Anti-Lambda polarization in high energy pp collisions with polarized beam

We study the polarization of the anti-Lambda particle in polarized high energy pp collisions at large transverse momenta. The anti-Lambda polarization is found to be sensitive to the polarization of the anti-strange sea of the nucleon. We make predictions using different parameterizations of the polarized quark distribution functions. The results show that the measurement of longitudinal anti-Lambda polarization can distinguish different parameterizations, and that similar measurements in the transversely polarized case can give some insights into the transversity distribution of the anti-strange sea of nucleon.Comment: 11 pages, 4 figure

Anti-Hyperon polarization in high energy pp collisions with polarized beams

We study the longitudinal polarization of the Sigma_bar and Xi_bar anti-hyperons in polarized high energy pp collisions at large transverse momenta, extending a recent study for the Lambda_bar anti-hyperon. We make predictions by using different parametrizations of the polarized parton densities and models for the polarized fragmentation functions. Similar to the Lambda_bar polarization, the Xi_bar0 and Xi_bar+ polarizations are found to be sensitive to the polarized anti-strange sea in the nucleon. The Sigma_bar- and Sigma_bar+ polarizations show sensitivity to the light sea quark polarizations, \Delta \bar u(x) and \Delta \bar d(x), and their asymmetry.Comment: 17 pages, 9 figures,version to appear in PR

The RHIC Spin Program: Achievements and Future Opportunities

This document summarizes recent achievements of the RHIC spin program and their impact on our understanding of the nucleon's spin structure, i.e. the individual parton (quark and gluon) contributions to the helicity structure of the nucleon and to understand the origin of the transverse spin phenomena. Open questions are identified and a suite of future measurements with polarized beams at RHIC to address them is laid out. Machine and detector requirements and upgrades are briefly discussed

The RHIC SPIN Program: Achievements and Future Opportunities

Time and again, spin has been a key element in the exploration of fundamental physics. Spin-dependent observables have often revealed deficits in the assumed theoretical framework and have led to novel developments and concepts. Spin is exploited in many parity-violating experiments searching for physics beyond the Standard Model or studying the nature of nucleon-nucleon forces. The RHIC spin program plays a special role in this grand scheme: it uses spin to study how a complex many-body system such as the proton arises from the dynamics of QCD. Many exciting results from RHIC spin have emerged to date, most of them from RHIC running after the 2007 Long Range Plan. In this document we present highlights from the RHIC program to date and lay out the roadmap for the significant advances that are possible with future RHIC running

Muon g-2

The muon g-2 collaboration has measured the anomalous magnetic g value of the positive muon to within a relative uncertainty of 0.7 parts per million. The result, a_{\mu^+} = 11 659 204(7)(5) x 10^{-10} is in good agreement with the preceding data on a_{\mu^+} and a_{\mu^-} and has about twice smaller uncertainty. The measurement tests standard model theory, which at the level of the experimental uncertainty involves quantum electrodynamics, quantum chromodynamics, and electroweak interaction in significant ways. The analysis of the anomalous magnetic g value of the negative muon is well underway

Anti-Lambda Polarization in High Energy pp Collisions with Polarized Beams

This work reviews the book “Uma história da onda progressista sul-americana (1998-2016)”, by Fabio Luis Barbosa dos Santos. As a result of field research in eleven countries, the book presents a well-informed analysis of the achievements and limits of the Pink Tide, explaining the particularities of each national situation and identifying their common historical movement. The Pink Tide phenomenon is understood in its heterogeneity, not as a set of governments, but as a historical moment. By explaining its national dilemmas, the author was able to draw a picture of their regional correlations and shared determinations. The specific tensions of each government are analyzed from their class alliances, supports and fractures with social movements and oligarchies, as well as the nuances of different integration strategies. By questioning the extractivist consensus, the author proposes a historical-structural understanding of the impasses of the Latin American conjuncture, reassessing dependence and inequality as the fortresses that block the horizons of change.Este texto é uma resenha do livro “Uma história da onda progressista sul-americana (1998-2016)”, de Fabio Luis Barbosa dos Santos. Resultado de pesquisas de campo em onze países, o livro apresenta uma análise bem-informada sobre os alcances e limites da onda progressista, explicando as particularidades de cada situação nacional e identificando seu movimento histórico comum. O fenômeno da onda progressista é entendido em sua heterogeneidade, não como um conjunto de governos, mas como um momento histórico. Ao explicar seus dilemas nacionais, o autor conseguiu traçar um quadro das suas correlações regionais e determinações compartilhadas. As tensões específicas de cada governo são analisadas a partir das suas alianças de classe, apoios e fraturas com os movimentos sociais e com as oligarquias, bem como os matizes de diferentes estratégias de integração. Ao problematizar o consenso extrativista, o autor propõe uma compreensão histórico-estrutural dos impasses da conjuntura latino-americana, recolocando a dependência e a desigualdade como fortalezas que obstruem os horizontes da transformação

Probing gluon TMDs with reconstructed and tagged heavy flavor hadron pairs at the EIC

Study of the transverse structure of the proton is one of the major physics goals of the upcoming electron ion collider (EIC). The gluon transverse momentum dependent distributions (TMDs) form an essential focus of this effort and are important towards understanding the angular momentum contribution to proton spin as well as QCD factorization. However, very limited experimental constraints on the gluon TMDs exist currently. As the heavy quark production in lepton-nucleon DIS gets a dominant contribution from the photon-gluon-fusion process, heavy quark production makes an attractive tool to probe gluon distributions in nucleons. In this paper we present a study of heavy flavor hadron pair reconstruction at a future EIC detector with MAPS based inner tracking and vertexing subsystems to constrain gluon TMDs. We utilize the excellent track pointing resolution provided by the detector to exclusively reconstruct heavy flavor hadron pairs via their hadronic decay channels and also to develop a heavy flavor hadron tagging algorithm. Statistical uncertainty projections on azimuthal asymmetries corresponding to gluon TMDs at the EIC is evaluated. The heavy flavor tagging is found to substantially enhance the purity of heavy flavor hadron pair selection, and the statistical precision of the measurement compared to that from exclusive reconstruction. The correlation between the azimuthal angle of the transverse momentum of the gluon initiating the process and that of the corresponding heavy flavor hadron pair was also studied and found to be well correlated. This study opens up heavy flavor hadron pair measurements as an attractive channel to access gluon TMDs at the EIC