arXiv subjects
Publications and source records attributed to R. Foot.
Mirror matter-type dark matter is one dark matter candidate which is particularly well motivated from high energy physics. The theoretical motivation and experimental evidence are pedagogically reviewed, with emphasis on the implications of recent orthopositronium experiments, the DAMA/NaI dark matter search, anomalous meteorite events etc.
The super-Kamiokande collaboration have used multi-ring events to discriminate between the $ν_μ--> ν_τ$ and $ν_μ--> ν_s$ solutions to the atmospheric neutrino anomaly. We show that the effect of systematic uncertainties in cross sections are so significant that the usefulness of multi-ring data to distinguish between these two solutions is doubtful.
Mirror matter type dark matter can exist on the Earth's surface, potentially in enhanced concentrations at various anomalous impact sites. Mirror matter fragments can draw in heat from the ordinary matter environment, radiate mirror photons and thereby cool the surrounding ordinary matter. We quantify this effect and suggest that it could be used to help locate mirror matter deposits. This method, together with the centrifuge technique, seems to provide the most promising means to experimentally detect mirror matter type dark matter in the Earth.
The cosmological dust has begun to settle. A likely picture is a universe comprised (predominantly) of three components: ordinary baryons ($Ω_B \approx 0.05$), non-baryonic dark matter ($Ω_{Dark} \approx 0.22$) and dark energy ($Ω_Λ \approx 0.7$). We suggest that the observed similarity of the abundances of ordinary baryons and non-baryonic dark matter ($Ω_{B}/Ω_{Dark} \approx 0.20$) hints at an underlying similarity between the fundamental properties of ordinary and dark matter particles. This is necessarily the case if dark matter is identified with mirror matter. We examine a specific mirror matter scenario where $Ω_B/Ω_{Dark} \approx 0.20$ is naturally obtained.
A new and inexpensive technique for detecting self interacting dark matter in the form of small grains in bulk matter is proposed. Depending on the interactions with ordinary matter, dark matter grains in bulk matter may be isolated by using a centrifuge and using ordinary matter as a filter. The case of mirror matter interacting with ordinary matter via photon-mirror photon kinetic mixing provides a concrete example of this type of dark matter candidate.
Mirror matter is an entirely new form of matter predicted to exist if mirror symmetry is a fundamental symmetry of nature. Mirror matter has the right broad properties to explain the inferred dark matter of the Universe and might also be responsible for a variety of other puzzles in particle physics, astrophysics, meteoritics and planetary science. It is known that mirror matter can interact with ordinary matter non-gravitationally via photon-mirror photon kinetic mixing. The strength of this possibly fundamental interaction depends on the (theoretically) free parameter $ε$. We consider various proposed manifestations of mirror matter in our solar system examining in particular how the physics changes for different possible values of $ε$. We find new evidence for mirror matter in the solar system coming from the observed sharp reduction in crater rates (for craters less than about 100 meters in diameter) on the asteroid 433 Eros. We also re-examine various existing ideas including the mirror matter explanation for the anomalous meteorite events, anomalous slow-down of Pioneer spacecraft etc.
There is a unique $\hbox{SU(4)}\otimes\hbox{SU(2)}_L \otimes \hbox{SU(2)}_R$ gauge model which allows quarks and leptons to be unified at the TeV scale -- thereby making the model testable and avoiding the gauge hierarchy problem. In its minimal form, this model could quite naturally accommodate simultaneous solutions to the solar and LSND neutrino oscillation data. The atmospheric neutrino anomaly can be easily accommodated by mirror-symmetrising the minimal model. The model also contains three right-handed neutrinos, with masses in the range 1 keV to $\sim$ 1 GeV. We investigate the implications of these right-handed neutrinos for early Universe cosmology. It is shown that the minimal model is inconsistent with some of the standard assumptions of the big bang model. This motivates an examination of non-standard big bang cosmology, such as a low reheating temperature scenario with $T_{RH} \sim$ MeV. In such a Universe, peaceful co-existence between low-scale quark-lepton gauge unification and early Universe cosmology is possible.
We show explicitly that four neutrino models of the 2+2 variety still provide an acceptable global fit to the solar, atmospheric and LSND neutrino data. The goodness of fit, defined in the usual way, is found to be 0.26 for the simplest such model. That is, we find that there is a 26% probability of obtaining a worse global fit to the neutrino data We also make some specific comments on the paper, ``Ruling out four-neutrino oscillation interpretations of the LSND anomaly'' [hep-ph/0207157], and explain why they reached drastically different conclusions.
