DOCSLIB.ORG

Abstracts Dark Universe.Odt

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Abstracts Dark Universe.Odt TALKS Rouzbeh Allahverdi - Nonthermal Dark Matter and Baryogenesis We study a simple TeV-scale model of baryon number violation which explains the observed proximity of the dark matter and baryon abundances. The model has constraints arising from both low and high-energy processes, and in particular, predicts a sizable rate for the neutron-antineutron (n−n¯) oscillation at low energy and the monojet signal at the LHC. We find an interesting complementarity among the constraints arising from the observed baryon asymmetry, ratio of dark matter and baryon abundances, n−n¯ oscillation lifetime and the LHC monojet signal. There are regions in the parameter space where the n−n¯oscillation lifetime is found to be more constraining than the LHC constraints, which illustrates the importance of the next-generation n−n¯oscillation experiments. Otávio Alonso - Probing Dark Matter properties using photometric surveys Despite decades of its first proposal, Dark Matter is still one of the big mysteries in cosmology. Different probes can shed light into different aspects of it, but they agree in a good level that it can be modeled as a pressureless perfect fluid, although we have reason to call that into question. Here we discuss how can we learn about Dark Matter from weak lensing and galaxy clustering in the context of photometric surveys. In particular, we present a phenomenological framework that generalizes DM behavior and look for constraints using The Dark Energy Survey data. Yang Bai - Primordial Extremal Black Holes as Dark Matter We show that primordial (nearly) extremal black holes with a wide range of masses from the Planck scale to around 1000 tons could be cosmologically stable and explain dark matter, given a dark electromagnetism and a heavy dark electron. The merger events of binary systems provide an opportunity to directly observe Hawking radiation. Because the merger products are not extremal, they rapidly evaporate and produce transient high-energy neutrino and gamma ray signals that can be observed at telescopes like IceCube and HAWC. Ronaldo Batista - Describing Warm Dark Matter with the Reduced Relativistic Gas The Reduced Relativistic Gas (RRG) is a simplified version of the ideal relativistic gas, which assumes that all particles have the same momentum magnitude. Although this is a very idealized situation, the resulting model preserves the phenomenology of Maxwell-Boltzmann distribution and, in some situations, can be described as a perfect fluid, without introducing large errors in both cosmological background and first-order perturbations. The perfect fluid description of RRG model was already used to study the warmness of dark matter, massive neutrinos and interaction of baryons and photons before recombination, showing very good agreement with previous works based on the full Einstein-Boltzmann system of equations. In order to understand these results and construct a more general and formal framework for RRG, we develop a theoretical description of first-order cosmological perturbations of RRG, based on a distribution function which encodes the simplifying assumption that all particles have the same momentum magnitude. The full set of Einstein-Boltzmann equations for RRG distribution are derived and quantities beyond the perfect fluid approximation are studied. Using RRG to describe warm dark matter, we show that, for particles with m∼ keV, the perfect fluid approximation is valid on scales k<10h/Mpc, for most of the universe evolution. We also determine initial conditions for RRG in the early universe and study the evolution of potential in a toy model of universe composed only by RRG. Antonio Delgado – Higgsino DM from natural susy We consider a minimal natural supersymmetric model based on an extra dimension with supersymmetry breaking provided by the Scherk-Schwarz mechanism. The lightest supersymmetric particle is a neutral, quasi-Dirac Higgsino and, unlike in previous studies, we assume that all Standard Model fields are propagating in the bulk. The resulting setup is minimal, as neither extra matter, effective operators, nor extra U(1) groups are needed in order to be viable. Pasquale di-Bari - A unified model of neutrino masses, dark matter and leptogenesis testable at Neutrino Telescopes Despite the lack of evidence of new physics at colliders, neutrino masses, dark matter and matter-antimatter asymmetry of the universe require an extension of the Standard Model. After discussing some new concepts and tools in the description of seesaw neutrino models, such as motion in flavour lepton space and the introduction of the bridging matrix that nicely complements the orthogonal matrix, I discuss recent developments in the connections between neutrino data and scenarios of leptogenesis within some well motivated extensions of the Standard Model. Finally, I briefly review a simple unified picture of neutrino masses, leptogenesis and dark matter based on an extension of the seesaw Lagrangian where a non- renormalizable effective operator coupling right-handed neutrinos to the Higgs