The Search for Feebly Interacting Particles

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.

We investigate the potential of the Square Kilometre Array (SKA) in detecting synchrotron radiation emitted from the decay of sub-GeV dark matter (dark matter with masses below the GeV scale) in the presence of strong magnetic fields. As a concrete setup, we consider scenarios where the magnetosphere of a magnetic white dwarf overlaps with dense dark matter environments, such as those surrounding a primordial black hole. Our study reveals that the encounters of compact objects such as white dwarfs and black holes offer a promising avenue for upcoming radio telescopes to probe the properties of light dark matter, which has been less explored compared with more conventional heavier (masses above the GeV scale) dark matter. Published by the American Physical Society 2024

Probing light inelastic dark matter from direct detection

Motivated by the recent PAMELA and ATIC data, one is ledto a scenario with heavy vector-like dark matter in associationwith a hidden U(1)X sector below GeV scale. Realizing this ideain the context of gauge mediated supersymmetry breaking (GMSB), aheavy scalar component charged under U(1)X is found to be agood dark matter candidate which can be searched for directscattering mediated by the Higgs boson and/or by the hidden gaugeboson. The latter turns out to put a stringent bound on thekinetic mixing parameter between U(1)X and U(1)Y: θ ≲ 10−6. For the typical range of model parameters, wefind that the decay rates of the ordinary lightest neutralino intohidden gauge boson/gaugino and photon/gravitino are comparable,and the former decay mode leaves displaced vertices of leptonpairs and missing energy with distinctive length scale larger than20 cm for invariant lepton pair mass below 0.5 GeV. Anunsatisfactory aspect of our model is that the Sommerfeld effectcannot raise the galactic dark matter annihilation by more than60 times for the dark matter mass below TeV.

The gravitational and cosmological evidence of dark matter (DM) as the dominant, 85% fraction of the matter in the Universe still remains, after 50 years of investigation, the only rm experimental evidence of DM, although some puzzling measurements from astroparticle experiments could be explained in terms of DM scattering on nuclei or DM annihilation. The thermal relic abundance of DM implies small couplings with the SM, main feature of the standard WIMP scenario, whose DM candidate is a weakly interacting massive particle (WIMP) with mass from 10−10 GeV. Some non-WIMP DMmodels postulate the existence of a dark gauge symmetry U(1)D [1] giving rise to a secluded sector with mediating bosons (dark photons), fermions, and scalar elds for the spontaneous breaking of the symmetry (dark higgs elds). In general, the phenomenology relating to the dark sector, especially in the case mU < mDM, is really di erent from the standard WIMP scenario. Some of the secluded sectors can be tested at the e e− colliders searching for vector or scalar particles at the GeV scale [2]. A DM sector mediated by a light dark photon with mass mU ≤ 1 GeV could explain both, the positron excess measured by the balloon-borne experiments HEAT [3] and PAMELA [4] and by AMS-02 on the International Space Station [5], and the measurement of the antiproton ux [6] that is instead in agreement with the abundance expected from secondary production in the interstellar medium (ISM) interactions of the primary cosmic rays. In this case, the kinetic mixing parameter of the dark photon with the γ/Z boson is expected to be of O(10−4−10−2), a range of couplings that can be studied at the φ and B factories. A light dark photon could be observed in a variety of nal states, among which are: (i) sharp resonance at mU in the invariant mass distribution of charged lepton or pion pairs, in e e− → γl+l− or V → Pl+l− reactions, where V (P ) stands for any vector (pseudoscalar) meson, and l± for muons, electrons or charged pions; (ii) dark-higgsstrahlung processes [7],

Recently Arkani-Hamed, Finkbeiner, Slatyer and Weiner proposed a unified explanation to the set of experimental and observational anomalies with possible connections to Dark Matter (DM). A central role is played by GeV scale ``dark" gauge bosons exchanged by the weak scale DM. Motivated by this proposal, we build an explicit model of DM in the context of Weak Scale Supersymmetry (SUSY). We employ high-scale SUSY-breaking and invoke the Giudice-Masiero mechanism to generate the weak scale DM masses. By sequestering the dark sector from the SUSY-breaking ``hidden" sector, it naturally acquires GeV scale soft masses that help generate the dark gauge boson mass. The visible MSSM sector is not fully sequestered and acquires gaugino-mediated soft terms at the weak scale. This hierarchy of scales naturally leads to the Sommerfeld enhancement of DM annihilations needed to account for the e+e− excesses in the PAMELA and ATIC experiments. The possibility of co-existing species of DM is used to show how the INTEGRAL and DAMA anomalies can both be explained. We study the cosmological constraints on the new stable or long-lived light particles that appear in our models. We discuss the lepton-jet collider signals suggested by Arkani-Hamed and Weiner, and find that they are not guaranteed in our construction.

