New look at the QCD ground state in a magnetic field

We explore chiral symmetry breaking in a magnetic field within a Nambu-Jona-Lasinio model of interacting massless quarks including tensor channels. We show that the new interaction channels open up via Fierz identities due to the explicit breaking of the rotational symmetry by the magnetic field. We demonstrate that the magnetic catalysis of chiral symmetry breaking leads to the generation of two independent condensates, the conventional chiral condensate and a spin-one condensate. While the chiral condensate generates a dynamical fermion mass, the new condensate gives rise to a dynamical anomalous magnetic moment for the fermions. As a consequence, the spectrum of the excitations in all Landau levels, except the lowest one, exhibits Zeeman splitting. Since the pair, formed by a quark and an antiquark with opposite spins, possesses a resultant magnetic moment, an external magnetic field can align it giving rise to a net magnetic moment for the ground state. This is the physical interpretation of the spin-one condensate. Our results show that the magnetically catalyzed ground state in QCD is actually richer than previously thought. The two condensates contribute to the effective mass of the LLL quasiparticles in such a way that the critical temperature for chiral symmetry restoration becomes enhanced.Comment: PRD version with updated Reference

Guidelines for Operationalizing Policy Coherence for Development (PCD) as a Methodology for the Design and Implementation of Sustainable Development Strategies

Policy Coherence for Development (PCD) is considered a pillar of the 2030 Sustainable Development Agenda. It aims to promote whole of government approaches to sustainable development. Despite its prominence in development cooperation discussions, many national development professionals or stakeholders have not heard of PCD, indicating that its effectiveness is significantly limited. This article contends that the impact of PCD has not been maximized because it has been presented as a political objective or a policy tool by multilateral organizations and their member states. Instead, the article argues that PCD should be implemented as a methodology that can be adopted by domestic government and non-governmental actors alike, in order to understand trade-offs and co-benefits within and between policy sectors, thus promoting a participative approach. I-GAMMA is a research project in Mexico that examines data-driven public policy in order to promote PCD. It is based on in-depth reviews of policy documents and interviews with development actors. It is committed to open data, evidence-based policymaking, and collaborative dialogue between academics, government officials, and representatives of civil society organizations in sustainable development discussions. In the results section of this article, the project proposes participative PCD as a methodology for policy analysis through which a plurality of actors can identify mechanisms that either reinforce or undermine sustainable development strategies. This section then applies the methodology to the governance of protected natural areas in Mexico. The discussion section and the conclusions highlight the relevance of this approach for participative policymaking in sustainable development

Lack of Debye and Meissner Screening in Strongly Magnetized Quark Matter at Intermediate Densities

We study the static responses of cold quark matter in the intermediate baryonic density region (characterized by a chemical potential μ) in the presence of a strong-magnetic field. We consider in particular, the so-called magnetic dual Chiral Density Wave (MDCDW) phase, which is materialized by an inhomogeneous condensate formed by a particle-hole pair. It is shown, that the MDCDW phase is more stable in the weak-coupling regime than the one considered in the magnetic catalysis of chiral symmetry braking phenomenon and even than the chiral symmetric phase that was expected to be realized at sufficiently high baryonic chemical potential. The different components of the photon polarization operator of the MDCDW phase in the one-loop approximation are calculated. We found that in the MDCDW phase there is neither Debye screening nor Meissner effect in the lowest-Landau-level approximation. The obtained Debye length depends on the amplitude m and modulation b of the inhomogeneous condensate and it is only different from zero if the relation |μ−b|\u3em holds. But, we found that in the region of interest this inequality is not satisfied. Thus, no Debye screening takes place under those conditions. On the other hand, since the particle-hole condensate is electrically neutral, the U(1) electromagnetic group is not broken by the ground state and consequently there is no Meissner effect. These results can be of interest for the astrophysics of neutron stars