Asymptotic safety of quantum gravity beyond Ricci scalars

Science.gov (United States)

Falls, Kevin; King, Callum R.; Litim, Daniel F.; Nikolakopoulos, Kostas; Rahmede, Christoph

2018-04-01

We investigate the asymptotic safety conjecture for quantum gravity including curvature invariants beyond Ricci scalars. Our strategy is put to work for families of gravitational actions which depend on functions of the Ricci scalar, the Ricci tensor, and products thereof. Combining functional renormalization with high order polynomial approximations and full numerical integration we derive the renormalization group flow for all couplings and analyse their fixed points, scaling exponents, and the fixed point effective action as a function of the background Ricci curvature. The theory is characterized by three relevant couplings. Higher-dimensional couplings show near-Gaussian scaling with increasing canonical mass dimension. We find that Ricci tensor invariants stabilize the UV fixed point and lead to a rapid convergence of polynomial approximations. We apply our results to models for cosmology and establish that the gravitational fixed point admits inflationary solutions. We also compare findings with those from f (R ) -type theories in the same approximation and pin-point the key new effects due to Ricci tensor interactions. Implications for the asymptotic safety conjecture of gravity are indicated.

Statefinder hierarchy exploration of the extended Ricci dark energy

Energy Technology Data Exchange (ETDEWEB)

Yu, Fei [Shenyang Aerospace University, College of Sciences, Shenyang (China); Cui, Jing-Lei; Zhang, Jing-Fei [Northeastern University, Department of Physics, College of Sciences, Shenyang (China); Zhang, Xin [Northeastern University, Department of Physics, College of Sciences, Shenyang (China); Peking University, Center for High Energy Physics, Beijing (China)

2015-06-15

We apply the statefinder hierarchy plus the fractional growth parameter to explore the extended Ricci dark energy (ERDE) model, in which there are two independent coefficients α and β. By adjusting them, we plot evolution trajectories of some typical parameters, including the Hubble expansion rate E, deceleration parameter q, the third and fourth-order hierarchy S{sub 3}{sup (1)} and S{sub 4}{sup (1)}, and the fractional growth parameter ε, respectively, as well as several combinations of them. For the case of variable α and constant β, in the low-redshift region the evolution trajectories of E are in high degeneracy and that of q separate somewhat. However, the ΛCDM model is confounded with ERDE in both of these cases. S{sub 3}{sup (1)} and S{sub 4}{sup (1)}, especially the former, perform much better. They can differentiate well only varieties of cases within ERDE except ΛCDM in the low-redshift region. For the high-redshift region, combinations {S_n"("1"), ε} can break the degeneracy. Both of {S_3"("1"), ε} and {S_4"("1"), ε} have the ability to discriminate ERDE with α = 1 from ΛCDM, of which the degeneracy cannot be broken by all the before-mentioned parameters. For the case of variable β and constant α, S{sub 3}{sup (1)}(z) and S{sub 4}{sup (1)}(z) can only discriminate ERDE from ΛCDM. Nothing but pairs {S_3"("1"), ε} and {S_4"("1"), ε} can discriminate not only within ERDE but also ERDE from ΛCDM. Finally, we find that S{sub 3}{sup (1)} is surprisingly a better choice to discriminate within ERDE itself, and ERDE from ΛCDM as well, rather than S{sub 4}{sup (1)}. (orig.)

Quantum wormhole as a Ricci flow

OpenAIRE

Dzhunushaliev, Vladimir

2008-01-01

The idea is considered that a quantum wormhole in a spacetime foam can be described as a Ricci flow. In this interpretation the Ricci flow is a statistical system and every metric in the Ricci flow is a microscopical state. The probability density of the microscopical state is connected with a Perelman's functional of a rescaled Ricci flow.

Introducing quantum Ricci curvature

Science.gov (United States)

Klitgaard, N.; Loll, R.

2018-02-01

Motivated by the search for geometric observables in nonperturbative quantum gravity, we define a notion of coarse-grained Ricci curvature. It is based on a particular way of extracting the local Ricci curvature of a smooth Riemannian manifold by comparing the distance between pairs of spheres with that of their centers. The quantum Ricci curvature is designed for use on non-smooth and discrete metric spaces, and to satisfy the key criteria of scalability and computability. We test the prescription on a variety of regular and random piecewise flat spaces, mostly in two dimensions. This enables us to quantify its behavior for short lattices distances and compare its large-scale behavior with that of constantly curved model spaces. On the triangulated spaces considered, the quantum Ricci curvature has good averaging properties and reproduces classical characteristics on scales large compared to the discretization scale.

Implementing quantum Ricci curvature

Science.gov (United States)

Klitgaard, N.; Loll, R.

2018-05-01

Quantum Ricci curvature has been introduced recently as a new, geometric observable characterizing the curvature properties of metric spaces, without the need for a smooth structure. Besides coordinate invariance, its key features are scalability, computability, and robustness. We demonstrate that these properties continue to hold in the context of nonperturbative quantum gravity, by evaluating the quantum Ricci curvature numerically in two-dimensional Euclidean quantum gravity, defined in terms of dynamical triangulations. Despite the well-known, highly nonclassical properties of the underlying quantum geometry, its Ricci curvature can be matched well to that of a five-dimensional round sphere.

Israel-Stewart Approach to Viscous Dissipative Extended Holographic Ricci Dark Energy Dominated Universe

Directory of Open Access Journals (Sweden)

Surajit Chattopadhyay

2016-01-01

Full Text Available This paper reports a study on the truncated Israel-Stewart formalism for bulk viscosity using the extended holographic Ricci dark energy (EHRDE. Under the consideration that the universe is dominated by EHRDE, the evolution equation for the bulk viscous pressure Π in the framework of the truncated Israel-Stewart theory has been taken as τΠ˙+Π=-3ξH, where τ is the relaxation time and ξ is the bulk viscosity coefficient. Considering effective pressure as a sum of thermodynamic pressure of EHRDE and bulk viscous pressure, it has been observed that under the influence of bulk viscosity the EoS parameter wDE is behaving like phantom, that is, wDE≤-1. It has been observed that the magnitude of the effective pressure peff=p+Π is decaying with time. We also investigated the case for a specific choice of scale factor; namely, a(t=(t-t0β/(1-α. For this choice we have observed that a transition from quintessence to phantom is possible for the equation of state parameter. However, the ΛCDM phase is not attainable by the state-finder trajectories for this choice. Finally it has been observed that in both of the cases the generalized second law of thermodynamics is valid for the viscous EHRDE dominated universe enveloped by the apparent horizon.

Interacting dark sector with transversal interaction

Energy Technology Data Exchange (ETDEWEB)

Chimento, Luis P.; Richarte, Martín G. [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA, CONICET, Ciudad Universitaria, Pabellón I, Buenos Aires 1428 (Argentina)

2015-03-26

We investigate the interacting dark sector composed of dark matter, dark energy, and dark radiation for a spatially flat Friedmann-Robertson-Walker (FRW) background by introducing a three-dimensional internal space spanned by the interaction vector Q and solve the source equation for a linear transversal interaction. Then, we explore a realistic model with dark matter coupled to a scalar field plus a decoupled radiation term, analyze the amount of dark energy in the radiation era and find that our model is consistent with the recent measurements of cosmic microwave background anisotropy coming from Planck along with the future constraints achievable by CMBPol experiment.

Interacting agegraphic dark energy

International Nuclear Information System (INIS)

Wei, Hao; Cai, Rong-Gen

2009-01-01

A new dark energy model, named ''agegraphic dark energy'', has been proposed recently, based on the so-called Karolyhazy uncertainty relation, which arises from quantum mechanics together with general relativity. In this note, we extend the original agegraphic dark energy model by including the interaction between agegraphic dark energy and pressureless (dark) matter. In the interacting agegraphic dark energy model, there are many interesting features different from the original agegraphic dark energy model and holographic dark energy model. The similarity and difference between agegraphic dark energy and holographic dark energy are also discussed. (orig.)

Dark Matter Decays from Nonminimal Coupling to Gravity.

Science.gov (United States)

Catà, Oscar; Ibarra, Alejandro; Ingenhütt, Sebastian

2016-07-08

We consider the standard model extended with a dark matter particle in curved spacetime, motivated by the fact that the only current evidence for dark matter is through its gravitational interactions, and we investigate the impact on the dark matter stability of terms in the Lagrangian linear in the dark matter field and proportional to the Ricci scalar. We show that this "gravity portal" induces decay even if the dark matter particle only has gravitational interactions, and that the decay branching ratios into standard model particles only depend on one free parameter: the dark matter mass. We study in detail the case of a singlet scalar as a dark matter candidate, which is assumed to be absolutely stable in flat spacetime due to a discrete Z_{2} symmetry, but which may decay in curved spacetimes due to a Z_{2}-breaking nonminimal coupling to gravity. We calculate the dark matter decay widths and we set conservative limits on the nonminimal coupling parameter from experiments. The limits are very stringent and suggest that there must exist an additional mechanism protecting the singlet scalar from decaying via this gravity portal.

Differential Harnack Inequalities Under a Coupled Ricci Flow

International Nuclear Information System (INIS)

Wang Linfeng

2012-01-01

In this paper, we prove several differential Harnack inequalities under a coupled Ricci flow. As applications, we get Harnack inequalities for positive solutions of backward heat-type equations with potentials under the coupled Ricci flow. We also derive Perelman’s differential Harnack inequality for fundamental solution of the conjugate heat equation under the Ricci flow.

Antonio Ricci en Madrid: 1586-1635

Directory of Open Access Journals (Sweden)

García López, David

2010-03-01

Full Text Available Life of painter Antonio Ricci is studied by new documents from his arrived at Escorial with Federico Zuccari in 1586. Ricci worked in the Palace of Madrid and was involved in the birth of the Academy of Painting. Here are studied his work as Painter and Appraiser, or his portrait of Philip IV of Spain and his relationship with Jeronimo Gratti, Caballero de Gracia.

Nuevas aportaciones documentales aclaran la vida del pintor Antonio Ricci en la Corte española desde su llegada a El Escorial junto a Federico Zuccari en 1586. Ricci trabajó como pintor en el entorno palaciego y estuvo involucrado desde el principio en el intento de creación de la Academia madrileña de pintores. Se detallan aquí su trabajo como tasador, su retrato del futuro Felipe IV o su cercana relación con un personaje tan singular como Jeronimo Gratti, el Caballero de Gracia.

Interacting dark matter disguised as warm dark matter

International Nuclear Information System (INIS)

Boehm, Celine; Riazuelo, Alain; Hansen, Steen H.; Schaeffer, Richard

2002-01-01

We explore some of the consequences of dark-matter-photon interactions on structure formation, focusing on the evolution of cosmological perturbations and performing both an analytical and a numerical study. We compute the cosmic microwave background anisotropies and matter power spectrum in this class of models. We find, as the main result, that when dark matter and photons are coupled, dark matter perturbations can experience a new damping regime in addition to the usual collisional Silk damping effect. Such dark matter particles (having quite large photon interactions) behave like cold dark matter or warm dark matter as far as the cosmic microwave background anisotropies or matter power spectrum are concerned, respectively. These dark-matter-photon interactions leave specific imprints at sufficiently small scales on both of these two spectra, which may allow us to put new constraints on the acceptable photon-dark-matter interactions. Under the conservative assumption that the abundance of 10 12 M · galaxies is correctly given by the cold dark matter, and without any knowledge of the abundance of smaller objects, we obtain the limit on the ratio of the dark-matter-photon cross section to the dark matter mass σ γ-DM /m DM -6 σ Th /(100 GeV)≅6x10 -33 cm 2 GeV -1

Ricci flow and geometrization of 3-manifolds

CERN Document Server

Morgan, John W

2010-01-01

This book is based on lectures given at Stanford University in 2009. The purpose of the lectures and of the book is to give an introductory overview of how to use Ricci flow and Ricci flow with surgery to establish the Poincar� Conjecture and the more general Geometrization Conjecture for 3-dimensional manifolds. Most of the material is geometric and analytic in nature; a crucial ingredient is understanding singularity development for 3-dimensional Ricci flows and for 3-dimensional Ricci flows with surgery. This understanding is crucial for extending Ricci flows with surgery so that they are defined for all positive time. Once this result is in place, one must study the nature of the time-slices as the time goes to infinity in order to deduce the topological consequences. The goal of the authors is to present the major geometric and analytic results and themes of the subject without weighing down the presentation with too many details. This book can be read as an introduction to more complete treatments of ...

Ricci solitons, Ricci flow and strongly coupled CFT in the Schwarzschild Unruh or Boulware vacua

International Nuclear Information System (INIS)

Figueras, Pau; Lucietti, James; Wiseman, Toby

2011-01-01

The elliptic Einstein-DeTurck equation may be used to numerically find Einstein metrics on Riemannian manifolds. Static Lorentzian Einstein metrics are considered by analytically continuing to Euclidean time. The Ricci-DeTurck flow is a constructive algorithm to solve this equation, and is simple to implement when the solution is a stable fixed point, the only complication being that Ricci solitons may exist which are not Einstein. Here we extend previous work to consider the Einstein-DeTurck equation for Riemannian manifolds with boundaries, and those that continue to static Lorentzian spacetimes which are asymptotically flat, Kaluza-Klein, locally AdS or have extremal horizons. Using a maximum principle, we prove that Ricci solitons do not exist in these cases and so any solution is Einstein. We also argue that the Ricci-DeTurck flow preserves these classes of manifolds. As an example, we simulate the Ricci-DeTurck flow for a manifold with asymptotics relevant for AdS 5 /CFT 4 . Our maximum principle dictates that there are no soliton solutions, and we give strong numerical evidence that there exists a stable fixed point of the flow which continues to a smooth static Lorentzian Einstein metric. Our asymptotics are such that this describes the classical gravity dual relevant for the CFT on a Schwarzschild background in either the Unruh or Boulware vacua. It determines the leading O(N 2 c ) part of the CFT stress tensor, which interestingly is regular on both the future and past Schwarzschild horizons. (paper)

Interacting Agegraphic Dark Energy

OpenAIRE

Wei, Hao; Cai, Rong-Gen

2007-01-01

A new dark energy model, named "agegraphic dark energy", has been proposed recently, based on the so-called K\\'{a}rolyh\\'{a}zy uncertainty relation, which arises from quantum mechanics together with general relativity. In this note, we extend the original agegraphic dark energy model by including the interaction between agegraphic dark energy and pressureless (dark) matter. In the interacting agegraphic dark energy model, there are many interesting features different from the original agegrap...

Dark Mass Creation During EWPT Via Dark Energy Interaction

OpenAIRE

Kisslinger, Leonard S.; Casper, Steven

2013-01-01

We add Dark Matter Dark Energy terms with a quintessence field interacting with a Dark Matter field to a MSSM EW Lagrangian previously used to calculate the magnetic field created during the EWPT. From the expectation value of the quintessence field we estimate the Dark Matter mass for parameters used in previous work on Dark Matter-Dark Energy interactions.

The interaction between dark energy and dark matter

International Nuclear Information System (INIS)

He Jianhua; Wang Bin

2010-01-01

In this review we first present a general formalism to study the growth of dark matter perturbations in the presence of interactions between dark matter(DM) and dark energy(DE). We also study the signature of such interaction on the temperature anisotropies of the large scale cosmic microwave background (CMB). We find that the effect of such interaction has significant signature on both the growth of dark matter structure and the late Integrated Sachs Wolfe effect(ISW). We further discuss the potential possibility to detect the coupling by cross-correlating CMB maps with tracers of the large scale structure. We finally confront this interacting model with WMAP 5-year data as well as other data sets. We find that in the 1σ range, the constrained coupling between dark sectors can solve the coincidence problem.

An introduction to the Kähler-Ricci flow

CERN Document Server

Eyssidieux, Philippe; Guedj, Vincent

2013-01-01

This volume collects lecture notes from courses offered at several conferences and workshops, and provides the first exposition in book form of the basic theory of the Kähler-Ricci flow and its current state-of-the-art. While several excellent books on Kähler-Einstein geometry are available, there have been no such works on the Kähler-Ricci flow. The book will serve as a valuable resource for graduate students and researchers in complex differential geometry, complex algebraic geometry and Riemannian geometry, and will hopefully foster further developments in this fascinating area of research.   The Ricci flow was first introduced by R. Hamilton in the early 1980s, and is central in G. Perelman’s celebrated proof of the Poincaré conjecture. When specialized for Kähler manifolds, it becomes the Kähler-Ricci flow, and reduces to a scalar PDE (parabolic complex Monge-Ampère equation). As a spin-off of his breakthrough, G. Perelman proved the convergence of the Kähler-Ricci flow on Kähler-Einstein man...

Interacting warm dark matter

International Nuclear Information System (INIS)

Cruz, Norman; Palma, Guillermo; Zambrano, David; Avelino, Arturo

2013-01-01

We explore a cosmological model composed by a dark matter fluid interacting with a dark energy fluid. The interaction term has the non-linear λρ m α ρ e β form, where ρ m and ρ e are the energy densities of the dark matter and dark energy, respectively. The parameters α and β are in principle not constrained to take any particular values, and were estimated from observations. We perform an analytical study of the evolution equations, finding the fixed points and their stability properties in order to characterize suitable physical regions in the phase space of the dark matter and dark energy densities. The constants (λ,α,β) as well as w m and w e of the EoS of dark matter and dark energy respectively, were estimated using the cosmological observations of the type Ia supernovae and the Hubble expansion rate H(z) data sets. We find that the best estimated values for the free parameters of the model correspond to a warm dark matter interacting with a phantom dark energy component, with a well goodness-of-fit to data. However, using the Bayesian Information Criterion (BIC) we find that this model is overcame by a warm dark matter – phantom dark energy model without interaction, as well as by the ΛCDM model. We find also a large dispersion on the best estimated values of the (λ,α,β) parameters, so even if we are not able to set strong constraints on their values, given the goodness-of-fit to data of the model, we find that a large variety of theirs values are well compatible with the observational data used

The classification of the Ricci tensor in the general theory of relativity

International Nuclear Information System (INIS)

Cormack, W.J.

1979-10-01

A comprehensive classification of the Ricci tensor in General Relativity using several techniques is given and their connection with existing classification studied under the headings; canonical forms for the Ricci tensor, invariant 2-spaces in the classification of the Ricci tensor, Riemannian curvature and the classification of the Riemann and Ricci tensors, and spinor classifications of the Ricci tensor. (U.K.)

Ricci inheritance symmetry in general relativity

International Nuclear Information System (INIS)

Bokhari, A.H.; Al-Dweik, A.; Zaman, F.D.; Karim, M.; Kubel, D.

2010-01-01

In an earlier paper (see Nuovo Cimento B, 19 (2004) 1187) it was conjectured that none of the well-known spherically symmetric static space-time solutions of the Einstein equations admit non-trivial Ricci inheritance symmetry. In this paper we discuss Ricci inheritance (R I) symmetry in three well-known non static spherically symmetric space-time metrics and show that our conjecture is also valid in non-static space-time metrics.

Effective dark energy equation of state in interacting dark energy models

International Nuclear Information System (INIS)

Avelino, P.P.; Silva, H.M.R. da

2012-01-01

In models where dark matter and dark energy interact non-minimally, the total amount of matter in a fixed comoving volume may vary from the time of recombination to the present time due to energy transfer between the two components. This implies that, in interacting dark energy models, the fractional matter density estimated using the cosmic microwave background assuming no interaction between dark matter and dark energy will in general be shifted with respect to its true value. This may result in an incorrect determination of the equation of state of dark energy if the interaction between dark matter and dark energy is not properly accounted for, even if the evolution of the Hubble parameter as a function of redshift is known with arbitrary precision. In this Letter we find an exact expression, as well as a simple analytical approximation, for the evolution of the effective equation of state of dark energy, assuming that the energy transfer rate between dark matter and dark energy is described by a simple two-parameter model. We also provide analytical examples where non-phantom interacting dark energy models mimic the background evolution and primary cosmic microwave background anisotropies of phantom dark energy models.

Effective dark energy equation of state in interacting dark energy models

Energy Technology Data Exchange (ETDEWEB)

Avelino, P.P., E-mail: ppavelin@fc.up.pt [Centro de Astrofisica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Departamento de Fisica e Astronomia da Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Silva, H.M.R. da, E-mail: hilberto.silva@gmail.com [Departamento de Fisica e Astronomia da Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal)

2012-07-24

In models where dark matter and dark energy interact non-minimally, the total amount of matter in a fixed comoving volume may vary from the time of recombination to the present time due to energy transfer between the two components. This implies that, in interacting dark energy models, the fractional matter density estimated using the cosmic microwave background assuming no interaction between dark matter and dark energy will in general be shifted with respect to its true value. This may result in an incorrect determination of the equation of state of dark energy if the interaction between dark matter and dark energy is not properly accounted for, even if the evolution of the Hubble parameter as a function of redshift is known with arbitrary precision. In this Letter we find an exact expression, as well as a simple analytical approximation, for the evolution of the effective equation of state of dark energy, assuming that the energy transfer rate between dark matter and dark energy is described by a simple two-parameter model. We also provide analytical examples where non-phantom interacting dark energy models mimic the background evolution and primary cosmic microwave background anisotropies of phantom dark energy models.

Spacetimes of Weyl and Ricci type N in higher dimensions

International Nuclear Information System (INIS)

Kuchynka, M; Pravdová, A

2016-01-01

We study the geometrical properties of null congruences generated by an aligned null direction of the Weyl tensor (WAND) in spacetimes of Weyl and Ricci type N (possibly with a non-vanishing cosmological constant) in an arbitrary dimension. We prove that a type N Ricci tensor and a type III or N Weyl tensor have to be aligned. In such spacetimes, the multiple WAND has to be geodetic. For spacetimes with type N aligned Weyl and Ricci tensors, the canonical form of the optical matrix in the twisting and non-twisting cases is derived and the dependence of the Weyl and the Ricci tensors and Ricci rotation coefficients on the affine parameter of the geodetic null congruence generated by the WAND is obtained. (paper)

Interactions between dark energy and dark matter

Energy Technology Data Exchange (ETDEWEB)

Baldi, Marco

2009-03-20

We have investigated interacting dark energy cosmologies both concerning their impact on the background evolution of the Universe and their effects on cosmological structure growth. For the former aspect, we have developed a cosmological model featuring a matter species consisting of particles with a mass that increases with time. In such model the appearance of a Growing Matter component, which is negligible in early cosmology, dramatically slows down the evolution of the dark energy scalar field at a redshift around six, and triggers the onset of the accelerated expansion of the Universe, therefore addressing the Coincidence Problem. We propose to identify this Growing Matter component with cosmic neutrinos, in which case the present dark energy density can be related to the measured average mass of neutrinos. For the latter aspect, we have implemented the new physical features of interacting dark energy models into the cosmological N-body code GADGET-2, and we present the results of a series of high-resolution simulations for a simple realization of dark energy interaction. As a consequence of the new physics, cold dark matter and baryon distributions evolve differently both in the linear and in the non-linear regime of structure formation. Already on large scales, a linear bias develops between these two components, which is further enhanced by the non-linear evolution. We also find, in contrast with previous work, that the density profiles of cold dark matter halos are less concentrated in coupled dark energy cosmologies compared with {lambda}{sub CDM}. Also, the baryon fraction in halos in the coupled models is significantly reduced below the universal baryon fraction. These features alleviate tensions between observations and the {lambda}{sub CDM} model on small scales. Our methodology is ideally suited to explore the predictions of coupled dark energy models in the fully non-linear regime, which can provide powerful constraints for the viable parameter

Interactions between dark energy and dark matter

International Nuclear Information System (INIS)

Baldi, Marco

2009-01-01

We have investigated interacting dark energy cosmologies both concerning their impact on the background evolution of the Universe and their effects on cosmological structure growth. For the former aspect, we have developed a cosmological model featuring a matter species consisting of particles with a mass that increases with time. In such model the appearance of a Growing Matter component, which is negligible in early cosmology, dramatically slows down the evolution of the dark energy scalar field at a redshift around six, and triggers the onset of the accelerated expansion of the Universe, therefore addressing the Coincidence Problem. We propose to identify this Growing Matter component with cosmic neutrinos, in which case the present dark energy density can be related to the measured average mass of neutrinos. For the latter aspect, we have implemented the new physical features of interacting dark energy models into the cosmological N-body code GADGET-2, and we present the results of a series of high-resolution simulations for a simple realization of dark energy interaction. As a consequence of the new physics, cold dark matter and baryon distributions evolve differently both in the linear and in the non-linear regime of structure formation. Already on large scales, a linear bias develops between these two components, which is further enhanced by the non-linear evolution. We also find, in contrast with previous work, that the density profiles of cold dark matter halos are less concentrated in coupled dark energy cosmologies compared with Λ CDM . Also, the baryon fraction in halos in the coupled models is significantly reduced below the universal baryon fraction. These features alleviate tensions between observations and the Λ CDM model on small scales. Our methodology is ideally suited to explore the predictions of coupled dark energy models in the fully non-linear regime, which can provide powerful constraints for the viable parameter space of such scenarios

Self-interacting warm dark matter

International Nuclear Information System (INIS)

Hannestad, Steen; Scherrer, Robert J.

2000-01-01

It has been shown by many independent studies that the cold dark matter scenario produces singular galactic dark halos, in strong contrast with observations. Possible remedies are that either the dark matter is warm so that it has significant thermal motion or that the dark matter has strong self-interactions. We combine these ideas to calculate the linear mass power spectrum and the spectrum of cosmic microwave background (CMB) fluctuations for self-interacting warm dark matter. Our results indicate that such models have more power on small scales than is the case for the standard warm dark matter model, with a CMB fluctuation spectrum which is nearly indistinguishable from standard cold dark matter. This enhanced small-scale power may provide better agreement with the observations than does standard warm dark matter. (c) 2000 The American Physical Society

Self-interacting dark matter constraints in a thick dark disk scenario

Science.gov (United States)

Vattis, Kyriakos; Koushiappas, Savvas M.

2018-05-01

A thick dark matter disk is predicted in cold dark matter simulations as the outcome of the interaction between accreted satellites and the stellar disk in Milky Way-sized halos. We study the effects of a self-interacting thick dark disk on the energetic neutrino flux from the Sun. We find that for particle masses between 100 GeV and 1 TeV and dark matter annihilation to τ+τ-, either the self-interaction may not be strong enough to solve the small-scale structure motivation or a dark disk cannot be present in the Milky Way.

Large-scale instability in interacting dark energy and dark matter fluids

International Nuclear Information System (INIS)

Väliviita, Jussi; Majerotto, Elisabetta; Maartens, Roy

2008-01-01

If dark energy interacts with dark matter, this gives a new approach to the coincidence problem. But interacting dark energy models can suffer from pathologies. We consider the case where the dark energy is modelled as a fluid with constant equation of state parameter w. Non-interacting constant-w models are well behaved in the background and in the perturbed universe. But the combination of constant w and a simple interaction with dark matter leads to an instability in the dark sector perturbations at early times: the curvature perturbation blows up on super-Hubble scales. Our results underline how important it is to carefully analyse the relativistic perturbations when considering models of coupled dark energy. The instability that we find has been missed in some previous work where the perturbations were not consistently treated. The unstable mode dominates even if adiabatic initial conditions are used. The instability also arises regardless of how weak the coupling is. This non-adiabatic instability is different from previously discovered adiabatic instabilities on small scales in the strong-coupling regime

Quantum Field Theory of Interacting Dark Matter/Dark Energy: Dark Monodromies

CERN Document Server

D'Amico, Guido; Kaloper, Nemanja

2016-11-28

We discuss how to formulate a quantum field theory of dark energy interacting with dark matter. We show that the proposals based on the assumption that dark matter is made up of heavy particles with masses which are very sensitive to the value of dark energy are strongly constrained. Quintessence-generated long range forces and radiative stability of the quintessence potential require that such dark matter and dark energy are completely decoupled. However, if dark energy and a fraction of dark matter are very light axions, they can have significant mixings which are radiatively stable and perfectly consistent with quantum field theory. Such models can naturally occur in multi-axion realizations of monodromies. The mixings yield interesting signatures which are observable and are within current cosmological limits but could be constrained further by future observations.

Signature of the interaction between dark energy and dark matter in observations

International Nuclear Information System (INIS)

Abdalla, Elcio; Abramo, L. Raul; Souza, Jose C. C. de

2010-01-01

We investigate the effect of an interaction between dark energy and dark matter upon the dynamics of galaxy clusters. This effect is computed through the Layser-Irvine equation, which describes how an astrophysical system reaches virial equilibrium and was modified to include the dark interactions. Using observational data from almost 100 purportedly relaxed galaxy clusters we put constraints on the strength of the couplings in the dark sector. We compare our results with those from other observations and find that a positive (in the sense of energy flow from dark energy to dark matter) nonvanishing interaction is consistent with the data within several standard deviations.

Interacting dark sector and precision cosmology

Science.gov (United States)

Buen-Abad, Manuel A.; Schmaltz, Martin; Lesgourgues, Julien; Brinckmann, Thejs

2018-01-01

We consider a recently proposed model in which dark matter interacts with a thermal background of dark radiation. Dark radiation consists of relativistic degrees of freedom which allow larger values of the expansion rate of the universe today to be consistent with CMB data (H0-problem). Scattering between dark matter and radiation suppresses the matter power spectrum at small scales and can explain the apparent discrepancies between ΛCDM predictions of the matter power spectrum and direct measurements of Large Scale Structure LSS (σ8-problem). We go beyond previous work in two ways: 1. we enlarge the parameter space of our previous model and allow for an arbitrary fraction of the dark matter to be interacting and 2. we update the data sets used in our fits, most importantly we include LSS data with full k-dependence to explore the sensitivity of current data to the shape of the matter power spectrum. We find that LSS data prefer models with overall suppressed matter clustering due to dark matter - dark radiation interactions over ΛCDM at 3–4 σ. However recent weak lensing measurements of the power spectrum are not yet precise enough to clearly distinguish two limits of the model with different predicted shapes for the linear matter power spectrum. In two appendices we give a derivation of the coupled dark matter and dark radiation perturbation equations from the Boltzmann equation in order to clarify a confusion in the recent literature, and we derive analytic approximations to the solutions of the perturbation equations in the two physically interesting limits of all dark matter weakly interacting or a small fraction of dark matter strongly interacting.

New interactions in the dark sector mediated by dark energy

International Nuclear Information System (INIS)

Brookfield, Anthony W.; Bruck, Carsten van de; Hall, Lisa M. H.

2008-01-01

Cosmological observations have revealed the existence of a dark matter sector, which is commonly assumed to be made up of one particle species only. However, this sector might be more complicated than we currently believe: there might be more than one dark matter species (for example, two components of cold dark matter or a mixture of hot and cold dark matter) and there may be new interactions between these particles. In this paper we study the possibility of multiple dark matter species and interactions mediated by a dark energy field. We study both the background and the perturbation evolution in these scenarios. We find that the background evolution of a system of multiple dark matter particles (with constant couplings) mimics a single fluid with a time-varying coupling parameter. However, this is no longer true on the perturbative level. We study the case of attractive and repulsive forces as well as a mixture of cold and hot dark matter particles

CIME course on Ricci Flow and Geometric Applications

CERN Document Server

Mantegazza, Carlo

2016-01-01

Presenting some impressive recent achievements in differential geometry and topology, this volume focuses on results obtained using techniques based on Ricci flow. These ideas are at the core of the study of differentiable manifolds. Several very important open problems and conjectures come from this area and the techniques described herein are used to face and solve some of them. The book's four chapters are based on lectures given by leading researchers in the field of geometric analysis and low-dimensional geometry/topology, respectively offering an introduction to: the differentiable sphere theorem (G. Besson), the geometrization of 3-manifolds (M. Boileau), the singularities of 3-dimensional Ricci flows (C. Sinestrari), and Kahler-Ricci flow (G. Tian). The lectures will be particularly valuable to young researchers interested in differential manifolds.

Is Self-Interacting Dark Matter Undergoing Dark Fusion?

OpenAIRE

McDermott, Samuel D.

2018-01-01

We suggest that two-to-two dark matter fusion may be the relaxation process that resolves the small-scale structure problems of the cold collisionless dark matter paradigm. In order for the fusion cross section to scale correctly across many decades of astrophysical masses from dwarf galaxies to galaxy clusters, we require the fractional binding energy released to be greater than vn∼(10−(2−3))n, where n=1, 2 depends on local dark sector chemistry. The size of the dark-sector interaction cross...

Interaction in the dark sector

Science.gov (United States)

del Campo, Sergio; Herrera, Ramón; Pavón, Diego

2015-06-01

It may well happen that the two main components of the dark sector of the Universe, dark matter and dark energy, do not evolve separately but interact nongravitationally with one another. However, given our current lack of knowledge of the microscopic nature of these two components, there is no clear theoretical path to determine their interaction. Yet, over the years, phenomenological interaction terms have been proposed on mathematical simplicity and heuristic arguments. In this paper, based on the likely evolution of the ratio between the energy densities of these dark components, we lay down reasonable criteria to obtain phenomenological, useful, expressions of the said term independent of any gravity theory. We illustrate this with different proposals which seem compatible with the known evolution of the Universe at the background level. Likewise, we show that two possible degeneracies with noninteracting models are only apparent as they can be readily broken at the background level. Further, we analyze some interaction terms that appear in the literature.

Dark degeneracy and interacting cosmic components

International Nuclear Information System (INIS)

Aviles, Alejandro; Cervantes-Cota, Jorge L.

2011-01-01

We study some properties of the dark degeneracy, which is the fact that what we measure in gravitational experiments is the energy-momentum tensor of the total dark sector, and any split into components (as in dark matter and dark energy) is arbitrary. In fact, just one dark fluid is necessary to obtain exactly the same cosmological and astrophysical phenomenology as the ΛCDM model. We work explicitly the first-order perturbation theory and show that beyond the linear order the dark degeneracy is preserved under some general assumptions. Then we construct the dark fluid from a collection of interacting fluids. Finally, we try to break the degeneracy with a general class of couplings to baryonic matter. Nonetheless, we show that these interactions can also be understood in the context of the ΛCDM model as between dark matter and baryons. For this last investigation we choose two independent parametrizations for the interactions, one inspired by electromagnetism and the other by chameleon theories. Then, we constrain them with a joint analysis of CMB and supernovae observational data.

Is Self-Interacting Dark Matter Undergoing Dark Fusion?

Energy Technology Data Exchange (ETDEWEB)

McDermott, Samuel D.

2017-11-02

We suggest that two-to-two dark matter fusion may be the relaxation process that resolves the small-scale structure problems of the cold collisionless dark matter paradigm. In order for the fusion cross section to scale correctly across many decades of astrophysical masses from dwarf galaxies to galaxy clusters, we require the fractional binding energy released to be greater than v^n ~ [10^{-(2-3)}]^n, where n=1,2 depends on local dark sector chemistry. The size of the dark-sector interaction cross sections must be sigma ~ 0.1-1 barn, moderately larger than for Standard Model deuteron fusion, indicating a dark nuclear scale Lambda ~ O(100 MeV). Dark fusion firmly predicts constant sigma v below the characteristic velocities of galaxy clusters. Observations of the inner structure of galaxy groups with velocity dispersion of several hundred kilometer per second, of which a handful have been identified, could differentiate dark fusion from a dark photon model.

RICCI and matter collineations of som-roy chaudhary symmetric space time

International Nuclear Information System (INIS)

Ramzan, M.; Ahmed, Y.; Mufti, M.

2018-01-01

This paper is devoted to explore the RICCI and MCs (Matter Collineations of the Som-Ray Chaudhary spacetime. The spacetime under consideration is one of the spatially homogeneous and rotating spacetimes. Collineations are the some kinds of the Lie symmetries. To discuss the required collineations we have used the RICCI and energy momentum tensors. As the RICCI tensor is formulated from the metric tensor, it must possess its symmetries. RCs (RICCI Collineations) leads to conservation laws. On the other hand for the distribution of matter in the spacetimes, the symmetries of energy momentum tensor or MCs provides conservation laws on matter field. Throughout this paper, these collineations are discussed by vanishing Lie derivative of RICCI and energy momentum tensors respectively. Complete solution of the RCs and MCs equations, which are formed in the result of vanishing Lie derivative are explored. Studying all these collineations in the said spacetime, it has been shown that RCs of the spacetime form an infinite dimensional vector space where as MCs are Killing vector fields. (author)

Ricci-flat branes

International Nuclear Information System (INIS)

Brecher, D.; Perry, M.J.

2000-01-01

Up to overall harmonic factors, the D8-brane solution of the massive type IIA supergravity theory is the product of nine-dimensional Minkowski space (the world-volume) with the real line (the transverse space). We show that the equations of motion allow for the world-volume metric to be generalised to an arbitrary Ricci-flat one. If this nine-dimensional Ricci-flat manifold admits Killing spinors, then the resulting solutions are supersymmetric and satisfy the usual Bogomol'nyi bound, although they preserve fewer than the usual one half of the supersymmetries. We describe the possible choices of such manifolds, elaborating on the connection between the existence of Killing spinors and the self-duality condition on the curvature two-form. Since the D8-brane is a domain wall in ten dimensions, we are led to consider the general case: domain walls in any supergravity theory. Similar considerations hold here also. Moreover, it is shown that the world-volume of any magnetic brane - of which the domain walls are a specific example - can be generalised in precisely the same way. The general class of supersymmetric solutions have gravitational instantons as their spatial sections. Some mention is made of the world-volume solitons of such branes

Self-interacting asymmetric dark matter coupled to a light massive dark photon

International Nuclear Information System (INIS)

Petraki, Kalliopi; Pearce, Lauren; Kusenko, Alexander

2014-01-01

Dark matter (DM) with sizeable self-interactions mediated by a light species offers a compelling explanation of the observed galactic substructure; furthermore, the direct coupling between DM and a light particle contributes to the DM annihilation in the early universe. If the DM abundance is due to a dark particle-antiparticle asymmetry, the DM annihilation cross-section can be arbitrarily large, and the coupling of DM to the light species can be significant. We consider the case of asymmetric DM interacting via a light (but not necessarily massless) Abelian gauge vector boson, a dark photon. In the massless dark photon limit, gauge invariance mandates that DM be multicomponent, consisting of positive and negative dark ions of different species which partially bind in neutral dark atoms. We argue that a similar conclusion holds for light dark photons; in particular, we establish that the multi-component and atomic character of DM persists in much of the parameter space where the dark photon is sufficiently light to mediate sizeable DM self-interactions. We discuss the cosmological sequence of events in this scenario, including the dark asymmetry generation, the freeze-out of annihilations, the dark recombination and the phase transition which gives mass to the dark photon. We estimate the effect of self-interactions in DM haloes, taking into account this cosmological history. We place constraints based on the observed ellipticity of large haloes, and identify the regimes where DM self-scattering can affect the dynamics of smaller haloes, bringing theory in better agreement with observations. Moreover, we estimate the cosmological abundance of dark photons in various regimes, and derive pertinent bounds

Dark patterns in proxemic interactions

DEFF Research Database (Denmark)

Greenberg, Saul; Boring, Sebastian; Vermeulen, Jo

2014-01-01

to better facilitate seamless and natural interactions. To do so, both people and devices are tracked to determine their spatial relationships. While interest in proxemic interactions has increased over the last few years, it also has a dark side: knowledge of proxemics may (and likely will) be easily...... exploited to the detriment of the user. In this paper, we offer a critical perspective on proxemic interactions in the form of dark patterns: ways proxemic interactions can be misused. We discuss a series of these patterns and describe how they apply to these types of interactions. In addition, we identify...

The Ricci flow part IV : long-time solutions and related topics

CERN Document Server

Chow, Bennett; Glickenstein, David; Isenberg, James

2015-01-01

Ricci flow is a powerful technique using a heat-type equation to deform Riemannian metrics on manifolds to better metrics in the search for geometric decompositions. With the fourth part of their volume on techniques and applications of the theory, the authors discuss long-time solutions of the Ricci flow and related topics. In dimension 3, Perelman completed Hamilton's program to prove Thurston's geometrization conjecture. In higher dimensions the Ricci flow has remarkable properties, which indicates its usefulness to understand relations between the geometry and topology of manifolds. This b

Colliding clusters and dark matter self-interactions

DEFF Research Database (Denmark)

Kahlhoefer, Felix; Schmidt-Hoberg, Kai; Frandsen, Mads Toudal

2014-01-01

When a dark matter halo moves through a background of dark matter particles, self-interactions can lead to both deceleration and evaporation of the halo and thus shift its centroid relative to the collisionless stars and galaxies. We study the magnitude and time evolution of this shift for two...... classes of dark matter self-interactions, viz. frequent self-interactions with low momentum transfer (e.g. due to long-range interactions) and rare self-interactions with high momentum transfer (e.g. contact interactions), and find important differences between the two cases. We find that neither effect...... can be strong enough to completely separate the dark matter halo from the galaxies, if we impose conservative bounds on the self-interaction cross-section. The majority of both populations remain bound to the same gravitational potential and the peaks of their distributions are therefore always...

Chromo-Rayleigh interactions of dark matter

International Nuclear Information System (INIS)

Bai, Yang; Osborne, James

2015-01-01

For a wide range of models, dark matter can interact with QCD gluons via chromo-Rayleigh interactions. We point out that the Large Hadron Collider (LHC), as a gluon machine, provides a superb probe of such interactions. In this paper, we introduce simplified models to UV-complete two effective dark matter chromo-Rayleigh interactions and identify the corresponding collider signatures, including four jets or a pair of di-jet resonances plus missing transverse energy. After performing collider studies for both the 8 TeV and 14 TeV LHC, we find that the LHC can be more sensitive to dark matter chromo-Rayleigh interactions than direct detection experiments and thus provides the best opportunity for future discovery of this class of models.

Mass-induced instability of SAdS black hole in Einstein-Ricci cubic gravity

Science.gov (United States)

Myung, Yun Soo

2018-05-01

We perform the stability analysis of Schwarzschild-AdS (SAdS) black hole in the Einstein-Ricci cubic gravity. It shows that the Ricci tensor perturbations exhibit unstable modes for small black holes. We call this the mass-induced instability of SAdS black hole because the instability of small black holes arises from the massiveness in the linearized Einstein-Ricci cubic gravity, but not a feature of higher-order derivative theory giving ghost states. Also, we point out that the correlated stability conjecture holds for the SAdS black hole by computing the Wald entropy of SAdS black hole in Einstein-Ricci cubic gravity.

The simplicial Ricci tensor

International Nuclear Information System (INIS)

Alsing, Paul M; McDonald, Jonathan R; Miller, Warner A

2011-01-01

The Ricci tensor (Ric) is fundamental to Einstein's geometric theory of gravitation. The three-dimensional Ric of a spacelike surface vanishes at the moment of time symmetry for vacuum spacetimes. The four-dimensional Ric is the Einstein tensor for such spacetimes. More recently, the Ric was used by Hamilton to define a nonlinear, diffusive Ricci flow (RF) that was fundamental to Perelman's proof of the Poincare conjecture. Analytic applications of RF can be found in many fields including general relativity and mathematics. Numerically it has been applied broadly to communication networks, medical physics, computer design and more. In this paper, we use Regge calculus (RC) to provide the first geometric discretization of the Ric. This result is fundamental for higher dimensional generalizations of discrete RF. We construct this tensor on both the simplicial lattice and its dual and prove their equivalence. We show that the Ric is an edge-based weighted average of deficit divided by an edge-based weighted average of dual area-an expression similar to the vertex-based weighted average of the scalar curvature reported recently. We use this Ric in a third and independent geometric derivation of the RC Einstein tensor in arbitrary dimensions.

The simplicial Ricci tensor

Science.gov (United States)

Alsing, Paul M.; McDonald, Jonathan R.; Miller, Warner A.

2011-08-01

The Ricci tensor (Ric) is fundamental to Einstein's geometric theory of gravitation. The three-dimensional Ric of a spacelike surface vanishes at the moment of time symmetry for vacuum spacetimes. The four-dimensional Ric is the Einstein tensor for such spacetimes. More recently, the Ric was used by Hamilton to define a nonlinear, diffusive Ricci flow (RF) that was fundamental to Perelman's proof of the Poincarè conjecture. Analytic applications of RF can be found in many fields including general relativity and mathematics. Numerically it has been applied broadly to communication networks, medical physics, computer design and more. In this paper, we use Regge calculus (RC) to provide the first geometric discretization of the Ric. This result is fundamental for higher dimensional generalizations of discrete RF. We construct this tensor on both the simplicial lattice and its dual and prove their equivalence. We show that the Ric is an edge-based weighted average of deficit divided by an edge-based weighted average of dual area—an expression similar to the vertex-based weighted average of the scalar curvature reported recently. We use this Ric in a third and independent geometric derivation of the RC Einstein tensor in arbitrary dimensions.

Colliding clusters and dark matter self-interactions

CERN Document Server

Kahlhoefer, Felix; Frandsen, Mads T; Sarkar, Subir

2014-01-01

When a dark matter halo moves through a background of dark matter particles, self-interactions can lead to both deceleration and evaporation of the halo and thus shift its centroid relative to the collisionless stars and galaxies. We study the magnitude and time evolution of this shift for two classes of dark matter self-interactions, viz. frequent self-interactions with small momentum transfer (e.g. due to long-range interactions) and rare self-interactions with large momentum transfer (e.g. contact interactions), and find important differences between the two cases. We find that neither effect can be strong enough to completely separate the dark matter halo from the galaxies, if we impose conservative bounds on the self-interaction cross-section. The majority of both populations remain bound to the same gravitational potential and the peaks of their distributions are therefore always coincident. Consequently any apparent separation is mainly due to particles which are leaving the gravitational potential, so...

Dark energy interacting with two fluids

Energy Technology Data Exchange (ETDEWEB)

Cruz, Norman [Departamento de Fisica, Facultad de Ciencia, Universidad de Santiago, Casilla 307, Santiago (Chile)], E-mail: ncruz@lauca.usach.cl; Lepe, Samuel [Instituto de Fisica, Facultad de Ciencias Basicas y Matematicas, Universidad Catolica de Valparaiso, Avenida Brasil 2950, Valparaiso (Chile)], E-mail: slepe@ucv.cl; Pena, Francisco [Departamento de Ciencias Fisicas, Facultad de Ingenieria, Ciencias y Administracion, Universidad de La Frontera, Avda. Francisco Salazar 01145, Casilla 54-D Temuco (Chile)], E-mail: fcampos@ufro.cl

2008-05-29

A cosmological model of dark energy interacting with dark matter and another general component of the universe is investigated. We found general constraints on these models imposing an accelerated expansion. The same is also studied in the case for holographic dark energy.

