The energy-, density-, and isospin-dependent ?-formation cross section σ_(Nπ→?)~* and ?-decay width are calculated based on the relativistic BUU approach in which the effective mass splitting of nucleon and ? baryo...The energy-, density-, and isospin-dependent ?-formation cross section σ_(Nπ→?)~* and ?-decay width are calculated based on the relativistic BUU approach in which the effective mass splitting of nucleon and ? baryons in isospin-asymmetric matter is considered by the inclusion of the δ meson exchange in the effective Lagrangian density and the density-dependent coupling constants of Hofmann et al. The results show that the σ_(Nπ→?)~* is decreased(increased) moderately with increasing density with(without)the consideration of medium modifications on pion mass. Meanwhile, if the invariant mass of the system is not far from the ?pole mass, the ?-decay width is also weakly dependent on density. The mass splitting effect of differently charged nucleon and ?baryons on σ_(Nπ→?)~* is found to be more obvious than that of pion mesons but much weaker than the mass splitting in the hard ?production channel NN → N?. Further, the largest mass-splitting influence is seen in the π^-p → ?~0 and π^+n → ?^+ channels but not in the production of ?^- and ?^(++) isobars.展开更多
The phenomenological non-relativistic quark model has been employed to obtain the ground state masses of light vector mesons and their radially excited states and their decay widths.The full hamiltonian used in the in...The phenomenological non-relativistic quark model has been employed to obtain the ground state masses of light vector mesons and their radially excited states and their decay widths.The full hamiltonian used in the investigation has kinetic energy,the confinement potential and the one-gluon-exchange potential.A good agreement is obtained with the experimental masses and their leptonic decay widths.展开更多
We perform a lattice QCD calculation of theχ_(c0)→2γdecay width using a model-independent method that does not require the momentum extrapolation of corresponding off-shell form factors.The simulation is performed ...We perform a lattice QCD calculation of theχ_(c0)→2γdecay width using a model-independent method that does not require the momentum extrapolation of corresponding off-shell form factors.The simulation is performed on ensembles of N_(f)=2 twisted mass lattice QCD gauge configurations with three different lattice spacings.After the continuum extrapolation,the decay width is obtained to beΓ_(γγ)(χ_(c0))=3.65(83)_(stat)(21)_(lat.syst)(66)_(syst)keV.Regardless of this large statistical error,our result is compatible with the experimental results within 1.3σ.Potential improvements of the lattice calculation in the future are also discussed.展开更多
This exploratory study computes two-photon decay widths of pseudo-scalar(ηc)and scalar(χc0)charmonium using two ensembles of Nf=2 twisted mass lattice QCD gauge configurations.The simulation is performed using two l...This exploratory study computes two-photon decay widths of pseudo-scalar(ηc)and scalar(χc0)charmonium using two ensembles of Nf=2 twisted mass lattice QCD gauge configurations.The simulation is performed using two lattice ensembles with lattice spacings a=0.067 fm with size 323×64 and a=0.085 fm with size 243×48.The decay widths for the two charmonia are obtained within the expected ballpark,but are however smaller than the experimental ones.Possible reasons for these discrepancies are discussed.展开更多
We present here a two-step method of classification and calculation for decay rates in the Standard Model. The first step is a phenomenological classification method, which is an extended and improved schematic experi...We present here a two-step method of classification and calculation for decay rates in the Standard Model. The first step is a phenomenological classification method, which is an extended and improved schematic experimental formula for decay width originally introduced by Chang. This schematic formula separates decays into seven classes. Furthermore, from it is derived a process-specific interaction energy m<sub>X</sub>. The second step is a numerical calculation method, which calculates this interaction energy m<sub>X</sub> numerically by minimization of action from the Lagrangian of the process, from which follows the decay width via the phenomenological formula. The Lagrangian is based on an extension of the Standard Model, the extended SU(4)-preon-model. A comparison of numerically calculated and observed decay widths for a large selection of decays shows a good agreement.展开更多
