Related papers: Updated Bounds on Milli-Charged Particles
A range of experimental results point to the existence of a massive neutrino. The recent high precision measurements of the cosmic microwave background and the large scale surveys of galaxies can be used to place an upper bound on this…
Particles with millicharge q and sub-eV mass can be produced in photon-photon collisions, distorting the energy spectrum of the Cosmic Microwave Background. We derive the conservative bound q < 10^-7 e (as well as model-dependent bounds two…
The constraints on the mixing angles of the standard fermions with new heavy particles that can appear in many extensions of the electroweak theory are reviewed. Some emphasis is put in distinguishing the effects of a mixing with new states…
We revisit constraints on the electric charge of the neutron and neutrino as well as on e_p+e_e. We consider phenomenological constraints based on laboratory study of the electrical neutrality of subatomic, atomic, and molecular species…
We propose a new constraint on millicharged dark matter from considerations on galaxy clusters. The charged dark matter moves under the influence of the randomly oriented magnetic fields in galaxy clusters, and the corresponding dark matter…
Using the new limit on the neutrino anomalous magnetic moment recently obtained by the GEMMA experiment on measurements of the cross section for the reactor antineutrino scattering on free electrons, we get a new direct upper bound on the…
Phenomenology of possible neutrino millicharge in terrestrial and astrophysical settings is discussed. Two new limits on the millicharge from terrestrial experiments and astrophysics are reported.
The small-scale power spectrum of the cosmological matter distribution together with other cosmological data provides a sensitive measure of the hot dark matter fraction, leading to restrictive neutrino mass limits. We extend this argument…
It has been recently suggested that the vacuum magnetic dichroism observed by the PVLAS experiment could be explained by the pair production of a new light, m ~0.1 eV, millicharged, q ~ 3 10^{-6} e, fermions. In addition, it has been…
Very light particles with CP-violating couplings to ordinary matter, such as axions or axion-like particles, can mediate long-range forces between polarized and unpolarized fermions. We describe a new experimental search for such forces…
The extreme properties of neutron stars provide unique opportunities to put constraints on new particles and interactions. In this paper, we point out a few interesting ideas that place constraints on light millicharged fermions, with…
We discuss the possibility of a laboratory search for light minicharged particles carrying electric charge that is a small fraction $\epsilon$ of that of electron. We point out that the production of pairs of such particles in an electric…
Although neutrinos are probably the most abundant particles of the universe their mass is not yet known. Oscillation experiments have proven that at least one of the neutrino mass states has m_{i}>0.05 eV while various interpretations of…
We investigate the impact of prior models on the upper bound of the sum of neutrino masses, $\sum m_{\nu}$. We use data from Large Scale Structure of galaxies, Cosmic Microwave Background, Type Ia SuperNovae, and Big Bang Nucleosynthesis.…
Heat transfer between baryons and millicharged dark matter has been invoked as a possible explanation for the anomalous 21-cm absorption signal seen by EDGES. Prior work has shown that the solution requires that millicharged particles make…
The massless fermion limit of QED is discussed. For on-shell renormalisation the high energy behaviour fixes no lower limit on the mass of the lightest fermion if the fine structure constant $\alpha$ is allowed to vary. The choice of an…
We derive limits on a class of new physics effects that are naturally present in grand unified theories based on extended gauge groups, and in particular in $E_6$ and $SO(10)$ models. We concentrate on $i$) the effects of the mixing of new…
We investigate the impact of a nonstandard electron mass $m_e$ on early-Universe thermal history, focusing on neutrino decoupling and Big Bang Nucleosynthesis (BBN). In the standard cosmology, neutrino--electron interactions keep neutrinos…
The latest cosmological constraints on the sum of the neutrino masses depend on prior physical assumptions about the mass spectrum. To test the accordance of cosmological and laboratory constraints in the absence of such priors, we…
How light can a fermion be if it has unit electric charge? We revisit the lore that LEP robustly excludes charged fermions lighter than about 100 GeV. We review LEP chargino searches, and find them to exclude charged fermions lighter than…