Search results for "MESONS"
showing 10 items of 131 documents
Averages of $b$-hadron, $c$-hadron, and $\tau$-lepton properties as of summer 2016
2017
This article reports world averages of measurements of $b$-hadron, $c$-hadron, and $\tau$-lepton properties obtained by the Heavy Flavor Averaging Group using results available through summer 2016. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, \CP~violation parameters, parameters of semileptonic decays and CKM matrix elements.
Production of π0 and η mesons up to high transverse momentum in pp collisions at 2.76 TeV
2017
The invariant differential cross sections for inclusive π0 and η mesons at midrapidity were measured in pp collisions at √s = 2.76 TeV for transverse momenta 0.4 < pT < 40 GeV/c and 0.6 < pT < 20 GeV/c, respectively, using the ALICE detector. This large range in pT was achieved by combining various analysis techniques and different triggers involving the electromagnetic calorimeter (EMCal). In particular, a new single-cluster, shower-shape based method was developed for the identification of highpT neutral pions, which exploits that the showers originating from their decay photons overlap in the EMCal. Above 4 GeV/c, the measured cross sections are found to exhibit a similar power-law behav…
Measurement of matter-antimatter differences in beauty baryon decays
2017
Differences in the behaviour of matter and antimatter have been observed in $K$ and $B$ meson decays, but not yet in any baryon decay. Such differences are associated with the non-invariance of fundamental interactions under the combined charge-conjugation and parity transformations, known as $C\!P$ violation. Using data from the LHCb experiment at the Large Hadron Collider, a search is made for $C\!P$-violating asymmetries in the decay angle distributions of $\Lambda^0_b$ baryons decaying to $p\pi^-\pi^+\pi^-$ and $p\pi^-K^+K^-$ final states. These four-body hadronic decays are a promising place to search for sources of $C\!P$ violation both within and beyond the Standard Model of particle…
Complex-mass renormalization in chiral effective field theory
2009
We consider a low-energy effective field theory of vector mesons and Goldstone bosons using the complex-mass renormalization. As an application we calculate the mass and the width of the $\rho$ meson.
A covariant constituent-quark formalism for mesons
2014
Using the framework of the Covariant Spectator Theory (CST) [1] we are developing a covariant model formulated in Minkowski space to study mesonic structure and spectra. Treating mesons as effective $q\bar{q}$ states, we focused in [2] on the nonrelativistic bound-state problem in momentum space with a linear confining potential. Although integrable, this kernel has singularities which are difficult to handle numerically. In [2] we reformulate it into a form in which all singularities are explicitely removed. The resulting equations are then easier to solve and yield accurate and stable solutions. In the present work, the same method is applied to the relativistic case, improving upon the r…
A measurement of the b baryon lifetime
1992
In 451 000 hadronic Z0 decays, recorded with the ALEPH detector at LEP, the yields of lambdal- and lambdal+ combinations are measured. Semileptonic decays of b baryons result in a signal of 122 +/- 18(stat.)+22/-23(syst.) lambdal- combinations. From a fit to the impact parameter distribution of the leptons in the lambdal- sample, the lifetime of b baryons is measured to be 1.12+0.32/-0.29(stat.) +/- 0.16(syst.) ps.
Precision measurement of the D*(0) decay branching fractions
2015
WOS: 000349437800001
Tests on the molecular structure of f(2)(1270), f(2)'(1525) from psi(nS) and Upsilon(nS) decays
2013
Based on previous studies that support the vector-vector molecular structure of the f(2)'(1270), f 2 (1525), _ K * 0 2 (1430), f0(1370) and f0(1710) resonances, we make predictions for the.(2S) decay into.(f) f2(1270),.(f) f 2 (1525), K* 0 (892) _ K * 0 2 (1430) and the radiative decay of.(1S),.(2S),.(2S) into.f2(1270),.f 2 (1525),.f0(1370),.f0(1710). Agreement with experimental data is found for three available ratios, without using free parameters, and predictions are done for other cases.
ϕ meson width in the medium from proton induced ϕ production in nuclei
2004
We perform calculations for the production of $\phi$ mesons in nuclei at energies just above threshold and study the $A$ dependence of the cross section. We use results for the $\phi$ selfenergy in the medium obtained within a chiral unitary approach. We find a strong $A$ dependence which is tied to the distortion of the incident proton and to the absorption of the $\phi$ in its way out of the nucleus. The effect of this latter process reduces the cross section in about a factor two in heavy nuclei proving that the $A$ dependence of the cross section bears valuable information on the $\phi$ width in the nuclear medium. Calculations are done for energies which are accessible in an experiment…
Topological structure of dense hadronic matter
2007
8 pages, 4 figures.-- ISI Article Identifier: 000244425500052.