A^(6)Li(^(16)O,^(19)Ne^(∗))^(3)H multi-nucleon transfer-reaction experiment was performed to populate the highly excited states in^(19)Ne.The subsequent decay particles,^(4)He or protons from the^(19)Ne resonant state...A^(6)Li(^(16)O,^(19)Ne^(∗))^(3)H multi-nucleon transfer-reaction experiment was performed to populate the highly excited states in^(19)Ne.The subsequent decay particles,^(4)He or protons from the^(19)Ne resonant states,were detected in coincidence with the recoil 3 H.The excitation-energy spectra of^(19)Ne were reconstructed using the detected proton or^(4)He and the deduced^(18)F or^(15)O data,respectively.A broad resonance at about 7.85 MeV(1/2^(+))was observed,with partial decay widths different from the previously reported values,which may have a significant impact on the destruction of 18 F in astrophysical processes.Several resonances up to very high excitation energies have been identified with a largeα-clustering strength,which confirm the formation of the cluster structure with a one-hole configuration in light nuclei and encourage further systematic studies of the cluster structure in^(19)Ne.展开更多
Last year,the Ξ(1620) state,which is cataloged in the Particle Data Group(PDG) with only one star,was reported again in the Ξ-π+final state by the Belle Collaboration.Its properties,such as the spectroscopy and dec...Last year,the Ξ(1620) state,which is cataloged in the Particle Data Group(PDG) with only one star,was reported again in the Ξ-π+final state by the Belle Collaboration.Its properties,such as the spectroscopy and decay width,cannot be simply explained in the context of conventional constituent quark models.This inspires an active discussion on the structure of this resonance.In this paper,we study the radiative decays of the newly observed Ξ(1620) assuming that it is a meson-baryon molecular state of AK and with spin-parity JP=1/2-developed in our previous study.The partial decay widths of the AK-ΣK molecular state into Ξγ and Ξπγ final states through hadronic loops are evaluated using effective Lagrangians.The partial widths for Ξ(1620)^(0)→γΞ is evaluated to be approximately 118.76-174.21 keV,which may be accessible for the LHCb experiment.If Ξ(1620) is aΛK-∑K molecule,the radiative transition strength Ξ(1620)^(0)→γKA is considerably small and the decay width is of the order of 0.01 eV.Future experimental measurements of these processes can be useful to test the molecule interpretations of the Ξ(1620).展开更多
The di-gamma and di-gluon decay widths of P-wave cc mesons are computed in nonrelativistic phenomenological quark-antiquark potential of the type V （r） =-4 3 α s r＋ Ar ν with different choices of ν using spectro...The di-gamma and di-gluon decay widths of P-wave cc mesons are computed in nonrelativistic phenomenological quark-antiquark potential of the type V （r） =-4 3 α s r＋ Ar ν with different choices of ν using spectroscopic parameters.The numerically obtained radial solutions are employed to obtain the di-gamma and di-gluon decay widths.The computed decay widths are consistent with other model predictions as well as with the known experimental values in the range of potential index 0.7 ≤ ν ≤ 1.1.展开更多
Within the hidden local symmetry framework, the Dalitz decay η→Ve＋e-is studied with the vector meson dominance model. It is found that the partial width Γ（η→ωe＋e-）≈40 e V and branching ratio B（η→ωe＋e-...Within the hidden local symmetry framework, the Dalitz decay η→Ve＋e-is studied with the vector meson dominance model. It is found that the partial width Γ（η→ωe＋e-）≈40 e V and branching ratio B（η→ωe＋e-）≈2×10^-4, and Γ（η→ρe＋e-）≈10Γ（η→ωe＋e-） and B（η→ρe＋e-）≈10B（η→ωe＋e-）. The maximum position of the dilepton distribution is m e＋e-≈1.33 Me V. These decays are measurable with the advent of high statistic ηexperiments.展开更多
A transfer reaction and cluster-decay experiment,12C(16O,24Mg→ α+20Ne)α, was performed at a beam energy of 96 MeV. Both recoil and decay α particles were detected in coincidence, allowing us to deduce the energymo...A transfer reaction and cluster-decay experiment,12C(16O,24Mg→ α+20Ne)α, was performed at a beam energy of 96 MeV. Both recoil and decay α particles were detected in coincidence, allowing us to deduce the energymomentum of a20Ne fragment. A number of resonant states of24Mg were reconstructed up to an excitation energy of approximately 30 MeV. Owing to the experimentally achieved excellent resolutions of the Q-value and excitationenergy spectra, the relative decay widths for each resonant state in24Mg to various final states of20Ne were extracted, along with the total decay width. The obtained results provide good testing ground for theoretical descriptions of multiple clustering configurations in24Mg.展开更多
