Structures of（ΩΩ）0＋and（[1]Ω）1＋in Extended Chiral SU（3） Quark Model

The structures of (ΩΩ)0 and ([1]Ω)1 are studied in the extended chiral SU(3) quark model in which vector meson exchanges are included. The effect from the vector meson fields is very similar to that from the one-gluon exchange (OGE) interaction. Both in the chiral SU(3) quark model and in the extended chiral SU(3) quark model,di-omega (ΩΩ)0 is always deeply bound, with over one hundred MeV binding energy, and ([1]Ω)1 ‘s binding energy is around 20 MeV. An analysis shows that the quark exchange effect plays a very important role for making di-omega (ΩΩ)0 deeply bound.     

Momentum dependence of pion-induced φ meson production on nuclei near threshold

We study the near-threshold pion-induced production ofφmesons off nuclei in the kinematical conditions of the HADES experiment,recently performed at GSI.The calculations have been performed within a collision model based on the nuclear spectral function.The model accounts for both the primaryπ~-meson–protonπ~-p→φn and the secondary pion–nucleonπN→φNφproduction processes as well as the effects of the nuclearφand nucleon mean-field potentials.We find that the primary reaction channelπ~-p→φn dominates in theφproduction off~(12)C and~(184)W target nuclei in the HADES acceptance window at incident pion momentum of 1.7 Ge V/c.We calculate the momentum dependence of the absolute and relative(transparency ratio)φmeson yields from the above direct channel.The calculations have been performed for this initial pion momentum allowing for different options for theφN absorption cross sectionσ_(φN )and different scenarios for the in-medium mass shifts of theφmeson and secondary neutron,produced together withφin this channel.We demonstrate that the transparency ratio for theφmesons has,contrary to the absolute cross sections,an insignificant sensitivity to theφmeson and secondary neutron in-medium mass shifts atφmomenta studied in the HADES experiment.On the other hand,we show that there are measurable changes in the transparency ratio due to theφN absorption cross section,which means that such a relative observable can be useful to help determine this cross section from the data taken in the HADES experiment.     

Study of the process e^＋e^- →π^＋π^-π^0π^0 at energies √s 〈 1 GeV

In an experiment with the Spherical Neutral Detector at VEPP-2M collider the cross section of the process e^＋e^- →π^＋π^-π^0π^0 was measured. At energies √s 〈 920 MeV this cross section was measured for the first time. The energy dependence of the cross section is well discribed by the vector dominance model with contributions from p, p＇, p＂ mesons. The decay probability ρ→π^＋π^-π^0π^0 was found to be Bρ = （1.60±0.74±0.18） × 10^-5. The upper limit for the decay ω→π^＋π^-π^0π^0 was improved by two orders of magnitude compared to the previous measurements and is Bω 〈 2 × 10^-4 at 90% confidence level.     

The single neutral top-higgs production at LHC and ILC in the Topcolor-Assisted Technicolor Model

In this paper, we study the single neutral top-higgs (h0t) production processes at the CERN Large Hadron Collider (LHC) and the International Linear Collider (ILC). At the LHC, the production rates of processes pp→Z(W)h0t are too small to detect h0t . However, with the reasonable parameter values, the cross sections can reach the level of 102 fb for qq→qqh0t process and 103 fb for top quark associated production process pp→th0t+X, respectively. At the ILC, we study the single top-higgs production processes e-γ→νeW-h0t and γγ→W+W-h0t in e-γ and γγ collisions. It is found that the production cross sections can reach the level of a few fb with reasonable parameter values. Furthermore, such processes with the flavor-changing decay mode h0t→tc might provide typical signatures to detected the top-higgs. Therefore, it is hopeful to find the signal of top-higgs at the LHC and ILC experiments via theses processes and test the TC2 model directly.     

Evidence for resonant structures in e＋e-→π＋π-hc

Abstract： The cross sections of e＋e-→π＋π-hc at center-of-mass energies from 3.90 to 4.42 GeV were measured by the BESIII and the CLEO-c experiments. Resonant structures are evident in the e＋e-→π＋π-hc line shape. The fit to the line shape results in a narrow structure at a mass of （4216±18） MeV/c2 and a width of （39±2） MeV, and a possible wide structure of mass （4293±9） MeV/c2 and width （222=k67） MeV. Here, the errors are combined statistical and systematic errors. This may indicate that the Y（4260） state observed in e＋e-→π＋π-J/ψ has a fine structure in it.     

Analysis of Vertex D^＊D^＊ρ with Light-Cone QCD Sum Rules

We analyse the vertex D^＊D^＊ρ with the light-cone QCD sum rules. The strong coupling constant gD^＊D^＊ρ is an important parameter in evaluating the charmonium absorption cross sections in searching for the quark-gluon plasmas. Our numerical value for the gD^＊D^＊ρ is consistent with the prediction of the effective SU（4） symmetry and vector meson dominance theory.     

