Late Phase Transition Research Articles

Formation and Abundance of Late-forming Primordial Black Holes as Dark Matter

We propose a novel mechanism where primordial black hole (PBH) dark matter is formed much later in the history of the universe, between the epochs of Big Bang nucleosynthesis and cosmic microwave background photon decoupling. In our setup, one does not need to modify the scale-invariant inflationary power spectra; instead, a late-phase transition in a strongly interacting fermion–scalar fluid (which occurs naturally around redshift 106 ≤ z T ≤ 108) creates an instability in the density perturbation as the sound speed turns imaginary. As a result, the dark matter perturbation grows exponentially in sub-Compton scales. This follows the immediate formation of an early dense dark matter halo, which finally evolves into PBHs due to cooling through scalar radiation. We calculate the variance of the density perturbations and the PBH fractional abundances f(M) by using a nonmonochromatic mass function. We find that the peak of our PBH mass function lies between 10−16 and 10−14 solar mass for z T ≃ 106, and thus that it can constitute the entire dark matter of the universe. In PBH formation, one would expect a temporary phase where an attractive scalar balances the Fermi pressure. We numerically confirm that such a state indeed exists, and we find the radius and density profile of the temporary static structure of the dark matter halo, which finally evolves into PBHs due to cooling through scalar radiation.

Gravitational wave induced baryon acoustic oscillations

We study the impact of gravitational waves originating from a first order phase transition on structure formation. To do so, we perform a second order perturbation analysis in the 1+31+3 covariant framework and derive a wave equation in which second order, adiabatic density perturbations of the photon-baryon fluid are sourced by the gravitational wave energy density during radiation domination and on sub-horizon scales. The scale on which such waves affect the energy density perturbation spectrum is found to be proportional to the horizon size at the time of the phase transition times its inverse duration. Consequently, structure of the size of galaxies and bigger can only be affected in this way by relatively late phase transitions at \ge 10^{6}\,\text{s}≥106s. Using cosmic variance as a bound we derive limits on the strength \alphaα and the relative duration (\beta/H_*)^{-1}(β/H*)−1 of phase transitions as functions of the time of their occurrence which results in a new exclusion region for the energy density in gravitational waves today. We find that the cosmic variance bound forbids only relative long lasting phase transitions, e.g. \beta/H_*\lesssim 6.8β/H*≲6.8 for t_*\approx 5\times10^{11}\,\text{s}t*≈5×1011s, which exhibit a substantial amount of supercooling \alpha>20α>20 to affect the matter power spectrum.

A Cdk4/6-dependent phosphorylation gradient regulates the early to late G1 phase transition

During early G1 phase, Rb is exclusively mono-phosphorylated by cyclin D:Cdk4/6, generating 14 different isoforms with specific binding patterns to E2Fs and other cellular protein targets. While mono-phosphorylated Rb is dispensable for early G1 phase progression, interfering with cyclin D:Cdk4/6 kinase activity prevents G1 phase progression, questioning the role of cyclin D:Cdk4/6 in Rb inactivation. To dissect the molecular functions of cyclin D:Cdk4/6 during cell cycle entry, we generated a single cell reporter for Cdk2 activation, RB inactivation and cell cycle entry by CRISPR/Cas9 tagging endogenous p27 with mCherry. Through single cell tracing of Cdk4i cells, we identified a time-sensitive early G1 phase specific Cdk4/6-dependent phosphorylation gradient that regulates cell cycle entry timing and resides between serum-sensing and cyclin E:Cdk2 activation. To reveal the substrate identity of the Cdk4/6 phosphorylation gradient, we performed whole proteomic and phospho-proteomic mass spectrometry, and identified 147 proteins and 82 phospho-peptides that significantly changed due to Cdk4 inhibition in early G1 phase. In summary, we identified novel (non-Rb) cyclin D:Cdk4/6 substrates that connects early G1 phase functions with cyclin E:Cdk2 activation and Rb inactivation by hyper-phosphorylation.

EFT interpretation of XENON1T electron recoil excess: Neutrinos and dark matter

We scrutinize the XENON1T electron recoil excess in the scalar-singlet-extended dark matter effective field theory. We confront it with various astrophysical and laboratory constraints both in a general setup and in the more specific, recently proposed, variant with leptophilic $Z_2$-odd mediators. The latter also provide mass to the light leptons via suppressed $Z_2$ breaking, a structure that is well fitting with the nature of the observed excess and the discrete symmetry leads to non-standard dark-matter interactions. We find that the excess can be explained by neutrino--electron interactions, linked with the neutrino and electron masses, while dark-matter--electron scattering does not lead to statistically significant improvement. We analyze the parameter space preferred by the anomaly and find severe constraints that can only be avoided in certain corners of parameter space. Potentially problematic bounds on electron couplings from Big-Bang Nucleosynthesis can be circumvented via a late phase transition in the new scalar sector.

