共查询到20条相似文献,搜索用时 31 毫秒
1.
We study the dynamical chiral symmetry breaking/restoration for various numbers of light quarks flavors \begin{document}$ N_f $\end{document} ![]()
![]()
and colors \begin{document}$ N_c $\end{document} ![]()
![]()
using the Nambu-Jona-Lasinio (NJL) model of quarks in the Schwinger-Dyson equation framework, dressed with a color-flavor dependence of effective coupling. For fixed \begin{document}$ N_f = 2 $\end{document} ![]()
![]()
and varying \begin{document}$ N_c $\end{document} ![]()
![]()
, we observe that the dynamical chiral symmetry is broken when \begin{document}$ N_c $\end{document} ![]()
![]()
exceeds its critical value \begin{document}$ N^{c}_{c}\approx2.2 $\end{document} ![]()
![]()
. For a fixed \begin{document}$ N_c = 3 $\end{document} ![]()
![]()
and varying \begin{document}$ N_f $\end{document} ![]()
![]()
, we observe that the dynamical chiral symmetry is restored when \begin{document}$ N_f $\end{document} ![]()
![]()
reaches its critical value \begin{document}$ N^{c}_{f}\approx8 $\end{document} ![]()
![]()
. Strong interplay is observed between \begin{document}$ N_c $\end{document} ![]()
![]()
and \begin{document}$ N_f $\end{document} ![]()
![]()
, i.e., larger values of \begin{document}$ N_c $\end{document} ![]()
![]()
tend to strengthen the dynamical generated quark mass and quark-antiquark condensate, while higher values of \begin{document}$ N_f $\end{document} ![]()
![]()
suppress both parameters. We further sketch the quantum chromodynamics (QCD) phase diagram at a finite temperature T and quark chemical potential μ for various \begin{document}$ N_c $\end{document} ![]()
![]()
and \begin{document}$ N_f $\end{document} ![]()
![]()
. At finite T and μ, we observe that the critical number of colors \begin{document}$ N^{c}_c $\end{document} ![]()
![]()
is enhanced, whereas the critical number of flavors \begin{document}$ N^{c}_f $\end{document} ![]()
![]()
is suppressed as T and μ increase. Consequently, the critical temperature \begin{document}$ T_c $\end{document} ![]()
![]()
, \begin{document}$ \mu_c $\end{document} ![]()
![]()
, and co-ordinates of the critical endpoint \begin{document}$ (T^{E}_c,\mu^{E}_c) $\end{document} ![]()
![]()
in the QCD phase diagram are enhanced as \begin{document}$ N_c $\end{document} ![]()
![]()
increases and suppressed when \begin{document}$ N_f $\end{document} ![]()
![]()
increases. Our findings agree with the lattice QCD and Schwinger-Dyson equations predictions. 相似文献
2.
Xiao-Yun Wang Wei Kou Qing-Yong Lin Ya-Ping Xie Xurong Chen Alexey Guskov 《中国物理C(英文版)》2021,45(5):054102-054102-7
The photoproduction of the bottomonium-like states Z_b(10610) and Z_b(10650) via γ p scattering is studied within an effective Lagrangian approach and the vector-meson-dominance model. The Regge model is employed to calculate the photoproduction of Z_b states via the t-channel with π exchange. The numerical results show that the values of the total cross-sections of Z_b(10610) and Z_b(10650) can reach 0.09 nb and 0.02 nb, respectively,near the center-of-mass energy of 22 GeV. Experimental measurements and studies of the photoproduction of Z_b states near the energy region around W ■ 22 GeV are suggested. Moreover, with the help of eSTARlight and STARlight programs, we have obtained the cross-sections and numbers of events for Z_b(10610) production in electron-ion collisions(EIC) and ultraperipheral collisions(UPCs). The results show that a considerable number of Z_b(10610)events can be produced in the relevant experiments on EICs and UPCs. We have also calculated the rates and kinematic distributions for γp → Z_bn in ep and pA collisions via EICs and UPCs. The results will provide an important reference for the RHIC, LHC, EIC-US, LHeC, and FCC experiments in searching for bottomonium-like Z_b states. 相似文献
3.
