Leptonic dipole moments in the left-right supersymmetric model

The observation of neutrino oscillations imposes a pattern of mixing in both the sneutrino and charged slepton sectors. On the other hand, the apparent 2.6 deviation of the anomalous magnetic moment of the muon from the standard model value favors a scenario beyond the standard model. We show that, in a supersymmetric model with left-right symmetry, which provides an explanation for both phenomena, the relationship between flavor conserving dipole moments, such as the magnetic and the electric dipole moments, and flavor violating dipole moments, such as and , is quite different from that in the MSSM. From general analytic considerations, we derive bounds on the fractional sneutrino mass splittings , and the fractional charged slepton splittings . For , the mixing is allowed to be maximal. We also comment on the magnitudes and correlations between CP-violating angles coming from electric dipole moments. We supplement the analytical considerations by detailed numerical calculations. Received: 6 September 2001 / Revised version: 30 October 2001 / Published online: 7 December 2001     

Baryon exotics in the quark model, the skyrme model, and QCD

We derive the quantum numbers of baryon exotics in the quark model and the Skyrme model and show that they agree for arbitrary colors and flavors. We define exoticness E, which can be used to classify the states. The exotic baryons include the recently discovered qqqqq pentaquarks (E=1), as well as exotic baryons with additional qq pairs (E>/=1). The mass formula for nonexotic and exotic baryons is given as an expansion in 1/N(c) and allows one to relate the moment of inertia of the Skyrme soliton to the mass of a constituent quark.     

A supersymmetric gluon model

It is pointed out that parity doubling does not provide a satisfactory resolution of the conflict between parity and fermion-number conservation in supersymmetric gauge theories. A new generalized gauge principle is proposed which overcomes this difficulty for both Abelian and non-Abelian local symmetries.     

Triality,exotics and the dynamical basis of the quark model

A non-relativistic three-triplet model with a simple two-body interaction is shown to bind only q$\text{q}$ and qqq states. Three triplets and unobserved charmed states are crucial in preventing binding of 4q$\text{q}$ and 2 q$\text{q}$ systems. They provide repulsive channels to make the q$\text{q}$ and 3q systems behave like “neutral atoms” with canceling attractive and repulsive forces between them and additional quarks. The ratio of q$\text{q}$ and qq interactions is just right to bind the q$\text{q}$ and 3q systems properly while leaving the qq system with the mass of a quark.     

Effective-potential model for the self-interacting gluon gas

The thermodynamic behaviour of a pure gluon-plasma is investigated within the context of an effective-interaction model and the relativistic Landau theory of quantum liquids. Agreement is sought withSU (2) andSU (3) lattice computer simulations and asymptotic perturbation theory. For bothSU (2) andSU (3) the available data are fitted rather well by a logarithmically screened Coulomb potential. The difference in critical behaviour ofSU (2) andSU (3) can also be modelled. Contact is made with the Bare Bones bag model, yielding a bag pressure ofB ^1/4≈200 MeV.     

Inclusive jet production within the two gluon exchange model

The work presents the predictions for the inclusive jet production in the two gluon exchange model for the LEP energies. It is shown that there is a region of the produced jet transverse momentap _T where the two gluon contribution is the only important one. The two gluon exchange model is not able to reproduce the exponential slope of the jet inclusive production cross section, which seems to be an essential feature of the hadronic component of a photon.     

Revisiting the quasi-particle model of the quark–gluon plasma

The quasi-particle model of the quark–gluon plasma (QGP) is revisited here with a new method, different from earlier studies, one without the need of a temperature dependent bag constant and other effects such as confinement, effective degrees of freedom etc. Our model has only one system dependent parameter and shows a surprisingly good fit to the lattice results for the gluon plasma, and for 2-flavor, 3-flavor and (2+1)-flavor QGP. The basic idea is first to evaluate the energy density ε from the grand partition function of quasi-particle QGP, and then derive all other thermodynamic functions from ε. Quasi-particles are assumed to have a temperature dependent mass equal to the plasma frequency. Energy density, pressure and speed of sound at zero chemical potential are evaluated and compared with the available lattice data. We further extend the model to a finite chemical potential, without any new parameters, to obtain the quark density, quark susceptibility etc., and the model fits very well with the lattice results on 2-flavor QGP. PACS 12.38.Mh; 12.38.Gc; 05.70.Ce; 52.25.Kn     

Charmed exotics in heavy ion collisions

Based on the color–spin interaction in diquarks, we argue that charmed multiquark hadrons are likely to exist. Because of the appreciable number of charm quarks produced in central nucleus–nucleus collisions at ultrarelativistic energies, the production of charmed multiquark hadrons is expected to be enhanced in these collisions. Using both the quark coalescence model and the statistical hadronization model, we estimate the yield of charmed tetraquark mesons, T_cc, and pentaquark baryons, Θ_cs, in heavy ion collisions at RHIC and LHC. We further discuss the decay modes of these charmed exotic hadrons in order to facilitate their detections in experiments. PACS 25.75.Dw; 14.20.Lq; 14.40.Lb     

Leptonic CP violation in leptoquark models

We study the leptonic CP violation effects in leptoquark models. We show that in general the leptoquark contribution to the longitudinal muon polarization effect inη→μ ⁺ μ ^? decay is very small and in a model which has no couplings induced by the leptoquark between different generations, both the electric dipole moment of electron or muon and longitudinal polarization of electron in π⁰,η→e ⁺ e ^? decays can be large.     

A three-dimensional model for quark and gluon jets

Based on the assumption that a color force-field has a stringlike character (like a stretchedout bag_ with no excited degrees of freedom transverse to the field direction (which is strongly supported by the observed polarization of inclusively produced Λ-particles) we derive the probability to produce heavy flavor quark-antiquark pairs and pairs with transverse momentum in the field. We show how to incorporate the results into a soft hadronisation scheme for particle distributions in quark and gluon jets. We point to some non-trivial effects from the finite (longitudinal) size of the force-field which result on the one hand in important correlations between the longitudinal scaling variable and the transverse momentum and on the other hand leads to correstions to the simple iterative cascade scheme.