Olivefest: Astroparticle Physics Looking Forward 2017
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Item A Bitter Pill? The Primordial Lithium Problem(2017-05) Fields, BrianBig-bang nucleosynthesis (BBN) describes the production of the lightest elements during the first three minutes of cosmic time, and represents our earliest reliable probe of the universe. BBN has stood as both cornerstone of modern cosmology and particle astrophysics, and Keith Olive has made fundamental contributions to BBN over a span of four decades. I will review BBN and Keith's hand in it, emphasizing the transformative influence of cosmic microwave background experiments in precisely determining the cosmic baryon density. Standard BBN combines this with the Standard Model of particle physics to make tight predictions for the primordial light element abundances. Deuterium observations match these predictions spectacularly, helium observations are in good agreement, but lithium observations (in metal-poor halo stars) are significantly discrepant-–this is the ”lithium problem.” Over the past decade, the lithium discrepancy has become more severe, and very recently the solution space has shrunk dramatically, with all resolutions of the problem facing stringent constraints. Future observations will either confirm surprises in stellar astrophysics, or most intriguingly, could reveal new physics at play in the early universe.Item Keith’s dark side (and some others)(2017-05) Ellis, JohnAfter some historical and personal reminiscences, I will discuss what we can learn about the possible scale of supersymmetry from the density of dark matter, and the prospects for discovering supersymmetry at the LHC, in direct searches for dark matter scattering and in experiments at future colliders.Item Banquet Presentation(2017-05) Ellis, JohnItem Large field inflation: Recent progress and observational predictions(2017-05) Linde, AndreiI will describe the new generation of inflationary models with plateau potentials and their observational predictions. I will also discuss the problem of initial conditions for inflation in such models.Item Stellar Explosions, Galactic Evolution, and my Encounters with Keith(2017-05) Thielemann, Friedrich-KarlItem What does it take to discover or falsify Weak Scale SUSY?(2017-05) Baer, HowieWhat does it take to discover or falsify weak scale SUSY (WSS)? What are the upper limits to parameter space and sparticle masses? This brings up the naturalness question. The most conservative measure requires weak scale contributions to m(W,Z,h)$ to be comparable to or less than the weak scale. This leads to an upper bound on m(gluino)<~5 TeV. In SUSY models with gaugino mass unification, it seems HL-LHC can just about cover all parameter space. In models such as mirage mediation with a compressed gaugino spectrum, then probably HE-LHC will be required. Alternatively, the ILC e+e- collider, should it be built with E(CM)~0.5-0.6 TeV, would either discover or rule out WSS via the search for higgsino pair production.Dark matter is expected to occur as an axion-higgsino admixture.Item Particle creation in the expanding universe(2017-05) Kolb, RockyThe big bang has often been called the ultimate particle accelerator, and physicists have used the enormous temperatures of the early universe as a laboratory for the study of new particles and new interactions. Less explored is another source for creation of particles in the big bang: gravitational production. I will discuss the production of particles from the vacuum caused by the expansion of the universe.Item Dark Matter: a Historical Perspective(2017-05) Srednicki, MarkI will review the impact of the dark matter problem on particle physics, and summarize where we stand today.Item Astrophysical Searches for Dark Matter: A Status Report(2017-05) Profumo, StefanoI will give an update on current status and future prospects in searching for the particle nature of dark matter with astronomical and cosmic ray observations. I will discuss a few more or less controversial signals, and how they can be tested and probed.Item Keith Inflated(2017-05) Nanopoulos, DimitriA Flipped Model for “Everything” below The Planck scale is presented.It is based on No-Scale Supergravity x Flipped SU(5),both components derivable,in principle,from string theory and providing: A SU(N,1) No-Scale Inflation ,avatarized as a Starobinsky -like model ,but with distinctive differences and automatically embedded in Flipped SU(5),specific Cosmological history of the Universe that leads to Supercosmology, strong reheating,controlled entropy release,baryon asymmetry ,on the nose,through RH heavy neutrinos,neutrino masses/ mixings,in accordance with present data and stable enough protons,but reachable ,in near future,lifetime,and a LHC attainable SUSY spectrum. Appropriately enough, Keith has played a pivotal role on all the above ,who sounds like the end (???) result of 35 years group work...Item Antimatter cosmic rays: recent results with the semi-analytic approach(2017-05) Salati, PierreThe nature of dark matter, an essential component of the Universe, is still unresolved. The best candidate is a weakly interacting particle yet to be discovered at accelerators. In most models, these exotic species annihilate and yield in particular antiprotons and positrons, hence the connection between the dark matter problem and antimatter cosmic rays. Distortions and anomalies in the antiproton and positron spectra are actively searched. A positron excess has actually been discovered and recently confirmed. But claiming that dark matter species have been discovered in the cosmic radiation requires to understand it and to properly model the various backgrounds in which the signal might be found. To achieve this goal, a key ingredient is the transport of charged particles within the magnetic halo of the Milky Way. In this talk, I will focus on a few (semi)-analytic methods used to solve the transport of cosmic rays and derive their fluxes at the Earth. I will then describe the so-called pinching method, which allows for a fast and reliable calculation of the positron spectrum even at low energies. Finally, with the help of this new tool, I will reinvestigate if dark matter can source the positron excess and I will set limits on MeV dark matter candidatesItem From local chemical evolution to cosmic chemical evolution(2017-05) Vangioni, ElisabethMy scientific life with Keith began about twenty five years