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Published:   , doi: 10.1088/1674-1137/44/9/093104
Abstract:
Recently a vector charmonium-like state \begin{document}$Y(4626)$\end{document} was observed in the portal of \begin{document}$D^+_sD_{s1}(2536)^-$\end{document}. It intrigues an active discussion on the structure of the resonance because it has obvious significance for gaining a better understanding on its hadronic structure with suitable inner constituents. It indeed concerns the general theoretical framework about possible structures of exotic states. Since the mass of \begin{document}$Y(4626)$\end{document} is slightly above the production threshold of \begin{document}$D^+_s\bar D_{s1}(2536)^-$\end{document} whereas below that of \begin{document}$D^ * _s\bar D_{s1}(2536)$\end{document} with the same quark contents as that of \begin{document}$D^+_s\bar D_{s1}(2536)^-$\end{document}, it is natural to conjecture \begin{document}$Y(4626)$\end{document} to be a molecular state of \begin{document}$D^{ * }_s\bar D_{s1}(2536)$\end{document}, as suggested in literature. Confirming or negating this allegation would shed light on the goal we concern. We calculate the mass spectrum of a system composed of a vector meson and an axial vector i.e. \begin{document}$D^ * _s\bar D_{s1}(2536)$\end{document} within the framework of the Bethe-Salpeter equations. Our numerical results show that the dimensionless parameter \begin{document}$\lambda$\end{document} in the form factor which is phenomenologically introduced to every vertex, is far beyond the reasonable range for inducing an even very small binding energy \begin{document}$\Delta E$\end{document}. It implies that the \begin{document}$D^ * _s\bar D_{s1}(2536)$\end{document} system cannot exist in the nature as a hadronic molecule in this model, so that we may not think the resonance \begin{document}$Y(4626)$\end{document} to be a bound state of \begin{document}$D^ * _s\bar D_{s1}(2536)$\end{document}, but something else, for example a tetraquark and etc.
Published:   , doi: 10.1088/1674-1137/44/9/093107
Abstract:
Based on the prediction of a \begin{document}$D^*\bar{D}^*$\end{document} molecular state \begin{document}$Z_c(4000)$\end{document} with isospin \begin{document}$I=1$\end{document} in the coupled channel approach, we suggest to search for this state in the reaction \begin{document}$B^- \to J/\psi \rho^0 K^-$\end{document}. By taking into account the final state interactions of \begin{document}$J/\psi \rho$\end{document} and \begin{document}$D^{*0}\bar{D}^{*0}$\end{document}, and the contribution from the \begin{document}$K_1(1270)$\end{document} resonance, we find that the \begin{document}$J/\psi\rho$\end{document} mass distribution shows a peak around 4000 MeV, which could be associated to the \begin{document}$D^*\bar{D}^*$\end{document} molecular state \begin{document}$Z_c(4000)$\end{document}. Searching for the \begin{document}$Z_c(4000)$\end{document} in the reaction \begin{document}$B^- \to J/\psi \rho^0 K^-$\end{document} is crucial to understand the internal structures of the exotic hadrons, and our predictions can be tested by the Belle II and LHCb in future.
Published:
Abstract:
Neutron-proton momentum correlation functions are constructed from three-body photodisintegration channel, i.e. \begin{document}$core + n + p$\end{document} and used to to explore the spatial-time information of the non-clustering Wood-Saxon spheric structure as well as \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 neutron and proton is indicated by the ratio of velocity-gated neutron-proton correlation functions, demonstrating its sensitivity to \begin{document}$\alpha$\end{document}-clustering structure. The work sheds light on a new probe for \begin{document}$\alpha$\end{document}-clustering structure.
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Abstract:
Enthused by the availability of the recent experimental as well as theoretical data on the energy levels of odd-mass 151-161Pm and odd-odd 154,156Pm, we applied the theoretical framework of the Projected Shell Model with the aim to further understand the nuclear structure of these nuclei. The calculations have reproduced well the experimental data reported on the yrast bands of these isotopes by assuming an axial (prolate) deformation of ~0.3. Other properties along the yrast line, such as transition energies, transition probabilities, etc., have also been discussed. Band diagrams are plotted to understand their intrinsic multi-quasiparticle structure which turn out to be dominated by 1-quasiparticle bands for the odd-mass Pm isotopes and 2-quasiparticle bands for doubly-odd Pm isotopes under study. The present study has not only confirmed the recently reported experimental/ theoretical data but also extended the already available information on the energy levels and added new information on the reduced transition probabilities.
