arXiv subjects

R. Foot

Publications and source records attributed to R. Foot.

At least 55 records · Page 3Linked to original sources

arXiv2009

Mirror dark matter interpretation of the DAMA/Libra annual modulation signal

The DAMA/Libra experiment has recently confirmed the annual modulation signal obtained in the earlier DAMA/NaI experiment, providing strong evidence that they have actually detected dark matter. We examine the implications of this experiment for the mirror dark matter candidate. We show that mirror dark matter successfully explains the latest DAMA/Libra data, whilst also being consistent with the null results of other direct detection experiments.

astro-ph.CO↗

arXiv2008

Mirror dark matter and the new DAMA/LIBRA results: A simple explanation for a beautiful experiment

Recently, the DAMA/LIBRA experiment has convincingly confirmed the DAMA/NaI annual modulation signal, experimentally demonstrating the existence of non-baryonic dark matter in the halo of our galaxy. Meanwhile, in another part of town, other experiments such as CDMS and XENON10 have not detected any evidence for dark matter. One promising dark matter candidate which can reconcile the positive DAMA annual modulation signal with the null results from the other experiments, is mirror dark matter. We re-analyse the mirror matter interpretation of the DAMA annual modulation signal utilizing a) the new data from DAMA/LIBRA, including the measured energy dependence of the annual modulation signal b) an updated quenching factor which takes into account the channeling effect in $NaI$ crystals and c) the latest constraints from CDMS/Ge, CDMS/Si and XENON10 experiments. We show that the simplest possibility of a $He'$ (and/or $H'$) dominated halo with a small $O'$ component is sufficient to fully explain all of the dark matter experiments. We also point out that a certain class of hidden sector dark matter models, although theoretically less appealing and less constrained, can mimic the success of the mirror dark matter model and hence are also viable.

hep-ph↗

arXiv2007

Mirror dark matter

A mirror sector of particles and forces provides a simple explanation of the inferred dark matter of the Universe. The status of this theory is reviewed - with emphasis on how the theory explains the impressive DAMA/NaI annual modulation signal, whilst also being consistent with the null results of the other direct detection experiments.

hep-ph↗

arXiv2007

A simple explanation of the PVLAS anomaly in spontaneously broken mirror models

The PVLAS anomaly can be explained if there exist millicharged particles of mass $\stackrel{<}{\sim} 0.1$ eV and electric charge $ε\sim 10^{-6} e$. We point out that such particles occur naturally in spontaneously broken mirror models. We argue that this interpretation of the PVLAS anomaly is not in conflict with astrophysical constraints due to the self interactions of the millicharged particles which lead them to be trapped within stars. This conclusion also holds for a generic paraphoton model.

hep-ph↗

arXiv2006

Generalised leptonic colour

It is conceivable that there is an $SU(N)_{\ell}$ `colour' gauge group for leptons, analogous to the gauged $SU(3)_q$ colour group of the quarks. The standard model emerges as the low energy effective theory when the leptonic colour is spontaneously broken. The simplest such generalised leptonic colour models are constructed. We show that the see-saw mechanism for small neutrino masses, along with the theoretical constraint of electric charge quantisation, suggests that the models with $N = 3, 5, 7$ are the theoretically most promising cases. A striking feature of generalized leptonic colour is the physics associated with the extra leptonic degrees of freedom -- the liptons. These particles can potentially be discovered at future colliders, such as the LHC, making the idea testable in the near future.

hep-ph↗

arXiv2006

Natural electroweak symmetry breaking in generalised mirror matter models

It has recently been pointed out that the mirror or twin Higgs model is more technically natural than the standard model, thus alleviating the ``little'' hierarchy problem. In this paper we generalise the analysis to models with an arbitrary number of isomorphic standard model sectors, and demonstrate that technical naturalness increases with the number of additional sectors. We consider two kinds of models. The first has $N$ standard model sectors symmetric under arbitrary permutations thereof. The second has $p$ left-chiral standard model sectors and $p$ right-chiral or mirror standard model sectors, with $p$-fold permutation symmetries within both and a discrete parity transformation interchanging left and right. In both kinds of models the lightest scalar has an invisible width fraction 1/N, which will provide an important means of experimentally testing this class of models.

