2,228 research outputs found
Electroweak Physics
The status of precision electroweak measurements as of summer 2002 is
reviewed. The recent results on the anomalous magnetic moment of the muon and
on neutrino-nucleon scattering are discussed. Precision results on the
electroweak interaction obtained by the experiments at the SLC, LEP and
TEVATRON colliders are presented. The experimental results are compared with
the predictions of the minimal Standard Model and are used to constrain its
parameters, including the mass of the Higgs boson. The final LEP results on the
direct search for the Higgs boson of the Standard Model are presented.Comment: Plenary talk presented at the 31st ICHEP, Amsterdam, The Netherlands,
July 24-31, 200
Search for top squark pair production using dilepton final states in pp collision data collected at √s =13TeV
Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UA
Nonresonant searches for axion-like particles in vector boson scattering processes at the LHC
We propose a new search for Axion-Like Particles (ALPs), targeting Vector
Boson Scattering (VBS) processes at the LHC. We consider nonresonant ALP-mediated
VBS, where the ALP participates as an off-shell mediator. This process occurs whenever
the ALP is too light to be produced resonantly, and it takes advantage of the derivative
nature of ALP interactions with the electroweak Standard Model bosons. We study the
production of ZZ, Zγ, W ±γ, W ±Z and W ±W ± pairs with large diboson invariant masses
in association with two jets. Working in a gauge-invariant framework, upper limits on
ALP couplings to electroweak bosons are obtained from a reinterpretation of Run 2 public
CMS VBS analyses. The constraints inferred on ALP couplings to ZZ, Zγ and W ±W ±
pairs are very competitive for ALP masses up to 100 GeV. They have the advantage of
being independent of the ALP coupling to gluons and of the ALP decay width. Simple
projections for LHC Run 3 and HL-LHC are also calculated, demonstrating the power of
future dedicated analyses at ATLAS and CMS
Vector form factor of the pion : A model-independent approach
We study a model-independent parameterization of the vector pion form factor
that arises from the constraints of analyticity and unitarity. Our description
should be suitable up to s^(1/2) ~ 1.2 GeV and allows a model-independent
determination of the mass of the rho(770) resonance. We analyse the
experimental data on tau^- -> pion^- pion^0 nu_tau and e^+ e^- -> pion^+ pion^-
in this framework, and its consequences on the low-energy observables worked
out by chiral perturbation theory. An evaluation of the two pion contribution
to the anomalous magnetic moment of the muon, a_{mu}, and to the fine structure
constant, alpha(M_Z^2), is also performed.Comment: 5 pages, 2 figures. To appear in the proceedings of the High-Energy
Physics International Conference on Quantum Chromodynamics QCD02, Montpellier
(France), 2-9 July (2002
Supersymmetric two-loop contributions to the anomalous magnetic moment of the muon
Recent results of two interesting classes of supersymmetric two-loop
contributions to (g-2)_mu are presented. Two-loop diagrams involving a closed
sfermion loop can amount to 5*10^{-10} or almost one standard deviation of the
current experimental uncertainty, and two-loop diagrams with a closed
chargino/neutralino loop can be similarly large. The dependence of these two
classes on the unknown supersymmetric parameters and the sensitivity on
existing experimental constraints on the parameter space are quite different.
We also comment on the calculational techniques, in particular the large mass
expansion and the treatment of gamma_5 and the epsilon-tensor.Comment: 5 pages, Talk at Loops & Legs 2004, DESY Workshop on Elementary
Particle Theory in Zinnowitz/Usedo
Model-dependent radiative corrections to tau- -> pi- pi0 nu revisited
The long-distance electromagnetic radiative corrections to tau- -> pi- pi0 nu
are re-evaluated. A meson dominance model is used to describe the emission of
real photons in this decay. Results obtained for the hadronic spectrum and the
decay rate in photon inclusive reactions are compared with previous
calculations based on the chiral resonance theory. Independent tests in tau ->
pi pi nu gamma that can help to validate the predictions of one of the two
models are briefly discussed.Comment: 5 pages, 4 figures, talk given by GLC at the 9th International
Workshop on Tau Lepton Physics, Pisa (Italy), september 200
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