Kleinberg Navigation in Fractal Small World Networks

We study the Kleinberg problem of navigation in Small World networks when the underlying lattice is a fractal consisting of N>>1 nodes. Our extensive numerical simulations confirm the prediction that most efficient navigation is attained when the length r of long-range links is taken from the distribution P(r)~r^{-alpha}, where alpha=d_f, the fractal dimension of the underlying lattice. We find finite-size corrections to the exponent alpha, proportional to 1/(ln N)^2

The Case for Future Hadron Colliders From B→K(∗)μ+μ−B \to K^{(*)} \mu^+ \mu^- Decays

Recent measurements in $B \to K^{(*)} \mu^+ \mu^-$ decays are somewhat discrepant with Standard Model predictions. They may be harbingers of new physics at an energy scale potentially accessible to direct discovery. We estimate the sensitivity of future hadron colliders to the possible new particles that may be responsible for the anomalies: leptoquarks or $Z^\prime$s. We consider luminosity upgrades for a 14 TeV LHC, a 33 TeV LHC, and a 100 TeV $pp$ collider such as the FCC-hh. Coverage of $Z^\prime$ models is excellent: for narrow particles, with perturbative couplings that may explain the $b$-decay results for $Z^\prime$ masses up to 20 TeV, a 33 TeV 1 ab$^{-1}$ LHC is expected to cover most of the parameter space up to 8 TeV in mass, whereas the 100 TeV FCC-hh with 10 ab$^{-1}$ will cover all of it. A smaller portion of the leptoquark parameter space is covered by future colliders: for example, in a $\mu^+\mu^-jj$ di-leptoquark search, a 100 TeV 10 ab$^{-1}$ collider has a projected sensitivity up to leptoquark masses of 12 TeV (extendable to 21 TeV with a strong coupling for single leptoquark production), whereas leptoquark masses up to 41 TeV may in principle explain the anomalies.Comment: 24 pages, 10 figures. v2: Improved discussion and references added, version submitted to JHE

Panic behavior and the performance of circuit breakers: Empirical evidence

Stock Markets;Financial Crisis

Vortex in a relativistic perfect isentropic fluid and Nambu Goto dynamics

By a weak deformation of the cylindrical symmetry of the potential vortex in a relativistic perfect isentropic fluid, we study the possible dynamics of the central line of this vortex. In "stiff" material the Nanbu-Goto equations are obtainedComment: 11 pages, Accepted for publication in Physical Review

Enhancement of singly and multiply strangeness in p-Pb and Pb-Pb collisions at 158A GeV/c

The idea that the reduction of the strange quark suppression in string fragmentation leads to the enhancement of strange particle yield in nucleus-nucleus collisions is applied to study the singly and multiply strange particle production in p-Pb and Pb-Pb collisions at 158A GeV/c. In this mechanism the strange quark suppression factor is related to the effective string tension, which increases in turn with the increase of the energy, of the centrality and of the mass of colliding system. The WA97 observation that the strange particle enhancement increases with the increasing of centrality and of strange quark content in multiply strange particles in Pb-Pb collisions with respect to p-Pb collisions was accounted reasonably.Comment: 8 pages, 3 PostScript figures, in Latex form. submitted to PR