hep-ph↗

arXiv2006

Implications of the DAMA/NaI and CDMS experiments for mirror matter-type dark matter

We re-analyse the implications of the DAMA/NaI experiment for mirror matter-type dark matter, taking into account information from the energy dependence of the DAMA annual modulation signal. This is combined with the null results from the CDMS experiment, leading to fairly well defined allowed regions of parameter space. The allowed regions of parameter space will be probed in the near future by the DAMA/LIBRA, CDMS, and other experiments, which should either exclude or confirm this explanation of the DAMA/NaI annual modulation signal. In particular, we predict that the CDMS experiments should find a positive signal around the threshold recoil energy region, E_R < 15 keV in the near future.

astro-ph↗

arXiv2005

Generalized mirror matter models

Non-minimal gauge models with exact unbroken improper space-time symmetries are constructed and their cosmological and astrophysical implications explored.

hep-ph↗

arXiv2005

Avoiding the gauge heirarchy problem with see-sawed neutrino masses

We show that the see-saw neutrino mass mechanism can coexist naturally with an extended gauge symmetry (i.e. without any gauge heirarchy problem) provided that the gauge symmetry contains gauged lepton number differences. The simplest such `natural' see-saw models are constructed and their implications for neutrino anomalies discussed.

hep-ph↗

arXiv2004

Mirror matter-type dark matter

There are six main things which any non-baryonic dark matter theory should endeavour to explain: (1) The basic dark matter particle properties [mass, stability, darkness]; (2) The similarity in cosmic abundance between ordinary and non-baryonic dark matter, $Ω_B \sim Ω_{dark}$; (3) Large scale structure formation; (4) Microlensing (MACHO) events; (5) Asymptotically flat rotation curves in spiral galaxies; (6) The impressive DAMA/NaI annual modulation signal. Only mirror matter-type dark matter is capable of explaining all six of these desirable features. The purpose of this article is to provide an up-to-date and pedagogical review of this dark matter candidate.

astro-ph↗

arXiv2004

Spheroidal galactic halos and mirror dark matter

Mirror matter has been proposed as a dark matter candidate. It has several very attractive features, including automatic stability and darkness, the ability to mimic the broad features of cold dark matter while in the linear density perturbation regime, and consistency with all direct dark matter search experiments, both negative (e.g. CDMS II) and positive (DAMA). In this paper we consider an important unsolved problem: Are there plausible reasons to explain why most of the mirror matter in spiral galaxies exists in the form of gaseous {\it spheroidal} galactic halos around ordinary matter {\it disks}? We compute an order-of-magnitude estimate that the mirror photon luminosity of a typical spiral galaxy today is around $10^{44}$ erg/s. Interestingly, this rate of energy loss is similar to the power supplied by ordinary supernova explosions. We discuss circumstances under which supernova power can be used to heat the gaseous part of the mirror matter halo and hence prevent its collapse to a disk. The {\it macro}scopic ordinary-mirror asymmetry plays a fundamental role in our analysis.

astro-ph↗

arXiv2004

Testing the mirror world hypothesis for the close-in extrasolar planets

Because planets are not expected to be able to form close to stars due to the high temperatures, it has been suggested that the observed close orbiting ($\sim 0.05$ AU) large mass planets ($\sim M_J$) might be mirror worlds -- planets composed predominately of mirror matter. The accretion of ordinary matter onto the mirror planet (from e.g. the solar wind from the host star) will make the mirror planet opaque to ordinary radiation with an effective radius $R_p$. It was argued in a previous paper, astro-ph/0101055, that this radius was potentially large enough to explain the measured size of the first transiting close-in extrasolar planet, HD209458b. Furthermore, astro-ph/0101055, made the rough prediction: $R_p \propto \sqrt{T_s \over M_p}$, where $T_s$ is the surface temperature of the ordinary matter in the mirror planet and $M_p$ is the mass of the planet (the latter dependence being the more robust prediction). We compare this prediction with the recently discovered transiting planets, OGLE-TR-56b and OGLE-TR-113b.

astro-ph↗

arXiv2004

Exploring the mirror matter interpretation of the DAMA experiment: Has the dark matter problem been solved?

