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JPMorgan Chase & Co. began a learning and evaluation practice of its summer youth employment program (SYEP) portfolio in 2022. At the time, the organization was providing grant support to 27 organizations that offer summer work-readiness training to young people between the ages of 14 and 24, including social service agencies, community-based organizations, and economic development agencies. JPMorgan Chase partnered with MDRC to promote continual improvement among these organizations through research. MDRC collected data in the form of interviews and metrics aggregated from nearly all providers. Afterward, MDRC invited 10 providers to share specific insights about a particular program component--soft-skills training. ("Soft skills" refer to the general habits and competencies that make for an effective employee, such as arriving at work on time, cooperating with coworkers, taking and giving direction, communicating clearly, dressing appropriately for the workplace, and so forth.) These providers were selected for such reasons as tenure in the field, depth of training reported in previous interviews and surveys, and responsiveness to MDRC's email outreach. Six SYEP providers responded to the invitation and are highlighted in this brief. The brief begins with an overview of the literature on the labor market value of soft skills, before explaining a particular type of labor market-advancement strategy: SYEPs. The brief then addresses how soft-skills training can be embedded successfully into the SYEP model and concludes with recommendations for the field. Ultimately, the findings presented in this brief are intended to showcase ways that soft-skills training, as a workforce development intervention, can put young people on the path to high-paying jobs and socio­economic advancement.

Summer youth employment programs (SYEPs) are a workforce development strategy used around the country to provide early work experiences to young people each year. These programs partner with local employers to provide subsidized wages for young people between the ages of 14 and 24. The programs often include job-readiness training (which prepares young people to seek employment through, for example, help writing résumés or getting ready for interviews) and financial literacy training, as well as other forms of support. SYEPs provide first job experiences for many young people who participate. Rigorous research examining whether summer jobs positively affect young people's longer-term employment and postsecondary outcomes is limited, but there is evidence that SYEPs improve more immediate outcomes. MDRC's lottery-based study of New York City's SYEP showed that the program had large effects on young people's employment and earnings during the summer for which they applied. Other studies have shown that SYEPs have the potential to improve outcomes related to school engagement and youth development. More generally, research shows that early work experience can bolster long-term economic and academic outcomes and those related to social and emotional well-being. Additionally, having a job between ages 16 and 18 is associated with having a higher-quality job in adulthood. In 2022, JPMorgan Chase & Co. committed $20 million over the course of five years to support SYEPs across the United States. In the first year thereafter, it awarded grants to 27 organizations that operate SYEPs across the country. The grantees include social service agencies, economic development agencies, and other types of organizations that focus on workforce development and youth development. JPMorgan Chase partnered with MDRC to conduct an evaluation to promote continual improvement among grantee organizations. MDRC conducted interviews with grantees, focused on grantees' program models and implementation, and collected data to gauge the programs' reach in terms of the number and demographics of young people they served, as well as the number and types of job placements they made. This brief focuses on SYEPs' efforts to engage and recruit employer partners.

We advance the study of pure de Sitter supergravity by introducing a finite formulation of unimodular supergravity via the super-St\"uckelberg mechanism. Building on previous works, we construct a complete four-dimensional action of spontaneously broken ${\cal N}\!\!=\!\!1$ supergravity to all orders, which allows for de Sitter solutions. The introduction of finite supergravity transformations extends the super-St\"uckelberg procedure beyond the second order, offering a recursive solution to all orders in the goldstino sector. This work bridges the earlier perturbative approaches and the complete finite theory, opening new possibilities for de Sitter vacua in supergravity models and eventually string theory., Comment: 23 pages

We use a suite of the most recent cosmological observations to test models of dynamical dark energy motivated by quantum gravity. Specifically, we focus on hilltop quintessence scenarios, able to satisfy theoretical constraints from quantum gravity. We discuss their realisation based on axions, their supersymmetric partners, and Higgs-like string constructions. We also examine a specific parameterisation for dynamical dark energy suitable for hilltop quintessence. We then perform an analysis based on Markov Chain Monte-Carlo to assess their predictions against CMB, galaxy surveys, and supernova data. We show to what extent current data can distinguish amongst different hilltop set-ups, providing model parameter constraints that are complementary to and synergetic with theoretical bounds from quantum gravity conjectures, as well as model comparisons across the main dark energy candidates in the literature. However, all these constraints are sensitive to priors based on theoretical assumptions about viable regions of parameter space. Consequently, we discuss theoretical challenges in refining these priors, with the aim of maximizing the informative power of current and forthcoming cosmological datasets for testing dark energy scenarios in quantum gravity., Comment: 35 pages + appendices, 24 figures, 9 tables

