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B. H. J. McKellar

Publications and source records attributed to B. H. J. McKellar.

48 records · Page 3Linked to original sources
arXiv1996

MSW-like Enhancements without Matter

We study the effects of a scalar field, coupled only to neutrinos, on oscillations among weak interaction current eigenstates. The effect of a real scalar field appears as effective masses for the neutrino mass eigenstates, the same for $\nbar$ as for $\n$. Under some conditions, this can lead to a vanishing of $δm^2$, giving rise to MSW-like effects. We discuss some examples and show that it is possible to resolve the apparent discrepancy in spectra required by r-process nucleosynthesis in the mantles of supernovae and by Solar neutrino solutions.

hep-ph↗
arXiv1996

MSW Without Matter

We examine the effects of a scalar field, coupled only to neutrinos, on oscillations among weak interaction current eigenstates. The existence of a real scalar field is manifested as effective masses for the neutrino mass eigenstates, the same for $\nbar$ as for $\n$. Under some conditions, this can lead to a vanishing of $δm^2$, giving rise to MSW-like effects. We present an idealized example and show that it may be possible to resolve the apparent discrepancy in spectra required by r-process nucleosynthesis in the mantles of supernovae and by Solar neutrino solutions.

hep-ph↗
arXiv1996

$ΔI=1$ axial-vector mixing and charge symmetry breaking

Phenomenological Lagrangians that exhibit (broken) chiral symmetry as well as isospin violation suggest short-range charge symmetry breaking (CSB) nucleon-nucleon potentials with a $\mbox{\boldmath $σ$}_1 \!\cdot\!\mbox{\boldmath $σ$}_2$ structure. This structure could be realized by the mixing of axial-vector ($1^+$) mesons in a single-meson exchange picture. The Coleman-Glashow scheme for $ΔI_{z}=1$ charge symmetry breaking applied to meson and baryon $SU(2)$ mass splittings suggests a universal scale. This scale can be extended to $ΔI=1$ nonstrange CSB transitions $\langle a_1^\circ|H_{em}|f_1\rangle$ of size $-0.005$ GeV$^2$. The resulting nucleon-nucleon axial-vector meson exchange CSB potential then predicts $ΔI=1$ effects which are small.

nucl-th↗
arXiv1996

Neutrino Clouds

We consider the possibility that neutrinos are coupled very weakly to an extremely light scalar boson. We first analyze the simple problem of one generation of neutrino and show that, for ranges of parameters that are allowed by existing data, such a system can have serious consequences for the evolution of stars and could impact precision laboratory measurements. We discuss the extension to more generations and show that the general conclusion remains viable. Finally, we note that, should such a scalar field be present, experiments give information about effective masses, not the masses that arise in unified field theories.

hep-ph↗
arXiv1995

A Nonperturbative Study of Quarkonium Systems

Using Nonrelativistic QCD on the lattice we studied the mass spectrum of quarkonium systems nonperturbatively for a range of the bar quark mass. We determined two products of the matrix elements involved in quarkonium decays and studied the mass dependence of the results. We predict from our calculations the leptonic decay width of $Υ$, and use the mass dependence to predict the leptonic decay width of $J/ψ$. These calculations agree with the experimental results. In lattice NRQCD an additional parameter $n$ is introduced, and we study the sensitivity of our results to the choice of $n$.

hep-ph↗
arXiv1994

CP Violating Effects in $e^+e^-\rightarrow ZH$ and Their Optimization

We consider the possibilities of testing CP conservation in the process $e^+e^- \rightarrow ZH$. The easiest is to measure the forward-backward asymmetry of the $Z$ boson, a nonzero value of which signals CP violation. The effects of CP violation are predicted in the two Higgs doublet model. We show here that a choise of optimal observables can improve the possibility of observing CP violation. Although the number of events is not large, useful information about CP violating parameters can be extracted.

hep-ph↗
arXiv1994

$ε'/ε$ And Anomalous Gauge Boson Couplings

We study $ε'/ε$ in the Standard Model and $ε'/ε$ due to anomalous $WWγ$ and $WWZ$ interactions %using recent result on the top quark mass from CDF. as a function of the top quark mass. In the Standard Model, $ε'/ε$ is in the range $10^{-3} \sim 10^{-4}$ for the central value of top quark mass reported by CDF. The anomalous gauge couplings can have large contributions to the $CP$ violating $I=2$ amplitude in $K \rightarrow ππ$. Within the allowed regions for the anomalous gauge couplings, $ε'/ε$ can be dramatically different from the standard model prediction.

hep-ph↗
arXiv1994

Transverse Polarization of Top Quarks Produced at a Photon-Photon Collider

At future $γγ$ colliders copious production of $t \bar{t}$ pairs is possible. This would allow a detailed investigation of the interactions involving the top quark. We propose some orrelations which are sensitive to $t \bar{t}$ final state interactions and we compute the QCD and standard model Higgs boson contributions to these correlations. QCD induced transverse polarization of top quarks is found to be sizeable and measurable at a high-energy $e^+e^-$ collider with an integrated luminosity of 10 $({\rm fb})^{-1}$ which is converted into a photon collider by backscattering of laser photons.

hep-ph↗
arXiv1993

CP Test in the W Pair Production via Photon Fusion at NLC

We study the possibility to test CP invariance in the $W^+W^-$ production via photon fusion at NLC. The predictions of the CP violation effects are made within two Higgs doublet extensions of the minimal standard model, where CP violation is introduced by a neutral Higgs exchange in s channel in our case. The width effect in the Higgs propagator on the CP violation effects is studied in detail. The CP violation effects can be measured in some parameter region of the extensions.

hep-ph↗
arXiv1992

Neutron electric dipole moment due to Higgs exchange in Left-Right symmetric models

In this paper we study the neutron electric dipole moment (EDM) due to Higgs boson exchange in Left-Right symmetric models. In pseudo-manifest Left-Right symmetric models, the neutral Higgs contribution is smaller than that from the charged Higgs. The charged Higgs contribution at the two loop level can be as large as the experimental upper bound. In non (pseudo) manifest Left-Right symmteric models, the neutral Higgs exchange contribution can reach the experimental upper bound. The Higgs exchange contributions can be more important than the ones from W-boson exchange due to $W_L - W_R$ mixing.

hep-ph↗
arXiv1992

CP Violating Form Factors for Three Gauge Boson Vertex in the Two Higgs Doublet and Left-Right symmetric Models

In this paper we calculate the one loop contributions to the CP violating three gauge boson couplings in two-Higgs doublet and Left--Right symmetric models. In the two-Higgs doublet model only a P conserving and CP violating coupling is generated, and it can be large as $10^{-3}$. In the Left--Right symmetric model both P conserving and violating couplings are generated. Due to constraints on the $W_L$--$W_R$ mixing, these couplings are small.

hep-ph↗