Abstract:
The contributions of $G'$-boson predicted by the chiral color symmetry of quarks to the charge asymmetry $A_C(p p \to t\bar{t})$ in $t \bar{t}$ production at the LHC and to the forward-backward asymmetry $A_{\rm FB}(p\bar{p} \to t\bar{t})$ in $t\bar{t}$ production at the Tevatron are calculated and analysed in dependence on two free parameters of the model, the $G'$ mass $m_{G'}$ and mixing angle $\theta_G$. The $m_{G'} - \theta_G$ regions of $1 \sigma$ consistency with the CMS data on the cross section $\sigma(pp \to t\bar{t})$ and on the charge asymmetry $A_C(p p \to t\bar{t})$ are found and compared with those resulted from the CDF data on the cross section $\sigma(p\bar{p} \to t\bar{t})$ and on the forward-backward asymmetry $A_{\rm FB}(p\bar{p} \to t\bar{t})$ of $t \bar{t}$ production at the Tevatron with account of the current SM predictions for $A_{\rm FB}(p\bar{p} \to t\bar{t})$.

Abstract:
Several models predict the existence of heavy colored resonances decaying to top quarks in the TeV energy range that might be discovered at the LHC. In some of those models, moreover, a sizable charge asymmetry of top versus antitop quarks might be generated. The detection of these exotic resonances, however, requires selecting data samples where the top and the antitop quarks are highly boosted, which is experimentally very challenging. We asses that the measurement of the top quark charge asymmetry at the LHC is very sensitive to the existence of excited states of the gluon with axial-vector couplings to quarks. We use a toy model with general flavour independent couplings, and show that a signal can be detected with relatively not too energetic top and antitop quarks. We also compare the results with the asymmetry predicted by QCD, and show that its highest statistical significance is achieved with data samples of top-antitop quark pairs of low invariant masses.

Abstract:
Several models predict the existence of heavy colored resonances decaying to top quarks in the TeV energy range that might be discovered at the LHC. In some of those models, moreover, a sizable charge asymmetry of top versus antitop quarks might be generated. The detection of these exotic resonances, however, requires selecting data samples where the top and the antitop quarks are highly boosted, which is experimentally very challenging. We asses that the measurement of the top quark charge asymmetry at the LHC is very sensitive to the existence of excited states of the gluon with axial-vector couplings to quarks. We use a toy model with general flavour independent couplings, and show that a signal can be detected with relatively not too energetic top and antitop quarks. We also compare the results with the asymmetry predicted by QCD, and show that its highest statistical significance is achieved with data samples of top-antitop quark pairs of low invariant masses.

Abstract:
With appropriate gauge transformations, field can replace electric charge in quarks. Classical quarks, in a necessary non-gauge invariant formulation, are used for illustration, bringing to the fore the limitations of the usual electric charge densities for single particles in Coulomb equations. The results are encouraging; the solutions for the Coulomb potentials apply individually to each quark in a shell structure. A remarkably simple relation emerges between the Coulomb and weak potentials.

Abstract:
A gauge-invariant color-charge operator is defined and related to an integral of the gauge-invariant chromoelectric field over a closed surface. We discuss the case of a surface all of whose points are a macroscopic distance from a system of quarks and gluons which it entirely surrounds. When this system of quarks and gluons forms a hadron or an object composed of hadrons, such as a nucleus, it is argued that the gauge-invariant color charge enclosed within this surface must vanish and the system of hadrons in the interior of the surface must be a color singlet.

Abstract:
In quantum chromodynamics with static quarks the confinement-deconfinement phase transition is connected to the spontaneous breaking of the global Z3 center symmetry. This symmetry is lost when one considers dynamical quarks. Owing to the fractional electric charge of quarks, we recover a global Z6 center symmetry when QCD is regarded as a part of the Standard Model. We present results from QCD-like theories extended by electromagnetic interactions and show that the weak coupling limit of the QED part of the model results in a center-like symmetry with disorder in the vacuum. This can be seen explicitly in a character expansion of the fermion determinant. Further, we show that corresponding center averages project the fermion determinant on N-ality zero and discuss whether the additional center symmetry can be used to eliminate the fermion sign problem in QCD with fundamental quarks.

Abstract:
An introductory review of physics of color superconducting state of matter is presented. Comparison with superconductivity in electron systems reveals difficulties involved in formulating color superconductivity theory at moderately ultra-nuclear density.

Abstract:
We consider a hydrodynamic approach in which a quantum system of interacting quarks and gluons is approximated classically by representing it as a perfect fluid having intrinsic degrees of freedom. Every particle of such fluid is endowed with spin and non-Abelian color charge. The variational theory of such perfect spin fluid with color charge is constructed, the spin-polarization chromomagnetic effects in an external Yang-Mills field and in Riemann-Cartan space with curvature and torsion being taken into account.

Abstract:
We analyze the topological structure of quenched QCD in the presence of static color sources. Distributions of the topological charge density around static quarks and mesons are computed in both phases of QCD. We observe a suppression of topological fluctuations in the vicinity of external sources. In the confinement phase, the suppression occurs in the whole flux tube between the static quark and antiquark.

Abstract:
An improved M.I.T. bag model with hyper central interaction is used to calculate the charge radius for proton containing u and d quarks. We present a theoretical approach to the internal structure of three-body hyper central interacting quarks in a proton, in which we take proton as a bag. We discuss a few of results obtained using a six-dimension potential, which is attractive for small separation, originating from the color charge of hyper color term. We calculate the relativistic wave function for quarks in a scalar-vector hyper central potential, analytically. Finally, vanishing the normal component of vector current at the surface of the proton bag as a boundary condition equivalent to confinement. The calculated charge radius for proton is better than in the uncorrected versions of the model.