is introduced. This operator enhances the right-handed neutrino mixing between a coupled heavy right-handed neutrino and a decoupled one playing the role of dark matter. Interference between the two coupled RH neutrinos generate usual CP violation so that one can also achieve successful leptogenesis. Although the dark matter right- handed neutrino escapes direct and collider searches, its decays produce a detectable contribution to the very high energy neutrino flux now discovered by IceCube, so that the model is predictive and can be tested at neutrino telescopes. Marcos Cardoso -NMSSM and Dark Matter We will present in one very nice SUSY B-L model some nice candidate to Dark Matter. I can if it is necessary give talk (another poster) about Next to Minimal Supersymmetric Standard Model (NMSSM) and also the General Singlet Extensions of the MSSM (GSEMSSM) models. We can show we can get pseudoscalars and neutralinos can give nice results in some cosmological analyses as presented Francesco D'Eramo - Displaced new physics at colliders and the pre-BBN universe Sylvain Fichet – The warped dark sector I present a dark sector scenario based on a 5d AdS space. Such a construction, also motivated as the AdS dual of a composite dark sector, naturally leads to models in which parts of the dark sector vanish at high 4d momentum or temperature.This sense of AdS "opacity" arises as a result of the dressing of propagators by bulk interactions. Exotic signatures are possible from laboratory to cosmological scales, including long-range forces with non-integer behaviour, non-standard momentum losses, periodic signals at colliders, “soft bombs” events, as well as a dark phase transition and a typically small amount of dark radiation. Vesselin Gueorguiev - The Scale Invariant Vacuum Theory as viable Cosmology Model Recent studies in applying the Weyl's original gauge symmetry idea within the framework of the Weyl's Integrable Geometry to modern observational data in cosmology has resulted in the Scale Invariant Vacuum Theory (SIVT) idea. A sequence of papers by Prof. André Maeder has shown that SIVT is a viable contender to standard LamdaCDM model. It has been also shown that the growth of the density perturbations of the early universe can be modeled within SIVT without the need of dark matter. Furthermore, SIVT has been able to explain the asymptotic limit of the Radial Acceleration Relation (RAR) in Dwarf Spheroidals better than MOND and Dark Matter models. An overview of the SIVT results will be summarized and discussed subject to the time constraints of the workshop. Nathan Herring - Particle Decay in the Expanding Spacetime of Post-Inflationary Cosmology The calculation of particle decay rates typically proceeds by an S-matrix approach in Minkowski spacetime. While such an approach is often highly eff ective, it fails, in general, when performing calculations in dynamic spacetimes since the S-matrix necessitates global energy conservation which is not present in an expanding universe, like ours. I will describe how the decay law of scalar particles decaying during the radiation dominated epoch of a standard cosmological model can be obtained by introducing an adiabatic approximation valid for degrees of freedom with typical wavelengths much smaller than the particle horizon at a given time. Furthermore, this decay law is calculated, treating the cosmological expansion consistently, through the non-perturbative Wigner-Weisskopf method adapted for cosmology. I will discuss both scalar to scalar and scalar to fermion (with Yukawa couplings) decays within this framework highlighting how the effects of cosmic expansion, such as cosmic redshift and the confluence of time-dependent particle frequencies with a renormalizable theory, lead to salient differences from the usual Minkowski spacetime results. Finally I will discuss implications for very long-lived particles (DM) and baryogenesis. Jay Hubisz - Cosmology of Brane Worlds From Symmetry Principles Alejandro Ibarra - Astrophysical Uncertainties on Local Dark Matter Searches Dark matter substructure can contribute significantly to local dark matter searches and may provide a large uncertainty in the interpretation of those experiments. For direct detection experiments, sub-halos give rise to an additional dark matter component on top of the smooth dark matter distribution of the host halo. In the case of dark matter capture in the Sun, sub-halo encounters temporarily increase the number of captured particles. We assess the impact of sub-halos on direct dark matter searches in a probabilistic way. Markus Luty - Blowing in the Dark Matter Wind Light bosonic dark matter can interact with ordinary matter, giving rise to steady-state forces from the dark matter wind that are small but potentially observable. We compute these forces and give some estimates of experimental sensitivities to them. Adam Martin - Custodial Dark Pions A new, strongly-coupled dark sector could be accessible to LHC searches now. These dark sectors consist of composites formed from constituents that are charged under the electroweak group and interact with the Higgs, but are neutral under Standard Model color.