ago with the study of the chemical evolution of light elements :cosmological elements D, He3, He4 and Li7 and spallative elements, LiBeB. Recently, major CMB results coming from WMAP and Planck, and observations of the total luminosity density leading to significant progress in establishing the star formation rate (SFR) at high redshift, led us to study in detail primordial stars say, Pop III stars, and their different properties (mass and associated nucleosynthesis, related ionizing power..), all that in a cosmological context. Presently, I will present the global cosmic chemical evolution within the framework of hierarchical formation of structures, in a merger tree context, to have a look at the early universe: reionization of the Universe, gamma ray burst and correlation with high z SFR, metal dispersion in DLAs... Finally, the discovery of gravitational waves coming from binary black holes mergers opens a new astrophysical window and we can, thanks to our nucleosynthetic approach, give some constraints on the cosmic binary compact object merger rates and associated stochastic gravitational backgroundItem the limits of cosmology(2017-05) Silk, JosephOne of our greatest challenges in cosmology is understanding the origin of the structure of the universe, and in particular the formation of the galaxies. I will describe how the fossil radiation from the beginning of the universe, the cosmic microwave background, has provided a window for probing the initial conditions from which structure evolved and seeded the formation of the galaxies. I will review the outstanding cosmological issues that remain to be resolved, and suggest an optimal choice of future strategy in order to make further progress on understanding our cosmic origins.Item Observational Constraints on the Primordial Helium Abundance(2017-05) Skillman, EvanI will review recent progress on the observational determination of the primordial helium abundance (Yp). Presently, the best constraints on Yp come from observations of star forming regions in very metal-poor galaxies (although the impact of Yp on the CMB has been detected). Progress has come through the discovery of more very metal-poor galaxies and by extending spectral observations in to the near infrared with, for example, the Large Binocular Telescope.Item Bringing Astrophysics and Cosmology to the Particle Data Book(2017-05) Barnett, MichaelFor 32 years, the outstanding work of Keith Olive has brought astrophysics and cosmology (A&C) to our community through his major contributions to the Particle Data Book. He has brought A&C to the Data Listings as well as to the eight Review articles. PDG is a large collaboration of 223 authors from 148 institutions in 24 countries. During the Olive era, citations grew enormously. For the last edition, downloads of the A&C reviews totaled 137,000.Item Baryogenesis from Dark Sector(2017-05) Kainulainen, KimmoThe measured Higgs mass value 125 GeV may suggest that standard model (SM) may be UV-complete up to Planck scale. Yet, questions of the nature of the dark matter and of the origin of baryons remain unsolved in the SM. The latter is particularily difficult to address in UV-complete low energy extensions of SM. The main problem is finding enough CP-violation consistent with existing laboratory bounds. I will show that a simple UV-complete model, with a fermionic dark matter particle X coupling to a new singlet scalar S can realize successful electroweak baryogenesis. In our model X gets a CP asymmetry that is transferred to the standard model through a CP portal interaction, coupling X to tau leptons and an inert Higgs doublet. The CP asymmetry induced in left-handed tau leptons biases sphalerons to produce the baryon asymmetry. The model has promising discovery potential at the LHC, while robustly providing a large enough baryon asymmetry and correct dark matter relic density with reasonable values of the couplings.Item Ultra-light Axion Dark Matter and CMB B-mode Polarization(2017-05) Ng, Kin-WangWe propose a new source of anisotropic cosmic birefringence induced by dark matter adiabatic density perturbation. If dark matter is ultralight axions that carry a coupling to photon, its adiabatic density fluctuations will induce anisotropic cosmic birefringence with a blue-tilted rotation power spectrum, thus generating CMB B-mode polarization on sub-degree angular scales. It is shown that the birefringence B modes can dominate over CMB lensing B modes at high l, manifesting as an excess power for l>1500 in future CMB lensing B-mode searches.Item Light particle solutions to the cosmological lithium problem(2017-05) Pospelov, MaximItem Minimal model of gravitino DM(2017-05) Mambrini, YannMotivated by the absence of SUSY signal at LHC, we consider a scenario where supersymmetry is broken at a scale above the reheating temperature and/or the inflaton mass. The low energy particle content consists then only in Standard Model states and a gravitino. We investigate the possibility that the latter provides the main component of dark matter through the annihilation of thermalized Standard Model particles. We identify the parameter space allowed by the cosmological constraints, allowing the possibility of large reheating temperature compatible with leptogenesis scenarios, alleviating the so called "gravitino problem"Item Dark Stars: Dark Matter Annihilation can power the first stars(2017-05) Freese, KatherineThe first phase of stellar evolution in the history of the Universe may be Dark Stars (DS), powered by dark matter heating rather than by nuclear fusion. Weakly Interacting Massive Particles, which may be their own antipartners, collect inside the first stars and annihilate to produce a heat source that can power the stars. A new stellar phase results, a Dark Star, powered by dark matter annihilation as long as there is dark matter fuel, with lifetimes from millions to billions of years. Dark stars are very bright diffuse puffy objects during the DS phase, and grow to be very massive. In fact, we have found they can to grow to 10^5-10^7 solar masses with luminosities 10^9-10^11 solar luminosities. Such objects will be observable with James Webb Space Telescope (the sequel to HST). Once the dark matter fuel is exhausted, the DS becomes a heavy main sequence star; these stars eventually collapse to form massive black holes that may provide seeds for supermassive black holes observed at early times as well as in galaxies today.