Effects of the interaction between dark energy and dark matter on cosmological parameters

International Nuclear Information System (INIS)

He, Jian-Hua; Wang, Bin

2008-01-01

We examine the effects of possible phenomenological interactions between dark energy and dark matter on cosmological parameters and their efficiency in solving the coincidence problem. We work with two simple parameterizations of the dynamical dark energy equation of state and the constant dark energy equation of state. Using observational data coming from the new 182 Gold type Ia supernova samples, the shift parameter of the Cosmic Microwave Background given by the three-year Wilkinson Microwave Anisotropy Probe observations and the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey, we perform a statistical joint analysis of different forms of phenomenological interaction between dark energy and dark matter

Self-interacting spin-2 dark matter

Science.gov (United States)

Chu, Xiaoyong; Garcia-Cely, Camilo

2017-11-01

Recent developments in bigravity allow one to construct consistent theories of interacting spin-2 particles that are free of ghosts. In this framework, we propose an elementary spin-2 dark matter candidate with a mass well below the TeV scale. We show that, in a certain regime where the interactions induced by the spin-2 fields do not lead to large departures from the predictions of general relativity, such a light dark matter particle typically self-interacts and undergoes self-annihilations via 3-to-2 processes. We discuss its production mechanisms and also identify the regions of the parameter space where self-interactions can alleviate the discrepancies at small scales between the predictions of the collisionless dark matter paradigm and cosmological N-body simulations.

Self-interacting dark matter

Science.gov (United States)

Mavromatos, Nick E.; Argüelles, Carlos R.; Ruffini, Remo; Rueda, Jorge A.

Self-interacting dark matter (SIDM) is a hypothetical form of dark matter (DM), characterized by relatively strong (compared to the weak interaction strength) self-interactions (SIs), which has been proposed to resolve a number of issues concerning tensions between simulations and observations at the galactic or smaller scales. We review here some recent developments discussed at the 14th Marcel Grossmann Meeting (MG14), paying particular attention to restrictions on the SIDM (total) cross-section from using novel observables in merging galactic structures, as well as the rôle of SIDM on the Milky Way halo and its central region. We report on some interesting particle-physics inspired SIDM models that were discussed at MG14, namely the glueball DM, and a right-handed neutrino DM (with mass of a few tens of keV, that may exist in minimal extensions of the standard model (SM)), interacting among themselves via vector bosons mediators in the dark sector. A detailed phenomenology of the latter model on galactic scales, as well as the potential role of the right handed neutrinos in alleviating some of the small-scale cosmology problems, namely the discrepancies between observations and numerical simulations within standard ΛCDM and ΛWDM cosmologies are reported.

Topological Signals of Singularities in Ricci Flow

Directory of Open Access Journals (Sweden)

Paul M. Alsing

2017-08-01

Full Text Available We implement methods from computational homology to obtain a topological signal of singularity formation in a selection of geometries evolved numerically by Ricci flow. Our approach, based on persistent homology, produces precise, quantitative measures describing the behavior of an entire collection of data across a discrete sample of times. We analyze the topological signals of geometric criticality obtained numerically from the application of persistent homology to models manifesting singularities under Ricci flow. The results we obtain for these numerical models suggest that the topological signals distinguish global singularity formation (collapse to a round point from local singularity formation (neckpinch. Finally, we discuss the interpretation and implication of these results and future applications.

Interacting hot dark matter

International Nuclear Information System (INIS)

Atrio-Barandela, F.; Davidson, S.

1997-01-01

We discuss the viability of a light particle (∼30eV neutrino) with strong self-interactions as a dark matter candidate. The interaction prevents the neutrinos from free-streaming during the radiation-dominated regime so galaxy-sized density perturbations can survive. Smaller scale perturbations are damped due to neutrino diffusion. We calculate the power spectrum in the imperfect fluid approximation, and show that it is damped at the length scale one would estimate due to neutrino diffusion. The strength of the neutrino-neutrino coupling is only weakly constrained by observations, and could be chosen by fitting the power spectrum to the observed amplitude of matter density perturbations. The main shortcoming of our model is that interacting neutrinos cannot provide the dark matter in dwarf galaxies. copyright 1997 The American Physical Society

Variable sound speed in interacting dark energy models

Science.gov (United States)

Linton, Mark S.; Pourtsidou, Alkistis; Crittenden, Robert; Maartens, Roy

2018-04-01

We consider a self-consistent and physical approach to interacting dark energy models described by a Lagrangian, and identify a new class of models with variable dark energy sound speed. We show that if the interaction between dark energy in the form of quintessence and cold dark matter is purely momentum exchange this generally leads to a dark energy sound speed that deviates from unity. Choosing a specific sub-case, we study its phenomenology by investigating the effects of the interaction on the cosmic microwave background and linear matter power spectrum. We also perform a global fitting of cosmological parameters using CMB data, and compare our findings to ΛCDM.

Searching for dark matter-dark energy interactions: Going beyond the conformal case

Science.gov (United States)

van de Bruck, Carsten; Mifsud, Jurgen

2018-01-01

We consider several cosmological models which allow for nongravitational direct couplings between dark matter and dark energy. The distinguishing cosmological features of these couplings can be probed by current cosmological observations, thus enabling us to place constraints on these specific interactions which are composed of the conformal and disformal coupling functions. We perform a global analysis in order to independently constrain the conformal, disformal, and mixed interactions between dark matter and dark energy by combining current data from: Planck observations of the cosmic microwave background radiation anisotropies, a combination of measurements of baryon acoustic oscillations, a supernova type Ia sample, a compilation of Hubble parameter measurements estimated from the cosmic chronometers approach, direct measurements of the expansion rate of the Universe today, and a compilation of growth of structure measurements. We find that in these coupled dark-energy models, the influence of the local value of the Hubble constant does not significantly alter the inferred constraints when we consider joint analyses that include all cosmological probes. Moreover, the parameter constraints are remarkably improved with the inclusion of the growth of structure data set measurements. We find no compelling evidence for an interaction within the dark sector of the Universe.

Cosmology with interaction in the dark sector

International Nuclear Information System (INIS)

Costa, F. E. M.; Barboza, E. M. Jr.; Alcaniz, J. S.

2009-01-01

Unless some unknown symmetry in nature prevents or suppresses a nonminimal coupling in the dark sector, the dark energy field may interact with the pressureless component of dark matter. In this paper, we investigate some cosmological consequences of a general model of interacting dark matter-dark energy characterized by a dimensionless parameter ε. We derive a coupled scalar field version for this general class of scenarios and carry out a joint statistical analysis involving type Ia supernovae data (Legacy and Constitution sets), measurements of baryon acoustic oscillation peaks at z=0.20 (2dFGRS) and z=0.35 (SDSS), and measurements of the Hubble evolution H(z). For the specific case of vacuum decay (w=-1), we find that, although physically forbidden, a transfer of energy from dark matter to dark energy is favored by the data.

Linear and nonlinear interactions in the dark sector

International Nuclear Information System (INIS)

Chimento, Luis P.

2010-01-01

We investigate models of interacting dark matter and dark energy for the Universe in a spatially flat Friedmann-Robertson-Walker space-time. We find the 'source equation' for the total energy density and determine the energy density of each dark component. We introduce an effective one-fluid description to evidence that interacting and unified models are related to each other, analyze the effective model, and obtain the attractor solutions. We study linear and nonlinear interactions, the former comprises a linear combination of the dark matter and dark energy densities, their first derivatives, the total energy density, its first and second derivatives, and a function of the scale factor. The latter is a possible generalization of the linear interaction consisting of an aggregate of the above linear combination and a significant nonlinear term built with a rational function of the dark matter and dark energy densities homogeneous of degree 1. We solve the evolution equations of the dark components for both interactions and examine exhaustively several examples. There exist cases where the effective one-fluid description produces different alternatives to the ΛCDM model and cases where the problem of coincidence is alleviated. In addition, we find that some nonlinear interactions yield an effective one-fluid model with a Chaplygin gas equation of state, whereas others generate cosmological models with de Sitter and power-law expansions. We show that a generic nonlinear interaction induces an effective equation of state which depends on the scale factor in the same way as the variable modified Chaplygin gas model, giving rise to the 'relaxed Chaplygin gas model'.

Interacting Dark Matter and q-Deformed Dark Energy Nonminimally Coupled to Gravity

Directory of Open Access Journals (Sweden)

Emre Dil

2016-01-01

Full Text Available In this paper, we propose a new approach to study the dark sector of the universe by considering the dark energy as an emerging q-deformed bosonic scalar field which is not only interacting with the dark matter, but also nonminimally coupled to gravity, in the framework of standard Einsteinian gravity. In order to analyze the dynamic of the system, we first give the quantum field theoretical description of the q-deformed scalar field dark energy and then construct the action and the dynamical structure of this interacting and nonminimally coupled dark sector. As a second issue, we perform the phase-space analysis of the model to check the reliability of our proposal by searching the stable attractor solutions implying the late-time accelerating expansion phase of the universe.

Holographic dark energy interacting with dark matter in a closed Universe

International Nuclear Information System (INIS)

Cruz, Norman; Lepe, Samuel; Pena, Francisco; Saavedra, Joel

2008-01-01

A cosmological model of an holographic dark energy interacting with dark matter throughout a decaying term of the form Q=3(λ 1 ρ DE +λ 2 ρ m )H is investigated. General constraint on the parameters of the model are found when accelerated expansion is imposed and we found a phantom scenario, without any reference to a specific equation of state for the dark energy. The behavior of equation of state for dark energy is also discussed

Dynamics of Interacting Tachyonic Teleparallel Dark Energy

International Nuclear Information System (INIS)

Banijamali, Ali

2014-01-01

We consider a tachyon scalar field which is nonminimally coupled to gravity in the framework of teleparallel gravity. We analyze the phase-space of the model, known as tachyonic teleparallel dark energy, in the presence of an interaction between dark energy and background matter. We find that although there exist some late-time accelerated attractor solutions, there is no scaling attractor. So, unfortunately interacting tachyonic teleparallel dark energy cannot alleviate the coincidence problem.

Signature of the interaction between dark energy and dark matter in galaxy clusters

International Nuclear Information System (INIS)

Abdalla, Elcio; Abramo, L. Raul; Sodre, Laerte; Wang Bin

2009-01-01

We investigate the influence of an interaction between dark energy and dark matter upon the dynamics of galaxy clusters. We obtain the general Layser-Irvine equation in the presence of interactions, and find how, in that case, the virial theorem stands corrected. Using optical, X-ray and weak lensing data from 33 relaxed galaxy clusters, we put constraints on the strength of the coupling between the dark sectors. Available data suggests that this coupling is small but positive, indicating that dark energy might be decaying into dark matter. Systematic effects between the several mass estimates, however, should be better known, before definitive conclusions on the magnitude and significance of this coupling could be established

Cosmological implications of a dark matter self-interaction energy density

International Nuclear Information System (INIS)

Stiele, Rainer; Boeckel, Tillmann; Schaffner-Bielich, Juergen

2010-01-01

We investigate cosmological constraints on an energy density contribution of elastic dark matter self-interactions characterized by the mass of the exchange particle m SI and coupling constant α SI . Because of the expansion behavior in a Robertson-Walker metric we investigate self-interacting dark matter that is warm in the case of thermal relics. The scaling behavior of dark matter self-interaction energy density (ρ SI ∝a -6 ) shows that it can be the dominant contribution (only) in the very early universe. Thus its impact on primordial nucleosynthesis is used to restrict the interaction strength m SI /√(α SI ), which we find to be at least as strong as the strong interaction. Furthermore we explore dark matter decoupling in a self-interaction dominated universe, which is done for the self-interacting warm dark matter as well as for collisionless cold dark matter in a two component scenario. We find that strong dark matter self-interactions do not contradict superweak inelastic interactions between self-interacting dark matter and baryonic matter (σ A SIDM weak ) and that the natural scale of collisionless cold dark matter decoupling exceeds the weak scale (σ A CDM >σ weak ) and depends linearly on the particle mass. Finally structure formation analysis reveals a linear growing solution during self-interaction domination (δ∝a); however, only noncosmological scales are enhanced.

Holographic dark energy interacting with dark matter in a closed Universe

Energy Technology Data Exchange (ETDEWEB)

Cruz, Norman [Departamento de Fisica, Facultad de Ciencia, Universidad de Santiago, Casilla 307, Santiago (Chile); Lepe, Samuel [Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Casilla 4950, Valparaiso (Chile); Pena, Francisco [Departamento de Ciencias Fisicas, Facultad de Ingenieria, Ciencias y Administracion, Universidad de La Frontera, Avda. Francisco Salazar 01145, Casilla 54-D Temuco (Chile); Saavedra, Joel [Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Casilla 4950, Valparaiso (Chile)], E-mail: joel.saavedra@ucv.cl

2008-11-27

A cosmological model of an holographic dark energy interacting with dark matter throughout a decaying term of the form Q=3({lambda}{sub 1}{rho}{sub DE}+{lambda}{sub 2}{rho}{sub m})H is investigated. General constraint on the parameters of the model are found when accelerated expansion is imposed and we found a phantom scenario, without any reference to a specific equation of state for the dark energy. The behavior of equation of state for dark energy is also discussed.

Constraints on the dark matter and dark energy interactions from weak lensing bispectrum tomography

Energy Technology Data Exchange (ETDEWEB)

An, Rui [School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Feng, Chang [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Wang, Bin, E-mail: an_rui@sjtu.edu.cn, E-mail: chang.feng@uci.edu, E-mail: wang_b@sjtu.edu.cn [Center for Gravitation and Cosmology, College of Physical Science and Technology, Yangzhou University, Yangzhou 225009 (China)

2017-10-01

We estimate uncertainties of cosmological parameters for phenomenological interacting dark energy models using weak lensing convergence power spectrum and bispectrum. We focus on the bispectrum tomography and examine how well the weak lensing bispectrum with tomography can constrain the interactions between dark sectors, as well as other cosmological parameters. Employing the Fisher matrix analysis, we forecast parameter uncertainties derived from weak lensing bispectra with a two-bin tomography and place upper bounds on strength of the interactions between the dark sectors. The cosmic shear will be measured from upcoming weak lensing surveys with high sensitivity, thus it enables us to use the higher order correlation functions of weak lensing to constrain the interaction between dark sectors and will potentially provide more stringent results with other observations combined.

Wandering in the Lyman-alpha forest: a study of dark matter-dark radiation interactions

International Nuclear Information System (INIS)

Krall, Rebecca; Cyr-Racine, Francis-Yan; Dvorkin, Cora

2017-01-01

The amplitude of large-scale matter fluctuations inferred from the observed Sunyaev-Zeldovich (SZ) cluster mass function and from weak gravitational lensing studies, when taken at face value, is in tension with measurements of the cosmic microwave background (CMB) and baryon acoustic oscillation (BAO). In this work, we revisit whether this possible discrepancy can be attributed to new interactions in the dark matter sector. Focusing on a cosmological model where dark matter interacts with a dark radiation species until the epoch of matter-radiation equality, we find that measurements of the Lyman-alpha flux power spectrum from the Sloan Digital Sky Survey provide no support to the hypothesis that new dark matter interactions can resolve the possible tension between CMB and large-scale structure (LSS). Indeed, while the addition of dark matter-dark radiation interactions leads to an improvement of 2ΔlnL=12 with respect to the standard Λ cold dark matter (ΛCDM) model when only CMB, BAO, and LSS data are considered, the inclusion of Lyman-alpha data reduces the improvement of the fit to 2ΔlnL=6 relative to ΛCDM . We thus conclude that the statistical evidence for new dark matter interactions (largely driven by the Planck SZ dataset) is marginal at best, and likely caused by systematics in the data. We also perform a Fisher forecast analysis for the reach of a future dataset composed of a CMB-S4 experiment combined with the Large Synoptic Survey Telescope galaxy survey. We find that the constraint on the effective number of fluid-like dark radiation species, Δ N fluid , will be improved by an order of magnitude compared to current bounds.

On dark degeneracy and interacting models

International Nuclear Information System (INIS)

Carneiro, S.; Borges, H.A.

2014-01-01

Cosmological background observations cannot fix the dark energy equation of state, which is related to a degeneracy in the definition of the dark sector components. Here we show that this degeneracy can be broken at perturbation level by imposing two observational properties on dark matter. First, dark matter is defined as the clustering component we observe in large scale structures. This definition is meaningful only if dark energy is unperturbed, which is achieved if we additionally assume, as a second condition, that dark matter is cold, i.e. non-relativistic. As a consequence, dark energy models with equation-of-state parameter −1 ≤ ω < 0 are reduced to two observationally distinguishable classes with ω = −1, equally competitive when tested against observations. The first comprises the ΛCDM model with constant dark energy density. The second consists of interacting models with an energy flux from dark energy to dark matter

Almost Kaehler Ricci Flows and Einstein and Lagrange-Finsler Structures on Lie Algebroids

CERN Document Server

Vacaru, Sergiu I

2015-01-01

In this work we investigate Ricci flows of almost Kaehler structures on Lie algebroids when the fundamental geometric objects are completely determined by (semi) Riemannian metrics, or effective) regular generating Lagrange/ Finsler, functions. There are constructed canonical almost symplectic connections for which the geometric flows can be represented as gradient ones and characterized by nonholonomic deformations of Grigory Perelman's functionals. The first goal of this paper is to define such thermodynamical type values and derive almost K\\"ahler - Ricci geometric evolution equations. The second goal is to study how fixed Lie algebroid, i.e. Ricci soliton, configurations can be constructed for Riemannian manifolds and/or (co) tangent bundles endowed with nonholonomic distributions modelling (generalized) Einstein or Finsler - Cartan spaces. Finally, there are provided some examples of generic off-diagonal solutions for Lie algebroid type Ricci solitons and (effective) Einstein and Lagrange-Finsler algebro...

Electroweakly-interacting Dirac dark matter

International Nuclear Information System (INIS)

Nagata, Natsumi

2014-11-01

We consider a class of fermionic dark matter candidates that are charged under both the SU(2) L and U(1) Y gauge interactions. Such a dark matter is stringently restricted by the dark matter direct detection experiments, since the Z-boson exchange processes induce too large dark matter-nucleus elastic scattering cross sections. Effects of ultraviolet (UV) physics, however, split it into two Majorana fermions to evade the constraint. These effects may be probed by means of the dark matter-nucleus scattering via the Higgs-boson exchange process, as well as the electric dipole moments induced by the dark matter and its SU(2) L partner fields. In this Letter, we evaluate them with effective operators that describe the UV-physics effects. It turns out that the constraints coming from the experiments for the quantities have already restricted the dark matters with hypercharge Y≥3/2. Future experiments have sensitivities to probe this class of dark matter candidates, and may disfavor the Y≥1 cases if no signal is observed. In this case, only the Y=0 and 1/2 cases may be the remaining possibilities for the SU(2) L charged fermionic dark matter candidates.

Dark matter and dark energy interactions: theoretical challenges, cosmological implications and observational signatures.

Science.gov (United States)

Wang, B; Abdalla, E; Atrio-Barandela, F; Pavón, D

2016-09-01

Models where dark matter and dark energy interact with each other have been proposed to solve the coincidence problem. We review the motivations underlying the need to introduce such interaction, its influence on the background dynamics and how it modifies the evolution of linear perturbations. We test models using the most recent observational data and we find that the interaction is compatible with the current astronomical and cosmological data. Finally, we describe the forthcoming data sets from current and future facilities that are being constructed or designed that will allow a clearer understanding of the physics of the dark sector.

Dark energy interacting with dark matter and a third fluid: Possible EoS for this component

International Nuclear Information System (INIS)

Cruz, Norman; Lepe, Samuel; Pena, Francisco

2011-01-01

A cosmological model of dark energy interacting with dark matter and another general component of the universe is considered. The equations for the coincidence parameters r and s, which represent the ratios between dark energy and dark matter and the other cosmic fluid respectively, are analyzed in terms of the stability of stationary solutions. The obtained general results allow to shed some light on the equations of state of the three interacting fluids, due to the constraints imposed by the stability of the solutions. We found that for an interaction proportional to the sum of the dark energy density and the third fluid density, the hypothetical fluid must have positive pressure, which leads naturally to a cosmological scenario with radiation, unparticle or even some form of warm dark matter as the third interacting fluid.

Dark energy interacting with dark matter and a third fluid: Possible EoS for this component

Energy Technology Data Exchange (ETDEWEB)

Cruz, Norman, E-mail: ncruz@lauca.usach.c [Departamento de Fisica, Facultad de Ciencia, Universidad de Santiago, Casilla 307, Santiago (Chile); Lepe, Samuel, E-mail: slepe@ucv.c [Instituto de Fisica, Facultad de Ciencias, Pontificia Universidad Catolica de Valparaiso, Casilla 4059, Valparaiso (Chile); Pena, Francisco, E-mail: fcampos@ufro.c [Departamento de Ciencias Fisicas, Facultad de Ingenieria, Ciencias y Administracion, Universidad de La Frontera, Avda. Francisco Salazar 01145, Casilla 54-D, Temuco (Chile)

2011-05-09

A cosmological model of dark energy interacting with dark matter and another general component of the universe is considered. The equations for the coincidence parameters r and s, which represent the ratios between dark energy and dark matter and the other cosmic fluid respectively, are analyzed in terms of the stability of stationary solutions. The obtained general results allow to shed some light on the equations of state of the three interacting fluids, due to the constraints imposed by the stability of the solutions. We found that for an interaction proportional to the sum of the dark energy density and the third fluid density, the hypothetical fluid must have positive pressure, which leads naturally to a cosmological scenario with radiation, unparticle or even some form of warm dark matter as the third interacting fluid.

The imprint of the interaction between dark sectors in galaxy clusters

International Nuclear Information System (INIS)

He, Jian-Hua; Wang, Bin; Abdalla, Elcio; Pavon, Diego

2010-01-01

Based on perturbation theory, we study the dynamics of how dark matter and dark energy in the collapsing system approach dynamical equilibrium when they are in interaction. We find that the interaction between dark sectors cannot ensure the dark energy to fully cluster along with dark matter. When dark energy does not trace dark matter, we present a new treatment on studying the structure formation in the spherical collapsing system. Furthermore we examine the cluster number counts dependence on the interaction between dark sectors and analyze how dark energy inhomogeneities affect cluster abundances. It is shown that cluster number counts can provide specific signature of dark sectors interaction and dark energy inhomogeneities

Evidence for dark matter interactions in cosmological precision data?

International Nuclear Information System (INIS)

Lesgourgues, Julien; Marques-Tavares, Gustavo; Schmaltz, Martin

2016-01-01

We study a two-parameter extension of the cosmological standard model ΛCDM in which cold dark matter interacts with a new form of dark radiation. The two parameters correspond to the energy density in the dark radiation fluid ΔN fluid and the interaction strength between dark matter and dark radiation. The interactions give rise to a very weak ''dark matter drag'' which damps the growth of matter density perturbations throughout radiation domination, allowing to reconcile the tension between predictions of large scale structure from the CMB and direct measurements of σ 8 . We perform a precision fit to Planck CMB data, BAO, large scale structure, and direct measurements of the expansion rate of the universe today. Our model lowers the χ-squared relative to ΛCDM by about 12, corresponding to a preference for non-zero dark matter drag by more than 3σ. Particle physics models which naturally produce a dark matter drag of the required form include the recently proposed non-Abelian dark matter model in which the dark radiation corresponds to massless dark gluons

Bounds on dark matter interactions with electroweak gauge bosons

Energy Technology Data Exchange (ETDEWEB)

Cotta, R. C.; Hewett, J. L.; Le, M. -P.; Rizzo, T. G.

2013-12-01

We investigate scenarios in which dark matter interacts with the Standard Model primarily through electroweak gauge bosons. We employ an effective field theory framework wherein the Standard Model and the dark matter particle are the only light states in order to derive model-independent bounds. Bounds on such interactions are derived from dark matter production by weak boson fusion at the LHC, indirect detection searches for the products of dark matter annihilation and from the measured invisible width of the Z ⁰ . We find that limits on the UV scale, Λ , reach weak scale values for most operators and values of the dark matter mass, thus probing the most natural scenarios in the weakly interacting massive particle dark matter paradigm. Our bounds suggest that light dark matter ( m _χ ≲ m _Z / 2 or m _χ ≲ 100 – 200 GeV , depending on the operator) cannot interact only with the electroweak gauge bosons of the Standard Model, but rather requires additional operator contributions or dark sector structure to avoid overclosing the Universe.

Dynamics of interacting dark energy

International Nuclear Information System (INIS)

Caldera-Cabral, Gabriela; Maartens, Roy; Urena-Lopez, L. Arturo

2009-01-01

Dark energy and dark matter are only indirectly measured via their gravitational effects. It is possible that there is an exchange of energy within the dark sector, and this offers an interesting alternative approach to the coincidence problem. We consider two broad classes of interacting models where the energy exchange is a linear combination of the dark sector densities. The first class has been previously investigated, but we define new variables and find a new exact solution, which allows for a more direct, transparent, and comprehensive analysis. The second class has not been investigated in general form before. We give general conditions on the parameters in both classes to avoid unphysical behavior (such as negative energy densities).

Wandering in the Lyman-alpha forest: a study of dark matter-dark radiation interactions

Energy Technology Data Exchange (ETDEWEB)

Krall, Rebecca; Cyr-Racine, Francis-Yan; Dvorkin, Cora, E-mail: rkrall@physics.harvard.edu, E-mail: fcyrraci@physics.harvard.edu, E-mail: dvorkin@physics.harvard.edu [Harvard University, Department of Physics, Cambridge, MA 02138 (United States)

2017-09-01

The amplitude of large-scale matter fluctuations inferred from the observed Sunyaev-Zeldovich (SZ) cluster mass function and from weak gravitational lensing studies, when taken at face value, is in tension with measurements of the cosmic microwave background (CMB) and baryon acoustic oscillation (BAO). In this work, we revisit whether this possible discrepancy can be attributed to new interactions in the dark matter sector. Focusing on a cosmological model where dark matter interacts with a dark radiation species until the epoch of matter-radiation equality, we find that measurements of the Lyman-alpha flux power spectrum from the Sloan Digital Sky Survey provide no support to the hypothesis that new dark matter interactions can resolve the possible tension between CMB and large-scale structure (LSS). Indeed, while the addition of dark matter-dark radiation interactions leads to an improvement of 2ΔlnL=12 with respect to the standard Λ cold dark matter (ΛCDM) model when only CMB, BAO, and LSS data are considered, the inclusion of Lyman-alpha data reduces the improvement of the fit to 2ΔlnL=6 relative to ΛCDM . We thus conclude that the statistical evidence for new dark matter interactions (largely driven by the Planck SZ dataset) is marginal at best, and likely caused by systematics in the data. We also perform a Fisher forecast analysis for the reach of a future dataset composed of a CMB-S4 experiment combined with the Large Synoptic Survey Telescope galaxy survey. We find that the constraint on the effective number of fluid-like dark radiation species, Δ N {sub fluid}, will be improved by an order of magnitude compared to current bounds.

Revisit of the interaction between holographic dark energy and dark matter

International Nuclear Information System (INIS)

Zhang, Zhenhui; Li, Xiao-Dong; Li, Song; Li, Miao; Zhang, Xin

2012-01-01

In this paper we investigate the possible direct, non-gravitational interaction between holographic dark energy (HDE) and dark matter. Firstly, we start with two simple models with the interaction terms Q∝ρ dm and Q∝ρ de , and then we move on to the general form Q∝ρ m α ρ de β . The cosmological constraints of the models are obtained from the joint analysis of the present Union2.1+BAO+CMB+H 0 data. We find that the data slightly favor an energy flow from dark matter to dark energy, although the original HDE model still lies in the 95.4% confidence level (CL) region. For all models we find c dm and ρ de is smaller, and the relative increment (decrement) amount of the energy in the dark matter component is constrained to be less than 9% (15%) at the 95.4% CL. By introducing the interaction, we find that even when c < 1 the big rip still can be avoided due to the existence of a de Sitter solution at z→−1. We show that this solution can not be accomplished in the two simple models, while for the general model such a solution can be achieved with a large β, and the big rip may be avoided at the 95.4% CL

The continuous tower of scalar fields as a system of interacting dark matter–dark energy

International Nuclear Information System (INIS)

Santos, Paulo

2015-01-01

This paper aims to introduce a new parameterisation for the coupling Q in interacting dark matter and dark energy models by connecting said models with the Continuous Tower of Scalar Fields model. Based upon the existence of a dark matter and a dark energy sectors in the Continuous Tower of Scalar Fields, a simplification is considered for the evolution of a single scalar field from the tower, validated in this paper. This allows for the results obtained with the Continuous Tower of Scalar Fields model to match those of an interacting dark matter–dark energy system, considering that the energy transferred from one fluid to the other is given by the energy of the scalar fields that start oscillating at a given time, rather than considering that the energy transference depends on properties of the whole fluids that are interacting.

Shape signature based on Ricci flow and optimal mass transportation

Science.gov (United States)

Luo, Wei; Su, Zengyu; Zhang, Min; Zeng, Wei; Dai, Junfei; Gu, Xianfeng

2014-11-01

A shape signature based on surface Ricci flow and optimal mass transportation is introduced for the purpose of surface comparison. First, the surface is conformally mapped onto plane by Ricci flow, which induces a measure on the planar domain. Second, the unique optimal mass transport map is computed that transports the new measure to the canonical measure on the plane. The map is obtained by a convex optimization process. This optimal transport map encodes all the information of the Riemannian metric on the surface. The shape signature consists of the optimal transport map, together with the mean curvature, which can fully recover the original surface. The discrete theories of surface Ricci flow and optimal mass transportation are explained thoroughly. The algorithms are given in detail. The signature is tested on human facial surfaces with different expressions accquired by structured light 3-D scanner based on phase-shifting method. The experimental results demonstrate the efficiency and efficacy of the method.

Boosted dark matter signals uplifted with self-interaction

Energy Technology Data Exchange (ETDEWEB)

Kong, Kyoungchul, E-mail: kckong@ku.edu [Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045 (United States); Mohlabeng, Gopolang, E-mail: mohlabeng319@gmail.com [Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045 (United States); Park, Jong-Chul, E-mail: log1079@gmail.com [Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045 (United States); Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

2015-04-09

We explore detection prospects of a non-standard dark sector in the context of boosted dark matter. We focus on a scenario with two dark matter particles of a large mass difference, where the heavier candidate is secluded and interacts with the standard model particles only at loops, escaping existing direct and indirect detection bounds. Yet its pair annihilation in the galactic center or in the Sun may produce boosted stable particles, which could be detected as visible Cherenkov light in large volume neutrino detectors. In such models with multiple candidates, self-interaction of dark matter particles is naturally utilized in the assisted freeze-out mechanism and is corroborated by various cosmological studies such as N-body simulations of structure formation, observations of dwarf galaxies, and the small scale problem. We show that self-interaction of the secluded (heavier) dark matter greatly enhances the capture rate in the Sun and results in promising signals at current and future experiments. We perform a detailed analysis of the boosted dark matter events for Super-Kamiokande, Hyper-Kamiokande and PINGU, including notable effects such as evaporation due to self-interaction and energy loss in the Sun.

Interacting diffusive unified dark energy and dark matter from scalar fields

Energy Technology Data Exchange (ETDEWEB)

Benisty, David; Guendelman, E.I. [Ben Gurion University of the Negev, Department of Physics, Beersheba (Israel)

2017-06-15

Here we generalize ideas of unified dark matter-dark energy in the context of two measure theories and of dynamical space time theories. In two measure theories one uses metric independent volume elements and this allows one to construct unified dark matter-dark energy, where the cosmological constant appears as an integration constant associated with the equation of motion of the measure fields. The dynamical space-time theories generalize the two measure theories by introducing a vector field whose equation of motion guarantees the conservation of a certain Energy Momentum tensor, which may be related, but in general is not the same as the gravitational Energy Momentum tensor. We propose two formulations of this idea: (I) by demanding that this vector field be the gradient of a scalar, (II) by considering the dynamical space field appearing in another part of the action. Then the dynamical space time theory becomes a theory of Diffusive Unified dark energy and dark matter. These generalizations produce non-conserved energy momentum tensors instead of conserved energy momentum tensors which leads at the end to a formulation of interacting DE-DM dust models in the form of a diffusive type interacting Unified dark energy and dark matter scenario. We solved analytically the theories for perturbative solution and asymptotic solution, and we show that the ΛCDM is a fixed point of these theories at large times. Also a preliminary argument as regards the good behavior of the theory at the quantum level is proposed for both theories. (orig.)

Ricci curvature: An economic indicator for market fragility and systemic risk.

Science.gov (United States)

Sandhu, Romeil S; Georgiou, Tryphon T; Tannenbaum, Allen R

2016-05-01

Quantifying the systemic risk and fragility of financial systems is of vital importance in analyzing market efficiency, deciding on portfolio allocation, and containing financial contagions. At a high level, financial systems may be represented as weighted graphs that characterize the complex web of interacting agents and information flow (for example, debt, stock returns, and shareholder ownership). Such a representation often turns out to provide keen insights. We show that fragility is a system-level characteristic of "business-as-usual" market behavior and that financial crashes are invariably preceded by system-level changes in robustness. This was done by leveraging previous work, which suggests that Ricci curvature, a key geometric feature of a given network, is negatively correlated to increases in network fragility. To illustrate this insight, we examine daily returns from a set of stocks comprising the Standard and Poor's 500 (S&P 500) over a 15-year span to highlight the fact that corresponding changes in Ricci curvature constitute a financial "crash hallmark." This work lays the foundation of understanding how to design (banking) systems and policy regulations in a manner that can combat financial instabilities exposed during the 2007-2008 crisis.

New Li-Yau-Hamilton Inequalities for the Ricci Flow via the Space-Time Approach

OpenAIRE

Chow, Bennett; Knopf, Dan

2002-01-01

We generalize Hamilton's matrix Li-Yau-type Harnack estimate for the Ricci flow by considering the space of all LYH (Li-Yau-Hamilton) quadratics that arise as curvature tensors of space-time connections satisfying the Ricci flow with respect to the natural space-time degenerate metric. As a special case, we employ scaling arguments to derive a linear-type matrix LYH estimate. The new LYH quadratics obtained in this way are associated to the system of the Ricci flow coupled to a 1-form and a 2...

Linear scale bounds on dark matter--dark radiation interactions and connection with the small scale crisis of cold dark matter

DEFF Research Database (Denmark)

Hannestad, Steen; Archidiacono, Maria; Bohr, Sebastian

2017-01-01

One of the open questions in modern cosmology is the small scale crisis of the cold dark matter paradigm. Increasing attention has recently been devoted to self-interacting dark matter models as a possible answer. However, solving the so-called "missing satellites" problem requires in addition...... the presence of an extra relativistic particle (dubbed dark radiation) scattering with dark matter in the early universe. Here we investigate the impact of different theoretical models devising dark matter dark radiation interactions on large scale cosmological observables. We use cosmic microwave background...... data to put constraints on the dark radiation component and its coupling to dark matter. We find that the values of the coupling allowed by the data imply a cut-off scale of the halo mass function consistent with the one required to match the observations of satellites in the Milky Way....

Neutron stars with spin polarized self-interacting dark matter

OpenAIRE

Rezaei, Zeinab

2018-01-01

Dark matter, one of the important portion of the universe, could affect the visible matter in neutron stars. An important physical feature of dark matter is due to the spin of dark matter particles. Here, applying the piecewise polytropic equation of state for the neutron star matter and the equation of state of spin polarized self-interacting dark matter, we investigate the structure of neutron stars which are influenced by the spin polarized self-interacting dark matter. The behavior of the...

Tying dark matter to baryons with self-interactions.

Science.gov (United States)

Kaplinghat, Manoj; Keeley, Ryan E; Linden, Tim; Yu, Hai-Bo

2014-07-11

Self-interacting dark matter (SIDM) models have been proposed to solve the small-scale issues with the collisionless cold dark matter paradigm. We derive equilibrium solutions in these SIDM models for the dark matter halo density profile including the gravitational potential of both baryons and dark matter. Self-interactions drive dark matter to be isothermal and this ties the core sizes and shapes of dark matter halos to the spatial distribution of the stars, a radical departure from previous expectations and from cold dark matter predictions. Compared to predictions of SIDM-only simulations, the core sizes are smaller and the core densities are higher, with the largest effects in baryon-dominated galaxies. As an example, we find a core size around 0.3 kpc for dark matter in the Milky Way, more than an order of magnitude smaller than the core size from SIDM-only simulations, which has important implications for indirect searches of SIDM candidates.

Topologically massive gravity and Ricci-Cotton flow

Energy Technology Data Exchange (ETDEWEB)

Lashkari, Nima; Maloney, Alexander, E-mail: lashkari@physics.mcgill.ca, E-mail: maloney@physics.mcgill.ca [McGill Physics Department, 3600 rue University, Montreal, QC H3A 2T8 (Canada)

2011-05-21

We consider topologically massive gravity (TMG), which is three-dimensional general relativity with a cosmological constant and a gravitational Chern-Simons term. When the cosmological constant is negative the theory has two potential vacuum solutions: anti-de Sitter space and warped anti-de Sitter space. The theory also contains a massive graviton state which renders these solutions unstable for certain values of the parameters and boundary conditions. We study the decay of these solutions due to the condensation of the massive graviton mode using Ricci-Cotton flow, which is the appropriate generalization of Ricci flow to TMG. When the Chern-Simons coupling is small the AdS solution flows to warped AdS by the condensation of the massive graviton mode. When the coupling is large the situation is reversed, and warped AdS flows to AdS. Minisuperspace models are constructed where these flows are studied explicitly.

Topologically massive gravity and Ricci-Cotton flow

International Nuclear Information System (INIS)

Lashkari, Nima; Maloney, Alexander

2011-01-01

We consider topologically massive gravity (TMG), which is three-dimensional general relativity with a cosmological constant and a gravitational Chern-Simons term. When the cosmological constant is negative the theory has two potential vacuum solutions: anti-de Sitter space and warped anti-de Sitter space. The theory also contains a massive graviton state which renders these solutions unstable for certain values of the parameters and boundary conditions. We study the decay of these solutions due to the condensation of the massive graviton mode using Ricci-Cotton flow, which is the appropriate generalization of Ricci flow to TMG. When the Chern-Simons coupling is small the AdS solution flows to warped AdS by the condensation of the massive graviton mode. When the coupling is large the situation is reversed, and warped AdS flows to AdS. Minisuperspace models are constructed where these flows are studied explicitly.

Weakly interacting dark matter and baryogenesis

International Nuclear Information System (INIS)

Gu Peihong; Lindner, Manfred; Sarkar, Utpal; Zhang Xinmin

2011-01-01

In the present Universe visible and dark matter contribute comparable energy density although they have different properties. This phenomenon can be explained if the dark matter relic density, originating from a dark matter asymmetry, is fully determined by the baryon asymmetry. Thus the dark matter mass is not arbitrary; rather, it becomes predictive. We realize this scenario in baryon (lepton) number conserving models where two or more neutral singlet scalars decay into two or three baryonic (leptonic) dark matter scalars, and also decay into quarks (leptons) through other on-shell and/or off-shell exotic scalar bilinears. The produced baryon (lepton) asymmetries in the dark matter scalar and in the standard model quarks (leptons) are thus equal and opposite. The dark matter mass can be predicted in a range from a few GeV to a few TeV, depending on the baryon (lepton) numbers of the decaying scalars and the dark matter scalar. The dark matter scalar can interact with the visible matter through the exchange of the standard model Higgs boson, opening a window for the dark matter direct detection experiments. These models also provide testable predictions in the searches for the exotic scalar bilinears at LHC.

Mirror matter as self-interacting dark matter

International Nuclear Information System (INIS)

Mohapatra, R.N.; Nussinov, S.; Teplitz, V.L.

2002-01-01

It has been argued that the observed core density profile of galaxies is inconsistent with having a dark matter particle that is collisionless and that alternative dark matter candidates which are self-interacting may explain observations better. One new class of self-interacting dark matter that has been proposed in the context of mirror universe models of particle physics is the mirror hydrogen atom, whose stability is guaranteed by the conservation of mirror baryon number. We show that the effective transport cross section for mirror hydrogen atoms has the right order of magnitude for solving the 'cuspy' halo problem. Furthermore, the suppression of dissipation effects for mirror atoms due to a higher mirror mass scale prevents the mirror halo matter from collapsing into a disk, strengthening the argument for mirror matter as galactic dark matter

Interacting holographic dark energy in Brans-Dicke theory

International Nuclear Information System (INIS)

Sheykhi, Ahmad

2009-01-01

We study cosmological application of interacting holographic energy density in the framework of Brans-Dicke cosmology. We obtain the equation of state and the deceleration parameter of the holographic dark energy in a non-flat universe. As system's IR cutoff we choose the radius of the event horizon measured on the sphere of the horizon, defined as L=ar(t). We find that the combination of Brans-Dicke field and holographic dark energy can accommodate w D =-1 crossing for the equation of state of noninteracting holographic dark energy. When an interaction between dark energy and dark matter is taken into account, the transition of w D to phantom regime can be more easily accounted for than when resort to the Einstein field equations is made.

Nonsmooth differential geometry-an approach tailored for spaces with Ricci curvature bounded from below

CERN Document Server

Gigli, Nicola

2018-01-01

The author discusses in which sense general metric measure spaces possess a first order differential structure. Building on this, spaces with Ricci curvature bounded from below a second order calculus can be developed, permitting the author to define Hessian, covariant/exterior derivatives and Ricci curvature.

Partially acoustic dark matter, interacting dark radiation, and large scale structure

Energy Technology Data Exchange (ETDEWEB)

Chacko, Zackaria [Maryland Center for Fundamental Physics, Department of Physics, University of Maryland,Stadium Dr., College Park, MD 20742 (United States); Cui, Yanou [Maryland Center for Fundamental Physics, Department of Physics, University of Maryland,Stadium Dr., College Park, MD 20742 (United States); Department of Physics and Astronomy, University of California-Riverside,University Ave, Riverside, CA 92521 (United States); Perimeter Institute, 31 Caroline Street, North Waterloo, Ontario N2L 2Y5 (Canada); Hong, Sungwoo [Maryland Center for Fundamental Physics, Department of Physics, University of Maryland,Stadium Dr., College Park, MD 20742 (United States); Okui, Takemichi [Department of Physics, Florida State University,College Avenue, Tallahassee, FL 32306 (United States); Tsai, Yuhsinz [Maryland Center for Fundamental Physics, Department of Physics, University of Maryland,Stadium Dr., College Park, MD 20742 (United States)

2016-12-21

The standard paradigm of collisionless cold dark matter is in tension with measurements on large scales. In particular, the best fit values of the Hubble rate H{sub 0} and the matter density perturbation σ{sub 8} inferred from the cosmic microwave background seem inconsistent with the results from direct measurements. We show that both problems can be solved in a framework in which dark matter consists of two distinct components, a dominant component and a subdominant component. The primary component is cold and collisionless. The secondary component is also cold, but interacts strongly with dark radiation, which itself forms a tightly coupled fluid. The growth of density perturbations in the subdominant component is inhibited by dark acoustic oscillations due to its coupling to the dark radiation, solving the σ{sub 8} problem, while the presence of tightly coupled dark radiation ameliorates the H{sub 0} problem. The subdominant component of dark matter and dark radiation continue to remain in thermal equilibrium until late times, inhibiting the formation of a dark disk. We present an example of a simple model that naturally realizes this scenario in which both constituents of dark matter are thermal WIMPs. Our scenario can be tested by future stage-IV experiments designed to probe the CMB and large scale structure.

Partially acoustic dark matter, interacting dark radiation, and large scale structure

International Nuclear Information System (INIS)

Chacko, Zackaria; Cui, Yanou; Hong, Sungwoo; Okui, Takemichi; Tsai, Yuhsinz

2016-01-01

The standard paradigm of collisionless cold dark matter is in tension with measurements on large scales. In particular, the best fit values of the Hubble rate H 0 and the matter density perturbation σ 8 inferred from the cosmic microwave background seem inconsistent with the results from direct measurements. We show that both problems can be solved in a framework in which dark matter consists of two distinct components, a dominant component and a subdominant component. The primary component is cold and collisionless. The secondary component is also cold, but interacts strongly with dark radiation, which itself forms a tightly coupled fluid. The growth of density perturbations in the subdominant component is inhibited by dark acoustic oscillations due to its coupling to the dark radiation, solving the σ 8 problem, while the presence of tightly coupled dark radiation ameliorates the H 0 problem. The subdominant component of dark matter and dark radiation continue to remain in thermal equilibrium until late times, inhibiting the formation of a dark disk. We present an example of a simple model that naturally realizes this scenario in which both constituents of dark matter are thermal WIMPs. Our scenario can be tested by future stage-IV experiments designed to probe the CMB and large scale structure.

X-ray lines and self-interacting dark matter.

Science.gov (United States)

Mambrini, Yann; Toma, Takashi

We study the correlation between a monochromatic signal from annihilating dark matter and its self-interacting cross section. We apply our argument to a complex scalar dark sector, where the pseudo-scalar plays the role of a warm dark matter candidate while the scalar mediates its interaction with the Standard Model. We combine the recent observation of the cluster Abell 3827 for self-interacting dark matter and the constraints on the annihilation cross section for monochromatic X-ray lines. We also confront our model to a set of recent experimental analyses and find that such an extension can naturally produce a monochromatic keV signal corresponding to recent observations of Perseus or Andromeda, while in the meantime it predicts a self-interacting cross section of the order of [Formula: see text], as recently claimed in the observation of the cluster Abell 3827. We also propose a way to distinguish such models by future direct detection techniques.