Load more

Recommended publications
  • Cosmology Falling in Love with Sterile Neutrinos
    Cosmology Falling in Love with Sterile Neutrinos Jörn Kersten Based on Torsten Bringmann, Jasper Hasenkamp, JK, JCAP 07 (2014) [arXiv:1312.4947] Outline 1 Introduction 2 Self-Interacting Dark Matter 3 Dark Matter Interacting with Neutrinos 3 / 23 1 Introduction 2 Self-Interacting Dark Matter 3 Dark Matter Interacting with Neutrinos 4 / 23 Or does it? Tensions in ΛCDM cosmology The Universe after Planck Flat ΛCDM cosmology fits data perfectly Planck, arXiv:1303.5062 5 / 23 The Universe after Planck Flat ΛCDM cosmology fits data perfectly Planck, arXiv:1303.5062 Or does it? Tensions in ΛCDM cosmology 5 / 23 Measurements of Cosmic Microwave Background (CMB): ∆Neff = 1:51 ± 0:75 at 68% CL ACT, ApJ 739 (2011) ∆Neff = 0:81 ± 0:42 at 68% CL SPT, ApJ 743 (2011) +0:68 ∆Neff = 0:31−0:64 at 95% CL Planck, arXiv:1303.5076 Hints for Dark Radiation Dark radiation: relativistic particles 6= γ; νSM Parameterized via radiation energy density " # 7 T 4 ρ ≡ 1 + N ν ρ rad eff 8 T γ T ≡ Tγ Neff: effective number of neutrino species Standard Model: Neff = 3:046 Existence of dark radiation , ∆Neff ≡ Neff − 3:046 > 0 6 / 23 Hints for Dark Radiation Dark radiation: relativistic particles 6= γ; νSM Parameterized via radiation energy density " # 7 T 4 ρ ≡ 1 + N ν ρ rad eff 8 T γ T ≡ Tγ Neff: effective number of neutrino species Standard Model: Neff = 3:046 Existence of dark radiation , ∆Neff ≡ Neff − 3:046 > 0 Measurements of Cosmic Microwave Background (CMB): ∆Neff = 1:51 ± 0:75 at 68% CL ACT, ApJ 739 (2011) ∆Neff = 0:81 ± 0:42 at 68% CL SPT, ApJ 743 (2011) +0:68
    [Show full text]
  • Cosmological Anomalies Shed Light on the Dark Sector
    COSMOLOGICAL ANOMALIES SHED LIGHT ON THE DARK SECTOR by Tanvi Karwal A dissertation submitted to The Johns Hopkins University in conformity with the requirements for the degree of Doctor of Philosophy. Baltimore, Maryland June, 2019 c 2019 Tanvi Karwal ⃝ All rights reserved Abstract Little is known about dark energy and dark matter; but their simple descriptions in the ΛCDM model of cosmology fit numerous datasets well. Recently however, tensions have emerged between the results of different datasets, as have certain unex- pected results. These anomalies may indicate new physics beyond ΛCDM; a revision of how we describe the dark sector. My work uses cosmological anomalies to explore the dark sector. My research resolves perhaps the most exciting tension in cosmology, the Hubble tension, with early dark energy (EDE). I developed two physical models for EDE and find that these models not only solve the Hubble tension, but also fit mostcosmolog- ical datasets well. No other solution to the Hubble tension proposed thus far can do both - fully solve the tension while still fitting early and late-time measurements of the Universe. The model that succeeds ΛCDM should solve not only the Hubble tension but ii ABSTRACT also other cosmological tensions such as the S8 anomaly. My research investigates a decaying dark matter model to address both tensions simultaneously but finds the constraints from late-universe observations too stringent to permit a full resolution. I am also building a phenomenological tool to model the dark sector in a widely- used cosmological code. This tool, generalised dark matter, is a powerful formalism capable of emulating the effects of a wide variety of dark matter and dark energy models, simplifying placing constraints on different fundamentally-motivated models.
