相关论文: Off shell W pair production in e+ e- annihilation:…
We calculate the processes e+ e- -> 4 pions and tau -> nu_tau + 4 pions to O(p^4) in the low-energy expansion of the standard model. The chiral amplitudes of O(p^4) can be extended via resonance exchange to energies around 1 GeV.…
We present an analytical description of top-antitop pair production near the threshold in $e^+e^-$ annihilation and $\g\g$ collisions. A set of basic observables considered includes the total cross sections, forward-backward asymmetry and…
If one of the recently discovered charmed-strange mesons (D_sJ(2317)) is the 0+ state of cs-bar, the other (D_sJ(2460)) is most likely the 1+ state with j=1/2. They could be produced in e+e- annihilation by fragmentation from cc-bar jets or…
We discuss the production of two hadrons in e+e- annihilation within the framework of perturbative QCD. The cross section for this process is calculated to next-to-leading order accuracy with a selection of variables that allows the…
The fermion mass effects in e+ e- --> 4f and in the corresponding bremsstrahlung reactions in the presence of realistic cuts are studied. It is shown that, for some four--fermion final states, the mass effects become sizeable to the extent…
The total cross section of the process $e^+e^- \to \Lambda\bar{\Lambda}$ is calculated within the energy range close to the mass of $\psi(3770)$ charmonium state. Two different contributions were considered: the $D$-meson loop and the three…
A threshold singularity in a heavier meson channel, e.g. $D^* {\bar D}^*$, generally reflects in the amplitudes of $e^+e^-$ annihilation into lighter meson pairs, such as $D^* {\bar D}$, $D {\bar D}$, and $D_s {\bar D}_s$, due to the…
We argue that the recent BESIII data on the cross section for the process $e^+e^- \to \chi_{c0} \, \omega$ in the center of mass energy range 4.21 - 4.42 GeV can be described by the contribution of the known charmonium-like resonance…
In the recent past,unparticle physics effects have been explored in detail in both the fermionic and bosonic sectors. We have used fermionic unparticles to study the cross-section of electron-positron annihilation to light pseudo-scalar…
Forward-backward (charge) asymmetry in the processes of $e^+e^-$ annihilation into a pair of charged pseudoscalar mesons is recalculated in the one-loop approximation. The exact dependence on the meson masses is taken into account. Results…
We study the effects of non-commutative QED (NCQED) in fermion pair production, $\gamma + \gamma \to f + \bar{f}$ and Compton scattering, $e + \gamma \to e + \gamma$. Non-commutative geometries appear naturally in the context of…
In a recent publication we have calculated elastic charmonium production in ep collisions employing realistic charmonia wave functions and dipole cross sections and have found good agreement with the data in a wide range of s and Q^2. Using…
We calculate the D-wave charmonium production in $e^+e^-$ annihilation at BELLE and BABAR at $\sqrt{s}=10.6$ GeV using the nonrelativistic QCD factorization formalism, including color singlet and color octet contributions. We analyze the…
The status of predictions for four-fermion production at e-e+ colliders is reviewed with an emphasis on the developments after the LEP2 era and an outlook to the challenges posed by the precision program at future colliders.
We present an analysis of the process $e^+e^-\to V^*\to\pi\pi\gamma$, where $V=\gamma$ or $V=Z$ boson, in the kinematical region where $\sqrt{s}$, the c.m. energy of the $e^+e^-$ pair, is large but much below the $Z$-pole. The subprocess…
The production of W-pairs is analysed in a data sample collected by ALEPH at a mean centre-of-mass energy of 188.6 GeV, corresponding to an integrated luminosity of 174.2 pb^-1. Cross sections are given for different topologies of W decays…
The cross section of $e^+e^- \to b \bar{b} u \bar{d} \mu^- \bar{\nu}_\mu$ process with a complete set of tree diagrams, 232 diagrams in the unitary gauge, was calculated at the energy range of $\sqrt{s}$ = 340 - 500 GeV by using GRACE…
Production of electroweak bosons in e+e- annihilation into quarks and into leptons at energies much greater than 100 Gev is considered. We account for double-logarithmic contributions to all orders in electroweak couplings. It is assumed…
The bound-free channel of electron-positron pair production by a highly charged bare ion in the presence of a strong constant crossed electromagnetic field is studied. To calculate the pair production rate, two different methods are applied…
We calculate total and differential cross sections for the production of sfermion pairs in photon-photon collisions, including contributions from resolved photons and arbitrary photon polarization. Sfermion production in photon collisions…