نتایج جستجو برای: baryon mass
تعداد نتایج: 483501 فیلتر نتایج به سال:
The smallness of the baryon asymmetry in our universe is one of the greatest mysteries and may originate from some profound physics beyond the standard model. We investigate the Affleck-Dine baryogenesis in split supersymmetry, and find that the smallness of the baryon asymmetry is directly related to the hierarchy between the supersymmetry breaking squark/slepton masses and the weak scale. Put...
Exotic penta-quark baryon with strangeness +1, Θ, is studied in the QCD sum rule approach. We derive sum rules for the positive and negative parity baryon states with J = 1 2 and I = 0. It is found that the standard values of the QCD condensates predict a negative parity Θ of mass ≃ 1.5 GeV, while no positive parity state is found. We stress the roles of chiral-odd condensates in determining th...
A phenomenological analysis of lifetimes of bottom and charmed hadrons within the framework of the heavy quark expansion is performed. The baryon matrix element is evaluated using the bag model and the nonrelativistic quark model. We find that bottom-baryon lifetimes follow the pattern τ(Ωb) ' τ(Ξ − b ) > τ(Λb) ' τ(Ξ 0 b). However, neither the lifetime ratio τ(Λb)/τ(Bd) nor the absolute decay r...
We calculate the F/D ratios of spin-nonflip baryon vertex for an arbitrary number of color degrees of freedom Nc both in the non-relativistic quark model with the SU(6) spin-flavor symmetry and in the chiral soliton model with SU(3) flavor symmetry. We find that the spin-nonflip F/D ratio tends to −1 in the limit of Nc → ∞. We show that this leading value F/D = −1 of spin-nonflip baryon vertex ...
Within the QCD sum-rule approach in an external field, we calculate the baryon matrix element of isovector-scalar current, HB = 〈B|uu−dd|B〉/2MB, for octet baryons, which appears in the response of the correlator of baryon interpolating fields to a constant isovector-scalar external field. The sum rules are obtained for a general baryon interpolating field with an appropriate form for the phenom...
We have analyzed the properties of a sample of 33 groups and clusters of galaxies for which both optical and X-ray data were available in the literature. This sample was built to examine the baryon content and to check for trends over a decade in temperature down to 1 keV. We examine the relative contribution of galaxies and ICM to baryons in clusters through the gas-to-stellar mass ratio (Mgas...
T. Aaltonen, A. Abulencia, J. Adelman, T. Affolder, T. Akimoto, M. G. Albrow, S. Amerio, D. Amidei, A. Anastassov, K. Anikeev, A. Annovi, J. Antos, M. Aoki, G. Apollinari, T. Arisawa, A. Artikov, W. Ashmanskas, A. Attal, A. Aurisano, F. Azfar, P. Azzi-Bacchetta, P. Azzurri, N. Bacchetta, W. Badgett, A. Barbaro-Galtieri, V. E. Barnes, B. A. Barnett, S. Baroiant, V. Bartsch, G. Bauer, P.-H. Beauc...
I report the current status on the determinations of the baryon fractions and dynamical/lensing masses of galaxy clusters as well as the σ T relationship, making use of all the published data in literature which include 304 measurements for baryon fractions, 320/21 data points for masses of intracluster gas/cluster galaxies, (152+228)/72 data points for cluster masses derived from X-ray emittin...
There is a striking suppression of the cross section for production of octet baryons in e+e− annihilation, as the mass of the produced hadron increases. We present a simple parametrization for the fragmentation functions into octet baryons guided by two input models: the SU(3) flavor symmetry part is given by a quark-diquark model, and the baryon mass suppression part is inspired by the string ...
We study the physics with finite nuclear density in the framework of AdS/QCD with holographic baryon field included. Based on a mean field type approach, we introduce the nucleon density as a bi-fermion condensate of the lowest mode of the baryon field and calculate the density dependence of the chiral condensate, the nucleon mass and the ρ-meson-nucleon coupling. We observe that the chiral con...
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