Dark-Matter Particles without Weak-Scale Masses or Weak Interactions

International Nuclear Information System (INIS)

Feng, Jonathan L.; Kumar, Jason

2008-01-01

We propose that dark matter is composed of particles that naturally have the correct thermal relic density, but have neither weak-scale masses nor weak interactions. These models emerge naturally from gauge-mediated supersymmetry breaking, where they elegantly solve the dark-matter problem. The framework accommodates single or multiple component dark matter, dark-matter masses from 10 MeV to 10 TeV, and interaction strengths from gravitational to strong. These candidates enhance many direct and indirect signals relative to weakly interacting massive particles and have qualitatively new implications for dark-matter searches and cosmological implications for colliders

Interacting dark energy and the expansion of the universe

CERN Document Server

Silbergleit, Alexander S

2017-01-01

This book presents a high-level study of cosmology with interacting dark energy and no additional fields. It is known that dark energy is not necessarily uniform when other sources of gravity are present: interaction with matter leads to its variation in space and time. The present text studies the cosmological implications of this circumstance by analyzing cosmological models in which the dark energy density interacts with matter and thus changes with the time. The book also includes a translation of a seminal article about the remarkable life and work of E.B. Gliner, the first person to suggest the concept of dark energy in 1965.

Probing interaction and spatial curvature in the holographic dark energy model

International Nuclear Information System (INIS)

Li, Miao; Li, Xiao-Dong; Wang, Shuang; Wang, Yi; Zhang, Xin

2009-01-01

In this paper we place observational constraints on the interaction and spatial curvature in the holographic dark energy model. We consider three kinds of phenomenological interactions between holographic dark energy and matter, i.e., the interaction term Q is proportional to the energy densities of dark energy (ρ Λ ), matter (ρ m ), and matter plus dark energy (ρ m +ρ Λ ). For probing the interaction and spatial curvature in the holographic dark energy model, we use the latest observational data including the type Ia supernovae (SNIa) Constitution data, the shift parameter of the cosmic microwave background (CMB) given by the five-year Wilkinson Microwave Anisotropy Probe (WMAP5) observations, and the baryon acoustic oscillation (BAO) measurement from the Sloan Digital Sky Survey (SDSS). Our results show that the interaction and spatial curvature in the holographic dark energy model are both rather small. Besides, it is interesting to find that there exists significant degeneracy between the phenomenological interaction and the spatial curvature in the holographic dark energy model

Evolution of holographic dark energy with interaction term Q∝ Hρde ...

Indian Academy of Sciences (India)

A flat FLRW Universe with dark matter and dark energy, which are interacting witheach other, is considered. The dark energy is represented by the holographic dark energy model and the interaction term is taken as proportional to the dark energy density. We have studied the cosmological evolution and analysed the ...

Interacting ghost dark energy in Brans-Dicke theory

International Nuclear Information System (INIS)

Ebrahimi, Esmaeil; Sheykhi, Ahmad

2011-01-01

We investigate the QCD ghost model of dark energy in the framework of Brans-Dicke cosmology. First, we study the non-interacting ghost dark energy in a flat Brans-Dicke theory. In this case we obtain the equation of state and the deceleration parameters and a differential equation governing the evolution of ghost energy density. Interestingly enough, we find that the equation of state parameter of the non-interacting ghost dark energy can cross the phantom line (w D =-1) provided the parameters of the model are chosen suitably. Then, we generalize the study to the interacting ghost dark energy in both flat and non-flat Brans-Dicke framework and find out that the transition of w D to phantom regime can be more easily achieved for than when resort to the Einstein field equations is made.

Reconstruction of the interaction term between dark matter and dark energy using SNe Ia

Energy Technology Data Exchange (ETDEWEB)

Solano, Freddy Cueva; Nucamendi, Ulises, E-mail: freddy@ifm.umich.mx, E-mail: ulises@ifm.umich.mx [Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio C-3, Ciudad Universitaria, CP. 58040, Morelia, Michoacán (Mexico)

2012-04-01

We apply a parametric reconstruction method to a homogeneous, isotropic and spatially flat Friedmann-Robertson-Walker (FRW) cosmological model filled of a fluid of dark energy (DE) with constant equation of state (EOS) parameter interacting with dark matter (DM)\\@. The reconstruction method is based on expansions of the general interaction term and the relevant cosmological variables in terms of Chebyshev polynomials which form a complete set orthonormal functions. This interaction term describes an exchange of energy flow between the DE and DM within dark sector. To show how the method works we do the reconstruction of the interaction function expanding it in terms of only the first six Chebyshev polynomials and obtain the best estimation for the coefficients of the expansion assuming three models: (a) a DE equation of the state parameter w = −1 (an interacting cosmological Λ), (b) a DE equation of the state parameter w = constant with a dark matter density parameter fixed, (c) a DE equation of the state parameter w = constant with a free constant dark matter density parameter to be estimated, and using the Union2 SNe Ia data set from ''The Supernova Cosmology Project'' (SCP) composed by 557 type Ia supernovae. In both cases, the preliminary reconstruction shows that in the best scenario there exist the possibility of a crossing of the noninteracting line Q = 0 in the recent past within the 1σ and 2σ errors from positive values at early times to negative values at late times. This means that, in this reconstruction, there is an energy transfer from DE to DM at early times and an energy transfer from DM to DE at late times. We conclude that this fact is an indication of the possible existence of a crossing behavior in a general interaction coupling between dark components.

Scattering of Ricci scalar perturbations from Schwarzschild black holes in modified gravity

Energy Technology Data Exchange (ETDEWEB)

Sibandze, Dan B.; Goswami, Rituparno; Maharaj, Sunil D.; Nzioki, Anne Marie [University of KwaZulu-Natal, Astrophysics and Cosmology Research Unit, School of Mathematics Statistics and Computer Science, Private Bag X54001, Durban (South Africa); Dunsby, Peter K.S. [University of Cape Town, Department of Mathematics and Applied Mathematics and ACGC, Cape Town (South Africa)

2017-06-15

It has already been shown that the gravitational waves emitted from a Schwarzschild black hole in f(R) gravity have no signatures of the modification of gravity from General Relativity, as the Regge-Wheeler equation remains invariant. In this paper we consider the perturbations of Ricci scalar in a vacuum Schwarzschild spacetime, which is unique to higher order theories of gravity and is absent in General Relativity. We show that the equation that governs these perturbations can be reduced to a Volterra integral equation. We explicitly calculate the reflection coefficients for the Ricci scalar perturbations, when they are scattered by the black hole potential barrier. Our analysis shows that a larger fraction of these Ricci scalar waves are reflected compared to the gravitational waves. This may provide a novel observational signature for fourth order gravity. (orig.)

Ricci curvature: An economic indicator for market fragility and systemic risk

Science.gov (United States)

Sandhu, Romeil S.; Georgiou, Tryphon T.; Tannenbaum, Allen R.

2016-01-01

Quantifying the systemic risk and fragility of financial systems is of vital importance in analyzing market efficiency, deciding on portfolio allocation, and containing financial contagions. At a high level, financial systems may be represented as weighted graphs that characterize the complex web of interacting agents and information flow (for example, debt, stock returns, and shareholder ownership). Such a representation often turns out to provide keen insights. We show that fragility is a system-level characteristic of “business-as-usual” market behavior and that financial crashes are invariably preceded by system-level changes in robustness. This was done by leveraging previous work, which suggests that Ricci curvature, a key geometric feature of a given network, is negatively correlated to increases in network fragility. To illustrate this insight, we examine daily returns from a set of stocks comprising the Standard and Poor’s 500 (S&P 500) over a 15-year span to highlight the fact that corresponding changes in Ricci curvature constitute a financial “crash hallmark.” This work lays the foundation of understanding how to design (banking) systems and policy regulations in a manner that can combat financial instabilities exposed during the 2007–2008 crisis. PMID:27386522

A more general interacting model of holographic dark energy

International Nuclear Information System (INIS)

Yu Fei; Zhang Jingfei; Lu Jianbo; Wang Wei; Gui Yuanxing

2010-01-01

So far, there have been no theories or observational data that deny the presence of interaction between dark energy and dark matter. We extend naturally the holographic dark energy (HDE) model, proposed by Granda and Oliveros, in which the dark energy density includes not only the square of the Hubble scale, but also the time derivative of the Hubble scale to the case with interaction and the analytic forms for the cosmic parameters are obtained under the specific boundary conditions. The various behaviors concerning the cosmic expansion depend on the introduced numerical parameters which are also constrained. The more general interacting model inherits the features of the previous ones of HDE, keeping the consistency of the theory.

Reconstructing the dark sector interaction with LISA

Energy Technology Data Exchange (ETDEWEB)

Cai, Rong-Gen; Yang, Tao [CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, P.O. Box 2735, Beijing 100190 (China); Tamanini, Nicola, E-mail: cairg@itp.ac.cn, E-mail: nicola.tamanini@cea.fr, E-mail: yangtao@itp.ac.cn [Institut de Physique Théorique, CEA-Saclay, CNRS UMR 3681, Université Paris-Saclay, F-91191 Gif-sur-Yvette (France)

2017-05-01

We perform a forecast analysis of the ability of the LISA space-based interferometer to reconstruct the dark sector interaction using gravitational wave standard sirens at high redshift. We employ Gaussian process methods to reconstruct the distance-redshift relation in a model independent way. We adopt simulated catalogues of standard sirens given by merging massive black hole binaries visible by LISA, with an electromagnetic counterpart detectable by future telescopes. The catalogues are based on three different astrophysical scenarios for the evolution of massive black hole mergers based on the semi-analytic model of E. Barausse, Mon. Not. Roy. Astron. Soc. 423 (2012) 2533. We first use these standard siren datasets to assess the potential of LISA in reconstructing a possible interaction between vacuum dark energy and dark matter. Then we combine the LISA cosmological data with supernovae data simulated for the Dark Energy Survey. We consider two scenarios distinguished by the time duration of the LISA mission: 5 and 10 years. Using only LISA standard siren data, the dark sector interaction can be well reconstructed from redshift z ∼1 to z ∼3 (for a 5 years mission) and z ∼1 up to z ∼5 (for a 10 years mission), though the reconstruction is inefficient at lower redshift. When combined with the DES datasets, the interaction is well reconstructed in the whole redshift region from 0 z ∼ to z ∼3 (5 yr) and z ∼0 to z ∼5 (10 yr), respectively. Massive black hole binary standard sirens can thus be used to constrain the dark sector interaction at redshift ranges not reachable by usual supernovae datasets which probe only the z ∼< 1.5 range. Gravitational wave standard sirens will not only constitute a complementary and alternative way, with respect to familiar electromagnetic observations, to probe the cosmic expansion, but will also provide new tests to constrain possible deviations from the standard ΛCDM dynamics, especially at high redshift.

Consequences of dark matter-dark energy interaction on cosmological parameters derived from type Ia supernova data

International Nuclear Information System (INIS)

Amendola, Luca; Campos, Gabriela Camargo; Rosenfeld, Rogerio

2007-01-01

Models where the dark matter component of the Universe interacts with the dark energy field have been proposed as a solution to the cosmic coincidence problem, since in the attractor regime both dark energy and dark matter scale in the same way. In these models the mass of the cold dark matter particles is a function of the dark energy field responsible for the present acceleration of the Universe, and different scenarios can be parametrized by how the mass of the cold dark matter particles evolves with time. In this article we study the impact of a constant coupling δ between dark energy and dark matter on the determination of a redshift dependent dark energy equation of state w DE (z) and on the dark matter density today from SNIa data. We derive an analytical expression for the luminosity distance in this case. In particular, we show that the presence of such a coupling increases the tension between the cosmic microwave background data from the analysis of the shift parameter in models with constant w DE and SNIa data for realistic values of the present dark matter density fraction. Thus, an independent measurement of the present dark matter density can place constraints on models with interacting dark energy

Searching for signatures of dark matter-dark radiation interaction in observations of large-scale structure

Science.gov (United States)

Pan, Zhen; Kaplinghat, Manoj; Knox, Lloyd

2018-05-01

In this paper, we conduct a search in the latest large-scale structure measurements for signatures of the dark matter-dark radiation interaction proposed by Buen-Abad et al. (2015). We show that prior claims of an inference of this interaction at ˜3 σ significance rely on a use of the Sunyaev-Zeldovich cluster mass function that ignores uncertainty in the mass-observable relationship. Including this uncertainty we find that the inferred level of interaction remains consistent with the data, but so does zero interaction; i.e., there is no longer a preference for nonzero interaction. We also point out that inference of the shape and amplitude of the matter power spectrum from Ly α forest measurements is highly inconsistent with the predictions of the Λ CDM model conditioned on Planck cosmic microwave background temperature, polarization, and lensing power spectra, and that the dark matter-dark radiation model can restore that consistency. We also phenomenologically generalize the model of Buen-Abad et al. (2015) to allow for interaction rates with different scalings with temperature, and find that the original scaling is preferred by the data.

Interacting holographic dark energy with logarithmic correction

International Nuclear Information System (INIS)

Jamil, Mubasher; Farooq, M. Umar

2010-01-01

The holographic dark energy (HDE) is considered to be the most promising candidate of dark energy. Its definition is motivated from the entropy-area relation which depends on the theory of gravity under consideration. Recently a new definition of HDE is proposed with the help of quantum corrections to the entropy-area relation in the setup of loop quantum cosmology. Employing this new definition, we investigate the model of interacting dark energy and derive its effective equation of state. Finally we establish a correspondence between generalized Chaplygin gas and entropy-corrected holographic dark energy

An exotic k-essence interpretation of interactive cosmological models

Energy Technology Data Exchange (ETDEWEB)

Forte, Monica [Universidad de Buenos Aires, Departamento de Fisica, Facultad de ciencias Exactas y Naturales, Buenos Aires (Argentina)

2016-01-15

We define a generalization of scalar fields with non-canonical kinetic term which we call exotic k-essence or, briefly, exotik. These fields are generated by the global description of cosmological models with two interactive fluids in the dark sector and under certain conditions they correspond to usual k-essences. The formalism is applied to the cases of constant potential and of inverse square potential and also we develop the purely exotik version for the modified holographic Ricci type (MHR) of dark energy, where the equations of state are not constant. With the kinetic function F = 1 + mx and the inverse square potential we recover, through the interaction term, the identification between k-essences and quintessences of an exponential potential, already known for Friedmann-Robertson-Walker and Bianchi type I geometries. Worked examples are shown that include the self-interacting MHR and also models with crossing of the phantom divide line (PDL). (orig.)

An exotic k-essence interpretation of interactive cosmological models

International Nuclear Information System (INIS)

Forte, Monica

2016-01-01

We define a generalization of scalar fields with non-canonical kinetic term which we call exotic k-essence or, briefly, exotik. These fields are generated by the global description of cosmological models with two interactive fluids in the dark sector and under certain conditions they correspond to usual k-essences. The formalism is applied to the cases of constant potential and of inverse square potential and also we develop the purely exotik version for the modified holographic Ricci type (MHR) of dark energy, where the equations of state are not constant. With the kinetic function F = 1 + mx and the inverse square potential we recover, through the interaction term, the identification between k-essences and quintessences of an exponential potential, already known for Friedmann-Robertson-Walker and Bianchi type I geometries. Worked examples are shown that include the self-interacting MHR and also models with crossing of the phantom divide line (PDL). (orig.)

Plane Symmetric Dark Energy Models in the Form of Wet Dark Fluid in f ( R, T) Gravity

Science.gov (United States)

Chirde, V. R.; Shekh, S. H.

2016-06-01

In this paper, we have investigated the plane symmetric space-time with wet dark fluid (WDF), which is a candidate for dark energy, in the framework of f ( R, T) gravity Harko et al. 2011, Phys. Rev. D, 84, 024020), where R and T denote the Ricci scalar and the trace of the energy-momentum tensor respectively. We have used the equation of state in the form of WDF for the dark energy component of the Universe. It is modeled on the equation of state p = ω( ρ - ρ ∗). The exact solutions to the corresponding field equations are obtained for power-law and exponential volumetric expansion. The geometrical and physical parameters for both the models are studied. Also, we have discussed the well-known astrophysical phenomena, namely the look-back time, proper distance, the luminosity distance and angular diameter distance with red shift.

Effective description of dark matter self-interactions in small dark matter haloes

International Nuclear Information System (INIS)

Kummer, Janis

2017-07-01

Self-interacting dark matter may have striking astrophysical signatures, such as observ- able offsets between galaxies and dark matter in merging galaxy clusters. Numerical N-body simulations used to predict such observables typically treat the galaxies as collisionless test particles, a questionable assumption given that each galaxy is embedded in its own dark matter halo. To enable a more accurate treatment we develop an effective description of small dark matter haloes taking into account the two major effects due to dark matter self-scatterings: deceleration and evaporation. We point out that self-scatterings can have a sizeable impact on the trajectories of galaxies, diminishing the separation between galaxies and dark matter in merging clusters. This effect depends sensitively on the underlying particle physics, in particular the angular dependence of the self-scattering cross section, and cannot be predicted from the momentum transfer cross section alone.

Interacting vacuum energy in the dark sector

Energy Technology Data Exchange (ETDEWEB)

Chimento, L. P. [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA, CONICET, Cuidad Universitaria, Buenos Aires 1428 (Argentina); Carneiro, S. [Instituto de Física, Uníversídade Federal da Bahia, 40210-340, Salvador, BA (Brazil)

2015-03-26

We analyse three cosmological scenarios with interaction in the dark sector, which are particular cases of a general expression for the energy flux from vacuum to matter. In the first case the interaction leads to a transition from an unstable de Sitter phase to a radiation dominated universe, avoiding in this way the initial singularity. In the second case the interaction gives rise to a slow-roll power-law inflation. Finally, the third scenario is a concordance model for the late-time universe, with the vacuum term decaying into cold dark matter. We identify the physics behind these forms of interaction and show that they can be described as particular types of the modified Chaplygin gas.

A fresh look into the interacting dark matter scenario

Science.gov (United States)

Escudero, Miguel; Lopez-Honorez, Laura; Mena, Olga; Palomares-Ruiz, Sergio; Villanueva-Domingo, Pablo

2018-06-01

The elastic scattering between dark matter particles and radiation represents an attractive possibility to solve a number of discrepancies between observations and standard cold dark matter predictions, as the induced collisional damping would imply a suppression of small-scale structures. We consider this scenario and confront it with measurements of the ionization history of the Universe at several redshifts and with recent estimates of the counts of Milky Way satellite galaxies. We derive a conservative upper bound on the dark matter-photon elastic scattering cross section of σγ DM non-cold dark matter candidates, such as interacting and warm dark matter scenarios. Let us emphasize that bounds of similar magnitude to the ones obtained here could be also derived for models with dark matter-neutrino interactions and would be as constraining as the tightest limits on such scenarios.

Interacting agegraphic dark energy models in non-flat universe

International Nuclear Information System (INIS)

Sheykhi, Ahmad

2009-01-01

A so-called 'agegraphic dark energy' was recently proposed to explain the dark energy-dominated universe. In this Letter, we generalize the agegraphic dark energy models to the universe with spatial curvature in the presence of interaction between dark matter and dark energy. We show that these models can accommodate w D =-1 crossing for the equation of state of dark energy. In the limiting case of a flat universe, i.e. k=0, all previous results of agegraphic dark energy in flat universe are restored.

Interaction between bosonic dark matter and stars

Science.gov (United States)

Brito, Richard; Cardoso, Vitor; Macedo, Caio F. B.; Okawa, Hirotada; Palenzuela, Carlos

2016-02-01

We provide a detailed analysis of how bosonic dark matter "condensates" interact with compact stars, extending significantly the results of a recent Letter [1]. We focus on bosonic fields with mass mB , such as axions, axion-like candidates and hidden photons. Self-gravitating bosonic fields generically form "breathing" configurations, where both the spacetime geometry and the field oscillate, and can interact and cluster at the center of stars. We construct stellar configurations formed by a perfect fluid and a bosonic condensate, and which may describe the late stages of dark matter accretion onto stars, in dark-matter-rich environments. These composite stars oscillate at a frequency which is a multiple of f =2.5 ×1014(mBc2/eV ) Hz . Using perturbative analysis and numerical relativity techniques, we show that these stars are generically stable, and we provide criteria for instability. Our results also indicate that the growth of the dark matter core is halted close to the Chandrasekhar limit. We thus dispel a myth concerning dark matter accretion by stars: dark matter accretion does not necessarily lead to the destruction of the star, nor to collapse to a black hole. Finally, we argue that stars with long-lived bosonic cores may also develop in other theories with effective mass couplings, such as (massless) scalar-tensor theories.

Interacting holographic dark energy with logarithmic correction

OpenAIRE

Jamil, Mubasher; Farooq, M. Umar

2010-01-01

The holographic dark energy (HDE) is considered to be the most promising candidate of dark energy. Its definition is originally motivated from the entropy-area relation which depends on the theory of gravity under consideration. Recently a new definition of HDE is proposed with the help of quantum corrections to the entropy-area relation in the setup of loop quantum cosmology. Using this new definition, we investigate the model of interacting dark energy and derive its effective equation of s...

Discrete Ricci Flow in Higher Dimensions

Science.gov (United States)

2015-02-01

recently, we showed analytically that the SRF equations converged to the continuum RF equations for the neck-pinch 3- geometry [10]. In this analysis we also...Hamilton’s RF. It is the first dimensionally agnostic generalization of RF for PL geometries . We refer to our approach as simplicial Ricci flow (SRF). For a...Discrete Exterior Calculus , Regge Calculus , Piecewise Linear Complex 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18. NUMBER

Simulations of structure formation in interacting dark energy cosmologies

International Nuclear Information System (INIS)

Baldi, M.

2009-01-01

The evidence in favor of a dark energy component dominating the Universe, and driving its presently accelerated expansion, has progressively grown during the last decade of cosmological observations. If this dark energy is given by a dynamic scalar field, it may also have a direct interaction with other matter fields in the Universe, in particular with cold dark matter. Such interaction would imprint new features on the cosmological background evolution as well as on the growth of cosmic structure, like an additional long-range fifth-force between massive particles, or a variation in time of the dark matter particle mass. We present here the implementation of these new physical effects in the N-body code GADGET-2, and we discuss the outcomes of a series of high-resolution N-body simulations for a selected family of interacting dark energy models. We interestingly find, in contrast with previous claims, that the inner overdensity of dark matter halos decreases in these models with respect to ΛCDM, and consistently halo concentrations show a progressive reduction for increasing couplings. Furthermore, the coupling induces a bias in the overdensities of cold dark matter and baryons that determines a decrease of the halo baryon fraction below its cosmological value. These results go in the direction of alleviating tensions between astrophysical observations and the predictions of the ΛCDM model on small scales, thereby opening new room for coupled dark energy models as an alternative to the cosmological constant.

Dark interactions and cosmological fine-tuning

Energy Technology Data Exchange (ETDEWEB)

Quartin, Miguel; Calvao, Mauricio O; Joras, Sergio E; Reis, Ribamar R R; Waga, Ioav, E-mail: mquartin@if.ufrj.br, E-mail: orca@if.ufrj.br, E-mail: joras@if.ufrj.br, E-mail: ribamar@if.ufrj.br, E-mail: ioav@if.ufrj.br [Instituto de Fisica, Universidade Federal do Rio de Janeiro, CEP 21941-972, Rio de Janeiro, RJ (Brazil)

2008-05-15

Cosmological models involving an interaction between dark matter and dark energy have been proposed in order to solve the so-called coincidence problem. Different forms of coupling have been studied, but there have been claims that observational data seem to narrow (some of) them down to something annoyingly close to the {Lambda}CDM (CDM: cold dark matter) model, thus greatly reducing their ability to deal with the problem in the first place. The smallness problem of the initial energy density of dark energy has also been a target of cosmological models in recent years. Making use of a moderately general coupling scheme, this paper aims to unite these different approaches and shed some light on whether this class of models has any true perspective in suppressing the aforementioned issues that plague our current understanding of the universe, in a quantitative and unambiguous way.

Cancellation Mechanism for Dark-Matter-Nucleon Interaction.

Science.gov (United States)

Gross, Christian; Lebedev, Oleg; Toma, Takashi

2017-11-10

We consider a simple Higgs portal dark-matter model, where the standard model is supplemented with a complex scalar whose imaginary part plays the role of weakly interacting massive particle dark matter (DM). We show that the direct DM detection cross section vanishes at the tree level and zero momentum transfer due to a cancellation by virtue of a softly broken symmetry. This cancellation is operative for any mediator masses. As a result, our electroweak-scale dark matter satisfies all of the phenomenological constraints quite naturally.

Planckian Interacting Massive Particles as Dark Matter.

Science.gov (United States)

Garny, Mathias; Sandora, McCullen; Sloth, Martin S

2016-03-11

The standard model could be self-consistent up to the Planck scale according to the present measurements of the Higgs boson mass and top quark Yukawa coupling. It is therefore possible that new physics is only coupled to the standard model through Planck suppressed higher dimensional operators. In this case the weakly interacting massive particle miracle is a mirage, and instead minimality as dictated by Occam's razor would indicate that dark matter is related to the Planck scale, where quantum gravity is anyway expected to manifest itself. Assuming within this framework that dark matter is a Planckian interacting massive particle, we show that the most natural mass larger than 0.01M_{p} is already ruled out by the absence of tensor modes in the cosmic microwave background (CMB). This also indicates that we expect tensor modes in the CMB to be observed soon for this type of minimal dark matter model. Finally, we touch upon the Kaluza-Klein graviton mode as a possible realization of this scenario within UV complete models, as well as further potential signatures and peculiar properties of this type of dark matter candidate. This paradigm therefore leads to a subtle connection between quantum gravity, the physics of primordial inflation, and the nature of dark matter.

Conformal Collineations of the Ricci and Energy-Momentum Tensors in Static Plane Symmetric Space-Times

Science.gov (United States)

Akhtar, S. S.; Hussain, T.; Bokhari, A. H.; Khan, F.

2018-04-01

We provide a complete classification of static plane symmetric space-times according to conformal Ricci collineations (CRCs) and conformal matter collineations (CMCs) in both the degenerate and nondegenerate cases. In the case of a nondegenerate Ricci tensor, we find a general form of the vector field generating CRCs in terms of unknown functions of t and x subject to some integrability conditions. We then solve the integrability conditions in different cases depending upon the nature of the Ricci tensor and conclude that the static plane symmetric space-times have a 7-, 10- or 15-dimensional Lie algebra of CRCs. Moreover, we find that these space-times admit an infinite number of CRCs if the Ricci tensor is degenerate. We use a similar procedure to study CMCs in the case of a degenerate or nondegenerate matter tensor. We obtain the exact form of some static plane symmetric space-time metrics that admit nontrivial CRCs and CMCs. Finally, we present some physical applications of our obtained results by considering a perfect fluid as a source of the energy-momentum tensor.

Constraining strong baryon-dark-matter interactions with primordial nucleosynthesis and cosmic rays

International Nuclear Information System (INIS)

Cyburt, Richard H.; Fields, Brian D.; Pavlidou, Vasiliki; Wandelt, Benjamin

2002-01-01

Self-interacting dark matter (SIDM) was introduced by Spergel and Steinhardt to address possible discrepancies between collisionless dark matter simulations and observations on scales of less than 1 Mpc. We examine the case in which dark matter particles not only have strong self-interactions but also have strong interactions with baryons. The presence of such interactions will have direct implications for nuclear and particle astrophysics. Among these are a change in the predicted abundances from big bang nucleosynthesis (BBN) and the flux of γ rays produced by the decay of neutral pions which originate in collisions between dark matter and galactic cosmic rays (CR). From these effects we constrain the strength of the baryon-dark-matter interactions through the ratio of baryon-dark-matter interaction cross section to dark matter mass, s. We find that BBN places a weak upper limit on this ratio (less-or-similar sign)10 8 cm 2 g -1 . CR-SIDM interactions, however, limit the possible DM-baryon cross section to (less-or-similar sign)5x10 -3 cm 2 g -1 ; this rules out an energy-independent interaction, but not one which falls with center-of-mass velocity s∝1/v or steeper

Quasi-topological Ricci polynomial gravities

Science.gov (United States)

Li, Yue-Zhou; Liu, Hai-Shan; Lü, H.

2018-02-01

Quasi-topological terms in gravity can be viewed as those that give no contribution to the equations of motion for a special subclass of metric ansätze. They therefore play no rôle in constructing these solutions, but can affect the general perturbations. We consider Einstein gravity extended with Ricci tensor polynomial invariants, which admits Einstein metrics with appropriate effective cosmological constants as its vacuum solutions. We construct three types of quasi-topological gravities. The first type is for the most general static metrics with spherical, toroidal or hyperbolic isometries. The second type is for the special static metrics where g tt g rr is constant. The third type is the linearized quasitopological gravities on the Einstein metrics. We construct and classify results that are either dependent on or independent of dimensions, up to the tenth order. We then consider a subset of these three types and obtain Lovelock-like quasi-topological gravities, that are independent of the dimensions. The linearized gravities on Einstein metrics on all dimensions are simply Einstein and hence ghost free. The theories become quasi-topological on static metrics in one specific dimension, but non-trivial in others. We also focus on the quasi-topological Ricci cubic invariant in four dimensions as a specific example to study its effect on holography, including shear viscosity, thermoelectric DC conductivities and butterfly velocity. In particular, we find that the holographic diffusivity bounds can be violated by the quasi-topological terms, which can induce an extra massive mode that yields a butterfly velocity unbound above.

Interactions in the Dark Sector of Cosmology

Science.gov (United States)

Bean, Rachel

The success of modern cosmology hinges on two dramatic augmentations beyond the minimalist assumption of baryonic matter interacting gravitationally through general relativity. The first assumption is that there must exist either new gravitational dynamics or a new component of the cosmic energy budget - dark matter - that allows structure to form and accounts for weak lensing and galactic rotation curves. The second assumption is that a further dynamical modification or energy component - dark energy - exists, driving late-time cosmic acceleration. The need for these is now firmly established through a host of observations, which have raised crucial questions, and present a deep challenge to fundamental physics. The central theme of this proposal is the detailed understanding of the nature of the dark sector through the inevitable interactions between its individual components and with the visible universe. Such interactions can be crucial to a given model's viability, affecting its capability to reproduce the cosmic expansion history; the detailed predictions or structure formation; the gravitational dynamics on astrophysical and solar system scales; the stability of the microphysical model, and its ultimate consistency. While many models are consistent with cosmology on the coarsest scales, as is often the case, the devil may lie in the details. In this proposal we plan a comprehensive analysis of these details, focusing on the interactions within the dark sector and between it and visible matter, and on how these interactions affect the observational and theoretical consistency of models. Since it is unlikely that there will be a silver bullet allowing us to isolate the cause of cosmic acceleration, it is critical to develop a coherent view of the landscape of proposed models, extract clear predictions, and determine what combination of experiments and observations might allow us to test these predictions.

Limits on Self-Interacting Dark Matter from Neutron Stars

DEFF Research Database (Denmark)

Kouvaris, C.

2012-01-01

We impose new severe constraints on the self-interactions of fermionic asymmetric dark matter based on observations of nearby old neutron stars. Weakly interacting massive particle (WIMP) self-interactions mediated by Yukawa-type interactions can lower significantly the number of WIMPs necessary...... for gravitational collapse of the WIMP population accumulated in a neutron star. Even nearby neutron stars located at regions of low dark matter density can accrete a sufficient number of WIMPs that can potentially collapse, form a mini black hole, and destroy the host star. Based on this, we derive constraints...

Dynamics of lumps and dark-dark solitons in the multi-component long-wave-short-wave resonance interaction system

Science.gov (United States)

Rao, Jiguang; Porsezian, Kuppuswamy; He, Jingsong; Kanna, Thambithurai

2018-01-01

General semi-rational solutions of an integrable multi-component (2+1)-dimensional long-wave-short-wave resonance interaction system comprising multiple short waves and a single long wave are obtained by employing the bilinear method. These solutions describe the interactions between various types of solutions, including line rogue waves, lumps, breathers and dark solitons. We only focus on the dynamical behaviours of the interactions between lumps and dark solitons in this paper. Our detailed study reveals two different types of excitation phenomena: fusion and fission. It is shown that the fundamental (simplest) semi-rational solutions can exhibit fission of a dark soliton into a lump and a dark soliton or fusion of one lump and one dark soliton into a dark soliton. The non-fundamental semi-rational solutions are further classified into three subclasses: higher-order, multi- and mixed-type semi-rational solutions. The higher-order semi-rational solutions show the process of annihilation (production) of two or more lumps into (from) one dark soliton. The multi-semi-rational solutions describe N(N≥2) lumps annihilating into or producing from N-dark solitons. The mixed-type semi-rational solutions are a hybrid of higher-order semi-rational solutions and multi-semi-rational solutions. For the mixed-type semi-rational solutions, we demonstrate an interesting dynamical behaviour that is characterized by partial suppression or creation of lumps from the dark solitons.

Dynamics of lumps and dark-dark solitons in the multi-component long-wave-short-wave resonance interaction system.

Science.gov (United States)

Rao, Jiguang; Porsezian, Kuppuswamy; He, Jingsong; Kanna, Thambithurai

2018-01-01

General semi-rational solutions of an integrable multi-component (2+1)-dimensional long-wave-short-wave resonance interaction system comprising multiple short waves and a single long wave are obtained by employing the bilinear method. These solutions describe the interactions between various types of solutions, including line rogue waves, lumps, breathers and dark solitons. We only focus on the dynamical behaviours of the interactions between lumps and dark solitons in this paper. Our detailed study reveals two different types of excitation phenomena: fusion and fission. It is shown that the fundamental (simplest) semi-rational solutions can exhibit fission of a dark soliton into a lump and a dark soliton or fusion of one lump and one dark soliton into a dark soliton. The non-fundamental semi-rational solutions are further classified into three subclasses: higher-order, multi- and mixed-type semi-rational solutions. The higher-order semi-rational solutions show the process of annihilation (production) of two or more lumps into (from) one dark soliton. The multi-semi-rational solutions describe N ( N ≥2) lumps annihilating into or producing from N -dark solitons. The mixed-type semi-rational solutions are a hybrid of higher-order semi-rational solutions and multi-semi-rational solutions. For the mixed-type semi-rational solutions, we demonstrate an interesting dynamical behaviour that is characterized by partial suppression or creation of lumps from the dark solitons.

A MAGNIFIED GLANCE INTO THE DARK SECTOR: PROBING COSMOLOGICAL MODELS WITH STRONG LENSING IN A1689

International Nuclear Information System (INIS)

Magaña, Juan; Motta, V.; Cárdenas, Victor H.; Verdugo, T.; Jullo, Eric

2015-01-01

In this paper we constrain four alternative models to the late cosmic acceleration in the universe: Chevallier–Polarski–Linder (CPL), interacting dark energy (IDE), Ricci holographic dark energy (HDE), and modified polytropic Cardassian (MPC). Strong lensing (SL) images of background galaxies produced by the galaxy cluster Abell 1689 are used to test these models. To perform this analysis we modify the LENSTOOL lens modeling code. The value added by this probe is compared with other complementary probes: Type Ia supernovae (SN Ia), baryon acoustic oscillations (BAO), and cosmic microwave background (CMB). We found that the CPL constraints obtained for the SL data are consistent with those estimated using the other probes. The IDE constraints are consistent with the complementary bounds only if large errors in the SL measurements are considered. The Ricci HDE and MPC constraints are weak, but they are similar to the BAO, SN Ia, and CMB estimations. We also compute the figure of merit as a tool to quantify the goodness of fit of the data. Our results suggest that the SL method provides statistically significant constraints on the CPL parameters but is weak for those of the other models. Finally, we show that the use of the SL measurements in galaxy clusters is a promising and powerful technique to constrain cosmological models. The advantage of this method is that cosmological parameters are estimated by modeling the SL features for each underlying cosmology. These estimations could be further improved by SL constraints coming from other galaxy clusters

Constraints on self interacting dark matter from IceCube results

International Nuclear Information System (INIS)

Albuquerque, Ivone F.M.; Robertson, Denis S.; Heros, Carlos Pérez de los

2014-01-01

If dark matter particles self-interact, their capture by astrophysical objects should be enhanced. As a consequence, the rate by which they annihilate at the center of the object will increase. If their self scattering is strong, it can be observed indirectly through an enhancement of the flux of their annihilation products. Here we investigate the effect of self-interaction on the neutrino flux produced by annihilating dark matter in the center of the Sun. We consider annihilation into two channels: W + W − (or τ + τ − for a dark matter mass below the W mass) and b b-bar . We estimate the event rate in the IceCube detector, using its 79-string configuration, and compare our prediction to their experimental results, hence probing dark matter self interacting models

Holographic reconstruction and renormalization in asymptotically Ricci-flat spacetimes

NARCIS (Netherlands)

Caldeira Costa, R.N.

2012-01-01

In this work we elaborate on an extension of the AdS/CFT framework to a sub-class of gravitational theories with vanishing cosmological constant. By building on earlier ideas, we construct a correspondence between Ricci-flat spacetimes admitting asymptotically hyperbolic hypersurfaces and a family

Formal matched asymptotics for degenerate Ricci flow neckpinches

International Nuclear Information System (INIS)

Angenent, Sigurd B; Isenberg, James; Knopf, Dan

2011-01-01

Gu and Zhu (2008 Commun. Anal. Geom. 16 467–94) have shown that type-II Ricci flow singularities develop from nongeneric rotationally symmetric Riemannian metrics on S n+1 (n≥2). In this paper, we describe and provide plausibility arguments for a detailed asymptotic profile and rate of curvature blow-up that we predict such solutions exhibit

The nongravitational interactions of dark matter in colliding galaxy clusters.

Science.gov (United States)

Harvey, David; Massey, Richard; Kitching, Thomas; Taylor, Andy; Tittley, Eric

2015-03-27

Collisions between galaxy clusters provide a test of the nongravitational forces acting on dark matter. Dark matter's lack of deceleration in the "bullet cluster" collision constrained its self-interaction cross section σ(DM)/m dark matter) for long-ranged forces. Using the Chandra and Hubble Space Telescopes, we have now observed 72 collisions, including both major and minor mergers. Combining these measurements statistically, we detect the existence of dark mass at 7.6σ significance. The position of the dark mass has remained closely aligned within 5.8 ± 8.2 kiloparsecs of associated stars, implying a self-interaction cross section σ(DM)/m < 0.47 cm(2)/g (95% CL) and disfavoring some proposed extensions to the standard model. Copyright © 2015, American Association for the Advancement of Science.

Planckian Interacting Massive Particles as Dark Matter

DEFF Research Database (Denmark)

Garny, Mathias; Sandora, McCullen; Sloth, Martin S.

2016-01-01

. In this case the WIMP miracle is a mirage, and instead minimality as dictated by Occam's razor would indicate that dark matter is related to the Planck scale, where quantum gravity is anyway expected to manifest itself. Assuming within this framework that dark matter is a Planckian Interacting Massive Particle......, we show that the most natural mass larger than $0.01\\,\\textrm{M}_p$ is already ruled out by the absence of tensor modes in the CMB. This also indicates that we expect tensor modes in the CMB to be observed soon for this type of minimal dark matter model. Finally, we touch upon the KK graviton mode...... as a possible realization of this scenario within UV complete models, as well as further potential signatures and peculiar properties of this type of dark matter candidate. This paradigm therefore leads to a subtle connection between quantum gravity, the physics of primordial inflation, and the nature of dark...

Boosted dark matter signals uplifted with self-interaction

OpenAIRE

Kong, Kyoungchul; Mohlabeng, Gopolang; Park, Jong-Chul

2018-01-01

We explore detection prospects of a non-standard dark sector in the context of boosted dark matter. We focus on a scenario with two dark matter particles of a large mass difference, where the heavier candidate is secluded and interacts with the standard model particles only at loops, escaping existing direct and indirect detection bounds. Yet its pair annihilation in the galactic center or in the Sun may produce boosted stable particles, which could be detected as visible Cherenkov light in l...

Helioseismology with long-range dark matter-baryon interactions

DEFF Research Database (Denmark)

Lopes, I.; Panci, Paolo; Silk, J.

2014-01-01

Assuming the existence of a primordial asymmetry in the dark sector, we study how long-range dark matter (DM)-baryon interactions, induced by the kinetic mixing of a new U(1) gauge boson and a photon, affect the evolution of the Sun and, in turn, the sound speed the profile obtained from...

Cosmological evolution of interacting dark energy in Lorentz violation

International Nuclear Information System (INIS)

Zen, Freddy P.; Gunara, Bobby E.; Triyanta; Arianto; Purwanto, A.

2009-01-01

The cosmological evolution of an interacting scalar-field model in which the scalar field interacts with dark matter, radiation, and baryons via Lorentz violation is investigated. We propose a model of interaction through the effective coupling, anti β. Using dynamical system analysis, we study the linear dynamics of an interacting model and show that the dynamics of critical points are completely controlled by two parameters. Some results can be mentioned as follows. Firstly, the sequence of radiation, the dark matter, and the scalar-field dark energy exist and baryons are subdominant. Secondly, the model also allows for the possibility of having a universe in the phantom phase with constant potential. Thirdly, the effective gravitational constant varies with respect to time through anti β. In particular, we consider the simple case where anti β has a quadratic form and has a good agreement with the modified ΛCDM and quintessence models. Finally, we also calculate the first post-Newtonian parameters for our model. (orig.)

Constraints on interacting dark energy models from Planck 2015 and redshift-space distortion data

Energy Technology Data Exchange (ETDEWEB)

Costa, André A.; Abdalla, E. [Instituto de Física, Universidade de São Paulo, C.P. 66318, 05315-970, São Paulo, SP (Brazil); Xu, Xiao-Dong [Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, Cape Town (South Africa); Wang, Bin, E-mail: alencar@if.usp.br, E-mail: xiaodong.xu@uct.ac.za, E-mail: wang_b@sjtu.edu.cn, E-mail: eabdalla@usp.br [Department of Physics and Astronomy, Shanghai Jiao Tong University, 200240 Shanghai (China)

2017-01-01

We investigate phenomenological interactions between dark matter and dark energy and constrain these models by employing the most recent cosmological data including the cosmic microwave background radiation anisotropies from Planck 2015, Type Ia supernovae, baryon acoustic oscillations, the Hubble constant and redshift-space distortions. We find that the interaction in the dark sector parameterized as an energy transfer from dark matter to dark energy is strongly suppressed by the whole updated cosmological data. On the other hand, an interaction between dark sectors with the energy flow from dark energy to dark matter is proved in better agreement with the available cosmological observations. This coupling between dark sectors is needed to alleviate the coincidence problem.

Simple cosmological model with inflation and late times acceleration

Science.gov (United States)

Szydłowski, Marek; Stachowski, Aleksander

2018-03-01

In the framework of polynomial Palatini cosmology, we investigate a simple cosmological homogeneous and isotropic model with matter in the Einstein frame. We show that in this model during cosmic evolution, early inflation appears and the accelerating phase of the expansion for the late times. In this frame we obtain the Friedmann equation with matter and dark energy in the form of a scalar field with a potential whose form is determined in a covariant way by the Ricci scalar of the FRW metric. The energy density of matter and dark energy are also parameterized through the Ricci scalar. Early inflation is obtained only for an infinitesimally small fraction of energy density of matter. Between the matter and dark energy, there exists an interaction because the dark energy is decaying. For the characterization of inflation we calculate the slow roll parameters and the constant roll parameter in terms of the Ricci scalar. We have found a characteristic behavior of the time dependence of density of dark energy on the cosmic time following the logistic-like curve which interpolates two almost constant value phases. From the required numbers of N-folds we have found a bound on the model parameter.

Testing the Interacting Dark Energy Model with Cosmic Microwave Background Anisotropy and Observational Hubble Data

Directory of Open Access Journals (Sweden)

Weiqiang Yang

2017-07-01

Full Text Available The coupling between dark energy and dark matter provides a possible approach to mitigate the coincidence problem of the cosmological standard model. In this paper, we assumed the interacting term was related to the Hubble parameter, energy density of dark energy, and equation of state of dark energy. The interaction rate between dark energy and dark matter was a constant parameter, which was, Q = 3 H ξ ( 1 + w x ρ x . Based on the Markov chain Monte Carlo method, we made a global fitting on the interacting dark energy model from Planck 2015 cosmic microwave background anisotropy and observational Hubble data. We found that the observational data sets slightly favored a small interaction rate between dark energy and dark matter; however, there was not obvious evidence of interaction at the 1 σ level.

Strongly interacting light dark matter

International Nuclear Information System (INIS)

Bruggisser, Sebastian; Riva, Francesco; Urbano, Alfredo

2016-07-01

In the presence of approximate global symmetries that forbid relevant interactions, strongly coupled light Dark Matter (DM) can appear weakly coupled at small-energy and generate a sizable relic abundance. Fundamental principles like unitarity restrict these symmetries to a small class, where the leading interactions are captured by effective operators up to dimension-8. Chiral symmetry, spontaneously broken global symmetries and non-linearly realized supersymmetry are examples of this. Their DM candidates (composite fermions, pseudo-Nambu-Goldstone Bosons and Goldstini) are interesting targets for LHC missing-energy searches.

Quadratic interaction effect on the dark energy density in the universe

International Nuclear Information System (INIS)

Deveci, Derya G; Aydiner, Ekrem

2017-01-01

In this study, we deal with the holographic model of interacting dark components of dark energy and dark matter quadratic case of the equation of state parameter (EoS). The effective equations of states for the interacting holographic energy density are derived and the results are analyzed and compared with the solution of the linear form in the literature. The result of our work shows that the value of interaction term between dark components affects the fixed points at far future in the DE-dominated universe in the case of quadratic EoS parameter; it is a different result from the linear case in the theoretical results in the literature, and as the Quintom scenario the equations of state had coincidence at the cosmological constant boundary of –1 from above to below. (paper)

Constraining the interaction between dark sectors with future HI intensity mapping observations

Science.gov (United States)

Xu, Xiaodong; Ma, Yin-Zhe; Weltman, Amanda

2018-04-01

We study a model of interacting dark matter and dark energy, in which the two components are coupled. We calculate the predictions for the 21-cm intensity mapping power spectra, and forecast the detectability with future single-dish intensity mapping surveys (BINGO, FAST and SKA-I). Since dark energy is turned on at z ˜1 , which falls into the sensitivity range of these radio surveys, the HI intensity mapping technique is an efficient tool to constrain the interaction. By comparing with current constraints on dark sector interactions, we find that future radio surveys will produce tight and reliable constraints on the coupling parameters.

