1,045 research outputs found
Curvature and topological effects on dynamical symmetry breaking in a four- and eight-fermion interaction model
A dynamical mechanism for symmetry breaking is investigated under the
circumstances with the finite curvature, finite size and non-trivial topology.
A four- and eight-fermion interaction model is considered as a prototype model
which induces symmetry breaking at GUT era. Evaluating the effective potential
in the leading order of the 1/N-expansion by using the dimensional
regularization, we explicitly calculate the phase boundary which divides the
symmetric and the broken phase in a weakly curved space-time and a flat
space-time with non-trivial topology, .Comment: 20 pages, 21 figure
Phase Structure of a Four- and Eight-Fermion Interaction Model at Finite Temperature and Chemical Potential in Arbitrary Dimensions
The phase structure of a four- and eight-fermion interaction model is
investigated at finite temperature and chemical potential in arbitrary
space-time dimensions, . The effective potential and the gap
equation are calculated in the leading order of the 1/N expansion. If the first
order phase transition takes place, the phase boundary dividing the symmetric
and the broken phase is modified by the eight-fermion interaction.Comment: 20 pages, 26 figures; revised argument and added reference for
section
GMsâ Responses to the Events of September 11, 2001
Hotel managersâ actions after 9â11 included modifying marketing activities, reducing employeesâ hours, and either postponing capital improvements (for lack of cash flow) or accelerating planned upgrades while business is slow
Nature of the Jurassic Magnetic Quiet Zone
Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 42 (2015): 8367â8372, doi:10.1002/2015GL065394.The nature of the Jurassic Quiet Zone (JQZ), a region of low-amplitude oceanic magnetic anomalies, has been a long-standing debate with implications for the history and behavior of the Earth's geomagnetic field and plate tectonics. To understand the origin of the JQZ, we studied high-resolution sea surface magnetic anomalies from the Hawaiian magnetic lineations and correlated them with the Japanese magnetic lineations. The comparison shows the following: (i) excellent correlation of anomaly shapes from M29 to M42; (ii) remarkable similarity of anomaly amplitude envelope, which decreases back in time from M19 to M38, with a minimum at M41, then increases back in time from M42; and (iii) refined locations of pre-M25 lineations in the Hawaiian lineation set. Based on these correlations, our study presents evidence of regionally and possibly globally coherent pre-M29 magnetic anomalies in the JQZ and a robust extension of Hawaiian isochrons back to M42 in the Pacific crust.National Science Foundation Grant Numbers: OCE-1029965, OCE-1233000, OCE-10295732016-04-2
Level Truncated Tachyon Potential in Various Gauges
New gauge fixing condition with single gauge parameter proposed by the
authors is applied to the level truncated analysis of tachyon condensation in
cubic open string field theory. It is found that the only one real non-trivial
extremum persists to appear in the well-defined region of the gauge parameter,
while the other solutions are turned out to be gauge-artifacts. Contrary to the
previously known pathology in the Feynman-Siegel gauge, tachyon potential is
remarkably smooth enough around Landau-type gauge.Comment: 13 pages, 5 figures. For associated movie files, see
http://hep1.c.u-tokyo.ac.jp/~kato/sft
Along-margin variations in breakup volcanism at the Eastern North American Margin
Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 125(12),(2020): e2020JB020040, https://doi.org/10.1029/2020JB020040.We model the magnetic signature of riftârelated volcanism to understand the distribution and volume of magmatic activity that occurred during the breakup of Pangaea and early Atlantic opening at the Eastern North American Margin (ENAM). Alongâstrike variations in the amplitude and character of the prominent East Coast Magnetic Anomaly (ECMA) suggest that the emplacement of the volcanic layers producing this anomaly similarly varied along the margin. We use threeâdimensional magnetic forward modeling constrained by seismic interpretations to identify alongâmargin variations in volcanic thickness and width that can explain the observed amplitude and character of the ECMA. Our model results suggest that the ECMA is produced by a combination of both firstâorder (~600â1,000 km) and secondâorder (~50â100 km) magmatic segmentation. The firstâorder magmatic segmentation could have resulted from preexisting variations in crustal thickness and rheology developed during the tectonic amalgamation of Pangaea. The secondâorder magmatic segmentation developed during continental breakup and likely