The decay properties of the D and D s mesons are computed in a nonrelativistic phenomenological quark-antiquark potential of the type V （r） =-4 /3 α s /r＋ Ar ν with different choices of ν.Numerical method to sol...The decay properties of the D and D s mesons are computed in a nonrelativistic phenomenological quark-antiquark potential of the type V （r） =-4 /3 α s /r＋ Ar ν with different choices of ν.Numerical method to solve the Schrdinger equation has been used to obtain the spectroscopy of qQ mesons.The numerically obtained radial solutions are employed to obtain the decay constant and leptonic decay widths.It has been observed that predictions of the ground state masses and the decay widths are consistent with other model predictions as well as with the known experimental values.展开更多
We study the rare decaysΛb→Λl+l−(l=e,μ,τ)in the Bethe-Salpeter equation approach.We find that the branching ratio is Br(Λb→Λμ^+μ^−)×10^6=1.051∼1.098 in our model.This result agrees with the experimenta...We study the rare decaysΛb→Λl+l−(l=e,μ,τ)in the Bethe-Salpeter equation approach.We find that the branching ratio is Br(Λb→Λμ^+μ^−)×10^6=1.051∼1.098 in our model.This result agrees with the experimental data well.In the same parametric region,we find that the branching ratio is Br(Λb→Λe^+e^−(τ^+τ^−))×10^6=0.252∼0.392(0.286∼0.489).展开更多
The baryonΞb(6227)with the quantum number J^P=1/2−is considered as a molecular state composed of aΣb baryon and K¯meson.The partial decay widths of theΣbK¯molecular state intoΞbγandΞ′bγfinal states t...The baryonΞb(6227)with the quantum number J^P=1/2−is considered as a molecular state composed of aΣb baryon and K¯meson.The partial decay widths of theΣbK¯molecular state intoΞbγandΞ′bγfinal states through hadronic loops are evaluated with the help of the effective Lagrangians.The partial widths for theΞb(6227)→γΞb andΞb(6227)→γΞ′b transitions are evaluated at 1.50–1.02 keV and 17.56–24.91 keV,respectively,which may be accessible for the LHCb.Based on our results,we argue that an experimental determination of the radiative decay width ofΞb(6227)is important for the understanding of its intrinsic properties.展开更多
From an inelastic excitation and breakup experiment with a12Be beam at 29 MeV/u,a large4He+8He cluster decay width of 1.1(2)MeV is determined for a state at an excitation energy of 10.3 MeV and with a spin parity of 0...From an inelastic excitation and breakup experiment with a12Be beam at 29 MeV/u,a large4He+8He cluster decay width of 1.1(2)MeV is determined for a state at an excitation energy of 10.3 MeV and with a spin parity of 0+.By using the R-matrix analysis,a cluster spectroscopic factor of 0.53(10)is extracted from the cluster partial width,providing a strong support for the clustering structure in12Be.A specially designed zero-degree telescope played an essential role in the present experiment and has been demonstrated to be a promising tool in future studies of the molecular-like resonances near the cluster separation threshold.展开更多
Mixing between the 2^3S1 and 1^3D1Ds is studied within the 3P0 model. If mixing between these two 1 states exists, Ds1^＊ （2700） ± and DsJ^＊（2860）± could be interpreted as the two orthogonal mixed state...Mixing between the 2^3S1 and 1^3D1Ds is studied within the 3P0 model. If mixing between these two 1 states exists, Ds1^＊ （2700） ± and DsJ^＊（2860）± could be interpreted as the two orthogonal mixed states with mixing angle θ ≈-80 °in the case of a special β for each meson. However, in the case of a universal β for all mesons, D_（s1）~＊（2700） ± could be interpreted as the mixed state of 23S1 and 13D1 with mixing angle 12° θ 21° but D_（sJ）~＊（2860）± seems difficult to interpret as the orthogonal partner of D（s1）~＊（2700）±.展开更多
We study the experimental and theoretical fusion reactions of compound nuclei synthesized using different projectile-target systems,among which at least one projectile/target nucleus is spherical.The first part of thi...We study the experimental and theoretical fusion reactions of compound nuclei synthesized using different projectile-target systems,among which at least one projectile/target nucleus is spherical.The first part of this study analyses the fusion cross sections obtained using different projectile-target combinations in the synthesis of polonium(Po),thorium(Th),and nobelium(No).In the second part of this study,we suggest the fusion reaction to synthesize the superheavy element Z=122.We select three nuclei,polonium(Po),thorium(Th),and nobelium(No),which are synthesized using various projectile-target combinations.We also investigate fusion reactions such as^(90)Zr(^(208)Pb,2n)^(296)122.This study may be a milestone in the synthesis of the superheavy element Z=122.展开更多
