Muon production in low-energy electron-nucleon and electron-nucleus scattering

Recently, muon production in electron-proton scattering has been suggested as a possible candidate reaction for the identification of lepton-flavor violation due to physics beyond the Standard Model. Here we point out that the Standard-Model processes $e^- p \to \mu^- p \bar{\nu}_\mu \nu_e$ and $e^- p \to e^- n \mu^+ \nu_\mu$ can cloud potential beyond-the-Standard-Model signals in electron-proton collisions. We find that Standard-Model $e p \to \mu X$ cross sections exceed those from lepton-flavor-violating operators by several orders of magnitude. We also discuss the possibility of using a nuclear target to enhance the $e p \to \mu X$ signal.Comment: 24 pages. Additional figure showing energy-dependence of total cross section, minor changes to text. Conclusions unaltered. This version to appear in Physical Review

Neutrino Pair Emission from Cooper Pair Breaking and Recombination in Superfluid Quark Matter

For the low energy Standard Model neutrino-matter interactions, we calculate neutrino pair ($\nu\bar\nu$) emissivites in superfluid quark matter. Just below the critical temperature, Cooper pairs continuously break and recombine, resulting in the emission of $\nu\bar \nu$ pairs with a rate that greatly exceeds the standard quark modified Urca and bremsstrahlung rates. At the same baryon density in baryonic and quark matter, the ratio of baryon to quark $\nu\bar\nu$ emissivites lies in the range 2-5 for the densities of interest in the long-term cooling of solar mass compact stars. We also find that in matter containing hyperons, $\nu\bar\nu$ emission can occur with hyperons of all species.Comment: 10 pages, no figure

Neutrino Emission from Goldstone Modes in Dense Quark Matter

We calculate neutrino emissivities from the decay and scattering of Goldstone bosons in the color-flavor-locked (CFL) phase of quarks at high baryon density. Interactions in the CFL phase are described by an effective low-energy theory. For temperatures in the tens of keV range, relevant to the long-term cooling of neutron stars, the emissivities involving Goldstone bosons dominate over those involving quarks, because gaps in the CFL phase are $\sim 100$ MeV while the masses of Goldstone modes are on the order of 10 MeV. For the same reason, the specific heat of the CFL phase is also dominated by the Goldstone modes. Notwithstanding this, both the emissivity and the specific heat from the massive modes remain rather small, because of their extremely small number densities. The values of the emissivity and the specific heat imply that the timescale for the cooling of the CFL core in isolation is $\sim 10^{26}$ y, which makes the CFL phase invisible as the exterior layers of normal matter surrounding the core will continue to cool through significantly more rapid processes. If the CFL phase appears during the evolution of a proto-neutron star, neutrino interactions with Goldstone bosons are expected to be significantly more important since temperatures are high enough ($\sim 20-40$ MeV) to admit large number densities of Goldstone modes.Comment: 29 pages, no figures. slightly modified text, one new eqn. and new refs. adde

Evaluation of Manual and Two-Rotary Niti Retreatment Systems in Removing Gutta-Percha Obturated with Two Root Canal Sealers

Objective. The objective of this study was to evaluate the efficacy of two retreatment NiTi systems (protaper universal retreatment files, R-Endo), when compared to manual technique in removing Gutta-percha obturated with two sealers. Study Design. Sixty extracted single-rooted premolars were instrumented with Protaper rotary files till F3. The specimens were divided into six groups. Groups 1, 2, 3 were obturated with Gutta-percha and zinc oxide eugenol and Groups 4, 5, 6 were obturated with Gutta-percha and AH-plus. The retreatment was carried out in groups 1 and 4 with H-files and GGdrills, groups 2 and 5 with R-endo retreatment files and groups 3 and 6 with Protaper retreatment files. The roots were sectioned and evaluated under optical stereomicroscope. Statistical analysis was performed with one-way ANOVA and Newman-Keul's test at . Results. The manual technique resulted in cleaner canal walls when compared with both rotary retreatment systems. Conclusion. NiTi rotary retreatment files can be used to remove the filling material quickly, but it should be followed by hand instruments to obtain better canal wall cleanliness.</jats:p

Simulation of Critical Settling Velocity of Gas Hydrate Slurries

Gas hydrates are composed of water molecules forming interlinked cage-like structures that encase small guest molecules, such as small hydrocarbons, carbon dioxide, nitrogen, and others. This thesis addresses their significance, particularly their role in causing plugging issues within offshore hydrocarbon production flowlines. Despite their importance, the coupling of multiphase flow with gas hydrates has only recently garnered attention. A crucial aspect is the determination of critical settling velocities, which have been developed for materials with high solid-to-liquid density ratios that do not correspond to gas hydrate scenarios. To bridge this research gap, this work introduces an Euler-Euler approach to simulate the stability of gas hydrate slurries. The simulations conducted in this study focus on a pipe diameter of 10.2 mm, monodispersed methane hydrate particles with a size of 50 μm, and a density of 910 kg/m3, flowing in a water medium. The accuracy of the model is assessed through replication and validation against existing literature data for sand particles and then extrapolated for gas hydrates. Three empirical engineering models for critical settling velocity are compared to the generated simulation dataset. While they align well with the behavior of slurries containing sand, the models deviate for gas hydrates. Refitting of these three models within ranges applicable to gas hydrates is proposed in this study. This research represents a significant step forward in enhancing the ability to predict and mitigate plugging risks associated with gas hydrates in hydrocarbon production, ultimately contributing to improved operational efficiency and safety in the industry

Interim Restorative Approach for the Management of Congenitally Missing Permanent Mandibular Incisors: Presentation of Three Cases

Congenital missing of mandibular permanent incisors with retained primary incisors may jeopardize the esthetic appearance and psychological development of children, especially during the years of transition into adolescence. The retained primary teeth are necessary for the maintenance and normal development of alveolar bone, which in turn is essential for future definitive rehabilitation. In such situations, an interim restoration may be provided before any definitive treatment is given to comfort the young patient during this transition period. Interim restorations may include resin-modified additions to the existing teeth as well as more sophisticated restorations such as resin-retained bridge and removable partial dentures. However, this restoration differs for different clinical situations based on various factors such as age and patient compliance, and also consideration has to be given for the growth changes of the child. The aim of this present paper is to discuss the esthetic management of three cases with bilateral agenesis of permanent mandibular incisors and retained primary incisors with composite interim restoration