EXISTENCE TIME FOR SOLUTIONS OFSEMILINEAR DIFFERENT SPEED KLEIN-GORDONSYSTEM WITH WEAK DECAY DATA IN 1D

A -4/3|log |-2 result is obtained for the existence time of solutions of semi- linear different speed Klein-Gordon system in one space dimension for weakly decaying Cauchy data, of size , in certain circumstances of nonlinearity.

Possibility of experimental study on nonleptonic B_(c)^(*) weak decays

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.

Search for the weak decayψ(3686)→■+c.c.

Using(448.1±2.9)×10^(6)ψ(3686)for the weak baryonic decayψ(3686)→Λc+∑-+c.c..The analysis procedure is optimized using a blinded method.No significant signal is observed,and the upper limit on the branching fraction(B)ofψ(3686)→Λc+∑-+c.c.is set as 1.4×10^(-5)at the 90%confidence level.

Study of C parity violating and strangeness changing J/ψ→ PP weak decays

Although J/ψ weak decays are rare,they are possible within the standard model of elementary particles.Inspired by the potential prospects of the future intensity frontier,the C parity violating J/ψ→πη^(′),ηη′decays and the strangeness changing J/ψ→πK,Kη^(′)decays are studied via the perturbative QCD approach.It is determined that the J/ψ→ηη^(′) decays have relatively large branching ratios,approximately on the order of 10^(11),which might be within the measurement capability and sensitivity of the future STCF experiment.

Weak decays of heavy baryons in the light-front approach

In this work, we analyse semi-leptonic and non-leptonic weak decays of the heavy baryons： Λ_b,Ξ_b,Ωb and Λ_c,Ξ_c,Ωc. For non-leptonic decay modes, we study only the factorizable channels induced by the external Wemission. The two spectator quarks in the baryonic transitions are treated as a diquark and form factors are calculated in the light-front approach. Using the results for form factors, we also calculate some corresponding semi-leptonic and non-leptonic decay widths. We find that our results are comparable with the available experimental data and other theoretical predictions. Decay branching fractions for many channels are found to reach the level 10^（-3）~10^（-2）,which is promising for discovery in future measurements at BESIII, LHCb and Belle II. The SU（3） symmetry in semi-leptonic decays is examined and sources of symmetry breaking are discussed.

Weak decays ofΞ^((′))_(c)→Ξin the light-front quark model

Without contamination from the final state interactions,the calculation of the branching ratios of semileptonic decays Ξ^((′))_(c)→Ξ+e^(+)ν_(e) may provide further information about the inner structure of charmed baryons.Moreover,by studying such processes,one can better determine the form factors of Ξ_(c)→Ξ that can be further applied to relevant estimates.In this study,we used the light-front quark model to carry out computations where the three-body vertex functions forΞ_(c) and Ξ are employed.To fit the new data of the Belle II,we re-adjusted the model parameters to obtain β_(s[sq])=1.07 GeV,which is 2.9 times larger than β_(ss)=0.366 GeV.This value may imply that the ss pair in Ξ constitutes a more compact subsystem.Furthermore,we investigated the non-leptonic decays of Ξ^((′))_(c)→Ξ,which will be experimentally measured soon.Thus,our model will be tested in terms of consistency with the new data.

A Novelty Solution to the Neutron Anomaly (An Anomalous Neutron or “Dark”?)

To explain the anomaly (τb ≠ τf) of the neutron lifetime τ in some experiments, in “bottle” τb and in “beam” τf, we resort to an anomalous form of the neutron na. This form belongs to one of two different states of the structure of the quark configurations making up the neutron (nucleon): first, an ordinary form Ψo, while the second is an “anomalous” form Ψa, difficult to detect and decay. If the ordinary configuration is present in everyone nuclear processes, to strong and weak interactions, and in diffusion processes, the anomalous form can emerge, in casual way and probabilistic, in some processes of fusion with production of neutrons and can be highlighted in some experiments as those in “bottle” and in “beam”, see the anomaly of the neutron lifetime. We show that the anomalous form Ψa can be highlighted in the coupling between a dipoles’ lattice of virtual bosons W and the neutron (nucleon) because the neutron into anomalous configuration does not decays. Finally, we interpret the anomalous neutron as a “dark” neutron, presenting, so, the dark matter as an anomalous form of hadron matter.

