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論文

Measurements of $$e^+e^-$$ pairs from open heavy flavor in $$p+p$$ and $$d+A$$ 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497名*

Physical Review C, 96(2), p.024907_1 - 024907_19, 2017/08

AA2017-0466.pdf:2.14MB

 被引用回数:9 パーセンタイル:11.96(Physics, Nuclear)

We report a measurement of $$e^+e^-$$ pairs from semileptonic heavy-flavor decays in $$p+p$$ collisions at $$sqrt{s_{NN}}$$ = 200 GeV. The $$e^+e^-$$ pair yield from $$bbar{b}$$ and $$cbar{c}$$ is separated by exploiting a double differential fit done simultaneously in dielectron invariant mass and $$p_T$$. We used three different event generators, ${sc pythia}$, ${sc mc@nlo}$, and ${sc powheg}$, to simulate the $$e^+e^-$$ spectra from $$bbar{b}$$ and $$cbar{c}$$ production. The data can be well described by all three generators within the detector acceptance. However, when using the generators to extrapolate to $$4pi$$, significant differences are observed for the total cross section. These difference are less pronounced for $$bbar{b}$$ than for $$cbar{c}$$. The same model dependence was observed in already published $$d+A$$ data. The $$p+p$$ data are also directly compared with $$d+A$$ data in mass and $$p_T$$, and within the statistical accuracy no nuclear modification is seen.

論文

Nonperturbative-transverse-momentum effects and evolution in dihadron and direct photon-hadron angular correlations in $$p+p$$ collisions at $$sqrt{s}$$ = 510 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462名*

Physical Review D, 95(7), p.072002_1 - 072002_19, 2017/04

AA2017-0102.pdf:1.1MB

 被引用回数:6 パーセンタイル:33.94(Astronomy & Astrophysics)

Dihadron and isolated direct photon-hadron angular correlations are measured in $$p+p$$ collisions at $$sqrt{s}$$ = 510 GeV. Correlations of charged hadrons of $$0.7 < p_T < 10$$ GeV/$$c$$ with $$pi^0$$ mesons of $$4 < p_T < 15$$ GeV/$$c$$ or isolated direct photons of $$7 < p_T < 15$$ GeV/$$c$$ are used to study nonperturbative effects generated by initial-state partonic transverse momentum and final-state transverse momentum from fragmentation. The nonperturbative behavior is characterized by measuring the out-of-plane transverse momentum component $$p_{rm out}$$ perpendicular to the axis of the trigger particle, which is the high-$$p_T$$ direct photon or $$pi^0$$. Nonperturbative evolution effects are extracted from Gaussian fits to the away-side inclusive-charged-hadron yields for different trigger-particle transverse momenta ($$p_{T}^{rm trig}$$). The Gaussian widths and root mean square of $$p_{rm out}$$ are reported as a function of the interaction hard scale $$p_{T}^{rm trig}$$ to investigate possible transverse-momentum-dependent evolution differences between the $$pi^0$$-$$h^pm$$ and direct photon-$$h^{pm}$$ correlations and factorization breaking effects. The widths are found to decrease with $$p_{T}^{rm trig}$$, which indicates that the Collins-Soper-Sterman soft factor is not driving the evolution with the hard scale in nearly back-to-back dihadron and direct photon-hadron production in $$p+p$$ collisions. This behavior is in contrast to Drell-Yan and semi-inclusive deep-inelastic scattering measurements.

論文

Azimuthally anisotropic emission of low-momentum direct photons 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545名*

Physical Review C, 94(6), p.064901_1 - 064901_14, 2016/12

AA2016-0473.pdf:0.66MB

 被引用回数:24 パーセンタイル:4.02(Physics, Nuclear)

The PHENIX experiment at the BNL Relativistic Heavy Ion Collider has measured second- and third-order Fourier coefficients of the azimuthal distributions of direct photons emitted at midrapidity in Au+Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV for various collision centralities. Combining two different analysis techniques, results were obtained in the transverse momentum range of $$0.4 < p_T < 4.0$$ GeV/$$c$$. At low $$p_T$$ the second-order coefficients, $$v_2$$, are similar to the ones observed in hadrons. Third-order coefficients, $$v_3$$, are nonzero and almost independent of centrality. These new results on $$v_2$$ and $$v_3$$, combined with previously published results on yields, are compared to model calculations that provide yields and asymmetries in the same framework. Those models are challenged to explain simultaneously the observed large yield and large azimuthal anisotropies.

