Isolating the Roper Resonance in Lattice QCD

We present results for the first positive parity excited state of the nucleon, namely, the Roper resonance ($N^{{{1/2}}^{+}}$=1440 MeV) from a variational analysis technique. The analysis is performed for pion masses as low as 224 MeV in quenched QCD with the FLIC fermion action. A wide variety of smeared-smeared correlation functions are used to construct correlation matrices. This is done in order to find a suitable basis of operators for the variational analysis such that eigenstates of the QCD Hamiltonian may be isolated. A lower lying Roper state is observed that approaches the physical Roper state. To the best of our knowledge, the first time this state has been identified at light quark masses using a variational approach.Comment: 7pp, 4 figures; minor typos corrected and one Ref. adde

The DNDN, πΣc\pi \Sigma_c interaction in finite volume and the Λc(2595)\Lambda_c(2595) resonance

In this work the interaction of the coupled channels $DN$ and $\pi \Sigma_c$ in an SU(4) extrapolation of the chiral unitary theory, where the $\Lambda_c(2595)$ resonance appears as dynamically generated from that interaction, is extended to produce results in finite volume. Energy levels in the finite box are evaluated and, assuming that they would correspond to lattice results, the inverse problem of determining the phase shifts in the infinite volume from the lattice results is solved. We observe that it is possible to obtain accurate $\pi \Sigma_c$ phase shifts and the position of the $\Lambda_c(2595)$ resonance, but it requires the explicit consideration of the two coupled channels. We also observe that some of the energy levels in the box are attached to the closed $DN$ channel, such that their use to induce the $\pi \Sigma_c$ phase shifts via L\"uscher's formula leads to incorrect results.Comment: 10 pages, 13 figures, accepted for publication in Eur. Phys. J.

Scalar mesons moving in a finite volume and the role of partial wave mixing

Phase shifts and resonance parameters can be obtained from finite-volume lattice spectra for interacting pairs of particles, moving with nonzero total momentum. We present a simple derivation of the method that is subsequently applied to obtain the pi pi and pi K phase shifts in the sectors with total isospin I=0 and I=1/2, respectively. Considering different total momenta, one obtains extra data points for a given volume that allow for a very efficient extraction of the resonance parameters in the infinite-volume limit. Corrections due to the mixing of partial waves are provided. We expect that our results will help to optimize the strategies in lattice simulations, which aim at an accurate determination of the scattering and resonance properties.Comment: 19 pages, 12 figure

Investigation of \mth{\alpha}-nucleus interaction in the \chem{^{27}Al(\alpha,\alpha)^{27}Al} scattering and \chem{^{27}Al(\alpha,d)^{29}Si} reaction

Full finite-range macroscopic calculations in the distorted-wave Born approximation have been performed using the molecular and Michel $\alpha$-nucleus potentials to analyze the angular distributions of cross-sections of the $^{27}$Al($\alpha,d$)$^{29}$Si reaction, at 26.5 and 27.2 MeV incident energies, leading to seven transitions up to the excitation energy $E_{\rm X} = 4.08$ MeV of the final nucleus. The parameters of the two types of the $\alpha$-nucleus potentials are determined from the elastic-scattering data. Both the molecular and Michel potentials, without any adjustment to the parameters needed to fit the elastic-scattering data, are able in most cases to reproduce, simultaneously, the absolute cross-sections particularly at large angles, where the previous calculations failed to reproduce by orders of magnitude, and the gross pattern of angular distributions of the reaction. The deuteron-cluster spectroscopic factors for most of the seven transitions, deduced using the two $\alpha$-$^{27}$Al potentials, differ from those obtained in earlier works. The spectroscopic factor for the ground-state transition, deduced in the present work for the 25.8 MeV data, agrees well with the shell model prediction

IL-33 expression is lower in current smokers at both transcriptomic and protein level

INTRODUCTION: IL-33 is a pro-inflammatory cytokine thought to play a role in the pathogenesis of asthma and COPD. A recent clinical trial using the anti-IL33 antibody showed a reduction in exacerbation and improved lung function in ex-smokers but not current smokers with COPD. In this study, we aimed to understand the effects of smoking status on IL-33. METHODS: We investigated the association of smoking status with the level of gene expression of IL33 in the airways in eight independent transcriptomic studies of lung airways. Additionally, we performed western blot and immunohistochemistry for IL-33 in lung tissue to assess protein levels. RESULTS: Across the bulk RNA-sequencing datasets, IL-33 gene expression and its signaling pathway were significantly lower in current- compared to ex- or never-smokers and increased upon smoking cessation (p<0.05). Single-cell sequencing showed that IL-33 is predominantly expressed in resting basal epithelial cells and decreases during the differentiation process triggered by smoke exposure. We also found a higher transitioning of this cellular sub-population into a more differentiated cell type during chronic smoking, potentially driving the reduction of IL-33. Protein analysis demonstrated lower IL-33 levels in lung tissue from COPD current- compared to ex-smokers and a lower proportion of IL-33 positive basal cells in current versus ex-smoking controls. CONCLUSION: We provide strong evidence that cigarette smoke leads to an overall reduction in IL33 expression in both transcriptomic and protein level and this may be due to the decrease in resting basal cells. Together, these findings may explain the clinical observation that a recent antibody-based anti-IL-33 treatment is more effective in ex- than current smokers with COPD

On the ambiguities of sign determination of the S-matrix from energy levels in a finite box

In a recent paper the authors make a study on the determination of the S-matrix elements for scattering of particles in the infinite volume from the energy levels in a finite box for the case of multiple channels. The study is done with a toy model in 1+1 dimension and the authors find that there is some ambiguity in the sign of nondiagonal matrix elements, casting doubts on whether the needed observables in the infinite volume can be obtained from the energy levels of the box. In this paper I present an easy derivation, confirming the ambiguity of the sign and argue that this, however, does not put restrictions in the determination of observables