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論文

Decay spectroscopy of $$^{160}$$Eu; Quasiparticle configurations of excited states and structure of $$K^{pi}$$ = 4$$^{+}$$ bandheads in $$^{160}$$Gd

Yates, D.*; Kr$"u$cken, R.*; Dillmann, I.*; Garrett, P. E.*; Smallcombe, J.; 他44名*

Physical Review C, 107(6), p.064309_1 - 064309_20, 2023/06

https://doi.org/10.1103/PhysRevC.107.064309
 被引用回数：0 パーセンタイル：0.02(Physics, Nuclear)

Detailed spectroscopy of neutron-rich, heavy, deformed nuclei is of broad interest for nuclear astrophysics and nuclear structure. Nuclei in the $$r$$-process path and following freeze-out region impact the resulting $$r$$-process abundance distribution, and the structure of nuclei midshell in both proton and neutron number helps to understand the evolution of subshell gaps and large deformation in these nuclei.

論文

Production of $$bbar{b}$$ at forward rapidity in $$p+p$$ collisions at $$sqrt{s}=510$$ GeV

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344名*

Physical Review D, 102(9), p.092002_1 - 092002_14, 2020/11

https://doi.org/10.1103/PhysRevD.102.092002
 被引用回数：0 パーセンタイル：0.01(Astronomy & Astrophysics)

The cross section of bottom quark-antiquark ($$bbar{b}$$) production in $$p+p$$ collisions at $$sqrt{s}=510$$ GeV is measured with the PHENIX detector at the Relativistic Heavy Ion Collider. The results are based on the yield of high mass, like-sign muon pairs measured within the PHENIX muon arm acceptance ($$1.2 < |y| < 2.2$$). The $$bbar{b}$$ signal is extracted from like-sign dimuons by utilizing the unique properties of neutral $$B$$ meson oscillation. We report a differential cross section of $$dsigma_{bbar{b} rightarrow mu^pmmu^pm}/dy = 0.16 pm 0.01~(mbox{stat}) pm 0.02~(mbox{syst}) pm 0.02~(mbox{global})$$ nb for like-sign muons in the rapidity and $$p_T$$ ranges $$1.2 < |y| < 2.2$$ and $$p_T > 1$$ GeV/$$c$$, and dimuon mass of 5 - 10 GeV/$$c^2$$. The extrapolated total cross section at this energy for $$bbar{b}$$ production is $$13.1 pm 0.6~(mbox{stat}) pm 1.5~(mbox{syst}) pm 2.7~(mbox{global})~mu$$b. The total cross section is compared to a perturbative quantum chromodynamics calculation and is consistent within uncertainties. The azimuthal opening angle between muon pairs from $$bbar{b}$$ decays and their $$p_T$$ distributions are compared to distributions generated using ${sc ps pythia 6}$, which includes next-to-leading order processes. The azimuthal correlations and pair $$p_T$$ distribution are not very well described by ${sc pythia}$ calculations, but are still consistent within uncertainties. Flavor creation and flavor excitation subprocesses are favored over gluon splitting.

論文

Polarization and cross section of midrapidity $$J/psi$$ production in $$p+p$$ collisions at $$sqrt{s}=510$$ GeV

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344名*

Physical Review D, 102(7), p.072008_1 - 072008_13, 2020/10

https://doi.org/10.1103/PhysRevD.102.072008
 被引用回数：2 パーセンタイル：15.55(Astronomy & Astrophysics)

The PHENIX experiment has measured the spin alignment for inclusive $$J/psi rightarrow e^{+}e^{-}$$ decays in $$p+p$$ collisions at $$sqrt{s}=510$$ GeV at midrapidity. The angular distributions have been measured in three different polarization frames, and the three decay angular coefficients have been extracted in a full two-dimensional analysis. Previously, PHENIX saw large longitudinal net polarization at forward rapidity at the same collision energy. This analysis at midrapidity, complementary to the previous PHENIX results, sees no sizable polarization in the measured transverse momentum range of $$0.0 < p_T < 10.0$$ GeV/$$c$$. The results are consistent with a previous one-dimensional analysis at midrapidity at $$sqrt{s}=200$$ GeV. The transverse-momentum-dependent cross section for midrapidity $$J/psi$$ production has additionally been measured, and after comparison to world data we find a simple logarithmic dependence of the cross section on $$sqrt{s}$$.