論文

Measurements of directed, elliptic, and triangular flow in Cu+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397名*

Physical Review C, 94(5), p.054910_1 - 054910_18, 2016/11

AA2016-0472.pdf:0.98MB

 被引用回数:12 パーセンタイル:13.07(Physics, Nuclear)

Measurements of anisotropic flow Fourier coefficients ($$v_n$$) for inclusive charged particles and identified hadrons $$pi^{pm}$$, $$K^{pm}$$, $$p$$, and $$bar{p}$$ produced at midrapidity in Cu+Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV are presented. The data were collected in 2012 by the PHENIX experiment at the Relativistic Heavy-Ion Collider (RHIC). The particle azimuthal distributions with respect to different-order symmetry planes $$Psi_n$$, for $$n=$$1, 2, and 3 are studied as a function of transverse momentum $$p_T$$ over a broad range of collision centralities. Mass ordering, as expected from hydrodynamic flow, is observed for all three harmonics. The charged-particle results are compared with hydrodynamical and transport model calculations. We also compare these Cu+Au results with those in Cu+Cu and Au+Au collisions at the same $$sqrt{s_{NN}}$$ and find that the $$v_2$$ and $$v_3$$, as a function of transverse momentum, follow a common scaling with $$1/(epsilon_n N_{rm part}^{1/3})$$.

論文

Measurement of the higher-order anisotropic flow coefficients for identified hadrons in Au + Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, A.*; 今井 憲一; 永宮 正治; 谷田 聖; PHENIX Collaboration*; 他385名*

Physical Review C, 93(5), p.051902_1 - 051902_8, 2016/05

AA2016-0390.pdf:0.48MB

 被引用回数:20 パーセンタイル:5.92(Physics, Nuclear)

Measurements of the anisotropic flow coefficients $$v_2{Psi_2 }$$, $$v_3{Psi_3 }$$, $$v_4{Psi_4 }$$, and $$v_4{Psi_2 }$$, for identified particles ($$pi^{pm}$$, $$K^{pm}$$, and $$p+bar{p}$$) at midrapidity, obtained relative to the event planes $$Psi_m$$ at forward rapidities in Au + Au collisions at $$sqrt{s_{NN}} =$$ 200 GeV, are presented as a function of collision centrality and particle transverse momenta $$p_T$$. The $$vn$$ coefficients show characteristic patterns consistent with hydrodynamical expansion of the matter produced in the collisions. For each harmonic $$n$$, a modified valence quark-number $$N_q$$ scaling [plotting $$v_n{Psi_m}/(N_q)^{n/2}$$ versus transverse kinetic energies $$(KE_{T})/N_q$$] is observed to yield a single curve for all the measured particle species for a broad range of $$KE_{T}$$. A simultaneous blast-wave model fit to the observed $$v_n{Psi_m}/(p_T)$$ coefficients and published particle spectra identifies radial flow anisotropies $$rho_n{Psi_m}$$ and spatial eccentricities $$s_n{Psi_m}$$ at freeze-out. These are generally smaller than the initial-state participant-plane geometric eccentricities $$epsilon_n{Psi_m^{PP}}$$ as also observed in the final eccentricity from quantum interferometry measurements with respect to the event plane.

論文

Forward $$J/psi$$ production in U + U collisions at $$sqrt{s_{NN}}$$ = 193 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397名*

Physical Review C, 93(3), p.034903_1 - 034903_12, 2016/03

AA2015-1022.pdf:0.96MB

 被引用回数:3 パーセンタイル:52.92(Physics, Nuclear)

