The autoionization branching ratios from Eu 4f76p1/26 d [J] autoionizing states to its 4f76s+(9So), 4f76s+(7So), and4f75d+(9Do) final ionic states are investigated with the combination of the three-step laser excitati...The autoionization branching ratios from Eu 4f76p1/26 d [J] autoionizing states to its 4f76s+(9So), 4f76s+(7So), and4f75d+(9Do) final ionic states are investigated with the combination of the three-step laser excitation and the velocity-map imaging technique. These different autoionizing states are excited via 4f76s6d8 DJ [J = 5/2, 7/2, and 9/2] intermediate states, respectively. The experimental photoelectron images are obtained, from which energy distributions of ejected electrons are achieved with the mathematical transformation. Furthermore, the energy dependence of the branching ratio is investigated within the autoionization resonance, by which population inversion is observed as an important characteristic.The J-dependence is also studied systematically. The validity of the well-known isolated core excitation technique used for obtaining the autoionization spectrum is also studied.展开更多
The photoabsorption and photodissociation of carbon monoxide(CO)in the vacuum ultraviolet(VUV)region is one of the most important photochemical processes in the interstellar medium,thus it has attracted numerous exper...The photoabsorption and photodissociation of carbon monoxide(CO)in the vacuum ultraviolet(VUV)region is one of the most important photochemical processes in the interstellar medium,thus it has attracted numerous experimental and theoretical studies.Here,we employed the two-color VUV-VUV laser pump-probe time-slice velocity-map ion imaging method to measure the relative branching ratios[C(3P0)+O(1D)]/{[C(3P0)+O(3P)]+[C(3P0)+O(1D)]}and[C(3P2)+O(1D)]/{[C(3P2)+O(3P)]+[C(3P2)+O(1D)]}in the VUV photoexcitation energy range of 108000-113200 cm^−1.Here,one tunable VUV laser beam is used to excite CO to speci c rovibronic states,and a second independently tunable VUV laser beam is used to state-selectively ionize C(3P0)and C(3P2)for detection.State-selective photoionization through the 1VUV+1UV/visible resonance-enhanced multiphoton ionization scheme has greatly enhanced the detection sensitivity,which makes many new weak absorption bands observable in the current study.The branching ratio measurement shows that the spin-forbidden channels C(3P0)+O(1D)and C(3P2)+O(1D)only open at several discrete narrow energy windows.This might be caused by certain accidental resonanceenhanced spin-orbit interactions between the directly excited Rydberg states and valence states of triplet type which nally dissociate into the spin-forbidden channels.展开更多
We present a systematic calculation on the α-decay branching ratios to excited-states of an even-even α-decay chain ^242Cm → ^238Pu → ^234U → ^230Th → ^226Rn by the improved barrier penetration approach. The c...We present a systematic calculation on the α-decay branching ratios to excited-states of an even-even α-decay chain ^242Cm → ^238Pu → ^234U → ^230Th → ^226Rn by the improved barrier penetration approach. The changes of the parities between the parent nuclei and the daughter nuclei are properly taken into account. The theoretical values are compared with the available experimental data and the deviation between them is within a factor of 5 in most cases.展开更多
The branching ratios of ions and the angular distributions of electrons ejected from the Eu 4f^76p_(1/2)nd auto-ionizing states are investigated with the velocity-map-imaging technique.To populate the above auto-ion...The branching ratios of ions and the angular distributions of electrons ejected from the Eu 4f^76p_(1/2)nd auto-ionizing states are investigated with the velocity-map-imaging technique.To populate the above auto-ionizing states,the relevant bound Rydberg states have to be detected first.Two new bound Rydberg states are identified in the region between41150 cm^(-1)and 44580 cm^(-1),from which auto-ionization spectra of the Eu 4f^76p_(1/2)nd states are observed with isolated core excitation method.With all preparations above,the branching ratios from the above auto-ionizing states to different final ionic states and the angular distributions of electrons ejected from these processes are measured systematically.Energy dependence of branching ratios and anisotropy parameters within the auto-ionization spectra are carefully analyzed,followed by a qualitative interpretation.展开更多
A detailed investigation of different decay modes,namely alpha decay,beta decay,cluster decay including heavy particle emission(Z_(c)>28),and spontaneous fission,was carried out,leading to the identification of new...A detailed investigation of different decay modes,namely alpha decay,beta decay,cluster decay including heavy particle emission(Z_(c)>28),and spontaneous fission,was carried out,leading to the identification of new cluster and beta-plus emitters in superheavy nucle with 104≤Z≤126.For the first time,we identified around20 beta-plus emitters in superheavy nuclei.Heavy-particle radioactivity was observed in superheavy elements of atomic number in the range 116≤Z≤126.^(292-293)Og were identified as ^(86)Kr emitters,and ^(298)122 and ^(300)122 were identified as ^(94)Zr emitters,whereas heavy-particle radioactivity from ^(91)Y was also observed in ^(299)123.Furthermore,the nuclei ^(300)124 and ^(306)126 exhibit ^(96)Mo radioactivity.The reported regions of beta-plus and heavyparticle radioactivity for superheavy nuclei are stronger than those for alpha decay.The identified decay modes for superheavy nuclei are presented in a chart.This study is intended to serve as a reference for identifying possible decay modes in the superheavy region.展开更多
