Two-center resonant photo ionization

Photoionization of an atom $A$, in the presence of a neighboring atom $B$, can proceed via resonant excitation of $B$ with subsequent energy transfer to $A$ through two-center electron-electron correlation. We demonstrate that this two-center mechanism can strongly outperform direct photoionization at nanometer internuclear distances and possesses characteristic features in its time development and the spectrum of emitted electrons.Comment: 4 pages, 3 figure

Solution to Faddeev equations with two-body experimental amplitudes as input and application to J^P=1/2^+, S=0 baryon resonances

We solve the Faddeev equations for the two meson-one baryon system $\pi\pi N$ and coupled channels using the experimental two-body $t$-matrices for the $\pi N$ interaction as input and unitary chiral dynamics to describe the interaction between the rest of coupled channels. In addition to the $N^*(1710)$ obtained before with the $\pi\pi N$ channel, we obtain, for $J^\pi=1/2^+$ and total isospin of the three-body system $I=1/2$, a resonance peak whose mass is around 2080 MeV and width of 54 MeV, while for $I=3/2$ we find a peak around 2126 MeV and 42 MeV of width. These two resonances can be identified with the $N^* (2100)$ and the $\Delta (1910)$, respectively. We obtain another peak in the isospin 1/2 configuration, around 1920 MeV which can be interpreted as a resonance in the $N a_0(980)$ and $N f_0(980)$ systems.Comment: published versio

Faddeev fixed-center approximation to the NKˉKN\bar{K}K system and the signature of a N∗(1920)(1/2+)N^*(1920)(1/2^+) state

We perform a calculation for the three body $N \bar{K} K$ scattering amplitude by using the fixed center approximation to the Faddeev equations, taking the interaction between $N$ and $\bar{K}$, $N$ and $K$, and $\bar{K}$ and $K$ from the chiral unitary approach. The resonant structures show up in the modulus squared of the three body scattering amplitude and suggest that a $N\bar{K}K$ hadron state can be formed. Our results are in agreement with others obtained in previous theoretical works, which claim a new $N^*$ resonance around 1920 MeV with spin-parity $J^P=1/2^+$. The existence of these previous works allows us to test the accuracy of the fixed center approximation in the present problem and sets the grounds for possible application in similar problems, as an explorative tool to determine bound or quasibound three hadron systems.Comment: Published versio

One-Nucleon Effective Generators of the Poincare Group derived from a Field Theory: Mass Renormalization

We start from a Lagrangian describing scalar "nucleons" and mesons which interact through a simple vertex. Okubo's method of unitary transformation is used to describe a single nucleon dressed by its meson cloud. We find an expression for the physical mass of the nucleon being correct up to second order in the coupling constant. It is then verified that this result is the same as the corresponding expression found by Feynman techniques. Finally we also express the three boost operators in terms of the physical nucleon mass. Doing so we find expressions for all the ten generators of Poincar\'e transformations for the system of one single dressed nucleon.Comment: 19 pages, no figure

The s-wave pion-nucleus optical potential

We calculate the s-wave part of the pion-nucleus optical potential using a unitarized chiral approach that has been previously used to simultaneously describe pionic hydrogen and deuterium data as well as low energy pi N scattering in the vacuum. This energy dependent model allows for additional isoscalar parts in the potential from multiple rescattering. We consider Pauli blocking and pion polarization in an asymmetric nuclear matter environment. Also, higher order corrections of the pi N amplitude are included. The model can accommodate the repulsion required by phenomenological fits, though the theoretical uncertainties are bigger than previously thought. At the same time, we also find an enhancement of the isovector part compatible with empirical determinations.Comment: 31 pages, 27 figure

Local Electronic Correlation at the Two-Particle Level

Electronic correlated systems are often well described by dynamical mean field theory (DMFT). While DMFT studies have mainly focused hitherto on one-particle properties, valuable information is also enclosed into local two-particle Green's functions and vertices. They represent the main ingredient to compute momentum-dependent response functions at the DMFT level and to treat non-local spatial correlations at all length scales by means of diagrammatic extensions of DMFT. The aim of this paper is to present a DMFT analysis of the local reducible and irreducible two-particle vertex functions for the Hubbard model in the context of an unified diagrammatic formalism. An interpretation of the observed frequency structures is also given in terms of perturbation theory, of the comparison with the atomic limit, and of the mapping onto the attractive Hubbard model.Comment: 29 pages, 26 Figures. Accepted for publication in Phys. Rev.