The invariant yields, $$dN/dy$$, for $$J/psi$$ production at forward rapidity ($$1.2 < |y| < 2.2$$) in U+U collisions at $$sqrt{s_{NN}}$$ = 193 GeV have been measured as a function of collision centrality. The invariant yields and nuclear-modification factor $$R_{AA}$$ are presented and compared with those from Au + Au collisions in the same rapidity range. Additionally, the direct ratio of the invariant yields from U + U and Au + Au collisions within the same centrality class is presented, and used to investigate the role of $$cbar{c}$$ coalescence. Two different parametrizations of the deformed Woods-Saxon distribution were used in Glauber calculations to determine the values of the number of nucleon-nucleon collisions in each centrality class, $$N_{rm coll}$$, and these were found to give significantly different $$N_{rm coll}$$ values. Results using $$N_{rm coll}$$ values from both deformed Woods-Saxon distributions are presented. The measured ratios show that the $$J/psi$$ suppression, relative to binary collision scaling, is similar in U + U and Au + Au for peripheral and midcentral collisions, but that $$J/psi$$ show less suppression for the most central U + U collisions. The results are consistent with a picture in which, for central collisions, increase in the $$J/psi$$ yield due to $$cbar{c}$$ coalescence becomes more important than the decrease in yield due to increased energy density. For midcentral collisions, the conclusions about the balance between $$cbar{c}$$ coalescence and suppression depend on which deformed Woods-Saxon distribution is used to determine $$N_{coll}$$.

論文

Single electron yields from semileptonic charm and bottom hadron decays 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426名*

Physical Review C, 93(3), p.034904_1 - 034904_29, 2016/03

AA2015-1023.pdf:2.82MB

 被引用回数:24 パーセンタイル:4.02(Physics, Nuclear)

The PHENIX Collaboration at the Relativistic Heavy Ion Collider has measured open heavy flavor production in minimum bias Au + Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV via the yields of electrons from semileptonic decays of charm and bottom hadrons. Previous heavy flavor electron measurements indicated substantial modification in the momentum distribution of the parent heavy quarks owing to the quark-gluon plasma created in these collisions. For the first time, using the PHENIX silicon vertex detector to measure precision displaced tracking, the relative contributions from charm and bottom hadrons to these electrons as a function of transverse momentum are measured in Au + Au collisions. We compare the fraction of electrons from bottom hadrons to previously published results extracted from electron-hadron correlations in $$p + p$$ collisions at $$sqrt{s_{NN}}$$ = 200 GeV and find the fractions to be similar within the large uncertainties on both measurements for $$p_T>$$ 4 GeV/$$c$$. We use the bottom electron fractions in Au + Au and $$p + p$$ along with the previously measured heavy flavor electron $$R_{AA}$$ to calculate the $$R_{AA}$$ for electrons from charm and bottom hadron decays separately. We find that electrons from bottom hadron decays are less suppressed than those from charm for the region 3$$<p_T<$$ 4 GeV/$$c$$.

論文

Centrality-dependent modification of jet-production rates in deuteron-gold collisions at $$sqrt{s_{NN}}$$=200 GeV

Adare, A.*; 今井 憲一; 長谷川 勝一; 永宮 正治; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他477名*

Physical Review Letters, 116(12), p.122301_1 - 122301_9, 2016/03

AA2015-1072.pdf:0.36MB

 被引用回数:20 パーセンタイル:9.61(Physics, Multidisciplinary)

Jet production rates are measured in $$p+p$$ and $$d+$$Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV recorded in 2008 with the PHENIX detector at the Relativistic Heavy Ion Collider. Jets are reconstructed using the $$R$$ =0.3 anti-$$k_t$$ algorithm from energy deposits in the electromagnetic calorimeter and charged tracks in multiwire proportional chambers, and the jet transverse momentum ($$p_T$$) spectra are corrected for the detector response. Spectra are reported for jets with $$12 < p_T < 50$$ GeV/$$c$$ within a pseudorapidity acceptance of $$|eta|<0.3$$. The nuclear-modification factor ($$R_{d{rm Au}}$$) values and central-to-peripheral ratios ($$R_{CP}$$) show large, $$p_T$$-dependent deviations from unity, challenging the conventional models that relate hard-process rates and soft-particle production in collisions involving nuclei.

