High Energy Physics - Phenomenology

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New submissions for Wed, 5 Nov 14

[1]  arXiv:1411.0664 [pdf, other]

Title: Improving the sensitivity of stop searches with on-shell constrained invariant mass variables

Authors: Won Sang Cho, James S. Gainer, Doojin Kim, Konstantin T. Matchev, Filip Moortgat, Luc Pape, Myeonghun Park

Comments: 49 pages, 28 figues

Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

The search for light stops is of paramount importance, both in general as a promising path to the discovery of beyond the standard model physics and more specifically as a way of evaluating the success of the naturalness paradigm. While the LHC experiments have ruled out much of the relevant parameter space, there are "stop gaps", i.e., values of sparticle masses for which existing LHC analyses have relatively little sensitivity to light stops. We point out that techniques involving on-shell constrained M_2 variables can do much to enhance sensitivity in this region and hence help close the stop gaps. We demonstrate the use of these variables for several benchmark points and describe the effect of realistic complications, such as detector effects and combinatorial backgrounds, in order to provide a useful toolkit for light stop searches in particular, and new physics searches at the LHC in general.

[2]  arXiv:1411.0665 [pdf, other]

Title: Building a Better Boosted Top Tagger

Authors: Andrew J. Larkoski, Ian Moult, Duff Neill

Comments: 5 pages, 4 figures

Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

Distinguishing hadronically decaying boosted top quarks from massive QCD jets is an important challenge at the Large Hadron Collider. In this paper we use the power counting method to study jet substructure observables designed for top tagging, and gain insight into their performance. We introduce a powerful new family of discriminants formed from the energy correlation functions which outperform the widely used N-subjettiness. These observables take a highly non-trivial form, demonstrating the importance of a systematic approach to their construction.

[3]  arXiv:1411.0668 [pdf, other]

Title: Invisible dark gauge boson search in top decays using a kinematic method

Authors: Doojin Kim, Hye-Sung Lee, Myeonghun Park

Comments: 19 pages, 6 figures

Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

We discuss the discovery potential of a dark force carrier ($Z'$) of very light mass, $m_{Z'} \lesssim {\cal O}(1-10)$ GeV, at hadron colliders via rare top quark decays, especially when it decays invisibly in typical search schemes. We emphasize that the top sector is promising for the discovery of new particles because top quark pairs are copiously produced at the Large Hadron Collider. The signal process is initiated by a rare top decay into a bottom quark and a charged Higgs boson ($H^\pm$) decaying subsequently into a $W$ and one or multiple $Z'$s. The light $Z'$ can be invisible in collider searches in various scenarios, and it would be hard to distinguish the relevant collider signature from the regular $t\bar{t}$ process in the Standard Model. We suggest a search strategy using the recently proposed on-shell constrained $M_2$ variables. Our signal process is featured by an $\textit{asymmetric}$ event topology, while the $t\bar{t}$ is $\textit{symmetric}$. The essence behind the strategy is to evoke some contradiction in the relevant observables by applying the kinematic variables designed under the assumption of the $t\bar{t}$ event topology. To see the viability of the proposed technique, we perform Monte Carlo simulations including realistic effects such as cuts, backgrounds, detector resolution, and so on at the LHC of $\sqrt{s}=14$ TeV.

[4]  arXiv:1411.0669 [pdf, ps, other]

Title: Model-independent precision constraints on dimension-6 operators

Authors: Adam Falkowski, Francesco Riva

Comments: 21 pages

Subjects: High Energy Physics - Phenomenology (hep-ph)

We discuss electroweak precision constraints on dimension-6 operators in the effective theory beyond the standard model. We identify the combinations of these operators that are constrained by the pole observables (the W and Z masses and on-shell decays) and by the W boson pair production. To this end, we define a set of effective couplings of W and Z bosons to fermions and to itself, which capture the effects of new physics corrections. This formalism clarifies which operators are constrained by which observable, independently of the adopted basis of operators. We obtain numerical constraints on the coefficients of dimension-6 operator in a form that can be easily adapted to any particular basis of operators, or any particular model with new heavy particles.

