On thermalization of a boost-invariant non-Abelian plasma

Using a holographic method, we further investigate the relaxation towards the hydrodynamic regime of a boost-invariant non-Abelian plasma taken out-of-equilibrium. In the dual description, the system is driven out-of-equilibrium by boundary sourcing, a deformation of the boundary metric, as proposed by Chesler and Yaffe. The effects of several deformation profiles on the bulk geometry are investigated by the analysis of the corresponding solutions of the Einstein equations. The time of restoration of the hydrodynamic regime is investigated: setting the effective temperature of the system at the end of the boundary quenching to T eff ( τ * ) = 500 MeV, the hydrodynamic regime is reached after a lapse of time of O $$\mathcal{O}$$ (1 fm/c)

ΔI=1/2 rule, ε′/ε and K→πνν¯ in Z′(Z) and G′ models with FCNC quark couplings

The experimental value for the isospin amplitude ReA2 in K→ππ decays has been successfully explained within the standard model (SM), both within the large N approach to QCD and by QCD lattice calculations. On the other hand within the large N approach the value of ReA0 is by at least 30% below the data. While this deficit could be the result of theoretical uncertainties in this approach and could be removed by future precise QCD lattice calculations, it cannot be excluded that the missing piece in ReA0 comes from new physics (NP). We demonstrate that this deficit can be significantly softened by tree-level FCNC transitions mediated by a heavy colourless Z′ gauge boson with a flavour-violating left-handed coupling ΔLsd(Z′) and an approximately universal flavour diagonal right-handed coupling ΔRqq(Z′) to the quarks. The approximate flavour universality of the latter coupling assures negligible NP contributions to ReA2 . This property, together with the breakdown of the GIM mechanisms at tree level, allows one to enhance significantly the contribution of the leading QCD-penguin operator Q6 to ReA0 . A large fraction of the missing piece in the ΔI=1/2 rule can be explained in this manner for MZ′ in the reach of the LHC, while satisfying the constraints from εK , ε′/ε , ΔMK , LEP-II and the LHC. The presence of a small right-handed flavour-violating coupling ΔRsd(Z′)≪ΔLsd(Z′) and of enhanced matrix elements of ΔS=2 left–right operators allows one to satisfy simultaneously the constraints from ReA0 and ΔMK , although this requires some fine-tuning. We identify the quartic correlation between Z′ contributions to ReA0 , ε′/ε , εK and ΔMK . The tests of this proposal will require much improved evaluations of ReA0 and ΔMK within the SM, of ⟨Q6⟩0 as well as precise tree-level determinations of |Vub| and |Vcb| . We present correlations between ε′/ε , K+→π+νν¯ and KL→π0νν¯ with and without the ΔI=1/2 rule constraint and generalise the whole analysis to Z′ with colour ( G′ ) and Z with FCNC couplings. In the latter case no improvement on ReA0 can be achieved without destroying the agreement of the SM with the data on ReA2 . Moreover, this scenario is very tightly constrained by ε′/ε . On the other hand, in the context of the ΔI=1/2 rule G′ is even more effective than Z′ : it provides the missing piece in ReA0 for MG′=(3.5 – 4.0)TeV

Z - Z ′ mixing and Z -mediated FCNCs in SU(3) C × SU(3) L × U(1) X models

Most of the existing analyses of flavour changing neutral current processes (FCNC) in the 331 models, based on the gauge group SU(3) C × SU(3) L × U(1) X , are fully dominated by tree-level exchanges of a new heavy neutral gauge boson Z ′. However, due to the Z − Z ′ mixing also corresponding contributions from Z boson are present. As the Z − Z ′ mixing is estimated generally in Z ′ models to be at most O 1 0 − 3 $$\mathcal{O}\left(1{0}^{-3}\right)$$ , the latter contributions are usually neglected. The paucity of relevant parameters in 331 models allows to check whether this neglect is really justified in these concrete models. We calculate the impact of these contributions on Δ F = 2 processes and rare K , B s and B d decays for different values of a parameter β , which distinguishes between various 331 models and for different fermion representations under the SU(3) L group. We find a general expression for the Z − Z ′ mixing in terms β , M Z , M Z ′ and tan β ¯ $$\overline{\beta}$$ , familiar from 2 Higgs Doublet models, that differs from the one quoted in the literature. We study in particular the models with β = ± n/ 3 $$\sqrt{3}$$ with n = 1 , 2 which have recently been investigated by us in the context of new data on B s , d → μ + μ − and B d → K * ( K ) μ + μ − . We find that these new contributions can indeed be neglected in the case of Δ F = 2 transitions and decays, like B d → K * μ + μ − , where they are suppressed by the small vectorial Z coupling to charged leptons. However, the contributions of tree-level Z exchanges to decays sensitive to axial-vector couplings, like B s , d → μ + μ − and B d → Kμ + μ − , and those with neutrinos in the final state, like b → sν ν ¯ $$\overline{\nu}$$ transitions, K + → π + ν ν ¯ $$\overline{\nu}$$ and K L → π 0 ν ν ¯ $$\overline{\nu}$$ cannot be generally neglected with size of Z contributions depending on β , tan β ¯ $$\overline{\beta}$$ and M Z ′ . We analyze how our recent results on FCNCs in 331 models, in particular correlations between various observables, are modified by these new contributions. As a byproduct we analyze for the first time the ratio ε ′ /ε in these models including both Z ′ and Z contributions. Our analysis of electroweak precision observables within 331 models demonstrates transparently that the interplay of NP effects in electroweak precision observables and those in flavour observables could allow in the future to identify the favourite 331 model

A. MASTROSERIO on behalf of the ALICE Collaboration

The ALICE experiment at LHC is mainly dedicated to heavy-ion physics. An overview of its performances, some predictions related to its first measurements and QGP observable measurements will be given.

