Gluon Model Research Articles

About Nature of Nuclear Forthes

After the discovery of the proton-neutron composition of nuclei, the problem of nuclear forces nature became especially urgent.Nowadays, nuclear forces are explained by the action of a special strong interaction that occurs when nuclear nucleons exchange special particles - gluons.This article proves that the attraction between protons and neutrons can be explained by the well-known quantum mechanical effect, which was first described about a hundred years ago. This is the attraction between two protons that occurs when they are exchanged by electron (in this case relativistic). This makes it possible, abandoning the gluon model, to obtain quantitative estimates of the magnitude of the mass defect of both lightand heavy nuclei.

About Nature of Nuclear Forthes

After the discovery of the proton-neutron composition of nuclei, the problem of nuclear forces nature became especially urgent. Nowadays, nuclear forces are explained by the action of a special strong interaction that occurs when nuclear nucleons exchange special particles - gluons. This article proves that the attraction between protons and neutrons can be explained by the well-known quantum mechanical effect, which was first described about a hundred years ago. This is the attraction between two protons that occurs when they are exchanged by electron (in this case relativistic). This makes it possible, abandoning the gluon model, to obtain quantitative estimates of the magnitude of the mass defect of both light and heavy nuclei.

Mass dependence of pseudocritical temperature in mean field approximation

We restrict our computation in the mean field approximation which could lead to a clear critical behavior. We analyze the scaling behavior with different shape of interaction kernel by considering different dressed-gluon models. The critical exponent we obtained is consistent with that in the $3D$ $\textrm{O}(4)$ universality class. The size of critical region is up to $m_{0}^{} \le 2\sim 4\;$MeV in this mean field approximation which sets naturally an upper bound of the critical region since the fluctuations beyond mean-field usually diminish the critical region. Besides, we analyze the possible percentage of the maximum chiral susceptibility and pion mass range at which the chiral phase transition temperature is independent of the current quark mass. The results show that the percentage and the pion mass range depend on the details of interaction kernel, which differs in gluon models.

QCD phase transition and equation of state of stellar strong interaction matter via Dyson\u2013Schwinger equation approach

We study the phase structure and phase transition of cold dense QCD matter via the Dyson–Schwinger equation approach. We take the rainbow approximation and the Gaussian-type gluon model. In order to guarantee that the quark number density begins to appear at the nuclear liquid-gas phase transition chemical potential, we propose a chemical potential dependent modification factor for the gluon model. We find that for the iso-symmetric quark matter, the modification reduces the chemical potential of the phase coexistence region of the first-order phase transition. We also implement the relativistic mean field theory to describe the hadron matter, and make use of the Maxwell and Gibbs construction method to study the phase transition of beta -equilibrium and charge neutral matter in compact stars. The results show that the phase transition will not happen in case of the Gaussian-type gluon model without any modification. The results also indicate that the upper boundary of the coexistence region should be larger than the current Nambu solution existing region. We also calculate the mass-radius relation of the compact stars, and find that the hadron-quark phase transition happens at too high chemical potential so that the maximum mass of the compact star is hardly affected by the hadron-quark phase transition.

Strangeonium-like hybrids on the lattice * *Supported by the National Key Research and Development Program of China (2017YFB0203202) and the Strategic Priority Research Program of Chinese Academy of Sciences (No.XDC01040100, XDB34030302). The numerical calculations are carried out on Tianhe-1A at the National Supercomputer Center (NSCC) in Tianjin and the GPU cluster at IHEP. We also acknowledge the support of the

The strangeonium-like hybrids are investigated from lattice QCD in the quenched approximation. In the Coulomb gauge, spatially extended operators are constructed for and states with the color octet component being separated from the chromomagnetic field strength by the spatial distance , whose matrix elements between the vacuum and the corresponding states are interpreted as Bethe-Salpeter (BS) wave functions. In each of the channels, the masses and the BS wave functions are reliably derived. The ground state mass is approximately 2.1-2.2 GeV, and that of is approximately 2.3-2.4 GeV, whereas the mass of the first excited state is approximately 1.4 GeV higher. This mass splitting is much larger compared to that expected based on the phenomenological flux-tube model or constituent gluon model for hybrids, which is usually a few hundred MeV. The BS wave functions with respect to exhibit clear radial nodal structures of a non-relativistic two-body system, which imply that is a meaningful dynamical variable for these hybrids and motivate a color halo picture of hybrids, in which the color octet is surrounded by gluonic degrees of freedom. In the channel, the properties of the lowest two states are consistent with those of and . We did not obtain convincing information with respect to . However, we argue that regardless of whether is a conventional meson or a hybrid in the color halo scenario, the ratio of partial decay widths and observed by BESIII can be understood based on the mechanism of hadronic transition of a strangeonium-like meson in addition to mixing.

