228,559 research outputs found
Is Cabibbo-Kobayasi-Maskawa Matrix Unitary?
First, we give summary of the present values of CKM matrix elements. Then, we
discuss whether CKM matrix is unitary or not, and how we can find out if it is
not unitary.Comment: 8 pages, 1 figur
Pion properties at finite density
In this talk, we report our recent work on the pion weak decay constant
(F_pi) and pion mass (m_pi) using the nonlocal chiral quark model with the
finite quark-number chemical potential (mu) taken into account. Considering the
breakdown of Lorentz invariance at finite density, the time and space
components are computed separately, and the corresponding results turn out to
be: F^t_pi = 82.96 MeV and F^s_pi = 80.29 MeV at mu_c ~ 320 MeV, respectively.
Using the in-medium Gell-Mann Oakes-Renner (GOR) relation, we show that the
pion mass increases by about 15% at mu_c.Comment: 5 pages, 2 figures, Talk given at the 4th Asia-Pacific Conference on
Few-Body Problems in Physics 2008 (APFB08), 19 ~ 23 Aug 2008, Depok,
Indonesi
Axial Anomaly and the Nucleon Spin
In this letter, we have taken a particular Lagrangian, which was introduced
to resolve U(1) problem, as an effective QCD Lagrangian, and have derived a
formula of the quark content of the nucleon spin. The difference between quark
content of the proton (\Delta\Sigma_p) and that of the neutron (\Delta\Sigma_n)
is evaluated by this formula. Neglecting the higher-order isospin corrections,
this formula can reduce to Efremov's results in the large N_c limit.Comment: (1) A few changes and corrections made following Referee. (2) The
difference between quark content of the proton (\Delta\Sigma_p) and that of
the neutron (\Delta\Sigma_n) is evaluated. Neglecting the higher-order
isospin corrections, this formula can reduce to Efremov's results in the
large N_c limi
Pentaquark in nuclear matter and hypernuclei
We study the properties of the in nuclear matter and
hypernuclei within the quark mean-field (QMF) model, which has been
successfully used for the description of ordinary nuclei and
hypernuclei. With the assumption that the non-strange mesons couple only to the
and quarks inside baryons, a sizable attractive potential of the
in nuclear matter is achieved as a consequence of the cancellation
between the attractive scalar potential and the repulsive vector potential. We
investigate the single-particle energies in light, medium, and heavy
nuclei. More bound states are obtained in hypernuclei in comparison
with those in hypernuclei.Comment: 16 pages, 5 figure
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