This work introduces the branching ratio(BR) method for determining relative spectral responses,which are needed routinely in laser induced breakdown spectroscopy(LIBS). Neutral and singly ionized Ti lines in the 250...This work introduces the branching ratio(BR) method for determining relative spectral responses,which are needed routinely in laser induced breakdown spectroscopy(LIBS). Neutral and singly ionized Ti lines in the 250–498 nm spectral range are investigated by measuring laser-induced micro plasma near a Ti plate and used to calculate the relative spectral response of an entire LIBS detection system. The results are compared with those of the conventional relative spectral response calibration method using a tungsten halogen lamp, and certain lines available for the BR method are selected. The study supports the common manner of using BRs to calibrate the detection system in LIBS setups.展开更多
The intrinsic product polarization and intramolecular isotope effect of the S(~1D,~3P) + HD reaction have been investigated on both the lowest singlet state(1A) and the triplet state(3A and 3A) potential energy...The intrinsic product polarization and intramolecular isotope effect of the S(~1D,~3P) + HD reaction have been investigated on both the lowest singlet state(1A) and the triplet state(3A and 3A) potential energy surfaces by using quasi-classical trajectory and quantum mechanical methods.The calculations indicate that intramolecular isotope effects are different on the three electronic states.The stereodynamics study shows that the P(θr) distributions,P(φ r) distributions,and polarization-dependent differential cross sections(PDDCSs)(00) are sensitive to mass factor and the product angular momentum vectors are not only aligned but also oriented.展开更多
This paper purposes an explanation for the recent evidence for the violation of lepton universality in beauty-quark decays at CERN’s Large Hadron Collider. A beauty meson (B<sup>+</sup>) transforms into a...This paper purposes an explanation for the recent evidence for the violation of lepton universality in beauty-quark decays at CERN’s Large Hadron Collider. A beauty meson (B<sup>+</sup>) transforms into a strange meson (K<sup>+</sup>) with the emission of either electron-positron (e<sup>+</sup>e<sup>-</sup>) or muon-antimuon (<span style="white-space:nowrap;"><em>μ</em></span><sup>+</sup><em>μ</em><sup>-</sup>). The ratio (<em>R</em><sub>K</sub>) of branching fractions for B<sup>+ </sup><span style="white-space:nowrap;">→</span> K<sup>+</sup><em>μ</em><sup>+</sup><em>μ</em><sup>- </sup>and B<sup>+</sup><span style="white-space:nowrap;">→</span> K<sup>+</sup>e<sup>+</sup>e<sup>-</sup> decays is measured to be <em>R</em><sub>K</sub> = 0.846 instead of 1 in the violation of lepton universality in the Standard Model. This paper proposes that the violation is derived from the binary isotope mixture of two beauty-quarks, b<sub>7</sub> (4979 MeV mass) and b<sub>8</sub> (143,258 MeV mass) whose masses are calculated from the periodic table of elementary particles. b<sub>7</sub> is the observable B, while b<sub>8</sub> is the hidden B to preserve the generation number symmetry between the three lepton family generations and the three quark family generations in the Standard Model. The preservation of the generation number symmetry forbids b<sub>8</sub> to decay into K<sup>+</sup><em>μ</em><sup>+</sup><em>μ</em><sup>-</sup>. In the transition state involving the virtual particles (<span style="white-space:nowrap;"><em>γ</em></span>, W± and Z<span style="white-space:nowrap;">°</span>) before the decay, b<sub>7</sub> and b<sub>8</sub> emerge to form the binary isotope mixture from B. The rates of emergence as the rates of diffuse in Graham’s law of diffusion are proportional to inverse square root of mass. The rate ratio between b<sub>8</sub>/b<sub>7</sub> is (4979/143,258)<sup>1/2</sup> = 0.1864. Since b<sub>7</sub> decays into K<sup>+</sup>, e<sup>+</sup>e<sup>-</sup>, and <em>μ</em><sup>+</sup><em>μ</em><sup>-</sup>, while b<sub>8</sub> decays into K<sup>+</sup>, e<sup>+</sup>e<sup>-</sup>, and forbidden <em>μ</em><sup>+</sup><em>μ</em><sup>-</sup>, the calculated ratio (RK) of branching fractions for B<sup>+</sup><span style="white-space:nowrap;">→</span> K<sup>+</sup><em>μ</em><sup>+</sup><em>μ</em><sup>-</sup> and B<sup>+</sup><span style="white-space:nowrap;">→</span> K<sup>+</sup>e<sup>+</sup>e<sup>- </sup>is 0.5/(0.1864 × 0.5+ 0.5) = 0.843 in excellent agreement with the observed 0.846. The agreement between the calculated RK and the observed RK confirms the validity of the periodic table of elementary particles which provides the answers for the dominance of matter over antimatter, dark-matter, and the mass hierarchy of elementary particles.展开更多
A maximum likelihood method is used to deal with the combined estimation of multi-measurements of a branching ratio, where each result can be presented as an upper limit. The joint likelihood function is constructed u...A maximum likelihood method is used to deal with the combined estimation of multi-measurements of a branching ratio, where each result can be presented as an upper limit. The joint likelihood function is constructed using observed spectra of all measurements and the combined estimate of the branching ratio is obtained by maxi- mizing the joint likelihood function. The Bayesian credible interval or upper limit of the combined branching ratio, is given in cases both with and without inclusion of systematic error.展开更多
