The Flow Fingerprinting Game

Linking two network flows that have the same source is essential in intrusion detection or in tracing anonymous connections. To improve the performance of this process, the flow can be modified (fingerprinted) to make it more distinguishable. However, an adversary located in the middle can modify the flow to impair the correlation by delaying the packets or introducing dummy traffic. We introduce a game-theoretic framework for this problem, that is used to derive the Nash Equilibrium. As obtaining the optimal adversary delays distribution is intractable, some approximations are done. We study the concrete example where these delays follow a truncated Gaussian distribution. We also compare the optimal strategies with other fingerprinting schemes. The results are useful for understanding the limits of flow correlation based on packet timings under an active attacker.Comment: Workshop on Information Forensics and Securit

Two and three electrons in a quantum dot: 1/|J| - expansion

We consider systems of two and three electrons in a two-dimensional parabolic quantum dot. A magnetic field is applied perpendicularly to the electron plane of motion. We show that the energy levels corresponding to states with high angular momentum, J, and a low number of vibrational quanta may be systematically computed as power series in 1/|J|. These states are relevant in the high-B limit.Comment: LaTeX, 15 pages,6 postscript figure

Magnetized strange quark matter and magnetized strange quark stars

Strange quark matter could be found in the core of neutron stars or forming strange quark stars. As is well known, these astrophysical objects are endowed with strong magnetic fields which affect the microscopic properties of matter and modify the macroscopic properties of the system. In this paper we study the role of a strong magnetic field in the thermodynamical properties of a magnetized degenerate strange quark gas, taking into account beta-equilibrium and charge neutrality. Quarks and electrons interact with the magnetic field via their electric charges and anomalous magnetic moments. In contrast to the magnetic field value of 10^19 G, obtained when anomalous magnetic moments are not taken into account, we find the upper bound B < 8.6 x 10^17 G, for the stability of the system. A phase transition could be hidden for fields greater than this value.Comment: 9 pages, 9 figure

How many Ultra High Energy Cosmic Rays could we expect from Centaurus A?

The Pierre Auger Observatory has associated a few ultra high energy cosmic rays with the direction of Centaurus A. This source has been deeply studied in radio, infrared, X-ray and $\gamma$-rays (MeV-TeV) because it is the nearest radio-loud active galactic nuclei. Its spectral energy distribution or spectrum shows two main peaks, the low energy peak, at an energy of $10^{-2}$ eV, and the high energy peak, at about 150 keV. There is also a faint very high energy (E $\geq$ 100 GeV) $\gamma$-ray emission fully detected by the High Energy Stereoscopic System experiment. In this work we describe the entire spectrum, the two main peaks with a Synchrotron/Self-Synchrotron Compton model and, the Very High Energy emission with a hadronic model. We consider p$\gamma$ and $pp$ interactions. For the p$\gamma$ interaction, we assume that the target photons are those produced at 150 keV in the leptonic processes. On the other hand, for the pp interaction we consider as targets the thermal particle densities in the lobes. Requiring a satisfactory description of the spectra at very high energies with p$\gamma$ interaction we obtain an excessive luminosity in ultra high energy cosmic rays (even exceeding the Eddington luminosity). However, when considering pp interaction to describe the $\gamma$-spectrum, the obtained number of ultra high energy cosmic rays are in agreement with Pierre Auger observations. Moreover, we calculate the possible neutrino signal from pp interactions on a Km$^3$ neutrino telescope using Monte Carlo simulations.Comment: Accepted in Ap

Constraints on the braneworld from compact stars

According to the braneworld idea, ordinary matter is confined on a 3-dimensional space (brane) that is embedded in a higher-dimensional space-time where gravity propagates. In this work, after reviewing the limits coming from general relativity, finiteness of pressure and causality on the brane, we derive observational constraints on the braneworld parameters from the existence of stable compact stars. The analysis is carried out by solving numerically the brane-modified Tolman-Oppenheimer-Volkoff equations, using different representative equations of state to describe matter in the star interior. The cases of normal dense matter, pure quark matter and hybrid matter are considered.Comment: 13 pages, 11 figures, 2 tables; new EoS considered, references and comments adde

Calorons on the lattice - a new perspective

We discuss the manifestation of instanton and monopole solutions on a periodic lattice at finite temperature and their relation to the infinite volume analytic caloron solutions with asymptotic non-trivial Polyakov loops. As a tool we use improved cooling and twisted boundary conditions. Typically we find 2Q lumps for topological charge Q. These lumps are BPS monopoles.Comment: Latex. 16 pages, 9 figure