Supersymmetry （SUSY） may be one of the most favored extensions of the Standard Model （SM）, but so far at the LHC no evidence of SUSY particles has been observed. An obvious question is whether they have already emerged but escaped our detection, or whether they do not exist at all. We propose that the future ILC may provide sufficient energy and luminosity to produce SUSY particles as long as they are not too heavy. Superflavor symmetry associates production rates of SUSY mesinos with those of regular mesons, because both contain a heavy constituent and a light one. In this work, we estimate the production rate of SUSY mesinos near their production threshold and compare it with BB production. Our analysis indicates that if SUSY mesinos with masses below √s/2 （√s is the ILC energy） exist, they could be observed at the future ILC or even the proposed CEPC in China.
The recent measurements on Rκ and Rπ imply that there exists a possible violation of the leptonic flavor universality which is one of the cornerstones of the Standard Model. It is suggested that a mixing between sterile and active neutrinos might induce such a violation. In this work we consider the scenarios with one or two sterile neutrinos to explicitly realize the data while the constraints from the available experiments have been taken into account. Moreover, as indicated in literature, the deviation of the real PMNS matrix from the symmetric patterns may be due to a μ-τ asymmetry, therefore the measurements on RD（Ds）eμ=F（D（Ds）→e＋νe）/Г（D（Ds）→μ＋νμ） and RD（Ds）μτ=Г（D（Ds）→μ＋νμ）Г（D（Ds）→ι＋ντ） （and for some other heavy mesons B± and Bc etc.） may shed more light on the physics responsible for the violation of the leptonic flavor universality. The data of BESⅢ are available to test the universality and that of future charm-tau factories will provide more accurate information. In this work, we will discuss RD（Ds）eμ and RD（Ds）μτ in detail and also briefly consider the cases for B± and Bc.
Since the birth of the quark model, the diquark, which is composed of two quarks, has been considered as a substantial structure of a color anti-triplet. This is not only a mathematical simplification for dealing with baryons, but also provides a physical picture where the diquark would behave as a whole object. It is natural to ask whether such a structure is sufficiently stable against external disturbance. The mass spectra of the ground states of the scalar and axial-vector diquarks, which are composed of two-light （L-L）, one-light-one-heavy （H-L） and two-heavy （H-H） quarks, respectively, have been calculated in terms of the QCD sum rules. We suggest a criterion as the quantitative standard for the stability of the diquark. It is the gap between the masses of the diquark and x/~ where so is the threshold of the excited states and continuity, namely the larger the gap is, the more stable the diquark would be. In this work, we calculate the masses of the H-H type to complete the series of the spectra of the ground state diquarks. However, as the criterion being taken, we find that all the gaps for the various diquarks are within a small range. In particular, the gap for the diquark with two heavy quarks, which is believed to be a stable structure, is slightly smaller than that of the other two types of diquarks. Therefore we conclude that because of the large theoretical uncertainty, we cannot use the numerical results obtained with the QCD sum rules to assess the stability of diquarks, but need to invoke other theoretical framework.
For the detection of direct dark matter, in order to extract useful information about the funda- mental interactions from the data, it is crucial to properly determine the nuclear form factor. The form factor for the spin-independent cross section of collisions between dark matter particles and the nucleus has been thoroughly studied by many authors. When the analysis was carried out, the nuclei were always supposed to be spherically symmetric. In this work, we investigate the effects of the deformation of nuclei from a spherical shape to an ellipticM one on the form factor. Our results indicate that as long as the ellipticity is not too large, such deformation will not cause any substantial effects. In particular, when the nuclei are randomly orientated in room-temperature circumstances, one can completely neglect them.