    [Show full text]
  • Dark Radiation and Dark Matter from Primordial Black Holes
    DARK RADIATION AND DARK MATTER FROM PRIMORDIAL BLACK HOLES Dan Hooper – Fermilab and the University of Chicago Next Frontiers in the Search for Dark Matter, GGI September 26, 2019 Dan Hooper – Dark Radiation & Dark Matter from PBHs This talk is based on Dark Radiation and Superheavy Dark Matter from Black Hole Domination With Gordan Krnjaic and Sam McDermott, JHEP 1908 (2019) 001, arXiv:1905.01301 For related work, see Morrison and Profumo, arXiv:1812.10606 and Lennon et al, arXiv:1712.07664 Dan Hooper – Dark Radiation & Dark Matter from PBHs Was the Early Universe Dominated by Black Holes? § Inhomogeneities in the early universe can led to the formation of primordial black holes § Very roughly, we expect the mass of these black holes to be similar to the energy enclosed within the horizon at or near the end of inflation: § In this mass range, black holes evaporate very rapidly, disappearing well before BBN § If even a small fraction of the energy density after inflation was in the form of black holes, this fraction would grow as the universe expands -3 (black holes evolve as matter, �BH � a , rather -4 than radiation, �rad � a ); § From this perspective, it is well-motivated to consider scenarios in which the early universe included an era in which the energy density was dominated by black holes Dan Hooper – Dark Radiation & Dark Matter from PBHs Was the Early Universe Dominated by Black Holes? § Quantitatively, the density of black holes will ultimately exceed the energy density in SM radiation (before the black holes evaporate) if the
    [Show full text]
  • Dark Radiation from the Axino Solution of the Gravitino Problem
    21st of July 2011 Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp II. Institute for Theoretical Physics, University of Hamburg, Hamburg, Germany [email protected] Abstract Current observations of the cosmic microwave background could confirm an in- crease in the radiation energy density after primordial nucleosynthesis but before photon decoupling. We show that, if the gravitino problem is solved by a light axino, dark (decoupled) radiation emerges naturally in this period leading to a new upper 11 bound on the reheating temperature TR . 10 GeV. In turn, successful thermal leptogenesis might predict such an increase. The Large Hadron Collider could en- dorse this opportunity. At the same time, axion and axino can naturally form the observed dark matter. arXiv:1107.4319v2 [hep-ph] 13 Dec 2011 1 Introduction It is a new opportunity to determine the amount of radiation in the Universe from obser- vations of the cosmic microwave background (CMB) alone with precision comparable to that from big bang nucleosynthesis (BBN). Recent measurements by the Wilkinson Mi- crowave Anisotropy Probe (WMAP) [1], the Atacama Cosmology Telescope (ACT) [2] and the South Pole Telescope (SPT) [3] indicate|statistically not significant|the radi- ation energy density at the time of photon decoupling to be higher than inferred from primordial nucleosynthesis in standard cosmology making use of the Standard Model of particle physics, cf. [4,5]. This could be taken as another hint for physics beyond the two standard models. The Planck satellite, which is already taking data, could turn the hint into a discovery. We should search for explanations from particle physics for such an increase in ra- diation [6,7], especially, because other explanations are missing, if the current mean values are accurate.
    [Show full text]
  • The Early Universe As a Laboratory for Particle Physics
    The Early Universe as a Laboratory for Particle Physics Nikita Blinov April 6, 2021 York University Triumph of the Standard Model Standard Model describes properties and interactions of leptons, quarks and force carriers 100+ years of science !"#N $ift Shop 2 Triumph of the Standard Model Standard Model describes properties and interactions of leptons, quarks and force carriers 100+ years of science !"