Feebly-interacting particles represent an alternative paradigm with respect to the traditional strongly-coupled Beyond the Standard Model physics explored at the LHC and can provide an answer to many ...fundamental open questions in particle physics. This document presents the state of the art of searches for feebly-interacting particles at accelerator-based experiments including projects proposed at CERN and currently discussed in the European Strategy for Particle Physics update.
The Physics Beyond Colliders initiative is an exploratory study aimed at exploiting the full scientific potential of the CERN's accelerator complex and scientific infrastructures through projects ...complementary to the LHC and other possible future colliders. These projects will target fundamental physics questions in modern particle physics. This document presents the status of the proposals presented in the framework of the Beyond Standard Model physics working group, and explore their physics reach and the impact that CERN could have in the next 10-20 years on the international landscape.
We present updated chemical evolution models of two dwarf spheroidal galaxies (Sculptor and Carina) and the first detailed chemical evolution models of two ultra-faint dwarfs (Hercules and Boötes I). ...Our results suggest that the dwarf spheroidals evolve with a low efficiency of star formation, confirming previous results, and the ultra-faint dwarfs with an even lower one. Under these assumptions, we can reproduce the stellar metallicity distribution function, the α/Fe versus Fe/H abundance patterns and the total stellar and gas masses observed at the present time in these objects. In particular, for the ultra-faint dwarfs we assume a strong initial burst of star formation, with the mass of the system being already in place at early times. On the other hand, for the classical dwarf spheroidals the agreement with the data is found by assuming the star formation histories suggested by the colour–magnitude diagrams and a longer time-scale of formation via gas infall. We find that all these galaxies should experience galactic winds, starting in all cases before 1 Gyr from the beginning of their evolution. From comparison with Galaxy data, we conclude that it is unlikely that the ultra-faint dwarfs have been the building blocks of the whole Galactic halo, although more data are necessary before drawing firm conclusions.
With the establishment and maturation of the experimental programs searching for new physics with sizeable couplings at the LHC, there is an increasing interest in the broader particle and ...astrophysics community for exploring the physics of light and feebly-interacting particles as a paradigm complementary to a New Physics sector at the TeV scale and beyond. FIPs 2020 has been the first workshop fully dedicated to the physics of feebly-interacting particles and was held virtually from 31 August to 4 September 2020. The workshop has gathered together experts from collider, beam dump, fixed target experiments, as well as from astrophysics, axions/ALPs searches, current/future neutrino experiments, and dark matter direct detection communities to discuss progress in experimental searches and underlying theory models for FIPs physics, and to enhance the cross-fertilisation across different fields. FIPs 2020 has been complemented by the topical workshop “Physics Beyond Colliders meets theory”, held at CERN from 7 June to 9 June 2020. This document presents the summary of the talks presented at the workshops and the outcome of the subsequent discussions held immediately after. It aims to provide a clear picture of this blooming field and proposes a few recommendations for the next round of experimental results.
We have studied the effects of various initial mass functions (IMFs) on the chemical evolution of the Sagittarius dwarf galaxy (Sgr). In particular, we tested the effects of the integrated galactic ...initial mass function (IGIMF) on various predicted abundance patterns. The IGIMF depends on the star formation rate and metallicity and predicts less massive stars in a regime of low star formation, as it is the case in dwarf spheroidals. We adopted a detailed chemical evolution model following the evolution of α-elements, Fe and Eu, and assuming the currently best set of stellar yields. We also explored different yield prescriptions for the Eu, including production from neutron star mergers. Although the uncertainties still present in the stellar yields and data prevent us from drawing firm conclusions, our results suggest that the IGIMF applied to Sgr predicts lower α/Fe ratios than classical IMFs and lower hydrostatic/explosive α-element ratios, in qualitative agreement with observations. In our model, the observed high Eu/O ratios in Sgr is due to reduced O production, resulting from the IGIMF mass cut-off of the massive oxygen-producing stars, as well as to the Eu yield produced in neutron star mergers, a more promising site than core-collapse supernovae, although many uncertainties are still present in the Eu nucleosynthesis. We find that a model, similar to our previous calculations, based on the late addition of iron from the Type Ia supernova time-delay (necessary to reproduce the shape of X/Fe versus Fe/H relations) but also including the reduction of massive stars due to the IGIMF, better reproduces the observed abundance ratios in Sgr than models without the IGIMF.
Duchenne muscular dystrophy (DMD) is the most common single-gene lethal disorder. Substantial patient-patient variability in disease onset and progression and response to glucocorticoids is seen, ...suggesting genetic or environmental modifiers.
Two DMD cohorts were used as test and validation groups to define genetic modifiers: a Padova longitudinal cohort (n = 106) and the Cooperative International Neuromuscular Research Group (CINRG) cross-sectional natural history cohort (n = 156). Single nucleotide polymorphisms to be genotyped were selected from mRNA profiling in patients with severe vs mild DMD, and genome-wide association studies in metabolism and polymorphisms influencing muscle phenotypes in normal volunteers were studied.
Effects on both disease progression and response to glucocorticoids were observed with polymorphism rs28357094 in the gene promoter of SPP1 (osteopontin). The G allele (dominant model; 35% of subjects) was associated with more rapid progression (Padova cohort log rank p = 0.003), and 12%-19% less grip strength (CINRG cohort p = 0.0003).
Osteopontin genotype is a genetic modifier of disease severity in Duchenne dystrophy. Inclusion of genotype data as a covariate or in inclusion criteria in DMD clinical trials would reduce intersubject variance, and increase sensitivity of the trials, particularly in older subjects.
