Extracting the wavefunction of the LSP at the LHC

We consider associated production of squarks and gluinos with the lightest supersymmetric particle (LSP), or states nearly degenerate in mass with it. Though sub-dominant to pair production of color SU(3)-charged superpartners, these processes are directly sensitive to the wavefunction composition of the lightest neutralinos. Exploiting event-shape variables - including some introduced here for the first time - we are able to identify the composition of the LSP by selecting events involving a single high-pT jet recoiling against missing transverse energy. We illustrate the proposed technique on a set of benchmark cases and propose methods for applying these results in more realistic experimental environments.     

Observation of eta'c production in gammagamma fusion at CLEO

We report on the observation of the eta(')(c)(2(1)S0), the radial excitation of the eta(c)(1(1)S0) ground state of charmonium, in the two-photon fusion reaction gammagamma-->eta(')(c)-->K(0)(S)K+/-pi(-/+) in 13.6 fb(-1) of CLEO II/II.V data and 13.1 fb(-1) of CLEO III data. We obtain M(eta(')(c))=3642.9+/-3.1(stat)+/-1.5(syst) MeV and M(eta(c))=2981.8+/-1.3(stat)+/-1.5(syst) MeV. The corresponding values of hyperfine splittings between 1S0 and 3S1 states are DeltaM(hf)(1S)=115.1+/-2.0 MeV and DeltaM(hf)(2S)=43.1+/-3.4 MeV. Assuming that the eta(c) and eta(')(c) have equal branching fractions to K(S)Kpi, we obtain Gamma(gammagamma)(eta(')(c))=1.3+/-0.6 keV.     

Neutrino oscillations as a probe of dark energy

We consider a class of theories in which neutrino masses depend significantly on environment, as a result of interactions with the dark sector. Such theories of mass varying neutrinos were recently introduced to explain the origin of the cosmological dark energy density and why its magnitude is apparently coincidental with that of neutrino mass splittings. In this Letter we argue that in such theories neutrinos can exhibit different masses in matter and in vacuum, dramatically affecting neutrino oscillations. As an example of modifications to the standard picture, we consider simple models that may simultaneously account for the LSND anomaly, KamLAND, K2K, and studies of solar and atmospheric neutrinos, while providing motivation to continue to search for neutrino oscillations in short baseline experiments such as BooNE.     

Nature of the pygmy resonance in continuous <Emphasis Type="Italic">γ</Emphasis> spectra

Two-step-cascade spectra of the ¹⁷¹Yb(n, γγ)¹⁷²Yb reaction have been measured using thermal neutrons. They are compared to calculations based on experimental values of the level density and radiative strength function obtained from the ¹⁷³Yb(³He, aγ)¹⁷²Yb reaction. The multipolarity of a 6.5(15) μ _N ² resonance at 3.3(1) MeV in the strength function is determined to be M1 by this comparison.     

Local control of electric current driven shell etching of multiwalled carbon nanotubes

We report on a novel method for local control of shell engineering in multiwalled carbon nanotubes (MWNTs) using Joule-heating induced electric breakdown. By modulating the heat dissipation along a nanotube, we can confine its thinning and shell breakdown to occur within localized regions of peak temperatures, which are distributed over one-half of the NT length. The modulation is achieved by using suitably designed nanomachined heat sinks with different degrees of thermal coupling at different parts of a current-carrying nanotube. The location of electric breakdown occurs precisely at the regions of high temperatures predicted by the classical finite-element model of Joule heating in the MWNT. The experiments herein provide new insight into the electric breakdown mechanism and prove unambiguously that shell removal occurs due to thermal stress, underpinning the diffusive nature of MWNTs. The method demonstrated here has the potential to be a powerful tool in realizing MWNT bearings with complex architectures for use in integrated nanoelectromechanical systems (NEMS). In addition, the breakdown current and power in the nanotubes are significantly higher than those observed in nanotubes without heat removal via additional heat sinks. This indicates future avenues for enhancing the performance of MWNTs in electrical interconnect and nanoelectronic applications. PACS  73.63.Fg; 65.80.+n     

Behavioral Characteristics of Children With Vocal Fold Nodules

Vocal fold nodules (VNs) in children are benign, bilateral lesions occurring on the mid-membranous vocal folds. Repetitive phonotraumatic behavior leading to chronic vocal fold injury and repair is frequently cited as the primary etiology; however, specific behavioral characteristics may predispose some children toward intense and potentially phonotraumatic voice use, thereby contributing secondarily to VN formation. The purpose of this case-control study was to determine whether children with VNs possess unique behavioral characteristics that may predispose them to VN development. Parents of 26 children with VNs (20 boys, 6 girls, mean age=7.2 years, SD=2.5 years), and 29 vocally normal, medical controls (22 boys, 7 girls, mean age=6.7 years, SD=2.4), completed the Childhood Behavior Checklist (CBCL/4-18, Achenbach, 1991), a standardized parent-rating scale with strong psychometric properties. No significant between-group differences were detected on any of the behavior problem syndrome scales. Group differences approached significance for the individual items "screams a lot" and "teases a lot" (VN group > Controls). The VN group scored significantly higher than the controls on the "Social Scale," a compilation of positive ratings of the child's social activity, frequency of contacts with friends, behavior with others, and behavior by themselves. Observed outcomes were consistent with previous characterizations of children with VN as "outgoing" or "extroverted" but were not consistent with other claims that this population may be at risk for "aggressive," "attentional," or "impulsive" behavior problems.     

Baryogenesis via leptogenesis in multi-field inflation

In multi-field reheating after modular j-inflation we investigate the conditions under which baryogenesis via non-thermal leptogenesis can be successfully realized. We introduce three heavy right-handed neutrinos to the non-supersymmetric Standard Model of particle physics, assuming hierarchical neutrino masses. Considering a typical mass for the first right-handed neutrino of the order of \(10^{11}\) GeV, suggested from the seesaw mechanism and also from concrete SO(10) grand unification models, we obtain the allowed parameter space for viable baryogenesis. An upper bound for the inflaton mass as well as a lower bound for its branching ratio to the pair of lightest right-handed neutrinos are found and reported.     

Field expulsion and reconfiguration in polaritonic photonic crystals

We uncover a rich set of optical phenomena stemming from the incorporation of polar materials exhibiting transverse phonon polariton excitations into a photonic crystal structure. We identify in the frequency spectrum two regimes in which the dielectric response of the polaritonic medium can induce extreme localization of the electromagnetic energy. Our analysis of the effect of polarization and the interaction between the polariton and photonic band gaps on the Bloch states leads to a pair of mechanisms for sensitive frequency-controlled relocation and/or reconfiguration of the fields.