The quest for the nature of dark matter has reached a historical point in time, with several different and complementary experiments on the verge of conclusively exploring large portions of the parameter space of the most theoretically compelling particle dark matter models. This focus issue on dark matter and particle physics brings together a broad selection of invited articles from the leading experimental and theoretical groups in the field. The leitmotif of the collection is the need for a multi-faceted search strategy that includes complementary experimental and theoretical techniques with the common goal of a sound understanding of the fundamental particle physical nature of dark matter. These include theoretical modelling, high-energy colliders and direct and indirect searches. We are confident that the works collected here present the state of the art of this rapidly changing field and will be of interest to both experts in the topic of dark matter as well as to those new to this exciting field.Focus on Dark Matter and Particle Physics ContentsDARK MATTER AND ASTROPHYSICSScintillator-based detectors for dark matter searches I S K Kim, H J Kim and Y D KimCosmology: small-scale issues Joel R PrimackBig Bang nucleosynthesis and particle dark matter Karsten Jedamzik and Maxim PospelovParticle models and the small-scale structure of dark matter Torsten BringmannDARK MATTER AND COLLIDERSDark matter in the MSSM R C Cotta, J S Gainer, J L Hewett and T G RizzoThe role of an e+e- linear collider in the study of cosmic dark matter M BattagliaCollider, direct and indirect detection of supersymmetric dark matter Howard Baer, Eun-Kyung Park and Xerxes TataINDIRECT PARTICLE DARK MATTER SEARCHES:EXPERIMENTSPAMELA and indirect dark matter searches M Boezio et alAn indirect search for dark matter using antideuterons: the GAPS experiment C J HaileyPerspectives for indirect dark matter search with AMS-2 using cosmic-ray electrons and positrons B Beischer, P von Doetinchem, H Gast, T Kirn and S SchaelAxion searches with helioscopes and astrophysical signatures for axion(-like) particles K Zioutas, M Tsagri, Y Semertzidis, T Papaevangelou, T Dafni and V AnastassopoulosThe indirect search for dark matter with IceCube Francis Halzen and Dan HooperDIRECT DARK MATTER SEARCHES:EXPERIMENTSGaseous dark matter detectors G Sciolla and C J MartoffSearch for dark matter with CRESST Rafael F Lang and Wolfgang SeidelDIRECT AND INDIRECT PARTICLE DARK MATTER SEARCHES:THEORYDark matter annihilation around intermediate mass black holes: an update Gianfranco Bertone, Mattia Fornasa, Marco Taoso and Andrew R ZentnerUpdate on the direct detection of dark matter in MSSM models with non-universal Higgs masses John Ellis, Keith A Olive and Pearl SandickDark stars: a new study of the first stars in the Universe Katherine Freese, Peter Bodenheimer, Paolo Gondolo and Douglas SpolyarDetermining the mass of dark matter particles with direct detection experiments Chung-Lin ShanThe detection of subsolar mass dark matter halos Savvas M KoushiappasNeutrino coherent scattering rates at direct dark matter detectors Louis E StrigariGamma rays from dark matter annihilation in the central region of the Galaxy Pasquale Dario Serpico and Dan HooperDARK MATTER MODELSThe dark matter interpretation of the 511 keV line Céline BoehmAxions as dark matter particles Leanne D Duffy and Karl van BibberSterile neutrinos Alexander KusenkoDark matter candidates Lars BergströmMinimal dark matter: model and results Marco Cirelli and Alessandro StrumiaShedding light on the dark sector with direct WIMP production Partha Konar, Kyoungchul Kong, Konstantin T Matchev and Maxim PerelsteinAxinos as dark matter particles Laura Covi and Jihn E Kim

