2,131 research outputs found
Dependence of nucleotide physical properties on their placement in codons and determinative degree
Various physical properties such as dipole moment, heat of formation and
energy of the most stable formation of nucleotides and bases were calculated by
PM3 (modified neglect of diatomic overlap, parametric method number 3) and AM1
(Austin model 1) methods. As distinct from previous calculations, for
nucleotides the interaction with neighbours is taken into account up to
gradient of convergence equaling 1. The dependences of these variables from the
place in the codon and the determinative degree were obtained. The difference
of these variables for codons and anticodons is shown.Comment: 13 pages, 8 figures, PD
Photoproduction and electroproduction of charm at high energies
We estimate the differential and total cross sections for both the
photoproduction of vector D*-meson and its yield in deep inelastic scattering
at the HERA collider in the framework of model motivated by perturbative
calculations in QCD. The offered model allows us to take into account higher
twists over the transverse momentum of meson at p_T ~ m_c and to correctly
approach the dominance of -quark fragmentation at p_T >> m_c. We consider a
possibility for the hadronization of color-octet c q-bar state into the meson.
The combined contribution by the singlet and octet-color terms results in a
good agreement with the experimental data for both the photoproduction and the
production in deep inelastic scattering.Comment: 27 pages, ReVTeX, 8 eps-figures, explanations added, results
unchange
Hadronic Production of the Doubly Heavy Baryon at LHC
We investigate the hadronic production of the doubly heavy baryon
at the large hadron collider (LHC), where contributions from the four
-diquark states and
have been taken into consideration. Numerical
results show that under the condition of GeV and , sizable
events about and per year can be
produced for the center-of-mass energy TeV and TeV
respectively. For experimental usage, the total and the interested differential
cross-sections are estimated under some typical - and - cuts for the
LHC detectors CMS, ATLAS and LHCb. Main uncertainties are discussed and a
comparative study on the hadronic production of , and
at LHC are also presented.Comment: 9 pages, 8 figures, 6 tables. References updated and more discussions
are added. To be published in Phys.Rev.
Formation of 24Mg* in the Splitting of 28Si Nuclei by 1-GeV Protons
The 28Si(p, p' gamma)24Mg reaction has been studied at the ITEP accelerator
by the hadron-gamma coincidence method for a proton energy of 1 GeV. Two
reaction products are detected: a 1368.6-keV gamma-ray photon accompanying the
transition of the 24Mg* nucleus from the first excited state to the ground
state and a proton p' whose momentum is measured in a magnetic spectrometer.
The measured distribution in the energy lost by the proton in interaction is
attributed to five processes: the direct knockout of a nuclear alpha cluster,
the knockout of four nucleons with a total charge number of 2, the formation of
the DeltaSi isobaric nucleus, the formation of the Delta isobar in the
interaction of the incident proton with a nuclear nucleon, and the production
of a pi meson, which is at rest in the nuclear reference frame. The last
process likely corresponds to the reaction of the formation of a deeply bound
pion state in the 28P nucleus. Such states were previously observed only on
heavy nuclei. The cross sections for the listed processes have been estimated.Comment: 14 pages, 3 figures submitted to JETP Letter
Pair Production of Heavy Quarkonium and Mesons at Hadron Colliders
We investigate the pair production of S-wave heavy quarkonium at the LHC in
the color-singlet mechanism (CSM) and estimate the contribution from the gluon
fragmentation process in the color-octet mechanism (COM) for comparison. With
the matrix elements extracted previously in the leading order calculations, the
numerical results show that the production rates are quite large for the pair
production processes at the LHC. The distribution of double
production in the CSM is dominant over that in the COM when is smaller
than about 8GeV. For the production of double , the contribution of
the COM is always larger than that in the CSM. The large differences in the
theoretical predictions between the CSM and COM for the distributions in
the large region are useful in clarifying the effects of COM on the
quarkonium production. We also investigate the pair production of S-wave
and mesons, and the measurement of these processes is useful to test
the CSM and extract the LDMEs for the and mesons.Comment: 8 figure
High-Energy Approach for Heavy-Ion Scattering with Excitations of Nuclear Collective States
A phenomenological optical potential is generalized to include the Coulomb
and nuclear interactions caused by the dynamical deformation of its surface. In
the high-energy approach analytical expressions for elastic and inelastic
scattering amplitudes are obtained where all the orders in the deformation
parameters are included. The multistep effect of the 2 rotational state
excitation on elastic scattering is analyzed. Calculations of inelastic cross
sections for the O ions scattered on different nuclei at about hundred
Mev/nucleon are compared with experimental data, and important role of the
Coulomb excitation is established.Comment: 9 pages; 3 figures. Submitted to the Physics of Atomic Nucle
Decays of the Meson to a -Wave Charmonium State or
The semileptonic decays,
, and the two-body
nonleptonic decays, , (here and
denote and respectively, and
indicates a meson) were computed. All of the form factors appearing in the
relevant weak-current matrix elements with as its initial state and a
-wave charmonium state as its final state for the decays were precisely
formulated in terms of two independent overlapping-integrations of the
wave-functions of and the -wave charmonium and with proper kinematics
factors being `accompanied'. We found that the decays are quite sizable, so
they may be accessible in Run-II at Tevatron and in the foreseen future at LHC,
particularly, when BTeV and LHCB, the special detectors for B-physics, are
borne in mind. In addition, we also pointed out that the decays may potentially be used as a fresh window to look for the
charmonium state, and the cascade decays,
() with one of the radiative decays
being followed accordingly, may affect
the observations of meson through the decays () substantially.Comment: 24 pages, 3 figures, the replacement for improving the presentation
and adding reference
Perturbative Fragmentation of Leptoquark into Heavy Lepto-Quarkonium
The fragmentation function of a scalar leptoquark into possible S-wave bound
states with a heavy anti-quark is calculated to the leading order in
perturbative QCD for the high energy processes at large transverse momenta. The
one-loop equations for the -evolution of moments of the fragmentation
function due to the hard gluon emission by the leptoquark are derived. The
integral probabilities of fragmentation are evaluated.Comment: 8 pages, epsf-style, 3 eps-figure
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.
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