1,810 research outputs found
Associated production of the charged Higgs boson and single top quark at the LHC
The left-right twin Higgs(LRTH) model predicts the existence of the charged
Higgs . In this paper, we study the production of the charged Higgs
boson with single top quark via the process at the
Large Hadron Collider(LHC). The numerical results show that the
production cross section can reach the level of in the reasonable
parameter space of the LRTH model. We expect that, as long as it is not too
heavy, the possible signatures of the heavy charged Higgs boson
might be detected via the decay mode at the LHC
experiments.Comment: This paper has been withdrawn by the author(s) due to some mistakes
in this pape
Implications of Neutrino Mass Generation from QCD Confinement
We consider the possibility that the quark condensate formed by QCD
confinement generates Majorana neutrino masses m_\nu via dimension seven
operators. No degrees of freedom beyond the Standard Model are necessary, below
the electroweak scale. Obtaining experimentally acceptable neutrino masses
requires the new physics scale \Lambda ~ TeV, providing a new motivation for
weak-scale discoveries at the LHC. We implement this mechanism using a Z_3
symmetry which leads to a massless up quark above the QCD chiral condensate
scale. We use non-helicity-suppressed light meson rare decay data to constrain
\Lambda. Experimental constraints place a mild hierarchy on the flavor
structure of dimension seven operators and the resulting neutrino mass matrix.Comment: 4 pages, Revte
Efficacy of alternative seating on attention, in-seat behavior, and occupational performance in children with Attention Deficit Hyperactivity Disorder
Currently, there is one systematic review conducted by Gochenour and Poskey7 that synthesize current research evidence regarding alternative seating for students with attention difficulties. A limitation of this review, as noted by the authors, is a lack of a consistent definition of attention difficulty in the studies they included. A systematic review focused on a specific, well-defined diagnosis will better contribute to practice recommendations since these recommendations will be tailored to a clear and comprehensive understanding of the child’s attentional and occupational challenges. The review also included studies of children with autism spectrum disorder (ASD).7 While those with ASD may also have difficulties with attention, in-seat behavior and occupational performance, the underlying mechanism yielding these symptoms may be different than in children with ADHD. Thus, alternative seating may not work in the same way for children with ASD as it would for children with ADHD.7 Thus, a systematic review is needed to examine the evidence from all current studies regarding alternative seating on improving attention, in-seat behavior and occupational performance in students with ADHD to increase evidence-based practice in the field of occupational therapy
Massive Gravity on a Brane
At present no theory of a massive graviton is known that is consistent with
experiments at both long and short distances. The problem is that consistency
with long distance experiments requires the graviton mass to be very small.
Such a small graviton mass however implies an ultraviolet cutoff for the theory
at length scales far larger than the millimeter scale at which gravity has
already been measured. In this paper we attempt to construct a model which
avoids this problem. We consider a brane world setup in warped AdS spacetime
and we investigate the consequences of writing a mass term for the graviton on
a the infrared brane where the local cutoff is of order a large (galactic)
distance scale. The advantage of this setup is that the low cutoff for physics
on the infrared brane does not significantly affect the predictivity of the
theory for observers localized on the ultraviolet brane. For such observers the
predictions of this theory agree with general relativity at distances smaller
than the infrared scale but go over to those of a theory of massive gravity at
longer distances. A careful analysis of the graviton two-point function,
however, reveals the presence of a ghost in the low energy spectrum. A mode
decomposition of the higher dimensional theory reveals that the ghost
corresponds to the radion field. We also investigate the theory with a brane
localized mass for the graviton on the ultraviolet brane, and show that the
physics of this case is similar to that of a conventional four dimensional
theory with a massive graviton, but with one important difference: when the
infrared brane decouples and the would-be massive graviton gets heavier than
the regular Kaluza--Klein modes, it becomes unstable and it has a finite width
to decay off the brane into the continuum of Kaluza-Klein states.Comment: 26 pages, LaTeX. v2: extended version with an appendix added about
non Fierz-Pauli mass terms. Few typos corrected. Final version appeared in
PR
Neutrino Telescopes as a Direct Probe of Supersymmetry Breaking
We consider supersymmetric models where the scale of supersymmetry breaking
lies between 5 GeV and 5 GeV. In this class of
theories, which includes models of gauge mediated supersymmetry breaking, the
lightest supersymmetric particle is the gravitino. The next to lightest
supersymmetric particle is typically a long lived charged slepton with a
lifetime between a microsecond and a second, depending on its mass. Collisions
of high energy neutrinos with nucleons in the earth can result in the
production of a pair of these sleptons. Their very high boost means they
typically decay outside the earth. We investigate the production of these
particles by the diffuse flux of high energy neutrinos, and the potential for
their observation in large ice or water Cerenkov detectors. The relatively
small cross-section for the production of supersymmetric particles is partially
compensated for by the very long range of heavy particles. The signal in the
detector consists of two parallel charged tracks emerging from the earth about
100 meters apart, with very little background. A detailed calculation using the
Waxman-Bahcall limit on the neutrino flux and realistic spectra shows that
km experiments could see as many as 4 events a year. We conclude that
