J/ψJ/\psi production and suppression in high energy proton-nucleus collisions

We apply a Color Glass Condensate+Non-Relativistic QCD (CGC+NRQCD) framework to compute $J/\psi$ production in deuteron-nucleus collisions at RHIC and proton-nucleus collisions at the LHC. Our results match smoothly at high $p_\perp$ to a next-to-leading order perturbative QCD + NRQCD computation. Excellent agreement is obtained for $p_\perp$ spectra at RHIC and LHC for central and forward rapidities, as well as for the normalized ratio $R_{pA}$ of these results to spectra in proton-proton collisions. In particular, we observe that the $R_{pA}$ data is strongly bounded by our computations of the same for each of the individual NRQCD channels; this result provides strong evidence that our description is robust against uncertainties in initial conditions and hadronization mechanisms.Comment: 7 pages, 4 figure

Untimely Applause Was a Distraction; Comment on “Shanghai Rising: Health Improvements as Measured by Avoidable Mortality since 2000”

The paper published in the January 2015 issue of this journal by Gusmano and colleagues entitled “Shanghai rising: health improvements as measured by avoidable mortality since 2000” has spurred this commentary. We discuss controversial issues surrounding the concept of avoidable mortality in health service research in general and Gusmano’s study in particular. The impact of overall social development on mortality may be underappreciated in Gusmano’s report; the innovative efforts of healthcare professionals to use cutting-edge technology and evidenceapproved preventive strategies to reduce healthcare cost and improve the life quality of community members may not necessarily come to fruition in death reduction, and might be undervalued, too. More critically, the shape and magnitude of emerging health issues in Shanghai, such as accidents and injuries, pollution-related cancers, may be camouflaged in Gusmano’s report. We conclude this commentary by suggesting the most urgent questions to be addressed in the future studies

Untimely applause was a distraction Comment on “Shanghai rising: health improvements as measured by avoidable mortality since 2000”

The paper published in the January 2015 issue of this journal by Gusmano and colleagues entitled “ Shanghai rising: health improvements as measured by avoidable mortality since 2000 ” has spurred this commentary. We discuss controversial issues surrounding the concept of avoidable mortality in health service research in general and Gusmano’s study in particular. The impact of overall social development on mortality may be underappreciated in Gusmano’s report; the innovative efforts of healthcare professionals to use cutting-edge technology and evidence- approved preventive strategies to reduce healthcare cost and improve the life quality of community members may not necessarily come to fruition in death reduction, and might be undervalued, too. More critically, the shape and magnitude of emerging health issues in Shanghai, such as accidents and injuries, pollution-related cancers, may be camouflaged in Gusmano’s report. We conclude this commentary by suggesting the most urgent questions to be addressed in the future studies

ψ(2S)\psi(2S) versus J/ψJ/\psi suppression in proton-nucleus collisions from factorization violating soft color exchanges

We argue that the large suppression of the $\psi(2S)$ inclusive cross-section relative to the $J/\psi$ inclusive cross-section in proton-nucleus (p+A) collisions can be attributed to factorization breaking effects in the formation of quarkonium. These factorization breaking effects arise from soft color exchanges between charm-anticharm pairs undergoing hadronization and comoving partons that are long-lived on time scales of quarkonium formation. We compute the short distance pair production of heavy quarks in the Color Glass Condensate (CGC) effective field theory and employ an improved Color Evaporation model (ICEM) to describe their hadronization into quarkonium at large distances. The combined CGC+ICEM model provides a quantitative description of $J/\psi$ and $\psi(2S)$ data in proton-proton (p+p) collisions from both RHIC and the LHC. Factorization breaking effects in hadronization, due to additional parton comovers in the nucleus, are introduced heuristically by imposing a cutoff $\Lambda$, representing the momentum kick from soft color exchanges, in the ICEM model. Such soft exchanges have no perceptible effect on $J/\psi$ suppression in p+A collisions. In contrast, the interplay of the physics of these soft exchanges at large distances, with the physics of semi-hard rescattering at short distances, causes a significant additional suppression of $\psi(2S)$ yields relative to that of the $J/\psi$. A good fit of all RHIC and LHC $J/\psi$ and $\psi(2S)$ data, for transverse momenta $P_\perp\leq 5$ GeV in p+p and p+A collisions, is obtained for $\Lambda\sim 10$ MeV.Comment: 16 pages, 12 figures. v2: version accepted for publication in PR

Diagonal and normal with Toeplitz-block splitting iteration method for space fractional coupled nonlinear Schr\"odinger equations with repulsive nonlinearities

By applying the linearly implicit conservative difference scheme proposed in [D.-L. Wang, A.-G. Xiao, W. Yang. J. Comput. Phys. 2014;272:670-681], the system of repulsive space fractional coupled nonlinear Schr\"odinger equations leads to a sequence of linear systems with complex symmetric and Toeplitz-plus-diagonal structure. In this paper, we propose the diagonal and normal with Toeplitz-block splitting iteration method to solve the above linear systems. The new iteration method is proved to converge unconditionally, and the optimal iteration parameter is deducted. Naturally, this new iteration method leads to a diagonal and normal with circulant-block preconditioner which can be executed efficiently by fast algorithms. In theory, we provide sharp bounds for the eigenvalues of the discrete fractional Laplacian and its circulant approximation, and further analysis indicates that the spectral distribution of the preconditioned system matrix is tight. Numerical experiments show that the new preconditioner can significantly improve the computational efficiency of the Krylov subspace iteration methods. Moreover, the corresponding preconditioned GMRES method shows space mesh size independent and almost fractional order parameter insensitive convergence behaviors