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Abstract:
We reduce all the most complicated Feynman integrals in two-loop five-light-parton scattering amplitudes to basic master integrals, while other integrals can be reduced even more easily. Our results are expressed as systems of linear relations in block-triangular form, which are very efficient for numerical calculation. Our results are crucial for complete next-to-next-to-leading order QCD calculation for three jets, photons, or hadrons production at hadron colliders. In order to find out the block-triangular relations, we develop a new method which is efficient and general. The method may provide a practical solution for the bottleneck problem of reducing multiloop multiscale integrals.
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Abstract:
High transverse momentum (\begin{document}$p_T$\end{document}) particle production is suppressed due to parton (jet) energy loss in the hot dense medium created in relativistic heavy-ion collisions. Redistribution of energy at low-to-modest \begin{document}$p_T$\end{document} has been elusive to measure because of large anisotropic backgrounds. We report a data-driven method for background evaluation and subtraction, exploiting the away-side pseudorapidity gaps, to measure the jetlike correlation shape in Au+Au collisions at \begin{document}$\sqrt{s_{\rm{NN}}} = 200$\end{document} GeV with the STAR experiment. The correlation shapes, for trigger particle \begin{document}$p_T>3\;{\rm{GeV}}/c$\end{document} and various associated particle \begin{document}$p_T$\end{document} ranges within \begin{document}$0.5<p_T<10\;{\rm{GeV}}/c$\end{document}, are consistent with Gaussians and their widths are found to increase with centrality. The results indicate jet broadening in the medium created in central heavy-ion collisions.
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Abstract:
By studying the \begin{document}$\eta_c$\end{document} exclusive decay to double glueballs, we introduce a model to mimic phenomenologically the gluon-pair-vacuum interaction vertices, namely the \begin{document}$0^{++}$\end{document} model. Based on this model, we study glueball production in pseudoscalar quarkonium decays, explicitly \begin{document}$\eta_c \to f_0(1500)\eta(1405)$\end{document}, \begin{document}$\eta_b\to f_0(1500)\eta(1405)$\end{document} and \begin{document}$\eta_b\to f_0(1710)\eta(1405)$\end{document} processes. Among them \begin{document}$f_0(1500)$\end{document} and \begin{document}$f_0(1710)$\end{document} are well-known scalars possessing large glue components and \begin{document}$\eta(1405)$\end{document} is a potential candidate for pseudoscalar glueball. The preliminary calculation results indicate that these processes are marginally accessible in the presently running experiments BES III, BELLE II, and LHCb.
Published:   , doi: 10.1088/1674-1137/44/9/094101
Abstract:
We develop a covariant kinetic theory for massive fermions in curved spacetime and external electromagnetic field based on quantum field theory. We derive four coupled semi-classical kinetic equations accurate at \begin{document}$O(\hbar)$\end{document}, which describe the transports of particle number and spin degrees of freedom. The relation with the chiral kinetic theory is discussed. As an application, we study the spin polarization in the presence of finite Riemann curvature and electromagnetic field in both local and global equilibrium states.
Published:   , doi: 10.1088/1674-1137/44/9/095102
Abstract:
Quasinormal modes (QNMs) for massless and massive Dirac perturbations of Born-Infeld black holes (BHs) in higher dimensions are investigated. Solving the corresponding master equation in accordance hypergeometric functions and the QNMs are evaluated. We pay more attention to discuss the relationships between QNM frequencies and spacetime dimension. Meanwhile, we discuss the stability of the Born-Infeld BH by calculating the temporal evolution of the perturbation field. Both the perturbation frequencies and the decay rate increase with the enhance of the dimension of spacetime n. This shows that the Born-Infeld BHs become more and more unstable in higher dimensions. Furthermore, the traditional finite difference method is improved, so that it can be used to calculate massive Dirac field. And we elucidate the dynamical evolution of Born-Infeld BHs in massive Dirac field. Because the number of extra dimensions is related to the string scale, there is a relationship between spacetime dimension n and the properties of Born-Infeld BHs which might be advantageous to the development of extra-dimensional brane worlds and string theory.