In the present study,the newly established preformation formula is applied for the first time to study the kinematics of the cluster emission from various radioactive nuclei,especially those that decay to the double s...In the present study,the newly established preformation formula is applied for the first time to study the kinematics of the cluster emission from various radioactive nuclei,especially those that decay to the double shell closure^(208)Pb nucleus and its neighbors as daughters.The recently proposed universal cluster preformation formula has been established based on the concepts that underscore the influence of mass and charge asymmetry(η_(A)andη_(Z)),cluster mass A_(c),and the Q-value,paving the way to quantify the energy contribution during preformation as well as during the tunneling process separately.The cluster-daughter interaction potential is obtained by folding the relativistic mean-field(RMF)densities with the recently developed microscopic R3Y using the NL 3^(*)and the phenomenological M3Y NN potentials to compare their adaptability.The penetration probabilities are calculated from the WKB approximation.With the inclusion of the new preformation probability P_(0),the predicted half-lives of the R3Y and M3Y interactions are in good agreement with the experimental data.Furthermore,a careful inspection reflects slight differences in the decay half-lives,which arise from their respective barrier properties.The P_(0)for systems with double magic shell closure^(208)Pb daughter are found to be an order of≈10^(2)higher than those with neighboring Pb daughter nuclei.By exploring the contributions of the decay energy,the recoil effect of the daughter nucleus is evaluated,in contrast to several other conjectures.Thus,the centrality of the Q-value in the decay process is demonstrated and redefined within the preformed cluster-decay model.Additionally,we have introduced a simple and intuitive set of criteria that governs the estimation of recoil energy in the cluster radioactivity.展开更多
In this work, we tentatively assign the charmed mesons D J（2580）, D＊J（2650）, D J（2740）, D＊J（2760）,D J（3000） and D＊J（3000） observed by the LHCb collaboration according to their spin, parity and masses, t...In this work, we tentatively assign the charmed mesons D J（2580）, D＊J（2650）, D J（2740）, D＊J（2760）,D J（3000） and D＊J（3000） observed by the LHCb collaboration according to their spin, parity and masses, then systematically study their strong decays to ground state charmed mesons plus pseudoscalar mesons with the3P0 decay model. Based on these studies, we assign the D＊J（2760） as the 1D5/23-state, the D＊J（3000） as the 1F5/22＋or 1F7/24＋state, the D J（3000） as the 1F7/23＋or 2P1/21＋state in the D meson family. As a byproduct, we also study the strong decays of the states 2P1/20＋, 2P3/22＋, 3S1/21-, 3S1/20-etc, which will be valuable in searching for the partners of these D mesons.展开更多
The electromagnetic transition properties of the decuplet to octet baryon （→ Nγ） is studied within the framework of a hypercentral quark model.The confinement potential is assumed as a hypercentral coloumb plus li...The electromagnetic transition properties of the decuplet to octet baryon （→ Nγ） is studied within the framework of a hypercentral quark model.The confinement potential is assumed as a hypercentral coloumb plus linear potential.The transition magnetic moment and transition amplitude f M 1 for the → Nγ are in agreement with other theoretical predictions.The present result of the radiative decay width is found to be in excellent agreement with the experimental values reported by the particle data group over other theoretical model predictions.展开更多
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 dispersio...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.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11875125,11847315,and 11475262)
文摘The energy-, density-, and isospin-dependent ?-formation cross section σ_(Nπ→?)~* and ?-decay width are calculated based on the relativistic BUU approach in which the effective mass splitting of nucleon and ? baryons in isospin-asymmetric matter is considered by the inclusion of the δ meson exchange in the effective Lagrangian density and the density-dependent coupling constants of Hofmann et al. The results show that the σ_(Nπ→?)~* is decreased(increased) moderately with increasing density with(without)the consideration of medium modifications on pion mass. Meanwhile, if the invariant mass of the system is not far from the ?pole mass, the ?-decay width is also weakly dependent on density. The mass splitting effect of differently charged nucleon and ?baryons on σ_(Nπ→?)~* is found to be more obvious than that of pion mesons but much weaker than the mass splitting in the hard ?production channel NN → N?. Further, the largest mass-splitting influence is seen in the π^-p → ?~0 and π^+n → ?^+ channels but not in the production of ?^- and ?^(++) isobars.