[5]  arXiv:1411.0675 [pdf, other]

Title: Two-Loop Higgs mass calculations in supersymmetric models beyond the MSSM with SARAH and SPheno

Authors: Mark D. Goodsell, Kilian Nickel, Florian Staub

Comments: 23 pages, 4 figures

Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

We present an extension to the Mathematica package SARAH which allows for Higgs mass calculations at the two-loop level in a wide range of supersymmetric models beyond the MSSM. These calculations are based on the effective potential approach and include all two-loop corrections which are independent of electroweak gauge couplings. For the numerical evaluation Fortran code for SPheno is generated by SARAH. This allows the prediction of the Higgs mass in more complicated SUSY models with the same precision that most state-of-the-art spectrum generators provide for the MSSM.

[6]  arXiv:1411.0676 [pdf, other]

Title: Precision Higgsstrahlung as a Probe of New Physics

Authors: Nathaniel Craig, Marco Farina, Matthew McCullough, Maxim Perelstein

Comments: 21 pages, 7 figures

Subjects: High Energy Physics - Phenomenology (hep-ph)

A "Higgs factory", an electron-positron collider with center-of-mass energy of about 250 GeV, will measure the cross section of the Higgsstrahlung process, $e^+e^-\rightarrow hZ$, with sub-percent precision. This measurement is sensitive to a variety of new physics scenarios. In this paper, we study two examples. First, we compute corrections to the $e^+e^-\rightarrow hZ$ differential cross section in the effective field theory (EFT) approach, including the complete set of dimension-6 operators contributing to this process. These results are applicable to any model where the new physics mass scale is significantly above the weak scale. Second, we present a complete one-loop calculation of the effect of third-generation squarks, with arbitrary soft masses and mixing, on this cross section. This is expected to be the leading correction in natural supersymmetric models. We demonstrate the agreement between the full one-loop calculation and the EFT result in the limit of large stop masses. Finally, we estimate the discovery reach of the $e^+e^-\rightarrow hZ$ cross section measurement in the two models.

[7]  arXiv:1411.0677 [pdf, other]

Title: A New Perspective on Scale Uncertainties for Diboson Processes

Authors: Prerit Jaiswal

Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

The electroweak diboson production cross-sections are known to receive large radiative corrections beyond leading-order (LO), approaching up to 60% at next-to-leading order (NLO), compared to the scale uncertainties which are in the range 1-5% at LO. If the scale uncertainties are to be taken seriously, the NLO predictions are as much as 30 sigma away from their LO counterpart suggesting a very poor convergence of the perturbation theory. In this paper, we show that there is a second source of scale uncertainty which has not been considered in the literature, namely the complex phase of the scales, which can lead to large perturbative corrections. Using the formalism of soft-collinear effective theory, we resum these large contributions from the complex phase, finding that the scale uncertainties in fixed-order calculations can be grossly underestimated compared to the resummed predictions, which have uncertainties as large as 13-16% at LO. Even at NLO, we find that the scale uncertainties are marginally higher than previously estimated, depending on the choice of scale. Using our method of scale variation, the compatibility of LO and NLO results within the scale uncertainties is vastly improved so that the perturbation theory can be relied upon. This method of scale variation can be easily extended to beyond NLO calculations as well as other LHC processes.

[8]  arXiv:1411.0693 [pdf, ps, other]

Title: New textures for the lepton mass matrices

Authors: P.M. Ferreira, L. Lavoura

Comments: 31 pages, 6 figures

Subjects: High Energy Physics - Phenomenology (hep-ph)

We study predictive textures for the lepton mass matrices in which the charged-lepton mass matrix has either four or five zero matrix elements while the neutrino Majorana mass matrix has, respectively, either four or three zero matrix elements. We find that all the viable textures of these two kinds share many predictions: the neutrino mass spectrum is inverted, the sum of the light-neutrino masses is close to 0.1 eV, the Dirac phase $\delta$ in the lepton mixing matrix is close to either $0$ or $\pi$, and the mass term responsible for neutrinoless double-beta decay lies in between 12 and 22 meV.