Hyperon weak radiative decay

We revisit the hyperon weak radiative decays in the framework of the non-relativistic constituent quark model. This study confirms the nonlocal feature of the hyperon weak radiative transition operators, which are dominated by the pole terms, and an overall self-consistent description of the available experimental data for the Cabibbofavored hyperon weak radiative decays is presented. It provides a natural mechanism for evading the Hara theorem,where sizeable parity-violating contributions can come from the intermediate orbital excitations. Cancellations between pole terms also explain the significant SU(3) flavor symmetry breaking manifested by the experimental data. We also discuss several interesting selection rules arising from either the electromagnetic or the weak interaction vertices. These features suggest nontrivial relations among various hyperon decays.

Mini-review of rare charmonium decays at BESⅢ

Recently, the LHCb experiment announced 3.5σ evidence for direct CP violation in D0 decay by looking at the difference between A CP （D0 → K＋ K- ） and A CP （D0 →π＋ π- ）. This is the first evidence of CP violation in a charm system, which may indicate new physics beyond the Standard Model. Motivated by this measurement, we review rare processes in charmonium decay, especially, the weak decay, C or P violated decay, and lepton flavor violated decays. In case the new physics appears in charm sector, these rare decays of charmonium states will provide an opportunity to search for significant contributions from physics beyond the Standard Model. With huge J/ψ and ψ（2S） samples in BES experiment, the rare decays may be feasible.

Effects of vector leptoquarks onΛb→Λ,lv^-l decay

Experimental data on R(D^(+)).R(K^(+)),and R(J/ψ),provided by different collaborations,show sizable deviations from the standard model predictions.To describe these anomalies,many new physics scenarios have been proposed.One of them is the leptoquark model,which introduces the simultaneous coupling of vector and scalar leptoquarks to quarks and leptons.To look for similar possible anomalies in the baryonic sector,we investigate the effects of a vector leptoquark U3(3,3,2/3)on various physical quantities related to the tree-levelΛb→Λclv^-l decays(l=u,t),which proceed via b→c l v^-l transiti ons at the quark level.We calculate the differential branching ratio,forward-backward asymmetry,and longitudinal polarizations of leptons and Ac baryons at theμandτlepton channels in the leptoquark model and compare their behavior to the predictions of the SM in terms of q^2.In the calculations,we use the form factors calculated in full QCD as the main input and account for all errors coming from the form factors and model parameters.We observe that at theτchanneL the Ra fit solution to data related to the leptoquark model sweeps some regions out of the SM band;nevertheless,the fit has a considerable intersection with the SM predictions.The Rr type solution gives roughly the same results as the SM on DBR(q^2)-q^2.At theμchannel.the leptoquark model gives results that are consistent with the SM predictions and existing experimental data on the behavior of DBR(q^2)with respect to q^2.Concerning the q^2 behavior of the AFB(q^2),the two types of fits forτand the predictions at the“channel in the leptoquark model give exactly the same results as the SM.We also investigate the behavior of the parameter R(q^2)with respect to q^2 and the value of R(Λc)in both the vector leptoquark and SM models.Both fit solutions lead to results that deviate considerably from the SM predictions for R(q^2)-q^2 and R(Ac).Future experimental data on R(q^2)-q^2 and RC made available by measurements of theΛb→Λcτv^-τchannel,will be particularly helpful.Any experimental deviations from the SM predictions in this channel would emphasize the im porta nee of tree-level hadronic weak tran sitions as good probes of new physics effects beyond the SM.

B_u→ψM decays and S-D wave mixing effects

The Bu→ψM decays are studied with the perturbative QCD approach, where the psion ψ=ψ（2S）, ψ（3770）, ψ（4040） and ψ（4160）, and the light meson M = π, K, ρ and K^＊. The factorizable and non-factorizable contributions, and the S-D wave mixing effects on the psions, are considered in the calculation. With appropriate inputs, the branching ratios for the Bu→ψM decays are generally coincident with the experimental data within errors. However, due to the large theoretical and experimental errors, it is impossible for the moment to give a severe constraint on the S-D wave mixing angles.

Rare semileptonic decays of heavy mesons in the heavy quark limit

We study the branching ratios of D^＋ → D^0e^＋ν, Ds^＋ → D^0e^＋ν, Bs^0→B^＋e^-^-ν, Ds^＋→D^＋e^-e^＋ and Bs^0→B^0e^-e^＋ rare semileptonic decay processes, which are induced by decays of light quarks, the heavy quarks remain unchanged. The branching ratios of these decay processes are estimated in the heavy quark limit and with SU（3） flavor symmetry. We find that the decay rates are very tiny in the framework of the Standard Model. We also estimate the sensitivities of the measurements of these rare decays at the future experiments, such as BES-Ⅲ, super-B and LHC-b. Observations of these decays may shed some light on new physics beyond the standard model.