influenced the segmentation and transform fault spacing of the initial, and modern, MidâAtlantic Ridge. These variations in magmatism show how extension and thermal weakening was distributed at the ENAM during continental breakup and how this breakup magmatism was related to both previous and subsequent Wilson cycle stages.Thanks to Anne BĂ©cel, Dan Lizarralde, Collin Brandl, Brandon Shuck, and Mark Everett for beneficial discussion and assistance in compiling the archived data used in this study. We thank Debbie Hutchinson (USGS Woods Hole Coastal and Marine Science Center) for passing along her vast breadth of knowledge on the ENAM through numerous constructive suggestions to greatly strengthen our manuscript. We greatly appreciate the insightful comments from two reviewers, the Associate Editor, and the Editor that significantly improved the manuscript. Thanks to Maurice Tivey for providing codes that aided our magnetic modeling efforts. Project completed as part of J.A.G.'s Ph.D. dissertation at Texas A&M University.2021-05-1
A new middle to late Jurassic Geomagnetic Polarity Time Scale (GPTS) from a multiscale marine magnetic anomaly survey of the Pacific Jurassic Quiet Zone
Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 126(3), (2021): e2020JB021136, https://doi.org/10.1029/2020JB021136.The Geomagnetic Polarity Time Scale (GPTS) provides a basis for the geological timescale, quantifies geomagnetic field behavior, and gives a time framework for geologic studies. We build a revised Middle to Late Jurassic GPTS by using a new multiscale magnetic profile, combining sea surface, midwater, and autonomous underwater vehicle near-bottom magnetic anomaly data from the Hawaiian lineation set in the Pacific Jurassic Quiet Zone (JQZ). We correlate the new profile with a previously published contemporaneous magnetic sequence from the Japanese lineation set. We then establish geomagnetic polarity block models as a basis for our interpretation of the origin and nature of JQZ magnetic anomalies and a GPTS. A significant level of coherency between short-wavelength anomalies for both the Japanese and Hawaiian lineation magnetic anomaly sequences suggests the existence of a regionally coherent field during this period of rapid geomagnetic reversals. Our study implies the rapid onset of the Mesozoic Dipole Low from M42 through M39 and then a subsequent gradual recovery in field strength into the Cenozoic. The new GPTS, together with the Japanese sequence, extends the magnetic reversal history from M29 back in time to M44. We identify a zone of varying, difficult-to-correlate anomalies termed the Hawaiian Disturbed Zone, which is similar to the zone of low amplitude, difficult-to-correlate anomalies in the Japanese sequence termed the Low Amplitude Zone (LAZ). We suggest that the LAZ, bounded by M39âM41 isochrons, may in fact represent the core of what is more commonly known as the JQZ crust.This study is funded by National Science Foundation grants OCE-1029965 (Tominaga, Tivey, and Lizarralde) and OCE-1233000 (Tominaga and Tivey) and OCE-1029573 (Sager).2021-07-2
Weitzman Meets Nordhaus : Expected Utility and Catastrophic Risk in a Stochastic Economy-Climate Model
The Sunyaev-Zel'dovich Effect by Cocoons of Radio Galaxies
We estimate the deformation of the cosmic microwave background radiation by
the hot region (``cocoon'') around a radio galaxy. A simple model is adopted
for cocoon evolution while the jet is on, and a model of evolution is
constructed after the jet is off. It is found that at low redshift the phase
after the jet is off is longer than the lifetime of the jets. The Compton
y-parameter generated by cocoons is calculated with a Press-Schechter number
density evolution. The resultant value of y is of the same order as the COBE
constraint. The Sunyaev-Zeldovich effect due to cocoons could therefore be a
significant foreground source of small angular scale anisotropies in the cosmic
microwave background radiation.Comment: Published version, 23 pages with 5 figure
Axial Anomaly and Transition Form Factors
We investigate the properties of the amplitude induced by the anomaly. In a
relatively high energy region those amplitudes are constructed by the vector
meson poles and the anomaly terms, in which the anomaly terms can be
essentially evaluated by the triangle quark graph. We pay our attention to the
anomaly term and make intensive analysis of the existing experimental data,
i.e., the electromagnetic and transition form factors. Our
result shows that it is essential to use the constituent quark mass instead of
the current quark mass in evaluating the anomaly term from the triangle graph.Comment: LaTeX, 14 pages + 4 figures, (figures are included as uuencoded
files), KUNS-1210 HE(TH) 93/0
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