Mechanism for thermal relic dark matter of strongly interacting massive particles.

Science.gov (United States)

Hochberg, Yonit; Kuflik, Eric; Volansky, Tomer; Wacker, Jay G

2014-10-24

We present a new paradigm for achieving thermal relic dark matter. The mechanism arises when a nearly secluded dark sector is thermalized with the standard model after reheating. The freeze-out process is a number-changing 3→2 annihilation of strongly interacting massive particles (SIMPs) in the dark sector, and points to sub-GeV dark matter. The couplings to the visible sector, necessary for maintaining thermal equilibrium with the standard model, imply measurable signals that will allow coverage of a significant part of the parameter space with future indirect- and direct-detection experiments and via direct production of dark matter at colliders. Moreover, 3→2 annihilations typically predict sizable 2→2 self-interactions which naturally address the "core versus cusp" and "too-big-to-fail" small-scale structure formation problems.

The effect of anisotropy on the thermodynamics of the interacting holographic dark energy model

Science.gov (United States)

Hossienkhani, H.; Jafari, A.; Fayaz, V.; Ramezani, A. H.

2018-02-01

By considering a holographic model for the dark energy in an anisotropic universe, the thermodynamics of a scheme of dark matter and dark energy interaction has been investigated. The results suggest that when holographic dark energy and dark matter evolve separately, each of them remains in thermodynamic equilibrium, therefore the interaction between them may be viewed as a stable thermal fluctuation that brings a logarithmic correction to the equilibrium entropy. Also the relation between the interaction term of the dark components and this thermal fluctuation has been obtained. Additionally, for a cosmological interaction as a free function, the anisotropy effects on the generalized second law of thermodynamics have been studied. By using the latest observational data on the holographic dark energy models as the unification of dark matter and dark energy, the observational constraints have been probed. To do this, we focus on observational determinations of the Hubble expansion rate H( z). Finally, we evaluate the anisotropy effects (although low) on various topics, such as the evolution of the statefinder diagnostic, the distance modulus and the spherical collapse from the holographic dark energy model and compare them with the results of the holographic dark energy of the Friedmann-Robertson-Walker and Λ CDM models.

Compact bifluid hybrid stars: hadronic matter mixed with self-interacting fermionic asymmetric dark matter

Energy Technology Data Exchange (ETDEWEB)

Mukhopadhyay, Somnath; Basu, D.N. [HBNI, Variable Energy Cyclotron Centre, Kolkata (India); Atta, Debasis [HBNI, Variable Energy Cyclotron Centre, Kolkata (India); Government General Degree College, West Bengal (India); Imam, Kouser [HBNI, Variable Energy Cyclotron Centre, Kolkata (India); Aliah University, Department of Physics, Kolkata (India); Samanta, C. [Virginia Military Institute, Department of Physics and Astronomy, Lexington, VA (United States)

2017-07-15

The masses and radii of non-rotating and rotating configurations of pure hadronic stars mixed with self-interacting fermionic asymmetric dark matter are calculated within the two-fluid formalism of stellar structure equations in general relativity. The Equation of State (EoS) of nuclear matter is obtained from the density dependent M3Y effective nucleon-nucleon interaction. We consider the dark matter particle mass of 1 GeV. The EoS of self-interacting dark matter is taken from two-body repulsive interactions of the scale of strong interactions. We explore the conditions of equal and different rotational frequencies of nuclear matter and dark matter and find that the maximum mass of differentially rotating stars with self-interacting dark matter to be ∝1.94 M {sub CircleDot} with radius ∝10.4 km. (orig.)

Helioseismology with long-range dark matter-baryon interactions

Energy Technology Data Exchange (ETDEWEB)

Lopes, Ilídio [Centro Multidisciplinar de Astrofísica, Instituto Superior Técnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Panci, Paolo [CP3-Origins and DIAS, University of Southern Denmark, DK-5230 Odense (Denmark); Silk, Joseph, E-mail: ilidio.lopes@tecnico.ulisboa.pt, E-mail: panci@iap.fr, E-mail: silk@astro.ox.ac.uk [Institut d' Astrophysique, UMR 7095 CNRS, Université Pierre et Marie Curie, 98bis Blvd Arago, F-75014 Paris (France)

2014-11-10

Assuming the existence of a primordial asymmetry in the dark sector, we study how long-range dark matter (DM)-baryon interactions, induced by the kinetic mixing of a new U(1) gauge boson and a photon, affect the evolution of the Sun and, in turn, the sound speed the profile obtained from helioseismology. Thanks to the explicit dependence on the exchanged momenta in the differential cross section (Rutherford-like scattering), we find that DM particles with a mass of ∼10 GeV, kinetic mixing parameter of the order of 10{sup –9}, and a mediator with a mass smaller than a few MeV improve the agreement between the best solar model and the helioseismic data without being excluded by direct detection experiments. In particular, the LUX detector will soon be able to either constrain or confirm our best-fit solar model in the presence of a dark sector with long-range interactions that reconcile helioseismology with thermal neutrino results.

Self-Interacting Dark Matter Can Explain Diverse Galactic Rotation Curves.

Science.gov (United States)

Kamada, Ayuki; Kaplinghat, Manoj; Pace, Andrew B; Yu, Hai-Bo

2017-09-15

The rotation curves of spiral galaxies exhibit a diversity that has been difficult to understand in the cold dark matter (CDM) paradigm. We show that the self-interacting dark matter (SIDM) model provides excellent fits to the rotation curves of a sample of galaxies with asymptotic velocities in the 25-300  km/s range that exemplify the full range of diversity. We assume only the halo concentration-mass relation predicted by the CDM model and a fixed value of the self-interaction cross section. In dark-matter-dominated galaxies, thermalization due to self-interactions creates large cores and reduces dark matter densities. In contrast, thermalization leads to denser and smaller cores in more luminous galaxies and naturally explains the flatness of rotation curves of the highly luminous galaxies at small radii. Our results demonstrate that the impact of the baryons on the SIDM halo profile and the scatter from the assembly history of halos as encoded in the concentration-mass relation can explain the diverse rotation curves of spiral galaxies.

Interacting dark energy models as an approach for solving Cosmic Coincidence Problem

Science.gov (United States)

Shojaei, Hamed

Understanding the dark side of the Universe is one of the main tasks of physicists. As there is no thorough understanding of nature of the dark energy, this area is full of new ideas and there may be several discoveries, theoretical or experimental, in the near future. We know that dark energy, though not detected directly, exists and it is not just an exotic idea. The presence of dark energy is required by the observation of the acceleration of the universe. There are several questions regarding dark energy. What is the nature of dark energy? How does it interact with matter, baryonic or dark? Why is the density of dark energy so tiny, i.e. why rhoΛ ≈ 10--120 M4Pl ? And finally why does its density have the same order of magnitude as the density of matter does at the present time? The last question is one form of what is known as the "Cosmic Coincidence Problem" and in this work, I have been investigating one way to resolve this issue. Observations of Type Ia supernovae indicate that we are in an accelerating universe. A matter-dominated universe cannot be accelerating. A good fit is obtained if we assume that energy density parameters are O Λ = 0.7 and Om = 0.3. Here O Λ is related to dark energy, or cosmological constant in ΛCDM model. At the same time data from Wilkinson Microwave Anisotropy Probe (WMAP) satellite and supernova surveys have placed a constraint on w, the equation of state for dark energy, which is actually the ratio of pressure and energy density. Any good theory needs to explain this coincidence problem and yields a value for w between -1.1 and -0.9. I have employed an interesting approach to solve this problem by assuming that there exists an interaction between dark energy and matter in the context of holographic dark energy. This interaction converts dark energy to matter or vice versa without violating the local conservation of energy in the universe. Holographic dark energy by itself indicates that the value of dark energy is related

On the interpretation of dark matter self-interactions in Abell 3827

International Nuclear Information System (INIS)

Kahlhoefer, Felix; Schmidt-Hoberg, Kai; Kummer, Janis; Sarkar, Subir

2015-04-01

Self-interactions of dark matter particles can potentially lead to an observable separation between the dark matter halo and the stars of a galaxy moving through a region of large dark matter density. Such a separation has recently been observed in a galaxy falling into the core of the galaxy cluster Abell 3827. We estimated the DM self-interaction cross section needed to reproduce the observed effects and find that the sensitivity of Abell 3827 has been significantly overestimated in a previous study. Our corrected estimate is σ/m DM ∝3 cm 2 g -1 when self-interactions result in an effective drag force and σ/m DM ∝ 1.5 cm 2 g -1 for the case of contact interactions, in some tension with previous upper bounds.

Interacting viscous ghost tachyon, K-essence and dilaton scalar field models of dark energy

International Nuclear Information System (INIS)

Karami, K; Fahimi, K

2013-01-01

We study the correspondence between the interacting viscous ghost dark energy model with the tachyon, K-essence and dilaton scalar field models in the framework of Einstein gravity. We consider a spatially non-flat FRW universe filled with interacting viscous ghost dark energy and dark matter. We reconstruct both the dynamics and potential of these scalar field models according to the evolutionary behavior of the interacting viscous ghost dark energy model, which can describe the accelerated expansion of the universe. Our numerical results show that the interaction and viscosity have opposite effects on the evolutionary properties of the ghost scalar field models. (paper)

Origin of ΔNeff as a result of an interaction between dark radiation and dark matter

International Nuclear Information System (INIS)

Bjaelde, Ole Eggers; Das, Subinoy; Moss, Adam

2012-01-01

Results from the Wilkinson Microwave Anisotropy Probe (WMAP), Atacama Cosmology Telescope (ACT) and recently from the South Pole Telescope (SPT) have indicated the possible existence of an extra radiation component in addition to the well known three neutrino species predicted by the Standard Model of particle physics. In this paper, we explore the possibility of the apparent extra dark radiation being linked directly to the physics of cold dark matter (CDM). In particular, we consider a generic scenario where dark radiation, as a result of an interaction, is produced directly by a fraction of the dark matter density effectively decaying into dark radiation. At an early epoch when the dark matter density is negligible, as an obvious consequence, the density of dark radiation is also very small. As the Universe approaches matter radiation equality, the dark matter density starts to dominate thereby increasing the content of dark radiation and changing the expansion rate of the Universe. As this increase in dark radiation content happens naturally after Big Bang Nucleosynthesis (BBN), it can relax the possible tension with lower values of radiation degrees of freedom measured from light element abundances compared to that of the CMB. We numerically confront this scenario with WMAP+ACT and WMAP+SPT data and derive an upper limit on the allowed fraction of dark matter decaying into dark radiation

Holographic Dark Energy Interacting with Two Fluids and Validity of Generalized Second Law of Thermodynamics

OpenAIRE

Debnath, Ujjal

2010-01-01

We have considered a cosmological model of holographic dark energy interacting with dark matter and another unknown component of dark energy of the universe. We have assumed two interaction terms $Q$ and $Q'$ in order to include the scenario in which the mutual interaction between the two principal components (i.e., holographic dark energy and dark matter) of the universe leads to some loss in other forms of cosmic constituents. Our model is valid for any sign of $Q$ and $Q'$. If $Q

Astronomical bounds on a cosmological model allowing a general interaction in the dark sector

Science.gov (United States)

Pan, Supriya; Mukherjee, Ankan; Banerjee, Narayan

2018-06-01

Non-gravitational interaction between two barotropic dark fluids, namely the pressureless dust and the dark energy in a spatially flat Friedmann-Lemaître-Robertson-Walker model, has been discussed. It is shown that for the interactions that are linear in terms the energy densities of the dark components and their first order derivatives, the net energy density is governed by a second-order differential equation with constant coefficients. Taking a generalized interaction, which includes a number of already known interactions as special cases, the dynamics of the universe is described for three types of the dark energy equation of state, namely that of interacting quintessence, interacting vacuum energy density, and interacting phantom. The models have been constrained using the standard cosmological probes, Supernovae Type Ia data from joint light curve analysis and the observational Hubble parameter data. Two geometric tests, the cosmographic studies, and the Om diagnostic have been invoked so as to ascertain the behaviour of the present model vis-a-vis the Λ-cold dark matter model. We further discussed the interacting scenarios taking into account the thermodynamic considerations.

Cosmological constraints on the gravitational interactions of matter and dark matter

International Nuclear Information System (INIS)

Bai, Yang; Salvado, Jordi; Stefanek, Ben A.

2015-01-01

Although there is overwhelming evidence of dark matter from its gravitational interaction, we still do not know its precise gravitational interaction strength or whether it obeys the equivalence principle. Using the latest available cosmological data and working within the framework of ΛCDM, we first update the measurement of the multiplicative factor of cosmology-relevant Newton’s constant over the standard laboratory-based value and find that it is consistent with one. In general relativity, dark matter equivalence principle breaking can be mimicked by a long-range dark matter force mediated by an ultra light scalar field. Using the Planck three year data, we find that the dark matter “fifth-force” strength is constrained to be weaker than 10 −4 of the gravitational force. We also introduce a phenomenological, post-Newtonian two-fluid description to explicitly break the equivalence principle by introducing a difference between dark matter inertial and gravitational masses. Depending on the decoupling time of the dark matter and ordinary matter fluids, the ratio of the dark matter gravitational mass to inertial mass is constrained to be unity at the 10 −6 level

Dark matter self-interactions from a general spin-0 mediator

Energy Technology Data Exchange (ETDEWEB)

Kahlhoefer, Felix; Schmidt-Hoberg, Kai; Wild, Sebastian

2017-04-15

Dark matter particles interacting via the exchange of very light spin-0 mediators can have large self-interaction rates and obtain their relic abundance from thermal freeze-out. At the same time, these models face strong bounds from direct and indirect probes of dark matter as well as a number of constraints on the properties of the mediator. We investigate whether these constraints can be consistent with having observable effects from dark matter self-interactions in astrophysical systems. For the case of a mediator with purely scalar couplings we point out the highly relevant impact of low-threshold direct detection experiments like CRESST-II, which essentially rule out the simplest realization of this model. These constraints can be significantly relaxed if the mediator has CP-violating couplings, but then the model faces strong constraints from CMB measurements, which can only be avoided in special regions of parameter space.

Dark matter self-interactions from a general spin-0 mediator

International Nuclear Information System (INIS)

Kahlhoefer, Felix; Schmidt-Hoberg, Kai; Wild, Sebastian

2017-01-01

Dark matter particles interacting via the exchange of very light spin-0 mediators can have large self-interaction rates and obtain their relic abundance from thermal freeze-out. At the same time, these models face strong bounds from direct and indirect probes of dark matter as well as a number of constraints on the properties of the mediator. We investigate whether these constraints can be consistent with having observable effects from dark matter self-interactions in astrophysical systems. For the case of a mediator with purely scalar couplings we point out the highly relevant impact of low-threshold direct detection experiments like CRESST-II, which essentially rule out the simplest realization of this model. These constraints can be significantly relaxed if the mediator has CP-violating couplings, but then the model faces strong constraints from CMB measurements, which can only be avoided in special regions of parameter space.

Dark matter self-interactions from a general spin-0 mediator

Energy Technology Data Exchange (ETDEWEB)

Kahlhoefer, Felix; Schmidt-Hoberg, Kai; Wild, Sebastian, E-mail: felix.kahlhoefer@desy.de, E-mail: kai.schmidt-hoberg@desy.de, E-mail: sebastian.wild@desy.de [DESY, Notkestraße 85, D-22607 Hamburg (Germany)

2017-08-01

Dark matter particles interacting via the exchange of very light spin-0 mediators can have large self-interaction rates and obtain their relic abundance from thermal freeze-out. At the same time, these models face strong bounds from direct and indirect probes of dark matter as well as a number of constraints on the properties of the mediator. We investigate whether these constraints can be consistent with having observable effects from dark matter self-interactions in astrophysical systems. For the case of a mediator with purely scalar couplings we point out the highly relevant impact of low-threshold direct detection experiments like CRESST-II, which essentially rule out the simplest realization of this model. These constraints can be significantly relaxed if the mediator has CP-violating couplings, but then the model faces strong constraints from CMB measurements, which can only be avoided in special regions of parameter space.

Radiating c metric: an example of a proper Ricci Collineation

International Nuclear Information System (INIS)

Aulestia, L.; Nunez, L.; Patino, A.; Rago, H.; Herrera, L.

1984-01-01

A generalization of the charged c metric to the nonstationary case is given. The possibility of associating the energy-momentum tensor with the electromagnetic or neutrino field is discussed. It is shown that, for a specific choice of the time-dependent parameters, the metric admits at least a two-parameter group of proper Ricci collineations

Exacerbating the Cosmological Constant Problem with Interacting Dark Energy Models.

Science.gov (United States)

Marsh, M C David

2017-01-06

Future cosmological surveys will probe the expansion history of the Universe and constrain phenomenological models of dark energy. Such models do not address the fine-tuning problem of the vacuum energy, i.e., the cosmological constant problem (CCP), but can make it spectacularly worse. We show that this is the case for "interacting dark energy" models in which the masses of the dark matter states depend on the dark energy sector. If realized in nature, these models have far-reaching implications for proposed solutions to the CCP that require the number of vacua to exceed the fine-tuning of the vacuum energy density. We show that current estimates of the number of flux vacua in string theory, N_{vac}∼O(10^{272 000}), are far too small to realize certain simple models of interacting dark energy and solve the cosmological constant problem anthropically. These models admit distinctive observational signatures that can be targeted by future gamma-ray observatories, hence making it possible to observationally rule out the anthropic solution to the cosmological constant problem in theories with a finite number of vacua.

Studying generalised dark matter interactions with extended halo-independent methods

Energy Technology Data Exchange (ETDEWEB)

Kahlhoefer, Felix [DESY, Notkestraße 85,D-22607 Hamburg (Germany); Wild, Sebastian [Physik-Department T30d, Technische Universität München,James-Franck-Straße 1, D-85748 Garching (Germany)

2016-10-20

The interpretation of dark matter direct detection experiments is complicated by the fact that neither the astrophysical distribution of dark matter nor the properties of its particle physics interactions with nuclei are known in detail. To address both of these issues in a very general way we develop a new framework that combines the full formalism of non-relativistic effective interactions with state-of-the-art halo-independent methods. This approach makes it possible to analyse direct detection experiments for arbitrary dark matter interactions and quantify the goodness-of-fit independent of astrophysical uncertainties. We employ this method in order to demonstrate that the degeneracy between astrophysical uncertainties and particle physics unknowns is not complete. Certain models can be distinguished in a halo-independent way using a single ton-scale experiment based on liquid xenon, while other models are indistinguishable with a single experiment but can be separated using combined information from several target elements.

Studying generalised dark matter interactions with extended halo-independent methods

International Nuclear Information System (INIS)

Kahlhoefer, Felix; Wild, Sebastian

2016-07-01

The interpretation of dark matter direct detection experiments is complicated by the fact that neither the astrophysical distribution of dark matter nor the properties of its particle physics interactions with nuclei are known in detail. To address both of these issues in a very general way we develop a new framework that combines the full formalism of non-relativistic effective interactions with state-of-the-art halo-independent methods. This approach makes it possible to analyse direct detection experiments for arbitrary dark matter interactions and quantify the goodness-of-fit independent of astrophysical uncertainties. We employ this method in order to demonstrate that the degeneracy between astrophysical uncertainties and particle physics unknowns is not complete. Certain models can be distinguished in a halo-independent way using a single ton-scale experiment based on liquid xenon, while other models are indistinguishable with a single experiment but can be separated using combined information from several target elements.

Spacetimes of Weyl and Ricci type N in higher dimensions

Czech Academy of Sciences Publication Activity Database

Kuchynka, M.; Pravdová, Alena

2016-01-01

Roč. 33, č. 11 (2016), s. 115006 ISSN 0264-9381 R&D Projects: GA ČR GB14-37086G Institutional support: RVO:67985840 Keywords : Weyl type N * Ricci type N * higher dimensions Subject RIV: BA - General Mathematics Impact factor: 3.119, year: 2016 http://iopscience.iop.org/article/10.1088/0264-9381/33/11/115006

Probing the sign-changeable interaction between dark energy and dark matter with current observations

Science.gov (United States)

Guo, Juan-Juan; Zhang, Jing-Fei; Li, Yun-He; He, Dong-Ze; Zhang, Xin

2018-03-01

We consider the models of vacuum energy interacting with cold dark matter in this study, in which the coupling can change sigh during the cosmological evolution. We parameterize the running coupling b by the form b( a) = b 0 a+ b e(1- a), where at the early-time the coupling is given by a constant b e and today the coupling is described by another constant b 0. We explore six specific models with (i) Q = b( a) H 0 ρ 0, (ii) Q = b( a) H 0 ρ de, (iii) Q = b( a) H 0 ρ c, (iv) Q = b( a) Hρ 0, (v) Q = b( a) H ρ de, and (vi) Q = b( a) Hρ c. The current observational data sets we use to constrain the models include the JLA compilation of type Ia supernova data, the Planck 2015 distance priors data of cosmic microwave background observation, the baryon acoustic oscillations measurements, and the Hubble constant direct measurement. We find that, for all the models, we have b 0 0 at around the 1 σ level, and b 0 and b e are in extremely strong anti-correlation. Our results show that the coupling changes sign during the evolution at about the 1 σ level, i.e., the energy transfer is from dark matter to dark energy when dark matter dominates the universe and the energy transfer is from dark energy to dark matter when dark energy dominates the universe.

Ricci time in the Lemaître-Tolman model and the block universe

Science.gov (United States)

Elmahalawy, Yasser; Hellaby, Charles; Ellis, George F. R.

2015-10-01

It is common to think of our universe according to the "block universe" concept, which says that spacetime consists of many "stacked" three-surfaces, labelled by some kind of proper time, . Standard ideas do not distinguish past and future, but Ellis' "evolving block universe" tries to make a fundamental distinction. One proposal for this proper time is the proper time measured along the timelike Ricci eigenlines, starting from the big bang. This work investigates the shape of the "Ricci time" surfaces relative to the the null surfaces. We use the Lemaître-Tolman metric as our inhomogeneous spacetime model, and we find the necessary and sufficient conditions for these constant surfaces, , to be spacelike or timelike. Furthermore, we look at the effect of strong gravity domains by determining the location of timelike S regions relative to apparent horizons. We find that constant Ricci time surfaces are always spacelike near the big bang, while at late times (near the crunch or the extreme far future), they are only timelike under special circumstances. At intermediate times, timelike S regions are common unless the variation of the bang time is restricted. The regions where these surfaces become timelike are often adjacent to apparent horizons, but always outside them, and in particular timelike S regions do not occur inside the horizons of black-hole-like models.

Rigidity of complete generic shrinking Ricci solitons

Science.gov (United States)

Chu, Yawei; Zhou, Jundong; Wang, Xue

2018-01-01

Let (Mn , g , X) be a complete generic shrinking Ricci soliton of dimension n ≥ 3. In this paper, by employing curvature inequalities, the formula of X-Laplacian for the norm square of the trace-free curvature tensor, the weak maximum principle and the estimate of the scalar curvature of (Mn , g) , we prove some rigidity results for (Mn , g , X) . In particular, it is showed that (Mn , g , X) is isometric to Rn or a finite quotient of Sn under a pointwise pinching condition. Moreover, we establish several optimal inequalities and classify those shrinking solitons for equalities.

Higgs exotic decays in general NMSSM with self-interacting dark matter

Science.gov (United States)

Wang, Wenyu; Zhang, Mengchao; Zhao, Jun

2018-04-01

Under current LHC and dark matter constraints, the general NMSSM can have self-interacting dark matter to explain the cosmological small structure. In this scenario, the dark matter is the light singlino-like neutralino (χ) which self-interacts through exchanging the light singlet-like scalars (h1,a1). These light scalars and neutralinos inevitably interact with the 125 GeV SM-like Higgs boson (hSM), which cause the Higgs exotic decays hSM → h1h1, a1a1, χχ. We first demonstrate the parameter space required by the explanation of the cosmological small structure and then display the Higgs exotic decays. We find that in such a parameter space the Higgs exotic decays can have branching ratios of a few percent, which should be accessible in the future e+e‑ colliders.

Strong constraints on self-interacting dark matter with light mediators

International Nuclear Information System (INIS)

Bringmann, Torsten; Walia, Parampreet

2017-04-01

Coupling dark matter to light new particles is an attractive way to combine thermal production with strong velocity-dependent self-interactions. Here we point out that in such models the dark matter annihilation rate is generically enhanced by the Sommerfeld effect, and we derive the resulting constraints from the Cosmic Microwave Background and other indirect detection probes. For the frequently studied case of s-wave annihilation these constraints exclude the entire parameter space where the self-interactions are large enough to address the small-scale problems of structure formation.

Strong constraints on self-interacting dark matter with light mediators

Energy Technology Data Exchange (ETDEWEB)

Bringmann, Torsten; Walia, Parampreet [Oslo Univ. (Norway). Dept. of Physics; Kahlhoefer, Felix; Schmidt-Hoberg, Kai [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2017-04-15

Coupling dark matter to light new particles is an attractive way to combine thermal production with strong velocity-dependent self-interactions. Here we point out that in such models the dark matter annihilation rate is generically enhanced by the Sommerfeld effect, and we derive the resulting constraints from the Cosmic Microwave Background and other indirect detection probes. For the frequently studied case of s-wave annihilation these constraints exclude the entire parameter space where the self-interactions are large enough to address the small-scale problems of structure formation.

Constraining the interacting dark energy models from weak gravity conjecture and recent observations

International Nuclear Information System (INIS)

Chen Ximing; Wang Bin; Pan Nana; Gong Yungui

2011-01-01

We examine the effectiveness of the weak gravity conjecture in constraining the dark energy by comparing with observations. For general dark energy models with plausible phenomenological interactions between dark sectors, we find that although the weak gravity conjecture can constrain the dark energy, the constraint is looser than that from the observations.

Global fits of the dark matter-nucleon effective interactions

International Nuclear Information System (INIS)

Catena, Riccardo; Gondolo, Paolo

2014-01-01

The effective theory of isoscalar dark matter-nucleon interactions mediated by heavy spin-one or spin-zero particles depends on 10 coupling constants besides the dark matter particle mass. Here we compare this 11-dimensional effective theory to current observations in a comprehensive statistical analysis of several direct detection experiments, including the recent LUX, SuperCDMS and CDMSlite results. From a multidimensional scan with about 3 million likelihood evaluations, we extract the marginalized posterior probability density functions (a Bayesian approach) and the profile likelihoods (a frequentist approach), as well as the associated credible regions and confidence levels, for each coupling constant vs dark matter mass and for each pair of coupling constants. We compare the Bayesian and frequentist approach in the light of the currently limited amount of data. We find that current direct detection data contain sufficient information to simultaneously constrain not only the familiar spin-independent and spin-dependent interactions, but also the remaining velocity and momentum dependent couplings predicted by the dark matter-nucleon effective theory. For current experiments associated with a null result, we find strong correlations between some pairs of coupling constants. For experiments that claim a signal (i.e., CoGeNT and DAMA), we find that pairs of coupling constants produce degenerate results

Comparing holographic dark energy models with statefinder

International Nuclear Information System (INIS)

Cui, Jing-Lei; Zhang, Jing-Fei

2014-01-01

We apply the statefinder diagnostic to the holographic dark energy models, including the original holographic dark energy (HDE) model, the new holographic dark energy model, the new agegraphic dark energy (NADE) model, and the Ricci dark energy model. In the low-redshift region the holographic dark energy models are degenerate with each other and with the ΛCDM model in the H(z) and q(z) evolutions. In particular, the HDE model is highly degenerate with the ΛCDM model, and in the HDE model the cases with different parameter values are also in strong degeneracy. Since the observational data are mainly within the low-redshift region, it is very important to break this lowredshift degeneracy in the H(z) and q(z) diagnostics by using some quantities with higher order derivatives of the scale factor. It is shown that the statefinder diagnostic r(z) is very useful in breaking the low-redshift degeneracies. By employing the statefinder diagnostic the holographic dark energy models can be differentiated efficiently in the low-redshift region. The degeneracy between the holographic dark energy models and the ΛCDM model can also be broken by this method. Especially for the HDE model, all the previous strong degeneracies appearing in the H(z) and q(z) diagnostics are broken effectively. But for the NADE model, the degeneracy between the cases with different parameter values cannot be broken, even though the statefinder diagnostic is used. A direct comparison of the holographic dark energy models in the r-s plane is also made, in which the separations between the models (including the ΛCDM model) can be directly measured in the light of the current values {r 0 , s 0 } of the models. (orig.)

On black holes in multidimensional theory with Ricci-flat internal spaces

OpenAIRE

Fadeev, S. B.; Ivashchuk, V. D.; Melnikov, V. N.

2010-01-01

A generalization of the Tangherlini solution for the case of n internal Ricci-flat spaces is obtained. It is shown that in the (2+d)-dimensional section a horizon exists only in the trivial case when the internal-space factors are constant. The p-adic analog of the solution is also considered.

The dark sector from interacting canonical and non-canonical scalar fields

International Nuclear Information System (INIS)

De Souza, Rudinei C; Kremer, Gilberto M

2010-01-01

In this work general models with interactions between two canonical scalar fields and between one non-canonical (tachyon type) and one canonical scalar field are investigated. The potentials and couplings to the gravity are selected through the Noether symmetry approach. These general models are employed to describe interactions between dark energy and dark matter, with the fields being constrained by the astronomical data. The cosmological solutions of some cases are compared with the observed evolution of the late Universe.

L2-Harmonic Forms on Incomplete Riemannian Manifolds with Positive Ricci Curvature

Directory of Open Access Journals (Sweden)

Junya Takahashi

2018-05-01

Full Text Available We construct an incomplete Riemannian manifold with positive Ricci curvature that has non-trivial L 2 -harmonic forms and on which the L 2 -Stokes theorem does not hold. Therefore, a Bochner-type vanishing theorem does not hold for incomplete Riemannian manifolds.

Long-range Self-interacting Dark Matter in the Sun

International Nuclear Information System (INIS)

Chen, Jing; Liang, Zheng-Liang; Wu, Yue-Liang; Zhou, Yu-Feng

2015-01-01

We investigate the implications of the long-rang self-interaction on both the self-capture and the annihilation of the self-interacting dark matter (SIDM) trapped in the Sun. Our discussion is based on a specific SIDM model in which DM particles self-interact via a light scalar mediator, or Yukawa potential, in the context of quantum mechanics. Within this framework, we calculate the self-capture rate across a broad region of parameter space. While the self-capture rate can be obtained separately in the Born regime with perturbative method, and in the classical limits with the Rutherford formula, our calculation covers the gap between in a non-perturbative fashion. Besides, the phenomenology of both the Sommerfeld-enhanced s- and p-wave annihilation of the solar SIDM is also involved in our discussion. Moreover, by combining the analysis of the Super-Kamiokande (SK) data and the observed DM relic density, we constrain the nuclear capture rate of the DM particles in the presence of the dark Yukawa potential. The consequence of the long-range dark force on probing the solar SIDM turns out to be significant if the force-carrier is much lighter than the DM particle, and a quantitative analysis is provided

A direct probe of dark energy interactions with a solar System laboratory

Data.gov (United States)

National Aeronautics and Space Administration — We propose a mission concept for direct detection of dark energy interactions with normal matter in a Solar System laboratory. Dark energy is the leading proposal to...

Supersymmetric dark-matter Q-balls and their interactions in matter

International Nuclear Information System (INIS)

Kusenko, Alexander; Loveridge, Lee C.; Shaposhnikov, Mikhail

2005-01-01

Supersymmetric extensions of the Standard Model contain nontopological solitons, Q-balls, which can be stable and can be a form of cosmological dark matter. Understanding the interaction of SUSY Q-balls with matter fermions is important for both astrophysical limits and laboratory searches for these dark-matter candidates. We show that a baryon scattering off a baryonic SUSY Q-ball can convert into its antiparticle with a high probability, while the baryon number of the Q-ball is increased by two units. For a SUSY Q-ball interacting with matter, this process dominates over those previously discussed in the literature

Bulk viscous cosmological model with interacting dark fluids

International Nuclear Information System (INIS)

Kremer, Gilberto M.; Sobreiro, Octavio A.S.

2012-01-01

We study a cosmological model for a spatially flat Universe whose constituents are a dark energy field and a matter field comprising baryons and dark matter. The constituents are assumed to interact with each other, and a non-equilibrium pressure is introduced to account for irreversible processes. We take the nonequilibrium pressure to be proportional to the Hubble parameter within the framework of a first-order thermodynamic theory. The dark energy and matter fields are coupled by their barotropic indexes, which depend on the ratio between their energy densities. We adjust the free parameters of the model to optimize the fits to the Hubble parameter data. We compare the viscous model with the non-viscous one, and show that the irreversible processes cause the dark-energy and matter-density parameters to become equal and the decelerated-accelerated transition to occur at earlier times. Furthermore, the density and deceleration parameters and the distance modulus have the correct behavior, consistent with a viable scenario of the present status of the Universe . (author)

The diverse density profiles of galaxy clusters with self-interacting dark matter plus baryons

Science.gov (United States)

Robertson, Andrew; Massey, Richard; Eke, Vincent; Tulin, Sean; Yu, Hai-Bo; Bahé, Yannick; Barnes, David J.; Bower, Richard G.; Crain, Robert A.; Dalla Vecchia, Claudio; Kay, Scott T.; Schaller, Matthieu; Schaye, Joop

2018-05-01

We present the first simulated galaxy clusters (M200 > 1014 M⊙) with both self-interacting dark matter (SIDM) and baryonic physics. They exhibit a greater diversity in both dark matter and stellar density profiles than their counterparts in simulations with collisionless dark matter (CDM), which is generated by the complex interplay between dark matter self-interactions and baryonic physics. Despite variations in formation history, we demonstrate that analytical Jeans modelling predicts the SIDM density profiles remarkably well, and the diverse properties of the haloes can be understood in terms of their different final baryon distributions.

Piecewise linear manifolds: Einstein metrics and Ricci flows

International Nuclear Information System (INIS)

Schrader, Robert

2016-01-01

This article provides an attempt to extend concepts from the theory of Riemannian manifolds to piecewise linear (p.l.) spaces. In particular we propose an analogue of the Ricci tensor, which we give the name of an Einstein vector field . On a given set of p.l. spaces we define and discuss (normalized) Einstein flows. p.l. Einstein metrics are defined and examples are provided. Criteria for flows to approach Einstein metrics are formulated. Second variations of the total scalar curvature at a specific Einstein space are calculated. (paper)

Spontaneous compactification and Ricci-flat manifolds with torsion

International Nuclear Information System (INIS)

McInnes, B.

1985-06-01

The Freund-Rubin mechanism is based on the equation Rsub(ik)=lambdagsub(ik) (where lambda>0), which, via Myers' Theorem, implies ''spontaneous'' compactification. The difficulties connected with the cosmological constant in this approach can be resolved if torsion is introduced and lambda set equal to zero, but then compactification ''by hand'' is necessary, since the equation Rsub(ik)=0 can be satisfied both on compact and on non-compact manifolds. In this paper we discuss the global geometry of Ricci-flat manifolds with torsion, and suggest ways of restoring the ''spontaneity'' of the compactification. (author)

Self-interacting dark matter with a stable vector mediator

OpenAIRE

Duerr, Michael; Schmidt-Hoberg, Kai; Wild, Sebastian

2018-01-01

Light vector mediators can naturally induce velocity-dependent dark matter self-interactions while at the same time allowing for the correct dark matter relic abundance via thermal freeze-out. If these mediators subsequently decay into Standard Model states such as electrons or photons however, this is robustly excluded by constraints from the Cosmic Microwave Background. We study to what extent this conclusion can be circumvented if the vector mediator is stable and hence contributes to the ...

Physical and Geometric Interpretations of the Riemann Tensor, Ricci Tensor, and Scalar Curvature

OpenAIRE

Loveridge, Lee C.

2004-01-01

Various interpretations of the Riemann Curvature Tensor, Ricci Tensor, and Scalar Curvature are described. Also, the physical meanings of the Einstein Tensor and Einstein's Equations are discussed. Finally a derivation of Newtonian Gravity from Einstein's Equations is given.

Interaction of ring dark solitons with ring impurities in Bose-Einstein condensates

International Nuclear Information System (INIS)

Xue Jukui

2005-01-01

The interaction of ring dark solitons/vortexes with the ring-shaped repulsive and attractive impurities in two-dimensional Bose-Einstein condensates is investigated numerically. Very rich interaction phenomena are obtained, i.e., not only the interaction between the ring soliton and the impurity, but also the interaction between vortexes and the impurity. The interaction characters, i.e., snaking of ring soliton, quasitrapping or reflection of ring soliton and vortexes by the impurity, strongly depend on initial ring soliton velocity, impurity strength, initial position of ring soliton and impurity. The numerical results also reveal that ring dark solitons/vortexes can be trapped and dragged by an adiabatically moving attractive ring impurity

A search for weakly interacting dark matter with the LUX experiment

International Nuclear Information System (INIS)

INIS-FR--11-0141/Pt.1-25

2010-01-01

Cosmological and astrophysical measurements indicate that our galaxy is filled with a new type of matter previously unknown to physics. This 'dark matter' apparently has no electromagnetic or strong interactions, but an interaction of the strength of the weak nuclear force is strongly suggested by the data. The LUX collaboration is attempting to detect the faint signature of weakly interacting dark matter as it passes through the earth. The experiment searches for recoiling atomic nuclei in a target consisting of 350 kg of liquefied xenon. LUX is the largest experiment of its type ever attempted, and it is expected to improve upon current experimental sensitivities by two orders of magnitude. The experiment is being assembled at the Sanford Underground Science and Engineering Laboratory (SUSEL) in Lead, South Dakota, USA, and first data is expected in 2011. We report on the status of LUX and the prospects for future large-scale dark matter searches with liquid xenon. (author)

Theoretical and observational constraints on {Lambda}-dark matter interaction

Energy Technology Data Exchange (ETDEWEB)

Costa, Francisco Ernandes Matos [Universidade de Sao Paulo (IAG/USP), SP (Brazil). Inst. de Astronomia, Geofisica e Ciencias Atmosfericas

2012-07-01

Full text: Phenomenological models with variable cosmological term (decaying vacuum) have been proposed in literature as an attempt to alleviate the cosmological constant problem and more recently the coincidence problem. In the context of the general relativity theory a cosmological term that varies in space or time requires a coupling with some other cosmic component, so that the total energy-momentum tensor is conserved. In this work we investigate a general class of interacting models in which the attenuated dilution of cold dark matter scales as a{sup -3} (a), where f(a) is an arbitrary function of the cosmic scale factor (a). From thermodynamic arguments, we show that f(a) is proportional to entropy source of the particle creation process. In order to investigate the cosmological consequences of this kind of interacting models, we expand f(a) in a power series up to the first order [f(a) = f{sub 0} + f{sub 1}a, where f{sub 0} and f{sub 1} are constants] and viable cosmological solutions are obtained. In particular, we show that the energy densities of the dark components present a term which dilutes at the same rate acting as a curvature in the evolution of the Universe. Finally, we use current Type Ia supernovae (SNe Ia), baryonic acoustic oscillations (BAO) and cosmic microwave background (CMB) data to place constraints on the interacting function f(a). We also show that an energy flow from dark matter to cosmological term or vice-versa is observationally allowed, however, the second law of thermodynamics forbids an energy flow from dark matter to cosmological term. (author)

Planckian Interacting Massive Particles as Dark Matter

CERN Document Server

Garny, Mathias; Sloth, Martin S.

2016-03-10

The Standard Model could be self-consistent up to the Planck scale according to the present measurements of the Higgs mass and top quark Yukawa coupling. It is therefore possible that new physics is only coupled to the Standard Model through Planck suppressed higher dimensional operators. In this case the WIMP miracle is a mirage, and instead minimality as dictated by Occam's razor would indicate that dark matter is related to the Planck scale, where quantum gravity is anyway expected to manifest itself. Assuming within this framework that dark matter is a Planckian Interacting Massive Particle, we show that the most natural mass larger than $0.01\\,\\textrm{M}_p$ is already ruled out by the absence of tensor modes in the CMB. This also indicates that we expect tensor modes in the CMB to be observed soon for this type of minimal dark matter model. Finally, we touch upon the KK graviton mode as a possible realization of this scenario within UV complete models, as well as further potential signatures and peculiar...

Interacting dark energy model and thermal stability

Energy Technology Data Exchange (ETDEWEB)

Bhandari, Pritikana; Haldar, Sourav; Chakraborty, Subenoy [Jadavpur University, Department of Mathematics, Kolkata, West Bengal (India)

2017-12-15

In the background of the homogeneous and isotropic FLRW model, the thermodynamics of the interacting DE fluid is investigated in the present work. By studying the thermodynamical parameters, namely the heat capacities and the compressibilities, both thermal and mechanical stability are discussed and the restrictions on the equation of state parameter of the dark fluid are analyzed. (orig.)

Interacting dark energy model and thermal stability

International Nuclear Information System (INIS)

Bhandari, Pritikana; Haldar, Sourav; Chakraborty, Subenoy

2017-01-01

In the background of the homogeneous and isotropic FLRW model, the thermodynamics of the interacting DE fluid is investigated in the present work. By studying the thermodynamical parameters, namely the heat capacities and the compressibilities, both thermal and mechanical stability are discussed and the restrictions on the equation of state parameter of the dark fluid are analyzed. (orig.)

Maximum Solutions of Normalized Ricci Flow on 4-Manifolds

Science.gov (United States)

Fang, Fuquan; Zhang, Yuguang; Zhang, Zhenlei

2008-10-01

We consider the maximum solution g( t), t ∈ [0, + ∞), to the normalized Ricci flow. Among other things, we prove that, if ( M, ω) is a smooth compact symplectic 4-manifold such that {b_2^+(M) > 1} and let g( t), t ∈ [0, ∞), be a solution to (1.3) on M whose Ricci curvature satisfies that |Ric( g( t))| ≤ 3 and additionally χ( M) = 3τ ( M) > 0, then there exists an {min mathbb{N}} , and a sequence of points { x j, k ∈ M}, j = 1, . . . , m, satisfying that, by passing to a subsequence, {{(M, g(tk+t), x_{1,k},ldots, x_{m,k})stackrel{d_{GH}}longrightarrow ({\\coprod limitsm_{j=1}} N_j , g_{infty}, x_{1,infty}, ldots, x_{m,infty}),}} t ∈ [0, ∞), in the m-pointed Gromov-Hausdorff sense for any sequence t k → ∞, where ( N j , g ∞), j = 1, . . . , m, are complete complex hyperbolic orbifolds of complex dimension 2 with at most finitely many isolated orbifold points. Moreover, the convergence is C ∞ in the non-singular part of {\\coprod _1^m Nj} and {text{Vol}_{g0}(M)=sum_{j=1}mtext{Vol}_{g_{infty}}(Nj)} , where χ( M) (resp. τ( M)) is the Euler characteristic (resp. signature) of M.

Curtailing the dark side in non-standard neutrino interactions

Energy Technology Data Exchange (ETDEWEB)

Coloma, Pilar [Theoretical Physics Department, Fermi National Accelerator Laboratory,P.O. Box 500, Batavia, IL 60510 (United States); Denton, Peter B. [Theoretical Physics Department, Fermi National Accelerator Laboratory,P.O. Box 500, Batavia, IL 60510 (United States); Niels Bohr International Academy, University of Copenhagen, The Niels Bohr Institute,Blegdamsvej 17, DK-2100, Copenhagen (Denmark); Gonzalez-Garcia, M.C. [Departament de Fisíca Quàntica i Astrofísica and Institut de Ciencies del Cosmos,Universitat de Barcelona, Diagonal 647, E-08028 Barcelona (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA),Pg. Lluis Companys 23, 08010 Barcelona (Spain); C.N. Yang Institute for Theoretical Physics, Stony Brook University,Stony Brook, NY 11794-3840 (United States); Maltoni, Michele [Instituto de Física Teórica UAM/CSIC, Universidad Autónoma de Madrid,Calle de Nicolás Cabrera 13-15, Cantoblanco, E-28049 Madrid (Spain); Schwetz, Thomas [Institut für Kernphysik, Karlsruher Institut für Technologie (KIT), D-76021 Karlsruhe (Germany)

2017-04-20

In presence of non-standard neutrino interactions the neutrino flavor evolution equation is affected by a degeneracy which leads to the so-called LMA-Dark solution. It requires a solar mixing angle in the second octant and implies an ambiguity in the neutrino mass ordering. Non-oscillation experiments are required to break this degeneracy. We perform a combined analysis of data from oscillation experiments with the neutrino scattering experiments CHARM and NuTeV. We find that the degeneracy can be lifted if the non-standard neutrino interactions take place with down quarks, but it remains for up quarks. However, CHARM and NuTeV constraints apply only if the new interactions take place through mediators not much lighter than the electroweak scale. For light mediators we consider the possibility to resolve the degeneracy by using data from future coherent neutrino-nucleus scattering experiments. We find that, for an experiment using a stopped-pion neutrino source, the LMA-Dark degeneracy will either be resolved, or the presence of new interactions in the neutrino sector will be established with high significance.

Classification of the Ricci and Plebanski tensors in general relativity using Newman--Penrose formalism

International Nuclear Information System (INIS)

McIntosh, C.B.G.; Foyster, J.M.; Lun, A.W.h.

1981-01-01

A list is given of a canonical set of the Newman--Penrose quantities Phi/sub A/B, the tetrad components of the trace-free Ricci tensor, for each Plebanski class according to Plebanski's classification of this tensor. This comparative list can easily be extended to cover the classification in tetrad language of any second-order, trace-free, symmetric tensor in a space-time. A fourth-order tensor which is the product of two such tensors was defined by Plebanski and used in his classification. This has the same symmetries as the Weyl tensor. The Petrov classification of this tensor, here called the Plebanski tensor, is discussed along with the classification of the Ricci tensor. The use of the Plebanski tensor in a couple of areas of general relativity is also briefly discussed

Viscous self interacting dark matter and cosmic acceleration

Science.gov (United States)

Atreya, Abhishek; Bhatt, Jitesh R.; Mishra, Arvind

2018-02-01

Self interacting dark matter (SIDM) provides us with a consistent solution to certain astrophysical observations in conflict with collision-less cold DM paradigm. In this work we estimate the shear viscosity (η) and bulk viscosity (ζ) of SIDM, within kinetic theory formalism, for galactic and cluster size SIDM halos. To that extent we make use of the recent constraints on SIDM cross-section for the dwarf galaxies, LSB galaxies and clusters. We also estimate the change in solution of Einstein's equation due to these viscous effects and find that σ/m constraints on SIDM from astrophysical data provide us with sufficient viscosity to account for the observed cosmic acceleration at present epoch, without the need of any additional dark energy component. Using the estimates of dark matter density for galactic and cluster size halo we find that the mean free path of dark matter ~ few Mpc. Thus the smallest scale at which the viscous effect start playing the role is cluster scale. Astrophysical data for dwarf, LSB galaxies and clusters also seems to suggest the same. The entire analysis is independent of any specific particle physics motivated model for SIDM.