We have examined the parametrization of the e^+e^- → ωπ0 cross section in the vicinity of the φ resonance and the extraction of the branching fraction of the isospin violating process φ → ωπ0 from experimenta...We have examined the parametrization of the e^+e^- → ωπ0 cross section in the vicinity of the φ resonance and the extraction of the branching fraction of the isospin violating process φ → ωπ0 from experimental data. We found that there are two possible solutions of the branching fraction: one is 4 × 10-5, and the other is 7×10^-3. The latter is two orders of magnitude higher than the former, which is the commonly accepted one.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
The ground vector Bc*meson has not yet been experimentally discovered until now.Besides the dominant electromagnetic decays,nonleptonic weak decays provide another choice to search for the mysterious Bc*mesons.Inspire...The ground vector Bc*meson has not yet been experimentally discovered until now.Besides the dominant electromagnetic decays,nonleptonic weak decays provide another choice to search for the mysterious Bc*mesons.Inspired by the potential prospects of Bc*mesons in future high-luminosity colliders,nonleptonic Bc*weak decays induced by bottom and charm quark decays are studied within the SM by using a naive factorization approach.It is found that for Bc*→Bs,dπ,Bs,d*π,Bs,dρ,BsK,Bs*K,BsK*,ηc(1S,2S)π,ηc(1S,2S)ρandψ(1S,2S)πdecays,a few hundred and even thousands of events might be observable in CEPC,FCC-ee and LHCb@HL-LHC experiments.展开更多
In this work,we investigate the quasi-two-body decays B_(c)→D^(*)h→Dπhwithh=(K^(0),π^(0),η,η′)using the perturbative QCD(PQCD)approach.The description of final state interactions of the Dπpair is achieved thro...In this work,we investigate the quasi-two-body decays B_(c)→D^(*)h→Dπhwithh=(K^(0),π^(0),η,η′)using the perturbative QCD(PQCD)approach.The description of final state interactions of the Dπpair is achieved through the two-meson distribution amplitudes(DAs),which are normalized to the time-like form factor.The PQCD predictions on the branching ratios of the quasi-two-body decays B_(c)→D^(*)h→Dπh show an obvious hierarchy:Br(B^(+)_(c)→D^(∗+)K^(0)→D^(0)π^(+)K^(0))=(5.22^(+0.86)_(-0.74))×10^(-6),Br(B^(+)_(c)→D^(∗+)π^(0)→D^(0)π^(+)π^(0))=(0.93±0.26)×10^(-7),Br(B^(+)_(c)→D^(∗+)η→D^(0)π^(+)η)=(2.83^(+0.59)_(-0.52))×10^(-8)and Br(B^(+)_(c)→D^(∗+)η′→D^(0)π^(+)η′)=(1.89+0.40-0.36)×10^(-8).From the invariant mass m Dπ-dependence of the decay spectrum for each channel,one can find that the branching fraction is concentrated in a narrow region around the D*pole mass.Thus,one can obtain the branching ratios for the corresponding two-body decays B_(c)→D^(*+)h under the narrow-width approximation.We find that the branching ratios of the decays B_(c)→D^(*+)h are consistent with the previous PQCD calculations within errors.These predictions will be tested in future experiments.展开更多
Based on the assumption that Ds1(2536) and Ds2(2573) belong to T doublet (1^+,2^+), we calculate the semileptonic decays of Bs to Ds1(2536) and Ds2(2573) in terms of the Constituent Quark Meson (CQM) mod...Based on the assumption that Ds1(2536) and Ds2(2573) belong to T doublet (1^+,2^+), we calculate the semileptonic decays of Bs to Ds1(2536) and Ds2(2573) in terms of the Constituent Quark Meson (CQM) model. For Bs → Ds1 (2536)+ lv^- and B→ → Ds2 (2573)+lv^-, the order of magnitude of the obtained branching ratios is 10^-3. Our numerical results of the semileptonic decays of Bs to Ds1(2536) and Ds2(2573) are large, which implies that two semileptonic decays should be seen in future experiments.展开更多
We study the CP-averaged branching fractions and the CP-violating asymmetries in the pure annihilation decays of B^(s)_(0)→a^(+)_(0)a^(−)_(0)and B^(0)_(d)→K^(∗+)_(0)K^(∗−)_(0),where a_(0)[K^(∗)_(0)]denotes the scala...We study the CP-averaged branching fractions and the CP-violating asymmetries in the pure annihilation decays of B^(s)_(0)→a^(+)_(0)a^(−)_(0)and B^(0)_(d)→K^(∗+)_(0)K^(∗−)_(0),where a_(0)[K^(∗)_(0)]denotes the scalar a_(0)(980)and a_(0)(1450)[K^(∗)_(0)(800)(orκ)and K^(∗)_(0)(1430)],with the perturbative QCD factorization approach under the assumption of two-quark structure for the a_(0)and K^(∗)_(0)states.The numerical results show that the branching ratios of the B^(0)_(d)→K^(∗+)_(0)K^(∗−)_(0)decays are in the order of 10^(−6),while the decay rates of the B^(s)_(0)→a^(+)_(0)a^(−)_(0)modes are in the order of 10−5.In light of the measured modes with the same quark components in the pseudoscalar sector,namely,B^(0)_(d)→K^(+)k_(-)and B^(0)_(s)→π^(+)π_(−),the predictions for the considered decay modes in this work are expected to be measured at the Large Hadron Collider beauty and/or Belle-Ⅱexperiments in the(near)future.Meanwhile,it is of great interest to find that the twist-3 distribution amplitudesφ^(S)andφ^(T)with inclusion of the Gegenbauer polynomials for the scalar a_(0)(1450)and K^(∗)_(0)(1430)states in scenario 2 contribute slightly to the branching ratios while significantly to the CP violations in the B^(0)_(d)→K^(∗)_(0)(1430)+K^(∗)_(0)(1430)−and B^(0)_(s)→a_(0)(1450)+a_(0)(1450)−decays,which indicates that,compared to the asymptoticφ^(S)andφ^(T),these Gegenbauer polynomials could change the strong phases evidently in these pure annihilation decay channels.These predictions await for the future confirmation experimentally,which could further provide useful information to help explore the inner structure of the scalars and shed light on the annihilation decay mechanism.展开更多