The self consistency between the impressive DAMA annual modulation signal and the differential energy spectrum is an important test for dark matter candidates.Mirror matter-type dark matter passes this test while other dark matter candidates, including standard (spin-independent) WIMPs and mini-electric charged particle dark matter, do not do so well.We argue that the unique properties of mirror matter-type dark matter seem to be just those required to fully explain the data, suggesting that the dark matter problem has finally been solved.

astro-ph↗

arXiv2004

Reconciling the positive DAMA annual modulation signal with the negative results of the CDMS II experiment

We examine the recent CDMS II results in the context of the mirror matter interpretation of the DAMA/NaI experiment.We find that the favoured mirror matter interpretation of the DAMA/NaI experiment -- a $He'/H'$ dominated halo with a small $O'$ component is fully consistent with the null results reported by CDMS II. While the CDMS II experiment is quite sensitive to a heavy $Fe'$ component, and may yet find a positive result, a more decisive test of mirror matter-type dark matter would require a lower threshold experiment using light target elements.

astro-ph↗

arXiv2004

Supernova explosions, 511 keV photons, gamma ray bursts and mirror matter

There are three astroparticle physics puzzles which fire the imagination: the origin of the ``Great Positron Producer'' in the galactic bulge, the nature of the gamma-ray bursts central engine and the mechanism of supernova explosions. We show that the mirror matter model has the potential to solve all three of these puzzles in one beautifully simple strike.

astro-ph↗

arXiv2004

Explaining $Ω_{Baryon} \approx 0.2 Ω_{Dark}$ through the synthesis of ordinary matter from mirror matter: a more general analysis

The emerging cosmological picture is of a spatially flat universe composed 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 recently proposed that ordinary matter was synthesised from mirror matter, motivated by the argument that the observed similarity of $Ω_B$ and $Ω_{Dark}$ suggests an underlying similarity between the fundamental properties of ordinary and dark matter particles. In this paper we generalise the previous analysis by considering a wider class of effective operators that non-gravitationally couple the ordinary and mirror sectors. We find that while all considered operators imply $Ω_{Dark} = $ few$\times Ω_B$, only a subset quantitatively reproduce the observed ratio $Ω_B/Ω_{Dark} \approx 0.20$. The $\sim 1$ eV mass scale induced through these operators hints at a connection with neutrino oscillation physics.

hep-ph↗

arXiv2004

Implications of the DAMA and CRESST experiments for mirror matter-type dark matter

Mirror atoms are expected to be a significant component of the galactic dark matter halo if mirror matter is identified with the non-baryonic dark matter in the Universe. Mirror matter can interact with ordinary matter via gravity and via the photon-mirror photon kinetic mixing interaction -- causing mirror charged particles to couple to ordinary photons with effective electric charge $εe$. This means that the nuclei of mirror atoms can elastically scatter off the nuclei of ordinary atoms, leading to nuclear recoils, which can be detected in existing dark matter experiments. We show that the dark matter experiments most sensitive to this type of dark matter candidate (via the nuclear recoil signature) are the DAMA/NaI and CRESST/Sapphire experiments. Furthermore, we show that the impressive annual modulation signal obtained by the DAMA/NaI experiment can be explained by mirror matter-type dark matter for $|ε| \sim 4 \times 10^{-9}$ and is supported by DAMA's absolute rate measurement as well as the CRESST/Sapphire data. This value of $|ε|$ is consistent with the value obtained from various solar system anomalies including the Pioneer spacecraft anomaly, anomalous meteorite events and lack of small craters on the asteroid Eros. It is also consistent with standard BBN.

hep-ph↗

arXiv2003

Have mirror micrometeorites been detected?

Slow-moving ($v \sim 15$ km/s) 'dark matter particles' have allegedly been discovered in a recent experiment. We explore the possibility that these slow moving dark matter particles are small mirror matter dust particles originating from our solar system. Ways of further testing our hypothesis, including the possibility of observing these dust particles in cryogenic detectors such as NAUTILUS, are also discussed.

hep-ph↗