Study of the B_c→B_sπ decay with the perturbative QCD approach

The Bc → Bsπ decay is studied with the perturbative QCD approach. Three types of wave functions for Bs meson are considered. The transition form factor F0Bc → Bsπ （0） and the branching ratio IBr（Bc → Bsπ） are sensitive to the model of the Bs meson wave functions. With appropriate inputs, our estimate on 23r（Bc → Bsπ） is comparable with the recent LHCb measurement. A clear signal of Bc → Bsπ decay should be easily observed at the Large Hadron Collider.

Roles of tensor and isoscalar pairing interactions in β-decay calculations for possible r-process waiting point nuclei with N~82 and 126

In this study,we adopt the self-consistent Hartree-Fock-Bogoliubov(HFB) theory with the proton-neutron quasi-particle random phase approximation(pnQRPA) based on the Skyrme force for calculation of the β^(-) -decay half-lives for nuclei with N~82 and 126 on possible r-process paths.In the calculations,the Skyrme interaction(e.g.,SKO’) is adopted,and the tensor interaction is added self-consistently in both HFB and QRPA calculations.We systematically study how the half-life is changed by varying the strength of the triplet-even(TE) and triplet-odd(TO) components as well as the IS pairing.We find that a variation in strength of the IS pairing of approximately 20% does not produce a substantial effect on β-decay rates with or without the tensor force,while a strength variation of the TO tensor force considerably affects the change in the β-decay half-lives for the very neutron rich N~82 and 126 isotonic chains.In addition,with the inclusion of the tensor force,the GT decay becomes dominant for very neutron-rich nuclei.

Discovery potentials of doubly charmed baryons

The existence of doubly heavy flavor baryons has not been well established experimentally so far. In this Letter we systematically investigate the weak decays of the doubly charmed baryons, Ξ;and Ξ;, which should be helpful for experimental searches for these particles. The long-distance contributions are first studied in the doubly heavy baryon decays, and found to be significantly enhanced. Comparing all the processes, Ξ;→Λ;K;π;π;andΞ;π;are the most favorable decay modes for experiments to search for doubly heavy baryons.

A family of double-beauty tetraquarks:Axial-vector state T^-bb;us^-

The spectroscopic parameters and decay channels of the axial-vector tetraquark Tho(in what follows,TAV)are explored using the quantum chromodynamics(QCD)sum rule method.The mass and coupling of this state are calculated using two-point sum rules by taking into account various vacuum condensates,up to 10 dimensions.Our prediction for the mass of this state m=(10215±250)MeV confirms that it is stable with respect to strong and electromagnetic decays and can dissociate to conventional mesons only via weak transformations.We investigate the dominant semileptonic■and nonleptonic T AV b:s^-→v10 b:s^-M decays of T AV b:s^-.In these processes,Z-b:s^-is a scalar tetraquark[be][us^-]built of a colo-triplet diquark and an antidiquark,whereas M is one of the vector mesonsρ^-,K^*(892),D^*(2010)^-,and D^*s-.To caleulate the partial w idths of these decays,we use the QCD three-point sum rule approach and evaluate the weak transition form factors Gi(i=0,1,2,3),which govem these processes.The full widthΓfull=(12.9±2.1)×10^-8 MeV and the mean lifetimeτ=5.1+0.99-0.71 fs of the tetraquark TAV are computed us-ing the aforementioned weak decays.The obtained information about the parametersof TAY and Zh,is useful for experimental investigations of these double-heavy exotic mesons.

Tensor form factors of P→P,S,V and A transitions within standard and covariant light-front approaches

We investigate the tensor form factors of,and A transitions within the standard light-front(SLF)and the covariant light-front(CLF)quark models(QMs).The self-consistency and Lorentz covariance of CLF QM are analyzed via these quantities,and the effects of zero-mode are discussed.For the and A transitions,besides the inconsistency between the results extracted via longitudinal and transverse polarization states,which is caused by the residual-dependent spurious contributions,we find and analyze a“novel”self-consistence problem of the traditional CLF QM,caused by different strategies for dealing with the trace term in CLF matrix element.A possible solution to the problems of traditional CLF QM is discussed and confirmed numerically.Finally,the theoret-ical predictions for the tensor form factors of some and()induced and A transitions are updated within the CLF QM with a self-consistent scheme.