Particle physics today faces the challenge of explaining the mystery of dark matter, the origin of matter over anti-matter in the Universe, the origin of the neutrino masses, the apparent fine-tuning ...of the electro-weak scale, and many other aspects of fundamental physics. Perhaps the most striking frontier to emerge in the search for answers involves new physics at mass scales comparable to familiar matter, below the GeV-scale, or even radically below, down to sub-eV scales, and with very feeble interaction strength. New theoretical ideas to address dark matter and other fundamental questions predict such feebly interacting particles (FIPs) at these scales, and indeed, existing data provide numerous hints for such possibility. A vibrant experimental program to discover such physics is under way, guided by a systematic theoretical approach firmly grounded on the underlying principles of the Standard Model. This document represents the report of the FIPs 2022 workshop, held at CERN between the 17 and 21 October 2022 and aims to give an overview of these efforts, their motivations, and the decadal goals that animate the community involved in the search for FIPs.
Aims.To study the effects of galactic winds on the stellar metallicity distributions and on the evolution of Draco and Ursa Minor dwarf spheroidal galaxies (dSphs), we compared the predictions of ...several chemical evolution models, adopting different prescriptions for the galactic winds (including a model with no wind), with the photometrically-derived stellar metallicity distributions (SMDs) of both galaxies. Methods.We adopted chemical evolution models for Draco and Ursa Minor, which are able to reproduce several observational features of these two galaxies, such as the α/Fe , Eu/Fe, Ba/Fe ratios and the present gas mass. The models take up-to-date nucleosynthesis into account for intermediate-mass stars and supernovae of both types, as well as the effect of these objects on the energetics of the systems. The predictions were compared to the photometric SMDs, which are accurate enough for a global comparison with general aspects such as metallicity range, shape, position of the peak, and high-metallicity tail, leaving aside minor details of the distributions. Results.For both galaxies, the model that best fits the data contains an intense continuous galactic wind, occurring at a rate proportional to the star formation rate. Models with a wind rate assumed to be proportional only to the supernova rate also reproduce the observed SMD, but do not match the gas mass, whereas the models with no galactic winds fail to reproduce the observed SMDs. In the case of Ursa Minor, the same model as in previous works reproduces the observed distribution very well with no need to modify the main parameters of the model (star formation efficiency $\nu = 0.1$ Gyr-1 and wind efficiency wi = 10). The model for Draco, on the other hand, is slightly modified. The observed SMD requires a model with a lower supernova type Ia thermalization efficiency ($\eta_{\rm SNeIa} = 0.5$ instead of $\eta_{\rm SNeIa} = 1.0$, as used in previous papers of this series) in order to delay the galactic wind, whereas all the other parameters are kept the same ($\nu = 0.05$ Gyr-1, wi = 4). Conclusions.The model results, compared to observations, strongly suggest that intense and continuous galactic winds play a very important role in the evolution of local dSphs. They not only remove a large fraction of the gas content of the galaxy, but also define the pattern of the abundance ratios and of the SMD, giving rise to low (below solar) values for α/Fe , Eu/Fe, as well as high Ba/Fe at high metallicities, as observed, and preventing metal-rich stars being formed, which is reflected in the strong decrease in the high-metallicity tail of the stellar distributions in these galaxies.
Aims. The aim of this paper is to study the basic equations of the chemical evolution of galaxies with gas flows. In particular, we focus on models in which the outflow is differential, namely in ...which the heavy elements (or some of the heavy elements) can leave the parent galaxy more easily than other chemical species such as H and He. Methods. We study the chemical evolution of galaxies in the framework of simple models, namely we make simplifying assumptions about the lifetimes of stars and the mixing of freshly produced metals. This allows us to solve analytically the equations for the evolution of gas masses and metallicities. In particular, we find new analytical solutions for various cases in which the effects of winds and infall are taken into account. Results. Differential galactic winds, namely winds carrying out preferentially metals, have the effect of reducing the global metallicity of a galaxy, with the amount of reduction increasing with the ejection efficiency of the metals. Abundance ratios are predicted to remain constant throughout the whole evolution of the galaxy, even in the presence of differential winds. One way to change them is by assuming differential winds with different ejection efficiencies for different elements. However, simple models apply only to elements produced on short timescales, namely all by type II SNe, and therefore large differences in the ejection efficiencies of different metals are unlikely. Conclusions. Variations in abundance ratios such as O/Fe in galaxies, without including the Fe production by type Ia supernovae, can in principle be obtained by assuming an unlikely different efficiency in the loss of O relative to Fe from type II supernovae. Therefore, we conclude that it is not realistic to ignore type Ia supernovae and that the delayed production of some chemical elements relative to others (time-delay model) remains the most plausible explanation for the evolution of α-elements relative to Fe.
Aims. We model the chemical evolution of manganese relative to iron in three different stellar systems: the Solar neighbourhood, the Galactic bulge, and the Sagittarius dwarf spheroidal galaxy, and ...we compare our results with recent and homogeneous observational data sets. Methods. We adopt three chemical evolution models able to reproduce the main properties of the Solar vicinity, the Galactic bulge, and the Sagittarius dwarf spheroidal. We then compare different stellar yields in order to identify the most appropriate set to match the observational data in these systems. Results. We compute the evolution of manganese in the three systems and find that to reproduce simultaneously the measurements of Mn/Fe versus Fe/H in the Galactic bulge, the Solar neighbourhood and Sagittarius, the type Ia supernova (SN) Mn yield must be metallicity-dependent. Conclusions. We conclude that modelling different histories of star formation in the three systems are insufficient to reproduce the different behaviour of the Mn/Fe ratio, unlike the situation for α/Fe ; rather, it is necessary to invoke metallicity-dependent type Ia SN Mn yields, as originally suggested by McWilliam, Rich & Smecker-Hane.
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