neutrino telescopes will complement collider searches in the determination of
the supersymmetry breaking scale, and may even give the first evidence for
supersymmetry at the weak scale.Comment: 4 pages, 3 figure
The GUT Scale and Superpartner Masses from Anomaly Mediated Supersymmetry Breaking
We consider models of anomaly-mediated supersymmetry breaking (AMSB) in which
the grand unification (GUT) scale is determined by the vacuum expectation value
of a chiral superfield. If the anomaly-mediated contributions to the potential
are balanced by gravitational-strength interactions, we find a
model-independent prediction for the GUT scale of order . The GUT threshold also affects superpartner masses, and can easily
give rise to realistic predictions if the GUT gauge group is asymptotically
free. We give an explicit example of a model with these features, in which the
doublet-triplet splitting problem is solved. The resulting superpartner
spectrum is very different from that of previously considered AMSB models, with
gaugino masses typically unifying at the GUT scale.Comment: 17 page
Implications on SUSY breaking mediation mechanisms from observing and the muon
We consider and the muon in various SUSY
breaking mediation mechanisms. If the decay is observed
at Tevatron Run II with a branching ratio larger than ,
the noscale supergravity (including the gaugino mediation), the gauge mediation
scenario with small number of messenger fields and low messenger scale, and a
class of anomaly mediation scenarios will be excluded, even if they can
accommodate a large muon . On the other hand, the minimal
supergravity scenario and similar mechanisms derived from string models can
accommodate this observation.Comment: 4 pages, 3 figure
Distinct phase-amplitude couplings distinguish cognitive processes in human attention
Abstract
Spatial attention is the cognitive function that coordinates the selection of visual stimuli with appropriate behavioral responses. Recent studies have reported that phase-amplitude coupling (PAC) of low and high frequencies covaries with spatial attention, but differ on the direction of covariation and the frequency ranges involved. We hypothesized that distinct phase-amplitude frequency pairs have differentiable contributions during tasks that manipulate spatial attention. We investigated this hypothesis with electrocorticography (ECoG) recordings from participants who engaged in a cued spatial attention task. To understand the contribution of PAC to spatial attention we classified cortical sites by their relationship to spatial variables or behavioral performance. Local neural activity in spatial sites was sensitive to spatial variables in the task, while local neural activity in behavioral sites correlated with reaction time. We found two PAC frequency clusters that covaried with different aspects of the task. During a period of cued attention, delta-phase/high-gamma (DH) PAC was sensitive to cue direction in spatial sites. In contrast, theta-alpha-phase/beta-low-gamma-amplitude (TABL) PAC robustly correlated with future reaction times in behavioral sites. Finally, we investigated the origins of TABL PAC and found it corresponded to behaviorally relevant, sharp waveforms, which were also coupled to a low frequency rhythm. We conclude that TABL and DH PAC correspond to distinct mechanisms during spatial attention tasks and that sharp waveforms are elements of a coupled dynamical process
Bulk Gauge Fields in Warped Space and Localized Supersymmetry Breaking
We consider five dimensional supersymmetric warped scenarios in which the
Standard Model quark and lepton fields are localized on the ultraviolet brane,
while the Standard Model gauge fields propagate in the bulk. Supersymmetry is
assumed to be broken on the infrared brane. The relative sizes of supersymmetry
breaking effects are found to depend on the hierarchy between the infrared
scale and the weak scale. If the infrared scale is much larger than the weak
scale the leading supersymmetry breaking effect on the visible brane is given
by gaugino mediation. The gaugino masses at the weak scale are proportional to
the square of the corresponding gauge coupling, while the dominant contribution
to the scalar masses arises from logarithmically enhanced radiative effects
involving the gaugino mass that are cutoff at the infrared scale. While the LSP
is the gravitino, the NLSP which is the stau is stable on collider time scales.
If however the infrared scale is close to the weak scale then the effects of
hard supersymmetry breaking operators on the scalar masses can become
comparable to those from gaugino mediation. These operators alter the relative
strengths of the couplings of gauge bosons and gauginos to matter, and give
loop contributions to the scalar masses that are also cutoff at the infrared
scale. The gaugino masses, while exhibiting a more complicated dependence on
the corresponding gauge coupling, remain hierarchical and become proportional
to the corresponding gauge coupling in the limit of strong supersymmetry
breaking. The scalar masses are finite and a loop factor smaller than the
gaugino masses. The LSP remains the gravitino.Comment: 36 pages, 2 figure
Pair production of charged Higgs bosons in the Left-Right Twin Higgs model at the ILC and LHC
Left-Right twin Higgs(LRTH) model predicts the existence of a pair of charged
Higgs . In this paper, we study the production of the charged Higgs
bosons pair via the process at
the International Linear Collider(ILC). The numerical results show that the
production rates are at the level of several tens fb, this process can produce
the adequate distinct multi-jet final states and the SM background can be
efficiently reduced. We also discuss the charged Higgs boson pair production
via the process at the Large Hadron
Collider(LHC) and estimate there production rates. We find that, as long as the
charged Higgs bosons are not too heavy, they can be abundantly produced at the
LHC. The possible signatures of these new particles might be detected at the
ILC and LHC experiments.Comment: 15 pages, 5 figures, discussion extended, reference added, typos
fixed, revised version to be published in Eur.Phys.J.
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