相关论文: Four-quark state in QCD

We perform a QCD sum rule calculation to determine the mass and the parity of the lowest lying pentaquark state. We include operators up to dimension $d=13$ in the OPE and the direct instanton contributions. We find evidence for a positive…

The QCD/HQET matching coefficient for the heavy-quark field is calculated up to four loops. It must be finite; this requirement produces analytical results for some terms in the four-loop on-shell heavy-quark field renormalization constant…

We present a next-to-leading order QCD sum rule analysis of $J^{PC}=1^{-+}$ light tetraquark states. By investigating various compact tetraquark and molecular configurations, we determine the mass spectrum of these states. Our calculations…

We determine the equation of state of QCD for nonzero chemical potentials via a Taylor expansion of the pressure. The results are obtained for N_f=2+1 flavors of quarks with physical masses, on various lattice spacings. We present results…

We calculate the equation of state at non-zero temperature and density from first principles in two-, three- and four-color QCD with two fermion flavors in the fundamental and two-index, antisymmetric representation. By matching low-energy…

The density of states method is applied for lattice QCD at a finite isospin density. The advantage of this method is that one can easily obtain results for various values of parameters (quark mass, coupling constant and the number of…

The research presented here uses QCD sum rules (QSR) to study exotic hadrons. There are several themes in this work. First is the use of QSR to predict the masses of exotic hadrons that may exist among the heavy quarkonium-like states. The…

For the case of two light flavors we propose the stringy description of the system made of one heavy and one light quark-antiquark pair, with the aim of exploring the two lower-lying Born-Oppenheimer potentials as a function of a separation…

The one-loop QCD heavy quark potential is computed to order v^2 in the color singlet and octet channels. Several errors in the previous literature are corrected. To be consistent with the velocity power counting, the full dependence on |p'…

We calculate color electric fields of quark/antiquark ($\bar{q}q$) and 3 quark ($qqq$) systems within the chromodielectric model (CDM). We explicitly evaluate the string tension of flux tubes in the $\bar{q}q$--system and analyze their…

We study the lowest-lying scalar mesons in the QCD sum rule by considering them as tetraquark states. We find that there are five independent currents for each state with a certain flavor structure. By forming linear combinations, we find…

We compute potentials of two static antiquarks in the presence of two quarks $qq$ of finite mass using lattice QCD. In a second step we solve the Schr\"odinger equation, to determine, whether the resulting potentials are sufficiently…

Within the framework of the heavy quark effective theory, QCD sum rules are used to calculate the masses of p-wave (c-bar s) states. The results for 0^+ and 1^+ states with the angular momentum of the light component j_l=1/2 are consistent…

In this article, we take the point of view that Y(2175) be a tetraquark state which consists of color octet constituents, and calculate its mass and decay constant within the framework of the QCD sum rule approach. We release standard…

The static potential between an infinitely heavy quark and antiquark is derived in the framework of perturbative QCD to three loops by performing a full calculation of the two-loop diagrams and using the renormalization group. The…

We investigate the pentaquark system $qqqs \bar q$ in a framework of chiral quark model. Two structures, $(qqq)(s\bar{q})$ and $(qqs)(q\bar{q})$, with all possible color, spin, flavor configurations are considered. The calculations show…

In this work, we distinguish the isospin unambiguously to construct the diquark-diquark-antiquark type five-quark currents with the isospin $I=\frac{1}{2}$, and study the $uudc\bar{c}$ pentaquark states with the QCD sum rules systematically…

Light-cone QCD sum rules are employed to compute the strong coupling constants: g_{B^* B^* pi}, g_{B_1 B_0 pi} and g_{B_1 B^* pi}, where (B,B^*) and (B_0,B_1) are negative and positive parity (0^-,1^-) and (0^+,1^+) \bar qQ doublets. The…

The mass spectra of light-heavy tetraquarks $cq\bar{c}\bar{q}$ (q= u, d) are computed in a non-relativistic diquark model with one-gluon exchange plus confining potential. In the diquark model, a $cq\bar{c}\bar{q}$ state is regarded to be…

In connection with recent discoveries of heavy-quark containing exotic states publications discussing $Qq$ diquarks ($Q,q$ stand for a heavy and light quarks, respectively) proliferated in the literature. After a brief summary of the…