Current constraints on interacting holographic dark energy

International Nuclear Information System (INIS)

Wu Qiang; Gong Yungui; Wang Anzhong; Alcaniz, J.S.

2008-01-01

Although there is mounting observational evidence that the cosmic expansion is undergoing a late-time acceleration, the physical mechanism behind such a phenomenon is yet unknown. In this Letter, we investigate a holographic dark energy (HDE) model with interaction between the components of the dark sector in the light of current cosmological observations. We use both the new gold sample of 182 type Ia supernovae (SNe Ia) and the 192 SNe Ia ESSENCE data, the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey and the shift parameter from the three-year Wilkinson Microwave Anisotropy Probe data. In agreement with previous results, we show that these observations suggest a very weak coupling or even a noninteracting HDE. The phantom crossing behavior in the context of these scenarios is also briefly discussed

Using the CMB angular power spectrum to study Dark Matter-photon interactions

International Nuclear Information System (INIS)

Wilkinson, Ryan J.; Boehm, Céline; Lesgourgues, Julien

2014-01-01

In this paper, we explore the impact of Dark Matter-photon interactions on the CMB angular power spectrum. Using the one-year data release of the Planck satellite, we derive an upper bound on the Dark Matter-photon elastic scattering cross section of σ DM−γ ≤ 8 × 10 −31 (m DM /GeV) cm 2 (68% CL) if the cross section is constant and a present-day value of σ DM−γ ≤ 6 × 10 −40 (m DM /GeV) cm 2 (68% CL) if it scales as the temperature squared. For such a limiting cross section, both the B-modes and the TT angular power spectrum are suppressed with respect to ΛCDM predictions for ℓ∼>500 and ℓ∼>3000 respectively, indicating that forthcoming data from CMB polarisation experiments and Planck could help to constrain and characterise the physics of the dark sector. This essentially initiates a new type of dark matter search that is independent of whether dark matter is annihilating, decaying or asymmetric. Thus, any CMB experiment with the ability to measure the temperature and/or polarisation power spectra at high ℓ should be able to investigate the potential interactions of dark matter and contribute to our fundamental understanding of its nature

Feebly Interacting Dark Matter Particle as the Inflaton

OpenAIRE

Tenkanen, Tommi

2016-01-01

We present a scenario where a $Z_2$-symmetric scalar field $\\phi$ first drives cosmic inflation, then reheats the Universe but remains out-of-equilibrium itself, and finally comprises the observed dark matter abundance, produced by particle decays \\`{a} la freeze-in mechanism. We work model-independently without specifying the interactions of the scalar field besides its self-interaction coupling, $\\lambda\\phi^4$, non-minimal coupling to gravity, $\\xi\\phi^2R$, and coupling to another scalar f...

Enhancement of four-wave mixing induced by interacting dark resonances

International Nuclear Information System (INIS)

Yang Weifeng; Gong Shangqing; Niu Yueping; Jin Shiqi; Xu Zhizhan

2005-01-01

We analyse a four-wave mixing (FWM) scheme in a five-level atomic system in which double-dark resonances are present. It is found that the enhancement of FWM in both electromagnetically induced transparency (EIT) windows can be obtained even without the condition of multiphoton resonance. Moreover, the conversion efficiency of FWM in one EIT window can be much larger than that in the other due to the presence of interacting dark resonances

Right-handed neutrino dark matter under the B−L gauge interaction

Energy Technology Data Exchange (ETDEWEB)

Kaneta, Kunio [Center for Theoretical Physics of the Universe, Institute for Basic Science,Daejeon 34051 (Korea, Republic of); Kang, Zhaofeng [School of Physics, Korea Institute for Advanced Study,Seoul 02455 (Korea, Republic of); Lee, Hye-Sung [Center for Theoretical Physics of the Universe, Institute for Basic Science,Daejeon 34051 (Korea, Republic of)

2017-02-07

We study the right-handed neutrino (RHN) dark matter candidate in the minimal U(1){sub B−L} gauge extension of the standard model. The U(1){sub B−L} gauge symmetry offers three RHNs which can address the origin of the neutrino mass, the relic dark matter, and the matter-antimatter asymmetry of the universe. The lightest among the three is taken as the dark matter candidate, which is under the B−L gauge interaction. We investigate various scenarios for this dark matter candidate with the correct relic density by means of the freeze-out or freeze-in mechanism. A viable RHN dark matter mass lies in a wide range including keV to TeV scale. We emphasize the sub-electroweak scale light B−L gauge boson case, and identify the parameter region motivated from the dark matter physics, which can be tested with the planned experiments including the CERN SHiP experiment.

Thermodynamics of interacting holographic dark energy with the apparent horizon as an IR cutoff

International Nuclear Information System (INIS)

Sheykhi, Ahmad

2010-01-01

As soon as an interaction between holographic dark energy and dark matter is taken into account, the identification of an IR cutoff with the Hubble radius H -1 , in a flat universe, can simultaneously drive accelerated expansion and solve the coincidence problem. Based on this, we demonstrate that in a non-flat universe the natural choice for the IR cutoff could be the apparent horizon radius, r-tilde A =1/√(H 2 +k/a 2 ). We show that any interaction of dark matter with holographic dark energy, whose infrared cutoff is set by the apparent horizon radius, implies an accelerated expansion and a constant ratio of the energy densities of both components thus solving the coincidence problem. We also verify that for a universe filled with dark energy and dark matter, the Friedmann equation can be written in the form of the modified first law of thermodynamics, dE = T h dS h + WdV, at the apparent horizon. In addition, the generalized second law of thermodynamics is fulfilled in a region enclosed by the apparent horizon. These results hold regardless of the specific form of dark energy and interaction term. Our study might reveal that in an accelerating universe with spatial curvature, the apparent horizon is a physical boundary from the thermodynamical point of view.

On the K(a)hler-Ricci Flow on Projective Manifolds of General Type

Institute of Scientific and Technical Information of China (English)

Gang TIAN; Zhou ZHANG

2006-01-01

This note concerns the global existence and convergence of the solution for K(a)hler-Ricci flow equation when the canonical class, Kx, is numerically effective and big.We clarify some known results regarding this flow on projective manifolds of general type and also show some new observations and refined results.

Early Career: The search for weakly interacting dark matter with liquid xenon

International Nuclear Information System (INIS)

Hall, Carter

2017-01-01

We report results from a search for weakly interacting dark matter particles obtained with the LUX experiment. LUX was located at a depth of 4850 feet at the Sanford Underground Research Facility in Lead, South Dakota from 2013 through 2016. It found no evidence for dark matter particle interactions and set new constraints on the properties of such particles for masses between 6 GeV and 100 TeV. The work reported here also characterized the performance of such experiments by developing a new calibration technique based upon a tritium beta decay source.

Early Career: The search for weakly interacting dark matter with liquid xenon

Energy Technology Data Exchange (ETDEWEB)

Hall, Carter [Univ. of Maryland, College Park, MD (United States). Dept. of Physics

2017-02-08

We report results from a search for weakly interacting dark matter particles obtained with the LUX experiment. LUX was located at a depth of 4850 feet at the Sanford Underground Research Facility in Lead, South Dakota from 2013 through 2016. It found no evidence for dark matter particle interactions and set new constraints on the properties of such particles for masses between 6 GeV and 100 TeV. The work reported here also characterized the performance of such experiments by developing a new calibration technique based upon a tritium beta decay source.

Signatures of dark radiation in neutrino and dark matter detectors

Science.gov (United States)

Cui, Yanou; Pospelov, Maxim; Pradler, Josef

2018-05-01

We consider the generic possibility that the Universe's energy budget includes some form of relativistic or semi-relativistic dark radiation (DR) with nongravitational interactions with standard model (SM) particles. Such dark radiation may consist of SM singlets or a nonthermal, energetic component of neutrinos. If such DR is created at a relatively recent epoch, it can carry sufficient energy to leave a detectable imprint in experiments designed to search for very weakly interacting particles: dark matter and underground neutrino experiments. We analyze this possibility in some generality, assuming that the interactive dark radiation is sourced by late decays of an unstable particle, potentially a component of dark matter, and considering a variety of possible interactions between the dark radiation and SM particles. Concentrating on the sub-GeV energy region, we derive constraints on different forms of DR using the results of the most sensitive neutrino and dark matter direct detection experiments. In particular, for interacting dark radiation carrying a typical momentum of ˜30 MeV /c , both types of experiments provide competitive constraints. This study also demonstrates that non-standard sources of neutrino emission (e.g., via dark matter decay) are capable of creating a "neutrino floor" for dark matter direct detection that is closer to current bounds than is expected from standard neutrino sources.

Holographic dark energy models: a comparison from the latest observational data

International Nuclear Information System (INIS)

Li, Miao; Li, Xiao-Dong; Wang, Shuang; Zhang, Xin

2009-01-01

The holographic principle of quantum gravity theory has been applied to the dark energy (DE) problem, and so far three holographic DE models have been proposed: the original holographic dark energy (HDE) model, the agegraphic dark energy (ADE) model, and the holographic Ricci dark energy (RDE) model. In this work, we perform the best-fit analysis on these three models, by using the latest observational data including the Union+CFA3 sample of 397 Type Ia supernovae (SNIa), the shift parameter of the cosmic microwave background (CMB) given by the five-year Wilkinson Microwave Anisotropy Probe (WMAP5) observations, and the baryon acoustic oscillation (BAO) measurement from the Sloan Digital Sky Survey (SDSS). The analysis shows that for HDE, χ min 2 = 465.912; for RDE, χ min 2 = 483.130; for ADE, χ min 2 = 481.694. Among these models, HDE model can give the smallest χ 2 min . Besides, we also use the Bayesian evidence (BE) as a model selection criterion to make a comparison. It is found that for HDE, ADE, and RDE, Δln BE = −0.86, −5.17, and −8.14, respectively. So, it seems that the HDE model is more favored by the observational data

Diurnal modulation due to self-interacting mirror and hidden sector dark matter

International Nuclear Information System (INIS)

Foot, R.

2012-01-01

Mirror and more generic hidden sector dark matter models can simultaneously explain the DAMA, CoGeNT and CRESST-II dark matter signals consistently with the null results of the other experiments. This type of dark matter can be captured by the Earth and shield detectors because it is self-interacting. This effect will lead to a diurnal modulation in dark matter detectors. We estimate the size of this effect for dark matter detectors in various locations. For a detector located in the northern hemisphere, this effect is expected to peak in April and can be detected for optimistic parameter choices. The diurnal variation is expected to be much larger for detectors located in the southern hemisphere. In particular, if the CoGeNT detector were moved to e.g. Sierra Grande, Argentina then a 5σ dark matter discovery would be possible in around 30 days of operation

Collider constraints on interactions of dark energy with the standard model

Energy Technology Data Exchange (ETDEWEB)

Brax, P. [CEA, IPhT, CNRS, Gif-sur-Yvette (France). Inst. de Physique Theorique; Burrage, C. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Davis, A.C.; Seery, D. [Cambridge Univ. (United Kingdom). Dept. of Applied Mathematics and Theoretical Physics; Weltman, A. (eds.) [Cambridge Univ. (United Kingdom). Dept. of Applied Mathematics and Theoretical Physics; Cape Town Univ. (South Africa). Dept. of Mathematics and Applied Mathematics

2009-04-15

We study models in which a light scalar dark energy particle couples to the gauge fields of the electroweak force, the photon, Z, and W{sup {+-}} bosons. Our analysis applies to a large class of interacting dark energy models, including those in which the dark energy mass can be adjusted to evade fifth-force bounds by the so-called ''chameleon'' mechanism. We conclude that - with the usual choice of Higgs sector - electroweak precision observables are screened from the indirect effects of dark energy, making such corrections effectively unobservable at present-day colliders, and limiting the dark energy discovery potential of any future International Linear Collider. We show that a similar screening effect applies to processes mediated by flavour-changing neutral currents, which can be traced to the Glashow-Iliopoulos-Maiani mechanism. However, Higgs boson production at the Large Hadron Collider via weak boson fusion may receive observable corrections. (orig.)

Dark group: dark energy and dark matter

International Nuclear Information System (INIS)

Macorra, A. de la

2004-01-01

We study the possibility that a dark group, a gauge group with particles interacting with the standard model particles only via gravity, is responsible for containing the dark energy and dark matter required by present day observations. We show that it is indeed possible and we determine the constrains for the dark group. The non-perturbative effects generated by a strong gauge coupling constant can de determined and a inverse power law scalar potential IPL for the dark meson fields is generated parameterizing the dark energy. On the other hand it is the massive particles, e.g., dark baryons, of the dark gauge group that give the corresponding dark matter. The mass of the dark particles is of the order of the condensation scale Λ c and the temperature is smaller then the photon's temperature. The dark matter is of the warm matter type. The only parameters of the model are the number of particles of the dark group. The allowed values of the different parameters are severely restricted. The dark group energy density at Λ c must be Ω DGc ≤0.17 and the evolution and acceptable values of dark matter and dark energy leads to a constrain of Λ c and the IPL parameter n giving Λ c =O(1-10 3 ) eV and 0.28≤n≤1.04

Interacting polytropic gas model of phantom dark energy in non-flat universe

International Nuclear Information System (INIS)

Karami, K.; Ghaffari, S.; Fehri, J.

2009-01-01

By introducing the polytropic gas model of interacting dark energy, we obtain the equation of state for the polytropic gas energy density in a non-flat universe. We show that for an even polytropic index by choosing K>Ba (3)/(n) , one can obtain ω Λ eff <-1, which corresponds to a universe dominated by phantom dark energy. (orig.)

Light weakly interacting particles. Constraints and connection to dark matter

International Nuclear Information System (INIS)

Andreas, Sarah

2013-07-01

The so far unknown particle nature of dark matter is a main motivation for extending the Standard Model of particle physics. A recently promoted approach to solving this puzzle is the concept of hidden sectors. Since the interactions of such sectors with the visible sector are very weak, so are the current experimental bounds. Hidden sectors might even contain sub-GeV scale particles that have so far escaped detection. In this thesis, we study the phenomenology of Weakly Interacting Slim Particles (WISPs) as well as their connection to dark matter in different Standard Model extensions. In the Next-to-Minimal Supersymmetric Standard Model (NMSSM), a light CPodd Higgs, arising from spontaneous breaking of approximate symmetries, represents an example of a WISP. Light gauge bosons of an extra U(1) symmetry in a hidden sector are other well motivated candidates for WISPs and called hidden photons. Such light hidden photons appear naturally in supersymmetry or string theory and might resolve the observed deviation in the muon anomalous magnetic moment from predictions. Moreover, scenarios in which hidden sector dark matter interacts via a light hidden photon with the visible sector exhibit appealing features in view of recent astrophysical anomalies. We study how the coupling of the CP-odd Higgs A 0 to fermions can be constrained by current measurements for the case where the A 0 is lighter than two muons. Analysing measurements of different rare and radiative meson decays, the muon anomalous magnetic moment as well as results from beam dump and reactor experiments, we severely constrain the CP-odd Higgs to be heavier than 210 MeV or to couple to fermions four orders of magnitude weaker than the Standard Model Higgs. These results apply more generally to the coupling of an axion-like particle to matter. Hidden photons can be constrained by experiments since they couple to charged Standard Model particles via kinetic mixing with the ordinary photon. We derive several

Interaction between a dark spot and a two-dimensional nonlinear photonic lattice with fully incoherent white light

International Nuclear Information System (INIS)

Liu, Zhaohong; Liu, Simin; Guo, Ru; Song, Tao; Zhu, Nan

2007-01-01

We study experimentally the interaction of a dark spot with a nonlinear photonic lattice with fully incoherent white light emitted from an incandescent bulb in the self-defocussing photovoltaic media when the dark spot is aimed at different positions of lattices with different lattice spacing. In this case a host of novel phenomena is demonstrated, including dark spot induced lattice dislocation-deformation, the annihilation of the dark spot and so on. Results demonstrate that the interaction between incoherent dark spot and photonic lattice is always attraction and the large-spacing photonic lattice is analogous to the continuous medium

Interacting entropy-corrected new agegraphic dark energy in the non-flat universe

Energy Technology Data Exchange (ETDEWEB)

Karami, Kayoomars [Department of Physics, University of Kurdistan, Pasdaran Street, Sanandaj (Iran, Islamic Republic of); Sorouri, Arash, E-mail: KKarami@uok.ac.i [Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of)

2010-08-15

Here, we consider the entropy-corrected version of the new agegraphic dark energy (NADE) model in the non-flat Friedmann-Robertson-Walker universe. We derive the exact differential equation that determines the evolution of the entropy-corrected NADE density parameter in the presence of interaction with dark matter. We also obtain the equation of state and deceleration parameters and present a necessary condition for the selected model to cross the phantom divide. Moreover, we reconstruct the potential and the dynamics of the phantom scalar field according to the evolutionary behavior of the interacting entropy-corrected new agegraphic model.

Interacting dark sector and the coincidence problem within the scope of LRS Bianchi type I model

Science.gov (United States)

Muharlyamov, Ruslan K.; Pankratyeva, Tatiana N.

2018-05-01

It is shown that a suitable interaction between dark energy and dark matter in locally rotationally symmetric (LRS) Bianchi-I space-time can solve the coincidence problem and not contradict the accelerated expansion of present Universe. The interaction parameters are estimated from observational data.

Dark Energy after GW170817 and GRB170817A

Science.gov (United States)

Creminelli, Paolo; Vernizzi, Filippo

2017-12-01

The observation of GW170817 and its electromagnetic counterpart implies that gravitational waves travel at the speed of light, with deviations smaller than a few ×10-15 . We discuss the consequences of this experimental result for models of dark energy and modified gravity characterized by a single scalar degree of freedom. To avoid tuning, the speed of gravitational waves must be unaffected not only for our particular cosmological solution but also for nearby solutions obtained by slightly changing the matter abundance. For this to happen, the coefficients of various operators must satisfy precise relations that we discuss both in the language of the effective field theory of dark energy and in the covariant one, for Horndeski, beyond Horndeski, and degenerate higher-order theories. The simplification is dramatic: of the three functions describing quartic and quintic beyond Horndeski theories, only one remains and reduces to a standard conformal coupling to the Ricci scalar for Horndeski theories. We show that the deduced relations among operators do not introduce further tuning of the models, since they are stable under quantum corrections.

Dark Energy after GW170817 and GRB170817A.

Science.gov (United States)

Creminelli, Paolo; Vernizzi, Filippo

2017-12-22

The observation of GW170817 and its electromagnetic counterpart implies that gravitational waves travel at the speed of light, with deviations smaller than a few×10^{-15}. We discuss the consequences of this experimental result for models of dark energy and modified gravity characterized by a single scalar degree of freedom. To avoid tuning, the speed of gravitational waves must be unaffected not only for our particular cosmological solution but also for nearby solutions obtained by slightly changing the matter abundance. For this to happen, the coefficients of various operators must satisfy precise relations that we discuss both in the language of the effective field theory of dark energy and in the covariant one, for Horndeski, beyond Horndeski, and degenerate higher-order theories. The simplification is dramatic: of the three functions describing quartic and quintic beyond Horndeski theories, only one remains and reduces to a standard conformal coupling to the Ricci scalar for Horndeski theories. We show that the deduced relations among operators do not introduce further tuning of the models, since they are stable under quantum corrections.

Dark coupling

International Nuclear Information System (INIS)

Gavela, M.B.; Hernández, D.; Honorez, L. Lopez; Mena, O.; Rigolin, S.

2009-01-01

The two dark sectors of the universe—dark matter and dark energy—may interact with each other. Background and linear density perturbation evolution equations are developed for a generic coupling. We then establish the general conditions necessary to obtain models free from non-adiabatic instabilities. As an application, we consider a viable universe in which the interaction strength is proportional to the dark energy density. The scenario does not exhibit ''phantom crossing'' and is free from instabilities, including early ones. A sizeable interaction strength is compatible with combined WMAP, HST, SN, LSS and H(z) data. Neutrino mass and/or cosmic curvature are allowed to be larger than in non-interacting models. Our analysis sheds light as well on unstable scenarios previously proposed

AIC, BIC, Bayesian evidence against the interacting dark energy model

International Nuclear Information System (INIS)

Szydlowski, Marek; Krawiec, Adam; Kurek, Aleksandra; Kamionka, Michal

2015-01-01

Recent astronomical observations have indicated that the Universe is in a phase of accelerated expansion. While there are many cosmological models which try to explain this phenomenon, we focus on the interacting ΛCDM model where an interaction between the dark energy and dark matter sectors takes place. This model is compared to its simpler alternative - the ΛCDM model. To choose between these models the likelihood ratio test was applied as well as the model comparison methods (employing Occam's principle): the Akaike information criterion (AIC), the Bayesian information criterion (BIC) and the Bayesian evidence. Using the current astronomical data: type Ia supernova (Union2.1), h(z), baryon acoustic oscillation, the Alcock- Paczynski test, and the cosmic microwave background data, we evaluated both models. The analyses based on the AIC indicated that there is less support for the interacting ΛCDM model when compared to the ΛCDM model, while those based on the BIC indicated that there is strong evidence against it in favor of the ΛCDM model. Given the weak or almost non-existing support for the interacting ΛCDM model and bearing in mind Occam's razor we are inclined to reject this model. (orig.)

Updated constraints on self-interacting dark matter from Supernova 1987A

Science.gov (United States)

Mahoney, Cameron; Leibovich, Adam K.; Zentner, Andrew R.

2017-08-01

We revisit SN1987A constraints on light, hidden sector gauge bosons ("dark photons") that are coupled to the standard model through kinetic mixing with the photon. These constraints are realized because excessive bremsstrahlung radiation of the dark photon can lead to rapid cooling of the SN1987A progenitor core, in contradiction to the observed neutrinos from that event. The models we consider are of interest as phenomenological models of strongly self-interacting dark matter. We clarify several possible ambiguities in the literature and identify errors in prior analyses. We find constraints on the dark photon mixing parameter that are in rough agreement with the early estimates of Dent et al. [arXiv:1201.2683.], but only because significant errors in their analyses fortuitously canceled. Our constraints are in good agreement with subsequent analyses by Rrapaj & Reddy [Phys. Rev. C 94, 045805 (2016)., 10.1103/PhysRevC.94.045805] and Hardy & Lasenby [J. High Energy Phys. 02 (2017) 33., 10.1007/JHEP02(2017)033]. We estimate the dark photon bremsstrahlung rate using one-pion exchange (OPE), while Rrapaj & Reddy use a soft radiation approximation (SRA) to exploit measured nuclear scattering cross sections. We find that the differences between mixing parameter constraints obtained through the OPE approximation or the SRA approximation are roughly a factor of ˜2 - 3 . Hardy & Laseby [J. High Energy Phys. 02 (2017) 33., 10.1007/JHEP02(2017)033] include plasma effects in their calculations finding significantly weaker constraints on dark photon mixing for dark photon masses below ˜10 MeV . We do not consider plasma effects. Lastly, we point out that the properties of the SN1987A progenitor core remain somewhat uncertain and that this uncertainty alone causes uncertainty of at least a factor of ˜2 - 3 in the excluded values of the dark photon mixing parameter. Further refinement of these estimates is unwarranted until either the interior of the SN1987A progenitor is

Probing velocity dependent self-interacting dark matter with neutrino telescopes

Science.gov (United States)

Robertson, Denis S.; Albuquerque, Ivone F. M.

2018-02-01

Self-interacting dark matter models constitute an attractive solution to problems in structure formation on small scales. A simple realization of these models considers the dark force mediated by a light particle which can couple to the Standard Model through mixings with the photon or the Z boson. Within this scenario we investigate the sensitivity of the IceCube-DeepCore and PINGU neutrino telescopes to the associated muon neutrino flux produced by dark matter annihilations in the Sun. Despite the model's simplicity, several effects naturally appear: momentum suppressed capture by nuclei, velocity dependent dark matter self-capture, Sommerfeld enhanced annihilation, as well as the enhancement on the neutrino flux due to mediator late decays. Taking all these effects into account, we find that most of the model relevant parameter space can be tested by the three years of data already collected by the IceCube-DeepCore. We show that indirect detection through neutrinos can compete with the strong existing limits from direct detection experiments, specially in the case of isospin violation.

Light weakly interacting particles. Constraints and connection to dark matter

Energy Technology Data Exchange (ETDEWEB)

Andreas, Sarah

2013-07-15

The so far unknown particle nature of dark matter is a main motivation for extending the Standard Model of particle physics. A recently promoted approach to solving this puzzle is the concept of hidden sectors. Since the interactions of such sectors with the visible sector are very weak, so are the current experimental bounds. Hidden sectors might even contain sub-GeV scale particles that have so far escaped detection. In this thesis, we study the phenomenology of Weakly Interacting Slim Particles (WISPs) as well as their connection to dark matter in different Standard Model extensions. In the Next-to-Minimal Supersymmetric Standard Model (NMSSM), a light CPodd Higgs, arising from spontaneous breaking of approximate symmetries, represents an example of a WISP. Light gauge bosons of an extra U(1) symmetry in a hidden sector are other well motivated candidates for WISPs and called hidden photons. Such light hidden photons appear naturally in supersymmetry or string theory and might resolve the observed deviation in the muon anomalous magnetic moment from predictions. Moreover, scenarios in which hidden sector dark matter interacts via a light hidden photon with the visible sector exhibit appealing features in view of recent astrophysical anomalies. We study how the coupling of the CP-odd Higgs A{sup 0} to fermions can be constrained by current measurements for the case where the A{sup 0} is lighter than two muons. Analysing measurements of different rare and radiative meson decays, the muon anomalous magnetic moment as well as results from beam dump and reactor experiments, we severely constrain the CP-odd Higgs to be heavier than 210 MeV or to couple to fermions four orders of magnitude weaker than the Standard Model Higgs. These results apply more generally to the coupling of an axion-like particle to matter. Hidden photons can be constrained by experiments since they couple to charged Standard Model particles via kinetic mixing with the ordinary photon. We derive

Radiative bound-state-formation cross-sections for dark matter interacting via a Yukawa potential

Energy Technology Data Exchange (ETDEWEB)

Petraki, Kalliopi [LPTHE, CNRS, UMR 7589,4 Place Jussieu, F-75252, Paris (France); Nikhef,Science Park 105, 1098 XG Amsterdam (Netherlands); Postma, Marieke; Vries, Jordy de [Nikhef,Science Park 105, 1098 XG Amsterdam (Netherlands)

2017-04-13

We calculate the cross-sections for the radiative formation of bound states by dark matter whose interactions are described in the non-relativistic regime by a Yukawa potential. These cross-sections are important for cosmological and phenomenological studies of dark matter with long-range interactions, residing in a hidden sector, as well as for TeV-scale WIMP dark matter. We provide the leading-order contributions to the cross-sections for the dominant capture processes occurring via emission of a vector or a scalar boson. We offer a detailed inspection of their features, including their velocity dependence within and outside the Coulomb regime, and their resonance structure. For pairs of annihilating particles, we compare bound-state formation with annihilation.

Interacting Quintessence Dark Energy Models in Lyra Manifold

International Nuclear Information System (INIS)

Khurshudyan, M.; Myrzakulov, R.; Sadeghi, J.; Farahani, H.; Pasqua, Antonio

2014-01-01

We consider two-component dark energy models in Lyra manifold. The first component is assumed to be a quintessence field while the second component may be a viscous polytropic gas, a viscous Van der Waals gas, or a viscous modified Chaplygin gas. We also consider the possibility of interaction between components. By using the numerical analysis, we study some cosmological parameters of the models and compare them with observational data.

Dark stars

DEFF Research Database (Denmark)

Maselli, Andrea; Pnigouras, Pantelis; Nielsen, Niklas Grønlund

2017-01-01

to the formation of compact objects predominantly made of dark matter. Considering both fermionic and bosonic (scalar φ4) equations of state, we construct the equilibrium structure of rotating dark stars, focusing on their bulk properties and comparing them with baryonic neutron stars. We also show that these dark......Theoretical models of self-interacting dark matter represent a promising answer to a series of open problems within the so-called collisionless cold dark matter paradigm. In case of asymmetric dark matter, self-interactions might facilitate gravitational collapse and potentially lead...... objects admit the I-Love-Q universal relations, which link their moments of inertia, tidal deformabilities, and quadrupole moments. Finally, we prove that stars built with a dark matter equation of state are not compact enough to mimic black holes in general relativity, thus making them distinguishable...

Superweakly interacting massive particle dark matter signals from the early Universe

International Nuclear Information System (INIS)

Feng, Jonathan L.; Rajaraman, Arvind; Takayama, Fumihiro

2003-01-01

Cold dark matter may be made of superweakly interacting massive particles, super-WIMP's, that naturally inherit the desired relic density from late decays of metastable WIMP's. Well-motivated examples are weak-scale gravitinos in supergravity and Kaluza-Klein gravitons from extra dimensions. These particles are impossible to detect in all dark matter experiments. We find, however, that super-WIMP dark matter may be discovered through cosmological signatures from the early Universe. In particular, super-WIMP dark matter has observable consequences for big bang nucleosynthesis and the cosmic microwave background (CMB), and may explain the observed underabundance of 7 Li without upsetting the concordance between deuterium and CMB baryometers. We discuss the implications for future probes of CMB blackbody distortions and collider searches for new particles. In the course of this study, we also present a model-independent analysis of entropy production from late-decaying particles in light of Wilkinson microwave anisotropy probe data

Dark matter self-interactions and small scale structure

Science.gov (United States)

Tulin, Sean; Yu, Hai-Bo

2018-02-01

We review theories of dark matter (DM) beyond the collisionless paradigm, known as self-interacting dark matter (SIDM), and their observable implications for astrophysical structure in the Universe. Self-interactions are motivated, in part, due to the potential to explain long-standing (and more recent) small scale structure observations that are in tension with collisionless cold DM (CDM) predictions. Simple particle physics models for SIDM can provide a universal explanation for these observations across a wide range of mass scales spanning dwarf galaxies, low and high surface brightness spiral galaxies, and clusters of galaxies. At the same time, SIDM leaves intact the success of ΛCDM cosmology on large scales. This report covers the following topics: (1) small scale structure issues, including the core-cusp problem, the diversity problem for rotation curves, the missing satellites problem, and the too-big-to-fail problem, as well as recent progress in hydrodynamical simulations of galaxy formation; (2) N-body simulations for SIDM, including implications for density profiles, halo shapes, substructure, and the interplay between baryons and self-interactions; (3) semi-analytic Jeans-based methods that provide a complementary approach for connecting particle models with observations; (4) merging systems, such as cluster mergers (e.g., the Bullet Cluster) and minor infalls, along with recent simulation results for mergers; (5) particle physics models, including light mediator models and composite DM models; and (6) complementary probes for SIDM, including indirect and direct detection experiments, particle collider searches, and cosmological observations. We provide a summary and critical look for all current constraints on DM self-interactions and an outline for future directions.

Dark matter and dark radiation

International Nuclear Information System (INIS)

Ackerman, Lotty; Buckley, Matthew R.; Carroll, Sean M.; Kamionkowski, Marc

2009-01-01

We explore the feasibility and astrophysical consequences of a new long-range U(1) gauge field ('dark electromagnetism') that couples only to dark matter, not to the standard model. The dark matter consists of an equal number of positive and negative charges under the new force, but annihilations are suppressed if the dark-matter mass is sufficiently high and the dark fine-structure constant α-circumflex is sufficiently small. The correct relic abundance can be obtained if the dark matter also couples to the conventional weak interactions, and we verify that this is consistent with particle-physics constraints. The primary limit on α-circumflex comes from the demand that the dark matter be effectively collisionless in galactic dynamics, which implies α-circumflex -3 for TeV-scale dark matter. These values are easily compatible with constraints from structure formation and primordial nucleosynthesis. We raise the prospect of interesting new plasma effects in dark-matter dynamics, which remain to be explored.

AIC, BIC, Bayesian evidence against the interacting dark energy model

Energy Technology Data Exchange (ETDEWEB)

Szydlowski, Marek [Jagiellonian University, Astronomical Observatory, Krakow (Poland); Jagiellonian University, Mark Kac Complex Systems Research Centre, Krakow (Poland); Krawiec, Adam [Jagiellonian University, Institute of Economics, Finance and Management, Krakow (Poland); Jagiellonian University, Mark Kac Complex Systems Research Centre, Krakow (Poland); Kurek, Aleksandra [Jagiellonian University, Astronomical Observatory, Krakow (Poland); Kamionka, Michal [University of Wroclaw, Astronomical Institute, Wroclaw (Poland)

2015-01-01

Recent astronomical observations have indicated that the Universe is in a phase of accelerated expansion. While there are many cosmological models which try to explain this phenomenon, we focus on the interacting ΛCDM model where an interaction between the dark energy and dark matter sectors takes place. This model is compared to its simpler alternative - the ΛCDM model. To choose between these models the likelihood ratio test was applied as well as the model comparison methods (employing Occam's principle): the Akaike information criterion (AIC), the Bayesian information criterion (BIC) and the Bayesian evidence. Using the current astronomical data: type Ia supernova (Union2.1), h(z), baryon acoustic oscillation, the Alcock- Paczynski test, and the cosmic microwave background data, we evaluated both models. The analyses based on the AIC indicated that there is less support for the interacting ΛCDM model when compared to the ΛCDM model, while those based on the BIC indicated that there is strong evidence against it in favor of the ΛCDM model. Given the weak or almost non-existing support for the interacting ΛCDM model and bearing in mind Occam's razor we are inclined to reject this model. (orig.)

AIC, BIC, Bayesian evidence against the interacting dark energy model

Energy Technology Data Exchange (ETDEWEB)

Szydłowski, Marek, E-mail: marek.szydlowski@uj.edu.pl [Astronomical Observatory, Jagiellonian University, Orla 171, 30-244, Kraków (Poland); Mark Kac Complex Systems Research Centre, Jagiellonian University, Reymonta 4, 30-059, Kraków (Poland); Krawiec, Adam, E-mail: adam.krawiec@uj.edu.pl [Institute of Economics, Finance and Management, Jagiellonian University, Łojasiewicza 4, 30-348, Kraków (Poland); Mark Kac Complex Systems Research Centre, Jagiellonian University, Reymonta 4, 30-059, Kraków (Poland); Kurek, Aleksandra, E-mail: alex@oa.uj.edu.pl [Astronomical Observatory, Jagiellonian University, Orla 171, 30-244, Kraków (Poland); Kamionka, Michał, E-mail: kamionka@astro.uni.wroc.pl [Astronomical Institute, University of Wrocław, ul. Kopernika 11, 51-622, Wrocław (Poland)

2015-01-14

Recent astronomical observations have indicated that the Universe is in a phase of accelerated expansion. While there are many cosmological models which try to explain this phenomenon, we focus on the interacting ΛCDM model where an interaction between the dark energy and dark matter sectors takes place. This model is compared to its simpler alternative—the ΛCDM model. To choose between these models the likelihood ratio test was applied as well as the model comparison methods (employing Occam’s principle): the Akaike information criterion (AIC), the Bayesian information criterion (BIC) and the Bayesian evidence. Using the current astronomical data: type Ia supernova (Union2.1), h(z), baryon acoustic oscillation, the Alcock–Paczynski test, and the cosmic microwave background data, we evaluated both models. The analyses based on the AIC indicated that there is less support for the interacting ΛCDM model when compared to the ΛCDM model, while those based on the BIC indicated that there is strong evidence against it in favor of the ΛCDM model. Given the weak or almost non-existing support for the interacting ΛCDM model and bearing in mind Occam’s razor we are inclined to reject this model.

arXiv Signatures of Dark Radiation in Neutrino and Dark Matter Detectors

CERN Document Server

Cui, Yanou; Pradler, Josef

2018-05-03

We consider the generic possibility that the Universe’s energy budget includes some form of relativistic or semi-relativistic dark radiation (DR) with nongravitational interactions with standard model (SM) particles. Such dark radiation may consist of SM singlets or a nonthermal, energetic component of neutrinos. If such DR is created at a relatively recent epoch, it can carry sufficient energy to leave a detectable imprint in experiments designed to search for very weakly interacting particles: dark matter and underground neutrino experiments. We analyze this possibility in some generality, assuming that the interactive dark radiation is sourced by late decays of an unstable particle, potentially a component of dark matter, and considering a variety of possible interactions between the dark radiation and SM particles. Concentrating on the sub-GeV energy region, we derive constraints on different forms of DR using the results of the most sensitive neutrino and dark matter direct detection experiments. In pa...

arXiv Signatures of Dark Radiation in Neutrino and Dark Matter Detectors

CERN Document Server

Cui, Yanou; Pradler, Josef

We consider the generic possibility that the Universe's energy budget includes some form of relativistic or semi-relativistic dark radiation (DR) with non-gravitational interactions with Standard Model (SM) particles. Such dark radiation may consist of SM singlets or a non-thermal, energetic component of neutrinos. If such DR is created at a relatively recent epoch, it can carry sufficient energy to leave a detectable imprint in experiments designed to search for very weakly interacting particles: dark matter and underground neutrino experiments. We analyze this possibility in some generality, assuming that the interactive dark radiation is sourced by late decays of an unstable particle, potentially a component of dark matter, and considering a variety of possible interactions between the dark radiation and SM particles. Concentrating on the sub-GeV energy region, we derive constraints on different forms of DR using the results of the most sensitive neutrino and dark matter direct detection experiments. In pa...

Effects of time-varying β in SNLS3 on constraining interacting dark energy models

International Nuclear Information System (INIS)

Wang, Shuang; Wang, Yong-Zhen; Geng, Jia-Jia; Zhang, Xin

2014-01-01

It has been found that, for the Supernova Legacy Survey three-year (SNLS3) data, there is strong evidence for the redshift evolution of the color-luminosity parameter β. In this paper, adopting the w-cold-dark-matter (wCDM) model and considering its interacting extensions (with three kinds of interaction between dark sectors), we explore the evolution of β and its effects on parameter estimation. In addition to the SNLS3 data, we also use the latest Planck distance priors data, the galaxy clustering data extracted from sloan digital sky survey data release 7 and baryon oscillation spectroscopic survey, as well as the direct measurement of Hubble constant H 0 from the Hubble Space Telescope observation. We find that, for all the interacting dark energy (IDE) models, adding a parameter of β can reduce χ 2 by ∝34, indicating that a constant β is ruled out at 5.8σ confidence level. Furthermore, it is found that varying β can significantly change the fitting results of various cosmological parameters: for all the dark energy models considered in this paper, varying β yields a larger fractional CDM densities Ω c0 and a larger equation of state w; on the other side, varying β yields a smaller reduced Hubble constant h for the wCDM model, but it has no impact on h for the three IDE models. This implies that there is a degeneracy between h and coupling parameter γ. Our work shows that the evolution of β is insensitive to the interaction between dark sectors, and then highlights the importance of considering β's evolution in the cosmology fits. (orig.)

Metastable dark energy

Directory of Open Access Journals (Sweden)

Ricardo G. Landim

2017-01-01

Full Text Available We build a model of metastable dark energy, in which the observed vacuum energy is the value of the scalar potential at the false vacuum. The scalar potential is given by a sum of even self-interactions up to order six. The deviation from the Minkowski vacuum is due to a term suppressed by the Planck scale. The decay time of the metastable vacuum can easily accommodate a mean life time compatible with the age of the universe. The metastable dark energy is also embedded into a model with SU(2R symmetry. The dark energy doublet and the dark matter doublet naturally interact with each other. A three-body decay of the dark energy particle into (cold and warm dark matter can be as long as large fraction of the age of the universe, if the mediator is massive enough, the lower bound being at intermediate energy level some orders below the grand unification scale. Such a decay shows a different form of interaction between dark matter and dark energy, and the model opens a new window to investigate the dark sector from the point-of-view of particle physics.

Possible interaction between baryons and dark-matter particles revealed by the first stars

Science.gov (United States)

Barkana, Rennan

2018-03-01

The cosmic radio-frequency spectrum is expected to show a strong absorption signal corresponding to the 21-centimetre-wavelength transition of atomic hydrogen around redshift 20, which arises from Lyman-α radiation from some of the earliest stars. By observing this 21-centimetre signal—either its sky-averaged spectrum or maps of its fluctuations, obtained using radio interferometers—we can obtain information about cosmic dawn, the era when the first astrophysical sources of light were formed. The recent detection of the global 21-centimetre spectrum reveals a stronger absorption than the maximum predicted by existing models, at a confidence level of 3.8 standard deviations. Here we report that this absorption can be explained by the combination of radiation from the first stars and excess cooling of the cosmic gas induced by its interaction with dark matter. Our analysis indicates that the spatial fluctuations of the 21-centimetre signal at cosmic dawn could be an order of magnitude larger than previously expected and that the dark-matter particle is no heavier than several proton masses, well below the commonly predicted mass of weakly interacting massive particles. Our analysis also confirms that dark matter is highly non-relativistic and at least moderately cold, and primordial velocities predicted by models of warm dark matter are potentially detectable. These results indicate that 21-centimetre cosmology can be used as a dark-matter probe.

Possible interaction between baryons and dark-matter particles revealed by the first stars.

Science.gov (United States)

Barkana, Rennan

2018-02-28

The cosmic radio-frequency spectrum is expected to show a strong absorption signal corresponding to the 21-centimetre-wavelength transition of atomic hydrogen around redshift 20, which arises from Lyman-α radiation from some of the earliest stars. By observing this 21-centimetre signal-either its sky-averaged spectrum or maps of its fluctuations, obtained using radio interferometers-we can obtain information about cosmic dawn, the era when the first astrophysical sources of light were formed. The recent detection of the global 21-centimetre spectrum reveals a stronger absorption than the maximum predicted by existing models, at a confidence level of 3.8 standard deviations. Here we report that this absorption can be explained by the combination of radiation from the first stars and excess cooling of the cosmic gas induced by its interaction with dark matter. Our analysis indicates that the spatial fluctuations of the 21-centimetre signal at cosmic dawn could be an order of magnitude larger than previously expected and that the dark-matter particle is no heavier than several proton masses, well below the commonly predicted mass of weakly interacting massive particles. Our analysis also confirms that dark matter is highly non-relativistic and at least moderately cold, and primordial velocities predicted by models of warm dark matter are potentially detectable. These results indicate that 21-centimetre cosmology can be used as a dark-matter probe.

Constraints on the interaction between dark matter and Baryons from cooling flow clusters.

Science.gov (United States)

Qin, B; Wu, X P

2001-08-06

Other nongravitational heating processes are needed to resolve the disagreement between the absence of cool gas components in the centers of galaxy clusters revealed recently by Chandra and XMM observations and the expectations of conventional radiative cooling models. We propose that the interaction between dark matter and baryonic matter may act as an alternative for the reheating of intracluster medium (ICM) in the inner regions of clusters, in which kinetic energy of dark matter is transported to ICM to balance radiative cooling. Using the Chandra and XMM data, we set a useful constraint on the dark-matter-baryon cross section: sigma(xp)/m(x) approximately 1x10(-25) cm(2) GeV-1, where m(x) is the mass of dark matter particles.

Gravitational wave from dark sector with dark pion

Energy Technology Data Exchange (ETDEWEB)

Tsumura, Koji [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Yamada, Masatoshi [Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany); Yamaguchi, Yuya, E-mail: ko2@gauge.scphys.kyoto-u.ac.jp, E-mail: m.yamada@thphys.uni-heidelberg.de, E-mail: yy@particle.sci.hokudai.ac.jp [Department of Physics, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan)

2017-07-01

In this work, we investigate the spectra of gravitational waves produced by chiral symmetry breaking in dark quantum chromodynamics (dQCD) sector. The dark pion (π) can be a dark matter candidate as weakly interacting massive particle (WIMP) or strongly interacting massive particle (SIMP). For a WIMP scenario, we introduce the dQCD sector coupled to the standard model (SM) sector with classical scale invariance and investigate the annihilation process of the dark pion via the 2π → 2 SM process. For a SIMP scenario, we investigate the 3π → 2π annihilation process of the dark pion as a SIMP using chiral perturbation theory. We find that in the WIMP scenario the gravitational wave background spectra can be observed by future space gravitational wave antennas. On the other hand, when the dark pion is the SIMP dark matter with the constraints for the chiral perturbative limit and pion-pion scattering cross section, the chiral phase transition becomes crossover and then the gravitational waves are not produced.

Constraining early and interacting dark energy with gravitational wave standard sirens: the potential of the eLISA mission

International Nuclear Information System (INIS)

Caprini, Chiara; Tamanini, Nicola

2016-01-01

We perform a forecast analysis of the capability of the eLISA space-based interferometer to constrain models of early and interacting dark energy using gravitational wave standard sirens. We employ simulated catalogues of standard sirens given by merging massive black hole binaries visible by eLISA, with an electromagnetic counterpart detectable by future telescopes. We consider three-arms mission designs with arm length of 1, 2 and 5 million km, 5 years of mission duration and the best-level low frequency noise as recently tested by the LISA Pathfinder. Standard sirens with eLISA give access to an intermediate range of redshift 1 ∼< z ∼< 8, and can therefore provide competitive constraints on models where the onset of the deviation from ΛCDM (i.e. the epoch when early dark energy starts to be non-negligible, or when the interaction with dark matter begins) occurs relatively late, at z ∼< 6. If instead early or interacting dark energy is relevant already in the pre-recombination era, current cosmological probes (especially the cosmic microwave background) are more efficient than eLISA in constraining these models, except possibly in the interacting dark energy model if the energy exchange is proportional to the energy density of dark energy.