We investigate observational constraints on the running vacuum model (RVM) of \begin{document}$\Lambda=3\nu (H^{2}+K/a^2)+c_0$\end{document} ![]()
![]()
in a spatially curved universe, where \begin{document}$\nu$\end{document} ![]()
![]()
is the model parameter, \begin{document}$K$\end{document} ![]()
![]()
corresponds to the spatial curvature constant, \begin{document}$a$\end{document} ![]()
![]()
represents the scalar factor, and \begin{document}$c_{0}$\end{document} ![]()
![]()
is a constant defined by the boundary conditions. We study the CMB power spectra with several sets of \begin{document}$\nu$\end{document} ![]()
![]()
and \begin{document}$K$\end{document} ![]()
![]()
in the RVM. By fitting the cosmological data, we find that the best fitted \begin{document}$\chi^2$\end{document} ![]()
![]()
value for RVM is slightly smaller than that of \begin{document}$\Lambda$\end{document} ![]()
![]()
CDM in the non-flat universe, along with the constraints of \begin{document}$\nu\leqslant O(10^{-4})$\end{document} ![]()
![]()
(68% C.L.) and \begin{document}$|\Omega_K=-K/(aH)^2|\leqslant O(10^{-2})$\end{document} ![]()
![]()
(95% C.L.). In particular, our results favor the open universe in both \begin{document}$\Lambda$\end{document} ![]()
![]()
CDM and RVM. In addition, we show that the cosmological constraints of \begin{document}$\Sigma m_{\nu}=0.256^{+0.224}_{-0.234}$\end{document} ![]()
![]()
(RVM) and \begin{document}$\Sigma m_{\nu}=0.257^{+0.219}_{-0.234}$\end{document} ![]()
![]()
(\begin{document}$\Lambda$\end{document} ![]()
![]()
CDM) at 95% C.L. for the neutrino mass sum are relaxed in both models in the spatially curved universe. 相似文献
4.
In this article,we illustrate how to calculate the hadronic coupling constants of the pentaquark states with QCD sum rules based on rigorous quark-hadron quality.We then study the hadronic coupling constants of the lowest diquark-diquark-antiquark type hidden-charm pentaquark state with spin-parity J~P=1/2~-in detail,and calculate the partial decay widths.The total width Г(P_c)=14.32±3.31 MeV is compatible with the experimental value T_(P_c(4312))=9.8±2.7_(-4.5)~(+3.7) MeV from the LHCb collaboration and favors assigning the P_c(4312) to be the [ud][uc]c pentaquark state with J~P=1/2~-.The hadronic coupling constants have the relation ■,and favor the hadronic dressing mechanism.The P_c(4312) may have a diquark-diquark-antiquark type pentaquark core with the typical size of the qqq-type baryon states.The strong couplings to the meson-baryon pairs DE_c lead to some pentaquark molecule components,and the P_c(4312) may spend a rather large time as the DE_c molecular state. 相似文献
5.
The process of primordial black hole (PBH) formation is inevitably accompanied by scalar induced gravitational waves (SIGWs). The strong correlation between PBH and SIGW signals may offer a promising approach to detecting PBHs in upcoming gravitational wave experiments, such as the Laser Interferometer Space Antenna (LISA). We investigate third order SIGWs during a radiation-dominated era in the case of the monochromatic primordial power spectrum \begin{document}$ \mathcal{P}_{\zeta}=A_{\zeta}k_*\delta\left(k-k_*\right) $\end{document} ![]()
![]()
. For LISA observations, the relationships between the signal-to-noise ratio (SNR) and monochromatic primordial power spectrum are studied systematically, revealing that the effects of third order SIGWs extend the cutoff frequency from \begin{document}$ 2f_* $\end{document} ![]()
![]()
to \begin{document}$ 3f_* $\end{document} ![]()
![]()
and lead to an approximately 200% increase in the SNR for the frequency band from \begin{document}$ 10^{-5} $\end{document} ![]()
![]()
Hz to \begin{document}$ 1.6\times 10^{-3} $\end{document} ![]()
![]()
Hz, corresponding to PBHs with masses in the range \begin{document}$4\times 10^{-12}M_{\odot} \sim 10^{-7}M_{\odot}$\end{document} ![]()
![]()
. We find that there is a critical value, \begin{document}$ A_*=1.76\times 10^{-2} $\end{document} ![]()
![]()
, for the amplitude of the monochromatic primordial power spectra, such that when \begin{document}$ A_{\zeta}>A_* $\end{document} ![]()
![]()
, the energy density of third order SIGWs is larger than that of second order SIGWs. 相似文献
6.
