial data to the final solution. Though it is possible to find differential equations of infinite order which admit well-defined initial value problem with only two initial data, neither the dynamical equations of p-adic string theory nor string field theory seem to belong to this class. However, both theories can be rendered ghost-free by suitable definition of the action of the formal pseudo-differential operator. This prescription restricts the theory to frequencies within some contour in the complex plane and hence may be thought of as a sort of ultra-violet cut-off.Comment: 40 pages, no figures. Added comments concerning fractional operators and the implications of restricting the contour of integration. Typos correcte

Active Brownian Particles. From Individual to Collective Stochastic Dynamics

We review theoretical models of individual motility as well as collective dynamics and pattern formation of active particles. We focus on simple models of active dynamics with a particular emphasis on nonlinear and stochastic dynamics of such self-propelled entities in the framework of statistical mechanics. Examples of such active units in complex physico-chemical and biological systems are chemically powered nano-rods, localized patterns in reaction-diffusion system, motile cells or macroscopic animals. Based on the description of individual motion of point-like active particles by stochastic differential equations, we discuss different velocity-dependent friction functions, the impact of various types of fluctuations and calculate characteristic observables such as stationary velocity distributions or diffusion coefficients. Finally, we consider not only the free and confined individual active dynamics but also different types of interaction between active particles. The resulting collective dynamical behavior of large assemblies and aggregates of active units is discussed and an overview over some recent results on spatiotemporal pattern formation in such systems is given.Comment: 161 pages, Review, Eur Phys J Special-Topics, accepte

On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)