175 research outputs found
Recommended from our members
Spectral and temporal processing in human auditory cortex
Hierarchical processing suggests that spectrally and temporally complex stimuli will evoke more activation than do simple stimuli, particularly in non-primary auditory fields. This hypothesis was tested using two tones, a single frequency tone and a harmonic tone, that were either static or frequency modulated to create four stimuli. We interpret the location of differences in activation by drawing comparisons between fMRI and human cytoarchitectonic data, reported in the same brain space. Harmonic tones produced more activation than single tones in right Heschl's gyrus (HG) and bilaterally in the lateral supratemporal plane (STP). Activation was also greater to frequency-modulated tones than to static tones in these areas, plus in left HG and bilaterally in an anterolateral part of the STP and the superior temporal sulcus. An elevated response magnitude to both frequency-modulated tones was found in the lateral portion of the primary area, and putatively in three surrounding non-primary regions on the lateral STP (one anterior and two posterior to HG). A focal site on the posterolateral STP showed an especially high response to the frequency-modulated harmonic tone. Our data highlight the involvement of both primary and lateral non-primary auditory regions
Renormalization of the Higgs sector in the triplet model
We study radiative corrections to the mass spectrum and the triple Higgs
boson coupling in the model with an additional Y=1 triplet field. In this
model, the vacuum expectation value for the triplet field is strongly
constrained from the electroweak precision data, under which characteristic
mass spectrum appear at the tree level; i.e., and , where the CP-even (), the CP-odd
() and the doubly-charged () as well as the singly-charged
() Higgs bosons are the triplet-like. We evaluate how the tree-level
formulae are modified at the one-loop level. The coupling for the
standard model-like Higgs boson () is also calculated at the one-loop level.
One-loop corrections to these quantities can be large enough for identification
of the model by future precision data at the LHC or the International Linear
Collider.Comment: Published version in Physics Letters
Recommended from our members
Functional magnetic resonance imaging measurements of sound-level encoding in the absence of background scanner noise
Effects of sound level on auditory cortical activation are seen in neuroimaging data. However, factors such as the cortical response to the intense ambient scanner noise and to the bandwidth of the acoustic stimuli will both confound precise quantification and interpretation of such sound-level effects. The present study used temporally "sparse" imaging to reduce effects of scanner noise. To achieve control for stimulus bandwidth, three schemes were compared for sound-level matching across bandwidth: component level, root-mean-square power and loudness. The calculation of the loudness match was based on the model reported by Moore and Glasberg [Acta Acust. 82, 335–345 (1996)]. Ten normally hearing volunteers were scanned using functional magnetic resonance imaging (fMRI) while listening to a 300-Hz tone presented at six different sound levels between 66 and 91 dB SPL and a harmonic-complex tone (F0 = 186 Hz) presented at 65 and 85 dB SPL. This range of sound levels encompassed all three bases of sound-level matching. Activation in the superior temporal gyrus, induced by each of the eight tone conditions relative to a quiet baseline condition, was quantified as to extent and magnitude. Sound level had a small, but significant, effect on the extent of activation for the pure tone, but not for the harmonic-complex tone, while it had a significant effect on the response magnitude for both types of stimulus. Response magnitude increased linearly as a function of sound level for the full range of levels for the pure tone
Lower Bounds on Charged Higgs Bosons from LEP and the TEVATRON
We point out that charged Higgs bosons can decay into final states different
than and , even when they are light enough to be
produced at LEPII or at the Tevatron, through top-quark decays. These
additional decay modes are overlooked in ongoing searches even though they
alter the existing lower bounds on the mass of charged Higgs bosons that are
present in supersymmetric and two Higgs doublets models.Comment: 9 pages, 4 figure
A set of equations for numerically calculating the interaural level difference in the horizontal plane
