Abstract:
We examine the interpretation of the light scalar meson nonet as tetraquark states using QCD sum rules. With the interpolating current for the tetraquark states composed of scalar diquark and scalar antidiquark, first, we construct the QCD sum rules by means of the operator product expansion up to the operators of dimension 8 and show that there is no evidence of the coupling of the tetraquark states to the light scalar meson nonet. In order to have a stable sum rule, we propose a "good" interpolating current for the tetraquarks based on chirality arguments which includes scalar and pseudoscalar diquark--antidiquarks with equal weights. In particular, for the lowest tetraquark $\sigma$--meson, we perform detail analysis of the QCD sum rule and obtain mass for the $\sigma(600)$ around 780 MeV.

Abstract:
The flavor singlet axial charge has been a source of study in the last years due to its relation to the so called {\it Proton Spin Problem}. The relevant flavor singlet axial current is anomalous, i.e., its divergence contains a piece which is the celebrated $U_A(1)$ anomaly. This anomaly is intimately associated with the $\eta^\prime$ meson, which gets its mass from it. When the gauge degrees of freedom of QCD are confined within a volume as is presently understood, the $U_A(1)$ anomaly is known to induce color anomaly leading to "leakage" of the color out of the confined volume (or bag). For consistency of the theory, this anomaly should be cancelled by a boundary term. This ``color boundary term" inherits part or most of the dynamics of the volume (i.e., QCD). In this thesis, we exploit this mapping of the volume to the surface via the color boundary condition to perform a complete analysis of the flavor singlet axial charge in the chiral bag model using the Cheshire Cat Principle. This enables us to obtain the hitherto missing piece in the axial charge associated with the gluon Casimir effect. The result is that the flavor singlet axial charge is small independent of the confinement (bag) size ranging from the skyrmion picture to the MIT bag picture, thereby confirming the (albeit approximate) Cheshire Cat phenomenon.

Abstract:
We perform a QCD sum rule analysis for the $f_0$ light tetraquark taking into account the contribution arising from the two pion intermediate state. With the interpolating currents of the different chiral combinations of scalar and pseudoscalar diquarks, it is demonstrated that the interpolating current with maximum chirality has a large coupling to the two pion state, but the current with zero chirality interacts only weekly with this state. Taking into account the form factor in the $f_0$--two pion vertex, it is shown that the $f_0$--coupling to the two pion state leads to an increase of the lightest tetraquark mass by a value of about 100 MeV. The analysis of the resulting sum rule shows that the $\sigma(f_0(600))$--meson state might be treated as the four--quark bound state in the instanton field which has a rather strong coupling to the two pion state.

Abstract:
We perform a QCD sum rule analysis for the light scalar meson $\sigma$ ($f_0(600)$) with a tetraquark current related to the instanton picture for QCD vacuum. We demonstrate that instanton current, including equal weights of scalar and pseudoscalar diquark-antidiquarks, leads to a strong cancelation between the contributions of high dimension operators in the operator product expansion (OPE). Furthermore, in the case of this current direct instanton contributions do not spoil the sum rules. Our calculation, obtained from the OPE up to dimension 10 operators, gives the mass of $\sigma$--meson around 780MeV.

Abstract:
The Skyrme model, an effective low energy theory rooted in large $N_c$ QCD, has been applied to the study of dense matter. Matter is described by various crystal structures of skyrmions. When this system is heated, the dominating thermal degrees of freedom are the fluctuating pions. Taking these mechanisms jointly produces a description of the chiral phase transition leading to the conventional phase diagram with critical temperatures and densities in agreement with expected values.