論文

Low-momentum direct-photon measurement in Cu + Cu collisions at $$sqrt{s_{_{NN}}}=200$$ GeV

Adare, A.*; 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448名*

Physical Review C, 98(5), p.054902_1 - 054902_11, 2018/11

https://doi.org/10.1103/PhysRevC.98.054902
 被引用回数：14 パーセンタイル：75.64(Physics, Nuclear)

We have measured direct photons for $$p_T< 5~$$GeV/$$c$$ in minimum bias and 0% - 40% most central events at midrapidity for Cu$$+$$Cu collisions at $$sqrt{s_{_{NN}}}=200$$ GeV. The $$e^{+}e^{-}$$ contribution from quasi-real direct virtual photons has been determined as an excess over the known hadronic contributions in the $$e^{+}e^{-}$$ mass distribution. A clear enhancement of photons over the binary scaled $$p$$$$+$$$$p$$ fit is observed for $$p_T < 4$$ GeV/$$c$$ in Cu$$+$$Cu data. The $$p_T$$ spectra are consistent with the Au$$+$$Au data covering a similar number of participants. The inverse slopes of the exponential fits to the excess after subtraction of the $$p$$$$+$$$$p$$ baseline are 285$$pm$$53(stat)$$pm$$57(syst)~MeV/$$c$$ and 333$$pm$$72(stat)$$pm$$45(syst)~MeV/$$c$$ for minimum bias and 0% - 40% most central events, respectively. The rapidity density, $$dN/dy$$, of photons demonstrates the same power law as a function of $$dN_{rm ch}/deta$$ observed in Au$$+$$Au at the same collision energy.

論文

L$'{e}$vy-stable two-pion Bose-Einstein correlations in $$sqrt{s_{NN}}=200$$ GeV Au$$+$$Au collisions

Adare, A.*; 長谷川 勝一; 永宮 正治; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他448名*

Physical Review C, 97(6), p.064911_1 - 064911_22, 2018/06

https://doi.org/10.1103/PhysRevC.97.064911
 被引用回数：35 パーセンタイル：92.4(Physics, Nuclear)

We present a detailed measurement of charged two-pion correlation functions in 0%-30% centrality $$sqrt{s_{_{NN}}}=200$$ GeV Au$$+$$Au collisions by the PHENIX experiment at the Relativistic Heavy Ion Collider. The data are well described by Bose-Einstein correlation functions stemming from L$'e$vy-stable source distributions. Using a fine transverse momentum binning, we extract the correlation strength parameter $$lambda$$, the L$'e$vy index of stability $$alpha$$ and the L$'e$vy length scale parameter $$R$$ as a function of average transverse mass of the pair $$m_T$$. We find that the positively and the negatively charged pion pairs yield consistent results, and their correlation functions are represented, within uncertainties, by the same L$'e$vy-stable source functions. The $$lambda(m_T)$$ measurements indicate a decrease of the strength of the correlations at low $$m_T$$. The L$'e$vy length scale parameter $$R(m_T)$$ decreases with increasing $$m_T$$, following a hydrodynamically predicted type of scaling behavior. The values of the L$'e$vy index of stability $$alpha$$ are found to be significantly lower than the Gaussian case of $$alpha=2$$, but also significantly larger than the conjectured value that may characterize the critical point of a second-order quark-hadron phase transition.

論文

Measurement of the decays $$Btoetaellnu_ell$$ and $$Btoeta^primeellnu_ell$$ in fully reconstructed events at Belle

Bele$~n$o, C.*; 谷田 聖; Belle Collaboration*; 他144名*

Physical Review D, 96(9), p.091102_1 - 091102_8, 2017/11

AA2018-0506.pdf:0.47MB

https://doi.org/10.1103/PhysRevD.96.091102
 被引用回数：4 パーセンタイル：23.95(Astronomy & Astrophysics)

We report branching fraction measurements of the decays $$B^+toetaell^+nu_ell$$ and $$B^+toeta^primeell^+nu_ell$$ based on 711~fb$$^{-1}$$ of data collected near the $$Upsilon(4S)$$ resonance with the Belle experiment at the KEKB asymmetric-energy $$e^+e^-$$ collider. This data sample contains 772 million $$Bbar B$$~events. One of the two $$B$$~mesons is fully reconstructed in a hadronic decay mode. Among the remaining ("signal-$$B$$") daughters, we search for the $$eta$$~meson in two decay channels, $$etatogammagamma$$ and $$etatopi^+pi^-pi^0$$, and reconstruct the $$eta^{prime}$$~meson in $$eta^primetoetapi^+pi^-$$ with subsequent decay of the $$eta$$ into $$gammagamma$$. Combining the two $$eta$$ modes and using an extended maximum likelihood, the $$B^+toetaell^+nu_ell$$ branching fraction is measured to be $$(4.2pm 1.1 (rm stat.)pm 0.3 (rm syst.))times 10^{-5}$$. For $$B^+toeta^primeell^+nu_ell$$, we observe no significant signal and set an upper limit of $$0.72times 10^{-4}$$ at 90% confidence level.

