Moving sources in a ghost condensate

Ghost condensation has been recently proposed as a mechanism inducing the spontaneous breaking of Lorentz symmetry. Corrections to the Newton potential generated by a static source have been computed: they yield a limit M < 10 MeV on the symmetry breaking scale, and - if the limit is saturated - they are maximal at a distance L ~ 1000 km from the source. However, these corrections propagate at a tiny velocity, v_s ~ 10^{-12} m/s, many orders of magnitude smaller than the velocity of any plausible source. We compute the gravitational potential taking the motion of the source into account: the standard Newton law is recovered in this case, with negligible corrections for any distance from the source up to astrophysical scales. Still, the vacuum of the theory is unstable, and requiring stability over the lifetime of the Universe gives a limit for M which is not too far from the one given above. In the absence of a direct coupling of the ghost to matter, signatures of this model will have to be searched in the form of exotic astrophysical events.Comment: 13 page

Domain wall generation by fermion self-interaction and light particles

A possible explanation for the appearance of light fermions and Higgs bosons on the four-dimensional domain wall is proposed. The mechanism of light particle trapping is accounted for by a strong self-interaction of five-dimensional pre-quarks. We obtain the low-energy effective action which exhibits the invariance under the so called \tau-symmetry. Then we find a set of vacuum solutions which break that symmetry and the five-dimensional translational invariance. One type of those vacuum solutions gives rise to the domain wall formation with consequent trapping of light massive fermions and Higgs-like bosons as well as massless sterile scalars, the so-called branons. The induced relations between low-energy couplings for Yukawa and scalar field interactions allow to make certain predictions for light particle masses and couplings themselves, which might provide a signature of the higher dimensional origin of particle physics at future experiments. The manifest translational symmetry breaking, eventually due to some gravitational and/or matter fields in five dimensions, is effectively realized with the help of background scalar defects. As a result the branons acquire masses, whereas the ratio of Higgs and fermion (presumably top-quark) masses can be reduced towards the values compatible with the present-day phenomenology. Since the branons do not couple to fermions and the Higgs bosons do not decay into branons, the latter ones are essentially sterile and stable, what makes them the natural candidates for the dark matter in the Universe.Comment: 34 pages, 2 figures, JHEP style,few important refs. adde

Виртуальный скрининг и идентификация потенциальных ингибиторов ВИЧ-1 на основе кросс-реактивного нейтрализующего антитела N6

Six potential peptidomimetics of the cross-reactive neutralizing anti-HIV-1 antibody N6 that are able to mimic the pharmacophoric features of this immunoglobulin by specific and effective interactions with the CD4-binding site of the viral gp120 protein were identified by virtual screening and molecular modeling. The key role in the interaction of these compounds with gp120 is shown to play multiple van der Waals contacts with conserved residues of the gp120 Phe43 cavity critical for the HIV binding to cellular receptor CD4, as well as hydrogen bonds with Asp-368gp120 that increase the chemical affinity without activating unwanted allosteric effect. According to the data of molecular dynamics, the complexes of the identified ligands with gp120 are energetically stable and show the lower values of binding free energy compared with the HIV-1 inhibitors NBD-11021 and DMJ-II-121 used in the calculations as a positive control. The identified compounds may be involved in the design of novel antiviral drugs presenting HIV-1 inhibitors that block the early stages of the development of HIV infection.Методами виртуального скрининга и молекулярного моделирования идентифицированы 6 потенциальных пептидомиметиков кросс-реактивного нейтрализующего анти-ВИЧ-1 антитела N6, способных имитировать фармакофорные свойства этого иммуноглобулина путем специфических и эффективных взаимодействий с CD4-связывающим сайтом белка gp120 оболочки вируса. Показано, что ключевую роль во взаимодействии этих соединений с белком gp120 играют многочисленные ван-дер-ваальсовы контакты с консервативными остатками Phe43-полости гликопротеина, критическими для связывания ВИЧ-1 с клеточным рецептором CD4, а также водородные связи с остатком Asp-368gp120, образование которых увеличивает химическое сродство без активации нежелательного аллостерического эффекта. Согласно данным молекулярной динамики, комплексы обнаруженных лигандов с белком gp120 энергетически стабильны и характеризуются более низкими значениями свободной энергии связывания по сравнению с ингибиторами ВИЧ-1 NBD-11021 и DMJ-II-121, использованными в расчетах в качестве контрольных соединений. Идентифицированные соединения могут быть использованы в работах по созданию новых противовирусных препаратов – ингибиторов проникновения ВИЧ-1, блокирующих ранние стадии развития ВИЧ-инфекции

QCD and strongly coupled gauge theories : challenges and perspectives

We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to strongly coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.Peer reviewe