Production Cross Section Distributions Research Articles

Interactions of unparticles with standard model particles

We study interactions of unparticles $\mathcal{U}$ of dimension ${d}_{\mathcal{U}}$ due to Georgi with standard model (SM) fields through effective operators. The unparticles describe the low energy physics of a nontrivial scale invariant sector. Since unparticles come from beyond the SM physics, it is plausible that they transform as a singlet under the SM gauge group. This helps tremendously in limiting possible interactions. We analyze interactions of scalar $\mathcal{U}$, vector ${\mathcal{U}}^{\ensuremath{\mu}}$, and spinor ${\mathcal{U}}^{s}$ unparticles with SM fields and derivatives up to dimension four. Using these operators, we discuss different features of producing unparticles at an ${e}^{+}{e}^{\ensuremath{-}}$ collider and other phenomenologies. It is possible to distinguish different unparticles produced at an ${e}^{+}{e}^{\ensuremath{-}}$ collider by looking at various distributions of production cross sections.

Target effect on fragmentation reaction at E = 290A MeV

The longitudinal and transverse momentum (PL and PYenT) distributions of projectile-like fragments, which were produced with an Ar beam and various targets (C, Al, Nb, Tb, Au), were measured at E=290A MeV. No significant target effects are found in P L distribution. The width of PT distribution increases with target mass. It is plausible that this result is explained by the deflection of orbit arising from Coulomb repulsion. The nuclear structural effects are observed in isotopic and isotonic distributions of production cross-sections of fragments, which are derived from observed momentum distributions.

Probing noncommuting extended technicolor effects bye+e−→tt¯at the Next Linear Collider

In the light case of the noncommuting extended technicolor model the heavy gauge bosons can have a mass less than or of the order of 1 TeV and hence they could be directly produced at foreseeable colliders. Even below their kinematic production threshold they are expected to produce significant deviations from the standard model (SM) predictions to various distributions of production cross sections and asymmetries that could be measured with high precision at the NLC. In this work we study the latter effects due to the heavy neutral ${Z}_{H}$ boson in the process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}t\overline{t}.$ We find that even for ${M}_{{Z}_{H}}=1500\mathrm{GeV}$ the deviations from the SM, particularly in ${\ensuremath{\sigma}}_{L}$ and ${A}_{\mathrm{LR}},$ are large enough to be measurable at NLC500.