Thermodynamics of the Quark Gluon Plasma in the Early Universe

The recent progress in collider experiments provides us with valuable information to understand the properties of the quark-gluon plasma. In this study, we provide the analytical solution to the deferential equation of the time evolution of the temperature in the early Universe in the MIT bag model for gluons only. We discuss the equation of state of a QGP in a particular model, the possible signs for a plasma created in heavy-ion collisions and provide analytic solutions describing the time evolution of the energy density, temperature and pressure of this plasma in the early universe.

Heavy hybrid decays in a constituent gluon model

A constituent gluon model that is informed by recent lattice field theory is developed. The model is then used to compute hybrid strong decay widths, that can be useful for the GlueX collaboration at Jefferson Lab and the PANDA collaboration at FAIR. Commensurately, forthcoming data from GlueX and PANDA will test the model. Widths tend to be large except for those of the lightest hybrid $S$-wave multiplet. Selection rules, extensions, limitations, and applications are discussed.

Chiral transition and the chiral charge density of the hot and dense QCD matter.

We study the chirally imbalanced hot and dense strongly interacting matter by means of the Dyson-Schwinger equations (DSEs). The chiral phase diagram is studied in the presence of chiral chemical potential μ5. The chiral quark condensate leftlangle overline{psi}psi rightrangle is obtained with the Cornwall-Jackiw-Tomboulis (CJT) effective action in concert with the Rainbow truncation. Catalysis effect of dynamical chiral symmetry breaking (DCSB) by μ5 is observed. We examine with two popular gluon models and consistency is found within the DSE approach, as well as in comparison with lattice QCD. The critical end point (CEP) location (μE, TE ) shifts toward larger TE but constant μE as μ5 increases. A technique is then introduced to compute the chiral charge density n5 from the fully dressed quark propagator. We find the n5 generally increases with temperature T , quark number chemical potential μ and μ5. Since the chiral magnetic effect (CME) is typically investigated with peripheral collisions, we also investigate the finite size effect on n5 and find an increase in n5 with smaller system size.

Masses and decays of the bottom-charm hybrid meson cb¯g

We study gluonic excitations inside a $B_{c} $ meson in the constituent gluon model, treating a bottom-charm hybrid meson $ c \bar{b} g $ as a three-body system. We obtain the mass spectra for the hybrid mesons with magnetic gluon and electric gluon and see that their lowest states appear above the $ D B $ threshold. Also, we consider the decays of the low-lying states of the hybrid meson into $ DB , \; D^{*} B, DB^{*} $, $ D^{*}B^{*} $, $ D_{s} B_{s} $, and $D_{s} B_{s}^{*} $ mesons, developing an existing model for the strong decays. We estimate their partial decay widths and find that the widths have a heavy dependence on the final meson states. We argue that the accuracy of our model will be tested experimentally when the branching ratios of the decays are measured. Our results suggest that there could be a prospect that the hybrid meson will be discovered as its first excited state rather than its lowest state.

One possible application of the Chronometric Theory of I.E. Segal: a toy model of quarks and gluons

A fundamental role of linear-fractional transformations in different spaces of matrices is well-known. The current research mainly deals with one such space: D. As a space-time, D can be viewed as a Lie group with causal structure determined by an invariant Lorentzian form on the Lie algebra u(2). Recently, the author suggested a matrix multi-level model of quarks and gluons. As a basis for this model, the Segal’s compact cosmos D has been employed as well as the sequence of canonical (that is, corresponding to principal minors of appropriate matrices) group embeddings: U(2) into U(3), U(2) into U(4), etc. These groups were called the levels (of matter): U(2) – the 0th (that is, our mundane), U(3) – the 1st, U(4) – the 2nd, etc. Such a convention matches the standard quarks’ generations’ list. Seemingly, the multi-level model is the only known construct where such notions as flavour and colour are defined mathematically. According to the model, a quark can be interpreted as a ‘sank’ proton (during the beginning of the reaction process, proton ‘is pushed’ into a ‘deeper’ level). At each level, a gluon can be interpreted as a colored and flavored photon. Not each and every feature of the model coincides with the corresponding standard assumption about quarks and gluons. In particular, the total number of colors is level-dependent. The model predicts THREE new quarks of the 4th generation (whereas currently there is a search for TWO).

