818 research outputs found
The coupling constants for an electroweak model with a unification symmetry
We introduce the sequence of spontaneous symmetry breaking of a coupling
between Pati-Salam and electroweak symmetries
in order to establish a mathematically consistent relation among the coupling
constants at grand unification energy scale. With the values of baryon minus
lepton quantum numbers of known quarks and leptons, by including right-handed
neutrinos, we can find the mixing angle relations at different energy levels up
to the electromagnetic scale.Comment: 8 page
Quarkonium Wave Functions at the Origin
We tabulate values of the radial Schr\"{o}dinger wave function or its first
nonvanishing derivative at zero quark-antiquark separation, for ,
, and levels that lie below, or just above, flavor
threshold. These quantities are essential inputs for evaluating production
cross sections for quarkonium states.Comment: 9 pages, RevTeX, no figure
Spacings of Quarkonium Levels with the Same Principal Quantum Number
The spacings between bound-state levels of the Schr\"odinger equation with
the same principal quantum number but orbital angular momenta
differing by unity are found to be nearly equal for a wide range of power
potentials , with . Semiclassical approximations are in accord with this behavior. The
result is applied to estimates of masses for quarkonium levels which have not
yet been observed, including the 2P states and the 1D
states.Comment: 20 pages, latex, 3 uuencoded figures submitted separately (process
using psfig.sty
Prospects for the Bc Studies at LHCb
We discuss the motivations and perspectives for the studies of the mesons of
the (bc) family at LHCb. The description of production and decays at LHC
energies is given in details. The event yields, detection efficiencies, and
background conditions for several Bc decay modes at LHCb are estimated.Comment: 20 pages, 5 eps-figure
Gedanken Worlds without Higgs: QCD-Induced Electroweak Symmetry Breaking
To illuminate how electroweak symmetry breaking shapes the physical world, we
investigate toy models in which no Higgs fields or other constructs are
introduced to induce spontaneous symmetry breaking. Two models incorporate the
standard SU(3)_c x SU(2)_L x U(1)_Y gauge symmetry and fermion content similar
to that of the standard model. The first class--like the standard electroweak
theory--contains no bare mass terms, so the spontaneous breaking of chiral
symmetry within quantum chromodynamics is the only source of electroweak
symmetry breaking. The second class adds bare fermion masses sufficiently small
that QCD remains the dominant source of electroweak symmetry breaking and the
model can serve as a well-behaved low-energy effective field theory to energies
somewhat above the hadronic scale. A third class of models is based on the
left-right--symmetric SU(3)_c x SU(2)_L x SU(2)_R x U(1)_{B-L} gauge group. In
a fourth class of models, built on SU(4)_{PS} x SU(2)_L x SU(2)_R gauge
symmetry, lepton number is treated as a fourth color. Many interesting
characteristics of the models stem from the fact that the effective strength of
the weak interactions is much closer to that of the residual strong
interactions than in the real world. The Higgs-free models not only provide
informative contrasts to the real world, but also lead us to consider
intriguing issues in the application of field theory to the real world.Comment: 20 pages, no figures, uses RevTeX; typos correcte
Eutrophication-induced phosphorus limitation in the Mississippi River plume: Evidence from fast repetition rate fluorometry
We assessed nutrient limitation in the Mississippi River plurne and Louisiana continental shelf during the summer of 2002 (04-08 July). We measured nutrient concentrations, alkaline phosphatase (AP) activities, chlorophyll a (Chl a) concentrations, and four fast repetition rate fluorescence (FRRF) parameters: the maximum quantum yield of photochemistry in photosystem II (PSII), F-v:F-m; the functional absorption cross section for PSII, sigma(psII); the time for photosynthetic electron transport on the acceptor side of PSII, tau(Qa); and the connectivity factor, p, in 24-h-long nutrient addition bioassays near the Mississippi River delta. Low phosphorus (P) concentrations, elevated inorganic nitrogen-to-phosphorus ratios, high AP activities, and Chl a increases in response to P additions in the bioassays all indicated phosphorus limitation that was confirmed by the response of FRRF parameters. This is the first study to use FRRF to confirm results from basic oceanographic methods to demonstrate phosphorus limitation in a marine setting. F-v:F-m and p responded positively to phosphorus addition, while sigma(psII) and tau(Qa) decreased in the same treatments. When nitrate alone was added, none of the measured parameters differed significantly from the control. We therefore suggest that FRRF can be used to rapidly detect phosphorus limitation in marine ecosystems
Scalar radius of the pion in the Kroll-Lee-Zumino renormalizable theory
The Kroll-Lee-Zumino renormalizable Abelian quantum field theory of pions and
a massive rho-meson is used to calculate the scalar radius of the pion at next
to leading (one loop) order in perturbation theory. Due to renormalizability,
this determination involves no free parameters. The result is . This value gives for , the low energy constant of
chiral perturbation theory, , and , where F
is the pion decay constant in the chiral limit. Given the level of accuracy in
the masses and the coupling, the only sizable uncertainty in this
result is due to the (uncalculated) NNLO contribution
Pion form factor in the Kroll-Lee-Zumino model
The renormalizable Abelian quantum field theory model of Kroll, Lee, and
Zumino is used to compute the one-loop vertex corrections to the tree-level,
Vector Meson Dominance (VMD) pion form factor. These corrections, together with
the known one-loop vacuum polarization contribution, lead to a substantial
improvement over VMD. The resulting pion form factor in the space-like region
is in excellent agreement with data in the whole range of accessible momentum
transfers. The time-like form factor, known to reproduce the Gounaris-Sakurai
formula at and near the rho-meson peak, is unaffected by the vertex correction
at order (g_\rpp^2).Comment: Revised version corrects a misprint in Eq.(1
Undetected Blooms in Prince William Sound: Using Multiple Techniques to Elucidate the Base of the Summer Food Web
© 2015, Coastal and Estuarine Research Federation. Prince William Sound supports many commercially and culturally important species. The phytoplankton community dynamics which support and sustain the high biomass and diversity of this ecosystem are largely unknown. The aim of this study was to describe the phytoplankton community composition during the summer, the time at which this system supports many additional migrants and commercially important fisheries. Phytoplankton community composition (pigments), dissolved nutrients, Secchi depth, total and particulate organic carbon and nitrogen, and export to deep water were measured during the summers of 2008–2010. In addition, natural abundance stable isotopes (δ13C and δ15N) of particulate organic matter (POM) and faunal samples were measured in 2010. The analysis of the phytoplankton community composition using multivariate statistics showed that changes over the summer were driven by changes in the proportion of the dominant groups: diatoms, dinoflagellates, cyanobacteria, cryptophytes, chlorophytes, and prasinophytes. These changes were driven by changes in nutrients including an organic nitrogen source, phosphate, and silica and correspond to shifts in particulate concentrations. A consistent pattern was observed each year: a large Noctiluca sp. bloom in June concurrent with low nutrients, low diversity, and high particulate organic carbon (POC) concentrations was followed by a shift in the phytoplankton community to a more diverse smaller size class community in July and equilibrating in August. This annual summer bloom could be an important contributor to the energy and nutrient inputs at the base of the regional marine food web
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