Constant entropy hybrid stars: a first approximation of cooling evolution

We aim to study the possibility of a hadron-quark phase transition in the interior of neutron stars, taking into account different schematic evolutionary stages at finite temperature. We also discuss the strange quark matter stability in the quark matter phase. Furthermore, we aim to analyze the astrophysical properties of hot and cold hybrid stars, considering the constraint on maximum mass given by the pulsars J1614-2230 and J0348+0432. We have developed a computational code to construct semi-analytical hybrid equations of state at fixed entropy per baryon and to obtain different families of hybrid stars. An analytical approximation of the Field Correlator Method is developed for the quark matter equation of state. For the hadronic equation of state we use a table based on the relativistic mean field theory, without hyperons. We solved the relativistic structure equations of hydrostatic equilibrium and mass conservation for hybrid star configurations. For the different equations of state obtained, we calculated the stability window for the strange quark matter, lepton abundances, temperature profiles and contours profiles for the maximum mass star depending on the parameters of the Field Correlator Method. We also computed the mass-radius and gravitational mass-baryonic mass relationships for different hybrid star families. We have analyzed different stages of hot hybrid stars as a first approximation of the cooling evolution of neutron stars with quark matter cores. We obtain cold hybrid stars with maximum masses $\geq 2 M_\odot$ for different combinations of the Field Correlator Method parameters. In addition, our study based on the gravitational mass - baryonic mass plane shows a late phase transition between hadronic and quark matter during the proto-hybrid star evolution, in contrast with previous studies of proto-neutron stars.

Simplified Thermal Evolution of Proto-Hybrid Stars

We study the possibility of a hadron-quark phase transition in the interior of neutron stars, taking into account different schematic evolutionary stages at finite temperature. Furthermore, we analyze the astrophysical properties of hot and cold hybrid stars, considering the constraint on maximum mass given by the pulsars J1614-2230 and J1614-2230. We obtain cold hybrid stars with maximum masses [Formula: see text] M[Formula: see text]. Our study also suggest that during the proto-hybrid star evolution a late phase transition between hadronic matter and quark matter could occur, in contrast with previous studies of proto-neutron stars.

Light sterile neutrinos from a late phase transition

Light sterile neutrinos represent a well-motivated extension of the 3-neutrino paradigm. However, the impressive agreement between standard cosmology and data casts doubts on their existence. Here we present a class of scenarios that robustly avoids this tension. In these models the sterile neutrinos are light, chiral states of a new sector interacting with the Standard Model via the right-handed neutrino portal and, crucially, active-sterile neutrino oscillations require a phase transition in the hidden sector. We explore the hidden-couplings/critical-temperature plane and identify regions where several sterile neutrinos can be accommodated. A late phase transition is usually preferred and may also ward off a potential threat posed by the formation of topologically stable defects.

Rural transitions in the Nambucca Valley: Socio-demographic change in a disadvantaged rural locale

Within current rural research, an ongoing challenge has been to conceptualise the overarching dynamics driving rural transitions in affluent societies, while also recognising diversity and complexity in driving forces and trajectories over time and place. While amenity migration may continue to be influential, more recent research has revealed that there are multiple driving forces leading towards diverse multifunctional rural occupance modes and trajectories. With its oversupply of desirable rural destinations, transitions along the subtropical New South Wales coast have been marked by increasingly divergent socioeconomic trajectories, tied to perceived gradients in amenity and sequential gradients in affordability related to inherent and constructed place imagery. We explore early- and late-phase transitions in the Nambucca Valley, one region within this zone. Initially available at exceptionally low entry costs, a plentiful supply of former dairyfarms attracted undercapitalised migrants seeking a rural lifestyle and possibly a livelihood from on-farm or non-farm sources. With limited finances, near-zero borrowing capacity and an ill-informed, opportunistic approach towards initiating their prospective cropping and/or livestock ventures, newcomers were destined to fail. Notwithstanding its high natural landscape and liveability values, the Nambucca Valley has been bypassed during the later-phase, locationally selective commodification of rural hinterlands. With its now-entrenched image of disadvantage, Nambucca lacks the market-oriented positional values accruing to prime destinations elsewhere along the subtropical coast. Given the continuing inability of Nambucca’s rural landholdings to support cropping and livestock livelihoods, and the compatibility between consumption and protection outcomes, there is a high probability of entrenching a complex multifunctional mode of rural occupance for the foreseeable future. In this mode, ’consumption of the countryside’ by residents with modest incomes will be most influential in shaping rural socioeconomic futures, but with desultory production and protection activity together with reduced inputs into property management shaping rural landscapes.

