2,944 research outputs found
Lepton masses and mixing without Yukawa hierarchies
We investigate the neutrino masses and mixing patten in a version of the
model with one extra exotic charged
lepton per family as introduced by Ozer. It is shown that an extended scalar
sector, together with a discrete symmetry, is able to reproduce a
consistent lepton mass spectrum without a hierarchy in the Yukawa coupling
constants, the former as a carefull balance between one universal see-saw and
two radiative mechanisms.Comment: 7 pages, 2 figures, accepted for publication in Phys. Rev. D
A q-Deformed Schr\"odinger Equation
We found hermitian realizations of the position vector , the angular
momentum and the linear momentum , all behaving like
vectors under the algebra, generated by and . They are
used to introduce a -deformed Schr\" odinger equation. Its solutions for the
particular cases of the Coulomb and the harmonic oscillator potentials are
given and briefly discussed.Comment: 14 pages, latex, no figure
A PBIL for load balancing in network coding based multicasting
One of the most important issues in multicast is how to achieve a balanced traffic load within a communications network. This paper formulates a load balancing optimization problem in the context of multicast with network coding and proposes a modified population based incremental learning (PBIL) algorithm for tackling it. A novel probability vector update scheme is developed to enhance the global exploration of the stochastic search by introducing extra flexibility when guiding the search towards promising areas in the search space. Experimental results demonstrate that the proposed PBIL outperforms a number of the state-of-the-art evolutionary algorithms in terms of the quality of the best solution obtained
The Narrow Pentaquark As The First Non-planar Hadron With the Diamond Structure And Negative Parity
Using the picture of the flux tube model, we propose that the
pentaquark as the first candidate of the three-dimensional non-planar hadron
with the extremely stable diamond structure. The up and down quarks lie at the
corners of the diamond while the anti-strange quark sits in the center. Various
un-excited color flux tubes between the five quarks bind them into a stable and
narrow color-singlet. Such a configuration allows the lowest state having the
negative parity naturally. The decay of the pentaquark into the
nucleon and kaon requires the breakup of the non-planar diamond configuration
into two conventional planar hadrons, which involves some kind of structural
phase transition as in the condensed matter physics. Hence the width of the
pentaquark should be narrow despite that it lies above the kaon
nucleon threshold. We suggest that future lattice QCD calculation adopt
non-planar interpolating currents to explore the underlying structure of the
pentaquark
Distribution amplitudes of light diquarks
Accumulating evidence indicates that soft quark+quark (diquark) correlations
play an important role in the structure and interactions of hadrons constituted
from three or more valence-quarks; so, it is worth developing insights into
diquark structure. Using a leading-order truncation of those equations needed
to solve continuum two-valence-body bound-state problems, the leading-twist
two-parton distribution amplitudes (DAs) of light-quark scalar and pseudovector
diquarks are calculated. The diquark DAs are narrower and taller than the
asymptotic profile that characterises mesons. Consequently, the valence
quasiparticles in a diquark are less likely to carry a large light-front
fraction of the system's total momentum than those in a meson. These features
may both influence the form of baryon DAs and be transmitted to diquark
distribution functions (DFs), in which case their impact will be felt, e.g. in
the proton's and valence-quark DFs.Comment: 8 pages, 2 figures, 1 table. Accepted for publication in Eur. Phys.
J. A (Lett
Hadronic Production of the Doubly Charmed Baryon with Intrinsic Charm
The effects of the intrinsic charm on the hadronic production of
are studied. By taking reasonable intrinsic charm component into account, the
change of the theoretical prediction on the production of for LHC
and Tevatron is small, but in contrast it may enhance significantly for SELEX.
The reason is that the collision energy at LHC and Tevatron is so large that
the gluon-gluon fusion sub-process, which is irrelevant to intrinsic charm,
becomes dominant. But the situation for SELEX is quite different. Our numerical
results for SELEX show that by considering all the contributions from various
sub-processes, the predicted cross-section may be enhanced by a factor so big
as due to a modulating intrinsic charm being taken into account.
Therefore, the hadronic production of at SELEX may be sensitive
enough in observing the intrinsic charm inside the incident hadrons.Comment: 18 pages, 8 figures. More discussions are adde
The meson annihilation to leptons and inclusive light hadrons
The annihilation of the meson to leptons and inclusive light hadrons is
analyzed in the framework of nonrelativistic QCD (NRQCD) factorization. We find
that the decay mode, which escapes from the helicity suppression, contributes a
sizable fraction width. According to the analysis, the branching ratio due to
the contribution from the color-singlet component of the meson can be of
order (10^{-2}). We also estimate the contributions from the color-octet
components. With the velocity scaling rule of NRQCD, we find that the
color-octet contributions are sizable too, especially, in certain phase space
of the annihilation they are greater than (or comparative to) the color-singlet
component. A few observables relevant to the spectrum of charged lepton are
suggested, that may be used as measurements on the color-octet and
color-singlet components in the future experiments. A typical long
distance contribution in the annihilation is estimated too.Comment: 26 pages, 5 figures (6 eps-files), submitted to Phys. Rev.
Supersymmetric contributions to B -> D K and the determination of angle \gamma
We analyze supersymmetric contributions to B^- -> D^0 K^- and B^- ->\bar{D}^0
K^- processes. We investigate the possibility that supersymmetric CP violating
phases can affect our determination for the angle \gamma in the unitary
triangle of Cabibbo-Kobayashi-Maskaw mixing matrix. We calculate the gluino and
chargino contributions to b--> u(\bar{c}s) and b-->c(\bar{u}s) transitions in a
model independent way by using the mass insertion approximation method. We also
revise the D^0 - \bar{D}^0 mixing constraints on the mass insertions between
the first and second generations of the up sector. We emphasize that in case of
negligible D^0 -\bar{D}^0 mixing, one should consider simultaneous
contributions from more than one mass insertion in order to be able to obtain
the CP asymmetries of these processes within their 1\sigma experimental range.
However, with a large D^0-\bar{D}^0 mixing, one finds a significant deviation
between the two asymmetries and it becomes natural to have them of order the
central values of their experimental measurements.Comment: 20 page
Revisiting the -Meson Production at the Hadronic Colliders
The production of heavy-flavored hadron at the hadronic colliders provides a
challenging opportunity to test the validity of pQCD predictions. There are two
mechanisms for the hadroproduction, i.e. the gluon-gluon fusion
mechanism via the subprocess and the
extrinsic heavy quark mechanism via the subprocesses and , both of which shall have sizable
contributions in proper kinematic region. Different from the
fixed-flavor-number scheme (FFNS) previously adopted in the literature, we
study the hadroproduction under the general-mass
variable-flavor-number scheme (GM-VFNS), in which we can consistently deal with
the double counting problem from the above two mechanisms. Properties for the
hadroproduction are discussed. To be useful reference, a
comparative study of FFNS and GM-VFNS is presented. Both of which can provide
reasonable estimations for the hadroproduction. At the Tevatron,
the difference between these two schemes is small, however such difference is
obvious at the LHC. The forthcoming more precise data on LHC shall provide a
good chance to check which scheme is more appropriate to deal with the
-meson production and to further study the heavy quark components in
hadrons.Comment: 18 pages, 8 figures, 4 tables. To match the published version. To be
published in Eur.Phys.J.
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