Scrutinizing the ZW+W- vertex at the Large Hadron Collider at 7 TeV

We analyze the potential of the CERN Large Hadron Collider running at 7 TeV to search for deviations from the Standard Model predictions for the triple gauge boson coupling ZW+W- assuming an integrated luminosity of 1 fb^{-1}. We show that the study of W+W- and W^\pm Z productions, followed by the leptonic decay of the weak gauge bosons can improve the present sensitivity on the anomalous couplings \Delta g_1^Z, \Delta \kappa_Z, \lambda_Z, g_4^Z, and \tilde{\lambda}_Z at the 2\sigma level.Comment: 12 pages, 3 figures. One reference added, matches published versio

Quartic Anomalous Couplings in eγe\gamma Colliders

We study the production of gauge boson pairs at the next generation of linear $e^+e^-$ colliders operating in the $e\gamma$ mode. The processes $e\gamma \rightarrow VV^\prime F$ ($V,V^\prime =W$, $Z$, or $\gamma$ and $F=e$ or $\nu$) can give valuable information on possible deviations of the quartic vector boson couplings from the Standard Model predictions. We establish the range of the new couplings that can be explored in these colliders based on a $3\sigma$ effect in the total cross section. We also present several kinematical distributions of the final state particles that could manifest the underlying new dynamics. Our results show that an $e\gamma$ collider can extend considerably the bounds on anomalous interactions coming from oblique radiative corrections and from direct searches in $e^+e^-$ colliders.Comment: 21 pages and 7 figures appended as a postscript file (uuencoded), MAD/PH/764, IFT-P.031/93, IFUSP-P 1047 (uses REVTeX3

Superprocesses as models for information dissemination in the Future Internet

Future Internet will be composed by a tremendous number of potentially interconnected people and devices, offering a variety of services, applications and communication opportunities. In particular, short-range wireless communications, which are available on almost all portable devices, will enable the formation of the largest cloud of interconnected, smart computing devices mankind has ever dreamed about: the Proximate Internet. In this paper, we consider superprocesses, more specifically super Brownian motion, as a suitable mathematical model to analyse a basic problem of information dissemination arising in the context of Proximate Internet. The proposed model provides a promising analytical framework to both study theoretical properties related to the information dissemination process and to devise efficient and reliable simulation schemes for very large systems

Percolation and high energy cosmic rays above 101710^{17} eV

In this work we argue that, in the interpretation of the energy dependence of the depth of the shower maximum and of the muon content in high energy cosmic ray showers ($E > 10^{17}$ eV), other variables besides the composition may play an important role, in particular those characterising the first (high energy) hadronic collisions. The role of the inelasticity, of the nature of the leading particle, and of the particle multiplicity are discussed. A consistent interpretation of existing data within a string percolation model implemented in a hybrid, one dimensional simulation method is given.Comment: 15 pages, 6 eps figure

Constraints on Quartic Vector-Boson Interactions from Z Physics

We obtain the constraints on possible anomalous quartic vector-boson vertices arising from the precision measurements at the $Z$ pole. In the framework of $SU(2)_L \otimes U(1)_Y$ chiral Lagrangians, we examine all effective operators of order $D=4$ that lead to four-gauge-boson interactions but do not induce anomalous trilinear vertices. We constrain the anomalous quartic interactions by evaluating their one-loop corrections to the $Z$ pole physics. Our analysis is performed in a generic $R_\xi$ gauge and it shows that only the operators that break the $SU(2)_C$ custodial symmetry get limits close to the theoretical expectations. Our results also indicate that these anomalous couplings are already out of reach of the Next Linear $e^+ e^-$ Collider, while the Large Hadron Collider could be able to further extend the bounds on some of these couplings.Comment: 16 pages, 1 Postscript figures, uses RevTex and eps.st

Non-autonomous stochastic evolution equations and applications to stochastic partial differential equations

