Dialogue or issue divergence in the political campaign?

We incorporate the media priming effects to explain how politicians can affect voters preferences on issues during the political campaign. We adapt well-known terms of international trade, such as absolute advantage and comparative advantage, to the context of parties' competition in political issues. We show that when either each party has an absolute advantage on a different issue or when parties have high comparative advantage on a different issue, the political campaign will consist of issue-emphasis divergence. However, when a party has an absolute advantage on both issues but the parties' comparative advantage is not high enough, the political campaign will consist of issue engagement or dialogue. Our results conciliate two separated theories concerning whether there must be dialogue or issue-emphasis divergence in the political campaign.political campaign, media priming, political issues, spatial model

Indicators of Electoral Victory

We study a two-party contest where candidates strategically allocate their campaign resources between two salient issues. We analyze to what extent the following indicators of a party's success predict the electoral victory: (1) the pre-campaign advantage, (2) the advantage on every salient issue, and (3) the advantage on campaign resources. We show that the electoral victory is guaranteed only when a party has a "sufficiently large" advantage on every salient issue. Otherwise no combination of these indicators ensures the electoral victory.Election campaign, salient issues, majority voting

The chiral logs of the K -> pi pi amplitude

I calculate the leading logarithmic contributions up to two-loop order of the octet part of the K -> pi pi amplitude. This sector of the weak chiral Lagrangian is believed to be the main source of the enhancement of the I=0 relative to the I=2 K -> pi pi amplitude, the so-called Delta I = 1/2 rule. I discuss the procedure of chiral extrapolations of lattice data specific to K -> pi pi decays and study the implication of the present calculation on these numerically. The latter reinforces the fact that one has to expect a large enhancement of the I=0 part of the amplitude due to re-scattering effects between the three mesons.Comment: 20 pages, 4 figures, uses axodra

An example of resonance saturation at one loop

We argue that the large-Nc expansion of QCD can be used to treat a Lagrangian of resonances in a perturbative way. As an illustration of this we compute the L_10 coupling of the Chiral Lagrangian by integrating out resonance fields at one loop. Given a Lagrangian and a renormalization scheme, this is how in principle one can answer in a concrete and unambiguous manner questions such as at what scale resonance saturation takes place.Comment: 9 pages, 5 figures. Enlarged discussion, results unchanged. To be published in Phys. Rev.

Sudden singularities in semiclassical gravity

It has been claimed in a recent paper \cite{bbfhd12} that sudden singularities will survive in semiclassical gravity. This issue is here carefully reviewed, pointing out that such conclusion, even if valid under some specific conditions, does not stand in other cases. An explicit example is studied in detail to support our statement, stemming from these other situations, that quantum effects may in fact drastically modify the behavior of sudden singularities.Comment: Accepted for publication in PR

The Inverse Amplitude Method in ππ\pi\pi Scattering in Chiral Perturbation Theory to Two Loops

The inverse amplitude method is used to unitarize the two loop $\pi\pi$ scattering amplitudes of SU(2) Chiral Perturbation Theory in the $I=0,J=0$, $I=1,J=1$ and $I=2,J=0$ channels. An error analysis in terms of the low energy one-loop parameters $\bar l_{1,2,3,4,}$ and existing experimental data is undertaken. A comparison to standard resonance saturation values for the two loop coefficients $\bar b_{1,2,3,4,5,6}$ is also carried out. Crossing violations are quantified and the convergence of the expansion is discussed.Comment: (Latex, epsfig) 30 pages, 13 figures, 8 table

Meson resonances, large N_c and chiral symmetry

We investigate the implications of large N_c and chiral symmetry for the mass spectra of meson resonances. Unlike for most other mesons, the mass matrix of the light scalars deviates strongly from its large-N_c limit. We discuss the possible assignments for the lightest scalar nonet that survives in the large-N_c limit.Comment: 14 page

πK\pi K Scattering in Three Flavour ChPT

We present the scattering lengths for the $\pi K$ processes in the three flavour Chiral Perturbation Theory (ChPT) framework at next-to-next-to-leading order (NNLO). The calculation has been performed analytically but we only include analytical results for the dependence on the low-energy constants (LECs) at NNLO due to the size of the expressions. These results, together with resonance estimates of the NNLO LECs are used to obtain constraints on the Zweig rule suppressed LECs at NLO, $L_4^r$ and $L_6^r$. Contrary to expectations from NLO order calculations we find them to be compatible with zero. We do a preliminary study of combining the results from $\pi\pi$ scattering, $\pi K$ scattering and the scalar form-factors and find only a marginal compatibility with all experimental/dispersive input data.Comment: 23 page

Scalar meson dynamics in Chiral Perturbation Theory

A comparison of the linear sigma model (L$\sigma$M) and Chiral Perturbation Theory (ChPT) predictions for pion and kaon dynamics is presented. Lowest and next-to-leading order terms in the ChPT amplitudes are reproduced if one restricts to scalar resonance exchange. Some low energy constants of the order $p^4$ ChPT Lagrangian are fixed in terms of scalar meson masses. Present values of these low energy constants are compatible with the L$\sigma$M dynamics. We conclude that more accurate values would be most useful either to falsify the L$\sigma$M or to show its capability to shed some light on the controversial scalar physics.Comment: 9 pages, REVTeX 4.0. Final version accepted for publicatio

Integrating out strange quarks in ChPT

We study three flavour chiral perturbation theory in a limit where the strange quark mass is much larger than the external momenta and the up and down quark masses, and where the external fields are those of two-flavour chiral perturbation theory. In this case, the theory reduces to the one of SU(2)_L x SU(2)_R. Through this reduction, one can work out the strange quark mass dependence of the LECs in the two-flavour case. We present the pertinent relations at two-loop order for F,B and l_i.Comment: 14 pages, 3 figures, References added. Due to a typo in a form program, we missed a finite, scale independent part in l_7. Is now included. Version to appear in Phys.Lett.