University of Tsukuba

About: University of Tsukuba is a education organization based out in Tsukuba, Ibaraki, Japan. It is known for research contribution in the topics: Population & Gene. The organization has 36352 authors who have published 79483 publications receiving 1934752 citations. The organization is also known as: Tsukuba daigaku & Tsukuba University.

Nuclear modification of electron spectra and implications for heavy quark energy loss in Au+Au collisions at sNN=200GeV

Abstract: The PHENIX experiment has measured midrapidity ([FORMULA: SEE TEXT]) transverse momentum spectra ([FORMULA: SEE TEXT]) of electrons as a function of centrality in Au+Au collisions at [FORMULA: SEE TEXT]. Contributions from photon conversions and from light hadron decays, mainly Dalitz decays of pi0 and eta mesons, were removed. The resulting nonphotonic electron spectra are primarily due to the semileptonic decays of hadrons carrying heavy quarks. Nuclear modification factors were determined by comparison to nonphotonic electrons in p+p collisions. A significant suppression of electrons at high pT is observed in central Au+Au collisions, indicating substantial energy loss of heavy quarks.

End-Permian catastrophe by a bolide impact: Evidence of a gigantic release of sulfur from the mantle

Abstract: Our studies in southern China have revealed a remarkable sulfur and strontium isotope excursion at the end of the Permian, along with a coincident concentration of impact- metamorphosed grains and kaolinite and a significant decrease in manganese, phosphorous, calcium, and microfossils (foraminifera). These data suggest that an asteroid or a comet hit the ocean at the end of Permian time and caused a rapid and massive release of sulfur from the mantle to the ocean-atmosphere system, leading to significant oxygen consumption, acid rain, and the most severe biotic crisis in the history of life on Earth.

Heavy-quark production in p + p and energy loss and flow of heavy quarks in Au + Au collisions at √sNN=200 GeV

Abstract: Transverse momentum spectra of electrons (p(T)(e)) from semileptonic weak decays of heavy-flavor mesons in the range of 0.3 < p(T)(e) < 9.0 GeV/c have been measured at midrapidity (|y| < 0.35) by the PHENIX experiment at the Relativistic Heavy Ion Collider in p + p and Au + Au collisions at root s(NN) = 200 GeV. In addition, the azimuthal anisotropy parameter v(2) has been measured for 0.3 < p(T)(e) < 5.0 GeV/c in Au + Au collisions. The substantial modification in the p(T)(e) spectra in Au + Au compared with p + p collisions as well as the nonzero v(2) indicate substantial interactions and flow of heavy quarks in traversing the produced medium. Comparisons of these observables with detailed theoretical calculations can be used to identify the nature of these interactions and to quantify their extent.