論文

Measurement of parity-violating spin asymmetries in W$$^{pm}$$ production at midrapidity in longitudinally polarized $$p+p$$ collisions

Adare, A.*; 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445名*

Physical Review D, 93(5), p.051103_1 - 051103_8, 2016/03

AA2015-1060.pdf:0.4MB

https://doi.org/10.1103/PhysRevD.93.051103
 被引用回数：25 パーセンタイル：73.27(Astronomy & Astrophysics)

We present midrapidity measurements from the PHENIX experiment of large parity-violating single-spin asymmetries of high transverse momentum electrons and positrons from $$W^{pm}/Z$$ decays, produced in longitudinally polarized $$p+p$$ collisions at center of mass energies of $$sqrt{s}$$ = 500 and 510 GeV. These asymmetries allow direct access to the antiquark polarized parton distribution functions due to the parity-violating nature of the $$W$$-boson coupling to quarks and antiquarks. The results presented are based on data collected in 2011, 2012, and 2013 with an integrated luminosity of 240 pb$$^{-1}$$, which exceeds previous PHENIX published results by a factor of more than 27. These high $$Q^2$$ data probe the parton structure of the proton at $$W$$ mass scale and provide an important addition to our understanding of the antiquark parton helicity distribution functions at an intermediate Bjorken $$x$$ value of roughly $$M_W/sqrt{s}=0.16$$.

論文

Dielectron production in Au + Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, A.*; 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440名*

Physical Review C, 93(1), p.014904_1 - 014904_34, 2016/01

AA2015-0856.pdf:3.7MB

https://doi.org/10.1103/PhysRevC.93.014904
 被引用回数：49 パーセンタイル：94.89(Physics, Nuclear)

We present measurements of $$e^+e^-$$ production at midrapidity in Au + Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV. The invariant yield is studied within the PHENIX detector acceptance over a wide range of mass ($$m_{ee} < 5$$ GeV/$$c^2$$) and pair transverse momentum ($$p_T<5$$ GeV/$$c$$) for minimum bias and for five centrality classes. The $$e^+e^-$$ yield is compared to the expectations from known sources. In the low-mass region ($$m_{ee}=$$0.30-0.76 GeV/$$c^2$$) there is an enhancement that increases with centrality and is distributed over the entire pair $$p_T$$ range measured. It is significantly smaller than previously reported by the PHENIX experiment and amounts to $$2.3 pm 0.4({rm stat}) pm 0.4({rm syst}) pm 0.2({rm model})$$ or to $$1.7 pm 0.3({rm stat}) pm 0.3({rm syst}) pm 0.2({rm model})$$ for minimum bias collisions when the open heavy-flavor contribution is calculated with pythia or mc@nlo, respectively. The inclusive mass and $$p_T$$ distributions, as well as the centrality dependence, are well reproduced by model calculations where the enhancement mainly originates from the melting of the $$rho$$ meson resonance as the system approaches chiral symmetry restoration. In the intermediate-mass region ($$m_{ee}=$$1.2-2.8 GeV/$$c^2$$), the data hint at a significant contribution in addition to the yield from the semileptonic decays of heavy-flavor mesons.

論文

Measurement of $$e^+e^- to pi^+pi^-psi(2S)$$ via initial state radiation at Belle

Wang, X. L.*; 谷田 聖; Belle Collaboration*; 他144名*

Physical Review D, 91(11), p.112007_1 - 112007_15, 2015/06

AA2015-0519.pdf:0.8MB

https://doi.org/10.1103/PhysRevD.91.112007
 被引用回数：117 パーセンタイル：97.73(Astronomy & Astrophysics)

We report measurement of the cross section of $$e^+e^- to pi^+pi^- psi(2S)$$ between 4.0 and 5.5 GeV, based on an analysis of initial state radiation events in a 980 $${rm fb^{-1}}$$ data sample recorded with the Belle detector. The properties of the $$Y(4360)$$ and $$Y(4660)$$ states are determined. Fitting the mass spectrum of $$pi^+pi^- psi(2S)$$ with two coherent Breit-Wigner functions, we find two solutions with identical mass and width but different couplings to electron-positron pairs: $$M_{Y(4360)}=(4347 pm 6 pm 3)$$ $${rm MeV}/c^2$$, $$Gamma_{Y(4360)} = (103 pm 9 pm 5)$$ MeV, $$M_{Y(4660)}=(4652 pm 10 pm 8)$$ $${rm MeV}/c^2$$, $$Gamma_{Y(4660)} = (68 pm 11 pm 1)$$ MeV, and $${cal B}[Y(4360) to pi^+pi^- psi(2S)]cdot Gamma^{e^+e^-}_{Y(4360)} = (10.9 pm 0.6 pm 0.7)$$ eV and $${cal B}[Y(4660)to pi^+pi^- psi(2S)]cdotGamma^{e^+e^-}_{Y(4660)}=(8.1 pm 1.1 pm 0.5)$$ eV for one solution; or $${cal B}[Y(4360) to pi^+pi^- psi(2S)]cdot Gamma^{e^+e^-}_{Y(4360)} = (9.2 pm 0.6 pm 0.6)$$ eV and $${cal B}[Y(4660)to pi^+pi^- psi(2S)]cdotGamma^{e^+e^-}_{Y(4660)}=(2.0 pm 0.3 pm 0.2)$$ eV for the other. Here, the first errors are statistical and the second systematic. Evidence for a charged charmoniumlike structure at 4.05 $${rm MeV}/c^2$$ is observed is observed in the $$pi^{pm}psi(2S)$$ intermediate state in the $$Y(4360)$$ decays.

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