Raymond R. Volkas

A model with fundamental improper spacetime symmetries

Abstract It is shown how the standard model can be extended so that both the lagrangian and the vacuum are invariant under appropriately defined space- and time-inversion transformations. This means that parity and time-reversal may actually be unbroken symmetries of nature.

Neutrino physics and the mirror world: How exact parity symmetry explains the solar neutrino deficit, the atmospheric neutrino anomaly, and the LSND experiment.

Important evidence for neutrino oscillations comes from the solar neutrino deficit and the atmospheric neutrino anomaly. Further evidence for \ensuremath{\nu}

Solution to the hierarchy problem from an almost decoupled hidden sector within a classically scale invariant theory

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Tribimaximal mixing, discrete family symmetries, and a conjecture connecting the quark and lepton mixing matrices

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Electroweak Higgs as a pseudo-Goldstone boson of broken scale invariance

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Possible consequences of parity conservation

oscillations has been reported at LAMPF using the LSND detector. All of these anomalies require new physics. We show that all of these anomalies can be explained if the standard model is enlarged so that an unbroken parity symmetry can be defined. This explanation holds independently of the actual model for neutrino masses. Thus, we argue that parity symmetry is not only a beautiful candidate for a symmetry beyond the standard model, but it can also explain the known neutrino physics anomalies.

Neutrino mass in radiatively broken scale-invariant models

If scale invariance is a classical symmetry then both the Planck scale and the weak scale should emerge as quantum effects. We show that this can be realized in simple scale invariant theories with a hidden sector. The weak/Planck scale hierarchy emerges in the (technically natural) limit in which the hidden sector decouples from the ordinary sector. In this limit, finite corrections to the weak scale are consequently small, while quadratic divergences are absent by virtue of classical scale invariance, so there is no hierarchy problem.

Reconciling sterile neutrinos with Big Bang nucleosynthesis.

Neutrino oscillation experiments (excluding the LSND experiment) suggest a tri-bimaximal form for the lepton mixing matrix. This form indicates that the mixing matrix is probably independent of the lepton masses, and suggests the action of an underlying discrete family symmetry. Using these hints, we conjecture that the contrasting forms of the quark and lepton mixing matrices may both be generated by such a discrete family symmetry. This idea is that the diagonalisation matrices out of which the physical mixing matrices are composed have large mixing angles, which cancel out due to a symmetry when the CKM matrix is computed, but do not do so in the MNS case. However, in the cases where the Higgs bosons are singlets under the symmetry, and the family symmetry commutes with SU(2)L, we prove a no-go theorem: no discrete unbroken family symmetry can produce the required mixing patterns. We then suggest avenues for future research.

Large neutrino asymmetries from neutrino oscillations

We point out that it is possible to associate the electroweak Higgs boson with the pseudo-Goldstone boson of broken scale invariance, thus resolving the hierarchy problem in a technically natural way. We illustrate this idea with two specific gauge models. Besides being consistent with all currently available experimental data, both models maintain the predictive power of the standard model, since the first model has only one additional parameter beyond the Standard Model, and the second has the same number of free parameters as the Standard Model.

Phenomenology of a very light scalar (100 MeV < mh < 10 GeV) mixing with the SM Higgs

It has been shown that parity may be an exact unbroken symmetry of nature. This requires a doubling of the number of physical particles, although only two parameters beyond those in the Standard Model are introduced. In this paper, the authors show that the Lagrangian describing parity conserving models can be reformulated in terms of a basis in which each term of the Lagrangian is parity invariant, although gauge invariance is not manifest. The authors then examine some further experimental signatures of parity conservation. The authors point out that, in the simplest case, there is one parity-even and one parity-odd physical neutral Higgs mass eigenstate, whose Yukawa coupling constants are 1/ sq. root 2 that of the Standard Model Higgs boson. Furthermore, half of their widths are generated by almost invisible decay modes. Also, if neutrinos are massive then the ordinary and mirror neutrinos will, in the minimal case, be maximally mixed due to parity conservation. This means that vacuum oscillations can be large, thus providing a possible solution to the solar neutrino problem.