Mirror symmetry is a plausible candidate for a fundamental symmetry of particle interactions which can be exactly conserved if a set of mirror particles exist. The properties of the mirror particles seem to provide an excellent candidate to explain the inferred dark matter of the Universe and might also be responsible for a variety of other puzzles in particle physics, astrophysics, meteoritics and planetary science. One such puzzle -- the orthopositronium lifetime problem -- can be explained if there is a small kinetic mixing of ordinary and mirror photons. We show that this kinetic mixing implies the existence of ordinary atom - mirror atom bound states with interesting terrestrial and astrophysical implications. We suggest that sensitive mass spectroscopic studies of ordinary samples containing heavy elements such as lead might reveal the presence of these bound states, as they would appear as anomalously heavy elements. In addition to the effects of single mirror atoms, collective effects from embedded fragments of mirror matter (such as mirror iron microparticles) are also possible. We speculate that such mirror matter fragments might explain a mysterious UV photon burst observed coming from a laser irradiated lead target in a recent experiment.
SNO's neutral current measurement has added a new piece to the emerging neutrino physics puzzle. Putting together the presently available experimental information, an essentially unique picture emerges: The solar neutrino anomaly is explained by nu_e --> nu_tau oscillations, the atmospheric neutrino anomaly is explained by nu_{mu} --> nu_s and the LSND data are explained by nu_e --> nu_{mu}. This scheme will be tested by future experiments: MiniBooNE will test the oscillation explanation of the LSND anomaly, while the long baseline experiments will discriminate between the nu_{mu} --> nu_s and nu_{mu} --> nu_{tau} possibilities for resolving the atmospheric anomaly (confirming or disconfirming the Super-Kamiokande result that the latter is favoured over the former).
There are a number of very puzzling meteoritic events including (a) The Tunguska event. It is the only known example of a low altitude atmospheric explosion. It is also the largest recorded event. Remarkably no fragments or significant chemical traces have ever been recovered. (b) Anomalous low altitude fireballs which (in some cases) have been observed to hit the ground. The absence of fragments is particularly striking in these cases, but this is not the only reason they are anomalous. On the other hand, there is strong evidence that most of our galaxy is made from exotic dark material - `dark matter'. Mirror matter is one well motivated dark matter candidate, since it is dark and stable and it is required to exist if particle interactions are mirror symmetric. If mirror matter is the dark matter, then some amount must exist in our solar system. We demonstrate that the mirror matter theory allows for a simple explanation for the puzzling meteoritic events [both (a) and (b)] if they are due to mirror matter space-bodies. A direct consequence of this explanation is that mirror matter fragments should exist in (or on) the ground at various impact sites. The properties of this potentially recoverable material depend importantly on the sign of the photon-mirror photon kinetic mixing parameter, $ε$. We argue that the broad characteristics of the anomalous events suggests that $ε$ is probably negative. Strategies for detecting mirror matter in the ground are discussed.
It is well established that active-sterile neutrino oscillations generate large neutrino asymmetries for very small mixing angles ($\sin^2 2θ_0\lesssim 10^{-4}$), negative values of $δm^2$ and provided that $|δm^2|\gtrsim 10^{-4} {\rm eV^2}$. By numerically solving the quantum kinetic equations, we show that the generation still occurs at much lower values of $|δm^2|$. We also describe the borders of the generation at small mixing angles and show how our numerical results can be analytically understood within the framework of the Landau-Zener approximation thereby extending previous work based on the adiabatic limit. This approximate approach leads to a fair description of the MSW dominated regime of the neutrino asymmetry evolution and is also able to correctly reproduce its final value. We also briefly discuss the impact that neutrino asymmetry generation could have on big bang nucleosynthesis, CMBR and relic neutrinos.
There is a unique $SU(4) \otimes SU(2)_L \otimes SU(2)_R$ gauge model which allows quarks and leptons to be unified at the TeV scale. It is already known that the neutrino masses arise radiatively in the model and are naturally light. We study the atmospheric, solar and LSND neutrino anomalies within the framework of this model.
