Search results for " DIP"
showing 10 items of 1273 documents
Hadronic Contributions to the Anomalous Magnetic Moment of the Muon from Lattice QCD
2021
The Standard Model of Particle Physics describes three of the four known fundamental interactions: the strong interaction between quarks and gluons, the electromagnetic interaction, and the weak interaction. While the Standard Model is extremely successful, we know that it is not a complete description of nature. One way to search for physics beyond the Standard Model lies in the measurement of precision observables. The anomalous magnetic moment of the muon \(a_\mu \equiv \frac{1}{2}(g-2)_\mu \), quantifying the deviation of the gyromagnetic ratio from the exact value of 2 predicted by the Dirac equation, is one such precision observable. It exhibits a persistent discrepancy of 3.5 standar…
Lattice calculations of the leading hadronic contribution to g-2
2012
We report on our ongoing project to calculate the leading hadronic contribution to the anomalous magnetic moment of the muon aHLO μ using two dynamical flavours of non-perturbatively O(a) improved Wilson fermions. In this study, we changed the vacuum polarisation tensor to a combination of local and point-split currents which significantly reduces the numerical effort. Partially twisted boundary conditions allow us to improve the momentum resolution of the vacuum polarisation tensor and therefore the determination of the leading hadronic contribution to (g− 2)μ . We also extended the range of ensembles to include a pion mass below 200MeV which allows us to check the non-trivial chiral behav…
Search for Axionlike Dark Matter Using Solid-State Nuclear Magnetic Resonance.
2021
Physical review letters 126(14), 141802 (2021). doi:10.1103/PhysRevLett.126.141802
Bottomonium precision tests from full lattice QCD: Hyperfine splitting, ϒ leptonic width, and b quark contribution to e+e−→hadrons
2021
We calculate the mass difference between the $\mathrm{\ensuremath{\Upsilon}}$ and ${\ensuremath{\eta}}_{b}$ and the $\mathrm{\ensuremath{\Upsilon}}$ leptonic width from lattice QCD using the highly improved staggered quark formalism for the $b$ quark and including $u$, $d$, $s$ and $c$ quarks in the sea. We have results for lattices with lattice spacing as low as 0.03 fm and multiple heavy quark masses, enabling us to map out the heavy quark mass dependence and determine values at the $b$ quark mass. Our results are ${M}_{\mathrm{\ensuremath{\Upsilon}}}\ensuremath{-}{M}_{{\ensuremath{\eta}}_{b}}=57.5(2.3)(1.0)\text{ }\text{ }\mathrm{MeV}$ (where the second uncertainty comes from neglect of …
Resonance interaction energy between two entangled atoms in a photonic bandgap environment
2018
We consider the resonance interaction energy between two identical entangled atoms, where one is in the excited state and the other in the ground state. They interact with the quantum electromagnetic field in the vacuum state and are placed in a photonic-bandgap environment with a dispersion relation quadratic near the gap edge and linear for low frequencies, while the atomic transition frequency is assumed to be inside the photonic gap and near its lower edge. This problem is strictly related to the coherent resonant energy transfer between atoms in external environments. The analysis involves both an isotropic three-dimensional model and the one-dimensional case. The resonance interaction…
Search for CP-violating nuclear magnetic quadrupole moment using the LuOH+ cation
2020
The time-reversal and spatial parity violating interaction of the nuclear magnetic quadrupole moment (MQM) of the 175Lu and 176Lu nuclei with electrons in the molecular cation LuOH+ is studied. The resulting effect is expressed in terms of fundamental parameters, such as quantum chromodynamics angle θ⎯⎯, quark electric dipole moment (EDM), and chromo-EDM. For this, we have estimated the magnetic quadrupole moments of 175Lu and 176Lu nuclei and calculated the molecular constant that characterizes the interaction of the MQM with electrons in the considered molecules. Additionally, we predict the hyperfine structure constants for the ground electronic state of LuOH+. In the molecular calculati…
Measurement of trilinear gauge boson couplings WWV, (V Z,gamma) in e(+)e(-) collisions at 189 GeV
2001
Measurements of the trilinear gauge boson couplings WWgamma and WWZ are presented using the data taken by DELPHI in 1998 at a centre-of-mass energy of 189 GeV and combined with DELPHI data at 183 GeV. Values are determined for Delta(g_1^Z) and Delta(kappa_gamma), the differences of the WWZ charge coupling and of the WWgamma dipole coupling from their Standard Model values, and for lambda_gamma, the WWgamma quadrupole coupling. A measurement of the magnetic dipole and electric quadrupole moment of the W is extracted from the results for Delta(kappa_gamma) and lambda_gamma. The study uses data from the final states jjlv, jjjj, lX, jjX and gammaX, where j represents a quark jet, l an identifie…
Electromagnetic structure of few-nucleon ground states
2015
Experimental form factors of the hydrogen and helium isotopes, extracted from an up-to-date global analysis of cross sections and polarization observables measured in elastic electron scattering from these systems, are compared to predictions obtained in three different theoretical approaches: the first is based on realistic interactions and currents, including relativistic corrections (labeled as the conventional approach); the second relies on a chiral effective field theory description of the strong and electromagnetic interactions in nuclei (labeled $\chi$EFT); the third utilizes a fully relativistic treatment of nuclear dynamics as implemented in the covariant spectator theory (labeled…
Lattice calculation of the hadronic leading order contribution to the muon g − 2
2019
The European physical journal / Web of Conferences Web of Conferences : proceedings proceedings 234, 01016 - (2020). doi:10.1051/epjconf/202023401016
Dipole operator constraints on composite Higgs models
2014
Flavour- and CP-violating electromagnetic or chromomagnetic dipole operators in the quark sector are generated in a large class of new physics models and are strongly constrained by measurements of the neutron electric dipole moment and observables sensitive to flavour-changing neutral currents, such as the $B\to X_s\gamma$ branching ratio and $\epsilon'/\epsilon$. After a model-independent discussion of the relevant constraints, we analyze these effects in models with partial compositeness, where the quarks get their masses by mixing with vector-like composite fermions. These scenarios can be seen as the low-energy limit of composite Higgs or warped extra dimensional models. We study diffe…