Probes for dark matter physics

Science.gov (United States)

Khlopov, Maxim Yu.

The existence of cosmological dark matter is in the bedrock of the modern cosmology. The dark matter is assumed to be nonbaryonic and consists of new stable particles. Weakly Interacting Massive Particle (WIMP) miracle appeals to search for neutral stable weakly interacting particles in underground experiments by their nuclear recoil and at colliders by missing energy and momentum, which they carry out. However, the lack of WIMP effects in their direct underground searches and at colliders can appeal to other forms of dark matter candidates. These candidates may be weakly interacting slim particles, superweakly interacting particles, or composite dark matter, in which new particles are bound. Their existence should lead to cosmological effects that can find probes in the astrophysical data. However, if composite dark matter contains stable electrically charged leptons and quarks bound by ordinary Coulomb interaction in elusive dark atoms, these charged constituents of dark atoms can be the subject of direct experimental test at the colliders. The models, predicting stable particles with charge ‑ 2 without stable particles with charges + 1 and ‑ 1 can avoid severe constraints on anomalous isotopes of light elements and provide solution for the puzzles of dark matter searches. In such models, the excessive ‑ 2 charged particles are bound with primordial helium in O-helium atoms, maintaining specific nuclear-interacting form of the dark matter. The successful development of composite dark matter scenarios appeals for experimental search for doubly charged constituents of dark atoms, making experimental search for exotic stable double charged particles experimentum crucis for dark atoms of composite dark matter.

Dark matter as a weakly coupled dark baryon

Science.gov (United States)

Mitridate, Andrea; Redi, Michele; Smirnov, Juri; Strumia, Alessandro

2017-10-01

Dark Matter might be an accidentally stable baryon of a new confining gauge interaction. We extend previous studies exploring the possibility that the DM is made of dark quarks heavier than the dark confinement scale. The resulting phenomenology contains new unusual elements: a two-stage DM cosmology (freeze-out followed by dark condensation), a large DM annihilation cross section through recombination of dark quarks (allowing to fit the positron excess). Light dark glue-balls are relatively long lived and give extra cosmological effects; DM itself can remain radioactive.

Is dark matter with long-range interactions a solution to all small-scale problems of Λ cold dark matter cosmology?

Science.gov (United States)

van den Aarssen, Laura G; Bringmann, Torsten; Pfrommer, Christoph

2012-12-07

The cold dark matter paradigm describes the large-scale structure of the Universe remarkably well. However, there exists some tension with the observed abundances and internal density structures of both field dwarf galaxies and galactic satellites. Here, we demonstrate that a simple class of dark matter models may offer a viable solution to all of these problems simultaneously. Their key phenomenological properties are velocity-dependent self-interactions mediated by a light vector messenger and thermal production with much later kinetic decoupling than in the standard case.

Higgs particles interacting via a scalar Dark Matter field

Directory of Open Access Journals (Sweden)

Bhattacharya Yajnavalkya

2016-01-01

Full Text Available We study a system of two Higgs particles, interacting via a scalar Dark Matter mediating field. The variational method in the Hamiltonian formalism of QFT is used to derive relativistic wave equations for the two-Higgs system, using a truncated Fock-space trial state. Approximate solutions of the two-body equations are used to examine the existence of Higgs bound states.

Direct detection signatures of self-interacting dark matter with a light mediator

International Nuclear Information System (INIS)

Nobile, Eugenio Del; Kaplinghat, Manoj; Yu, Hai-Bo

2015-01-01

Self-interacting dark matter (SIDM) is a simple and well-motivated scenario that could explain long-standing puzzles in structure formation on small scales. If the required self-interaction arises through a light mediator (with mass ∼ 10 MeV) in the dark sector, this new particle must be unstable to avoid overclosing the universe. The decay of the light mediator could happen due to a weak coupling of the hidden and visible sectors, providing new signatures for direct detection experiments. The SIDM nuclear recoil spectrum is more peaked towards low energies compared to the usual case of contact interactions, because the mediator mass is comparable to the momentum transfer of nuclear recoils. We show that the SIDM signal could be distinguished from that of DM particles with contact interactions by considering the time-average energy spectrum in experiments employing different target materials, or the average and modulated spectra in a single experiment. Using current limits from LUX and SuperCDMS, we also derive strong bounds on the mixing parameter between hidden and visible sector

How CMB and large-scale structure constrain chameleon interacting dark energy

International Nuclear Information System (INIS)

Boriero, Daniel; Das, Subinoy; Wong, Yvonne Y.Y.

2015-01-01

We explore a chameleon type of interacting dark matter-dark energy scenario in which a scalar field adiabatically traces the minimum of an effective potential sourced by the dark matter density. We discuss extensively the effect of this coupling on cosmological observables, especially the parameter degeneracies expected to arise between the model parameters and other cosmological parameters, and then test the model against observations of the cosmic microwave background (CMB) anisotropies and other cosmological probes. We find that the chameleon parameters α and β, which determine respectively the slope of the scalar field potential and the dark matter-dark energy coupling strength, can be constrained to α < 0.17 and β < 0.19 using CMB data and measurements of baryon acoustic oscillations. The latter parameter in particular is constrained only by the late Integrated Sachs-Wolfe effect. Adding measurements of the local Hubble expansion rate H 0 tightens the bound on α by a factor of two, although this apparent improvement is arguably an artefact of the tension between the local measurement and the H 0 value inferred from Planck data in the minimal ΛCDM model. The same argument also precludes chameleon models from mimicking a dark radiation component, despite a passing similarity between the two scenarios in that they both delay the epoch of matter-radiation equality. Based on the derived parameter constraints, we discuss possible signatures of the model for ongoing and future large-scale structure surveys

How CMB and large-scale structure constrain chameleon interacting dark energy

Energy Technology Data Exchange (ETDEWEB)

Boriero, Daniel [Fakultät für Physik, Universität Bielefeld, Universitätstr. 25, Bielefeld (Germany); Das, Subinoy [Indian Institute of Astrophisics, Bangalore, 560034 (India); Wong, Yvonne Y.Y., E-mail: boriero@physik.uni-bielefeld.de, E-mail: subinoy@iiap.res.in, E-mail: yvonne.y.wong@unsw.edu.au [School of Physics, The University of New South Wales, Sydney NSW 2052 (Australia)

2015-07-01

We explore a chameleon type of interacting dark matter-dark energy scenario in which a scalar field adiabatically traces the minimum of an effective potential sourced by the dark matter density. We discuss extensively the effect of this coupling on cosmological observables, especially the parameter degeneracies expected to arise between the model parameters and other cosmological parameters, and then test the model against observations of the cosmic microwave background (CMB) anisotropies and other cosmological probes. We find that the chameleon parameters α and β, which determine respectively the slope of the scalar field potential and the dark matter-dark energy coupling strength, can be constrained to α < 0.17 and β < 0.19 using CMB data and measurements of baryon acoustic oscillations. The latter parameter in particular is constrained only by the late Integrated Sachs-Wolfe effect. Adding measurements of the local Hubble expansion rate H{sub 0} tightens the bound on α by a factor of two, although this apparent improvement is arguably an artefact of the tension between the local measurement and the H{sub 0} value inferred from Planck data in the minimal ΛCDM model. The same argument also precludes chameleon models from mimicking a dark radiation component, despite a passing similarity between the two scenarios in that they both delay the epoch of matter-radiation equality. Based on the derived parameter constraints, we discuss possible signatures of the model for ongoing and future large-scale structure surveys.

Classification of effective operators for interactions between the Standard Model and dark matter

International Nuclear Information System (INIS)

Duch, M.; Grzadkowski, B.; Wudka, J.

2015-01-01

We construct a basis for effective operators responsible for interactions between the Standard Model and a dark sector composed of particles with spin ≤1. Redundant operators are eliminated using dim-4 equations of motion. We consider simple scenarios where the dark matter components are stabilized against decay by ℤ_2 symmetries. We determine operators which are loop-generated within an underlying theory and those that are potentially tree-level generated.

Emergence of running dark energy from polynomial f( R) theory in Palatini formalism

Science.gov (United States)

Szydłowski, Marek; Stachowski, Aleksander; Borowiec, Andrzej

2017-09-01

We consider FRW cosmology in f(R)= R+ γ R^2+δ R^3 modified framework. The Palatini approach reduces its dynamics to the simple generalization of Friedmann equation. Thus we study the dynamics in two-dimensional phase space with some details. After reformulation of the model in the Einstein frame, it reduces to the FRW cosmological model with a homogeneous scalar field and vanishing kinetic energy term. This potential determines the running cosmological constant term as a function of the Ricci scalar. As a result we obtain the emergent dark energy parametrization from the covariant theory. We study also singularities of the model and demonstrate that in the Einstein frame some undesirable singularities disappear.

Emergence of running dark energy from polynomial f(R) theory in Palatini formalism

Energy Technology Data Exchange (ETDEWEB)

Szydlowski, Marek [Jagiellonian University, Astronomical Observatory, Krakow (Poland); Jagiellonian University, Mark Kac Complex Systems Research Centre, Krakow (Poland); Stachowski, Aleksander [Jagiellonian University, Astronomical Observatory, Krakow (Poland); Borowiec, Andrzej [University of Wroclaw, Institute of Theoretical Physics, Wroclaw (Poland)

2017-09-15

We consider FRW cosmology in f(R)= R + γR{sup 2} + δR{sup 3} modified framework. The Palatini approach reduces its dynamics to the simple generalization of Friedmann equation. Thus we study the dynamics in two-dimensional phase space with some details. After reformulation of the model in the Einstein frame, it reduces to the FRW cosmological model with a homogeneous scalar field and vanishing kinetic energy term. This potential determines the running cosmological constant term as a function of the Ricci scalar. As a result we obtain the emergent dark energy parametrization from the covariant theory. We study also singularities of the model and demonstrate that in the Einstein frame some undesirable singularities disappear. (orig.)

Supplying Dark Energy from Scalar Field Dark Matter

OpenAIRE

Gogberashvili, Merab; Sakharov, Alexander S.

2017-01-01

We consider the hypothesis that dark matter and dark energy consists of ultra-light self-interacting scalar particles. It is found that the Klein-Gordon equation with only two free parameters (mass and self-coupling) on a Schwarzschild background, at the galactic length-scales has the solution which corresponds to Bose-Einstein condensate, behaving as dark matter, while the constant solution at supra-galactic scales can explain dark energy.

Solar neutrinos as a probe of dark matter-neutrino interactions

Energy Technology Data Exchange (ETDEWEB)

Capozzi, Francesco; Vecchi, Luca [Dipartimento di Fisica e Astronomia, Università di Padova, via Marzolo 8, I-35131 Padova (Italy); Shoemaker, Ian M., E-mail: capozzi.12@osu.edu, E-mail: ian.shoemaker@usd.edu, E-mail: vecchi@infn.pd.it [Department of Physics, University of South Dakota, Vermillion, SD 57069 (United States)

2017-07-01

Sterile neutrinos at the eV scale have long been studied in the context of anomalies in short baseline neutrino experiments. Their cosmology can be made compatible with our understanding of the early Universe provided the sterile neutrino sector enjoys a nontrivial dynamics with exotic interactions, possibly providing a link to the Dark Matter (DM) puzzle. Interactions between DM and neutrinos have also been proposed to address the long-standing 'missing satellites' problem in the field of large scale structure formation. Motivated by these considerations, in this paper we discuss realistic scenarios with light steriles coupled to DM . We point out that within this framework active neutrinos acquire an effective coupling to DM that manifests itself as a new matter potential in the propagation within a medium of asymmetric DM . Assuming that at least a small fraction of asymmetric DM has been captured by the Sun, we show that a sizable region of the parameter space of these scenarios can be probed by solar neutrino experiments, especially in the regime of small couplings and light mediators where all other probes become inefficient. In the latter regime these scenarios behave as familiar 3+1 models in all channels except for solar data, where a Solar Dark MSW effect takes place. Solar Dark MSW is characterized by modifications of the most energetic {sup 8}B and CNO neutrinos, whereas the other fluxes remain largely unaffected.

Reconstructing interacting entropy-corrected holographic scalar field models of dark energy in the non-flat universe

Energy Technology Data Exchange (ETDEWEB)

Karami, K; Khaledian, M S [Department of Physics, University of Kurdistan, Pasdaran Street, Sanandaj (Iran, Islamic Republic of); Jamil, Mubasher, E-mail: KKarami@uok.ac.ir, E-mail: MS.Khaledian@uok.ac.ir, E-mail: mjamil@camp.nust.edu.pk [Center for Advanced Mathematics and Physics (CAMP), National University of Sciences and Technology (NUST), Islamabad (Pakistan)

2011-02-15

Here we consider the entropy-corrected version of the holographic dark energy (DE) model in the non-flat universe. We obtain the equation of state parameter in the presence of interaction between DE and dark matter. Moreover, we reconstruct the potential and the dynamics of the quintessence, tachyon, K-essence and dilaton scalar field models according to the evolutionary behavior of the interacting entropy-corrected holographic DE model.

Thermally Generated Gauge Singlet Scalars as Self-Interacting Dark Matter

CERN Document Server

McDonald, J

2002-01-01

We show that a gauge singlet scalar S with a coupling to the Higgs doublet of the form lambda_{S} S^{\\dagger}S H^{\\dagger}H and with the S mass entirely generated by the Higgs expectation value has a thermally generated relic density Omega_{S} \\approx 0.3 if m_{S} \\approx (2.9-10.5)(Omega_{S}/0.3)^{1/5}(h/0.7)^{2/5} MeV for Higgs boson masses in the range 115 GeV to 1 TeV. Remarkably, this is very similar to the range (m_{S} = (6.6-15.4)\\eta^{2/3} MeV) required in order for the self-interaction (\\eta/4)(S^{\\dagger}S)^{2} to account for self-interacting dark matter when \\eta is about 1. The corresponding coupling is lambda_{S} \\approx (2.7 \\times 10^{-10} - 3.6 \\times 10^{-9})(Omega_{S}/0.3)^{2/5}(h/0.7)^{4/5}, implying that such scalars are very weakly coupled to the Standard Model sector. More generally, for the case where the S mass is at least partially due to a bare mass term, if m_{S} \\approx 10 \\eta^{2/3} MeV, corresponding to self-interacting dark matter, then in order not to overpopulate the Universe ...

Dark influences: imprints of dark satellites on dwarf galaxies

NARCIS (Netherlands)

Starkenburg, T. K.; Helmi, A.

Context. In the context of the current Λ cold dark matter cosmological model small dark matter halos are abundant and satellites of dwarf galaxies are expected to be predominantly dark. Since low mass galaxies have smaller baryon fractions, interactions with these satellites may leave particularly

Constraining self-interacting dark matter with scaling laws of observed halo surface densities

Science.gov (United States)

Bondarenko, Kyrylo; Boyarsky, Alexey; Bringmann, Torsten; Sokolenko, Anastasia

2018-04-01

The observed surface densities of dark matter halos are known to follow a simple scaling law, ranging from dwarf galaxies to galaxy clusters, with a weak dependence on their virial mass. Here we point out that this can not only be used to provide a method to determine the standard relation between halo mass and concentration, but also to use large samples of objects in order to place constraints on dark matter self-interactions that can be more robust than constraints derived from individual objects. We demonstrate our method by considering a sample of about 50 objects distributed across the whole halo mass range, and by modelling the effect of self-interactions in a way similar to what has been previously done in the literature. Using additional input from simulations then results in a constraint on the self-interaction cross section per unit dark matter mass of about σ/mχlesssim 0.3 cm2/g. We expect that these constraints can be significantly improved in the future, and made more robust, by i) an improved modelling of the effect of self-interactions, both theoretical and by comparison with simulations, ii) taking into account a larger sample of objects and iii) by reducing the currently still relatively large uncertainties that we conservatively assign to the surface densities of individual objects. The latter can be achieved in particular by using kinematic observations to directly constrain the average halo mass inside a given radius, rather than fitting the data to a pre-selected profile and then reconstruct the mass. For a velocity-independent cross-section, our current result is formally already somewhat smaller than the range 0.5‑5 cm2/g that has been invoked to explain potential inconsistencies between small-scale observations and expectations in the standard collisionless cold dark matter paradigm.

Thermal dark matter co-annihilating with a strongly interacting scalar

Science.gov (United States)

Biondini, S.; Laine, M.

2018-04-01

Recently many investigations have considered Majorana dark matter co-annihilating with bound states formed by a strongly interacting scalar field. However only the gluon radiation contribution to bound state formation and dissociation, which at high temperatures is subleading to soft 2 → 2 scatterings, has been included. Making use of a non-relativistic effective theory framework and solving a plasma-modified Schrödinger equation, we address the effect of soft 2 → 2 scatterings as well as the thermal dissociation of bound states. We argue that the mass splitting between the Majorana and scalar field has in general both a lower and an upper bound, and that the dark matter mass scale can be pushed at least up to 5…6TeV.

Make dark matter charged again

Energy Technology Data Exchange (ETDEWEB)

Agrawal, Prateek; Cyr-Racine, Francis-Yan; Randall, Lisa; Scholtz, Jakub, E-mail: prateekagrawal@fas.harvard.edu, E-mail: fcyrraci@physics.harvard.edu, E-mail: randall@physics.harvard.edu, E-mail: jscholtz@physics.harvard.edu [Department of Physics, Harvard University, Cambridge, MA 02138 (United States)

2017-05-01

We revisit constraints on dark matter that is charged under a U(1) gauge group in the dark sector, decoupled from Standard Model forces. We find that the strongest constraints in the literature are subject to a number of mitigating factors. For instance, the naive dark matter thermalization timescale in halos is corrected by saturation effects that slow down isotropization for modest ellipticities. The weakened bounds uncover interesting parameter space, making models with weak-scale charged dark matter viable, even with electromagnetic strength interaction. This also leads to the intriguing possibility that dark matter self-interactions within small dwarf galaxies are extremely large, a relatively unexplored regime in current simulations. Such strong interactions suppress heat transfer over scales larger than the dark matter mean free path, inducing a dynamical cutoff length scale above which the system appears to have only feeble interactions. These effects must be taken into account to assess the viability of darkly-charged dark matter. Future analyses and measurements should probe a promising region of parameter space for this model.

Constraints on Λ(t)-cosmology with power law interacting dark sectors

International Nuclear Information System (INIS)

Poitras, Vincent

2012-01-01

Motivated by the cosmological constant and the coincidence problems, we consider a cosmological model where the cosmological constant Λ 0 is replaced by a cosmological term Λ(t) which is allowed to vary in time. More specifically, we are considering that this dark energy term interacts with dark matter through the phenomenological decay law ρ-dot Λ = −Qρ Λ n . We have constrained the model for the range n element of [0,10] using various observational data (SNeIa, GRB, CMB, BAO, OHD), emphasizing the case where n = 3/2. This case is the only one where the late-time value for the ratio of dark energy density and matter energy density ρ Λ /ρ m is constant, which could provide an interesting explanation to the coincidence problem. We obtain strong limits on the model parameters which however exclude the region where the coincidence or the cosmological constant problems are significantly ameliorated

Dark matter that can form dark stars

International Nuclear Information System (INIS)

Gondolo, Paolo; Huh, Ji-Haeng; Kim, Hyung Do; Scopel, Stefano

2010-01-01

The first stars to form in the Universe may be powered by the annihilation of weakly interacting dark matter particles. These so-called dark stars, if observed, may give us a clue about the nature of dark matter. Here we examine which models for particle dark matter satisfy the conditions for the formation of dark stars. We find that in general models with thermal dark matter lead to the formation of dark stars, with few notable exceptions: heavy neutralinos in the presence of coannihilations, annihilations that are resonant at dark matter freeze-out but not in dark stars, some models of neutrinophilic dark matter annihilating into neutrinos only and lighter than about 50 GeV. In particular, we find that a thermal DM candidate in standard Cosmology always forms a dark star as long as its mass is heavier than ≅ 50 GeV and the thermal average of its annihilation cross section is the same at the decoupling temperature and during the dark star formation, as for instance in the case of an annihilation cross section with a non-vanishing s-wave contribution

Dark Matter Effective Theory

DEFF Research Database (Denmark)

Del Nobile, Eugenio; Sannino, Francesco

2012-01-01

We organize the effective (self)interaction terms for complex scalar dark matter candidates which are either an isosinglet, isodoublet or an isotriplet with respect to the weak interactions. The classification has been performed ordering the operators in inverse powers of the dark matter cutoff...... scale. We assume Lorentz invariance, color and charge neutrality. We also introduce potentially interesting dark matter induced flavor-changing operators. Our general framework allows for model independent investigations of dark matter properties....

The Dark Side of Friendship: Questions about Negative Interactions between Friends.

Science.gov (United States)

Berndt, Thomas J.

Alluding to the difficulty in explaining the two opposing powers, the "dark side" and the Force, in the Star Wars movies, this paper focuses on the complex combination of negative and positive interactions among children who are best friends. Presented in question-answer format, the paper discusses research findings and needs related to…

On the interpretation of dark matter self-interactions in Abell 3827

DEFF Research Database (Denmark)

Kahlhoefer, Felix; Schmidt-Hoberg, Kai; Kummer, Janis

2015-01-01

Self-interactions of dark matter (DM) particles can potentially lead to an observable separation between the DM halo and the stars of a galaxy moving through a region of large DM density. Such a separation has recently been observed in a galaxy falling into the core of the galaxy cluster Abell 3827...

Search for weakly interacting massive particles with the Cryogenic Dark Matter Search experiment

Energy Technology Data Exchange (ETDEWEB)

Saab, Tarek [Stanford U.

2002-01-01

From individual galaxies, to clusters of galaxies, to in between the cushions of your sofa, Dark Matter appears to be pervasive on every scale. With increasing accuracy, recent astrophysical measurements, from a variety of experiments, are arriving at the following cosmological model : a flat cosmology (Ωk = 0) with matter and energy densities contributing roughly 1/3 and 2/3 (Ωm = 0.35, ΩΛ = 0.65). Of the matter contribution, it appears that only ~ 10% (Ωb ~ 0.04) is attributable to baryons. Astrophysical measurements constrain the remaining matter to be non-realtivistic, interacting primarily gravitationally. Various theoretical models for such Dark Matter exist. A leading candidate for the non-baryonic matter are Weakly Interacting Massive Particles (dubbed WIMPS). These particles, and their relic density may be naturally explained within the framework of Super-Symmetry theories. SuperSymmetry also offers predictions as to the scattering rates of WIMPs with baryonic matter allowing for the design and tailoring of experiments that search specifically for the WIMPs. The Cryogenic Dark Matter Search experiment is searching for evidence of WIMP interactions in crystals of Ge and Si. Using cryogenic detector technology to measure both the phonon and ionization response to a particle recoil the CDMS detectors are able to discriminate between electron and nuclear recoils, thus reducing the large rates of electron recoil backgrounds to levels with which a Dark Matter search is not only feasible, but far-reaching. This thesis will describe in some detail the physical principles behind the CDMS detector technology, highlighting the final step in the evolution of the detector design and characterization techniques. In addition, data from a 100 day long exposure of the current run at the Stanford Underground Facility will be presented, with focus given to detector performance as well as to the implications on allowable WIMP mass - cross-section parameter space.

arXiv Supplying Dark Energy from Scalar Field Dark Matter

CERN Document Server

Gogberashvili, Merab

We consider the hypothesis that dark matter and dark energy consists of ultra-light self-interacting scalar particles. It is found that the Klein-Gordon equation with only two free parameters (mass and self-coupling) on a Schwarzschild background, at the galactic length-scales has the solution which corresponds to Bose-Einstein condensate, behaving as dark matter, while the constant solution at supra-galactic scales can explain dark energy.

Directly detecting isospin-violating dark matter

OpenAIRE

Kelso, Chris; Kumar, Jason; Marfatia, Danny; Sandick, Pearl

2018-01-01

We consider the prospects for multiple dark matter direct detection experiments to determine if the interactions of a dark matter candidate are isospin-violating. We focus on theoretically well-motivated examples of isospin-violating dark matter (IVDM), including models in which dark matter interactions with nuclei are mediated by a dark photon, a Z, or a squark. We determine that the best prospects for distinguishing IVDM from the isospin-invariant scenario arise in the cases of dark photon–...

Emergent Criticality and Ricci Flow in a 2D Frustrated Heisenberg Model

Science.gov (United States)

Orth, Peter P.

2014-03-01

In most systems that exhibit order at low temperatures, the order occurs in the elementary degrees of freedom such as spin or charge. Prominent examples are magnetic or superconducting states of matter. In contrast, emergent order describes the phenomenon where composite objects exhibit longer range correlations. Such emergent order has been suspected to occur in a range of correlated materials. One specific example are spin systems with competing interactions, where long-range discrete order in the relative orientation of spins may occur. Interestingly, this order parameter may induce other phase transitions as is the case for the nematic transition in the iron pnictides. In this talk, we introduce and discuss a system with emergent Z6 symmetry, a two-dimensional frustrated Heisenberg antiferromagnet on the windmill lattice consisting of interpenetrating honeycomb and triangular lattices. The multiple spin stiffnesses can be captured in terms of a four-dimensional metric tensor, and the renormalization group flow of the stiffnesses is described by the Ricci flow of the metric tensor. The key result is a decoupling of an emergent collective degree of freedom given by the relative phase of spins on different sublattices. In particular, our results reveal a sequence of two Berezinskii-Kosterlitz-Thouless phase transitions that bracket a critical phase.

Ricci cubic gravity in d dimensions, gravitons and SAdS/Lifshitz black holes

Energy Technology Data Exchange (ETDEWEB)

Ghodsi, Ahmad; Najafi, Farzaneh [Ferdowsi University of Mashhad, Department of Physics, Mashhad (Iran, Islamic Republic of)

2017-08-15

A special class of higher curvature theories of gravity, Ricci cubic gravity (RCG), in general d dimensional space-time has been investigated in this paper. We have used two different approaches, the linearized equations of motion and the auxiliary field formalism to study the massive and massless graviton propagating modes of the AdS background. Using the auxiliary field formalism, we have found the renormalized boundary stress tensor to compute the mass of the Schwarzschild-AdS and Lifshitz black holes in RCG theory. (orig.)

Multipartite interacting scalar dark matter in the light of updated LUX data

Energy Technology Data Exchange (ETDEWEB)

Bhattacharya, Subhaditya; Ghosh, Purusottam; Poulose, Poulose, E-mail: subhab@iitg.ernet.in, E-mail: p.ghosh@iitg.ernet.in, E-mail: poulose@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati, Assam 781039 (India)

2017-04-01

We explore constraints on multipartite dark matter (DM) framework composed of singlet scalar DM interacting with the Standard Model (SM) through Higgs portal coupling. We compute relic density and direct search constraints including the updated LUX bound for two component scenario with non-zero interactions between two DM components in Z{sub 2} × Z{sub 2}{sup '} framework in comparison with the one having O(2) symmetry. We point out availability of a significantly large region of parameter space of such a multipartite model with DM-DM interactions.

Musei parlanti. Corrado Ricci e la sfida di comunicare ad un ampio pubblico / Talking museums. Corrado Ricci and the challenge of communicating the museum to a wide audience

Directory of Open Access Journals (Sweden)

Silvia Cecchini

2013-05-01

Full Text Available Nel ruolo di direttore di musei Corrado Ricci sperimenta, tra il 1893 e il 1904, la possibilità di far comunicare il museo con un pubblico più ampio degli addetti ai lavori attraverso sale allestite secondo un impianto tipologico-iconografico.  Crea così le sale storico-topografiche e le sale dei ritratti. Il modello viene realizzato per la prima volta nella Galleria Reale di Parma, poi replicato nella Galleria Estense di Modena, nell’Accademia Carrara di Bergamo, ed anche nella mostra temporanea dedicata all’antica arte senese. Introduce uno spazio di mediazione tra gli spazi della città e le sale del museo, tra il tempo presente della vita e il passato ritratto nei quadri. Proposte che oggi ci possono sollecitare a riflettere sul ruolo della ricerca e su quello della traduzione, momenti essenziali del messaggio che il museo vorrebbe trasmettere.   As Museum Director Corrado Ricci experiences, between 1893 and 1904, the ability to communicate the Museum to a wider audience then the scholars through halls outfitted with a typological-iconographic system. He creates topographic-historic rooms and rooms of portraits. The model is realized for the first time in the Royal Gallery of Parma, then replicated in Galleria Estense in Modena, in the Accademia Carrara of Bergamo, and also in the temporary exhibition dedicated to ancient art of Siena. He introduces a mediation between the spaces of the city and the rooms of the Museum, between the present life and the past of the paintings. Proposals that today we shall seek to reflect on the role of research and translation, essential moments of the message that the Museum would like to transmit.

Strategies for dark matter detection

International Nuclear Information System (INIS)

Silk, J.

1988-01-01

The present status of alternative forms of dark matter, both baryonic and nonbaryonic, is reviewed. Alternative arguments are presented for the predominance of either cold dark matter (CDM) or of baryonic dark matter (BDM). Strategies are described for dark matter detection, both for dark matter that consists of weakly interacting relic particles and for dark matter that consists of dark stellar remnants

On the capture of dark matter by neutron stars

International Nuclear Information System (INIS)

Güver, Tolga; Erkoca, Arif Emre; Sarcevic, Ina; Reno, Mary Hall

2014-01-01

We calculate the number of dark matter particles that a neutron star accumulates over its lifetime as it rotates around the center of a galaxy, when the dark matter particle is a self-interacting boson but does not self-annihilate. We take into account dark matter interactions with baryonic matter and the time evolution of the dark matter sphere as it collapses within the neutron star. We show that dark matter self-interactions play an important role in the rapid accumulation of dark matter in the core of the neutron star. We consider the possibility of determining an exclusion region of the parameter space for dark matter mass and dark matter interaction cross section with the nucleons as well as dark matter self-interaction cross section, based on the observation of old neutron stars. We show that for a dark matter density of 10 3 GeV/cm 3 and dark matter mass m χ ∼< 10 GeV, there is a potential exclusion region for dark matter interactions with nucleons that is three orders of magnitude more stringent than without self-interactions. The potential exclusion region for dark matter self-interaction cross sections is many orders of magnitude stronger than the current Bullet Cluster limit. For example, for high dark matter density regions, we find that for m χ ∼ 10 GeV when the dark matter interaction cross section with the nucleons ranges from σ χn ∼ 10 −52 cm 2 to σ χn ∼ 10 −57 cm 2 , the dark matter self-interaction cross section limit is σ χχ ∼< 10 −33 cm 2 , which is about ten orders of magnitude stronger than the Bullet Cluster limit

Traversable geometric dark energy wormholes constrained by astrophysical observations

Energy Technology Data Exchange (ETDEWEB)

Wang, Deng [Nankai University, Theoretical Physics Division, Chern Institute of Mathematics, Tianjin (China); Meng, Xin-he [Nankai University, Department of Physics, Tianjin (China); Institute of Theoretical Physics, CAS, State Key Lab of Theoretical Physics, Beijing (China)

2016-09-15

In this paper, we introduce the astrophysical observations into the wormhole research. We investigate the evolution behavior of the dark energy equation of state parameter ω by constraining the dark energy model, so that we can determine in which stage of the universe wormholes can exist by using the condition ω < -1. As a concrete instance, we study the Ricci dark energy (RDE) traversable wormholes constrained by astrophysical observations. Particularly, we find from Fig. 5 of this work, when the effective equation of state parameter ω{sub X} < -1 (or z < 0.109), i.e., the null energy condition (NEC) is violated clearly, the wormholes will exist (open). Subsequently, six specific solutions of statically and spherically symmetric traversable wormhole supported by the RDE fluids are obtained. Except for the case of a constant redshift function, where the solution is not only asymptotically flat but also traversable, the five remaining solutions are all non-asymptotically flat, therefore, the exotic matter from the RDE fluids is spatially distributed in the vicinity of the throat. Furthermore, we analyze the physical characteristics and properties of the RDE traversable wormholes. It is worth noting that, using the astrophysical observations, we obtain the constraints on the parameters of the RDE model, explore the types of exotic RDE fluids in different stages of the universe, limit the number of available models for wormhole research, reduce theoretically the number of the wormholes corresponding to different parameters for the RDE model, and provide a clearer picture for wormhole investigations from the new perspective of observational cosmology. (orig.)

Traversable geometric dark energy wormholes constrained by astrophysical observations

International Nuclear Information System (INIS)

Wang, Deng; Meng, Xin-he

2016-01-01

In this paper, we introduce the astrophysical observations into the wormhole research. We investigate the evolution behavior of the dark energy equation of state parameter ω by constraining the dark energy model, so that we can determine in which stage of the universe wormholes can exist by using the condition ω < -1. As a concrete instance, we study the Ricci dark energy (RDE) traversable wormholes constrained by astrophysical observations. Particularly, we find from Fig. 5 of this work, when the effective equation of state parameter ω X < -1 (or z < 0.109), i.e., the null energy condition (NEC) is violated clearly, the wormholes will exist (open). Subsequently, six specific solutions of statically and spherically symmetric traversable wormhole supported by the RDE fluids are obtained. Except for the case of a constant redshift function, where the solution is not only asymptotically flat but also traversable, the five remaining solutions are all non-asymptotically flat, therefore, the exotic matter from the RDE fluids is spatially distributed in the vicinity of the throat. Furthermore, we analyze the physical characteristics and properties of the RDE traversable wormholes. It is worth noting that, using the astrophysical observations, we obtain the constraints on the parameters of the RDE model, explore the types of exotic RDE fluids in different stages of the universe, limit the number of available models for wormhole research, reduce theoretically the number of the wormholes corresponding to different parameters for the RDE model, and provide a clearer picture for wormhole investigations from the new perspective of observational cosmology. (orig.)

Why we need to see the dark matter to understand the dark energy

OpenAIRE

Kunz, Martin

2007-01-01

The cosmological concordance model contains two separate constituents which interact only gravitationally with themselves and everything else, the dark matter and the dark energy. In the standard dark energy models, the dark matter makes up some 20% of the total energy budget today, while the dark energy is responsible for about 75%. Here we show that these numbers are only robust for specific dark energy models and that in general we cannot measure the abundance of the dark constituents sepa...

Unified dark energy-dark matter model with inverse quintessence

Energy Technology Data Exchange (ETDEWEB)

Ansoldi, Stefano [ICRA — International Center for Relativistic Astrophysics, INFN — Istituto Nazionale di Fisica Nucleare, and Dipartimento di Matematica e Informatica, Università degli Studi di Udine, via delle Scienze 206, I-33100 Udine (UD) (Italy); Guendelman, Eduardo I., E-mail: ansoldi@fulbrightmail.org, E-mail: guendel@bgu.ac.il [Department of Physics, Ben-Gurion University of the Negeev, Beer-Sheva 84105 (Israel)

2013-05-01

We consider a model where both dark energy and dark matter originate from the coupling of a scalar field with a non-canonical kinetic term to, both, a metric measure and a non-metric measure. An interacting dark energy/dark matter scenario can be obtained by introducing an additional scalar that can produce non constant vacuum energy and associated variations in dark matter. The phenomenology is most interesting when the kinetic term of the additional scalar field is ghost-type, since in this case the dark energy vanishes in the early universe and then grows with time. This constitutes an ''inverse quintessence scenario'', where the universe starts from a zero vacuum energy density state, instead of approaching it in the future.

Unified dark energy-dark matter model with inverse quintessence

International Nuclear Information System (INIS)

Ansoldi, Stefano; Guendelman, Eduardo I.

2013-01-01

We consider a model where both dark energy and dark matter originate from the coupling of a scalar field with a non-canonical kinetic term to, both, a metric measure and a non-metric measure. An interacting dark energy/dark matter scenario can be obtained by introducing an additional scalar that can produce non constant vacuum energy and associated variations in dark matter. The phenomenology is most interesting when the kinetic term of the additional scalar field is ghost-type, since in this case the dark energy vanishes in the early universe and then grows with time. This constitutes an ''inverse quintessence scenario'', where the universe starts from a zero vacuum energy density state, instead of approaching it in the future

Observational constraint on the interacting dark energy models including the Sandage-Loeb test

Science.gov (United States)

Zhang, Ming-Jian; Liu, Wen-Biao

2014-05-01

Two types of interacting dark energy models are investigated using the type Ia supernova (SNIa), observational data (OHD), cosmic microwave background shift parameter, and the secular Sandage-Loeb (SL) test. In the investigation, we have used two sets of parameter priors including WMAP-9 and Planck 2013. They have shown some interesting differences. We find that the inclusion of SL test can obviously provide a more stringent constraint on the parameters in both models. For the constant coupling model, the interaction term has been improved to be only a half of the original scale on corresponding errors. Comparing with only SNIa and OHD, we find that the inclusion of the SL test almost reduces the best-fit interaction to zero, which indicates that the higher-redshift observation including the SL test is necessary to track the evolution of the interaction. For the varying coupling model, data with the inclusion of the SL test show that the parameter at C.L. in Planck priors is , where the constant is characteristic for the severity of the coincidence problem. This indicates that the coincidence problem will be less severe. We then reconstruct the interaction , and we find that the best-fit interaction is also negative, similar to the constant coupling model. However, for a high redshift, the interaction generally vanishes at infinity. We also find that the phantom-like dark energy with is favored over the CDM model.

Phenomenology of ELDER dark matter

Science.gov (United States)

Kuflik, Eric; Perelstein, Maxim; Lorier, Nicolas Rey-Le; Tsai, Yu-Dai

2017-08-01

We explore the phenomenology of Elastically Decoupling Relic (ELDER) dark matter. ELDER is a thermal relic whose present density is determined primarily by the cross-section of its elastic scattering off Standard Model (SM) particles. Assuming that this scattering is mediated by a kinetically mixed dark photon, we argue that the ELDER scenario makes robust predictions for electron-recoil direct-detection experiments, as well as for dark photon searches. These predictions are independent of the details of interactions within the dark sector. Together with the closely related Strongly-Interacting Massive Particle (SIMP) scenario, the ELDER predictions provide a physically motivated, well-defined target region, which will be almost entirely accessible to the next generation of searches for sub-GeV dark matter and dark photons. We provide useful analytic approximations for various quantities of interest in the ELDER scenario, and discuss two simple renormalizable toy models which incorporate the required strong number-changing interactions among the ELDERs, as well as explicitly implement the coupling to electrons via the dark photon portal.

THE CASE AGAINST WARM OR SELF-INTERACTING DARK MATTER AS EXPLANATIONS FOR CORES IN LOW SURFACE BRIGHTNESS GALAXIES

International Nuclear Information System (INIS)

Kuzio de Naray, Rachel; Martinez, Gregory D.; Bullock, James S.; Kaplinghat, Manoj

2010-01-01

Warm dark matter (WDM) and self-interacting dark matter (SIDM) are often motivated by the inferred cores in the dark matter halos of low surface brightness (LSB) galaxies. We test thermal WDM, non-thermal WDM, and SIDM using high-resolution rotation curves of nine LSB galaxies. We fit these dark matter models to the data and determine the halo core radii and central densities. While the minimum core size in WDM models is predicted to decrease with halo mass, we find that the inferred core radii increase with halo mass and also cannot be explained with a single value of the primordial phase-space density. Moreover, if the core size is set by WDM particle properties, then even the smallest cores we infer would require primordial phase-space density values that are orders of magnitude smaller than lower limits obtained from the Lyα forest power spectra. We also find that the dark matter halo core densities vary by a factor of about 30 from system to system while showing no systematic trend with the maximum rotation velocity of the galaxy. This strongly argues against the core size being directly set by large self-interactions (scattering or annihilation) of dark matter. We therefore conclude that the inferred cores do not provide motivation to prefer WDM or SIDM over other dark matter models.

Search for Dark Matter Interactions using Ionization Yield in Liquid Xenon

Science.gov (United States)

Uvarov, Sergey

Cosmological observations overwhelmingly support the existence of dark matter which constitutes 87% of the universe's total mass. Weakly Interacting Massive Particles (WIMPs) are a prime candidate for dark matter, and the Large Underground Xenon (LUX) experiment aims to a direct-detection of a WIMP-nucleon interaction. The LUX detector is a dual-phase xenon time-projection chamber housed 4,850 feet underground at Sanford Underground Research Facility in Lead, South Dakota. We present the ionization-only analysis of the LUX 2013 WIMP search data. In the 1.04 x 104 kg-days exposure, thirty events were observed out of the 24.8 expected from radioactive backgrounds. We employ a cut-and-count method to set a 1-sided 90% C.L. upper limit for spin-independent WIMP-nucleon cross-sections. A zero charge yield for nuclear-recoils below 0.7 keV is included upper limit calculation. This ionization-only analysis excludes an unexplored region of WIMP-nucleon cross-section for low-mass WIMPs achieving 1.56 x 10-43 cm2 WIMP-nucleon cross-section exclusion for a 5.1 GeV/ c2 WIMP.

Why we need to see the dark matter to understand the dark energy

International Nuclear Information System (INIS)

Kunz, M

2008-01-01

Abstract. The cosmological concordance model contains two separate constituents which interact only gravitationally with themselves and everything else, the dark matter and the dark energy. In the standard dark energy models, the dark matter makes up some 20% of the total energy budget today, while the dark energy is responsible for about 75%. Here we show that these numbers are only robust for specific dark energy models and that in general we cannot measure the abundance of the dark constituents separately without making strong assumptions

Rotation curves of galaxies by fourth order gravity

International Nuclear Information System (INIS)

Stabile, A.; Scelza, G.

2011-01-01

We investigate the radial behavior of galactic rotation curves by a Fourth Order Gravity adding also the dark matter component. The Fourth Order Gravity is a theory of gravity described by Lagrangian generalizing the one of Hilbert-Einstein containing a generic function of the Ricci scalar, the Ricci and Riemann tensor. A systematic analysis of rotation curves, in the Newtonian Limit of theory, induced by all galactic substructures of ordinary matter is shown. This analysis is presented for Fourth Order Gravity with and without dark matter. The outcomes are compared with respect to the classical outcomes of General Relativity. The gravitational potential of pointlike mass is the usual potential corrected by two Yukawa terms. The rotation curve is higher or also lower than curve of General Relativity if in the Lagrangian the Ricci scalar square is dominant or not with respect to the contribution of the Ricci tensor square. The theoretical spatial behaviors of rotation curve are compared with the experimental data for the Milky Way and the galaxy NGC 3198. Although the Fourth Order Gravity gives more rotational contributions, in the limit of large distances the Keplerian behavior is ever present, and it is missing only if we add the dark matter component. However by modifying the theory of gravity, consequently, also the spatial description of dark matter could undergo a modification and the free parameters of model can assume different values. After an analytical discussion of theoretical behaviors and the comparing with experimental evidence we can claim that any Fourth Order Gravity is not successful to explain the galactic rotation curves. In the last part of paper we analyze the gravitational potential induced by Lagrangian containing only powers of Ricci scalar. In this case we find an inconsistency in the boundary conditions in the passage from matter to the vacuum.

Directly detecting isospin-violating dark matter

Science.gov (United States)

Kelso, Chris; Kumar, Jason; Marfatia, Danny; Sandick, Pearl

2018-03-01

We consider the prospects for multiple dark matter direct detection experiments to determine if the interactions of a dark matter candidate are isospin-violating. We focus on theoretically well-motivated examples of isospin-violating dark matter (IVDM), including models in which dark matter interactions with nuclei are mediated by a dark photon, a Z , or a squark. We determine that the best prospects for distinguishing IVDM from the isospin-invariant scenario arise in the cases of dark photon-or Z -mediated interactions, and that the ideal experimental scenario would consist of large exposure xenon- and neon-based detectors. If such models just evade current direct detection limits, then one could distinguish such models from the standard isospin-invariant case with two detectors with of order 100 ton-year exposure.

Effective theories for Dark Matter interactions and the neutrino portal paradigm

Energy Technology Data Exchange (ETDEWEB)

Macías, Vannia González; Wudka, José [Department of Physics & Astronomy, University of California Riverside,University Av., Riverside, California 92521-0413 (United States)

2015-07-29

In this article we discuss a general effective-theory description of a multi-component dark sector with an unspecified non-trivial symmetry and its interactions with the Standard Model generated by the exchange of heavy mediators. We then categorize the relevant effective operators given the current experimental sensistivity where the underlying theory is weakly coupled and renormalizable, with neutral mediators: either scalars or fermions. An interesting scenario resulting from this categorization is the neutrino portal, where only fermion mediators are present, and where the dark sector consists of fermions and scalars such that the lightest dark particle is a fermion, this scenario is characterized by having naturally suppressed couplings of the DM to all SM particles except the neutrinos and has received little attention in the literature. We find that there is a wide region in parameter space allowed by the current experimental constraints (relic abundance, direct and indirect detection limits); the cleanest signature of this paradigm is the presence of monochromatic neutrino lines with energy equal to that of the DM mass, but experimental sensitivity would have to be improved significantly before this can be probed.

Macro Dark Matter

CERN Document Server

Jacobs, David M; Lynn, Bryan W.

2015-01-01

Dark matter is a vital component of the current best model of our universe, $\\Lambda$CDM. There are leading candidates for what the dark matter could be (e.g. weakly-interacting massive particles, or axions), but no compelling observational or experimental evidence exists to support these particular candidates, nor any beyond-the-Standard-Model physics that might produce such candidates. This suggests that other dark matter candidates, including ones that might arise in the Standard Model, should receive increased attention. Here we consider a general class of dark matter candidates with characteristic masses and interaction cross-sections characterized in units of grams and cm$^2$, respectively -- we therefore dub these macroscopic objects as Macros. Such dark matter candidates could potentially be assembled out of Standard Model particles (quarks and leptons) in the early universe. A combination of earth-based, astrophysical, and cosmological observations constrain a portion of the Macro parameter space; ho...