Yong-Jin Yao Cheng-Jian Lin Lei Yang Nan-Ru Ma Dong-Xi Wang Gao-long Zhang Guang-Xin Zhang Hui-Ming Jia Feng Yang Fu-Peng Zhong Pei-Wei Wen Xiu-Bo Qin Hong-Ming Zhao 《中国物理C(英文版)》2021,45(5):054104-054104-8
Coincidence measurements of breakup fragments in reactions of~ (6,7) Li with ~(209)Bi at energies around and above the Coulomb barrier were carried out using a large solid-angle covered detector array. Through the Q values along with the relative energies of the breakup fragments, different breakup components(prompt breakups and delayed breakups) and different breakup modes(α + t, α + d, α + p, and α + α) are distinguished. A new breakup mode, α + t, is observed in ~6Li-induced reactions at energies above the Coulomb barrier. Correlations between breakup modes and breakup components as well as their variations with the incident energy are investigated. The results will help us better understand the breakup effects of weakly bound nuclei on the suppression of a complete fusion, particularly for the above-barrier energies. 相似文献
7.
Neutron–proton momentum correlation functions are constructed from a three-body photodisintegration channel, i.e., core\begin{document}$ + n + p$\end{document} ![]()
![]()
, and used to explore the spatial-time information of the non-clustering Woods–Saxon spherical structure as well as the \begin{document}$\alpha$\end{document} ![]()
![]()
-clustering structures of \begin{document}$^{12}{\rm{C}}$\end{document} ![]()
![]()
or \begin{document}$^{16}{\rm{O}}$\end{document} ![]()
![]()
based on an extended quantum molecular dynamics model. The emission time sequence of neutrons and protons is indicated by the ratio of velocity-gated neutron–proton correlation functions, demonstrating its sensitivity to \begin{document}$\alpha$\end{document} ![]()
![]()
-clustering structures. This work sheds light on a new probe for \begin{document}$\alpha$\end{document} ![]()
![]()
-clustering structures. 相似文献
8.
In this work, the characteristics of \begin{document}$2\nu\beta\beta$\end{document} ![]()
![]()
decays for six nuclei (\begin{document}$^{36}$\end{document} ![]()
![]()
Ar, \begin{document}$^{46}$\end{document} ![]()
![]()
Ca, \begin{document}$^{48}$\end{document} ![]()
![]()
Ca, \begin{document}$^{50}$\end{document} ![]()
![]()
Cr, \begin{document}$^{70}$\end{document} ![]()
![]()
Zn, and \begin{document}$^{136}$\end{document} ![]()
![]()
Xe) in a mass range from \begin{document}$A = 36$\end{document} ![]()
![]()
to \begin{document}$A = 136$\end{document} ![]()
![]()
are studied within the nuclear shell model (NSM) framework. Calculations are presented for the half-lives, nuclear matrix elements (NMEs), phase space factors (\begin{document}$G_{2\nu}$\end{document} ![]()
![]()
), and convergence of the NMEs. The theoretical results agree well with the experimental data. In addition, we predict the half-lives of \begin{document}$2\nu\beta\beta$\end{document} ![]()
![]()
decays for four nuclei. We focus on the convergence of the NMEs by analyzing the number of contributing intermediate \begin{document}$1^{+}$\end{document} ![]()
![]()
states (\begin{document}$N_{\rm{C}}$\end{document} ![]()
![]()
) for the nuclei of interest. We assume that \begin{document}$N_{\rm{C}}$\end{document} ![]()
![]()
is safely determined when the accumulated NMEs saturate 99.7% of the final calculated magnitude. From the calculations of the involved nuclei, we discover a connection between \begin{document}$N_{\rm{C}}$\end{document} ![]()
![]()
and the total number of intermediate \begin{document}$1^{+}$\end{document} ![]()
![]()
states (\begin{document}$N_{\rm{T}}$\end{document} ![]()
![]()
). According to the least squares fit, we conclude that the correlation is \begin{document}$N_{\rm{C}}=\left( 10.8\pm 1.2\right) \times N_{\rm{T}}^{\left( 0.29\pm 0.02\right)}$\end{document} ![]()
![]()
. 相似文献
9.
