On the relation between boundary proposals and hidden symmetries of the extended pre-big bang quantum cosmology

A framework associating quantum cosmological boundary conditions to minisuperspace hidden symmetries has been introduced in \cite{7}. The scope of the application was, notwithstanding the novelty, restrictive because it lacked a discussion involving realistic matter fields. Therefore, in the herein letter, we extend the framework scope to encompass elements from a scalar-tensor theory in the presence of a cosmological constant. More precisely, it is shown that hidden minisuperspace symmetries present in a pre-big bang model suggest a process from which boundary conditions can be selected.Comment: 15 pages, no figures, to appear in European Physical Journal

Evaluation of the growth potential of Paulownia furtunei in Guilan Province

Paulownia furtunei is a fast-growing tree which under optimal conditions can produce useful timber in five to six years. The wood of this species has properties suited for a variety of applications. This species is highly adaptable with regard to planting site, and is widely distributed. Its natural distribution ranges from tropical through to temperate climates. P. furtunei is cultivated in many locations including in the Golestan Province of Northern Iran. To evaluate diameter and height growth potential of P. furtunei in Guilan in order to use this species in forest farming or cultivated forests with the purpose of rapid exploitation of timber in Guilan Province, an area of about 3000 m2 was selected in Shanderman Nursery and was planted at a 4 m by 4 m spacing. The diameter at breast height (dbh) and total height were measured after planting and again in the second and third year to estimate diameter and height growth potential and some important characteristics were analyzed. Growth measurements will be continued for at least five or six years. The dbh and height annual increment of P. fortunei were 3.24 cm and 1.88 m in the second year and 4.87 cm and 3.23 m in the third year, respectively. The mean dbh and annual height increment were 4.12 cm and 2.61 m up to the third year. A parabloid relationship between height and dbh was estimated. If the current growth rate continues, it seems that growth of P. fortunei in Guilan Province is suitable and comparable to its natural distribution areas

EFT Compatible PBHs: Effective Spawning of the Seeds for Primordial Black Holes during Inflation

Most of the inflationary scenarios that try to explain the origin of Primordial Black Holes (PBHs) from the enhancements of the power spectrum to values of order one, at the relevant scales, run into clashes with the Effective Field Theory (EFT) criteria or fail to enhance the power spectrum to such large amplitudes. In this paper, we unravel a mechanism for enhancing the power spectrum during inflation that does not use the flattening of the potential or reduction of the sound speed of scalar perturbations. The mechanism is based on this observation in the formalism of Extended EFT of inflation (EEFToI) with the sixth order polynomial dispersion relation for scalar perturbations that if the quartic coefficient in the dispersion relation is negative and smaller than a certain threshold, the amplitude of the power spectrum is enhanced substantially. The instability mechanism must arrange to kick in at the scales of interest related to the mass of the PBHs one would like to produce, which can be ten(s) of solar mass PBHs, suitable for LIGO events, or $10^{-17}-10^{-13}$ solar mass PBHs, which can comprise the whole dark matter energy density. We argue that the strong coupling is avoided for the range of parameters that the mechanisms enhance the power spectrum to the required amount.Comment: v1:1+18 pages, 5 figures; v2: 1+21 pages, 5 figures, matched the JHEP versio