[9]  arXiv:1411.0714 [pdf, other]

Title: Evolution of gluon TMD at low and moderate x

Authors: I. Balitsky, A. Tarasov

Comments: 10 pages, 3 figures

Subjects: High Energy Physics - Phenomenology (hep-ph)

We study how the rapidity evolution of gluon transverse momentum dependent distribution changes from nonlinear evolution at small $x\ll 1$ to linear double-logarithmic evolution at moderate $x\sim 1$.

[10]  arXiv:1411.0723 [pdf, other]

Title: CP Asymmetries (\& T Violation) in Known Matter -- and beyond

Authors: I.I. Bigi

Comments: 29 pages, 6 figures

Subjects: High Energy Physics - Phenomenology (hep-ph)

Finding \cp~violation (\CPV ) in 1964 produced a real revolution in the fundamental dynamics, although the community did not understand it right away. The paper by Kobayashi \& Maskawa \cite{KM} appeared in 1973 to describe \CPV~in classes of three (or more) families of quarks, non-minimal Higgs' dynamics and/or charged right-handed currents. The Standard Model is defined now with three families of quarks. It can describe the measured \cp~ \& \ot~violation in kaon and $B$ mesons at least as the leading source. None has been found in baryons, charm mesons, top quarks and EDMs. We have failed the explain our matter vs. anti-matter huge asymmetry. Even when there is no obvious connections with that asymmetry, it makes sense to probe \CPV~for the signs of New Dynamics \& their features. Furthermore we have to measure regional \CPV~in multi-body final states with accuracy. Finally I emphasize \CPV~in leptonic dynamics, connections with Dark Matter and possible axion's impact of cosmology.

[11]  arXiv:1411.0726 [pdf, ps, other]

Title: Constraining double parton correlations and interferences

Authors: Tomas Kasemets, Piet J. Mulders

Comments: 10 pages, 1 figure

Subjects: High Energy Physics - Phenomenology (hep-ph)

Double parton scattering (DPS) has become very relevant as a background to interesting analyses performed by the experiments at the LHC. It encodes knowledge of correlations between the proton constituents not accessible in single parton scattering. Within perturbative QCD DPS is described in terms of partonic subprocesses and double parton distributions (DPDs). There exists a large number of different DPDs describing the different possible states of two partons inside a proton. They include correlations between the two partons and interferences between the two hard subprocesses. Taking the probability interpretation of the DPDs as starting point, we derive limits on the interference DPDs and thereby constrain the size of correlations between two partons inside an unpolarized proton.

[12]  arXiv:1411.0741 [pdf, ps, other]

Title: Resummation of Jet Shapes and Extracting Properties of the Quark-Gluon Plasma

Authors: Yang-Ting Chien

Comments: 8 pages, 3 figures, to appear in the Proceedings of the QCD Evolution Workshop 2014, Santa Fe, NM, May 12-16, 2014

Subjects: High Energy Physics - Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)

Understanding the properties of the quark-gluon plasma (QGP) that is produced in ultra-relativistic nucleus-nucleus collisions has been one of the top priorities of the heavy ion program at the LHC. Energetic jets are produced and subsequently quenched in the collisions. Such jet quenching phenomena provide promising tools to probe the medium properties by studying the modification of jets due to the medium interactions. Significant modifications of jet shapes have been measured. In this talk we focus on the calculation of jet shapes in both proton-proton and lead-lead collisions using soft-collinear effective theory (SCET), with Glauber gluon interactions in the medium. Large logarithms in jet shapes are resummed at next-to-leading logarithmic (NLL) accuracy by the renormalization-group evolution between hierarchical jet scales. The medium interactions contribute as power corrections, and we calculate the modification of jet shapes at leading order in opacity with the static QGP model. Preliminary results are presented with good agreement with the recent CMS jet shape measurements.