Abstract:
Based on both the constituent quark picture and the instanton model for QCD vacuum, we calculate the unpolarized and polarized gluon distributions in the constituent quark and in the nucleon. Our approach consists of the two main steps. At the first step, we calculate the gluon distributions inside the constituent quark generated by the perturbative quark-gluon interaction, the non-perturbative quark-gluon interaction, and the non-perturbative quark-gluon-pion anomalous chromomagnetic interaction. The non-perturbative interactions are related to the existence of the instantons, strong topological fluctuations of gluon fields, in the QCD vacuum. At the second step, the convolution model is applied to derive the gluon distributions in the nucleon. A very important role of the pion field in producing the unpolarized and the polarized gluon distributions in the hadrons is discovered. We discuss a possible solution of the proton spin problem.

Abstract:
We perform a QCD sum rule analysis for the scalar $f_0(980)$ meson to investigate whether it can be described as a pure bound state of $K$ and $\bar{K}$ mesons. Based on the QCD sum rule with the operators of up to dimension 10 within the operator product expansion, we found that it is hard to treat the $f_0(980)$ as a simple $K\bar{K}$ bound state, which implies that the $f_0(980)$ scalar meson has more complicated structure being mixed states of various configurations.

Abstract:
The role of quark correlations in the description of hadron dynamics in many domains of physics, from low energy dynamics to very hot(dense) systems, is being appreciated. Strong correlations of two quarks (diquark) have been widely investigated in this respect. Recently, we have proposed a dynamical scheme to describe the $\Theta^+$ pentaquark in which also three quark correlations (triquark) were instrumental in producing a low mass exotic state. We perform a study, within the QCD sum rule approach including OPE and direct instanton contributions, of triquark correlations and obtain two quasi-bound light $ud\bar{s}$ color quark clusters of 800 MeV and 930 MeV respectively.

Abstract:
Two bisbenzylisoquinoline alkaloids, two morphine alkaloids, one aporphine alkaloid, syringaresinol and aristolochic acid ？ were selected as marker compounds and simultaneously analyzed using an ultra-high pressure liquid chromatography-diode array detection (UHPLC-DAD) method. These marker compounds were used for the quality control of Fangchi species of different origins, including Sinomenium acutum, Stephania tetrandra, Cocculus trilobus and Aristolochia fangchi. A reversed-phase UHPLC-DAD method was developed and validated for the simultaneous quantification of structurally diverse markers in different Fangchi species. In addition, an UHPLC-electrospray ionization tandem mass spectrometry (ESI-MS/MS) method was used for marker identification in Fangchi species, which provided diagnostic MS/MS spectral patterns that were dependent upon the marker structures. The UHPLC-MS/MS data were used to confirm and complement the UHPLC-DAD quality evaluation results. Additionally, magnoflorine and syringaresinol were observed for the first time in S. tetrandra and C. trilobus, respectively. Twenty different Fangchi species samples were analyzed for aristolochic acid I, syringaresinol and the alkaloids using the UHPLC-DAD and MS/MS method. Based on the levels of markers and principal component analysis (PCA), this method allowed for the clear classification of the samples into four different groups representing samples originating from the four species.

Abstract:
In continuation of our systematic effort to understand hadronic matter at high density, we study dense skyrmion matter and its chiral phase structure in an effective field theory implemented with the trace anomaly of QCD applicable in the large $N_c$ limit. By incorporating a dilaton field $\chi$ associated with broken conformal symmetry of QCD into the simplest form of skyrmion Lagrangian, we simulate the effect of "sliding vacua" influenced by the presence of matter and obtain what could correspond to the ``intrinsic dependence" on the background of the system, i.e., matter density or temperature, that results when a generic chiral effective field theory of strong interactions is matched to QCD at a matching scale near the chiral scale $\Lambda_\chi \sim 4\pi f_\pi\sim 1$ GeV. The properties of the Goldstone pions and the dilaton scalar near the chiral phase transition are studied by looking at the pertinent excitations of given quantum numbers on top of a skyrmion matter and their behavior in the vicinity of the phase transition from Goldstone mode to Wigner mode characterized by the changeover from the FCC crystal to the half-skyrmion CC crystal. We recover from the model certain features that are connected to Brown-Rho scaling and that suggest how to give a precise meaning to the latter in the framework of an effective field theory that is matched to QCD .