We consider electrically neutral complex-vector particles $V$ below the GeV mass scale that, from a low-energy perspective, couple to the photon via higher-dimensional form factor interactions. We derive ensuing astrophysical constraints by considering the anomalous energy loss from the Sun, Horizontal Branch, and Red Giant stars as well as from SN1987A that arise from vector pair production in these environments. Under the assumption that the dark states $V$ constitute dark matter, the bounds are then complemented by direct and indirect detection as well as cosmological limits. The relic density from freeze-out and freeze-in mechanisms is also computed. On the basis of a UV-complete model that realizes the considered effective couplings, we also discuss the naturalness of the constrained parameter space, and provide an analysis of the zero mass limit of $V$.

Cumulative observational evidence confirms that the surface gravity of dark matter (DM) halos μ0 D = r0ρ0, where r0 and ρ0 are the halo core radius and central density, respectively, is nearly constant and independent of galaxy luminosity for a high number of galactic systems (spirals, dwarf irregular and spheroidals, elliptics) spanning over 14 magnitudes in luminosity and of different Hubble types. Remarkably, its numerical value, μ0D ≃140M⊙/ pc 2 = (18.6 MeV )3, is approximately the same (up to a factor of 2) in all these systems. First, we present the physical consequences of the independence of μ0D from r0: the energy scales as the volume [Formula: see text], while the mass and the entropy scale as the surface [Formula: see text] and the surface times log r0, respectively. Namely, the entropy scales similarly to the black hole entropy but with a much smaller coefficient. Second, we compute the surface gravity and the density profile for small scales from first principles and the evolution of primordial density fluctuations from the end of inflation till today using the linearized Boltzmann–Vlasov equation. The density profile ρ lin (r) obtained in this way decreases as r-1-ns/2 for intermediate scales, where ns≃0.964 is the primordial spectral index. This scaling is in remarkable agreement with the empirical behavior found observationally and in N-body simulations: r-1.6±0.4. The observed value of μ0D indicates that the DM particle mass m is on the keV scale. The theoretically derived density profiles ρ lin (r) turn to be cored for m on the keV scale and they are cusped for m on the GeV scale or beyond. We consider both fermions and bosons as DM particles decoupling either ultrarelativistically or nonrelativistically. Our results do not use any particle physics model and vary slightly with the statistics of the DM particle.

We study the phenomenology of a light (GeV scale) sterile neutrino sector and the pseudo-Goldstone boson (not the majoron) associated with a global symmetry in this sector that is broken at a high scale. Such scenarios can be motivated from considerations of singlet fermions from a hidden sector coupling to active neutrinos via heavy right-handed seesaw neutrinos, effectively giving rise to a secondary, low-energy seesaw framework. This framework involves rich phenomenology with observable implications for cosmology, dark matter, and direct searches, involving novel sterile neutrino dark matter production mechanisms from the pseudo-Goldstone-mediated scattering or decay, modifications of BBN bounds on sterile neutrinos, suppression of canonical sterile neutrino decay channels at direct search experiments, late injection of an additional population of neutrinos in the Universe after neutrino decoupling, and measurable dark radiation.

We perform an analysis of the influence of non-standard neutrino interactions (NSI) on neutrino signal from dark matter annihilations in the Sun. Taking experimentally allowed benchmark values for the matter NSI parameters we show that the evolution of such neutrinos with energies at GeV scale can be considerably modified. We simulate propagation of neutrinos from the Sun to the Earth for realistic dark matter annihilation channels and find that the matter NSI can result in at most 30% correction to the signal rate of muon track events at neutrino telescopes. Still present experimental bounds on dark matter from these searches are robust in the presence of NSI within considerable part of their allowed parameter space. At the same time electron neutrino flux from dark matter annihilation in the Sun can be changed by a factor of few.