Late-time vacuum phase transitions: Connecting sub-eV scale physics with cosmological structure formation

We show that a particular class of postrecombination phase transitions in the vacuum can lead to localized overdense regions on relatively small scales, roughly 10^6 to 10^10 M_sun, potentially interesting for the origin of large black hole seeds and for dwarf galaxy evolution. Our study suggests that this mechanism could operate over a range of conditions which are consistent with current cosmological and laboratory bounds. One byproduct of phase transition bubble-wall decay may be extra radiation energy density. This could provide an avenue for constraint, but it could also help reconcile the discordant values of the present Hubble parameter (H_0) and sigma_8 obtained by cosmic microwave background (CMB) fits and direct observational estimates. We also suggest ways in which future probes, including CMB considerations (e.g., early dark energy limits), 21-cm observations, and gravitational radiation limits, could provide more stringent constraints on this mechanism and the sub-eV scale beyond-standard-model physics, perhaps in the neutrino sector, on which it could be based. Late phase transitions associated with sterile neutrino mass and mixing may provide a way to reconcile cosmological limits and laboratory data, should a future disagreement arise.

Sterile neutrino, hidden dark matter and their cosmological signatures

Though thermal dark matter has been the central idea behind the dark matter candidates, it is highly possible that dark matter of the universe is non-thermal in origin or it might be in thermal contact with some hidden or dark sector but not with standard model. Here we explore the cosmological bounds as well as the signatures on two types of non-thermal dark matter candidates. First we discuss a hidden dark matter with almost no interaction (or very feeble) with standard model particles so that it is not in thermal contact with visible sector but we assume it is thermalized with in a hidden sector due to some interaction. While encompassing the standard cold WIMP scenario, we do not require the freeze-out process to be non-relativistic. Rather, freeze-out may also occur when dark matter particles are semi-relativistic or relativistic. Especially we focus on the warm dark matter scenario in this set up and find the constraints on the warm dark matter mass, cross-section and hidden to visible sector temperature ratio which accounts for the observed dark-matter density, satisfies the Tremaine-Gunn bound on dark-matter phase space density and has a free-streaming length consistent with cosmological constraints on the matter power spectrum. Our method can also be applied to keV sterile neutrino dark matter which is not thermalized with standard model but is thermalized with in a dark sector. The second part of this proceeding focuses on an exotic dark matter candidate which arises from the existence of eV mass sterile neutrino through a late phase transition. Due to existence of a strong scalar force the light sterile states get trapped into stable degenerate micro nuggets. We find that its signature in matter power spectra is close to a warm dark matter candidate.

Transition between vegetative phases in maize: genetic effects and variances and associated markers

SUMMARYTransition from juvenile to adult vegetative phase in maize is associated with pest and disease resistance. However, reports are not consistent on the significance and relative importance of additive or dominance genetic effects and variances. The purpose of the present research was to elucidate the genetic effects and variances and to identify molecular markers associated with phase transition. Three cycles of divergent selection were carried out in a maize synthetic accelerating and delaying phase transition. Three and four inbred lines were released from the third cycles of late phase transition (LPT) and early phase transition (EPT), respectively. Generation mean analyses were performed from two LPT×EPT crosses in order to calculate genetic effects and variances. Markers associated with vegetative phase transition were identified by contrasting simple sequence repeat (SSR) alleles between LPT and EPT inbreds and selection cycles, and by testing whether drift could explain the allelic changes observed in the respective third cycles of selection. Juvenile traits are mainly regulated by additive genetic effects and variances, whereas adult traits have a complex regulation involving dominance and epistatic effects. Based on error variances, EPT improves phenotypic stability. The SSRsphi028,phi112andumc1725were associated with selection for phase transition, suggesting that these genome regions are involved in the regulation of vegetative phase transition of maize, although none of the genes previously associated with phase transition has been located in those regions.