基金the DST for funding the project (Sanction No SR/S2/HEP-14/2006)
文摘The phenomenological non-relativistic quark model has been employed to obtain the ground state masses of light vector mesons and their radially excited states and their decay widths.The full hamiltonian used in the investigation has kinetic energy,the confinement potential and the one-gluon-exchange potential.A good agreement is obtained with the experimental masses and their leptonic decay widths.
基金Support by NSFC of China (12070131001)support by CAS Interdisciplinary Innovation Team and NSFC of China (11935017)+1 种基金NSFC of China(12047505)State Key Laboratory of Nuclear Physics and Technology,Peking University
文摘We perform a lattice QCD calculation of theχ_(c0)→2γdecay width using a model-independent method that does not require the momentum extrapolation of corresponding off-shell form factors.The simulation is performed on ensembles of N_(f)=2 twisted mass lattice QCD gauge configurations with three different lattice spacings.After the continuum extrapolation,the decay width is obtained to beΓ_(γγ)(χ_(c0))=3.65(83)_(stat)(21)_(lat.syst)(66)_(syst)keV.Regardless of this large statistical error,our result is compatible with the experimental results within 1.3σ.Potential improvements of the lattice calculation in the future are also discussed.
基金supported in part by the National Science Foundation of China(NSFC)(11335001,11275169,11405178,11935017,11575196,11875169,11775229)It is also supported in part by the DFG and the NSFC(11261130311)through funds provided to the Sino-Germen CRC 110 symmetries and the Emergence of Structure in QCD+1 种基金This work is also funded in part by National Basic Research Program of China(973 Program)(2015CB856700).M.Gong and Z.Liu are partially supported by the Youth Innovation Promotion Association of CAS(2013013).This work is also supported by the Scientific Research Program Funded by Shaanxi Pro-vincial Education Department(19JK0391)Natural Science Basic Research Plan in Shaanxi Province of China(2019JM-001)。
文摘This exploratory study computes two-photon decay widths of pseudo-scalar(ηc)and scalar(χc0)charmonium using two ensembles of Nf=2 twisted mass lattice QCD gauge configurations.The simulation is performed using two lattice ensembles with lattice spacings a=0.067 fm with size 323×64 and a=0.085 fm with size 243×48.The decay widths for the two charmonia are obtained within the expected ballpark,but are however smaller than the experimental ones.Possible reasons for these discrepancies are discussed.
文摘We present here a two-step method of classification and calculation for decay rates in the Standard Model. The first step is a phenomenological classification method, which is an extended and improved schematic experimental formula for decay width originally introduced by Chang. This schematic formula separates decays into seven classes. Furthermore, from it is derived a process-specific interaction energy m<sub>X</sub>. The second step is a numerical calculation method, which calculates this interaction energy m<sub>X</sub> numerically by minimization of action from the Lagrangian of the process, from which follows the decay width via the phenomenological formula. The Lagrangian is based on an extension of the Standard Model, the extended SU(4)-preon-model. A comparison of numerically calculated and observed decay widths for a large selection of decays shows a good agreement.
