A closer look at string resonances in dijet events at the LHC

The first string excited state can be observed as a resonance in dijet invariant mass distributions at the LHC, if the scenario of low-scale string with large extra dimensions is realized. A distinguished property of the dijet resonance by string excited states from that the other "new physics" is that many almost degenerate states with various spin compose a single resonance structure. It is examined that how we can obtain evidences of low-scale string models through the analysis of angular distributions of dijet events at the LHC. Some string resonance states of color singlet can obtain large mass shifts through the open string one-loop effect, or through the mixing with closed string states, and the shape of resonance structure can be distorted. Although the distortion is not very large (10% for the mass squared), it might be able to observe the effect at the LHC, if gluon jets and quark jets could be distinguished in a certain level of efficiency.Comment: 12 pages, 8 figure

Interaction of reed and acoustic resonator in clarinetlike systems

Sound emergence in clarinetlike instruments is investigated in terms of instability of the static regime. Various models of reed-bore coupling are considered, from the pioneering work of Wilson and Beavers ["Operating modes of the clarinet", J. Acoust. Soc. Am. 56, 653--658 (1974)] to more recent modeling including viscothermal bore losses and vena contracta at the reed inlet. The pressure threshold above which these models may oscillate as well as the frequency of oscillation at threshold are calculated. In addition to Wilson and Beavers' previous conclusions concerning the role of the reed damping in the selection of the register the instrument will play on, the influence of the reed motion induced flow is also emphasized, particularly its effect on playing frequencies, contributing to reduce discrepancies between Wilson and Beavers' experimental results and theory, despite discrepancies still remain concerning the pressure threshold. Finally, analytical approximations of the oscillating solution based on Fourier series expansion are obtained in the vicinity of the threshold of oscillation. This allows to emphasize the conditions which determine the nature of the bifurcation (direct or inverse) through which the note may emerge, with therefore important consequences on the musical playing performances

Cosmic Rays and Large Extra Dimensions

We have proposed that the cosmic ray spectrum "knee", the steepening of the cosmic ray spectrum at energy E \gsim 10^{15.5} eV, is due to "new physics", namely new interactions at TeV cm energies which produce particles undetected by the experimental apparatus. In this letter we examine specifically the possibility that this interaction is low scale gravity. We consider that the graviton propagates, besides the usual four dimensions, into an additional $\delta$, compactified, large dimensions and we estimate the graviton production in $p p$ collisions in the high energy approximation where graviton emission is factorized. We find that the cross section for graviton production rises as fast as $(\sqrt{s}/M_f)^{2+\delta}$, where $M_f$ is the fundamental scale of gravity in $4+\delta$ dimensions, and that the distribution of radiating a fraction $y$ of the initial particle's energy into gravitational energy (which goes undetected) behaves as $\delta y^{\delta -1}$. The missing energy leads to an underestimate of the true energy and generates a break in the {\sl inferred} cosmic ray spectrum (the "kne"). By fitting the cosmic ray spectrum data we deduce that the favorite values for the parameters of the theory are $M_f \sim 8$ TeV and $\delta =4$.Comment: 8 pages, 1 figur

Microwave sensors for in situ monitoring of trace metals in polluted water

Thousands of pollutants are threatening our water supply, putting at risk human and environmental health. Between them, trace metals are of significant concern, due to their high toxicity at low concentrations. Abandoned mining areas are globally one of the major sources of toxic metals. Nowadays, no method can guarantee an immediate response for quantifying these pollutants. In this work, a novel technique based on microwave spectroscopy and planar sensors for in situ real-time monitoring of water quality is described. The sensors were developed to directly probe water samples, and in situ trial measurements were performed in freshwater in four polluted mining areas in the UK. Planar microwave sensors were able to detect the water pollution level with an immediate response specifically depicted at three resonant peaks in the GHz range. To the authors' best knowledge, this is the first time that planar microwave sensors were tested in situ, demonstrating the ability to use this method for classifying more and less polluted water using a multiple-peak approach

TeV Strings and the Neutrino-Nucleon Cross Section at Ultra-high Energies

In scenarios with the fundamental unification scale at the TeV one expects string excitations of the standard model fields at accessible energies. We study the neutrino-nucleon cross section in these models. We show that duality of the scattering amplitude forces the existence of a tower of massive leptoquarks that mediate the process in the s-channel. Using the narrow-width approximation we find a sum rule for the production rate of resonances with different spin at each mass level. We show that these contributions can increase substantially the standard model neutrino-nucleon cross section, although seem insufficient in order to explain the cosmic ray events above the GZK cutoff energy.Comment: 10 pages, 1 figure, version to appear in PR

A non-linear optimal estimation inverse method for radio occultation measurements of temperature, humidity and surface pressure

An optimal estimation inverse method is presented which can be used to retrieve simultaneously vertical profiles of temperature and specific humidity, in addition to surface pressure, from satellite-to-satellite radio occultation observations of the Earth's atmosphere. The method is a non-linear, maximum {\it a posteriori} technique which can accommodate most aspects of the real radio occultation problem and is found to be stable and to converge rapidly in most cases. The optimal estimation inverse method has two distinct advantages over the analytic inverse method in that it accounts for some of the effects of horizontal gradients and is able to retrieve optimally temperature and humidity simultaneously from the observations. It is also able to account for observation noise and other sources of error. Combined, these advantages ensure a realistic retrieval of atmospheric quantities. A complete error analysis emerges naturally from the optimal estimation theory, allowing a full characterisation of the solution. Using this analysis a quality control scheme is implemented which allows anomalous retrieval conditions to be recognised and removed, thus preventing gross retrieval errors. The inverse method presented in this paper has been implemented for bending angle measurements derived from GPS/MET radio occultation observations of the Earth. Preliminary results from simulated data suggest that these observations have the potential to improve NWP model analyses significantly throughout their vertical range.Comment: 18 (jgr journal) pages, 7 figure

Compact Hyperbolic Extra Dimensions: Branes, Kaluza-Klein Modes and Cosmology

We reconsider theories with low gravitational (or string) scale M_* where Newton's constant is generated via new large-volume spatial dimensions, while Standard Model states are localized to a 3-brane. Utilizing compact hyperbolic manifolds (CHM's) we show that the spectrum of Kaluza-Klein (KK) modes is radically altered. This allows an early universe cosmology with normal evolution up to substantial temperatures, and completely negates the constraints on M_* arising from astrophysics. Furthermore, an exponential hierarchy between the usual Planck scale and the true fundamental scale of physics can emerge with only order unity coefficients. The linear size of the internal space remains small. The proposal has striking testable signatures.Comment: 4 pages, no figure

Neutrino-Induced Giant Air Showers in Large Extra Dimension Models

In models based on large extra dimensions where massive spin 2 exchange can dominate at high energies, the neutrino-proton cross section can rise to typical hadronic values at energies above 10^20 eV. The neutrino then becomes a candidate for the primary that initiates the highest energy cosmic ray showers. We investigate characteristics of neutrino-induced showers compared to proton-induced showers. The comparison includes study of starting depth, profile with depth, lateral particle distribution at ground and muon lateral distribution at ground level. We find that for cross sections above 20 mb there are regions of parameter space where the two types of showers are essentially indistinguishable. We conclude that the neutrino candidate hypothesis cannot be ruled out on the basis of shower characteristics.Comment: 24 pages, latex, 19 figures; text discussion and references added, typos corrected; figures and conclusions unchange