The variation of interaural level difference (ILD) with direction and frequency is particularly complex and convoluted. The purpose of this work was to determine a set of parametric equations that can be used to calculate ILDs continuously at any value of frequency and azimuth in the horizontal plane. They were derived by fitting equations to ILDs derived from the azimuthal-dependence data tabulated by Shaw and Vaillancourt [(1985). J. Acoust. Soc Am. 78, 1120–1123] and assuming left-right symmetry. The equations are shown to fit those data to an overall RMS error less than 0.5 dB
Probing the Majorana nature of TeV-scale radiative seesaw models at collider experiments
A general feature of TeV-scale radiative seesaw models, in which tiny
neutrino masses are generated via loop corrections, is an extended scalar
(Higgs) sector. Another feature is the Majorana nature; e.g., introducing
right-handed neutrinos with TeV-scale Majorana masses under the discrete
symmetry, or otherwise introducing some lepton number violating interactions in
the scalar sector. We study phenomenological aspects of these models at
collider experiments. We find that, while properties of the extended Higgs
sector of these models can be explored to some extent, the Majorana nature of
the models can also be tested directly at the International Linear Collider via
the electron-positron and electron-electron collision experiments.Comment: 19 pages, 7 figures, version published in Physics Letters
Recommended from our members
Binaural specialisation in human auditory cortex: an fMRI investigation of interaural correlation sensitivity
A listener's sensitivity to the interaural correlation (IAC) of sound plays an important role in several phenomena in binaural hearing. Although IAC has been examined extensively in neurophysiological studies in animals and in psychophysical studies in humans, little is known about the neural basis of sensitivity to IAC in humans. The present study employed functional magnetic resonance imaging to measure blood oxygen level-dependent (BOLD) activity in auditory brainstem and cortical structures in human listeners during presentation of band-pass noise stimuli between which IAC was varied systematically. The stimuli evoked significant bilateral activation in the inferior colliculus, medial geniculate body, and auditory cortex. There was a significant positive relationship between BOLD activity and IAC which was confined to a distinct subregion of primary auditory cortex located bilaterally at the lateral extent of Heschl's gyrus. Comparison with published anatomical data indicated that this area may also be cytoarchitecturally distinct. Larger differences in activation were found between levels of IAC near unity than between levels near zero. This response pattern is qualitatively compatible with previous measures of psychophysical and neurophysiological sensitivity to IAC
The Private Higgs
We introduce Higgs democracy in the Yukawa sector by constructing a model
with a private Higgs and a dark scalar for each fermion thus addressing the
large hierarchy among fermion masses. The model has interesting implications
for the LHC, while the Standard Model phenomenology is recovered at low
energies. We discuss some phenomenological implications such as FCNC, new
Higgses at the TeV scale and dark matter candidates.Comment: 8 pages, no figures. Version published in Phys. Lett.
Natural Two-Higgs-Doublet Model
We show that the Two-Higgs-Doublet Model (2HDM) constrained by the
two-loop-order requirement of cancellation of quadratic divergences is
consistent with the existing experimental constraints. The model allows to
ameliorate the little hierarchy problem by suppressing the quadratic
corrections to scalar masses and lifting the mass of the lightest Higgs boson.
A strong source of CP violation emerges from the scalar potential. The cutoff
originating from the naturality arguments is shifted from 0.6 TeV in the
Standard Model to >6 TeV in the 2HDM, depending on the mass of the lightest
scalar.Comment: 2 figures, submitted to Fortschritte der Physik, presented at the
10th Hellenic School on Elementary Particle Physics and Gravity, Corfu 201
On the possibility of a very light A^0 at low \tan\beta
The searches at LEP II for the processes e^+e^-\to h^0Z and e^+e^-\to h^0A^0
in the Minimal Supersymmetric Standard Model (MSSM) fail to exclude regions of
the m_h,m_A plane where \tan\beta <1, thus allowing a very light A^0 (m_A< 20
GeV). Such a parameter choice would predict a light H^\pm with m_{H^\pm}< m_W.
Although the potentially large branching ratio for H^\pm \to A^0 W^* would
ensure that H^\pm also escaped detection in direct searches at LEP II and the
Tevatron Run I, we show that this elusive parameter space is overwhelmingly
disfavoured by electroweak precision measurements.Comment: 11 pages, 2 figures, Revtex, references added, minor additions to
tex
- …