基金Supported by the National Key R&D Program of China(2018YFA0404403,2022YFA1602302)the National Natural Science Foundation of China(11875074,11875073,12235020,12027809,11961141003,U1967201,U2167204,11775004,11775003)+2 种基金the Continuous Basic Scientific Research Project(WDJC-2019-13)the State Key Laboratory of Nuclear Physics and Technology,Peking University(NPT2020KFY10)the Leading Innovation Project(LC192209000701,LC202309000201)。
文摘A^(6)Li(^(16)O,^(19)Ne^(∗))^(3)H multi-nucleon transfer-reaction experiment was performed to populate the highly excited states in^(19)Ne.The subsequent decay particles,^(4)He or protons from the^(19)Ne resonant states,were detected in coincidence with the recoil 3 H.The excitation-energy spectra of^(19)Ne were reconstructed using the detected proton or^(4)He and the deduced^(18)F or^(15)O data,respectively.A broad resonance at about 7.85 MeV(1/2^(+))was observed,with partial decay widths different from the previously reported values,which may have a significant impact on the destruction of 18 F in astrophysical processes.Several resonances up to very high excitation energies have been identified with a largeα-clustering strength,which confirm the formation of the cluster structure with a one-hole configuration in light nuclei and encourage further systematic studies of the cluster structure in^(19)Ne.
基金Supported by the Science and Technology Research Program of Chongqing Municipal Education Commission (KJQN201800510)the Opened Fund of the State Key Laboratory on Integrated Optoelectronics (IOSKL2017KF19).+2 种基金support from the Development and Exchange Platform for the Theoretic Physics of Southwest Jiaotong University (11947404, 12047576)the Fundamental Research Funds for the Central Universities (2682020CX70)the National Natural Science Foundation of China (12005177)
文摘Last year,the Ξ(1620) state,which is cataloged in the Particle Data Group(PDG) with only one star,was reported again in the Ξ-π+final state by the Belle Collaboration.Its properties,such as the spectroscopy and decay width,cannot be simply explained in the context of conventional constituent quark models.This inspires an active discussion on the structure of this resonance.In this paper,we study the radiative decays of the newly observed Ξ(1620) assuming that it is a meson-baryon molecular state of AK and with spin-parity JP=1/2-developed in our previous study.The partial decay widths of the AK-ΣK molecular state into Ξγ and Ξπγ final states through hadronic loops are evaluated using effective Lagrangians.The partial widths for Ξ(1620)^(0)→γΞ is evaluated to be approximately 118.76-174.21 keV,which may be accessible for the LHCb experiment.If Ξ(1620) is aΛK-∑K molecule,the radiative transition strength Ξ(1620)^(0)→γKA is considerably small and the decay width is of the order of 0.01 eV.Future experimental measurements of these processes can be useful to test the molecule interpretations of the Ξ(1620).
基金done with a financial support from DST,Government of India,under a Major Research Project SR/S2/HEP-20/2006
文摘The di-gamma and di-gluon decay widths of P-wave cc mesons are computed in nonrelativistic phenomenological quark-antiquark potential of the type V （r） =-4 3 α s r＋ Ar ν with different choices of ν using spectroscopic parameters.The numerically obtained radial solutions are employed to obtain the di-gamma and di-gluon decay widths.The computed decay widths are consistent with other model predictions as well as with the known experimental values in the range of potential index 0.7 ≤ ν ≤ 1.1.
基金Supported by National Natural Science Foundation of China(11147008,11275057,U1332103,U1232101)Program for Science and Technology Innovation Talents in Universities of Henan Province(2012HASTIT030)
文摘Within the hidden local symmetry framework, the Dalitz decay η→Ve＋e-is studied with the vector meson dominance model. It is found that the partial width Γ（η→ωe＋e-）≈40 e V and branching ratio B（η→ωe＋e-）≈2×10^-4, and Γ（η→ρe＋e-）≈10Γ（η→ωe＋e-） and B（η→ρe＋e-）≈10B（η→ωe＋e-）. The maximum position of the dilepton distribution is m e＋e-≈1.33 Me V. These decays are measurable with the advent of high statistic ηexperiments.