White noise from dark matter: 21 cm observations of early baryon collapse

In concordance cosmology, dark matter density perturbations generated by inflation lead to nonlinear, virialized minihalos, into which baryons collapse at redshift $z\ensuremath{\sim}20$. We survey here novel baryon evolution produced by a modification of the power spectrum from white noise density perturbations at scales below $k\ensuremath{\sim}10h\text{ }\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}$ (the smallest scales currently measured with the Lyman-$\ensuremath{\alpha}$ forest). Exotic dark matter dynamics, such as would arise from scalar dark matter with a late phase transition (similar to an axion, but with lower mass), or primordial black hole dark matter, create such an amplification of small scale power. The dark matter produced in such a phase transition collapses into minihalos, with a size given by the dark matter mass within the horizon at the phase transition. If the mass of the initial minihalos is larger than $\ensuremath{\sim}{10}^{\ensuremath{-}3}{M}_{\ensuremath{\bigodot}}$, the modified power spectrum is found to cause widespread baryon collapse earlier than standard $\ensuremath{\Lambda}\mathrm{CDM}$, leading to earlier gas heating. It also results in higher spin temperature of the baryons in the 21 cm line relative to $\ensuremath{\Lambda}\mathrm{CDM}$ at redshifts $zg20$ if the mass of the minihalo is larger than $1{M}_{\ensuremath{\bigodot}}$. It is estimated that experiments probing 21 cm radiation at high redshift will contribute a significant constraint on dark matter models of this type for initial minihalos larger than $\ensuremath{\sim}10{M}_{\ensuremath{\bigodot}}$. These experiments may also detect (or rule out) primordial black holes as the dark matter in the window $30{M}_{\ensuremath{\bigodot}}\ensuremath{\lesssim}{M}_{H}\ensuremath{\lesssim}4\ifmmode\times\else\texttimes\fi{}{10}^{3}{M}_{\ensuremath{\bigodot}}$ still left open by strong microlensing experiments and other astrophysical constraints. Early experiments reaching to $z\ensuremath{\approx}15$ will constrain minihalos down to $\ensuremath{\sim}{10}^{3}{M}_{\ensuremath{\bigodot}}$.

Exotic Axion Cosmology in Theories with Phase Transitions below the QCD Scale

We show that axion phenomenology may be significantly different than conventionally assumed in theories which exhibit late phase transitions (below the QCD scale). In such theories, one can find multiple pseudoscalars with axionlike couplings to matter, including a string scale axion, whose decay constant far exceeds the conventional cosmological bound. Such theories have several dark matter candidates.

Effects of Selection for the Timing of Vegetative Phase Transition on Corn Borer (Lepidoptera: Noctuidae and Crambidae) Damage

In maize, Zea mays L., the timing of vegetative phase transition from juvenile to adult vegetative phases can be modified through selection. A reduction in the juvenile vegetative phase has been associated with resistance to diseases and pests. The major maize pest in temperate areas is Ostrinia nubilalis (Hübner) and in Europe Sesamia nonagrioides Lefebvre. The objective of our study was to determine the effects of divergent selection for the timing of vegetative phase transition in maize on resistance to corn borers. Three cycles of divergent selection for early and late phase transition in a field corn synthetic and in a sweet corn population were evaluated separately under S. nonagrioides and O. nubilalis artificial infestation. For the field corn experiment, yield and moisture improved with selection for phase transition in both directions, but improvement was due to artifacts of selection, rather than to the change in phase transition. There were no correlated responses for corn borer damage, yield, or grain moisture due to selection for the timing of vegetative phase transition. In the sweet corn experiment, selection for the timing of vegetative phase transition had no significant effects on corn borer damage in sweet corn harvested at the fresh stage. Our results do not support the use of phase transition as an indirect criterion for improving resistance to corn borers in maize. The relationship between phase transition and pest resistance reported by other studies could depend on the genotypes or could be too weak to be detected in a selection program with wild-type maize.

Fine structure constant variation from a late phase transition

Recent experimental data indicates that the fine structure constant α may be varying on cosmological time scales. We consider the possibility that such a variation could be induced by a second order phase transition which occurs at late times (z∼1–3) and involves a change in the vacuum expectation value (vev) of a scalar with milli-eV mass. Such light scalars are natural in supersymmetric theories with low SUSY breaking scale. If the vev of this scalar contributes to masses of electrically charged fields, the low-energy value of α changes during the phase transition. The observational predictions of this scenario include isotope-dependent deviations from Newtonian gravity at sub-millimeter distances, and (if the phase transition is a sharp event on cosmological time scales) the presence of a well-defined step-like feature in the α(z) plot. The relation between the fractional changes in α and the QCD confinement scale is highly model dependent, and even in grand unified theories the change in α does not need to be accompanied by a large shift in nucleon masses.