[13]  arXiv:1411.0752 [pdf, other]

Title: Electroweakly-Interacting Dirac Dark Matter

Authors: Natsumi Nagata, Satoshi Shirai

Comments: 5 pages, 3 figures

Subjects: High Energy Physics - Phenomenology (hep-ph)

We consider a class of fermionic dark matter candidates that are charged under both the SU(2)$_L$ and U(1)$_Y$ gauge interactions. Such a dark matter is stringently restricted by the dark matter direct detection experiments, since the $Z$-boson exchange processes induce too large dark matter-nucleus elastic scattering cross sections. Effects of ultraviolet (UV) physics, however, split it into two Majorana fermions to evade the constraint. These effects may be probed by means of the dark matter-nucleus scattering via the Higgs-boson exchange process, as well as the electric dipole moments induced by the dark matter and its SU(2)$_L$ partner fields. In this Letter, we evaluate them with effective operators that describe the UV-physics effects. It turns out that the constraints coming from the experiments for the quantities have already restricted the dark matters with hypercharge $Y\geq 3/2$. Future experiments have sensitivities to probe this class of dark matter candidates, and may disfavor the $Y\geq 1$ cases if no signal is observed. In this case, only the $Y=0$ and $1/2$ cases may be the remaining possibilities for the SU(2)$_L$ charged fermionic dark matter candidates.

[14]  arXiv:1411.0768 [pdf, ps, other]

Title: Asymmetries from the interference between Cabibbo-favored and doubly-Cabibbo-suppressed D decays

Authors: Dao-Neng Gao

Comments: 7 pages, 1 figure

Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

A phenomenological analysis of $D\to K\pi$ and $D_s^+\to K K $decays including both Cabibbo favored and doubly Cabibbo suppressed modes have been presented by employing the present experimental data. SU(3) symmetry breaking effects from the decay constants and form factors have been taken into account in the analysis. Three asymmetries, $R(D^0)$, $R(D^+)$, and $R(D_s^+)$, which are generated through interference between Cabbibo favored and doubly Cabibbo suppressed decays, are estimated. Theoretical results agree well with the current measurements.

[15]  arXiv:1411.0787 [pdf, other]

Title: Halo-Independent analysis of direct dark matter detection data for any WIMP interaction

Authors: Graciela B. Gelmini

Comments: Talk given at the 37th. International Conference on High Energy Physics (ICHEP 2014), July 2 to 9, 2014, Valencia, Spain; 7 pages, 7 figures

Subjects: High Energy Physics - Phenomenology (hep-ph)

The halo independent comparison of direct dark matter detection data eliminates the need to make any assumption on the uncertain local dark matter distribution and is complementary to the usual data comparison which required assuming a dark halo model for our galaxy. The method, initially proposed for WIMPs with spin-independent contact interactions, has been generalized to any other interaction and applied to recent data on "Light WIMPs".

[16]  arXiv:1411.0817 [pdf, other]

Title: Charge and magnetization densities in transverse coordinate and impact parameter space

Authors: Narinder Kumar, Harleen Dahiya

Comments: 18 pages, 5 figures. To appear in Phys. Rev. D

Subjects: High Energy Physics - Phenomenology (hep-ph); Nuclear Theory (nucl-th)

Electromagnetic form factors obtained from the overlap of light front wave functions (LFWFs) have been used to study the transverse densities of charge and magnetization. The calculations have been carried out to develop a relation between the charge distribution of the quarks inside nucleon in the transverse coordinate space as well as in the impact parameter space. When a comparison is carried out, it is found that the transverse distribution in the impact parameter space, where the longitudinal momentum fraction $x$ can be fixed, falls off faster than the spatial distribution in the transverse coordinate space where there is some contribution from the longitudinal momentum as well. The anomalous magnetization density of the nucleon has also been discussed. Further, we have also presented the results of the QCD transverse AdS charge density inspired from the holographic QCD model.

[17]  arXiv:1411.0832 [pdf, ps, other]

Title: SSA in electroproduction of $J/ψ$ and QCD-evolved TMD's

Authors: Rohini M. Godbole, Abhiram Kaushik, Anuradha Misra, Vaibhav S. Rawoot

Comments: Conference proceedings of QCD Evolution Workshop 2014

Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

We estimate Sivers asymmetry in low virtuality photoproduction of $J/\psi$ using color evaporation model and taking into account $Q^2$- evolution of transverse momentum dependent PDF's and Sivers function. There is a substantial reduction in asymmetry as compared to our previous analysis wherein the $Q^2$-dependance came only from DGLAP evolution of collinear part of TMDs. The estimates of asymmetry are comparable to our earlier estimates in which we had used analytical solution of only an approximated form of the evolution equations.
We have also estimated asymmetry using the latest parametrization by Echevarria {\it et al.} which are based on an evolution kernel in which the perturbative part is resummed to NLL accuracy.

