scholarly journals First cosmological constraint on the effective theory of dark matter-proton interactions

2018 ◽  
Vol 98 (8) ◽  
Author(s):  
Kimberly K. Boddy ◽  
Vera Gluscevic
Keyword(s):  
Dark Matter ◽  
Effective Theory ◽  
Cosmological Constraint

scholarly journals Exothermic dark matter for XENON1T excess

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Hyun Min Lee
Keyword(s):  
Dark Matter ◽  
Mass Difference ◽  
Mass Splitting ◽  
Effective Theory ◽  
Recoil Energy ◽  
Detector Resolution ◽  
Atomic Excitation ◽  
Microscopic Models ◽  
Electron Recoil ◽  
Two Component

Abstract Motivated by the recent excess in the electron recoil from XENON1T experiment, we consider the possibility of exothermic dark matter, which is composed of two states with mass splitting. The heavier state down-scatters off the electron into the lighter state, making an appropriate recoil energy required for the Xenon excess even for the standard Maxwellian velocity distribution of dark matter. Accordingly, we determine the mass difference between two component states of dark matter to the peak electron recoil energy at about 2.5 keV up to the detector resolution, accounting for the recoil events over ER = 2 − 3 keV, which are most significant. We include the effects of the phase-space enhancement and the atomic excitation factor to calculate the required scattering cross section for the Xenon excess. We discuss the implications of dark matter interactions in the effective theory for exothermic dark matter and a massive Z′ mediator and provide microscopic models realizing the required dark matter and electron couplings to Z′.

scholarly journals A combined analysis of PandaX, LUX, and XENON1T experiments within the framework of dark matter effective theory

2017 ◽  
Vol 2017 (11) ◽  
Author(s):  
Zuowei Liu ◽  
Yushan Su ◽  
Yue-Lin Sming Tsai ◽  
Bingrong Yu ◽  
Qiang Yuan
Keyword(s):  
Dark Matter ◽  
Effective Theory ◽  
Combined Analysis

scholarly journals ETHOS – an effective theory of structure formation: formation of the first haloes and their stars

2019 ◽  
Vol 485 (4) ◽  
pp. 5474-5489 ◽  
Author(s):  
Mark R Lovell ◽  
Jesús Zavala ◽  
Mark Vogelsberger
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Dwarf Galaxy ◽  
Mass Scale ◽  
Effective Theory ◽  
Matter Power Spectrum ◽  
Hydrodynamical Simulations ◽  
Stellar Masses

Abstract A cut-off in the linear matter power spectrum at dwarf galaxy scales has been shown to affect the abundance, formation mechanism and age of dwarf haloes, and their galaxies at high and low redshifts. We use hydrodynamical simulations of galaxy formation within the ETHOS framework in a benchmark model that has such a cut-off and that has been shown to be an alternative to the cold dark matter (CDM) model that alleviates its dwarf-scale challenges. We show how galaxies in this model form differently to CDM, on a halo-by-halo basis, at redshifts z ≥ 6. We show that when CDM haloes with masses around the ETHOS half-mode mass scale are resimulated with the ETHOS matter power spectrum, they form with 50 per cent less mass than their CDM counterparts due to their later formation times, yet they retain more of their gas reservoir due to the different behaviour of gas and dark matter during the monolithic collapse of the first haloes in models with a galactic-scale cut-off. As a result, galaxies in ETHOS haloes near the cut-off scale grow rapidly between z = 10 and 6 and by z = 6 end up having very similar stellar masses, higher gas fractions and higher star formation rates relative to their CDM counterparts. We highlight these differences by making predictions for how the number of galaxies with old stellar populations is suppressed in ETHOS for both z = 6 galaxies and for gas-poor Local Group fossil galaxies. Interestingly, we find an age gradient in ETHOS between galaxies that form in high- and low-density environments.

scholarly journals Viscosity in cosmic fluids

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Pravin Kumar Natwariya ◽  
Jitesh R. Bhatt ◽  
Arun Kumar Pandey
Keyword(s):  
Dark Matter ◽  
Effective Viscosity ◽  
Large Scale ◽  
Significant Contribution ◽  
Viscosity Coefficient ◽  
Effective Theory ◽  
Viscous Effect ◽  
Dissipative Effects ◽  
Large Scale Structure Formation

