Zobrazeno 1 - 10
of 37
pro vyhledávání: '"Yamagishi, Hidenaga"'
Autor:
Yamagishi, Hidenaga, Zahed, Ismail
In the absence of nucleons, we use partial wave unitarity, to show that the chiral expansion parameter must be close to $p^2/4\pi f_{\pi}^2$ rather than $p^2/16\pi^2 f_{\pi}^2$ as previously suggested, where $p$ is a typical pion momentum and $f_{\pi
Externí odkaz:
http://arxiv.org/abs/hep-ph/9802260
Publikováno v:
Nucl.Phys. A638 (1998) 495c-498c
The electromagnetic emission rates at SPS energies satisfy spectral constraints in leading order in the pion and nucleon densities. These constraints follow from the strictures of broken chiral symmetry. We saturate these constraints using available
Externí odkaz:
http://arxiv.org/abs/hep-ph/9802256
Autor:
Yamagishi, Hidenaga, Zahed, Ismail
Publikováno v:
Phys.Rept. 398 (2004) 245-252
We find that QCD in covariant gauge yields zero for the topological susceptibility, even at the nonperturbative level. The result is derived in two ways, one using translational invariance, and the other using the BRST Hamiltonian. Comparison with th
Externí odkaz:
http://arxiv.org/abs/hep-th/9709125
Publikováno v:
Phys.Rev. D57 (1998) 1703-1714
We discuss an on-shell approach to pion-nucleon physics that is consistent order by order in a $1/f_{\pi}$ expansion with the chiral reduction formula, crossing, and relativistic unitarity. A number of constraints between the on-shell low-energy para
Externí odkaz:
http://arxiv.org/abs/hep-ph/9707399
Publikováno v:
Phys.Rev.D56:5605-5617,1997
We extend our recent analysis of the dilepton and photon emission rates to the case of finite temperature and baryon density, within the context of a density expansion. To leading order, the effects of the baryon density are assessed using data (phot
Externí odkaz:
http://arxiv.org/abs/hep-ph/9704414
Publikováno v:
Phys.Lett. B384 (1996) 255-262
We analyze the dilepton and photon emission rates from a hadronic gas using chiral reduction formulas and a virial expansion. The emission rates are reduced to pertinent vacuum correlation functions, most of which can be assessed from experiment. Our
Externí odkaz:
http://arxiv.org/abs/hep-ph/9603290
The pion-nucleon sigma term is shown to be equal to the Goldberger-Treiman discrepancy at tree level. Its value estimated this way is very sensitive to the pion-nucleon coupling constant g_{pi NN}. This relation, when combined with the pion-nucleon S
Externí odkaz:
http://arxiv.org/abs/hep-ph/9512233
Autor:
Yamagishi, Hidenaga, Zahed, Ismail
The non-perturbative implications of BRST quantization are examined for $\theta$ vacua and related issues. Strong CP violation is shown to be absent for QCD in the BRST formalism. Previous evidence for CP violation is reexamined, and much of it is fo
Externí odkaz:
http://arxiv.org/abs/hep-ph/9507296
Publikováno v:
Nucl.Phys. A615 (1997) 305-324
The master formula approach to chiral symmetry breaking is used to analyze the phase shifts for $\pi\pi$ scattering in the elastic region. The results are in excellent agreement with the data for the phase shifts up to the K-K bar threshold. Our anal
Externí odkaz:
http://arxiv.org/abs/hep-ph/9505330
Autor:
YAMAGISHI, HIDENAGA, ZAHED, ISMAIL
Publikováno v:
Annals Phys.247:292-413,1996
We derive a master formula for chiral $SU(2)\times SU(2)$ breaking, based on the Veltman-Bell equations and the Peierls-Dyson relation. Our approach does not rely on the use of the soft pion limit or an expansion around the chiral limit, and yields e
Externí odkaz:
http://arxiv.org/abs/hep-ph/9503413