43,572 research outputs found
Anomalous Gluon Self-Interactions and Production
Strong-interaction physics that lies beyond the standard model may
conveniently be described by an effective Lagrangian. The only genuinely
gluonic CP-conserving term at dimension six is the three-gluon-field-strength
operator . This operator, which alters the 3-gluon and 4-gluon vertices
form their standard model forms, turns out to be difficult to detect in final
states containing light jets. Its effects on top quark pair production hold the
greatest promise of visibility.Comment: Latex file using [aps,aipbook,floats,epsf]{revtex}. 12 pages, 4
Postscript figures. Full PS copy at http://smyrd.bu.edu/htfigs/htfigs.html
Talk presented by EHS at the International Symposium on Vector Boson
Self-Interactions, UCLA, Feb. 1-3, 199
The Price of an Electroweak Monopole
In a recent paper, Cho, Kim and Yoon (CKY) have proposed a version of the
SU(2) U(1) Standard Model with finite-energy monopole and dyon
solutions. The CKY model postulates that the effective U(1) gauge coupling very rapidly as the Englert-Brout-Higgs vacuum expectation value , but in a way that is incompatible with LHC measurements of the Higgs boson
decay rate. We construct generalizations of the CKY model
that are compatible with the constraint, and calculate
the corresponding values of the monopole and dyon masses. We find that the
monopole mass could be TeV, so that it could be pair-produced at the
LHC and accessible to the MoEDAL experiment.Comment: 15 pages; Two clarifying footnotes (3 and 4) added. No effect on
conclusion
Monopoles and Knots in Skyrme Theory
We show that the Skyrme theory actually is a theory of monopoles which allows
a new type of solitons, the topological knots made of monopole-anti-monopole
pair,which is different from the well-known skyrmions. Furthermore, we derive a
generalized Skyrme action from the Yang-Mills action of QCD, which we propose
to be an effective action of QCD in the infra-red limit. We discuss the
physical implications of our results.Comment: 4 pages. Phys. Rev. Lett. in pres
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
First Principles Study of Work Functions of Double Wall Carbon Nanotubes
Using first-principles density functional calculations, we investigated work
functions (WFs) of thin double-walled nanotubes (DWNTs) with outer tube
diameters ranging from 1nm to 1.5nm. The results indicate that work function
change within this diameter range can be up to 0.5 eV, even for DWNTs with same
outer diameter. This is in contrast with single-walled nanotubes (SWNTs) which
show negligible WF change for diameters larger than 1nm. We explain the WF
change and related charge redistribution in DWNTs using charge equilibration
model (CEM). The predicted work function variation of DWNTs indicates a
potential difficulty in their nanoelectronic device applications.Comment: 11 pages, 3 figures, to appear as rapid communication on Physical
Review
Growth of Magnetic Fields Induced by Turbulent Motions
We present numerical simulations of driven magnetohydrodynamic (MHD)
turbulence with weak/moderate imposed magnetic fields. The main goal is to
clarify dynamics of magnetic field growth. We also investigate the effects of
the imposed magnetic fields on the MHD turbulence, including, as a limit, the
case of zero external field. Our findings are as follows. First, when we start
off simulations with weak mean magnetic field only (or with small scale random
field with zero imposed field), we observe that there is a stage at which
magnetic energy density grows linearly with time. Runs with different numerical
resolutions and/or different simulation parameters show consistent results for
the growth rate at the linear stage. Second, we find that, when the strength of
the external field increases, the equilibrium kinetic energy density drops by
roughly the product of the rms velocity and the strength of the external field.
The equilibrium magnetic energy density rises by roughly the same amount.
Third, when the external magnetic field is not very strong (say, less than ~0.2
times the rms velocity when measured in the units of Alfven speed), the
turbulence at large scales remains statistically isotropic, i.e. there is no
apparent global anisotropy of order B_0/v. We discuss implications of our
results on astrophysical fluids.Comment: 16 pages, 18 figures; ApJ, accepte
CMB Spectral Distortion Constraints on Thermal Inflation
Thermal inflation is a second epoch of exponential expansion at typical
energy scales . If the usual
primordial inflation is followed by thermal inflation, the primordial power
spectrum is only modestly redshifted on large scales, but strongly suppressed
on scales smaller than the horizon size at the beginning of thermal inflation,
. We calculate the spectral distortion of
the cosmic microwave background generated by the dissipation of acoustic waves
in this context. For , thermal inflation
results in a large suppression of the -distortion amplitude, predicting
that it falls well below the standard value of .
Thus, future spectral distortion experiments, similar to PIXIE, can place new
limits on the thermal inflation scenario, constraining if were found.Comment: 18 pages, 7 figure
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