Abstract The effective theory of large-scale structure formation based on $$\Lambda $$ΛCDM paradigm predicts finite dissipative effects in the resulting fluid equations. In this work, we study how viscous effect that could arise if one includes self-interaction among the dark-matter particles combines with the effective theory. It is shown that these two possible sources of dissipation can operate together in a cosmic fluid and the interplay between them can play an important role in determining dynamics of the cosmic fluid. In particular, we demonstrate that the viscosity coefficient due to self-interaction is added inversely with the viscosity calculated using effective theory of $$\Lambda $$ΛCDM model. Thus the larger viscosity has less significant contribution in the effective viscosity. Using the known bounds on $$\sigma /m$$σ/m for self-interacting darkmatter, where $$\sigma $$σ and m are the cross-section and mass of the dark-matter particles respectively, we discuss role of the effective viscosity in various cosmological scenarios.

scholarly journals Learning effective physical laws for generating cosmological hydrodynamics with Lagrangian deep learning

2021 ◽  
Vol 118 (16) ◽  
pp. e2020324118
Author(s):  
Biwei Dai ◽  
Uroš Seljak
Keyword(s):  
Dark Matter ◽  
Deep Learning ◽  
Generative Models ◽  
Generative Model ◽  
Effective Theory ◽  
High Dimensions ◽  
Wide Range ◽  
Hydrodynamical Simulations ◽  
Physical Laws ◽  
Very High

The goal of generative models is to learn the intricate relations between the data to create new simulated data, but current approaches fail in very high dimensions. When the true data-generating process is based on physical processes, these impose symmetries and constraints, and the generative model can be created by learning an effective description of the underlying physics, which enables scaling of the generative model to very high dimensions. In this work, we propose Lagrangian deep learning (LDL) for this purpose, applying it to learn outputs of cosmological hydrodynamical simulations. The model uses layers of Lagrangian displacements of particles describing the observables to learn the effective physical laws. The displacements are modeled as the gradient of an effective potential, which explicitly satisfies the translational and rotational invariance. The total number of learned parameters is only of order 10, and they can be viewed as effective theory parameters. We combine N-body solver fast particle mesh (FastPM) with LDL and apply it to a wide range of cosmological outputs, from the dark matter to the stellar maps, gas density, and temperature. The computational cost of LDL is nearly four orders of magnitude lower than that of the full hydrodynamical simulations, yet it outperforms them at the same resolution. We achieve this with only of order 10 layers from the initial conditions to the final output, in contrast to typical cosmological simulations with thousands of time steps. This opens up the possibility of analyzing cosmological observations entirely within this framework, without the need for large dark-matter simulations.

scholarly journals Effective Theory Approach to Direct Detection of Dark Matter

2020 ◽  
pp. 650-688
Author(s):  
Junji Hisano
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Particle Physics ◽  
Direct Detection ◽  
Effective Field ◽  
Weakly Interacting Massive Particles ◽  
Effective Theory ◽  
Beyond The Standard Model ◽  
Theory Approach ◽  
The Standard Model

It is now certain that dark matter exists in the Universe. However, we do not know its nature, nor are there dark matter candidates in the standard model of particle physics or astronomy However, weakly interacting massive particles (WIMPs) in models beyond the standard model are one of the leading candidates available to provide explanation. The dark matter direct detection experiments, in which the nuclei recoiled by WIMPs are sought, are one of the methods to elucidate the nature of dark matter. This chapter introduces an effective field theory (EFT) approach in order to evaluate the nucleon–WIMP elastic scattering cross section.

scholarly journals Lightening gravity-mediated dark matter

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
Yoo-Jin Kang ◽  
Hyun Min Lee
Keyword(s):  
Dark Matter ◽  
Arbitrary Spin ◽  
Effective Theory ◽  
Density Condition ◽  
Massive Spin ◽  
The Standard Model ◽  
Warped Extra Dimension ◽  
Consistent Parameter ◽  
Opening Up ◽  
Production Mechanisms

Abstract We revisit the scenario of a massive spin-2 particle as the mediator for communicating between dark matter of arbitrary spin and the Standard Model. Taking the general couplings of the spin-2 particle in the effective theory, we discuss the thermal production mechanisms for dark matter with various channels and the dark matter self-scattering. For WIMP and light dark matter cases, we impose the relic density condition and various experimental constraints from direct and indirect detections, precision measurements as well as collider experiments. We show that it is important to include the annihilation of dark matter into a pair of spin-2 particles in both allowed and forbidden regimes, thus opening up the consistent parameter space for dark matter. The benchmark models of the spin-2 mediator are presented in the context of the warped extra dimension and compared to the simplified models.

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