Self-interacting inelastic dark matter: a viable solution to the small scale structure problems

Energy Technology Data Exchange (ETDEWEB)

Blennow, Mattias; Clementz, Stefan; Herrero-Garcia, Juan, E-mail: emb@kth.se, E-mail: scl@kth.se, E-mail: juan.herrero-garcia@adelaide.edu.au [Department of Physics, School of Engineering Sciences, KTH Royal Institute of Technology, AlbaNova University Center, 106 91 Stockholm (Sweden)

2017-03-01

Self-interacting dark matter has been proposed as a solution to the small-scale structure problems, such as the observed flat cores in dwarf and low surface brightness galaxies. If scattering takes place through light mediators, the scattering cross section relevant to solve these problems may fall into the non-perturbative regime leading to a non-trivial velocity dependence, which allows compatibility with limits stemming from cluster-size objects. However, these models are strongly constrained by different observations, in particular from the requirements that the decay of the light mediator is sufficiently rapid (before Big Bang Nucleosynthesis) and from direct detection. A natural solution to reconcile both requirements are inelastic endothermic interactions, such that scatterings in direct detection experiments are suppressed or even kinematically forbidden if the mass splitting between the two-states is sufficiently large. Using an exact solution when numerically solving the Schrödinger equation, we study such scenarios and find regions in the parameter space of dark matter and mediator masses, and the mass splitting of the states, where the small scale structure problems can be solved, the dark matter has the correct relic abundance and direct detection limits can be evaded.

Dark matter detectors

International Nuclear Information System (INIS)

Forster, G.

1995-01-01

A fundamental question of astrophysics and cosmology is the nature of dark matter. Astrophysical observations show clearly the existence of some kind of dark matter, though they cannot yet reveal its nature. Dark matter can consist of baryonic particles, or of other (known or unknown) elementary particles. Baryonic dark matter probably exists in the form of dust, gas, or small stars. Other elementary particles constituting the dark matter can possibly be measured in terrestrial experiments. Possibilities for dark matter particles are neutrinos, axions and weakly interacting massive particles (WIMPs). While a direct detection of relic neutrinos seems at the moment impossible, there are experiments looking for baryonic dark matter in the form of Massive Compact Halo Objects, and for particle dark matter in the form of axions and WIMPS. (orig.)

Signatures of dark radiation in neutrino and dark matter detectors

OpenAIRE

Cui, Yanou; Pospelov, Maxim; Pradler, Josef

2018-01-01

We consider the generic possibility that the Universe’s energy budget includes some form of relativistic or semi-relativistic dark radiation (DR) with nongravitational interactions with standard model (SM) particles. Such dark radiation may consist of SM singlets or a nonthermal, energetic component of neutrinos. If such DR is created at a relatively recent epoch, it can carry sufficient energy to leave a detectable imprint in experiments designed to search for very weakly interacting particl...

Plasma dark matter direct detection

Energy Technology Data Exchange (ETDEWEB)

Clarke, J.D.; Foot, R., E-mail: j.clarke5@pgrad.unimelb.edu.au, E-mail: rfoot@unimelb.edu.au [ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics, University of Melbourne, Victoria 3010 Australia (Australia)

2016-01-01

Dark matter in spiral galaxies like the Milky Way may take the form of a dark plasma. Hidden sector dark matter charged under an unbroken U(1)' gauge interaction provides a simple and well defined particle physics model realising this possibility. The assumed U(1)' neutrality of the Universe then implies (at least) two oppositely charged dark matter components with self-interactions mediated via a massless 'dark photon' (the U(1)' gauge boson). In addition to nuclear recoils such dark matter can give rise to keV electron recoils in direct detection experiments. In this context, the detailed physical properties of the dark matter plasma interacting with the Earth is required. This is a complex system, which is here modelled as a fluid governed by the magnetohydrodynamic equations. These equations are numerically solved for some illustrative examples, and implications for direct detection experiments discussed. In particular, the analysis presented here leaves open the intriguing possibility that the DAMA annual modulation signal is due primarily to electron recoils (or even a combination of electron recoils and nuclear recoils). The importance of diurnal modulation (in addition to annual modulation) as a means of probing this kind of dark matter is also emphasised.

Z2 SIMP dark matter

International Nuclear Information System (INIS)

Bernal, Nicolás; Chu, Xiaoyong

2016-01-01

Dark matter with strong self-interactions provides a compelling solution to several small-scale structure puzzles. Under the assumption that the coupling between dark matter and the Standard Model particles is suppressed, such strongly interacting massive particles (SIMPs) allow for a successful thermal freeze-out through N-to-N' processes, where N dark matter particles annihilate to N' of them. In the most common scenarios, where dark matter stability is guaranteed by a Z 2 symmetry, the seemingly leading annihilating channel, i.e. 3-to-2 process, is forbidden, so the 4-to-2 one dominate the production of the dark matter relic density. Moreover, cosmological observations require that the dark matter sector is colder than the thermal bath of Standard Model particles, a condition that can be dynamically generated via a small portal between dark matter and Standard Model particles, à la freeze-in. This scenario is exemplified in the context of the Singlet Scalar dark matter model

Direct search for dark matter

Energy Technology Data Exchange (ETDEWEB)

Yoo, Jonghee; /Fermilab

2009-12-01

Dark matter is hypothetical matter which does not interact with electromagnetic radiation. The existence of dark matter is only inferred from gravitational effects of astrophysical observations to explain the missing mass component of the Universe. Weakly Interacting Massive Particles are currently the most popular candidate to explain the missing mass component. I review the current status of experimental searches of dark matter through direct detection using terrestrial detectors.

Extra Dimensions are Dark: II Fermionic Dark Matter

OpenAIRE

Rizzo, Thomas G.

2018-01-01

Extra dimensions can be very useful tools when constructing new physics models. Previously, we began investigating toy models for the 5-D analog of the kinetic mixing/vector portal scenario where the interactions of bulk dark matter with the brane-localized fields of the Standard Model are mediated by a massive $U(1)_D$ dark photon also living in the bulk. In that setup, where the dark matter was taken to be a complex scalar, a number of nice features were obtained such as $U(1)_D$ breaking b...

Working Group Report: Dark Matter Complementarity (Dark Matter in the Coming Decade: Complementary Paths to Discovery and Beyond)

Energy Technology Data Exchange (ETDEWEB)

Arrenberg, Sebastian; et al.,

2013-10-31

In this Report we discuss the four complementary searches for the identity of dark matter: direct detection experiments that look for dark matter interacting in the lab, indirect detection experiments that connect lab signals to dark matter in our own and other galaxies, collider experiments that elucidate the particle properties of dark matter, and astrophysical probes sensitive to non-gravitational interactions of dark matter. The complementarity among the different dark matter searches is discussed qualitatively and illustrated quantitatively in several theoretical scenarios. Our primary conclusion is that the diversity of possible dark matter candidates requires a balanced program based on all four of those approaches.

Dark matter directional detection in non-relativistic effective theories

International Nuclear Information System (INIS)

Catena, Riccardo

2015-01-01

We extend the formalism of dark matter directional detection to arbitrary one-body dark matter-nucleon interactions. The new theoretical framework generalizes the one currently used, which is based on 2 types of dark matter-nucleon interaction only. It includes 14 dark matter-nucleon interaction operators, 8 isotope-dependent nuclear response functions, and the Radon transform of the first 2 moments of the dark matter velocity distribution. We calculate the recoil energy spectra at dark matter directional detectors made of CF 4 , CS 2 and 3 He for the 14 dark matter-nucleon interactions, using nuclear response functions recently obtained through numerical nuclear structure calculations. We highlight the new features of the proposed theoretical framework, and present our results for a spherical dark matter halo and for a stream of dark matter particles. This study lays the foundations for model independent analyses of dark matter directional detection experiments

Dark matter and neutrino mass from the smallest non-Abelian chiral dark sector

Science.gov (United States)

Berryman, Jeffrey M.; de Gouvêa, André; Kelly, Kevin J.; Zhang, Yue

2017-10-01

All pieces of concrete evidence for phenomena outside the standard model (SM)—neutrino masses and dark matter—are consistent with the existence of new degrees of freedom that interact very weakly, if at all, with those in the SM. We propose that these new degrees of freedom organize themselves into a simple dark sector, a chiral S U (3 )×S U (2 ) gauge theory with the smallest nontrivial fermion content. Similar to the SM, the dark S U (2 ) is spontaneously broken while the dark S U (3 ) confines at low energies. At the renormalizable level, the dark sector contains massless fermions—dark leptons—and stable massive particles—dark protons. We find that dark protons with masses between 10 and 100 TeV satisfy all current cosmological and astrophysical observations concerning dark matter even if dark protons are a symmetric thermal relic. The dark leptons play the role of right-handed neutrinos and allow simple realizations of the seesaw mechanism or the possibility that neutrinos are Dirac fermions. In the latter case, neutrino masses are also parametrically different from charged-fermion masses and the lightest neutrino is predicted to be massless. Since the new "neutrino" and "dark-matter" degrees of freedom interact with one another, these two new-physics phenomena are intertwined. Dark leptons play a nontrivial role in early Universe cosmology while indirect searches for dark matter involve, decisively, dark-matter annihilations into dark leptons. These, in turn, may lead to observable signatures at high-energy neutrino and gamma-ray observatories, especially once one accounts for the potential Sommerfeld enhancement of the annihilation cross section, derived from the low-energy dark-sector effective theory, a possibility we explore quantitatively in some detail.

Asymptotically Safe Dark Matter

DEFF Research Database (Denmark)

Sannino, Francesco; Shoemaker, Ian M.

2015-01-01

We introduce a new paradigm for dark matter (DM) interactions in which the interaction strength is asymptotically safe. In models of this type, the coupling strength is small at low energies but increases at higher energies, and asymptotically approaches a finite constant value. The resulting...... searches are the primary ways to constrain or discover asymptotically safe dark matter....

Disentangling interacting dark energy cosmologies with the three-point correlation function

Science.gov (United States)

Moresco, Michele; Marulli, Federico; Baldi, Marco; Moscardini, Lauro; Cimatti, Andrea

2014-10-01

We investigate the possibility of constraining coupled dark energy (cDE) cosmologies using the three-point correlation function (3PCF). Making use of the CODECS N-body simulations, we study the statistical properties of cold dark matter (CDM) haloes for a variety of models, including a fiducial ΛCDM scenario and five models in which dark energy (DE) and CDM mutually interact. We measure both the halo 3PCF, ζ(θ), and the reduced 3PCF, Q(θ), at different scales (2 values of the halo 3PCF for perpendicular (elongated) configurations. The effect is also scale-dependent, with differences between ΛCDM and cDE models that increase at large scales. We made use of these measurements to estimate the halo bias, that results in fair agreement with the one computed from the two-point correlation function (2PCF). The main advantage of using both the 2PCF and 3PCF is to break the bias-σ8 degeneracy. Moreover, we find that our bias estimates are approximately independent of the assumed strength of DE coupling. This study demonstrates the power of a higher order clustering analysis in discriminating between alternative cosmological scenarios, for both present and forthcoming galaxy surveys, such as e.g. Baryon Oscillation Spectroscopic Survey and Euclid.

Secretly asymmetric dark matter

Science.gov (United States)

Agrawal, Prateek; Kilic, Can; Swaminathan, Sivaramakrishnan; Trendafilova, Cynthia

2017-01-01

We study a mechanism where the dark matter number density today arises from asymmetries generated in the dark sector in the early Universe, even though the total dark matter number remains zero throughout the history of the Universe. The dark matter population today can be completely symmetric, with annihilation rates above those expected from thermal weakly interacting massive particles. We give a simple example of this mechanism using a benchmark model of flavored dark matter. We discuss the experimental signatures of this setup, which arise mainly from the sector that annihilates the symmetric component of dark matter.

Characterizing dark matter interacting with extra charged leptons

Science.gov (United States)

Barducci, D.; Deandrea, A.; Moretti, S.; Panizzi, L.; Prager, H.

2018-04-01

In the context of a simplified leptophilic dark matter (DM) scenario where the mediator is a new charged fermion carrying leptonic quantum number and the DM candidate is either scalar or vector, the complementarity of different bounds is analyzed. In this framework, the extra lepton and DM are odd under a Z2 symmetry, and hence the leptonic mediator can only interact with the DM state and Standard Model leptons of various flavors. We show that there is the possibility to characterize the DM spin (scalar or vector), as well as the nature of the mediator, through a combined analysis of cosmological, flavor and collider data. We present an explicit numerical analysis for a set of benchmarks points of the viable parameter space of our scenario.

How cold is cold dark matter?

International Nuclear Information System (INIS)

Armendariz-Picon, Cristian; Neelakanta, Jayanth T.

2014-01-01

If cold dark matter consists of particles, these must be non-interacting and non-relativistic by definition. In most cold dark matter models however, dark matter particles inherit a non-vanishing velocity dispersion from interactions in the early universe, a velocity that redshifts with cosmic expansion but certainly remains non-zero. In this article, we place model-independent constraints on the dark matter temperature to mass ratio, whose square root determines the dark matter velocity dispersion. We only assume that dark matter particles decoupled kinetically while non-relativistic, when galactic scales had not entered the horizon yet, and that their momentum distribution has been Maxwellian since that time. Under these assumptions, using cosmic microwave background and matter power spectrum observations, we place upper limits on the temperature to mass ratio of cold dark matter today (away from collapsed structures). These limits imply that the present cold dark matter velocity dispersion has to be smaller than 54 m/s. Cold dark matter has to be quite cold, indeed

Dark matter and dark forces from a supersymmetric hidden sector

Energy Technology Data Exchange (ETDEWEB)

Andreas, S.; Goodsell, M.D.; Ringwald, A.

2011-09-15

We show that supersymmetric ''Dark Force'' models with gravity mediation are viable. To this end, we analyse a simple supersymmetric hidden sector model that interacts with the visible sector via kinetic mixing of a light Abelian gauge boson with the hypercharge. We include all induced interactions with the visible sector such as neutralino mass mixing and the Higgs portal term. We perform a detailed parameter space scan comparing the produced dark matter relic abundance and direct detection cross-sections to current experiments. (orig.)

Asymmetric dark matter: residual annihilations and self-interactions arXiv

CERN Document Server

Baldes, Iason; Panci, Paolo; Petraki, Kalliopi; Sala, Filippo; Taoso, Marco

Dark matter (DM) coupled to light mediators has been invoked to resolve the putative discrepancies between collisionless cold DM and galactic structure observations. However, $\\gamma$-ray searches and the CMB strongly constrain such scenarios. To ease the tension, we consider asymmetric DM. We show that, contrary to the common lore, detectable annihilations occur even for large asymmetries, and derive bounds from the CMB, $\\gamma$-ray, neutrino and antiproton searches. We then identify the viable space for self-interacting DM. Direct detection does not exclude this scenario, but provides a way to test it.

Nonthermal Supermassive Dark Matter

Science.gov (United States)

Chung, Daniel J. H.; Kolb, Edward W.; Riotto, Antonio

1999-01-01

We discuss several cosmological production mechanisms for nonthermal supermassive dark matter and argue that dark matter may he elementary particles of mass much greater than the weak scale. Searches for dark matter should ma be limited to weakly interacting particles with mass of the order of the weak scale, but should extend into the supermassive range as well.

Nonthermal Supermassive Dark Matter

OpenAIRE

Chung, Daniel J. H.; Kolb, Edward W.; Riotto, Antonio

1998-01-01

We discuss several cosmological production mechanisms for nonthermal supermassive dark matter and argue that dark matter may be elementary particles of mass much greater than the weak scale. Searches for dark matter should not be limited to weakly interacting particles with mass of the order of the weak scale, but should extend into the supermassive range as well.

The Dark Matter of Biology.

Science.gov (United States)

Ross, Jennifer L

2016-09-06

The inside of the cell is full of important, yet invisible species of molecules and proteins that interact weakly but couple together to have huge and important effects in many biological processes. Such "dark matter" inside cells remains mostly hidden, because our tools were developed to investigate strongly interacting species and folded proteins. Example dark-matter species include intrinsically disordered proteins, posttranslational states, ion species, and rare, transient, and weak interactions undetectable by biochemical assays. The dark matter of biology is likely to have multiple, vital roles to regulate signaling, rates of reactions, water structure and viscosity, crowding, and other cellular activities. We need to create new tools to image, detect, and understand these dark-matter species if we are to truly understand fundamental physical principles of biology. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Light dark photon and fermionic dark radiation for the Hubble constant and the structure formation

OpenAIRE

Ko, P.; Tang, Yong

2018-01-01

Motivated by the tensions in the Hubble constant $H_0$ and the structure growth $\\sigma_8$ between $Planck$ results and other low redshift measurements, we discuss some cosmological effects of a dark sector model in which dark matter (DM) interacts with fermionic dark radiation (DR) through a light gauge boson (dark photon). Such kind of models are very generic in particle physics with a dark sector with dark gauge symmetries. The effective number of neutrinos is increased by $\\delta N_{eff} ...

Hidden charged dark matter

International Nuclear Information System (INIS)

Feng, Jonathan L.; Kaplinghat, Manoj; Tu, Huitzu; Yu, Hai-Bo

2009-01-01

Can dark matter be stabilized by charge conservation, just as the electron is in the standard model? We examine the possibility that dark matter is hidden, that is, neutral under all standard model gauge interactions, but charged under an exact (\\rm U)(1) gauge symmetry of the hidden sector. Such candidates are predicted in WIMPless models, supersymmetric models in which hidden dark matter has the desired thermal relic density for a wide range of masses. Hidden charged dark matter has many novel properties not shared by neutral dark matter: (1) bound state formation and Sommerfeld-enhanced annihilation after chemical freeze out may reduce its relic density, (2) similar effects greatly enhance dark matter annihilation in protohalos at redshifts of z ∼ 30, (3) Compton scattering off hidden photons delays kinetic decoupling, suppressing small scale structure, and (4) Rutherford scattering makes such dark matter self-interacting and collisional, potentially impacting properties of the Bullet Cluster and the observed morphology of galactic halos. We analyze all of these effects in a WIMPless model in which the hidden sector is a simplified version of the minimal supersymmetric standard model and the dark matter is a hidden sector stau. We find that charged hidden dark matter is viable and consistent with the correct relic density for reasonable model parameters and dark matter masses in the range 1 GeV ∼ X ∼< 10 TeV. At the same time, in the preferred range of parameters, this model predicts cores in the dark matter halos of small galaxies and other halo properties that may be within the reach of future observations. These models therefore provide a viable and well-motivated framework for collisional dark matter with Sommerfeld enhancement, with novel implications for astrophysics and dark matter searches

Interacting viscous entropy-corrected holographic scalar field models of dark energy with time-varying G in modified FRW cosmology

International Nuclear Information System (INIS)

Adabi, Farzin; Karami, Kayoomars; Felegary, Fereshte; Azarmi, Zohre

2012-01-01

We study the entropy-corrected version of the holographic dark energy (HDE) model in the framework of modified Friedmann-Robertson-Walker cosmology. We consider a non-flat universe filled with an interacting viscous entropy-corrected HDE (ECHDE) with dark matter. Also included in our model is the case of the variable gravitational constant G. We obtain the equation of state and the deceleration parameters of the interacting viscous ECHDE. Moreover, we reconstruct the potential and the dynamics of the quintessence, tachyon, K-essence and dilaton scalar field models according to the evolutionary behavior of the interacting viscous ECHDE model with time-varying G. (research papers)

Phases of cannibal dark matter

Energy Technology Data Exchange (ETDEWEB)

Farina, Marco [New High Energy Theory Center, Department of Physics, Rutgers University,136 Frelinghuisen Road, Piscataway, NJ 08854 (United States); Pappadopulo, Duccio; Ruderman, Joshua T.; Trevisan, Gabriele [Center for Cosmology and Particle Physics, Department of Physics, New York University,New York, NY 10003 (United States)

2016-12-13

A hidden sector with a mass gap undergoes an epoch of cannibalism if number changing interactions are active when the temperature drops below the mass of the lightest hidden particle. During cannibalism, the hidden sector temperature decreases only logarithmically with the scale factor. We consider the possibility that dark matter resides in a hidden sector that underwent cannibalism, and has relic density set by the freeze-out of two-to-two annihilations. We identify three novel phases, depending on the behavior of the hidden sector when dark matter freezes out. During the cannibal phase, dark matter annihilations decouple while the hidden sector is cannibalizing. During the chemical phase, only two-to-two interactions are active and the total number of hidden particles is conserved. During the one way phase, the dark matter annihilation products decay out of equilibrium, suppressing the production of dark matter from inverse annihilations. We map out the distinct phenomenology of each phase, which includes a boosted dark matter annihilation rate, new relativistic degrees of freedom, warm dark matter, and observable distortions to the spectrum of the cosmic microwave background.

Constraining dark photon model with dark matter from CMB spectral distortions

Directory of Open Access Journals (Sweden)

Ki-Young Choi

2017-08-01

Full Text Available Many extensions of Standard Model (SM include a dark sector which can interact with the SM sector via a light mediator. We explore the possibilities to probe such a dark sector by studying the distortion of the CMB spectrum from the blackbody shape due to the elastic scatterings between the dark matter and baryons through a hidden light mediator. We in particular focus on the model where the dark sector gauge boson kinetically mixes with the SM and present the future experimental prospect for a PIXIE-like experiment along with its comparison to the existing bounds from complementary terrestrial experiments.

Ultra-compact structure in radio quasars as a cosmological probe: a revised study of the interaction between cosmic dark sectors

Energy Technology Data Exchange (ETDEWEB)

Zheng, Xiaogang; Biesiada, Marek; Cao, Shuo; Qi, Jingzhao; Zhu, Zong-Hong, E-mail: zhengxg2012@mail.bnu.edu.cn, E-mail: marek.biesiada@us.edu.pl, E-mail: caoshuo@bnu.edu.cn, E-mail: 11132016039@bnu.edu.cn, E-mail: zhuzh@bnu.edu.cn [Department of Astronomy, Beijing Normal University, Beijing 100875 (China)

2017-10-01

A new compilation of 012 angular-size/redshift data for compact radio quasars from very-long-baseline interferometry (VLBI) surveys motivates us to revisit the interaction between dark energy and dark matter with these probes reaching high redshifts z ∼ 3.0. In this paper, we investigate observational constraints on different phenomenological interacting dark energy (IDE) models with the intermediate-luminosity radio quasars acting as individual standard rulers, combined with the newest BAO and CMB observation from Planck results acting as statistical rulers. The results obtained from the MCMC method and other statistical methods including figure of Merit and Information Criteria show that: (1) Compared with the current standard candle data and standard clock data, the intermediate-luminosity radio quasar standard rulers , probing much higher redshifts, could provide comparable constraints on different IDE scenarios. (2) The strong degeneracies between the interaction term and Hubble constant may contribute to alleviate the tension of H {sub 0} between the recent Planck and HST measurements. (3) Concerning the ranking of competing dark energy models, IDE with more free parameters are substantially penalized by the BIC criterion, which agrees very well with the previous results derived from other cosmological probes.

Dark matter and its detection

International Nuclear Information System (INIS)

Bi Xiaojun; Qin Bo

2011-01-01

We first explain the concept of dark matter,then review the history of its discovery and the evidence of its existence. We describe our understanding of the nature of dark matter particles, the popular dark matter models,and why the weakly interacting massive particles (called WIMPs) are the most attractive candidates for dark matter. Then we introduce the three methods of dark matter detection: colliders, direct detection and indirect detection. Finally, we review the recent development of dark matter detection, including the new results from DAMA, CoGent, PAMELA, ATIC and Fermi. (authors)

Constraining Dark Matter with ATLAS

CERN Document Server

Czodrowski, Patrick; The ATLAS collaboration

2017-01-01

The presence of a non-baryonic dark matter component in the Universe is inferred from the observation of its gravitational interaction. If dark matter interacts weakly with the Standard Model it would be produced at the LHC, escaping the detector and leaving a large missing transverse momentum as their signature. The ATLAS detector has developed a broad and systematic search program for dark matter production in LHC collisions. The results of these searches on the first 13 TeV data, their interpretation, and the design and possible evolution of the search program will be presented.

Dark matter and particle physics

International Nuclear Information System (INIS)

Peskin, Michael E.

2007-01-01

Astrophysicists now know that 80% of the matter in the universe is 'dark matter', composed of neutral and weakly interacting elementary particles that are not part of the Standard Model of particle physics. I will summarize the evidence for dark matter. I will explain why I expect dark matter particles to be produced at the CERN LHC. We will then need to characterize the new weakly interacting particles and demonstrate that they the same particles that are found in the cosmos. I will describe how this might be done. (author)

Dark matter, a hidden universe

International Nuclear Information System (INIS)

Trodden, M.; Feng, J.

2011-01-01

The main candidates to dark matter are particles called WIMPs for weakly interacting massive particles. 4 experiments (CDMS in Minnesota (Usa), DAMA at Gran Sasso (Italy), CoGeNT in Minnesota (Usa) and PAMELA onboard a Russian satellite) have claimed to have detected them. New clues suggest that it could exist new particles interacting via new forces. The observation that dwarf galaxies are systematically more spherical than massive galaxies might be a sign of the existence of new forces between dark matter components. Dark matter could not be as inert as previously thought. (A.C.)

Dissipative hidden sector dark matter

Science.gov (United States)

Foot, R.; Vagnozzi, S.

2015-01-01

A simple way of explaining dark matter without modifying known Standard Model physics is to require the existence of a hidden (dark) sector, which interacts with the visible one predominantly via gravity. We consider a hidden sector containing two stable particles charged under an unbroken U (1 )' gauge symmetry, hence featuring dissipative interactions. The massless gauge field associated with this symmetry, the dark photon, can interact via kinetic mixing with the ordinary photon. In fact, such an interaction of strength ε ˜10-9 appears to be necessary in order to explain galactic structure. We calculate the effect of this new physics on big bang nucleosynthesis and its contribution to the relativistic energy density at hydrogen recombination. We then examine the process of dark recombination, during which neutral dark states are formed, which is important for large-scale structure formation. Galactic structure is considered next, focusing on spiral and irregular galaxies. For these galaxies we modeled the dark matter halo (at the current epoch) as a dissipative plasma of dark matter particles, where the energy lost due to dissipation is compensated by the energy produced from ordinary supernovae (the core-collapse energy is transferred to the hidden sector via kinetic mixing induced processes in the supernova core). We find that such a dynamical halo model can reproduce several observed features of disk galaxies, including the cored density profile and the Tully-Fisher relation. We also discuss how elliptical and dwarf spheroidal galaxies could fit into this picture. Finally, these analyses are combined to set bounds on the parameter space of our model, which can serve as a guideline for future experimental searches.

Nonthermal Supermassive Dark Matter

International Nuclear Information System (INIS)

Chung, D.J.; Chung, D.J.; Kolb, E.W.; Kolb, E.W.; Riotto, A.

1998-01-01

We discuss several cosmological production mechanisms for nonthermal supermassive dark matter and argue that dark matter may be elementary particles of mass much greater than the weak scale. Searches for dark matter should not be limited to weakly interacting particles with mass of the order of the weak scale, but should extend into the supermassive range as well. copyright 1998 The American Physical Society

Asymmetric Dark Matter and Dark Radiation

International Nuclear Information System (INIS)

Blennow, Mattias; Martinez, Enrique Fernandez; Mena, Olga; Redondo, Javier; Serra, Paolo

2012-01-01

Asymmetric Dark Matter (ADM) models invoke a particle-antiparticle asymmetry, similar to the one observed in the Baryon sector, to account for the Dark Matter (DM) abundance. Both asymmetries are usually generated by the same mechanism and generally related, thus predicting DM masses around 5 GeV in order to obtain the correct density. The main challenge for successful models is to ensure efficient annihilation of the thermally produced symmetric component of such a light DM candidate without violating constraints from collider or direct searches. A common way to overcome this involves a light mediator, into which DM can efficiently annihilate and which subsequently decays into Standard Model particles. Here we explore the scenario where the light mediator decays instead into lighter degrees of freedom in the dark sector that act as radiation in the early Universe. While this assumption makes indirect DM searches challenging, it leads to signals of extra radiation at BBN and CMB. Under certain conditions, precise measurements of the number of relativistic species, such as those expected from the Planck satellite, can provide information on the structure of the dark sector. We also discuss the constraints of the interactions between DM and Dark Radiation from their imprint in the matter power spectrum

Gravity-mediated (or Composite) Dark Matter

CERN Document Server

Lee, Hyun Min; Sanz, Veronica

2014-01-01

Dark matter could have an electroweak origin, yet communicate with the visible sector exclusively through gravitational interactions. In a set-up addressing the hierarchy problem, we propose a new dark matter scenario where gravitational mediators, arising from the compactification of extra-dimensions, are responsible for dark matter interactions and its relic abundance in the Universe. We write an explicit example of this mechanism in warped extra-dimensions and work out its constraints. We also develop a dual picture of the model, based on a four-dimensional scenario with partial compositeness. We show that Gravity-mediated Dark Matter is equivalent to a mechanism of generating viable dark matter scenarios in a strongly-coupled, near-conformal theory, such as in composite Higgs models.

Gravitational probes of dark matter physics

OpenAIRE

Buckley, Matthew R.; Peter, Annika H. G.

2017-01-01

The nature of dark matter is one of the most pressing questions in particle physics. Yet all our present knowledge of the dark sector to date comes from its gravitational interactions with astrophysical systems. Moreover, astronomical results still have immense potential to constrain the particle properties of dark matter. We introduce a simple 2D parameter space which classifies models in terms of a particle physics interaction strength and a characteristic astrophysical scale on which new p...

Diurnal modulation signal from dissipative hidden sector dark matter

Directory of Open Access Journals (Sweden)

R. Foot

2015-09-01

Full Text Available We consider a simple generic dissipative dark matter model: a hidden sector featuring two dark matter particles charged under an unbroken U(1′ interaction. Previous work has shown that such a model has the potential to explain dark matter phenomena on both large and small scales. In this framework, the dark matter halo in spiral galaxies features nontrivial dynamics, with the halo energy loss due to dissipative interactions balanced by a heat source. Ordinary supernovae can potentially supply this heat provided kinetic mixing interaction exists with strength ϵ∼10−9. This type of kinetically mixed dark matter can be probed in direct detection experiments. Importantly, this self-interacting dark matter can be captured within the Earth and shield a dark matter detector from the halo wind, giving rise to a diurnal modulation effect. We estimate the size of this effect for detectors located in the Southern hemisphere, and find that the modulation is large (≳10% for a wide range of parameters.

Nearly Supersymmetric Dark Atoms

Energy Technology Data Exchange (ETDEWEB)

Behbahani, Siavosh R.; Jankowiak, Martin; /SLAC /Stanford U., ITP; Rube, Tomas; /Stanford U., ITP; Wacker, Jay G.; /SLAC /Stanford U., ITP

2011-08-12

Theories of dark matter that support bound states are an intriguing possibility for the identity of the missing mass of the Universe. This article proposes a class of models of supersymmetric composite dark matter where the interactions with the Standard Model communicate supersymmetry breaking to the dark sector. In these models supersymmetry breaking can be treated as a perturbation on the spectrum of bound states. Using a general formalism, the spectrum with leading supersymmetry effects is computed without specifying the details of the binding dynamics. The interactions of the composite states with the Standard Model are computed and several benchmark models are described. General features of non-relativistic supersymmetric bound states are emphasized.

Dark discrete gauge symmetries

International Nuclear Information System (INIS)

Batell, Brian

2011-01-01

We investigate scenarios in which dark matter is stabilized by an Abelian Z N discrete gauge symmetry. Models are surveyed according to symmetries and matter content. Multicomponent dark matter arises when N is not prime and Z N contains one or more subgroups. The dark sector interacts with the visible sector through the renormalizable kinetic mixing and Higgs portal operators, and we highlight the basic phenomenology in these scenarios. In particular, multiple species of dark matter can lead to an unconventional nuclear recoil spectrum in direct detection experiments, while the presence of new light states in the dark sector can dramatically affect the decays of the Higgs at the Tevatron and LHC, thus providing a window into the gauge origin of the stability of dark matter.

Dark Matter's secret liaisons: phenomenology of a dark U(1) sector with bound states

Energy Technology Data Exchange (ETDEWEB)

Cirelli, Marco; Petraki, Kalliopi; Sala, Filippo [Laboratoire de Physique Théorique et Hautes Energies (LPTHE), UMR 7589 CNRS and UPMC, 4 Place Jussieu, F-75252, Paris (France); Panci, Paolo [CERN Theoretical Physics Department, CERN, Case C01600, CH-1211 Genève (Switzerland); Taoso, Marco, E-mail: marco.cirelli@gmail.com, E-mail: paolo.panci@cern.ch, E-mail: kpetraki@lpthe.jussieu.fr, E-mail: filo.sala@gmail.com, E-mail: m.taoso@csic.es [Instituto de Física Teórica (IFT) UAM/CSIC, calle Nicolás Cabrera 13-15, 28049 Cantoblanco, Madrid (Spain)

2017-05-01

Dark matter (DM) charged under a dark U(1) force appears in many extensions of the Standard Model, and has been invoked to explain anomalies in cosmic-ray data, as well as a self-interacting DM candidate. In this paper, we perform a comprehensive phenomenological analysis of such a model, assuming that the DM abundance arises from the thermal freeze-out of the dark interactions. We include, for the first time, bound-state effects both in the DM production and in the indirect detection signals, and quantify their importance for FERMI, AMS-02, and CMB experiments. We find that DM in the mass range 1 GeV to 100 TeV, annihilating into dark photons of MeV to GeV mass, is in conflict with observations. Instead, DM annihilation into heavier dark photons is viable. We point out that the late decays of multi-GeV dark photons can produce significant entropy and thus dilute the DM density. This can lower considerably the dark coupling needed to obtain the DM abundance, and in turn relax the existing constraints.

Probing dark matter self-interaction in the Sun with IceCube-PINGU

International Nuclear Information System (INIS)

Chen, Chian-Shu; Lee, Fei-Fan; Lin, Guey-Lin; Lin, Yen-Hsun

2014-01-01

We study the capture, annihilation and evaporation of dark matter (DM) inside the Sun. It has been shown that the DM self-interaction can increase the DM number inside the Sun. We demonstrate that this enhancement becomes more significant in the regime of small DM mass, given a fixed DM self-interaction cross section. This leads to the enhancement of neutrino flux from DM annihilation. On the other hand, for DM mass as low as as a few GeVs, not only the DM-nuclei scatterings can cause the DM evaporation, DM self-interaction also provides non-negligible contributions to this effect. Consequently, the critical mass for DM evaporation (typically 3 ∼ 4 GeV without the DM self-interaction) can be slightly increased. We discuss the prospect of detecting DM self-interaction in IceCube-PINGU using the annihilation channels χχ → τ + τ - , νν-bar as examples. The PINGU sensitivities to DM self-interaction cross section σ χχ are estimated for track and cascade events

Reexploration of interacting holographic dark energy model. Cases of interaction term excluding the Hubble parameter

Energy Technology Data Exchange (ETDEWEB)

Li, Hai-Li; Zhang, Jing-Fei; Feng, Lu [Northeastern University, Department of Physics, College of Sciences, Shenyang (China); Zhang, Xin [Northeastern University, Department of Physics, College of Sciences, Shenyang (China); Peking University, Center for High Energy Physics, Beijing (China)

2017-12-15

In this paper, we make a deep analysis for the five typical interacting holographic dark energy models with the interaction terms Q = 3βH{sub 0}ρ{sub de}, Q = 3βH{sub 0}ρ{sub c}, Q = 3βH{sub 0}(ρ{sub de} + ρ{sub c}), Q = 3βH{sub 0}√(ρ{sub de}ρ{sub c}), and Q = 3βH{sub 0}(ρ{sub de}ρ{sub c})/(ρ{sub de}+ρ{sub c}), respectively. We obtain observational constraints on these models by using the type Ia supernova data (the Joint Light-Curve Analysis sample), the cosmic microwave background data (Planck 2015 distance priors), the baryon acoustic oscillations data, and the direct measurement of the Hubble constant. We find that the values of χ{sub min}{sup 2} for all the five models are almost equal (around 699), indicating that the current observational data equally favor these IHDE models. In addition, a comparison with the cases of an interaction term involving the Hubble parameter H is also made. (orig.)

Axion mediated photon to dark photon mixing

Energy Technology Data Exchange (ETDEWEB)

Ejlli, Damian [Novosibirsk State University, Department of Physics, Novosibirsk (Russian Federation); Laboratori Nazionali del Gran Sasso, Theory Group, Assergi, L' Aquila (Italy)

2018-01-15

The interaction between the dark/mirror sector and the ordinary sector is considered, where the two sectors interact with each other by sharing the same QCD axion field. This feature makes the mixing between ordinary and dark/mirror photons in ordinary and dark electromagnetic fields possible. Perturbative solutions of the equations of motion describing the evolution of fields in ordinary and dark external magnetic fields are found. User-friendly quantities such as transition probability rates and Stokes parameters are derived. Possible astrophysical and cosmological applications of this model are suggested. (orig.)

How to distinguish dark energy and modified gravity?

International Nuclear Information System (INIS)

Wei Hao; Zhang Shuangnan

2008-01-01

The current accelerated expansion of our universe could be due to an unknown energy component (dark energy) or a modification of general relativity (modified gravity). In the literature it has been proposed that combining the probes of the cosmic expansion history and growth history can distinguish between dark energy and modified gravity. In this work, without invoking nontrivial dark energy clustering, we show that the possible interaction between dark energy and dark matter could make the interacting dark model and the modified gravity model indistinguishable. An explicit example is also given. Therefore, it is required to seek some complementary probes beyond the ones of cosmic expansion history and growth history.

Exploring the dark side of the Universe

International Nuclear Information System (INIS)

Das, Mala

2014-01-01

Astronomical observations show that about 95% of the energy density of the Universe cannot be accounted for in terms of mass and energy of which about 26.8% is considered to be dark matter. The detection of this dark matter is one of the major and interesting unsolved problems in Physics. There are many experiments running worldwide at different underground laboratories for the direct detection of dark matter, mainly WIMPs (Weakly Interacting Massive Particles), the most favoured candidate of dark matter. Direct detection experiments expect to detect the dark matter directly by measuring the small energy imparted to recoil nuclei in occasional dark matter interactions with detector, stationed at earth's laboratory. In the subsequent sections, the challenges of such experiments are discussed followed by the details on PICASSO/PICO dark matter search experiment at SNO Lab, activities related to this experiment at SINP and the future direction of dark matter experiments

Asymmetric dark matter

International Nuclear Information System (INIS)

Kaplan, David E.; Luty, Markus A.; Zurek, Kathryn M.

2009-01-01

We consider a simple class of models in which the relic density of dark matter is determined by the baryon asymmetry of the Universe. In these models a B-L asymmetry generated at high temperatures is transferred to the dark matter, which is charged under B-L. The interactions that transfer the asymmetry decouple at temperatures above the dark matter mass, freezing in a dark matter asymmetry of order the baryon asymmetry. This explains the observed relation between the baryon and dark matter densities for the dark matter mass in the range 5-15 GeV. The symmetric component of the dark matter can annihilate efficiently to light pseudoscalar Higgs particles a or via t-channel exchange of new scalar doublets. The first possibility allows for h 0 →aa decays, while the second predicts a light charged Higgs-like scalar decaying to τν. Direct detection can arise from Higgs exchange in the first model or a nonzero magnetic moment in the second. In supersymmetric models, the would-be lightest supersymmetric partner can decay into pairs of dark matter particles plus standard model particles, possibly with displaced vertices.

Particle Physics Foundations of Dark Matter, Dark Energy, and Inflation (2/3)

CERN Multimedia

CERN. Geneva

2012-01-01

Ninety-five percent of the present mass-energy density of the Universe is dark. Twenty-five percent is in the form of dark matter holding together galaxies and other large scale structures, and 70% is in the form of dark energy driving an accelerated expansion of the universe. Dark matter and dark energy cannot be explained within the standard model of particle physics. In the first lecture I will review the evidence for dark matter and the observations that point to an explanation in the form of cold dark matter. I will then describe the expected properties of a hypothetical Weakly-Interacting Massive Particle, or WIMP, and review experimental and observational approaches to test the hypothesis. Finally, I will discuss how the LHC might shed light on the problem. In the second lecture I will review the theoretical foundations and observational evidence that the dominant component of the present mass density of the Universe has a negative pressure, which leads to an accelerated expansion of the Universe...

Particle Physics Foundations of Dark Matter, Dark Energy, and Inflation (3/3)

CERN Multimedia

CERN. Geneva

2012-01-01

Ninety-five percent of the present mass-energy density of the Universe is dark. Twenty-five percent is in the form of dark matter holding together galaxies and other large scale structures, and 70% is in the form of dark energy driving an accelerated expansion of the universe. Dark matter and dark energy cannot be explained within the standard model of particle physics. In the first lecture I will review the evidence for dark matter and the observations that point to an explanation in the form of cold dark matter. I will then describe the expected properties of a hypothetical Weakly-Interacting Massive Particle, or WIMP, and review experimental and observational approaches to test the hypothesis. Finally, I will discuss how the LHC might shed light on the problem. In the second lecture I will review the theoretical foundations and observational evidence that the dominant component of the present mass density of the Universe has a negative pressure, which leads to an accelerated expansion of the Universe...

Particle Physics Foundations of Dark Matter, Dark Energy, and Inflation (1/3)

CERN Multimedia

CERN. Geneva

2012-01-01

Ninety-five percent of the present mass-energy density of the Universe is dark. Twenty-five percent is in the form of dark matter holding together galaxies and other large scale structures, and 70% is in the form of dark energy driving an accelerated expansion of the universe. Dark matter and dark energy cannot be explained within the standard model of particle physics. In the first lecture I will review the evidence for dark matter and the observations that point to an explanation in the form of cold dark matter. I will then describe the expected properties of a hypothetical Weakly-Interacting Massive Particle, or WIMP, and review experimental and observational approaches to test the hypothesis. Finally, I will discuss how the LHC might shed light on the problem. In the second lecture I will review the theoretical foundations and observational evidence that the dominant component of the present mass density of the Universe has a negative pressure, which leads to an accelerated expansion of the Universe...

Anisotropic interactions of a single spin and dark-spin spectroscopy in diamond

Science.gov (United States)

Epstein, R. J.; Mendoza, F. M.; Kato, Y. K.; Awschalom, D. D.

2005-11-01

Experiments on single nitrogen-vacancy (N-V) centres in diamond, which include electron spin resonance, Rabi oscillations, single-shot spin readout and two-qubit operations with a nearby13C nuclear spin, show the potential of this spin system for solid-state quantum information processing. Moreover, N-V centre ensembles can have spin-coherence times exceeding 50 μs at room temperature. We have developed an angle-resolved magneto-photoluminescence microscope apparatus to investigate the anisotropic electron-spin interactions of single N-V centres at room temperature. We observe negative peaks in the photoluminescence as a function of both magnetic-field magnitude and angle that are explained by coherent spin precession and anisotropic relaxation at spin-level anti-crossings. In addition, precise field alignment unmasks the resonant coupling to neighbouring `dark' nitrogen spins, otherwise undetected by photoluminescence. These results demonstrate the capability of our spectroscopic technique for measuring small numbers of dark spins by means of a single bright spin under ambient conditions.

Gravitational Waves from a Dark Phase Transition.

Science.gov (United States)

Schwaller, Pedro

2015-10-30

In this work, we show that a large class of models with a composite dark sector undergo a strong first order phase transition in the early Universe, which could lead to a detectable gravitational wave signal. We summarize the basic conditions for a strong first order phase transition for SU(N) dark sectors with n_{f} flavors, calculate the gravitational wave spectrum and show that, depending on the dark confinement scale, it can be detected at eLISA or in pulsar timing array experiments. The gravitational wave signal provides a unique test of the gravitational interactions of a dark sector, and we discuss the complementarity with conventional searches for new dark sectors. The discussion includes the twin Higgs and strongly interacting massive particle models as well as symmetric and asymmetric composite dark matter scenarios.

Ultrashort dark solitons interactions and nonlinear tunneling in the modified nonlinear Schrödinger equation with variable coefficient

Science.gov (United States)

Musammil, N. M.; Porsezian, K.; Nithyanandan, K.; Subha, P. A.; Tchofo Dinda, P.

2017-09-01

We present the study of the dark soliton dynamics in an inhomogeneous fiber by means of a variable coefficient modified nonlinear Schrödinger equation (Vc-MNLSE) with distributed dispersion, self-phase modulation, self-steepening and linear gain/loss. The ultrashort dark soliton pulse evolution and interaction is studied by using the Hirota bilinear (HB) method. In particular, we give much insight into the effect of self-steepening (SS) on the dark soliton dynamics. The study reveals a shock wave formation, as a major effect of SS. Numerically, we study the dark soliton propagation in the continuous wave background, and the stability of the soliton solution is tested in the presence of photon noise. The elastic collision behaviors of the dark solitons are discussed by the asymptotic analysis. On the other hand, considering the nonlinear tunneling of dark soliton through barrier/well, we find that the tunneling of the dark soliton depends on the height of the barrier and the amplitude of the soliton. The intensity of the tunneling soliton either forms a peak or valley and retains its shape after the tunneling. For the case of exponential background, the soliton tends to compress after tunneling through the barrier/well.

Production of Purely Gravitational Dark Matter

OpenAIRE

Ema, Yohei; Nakayama, Kazunori; Tang, Yong

2018-01-01

In the purely gravitational dark matter scenario, the dark matter particle does not have any interaction except for gravitational one. We study the gravitational particle production of dark matter particle in such a minimal setup and show that correct amount of dark matter can be produced depending on the inflation model and the dark matter mass. In particular, we carefully evaluate the particle production rate from the transition epoch to the inflaton oscillation epoch in a realistic inflati...

Conformal invariant powers of the Laplacian, Fefferman-Graham ambient metric and Ricci gauging

International Nuclear Information System (INIS)

Manvelyan, Ruben; Mkrtchyan, Karapet; Mkrtchyan, Ruben

2007-01-01

The hierarchy of conformally invariant kth powers of the Laplacian acting on a scalar field with scaling dimensions Δ (k) =k-d/2, k=1,2,3, as obtained in the recent work [R. Manvelyan, D.H. Tchrakian, Phys. Lett. B 644 (2007) 370, (hep-th/0611077)] is rederived using the Fefferman-Graham (d+2)-dimensional ambient space approach. The corresponding mysterious 'holographic' structure of these operators is clarified. We explore also the (d+2)-dimensional ambient space origin of the Ricci gauging procedure proposed by A. Iorio, L. O'Raifeartaigh, I. Sachs and C. Wiesendanger as another method of constructing the Weyl invariant Lagrangians. The corresponding gauged ambient metric, Fefferman-Graham expansion and extended Penrose-Brown-Henneaux transformations are proposed and analyzed

Dark Matter Detection: Current Status

International Nuclear Information System (INIS)

Akerib, Daniel S.