Entanglement in bosonic systems

We present a technique to resolve a Gaussian density matrix and its time evolution through known expectation values in position and momentum. Further we find the full spectrum of this density matrix and apply the technique to a chain of harmonic oscillators to find agreement with conformal field theory in this domain. We also observe that a non-conformal state has a divergent entanglement entropy.Comment: 7 pages, 6 figure

Surveillance of medication use: early identification of poor adherence

Background: We sought to measure population-level adherence to antihyperlipidemics, antihypertensives, and oral hypoglycemics, and to develop a model for early identification of subjects at high risk of long-term poor adherence. Methods Prescription-filling data for 2 million subjects derived from a payor's insurance claims were used to evaluate adherence to three chronic drugs over 1 year. We relied on patterns of prescription fills, including the length of gaps in medication possession, to measure adherence among subjects and to build models for predicting poor long-term adherence. Results: All prescription fills for a specific drug were sequenced chronologically into drug eras. 61.3% to 66.5% of the prescription patterns contained medication gaps >30 days during the first year of drug use. These interrupted drug eras include long-term discontinuations, where the subject never again filled a prescription for any drug in that category in the dataset, which represent 23.7% to 29.1% of all drug eras. Among the prescription-filling patterns without large medication gaps, 0.8% to 1.3% exhibited long-term poor adherence. Our models identified these subjects as early as 60 days after the first prescription fill, with an area under the curve (AUC) of 0.81. Model performance improved as the predictions were made at later time-points, with AUC values increasing to 0.93 at the 120-day time-point. Conclusions: Dispensed medication histories (widely available in real time) are useful for alerting providers about poorly adherent patients and those who will be non-adherent several months later. Efforts to use these data in point of care and decision support facilitating patient are warranted

A description of the f2(1270), rho3(1690), f4(2050), rho5(2350) and f6(2510) resonances as multi-rho(770) states

In a previous work regarding the interaction of two $\rho(770)$ resonances, the $f_2(1270)$ ($J^{PC}=2^{++}$) resonance was obtained dynamically as a two-$\rho$ molecule with a very strong binding energy, 135~MeV per $\rho$ particle. In the present work we use the $\rho\rho$ interaction in spin 2 and isospin 0 channel to show that the resonances $\rho_3(1690)$ ($3^{--}$), $f_4(2050)$ ($4^{++}$), $\rho_5(2350)$ ($5^{--}$) and $f_6(2510)$ ($6^{++}$) are basically molecules of increasing number of $\rho(770)$ particles. We use the fixed center approximation of the Faddeev equations to write the multi-body interaction in terms of the two-body scattering amplitudes. We find the masses of the states very close to the experimental values and we get an increasing value of the binding energy per $\rho$ as the number of $\rho$ mesons is increased.Comment: 17 pages, 6 figure

Density operators that extremize Tsallis entropy and thermal stability effects

Quite general, analytical (both exact and approximate) forms for discrete probability distributions (PD's) that maximize Tsallis entropy for a fixed variance are here investigated. They apply, for instance, in a wide variety of scenarios in which the system is characterized by a series of discrete eigenstates of the Hamiltonian. Using these discrete PD's as "weights" leads to density operators of a rather general character. The present study allows one to vividly exhibit the effects of non-extensivity. Varying Tsallis' non-extensivity index $q$ one is seen to pass from unstable to stable systems and even to unphysical situations of infinite energy.Comment: 22 page