We study $bar{Q}Qbar{q}q$ and $bar{Q}qQbar{q}$ molecular states as mixed states in QCD sum rules. By calculating the two-point correlation functions of pure states of their corresponding currents, we review the mass and coupling constant predictions
of $J^{PC}=1^{++}$, $1^{--}$, $1^{-+}$ molecular states. By calculating the two-point mixed correlation functions of $bar{Q}Qbar{q}q$ and $bar{Q}qQbar{q}$ molecular currents, and we estimate the mass and coupling constants of the corresponding ``physical state that couples to both $bar{Q}Qbar{q}q$ and $bar{Q}qQbar{q}$ currents. Our results suggest that $1^{++}$ states are more likely mixing from $bar{Q}Qbar{q}q$ and $bar{Q}qQbar{q}$ components, while for $1^{--}$ and $1^{-+}$ states, there is less mixing between $bar{Q}Qbar{q}q$ and $bar{Q}qQbar{q}$. Our results suggest the $Y$ series of states have more complicated components.
We calculate the complete form of the dimension-8 condensate contributions in the two-point correlator of the ($1^{-+}$,$0^{++}$) light hybrid current considering the operator mixing under renormalization. We find the inclusion these higher power cor
rections as well as the update of $langle g^3G^3rangle$ increase the QCD sum rule mass prediction for the $1^{-+}$ light hybrid. The obtained conservative mass range 1.72--2.60 GeV does not favor the $pi_1(1400)$ and the $pi_1(1600)$ to be pure hybrid states and suggests the $pi_1(2015)$ observed by E852 is more likely to have much of a hybrid constituent. We also study the $b_1pi$ and $rhopi$ decay patterns of the $1^{-+}$ light hybrid with light-cone QCD sum rules. We obtain a relatively large partial decay width of the $b_1pi$ mode, which is consistent with the predictions from the flux tube models and lattice QCD. More interestingly, using the tensor interpolating current we find the partial decay width of the $rhopi$ mode is small due to the absence of the leading twist contribution in the light-cone expansion of the correlation function.
We calculate the coefficients of the dimension-8 quark and gluon condensates in the current-current correlator of $1^{-+}$ light hybrid current $gbar{q}(x)gamma_{ u}iG_{mu u}(x)q{(x)}$. With inclusion of these higher-power corrections and updating th
e input parameters, we re-analyze the mass of the $1^{-+}$ light hybrid meson from Monte-Carlo based QCD sum rules. Considering the possible violation of factorization of higher dimensional condensates and variation of $langle g^3G^3rangle$, we obtain a conservative mass range 1.72--2.60,GeV, which favors $pi_{1}(2015)$ as a better hybrid candidate compared with $pi_{1}(1600)$ and $pi_{1}(1400)$.
The supersymmetry (SUSY) may be one of the most favorable extensions of the standard model (SM), however, so far at LHC no evidence of the SUSY particles were observed. An obvious question is whether they have already emerged, but escaped from our de
tection, or do not exist at all. We propose that the future ILC may provide sufficient energy to produce SUSY particles if they are not too heavy in the low background environment. The superflavor symmetry associates baryons with mesons as long as both of them containing a heavy constituent and a light one. In this work, we estimate the production rate of SUSY baryons near their production threshold in terms of the $Bbar B$ production data. Our analysis indicates that if the SUSY baryons with masses below $sqrt s/2$ ($sqrt s$ is the ILC energy) exist, they could be observed at future ILC.
In this paper, we re-analyze the $1^{-+}$ and $0^{++}$ light hybrids from QCD sum rules with a Monte-Carlo based uncertainty analysis. With $30%$ uncertainties in the accepted central values for QCD condensates and other input parameters, we obtain a
prediction on $1^{-+}$ hybrid mass of $1.71 pm 0.22$,GeV, which covers the mass of $pi_1(1600)$. However, the $0^{++}$ hybrid mass prediction is more than 4,GeV, which is far away from any known $a_0$ meson. We also study the correlations between the input and output parameters of QCD sum rules.
QCD sum-rules are employed to determine whether the X(3872) can be described as a mixed state that couples to $J^{PC}=1^{++}$ charmonium hybrid and $bar D D^*$ molecular currents. After calculating the mixed correlator of hybrid and molecular current
s, we formulate the sum-rule in terms of a mixing parameter that interpolates between the pure molecular and hybrid scenarios. As the mixing parameter is increased from the pure molecular case, the predicted mass increases until it reaches a maximum value in good agreement with the X(3872) and the resulting sum-rule analysis appears more robust than the pure molecular case.
