A Search For Sequential Neutrinos With Hrs At Pep.

A search was made in e\sp+e\sp- annihilations at $\sqrt s$ = 29 GeV with the High Resolution Spectrometer at PEP, for events with an isolated pair of charged tracks e\sp{\pm}X\sp{\mp} where X is a muon or meson. Such pairs are a possible signature for the decay of massive neutrinos. The model investigated produces these neutrinos through the virtual neutral weak vector current Z\sp\circ and allows them to decay via the virtual charged weak vector boson W\sp{\pm}. The neutrinos were assumed to mix with one of the known neutrinos (electron, muon, or tau), and each case was considered separately. For a given mass and mixing parameter $\vert$U\vert\sp2 the production cross section and decay branching ratios are completely determined by the Standard Model. Only one event was found, for an integrated luminosity of 300 pb\sp{-1}, satisfying certain selection criteria and with a mass M\sb{\rm eX} $>$ 1.8 GeV/c\sp2. Detection efficiencies for events containing at least one e\sp{\pm}X\sp{\mp} pair were calculated using Monte Carlo techniques. Limits were first set on the production cross section versus the mass of the neutrino in the limit where the mixing parameter $\vert$U\vert\sp2 = 1. Limits were then set on $\vert$U\vert\sp2 versus mass of the neutrino for the three cases of mixing. This result places strong constraints on the existence of new neutrinos with masses from 1.8 to 6.7 GeV/c\sp2 and with mixing parameters to the known neutrinos in the range 3 $\times$ 10\sp{-6} $<$ $\vert$U\vert\sp2 $<$ 1.Ph.D.High energy physicsPure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/128090/2/8801314.pd

Recent progress in neutrino factory and muon collider research within the Muon collaboration

We describe the status of our effort to realize a first neutrino factory and the progress made in understanding the problems associated with the collection and cooling of muons towards that end. We summarize the physics that can be done with neutrino factories as well as with intense cold beams of muons. The physics potential of muon colliders is reviewed, both as Higgs Factories and compact high energy lepton colliders. The status and timescale of our research and development effort is reviewed as well as the latest designs in cooling channels including the promise of ring coolers in achieving longitudinal and transverse cooling simultaneously. We detail the efforts being made to mount an international cooling experiment to demonstrate the ionization cooling of muons

Search for Scalar Diphoton Resonances in the Mass Range 65−60065-600 GeV with the ATLAS Detector in pppp Collision Data at s\sqrt{s} = 8 TeVTeV

A search for scalar particles decaying via narrow resonances into two photons in the mass range 65–600 GeV is performed using $20.3\text{}\text{}{\mathrm{fb}}^{-1}$ of $\sqrt{s}=8\text{}\text{}\mathrm{TeV}$ $pp$ collision data collected with the ATLAS detector at the Large Hadron Collider. The recently discovered Higgs boson is treated as a background. No significant evidence for an additional signal is observed. The results are presented as limits at the 95% confidence level on the production cross section of a scalar boson times branching ratio into two photons, in a fiducial volume where the reconstruction efficiency is approximately independent of the event topology. The upper limits set extend over a considerably wider mass range than previous searches

Measurement of the W±ZW^{\pm}Z boson pair-production cross section in pppp collisions at s=13\sqrt{s}=13 TeV with the ATLAS Detector

The production of $W^{\pm}Z$ events in proton--proton collisions at a centre-of-mass energy of 13 TeV is measured with the ATLAS detector at the LHC. The collected data correspond to an integrated luminosity of 3.2 fb$^{-1}$. The $W^{\pm}Z$ candidates are reconstructed using leptonic decays of the gauge bosons into electrons or muons. The measured inclusive cross section in the detector fiducial region for leptonic decay modes is $\sigma_{W^\pm Z \rightarrow \ell^{'} \nu \ell \ell}^{\textrm{fid.}} = 63.2 \pm 3.2$ (stat.) $\pm 2.6$ (sys.) $\pm 1.5$ (lumi.) fb. In comparison, the next-to-leading-order Standard Model prediction is $53.4^{+3.6}_{-2.8}$ fb. The extrapolation of the measurement from the fiducial to the total phase space yields $\sigma_{W^{\pm}Z}^{\textrm{tot.}} = 50.6 \pm 2.6$ (stat.) $\pm 2.0$ (sys.) $\pm 0.9$ (th.) $\pm 1.2$ (lumi.) pb, in agreement with a recent next-to-next-to-leading-order calculation of $48.2^{+1.1}_{-1.0}$ pb. The cross section as a function of jet multiplicity is also measured, together with the charge-dependent $W^+Z$ and $W^-Z$ cross sections and their ratio