Published:   , doi: 10.1088/1674-1137/44/9/094108
Abstract:
In this work, we have performed Skyrme density functional theory (DFT) calculations of nuclei around 132Sn to study whether the abnormal odd-even staggering (OES) behavior of binding energies around N = 82 can be reproduced. With the Skyrme force SLy4 and SkM*, we test the volume- and surface-type of pairing forces, and also the intermediate between these two pairing forces, in the Hartree-Fock-Bogoliubov (HFB) approximation with or without the Lipkin-Nogami (LN) approximation or particle number projection after the convergence of HFBLN (PLN). The UNEDF parameter sets are also used. The trend of the neutron OES against the neutron number or proton number does not change much, by tuning the density dependence of the pairing force. And, for the pairing force which is more favoured at the nuclear surface, the larger mass OES is obtained, and vice versa. It seems that the mix between the volume and surface pairing can give better agreement with data. In the studies of the OES, larger ratio of the surface to volume pairing might be favoured. And, in most cases, the OES given by the HFBLN approximation agrees better with the experimental data. We found that both the Skyrme and pairing forces can influence the OES behavior. The mass OES calculated by the UNEDF DFT is explictly smaller than the experimental one. UNEDF1 and UNEDF2 force can reproduce the experimental trend of the abnormal OES around 132Sn. The neutron OES of the tin isotopes given by SkM* force agrees better with the experimental one than that by SLy4 force, in most cases. Both SLy4 and SkM* DFT have difficulties to reproduce the abnormal OES around 132Sn. By the PLN method, the systematics of OES is improved for several combinations of the Skyrme and pairing forces.
Published:   , doi: 10.1088/1674-1137/44/9/091001
Abstract:
We investigate the invariant-mass distribution of top-quark pairs near the 2mt threshold, which has strong impact on the determination of the top-quark mass mt. We show that higher-order nonrelativistic corrections lead to large contributions which are not included in the state-of-the-art theoretical predictions. We derive a factorization formula to resum such corrections to all orders in the strong-coupling, and calculate necessary ingredients to perform the resummation at next-to-leading power. We combine the resummation with fixed-order results and present phenomenologically relevant numeric results. We find that the resummation effect significantly enhances the differential cross section in the threshold region, and makes the theoretical prediction more compatible with experimental data. We estimate that using our prediction in the determination of mt will lead to a value closer to the result of direct measurement.
Published:   , doi: 10.1088/1674-1137/44/9/095103
Abstract:
Banerjee-Ghosh's work shows that the singularity problem can be naturally avoided by the fact that the black hole evaporation stops at the remnant mass greater than the critical mass when including the GUP effects with the first- and second-order corrections. In this paper, we first follow their steps to reexamine the Banerjee-Ghosh's work, but find an interesting result that the remnant mass is always equal to the critical mass at the final stage of the black hole evaporation with the inclusion of the GUP effects. Then, we use the Hossenfelder's GUP, i.e. another GUP model with higher-order corrections, to restudy the final evolution behavior of the black hole evaporation, and confirm the intrinsic self-consistency between the black hole remnant and critical mass once more. In both cases, we also find that the thermodynamic quantities are not singular at the final stage of the black hole evaporation.
Published:   , doi: 10.1088/1674-1137/44/9/093102
Abstract:
We investigate the strongly coupled minimal walking technicolor model (MWT) in the framework of a bottom-up holographic model, where the global \begin{document}$SU(4)$\end{document} symmetry breaks to \begin{document}$SO(4)$\end{document} subgroup. In the holographic model, we found that 125 GeV composite Higgs particles and small Peskin-Takeuchi S parameter can be achieved simultaneously. In addition, the model predicts a large number of particles at the TeV scale, including dark matter candidate Technicolor Interacting Massive Particles (TIMPs). If we consider the dark matter nuclear spin-independent cross-section in the range of \begin{document}$10^{-45}\sim 10 ^ {-48} \;{\rm{cm}}^2$\end{document}, which can be detected by future experiments, the mass range of TIMPs predicted by the holographic technicolor model is \begin{document}$2 \sim 4$\end{document} TeV.