[18]  arXiv:1411.0847 [pdf, other]

Title: Multiple hard scattering and parton correlations in the proton

Authors: Markus Diehl

Comments: 9 pages, 5 figures. To appear in the proceedings of the QCD Evolution Workshop 2014, Santa Fe, NM, 12-16 May 2014

Subjects: High Energy Physics - Phenomenology (hep-ph)

This proceedings contribution gives a brief introduction to the theoretical description of double parton scattering and discusses several open problems.

[19]  arXiv:1411.0865 [pdf, ps, other]

Title: QCD Sum Rules for Heavy-Meson Decay Constants: Impact of Renormalization Scale and Scheme

Authors: Wolfgang Lucha, Dmitri Melikhov, Silvano Simula

Comments: 5 pages, 3 figures, contributed to "Quark Confinement and the Hadron Spectrum XI" (8 - 12 September 2014, St. Petersburg, Russia)

Subjects: High Energy Physics - Phenomenology (hep-ph)

Within the realm of QCD sum rules, one of the most important areas of application of this nonperturbative approach is the prediction of the decay constants of heavy mesons. However, in spite of the fact that, indisputably, the adopted techniques are, of course, very similar, we encounter rather dissimilar challenges, or obstacles, when extracting from two-point correlators of appropriate heavy-light currents interpolating the mesons, the characteristics of charmed mesons with different spin. In view of this, it seems worthwhile to us to revisit this issue for the case of charmed pseudoscalar mesons $D_{(s)}$ and vector mesons $D^*_{(s)}.$

[20]  arXiv:1411.0887 [pdf, other]

Title: Ballistic protons in incoherent exclusive vector meson production as a measure of rare parton fluctuations at an Electron-Ion Collider

Authors: T. Lappi, H. Mäntysaari, R. Venugopalan

Comments: 5 pages, 4 figures, RevTEX

Subjects: High Energy Physics - Phenomenology (hep-ph)

We argue that the proton multiplicities measured in Roman pot detectors at an electron ion collider can be used to determine centrality classes in incoherent diffractive scattering. Incoherent diffraction probes the fluctuations in the interaction strengths of multi-parton Fock states in the nuclear wavefunctions. In particular, the saturation scale that characterizes this multi-parton dynamics is significantly larger in central events relative to minimum bias events. As an application, we study the centrality dependence of incoherent diffractive vector meson production. We identify an observable which is simultaneously very sensitive to centrality triggered parton fluctuations and insensitive to details of the model.

[21]  arXiv:1411.0904 [pdf, other]

Title: Hard Excluseive $Φ$ and $J/Ψ$ Photoproduction off a Proton

Authors: A. T. Goritschnig, B. Melic, K. Passek-Kumericki, W. Schweiger

Comments: 6 pages, talk given at conference C14-04-28.1

Subjects: High Energy Physics - Phenomenology (hep-ph); Nuclear Theory (nucl-th)

We study the photoproduction of the vector mesons $\Phi$ and $J/\Psi$ off a proton in the kinematical regime of large energies and scattering angles within the framework of perturbative QCD. Our investigations are based on the hard scattering approach. This means that the hadrons are replaced by their valence Fock states and scattering on the partonic level is described by tree graphs in which the large transferred momentum is redistributed between the valence partons via the exchange of hard gluons. We find that the unpolarized photoproduction cross sections are dominated by Compton-scattering-like graphs in which the photon couples to the proton, whereas vector-meson-dominance-like graphs, in which the photon fluctuates into the heavy quark-antiquark pair which then exchanges two gluons with the proton, play a minor role. We give explicit predictions for unpolarized scattering cross sections and compare them with experimental data where possible.