Systematic study of the α decay preformation factors of the nuclei around the Z = 82, N = 126 shell closures within the generalized liquid drop model
下载免费PDF全文
![点击此处可从《中国物理C(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hong-Ming Liu You-Tian Zou Xiao Pan Xiao-Jun Bao Xiao-Hua Li 《中国物理C(英文版)》2020,44(9):094106-094106-12
In this study, we systematically investigate the \begin{document}$\alpha$\end{document}
decay preformation factors, \begin{document}$P_{\alpha}$\end{document}
, and the \begin{document}$\alpha$\end{document}
decay half-lives of 152 nuclei around Z = 82, N = 126 closed shells based on the generalized liquid drop model (GLDM) with \begin{document}$P_{\alpha}$\end{document}
being extracted from the ratio of the calculated \begin{document}$\alpha$\end{document}
decay half-life to the experimental one. The results show that there is a remarkable linear relationship between \begin{document}$P_{\alpha}$\end{document}
and the product of valance protons (holes) \begin{document}$N_p$\end{document}
and valance neutrons (holes) \begin{document}$N_n$\end{document}
. At the same time, we extract the \begin{document}$\alpha$\end{document}
decay preformation factor values of the even–even nuclei around the Z = 82, N = 126 closed shells from the study of Sun \begin{document}${et\ al.}$\end{document}
[J. Phys. G: Nucl. Part. Phys., 45: 075106 (2018)], in which the \begin{document}$\alpha$\end{document}
decay was calculated by two different microscopic formulas. We find that the \begin{document}$\alpha$\end{document}
decay preformation factors are also related to \begin{document}$N_pN_n$\end{document}
. Combining with our previous studies [Sun \begin{document}${et\ al.}$\end{document}
, Phys. Rev. C, 94: 024338 (2016); Deng \begin{document}${et\ al.}$\end{document}
, ibid. 96: 024318 (2017); Deng \begin{document}${et\ al.}$\end{document}
, ibid. 97: 044322 (2018)] and that of Seif \begin{document}${et\ al.,}$\end{document}
[Phys. Rev. C, 84: 064608 (2011)], we suspect that this phenomenon of linear relationship for the nuclei around the above closed shells is model-independent. This may be caused by the effect of the valence protons (holes) and valence neutrons (holes) around the shell closures. Finally, using the formula obtained by fitting the \begin{document}$\alpha$\end{document}
decay preformation factor data calculated by the GLDM, we calculate the \begin{document}$\alpha$\end{document}
decay half-lives of these nuclei. The calculated results agree with the experimental data well. 相似文献
10.
Zhishuai Ge Gen Zhang Shihui Cheng Yu. S. Tsyganov Feng-Shou Zhang 《中国物理C(英文版)》2020,44(10):104102-104102-17
The \begin{document}$\alpha$\end{document} ![]()
![]()
-decay properties of even-Z nuclei with Z = 120, 122, 124, 126 are predicted. We employ the generalized liquid drop model (GLDM), Royer's formula, and universal decay law (UDL) to calculate the \begin{document}$\alpha$\end{document} ![]()
![]()
-decay half-lives. By comparing the theoretical calculations with the experimental data of known nuclei from Fl to Og, we confirm that all the employed methods can reproduce the \begin{document}$\alpha$\end{document} ![]()
![]()
-decay half-lives well. The preformation factor \begin{document}$P_{\alpha}$\end{document} ![]()
![]()
and \begin{document}$\alpha$\end{document} ![]()
![]()
-decay energy \begin{document}$Q_{\alpha}$\end{document} ![]()
![]()
show that \begin{document}$^{298,304,314,316,324,326,338,348}$\end{document} ![]()
![]()
120, \begin{document}$^{304,306,318,324,328,338}$\end{document} ![]()
![]()
122, and \begin{document}$^{328,332,340,344}$\end{document} ![]()
![]()
124 might be stable. The \begin{document}$\alpha$\end{document} ![]()
![]()
-decay half-lives show a peak at Z = 120, N = 184, and the peak vanishes when Z = 122, 124, 126. Based on detailed analysis of the competition between \begin{document}$\alpha$\end{document} ![]()
![]()
-decay and spontaneous fission, we predict that nuclei nearby N = 184 undergo \begin{document}$\alpha$\end{document} ![]()
![]()
-decay. The decay modes of \begin{document}$^{287-339}$\end{document} ![]()
![]()
120, \begin{document}$^{294-339}$\end{document} ![]()
![]()
122, \begin{document}$^{300-339}$\end{document} ![]()
![]()
124, and \begin{document}$^{306-339}$\end{document} ![]()
![]()
126 are also presented. 相似文献
11.
