نتایج جستجو برای: baryon mass
تعداد نتایج: 483501 فیلتر نتایج به سال:
The possibility that the observed cosmological baryon density might be a consequence of non-perturbative dynamics at the electroweak phase transition is one of the most exciting topics at the interface of particle physics and cosmology. However, determining the viability of electroweak baryogenesis in (minimal extensions of) the standard model requires knowledge of the equilibrium behavior of t...
Motivated by the recent discovery of the exotic S = +1 narrow baryon resonance Θ+ at 1540 MeV, with quark content uud ds̄, we conjecture the existence of its anti-charmed analogue Θcwith quark content uuddc̄, and compute its likely properties. We rely on the recently constructed model of a novel kind of a pentaquark with an unusual color structure which provides a good approximation to the Θ+ mas...
The comprehensive analyses are presented in the model with the inverted mass hierarchy for neutrinos, which follows from a geometrical structure of a (1+5) dimensional space-time where two extra dimensions are compactified on the T2/Z3 orbifold. The model gives two large lepton flavor mixings due to the S3 structure in the (1+5) dimensional space-time. It also predicts the lightest neutrino mas...
We explore the possibility that QCD may undergo a phase transition as a function of the strange quark mass. This would hint towards models with " spontaneous color symmetry breaking " in the vacuum. For two light quark flavors we classify possible colored quark-antiquark, diquark and gluon condensates that are compatible with a spectrum of integer charged states and conserved isospin and baryon...
A search for charmed baryons decaying to D(0)p reveals two states: the Lambdac(2880)+ baryon and a previously unobserved state at a mass of [2939.8+/-1.3(stat)+/-1.0(syst)] MeV/c2 and with an intrinsic width of [17.5+/-5.2(stat)+/-5.9(syst)] MeV. Consistent and significant signals are observed for the K(-)pi(+) and K(-)pi(+)pi(-)pi(+) decay modes of the D0 in 287 fb(-1) annihilation data record...
Baryon-baryon bound states in the strangeness S = −2, S = −3, and S = −4 sectors are considered. In particular, the dependence of the corresponding binding energies on the quark mass (or equivalently the pion mass) is explored in the framework of chiral effective field theory, in order to connect with current lattice QCD calculations. For a bound state in the ΞΞ S0 channel, predicted by our lea...
Title of dissertation: Lattice QCD Simulations of Baryon Spectra and Development of Improved Interpolating Field Operators Ikuro Sato, Doctor of Philosophy, 2005 Dissertation directed by: Professor Stephen J. Wallace Department of Physics Large sets of baryon interpolating field operators are developed for use in lattice QCD studies of baryons with zero momentum. Because of the discretization o...
We analyze the quark mass dependence of the Roper mass to one-loop order in relativistic baryon chiral perturbation theory. The loop integrals are evaluated using infrared regu-larization which preserves chiral symmetry and establishes a chiral counting scheme. The derived chiral expansion of the Roper mass may prove useful for chiral extrapolations of lattice data. For couplings of natural siz...
The origin of the baryon asymmetry of the Universe is one of the key open questions to be addressed in particle physics and cosmology. Assuming a negligible initial baryon asymmetry, its dynamical production can happen in presence of non-conservation of the baryon and/or lepton number, violation of the C and CP symmetries and out-of-equilibrium conditions. Leptogenesis is a mechanism, proposed ...
We investigate the gas mass function of clusters of galaxies to measure the density fluctuation spectrum on cluster scales. The baryon abundance confined in rich clusters is computed from the gas mass function and compared with the mean baryon density in the universe which is predicted by the Big Bang Nucleosynthesis. This baryon fraction and the slope of the gas mass function put constraints o...
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