897,112 research outputs found
Inclusive b and b anti-b production with quasi-multi-Regge kinematics at the Tevatron
We consider b-jet hadroproduction in the quasi-multi-Regge-kinematics
approach based on the hypothesis of gluon and quark Reggeization in t-channel
exchanges at high energies. The preliminary data on inclusive b-jet and b
anti-b-dijet production taken by the CDF Collaboration at the Fermilab Tevatron
are well described without adjusting parameters. We find the main contribution
to inclusive b-jet production to be the scattering of a Reggeized gluon and a
Reggeized b-quark to a b quark, which is described by the effective
Reggeon-Reggeon-quark vertex. The main contribution to b anti-b-pair production
arises from the scattering of two Reggeized gluons to a b anti-b pair, which is
described by the effective Reggeon-Reggeon-quark-quark vertex. Our anaysis is
based on the Kimber-Martin-Ryskin prescription for unintegrated gluon and quark
distribution functions using as input the Martin-Roberts-Stirling-Thorne
collinear parton distribution functions of the proton.Comment: 14 pages, 4 figures; formulas for effective vertices included,
discussion of errors somewhat expanded; accepted for publication in Phys.
Rev.
The molecular ion in a magnetic field
A detailed study of the low-lying electronic states
{}^1\Si,{}^3\Si,{}^3\Pi,{}^3\De of the molecular ion in parallel
to a magnetic field configuration (when \al-particle and proton are situated
on the same magnetic line) is carried out for G in
the Born-Oppenheimer approximation. The variational method is employed using a
physically adequate trial function. It is shown that the parallel configuration
is stable with respect to small deviations for \Si-states. The quantum
numbers of the ground state depend on the magnetic field strength. The ground
state evolves from the spin-singlet {}^1\Si state for small magnetic fields
a.u. to the spin-triplet {}^3\Si unbound state for
intermediate fields and to the spin-triplet strongly bound state for a.u. When the molecular ion exists, it is stable with
respect to a dissociation.Comment: 13 pages, 5 figures, 4 table
Nuclear bound states of antikaons, or quantized multiskyrmions?
The spectrum of strange multibaryons is considered within the chiral soliton
model using one of several possible SU(3$ quantization models (the bound state
rigid oscillator version). The states with energy below that of antikaon and
corresponding nucleus can be interpreted as antikaon-nucleus bound states. In
the formal limit of small kaon mass the number of such states becomes large,
for real value of this mass there are at least several states. For large values
of binding energies interpretation of such states just as antikaon-nuclear
bound states becomes more ambiguous.Comment: Corrections, amendments and additions made, references adde
Condon Domain Phase Diagram for Silver
We present the Condon domain phase diagram for a silver single crystal
measured in magnetic fields up to 28 T and temperatures down to 1.3 K. A
standard ac method with a pickup coil system is used at low frequency for the
measurements of the de Haas-van Alphen effect (dHvA). The transition point from
the state of homogeneous magnetization to the inhomogeneous Condon domain state
(CDS) is found as the point where a small irreversibility in the dHvA
magnetization arises, as manifested by an extremely nonlinear response in the
pickup voltage showing threshold character. The third harmonic content in the
ac response is used to determine with high precision the CDS phase boundary.
The experimentally determined Condon domain phase diagram is in good agreement
with the theoretical prediction calculated by the standard Lifshitz-Kosevich
(LK) formula
Charged Hydrogenic, Helium and Helium-Hydrogenic Molecular Chains in a Strong Magnetic Field
A non-relativistic classification of charged molecular hydrogenic, helium and
mixed helium-hydrogenic chains with one or two electrons which can exist in a
strong magnetic field G is given. It is shown that for
both cases at the strongest studied magnetic fields the longest
hydrogenic chain contains at most five protons indicating to the existence of
the and ions, respectively. In the case of the
helium chains the longest chains can exist at the strongest studied magnetic
fields with three and four \al-particles for cases, respectively. For
mixed helium-hydrogenic chains the number of heavy centers can reach five for
highest magnetic fields studied. In general, for a fixed magnetic field
two-electron chains are more bound than one-electron ones.Comment: 32 pages, 2 figures, 9 table
Cluster ensembles, quantization and the dilogarithm
Cluster ensemble is a pair of positive spaces (X, A) related by a map p: A ->
X. It generalizes cluster algebras of Fomin and Zelevinsky, which are related
to the A-space. We develope general properties of cluster ensembles, including
its group of symmetries - the cluster modular group, and a relation with the
motivic dilogarithm. We define a q-deformation of the X-space. Formulate
general duality conjectures regarding canonical bases in the cluster ensemble
context. We support them by constructing the canonical pairing in the finite
type case.
Interesting examples of cluster ensembles are provided the higher Teichmuller
theory, that is by the pair of moduli spaces corresponding to a split reductive
group G and a surface S defined in math.AG/0311149.
We suggest that cluster ensembles provide a natural framework for higher
quantum Teichmuller theory.Comment: Version 7: Final version. To appear in Ann. Sci. Ecole Normale. Sup.
New material in Section 5. 58 pages, 11 picture
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