Effective field theories for heavy quarkonium

We review recent theoretical developments in heavy quarkonium physics from the point of view of Effective Field Theories of QCD. We discuss Non-Relativistic QCD and concentrate on potential Non-Relativistic QCD. Our main goal will be to derive QCD Schr\"odinger-like equations that govern the heavy quarkonium physics in the weak and strong coupling regime. We also discuss a selected set of applications, which include spectroscopy, inclusive decays and electromagnetic threshold production.Comment: 162 pages, 30 figures, revised version, references added. Accepted for publication in Reviews of Modern Physic

Renormalization group improvement of the spectrum of Hydrogen-like atoms with massless fermions

We obtain the next-to-next-to-leading-log renormalization group improvement of the spectrum of Hydrogen-like atoms with massless fermions by using potential NRQED. These results can also be applied to the computation of the muonic Hydrogen spectrum where we are able to reproduce some known double logs at O(m\alpha^6). We compare with other formalisms dealing with log resummation available in the literature.Comment: 9 pages, LaTeX. Minor changes, note added, final versio

Preparing the bound instance of quantum entanglement

Among the possibly most intriguing aspects of quantum entanglement is that it comes in "free" and "bound" instances. Bound entangled states require entangled states in preparation but, once realized, no free entanglement and therefore no pure maximally entangled pairs can be regained. Their existence hence certifies an intrinsic irreversibility of entanglement in nature and suggests a connection with thermodynamics. In this work, we present a first experimental unconditional preparation and detection of a bound entangled state of light. We consider continuous-variable entanglement, use convex optimization to identify regimes rendering its bound character well certifiable, and realize an experiment that continuously produced a distributed bound entangled state with an extraordinary and unprecedented significance of more than ten standard deviations away from both separability and distillability. Our results show that the approach chosen allows for the efficient and precise preparation of multimode entangled states of light with various applications in quantum information, quantum state engineering and high precision metrology.Comment: The final version accounts for a recent comment in Nature Physics [24] clarifying that a previous claim of having generated bound entanglement [23] was not supported by the authors' data. We also extended our introduction and discussion and also added reference

Renormalization group improvement of the NRQCD Lagrangian and heavy quarkonium spectrum

We complete the leading-log renormalization group scaling of the NRQCD Lagrangian at $O(1/m^2)$. The next-to-next-to-leading-log renormalization group scaling of the potential NRQCD Lagrangian (as far as the singlet is concerned) is also obtained in the situation $m\alpha_s \gg \Lambda_{QCD}$. As a by-product, we obtain the heavy quarkonium spectrum with the same accuracy in the situation m\alpha_s^2 \simg \Lambda_{QCD}. When $\Lambda_{QCD} \ll m\alpha_s^2$, this is equivalent to obtain the whole set of $O(m\alpha_s^{(n+4)} \ln^n \alpha_s)$ terms in the heavy quarkonium spectrum. The implications of our results in the non-perturbative situation $m\alpha_s \sim \Lambda_{QCD}$ are also mentioned.Comment: 16 pages, LaTeX. Minor changes. Final versio

Travel Time Savings Perception and Well-Being through Public Transport Projects: The Case of Metro de Santiago

Relying mostly on travel time savings, cost-benefit analysis has been widely used in transport project appraisals in the Chilean context, with utility maximisation theory as its background. Nevertheless, subjective well-being advocates have challenged the notion of the rational man underlying this theory by proposing that other trip attributes, individual perceptions and personal features mediate satisfaction with travel, alongside global well-being. Using the recently-opened Line 6 of Metro de Santiago (Chile) as a case study, this research has two main aims: (1) to verify to what extent travel time savings, which support the cost-benefit analysis process, are present after the launching of the new line; and (2) analyse the perception of passengers’ travel time savings, and to what extent this element contributes to the travel satisfaction and to the global well-being at the individual level. Using passive data from smart cards, the results show that travel times decreased by 14% in comparable trips after the launching of Line 6. Furthermore, a confirmatory factor analysis (CFA) construct is proposed, including travel and life satisfaction as latent variables of the model. This revealed that travel times in the Metro system are highly valued by people. However, this element does not mediate travel satisfaction, as users take low travel times for granted. Waiting times, stations’ design, safety and intermodality are perceived attributes that effectively mediate travel satisfaction. Moreover, the latter variable has a relevant influence on global life satisfaction, revealing that transport conditions mediate in day-to-day well-being. These results challenged travel time savings as the most important driver in transport projects’ appraisal processes, and some recommendations are made in order to incorporate these findings in future appraisals

More nonperturbative corrections to the fine and hyperfine splitting in the heavy quarkonium

The leading nonperturbative effects to the fine and hyperfine splitting were calculated some time ago. Recently, they have been used in order to obtain realistic numerical results for the lower levels in bottomonium systems. We point out that a contribution of the same order $O(\Lambda_{QCD}^4/m^3 \alpha_s^2)$ has been overlooked. We calculate it in this paper.Comment: 9 pages, LaTeX, More self-contained and lengthier version without changing physical outputs. To be published in Phys. Rev.