Beyond the quark model of hadrons from lattice QCD

Lattice QCD can give direct information on OZI-violating contributions to mesons. Here we explore the contributions that split flavour singlet and non-singlet meson masses. I discuss in detail the spectrum and decays for scalar mesons (i.e. including glueball effects). I also review the status of hybrid mesons and their decays.Received: 30 September 2002, Published online: 22 October 2003PACS: 12.38.Gc Lattice QCD calculations - 12.39.Mk Glueball and nonstandard multi-quark/gluon states     

A Lattice Study of the Glueball Spectrum

Glueball Spectrum is studied using an improved gluonic action on asymmetric lattices in the pure SU(3) gauge theory.The smallest spatial lattice spacing is about 0.08 fm which makes the extrapolation to the continuum limit more reliable.In particular.attention is paid to the scalar glueball mass which is known to have problems in the extrapolation.Converting our lattice results to physical units using the scale set by the static quark potential,we obtain the following results for the glueball masses:MG(0 )=1730(90)MeV for the scalar glueball mass and MG(2 )=2400(95)MeV for the tensor glueball.     

A remark on the large difference between the glueball mass and T<Subscript>c</Subscript> in quenched QCD

The lattice QCD studies indicate that the critical temperature T _c ≃ 260-280 MeV of the deconfinement phase transition in quenched QCD is considerably smaller than the lowest-lying glueball mass m _G ≃ 1500-1700 MeV, i.e., T _c ≪ m _G. As a consequence of this large difference, the thermal excitation of the glueball in the confinement phase is strongly suppressed by the statistical factor e ^-mG/Tc ≃ 0.00207 even near T ≃ T _c. We consider its physical implication, and argue the abnormal feature of the deconfinement phase transition in quenched QCD from the statistical viewpoint. To appreciate this, we demonstrate a statistical argument of the QCD phase transition using the recent lattice QCD data. From the phenomenological relation between T _c and the glueball mass, the deconfinement transition is found to take place in quenched QCD before a reasonable amount of glueballs is thermally excited. In this way, quenched QCD reveals a question “what is the trigger of the deconfinement phase transition ?” Received: 18 November 2002 / Accepted: 4 February 2003 / Published online: 29 April 2003     

A power-law coupled three-form dark energy model

We consider a field theory model of coupled dark energy which treats dark energy as a three-form field and dark matter as a spinor field. By assuming the effective mass of dark matter as a power-law function of the three-form field and neglecting the potential term of dark energy, we obtain three solutions of the autonomous system of evolution equations, including a de Sitter attractor, a tracking solution and an approximate solution. To understand the strength of the coupling, we confront the model with the latest Type Ia Supernova, Baryon Acoustic Oscillations and Cosmic Microwave Background radiation observations, with the conclusion that the combination of these three databases marginalized over the present dark matter density parameter \(\Omega _{m0}\) and the present three-form field \(\kappa X_{0}\) gives stringent constraints on the coupling constant, \(-\,0.017< \lambda <0.047\) (\(2\sigma \) confidence level), by which we present the model’s applicable parameter range.     

Scalar mesons in a chiral quark model with glueball

Ground-state scalar isoscalar mesons and a scalar glueball are described in a U(3)×U(3) chiral quark model of the Nambu-Jona-Lasinio (NJL) type with 't Hooft interaction. The latter interaction produces singlet-octet mixing in the scalar and pseudoscalar sectors. The glueball is introduced into the effective meson Lagrangian as a dilaton on the base of scale invariance. The mixing of the glueball with scalar isoscalar quarkonia and amplitudes of their decays into two pseudoscalar mesons are shown to be proportional to current quark masses, vanishing in the chiral limit. Mass spectra of the scalar mesons and the glueball and their main modes of strong decay are described. Received: 14 July 2000 / Accepted: 31 July 2000     

Renormalization of anisotropy and glueball masseson tadpole improved lattice gauge action

The Numerical calculations for tadpole-improved U(1) lattice gauge theory in three-dimensions on anisotropic lattices have been performed using standard path integral Monte Carlo techniques. Using average plaquette tadpole renormalization scheme, simulations were done with temporal lattice spacings much smaller than the spatial ones and results were obtained for the string tension, the renormalized anisotropy and scalar glueball masses. We find, by comparing the regular and sideways potentials, that tadpole improvement results in very little renormalization of the bare anisotropy and reduces the discretization errors in the static quark potential and in the glueball masses.Received: 19 March 2003, Revised: 26 August 2003, Published online: 24 October 2003     

The BES f<Subscript>0</Subscript>(1810): a new glueball candidate

We analyze the f₀(1810) state recently observed by the BES collaboration via radiative J/ψ decay to a resonant φω spectrum and confront it with DM2 data and glueball theory. The DM2 group only measured ωω decays and reported a pseudoscalar but no scalar resonance in this mass region. A rescattering mechanism from the open flavored KK̄ decay channel is considered to explain why the resonance is only seen in the flavor asymmetric ωφ branch along with a discussion of positive C-parity charmonia decays to strengthen the case for preferred open flavor glueball decays. We also calculate the total decay width of a glueball with this mass to be roughly 100 MeV, in agreement with the narrow, newly found f₀, and smaller than the expected estimate of 200–400 MeV. We conclude that this discovered scalar hadron deserves further experimental investigation, especially in the KK̄ channel, and if shown to be different from the f₀(1710), will become a solid glueball candidate. Finally we comment on other, but less likely, possible assignments for this state.     