Published:   , doi: 10.1088/1674-1137/44/9/094103
Abstract:
We study chiral magnetic effect in collisions of AuAu, RuRu and ZrZr at \begin{document}$\sqrt{s_{\rm{NN}}}=200\;{\rm{GeV}}$\end{document}. The axial charge evolution is modeled with stochastic hydrodynamics and geometrical quantities are calculated with Monte Carlo Glauber model. By adjusting the relaxation time of magnetic field, we find our results in good agreement with background subtracted data for AuAu collisions at the same energy. We also make prediction for RuRu and ZrZr collisions. We find a weak centrality dependence of initial chiral imbalance, which implies the centrality dependence of chiral magnetic effect signal comes mainly from those of magnetic field and volume factor. Our results also show an unexpected dependence on system size: while the system of AuAu has larger chiral imbalance and magnetic field, it turns out to have smaller signal for chiral magnetic effect due to the larger volume suppression factor.
Published:   , doi: 10.1088/1674-1137/44/9/095106
Abstract:
Based on the idea of the black hole molecule proposed in [Phys. Rev. Lett. 115 (2015) 111302], in this paper, by choosing the appropriate extensive variables, we have solved the puzzle whether the molecules of the Reissner-Nordström black hole is an interaction or not through the Ruppeiner thermodynamic geometry. Our results show that the Reissner-Nordström black hole is indeed an interaction system that may be dominated by repulsive interaction. More importantly, with the help of a new quantity, thermal-charge density, we describe the fine micro-thermal structures of the Reissner-Nordström black hole in detail. It presents three different phases, the free, interactive and balanced phases. The thermal-charge density plays a role similar to the order parameter, and the back hole undergoes a new phase transition between the free phase and interactive phase. The competition between the free phase and interactive phase exists, which leads to the extreme behavior of the temperature of the Reissner-Nordström black hole. For extreme Reissner-Nordström black hole, the whole system is completely in the interactive phase. What is more significant is that we provide the thermodynamic micro-mechanism for the formation of the naked singularity of the Reissner-Nordström black hole.
Published:   , doi: 10.1088/1674-1137/44/9/095105
Abstract:
The ambition of the present work is to highlight the phenomena of strong gravitational lensing and deflection angle for the photons coupling with Weyl tensor in a Kiselev black hole. Here, we have extended the prior work of Chen and Jing [1] for Schwarzschild black hole to Kiselev black hole. For this purpose, the equation of motion for the photons coupled to Weyl tensor, null geodesic and equation of photon sphere in a Kiselev black hole spacetime have been formulated. It is found that the equation of motion of the photons depends not only on the coupling between photon and Weyl tensor, but also on the polarization direction of the photons. There is a critical value of the coupling parameter \begin{document}$\alpha$\end{document} for existence of the marginally circular photon orbit outside the event horizon, which depends on the parameters of black hole and the polarization direction of photons. Further, the polarization directions of coupled photon and the coupling parameter \begin{document}$\alpha$\end{document}, both modify the features of the photon sphere, the angle of deflection and the functions \begin{document}$(\bar{a}$\end{document} and \begin{document}$\bar{b})$\end{document} for the strong gravitational lensing in Kiselev black hole spacetime. In addition to this, the observable gravitational lensing quantities and the shadows of the Kiselev black hole spacetime are presented in detail.
Published:   , doi: 10.1088/1674-1137/44/9/094106
Abstract:
In this work, we systematically study the \begin{document}$\alpha$\end{document} decay preformation factors \begin{document}$P_{\alpha}$\end{document} and \begin{document}$\alpha$\end{document} decay half-lives of 152 nuclei around Z = 82, N = 126 closed shells based on a generalized liquid drop model while \begin{document}$P_{\alpha}$\end{document} is 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 an obvious 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 factors values of even-even nuclei around Z = 82, N = 126 closed shells from the work 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 preformation factors can be 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 works [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 the work 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 those closed shells is model independent. It 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 generalized liquid drop model (GLDM), we calculate the \begin{document}$\alpha$\end{document} decay half-lives of these nuclei. The calculated results are agree with the experimental data well.
