Albaladejo, M., Guo, F. K., Hanhart, C., Meissner, U. G., Nieves, J., Nogga, A., et al. (2017). Note on X(3872) production at hadron colliders and its molecular structure. Chin. Phys. C, 41(12), 121001–3pp.
Abstract: The production of the X (3872) as a hadronic molecule in hadron colliders is clarified. We show that the conclusion of Bignamini et al., Phys. Rev. Lett. 103 (2009) 162001, that the production of the X(3872) at high pT implies a non-molecular structure, does not hold. In particular, using the well understood properties of the deuteron wave function as an example, we identify the relevant scales in the production process.
|
Nieves, J., & Sobczyk, J. E. (2017). In medium dispersion relation effects in nuclear inclusive reactions at intermediate and low energies. Ann. Phys., 383, 455–496.
Abstract: In a well-established many-body framework, successful in modeling a great variety of nuclear processes, we analyze the role of the spectral functions (SFs) accounting for the modifications of the dispersion relation of nucleons embedded in a nuclear medium. We concentrate in processes mostly governed by one-body mechanisms, and study possible approximations to evaluate the particle hole propagator using SFs. We also investigate how to include together SFs and long-range RPA-correlation corrections in the evaluation of nuclear response functions, discussing the existing interplay between both type of nuclear effects. At low energy transfers (<= 50 MeV), we compare our predictions for inclusive muon and radiative pion captures in nuclei, and charge-current (CC) neutrino-nucleus cross sections with experimental results. We also present an analysis of intermediate energy quasi-elastic neutrino scattering for various targets and both neutrino and antineutrino CC driven processes. In all cases, we pay special attention to estimate the uncertainties affecting the theoretical predictions. In particular, we show that errors on the a,,sigma(mu)/sigma(e) ratio are much smaller than 5%, and also much smaller than the size of the SF+RPA nuclear corrections, which produce significant effects, not only in the individual cross sections, but also in their ratio for neutrino energies below 400 MeV. These latter nuclear corrections, beyond Pauli blocking, turn out to be thus essential to achieve a correct theoretical understanding of this ratio of cross sections of interest for appearance neutrino oscillation experiments. We also briefly compare our SF and RPA results to predictions obtained within other representative approaches.
|
Rocco, N., Alvarez-Ruso, L., Lovato, A., & Nieves, J. (2017). Electromagnetic scaling functions within the Green's function Monte Carlo approach. Phys. Rev. C, 96(1), 015504–12pp.
Abstract: We have studied the scaling properties of the electromagnetic response functions of He-4 and C-12 nuclei computed by the Green's function Monte Carlo approach, retaining only the one-body current contribution. Longitudinal and transverse scaling functions have been obtained in the relativistic and nonrelativistic cases and compared to experiment for various kinematics. The characteristic asymmetric shape of the scaling function exhibited by data emerges in the calculations in spite of the nonrelativistic nature of the model. The results are mostly consistent with scaling of zeroth, first, and second kinds. Our analysis reveals a direct correspondence between the scaling and the nucleon-density response functions. The scaling function obtained from the proton-density response displays scaling of the first kind, even more evidently than the longitudinal and transverse scaling functions.
|
Pavao, R. P., Liang, W. H., Nieves, J., & Oset, E. (2017). Predictions for Xi(-)(b) -> pi-(D-S(-)) Xi(0)(C) (2790) (Xi(0)(C)(2815) and Xi(-)(b) -> (v)over-bar (l)l Xi(0)(C)(2790) (Xi(0)(C)(2815). Eur. Phys. J. C, 77(4), 265–12pp.
Abstract: We have performed calculations for the non-leptonic Xi(-)(b) -> pi-(D-S(-)) Xi(0)(C) (2790)(J = 1/2) Xi(-)(b) -> pi(-) Xi(0)(C)(2815) (J = 3/2) and decays and the same reactions replacing the pi- by a D-s(-). At the same time we have also evaluated the semileptonic rates for and Xi(-)(b) -> pi-(D-S(-)) Xi(0)(C) (2790). We look at the reactions from the perspective that the Xi(0(2790))(c) and Xi(0)(c)(2815()) resonances are dynamically generated from the pseudoscalar-baryon and vector-baryon interactions. We evaluate ratios of the rates of these reactions and make predictions that can be tested in future experiments. We also find that the results are rather sensitive to the coupling of the Xi(c)* resonances to the D*Sigma and D*A components.
|
Albaladejo, M., Fernandez-Soler, P., Nieves, J., & Ortega, P. G. (2017). Lowest-lying even-parity (B)over-bar(s) mesons: heavy-quark spin-flavor symmetry, chiral dynamics, and constituent quark-model bare masses. Eur. Phys. J. C, 77(3), 170–9pp.
Abstract: The discovery of the D*(s0)(2317) and D-s1(2460) resonances in the charmed-strange meson spectra revealed that formerly successful constituent quark models lose predictability in the vicinity of two-meson thresholds. The emergence of non-negligible effects due to meson loops requires an explicit evaluation of the interplay between Q (q) over bar and (Q (q) over bar)(q (q) over bar) Fock components. In contrast to the c (s) over bar sector, there is no experimental evidence of J(P) = 0(+), 1(+) bottom-strange states yet. Motivated by recent lattice studies, in this work the heavy-quark partners of the D*(s0)(2317) and D-s1(2460) states are analyzed within a heavy meson chiral unitary scheme. As a novelty, the coupling between the constituent quark-model P-wave (B) over bar (s) scalar and axial mesons and the (B) over bar (()*()) K channels is incorporated employing an effective interaction, consistent with heavy-quark spin symmetry, constrained by the lattice energy levels.
|