The self-consistent mean field approximation of the two-flavor NJL model,with a free parameter a to reflect the competition between the "direct" channel and the "exchange" channel,is employed to study the QCD phase structure at finite iso spin chemical potential μ_I,finite bary on chemical potential μ_B and finite temperature T,and especially to study the location of the QCD critical point.Our results show that in order to match the corresponding lattice results of iso spin density and energy density,the contributions of the "exchange" channel need to be considered in the framework of the NJL model,and a weighting factor α=0.5 should be taken.It is also found that for fixed isospin chemical potentials,the lower temperature of the phase transition is obtained with increasing a in the T-μ_I plane,and the largest difference of the phase transition temperature with different a's appears at μ_I~1.5 mπ.At μ_I=0 the temperature of the QCD critical end point(CEP) decreases with increasing a,while the critical baryon chemical potential increases.At high isospin chemical potential(μ_I=500 MeV),the temperature of the QCD tricritical point(TCP) increases with increasing a,and in the low temperature regions the system will transition from the pion superfluidity phase to the normal phase as μ_B increases.At low density,the critical temperature of the QCD phase transition with different a's rapidly increases with μ_I at the beginning,and then increases smoothly around μ_I 300 MeV.In the high baryon density region,the increase of the iso spin chemical potential will raise the critical baryon chemical potential of the phase transition. 相似文献
12.
Analysis of the strong decays of Pc(4312) as a pentaquark molecular state with QCD sum rules
下载免费PDF全文
![点击此处可从《中国物理C(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In this article, we tentatively assign \begin{document}$P_c(4312)$\end{document}
to be the \begin{document}$\bar{D}\Sigma_c$\end{document}
pentaquark molecular state with the spin-parity \begin{document}$J^P={\frac{1}{2}}^-$\end{document}
, and discuss the factorizable and non-factorizable contributions in the two-point QCD sum rules for the \begin{document}$\bar{D}\Sigma_c$\end{document}
molecular state in detail to prove the reliability of the single pole approximation in the hadronic spectral density. We study its two-body strong decays with the QCD sum rules, and special attention is paid to match the hadron side with the QCD side of the correlation functions to obtain solid duality. We obtain the partial decay widths \begin{document}$\Gamma\left(P_c(4312)\to \eta_c p\right)=0.255\,\,{\rm{MeV}}$\end{document}
and \begin{document}$\Gamma\left(P_c(4312)\to J/\psi p\right)=9.296^{+19.542}_{-9.296}\,\,{\rm{MeV}}$\end{document}
, which are compatible with the experimental value of the total width, and support assigning \begin{document}$P_c(4312)$\end{document}
to be the \begin{document}$\bar{D}\Sigma_c$\end{document}
pentaquark molecular state. 相似文献
13.
Possibility of observation of hidden-bottom pentaquark resonances in bottomonium photoproduction on protons and nuclei near threshold
下载免费PDF全文
![点击此处可从《中国物理C(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
E. Ya. Paryev 《中国物理C(英文版)》2020,44(10):104101-104101-11
We study the \begin{document}$\Upsilon(1S)$\end{document} ![]()
![]()
meson photoproduction on protons and nuclei at near-threshold center-of-mass energies below 11.4 GeV (or at the corresponding photon laboratory energies \begin{document}$E_{\gamma}$\end{document} ![]()
![]()
below 68.8 GeV). We calculate the absolute excitation functions for the nonresonant and resonant photoproduction of \begin{document}$\Upsilon(1S)$\end{document} ![]()
![]()
mesons off protons at incident photon laboratory energies of 63-68 GeV by considering direct (\begin{document}${\gamma}p \to {\Upsilon(1S)}p$\end{document} ![]()
![]()
) and two-step (\begin{document}${\gamma}p \to P^+_b(11080) \to {\Upsilon(1S)}p$\end{document} ![]()
![]()
, \begin{document}${\gamma}p \to P^+_b(11125) \to {\Upsilon(1S)}p$\end{document} ![]()
![]()
, \begin{document}${\gamma}p \to P^+_b(11130) \to {\Upsilon(1S)}p$\end{document} ![]()
![]()
) \begin{document}$\Upsilon(1S)$\end{document} ![]()
![]()
production channels within different scenarios for the nonresonant total cross section of the elementary reaction \begin{document}${\gamma}p \to {\Upsilon(1S)}p$\end{document} ![]()
![]()
and for branching ratios of the decays \begin{document}$P^+_b(11080) \to {\Upsilon(1S)}p$\end{document} ![]()
![]()
, \begin{document}$P^+_b(11125) \to {\Upsilon(1S)}p$\end{document} ![]()
![]()
, and \begin{document}$P^+_b(11130) \to {\Upsilon(1S)}p$\end{document} ![]()
![]()
. We also calculate an analogous function for the photoproduction of \begin{document}$\Upsilon(1S)$\end{document} ![]()