A new algorithm towards a quasi-Wigner solution of the gap equation beyond the chiral limit

We propose a new algorithm to solve the quasi-Wigner solution of the gap equation beyond the chiral limit. Employing a Gaussian gluon model and rainbow truncation, we find that the quasi-Wigner solution exists in a limited region of quark mass, m < 43.1 MeV, at zero temperature T and zero chemical potential μ. The difference between Cornwall–Jackiw–Tomboulis (CJT) effective actions of quasi-Wigner and Nambu–Goldstone solutions shows that the Nambu–Goldstone solution is more stable. Moreover, the quasi-Wigner solution is studied at finite temperature and chemical potential, the infrared mass function of the quasi-Wigner solution is negative and decreases along with T at μ = 0. Its susceptibility is divergent at certain temperatures with small m, and this temperature decreases along with m. Taking T = 80 MeV as an example, the quasi-Wigner solution is shown at finite chemical potential up to μ = 350 MeV as well as Nambu solution, the coexistence of these two solutions is used to analyze the properties of phase transition. The first order chiral phase transition line is determined by the difference of CJT effective actions.

Dynamical model of antishadowing of the nuclear gluon distribution

We explore the theoretical observation that within the leading twist approximation, the nuclear effects of shadowing and antishadowing in non-perturbative nuclear parton distribution functions (nPDFs) at the input QCD evolution scale involve diffraction on nucleons of a nuclear target and originate from merging of two parton ladders belonging to two different nucleons, which are close in the rapidity space. It allows us to propose that for a given momentum fraction $x_P$ carried by the diffractive exchange, nuclear shadowing and antishadowing should compensate each other in the momentum sum rule for nPDFs locally on the interval $\ln (x/x_P) \le 1$. We realize this by constructing an explicit model of nuclear gluon antishadowing, which has a wide support in $x$, $10^{-4} < x < 0.2$, peaks at $x=0.05-0.1$ at the level of $\approx 15$\% for $^{208}$Pb at $Q_0^2=4$ GeV$^2$ and rather insignificantly depends on details of the model. We also studied the impact parameter $b$ dependence of antishadowing and found it to be slow.

Twelve-quark hypernuclei with A = 4 in a relativistic quark–gluon model

Hypernuclei [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], where [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], with the atomic (baryon) number [Formula: see text], are described by the relativistic twelve-quark equations in the framework of the dispersion relation technique. Hypernuclei as the systems of interacting quarks and gluons are considered. The relativistic twelve-quark amplitudes of hypernuclei, including the constituent quarks of three flavors [Formula: see text], [Formula: see text], [Formula: see text] are calculated. The approximate solutions of these equations are obtained using a method based on extraction of leading singularities of the amplitudes. The poles of the multiquark amplitudes allow us to determine the masses and the binding energy of hypernuclei with [Formula: see text]. The mass and the binding energy of state [Formula: see text] with the isospin projection [Formula: see text] and the spin-parity [Formula: see text] is equal to [Formula: see text] and [Formula: see text], respectively. We predict the mass spectrum of hypernuclei with [Formula: see text], which is valuable for further experimental study of the hypernuclei.

Polyakov loop fluctuations and deconfinement in the limit of heavy quarks

We explore the influence of heavy quarks on color deconfinement within an effective model of gluons interacting with dynamical quarks. As the quark mass decreases, the strength of the explicit breaking of the Z(3) symmetry grows, and the first-order transition in the pure SU(3) gauge theory ends in a critical end point. The nature of this critical end point is examined by studying the fluctuations of the Polyakov loop, quantified by the corresponding susceptibilities. The properties of the Polyakov loop fluctuations and their ratios are also studied in QCD with physical quark masses.