Response to Selection for the Timing of Vegetative Phase Transition in a Maize Population

Variability for the timing of transition from juvenile to adult vegetative phases in maize (Zea mays L.) is genetically regulated and has been associated with disease and pest tolerance. Epicuticular wax is present in juvenile leaves and absent in adult leaves. The objective of this work was to assess the potential modification through selection of the timing of vegetative phase transition. Three cycles of divergent phenotypic selection for early and late vegetative phase transition performed on a synthetic population were evaluated by means of a randomized complete block design with two replications, in two locations of northwestern Spain across two years. Selection for early transition was made by recombining plants with fewer leaves with epicuticular wax, while, for late transition, plants with more leaves with epicuticular wax were recombined. Selection response was significant and more efficient for late phase transition than for early phase transition. Other changes observed cannot be considered correlated responses to selection because they changed in the same way for both directions of selection. We conclude that selection for the timing of vegetative phase transition was efficient and there was no detrimental correlated responses on any agronomic trait.

Consistent viral evolutionary changes associated with the progression of human immunodeficiency virus type 1 infection.

To understand the high variability of the asymptomatic interval between primary human immunodeficiency virus type 1 (HIV-1) infection and the development of AIDS, we studied the evolution of the C2-V5 region of the HIV-1 env gene and of T-cell subsets in nine men with a moderate or slow rate of disease progression. They were monitored from the time of seroconversion for a period of 6 to 12 years until the development of advanced disease in seven men. Based on the analysis of viral divergence from the founder strain, viral population diversity within sequential time points, and the outgrowth of viruses capable of utilizing the CXCR4 receptor (X4 viruses), the existence of three distinct phases within the asymptomatic interval is suggested: an early phase of variable duration during which linear increases ( approximately 1% per year) in both divergence and diversity were observed; an intermediate phase lasting an average of 1.8 years, characterized by a continued increase in divergence but with stabilization or decline in diversity; and a late phase characterized by a slowdown or stabilization of divergence and continued stability or decline in diversity. X4 variants emerged around the time of the early- to intermediate-phase transition and then achieved peak representation and began a decline around the transition between the intermediate and late phases. The late-phase transition was also associated with failure of T-cell homeostasis (defined by a downward inflection in CD3(+) T cells) and decline of CD4(+) T cells to </=200 cells/microliter. The strength of these temporal associations between viral divergence and diversity, viral coreceptor specificity, and T-cell homeostasis and subset composition supports the concept that the phases described represent a consistent pattern of viral evolution during the course of HIV-1 infection in moderate progressors. Recognition of this pattern may help explain previous conflicting data on the relationship between viral evolution and disease progression and may provide a useful framework for evaluating immune damage and recovery in untreated and treated HIV-1 infections.

Organization of Splicing Factors in Adenovirus-Infected Cells Reflects Changes in Gene Expression during the Early to Late Phase Transition

The spatial distribution of splicing factors is temporally regulated during adenovirus (ad) infection. Here we focus on two splicing factor distribution patterns characteristic of ad-infected cells. During the intermediate phase splicing factors surround sites of viral DNA accumulation in regions of high transcriptional activity. This distribution appears as a series of interconnected rings when viewed by microscopy. We refer to cells with this staining pattern as “ring cells.” We have previously shown that at late times after infection, splicing factors are present in discrete structures identified as enlarged interchromatin granules (IGs) that also contain spliced viral RNA. We refer to cells with this pattern as “cluster cells.” We determined which steps in viral gene expression occurred in ring and cluster cells. We found that transcription and some splicing of viral late genes had occurred in ring cells. Late RNA was present at transcription sites in ring cells. Cluster cells contained spliced viral late RNA in nuclear IGs and in the cytoplasm. The presence of cluster cells in the infected culture was well correlated with the export of viral RNA to the cytoplasm. Cluster cells had synthesized late proteins. Our data show that the dynamic localization of splicing factors reflects changes in gene expression activity of the infected cell as it switches over to late gene expression.

Structure formation from unstable domain walls

We discuss the field theory expectations for very light scalar states which may give rise to a late stage of spontaneous symmetry breaking, paying particular regard to the spontaneous breaking of the discrete symmetries which commonly occur in compactified string or Grand Unified theories. We consider the possibility that the large scale structure of the universe is generated due to domain walls associated with this late phase transition. Efficient dissipation of the wall energy in a dark matter component may occur leading to large local density fluctuations which generate a component of the large scale structure today. Provided the walls decay at an early time the magnitude of fluctuations needed to explain the present day structure is consistent with induced fluctuations in the cosmic microwave background radiation of order 10 −5. The model also predicts early quasar formation (at redshifts ∼ 10).

Kinetics of the intermediate stage of phase transition in batch crystallization

The batch crystallization kinetics in supersaturated (or supercooled) system is investigated before the late phase transition stage of relaxation. The integro-differential equation for supersaturation (supercooling) is derived. The supersaturation (supercooling) evolution is determined. The explicit particle size distribution function is obtained.