PRODUCTION OF VECTOR UNPARTICLE PAIRS IN $e^+ e^-$ COLLISIONS

Abstract

We calculate and investigate the production of vector unparticle pairs in $e^+ e^-$ collisions for both unpolarized and polarized initial $e^+ , e^-$  beams, and evaluate the dependence of the cross section on the cosine of the scattering angle $cosθ$, the energy $E_U$ of the produced vector unparticle, the center-of-mass energy $\sqrt{s}$ , the beam polarization coefficients, and the invariant parameters $d_U$ and the energy scale $Λ_U$  of the unparticle physics model. Here, the vector unparticle is treated as an effective massless final-state vector. The results indicate that the differential and total cross sections strongly depend on the considered parameters. The differential cross section reaches its maximum in the forward or backward directions, corresponding to the same or opposite direction relative to the initial electron beams. The total cross section is larger in the low collision-energy region and decreases as the energy of the produced vector unparticle beam increases. The total cross section
attains its maximum value when both the $e^+ , e^-$ beams are 100% right-polarized. The cross section becomes significantly larger for smaller values of $d_U$, while showing less sensitivity to variations in $Λ_U$ within the investigated parameter range. These results provide theory-level estimates that may be useful for exploring constraints on the parameter space of the unparticle physics model within the adopted effective massless-vector approximation.