We study the semileptonic decaysBc-→(ηc,J/ψ)l-■lusing the PQCD factorization approach with the newly defined distribution amplitudes of the B c meson and a new kind of parametrization for extrapolating the form fa...We study the semileptonic decaysBc-→(ηc,J/ψ)l-■lusing the PQCD factorization approach with the newly defined distribution amplitudes of the B c meson and a new kind of parametrization for extrapolating the form factors which takes into account the recent lattice QCD results.We find the following main results:(a)the PQCD predictions of the branching ratios of theBc→(ηc,J/ψ)l■decays are smaller by about 5%-16%when the lattice results are taken into account in the extrapolation of the relevant form factors;(b)the PQCD predictions of the ratio Rηc,RJ/ψand of the longitudinal polarization PτareRηc=0.34±0.01,RJ/ψ=0.28±0.01,Pτ(ηc)=0.37±0.01and Pτ(J/ψ)=-0.55±0.01;and(c)after including the lattice results,the theoretical predictions slightly change:Rηc=0.31±0.01,RJ/ψ=0.27±0.01,Pτ(ηc)=0.36±0.01andPτ(J/ψ)=-0.53±0.01.The theoretical predictions of RJ/ψagree with the measurements within the errors.The other predictions could be tested by the LHCb experiment in the near future.展开更多
The decay t→cV(V=γ,Z,g)processes in mirror twin Higgs models with colorless top partners are studied in this paper.We report that the branchi ng ratios of these decays can strongly affect the standard model expectat...The decay t→cV(V=γ,Z,g)processes in mirror twin Higgs models with colorless top partners are studied in this paper.We report that the branchi ng ratios of these decays can strongly affect the standard model expectations in some parameter spaces and may be detectable according to the current precision electroweak measurements.Thus,constraints on the model parameters may be obtained from the branching fraction of the decay processes,which may serve as a robust detection tool for this new physics model.展开更多
In a supersymmetric extension of the Standard Model(SM) where baryon and lepton numbers are local gauge symmetries(BLMSSM), we investigate the charged lepton flavor violating(CLFV) processes Z→li^±lj^ jaf...In a supersymmetric extension of the Standard Model(SM) where baryon and lepton numbers are local gauge symmetries(BLMSSM), we investigate the charged lepton flavor violating(CLFV) processes Z→li^±lj^ jafter introducing new gauginos and right-handed neutrinos. In this model, the branching ratios of Z→li^±lj^ jare around(10^-8–10^-10), which approach the present experimental upper bounds. We hope that the branching ratios for these CLFV processes can be detected in the near future.展开更多
By employing the perturbative QCD (pQCD) factorization approach, we calculate the full leading and the partial next-to-leading order (NLO) contributions to the seven B →πη(′) and η(′)η(′) decays. For...By employing the perturbative QCD (pQCD) factorization approach, we calculate the full leading and the partial next-to-leading order (NLO) contributions to the seven B →πη(′) and η(′)η(′) decays. For B^+→ π+η(′) decays, the pQCD predictions for their decay rates agree very well with the data after the inclusion of the small NLO contributions. For neutral decays, the pQCD predictions are also consistent with the experimental upper limits and can be tested by the LHC experiments. The measured value of dir .Acp^dir(π+η)= 19±7% can also be accommodated by the pQCD approach.展开更多
Recently,the CDF Collaboration has measured the branching fraction and time-integrated direct CP asymmetry of Bs → K-π+ decay.The branching ratio is lower than the previous predictions based on QCD factorization.Th...Recently,the CDF Collaboration has measured the branching fraction and time-integrated direct CP asymmetry of Bs → K-π+ decay.The branching ratio is lower than the previous predictions based on QCD factorization.The experimental results favor a large CP asymmetry in Bs → K-π+ decay while the standard model prediction is very small.We compute the supersymmetry contributions to Bs → K-π+ decay using the mass insertion method,and find that the LR and RL mass insertions could suppress this branching ratio and increase this direct CP asymmetry well in line with the experimental data.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.11174218)
文摘The autoionization branching ratios from Eu 4f76p1/26 d [J] autoionizing states to its 4f76s+(9So), 4f76s+(7So), and4f75d+(9Do) final ionic states are investigated with the combination of the three-step laser excitation and the velocity-map imaging technique. These different autoionizing states are excited via 4f76s6d8 DJ [J = 5/2, 7/2, and 9/2] intermediate states, respectively. The experimental photoelectron images are obtained, from which energy distributions of ejected electrons are achieved with the mathematical transformation. Furthermore, the energy dependence of the branching ratio is investigated within the autoionization resonance, by which population inversion is observed as an important characteristic.The J-dependence is also studied systematically. The validity of the well-known isolated core excitation technique used for obtaining the autoionization spectrum is also studied.
