Related papers: Precision muon decay measurements and improved con…
We present the first measurement of the energy spectrum up to 70 MeV of electrons from the decay of negative muons after they become bound in $^{27}$Al atoms. The data were taken with the TWIST apparatus at TRIUMF. We find a muon lifetime…
In an effort to resolve the discrepancy between two measurements of the fundamental constant mu, the proton to electron mass ratio, at early times in the universe we reanalyze the same data used in the earlier studies. Our analysis of the…
We review the recent measurements of the rare pion decays: Pi+ -> Pi0 e+ Nu [pion beta, Pi_(e3), or Pi_beta decay], radiative decay Pi+ -> e+ Nu Gamma [Pi_(e2Gamma) or RPD], and Pi+ -> e+ Nu [Pi_(e2)] decay, as well as the radiative muon…
In this article, we explore the ability of direct and indirect dark matter experiments to not only detect neutralino dark matter, but to constrain and measure the parameters of supersymmetry. In particular, we explore the relationship…
This paper presents the muon momentum calibration and performance studies for the ATLAS detector based on the $pp$ collisions data sample produced at $\sqrt{s}$=13 TeV at the LHC during Run 2 and corresponding to an integrated luminosity of…
The forward-backward charge asymmetry for the process $q\bar{q} \rightarrow Z/\gamma^{\ast} \rightarrow \mu^{+}\mu^{-}$ is measured as a function of the invariant mass of the dimuon system. Measurements are performed using proton proton…
The Standard Model of particle physics encapsulates our current best understanding of physics at the smallest scales. A fundamental axiom of this theory is the universality of the couplings of the different generations of leptons to the…
The variation of the dimensionless fundamental physical constant mu=m_p/m_e can be checked through observation of Lyman and Werner lines of molecular hydrogen in the spectra of distant QSOs. Our intention is to asses the accuracy of the…
In a previous paper, new sets of parameters to replace the Michel parameters were proposed to analyze data for the muon decay $\mu^{+} \to e^{+}\nu_{e}\bar{\nu_{\mu}}$. Both $(V-A)$ and $(V+A)$ charged currents with finite neutrino mass…
Neutrino oscillation data indicate that $\theta_{23}$ is close to $\pi/4$ and $\theta_{13}$ is very small. A simple $\mu\leftrightarrow\tau$ exchange symmetry of the neutrino mass matrix predicts $\theta_{23}=-\pi/4$ and $\theta_{13}=0$.…
The proton asymmetry parameter C in neutron decay describes the correlation between neutron spin and proton momentum. In this Letter, the first measurement of this quantity is presented. The result C=-0.2377(26) agrees with the Standard…
Recently a new method for determining the neutrino mass hierarchy by comparing the effective values of the atmospheric \Delta m^2 measured in the electron neutrino disappearance channel, \Delta m^2(ee), with the one measured in the muon…
Direct detection experiments searching for weakly interacting massive particle (WIMP) dark matter typically use a simplified model of the Galactic halo to derive parameter constraints. However, there is strong evidence that this Standard…
Precision measurements at low energy search for physics beyond the Standard Model in a way complementary to searches for new particles at colliders. In the weak sector the most general $\beta$ decay Hamiltonian contains, besides vector and…
Within the standard $3\nu$ framework, we discuss updated bounds on the leading oscillation parameters related to the $(\nu_1,\,\nu_2)$ states, namely, the squared mass difference $\delta m^2=m^2_2-m^2_1$ and the mixing parameter…
In the standard model of electroweak interactions the positrons from the decay of polarized positive muons are mainly longitudinally polarized. The measurement of the two transverse polarization components PT1 and PT2 is a sensitive tool to…
We present a new measurement of the tau neutrino helicity, hnu and the tau Michel parameters rho, eta, xi and the product delta xi. The analysis exploits the highly polarized SLC electron beam to extract these quantities directly from a…
We study dimuon events in 2.11/fb of 7 TeV pp collisions, using CMS Open Data, and search for a narrow dimuon resonance with moderate mass (14-66 GeV) and substantial transverse momentum (pT). Applying dimuon pT cuts of 25 GeV and 60 GeV,…
The aim of the MuCap experiment is a 1% measurement of the singlet capture rate Lambda_S for the basic electro-weak reaction mu + p -> n + nu_mu. This observable is sensitive to the weak form-factors of the nucleon, in particular to the…
We propose a new experiment to search for a time-reversal (T) symmetry breaking process in muon decay and the Majoranality of the neutrinos. In the presence of V+A interactions, the Majoranality appears as a T-violating term in the muon…