論文

Scaling properties of fractional momentum loss of high-$$p_T$$ hadrons in nucleus-nucleus collisions at $$sqrt{s_{NN}}$$ from 62.4 GeV to 2.76 TeV

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623名*

Physical Review C, 93(2), p.024911_1 - 024911_20, 2016/02

AA2015-1021.pdf:1.07MB

 被引用回数:6 パーセンタイル:31.2(Physics, Nuclear)

Measurements of the fractional momentum loss ($$S_{rm loss}=delta p_T/p_T$$) of high-transverse-momentum-identified hadrons in heavy-ion collisions are presented. Using $$pi^0$$ in Au+Au and Cu+Cu collisions at $$sqrt{s_{NN}}$$ = 62.4 and 200 GeV measured by the PHENIX experiment at the Relativistic Heavy Ion Collider and and charged hadrons in Pb+Pb collisions measured by the ALICE experiment at the Large Hadron Collider, we studied the scaling properties of $$S_{rm loss}$$ as a function of a number of variables: the number of participants, $$N_{rm part}$$, the number of quark participants, $$N_{qp}$$, the charged-particle density, $$dN_{rm ch}/deta$$, and the Bjorken energy density times the equilibration time, $$epsilon_{Bj}tau_0$$. We find that the $$p_T$$, where $$S_{rm loss}$$ has its maximum, varies both with centrality and collision energy. Above the maximum, $$S_{rm loss}$$ tends to follow a power-law function with all four scaling variables. The data at $$sqrt{s_{NN}}$$ = 200 and 2.76 TeV, for sufficiently high particle densities, have a common scaling of $$S_{rm loss}$$ with $$dN_{rm ch}/deta$$ and $$epsilon_{Bj}tau_0$$, lending insight into the physics of parton energy loss.

論文

Measurement of higher cumulants of net-charge multiplicity distributions in Au + Au collisions at $$sqrt{s_{NN}}$$ = 7.7-200 GeV

Adare, A.*; 今井 憲一; 永宮 正治; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他506名*

Physical Review C, 93(1), p.011901_1 - 011901_8, 2016/01

AA2015-0857.pdf:0.94MB

 被引用回数:41 パーセンタイル:1.3(Physics, Nuclear)

We report the measurement of cumulants ($$C_n$$, $$n=1,...,4$$) of the net-charge distributions measured within pseudorapidity ($$|eta| < 0.35$$) in Au + Au collisions at $$sqrt{s_{NN}}$$ = 7.7-200 GeV with the PHENIX experiment at the Relativistic Heavy Ion Collider. The ratios of cumulants (e.g., $$C_1/C_2$$, $$C_3/C_1$$) of the net-charge distributions, which can be related to volume independent susceptibility ratios, are studied as a function of centrality and energy. These quantities are important to understand the quantum-chromodynamics phase diagram and possible existence of a critical end point. The measured values are very well described by expectation from negative binomial distributions. We do not observe any nonmonotonic behavior in the ratios of the cumulants as a function of collision energy. The measured values of $$C_1/C_2$$ and $$C_3/C_1$$ can be directly compared to lattice quantum-chromodynamics calculations and thus allow extraction of both the chemical freeze-out temperature and the baryon chemical potential at each center-of-mass energy. The extracted baryon chemical potentials are in excellent agreement with a thermal-statistical analysis model.

論文

$$phi$$ meson production in $$d$$ + 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477名*

Physical Review C, 92(4), p.044909_1 - 044909_14, 2015/10

AA2015-0749.pdf:0.78MB

 被引用回数:8 パーセンタイル:30.05(Physics, Nuclear)

The PHENIX Collaboration has measured $$phi$$ meson production in $$d$$ + Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV using the dimuon and dielectron decay channels. The $$phi$$ meson is measured in the forward (backward) $$d$$-going (Au-going) direction, $$1.2 < y < 2.2$$ $$(-2.2 < y < -1.2)$$ in the transverse-momentum ($$p_T$$) range from 1-7 GeV/$$c$$ and at midrapidity $$|y| < 0.35$$ in the $$p_T$$ range below 7 GeV/$$c$$. The $$phi$$ meson invariant yields and nuclear-modification factors as a function of $$p_T$$, rapidity, and centrality are reported. An enhancement of $$phi$$ meson production is observed in the Au-going direction, while suppression is seen in the $$d$$-going direction, and no modification is observed at midrapidity relative to the yield in $$p+p$$ collisions scaled by the number of binary collisions. Similar behavior was previously observed for inclusive charged hadrons and open heavy flavor, indicating similar cold-nuclear-matter effects.