![]()
mesons on the 12C and 208Pb target nuclei in the near-threshold center-of-mass beam energy region of 9.0-11.4 GeV by considering the respective incoherent direct (\begin{document}${\gamma}N \to {\Upsilon(1S)}N$\end{document} ![]()
![]()
) and two-step (\begin{document}${\gamma}p \to P^+_b(11080) \to {\Upsilon(1S)}p$\end{document} ![]()
![]()
, \begin{document}${\gamma}p \to P^+_b(11125) \to {\Upsilon(1S)}p$\end{document} ![]()
![]()
, \begin{document}${\gamma}p \to P^+_b(11130) \to {\Upsilon(1S)}p$\end{document} ![]()
![]()
and \begin{document}${\gamma}n \to P^0_b$\end{document} ![]()
![]()
\begin{document}$ (11080) \to{\Upsilon(1S)}n $\end{document} ![]()
![]()
, \begin{document}${\gamma}n \to P^0_b(11125) \to {\Upsilon(1S)}n$\end{document} ![]()
![]()
, \begin{document}${\gamma}n \to P^0_b(11130) \to {\Upsilon(1S)}n$\end{document} ![]()
![]()
) \begin{document}$\Upsilon(1S)$\end{document} ![]()
![]()
) production processes using a nuclear spectral function approach. We demonstrate that a detailed scan of the\begin{document}$\Upsilon(1S)$\end{document} ![]()
![]()
total photoproduction cross section on proton and nuclear targets in the near-threshold energy region in future high-precision experiments at the proposed high-luminosity electron-ion colliders EIC and EicC in the US and China should provide a definite result for or against the existence of the nonstrange hidden-bottom pentaquark states\begin{document}$P_{bi}^+$\end{document} ![]()
![]()
and \begin{document}$P_{bi}^0$\end{document} ![]()
![]()
(\begin{document}$i$\end{document} ![]()
![]()
=1, 2, 3) as well as clarify their decay rates. 相似文献
14.
Measuring the pionic structure function is of high interest, as it provides a new area for understanding the strong interaction among quarks and testing QCD predictions. To this end, we investigate the feasibility and expected impact of a possible experiment at EicC(Electron-ion collider in China). We show the simulation results on the statistical precision of an EicC measurement, based on the model of leading neutron tagged DIS process and the parton distribution functions of the pion from JAM18 global analysis. The simulation shows that at EicC, the kinematics cover the x π range from 0.01 to 1, and the Q~2 range from 1 to 50 GeV~2, within the acceptable statistical uncertainty. Assuming an integrated luminosity of 50 fb~(-1), in the low-Q~2 region( 10 GeV~2), the Monte Carlo data show that the suggested measurement in the whole x π range reaches very high precision( 3%). To perform such an experiment, only the addition of a far-forward neutron calorimeter is needed. 相似文献
15.
B. Mukeru 《中国物理C(英文版)》2021,45(5):054107-054107-7
Proton-halo breakup behavior in the \begin{document}$ \varepsilon_0\to 0 $\end{document} ![]()
![]()
limit (where \begin{document}$ \varepsilon_0 $\end{document} ![]()
![]()
is the ground-state binding energy) is studied around the Coulomb barrier in the \begin{document}$ ^8{\rm{B}}+{}^{58}{\rm{Ni}} $\end{document} ![]()
![]()
reaction for the first time. For practical purposes, apart from the experimental \begin{document}$ ^8{\rm{B}} $\end{document} ![]()
![]()
binding energy of 137 keV, three more arbitrarily chosen values (1, 0.1, 0.01 keV) are considered. It is first shown that the Coulomb barrier between the core and the proton prevents the \begin{document}$ ^7{\rm{Be}}+p $\end{document} ![]()
![]()
system from reaching the state of an open proton-halo system, which, among other factors, would require the ground-state wave function to extend to infinity in the asymptotic region, as \begin{document}$ \varepsilon_0\to 0 $\end{document} ![]()
![]()
. The elastic scattering cross section, which depends on the density of the ground-state wave function, is found to have a negligible dependence on the binding energy in this limit. The total, Coulomb and nuclear breakup cross sections are all reported to increase significantly from \begin{document}$ \varepsilon_0 = 137 $\end{document} ![]()
![]()
to 1.0 keV, and converge to their maximum values as \begin{document}$ \varepsilon_0\to 0 $\end{document} ![]()
![]()
. This increase is mainly understood as coming from a longer tail of the ground-state wave function for \begin{document}$ \varepsilon_0\leqslant 1.0 $\end{document} ![]()
![]()
keV, compared to that for \begin{document}$ \varepsilon_0 = 137 $\end{document} ![]()
![]()
keV. It is also found that the effect of the continuum-continuum couplings is to slightly delay the convergence of the breakup cross section. The analysis of the reaction cross section indicates a convergence of all the breakup observables as \begin{document}$ \varepsilon_0\to 0 $\end{document} ![]()
![]()
. These results provide a better sense of the dependence of the breakup process on the breakup threshold. 相似文献
16.