ASAR Wide-Swath Mode: System and Processing Optimization

We discuss the algorithm and the implementation of a procedure to optimize both system and processing parameters for ASAR-WSM. The impact of the optimized setting is shown by comparing the quality measured on the early mission acquistions (non-optimized), with the later one, achieved after tuning both instruments and processing parameters.

Convexity of domains of Riemannian manifolds

Abstract. In this paper the problem of the geodesic connectedness and convexity of incomplete Riemannian manifolds is analyzed. To this aim, a detailed study of the notion of convexity for the associated Cauchy boundary is carried out. In particular, under widely discussed hypotheses, we prove the convexity of open domains (whose boundaries may be nondifferentiable) of a complete Riemannian manifold. Variational methods are mainly used. Examples and applications are provided, including a result for dynamical systems on the existence of trajectories with fixed energy

Like Breadcrumbs in the Forest: a Tool for Semantic Exploratory Search

The recent explosion of freely available RDF datasets on the Web calls for new tools and techniques for semantic-enabled exploratory browsing. We present ENT, an HTML5-based tool that guides the user through the navigation of RDF graphs avoiding the visualization of information resulting irrelevant for the exploratory task. Thanks to a hypertree-based visualization of the data-space, the user has a clear picture both of his/her navigation path and of the information he/she may discover

Semantic Tags Generation and Retrieval for Online Advertising

One of the main problems in online advertising is to display ads which are relevant and appropriate w.r.t. what the user is looking for. Often search engines fail to reach this goal as they do not consider semantics attached to keywords. In this paper we propose a system that tackles the problem by two different angles: help (i) advertisers to create more efficient ads campaigns and (ii) ads providers to properly match ads content to keywords in search engines. We exploit semantic relations stored in the DBpedia dataset and use an hybrid ranking system to rank keywords and to expand queries formulated by the user. Inputs of our ranking system are (i) the DBpedia dataset; (ii) external information sources such as classical search engine results and social tagging systems. We compare our approach with other RDF similarity measures, proving the validity of our algorithm with an extensive evaluation involving real users

1 Puzzles in charm spectroscopy

We briefly analyze aspects of open and hidden charm resonances, discussing in particular the mesons DsJ(2860) and X(3872). §1. Prologue The word puzzle means a problem, a mystery deserving explanation. It also indicates a game designed for testing ingenuity, where pieces of information have to be put together to reassemble a known picture. It is worth asking if recent results in charm spectroscopy 1) represent problems or information fitting into a known theoretical scheme. The answer is different in case of open and hidden charm mesons. §2. c¯s system and DsJ(2860) An example of new experimental information fitting into an established theoretical scheme is the meson DsJ(2860) recently observed by BaBar Collaboration2) in the DK system inclusively produced in e + e − → DKX, with M(DsJ(2860)) = 2856.6 ± 1.5±5.0 MeV and Γ(DsJ(2860) → DK) = 47±7±10 MeV (DK = D0K ++D+ K0 S). Together with this state, a broad structure was noticed with M = 2688 ± 4 ± 3 MeV and Γ = 112 ± 7 ± 36 MeV; indeed, Belle Collaboration3) reported the evidence of DsJ(2715) in B + → ¯ D0D0K + decays, with M(DsJ(2715)) = 2715 ± 11 +11 −14 MeV, Γ(DsJ(2715) = 115 ± 20 +36 −32 MeV and JP = 1 −. The interpretation of these charmed resonances is easier in the heavy quark limit mQ → ∞. In such a limit the spin sQ of the heavy quark and the angular momentum sℓ of the meson light degrees of freedom: sℓ = s¯q+ℓ (s¯q light antiquark spin, ℓ orbital angular momentum of the light degrees of freedom relative to the heavy quark) are decoupled, and the spin-parity sP ℓ is conserved in strong interaction processes. 5) Mesons can be classified as doublets of sP ℓ. Two states (P,P ∗ ) with JP = (0−,1 −) correspond to ℓ = 0. The four states corresponding to ℓ = 1 can be collected in two doublets, one (P ∗ 0,P ′ 1) with sP 1+ ℓ = and JP = (0+,1+), another one (P1,P2) with ((

Drop Call Probability in Established Cellular Networks: from data Analysis to Modelling

Abstract — The ever increase of advanced services offered by modern cellular networks require stringent Quality of Service (QoS) guarantee, obtained as the typical result of many optimization procedures. In this paper the phenomenon of dropped calls, one of the most important indices of QoS in a large scale well-established cellular network, has been analyzed. We verified from measured data traffic that, in a well-established cellular network, models available in literature are useless to pursue the objective of service optimization: many phenomena, neglected till now, heavily influence the call termination. To relate the drop call probability to these phenomena, an original analytical model has been developed. The obtained results, validated by experimental measures taken from a real network, can allow the network operator to optimize system performance improving the offered Quality of Service and their revenue. I