![]() Of lower energies, tau lepton decays constitute an excellent laboratory for Offers an important ingredient of new physics signatures. Of high-energy experiments such as at LHC, knowledge of tau lepton properties Parity sensitive couplings lead to broad physics interest. Measurements of tau lepton, because of its long lifetime, large mass and Also it is explained that the phase space parameterization used in the program is exact. In particular, it is mentioned that the second order matrix elements were used in design and validation of the program iteration procedure. Physics assumptions used in the program and properties of the solution it offers are reviewed. In the FORTRAN version of PHOTOS they were available only for decays of particles at rest and with spin set along the z axis. Weights, featuring complete first order matrix elements, can be installed for general use. An algorithm of the event record interface is prepared for the installation of process dependent variants of the photon emission kernel. Howeverbetter steering options are available. The PHOTOS C++ physics precision is now as good as that of its FORTRAN predecessor. A multitude of test results and examples are distributed together with the program code. The main purpose of the present paper is to document technical aspects of the PHOTOS Monte Carlo installation and its use. The first version of PHOTOS Monte Carlo for bremsstrahlung in the decay of particles and resonances with an interface to the HepMC event record written in C++ is now available. Global fits to moments of kinematic distributions measured in inclusive semileptonic $B\rightarrow X_c l \nu_l$ enable the determination of the Cabibbo-Kobayashi-Maskawa matrix element $|V_$ and differences of partial moments are discussed. Is quite universal: any color-neutral current can be used in particular, our approach is not restricted to vector currents To avoidĬomplications and ambiguities related to regularization schemes, we ignore, at this point, virtual corrections. Our aim is toīetter understand the environment necessary to optimally match hard matrix elements with parton-shower algorithms. Of evolution kernels for individual splittings and to some degree for the running coupling constant as well. Special emphasis will be put on the isolation of parts necessary for the construction We will search for forms compatible with parton-shower languages, without applying approximations WeĬoncentrate our attention on processes involving two quarks entering a color-neutral current and, thanks to the QCD interactions, In this note we discuss possible separations of exact, massive, tree-level spin amplitudes into gauge-invariant parts. Independent calculations of scalar QED is demonstrated. ![]() Simultaneously, fullĭifferential distributions over the complete multiple-body phase-space are provided. Leading and next to leading logarithmic terms are properly reproduced by the Monte Carlo simulation. The massive phase-space is controlled in the program with no approximations. Jacobians are separated in the final weight, and future extensions based on measurable electromagnetic form-factors are thus We present the analyticalįorm of the kernel used in the older versions of PHOTOS, and the new, exact (scalar QED) one. Use scalar QED to benchmark PHOTOS, even though this theory is of limited use for complex objects. If experimentalĪcceptance must be taken into account, the PHOTOS Monte Carlo technique is often used in experimental simulations. Recently, QED bremsstrahlung in B meson decays into pair of scalars (πs and/or Ks) has become of interest.
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