2,227 research outputs found
Testable and Untestable Aspects of Dark Energy
It has been suggested that dark energy will lead to a frequency cut-off in an
experiment involving a Josephson junction. Here we show that were such a
cut-off detected, it would have dramatic consequences including the possible
demise of the string landscape.Comment: 5 page
Entropy of Contracting Universe in Cyclic Cosmology
Following up a recent proposal \cite{BF} for a cyclic model based on phantom
dark energy, we examine the content of the contracting universe (cu) and its
entropy . We find that beyond dark energy the universe contains on
average zero or at most a single photon which if present immediately after
turnaround has infinitesimally energy which subsequently blue shifts to produce
pairs. These statements are independent of the equation of state
of dark energy provided . Thus and
if observations confirm the entropy problem is solved. We discuss
the absence of a theoretical lower bound on , then
describe an anthropic fine tuning argument that renders unlikely extremely
small . The present bound already implies a time
until turnaround of Gy.Comment: 5 pages late
Cyclic Universe and Infinite Past
We address two questions about the past for infinitely cyclic cosmology. The
first is whether it can contain an infinite length null geodesic into the past
in view of the Borde-Guth-Vilenkin (BGV) "no-go" theorem, The second is
whether, given that a small fraction of spawned universes fail to cycle, there
is an adequate probability for a successful universe after an infinite time. We
give positive answers to both questions then show that in infinite cyclicity
the total number of universes has been infinite for an arbitrarily long time.Comment: 7 pages. Clarification in discussion of infinite pas
Mersenne Primes, Polygonal Anomalies and String Theory Classification
It is pointed out that the Mersenne primes and associated
perfect numbers play a significant role in string
theory; this observation may suggest a classification of consistent string
theories.Comment: 10 pages LaTe
Setting the Mood: An Examination of the Roles of Romance-Related Mood, Situational Similarity, and Character Attribute Similarity in Selective Exposure to Romantic Comedies
Two studies were conducted in order to explore how romance-related mood, situational similarity, and character attribute similarity affect selective exposure to romantic comedies. Eight hypotheses were proposed based on traditional mood management theory (MMT). MMT predicts that people make media selection choices based on a desire to alter a negative mood state and achieve a positive mood state (Zillmann, 1988; Zillmann & Bryant, 1985). For this study in particular, MMT predicts that people in a negative romance-related mood would choose to avoid media content that reminds them of their negative romance-related mood. Content could remind participants of their negative romance-related mood through either situational similarity (Study 1) or character attribute similarity (Study 2). Situational similarity was operationalized through subgenre (female-led comedies vs. traditional romantic comedies), and character attribute similarity was operationalized through age. Experimental research was conducted with college-aged female participants in order to test the hypotheses. Results from a series of ANOVAs and hierarchical regressions revealed that, in general, the hypotheses proposed in this study were not supported. In fact, this study found results contrary to predictions made based on traditional MMT predicted outcomes. This suggests the need for future studies of MMT and its extensions, particularly in regard to motivations for counter-hedonic media selection choices
Quark mass hierarchy in 3-3-1 models
We study the mass spectrum of the quark sector in an special type I-like
model with gauge symmetry . By
considering couplings with scalar triplets at large () and small
() scales, we obtain specific zero-texture mass matrices for the
quarks which predict three massless quarks () and three massive quarks
() at the electroweak scale ( GeV). Taking into account mixing
couplings with three heavy quarks at large scales predicted by the model, the
three massless quarks obtain masses at small order that depends on the inverse
of the large scale. Thus, masses of the form
and can be obtained naturally from the gauge structure of
the model
Constraints on Deflation from the Equation of State of Dark Energy
In cyclic cosmology based on phantom dark energy the requirement that our
universe satisfy a CBE-condition ({\it Comes Back Empty}) imposes a lower bound
on the number of causal patches which separate just prior to
turnaround. This bound depends on the dark energy equation of state with . More accurate measurement of will
constrain . The critical density in the model has a lower
bound or
when the smallest bound state has size m, or m,
respectively.Comment: 23 pages, 3 figures, typos fixe
Search for Heavy Leptons at Hadron Colliders
Four models are considered which contain heavy leptons beyond the three
families of the standard model. Two are fourth-generation extensions of the
standard model in which the right-handed heavy leptons are either isosinglets
or in an isodoublet; the other two are motivated by the aspon model of CP
violation. In all these models, the heavy neutrino can either be heavier than,
or comparable in mass to, the charged lepton leading to the possibility that
the charged lepton is very long-lived. Production cross section and signatures
for the heavy leptons are computed for the SSC and LHC.Comment: 17 pages(8 figures are not included),TRI-PP-92-9
Axigluon Couplings in the Presence of Extra Color-Octet Spin-One Fields
In this paper, we study how the interaction of the axigluon with quarks is
modified when we introduce new color-octet spin-one fields in a chiral color
model. We show that in this case the strength of this interaction is not
completely determined by the gauge symmetry any more and can be significantly
weaker than the one predicted in the original chiral color model. In this way,
we reinterpret the non-observability of the axigluon at the Tevatron, not as a
limit on the axigluon mass, but as a limit on the strength of the axigluon
coupling to quarks
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