Published:   , doi: 10.1088/1674-1137/44/8/083107
Abstract:
We study the rare decays \begin{document}$\Lambda_b \rightarrow \Lambda l^+ l^-~(l=e,\mu, \tau)$\end{document} in the Bethe-Salpeter equation approach. We find that the branching ratio \begin{document}$Br(\Lambda_b \rightarrow \Lambda \mu^+ \mu^-)\times 10^{6} = 1.051 \sim 1.098$\end{document} in our model. This result agrees with the experimental data well. In the same parameter regions, we find that the branching ratio \begin{document}$Br(\Lambda_b \rightarrow \Lambda e^+ e^-(\tau^+ \tau^-) )\times 10^{6} = 0.252 \sim 0.392 ~(0.286 \sim 0.489)$\end{document}.
Published:   , doi: 10.1088/1674-1137/44/8/084104
Abstract:
With partially restored isospin symmetry, we calculate the nuclear matrix element for a special decay mode of 2νββ (two neutrino double beta decay) – the decay to the first 2+ excited states. With the realistic CD-Bonn nuclear force, we analyze the dependence of the nuclear matrix elements on the iso-vector and iso-scalar parts of proton-neutron particle-particle interaction. The dependence on the different nuclear matrix element is observed and the results are explained. We also give the phase space factors with numerical electron wave functions and properly chosen excitation energies. Finally we give our results for the half-lives of this decay mode for different nuclei.
Published:   , doi: 10.1088/1674-1137/44/8/084105
Abstract:
The relativistic mean field theory with the Green's function method is taken to study the single-particle resonant states. Different from our previous work [Phys.Rev.C 90,054321(2014)], the resonant states are identified by searching for the poles of Green's function or the extremes of the density of states. This new approach is very effective for all kinds of resonant states, no matter it is broad or narrow. The dependence on the space size for the resonant energies, widths, and the density distributions in the coordinate space has been checked and it is found very stable. Taking \begin{document}$^{120}$\end{document}Sn as an example, four new broad resonant states \begin{document}$2g_{7/2}$\end{document}, \begin{document}$2g_{9/2}$\end{document}, \begin{document}$2h_{11/2}$\end{document} and \begin{document}$1j_{13/2}$\end{document} are observed, and also the accuracy for the width of the very narrow resonant state \begin{document}$1h_{9/2}$\end{document} is highly improved to be \begin{document}$1\times 10^{-8}$\end{document} MeV. Besides, our results are very close to those by the complex momentum representation method and the complex scaling method.
Published:   , doi: 10.1088/1674-1137/44/8/083103
Abstract:
The preference of the normal neutrino mass ordering from the recent cosmological constraint and the global fit of neutrino oscillation experiments does not seem like a wise choice at first glance since it obscures the neutrinoless double beta decay and hence the Majorana nature of neutrinos. Contrary to this naive expectation, we point out that the actual situation is the opposite. The normal ordering opens the possibility of excluding the higher solar octant and simultaneously measuring the two Majorana CP phases in future \begin{document}$0 \nu 2 \beta$\end{document} experiments. Especially, the funnel region will completely disappear if the solar mixing angle takes the higher octant. The combined precision measurement by the JUNO and Daya Bay experiments can significantly reduce the uncertainty in excluding the higher octant. With a typical \begin{document}${\cal{O}}({\rm{meV}})$\end{document} sensitivity on the effective mass \begin{document}$|m_{ee}|$\end{document}, the neutrinoless double beta decay experiment can tell if the funnel region really exists and hence exclude the higher solar octant. With the sensitivity further improved to sub-meV, the two Majorana CP phases can be simultaneously determined. The normal neutrino mass ordering clearly shows phenomenological advantages than the inverted one.
Published:   , doi: 10.1088/1674-1137/44/5/055101
Abstract:
We construct an alternative uniformly accelerated reference frame based on 3+1 formalism in adapted coordinate. It is distinguished with Rindler coordinate that there is time-dependent redshift drift between co-moving observers. The experimentally falsifiable distinguishment might promote our understanding of non-inertial frame in laboratory.
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ISSN 1674-1137 CN 11-5641/O4

Original research articles, Ietters and reviews Covering theory and experiments in the fieids of

• Particle physics
• Nuclear physics
• Particle and nuclear astrophysics
• Cosmology
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