#N $ift Shop Enormous dynamic range when combined with gravity ,ar)e Hadron Collider probes ~10-20 m Cosmic Micro(ave Background: ~10+24 m 3 The Cosmological Fine Print 4n largest scales, the universe is (ell-described by a %andf l of para'eters Planck ‘18 Only 'eas red indirectly 2%y not 03 .nconsistent (it% q ant m estimates No candidate in Standard Model 4 The Expanding Universe 6ar-a(ay ob7ects (like )alaxies) are receding fro' s - bble (1929) "arlier estimates by Lemaitre (1927) and #obertson (1928) 5 The Expanding Universe 6ar-a(ay ob7ects (like )alaxies) are receding fro' s - bble (1929) 6 #iess et al 2019 Expansion in General Relativity $eneral #elativity relates expansion rate to t%e contents of the niverse Hotter and denser in the past! 7 Early Universe Primer =%e niverse e9panded from a %ot dense state "volution described by C>1 $yr 1 !o'pare (it%* Solar s rface* = ~ 0>? e@ #oo' te'p* = ~ 1AB0 e@ Galaxy formation, life etc 8 Early Universe Primer =%e niverse e9panded from a %ot dense state "volution described by C10 000 yr 1C>1 $yr !o'pare (it%* Solar s rface* = ~ 0>? e@ #oo' te'p* = ~ 1AB0 e@ -ydrogen recombination: Galaxy formation,
    [Show full text]
  • Strategic Overview of Fermilab Particle Astrophysics Program
    Strategic Overview of Fermilab Particle Astrophysics Program Craig Hogan PAC 16 January 2015 Particle Astrophysics at Fermilab Fermilab (and HEP) mission: study the fundamental nature of matter, energy, space and time Cosmic studies uniquely probe deep mysteries: dark matter, cosmic acceleration, neutrino mass, gravity Challenging experiments require capabilities of national laboratories: technologies, development, engineering, scale, management DOE labs share effort on most cosmic experiments Program is planned with University community Fermilab’s plan is based on the scientific drivers in the HEPAP P5 report, as shaped by community support needs, agency funding opportunities, and unique laboratory capabilities 2 Craig Hogan | Particle Astrophysics Program 1/8/15 Fermilab Center for Par0cle Astrophysics Strategic Plan - January 2015 P5 Driver Experiments Dark Maer G1: SuperCDMS Soudan, COUPP/PICO, Darkside, DAMIC G2: SuperCDMS SNOLAB, LZ, ADMX G3: R&D towards advanced WIMP and Axion experiments Dark Energy DES, DESI, LSST CMB SPT-3G, CMB-S4 Exploring the Holometer, Pierre Auger Unknown Detector R&D R&D on new techniques for par0cle astrophysics experiments Astrophysics Strong coupling with par0cle astrophysics experiments Theory Dark Matter Astrophysical evidence suggests that most of our Galaxy is made of a new form of matter Theory suggests that it may be detectable in this decade Weakly Interacting Massive Particles (WIMPs) Axions (solution to CP problem of strong interactions) P5: diverse program for direct detection of WIMPs and axions
    [Show full text]
  • Cosmology in LARGE Volume String Models
    2013 Oct.24th@Tohoku Moduli-Induced Axion Problem Tetsutaro Higaki (KEK) 1208.3563 and 1304.7987 with K. Nakayama and F. Takahashi 2013 Oct.24th@Tohoku Moduli-Induced Axion Probe for extra dimensions Tetsutaro Higaki (KEK) 1208.3563 and 1304.7987 with K. Nakayama and F. Takahashi Cosmological test for string models CMB Ex-dim. + D-branes Axionic dark radiation (= relativistic DM): ΔNeff = O(0.1) Key: Moduli problem in reheating Φ: Moduli/Inflaton a: Axion Axionic dark radiation exists even for mΦ >> 100TeV. Dark radiation Dark radiation ΔNeff in ρrad ΔNeff: Dark radiation, Neff: Effective neutrino number, 3.046: The SM value Effective neutrino number Neff • Observations from Planck (95%): [Planck collaborations] (CMB) (CMB+BAO) (CMB+H0) Effective neutrino number Neff • Observations from Planck (95%): [Planck collaborations] (CMB) (CMB+BAO) (CMB+H0) Dark radiation is hinted, while tension between H0 measurement and CMB/BAO. See also [Hamann and Hasenkamp]: (CMB+HST+C+BAO+WL) Axions in string theory: Dark radiation candidates QCD axion: Strong CP and CDM Ultralight . Original motivations: • A solution of strong CP problem: θ < 10-10 • A candidate of CDM Motivation for string theory Unified theory including quantum gravity! Gauge Matter Gravity D-brane Axions in string theory • Axions via compactifications: C n: n-form gauge field for strings/branes. They can be ultralight and very weak – shift symmetry:aaaaaaaaaaaa; – solution of CP and/or CDM with Moduli Reheating field: • String moduli: Long lifetime: Light + 1/MPl (if SUSY) • Other possibilities: – Inflaton (also in non-SUSY if coupled to axions) – Open string state, e.g., SUSY-breaking fields [Coughlan et al.] Moduli oscillation Radiation Vinflation Vmoduli : moduli VEV : Inflaton potential The decay = Reheating + dark radiation.