基金the National Natural Science Foundation of China(No.21803072)the Program for Young Outstanding Scientists of Institute of Chemistry,Chinese Academy of Science(ICCAS),and Beijing National Laboratory for Molecular Sciences(BNLMS).+1 种基金the National Aeronautics and Space Administration Award #80NSSC18K0592 and National Science Foundation under CHE-1763319.Yu SongWilliam.M.Jackson gratefully acknowledge the support of NSF under grants CHE-1301501 and AST-1410297.
文摘The photoabsorption and photodissociation of carbon monoxide(CO)in the vacuum ultraviolet(VUV)region is one of the most important photochemical processes in the interstellar medium,thus it has attracted numerous experimental and theoretical studies.Here,we employed the two-color VUV-VUV laser pump-probe time-slice velocity-map ion imaging method to measure the relative branching ratios[C(3P0)+O(1D)]/{[C(3P0)+O(3P)]+[C(3P0)+O(1D)]}and[C(3P2)+O(1D)]/{[C(3P2)+O(3P)]+[C(3P2)+O(1D)]}in the VUV photoexcitation energy range of 108000-113200 cm^−1.Here,one tunable VUV laser beam is used to excite CO to speci c rovibronic states,and a second independently tunable VUV laser beam is used to state-selectively ionize C(3P0)and C(3P2)for detection.State-selective photoionization through the 1VUV+1UV/visible resonance-enhanced multiphoton ionization scheme has greatly enhanced the detection sensitivity,which makes many new weak absorption bands observable in the current study.The branching ratio measurement shows that the spin-forbidden channels C(3P0)+O(1D)and C(3P2)+O(1D)only open at several discrete narrow energy windows.This might be caused by certain accidental resonanceenhanced spin-orbit interactions between the directly excited Rydberg states and valence states of triplet type which nally dissociate into the spin-forbidden channels.
基金Supported by National Natural Science Foundation of China (10535010, 10805026, 10775068, 10735010)Major State Basic Research Development Program (2007CB815004)Doctoral Fund of Ministry of Education of China (20070284016)
文摘We present a systematic calculation on the α-decay branching ratios to excited-states of an even-even α-decay chain ^242Cm → ^238Pu → ^234U → ^230Th → ^226Rn by the improved barrier penetration approach. The changes of the parities between the parent nuclei and the daughter nuclei are properly taken into account. The theoretical values are compared with the available experimental data and the deviation between them is within a factor of 5 in most cases.
基金Project supported by the National Natural Science Foundation of China(Grant No.11174218)
文摘The branching ratios of ions and the angular distributions of electrons ejected from the Eu 4f^76p_(1/2)nd auto-ionizing states are investigated with the velocity-map-imaging technique.To populate the above auto-ionizing states,the relevant bound Rydberg states have to be detected first.Two new bound Rydberg states are identified in the region between41150 cm^(-1)and 44580 cm^(-1),from which auto-ionization spectra of the Eu 4f^76p_(1/2)nd states are observed with isolated core excitation method.With all preparations above,the branching ratios from the above auto-ionizing states to different final ionic states and the angular distributions of electrons ejected from these processes are measured systematically.Energy dependence of branching ratios and anisotropy parameters within the auto-ionization spectra are carefully analyzed,followed by a qualitative interpretation.
文摘A detailed investigation of different decay modes,namely alpha decay,beta decay,cluster decay including heavy particle emission(Z_(c)>28),and spontaneous fission,was carried out,leading to the identification of new cluster and beta-plus emitters in superheavy nucle with 104≤Z≤126.For the first time,we identified around20 beta-plus emitters in superheavy nuclei.Heavy-particle radioactivity was observed in superheavy elements of atomic number in the range 116≤Z≤126.^(292-293)Og were identified as ^(86)Kr emitters,and ^(298)122 and ^(300)122 were identified as ^(94)Zr emitters,whereas heavy-particle radioactivity from ^(91)Y was also observed in ^(299)123.Furthermore,the nuclei ^(300)124 and ^(306)126 exhibit ^(96)Mo radioactivity.The reported regions of beta-plus and heavyparticle radioactivity for superheavy nuclei are stronger than those for alpha decay.The identified decay modes for superheavy nuclei are presented in a chart.This study is intended to serve as a reference for identifying possible decay modes in the superheavy region.