To solve the cosmological constant fine tuning problem, we investigate an \begin{document}$(n+1)$\end{document} ![]()
![]()
-dimensional generalized Randall-Sundrum brane world scenario with two \begin{document}$(n-1)$\end{document} ![]()
![]()
-branes instead of two 3-branes. Adopting an anisotropic metric ansatz, we obtain the positive effective cosmological constant \begin{document}$\Omega_{\rm eff}$\end{document} ![]()
![]()
of order \begin{document}$10^{-124}$\end{document} ![]()
![]()
and only require a solution \begin{document}$\simeq50-80$\end{document} ![]()
![]()
. Meanwhile, both the visible and hidden branes are stable because their tensions are positive. Therefore, the fine tuning problem can be solved quite well. Furthermore, the Hubble parameter \begin{document}$H_{1}(z)$\end{document} ![]()
![]()
as a function of redshift \begin{document}$z$\end{document} ![]()
![]()
is in good agreement with the cosmic chronometers dataset. The evolution of the universe naturally shifts from deceleration to acceleration. This suggests that the evolution of the universe is intrinsically an extra-dimensional phenomenon. It can be regarded as a dynamic model of dark energy that is driven by the evolution of the extra dimensions on the brane. 相似文献
17.
Nan Zhang Ya-Bo Wu Jun-Wang Lu Chu-Wen Sun Li-Jie Shou Hai-Zhou Xu 《中国物理C(英文版)》2020,44(9):095107-095107-8
Based on the dynamics of single scalar field slow-roll inflation and the theory of reheating, we investigate the generalized natural inflationary (GNI) model. We introduce constraints on the scalar spectral index \begin{document}$n_{s}$\end{document} ![]()
![]()
and the tensor-to scalar ratio r for the \begin{document}$\Lambda$\end{document} ![]()
![]()
CDM \begin{document}$+r$\end{document} ![]()
![]()
model, according to the latest data from Planck 2018 TT, TE, EE+low E+lensing (P18) and BICEP2/Keck 2015 season (BK15), i.e., with \begin{document}$n_{s}=0.9659\pm0.0044$\end{document} ![]()
![]()
at 68% confidence level (CL), and \begin{document}$r<0.0623$\end{document} ![]()
![]()
at 95% CL. We find that the GNI model is favored by P18 and BK15 in the ranges \begin{document}$\log_{10}(f/M_{p})= 0.62^{+0.17}_{-0.18}$\end{document} ![]()
![]()
and \begin{document}$m=0.35^{+0.13}_{-0.23}$\end{document} ![]()
![]()
at 68% CL. In addition, the corresponding predictions of generalized and two-phase reheating are discussed. It follows that the parameter m has significant effect on the model behavior. 相似文献
18.