Glueball physics in QCD

The Abelian decomposition of QCD which decomposes the gluons to the color neutral binding gluons and the colored valence gluons shows that QCD can be viewed as the restricted QCD (RCD) made of the binding gluons which has the valence gluons as colored source, and simplifies the QCD dynamics greatly. In particular, it tells that the gauge covariant valence gluons can be treated as the constituents of hadrons, and generalizes the quark model to the quark and valence gluon model. So it provides a comprehensive picture of glueballs and their mixing with quarkoniums, and predicts new hybrid hadrons made of quarks and valence gluons. We discuss how these predictions could be confirmed experimentally. In particular we present a systematic search for the ground state glueballs and their mixing with quarkoniums below 2 GeV in ${0}^{++}$, ${2}^{++}$, and ${0}^{\ensuremath{-}+}$ channels within the framework of QCD, and predict the relative branching ratios of the radiative decay of $\ensuremath{\psi}$ to the physical states.

Inhomogeneous Polyakov loop induced by inhomogeneous chiral condensates

We study the spatial inhomogeneity of the Polyakov loop induced by inhomogeneous chiral condensates. We formulate an effective model of gluons on the background fields of chiral condensates, and perform its lattice simulation. On the background of inhomogeneous chiral condensates, the Polyakov loop exhibits an in-phase spatial oscillation with the chiral condensates. We also analyze the heavy quark potential and show that the inhomogeneous Polyakov loop indicates the inhomogeneous confinement of heavy quarks.

Polyakov loop fluctuations and deconfinement in the limit of heavy quarks

We explore the influence of heavy quarks on the deconfinement phase transition in an effective model for gluons interacting with dynamical quarks in color SU(3). With decreasing quark mass, the strength of the explicit breaking of the Z(3) symmetry grows, and the first-order transition ends in a critical end point. The nature of the critical end point is examined by studying the longitudinal and transverse fluctuations of the Polyakov loop, quantified by the corresponding susceptibilities. The longitudinal susceptibility is enhanced in the critical region, while the transverse susceptibility shows a monotonic behavior across the transition point. We investigate the dependence of the critical end point on the number of quark flavors at vanishing and finite quark density and relate these results to lattice findings.

An operator-theoretical treatment of the Maskawa–Nakajima equation in the massless abelian gluon model

The Maskawa–Nakajima equation has attracted considerable interest in elementary particle physics. From the viewpoint of operator theory, we study the Maskawa–Nakajima equation in the massless abelian gluon model. We first show that there is a nonzero solution to the Maskawa–Nakajima equation when the parameter λ satisfies λ>2. Moreover, we show that the solution is infinitely differentiable and strictly decreasing. We thus conclude that the massless abelian gluon model generates the nonzero quark mass spontaneously and exhibits the spontaneous chiral symmetry breaking when λ>2. We next show that there is a unique solution 0 to the Maskawa–Nakajima equation when 0<λ<1, from which we conclude that each quark remains massless and that the model realizes the chiral symmetry when 0<λ<1.

Low-Lying Baryons in Hybrid Quark Model

We study the strong decay processes of the Roper resonance, N*(1440) in the picture of hybrid baryon in which the Roper resonance N*(1440) is interpreted as a state of three quarks and one transverse-electric gluon, q3G. A nonrelativistic quark–gluon model is employed, where the dynamics of antiquark–quark–gluon is described in the effective \({^{3}S_{1}}\) vertex in which a quark–antiquark pair is created (destroyed) from (into) a gluon. The wave function of the Roper resonance is properly constructed to take into account the gluon freedom in the nonrelativistic regime. The evaluated strong decay width ratios of N*(1440) are in good agreement with the experimental data.

Searches for Fourth Generation, Vector-like Quarks and Resonances with the ATLAS Detector

A summary of the searches for heavy quarks and heavy bosons decaying to top-antitop pairs ( resonances) with 14.3 fb−1 of the proton-proton collisions data at √s = 8 TeV delivered by the LHC and recorded by the ATLAS detector is presented here. The searches for heavy quarks are performed in context of the chiral fourth generation and vector-like quarks. One of the searches is also sensitive to the production of four top quarks and positively-charged top quark pairs. The search for resonances is motivated by the narrow width topcolor leptophobic Z’ and broad width Kaluza-Klein gluon models.