基金Supported by the National Key R&D Program of China (2018YFA0404403)the National Natural Science Foundation of China (11875074, 11875073, 12027809,11961141003, U1967201, 11775004, and 11775003)+1 种基金the Continuous Basic Scientific Research Project (WDJC-2019-13)the State Key Laboratory of Nuclear Physics and Technology,Peking University (NPT2020KFY10)。
文摘A transfer reaction and cluster-decay experiment,12C(16O,24Mg→ α+20Ne)α, was performed at a beam energy of 96 MeV. Both recoil and decay α particles were detected in coincidence, allowing us to deduce the energymomentum of a20Ne fragment. A number of resonant states of24Mg were reconstructed up to an excitation energy of approximately 30 MeV. Owing to the experimentally achieved excellent resolutions of the Q-value and excitationenergy spectra, the relative decay widths for each resonant state in24Mg to various final states of20Ne were extracted, along with the total decay width. The obtained results provide good testing ground for theoretical descriptions of multiple clustering configurations in24Mg.
基金support from DST,Government of India,under a Major Research Project SR/S2/HEP-20/2006
文摘The decay properties of the D and D s mesons are computed in a nonrelativistic phenomenological quark-antiquark potential of the type V （r） =-4 /3 α s /r＋ Ar ν with different choices of ν.Numerical method to solve the Schrdinger equation has been used to obtain the spectroscopy of qQ mesons.The numerically obtained radial solutions are employed to obtain the decay constant and leptonic decay widths.It has been observed that predictions of the ground state masses and the decay widths are consistent with other model predictions as well as with the known experimental values.
基金Supported by National Natural Science Foundation of China(11775024,11575023,11905117,11847052,11805012,11947001)。
文摘We study the rare decaysΛb→Λl+l−(l=e,μ,τ)in the Bethe-Salpeter equation approach.We find that the branching ratio is Br(Λb→Λμ^+μ^−)×10^6=1.051∼1.098 in our model.This result agrees with the experimental data well.In the same parametric region,we find that the branching ratio is Br(Λb→Λe^+e^−(τ^+τ^−))×10^6=0.252∼0.392(0.286∼0.489).
基金supported by the Development and Exchange Platform for Theoretic Physics of Southwest Jiaotong University in 2020(11947404)We ac-knowledge the supported by the National Science Foundation of Chongqing(cstc2019jcyj-msxm0953)+1 种基金the Science and Technology Research Program of Chongqing Municipal Education Commission(KJQN201800510)supported by the Fundamental Research Funds for the Central Universities(2682020CX70)。
文摘The baryonΞb(6227)with the quantum number J^P=1/2−is considered as a molecular state composed of aΣb baryon and K¯meson.The partial decay widths of theΣbK¯molecular state intoΞbγandΞ′bγfinal states through hadronic loops are evaluated with the help of the effective Lagrangians.The partial widths for theΞb(6227)→γΞb andΞb(6227)→γΞ′b transitions are evaluated at 1.50–1.02 keV and 17.56–24.91 keV,respectively,which may be accessible for the LHCb.Based on our results,we argue that an experimental determination of the radiative decay width ofΞb(6227)is important for the understanding of its intrinsic properties.
基金supported by the National Basic Research Program of China(Grant No.2013CB834402)the National Natural Science Foundation of China(Grant Nos.11035001,11275011,11235001,11320101004 andJ1103206)
文摘From an inelastic excitation and breakup experiment with a12Be beam at 29 MeV/u,a large4He+8He cluster decay width of 1.1(2)MeV is determined for a state at an excitation energy of 10.3 MeV and with a spin parity of 0+.By using the R-matrix analysis,a cluster spectroscopic factor of 0.53(10)is extracted from the cluster partial width,providing a strong support for the clustering structure in12Be.A specially designed zero-degree telescope played an essential role in the present experiment and has been demonstrated to be a promising tool in future studies of the molecular-like resonances near the cluster separation threshold.
基金Supported by National Natural Science Foundation of China(11075102)
文摘Mixing between the 2^3S1 and 1^3D1Ds is studied within the 3P0 model. If mixing between these two 1 states exists, Ds1^＊ （2700） ± and DsJ^＊（2860）± could be interpreted as the two orthogonal mixed states with mixing angle θ ≈-80 °in the case of a special β for each meson. However, in the case of a universal β for all mesons, D_（s1）~＊（2700） ± could be interpreted as the mixed state of 23S1 and 13D1 with mixing angle 12° θ 21° but D_（sJ）~＊（2860）± seems difficult to interpret as the orthogonal partner of D（s1）~＊（2700）±.