論文

Systematic study of azimuthal anisotropy in Cu + Cu and Au + Au collisions at $$sqrt{s_{NN}}$$ = 62.4 and 200 GeV

Adare, A.*; 今井 憲一; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他420名*

Physical Review C, 92(3), p.034913_1 - 034913_20, 2015/09

AA2015-0713.pdf:1.3MB

 被引用回数:11 パーセンタイル:20.99(Physics, Nuclear)

We have studied the dependence of azimuthal anisotropy $$v_2$$ for inclusive and identified charged hadrons in Au + Au and Cu + Cu collisions on collision energy, species, and centrality. The values of $$v_2$$ as a function of transverse momentum $$p_T$$ and centrality in Au+Au collisions at $$sqrt{s_{NN}}$$ = 200 and 62.4 GeV are the same within uncertainties. However, in Cu + Cu collisions we observe a decrease in $$v_2$$ values as the collision energy is reduced from 200 to 62.4 GeV. The decrease is larger in the more peripheral collisions. By examining both Au + Au and Cu + Cu collisions we find that $$v_2$$ depends both on eccentricity and the number of participants, $$N_{rm part}$$. We observe that $$v_2$$ divided by eccentricity ($$epsilon$$) monotonically increases with $$N_{rm part}$$ and scales as $$N_{rm part}^{1/3}$$. The Cu + Cu data at 62.4 GeV falls below the other scaled $$v_2$$ data. For identified hadrons, $$v_2$$ divided by the number of constituent quarks $$n_q$$ is independent of hadron species as a function of transverse kinetic energy $$KE_T=m_T-m$$ between $$0.1 < KE_T/n_q < 1$$ GeV. Combining all of the above scaling and normalizations, we observe a near-universal scaling, with the exception of the Cu + Cu data at 62.4 GeV, of $$v_2/(n_q cdot epsilon cdot N_{rm part}^{1/3})$$ vs $$KE_T/n_q$$ for all measured particles.

論文

Systematic study of charged-pion and kaon femtoscopy in Au + Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, A.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他493名*

Physical Review C, 92(3), p.034914_1 - 034914_21, 2015/09

AA2015-0712.pdf:1.48MB

 被引用回数:14 パーセンタイル:16.92(Physics, Nuclear)

We present a systematic study of charged-pion and kaon interferometry in Au + Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV. The kaon mean source radii are found to be larger than pion radii in the outward and longitudinal directions for the same transverse mass; this difference increases for more central collisions. The azimuthal angle dependence of the radii was measured with respect to the second-order event plane and similar oscillations of the source radii were found for pions and kaons. Hydrodynamic models qualitatively describe the similar oscillations of the mean source radii for pions and kaons, but they do not fully describe the transverse-mass dependence of the oscillations.

論文

Measurements of elliptic and triangular flow in high-multiplicity $$^3$$He + 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623名*

Physical Review Letters, 115(14), p.142301_1 - 142301_9, 2015/09

AA2015-0748.pdf:0.64MB

 被引用回数:74 パーセンタイル:1.95(Physics, Multidisciplinary)

We present the first measurement of elliptic ($$v_2$$) and triangular ($$v_3$$) flow in high-multiplicity $$^3$$He + Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV. Two-particle correlations, where the particles have a large separation in pseudorapidity, are compared in $$^3$$He + Au and in $$p+p$$ collisions and indicate that collective effects dominate the second and third Fourier components for the correlations observed in the $$^3$$He + Au system. The collective behavior is quantified in terms of elliptic $$v_2$$ and triangular $$v_3$$ anisotropy coefficients measured with respect to their corresponding event planes. The $$v_2$$ values are comparable to those previously measured in $$d$$ + Au collisions at the same nucleon-nucleon center-of-mass energy. Comparisons with various theoretical predictions are made, including to models where the hot spots created by the impact of the three $$^3$$He nucleons on the Au nucleus expand hydrodynamically to generate the triangular flow. The agreement of these models with data may indicate the formation of low-viscosity quark-gluon plasma even in these small collision systems.

