1,237 research outputs found
Helicity conservation in inclusive nonleptonic decay B to VX: Test of long-distance final state interaction
The polarization measurement in the inclusive B decay provides us with a
simple test of how much the long-distance final-state interaction takes place
as the energy of the observed meson varies in the final state. We give the
expectation of the perturbative QCD for the energy dependence of the helicity
fractions in a semiquantitative form. Experiment will tell us for which decay
processes the perturbative calculation should be applicable.Comment: 15 pages in Revtex with 3 figures embedde
The Isovector Quadrupole-Quadrupole Interaction Used in Shell Model Calculations
An interaction is used
in a shell model calculation for . Whereas for the state
is two-fold degenerate, introducing a negative causes an `isovector'
state to come down to zero energy at and an triplet
() to come down to zero energy at . These are
undesirable properties, but a large negative is apparently needed to fit
the energy of the isovector giant quadrupole resonance.Comment: 12 pages, revtex, 2 figures (available on request
Helicity conservation and factorization-suppressed charmless B decays
Toward the goal of extracting the weak angle alpha, the decay B^0/B^0-bar to
a_0^{+/-}pi^{-/+} was recently measured. The decay B^0 to a_0^+pi^- is not only
forbidden in the factorization limit of the tree interaction, but also strongly
suppressed for the penguin interaction if short-distance QCD dominates. This
makes extraction of alpha very difficult from a^{+/-}\pi^{-/+}. We examine the
simlar factorization-suppressed decays, in particular, B^0\to b_1^+pi^-. The
prospect of obtaining alpha is even less promising with b_1^{+/-}pi^{-/+}. To
probe how well the short-distance dominance works, we emphasize importance of
testing helicity conservation in the charmless B decays with spins.Comment: The version to appear in Phys. Rev. D after minor alteration
Final-state interaction and s-quark helicity conservation in B -> J/psi K*
The Section of charm quark spin conservation is deleted since it involves
more dynamical assumptions than previously stated. A few comments are added in
view of new experimental results.Comment: To replace the earlier version of hep-ph/0106354. Minor additions and
one deletion with no change in the main argument nor the conclusio
HPV-18 transformed cells fail to arrest in G1 in response to quercetin treatment
Previous work with primary human keratinocytes demonstrated that quercetin, a potent mutagen found in high levels in bracken fern (Pteridium aquilinum), arrested cells in G1 with concomitant elevation of the cyclin-dependent kinase inhibitor (cdki) p27Kip1. Expression of the human papillomavirus type 16 (HPV-16) E6 and E7 oncoproteins, under transcriptional control of a heterologous promoter, in transformed keratinocytes failed to abrogate this arrest [Beniston, R., Campo, M.S., 2003. Quercetin elevates p27(Kip1) and arrests both primary and HPV-16 E6/E7 transformed human keratinocytes in G1. Oncogene 22, 5504–5514]. Given the link between papillomavirus infection, bracken fern in the diet and cancer of the oesophagus in humans, we wished to investigate further whether cells transformed by the whole genome of HPV-16 or HPV-18, with E6 and E7 under the transcriptional control of their respective homologous promoters, would be similarly arrested in G1 by quercetin. In agreement with earlier work, quercetin arrested HPV-16 transformed cells in G1 with an increase in the cyclin-dependent kinase inhibitor p27Kip1. However, HPV-18 transformed cells did not arrest after quercetin treatment. The failure of HPV-18 transformed cells to arrest in G1 was linked to the up-regulation of the HPV-18 long control region (LCR) by quercetin, maintaining high expression of the viral transforming proteins. Transcriptional up-regulation of the HPV-18 LCR was mediated by a “quercetin responsive element” homologous to the one identified previously in the bovine papillomavirus type 4 (BPV-4) LCR
Looking into the matter of light-quark hadrons
In tackling QCD, a constructive feedback between theory and extant and
forthcoming experiments is necessary in order to place constraints on the
infrared behaviour of QCD's \beta-function, a key nonperturbative quantity in
hadron physics. The Dyson-Schwinger equations provide a tool with which to work
toward this goal. They connect confinement with dynamical chiral symmetry
breaking, both with the observable properties of hadrons, and hence provide a
means of elucidating the material content of real-world QCD. This contribution
illustrates these points via comments on: in-hadron condensates; dressed-quark
anomalous chromo- and electro-magnetic moments; the spectra of mesons and
baryons, and the critical role played by hadron-hadron interactions in
producing these spectra.Comment: 11 pages, 7 figures. Contribution to the Proceedings of "Applications
of light-cone coordinates to highly relativistic systems - LIGHTCONE 2011,"
23-27 May, 2011, Dallas. The Proceedings will be published in Few Body
System
Masses of ground and excited-state hadrons
We present the first Dyson-Schwinger equation calculation of the light hadron
spectrum that simultaneously correlates the masses of meson and baryon ground-
and excited-states within a single framework. At the core of our analysis is a
symmetry-preserving treatment of a vector-vector contact interaction. In
comparison with relevant quantities the
root-mean-square-relative-error/degree-of freedom is 13%. Notable amongst our
results is agreement between the computed baryon masses and the bare masses
employed in modern dynamical coupled-channels models of pion-nucleon reactions.