基金supported by the National Key Scientific Instrument and Equipment Development Projects of China (2014YQ120351)National Natural Science Foundation of China (11704372)Anhui Provincial Natural Science Foundation (1708085QF130)
文摘This work introduces the branching ratio(BR) method for determining relative spectral responses,which are needed routinely in laser induced breakdown spectroscopy(LIBS). Neutral and singly ionized Ti lines in the 250–498 nm spectral range are investigated by measuring laser-induced micro plasma near a Ti plate and used to calculate the relative spectral response of an entire LIBS detection system. The results are compared with those of the conventional relative spectral response calibration method using a tungsten halogen lamp, and certain lines available for the BR method are selected. The study supports the common manner of using BRs to calibrate the detection system in LIBS setups.
文摘The intrinsic product polarization and intramolecular isotope effect of the S(~1D,~3P) + HD reaction have been investigated on both the lowest singlet state(1A) and the triplet state(3A and 3A) potential energy surfaces by using quasi-classical trajectory and quantum mechanical methods.The calculations indicate that intramolecular isotope effects are different on the three electronic states.The stereodynamics study shows that the P(θr) distributions,P(φ r) distributions,and polarization-dependent differential cross sections(PDDCSs)(00) are sensitive to mass factor and the product angular momentum vectors are not only aligned but also oriented.
文摘This paper purposes an explanation for the recent evidence for the violation of lepton universality in beauty-quark decays at CERN’s Large Hadron Collider. A beauty meson (B<sup>+</sup>) transforms into a strange meson (K<sup>+</sup>) with the emission of either electron-positron (e<sup>+</sup>e<sup>-</sup>) or muon-antimuon (<span style="white-space:nowrap;"><em>μ</em></span><sup>+</sup><em>μ</em><sup>-</sup>). The ratio (<em>R</em><sub>K</sub>) of branching fractions for B<sup>+ </sup><span style="white-space:nowrap;">→</span> K<sup>+</sup><em>μ</em><sup>+</sup><em>μ</em><sup>- </sup>and B<sup>+</sup><span style="white-space:nowrap;">→</span> K<sup>+</sup>e<sup>+</sup>e<sup>-</sup> decays is measured to be <em>R</em><sub>K</sub> = 0.846 instead of 1 in the violation of lepton universality in the Standard Model. This paper proposes that the violation is derived from the binary isotope mixture of two beauty-quarks, b<sub>7</sub> (4979 MeV mass) and b<sub>8</sub> (143,258 MeV mass) whose masses are calculated from the periodic table of elementary particles. b<sub>7</sub> is the observable B, while b<sub>8</sub> is the hidden B to preserve the generation number symmetry between the three lepton family generations and the three quark family generations in the Standard Model. The preservation of the generation number symmetry forbids b<sub>8</sub> to decay into K<sup>+</sup><em>μ</em><sup>+</sup><em>μ</em><sup>-</sup>. In the transition state involving the virtual particles (<span style="white-space:nowrap;"><em>γ</em></span>, W± and Z<span style="white-space:nowrap;">°</span>) before the decay, b<sub>7</sub> and b<sub>8</sub> emerge to form the binary isotope mixture from B. The rates of emergence as the rates of diffuse in Graham’s law of diffusion are proportional to inverse square root of mass. The rate ratio between b<sub>8</sub>/b<sub>7</sub> is (4979/143,258)<sup>1/2</sup> = 0.1864. Since b<sub>7</sub> decays into K<sup>+</sup>, e<sup>+</sup>e<sup>-</sup>, and <em>μ</em><sup>+</sup><em>μ</em><sup>-</sup>, while b<sub>8</sub> decays into K<sup>+</sup>, e<sup>+</sup>e<sup>-</sup>, and forbidden <em>μ</em><sup>+</sup><em>μ</em><sup>-</sup>, the calculated ratio (RK) of branching fractions for B<sup>+</sup><span style="white-space:nowrap;">→</span> K<sup>+</sup><em>μ</em><sup>+</sup><em>μ</em><sup>-</sup> and B<sup>+</sup><span style="white-space:nowrap;">→</span> K<sup>+</sup>e<sup>+</sup>e<sup>- </sup>is 0.5/(0.1864 × 0.5+ 0.5) = 0.843 in excellent agreement with the observed 0.846. The agreement between the calculated RK and the observed RK confirms the validity of the periodic table of elementary particles which provides the answers for the dominance of matter over antimatter, dark-matter, and the mass hierarchy of elementary particles.
基金Supported by National Nature Science Foundation of China(11275266)Youth Innovation Promotion Association CAS
文摘A maximum likelihood method is used to deal with the combined estimation of multi-measurements of a branching ratio, where each result can be presented as an upper limit. The joint likelihood function is constructed using observed spectra of all measurements and the combined estimate of the branching ratio is obtained by maxi- mizing the joint likelihood function. The Bayesian credible interval or upper limit of the combined branching ratio, is given in cases both with and without inclusion of systematic error.
