Narrow Results

From several neutrino oscillation experiments, we understand now that neutrinos have mass. However, we really do not know what mechanism is responsible for producing this neutrino mass. Current or planned neutrino experiments utilize neutrino beams and long-baseline detectors to explore flavor mixing but do not address the question of the origin of neutrino mass. In order to begin answering that question, neutrino interactions need to be explored at much higher energies. This paper outlines a program to explore neutrinos and their interactions with various particles through a series of experiments involving colliding neutrino beams.

The interference between resonance signal and continuum background can be either constructive or destructive, depending on the relative sign of couplings between the signal and background amplitudes. Different interference schemes lead to asymmetric distortions of the resonance line shape, which could be distinguished in experiments, when the internal resonance width is larger than the detector resolution. Interpreting the ATLAS diboson excesses by means of a toy $W^{\prime }$ model as an illustrative example (though it is disfavored by the 13 TeV data), we find that the signs of resonance couplings can only be revealed in the line shape measurements up to a high confidence level at a high luminosity, which could bring us further information on the underlying theory beyond resonance searches at future lepton and hadron colliders.

Inspired by recent anomalies associated with the $b$ hadron decays, a theoretical investigation on $B_{d(s)}^{\ast }\to D_d^{+}(D_s^{+}){\tau }^{-}{\bar{v}}_{\tau }$ decays has been performed in $W^{\prime }$ model and scalar leptoquark model. To implicate these models, new coupling parameters are fixed by ${\chi }^2$ fitting using recent experimental results from $b\to c\tau {\bar{v}}_{\tau }$ transition as constraints. We have estimated branching fraction, lepton flavor universality (LFU) parameter, forward–backward asymmetry and lepton-spin asymmetry in the standard model (SM) as well as above two new physics (NP) models. Except lepton-spin asymmetry, significant deviations from the SM predictions are observed in $W^{\prime }$ model for both channels. In comparison to other observables, lepton-spin asymmetry shifts slightly from the SM in scalar leptoquark model. Our results may be helpful to the experimental communities to explore these decays and $W^{\prime }$ boson and leptoquark at the colliders.

This article reports on recent searches for single-top-quark production by the CDF and DØ collaborations at the Tevatron. Neither two CDF analyses, using data corresponding to 695 pb^-1 of integrated luminosity, nor a DØ search based on 370 pb^-1 of data can establish a signal for this standard model process. These null results translate in upper limits on the cross section of 2.9 pb for the t-channel production mode and 3.2 pb for the s-channel mode at the 95% C.L. In addition, the DØ collaboration has searched for non-standard model production of single-top-quarks via a heavy W' boson. No signal of this process is found resulting in lower mass limits of 610 GeV/c² for a left-handed W' and 630 GeV/c² for a right-handed W' boson.