Lunar surface holography experiment instrument feasibility demonstration Final report, 27 Jul. - 30 Nov. 1970

Prototype holocamera and playback system for lunar surface holography experimen

The role of secondary Reggeons in central meson production

We estimate the contribution of f_2 trajectory exchange to the central \eta and \eta^\prime production. It is shown that secondary Reggeons may give a large contribution to processes of double diffractive meson production at high energy.Comment: 7 pages, Latex, 5 figure

Equivalent variational approaches to biaxial liquid crystal dynamics

Within the framework of liquid crystal flows, the Qian & Sheng (QS) model for Q-tensor dynamics is compared to the Volovik & Kats (VK) theory of biaxial nematics by using Hamilton's variational principle. Under the assumption of rotational dynamics for the Q-tensor, the variational principles underling the two theories are equivalent and the conservative VK theory emerges as a specialization of the QS model. Also, after presenting a micropolar variant of the VK model, Rayleigh dissipation is included in the treatment. Finally, the treatment is extended to account for nontrivial eigenvalue dynamics in the VK model and this is done by considering the effect of scaling factors in the evolution of the Q-tensor.Comment: 8 pages. Third versio

An Explanation of the Very Low Radio Flux of Young Planet-mass Companions

We report Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm continuum upper limits for 5 planetary-mass companions DH Tau B, CT Cha B, GSC 6214-210 B, 1RXS 1609 B, and GQ Lup B. Our survey, together with other ALMA studies, have yielded null results for disks around young planet-mass companions and placed stringent dust mass upper limits, typically less than 0.1 M_earth, when assuming dust continuum is optically thin. Such low-mass gas/dust content can lead to a disk lifetime estimate (from accretion rates) much shorter than the age of the system. To alleviate this timescale discrepancy, we suggest that disks around wide companions might be very compact and optically thick, in order to sustain a few Myr of accretion yet have very weak (sub)millimeter flux so as to still be elusive to ALMA. Our order-of-magnitude estimate shows that compact optically-thick disks might be smaller than 1000 R_jup and only emit ~micro-Jy of flux in the (sub)millimeter, but their average temperature can be higher than that of circumstellar disks. The high disk temperature could impede satellite formation, but it also suggests that mid- to far-infrared might be more favorable than radio wavelengths to characterize disk properties. Finally, the compact disk size might imply that dynamical encounters between the companion and the star, or any other scatterers in the system, play a role in the formation of planetary-mass companions.Comment: Accepted for publication in A

Sea-quark effects in the pion charge form factor

It is shown that the data on the pion charge form factor admit the possibility for a substantial sea-quark components in the pion wave function. If the charge form factor is calculated with instant form kinematics in a constituent quark model that is extended to include explicit $(q\bar q)^2$ components in the pion wave function, that component will give the dominant contribution to the calculated $\pi^+$ charge form factor at large values of momentum transfer. The present experimental values $Q^2$ can be described well with $(q\bar q)^2$ component admixtures of up to 50%. The sensitivity of the calculated $\pi^+$ charge form factor to whether one of the quarks or one of the antiquarks is taken to be in the P-state is small.Comment: 14 page

Evaluation of valued youth: a national peer-tutoring programme to increase self confidence and motivation

Established first in the USA, Valued Youth has operated in the UK since 1996, and is currently implemented in about 50 schools in 8 regions. The programme is intended to help secondary school students who are at risk of disengaging with school or underperforming for a variety of reasons. These students are selected as tutors, given training on how to work with younger children and placed in a local primary school where they support pupils' learning. Valued Youth can be seen as one of many initiatives in secondary schools on re-engagement in learning and contributes to the UK government strategy of extending opportunities and providing flexible learning experiences to meet individual learners' needs and aptitudes. Evidence from the USA has shown the value of the programme in reducing drop-out, strengthening youngsters' perceptions of self and school, and reducing disciplinary referrals and absenteeism. The evaluation discussed in this paper considers the effect of the programme in a UK context, not only in terms of young people's attendance, attainment and confidence, but also in terms of what sort of youngsters seem to benefit and the effects of financial rewards, if any, on the outcomes. The paper reports on the first year of a two-year evaluation. Data were obtained from a pre- and post-questionnaire survey among tutors, a workshop with coordinators and visits to selected case study schools in several regions. Almost all tutors enjoyed the programme and would recommend the experience to others. There was a relatively low dropout and the programme was warmly appreciated by participating primary schools. We have evidence that Valued Youth markedly raises confidence, improves communication skills and keeps some at risk youngsters on track in school. Many types of youngsters benefit from the experience; those who lack confidence and have poor communication skills seem to make the most progress. Successful tutors tend to be those who are committed to the programme, willing to learn, are flexible and cooperative, and have some ability to interact with others, particularly children and primary teachers.</p

Four-Quark Mesons in Non-leptonic B Decays--Could They Resolve Some Old Puzzles?

We point out that non-leptonic B decays driven by b-->ccbar s should provide a favourable environment for the production of hidden charm diquark-antidiquark bound states that have been suggested to explain the resonances with masses around 4 GeV recently observed by BaBar and BELLE. Studying their relative abundances in non-leptonic B decays can teach us novel lessons about their structure and the strong interactions. Through their decay into psi they can provide a natural explanation of the excess of B-->psi X observed for p_psi < 1 GeV. Other phenomenological consequences are mentioned as well.Comment: 6 pages, 2 figures, revte

Open-charm meson spectroscopy

We present a theoretical framework that accounts for the new $D_J$ and $D_{sJ}$ mesons measured in the open-charm sector. These resonances are properly described if considered as a mixture of conventional $P-$wave quark-antiquark states and four-quark components. The narrowest states are basically $P-$wave quark-antiquark mesons, while the dominantly four-quark states are shifted above the corresponding two-meson threshold, being broad resonances. We study the electromagnetic decay widths as basic tools to scrutiny their nature. The proposed explanation incorporates in a natural way the most recently discovered mesons in charmonium spectroscopy.Comment: 15 pages, 5 tables. Accepted for publication in Phys. Rev.