اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدMetaspin and dirishonic dark matter
38
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
The antisymmetry requirement of rishon bound state wave functions suggests a new rishon quantum number called M spin. From M spin conservation and the Nussinov-Weingarten-Witten theorem we predict the existence of a stable pseudoscalar dirishonic meson, called zeta, that is lighter than the lightest neutrino. Its mass is estimated as m(zeta) = 10^{-9} eV. This particle could make up the major part of cold dark matter in the Universe.
قيم البحث
اقرأ أيضاً
We propose a new class of dark matter models with unusual phenomenology. What is ordinary about our models is that dark matter particles are WIMPs, they are weakly coupled to the Standard Model and have weak scale masses. What is unusual is that they
come in multiplets of a new dark non-Abelian gauge group with milli-weak coupling. The massless dark gluons of this dark gauge group contribute to the energy density of the universe as a form of weakly self-interacting dark radiation. In this paper we explore the consequences of having i.) dark matter in multiplets ii.) self-interacting dark radiation and iii.) dark matter which is weakly coupled to dark radiation. We find that i.) dark matter cross sections are modified by multiplicity factors which have significant consequences for collider searches and indirect detection, ii.) dark gluons have thermal abundances which affect the CMB as dark radiation. Unlike additional massless neutrino species the dark gluons are interacting and have vanishing viscosity and iii.) the coupling of dark radiation to dark matter represents a new mechanism for damping the large scale structure power spectrum. A combination of additional radiation and slightly damped structure is interesting because it can remove tensions between global $Lambda$CDM fits from the CMB and direct measurements of the Hubble expansion rate ($H_0$) and large scale structure ($sigma_8$).
Even if Dark Matter (DM) is neutral under electromagnetism, it can still interact with the Standard Model (SM) via photon exchange from higher-dimensional operators. Here we classify the general effective operators coupling DM to photons, distinguish
ing between Dirac/Majorana fermion and complex/real scalar DM. We provide model-independent constraints on these operators from direct and indirect detection. We also constrain various DM-lepton operators, which induce DM-photon interactions via RG running or which typically arise in sensible UV-completions. This provides a simple way to quickly assess constraints on any DM model that interacts mainly via photon exchange or couples to SM leptons.
We argue that dark radiation is naturally generated from the decay of the overall volume modulus in the LARGE volume scenario. We consider both sequestered and non-sequestered cases, and find that the axionic superpartner of the modulus is produced b
y the modulus decay and it can account for the dark radiation suggested by observations, while the modulus decay through the Giudice-Masiero term gives the dominant contribution to the total decay rate. In the sequestered case, the lightest supersymmetric particles produced by the modulus decay can naturally account for the observed dark matter density. In the non-sequestered case, on the other hand, the supersymmetric particles are not produced by the modulus decay, since the soft masses are of order the heavy gravitino mass. The QCD axion will then be a plausible dark matter candidate.
We generalize dark matter production to a two-metric framework whereby the physical metric, which couples to the Standard Model (SM), is conformally and/or disformally related to the metric governing the gravitational dynamics. We show that this setu
p is naturally present in many Ultra Violet (UV) constructions, from Kahler moduli fields to tensor-portal models, and from emergent gravity to supergravity models. In this setting we study dark matter production in the early Universe resulting from both scatterings off the thermal bath and the radiative decay of the inflaton. We also take into account non-instantaneous reheating effects at the end of inflation. In this context, dark matter emerges from the production of the scalar field mediating the conformal/disformal interactions with the SM, i.e. realising a Feebly Interacting Matter Particle (FIMP) scenario where the suppression scale of the interaction between the scalar and the SM can be taken almost as high as the Planck scale in the deep UV.
We propose a novel thermal production mechanism for dark matter based on the idea that dark matter particles $chi$ can transform (`infect) heat bath particles $psi$: $chi psi rightarrow chi chi$. For a small initial abundance of $chi$ this induces an
exponential growth in the dark matter number density, closely resembling the epidemic curves of a spreading pathogen after an initial outbreak. To quantify this relation we present a sharp duality between the Boltzmann equation for the dark matter number density and epidemiological models for the spread of infectious diseases. Finally we demonstrate that the exponential growth naturally stops before $chi$ thermalizes with the heat bath, corresponding to a triumphant `flattening of the curve that matches the observed dark matter abundance.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
