Production and Polarization Effects in Some Tau-Lepton Decays

The conditions for the independence of decays of the spin-1/2 resonances on the production mechanism of the resonances and on polarizations of the incoming and outgoing particles are derived and applied in the case of several tau-lepton decays. The necessity for inclusion of the influence of the production mechanism in the evaluation of the lepton flavour violating decays is stressed.Comment: Invited Talk at the Seventh International Workshop on Tau Lepton Physics (TAU02), Santa Cruz, CA, USA, Sept. 2002, 6 pages LaTeX; One typo corrected, a note added, one reference adde

Opažanje gibanja brzih tijela iz jedne točke

We study the kinematical problem of observation of motion of objects that move at velocities comparable to the velocity of signals which are used to determine the velocity and distance of the objects. The main purpose of this work is to demonstrate the importance of time delay between the emission of signals and their reception at the observation point. The simplest cases are considered, i.e., rectilinear motion and assuming the observational point at the path of the moving object. Sound and light signals are considered to transmit the information on the motion. The results relating to the motion at constant velocity and for the acceleration due to a constant force are presented.Razmatramo kinematički problem opažanja gibanja tijela čije su brzine usporedive s brzinama signala koji se rabe za određivanje udaljenosti i brzine tih tijela. Osnovni je cilj ovog rada pokazivanje važnosti vremenskog kašnjenja od trenutka emisije do prijama signala u točki opažanja. Razmatraju se najjednostavniji slučajevi, tj. gibanje duž pravca i položaj opažača na putu promatranog tijela. Pretpostavlja se prijenos podataka o gibanju zvučnim i svjetlosnim signalima. Prikazuju se ishodi računa za gibanje stalnom brzinom i pod djelovanjem stalne sile

Opažanje gibanja brzih tijela iz jedne točke

We study the kinematical problem of observation of motion of objects that move at velocities comparable to the velocity of signals which are used to determine the velocity and distance of the objects. The main purpose of this work is to demonstrate the importance of time delay between the emission of signals and their reception at the observation point. The simplest cases are considered, i.e., rectilinear motion and assuming the observational point at the path of the moving object. Sound and light signals are considered to transmit the information on the motion. The results relating to the motion at constant velocity and for the acceleration due to a constant force are presented.Razmatramo kinematički problem opažanja gibanja tijela čije su brzine usporedive s brzinama signala koji se rabe za određivanje udaljenosti i brzine tih tijela. Osnovni je cilj ovog rada pokazivanje važnosti vremenskog kašnjenja od trenutka emisije do prijama signala u točki opažanja. Razmatraju se najjednostavniji slučajevi, tj. gibanje duž pravca i položaj opažača na putu promatranog tijela. Pretpostavlja se prijenos podataka o gibanju zvučnim i svjetlosnim signalima. Prikazuju se ishodi računa za gibanje stalnom brzinom i pod djelovanjem stalne sile

On Bethe strings in the two-particle sector of the closed SU(2)qSU(2)_{q} invariant spin chain

In this paper we investigate complex solutions of the Bethe equations in the two-particle sector both for arbitrary finite number of sites and for the thermodynamic limit . We find the number of complex solutions (strings) and compare it with the string conjecture prediction. Some simple properties of these solutions like position in the spectrum, crossing of levels, connection to the ground state and transformation to the real solutions are discussed. Counting both real and complex solutions we find expected number of highest weight Bethe states

Search for neutrinoless tau decays tau -> 3l and tau -> l K0S

Neutrinoless tau-lepton decays into either three leptons (tau- -> l1- l2 l3) or one lepton and one K0S meson(tau- -> l- K0S) where lepton l means either an electron or muon, have been searched for using 48.6 fb^{-1} of data collected with the Belle detector at the KEKB e+e- collider. No evidence for candidate decays are found in any channel. Therefore we set 90% confidence level upper limits on the branching fraction for 8 different decay modes. These limits are more stringent than those set previously and reach to the 10^{-7} level.Comment: Invited talk at the Seventh International Workshop on Tau Lepton Physics (TAU02), Santa Cruz, Ca, USA, Sept 2002, 7 pages, LaTeX, 3 eps figure

Resonant inelastic x-ray scattering probes the electron-phonon coupling in the spin-liquid kappa-(BEDT-TTF)2Cu2(CN)3

Resonant inelastic x-ray scattering at the N K edge reveals clearly resolved harmonics of the anion plane vibrations in the kappa-(BEDT-TTF)2Cu2(CN)3 spin-liquid insulator. Tuning the incoming light energy at the K edge of two distinct N sites permits to excite different sets of phonon modes. Cyanide CN stretching mode is selected at the edge of the ordered N sites which are more strongly connected to the BEDT-TTF molecules, while positionally disordered N sites show multi-mode excitation. Combining measurements with calculations on an anion plane cluster permits to estimate the sitedependent electron-phonon coupling of the modes related to nitrogen excitation

Polarization correlations in the two--photon decay of hydrogen--like ions

Polarization properties of the photons emitted in the two-photon decay of hydrogen-like ions are studied within the framework of the density matrix and second-order perturbation theory. In particular, we derive the polarization correlation function that gives the probability of the (two-photon) coincidence measurement performed by polarization-sensitive detectors. Detailed calculations of this function are performed for the $2s_{1/2} \to 1s_{1/2}$ transition in neutral hydrogen as well as Xe$^{53+}$ and U$^{91+}$ ions. The obtained results allow us to understand the influence of relativistic and non-dipole effects on the polarization correlations in the bound-bound two-photon transitions in heavy ions