Search results for "Mixing"

Searching for new physics in bottomonium decays

2005

Heavy quarkonium decays can be used to search for New Physics beyond the Standard Model. In particular, a light Higgs boson could induce a slight (but observable) lepton universality breaking in Upsilon decays. In fact, current experimental data from CLEO presented in this Conference seem to point out to this direction within experimental accuracy. Moreover, LEP constraints on a light Higgs mass can be evaded by different models (like MSSM with a CPV Higgs sector) as shown in this Conference. We also consider spectroscopic consequences stemming from a possible mixing between Higgs and bottomonium states leading to discrepancies with the SM expectations (e.g. hyperfine splittings).

2011

Theoretical approaches that use one-body densities as dynamical variables, such as Hartree-Fock or the density functional theory (DFT), break isospin symmetry both explicitly, by virtue of charge-dependent interactions, and spontaneously. To restore the spontaneously broken isospin symmetry, we implemented the isospin-projection scheme on top of the Skyrme-DFT approach. This development allows for consistent treatment of isospin mixing in both ground and exited nuclear states. In this study, we apply this method to evaluate the isospin impurities in ground states of even-even and odd-odd N~Z nuclei. By including simultaneous isospin and angular-momentum projection, we compute the isospin-br…

Neutrino mass in supersymmetry

2009

10 páginas, 8 figuras.-- El PDF es la versión pre-print (arXiv:0911.3103v1).-- Trabajo presentado al SUSY09: 7th International Conference on Supersymmetry and the Unification of Fundamental Interactions.

Abnormal isospin violation and a0−f0 mixing in the Ds+→π+π0a0(980)(f0(980)) reactions

2017

We have chosen the reactions ${D}_{s}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{0}{a}_{0}(980)({f}_{0}(980))$ investigating the isospin violating channel ${D}_{s}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{0}{f}_{0}(980)$. The reaction was chosen because by varying the ${\ensuremath{\pi}}^{0}{a}_{0}(980)({f}_{0}(980))$ invariant mass one goes through the peak of a triangle singularity emerging from ${D}_{s}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\overline{K}}^{*}K$, followed by ${\overline{K}}^{*}\ensuremath{\rightarrow}\overline{K}{\ensuremath{\pi}}^{0}$ and the further merging of $K\overline{K}$ to produce the ${a}_{0}(980)$ …

Measurements of charm mixing and CP violation using D0→K±π∓ decays

2017

Measurements of charm mixing and CP violation parameters from the decay-time-dependent ratio of D0→K+π− to D0→K−π+ decay rates and the charge-conjugate ratio are reported. The analysis uses B¯¯¯¯→D∗+μ−X, and charge-conjugate decays, where D∗+→D0π+, and D0→K∓π±. The pp collision data are recorded by the LHCb experiment at center-of-mass energies s√ = 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb−1. The data are analyzed under three hypotheses: (i) mixing assuming CP symmetry, (ii) mixing assuming no direct CP violation in the Cabibbo-favored or doubly Cabibbo-suppressed decay amplitudes, and (iii) mixing allowing either direct CP violation and/or CP violation in the superpos…

Updated determination of D0–D¯0 mixing and CP violation parameters with D0→K+π− decays

2018

We report measurements of charm-mixing parameters based on the decay-time-dependent ratio of D0→K+π- to D0→K-π+ rates. The analysis uses a data sample of proton-proton collisions corresponding to an integrated luminosity of 5.0  fb-1 recorded by the LHCb experiment from 2011 through 2016. Assuming charge-parity (CP) symmetry, the mixing parameters are determined to be x′2=(3.9±2.7)×10-5, y′=(5.28±0.52)×10-3, and RD=(3.454±0.031)×10-3. Without this assumption, the measurement is performed separately for D0 and D¯0 mesons, yielding a direct CP-violating asymmetry AD=(-0.1±9.1)×10-3, and magnitude of the ratio of mixing parameters 1.00<|q/p|<1.35 at the 68.3% confidence level. All results incl…

Search for Violation ofCPTand Lorentz Invariance inBs0Meson Oscillations

2015

We present the first search for CPT-violating effects in the mixing of B-s(0) mesons using the full Run II data set with an integrated luminosity of 10.4 fb(-1) of proton-antiproton collisions coll ...

Triangle singularity enhancing isospin violation in $D_s^ + \to {\pi ^ + }{\pi ^0}{f_0}(980)$ and $\overline B _s^0 \to J/\psi {\pi ^0}{f_0}(980)$ de…

2019

We investigate isospin violation in the and reactions, which proceed via a triangle mechanism. We show that the mechanism develops a singularity around the π 0 f 0 (980) or π 0 a0 (980) invariant mass of 1420 MeV where the π 0 f 0 and π 0 a0 decay modes are magnified and also the ratio of π 0 f0 to π 0 a0 production, stressing the role of the triangle singularities as a factor to enhance isospin violation. The measurement of these reactions would bring further information into the role of triangle singularities in isospin violation and the a 0 – f 0 mixing in particular and shed further light into the nature of the low lying scalar mesons.

Measurement of the SemileptonicCPAsymmetry inB0-B¯0Mixing

2015

The semileptonic $CP$ asymmetry in $B^0-\overline{B}{}^0$ mixing, $a_{\rm sl}^d$, is measured in proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb$^{-1}$, recorded by the LHCb experiment. Semileptonic $B^0$ decays are reconstructed in the inclusive final states $D^-\mu^+$ and $D^{*-}\mu^+$, where the $D^-$ meson decays into the $K^+\pi^-\pi^-$ final state, and the $D^{*-}$ meson into the $\overline{D}{}^0(\rightarrow K^+\pi^-)\pi^-$ final state. The asymmetry between the numbers of $D^{(*)-}\mu^+$ and $D^{(*)+}\mu^-$ decays is measured as a function of the decay time of the $B^0$ mesons. The $CP$ asymmetry is measured to be $a_{\rm sl}^d = (-0.02 \pm 0.19 \pm…

Pseudoscalar Transition Form Factors from Rational Approximants

2014

The $\pi^0$, $\eta$, and $\eta^\prime$ transition form factors in the space-like region are analyzed at low and intermediate energies in a model-independent way through the use of rational approximants. Slope and curvature parameters as well as their values at infinity are extracted from experimental data. These results are suited for constraining hadronic models such as the ones used for the hadronic light-by-light scattering piece of the anomalous magnetic moment of the muon, and for the mixing parameters of the $\eta - \eta^\prime$ system.