The Price of Anarchy in Selfish Multicast Routing

We study the price of anarchy for selfish multicast routing games in directed multigraphs with latency functions on the edges, extending the known theory for the unicast situation, and exhibiting new phenomena not present in the unicast model...

Multiphoton Exchange Processes in Ultraperipheral Relativistic Heavy Ion Collisions

The very strong electromagnetic fields present in ultraperipheral relativistic heavy ion collisions lead to important higher order effects of the electromagnetic interaction. These multiphoton exchange processes are studied using perturbation theory and the sudden or Glauber approximation. In many important cases, the multi-photon amplitudes factorize into independent single-photon amplitudes. These amplitudes have a common impact parameter vector, which induces correlations between the amplitudes. Impact-parameter dependent equivalent-photon spectra for simultaneous excitation are calculated, as well as, impact-parameter dependent gammagamma-luminosities. Excitations, like the multiphonon giant dipole resonances, vector meson production and multiple e+e- pair production can be treated analytically in a bosonic model, analogous to the emission of soft photons in QED.Comment: 28 pages, 7 figures, accepted for publication in Nucl. Phys.

A new viable region of the inert doublet model

The inert doublet model, a minimal extension of the Standard Model by a second Higgs doublet, is one of the simplest and most attractive scenarios that can explain the dark matter. In this paper, we demonstrate the existence of a new viable region of the inert doublet model featuring dark matter masses between Mw and about 160 GeV. Along this previously overlooked region of the parameter space, the correct relic density is obtained thanks to cancellations between different diagrams contributing to dark matter annihilation into gauge bosons (W+W- and ZZ). First, we explain how these cancellations come about and show several examples illustrating the effect of the parameters of the model on the cancellations themselves and on the predicted relic density. Then, we perform a full scan of the new viable region and analyze it in detail by projecting it onto several two-dimensional planes. Finally, the prospects for the direct and the indirect detection of inert Higgs dark matter within this new viable region are studied. We find that present direct detection bounds already rule out a fraction of the new parameter space and that future direct detection experiments, such as Xenon100, will easily probe the remaining part in its entirety.Comment: 27 pages, 16 figure

Scalar Multiplet Dark Matter

We perform a systematic study of the phenomenology associated to models where the dark matter consists in the neutral component of a scalar SU(2)_L n-uplet, up to n=7. If one includes only the pure gauge induced annihilation cross-sections it is known that such particles provide good dark matter candidates, leading to the observed dark matter relic abundance for a particular value of their mass around the TeV scale. We show that these values actually become ranges of values -which we determine- if one takes into account the annihilations induced by the various scalar couplings appearing in these models. This leads to predictions for both direct and indirect detection signatures as a function of the dark matter mass within these ranges. Both can be largely enhanced by the quartic coupling contributions. We also explain how, if one adds right-handed neutrinos to the scalar doublet case, the results of this analysis allow to have altogether a viable dark matter candidate, successful generation of neutrino masses, and leptogenesis in a particularly minimal way with all new physics at the TeV scale.Comment: 43 pages, 20 figure

Gamma rays from the annihilation of singlet scalar dark matter

We consider an extension of the Standard Model by a singlet scalar that accounts for the dark matter of the Universe. Within this model we compute the expected gamma ray flux from the annihilation of dark matter particles in a consistent way. To do so, an updated analysis of the parameter space of the model is first presented. By enforcing the relic density constraint from the very beginning, the viable parameter space gets reduced to just two variables: the singlet mass and the higgs mass. Current direct detection constraints are then found to require a singlet mass larger than 50 GeV. Finally, we compute the gamma ray flux and annihilation cross section and show that a large fraction of the viable parameter space lies within the sensitivity of Fermi-GLAST.Comment: 13 pages, 5 figures. v2: minor modifications to text and figures; main results unchanged. v3: some references adde

Deviation from Tri-Bimaximal Mixing and Large Reactor Mixing Angle

Recent observations for a non-zero $\theta_{13}$ have come from various experiments. We study a model of lepton mixing with a 2-3 flavor symmetry to accommodate the sizable $\theta_{13}$ measurement. In this work, we derive deviations from the tri-bimaximal (TBM) pattern arising from breaking the flavor symmetry in the neutrino sector, while the charged leptons contribution has been discussed in a previous work. Contributions from both sectors towards accommodating the non-zero $\theta_{13}$ measurement are presented.Comment: 25 pages, 12 figures. arXiv admin note: text overlap with arXiv:1109.232

New Applications for Phage Integrases

Within the last twenty-five years bacteriophage integrases have rapidly risen to prominence as genetic tools for a wide range of applications from basic cloning to genome engineering. Serine integrases such as that from ϕC31 and its relatives have found an especially wide-range of applications within diverse micro-organisms right through to multi-cellular eukaryotes. Here we review the mechanisms of the two major families of integrases, the tyrosine and serine integrases, and the advantages and disadvantages of each type as they are applied in genome engineering and synthetic biology. In particular, we focus on the new areas of metabolic pathway construction and optimisation, bio-computing, heterologous expression and multiplexed assembly techniques. Integrases are versatile and efficient tools that can be used in conjunction with the various extant molecular biology tools to streamline the synthetic biology production line

Algorithmic and Probabilistic Aspects of the Bipartite Traveling Salesman Problem

Contents Introduction 7 1 Preliminaries 11 1.1 It is not only salesmen who travel . . . . . . . . . . . . . . . . . . 11 1.2 The alternating TSP . . . . . . . . . . . . . . . . . . . . . . . . . 11 1.3 Basic denitions and notations . . . . . . . . . . . . . . . . . . . . 12 2 Euclidean bipartite TSP 15 2.1 Complexity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.2 The trouble with good TSP approximations . . . . . . . . . . . . 16 2.3 The matching method . . . . . . . . . . . . . . . . . . . . . . . . 17 2.4 The spanning tree strategy . . . . . . . . . . . . . . . . . . . . . . 20 2.5 Cycle covers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 3 Computational results 33 3.1 Uniformly distributed points . . . . . . . . . . . . . . . . . . . . . 33 3.2 Two non-uniform point distributions . . . . . . . . . . . . . . . . 34 4 Random points in the unit square 37 4.1 An optimal algorithm

Fast approximation of minimum multicast congestion – Implementation VERSUS Theory

The problem of minimizing the maximum edge congestion in a multicast communication network generalizes the well-known NP-hard multicommodity flow problem. We give the presently best theoretical approximation results as well as efficient implementations. In particular we show that for a network with m edges and k multicast requests, an r(1 + ε)(rOPT + exp(1)lnm)-approximation can be computed in O(kmε-2lnklnm) time, where β bounds the time for computing an r-approximate minimum Steiner tree. Moreover, we present a new fast heuristic that outperforms the primal-dual approaches with respect to both running time and objective value