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Acharya, U.*; 長谷川 勝一; 今井 憲一*; 永宮 正治*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他572名*
Physical Review C, 102(5), p.054910_1 - 054910_11, 2020/11
被引用回数:3 パーセンタイル:35.09(Physics, Nuclear)We present direct photon-hadron correlations in 200 GeV/A AuAu, Au and collisions, for direct photon from 5 - 12 GeV/, collected by the PHENIX Collaboration in the years from 2006 to 2011. We observe no significant modification of jet fragmentation in Au collisions, indicating that cold nuclear matter effects are small or absent. Hadrons carrying a large fraction of the quark's momentum are suppressed in AuAu compared to and Au. As the momentum fraction decreases, the yield of hadrons in AuAu increases to an excess over the yield in collisions. The excess is at large angles and at low hadron and is most pronounced for hadrons associated with lower momentum direct photons. Comparison to theoretical calculations suggests that the hadron excess arises from medium response to energy deposited by jets.
Cubiss, J. G.*; Barzakh, A. E.*; Andreyev, A. N.; 他57名*
Physics Letters B, 786, p.355 - 363, 2018/11
被引用回数:21 パーセンタイル:84.76(Astronomy & Astrophysics)The first accurate measurements of the -decay branching ratio and half-life of the I=1/2 ground state in Tl have been made, along with the first determination of the magnetic moments and I=1/2 spin assignments of the ground states in Au. The results are discussed within the complementary systematics of the reduced -decay widths and nuclear g factors of low-lying, I=1/2states in the neutron-deficient lead region. The findings shed light on the unexpected hindrance of the 1/2 1/2, Tl Au decay, which is explained by a mixing of 3sand 2d configurations in Au, whilst Tl remains a near-pure 3s. This conclusion is inferred from the g factor of Au which has an intermediate value between those of 3s and 2d states. A similar mixed configuration is proposed for the I=1/2 ground state of Au. This mixing may provide evidence for triaxial shapes in the ground states in these nuclei.
Adare, A.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他574名*
Physical Review C, 91(3), p.031091_1 - 031091_8, 2015/03
被引用回数:44 パーセンタイル:93.22(Physics, Nuclear)The standard model (SM) of particle physics is spectacularly successful, yet the measured value of the muon anomalous magnetic moment deviates from SM calculations by . Several theoretical models attribute this to the existence of a "dark photon", an additional gauge boson, which is weakly coupled to ordinary photons. The PHENIX experiment at the Relativistic Heavy Ion Collider has searched for a dark photon, , in decays and obtained upper limits of O(2 on - mixing at 90% C.L. for the mass range . Combined with other experimental limits, the remaining region in the - mixing parameter space that can explain the deviation from its SM value is nearly completely excluded at the 90% confidence level, with only a small region of remaining.