    [Show full text]
  • CF1 Sterile Neutrino Dark Matter Bibhushan
    STERILE NEUTRINO DARK MATTER MODELS / THEORY BIBHUSHAN SHAKYA SNOWMASS CF1 MEETING SEPTEMBER 11, 2020 1 STERILE NEUTRINO DARK MATTER MODELS / THEORY AN (INCOMPLETE, RAPID) OVERVIEW For greater details, see one of several reviews in the literature, e.g. • Sterile Neutrino Dark Matter; Boyarsky+, 1807.07938 • A White Paper on keV Sterile Neutrino Dark Matter; Adhikari+, 1602.04816 • Sterile Neutrino Dark Matter from Freeze-in; Shakya, 1512.02751 • The Phenomenology of Right Handed Neutrinos; Drewes, 1303.6912 • keV Neutrino Model Building; Merle, 1302.2625 • … 2 WHY STERILE NEUTRINOS (AS DARK MATTER) ? • Neutrino masses require BSM, most straightforward implementations feature right handed/sterile neutrinos • Very weakly coupled to SM sector: small but non-negligible production in early Universe, as well as long lifetime, are “automatic” • Relatively straightforward/predictive phenomenology: depends mostly on the sterile neutrino mass and mixing angle with SM neutrinos. Diverse signatures: extended neutrino sectors generally feature observable signals in indirect detection, cosmology, colliders, low energy (neutrino) experiments • Hints of sterile neutrinos at several experiments (3.5 keV line, short baseline anomalies) 3 STERILE NEUTRINO AS DARK MATTER: CAVEATS (PROBLEMS / OPPORTUNITIES) • MASS SCALE: The natural value of the mass of a singlet is at the cutoff scale of the theory (e.g. Planck or GUT scale), most of the viable DM candidates have much lower masses (sub-electroweak scale) • Not a disaster: singlet fermion mass does not get large quantum corrections (unlike the higgs); Seesaw mechanism works across a wide range of mass scales (from keV to GUT scale) Nevertheless, need an explanation for the mass scale 4 STERILE NEUTRINO AS DARK MATTER: CAVEATS (PROBLEMS / OPPORTUNITIES) • MASS SCALE: The natural value of the mass of a singlet is at the cutoff scale of the theory (e.g.
    [Show full text]
  • WISP Dark Matter Theory
    WISP Dark Matter Theory. Andreas Ringwald (DESY) Latest Results in Dark Matter Searches Stockholm, Sweden 12-14 May 2014 Introduction > Plenty of dark matter (DM) candi- dates spanning huge parameter range in masses and couplings > Two classes stand out because of their convincing physics case and the variety of experimental and observational probes: § Weakly Interacting Massive Particles (WIMPs), such as neutralinos § Very Weakly Interacting Slim (=ultra- light) Particles (WISPs), such as axions, axion-like particles and hidden photons [Kim,Carosi `10] Andreas Ringwald | WISP Dark Matter Theory, Latest Results in Dark Matter Searches, Stockholm, 12-14 May 2014 | Page 2 Theoretically favored WISP candidates > Pseudo Nambu-Goldstone bosons: § “Axion-Like Particles” (ALPs) arising from breaking of global U(1) symmetries at high energy scale f a ; angular part of complex SM singlet Higgs-like field • Low energy effective field theory has shift symmetry a ( x ) a ( x ) + const . , forbidding 2 2 explicit mass terms, m a a ( x ) , in the Lagrangian ! • Effective couplings to/ SM particles suppressed by powers of high energy scale f a , e.g. coupling to photons, ↵ a C F F˜µ⌫ aγ µ⌫ L ⊃−8⇡ fa • Examples: • Axion from breaking of global chiral symmetry; axion field acts as dynamical theta parameter, [Peccei,Quinn 77; Weinberg 78; Wilczek 78] spontaneously relaxing to zero, (thus CP conserved in strong interactions) • mass due to chiral symmetry breaking, • Majoron from breaking of global lepton number symmetry [Chikashige et al. 78] • high scale
    [Show full text]
  • On Dark Matter - Dark Radiation Interaction and Cosmic Reionization
    IITB-PHY11122017 PREPARED FOR SUBMISSION TO JCAP On dark matter - dark radiation interaction and cosmic reionization Subinoy Das,a Rajesh Mondal,b;c Vikram Rentala,d Srikanth Suresha aIndian Institute of Astrophysics, Bengaluru – 560034, India bAstronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH, U.K. cDepartment of Physics and Centre for Theoretical Studies, Indian Institute of Technology Kharag- pur, Kharagpur – 721302, India dDepartment of Physics, Indian Institute of Technology - Bombay, Powai, Mumbai 400076, India E-mail: [email protected], [email protected], [email protected], [email protected] Abstract. The dark matter sector of our universe can be much richer than the conventional picture of a single weakly interacting cold dark matter particle species. An intriguing possibility is that the dark matter particle interacts with a dark radiation component. If the non-gravitational interactions of the dark matter and dark radiation species with Standard Model particles are highly suppressed, then astrophysics and cosmology could be our only windows into probing the dynamics of such a dark sector. It is well known that such dark sectors would lead to suppression of small scale structure, which would be constrained by measurements of the Lyman-α forest. In this work we consider the cosmological signatures of such dark sectors on the reionization history of our universe. Working within the recently proposed “ETHOS” (effective theory of structure formation) framework, we show that if such a dark sector exists in our universe, the suppression of low mass dark matter halos would also reduce the total number of ionizing photons, thus affecting the reionization history of our universe.