Our analysis provides insight into numerous aspects of baryon structure; e.g.,
relationships between the nucleon and Delta masses and those of the
dressed-quark and diquark correlations they contain.Comment: 25 pages, 7 figures, 4 table
Light Front Formalism for Composite Systems and Some of Its Applications in Particle and Relativistic Nuclear Physics
Light front formalism for composite systems is presented. Derivation of
equations for bound state and scattering problems are given. Methods of
constructing of elastic form factors and scattering amplitudes of composite
particles are reviewed. Elastic form factors in the impulse approximation are
calculated. Scattering amplitudes for relativistic bound states are
constructed. Some model cases for transition amplitudes are considered. Deep
inelastic form factors (structure functions) are expressed through light front
wave functions. It is shown that taking into account of transverse motion of
partons leads to the violation of Bjorken scaling and structure functions
become square of transverse momentum dependent. Possible explanation of the
EMC-effect is given. Problem of light front relativization of wave functions of
lightest nuclei is considered. Scaling properties of deuteron, and
light front wave functions are checked in a rather wide energy range.Comment: Review paper, Submitted to Phys. Rep., 89 pages, 23 figure
Large-space shell-model calculations for light nuclei
An effective two-body interaction is constructed from a new Reid-like
potential for a large no-core space consisting of six major shells and is used
to generate the shell-model properties for light nuclei from =2 to 6. (For
practical reasons, the model space is partially truncated for =6.) Binding
energies and other physical observables are calculated and compare favorably
with experiment.Comment: prepared using LaTex, 21 manuscript pages, no figure
A Complete Theory of Grand Unification in Five Dimensions
A fully realistic unified theory is constructed, with SU(5) gauge symmetry
and supersymmetry both broken by boundary conditions in a fifth dimension.
Despite the local explicit breaking of SU(5) at a boundary of the dimension,
the large size of the extra dimension allows precise predictions for gauge
coupling unification, alpha_s(M_Z) = 0.118 \pm 0.003, and for Yukawa coupling
unification, m_b(M_Z) = 3.3 \pm 0.2 GeV. A complete understanding of the MSSM
Higgs sector is given; with explanations for why the Higgs triplets are heavy,
why the Higgs doublets are protected from a large tree-level mass, and why the
mu and B parameters are naturally generated to be of order the SUSY breaking
scale. All sources of d=4,5 proton decay are forbidden, while a new origin for
d=6 proton decay is found to be important. Several aspects of flavor follow
from an essentially unique choice of matter location in the fifth dimension:
only the third generation has an SU(5) mass relation, and the lighter two
generations have small mixings with the heaviest generation. The entire
superpartner spectrum is predicted in terms of only two free parameters. The
squark and slepton masses are determined by their location in the fifth
dimension, allowing a significant experimental test of the detailed structure
of the extra dimension. Lepton flavor violation is found to be generically
large in higher dimensional unified theories with high mediation scales of SUSY
breaking. In our theory this forces a common location for all three neutrinos,
predicting large neutrino mixing angles. Rates for mu -> e gamma, mu -> e e e,
mu -> e conversion and tau -> mu gamma are larger in our theory than in
conventional 4D supersymmetric GUTs. Proposed experiments probing mu -> e
transitions will probe the entire interesting parameter space of our theory.Comment: 51 pages, late
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