Charged Top-Pion Production at e^＋e^- and γγ Colliders

We study the charged top-pion in the topcolor assisted technicolor model（TC2）, and calculate the production of charged top-pion at e^＋ e^- and γγ colliders. At an e^＋ e^- collider, charged top-pion can be produced via the processes e^＋e^- → t^bπt^-（^tbπt^＋）. At a γγ collider, it can be produced via the processes γγ →t^bπt^-（t^-bπt^＋）. The cross section can reach to a few of fb depending on the mass of the charged top-pion.     

Production of Λ-hypernuclei in A(p,K~ )ΛB reactions

The production of Λ-hypernuclei in the A(p,K )ΛB reaction is investigated in the framework of the distorted wave impulse approximation(DWIA). The total cross sections and differential cross sections for various nuclear targets are calculated with an elementary process pN→NKΛ where the additional contributions from the N*(1535) resonance and the final state interaction between p and Λ are included. The dependence of the production cross sections of Λ-hypernuclei on the phenomenological nuclear density and the nucleon number in the target, as well as the distortion effect of the incident proton and outgoing kaon, are also explored. It is shown that the distortion effect tends to decrease the cross sections by a factor of about 3—10. The production cross sections are sensitive to the adopted nuclear density.     

Study of the process e~+e~- →π~+π~-π~0π~0 at energies s～(1/2)<1 GeV

In an experiment with the Spherical Neutral Detector at VEPP-2M collider the cross section of the process e+e-→π+π-π0π0 was measured.At energies s～(1/2)920 MeV this cross section was measured for the first time.The energy dependence of the cross section is well discribed by the vector dominance model with contributions from ρ,ρ,ρ mesons.The decay probability ρ→π+π-π0π0 was found to be Bρ =(1.60±0.74±0.18)×10-5.The upper limit for the decay ω→π+π-π0π0 was improved by two orders of magnitude compared to the previous measurements and is Bω 2×10-4 at 90% confidence level.     

Two-photon processes at Belle

We review recent measurements of pure neutral final state production in the two-photon processes,γγ→π0π0 and ηπ0 at the Belle experiment.In the lower invariant mass region,properties of light scalar mesons are measured by partial wave analysis.In the higher energy region the total and differential cross section are compared with QCD models.     

The Role of α_1(1260) in π~-p→α_1~-(1260)p and π~-p → π~-ρ~0p Reactions Near Threshold

We report on a theoretical study of the π~-ρ→α1(1260)p and π~-ρ→π~-ρ~0p reactions near threshold within an effective Lagrangian approach.The production process is described by t-channel ρ~0 meson exchange.For the π~-ρ→π~- ρ~0p reaction,the final π~-ρ~0 results from the decay of the α1(1260) resonance,which is assumed as a dynamically generated state from the K* K and ρπ coupled channel interactions.We calculate the total cross section of the π~-ρ→α1(1260)p reaction.It is shown that,with the coupling constant of the α1(1260) to ρπ channel obtained from the chiral unitary theory and a cut off parameter Δρ~1.5 GeV in the form factors,the experimental measurement can be reproduced.Furthermore,the total and differential cross sections of π~p→α1(1260)p→π~ρ~0p reaction are evaluated,and it is expected that our model calculations can be tested by future experiments.These reactions are important for the study of the α1(1260) resonance and would provide further constraints on the properties of the α1(1260) state.     

Two-photon processes at Belle

We review recent measurements of pure neutral final state production in the two-photon processes, γγ→π^0π^0 and ηπ^0 at the Belle experiment. In the lower invariant mass region, properties of light scalar mesons are measured by partial wave analysis. In the higher energy region the total and differential cross section are compared with QCD models.     

Study of the process e+e-→π+π-π0π0 at energies √s< 1 GeV

In an experiment with the Spherical Neutral Detector at VEPP-2M collider the cross section of the process e+e-→π+π-π0π0 was measured. At energies √s < 920 MeV this cross section was measured for the first time. The energy dependence of the cross section is well discribed by the vector dominance model with contributions from ρ, ρ' ρ", mesons. The decay probability ρ→π+π-π0π0was found to be Bρ = (1.60±0.74±0.18)×10-5. The upper limit for the decay ω→π+π-π0π0 was improved by two orders of magnitude compared to the previous measurements and is Bω < 2 × 10-4 at 90% confidence level.     

Production of Charged Higgs Bosons from Left-Right Twin Higgs Model at TeV Energy e-γ Colliders

The left-right twin Higgs （LRTH） model predicts the existence of three additional Higgs bosons： one neutral Higgs φo and a pair of charged Higgs bosons φ±. In this paper, we study two pair production processes of these new particles at the next generation eγ colliders, i.e., e-γ → e-φ＋φ- , and e-γ→vRφ-φ0. We find that the production cross section of the process e-γ → e-φ＋φ- are at the level of several tens fb, the production cross section of the process e-γ→vRφ-φ0 can reach 0.35 fb with the reasonable parameter values. As long as the charged Higgs bosons are not too heavy, we conclude that these processes might be used to test for the left-right twin Higgs model in future high-energy linear collider experiments.     

