Latex 4 pages, 1 table, 2 figures. To appear in the proceedings of 10th Hellenic School and Workshops on Elementary Particle Physics and Gravity (Corfu 2010), Corfu, Greece, Aug 29 - Sep 19, 2010
We briefly review the limits on new interactions implied by electroweak precision data. Special attention is payed to the bounds on the Higgs boson mass. We also comment on the required cancellation among the new contributions to precisely measured electroweak observables in any Standard Model extension, if the new particles have to evade the indirect constraints on their couplings and masses but still remain at the LHC reach.
We present an update of the global fit of the Standard Model electroweak sector to latest experimental results. We include new kinematic top quark and $W$ boson mass measurements from the LHC, a $\sin^2θ^{\ell}_{\mathrm{eff}}$ result from the Tevatron, and a new evaluation of the hadronic contribution to $α(M_Z^2)$. We present tests of the internal consistency of the electroweak Standard Model and updated numerical predictions of key observables. The electroweak data combined with measurements of the Higgs boson coupling strengths and flavour physics observables are used to constrain parameter…
The oblique parameters $S$ and $T$ are calculated in a gauged unparticles model based on the electroweak group $SU(2)*U(1)$ and it's parameters space is constrained using electroweak precision measurements.
Improved Constraints on Z' Bosons from Electroweak Precision Data
我们分析了在低能下除了标准模型（SM）规范群之外，还具有额外U（1）规范对称性的各种模型，并对中性Z'玻色子的质量（M_Z'）和Z-Z'混合角（theta_ZZ'）施加了限制。精确的电弱数据强烈地限制θ_ZZ'到非常小的值，对于大多数模型，我们发现M_Z'的下限为1 TeV。在一种情况下，我们获得了比SM更好的拟合（尽管这在统计学上仅具有轻微的显著性），并且在90% C. L.处发现了弱上限。
We report on the status of an ongoing calculation of the NLO electroweak corrections to sequential polarized top quark decays $t(\uparrow) \to X_b +W^+ (\to \ell^+ +ν_\ell)$.
We study the type-II first-order electroweak phase transition and dark matter (DM) phenomenology in both real and complex singlet extensions of SM. In the real singlet extension with a $\mathbb{Z}_2$ symmetry, we show that the parameter regions favored by the phase transition suffer from strong constraints from DM direct detection so that only a negligible fraction ($f_{X}\sim 10^{-4}-10^{-5}$) of DM composed of the real singlet scalar can survive the LUX and XENON1T constraints. In the complex singlet $S$ case, we impose a $CP$ symmetry $S\to S^{*}$ to the scalar potential. The real component…
Two Higgs doublet models are attractive scenarios for physics beyond the Standard Model. In particular, lepton-specific manifestations remain contenders to explain the observed discrepancy between the anomalous magnetic moment of the muon $a_μ$ predicted within the Standard Model and recent observations at Fermilab and BNL. Dominant uncertainties that affect $a_μ$ have motivated the MUonE experiment to access the hadronic vacuum polarisation contribution that impacts $a_μ$ via elastic muon-electron scattering. In this work, we contrast the high precision that is achievable within the MUonE con…
Rare $B$, $D$ and $K$ decays provide interesting probes of the Standard Model (SM), with a potential sensitivity to New Physics (NP) higher than other, more common, decays. Their experimental measurement is challenging, and their theoretical interpretation requires a precise knowledge of QCD at low energies, in the non-perturbative (hadronic) regime. The various $b$, $c$, $s$ decays provide different types of tests of the Standard Model, which can be performed in different experimental settings and which may exhibit correlated deviations in models of New Physics.
We compute bounds on coefficients of effective operators in the Standard Model that can be inferred from observations of neutrino scattering by the COHERENT experiment. While many operators are bound extremely well by past experiments the full future data set from COHERENT will provide modest improvements for some operators.
While an additional scalar multiplet over and above the Standard Model can lead to a strong electroweak phase transition, depending on its quantum numbers, it also potentially confronts crucial constraints from theory and experiments. Should there exist more than one copy of such a multiplet, it is possible to predict that number from the requirements of a strong electroweak phase transition and agreement with the latest constraints. We aim to probe this specific issue in this study in the context of $N$ degenerate scalar triplets governed by a global O$(N)$ symmetry. We fold in important cons…