2011-01-01

Overwhelming observational evidence indicates that most of the matter in the Universe consists of non-baryonic dark matter. One possibility is that the dark matter is Weakly-Interacting Massive Particles (WIMPs) that were produced in the early Universe. These relics could comprise the Milky Way's dark halo and provide evidence for new particle physics, such as Supersymmetry. This talk focuses on the status of current efforts to detect dark matter by testing the hypothesis that WIMPs exist in the galactic halo. WIMP searches have begun to explore the region of parameter space where SUSY particles could provide dark matter candidates.

Is Large-Scale-Structure formation a new probe of the Dark Matter interactions with Standard Model particles?

CERN Multimedia

CERN. Geneva

2014-01-01

In the last few decades, there have been extensive efforts made to discover dark matter particles through a significant experimental program based on direct and indirect detection techniques. However so far these searches remain unsuccessful, thus questioning our ability to elucidate one of the biggest challenges of modern Cosmology. In this talk I will review some of the key aspects of these techniques and present a new strategy to characterise the dark matter interactions with the visible sector without having to rely on critical assumptions.

Dark matter and exotic neutrino interactions in direct detection searches

Energy Technology Data Exchange (ETDEWEB)

Bertuzzo, Enrico [Departamento de Física Matemática, Instituto de Física, Universidade de São Paulo,R. do Matão 1371, CEP. 05508-090, São Paulo (Brazil); Deppisch, Frank F. [Department of Physics and Astronomy, University College London,London WC1E 6BT (United Kingdom); Kulkarni, Suchita [Institut für Hochenergiephysik, Österreichische Akademie der Wissenschaften,Nikolsdorfer Gasse 18, 1050 Wien (Austria); Gonzalez, Yuber F. Perez; Funchal, Renata Zukanovich [Departamento de Física Matemática, Instituto de Física, Universidade de São Paulo,R. do Matão 1371, CEP. 05508-090, São Paulo (Brazil)

2017-04-12

We investigate the effect of new physics interacting with both Dark Matter (DM) and neutrinos at DM direct detection experiments. Working within a simplified model formalism, we consider vector and scalar mediators to determine the scattering of DM as well as the modified scattering of solar neutrinos off nuclei. Using existing data from LUX as well as the expected sensitivity of LUX-ZEPLIN and DARWIN, we set limits on the couplings of the mediators to quarks, neutrinos and DM. Given the current limits, we also assess the true DM discovery potential of direct detection experiments under the presence of exotic neutrino interactions. In the case of a vector mediator, we show that the DM discovery reach of future experiments is affected for DM masses m{sub χ}≲10 GeV or DM scattering cross sections σ{sub χ}≲10{sup −47} cm{sup 2}. On the other hand, a scalar mediator will not affect the discovery reach appreciably.

Dynamics and elastic interactions of the discrete multi-dark soliton solutions for the Kaup-Newell lattice equation

Science.gov (United States)

Liu, Nan; Wen, Xiao-Yong

2018-03-01

Under consideration in this paper is the Kaup-Newell (KN) lattice equation which is an integrable discretization of the KN equation. Infinitely, many conservation laws and discrete N-fold Darboux transformation (DT) for this system are constructed and established based on its Lax representation. Via the resulting N-fold DT, the discrete multi-dark soliton solutions in terms of determinants are derived from non-vanishing background. Propagation and elastic interaction structures of such solitons are shown graphically. Overtaking interaction phenomena between/among the two, three and four solitons are discussed. Numerical simulations are used to explore their dynamical behaviors of such multi-dark solitons. Numerical results show that their evolutions are stable against a small noise. Results in this paper might be helpful for understanding the propagation of nonlinear Alfvén waves in plasmas.

Review of dark photon searches

International Nuclear Information System (INIS)

Denig, Achim

2016-01-01

Dark Photons are hypothetical extra-U(1) gauge bosons, which are motivated by a number of astrophysical anomalies as well as the presently seen deviation between the Standard Model prediction and the direct measurement of the anomalous magnetic moment of the muon, (g − 2)μ. The Dark Photon does not serve as the Dark Matter particle itself, but acts as a messenger particle of a hypothetical Dark Sector with residual interaction to the Standard Model. We review recent Dark Photon searches, which were carried out in a global effort at various hadron and particle physics facilities. We also comment on the perspectives for future invisble searches, which directly probe the existence of Light Dark Matter particles.

Constraints on the coupling between dark energy and dark matter from CMB data

International Nuclear Information System (INIS)

Murgia, R.; Gariazzo, S.; Fornengo, N.

2016-01-01

We investigate a phenomenological non-gravitational coupling between dark energy and dark matter, where the interaction in the dark sector is parameterized as an energy transfer either from dark matter to dark energy or the opposite. The models are constrained by a whole host of updated cosmological data: cosmic microwave background temperature anisotropies and polarization, high-redshift supernovae, baryon acoustic oscillations, redshift space distortions and gravitational lensing. Both models are found to be compatible with all cosmological observables, but in the case where dark matter decays into dark energy, the tension with the independent determinations of H 0 and σ 8 , already present for standard cosmology, increases: this model in fact predicts lower H 0 and higher σ 8 , mostly as a consequence of the higher amount of dark matter at early times, leading to a stronger clustering during the evolution. Instead, when dark matter is fed by dark energy, the reconstructed values of H 0 and σ 8 nicely agree with their local determinations, with a full reconciliation between high- and low-redshift observations. A non-zero coupling between dark energy and dark matter, with an energy flow from the former to the latter, appears therefore to be in better agreement with cosmological data

The pursuit of dark matter at colliders—an overview

Science.gov (United States)

Penning, Björn

2018-06-01

Dark matter is one of the main puzzles in fundamental physics and the goal of a diverse, multi-pronged research programme. Underground and astrophysical searches look for dark matter particles in the cosmos, either by interacting directly or by searching for dark matter annihilation. Particle colliders, in contrast, might produce dark matter in the laboratory and are able to probe most basic dark-matter–matter interactions. They are sensitive to low dark matter masses, provide complementary information at higher masses and are subject to different systematic uncertainties. Collider searches are therefore an important part of an inter-disciplinary dark matter search strategy. This article highlights the experimental and phenomenological development in collider dark matter searches of recent years and their connection with the wider field.

Dark-photon search using data from CRESST-II Phase 2

Energy Technology Data Exchange (ETDEWEB)

Angloher, G.; Bauer, P.; Iachellini, N.F.; Hauff, D.; Kiefer, M.; Mancuso, M.; Petricca, F.; Proebst, F.; Seidel, W.; Stodolsky, L.; Strauss, R.; Tanzke, A.; Wuestrich, M. [Max-Planck-Institut fuer Physik, Munich (Germany); Bento, A. [Max-Planck-Institut fuer Physik, Munich (Germany); Universidade de Coimbra, Departamento de Fisica, Coimbra (Portugal); Bucci, C.; Gorla, P.; Pagliarone, C. [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Canonica, L. [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Massachusetts Institute of Technology, Cambridge, MA (United States); Defay, X.; Feilitzsch, F. v.; Lanfranchi, J.C.; Muenster, A.; Potzel, W.; Schoenert, S.; Thi, H.H.T.; Ulrich, A.; Wawoczny, S.; Willers, M.; Zoeller, A. [Technische Universitaet Muenchen, Physik-Department and Excellence Cluster Universe, Garching (Germany); Erb, A. [Technische Universitaet Muenchen, Physik-Department and Excellence Cluster Universe, Garching (Germany); Walther-Meissner-Institut fuer Tieftemperaturforschung, Garching (Germany); Guetlein, A.; Kluck, H.; Puig, R.; Schieck, J.; Tuerkoglu, C. [Institut fuer Hochenergiephysik der Oesterreichischen Akademie der Wissenschaften, Vienna (Austria); Atominstitut, Vienna University of Technology, Vienna (Austria); Jochum, J.; Loebell, J.; Strandhagen, C.; Uffinger, M.; Usherov, I. [Eberhard-Karls-Universitaet Tuebingen, Tuebingen (Germany); Kraus, H. [University of Oxford, Department of Physics, Oxford (United Kingdom); Reindl, F. [Max-Planck-Institut fuer Physik, Munich (Germany); INFN-Sezione di Roma, Rome (Italy); Schaeffner, K. [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); GSSI-Gran Sasso Science Institute, L' Aquila (Italy)

2017-05-15

Identifying the nature and origin of dark matter is one of the major challenges for modern astro and particle physics. Direct dark-matter searches aim at an observation of dark-matter particles interacting within detectors. The focus of several such searches is on interactions with nuclei as provided e.g. by weakly interacting massive particles. However, there is a variety of dark-matter candidates favoring interactions with electrons rather than with nuclei. One example are dark photons, i.e., long-lived vector particles with a kinetic mixing to standard-model photons. In this work we present constraints on this kinetic mixing based on data from CRESST-II Phase 2 corresponding to an exposure before cuts of 52 kg-days. These constraints improve the existing ones for dark-photon masses between 0.3 and 0.7 keV/c{sup 2}. (orig.)

Partner Symmetries, Group Foliation and ASD Ricci-Flat Metrics without Killing Vectors

Directory of Open Access Journals (Sweden)

Andrei A. Malykh

2013-11-01

Full Text Available We demonstrate how a combination of our recently developed methods of partner symmetries, symmetry reduction in group parameters and a new version of the group foliation method can produce noninvariant solutions of complex Monge-Ampère equation (CMA and provide a lift from invariant solutions of CMA satisfying Boyer-Finley equation to non-invariant ones. Applying these methods, we obtain a new noninvariant solution of CMA and the corresponding Ricci-flat anti-self-dual Einstein-Kähler metric with Euclidean signature without Killing vectors, together with Riemannian curvature two-forms. There are no singularities of the metric and curvature in a bounded domain if we avoid very special choices of arbitrary functions of a single variable in our solution. This metric does not describe gravitational instantons because the curvature is not concentrated in a bounded domain.

Constraining Dark Matter Interactions with Pseudoscalar and Scalar Mediators Using Collider Searches for Multijets plus Missing Transverse Energy.

Science.gov (United States)

Buchmueller, Oliver; Malik, Sarah A; McCabe, Christopher; Penning, Bjoern

2015-10-30

The monojet search, looking for events involving missing transverse energy (E_{T}) plus one or two jets, is the most prominent collider dark matter search. We show that multijet searches, which look for E_{T} plus two or more jets, are significantly more sensitive than the monojet search for pseudoscalar- and scalar-mediated interactions. We demonstrate this in the context of a simplified model with a pseudoscalar interaction that explains the excess in GeV energy gamma rays observed by the Fermi Large Area Telescope. We show that multijet searches already constrain a pseudoscalar interpretation of the excess in much of the parameter space where the mass of the mediator M_{A} is more than twice the dark matter mass m_{DM}. With the forthcoming run of the Large Hadron Collider at higher energies, the remaining regions of the parameter space where M_{A}>2m_{DM} will be fully explored. Furthermore, we highlight the importance of complementing the monojet final state with multijet final states to maximize the sensitivity of the search for the production of dark matter at colliders.

Searching dark matter at LHC

International Nuclear Information System (INIS)

Nojiri, Mihoko M.

2007-01-01

We now believe that the dark matter in our Universe must be an unknown elementary particle, which is charge neutral and weakly interacting. The standard model must be extended to include it. The dark matter was likely produced in the early universe from the high energy collisions of the particles. Now LHC experiment starting from 2008 will create such high energy collision to explore the nature of the dark matter. In this article we explain how dark matter and LHC physics will be connected in detail. (author)

Dynamics of quintessence models of dark energy with exponential coupling to dark matter

International Nuclear Information System (INIS)

Gonzalez, Tame; Leon, Genly; Quiros, Israel

2006-01-01

We explore quintessence models of dark energy which exhibit non-minimal coupling between the dark matter and dark energy components of the cosmic fluid. The kind of coupling chosen is inspired by scalar-tensor theories of gravity. We impose a suitable dynamics of the expansion allowing us to derive exact Friedmann-Robertson-Walker solutions once the coupling function is given as input. Self-interaction potentials of single and double exponential types emerge as a result of our choice of the coupling function. The stability and existence of the solutions are discussed in some detail. Although, in general, models with appropriate interaction between the components of the cosmic mixture are useful for handling the coincidence problem, in the present study this problem cannot be avoided due to the choice of solution generating ansatz

TeV scale singlet dark matter

International Nuclear Information System (INIS)

Ponton, Eduardo; Randall, Lisa

2009-01-01

It is well known that stable weak scale particles are viable dark matter candidates since the annihilation cross section is naturally about the right magnitude to leave the correct thermal residual abundance. Many dark matter searches have focused on relatively light dark matter consistent with weak couplings to the Standard Model. However, in a strongly coupled theory, or even if the coupling is just a few times bigger than the Standard Model couplings, dark matter can have TeV-scale mass with the correct thermal relic abundance. Here we consider neutral TeV-mass scalar dark matter, its necessary interactions, and potential signals. We consider signals both with and without higher-dimension operators generated by strong coupling at the TeV scale, as might happen for example in an RS scenario. We find some potential for detection in high energy photons that depends on the dark matter distribution. Detection in positrons at lower energies, such as those PAMELA probes, would be difficult though a higher energy positron signal could in principle be detectable over background. However, a light dark matter particle with higher-dimensional interactions consistent with a TeV cutoff can in principle match PAMELA data.

Astrophysical search strategies for accelerator blind dark matter

International Nuclear Information System (INIS)

Wells, J.D.

1998-04-01

A weakly interacting dark matter particle may be very difficult to discover at an accelerator because it either (1) is too heavy, (2) has no standard model gauge interactions, or (3) is almost degenerate with other states. In each of these cases, searches for annihilation products in the galactic halo are useful probes of dark matter properties. Using the example of supersymmetric dark matter, the author demonstrates how astrophysical searches for dark matter may provide discovery and mass information inaccessible to collider physics programs such as the Tevatron and LHC

A Search for weakly interacting dark matter particles with low temperature detectors capable of simultaneously measuring ionization and heat

Energy Technology Data Exchange (ETDEWEB)

Sonnenschein, Andrew Harry [UC, Santa Barbara

1999-01-01

Lots of gravitating material that doesn't emit or absorb light seems to be required in all sensible accounts of the dynamics of large-scale structures in the universe. The nature and extent of this mysterious "dark matter" has been one of the central puzzles in cosmology over the last decade. This dissertation describes an experiment that tests one possibility, that the dark matter is in the form of undiscovered Weakly Interacting Massive Particles (WIMPs) produced as a thermal relic of the big bang. In this chapter, we will review the most important observations that suggest the dark matter must exist and discuss the forms it could take.

Self-interacting dark matter and Higgs bosons in the SU(3)C x SU(3)L x U(1)N model with right-handed neutrinos

International Nuclear Information System (INIS)

Hoang Ngoc Long; Nguyen Quynh Lan

2003-05-01

We show that the SU(3) C x SU(3) L x U(1) N (3-3-1) model with right-handed neutrinos can provide candidates for self-interacting dark matter, namely they are the CP-even and odd Higgs bosons. These dark matters are stable without imposing of new symmetry and should be weak-interacting. (author)

The Dark Cube: dark character profiles and OCEAN

Directory of Open Access Journals (Sweden)

Danilo Garcia

2017-09-01

Full Text Available Background The Big Five traits (i.e., openness, conscientiousness, extraversion, agreeableness, and neuroticism: OCEAN have been suggested to provide a meaningful taxonomy for studying the Dark Triad: Machiavellianism, narcissism, and psychopathy. Nevertheless, current research consists of mixed and inconsistent associations between the Dark Triad and OCEAN. Here we used the Dark Cube (Garcia & Rosenberg, 2016, a model of malevolent character theoretically based on Cloninger’s biopsychosocial model of personality and in the assumption of a ternary structure of malevolent character. We use the dark cube profiles to investigate differences in OCEAN between individuals who differ in one dark character trait while holding the other two constant (i.e., conditional relationships. Method Participants (N = 330 responded to the Short Dark Triad Inventory and the Big Five Inventory and were grouped according to the eight possible combinations using their dark trait scores (M, high Machiavellianism; m, low Machiavellianism; N, high narcissism; n, low narcissism; P, high psychopathy; p, low psychopathy: MNP “maleficent”, MNp “manipulative narcissistic”, MnP “anti-social”, Mnp “Machiavellian”, mNP “psychopathic narcissistic”, mNp “narcissistic”, mnP “psychopathic”, and mnp “benevolent”. Results High narcissism-high extraversion and high psychopathy-low agreeableness were consistently associated across comparisons. The rest of the comparisons showed a complex interaction. For example, high Machiavellianism-high neuroticism only when both narcissism and psychopathy were low (Mnp vs. mnp, high narcissism-high conscientiousness only when both Machiavellianism and psychopathy were also high (MNP vs. MnP, and high psychopathy-high neuroticism only when Machiavellianism was low and narcissism was high (mNP vs. mNp. Conclusions We suggest that the Dark Cube is a useful tool in the investigation of a consistent Dark Triad Theory

The Dark Cube: dark character profiles and OCEAN.

Science.gov (United States)

Garcia, Danilo; González Moraga, Fernando R

2017-01-01

The Big Five traits (i.e., openness, conscientiousness, extraversion, agreeableness, and neuroticism: OCEAN) have been suggested to provide a meaningful taxonomy for studying the Dark Triad: Machiavellianism, narcissism, and psychopathy. Nevertheless, current research consists of mixed and inconsistent associations between the Dark Triad and OCEAN. Here we used the Dark Cube (Garcia & Rosenberg, 2016), a model of malevolent character theoretically based on Cloninger's biopsychosocial model of personality and in the assumption of a ternary structure of malevolent character. We use the dark cube profiles to investigate differences in OCEAN between individuals who differ in one dark character trait while holding the other two constant (i.e., conditional relationships). Participants ( N  = 330) responded to the Short Dark Triad Inventory and the Big Five Inventory and were grouped according to the eight possible combinations using their dark trait scores (M, high Machiavellianism; m, low Machiavellianism; N, high narcissism; n, low narcissism; P, high psychopathy; p, low psychopathy): MNP "maleficent", MNp "manipulative narcissistic", MnP "anti-social", Mnp "Machiavellian", mNP "psychopathic narcissistic", mNp "narcissistic", mnP "psychopathic", and mnp "benevolent". High narcissism-high extraversion and high psychopathy-low agreeableness were consistently associated across comparisons. The rest of the comparisons showed a complex interaction. For example, high Machiavellianism-high neuroticism only when both narcissism and psychopathy were low (Mnp vs. mnp), high narcissism-high conscientiousness only when both Machiavellianism and psychopathy were also high (MNP vs. MnP), and high psychopathy-high neuroticism only when Machiavellianism was low and narcissism was high (mNP vs. mNp). We suggest that the Dark Cube is a useful tool in the investigation of a consistent Dark Triad Theory. This approach suggests that the only clear relationships were narcissism

Dark-dark solitons for a coupled variable-coefficient higher-order nonlinear Schrödinger system in an inhomogeneous optical fiber

Science.gov (United States)

Li, Ming-Zhen; Tian, Bo; Qu, Qi-Xing; Chai, Han-Peng; Liu, Lei; Du, Zhong

2017-12-01

In this paper, under investigation is a coupled variable-coefficient higher-order nonlinear Schrödinger system, which describes the simultaneous propagation of optical pulses in an inhomogeneous optical fiber. Based on the Lax pair and binary Darboux transformation, we present the nondegenerate N-dark-dark soliton solutions. With the graphical simulation, soliton propagation and interaction are discussed with the group velocity dispersion and fourth-order dispersion effects, which affect the velocity but have no effect on the amplitude. Linear, parabolic and periodic one dark-dark solitons are displayed. Interactions between the two solitons are presented as well, which are all elastic.

Search for Dark Photons with Accelerators

Directory of Open Access Journals (Sweden)

Merkel Harald

2014-01-01

Full Text Available A dark photon as the mediator of an interaction of the dark sector is a well motivated extension of the standard model. While possible dark matter particles are heavy and seem to be beyond the reach of current accelerators, the dark photon is not necessarily heavy and might have a mass in the range of existing accelerators. In recent years, an extensive experimental program at several accelerators for the search for dark photons were established. In this talk, recent results and progress in the determination of exclusion limits with accelerators is presented.

Dark energy with a gradient coupling to the dark matter fluid: cosmological dynamics and structure formation

Science.gov (United States)

Dutta, Jibitesh; Khyllep, Wompherdeiki; Tamanini, Nicola

2018-01-01

We consider scalar field models of dark energy interacting with dark matter through a coupling proportional to the contraction of the four-derivative of the scalar field with the four-velocity of the dark matter fluid. The coupling is realized at the Lagrangian level employing the formalism of Scalar-Fluid theories, which use a consistent Lagrangian approach for relativistic fluid to describe dark matter. This framework produces fully covariant field equations, from which we can derive unequivocal cosmological equations at both background and linear perturbations levels. The background evolution is analyzed in detail applying dynamical systems techniques, which allow us to find the complete asymptotic behavior of the universe given any set of model parameters and initial conditions. Furthermore we study linear cosmological perturbations investigating the growth of cosmic structures within the quasi-static approximation. We find that these interacting dark energy models give rise to interesting phenomenological dynamics, including late-time transitions from dark matter to dark energy domination, matter and accelerated scaling solutions and dynamical crossing of the phantom barrier. Moreover we obtain possible deviations from standard ΛCDM behavior at the linear perturbations level, which have an impact on the dynamics of structure formation and might provide characteristic observational signatures.

Dark Matter searches with the ATLAS Detector

CERN Document Server

Ippolito, Valerio; The ATLAS collaboration

2017-01-01

The presence of a non-baryonic Dark Matter component in the Universe is inferred from the observation of its gravitational interaction. If Dark Matter interacts weakly with the Standard Model particles it may be produced at the Large Hadron Collider (LHC), escaping detection and leaving large missing transverse momentum as its signature. New results from the Dark Matter search programme of the ATLAS experiment are presented, based on LHC proton-proton collision data collected at a center-of-mass energy of 13 TeV.

R2 dark energy in the laboratory

Science.gov (United States)

Brax, Philippe; Valageas, Patrick; Vanhove, Pierre

2018-05-01

We analyze the role, on large cosmological scales and laboratory experiments, of the leading curvature squared contributions to the low-energy effective action of gravity. We argue for a natural relationship c0λ2≃1 at low energy between the R2 coefficients c0 of the Ricci scalar squared term in this expansion and the dark energy scale Λ =(λ MPl)4 in four-dimensional Planck mass units. We show how the compatibility between the acceleration of the expansion rate of the Universe, local tests of gravity and the quantum stability of the model all converge to select such a relationship up to a coefficient which should be determined experimentally. When embedding this low-energy theory of gravity into candidates for its ultraviolet completion, we find that the proposed relationship is guaranteed in string-inspired supergravity models with modulus stabilization and supersymmetry breaking leading to de Sitter compactifications. In this case, the scalar degree of freedom of R2 gravity is associated to a volume modulus. Once written in terms of a scalar-tensor theory, the effective theory corresponds to a massive scalar field coupled with the universal strength β =1 /√{6 } to the matter stress-energy tensor. When the relationship c0λ2≃1 is realized, we find that on astrophysical scales and in cosmology the scalar field is ultralocal and therefore no effect arises on such large scales. On the other hand, the scalar field mass is tightly constrained by the nonobservation of fifth forces in torsion pendulum experiments such as Eöt-Wash. It turns out that the observation of the dark energy scale in cosmology implies that the scalar field could be detectable by fifth-force experiments in the near future.

Window in the dark matter exclusion limits

International Nuclear Information System (INIS)

Zaharijas, Gabrijela; Farrar, Glennys R.

2005-01-01

We consider the cross section limits for light dark matter cadnidates (m=0.4 to 10 GeV). We calculate the interaction of dark matter in the crust above underground dark matter detectors and find that in the intermediate cross section range, the energy loss of dark matter is sufficient to fall below the energy threshold of current underground experiments. This implies the existence of a window in the dark matter exclusion limits in the micro-barn range

Modelling non-linear effects of dark energy

Science.gov (United States)

Bose, Benjamin; Baldi, Marco; Pourtsidou, Alkistis

2018-04-01

We investigate the capabilities of perturbation theory in capturing non-linear effects of dark energy. We test constant and evolving w models, as well as models involving momentum exchange between dark energy and dark matter. Specifically, we compare perturbative predictions at 1-loop level against N-body results for four non-standard equations of state as well as varying degrees of momentum exchange between dark energy and dark matter. The interaction is modelled phenomenologically using a time dependent drag term in the Euler equation. We make comparisons at the level of the matter power spectrum and the redshift space monopole and quadrupole. The multipoles are modelled using the Taruya, Nishimichi and Saito (TNS) redshift space spectrum. We find perturbation theory does very well in capturing non-linear effects coming from dark sector interaction. We isolate and quantify the 1-loop contribution coming from the interaction and from the non-standard equation of state. We find the interaction parameter ξ amplifies scale dependent signatures in the range of scales considered. Non-standard equations of state also give scale dependent signatures within this same regime. In redshift space the match with N-body is improved at smaller scales by the addition of the TNS free parameter σv. To quantify the importance of modelling the interaction, we create mock data sets for varying values of ξ using perturbation theory. This data is given errors typical of Stage IV surveys. We then perform a likelihood analysis using the first two multipoles on these sets and a ξ=0 modelling, ignoring the interaction. We find the fiducial growth parameter f is generally recovered even for very large values of ξ both at z=0.5 and z=1. The ξ=0 modelling is most biased in its estimation of f for the phantom w=‑1.1 case.

Simplified phenomenology for colored dark sectors

Energy Technology Data Exchange (ETDEWEB)

Hedri, Sonia El; Kaminska, Anna; Vries, Maikel de [PRISMA Cluster of Excellence & Mainz Institute for Theoretical Physics,Johannes Gutenberg University,55099 Mainz (Germany); Zurita, Jose [Institute for Nuclear Physics (IKP), Karlsruhe Institute of Technology,Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Institute for Theoretical Particle Physics (TTP), Karlsruhe Institute of Technology,Engesserstraße 7, D-76128 Karlsruhe (Germany)

2017-04-20

We perform a general study of the relic density and LHC constraints on simplified models where the dark matter coannihilates with a strongly interacting particle X. In these models, the dark matter depletion is driven by the self-annihilation of X to pairs of quarks and gluons through the strong interaction. The phenomenology of these scenarios therefore only depends on the dark matter mass and the mass splitting between dark matter and X as well as the quantum numbers of X. In this paper, we consider simplified models where X can be either a scalar, a fermion or a vector, as well as a color triplet, sextet or octet. We compute the dark matter relic density constraints taking into account Sommerfeld corrections and bound state formation. Furthermore, we examine the restrictions from thermal equilibrium, the lifetime of X and the current and future LHC bounds on X pair production. All constraints are comprehensively presented in the mass splitting versus dark matter mass plane. While the relic density constraints can lead to upper bounds on the dark matter mass ranging from 2 TeV to more than 10 TeV across our models, the prospective LHC bounds range from 800 to 1500 GeV. A full coverage of the strongly coannihilating dark matter parameter space would therefore require hadron colliders with significantly higher center-of-mass energies.

Dark matter model with non-Abelian gauge symmetry

International Nuclear Information System (INIS)

Zhang Hao; Li Chongsheng; Cao Qinghong; Li Zhao

2010-01-01

We propose a dark-matter model in which the dark sector is gauged under a new SU(2) group. The dark sector consists of SU(2) dark gauge fields, two triplet dark Higgs fields, and two dark fermion doublets (dark-matter candidates in this model). The dark sector interacts with the standard model sector through kinetic and mass mixing operators. The model explains both PAMELA and Fermi LAT data very well and also satisfies constraints from both the dark-matter relic density and standard model precision observables. The phenomenology of the model at the LHC is also explored.

Dark matter wants Linear Collider

International Nuclear Information System (INIS)

Matsumoto, S.; Asano, M.; Fujii, K.; Takubo, Y.; Honda, T.; Saito, T.; Yamamoto, H.; Humdi, R.S.; Ito, H.; Kanemura, S; Nabeshima, T.; Okada, N.; Suehara, T.

2011-01-01

One of the main purposes of physics at the International Linear Collider (ILC) is to study the property of dark matter such as its mass, spin, quantum numbers, and interactions with particles of the standard model. We discuss how the property can or cannot be investigated at the ILC using two typical cases of dark matter scenario: 1) most of new particles predicted in physics beyond the standard model are heavy and only dark matter is accessible at the ILC, and 2) not only dark matter but also other new particles are accessible at the ILC. We find that, as can be easily imagined, dark matter can be detected without any difficulties in the latter case. In the former case, it is still possible to detect dark matter when the mass of dark matter is less than a half mass of the Higgs boson.

Dark matter searches with the ATLAS detector

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00379232; The ATLAS collaboration

2017-01-01

The presence of a non-baryonic dark matter component in the Universe is inferred from the observation of its gravitational interaction. If dark matter interacts weakly with the Standard Model it would be produced at the LHC, escaping the detector and leaving a large missing transverse momentum as its signature. The ATLAS detector has developed a broad and systematic search program for dark matter production in LHC collisions. The results of these searches on the first 13 TeV data, their interpretation, and the design and possible evolution of the search program will be presented.

Dark Matter searches with the ATLAS Detector

CERN Document Server

Cortes-Gonzalez, Arely; The ATLAS collaboration

2017-01-01

The presence of a non-baryonic dark matter component in the Universe is inferred from the observation of its gravitational interaction. If dark matter interacts weakly with the Standard Model it would be produced at the LHC, escaping the detector and leaving a large missing transverse momentum as their signature. The ATLAS detector has developed a broad and systematic search program for dark matter production in LHC collisions. The results of these searches on the first 13 TeV data, their interpretation, and the design and possible evolution of the search program will be presented.

Dark matter searches with the ATLAS detector

CERN Document Server

Whalen, Kathleen; The ATLAS collaboration

2017-01-01

The presence of a non-baryonic dark matter component in the Universe is inferred from the observation of its gravitational interaction. If dark matter interacts weakly with the Standard Model it would be produced at the LHC, escaping the detector and leaving a large missing transverse momentum as its signature. The ATLAS detector has developed a broad and systematic search program for dark matter production in LHC collisions. The results of these searches using the first 13 TeV data, their interpretation, and the design and possible evolution of the search program will be presented.

The dark cube: dark and light character profiles

Directory of Open Access Journals (Sweden)

Danilo Garcia

2016-02-01

Full Text Available Background. Research addressing distinctions and similarities between people’s malevolent character traits (i.e., the Dark Triad: Machiavellianism, narcissism, and psychopathy has detected inconsistent linear associations to temperament traits. Additionally, these dark traits seem to have a common core expressed as uncooperativeness. Hence, some researchers suggest that the dark traits are best represented as one global construct (i.e., the unification argument rather than as ternary construct (i.e., the uniqueness argument. We put forward the dark cube (cf. Cloninger’s character cube comprising eight dark profiles that can be used to compare individuals who differ in one dark character trait while holding the other two constant. Our aim was to investigate in which circumstances individuals who are high in each one of the dark character traits differ in Cloninger’s “light” character traits: self-directedness, cooperativeness, and self-transcendence. We also investigated if people’s dark character profiles were associated to their light character profiles. Method. A total of 997 participants recruited from Amazon’s Mechanical Turk (MTurk responded to the Short Dark Triad and the Short Character Inventory. Participants were allocated to eight different dark profiles and eight light profiles based on their scores in each of the traits and any possible combination of high and low scores. We used three-way interaction regression analyses and t-tests to investigate differences in light character traits between individuals with different dark profiles. As a second step, we compared the individuals’ dark profile with her/his character profile using an exact cell-wise analysis conducted in the ROPstat software (http://www.ropstat.com. Results. Individuals who expressed high levels of Machiavellianism and those who expressed high levels of psychopathy also expressed low self-directedness and low cooperativeness. Individuals with high

WISPy cold dark matter

Energy Technology Data Exchange (ETDEWEB)

Arias, Paola [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Pontificia Univ. Catolica de Chile, Santiago (Chile). Facultad de Fisica; Cadamuro, Davide; Redondo, Javier [Max-Planck-Institut fuer Physik, Muenchen (Germany); Goodsell, Mark [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); European Organization for Nuclear Research (CERN), Geneva (Switzerland); Jaeckel, Joerg [Durham Univ. (United Kingdom). Inst. for Particle Physics Phenomenology; Ringwald, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2012-01-15

Very weakly interacting slim particles (WISPs), such as axion-like particles (ALPs) or hidden photons (HPs), may be non-thermally produced via the misalignment mechanism in the early universe and survive as a cold dark matter population until today. We find that, both for ALPs and HPs whose dominant interactions with the standard model arise from couplings to photons, a huge region in the parameter spaces spanned by photon coupling and ALP or HP mass can give rise to the observed cold dark matter. Remarkably, a large region of this parameter space coincides with that predicted in well motivated models of fundamental physics. A wide range of experimental searches - exploiting haloscopes (direct dark matter searches exploiting microwave cavities), helioscopes (searches for solar ALPs or HPs), or light-shining-through-a-wall techniques - can probe large parts of this parameter space in the foreseeable future. (orig.)

Analysis of pilgrim dark energy models

Energy Technology Data Exchange (ETDEWEB)

Sharif, M.; Jawad, Abdul [University of the Punjab, Department of Mathematics, Lahore (Pakistan)

2013-04-15

The proposal of pilgrim dark energy is based on the idea that phantom dark energy possesses enough resistive force to preclude black hole formation. We work on this proposal by choosing an interacting framework with cold dark matter and three cutoffs such as Hubble as well as event horizon and conformal age of the universe. We present a graphical analysis and focus our study on the pilgrim dark energy as well as interacting parameters. It is found that these parameters play an effective role on the equation of state parameter for exploring the phantom region of the universe. We also make the analysis of {omega}-{omega}' and point out freezing region in the {omega}-{omega}' plane. Finally, it turns out that the {Lambda}CDM is achieved in the statefinders plane for all models. (orig.)

An intermediate framework between WIMP, FIMP, and EWIP dark matter

International Nuclear Information System (INIS)

Yaguna, Carlos E.

2012-01-01

WIMP (Weakly Interacting Massive Particle), FIMP (Feebly interacting Massive Particle) and EWIP (Extremely Weakly Interacting Particle) dark matter are different theoretical frameworks that have been postulated to explain the dark matter. In this paper we examine an intermediate scenario that combines features from these three frameworks. It consists of a weakly interacting particle — à la WIMP — that does not reach thermal equilibrium in the early Universe — à la FIMP — and whose relic density is determined by the reheating temperature of the Universe — à la EWIP. As an example, an explicit realization of this framework, based on the singlet scalar model of dark matter, is analyzed in detail. In particular, the relic density is studied as a function of the parameters of the model, and the new viable region within this intermediate scenario is determined. Finally, it is shown that this alternative framework of dark matter allows for arbitrarily heavy dark matter particles and that it suggests a connection between dark matter and inflation

Dynamics of teleparallel dark energy

International Nuclear Information System (INIS)

Wei Hao

2012-01-01

Recently, Geng et al. proposed to allow a non-minimal coupling between quintessence and gravity in the framework of teleparallel gravity, motivated by the similar one in the framework of General Relativity (GR). They found that this non-minimally coupled quintessence in the framework of teleparallel gravity has a richer structure, and named it “teleparallel dark energy”. In the present work, we note that there might be a deep and unknown connection between teleparallel dark energy and Elko spinor dark energy. Motivated by this observation and the previous results of Elko spinor dark energy, we try to study the dynamics of teleparallel dark energy. We find that there exist only some dark-energy-dominated de Sitter attractors. Unfortunately, no scaling attractor has been found, even when we allow the possible interaction between teleparallel dark energy and matter. However, we note that w at the critical points is in agreement with observations (in particular, the fact that w=−1 independently of ξ is a great advantage).

Sebastiano Ricci impresario in angustie a Venezia: i guai della stagione 1718-1719 al Sant’Angelo

Directory of Open Access Journals (Sweden)

Gianluca Stefani

2016-06-01

Full Text Available Sebastiano Ricci was not only one of the greatest painters of the 18th century, but an active impresario in the Venetian opera houses at the beginning of the early 18th century. Thanks to the rediscovery of some notarial and judicial documents in the Archivio di Stato of Venice, we can reconstruct the circumstances under which he became manager of the Teatro di Sant’Angelo in the season 1718-1719, a season marked by his succession to the previous impresario Antonio Moretti (known as Modotto and by his legal dispute with the violinists Giovan Battista and Ludovico Madonis at the tribunal ‘del Forestier’.

The dark universe dark matter and dark energy

CERN Multimedia

CERN. Geneva

2008-01-01

According to the standard cosmological model, 95% of the present mass density of the universe is dark: roughly 70% of the total in the form of dark energy and 25% in the form of dark matter. In a series of four lectures, I will begin by presenting a brief review of cosmology, and then I will review the observational evidence for dark matter and dark energy. I will discuss some of the proposals for dark matter and dark energy, and connect them to high-energy physics. I will also present an overview of an observational program to quantify the properties of dark energy.

Bound-state formation for thermal relic dark matter and unitarity

International Nuclear Information System (INIS)

Harling, Benedict von; Petraki, Kalliopi

2014-01-01

We show that the relic abundance of thermal dark matter annihilating via a long-range interaction, is significantly affected by the formation and decay of dark matter bound states in the early universe, if the dark matter mass is above a few TeV . We determine the coupling required to obtain the observed dark matter density, taking into account both the direct 2-to-2 annihilations and the formation of bound states, and provide an analytical fit. We argue that the unitarity limit on the inelastic cross-section is realized only if dark matter annihilates via a long-range interaction, and we determine the upper bound on the mass of thermal-relic dark matter to be about 197 (139) TeV for (non)-self-conjugate dark matter

Prospects for direct detection of dark matter in an effective theory approach

International Nuclear Information System (INIS)

Catena, Riccardo

2014-01-01

We perform the first comprehensive analysis of the prospects for direct detection of dark matter with future ton-scale detectors in the general 11-dimensional effective theory of isoscalar dark matter-nucleon interactions mediated by a heavy spin-1 or spin-0 particle. The theory includes 8 momentum and velocity dependent dark matter-nucleon interaction operators, besides the familiar spin-independent and spin-dependent operators. From a variegated sample of 27 benchmark points selected in the parameter space of the theory, we simulate independent sets of synthetic data for ton-scale Germanium and Xenon detectors. From the synthetic data, we then extract the marginal posterior probability density functions and the profile likelihoods of the model parameters. The associated Bayesian credible regions and frequentist confidence intervals allow us to assess the prospects for direct detection of dark matter at the 27 benchmark points. First, we analyze the data assuming the knowledge of the correct dark matter nucleon-interaction type, as it is commonly done for the familiar spin-independent and spin-dependent interactions. Then, we analyze the simulations extracting the dark matter-nucleon interaction type from the data directly, in contrast to standard analyses. This second approach requires an extensive exploration of the full 11-dimensional parameter space of the dark matter-nucleon effective theory. Interestingly, we identify 5 scenarios where the dark matter mass and the dark matter-nucleon interaction type can be reconstructed from the data simultaneously. We stress the importance of extracting the dark matter nucleon-interaction type from the data directly, discussing the main challenges found addressing this complex 11-dimensional problem

Higgs production as a probe of dark energy interactions

CERN Document Server

Brax, Philippe; Davis, Anne-Christine; Seery, David; Weltman, Amanda

2010-01-01

We study Higgs production under the influence of a light, scalar dark energy field with chameleon-like couplings to matter. Our analysis is relevant for hadron colliders, such as the Large Hadron Collider, which are expected to manufacture Higgs particles through weak boson fusion, or associated production with a Z or W. We show that the corrections arising in these models are too small to be observed. This result can be attributed to the gauge invariance of the low energy Lagrangian. As a by-product of our analysis, we provide the first microphysical realization of a dark energy model coupled to the electromagnetic field strength. In models where dark energy couples to all matter species in a uniform manner we are able to give a new, stringent bound on its coupling strength.

Higgs production as a probe of dark energy interactions

International Nuclear Information System (INIS)

Brax, Philippe; Davis, Anne-Christine; Seery, David

2009-11-01

We study Higgs production under the influence of a light, scalar dark energy field with chameleon-like couplings to matter. Our analysis is relevant for hadron colliders, such as the Large Hadron Collider, which are expected to manufacture Higgs particles through weak boson fusion, or associated production with a Z or W ± . We show that the corrections arising in these models are too small to be observed. This result can be attributed to the gauge invariance of the low energy Lagrangian. As a by-product of our analysis, we provide the first microphysical realization of a dark energy model coupled to the electromagnetic field strength. In models where dark energy couples to all matter species in a uniform manner we are able to give a new, stringent bound on its coupling strength. (orig.)

Higgs production as a probe of dark energy interactions

Energy Technology Data Exchange (ETDEWEB)

Brax, Philippe [CEA, IPhT, CNRS, URA2306, Gif-sur-Yvette (France). Inst. de Physique Theorique; Burrage, Clare [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Davis, Anne-Christine; Seery, David [Cambridge Univ. (United Kingdom). Dept. of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences; Weltmann, Amanda [Cambridge Univ. (United Kingdom). Dept. of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences; Cape Town Univ. (South Africa). Dept. of Mathematics and Applied Mathematics; Centre for Theoretical Cosmology Fellow, Cambridge (United Kingdom)

2009-11-15

We study Higgs production under the influence of a light, scalar dark energy field with chameleon-like couplings to matter. Our analysis is relevant for hadron colliders, such as the Large Hadron Collider, which are expected to manufacture Higgs particles through weak boson fusion, or associated production with a Z or W{sup {+-}}. We show that the corrections arising in these models are too small to be observed. This result can be attributed to the gauge invariance of the low energy Lagrangian. As a by-product of our analysis, we provide the first microphysical realization of a dark energy model coupled to the electromagnetic field strength. In models where dark energy couples to all matter species in a uniform manner we are able to give a new, stringent bound on its coupling strength. (orig.)

Direct Detection Phenomenology in Models Where the Products of Dark Matter Annihilation Interact with Nuclei

DEFF Research Database (Denmark)

Cherry, John F.; Frandsen, Mads T.; Shoemaker, Ian M.

2015-01-01

We investigate the direct detection phenomenology of a class of dark matter (DM) models in which DM does not directly interact with nuclei, {but rather} the products of its annihilation do. When these annihilation products are very light compared to the DM mass, the scattering in direct detection...... to nuclei, the limit from annihilation to relativistic particles in the Sun can be stronger than that of conventional non-relativistic direct detection by more than three orders of magnitude for masses in a 2-7 GeV window.......We investigate the direct detection phenomenology of a class of dark matter (DM) models in which DM does not directly interact with nuclei, {but rather} the products of its annihilation do. When these annihilation products are very light compared to the DM mass, the scattering in direct detection...... experiments is controlled by relativistic kinematics. This results in a distinctive recoil spectrum, a non-standard and or even absent annual modulation, and the ability to probe DM masses as low as a $\\sim$10 MeV. We use current LUX data to show that experimental sensitivity to thermal relic annihilation...

DarkSide-50, a background free experiment for dark matter searches

International Nuclear Information System (INIS)

Bossa, M

2014-01-01

The existence of dark matter is inferred from gravitational effects, but its nature remains a deep mystery. One possibility, motivated by considerations in elementary particle physics, is that dark matter consists of elementary particles, such as the hypothesized Weakly Interacting Massive Particles (WIMPs), with mass ∼ 100 GeV and cross-section ∼ 10 −47 cm 2 , that can be gravitationally trapped inside our galaxy and revealed by their scattering on nuclei. It should be possible to detect WIMPs directly, as the orbital motion of the WIMPs composing the dark matter halo pervading the galaxy should result in WIMP-nucleus collisions of sufficient energy to be observable in the laboratory. The DarkSide-50 experiment is a direct WIMP search using a Liquid Argon Time Projection Chamber (LAr-TPC) with an active mass of 50 kg with a high sensitivity and an ultra-low background detector

Observation of attraction between dark solitons

DEFF Research Database (Denmark)

Dreischuh, A.; Neshev, D.N.; Petersen, D.E.

2006-01-01

We demonstrate a dramatic change in the interaction forces between dark solitons in nonlocal nonlinear media. We present what we believe is the first experimental evidence of attraction of dark solitons. Our results indicate that attraction should be observable in other nonlocal systems...

Scalar dark matter in the B−L model

International Nuclear Information System (INIS)

Rodejohann, Werner; Yaguna, Carlos E.

2015-01-01

The U(1) B−L extension of the Standard Model requires the existence of right-handed neutrinos and naturally realizes the seesaw mechanism of neutrino mass generation. We study the possibility of explaining the dark matter in this model with an additional scalar field, ϕ DM , that is a singlet of the Standard Model but charged under U(1) B−L . An advantage of this scenario is that the stability of ϕ DM can be guaranteed by appropriately choosing its B−L charge, without the need of an extra ad hoc discrete symmetry. We investigate in detail the dark matter phenomenology of this model. We show that the observed dark matter density can be obtained via gauge or scalar interactions, and that semi-annihilations could play an important role in the latter case. The regions consistent with the dark matter density are determined in each instance and the prospects for detection in future experiments are analyzed. If dark matter annihilations are controlled by the B−L gauge interaction, the mass of the dark matter particle should lie below 5 TeV and its direct detection cross section can be easily probed by XENON1T; if instead they are controlled by scalar interactions, the dark matter mass can be much larger and the detection prospects are less certain. Finally, we show that this scenario can be readily extended to accommodate multiple dark matter particles

Dark Matter Searches with the ATLAS Detector

CERN Document Server

Elliot, Alison; The ATLAS collaboration

2017-01-01

The presence of a non-baryonic dark matter component in the Universe is inferred from the observation of its gravitational interaction. If dark matter interacts weakly with the Standard Model it would be produced at the LHC, escaping the detector and leaving a large missing transverse momentum as their signature.  The ATLAS detector has developed a broad and systematic search program for dark matter production in LHC collisions. The results of these searches on the first 13 TeV data, their interpretation, and the design and possible evolution of the search program will be presented.