論文

Measurement of $$Upsilon(1S+2S+3S)$$ production in $$p+p$$ and Au+Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, A.*; 今井 憲一; 谷田 聖; PHENIX Collaboration*; 他504名*

Physical Review C, 91(2), p.024913_1 - 024913_16, 2015/02

AA2015-0520.pdf:2.14MB

 被引用回数:18 パーセンタイル:9.89(Physics, Nuclear)

Measurements of bottomonium production in heavy-ion and $$p+p$$ collisions at the Relativistic Heavy Ion Collider (RHIC) are presented. The inclusive yield of the three $$Upsilon$$ states, $$Upsilon(1S+2S+3S)$$, was measured in the PHENIX experiment via electron-positron decay pairs at midrapidity for Au+Au and $$p+p$$ collisions at $$sqrt{s_{NN}} = 200$$ GeV. The $$Upsilon(1S+2S+3S) to e^+e^-$$ differential cross section at midrapidity was found to be $$B_{ee}dsigma/dy = 108 pm 38({rm stat.}) pm 15 ({rm syst.}) pm 11 ({rm luminosity})$$ pb in $$p+p$$ collisions. The nuclear modification factor in the 30% most central Au+Au collisions indicates a suppression of the total $$Upsilon$$ state yield relative to the extrapolation from $$p+p$$ collision data. The suppression is consistent with measurements made by STAR at RHIC and at higher energies by the CMS experiment at the Large Hadron Collider.

論文

Molecular dynamics simulation for the baryon-quark phase transition at finite baryon density

秋村 友香; 丸山 敏毅; 吉永 尚孝*; 千葉 敏

European Physical Journal A, 25(3), p.405 - 411, 2005/09

 被引用回数:3 パーセンタイル:67.13(Physics, Nuclear)

クォーク多体系の分子動力学を用いて、低密度のバリオン物質から高密度のクォーク物質への相転移の機構を調べ、相互作用と運動エネルギーの競合により物質の状態が変化することを明らかにした。また、中間子交換力をクォーク間に導入することで、バリオン物質の状態方程式をよく知られているものに合わせることができた。これにより、相転移が起こる高密度でストレンジ物質と通常原子核物質のどちらが安定であるかを議論することができるようになった。さらに、有限温度でのシミュレーションを行い、温度-密度平面でのバリオン物質,クォーク物質の相図を求めた。

報告書

第5回「極限条件におけるハドロン科学」研究会報告集; 2003年3月18日$$sim$$20日,東海研究所,東海村

丸山 敏毅; 千葉 敏

JAERI-Conf 2003-009, 233 Pages, 2003/08

JAERI-Conf-2003-009.pdf:15.94MB

第5回「極限条件におけるハドロン科学」研究会は、先端基礎研究センター第258回基礎科学セミナーとして、極限ハドロン科学研究グループの主催で2003年3月18日から20日にかけて、東海研究所にて開催された。高密度核物質やハドロン構造,ハイパー核,中性子星,超新星爆発,元素合成,重イオン反応,クォーク物質,QCDなど多岐にわたるトピックスについて33件の研究発表と討論が約50名の参加者によって行われた。また、今回は極限ハドロン科学研究グループの総括と、次期の多体ハドロン系理論研究グループに向けての展望をも目的として行われた。本レポートはその報告書である。

口頭

A New phase and exciton modes in QCD Kondo effect

鈴木 渓

no journal, , 

通常の近藤効果は金属中に局在する不純物によって引き起こされ、系の電気的/熱的/輸送的性質に対して大きな影響を及ぼす。一方で、高密度のクォーク物質においては、比較的重い不純物クォークと軽いクォークとのカラー交換相互作用によって同様の効果が起こることが期待されている(QCD近藤効果)。この講演では、Refs.~[1,2]において予言された、ライトクォークとヘビークォークから成る凝縮によって特徴づけられる新しい相についてレビューを行う。特に、この相における励起状態として現れる様々なエキシトンモードについて議論を行う~[3]。これらのモードは高密度クォーク物質における輸送的性質に寄与することが期待される。[1] S. Yasui, K. Suzuki, and K. Itakura, Nucl. Phys. A983 (2019) 90. [2] S. Yasui, K. Suzuki, and K. Itakura, Phys. Rev. D96 (2017) 014016. [3] D. Suenaga, K. Suzuki, and S. Yasui, arXiv:1909.07573.

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