文摘We study the experimental and theoretical fusion reactions of compound nuclei synthesized using different projectile-target systems,among which at least one projectile/target nucleus is spherical.The first part of this study analyses the fusion cross sections obtained using different projectile-target combinations in the synthesis of polonium(Po),thorium(Th),and nobelium(No).In the second part of this study,we suggest the fusion reaction to synthesize the superheavy element Z=122.We select three nuclei,polonium(Po),thorium(Th),and nobelium(No),which are synthesized using various projectile-target combinations.We also investigate fusion reactions such as^(90)Zr(^(208)Pb,2n)^(296)122.This study may be a milestone in the synthesis of the superheavy element Z=122.
基金Supported by the Fundamental Research Grant Scheme(FRGS/1/2019/STG02/UNIMAP/02/2)from the Ministry of Education Malaysia stipulated with the Institute of Engineering Mathematics(IMK)of the Faculty of Applied and Human Sciences UniMAP as the beholder,Science and Engineering Research Board(SERB,CRG/2021/001229)FOSTECT Project(FOSTECT.2019B.04)FAPESP Project(2017/05660-0)
文摘In the present study,the newly established preformation formula is applied for the first time to study the kinematics of the cluster emission from various radioactive nuclei,especially those that decay to the double shell closure^(208)Pb nucleus and its neighbors as daughters.The recently proposed universal cluster preformation formula has been established based on the concepts that underscore the influence of mass and charge asymmetry(η_(A)andη_(Z)),cluster mass A_(c),and the Q-value,paving the way to quantify the energy contribution during preformation as well as during the tunneling process separately.The cluster-daughter interaction potential is obtained by folding the relativistic mean-field(RMF)densities with the recently developed microscopic R3Y using the NL 3^(*)and the phenomenological M3Y NN potentials to compare their adaptability.The penetration probabilities are calculated from the WKB approximation.With the inclusion of the new preformation probability P_(0),the predicted half-lives of the R3Y and M3Y interactions are in good agreement with the experimental data.Furthermore,a careful inspection reflects slight differences in the decay half-lives,which arise from their respective barrier properties.The P_(0)for systems with double magic shell closure^(208)Pb daughter are found to be an order of≈10^(2)higher than those with neighboring Pb daughter nuclei.By exploring the contributions of the decay energy,the recoil effect of the daughter nucleus is evaluated,in contrast to several other conjectures.Thus,the centrality of the Q-value in the decay process is demonstrated and redefined within the preformed cluster-decay model.Additionally,we have introduced a simple and intuitive set of criteria that governs the estimation of recoil energy in the cluster radioactivity.
基金Supported by National Natural Science Foundation of China(11375063)Fundamental Research Funds for the Central Universities(13QN59,2014MS165)
文摘In this work, we tentatively assign the charmed mesons D J（2580）, D＊J（2650）, D J（2740）, D＊J（2760）,D J（3000） and D＊J（3000） observed by the LHCb collaboration according to their spin, parity and masses, then systematically study their strong decays to ground state charmed mesons plus pseudoscalar mesons with the3P0 decay model. Based on these studies, we assign the D＊J（2760） as the 1D5/23-state, the D＊J（3000） as the 1F5/22＋or 1F7/24＋state, the D J（3000） as the 1F7/23＋or 2P1/21＋state in the D meson family. As a byproduct, we also study the strong decays of the states 2P1/20＋, 2P3/22＋, 3S1/21-, 3S1/20-etc, which will be valuable in searching for the partners of these D mesons.
文摘The electromagnetic transition properties of the decuplet to octet baryon （→ Nγ） is studied within the framework of a hypercentral quark model.The confinement potential is assumed as a hypercentral coloumb plus linear potential.The transition magnetic moment and transition amplitude f M 1 for the → Nγ are in agreement with other theoretical predictions.The present result of the radiative decay width is found to be in excellent agreement with the experimental values reported by the particle data group over other theoretical model predictions.
基金Supported by National Key R&D Program of China(2018 YFA0404404)National Natural Science Foundation of China(11875323,11875125,11475262,11961141003,11790323,11790324,11790325)the Continuous Basic Scientific Research Project(WDJC-2019-13,No BJ20002501).
文摘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.