Vector meson effects on multi-Skyrmion states from the rational map ansatz

The roles of the lightest vector mesons ρ and ω in the multi-Skyrmion states are studied using the hidden local symmetry approach up to the next-to-leading order, including the homogeneous Wess-Zumino terms. The low-energy constants in the effective field theory are determined using the Sakai-Sugimoto model and the flat-space five-dimensional Yang-Mills action. With only two inputs, mρ and fπ, it is possible to determine all low-energy constants without ambiguity. The vector meson effects can be...     

Structures of (ΩΩ)0 and (([1])Ω)1 in Extended Chiral SU(3) Quark Model

The structures of (ΩΩ)0 and (([1])Ω)1 are studied in the extended chiral SU(3) quark model in whichvector meson exchanges are included. The effect from the vector meson fields is very similar to that from the one-gluonexchange (OGE) interaction. Both in the chiral SU(3) quark model and in the extended chiral SU(3) quark model,di-omega (ΩΩ)0 is always deeply bound, with over one hundred MeV binding energy, and (([1])Ω)1 ‘s binding energyis around 20 MeV. An analysis shows that the quark exchange effect plays a very important role for making di-omega(ΩΩ)0 deeply bound.     

In-medium pion dispersion relation and medium correction of Nπ■Δ near the threshold energy of pion production

Transport models cannot simultaneously explain very recent data on pion multiplicities and pion charged ratios from central collision of Sn+Sn at 0.27 A GeV.This stimulates further investigations on the pion dispersion relation,in-medium Nπ→Δ cross sections,and Δ→Nπ decay widths near the threshold energy or at subthreshold energy of pion production in isospin asymmetric nuclear matter.In this study,the pion dispersion relation,in-medium Nπ→Δ cross section,and Δ→Nπ decay width near the threshold energy are investigated in isospin asymmetric nuclear matter by using the one-boson-exchange model.With the consideration of the energy conservation effect,the in-medium Nπ→Δ cross sections are enhanced at s1/2 <1.11 GeV in a nuclear medium.The prediction of pion multiplicity and π-/π+ ratios near the threshold energy could be modified if this effect is considered in transport model simulations.     

Effects of the vibrational and rotational excitation of reagent on the stereodynamics of the reaction S（3P） + H2→ SH + H

Quasiclassical trajectory （QCT） calculations are first carried out to study the stereodynamics of the S （3p） ＋ H2 → SH ＋ H reaction based on the ab initio 13Atr potential energy surface （PES） （Lii etal. 2012 J. Chem. Phys. 136 094308）. The QCT-calculated reaction probabilities and cross sections for the S ＋ H2 （v = 0, j = 0） reaction are in good agreement with the previous quantum mechanics （QM） results. The vector properties including the alignment, orientation, and polarization- dependent differential cross sections （PDDCSs） of the product SH are presented at a collision energy of 1.8 eV. The effects of the vibrational and rotational excitations of reagent on the stereodynamics are also investigated and discussed in the present work. The calculated QCT results indicate that the vibrational and rotational excitations of reagent play an important role in determining the stereodynamic properties of the title reaction.     

Structure of Di-Ω Dibaryon

Previously, we extended our chiral SU（3） quark model to include the coupling between the quark and vector chiral fields [Nucl. Phys. A 727（2003）321]. Here we further study the structure of （ΩΩ）ST=oo dibaryon in the extended chiral SU（3） quark model by solving a resonating group method equation. The vector meson exchanges effect, hidden colour channel and colour screening effect are investigated, respectively. The results show that the （ΩΩ）ST=oo system is still the deeply bound state in the extended chiral SU（3） quark model in which the vector meson exchanges control the short-range quark-quark interaction, which is similar to the results obtained from the chiral SU（3） quark model. When the model space is enlarged by including the hidden colour channel, it is found that the energy of the hidden colour state ｜CC〉str=-6,ST=oo is much higher than that of the （ΩΩ）ST=oo state, thus the CC channel has little effect on the binding energy of （ΩΩ）ST=oo state. When the error function confinement potential is considered, the bound state property would not change largely. Fhrther, scalar meson mixing is considered. No matter whether θs= -18° or ideal mixing is taken, （ΩΩ）ST=oo state is still a bound state.     

Production of Charged Heavy Quarkonium-Like States at the LHC and Tevatron

We study prompt hadroproduction of the charged bottomonium-like states Zb± （10610） and Zb±（10650）, and the charged eharmonium-like states Zc± （3900） and Zc± （4020）, at the Tevatron and the LHC, provided that these states are S-wave hadronic molecules. Using two Monte Carlo event generators, Herwig and Pythia, to simulate the production of heavy meson pairs, we derive an order-of-magnitude estimate of the production rates for these four particles. Our estimates yield a cross section at the nb level for the Zb（10610） and Zb（10650）. The results for the Zc（3900） and Zc （4020） are larger by a factor of 2~30. These cross sections are large enough to be observed, and measurements at hadron colliders in the future will supplement the study using electron-positron collisions, and therefore allow to explore the mysterious nature of these exotic states.