378 research outputs found
Noncommutative Inspired Black Holes in Extra Dimensions
In a recent string theory motivated paper, Nicolini, Smailagic and Spallucci
(NSS) presented an interesting model for a noncommutative inspired,
Schwarzschild-like black hole solution in 4-dimensions. The essential effect of
having noncommutative co-ordinates in this approach is to smear out matter
distributions on a scale associated with the turn-on of noncommutativity which
was taken to be near the 4-d Planck mass. In particular, NSS took this smearing
to be essentially Gaussian. This energy scale is sufficiently large that in 4-d
such effects may remain invisible indefinitely. Extra dimensional models which
attempt to address the gauge hierarchy problem, however, allow for the
possibility that the effective fundamental scale may not be far from 1
TeV, an energy regime that will soon be probed by experiments at both the LHC
and ILC. In this paper we generalize the NSS model to the case where flat,
toroidally compactified extra dimensions are accessible at the Terascale and
examine the resulting modifications in black hole properties due to the
existence of noncommutativity. We show that while many of the
noncommutativity-induced black hole features found in 4-d by NSS persist, in
some cases there can be significant modifications due the presence of extra
dimensions. We also demonstrate that the essential features of this approach
are not particularly sensitive to the Gaussian nature of the smearing employed
by NSS.Comment: 30 pages, 12 figures; slight text modifications and references adde
Mechanism of C-H Bond Activation of Alkyl-Substituted Benzenes by Cationic Platinum(II) Complexes
The critical exponents of the two-dimensional Ising spin glass revisited: Exact Ground State Calculations and Monte Carlo Simulations
The critical exponents for of the two-dimensional Ising spin glass
model with Gaussian couplings are determined with the help of exact ground
states for system sizes up to and by a Monte Carlo study of a
pseudo-ferromagnetic order parameter. We obtain: for the stiffness exponent
, for the magnetic exponent
and for the chaos exponent . From Monte Carlo simulations we
get the thermal exponent . The scaling prediction is
fulfilled within the error bars, whereas there is a disagreement with the
relation .Comment: 8 pages RevTeX, 7 eps-figures include
Remarks on Limits on String Scale from Proton Decay and Low-Energy amplitudes in Braneworld Scenario
We discuss IR limit of four-fermion scattering amplitudes in braneworld
models including intersecting-branes and SUSY SU(5) GUT version of it. With
certain compactification where instanton effect is negligible, grand
unification condition in D6-D6 intersecting-branes scenario subject to
experimental constraint on proton decay provides possibility for upper limit on
the string scale, , through relationship between the string coupling,
, and the string scale. We discuss how IR divergence is related to number
of twisted fields we have to introduce into intersection region and how it can
change IR behaviour of tree-level amplitudes in various intersecting-branes
models. Using number of twisted fields, we identify some intersecting-branes
models whose tree-level amplitudes are purely stringy in nature and
automatically proportional to at low energy. They are
consequently suppressed by the string scale. For comparison, we also derive
limit on the lower bound of the string scale from experimental constraint on
proton decay induced from purely stringy contribution in the coincident-branes
model, the limit is about TeV.Comment: 14 page
Dynamics of Collapse of flexible Polyelectrolytes and Polyampholytes
We provide a theory for the dynamics of collapse of strongly charged
polyelectrolytes (PEs) and flexible polyampholytes (PAs) using Langevin
equation. After the initial stage, in which counterions condense onto PE, the
mechanism of approach to the globular state is similar for PE and PA. In both
instances, metastable pearl-necklace structures form in characteristic time
scale that is proportional to N^{4/5} where N is the number of monomers. The
late stage of collapse occurs by merger of clusters with the largest one
growing at the expense of smaller ones (Lifshitz- Slyozov mechanism). The time
scale for this process T_{COLL} N. Simulations are used to support the proposed
collapse mechanism for PA and PE.Comment: 14 pages, 2 figure
Supersymmetry Without Prejudice
We begin an exploration of the physics associated with the general
CP-conserving MSSM with Minimal Flavor Violation, the pMSSM. The 19 soft SUSY
breaking parameters in this scenario are chosen so as to satisfy all existing
experimental and theoretical constraints assuming that the WIMP is a
conventional thermal relic, ie, the lightest neutralino. We scan this parameter
space twice using both flat and log priors for the soft SUSY breaking mass
parameters and compare the results which yield similar conclusions. Detailed
constraints from both LEP and the Tevatron searches play a particularly
important role in obtaining our final model samples. We find that the pMSSM
leads to a much broader set of predictions for the properties of the SUSY
partners as well as for a number of experimental observables than those found
in any of the conventional SUSY breaking scenarios such as mSUGRA. This set of
models can easily lead to atypical expectations for SUSY signals at the LHC.Comment: 61 pages, 24 figs. Refs., figs, and text added, typos fixed; This
version has reduced/bitmapped figs. For a version with better figs please go
to http://www.slac.stanford.edu/~rizz
Metaphors we die by? Geoengineering, metaphors and the argument from catastrophe
Geoeengineering the climate by reflecting sunlight or extracting carbon dioxide from the atmosphere has attracted increasing attention from natural scientists, social scientists, policy makers and the media. This article examines promotional discourse related to geoengineering from the 1980s to 2010. It asks in particular how this option for dealing with the problems posed by climate change were framed through the use of conceptual and discourse metaphors and whether one can argue that these are metaphors we âlive byâ or metaphors we might âdie byâ. Findings show that an overarching argument from catastrophe was bolstered by three conceptual master-metaphors, namely The Planet is a body, The Planet is a machine and The planet is a patient/addict, linked to a variety of discourse metaphors, older conceptual metaphors and clichĂ©s. This metaphorical landscape began to shift while the article was being written and will have to be closely monitored in the future
Exploring Takfir, Its Origins and Contemporary Use: The Case of Takfiri Approach in Daeshâs Media
Muslims have been the primary targets of Daeshâs attacks since 2014 in different countries such as Afghanistan, Iraq, and Syria. These attacks were based on its takfiri ideology. As Daesh official media and documents indicate, kufr (unbelief, infidelity) in Daeshâs approach is not limited to non-Muslims (original disbelievers), but Muslims are the most significant parts of kuffar (unbelievers) in its view and defined as incidental disbelievers. Through studying Daeshâs official documents and various Arabic, English, and Persian media productions, in an explanatory research, this article attempts to display Daeshâs takfiri approach toward Muslims and explains its historical and ideological roots, difference with Al-Qaedaâs takfiri approach, different approaches to takfir inside Daesh, main targets of Daeshâs takfir, and the reasons behinds its takfiri view. This article displays that for Daesh, the Muslims are limited only to Sunni Muslims who are accepting and following its approach. Other Sunni and non-Sunni Muslims are thus kuffar. This study also shows that the assertion of takfir has become a method for Daesh to discredit its opponents, such as Shiâa Muslims and other Muslim groups
A beer a minute in Texas football: Heavy drinking and the heroizing of the antihero in Friday Night Lights
This article applies a qualitative framing analysis to the first three seasons of the television series Friday Night Lights, focusing particularly on its incorporation of heavy drinking into narrative representations of the player whose character is most consistently central to the game of football as fictionally mediated in small-town Texas over the course of those three seasons. The analysis suggests that over the course of that period Friday Night Lights embeds nuanced social meanings in its framing of alcohol use by that player and other characters so as to associate it with multiple potential outcomes. Yet among those outcomes, the most dominant framing works to, in effect, reverse a progression through which media representations historically evolved from a heroic model toward an antihero model, with heavy drinking central to that narrative process of meaning-making in such messages.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
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