基金Supported by National Natural Science Foundation of China (10491303, 10775412, 10825524, 10935008)Instrument Developing Project of Chinese Academy of Sciences (YZ200713)+1 种基金Major State Basic Research Development Program (2009CB825206)Knowledge Innovation Project of Chinese Academy of Sciences (KJCX2-YW-N29)
文摘We have examined the parametrization of the e^+e^- → ωπ0 cross section in the vicinity of the φ resonance and the extraction of the branching fraction of the isospin violating process φ → ωπ0 from experimental data. We found that there are two possible solutions of the branching fraction: one is 4 × 10-5, and the other is 7×10^-3. The latter is two orders of magnitude higher than the former, which is the commonly accepted one.
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 National Natural Science Foundation of China(11705047,12275068,U1632109,11875122)the Natural Science Foundation of Henan Province,China(222300420479)the Excellent Youth Foundation of Henan Province,China(212300410010)。
文摘The ground vector Bc*meson has not yet been experimentally discovered until now.Besides the dominant electromagnetic decays,nonleptonic weak decays provide another choice to search for the mysterious Bc*mesons.Inspired by the potential prospects of Bc*mesons in future high-luminosity colliders,nonleptonic Bc*weak decays induced by bottom and charm quark decays are studied within the SM by using a naive factorization approach.It is found that for Bc*→Bs,dπ,Bs,d*π,Bs,dρ,BsK,Bs*K,BsK*,ηc(1S,2S)π,ηc(1S,2S)ρandψ(1S,2S)πdecays,a few hundred and even thousands of events might be observable in CEPC,FCC-ee and LHCb@HL-LHC experiments.
基金Supported by the National Natural Science Foundation of China(11347030)the Program of Science and Technology Innovation Talents in Universities of Henan Province,China(14HASTIT037)the Natural Science Foundation of Henan Province,China(232300420116)
文摘In this work,we investigate the quasi-two-body decays B_(c)→D^(*)h→Dπhwithh=(K^(0),π^(0),η,η′)using the perturbative QCD(PQCD)approach.The description of final state interactions of the Dπpair is achieved through the two-meson distribution amplitudes(DAs),which are normalized to the time-like form factor.The PQCD predictions on the branching ratios of the quasi-two-body decays B_(c)→D^(*)h→Dπh show an obvious hierarchy:Br(B^(+)_(c)→D^(∗+)K^(0)→D^(0)π^(+)K^(0))=(5.22^(+0.86)_(-0.74))×10^(-6),Br(B^(+)_(c)→D^(∗+)π^(0)→D^(0)π^(+)π^(0))=(0.93±0.26)×10^(-7),Br(B^(+)_(c)→D^(∗+)η→D^(0)π^(+)η)=(2.83^(+0.59)_(-0.52))×10^(-8)and Br(B^(+)_(c)→D^(∗+)η′→D^(0)π^(+)η′)=(1.89+0.40-0.36)×10^(-8).From the invariant mass m Dπ-dependence of the decay spectrum for each channel,one can find that the branching fraction is concentrated in a narrow region around the D*pole mass.Thus,one can obtain the branching ratios for the corresponding two-body decays B_(c)→D^(*+)h under the narrow-width approximation.We find that the branching ratios of the decays B_(c)→D^(*+)h are consistent with the previous PQCD calculations within errors.These predictions will be tested in future experiments.
基金Natural Science Fund of Hebei Province (A2005000090,E2005000129)Fund of Education Department of HebeiProvince (2007409)Natural Science Fund of Hebei University (2005007)
文摘Based on the assumption that Ds1(2536) and Ds2(2573) belong to T doublet (1^+,2^+), we calculate the semileptonic decays of Bs to Ds1(2536) and Ds2(2573) in terms of the Constituent Quark Meson (CQM) model. For Bs → Ds1 (2536)+ lv^- and B→ → Ds2 (2573)+lv^-, the order of magnitude of the obtained branching ratios is 10^-3. Our numerical results of the semileptonic decays of Bs to Ds1(2536) and Ds2(2573) are large, which implies that two semileptonic decays should be seen in future experiments.