This study redefines the analysis of Devaney chaos in multiple mappings from a set-valued perspective and introduces new conditions to characterize their chaotic behavior. As an innovative advancement, we develop computational algorithms to detect and visualize chaotic features such as transitivity and sensitivity. These algorithms provide tools to explore complex dynamics in higher-dimensional systems, validating theoretical concepts and opening new research avenues in chaos theory., Comment: 7 pag

We present the design of the mechanical structure of the miniBeBe detector, a subsystem of the Multi-Purpose Detector, soon to enter into operation at the Nuclotron based Ion Collider fAcility of the Joint Institute for Nuclear Research. The miniBeBe detector was designed and is currently being developed by the MexNICA Collaboration to contribute to the level-zero trigger of the Time of Flight. The mechanical structure meets the requirements of minimizing the material budget and be free of ferromagnetic materials, without compromising its robustness. The design also allows easy module replacement for maintenance and overall removal at the end of the first stage of the experiment, without affecting the rest of the subsystems, to leave room for the installation of the Inner Tracking System. In addition, a Finite Element Method analysis of the mechanical components under load was performed. Based on this analysis, it was determined that the design meets the space constraints within the Multi-Purpose Detector, as well as a deformation of less than 1 mm with overall stress of less than 2 MPa, such that no material used in the design is at risk of mechanical failure during operation. A cooling system heat transfer analysis was performed showing that the detector Silicon Photo-Multipliers can be kept within a temperature range of 19$^{\circ}$C to 23$^{\circ}$C, which is adequate for their optimal performance., Comment: 15 pages, 13 figures, 6 tables

The circular polarization of the stochastic gravitational wave background (SGWB) is a key observable for characterising the origin of the signal detected by Pulsar Timing Array (PTA) collaborations. Both the astrophysical and the cosmological SGWB can have a sizeable amount of circular polarization, due to Poisson fluctuations in the source properties for the former, and to parity violating processes in the early universe for the latter. Its measurement is challenging since PTA are blind to the circular polarization monopole, forcing us to turn to anisotropies for detection. We study the sensitivity of current and future PTA datasets to circular polarization anisotropies, focusing on realistic modelling of intrinsic and kinematic anisotropies for astrophysical and cosmological scenarios respectively. Our results indicate that the expected level of circular polarization for the astrophysical SGWB should be within the reach of near future datasets, while for cosmological SGWB circular polarization is a viable target for more advanced SKA-type experiments., Comment: 28 pages, 9 figures

Dynamical dark energy has gained renewed interest due to recent theoretical and observational developments. In the present paper, we focus on a string-motivated dark energy set-up, and perform a detailed cosmological analysis of exponential quintessence with potential $V=V_0 e^{-\lambda\phi}$, allowing for non-zero spatial curvature. We first gain some physical intuition into the full evolution of such a scenario by analysing the corresponding dynamical system. Then, we test the model using a combination of Planck CMB data, DESI BAO data, as well as recent supernovae datasets. For the model parameter $\lambda$, we obtain a preference for nonzero values: $\lambda = 0.48^{+0.28}_{-0.21},\; 0.68^{+0.31}_{-0.20},\; 0.77^{+0.18}_{-0.15}$ at 68% C.L. when combining CMB+DESI with Pantheon+, Union3 and DES-Y5 supernovae datasets respectively. We find no significant hint for spatial curvature. We discuss the implications of current cosmological results for the exponential quintessence model, and more generally for dark energy in string theory., Comment: 34 pages, 13 figures, 10 tables. Comments welcome! V2 - updated plots and added references