We show that the anomalous acceleration of the Pioneer 10/11 spacecraft can be explained if there is some mirror gas or mirror dust in our solar system.
Mirror matter is predicted to exist if parity (i.e. left-right symmetry) is a symmetry of nature. Remarkably mirror matter is capable of simply explaining a large number of contemporary puzzles in astrophysics and particle physics including: Explanation of the MACHO gravitational microlensing events, the existence of close-in extrasolar gas giant planets, apparently `isolated' planets, the solar, atmospheric and LSND neutrino anomalies, the orthopositronium lifetime anomaly and perhaps even gamma ray bursts. One fascinating possibility is that our solar system contains small mirror matter space bodies (asteroid or comet sized objects), which are too small to be revealed from their gravitational effects but nevertheless have explosive implications when they collide with the Earth. We examine the possibility that the 1908 Tunguska explosion in Siberia was the result of the collision of a mirror matter space body with the Earth. We point out that if the catastrophic event and many other similar smaller events are manifestations of the mirror world then these impact sites should be a good place to start digging for mirror matter. Mirror matter could potentially be extracted and purified using a centrifuge and have many useful industrial applications.
Over the last few years, many close orbiting ($\sim 0.05$ A.U.) large mass planets ($\sim M_{J}$) of nearby stars have been discovered. Their existence has been inferred from tiny Doppler shifts in the light from the star and in one case a transit has been observed. Because ordinary planets are not expected to be able to form this close to ordinary stars due to the high temperatures, it has been speculated that the close-in large planets are in fact exotic heavenly bodies made of mirror matter. We show that the accretion of ordinary matter onto the mirror planet (from e.g.the solar wind from the host star) should make the mirror planet opaque to ordinary radiation with an effective radius ($R_p$) large enough to explain the measured size of the transiting close-in extrasolar planet, HD209458b. Furthermore we obtain the rough prediction that $R_{p} \propto \sqrt{T_s\over M_p}$ (where $T_s$, is the surface temperature of the ordinary matter in the mirror planet and $M_p$ is the mass of the mirror planet) which will be tested in the near future as more transiting planets are found. We also show that the mirror world interpretation of the close-in extra solar planets explains the low albedo of $τ$ Boo b because the large estimated mass of $τ$ Boo b ($\sim 7M_J$) implies a small effective radius of $R_p \approx 0.5R_J$ for $τ$ Boo.
Mirror matter is predicted to exist if parity is an unbroken symmetry of nature. Currently, there is a large amount of evidence that mirror matter actually exists coming from astrophysics and particle physics. One of the most fascinating (but speculative) possibilities is that there is a significant abundance of mirror matter within our solar system. If the mirror matter condensed to form a large body of planatary or stellar mass then there could be interesting observable effects. Indeed studies of long period comets suggest the existence of a solar companion which has escaped direct detection and is therefore a candidate for a mirror body. Nemesis, hypothetical "death star" companion of the Sun, proposed to explain biological mass extinctions, may potentially be a mirror star. We examine the prospects for detecting these objects if they do indeed exist and are made of mirror matter.
Parity and time reversal are obvious and plausible candidates for fundamental symmetries of nature. Hypothesising that these symmetries exist implies the existence of a new form of matter, called mirror matter. The mirror matter theory (or exact parity model) makes four main predictions: 1) Dark matter in the form of mirror matter should exist in the Universe (i.e. mirror galaxies, stars, planets, meteoroids...), 2) Maximal ordinary neutrino - mirror neutrino oscillations if neutrinos have mass, 3) Orthopositronium should have a shorter effective lifetime than predicted by QED (in "vacuum" experiments) because of the effects of photon-mirror photon mixing and 4) Higgs production and decay rate should be 50% lower than in the standard model due to Higgs mirror - Higgs mixing (assuming that the seperation of the Higgs masses is larger than their decay widths). At the present time there is strong experimental/observational evidence supporting the first three of these predictions, while the fourth one is not tested yet because the Higgs boson, predicted in the standard model of particle physics, is yet to be found. This experimental/observational evidence is rich and varied ranging from the atmospheric and solar neutrino deficits, MACHO gravitational microlensing events, strange properties of extra-solar planets, the existence of "isolated" planets, orthopositronium lifetime anomaly, Tunguska and other strange "meteor" events including perhaps, the origin of the moon. The purpose of this article is to provide a not too technical review of these ideas along with some new results.