The 2nd International Conference on Particle Physics and Astrophysics (ICPPA-2016) was held in Moscow, Russia, from October 10 to 14, 2016. The conference is organized by the National Research Nuclear University “MEPhI”. The aim of the Conference is to promote contacts between scientists and to develop new ideas in fundamental research. We bring together experts and young scientists working on experimental and theoretical aspects of nuclear, particle and astroparticle physics and cosmology.The conference covers a wide range of topics such as accelerator physics, (astro) particle physics, cosmic rays, cosmology and methods of experimental physics: detectors and instruments. These directions are unified by development of the Standard Model which is evidently not complete. There are deviations from the Standard Model: neutrino oscillations, the dark matter existence. Together with strong interactions they are main subjects of the Conference.New results from leading high energy physics collaborations are discussed. Main LHC experiments (ATLAS, CMS, ALICE) presented their results and detector upgrade prospects on the conference. Various aspects of Standard Model testing and search for new phenomena are main subjects of the conference. Among them: flavor physics at B factories, precision multi-boson production measurements, dark matter searches.Electroweak interaction was discussed in the talks given by participants of neutrino physics experiments (Borexino, Neutrino-4, SOX, T2K and others). Enigmatic properties of neutrinos such as their tiny masses, oscillations between different neutrino types, cannot be explained in frame of the modern theory and require new approaches. Properties of neutrinos influenced the formation of the large-scale structure of the Universe and may be neutrinos are partially responsible for the excess of matter over anti-matter. Also our current challenge is the nature of the Dark matter. Many opportunities arise with the development of neutrino detection technologies comprising: measurements of neutrinos from the Sun, measurements of geo-neutrino from the deep interior of the Earth, detecting neutrino fluxes from supernovae and different astrophysical sources. They were the subject of discussion which have been held at the conference. Neutrino physics experiments make huge demands to technologies like ultra-high precision measurements, huge detector size, excellent reliability and ultra-low radioactive background.AcknowledgmentsWe are thankful to Anotonova M M, Buzhan P Zh, Gurov Yu B, Vdovkina S S, Zherebtsova E S, Esipova E A, Kovylyaeva A A, Kozlov E S, Koshelenko D D, Matveev N A, Mayorov A G, Nigmatkulov G A, Novikov A S, Svadkovsky I V, Smirnov Yu S, Voronov S A and Yurin K O for the assistance in organizing the conference and heavy work on proceedings.Conference organizers would like to express their gratitude to the TFT company (supply and maintenance of CAEN equipment, delivery of equipment and components for scientific research) for their support.

micrOMEGAs5.0 : Freeze-in

This chapter starts with the known and candidate elementary and composite particles that the previous chapter discusses and shows possibilities for correlating with or anticipating data about cosmology or astrophysics. We show models that possibly correlate with various cosmological phenomena and with various astrophysical phenomena. People might say that some models point to how to close some gaps between physics data and results from traditional theory. People might say that results in this chapter might correlate with or provide insight about the following aspects of physics. Mechanisms governing the rate of expansion of the universe. Dark energy. Dark matter. Stuff other than ordinary matter, dark matter, and dark-energy stuff. Ratios of densities of dark matter to densities of ordinary matter. Clustering and anti-clustering mechanisms, regarding ordinary matter and dark matter. Objects, such as galaxies, that include both ordinary matter and dark matter. A mechanism possibly leading to imbalance between matter and antimatter. Mechanisms, correlating with quantum phenomena, that may correlate with phenomena people describe via general relativity. The galaxy rotation problem. Phenomena regarding the spacecraft flyby anomaly. Mechanisms leading to quasars. Cosmic microwave background cooling. Some phases, for quark-based plasmas.

The mechanism behind electroweak symmetry breaking (EWSB) and the nature of dark matter (DM) are currently very important issues in particle physics. Usually, in most models, these two issues are not or poorly connected. However, since a natural dark matter candidate is a weakly interacting massive particle or WIMP, with mass around the electroweak scale, it is clearly of interest to investigate the possibility that DM and EWSB are closely related. In the context of a very simple extension of the Standard Model, the Inert Doublet Model, we show that dark matter could play a crucial role in the breaking of the electroweak symmetry. In this model, dark matter is the lightest component of an inert scalar doublet which can induce dynamically electroweak symmetry breaking at one loop level. Moreover, in a large fraction of the parameter space of this model, the mass of the dark matter particle is essentially determined by the electroweak scale, so that the fact that the WIMP DM mass is around the electroweak scale is not a coincidence.