On the polarization properties of the charmed baryon Lambda^+_c in the Lambda^+_c -> p + K^- + pi^+ + pi^0 decay

The polarization properties of the charmed Lambda^+_c baryon are investigated in weak non-leptonic four-body Lambda^+_c -> p + K^- + pi^+ + pi^0 decay. The probability of this decay and the angular distribution of the probability are calculated in the effective quark model with chiral U(3)XU(3) symmetry incorporating Heavy Quark Effective theory (HQET) and the extended Nambu-Jona-Lasinio model with a linear realization of chiral U(3)XU(3) symmetry. The theoretical value of the probability of the decay Lambda^+_c -> p + K^- + pi^+ + pi^0 relative to the probability of the decay Lambda^+_c -> p + K^- + pi^+ does not contain free parameters and fits well experimental data. The application of the obtained results to the analysis of the polarization of the Lambda^+_c produced in the processes of photo and hadroproduction is discussed.Comment: 10 pages, no figures, Late

Antiferromagnetism and phase separation in the t-J model at low doping: a variational study

Using Gutzwiller-projected wave functions, I estimate the ground-state energy of the t-J model for several variational states relevant for high-temperature cuprate superconductors. The results indicate antiferromagnetism and phase separation at low doping both in the superconducting state and in the staggered-flux normal state proposed for the vortex cores. While phase separation in the underdoped superconducting state may be relevant for the stripe formation mechanism, the results for the normal state suggest that similar charge inhomogeneities may also appear in vortex cores up to relatively high doping values.Comment: 4 pages, 3 figures, reference adde

Relativistic Heavy-Ion Collisions within 3-Fluid Hydrodynamics: Hadronic Scenario

A 3-fluid hydrodynamic model for simulating relativistic heavy-ion collisions is introduced. Alongside with two baryon-rich fluids, the new model considers time-delayed evolution of a third, baryon-free (i.e. with zero net baryonic charge) fluid of newly produced particles. Its evolution is delayed due to a formation time, during which the baryon-free fluid neither thermalizes nor interacts with the baryon-rich fluids. After the formation it starts to interact with the baryon-rich fluids and quickly gets thermalized. Within this model with pure hadronic equation of state, a systematic analysis of various observables at incident energies between few and about 160A GeV has been done as well as comparison with results of transport models. We have succeeded to reasonably reproduce a great body of experimental data in the incident energy range of E_{lab} = (1-160)A GeV. The list includes proton and pion rapidity distributions, proton transverse-mass spectra, rapidity distributions of Lambda and antiLambda hyperons, elliptic flow of protons and pions (with the exception of proton v2 at 40A GeV), multiplicities of pions, positive kaons, phi-mesons, hyperons and antihyperons, including multi-strange particles. This agreement is achieved on the expense of substantial enhancement of the interflow friction as compared to that estimated proceeding from hadronic free cross sections. However, we have also found out certain problems. The calculated yield of K^- is approximately by a factor of 1.5 higher than that in the experiment. We have also failed to describe directed transverse flow of protons and pion at E_{lab} > 40A GeV. This failure apparently indicates that the used EoS is too hard and thereby leaves room for a phase transition.Comment: 30 pages, 20 figures, 2 tables. Version accepted for publication in Phys. Rev.

Numerical study of fractionalization in an Easy-axis Kagome antiferromagnet

Based on exact numerical calculations, we show that the generalized Kagome spin model in the easy axis limit exhibits a spin liquid, topologically degenerate ground state over a broad range of phase space. We present an (to our knowledge the first) explicit calculation of the gap (and dispersion) of ``vison'' excitations, and exponentially decaying spin and vison 2-point correlators, hallmarks of deconfined, fractionalized and gapped spinons. The region of the spin liquid phase includes a point at which the model is equivalent to a Heisenberg model with purely two-spin interactions. Beyond this range, a negative ``potential'' term tunes a first order transition to a magnetic ordered state. The nature of the phase transition is also discussed in light of the low energy spectrum. These results greatly expand the results and range of a previous study of this model in the vicinity of an exactly soluble point.Comment: 4 pages, 5 figure