Phenomenological applications in CP-violating systems in the SM and beyond
El coneixement actual sobre l'estructura de la matèria és el resultat d'un enorme esforç experimental i teòric. El nostre Univers es compon de partícules elementals governades per les quatre forces fonamentals: gravitatòries, febles, electromagnètiques i fortes. El model estàndard (SM) de la física de partícules és la descripció teòrica més senzilla de com es relacionen aquestes partícules i forces, excepte la força gravitatòria. Al llarg dels anys, el SM ha estat capaç d'explicar totes les dades experimentals amb gran precisió, culminant en 2012 amb el descobriment del bosó de Higgs amb una massa de 125 GeV. La seua elegància, simplicitat i alta predictibilitat han convertit el SM en el mi…
Updated Standard Model Prediction for ε′/ε
Abstract A recent lattice evaluation of e ′ / e , finding a 2.1 σ deviation from the experimental value, has revived the old debate about a possible e ′ / e anomaly. The unfounded claims of a too low Standard Model prediction are based on incorrect estimates that neglect the long-distance re-scattering of the final pions in K → 2 π . In view of the current situation, we have recently updated the Standard Model calculation, including all known short- and long-distance contributions. Our result, Re ( e ′ / e ) = ( 15 ± 7 ) ⋅ 10 − 4 [H. Gisbert and A. Pich, “Direct CP violation in K 0 → π π : Standard Model Status”, Rept. Prog. Phys. 81 (2018) no. 7, 076201 arXiv:1712.06147 [hep-ph] .], is in …
Improved bounds on heavy quark electric dipole moments
New bounds on the electric dipole moment (EDM) of charm and bottom quarks are derived using the stringent limits on their chromo-EDMs. The new limits, $|d_c|<1.5\times10^{-21}\:e\,\text{cm}$ and $|d_b|< 1.2\times 10^{-20}\:e\,\text{cm}$, improve the previous ones by about three orders of magnitude. These indirect bounds have implications for different models of new physics, including two-Higgs-doublet, leptoquarks, and supersymmetry models.
Isospin-breaking contributions to ε ′ / ε
Abstract We present an updated analysis of isospin-violating corrections to ε ′/ε in the framework of chiral perturbation theory, taking advantage of the currently improved knowledge on quark masses and nonperturbative parameters. The role of the different ingredients entering into the analysis is carefully assessed. Our final result is Ω eff = 0.110 − 0.088 + 0.090 [1].
Direct CP violation in ${K^0\to\pi\pi}$ : Standard Model Status
In 1988 the NA31 experiment presented the first evidence of direct CP violation in the $K^0\to\pi\pi$ decay amplitudes. A clear signal with a $7.2\,\sigma$ statistical significance was later established with the full data samples from the NA31, E731, NA48 and KTeV experiments, confirming that CP violation is associated with a $\Delta S=1$ quark transition, as predicted by the Standard Model. However, the theoretical prediction for the measured ratio $\varepsilon'/\varepsilon$ has been a subject of strong controversy along the years. Although the underlying physics was already clarified in 2001, the recent release of improved lattice data has revived again the theoretical debate. We review t…