We explore the possibility that our universe's current accelerated expansion is explained by a quintessence model with an exponential scalar potential, $V =V_0\, e^{-\lambda\, \phi}$, keeping an eye towards $\lambda \geq \sqrt{2}$ and an open universe, favorable to a string theory realisation and with no cosmological horizon. We work out the full cosmology of the model, including matter, radiation, and optionally negative spatial curvature, for all $\lambda>0$, performing an extensive analysis of the dynamical system and its phase space. The minimal physical requirements of a past epoch of radiation domination and an accelerated expansion today lead to an upper bound $\lambda \lesssim \sqrt{3}$, which is driven slightly up in the presence of observationally allowed spatial curvature. Cosmological solutions start universally in a kination epoch, go through radiation and matter dominated phases and enter an epoch of acceleration, which is only transient for $\lambda>\sqrt{2}$. Field distances traversed between BBN and today are sub-Planckian. We discuss possible string theory origins and phenomenological challenges, such as time variation of fundamental constants. We provide theoretical predictions for the model parameters to be fitted to data, most notably the varying dark energy equation of state parameter, in light of recent results from DES-Y5 and DESI., Comment: 53 pages + appendices, several figures. A notebook with all figures is provided as an ancillary file. v2: minor modifications

Recent Pulsar Timing Array (PTA) collaborations show strong evidence for a stochastic gravitational wave background (SGWB) with the characteristic Hellings-Downs inter-pulsar correlations. The signal may stem from supermassive black hole binary mergers, or early universe phenomena. The former is expected to be strongly anisotropic while primordial backgrounds are likely to be predominantly isotropic with small fluctuations. In case the observed SGWB is of cosmological origin, our relative motion with respect to the SGWB rest frame is a guaranteed source of anisotropy, leading to $\textit{O}(10^{-3})$ energy density fluctuations of the SGWB. For such cosmological SGWB, kinematic anisotropies are likely to be larger than the intrinsic anisotropies, akin to the cosmic microwave background (CMB) dipole anisotropy. We assess the sensitivity of current PTA data to the kinematic dipole anisotropy, and we also forecast at what extent the magnitude and direction of the kinematic dipole can be measured in the future with an SKA-like experiment. We also discuss how the spectral shape of the SGWB and the location of the pulsars to monitor affect the prospects of detecting the kinematic dipole with PTA. In the future, a detection of this anisotropy may even help resolve the discrepancy in the magnitude of the kinematic dipole as measured by CMB and large-scale structure observations., Comment: 29 pages, 6 figures. V2: corrected upper limit, updated forecasts

We study the evolution of the two-pion correlation function parameters with collision energy in the context of relativistic heavy-ion collisions within the NICA energy range. To this end, we perform UrQMD simulations in the cascade mode to produce samples of pions from $5\times 10^6$ Bi+Bi collisions for each of the studied energies. The effects of the quantum-statistical correlations are introduced using the correlation afterburner code CRAB. We fit the correlation function using Gaussian, exponential and symmetric L\'evy shapes and show that for all collision energies the latter provides the best fit. We separate the sample into pions coming from primary processes and pions originating from the decay of long-lived resonances, and show that the source size for the latter is significantly larger than for the former. The source size for the secondaries, is similar but in general larger than the size for the whole pion sample. To further characterize the pion source, we also simulate the effects of a non-ideal detector introducing a momentum smearing parameter, representing the minimum pair momentum and thus a maximum source size that can be resolved. The values of the correlation function intercept parameter are therefore modified from the values they attain for the perfect detector case. Using the core-halo picture of the source, we show that the values of the intercept parameter are influenced by the presence of a significant fraction of core pions coming from the decay of long-lived but slow-moving resonances. These findings serve as a benchmark to compare with future Monte Carlo studies that consider an Equation of State and thus allow for a phase transition within the studied energy domain., Comment: 8 pages, 10 figures. Version accepted to appear in EPJ-A

We compute the relaxation times for massive quarks and anti-quarks to align their spins with the angular velocity in a rigidly rotating medium at finite temperature and baryon density. The rotation effects are implemented using a fermion propagator immersed in a cylindrical rotating environment. The relaxation time is computed as the inverse of the interaction rate to produce an asymmetry between the quark (anti-quark) spin components along and opposite to the angular velocity. For conditions resembling heavy-ion collisions, the relaxation times for quarks are smaller than for anti-quarks. For semi-central collisions the relaxation time is within the possible life-time of the QGP for all collision energies. However, for anti-quarks this happens only for collision energies $\sqrt{s_{NN}}\gtrsim 50$ GeV. The results are quantified in terms of the intrinsic quark and anti-quark polarizations, namely, the probability to build the spin asymmetry as a function of time. Our results show that these intrinsic polarizations tend to 1 with time at different rates given by the relaxation times with quarks reaching a sizable asymmetry at a faster pace. These are key results to further elucidate the mechanisms of hyperon polarization in relativistic heavy-ion collisions., Comment: 9 pages, 10 figures