In this paper we study the following non-autonomous stochastic evolution equation on a UMD Banach space $E$ with type 2, {equation}\label{eq:SEab}\tag{SE} {{aligned} dU(t) & = (A(t)U(t) + F(t,U(t))) dt + B(t,U(t)) dW_H(t), \quad t\in [0,T], U(0) & = u_0. {aligned}. {equation} Here $(A(t))_{t\in [0,T]}$ are unbounded operators with domains $(D(A(t)))_{t\in [0,T]}$ which may be time dependent. We assume that $(A(t))_{t\in [0,T]}$ satisfies the conditions of Acquistapace and Terreni. The functions $F$ and $B$ are nonlinear functions defined on certain interpolation spaces and $u_0\in E$ is the initial value. $W_H$ is a cylindrical Brownian motion on a separable Hilbert space $H$. Under Lipschitz and linear growth conditions we show that there exists a unique mild solution of \eqref{eq:SEab}. Under assumptions on the interpolation spaces we extend the factorization method of Da Prato, Kwapie\'n, and Zabczyk, to obtain space-time regularity results for the solution $U$ of \eqref{eq:SEab}. For Hilbert spaces $E$ we obtain a maximal regularity result. The results improve several previous results from the literature. The theory is applied to a second order stochastic partial differential equation which has been studied by Sanz-Sol\'e and Vuillermot. This leads to several improvements of their result.Comment: Accepted for publication in Journal of Evolution Equation

Neutrino masses in R-parity violating supersymmetric models

We study neutrino masses and mixing in R-parity violating supersymmetric models with generic soft supersymmetry breaking terms. Neutrinos acquire masses from various sources: Tree level neutrino--neutralino mixing and loop effects proportional to bilinear and/or trilinear R-parity violating parameters. Each of these contributions is controlled by different parameters and have different suppression or enhancement factors which we identified. Within an Abelian horizontal symmetry framework these factors are related and specific predictions can be made. We found that the main contributions to the neutrino masses are from the tree level and the bilinear loops and that the observed neutrino data can be accommodated once mild fine-tuning is allowed.Comment: 18 pages; minor typos corrected. To be published in Physical Review

Implicit media frames: Automated analysis of public debate on artificial sweeteners

The framing of issues in the mass media plays a crucial role in the public understanding of science and technology. This article contributes to research concerned with diachronic analysis of media frames by making an analytical distinction between implicit and explicit media frames, and by introducing an automated method for analysing diachronic changes of implicit frames. In particular, we apply a semantic maps method to a case study on the newspaper debate about artificial sweeteners, published in The New York Times (NYT) between 1980 and 2006. Our results show that the analysis of semantic changes enables us to filter out the dynamics of implicit frames, and to detect emerging metaphors in public debates. Theoretically, we discuss the relation between implicit frames in public debates and codification of information in scientific discourses, and suggest further avenues for research interested in the automated analysis of frame changes and trends in public debates

Reexamining nonstandard interaction effects on supernova neutrino flavor oscillations

Several extensions of the standard electroweak model allow new four-fermion interactions (nu_a nu_b * ff) with strength eps_ab*G_F, where (a,b) are flavor indices. We revisit their effects on flavor oscillations of massive (anti)neutrinos in supernovae, in order to achieve, in the region above the protoneutron star, an analytical treatment valid for generic values of the neutrino mixing angles (omega,phi,psi)=(theta_12,theta_13,theta_23). Assuming that eps_ab<<1, we find that the leading effects on the flavor transitions occurring at high (H) and low (L) density along the supernova matter profile can be simply embedded through the replacements phi-->phi+eps_H and omega-->omega+eps_L, respectively, where eps_H and eps_L are specific linear combinations of the eps_ab's. Similar replacements hold for eventual oscillations in the Earth matter. From a phenomenological point of view, the most relevant consequence is a possible uncontrolled bias (phi-->phi+eps_H) in the value of the mixing angle phi inferred by inversion of supernova neutrino data. Such a drawback, however, does not preclude the discrimination of the neutrino mass spectrum hierarchy (direct or inverse) through supernova neutrino oscillations.Comment: Text clarified, one figure added. To appear in PR

Single Top Production as a Window to Physics Beyond the Standard Model

Production of single top quarks at a high energy hadron collider is studied as a means to identify physics beyond the standard model related to the electroweak symmetry breaking. The sensitivity of the $s$-channel $W^*$ mode, the $t$-channel $W$-gluon fusion mode, and the \tw mode to various possible forms of new physics is assessed, and it is found that the three modes are sensitive to different forms of new physics, indicating that they provide complimentary information about the properties of the top quark. Polarization observables are also considered, and found to provide potentially useful information about the structure of the interactions of top.Comment: References added and minor discussion improvements; results unchanged; Version to be published in PR