Related papers: Proton size anomaly
The discrepancy between the muon $g-2$ measurement and the Standard Model prediction points to new physics around or below the weak scale. It is tantalizing to consider the loop effects of a heavy axion (in the general sense, also known as…
There is limited information about the interaction strength of a scalar dark matter candidate with hadrons and leptons for a scalar particle mass exceeding $10^{-3}$ eV while its interaction with photon is well studied. The scalar-photon…
The recent observation of a modest excess in diphoton final states at the LHC, by both the ATLAS and CMS Collaborations, has sparked off the expected race among theorists to find the right explanation for this proto-resonance, assuming that…
We consider hydrogen-like atoms in unstable levels of principal quantum number n=2, confined to a finite size region in a non-homogeneous electric field carrying handedness. The interplay between the internal degrees of freedom of the atoms…
In this paper, we consider the Standard Model (SM) with one family of vector-like (VL) leptons, which couple to all three families of the SM leptons. We study the constraints on this model coming from the heavy charged lepton mass bound,…
I provide a (personal) review of the current hints for physics beyond the Standard Model, called ``anomalies'', obtained both at the intensity frontier (flavour and electroweak precision observables) and in direct LHC searches. This…
The exchange of spin-0 or spin-1 bosons between fermions or spin-polarised macroscopic objects gives rise to various spin-dependent potentials. We derive the coordinate-space non-relativistic potentials induced by the exchange of such…
A search is presented for physics beyond the standard model (SM) using electron or muon pairs with high invariant mass. A data set of proton-proton collisions collected by the CMS experiment at the LHC at $\sqrt{s} =$ 13 TeV from 2016 to…
The possibility of explaining the current value of the muon anomalous magnetic moment in models with an additional U(1) gauge symmetry that has kinetic mixing with hypercharge are increasingly constrained by dark photon searches at electron…
We calculate the shift in the atomic energy levels induced by the presence of a scalar field which couples to matter and photons. We find that a combination of atomic measurements can be used to probe both these couplings independently. A…
Flavor-specific scalar bosons exist in various Standard Model extensions and couple to a single generation of fermions via a global flavor symmetry breaking mechanism. Given this strategy, we propose a MeV flavor-specific scalar model in…
Systematic differences in the the proton's charge radius, as determined by ordinary atoms and muonic atoms, have caused a resurgence of interest in elastic lepton scattering measurements. The proton's charge radius, defined as the slope of…
The proton polarizability correction to the Lamb shift of electronic and muonic hydrogen is calculated on the basis of isobar model and experimental data on the structure functions of deep inelastic lepton-nucleon scattering. The…
Hitherto unknown elementary particles can be searched for with atomic spectroscopy. We conduct such a search using a potential that results from the longitudinal polarization of a pseudovector particle. We show that such a potential,…
The leading order vacuum polarization contribution of very light millicharged fermions and scalar (spin-0) particles with charge \epsilon e and mass \mu to the Lamb shift of the hydrogen atom is shown to imply universal, i.e.…
We propose a model to explain the W boson mass anomaly reported by the CDFII collaboration that would suggest new physics (NP). We introduce exotic fermions; one isospin doublet vector-like lepton, one isospin singlet singly-charged…
A magnetometer using spin-polarized K and $^3$He atoms occupying the same volume is used to search for anomalous nuclear spin-dependent forces generated by a separate $^3$He spin source. We measure changes in the $^3$He spin precession…
We report a new measurement of the $n=2$ Lamb shift in Muonium using microwave spectroscopy. Our result of $1047.2(2.3)_\textrm{stat}(1.1)_\textrm{syst}$ MHz comprises an order of magnitude improvement upon the previous best measurement.…
Experimental searches for new, "fifth" forces are attracting a lot of attention because they allow to test theoretical extensions to the standard model. Here, we report a new experimental search for possible fifth forces, specifically…
If the atmospheric and the solar neutrino problem are both explained by neutrino oscillations, and if there are only three light neutrinos, then all mass-squared differences between the neutrinos are known. In such a case, existing…