    [Show full text]
  • Dark Radiation IAXO
    Dark radiation in IAXO José Manuel Carmona Universidad de Zaragoza 1. The axiverse from string theory 2. Moduli and dark radiation 3. The cosmic axion background and IAXO References: Arvanitaki et al., PRD 81 (2010) Conlon & Marsch, JHEP 10 (2013), PRL 111 (2013) J. Conlon, talk at ESQG (Frankfurt, 2016) J. Redondo, private communication Fine-tuning and the strong CP problem and seems like a big fine-tuning: strong CP problem • Moreover, no symmetry of the SM is restored as Other similar apparent fine-tunings: cosmological constant, hierarchy problem However, has no anthropic solution: call for a dynamical mechanism PQ mechanism: a new (anomalous) spontaneously broken chiral symmetry U(1)PQ • QCD axion: the NG boson of the SSB, BUT: all other sources of explicit U(1)PQ breaking should be at least 10 orders of magnitude down with respect to the potential generated by the QCD anomaly • Quantum gravity effects? String theory Axions in string theory Massless fields arise in string theory under compactification of M6 as Kaluza-Klein zero modes of antisymmetric tensor fields, present in all string theories • Number of massless scalar fields is determined by the topology of the compactification (e.g., number of 2-cycles in M6 , usually more than one hundred) Axions in string theory Massless fields arise in string theory under compactification of M6 as Kaluza-Klein zero modes of antisymmetric tensor fields, present in all string theories • Number of massless scalar fields is determined by the topology of the compactification (e.g., number of 2-cycles in M6 , usually more than one hundred) • Anomaly-cancellation conditions result in axion-like couplings for these fields String compactifications have plenty of candidates for axion-like particles But… do they really predict the QCD axion? Difficulties: 1.
    [Show full text]
  • 25. Neutrinos in Cosmology
    1 25. Neutrinos in Cosmology 25. Neutrinos in Cosmology Revised August 2019 by J. Lesgourgues (TTK, RWTH) and L. Verde (ICC, U. of Barcelona; ICREA, Barcelona). 25.1 Standard neutrino cosmology Neutrino properties leave detectable imprints on cosmological observations that can then be used to constrain neutrino properties. This is a great example of the remarkable interconnection and interplay between nuclear physics, particle physics, astrophysics and cosmology (for general reviews see e.g., [1–4]). Present cosmological data are already providing constraints on neutrino properties not only complementary but also competitive with terrestrial experiments; for instance, upper bounds on the total neutrino mass have shrinked by a factor of about 14 in the past 17 years. Forthcoming cosmological data may soon provide key information, not obtainable in other ways like e.g., a measurement of the absolute neutrino mass scale. This new section is motivated by this exciting prospect. A relic neutrino background pervading the Universe (the Cosmic Neutrino background, CνB) is a generic prediction of the standard hot Big Bang model (see Big Bang Nucleosynthesis – Chap. 23 of this Review). While it has not yet been detected directly, it has been indirectly confirmed by the accurate agreement of predictions and observations of: a) the primordial abundance of light elements (see Big Bang Nucleosynthesis – Chap. 23) of this Review; b) the power spectrum of Cosmic Microwave Background (CMB) anisotropies (see Cosmic Microwave Background – Chap. 28 of this Review); and c) the large scale clustering of cosmological structures. Within the hot Big Bang model such good agreement would fail dramatically without a CνB with properties matching closely those predicted by the standard neutrino decoupling process (i.e., involving only weak interactions).
    [Show full text]