Production of Heavy neutrino in next-to-leading order QCD at the LHC and beyond

Majorana and pseudo-Dirac heavy neutrinos are introduced into the type-I and inverse seesaw models, respectively, in explaining the naturally small neutrino mass. TeV scale heavy neutrinos can also be accommodated to have a sizable mixing with the Standard Model light neutrinos, through which they can be produced and detected at the high energy colliders. In this paper we consider the Next-to-Leading Order QCD corrections to the heavy neutrino production, and study the scale variation in cross-sections as well as the kinematic distributions with different final states at $14$ TeV LHC and also in the context of $100$ TeV hadron collider. The repertoire of the Majorana neutrino is realized through the characteristic signature of the same-sign dilepton pair, whereas, due to a small lepton number violation, the pseudo-Dirac heavy neutrino can manifest the trileptons associated with missing energy in the final state. Using the $\sqrt{s}=8$ TeV, $20.3$ fb$^{-1}$ and $19.7$ fb$^{-1}$ data at the ATLAS and CMS respectively, we obtain prospective scale dependent upper bounds of the light-heavy neutrino mixing angles for the Majorana heavy neutrinos at the $14$ TeV LHC and $100$ TeV collider. Further exploiting a recent study on the anomalous multilepton search by CMS at $\sqrt{s}=8$ TeV with $19.5$ fb$^{-1}$ data, we also obtain the prospective scale dependent upper bounds on the mixing angles for the pseudo-Dirac neutrinos. We thus project a scale dependent prospective reach using the NLO processes at the $14$ TeV LHC.Comment: 28 pages. Matched journal versio

Broadening of ρ(→e+e−)\rho (\to e^+e^-) meson produced coherently in the photonuclear reaction

The $e^+e^-$ invariant mass distribution spectra are calculated to estimate the hadron parameters of the $\rho$ meson produced coherently in the photonuclear reaction. The elementary reaction occurring in the nucleus is considered to proceed as $\gamma N \to \rho^0 N ; ~ \rho^0 \to e^+e^-$. We describe the elementary $\rho$ meson photoproduction by the experimentally determined reaction amplitude $f_{ \gamma N \to \rho^0 N }$. The $\rho$ meson propagator is presented by the eikonal form, and the $\rho$ meson nucleus optical potential $V_{O\rho}$ appearing in it is estimated using the "$t\varrho$" approximation. The $\rho$ meson nucleon scattering amplitude $f_{ \rho N }$ extracted from the measurements is used to generate this potential. The calculated $e^+e^-$ invariant mass distribution spectra are compared with those measured at Jefferson Laboratory. The calculated results for the transparency ratio are also presented.Comment: 22 pages, 8 figure

Resonance dynamics in the coherent η\eta meson production in the (p,p′)(p,p^\prime) reaction on the spin-isospin saturated nucleus

For the forward going proton and $\eta$ meson, the coherent $\eta$ meson production in the $(p,p^\prime)$ reaction on the spin-isospin saturated nucleus occurs only due to the $\eta$ meson exchange interaction between the beam proton and nucleus. In this process, the nucleon in the nucleus can be excited to resonances $N^*$ and the $\eta$ meson in the final state can arise due to $N^* \to N\eta$. We investigate the dynamics of resonances, including nucleon Born terms, and their interferences in the coherently added cross section of this reaction. We discuss the importance of $N(1520)$ resonance and show the sensitivity of the cross section to the hadron nucleus interaction.Comment: 15 pages, 4 figure