Stringent tests of constrained Minimal Flavor Violation through ΔF=2 transitions

An extended version of the AdS/QCD soft-wall model that incorporates QCD-like anomalous contributions to the dimensions of gauge theory operators is proposed. This exploratory approach leads to a relation between scalar glueball masses and beta functions. Using this relation, the properties of the glueball mass spectroscopy that emerge from phenomenological beta functions proposed in the literature are investigated. The reverse problem is also considered: starting from a linear Regge trajectory which fits the lattice glueball masses, beta functions with different asymptotic infrared behaviors are found. Remarkably, some of them present a fixed point at finite coupling.     

混合效应在QCD求和规则下对标量胶球质量的影响

在QCD求和规则的框架下考虑了纯胶球和普通介子态的混合效应对二者质量的影响.在关联函数的构造中,胶子流和夸克流都被认为既和胶球态有耦合,也和夸克态有耦合.利用QCD低能定理,构造了一个混合关联函数.通过这些关系及两共振态近似,得出了0⁺⁺胶球和夸克态的质量,它们与各自的纯态的质量相差不大.     

Calculation of the glueball mass spectrum ofSU (2) andSU (3) non-abelian lattice gauge theories II:SU (3)

We calculate the glueball mass spectrum in theSU (3) lattice regularized gauge theory. We find fourlight glueballs: the 0⁺⁺, 2⁺⁺, 0^?+ and, most interestingly from the experimental point of view, the oddball 1^?+. We calculate the 0⁺⁺ and 2⁺⁺ masses over a range of β values and find thatboth states conform to continuum renormalization group behaviour to a very significant degree. The question of metastable states and temperature is addressed in detail. Finally we discuss and resolve contrary claims in the recent literature.     

Mass terms and mass renormalization for Susskind fermions

We discuss the symmetry properties of a geometrically motivated mass term giving different masses to the four flavours of Susskind fermions. Using this mass term we calculate the fermion self-energy in weak coupling perturbation theory at the one-loop level as well as the relation between the fermion masses on the lattice and in the continuum.     

Neutrino masses in the supersymmetric SU(3)C⊗SU(3)L⊗U(1)X model with right-handed neutrinos

The R-symmetry formalism is applied for the supersymmetric SU(3)_C⊗SU(3)_L⊗U(1)_X (3-3-1) model with right-handed neutrinos. For this kind of models, we study the generalization of the MSSM relation among R-parity, spin and matter parity. Discrete symmetries for the proton stable in this model are imposed, and we show that in such a case it is able to give leptons masses at only the tree level contributions required. A simple mechanism for the mass generation of the neutrinos is explored. We show that at the low-energy effective theory, the neutrino spectrum contains three Dirac fermions, one massless and two degenerate in mass. At the energy level where the mixing among them with the neutralinos is turned on, neutrinos obtain Majorana masses and correct the low-energy effective result which naturally gives rise to an inverted hierarchy mass pattern. This mass spectrum can fit the current data with minor fine-tuning. Consistent values for masses of the charged leptons are also given. In this model, the MSSM neutralinos and charginos can be explicitly identified in terms of the new constraints on masses which is not as in a supersymmetric version of the minimal 3-3-1 model. PACS 11.30.Er; 14.60.Pq; 14.60.-z; 12.60.Jv     

On the mass,width and coupling constants of the <Emphasis Type="Italic">f</Emphasis><Subscript><Emphasis Type="Italic">0</Emphasis></Subscript>(980)

Using the pole approach we determine the mass and width of the f ₀ (980); in particular, we analyze the possibility that two nearby poles are associated to it. We restrict our analysis to a neighborhood of the resonance, using data for the phase shift and inelasticity, and the invariant mass spectrum of the decays. The formalism we use is based on unitarity and a generalized ver sion of the Breit-Wigner parameterization. We find that a single pole describes the f ₀ (980), the precise position depending upon the data used. As a byproduct, values for the and coupling constants are obtained. Received: 6 June 2002 / Revised version: 21 October 2002 / Published online: 3 March 2003     

The Nonsymmetric Kaluza–Klein Theory and Modern Physics A Novel Approach

We consider in the paper the Nonsymmetric Kaluza–Klein Theory finding a condition for a color confinement in the theory. We consider also a Kerner–Wong–Kopczyński equation in this theory. The Nonsymmetric Kaluza–Klein Theory with a spontaneous symmetry breaking and Higgs' mechanism is examined. We find a mass spectrum for a broken gauge bosons and Higgs' particles. We derive a generalization of Kerner–Wong–Kopczyński equation in the presence of Higgs' field. A new term in the equation is a generalization of a Lorentz force term for a Higgs' field. We consider also a bosonic part of GSW (Glashow–Salam–Weinberg) model in our theory, getting masses for W, Z bosons and for a Higgs' boson agreed with an experiment. We consider Kerner–Wong–Kopczyński equation in GSW model obtaining some additional charges coupled to Higgs' field.     

Glueball mass calculations on an array of computers

We have calculated the mass of the 0⁺ glueball in SU(2) pure gauge theory in 4 dimensions, with very high statistics. The computation was done on an array of microprocessors with nearest-neighbor connections which run concurrently. We discuss, in detail, the implementation of the pure gauge algorithm for SU(2) and SU(3) and also the algorithm for calculating arbitrarily shaped Wilson loops on the array. The extension of these algorithms to the inclusion of dynamical fermions is also discussed. Finally, we present the results of our variational calculation of glueball masses which are in agreement with published results.