The \begin{document}$ \alpha $\end{document} ![]()
![]()
-particle preformation factors of nuclei above doubly magic nuclei \begin{document}$ ^{100} $\end{document} ![]()
![]()
Sn and \begin{document}$ ^{208} $\end{document} ![]()
![]()
Pb are investigated within the generalized liquid drop model. The results show that the \begin{document}$ \alpha $\end{document} ![]()
![]()
-particle preformation factors of nuclei near self-conjugate doubly magic \begin{document}$ ^{100} $\end{document} ![]()
![]()
Sn are significantly larger than those of analogous nuclei just above \begin{document}$ ^{208} $\end{document} ![]()
![]()
Pb, and they will be enhanced as the nuclei move towards the \begin{document}$ N = Z $\end{document} ![]()
![]()
line. The proton–neutron correlation energy \begin{document}$ E_{p-n} $\end{document} ![]()
![]()
and two protons–two neutrons correlation energy \begin{document}$ E_{2p-2n} $\end{document} ![]()
![]()
of nuclei near \begin{document}$ ^{100} $\end{document} ![]()
![]()
Sn also exhibit a similar situation, indicating that the interactions between protons and neutrons occupying similar single-particle orbitals could enhance the \begin{document}$ \alpha $\end{document} ![]()
![]()
-particle preformation factors and result in superallowed \begin{document}$ \alpha $\end{document} ![]()
![]()
decay. This also provides evidence of the significant role of the proton–neutron interaction on \begin{document}$ \alpha $\end{document} ![]()
![]()
-particle preformation. Also, the linear relationship between \begin{document}$ \alpha $\end{document} ![]()
![]()
-particle preformation factors and the product of valence protons and valence neutrons for nuclei around \begin{document}$ ^{208} $\end{document} ![]()
![]()
Pb is broken in the \begin{document}$ ^{100} $\end{document} ![]()
![]()
Sn region because the \begin{document}$ \alpha $\end{document} ![]()
![]()
-particle preformation factor is enhanced when a nucleus near \begin{document}$ ^{100} $\end{document} ![]()
![]()
Sn moves towards the \begin{document}$ N = Z $\end{document} ![]()
![]()
line. Furthermore, the calculated \begin{document}$ \alpha $\end{document} ![]()
![]()
decay half-lives fit well with the experimental data, including the recent observed self-conjugate nuclei \begin{document}$ ^{104} $\end{document} ![]()
![]()
Te and \begin{document}$ ^{108} $\end{document} ![]()
![]()
Xe [Phys. Rev. Lett. 121, 182501 (2018)]. 相似文献
19.
Surbhi Gupta Ridham Bakshi Suram Singh Arun Bharti G. H. Bhat J. A. Sheikh 《中国物理C(英文版)》2020,44(7):074108-074108-10
In this study, the multi-quasiparticle triaxial projected shell model (TPSM) is applied to investigate \begin{document}$\gamma$\end{document} ![]()
![]()
-vibrational bands in transitional nuclei of \begin{document}$^{118-128}{\rm{Xe}}$\end{document} ![]()
![]()
. We report that each triaxial intrinsic state has a \begin{document}$\gamma$\end{document} ![]()
![]()
-band built on it. The TPSM approach is evaluated by the comparison of TPSM results with available experimental data, which shows a satisfactory agreement. The energy ratios, B(E2) transition rates, and signature splitting of the \begin{document}$\gamma$\end{document} ![]()
![]()
-vibrational band are calculated. 相似文献
20.
Nucleon effective mass splitting and density-dependent symmetry energy effects on elliptic flow in heavy ion collisions at E_(lab)= 0.09 ~ 1.5 GeV/nucleon
下载免费PDF全文
![点击此处可从《中国物理C(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Luyao Tong Pengcheng Li Fupeng Li Yongjia Wang Qingfeng Li Fanxin Liu 《中国物理C(英文版)》2020,44(7):074103-074103-8
By incorporating an iso spin-dependent form of the momentum-dependent potential in the ultra-relativistic quantum molecular dynamics(UrQMD) model,we systematically investigate effects of the neutron-proton effective mass splitting m*_(n-p)=m*_n-m*_p/m and the density-dependent nuclear symmetry energy E_(sym)(ρ) on the elliptic flow v_2 in~(197)Au+~(197) Au collisions at beam energies from 0.09 to 1.5 GeV/nucleon.It is found that at higher beam energies(≥0.25 GeV/nucleon) with the approximately 75 MeV difference in slopes of the two different E_(sym)(ρ),and the variation of m*_(n-p) ranging from-0.03 to 0.03 at saturation density with isospin asymmetry δ=(ρ_n-ρ_p)/ρ-0.2,the E_(sym)(ρ) has a stronger influence on the difference in v_2 between neutrons and protons,i.e.,v_2~n-v_2~p,than m*_(n-p) has.Meanwhile,at lower beam energies(≤0.25 GeV/nucleon),v_2~n-v_2~p is sensitive to both the E_(sym)(ρ) and the m*_(n-p).Moreover,the influence of m*_(n-p) on v_2~n-v_2~p is more evident with the parameters of this study when using the soft,rather than stiff,symmetry energy. 相似文献