Search results for "radiative decay"
showing 10 items of 55 documents
η→π0γγdecay within a chiral unitary approach revisited
2008
In view of the recent experimental developments in η→π^(0)γ γ decay, and the fact that the Particle Data Group in the online edition of 2007 reports sizable changes of the radiative decay widths of vector mesons used as input in the theoretical calculations of E. Oset, J. R. Pelaez, and L. Roca [Phys. Rev. D 67, 073013 (2003)], a reevaluation of the decay width of the in this channel has been done, reducing its uncertainty by almost a factor of 2. The new input of the Particle Data Group is used, and invariant mass distributions and total widths are compared with the most recent results from the AGS and MAMI experiments, and preliminary ones of KLOE. The agreement of the theory with the AGS…
THE X(3872) AND OTHER X,Y,Z RESONANCES AS HIDDEN CHARM MESON-MESON MOLECULES
2011
We report on some ideas concerning the nature of the X(3872) resonance and the need for approximately equal charged and neutral components of $D \bar{D}^* +cc$. Then we discuss how some hidden charm states are obtained from the interaction between vector mesons with charm and can be associated to some of the charmonium-like X,Y,Z states. Finally we discuss how the nature of these states could be investigated through different types of radiative decay.
Measurement of the Ξ0→Λγ decay asymmetry and branching fraction
2004
In data taken with the NA48 experiment at the CERN SPS in 1999, 730 candidates of the weak radiative hyperon decay Ξ0→Λγ have been found with an estimated background of 58±8 events. From these events the Ξ0→Λγ decay asymmetry has been determined to α(Ξ0→Λγ)=-0.78±0.18stat±0.06 syst, which is the first evidence of a decay asymmetry in Ξ 0→Λγ. The branching fraction of the decay has been measured to be Br(Ξ0→Λγ)=(1.16±0.05 stat±0.06syst)×10-3. © 2004 Elsevier B.V. All rights reserved.
Observation of the Baryonic Flavor-Changing Neutral Current Decay Λb0→Λμ+μ-
2011
8 páginas, 2 figuras, 4 tablas.-- PACS numbers: 13.30.Ce, 12.15.Mm, 14.20.Mr.-- CDF Collaboration: et al.
Spectroscopy, leptonic decays and the nature of heavy quarkonia
2008
We examine the electronic width ratios of Upsilon resonances below the BBbar threshold by means of an effective (Cornell-type) QCD potential incorporating 1/m_b corrections obtained from a prior fit to the bottomonium spectrum. From our analysis we conclude that the Upsilon(2S) and Upsilon(3S) states should belong to the strong-coupling (nonperturbative) regime while the Upsilon(1S) state should belong to the weak-coupling (perturbative) regime, in agreement with a previous study based on radiative decays.
Dynamically generated resonances
2010
We study the radiative decay properties of the charmonium-like X, Y and Z mesons generated dynamically from vector meson-vector meson interaction in the framework of a unitarized hiddengauge formalism. In the present work we calculate the one- and two-photon decay widths of the hidden-charm Y (3940), Z(3930) (or X(3915)) and X(4160) mesons in the framework of the vector meson dominance formalism. We obtain good agreement with experiment in case of the two photon width of the X(3915) which we associate with the 2 + resonance that we find at 3922 MeV.
Measurement of the chi(b) (3 P) mass and of the relative rate of chi(b1) (1 P) and chi(b2) (1 P) production
2014
The production of $\chi_b$ mesons in proton-proton collisions is studied using a data sample collected by the LHCb detector, at centre-of-mass energies of $\sqrt{s}=7$ and $8$ TeV and corresponding to an integrated luminosity of 3.0 fb$^{-1}$. The $\chi_b$ mesons are identified through their decays to $\Upsilon(1S)\gamma$ and $\Upsilon(2S)\gamma$ using photons that converted to $e^+e^-$ pairs in the detector. The $\chi_b(3P)$ meson mass, and the relative prompt production rate of $\chi_{b1}(1P)$ and $\chi_{b2}(1P)$ mesons as a function of the $\Upsilon(1S)$ transverse momentum in the $\chi_b$ rapidity range 2.0< $y$<4.5, are measured. Assuming a mass splitting between the $\chi_{b1}(3P)$ an…
Search for excited leptons in proton-proton collisions ats=7 TeVwith the ATLAS detector
2012
The ATLAS detector is used to search for excited leptons in the electromagnetic radiative decay channel l* -> l gamma. Results are presented based on the analysis of pp collisions at a center-of ...
Lattice-constrained parametrizations of form factors for semileptonic and rare radiative B decays
1997
We describe the form factors for B to rho lepton neutrino and B to K* gamma decays with just two parameters and the two form factors for B to pi lepton neutrino with a further two or three parameters. The parametrizations are consistent with heavy quark symmetry, kinematic constraints and lattice results, which we use to determine the parameters. In addition, we test versions of the parametrizations consistent (or not) with light-cone sum rule scaling relations at q^2=0.
Radiative decays in charmonium beyond the p/m approximation
2020
We analyze the theoretical description of radiative decays in charmonium. We use an elementary emission decay model to build the most general electromagnetic transition operator. We show that accurate results for the widths can be obtained from a simple quark potential model reasonably fitting the spectroscopy if the complete form of the operator is used instead of its standard p/m approximation and the experimental masses are properly implemented in the calculation.