基金supported in part by the National Natural Science Foundation of China under Grant Nos.11765012 and 11205072by the Research Fund of Jiangsu Normal University(No.HB2016004)supported by the Undergraduate Research&Practice Innovation Program of Jiangsu Province(No.201810320103Z)。
文摘We study the CP-averaged branching fractions and the CP-violating asymmetries in the pure annihilation decays of B^(s)_(0)→a^(+)_(0)a^(−)_(0)and B^(0)_(d)→K^(∗+)_(0)K^(∗−)_(0),where a_(0)[K^(∗)_(0)]denotes the scalar a_(0)(980)and a_(0)(1450)[K^(∗)_(0)(800)(orκ)and K^(∗)_(0)(1430)],with the perturbative QCD factorization approach under the assumption of two-quark structure for the a_(0)and K^(∗)_(0)states.The numerical results show that the branching ratios of the B^(0)_(d)→K^(∗+)_(0)K^(∗−)_(0)decays are in the order of 10^(−6),while the decay rates of the B^(s)_(0)→a^(+)_(0)a^(−)_(0)modes are in the order of 10−5.In light of the measured modes with the same quark components in the pseudoscalar sector,namely,B^(0)_(d)→K^(+)k_(-)and B^(0)_(s)→π^(+)π_(−),the predictions for the considered decay modes in this work are expected to be measured at the Large Hadron Collider beauty and/or Belle-Ⅱexperiments in the(near)future.Meanwhile,it is of great interest to find that the twist-3 distribution amplitudesφ^(S)andφ^(T)with inclusion of the Gegenbauer polynomials for the scalar a_(0)(1450)and K^(∗)_(0)(1430)states in scenario 2 contribute slightly to the branching ratios while significantly to the CP violations in the B^(0)_(d)→K^(∗)_(0)(1430)+K^(∗)_(0)(1430)−and B^(0)_(s)→a_(0)(1450)+a_(0)(1450)−decays,which indicates that,compared to the asymptoticφ^(S)andφ^(T),these Gegenbauer polynomials could change the strong phases evidently in these pure annihilation decay channels.These predictions await for the future confirmation experimentally,which could further provide useful information to help explore the inner structure of the scalars and shed light on the annihilation decay mechanism.
基金Supported by the National Natural Science Foundation of China(11775117,11235005)
文摘We study the semileptonic decaysBc-→(ηc,J/ψ)l-■lusing the PQCD factorization approach with the newly defined distribution amplitudes of the B c meson and a new kind of parametrization for extrapolating the form factors which takes into account the recent lattice QCD results.We find the following main results:(a)the PQCD predictions of the branching ratios of theBc→(ηc,J/ψ)l■decays are smaller by about 5%-16%when the lattice results are taken into account in the extrapolation of the relevant form factors;(b)the PQCD predictions of the ratio Rηc,RJ/ψand of the longitudinal polarization PτareRηc=0.34±0.01,RJ/ψ=0.28±0.01,Pτ(ηc)=0.37±0.01and Pτ(J/ψ)=-0.55±0.01;and(c)after including the lattice results,the theoretical predictions slightly change:Rηc=0.31±0.01,RJ/ψ=0.27±0.01,Pτ(ηc)=0.36±0.01andPτ(J/ψ)=-0.53±0.01.The theoretical predictions of RJ/ψagree with the measurements within the errors.The other predictions could be tested by the LHCb experiment in the near future.
基金Supported by the National Natural Science Foundation of China(11775012,11675147)the Fundamental Research Cultivation Fund for Young Teachers of Zhengzhou University(JC202041040)the Academic Improvement Project of Zhengzhou University。
文摘The decay t→cV(V=γ,Z,g)processes in mirror twin Higgs models with colorless top partners are studied in this paper.We report that the branchi ng ratios of these decays can strongly affect the standard model expectations in some parameter spaces and may be detectable according to the current precision electroweak measurements.Thus,constraints on the model parameters may be obtained from the branching fraction of the decay processes,which may serve as a robust detection tool for this new physics model.
基金Supported by Major Project of NNSFC(11535002,11605037,11647120,11275036)Natural Science Foundation of Hebei Province(A2016201010,A2016201069)+1 种基金Natural Science Fund of Hebei University(2011JQ05,2012-242)Hebei Key Lab of Optic-Electronic Information and Materials,the Midwest Universities Comprehensive Strength Promotion Project
文摘In a supersymmetric extension of the Standard Model(SM) where baryon and lepton numbers are local gauge symmetries(BLMSSM), we investigate the charged lepton flavor violating(CLFV) processes Z→li^±lj^ jafter introducing new gauginos and right-handed neutrinos. In this model, the branching ratios of Z→li^±lj^ jare around(10^-8–10^-10), which approach the present experimental upper bounds. We hope that the branching ratios for these CLFV processes can be detected in the near future.
基金Supported by National Natural Science Foundation of China (10575052, 10735080)Specialized Research Fund for Doctoral Program of Higher Education (SRFDP) (20050319008)
文摘By employing the perturbative QCD (pQCD) factorization approach, we calculate the full leading and the partial next-to-leading order (NLO) contributions to the seven B →πη(′) and η(′)η(′) decays. For B^+→ π+η(′) decays, the pQCD predictions for their decay rates agree very well with the data after the inclusion of the small NLO contributions. For neutral decays, the pQCD predictions are also consistent with the experimental upper limits and can be tested by the LHC experiments. The measured value of dir .Acp^dir(π+η)= 19±7% can also be accommodated by the pQCD approach.
基金Supported by National Natural Science Foundation of China (10675039, 10735080)
文摘Recently,the CDF Collaboration has measured the branching fraction and time-integrated direct CP asymmetry of Bs → K-π+ decay.The branching ratio is lower than the previous predictions based on QCD factorization.The experimental results favor a large CP asymmetry in Bs → K-π+ decay while the standard model prediction is very small.We compute the supersymmetry contributions to Bs → K-π+ decay using the mass insertion method,and find that the LR and RL mass insertions could suppress this branching ratio and increase this direct CP asymmetry well in line with the experimental data.