[22]  arXiv:1411.0909 [pdf, ps, other]

Title: Generalized Ginzburg-Landau approach to inhomogeneous phases in nonlocal chiral quark models

Authors: J.P. Carlomagno, D. Gomez Dumm, N.N. Scoccola

Comments: 9 pages, 1 figure

Subjects: High Energy Physics - Phenomenology (hep-ph)

We analyze the presence of inhomogeneous phases in the QCD phase diagram within the framework of nonlocal chiral quark models. We concentrate in particular in the positions of the tricritical (TCP) and Lifshitz (LP) points, which are studied in a general context using a generalized Ginzburg-Landau approach. We find that for all the phenomenologically acceptable model parametrizations considered the TCP is located at a higher temperature and a lower chemical potential in comparison with the LP. Consequently, these models seem to favor a scenario in which the onset of the first order transition between homogeneous phases is not covered by an inhomogeneous, energetically favored phase.

[23]  arXiv:1411.0911 [pdf, ps, other]

Title: Reducing differential equations for multiloop master integrals

Authors: Roman N. Lee

Comments: 24 pages

Subjects: High Energy Physics - Phenomenology (hep-ph)

We present an algorithm of the reduction of the differential equations for master integrals to the Fuchsian form with the right-hand side matrix linearly depending on dimensional regularization parameter $\epsilon$.

[24]  arXiv:1411.0916 [pdf, ps, other]

Title: Electroweak corrections to lepton pair production in association with two hard jets at the LHC

Authors: Ansgar Denner, Lars Hofer, Andreas Scharf, Sandro Uccirati

Comments: 28 pages, 24 eps figures

Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

We compute the next-to-leading order corrections of $O(\alpha_s^2\alpha^3)$ to the hadronic production of two oppositely charged leptons and two hard jets, $p p \to j j l^- l^+$, using Recola and Collier. We include electroweak and QCD corrections at the given order and all off-shell effects. We provide detailed predictions for the LHC operating at 13 TeV and obtain per-cent-level corrections for the total cross section. For differential distributions we find significant non-uniform distortions in high-energy tails at the level of several ten per cent due to electroweak Sudakov logarithms and deformations at the level of a few per cent for angular variables.

[25]  arXiv:1411.0922 [pdf, other]

Title: QCD uncertainties in the prediction of B --> K^* mu^+ mu^- observables

Authors: Sébastien Descotes-Genon, Lars Hofer, Joaquim Matias, Javier Virto

Comments: 6 pages, 3 figures

Subjects: High Energy Physics - Phenomenology (hep-ph)

The recent LHCb angular analysis of the exclusive decay B --> K^* mu^+ mu^- has indicated significant deviations from the Standard Model expectations. In order to give precise theory predictions, it is crucial that uncertainties from non-perturbative QCD are under control and properly included. The dominant QCD uncertainties originate from the hadronic B --> K^* form factors and from charm loops. We present a systematic method to include factorisable power corrections to the form factors in the framework of QCD factorisation and study the impact of the scheme chosen to define the soft form factors. We also discuss charm-loop effects.

[26]  arXiv:1411.0994 [pdf, ps, other]

Title: Numerical multi-loop calculations with the program SecDec

Authors: Sophia Borowka, Gudrun Heinrich

Comments: 9 pages, 5 figures; contribution to the proceedings of the conference ACAT 2014 (Advanced Computing and Analysis Techniques in physics), Prague, Czech Republic, September 2014

Subjects: High Energy Physics - Phenomenology (hep-ph)

SecDec is a program which can be used for the evaluation of parametric integrals, in particular multi-loop integrals. For a given set of propagators defining the graph, the program constructs the graph polynomials, factorizes the endpoint singularities, and finally produces a Laurent series in the dimensional regularization parameter, whose coefficients are evaluated numerically. In this talk we discuss various features of the program, which extend the range of applicability. We also present a recent phenomenological example of an application entering the momentum dependent two-loop corrections to neutral Higgs boson masses in the MSSM.

Cross-lists for Wed, 5 Nov 14

[27]  arXiv:1411.0620 (cross-list from gr-qc) [pdf, ps, other]

Title: Classical, quantum, and phenomenological aspects of dark energy models

Authors: Houri Ziaeepour

Comments: 49 pages, 14 figures; Review based on one of chapters of the author's "Habilitation \`a Diriger des Recherches (H.D.R.)" memoir

Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.C