66,451 research outputs found
Instantons and the singlet-coupling in the chiral quark model
Chiral quark model with a broken-U(3) flavor symmetry can be interpreted as
the effective theory of the instanton-dominated non-perturbative QCD. This
naturally suggests the possibility of a negative singlet/octet coupling ratio,
which has been found, in a previous publication, to be compatible with the
phenomenological description of the nucleon spin-flavor structure.Comment: 9 page
One-loop quantum corrections to cosmological scalar field potentials
We study the loop corrections to potentials of complex or coupled real scalar
fields used in cosmology to account for dark energy, dark matter or dark fluid.
We show that the SUGRA quintessence and dark matter scalar field potentials are
stable against the quantum fluctuations, and we propose solutions to the
instability of the potentials of coupled quintessence and dark fluid scalar
fields. We also find that a coupling to fermions is very restricted, unless
this coupling has a structure which already exists in the scalar field
potential or which can be compensated by higher order corrections. Finally, we
study the influence of the curvature and kinetic term corrections.Comment: 11 pages, 1 figure, accepted for publication in Phys. Rev.
As-built design specification for MISMAP
The MISMAP program, which is part of the CLASFYT package, is described. The program is designed to compare classification values with ground truth values for a segment and produce a comparison map and summary table
Radiative lepton flavor violating decays in the Randall Sundrum background with localized leptons
We study the radiative lepton flavor violating l_i -> l_j\gamma decays in the
two Higgs doublet model, respecting the Randall Sundrum scenario and estimate
the contributions of the KK modes of left (right) handed charged lepton
doublets (singlets) on the branching ratios. We observe that the branching
ratios are sensitive to the contributions of the charged lepton KK modes.Comment: 23 pages, 10 figures, 2 table
When renormalizability is not sufficient: Coulomb problem for vector bosons
The Coulomb problem for vector bosons W incorporates a known difficulty; the
boson falls on the center. In QED the fermion vacuum polarization produces a
barrier at small distances which solves the problem. In a renormalizable SU(2)
theory containing vector triplet (W^+,W^-,gamma) and a heavy fermion doublet F
with mass M the W^- falls on F^+, to distances r ~ 1/M, where M can be made
arbitrary large. To prevent the collapse the theory needs additional light
fermions, which switch the ultraviolet behavior of the theory from the
asymptotic freedom to the Landau pole. Similar situation can take place in the
Standard Model. Thus, the renormalizability of a theory is not sufficient to
guarantee a reasonable behavior at small distances for non-perturbative
problems, such as a bound state problem.Comment: Four page
Strength distribution of repeatedly broken chains
We determine the probability distribution of the breaking strength for chains
of N links, which have been produced by repeatedly breaking a very long chain.Comment: 4 pages, 1 figur
Probing the SUSY breaking scale at an collider
If supersymmetry is spontaneously at a low energy scale then the resulting
gravitino would be very light. The interaction strength of the longitudinal
components of such a light gravitino to electron-selectron pair then becomes
comparable to that of electroweak interactions. Such a light gravitino could
modify the cross-section for e^_L e^_R-->\tilde {e}_L\tilde {e}_R from its
MSSM value. Precision measurement of this cross-section could therefore be used
to probe the low energy SUSY breaking scale.Comment: Plain Tex, 7 pages, No figure
The Additional Symmetries for the BTL and CTL Hierarchies
The Toda lattice (TL) hierarchy was first introduced by K.Ueno and K.Takasaki
in \cite{uenotaksasai} to generalize the Toda lattice equations\cite{toda}.
Along the work of E. Date, M. Jimbo, M. Kashiwara and T. Miwa \cite{DJKM} on
the KP hierarchy, K.Ueno and K.Takasaki in \cite{uenotaksasai} develop the
theory for the TL hierarchy: its algebraic structure, the linearization, the
bilinear identity, function and so on. Also the analogues of the B and C
types for the TL hierarchy, i.e. the BTL and CTL hierarchies, are considered in
\cite{uenotaksasai}, which are corresponding to infinite dimensional Lie
algebras and respectively. In this
paper, we will focus on the study of the additional symmetries for the BTL and
CTL hierarchies.Comment: 13 page
Equation of State for physical quark masses
We calculate the QCD equation of state for temperatures corresponding to the
transition region with physical mass values for two degenerate light quark
flavors and a strange quark using an improved staggered fermion action
(p4-action) on lattices with temporal extent N_tau=8. We compare our results
with previous calculations performed at twice larger values of the light quark
masses as well as with results obtained from a resonance gas model calculation.
We also discuss the deconfining and chiral aspects of the QCD transition in
terms of renormalized Polyakov loop, strangeness fluctuations and subtracted
chiral condensate. We show that compared to the calculations performed at twice
larger value of the light quark mass the transition region shifts by about 5
MeV toward smaller temperaturesComment: 7 pages, LaTeX, 6 figures; minor corrections, typos corrected,
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