A composite solution to the EDGES anomaly

Solving the A{FB}^b anomaly in natural composite models

The Standard Model with a light Higgs provides a very accurate description of the electroweak precision observables. The largest deviation between the Standard Model predictions and the experimental measurements, the forward-backward asymmetry of the bottom quark A{FB}^b, can be interpreted as an indication of new physics at the TeV scale. The strong agreement between theory and experiment in the branching fraction of the Z into b-quarks puts strong constraints for new physics aiming to solve the A{FB}^b puzzle. We study a class of natural composite Higgs models that can solve the A{FB}^b anom…

Anomaly-matching and Higgs-less effective theories

We reconsider the low-energy effective theory for Higgs-less electroweak symmetry breaking: we study the anomaly-matching in the situation where all Goldstone fields disappear from the spectrum as a result of the Higgs mechanism. We find that the global SU(2)_L x SU(2)_R x U(1)_{B-L} symmetry of the underlying theory, which is spontaneously broken to SU(2)_{L+R} x U(1)_{B-L} has to be anomaly-free. For the sake of generality, we include the possibility of light spin-1/2 bound states resulting from the dynamics of the strongly-interacting symmetry-breaking sector, in addition to the Goldstone b…

On the baryon-color-flavor (BCF) anomaly in vector-like theories

We consider the most general fractional background fluxes in the color, flavor, and baryon number directions, compatible with the faithful action of the global symmetry of a given theory. We call the obstruction to gauging symmetries revealed by such backgrounds the baryon-color-flavor (BCF) 't Hooft anomaly. We apply the BCF anomaly to vector-like theories, with fermions in higher-dimensional representations of arbitrary N-ality, and derive non-trivial constraints on their IR dynamics. In particular, this class of theories enjoys an independent discrete chiral symmetry and one may ask about t…

A detailed exploration of the EDGES 21 cm absorption anomaly and axion-induced cooling

The EDGES collaboration's observation of an anomalously strong 21 cm absorption feature around the cosmic dawn era has energised the cosmological community by suggesting a novel signature of dark matter in the cooling of cosmic hydrogen. In a recent letter we have argued that by virtue of the ability to mediate cooling processes whilst in the condensed phase, a small amount of axion dark matter can explain these observations within the context of standard models of axions and axion-like particles. These axions and axion-like particles (ALPs) can thermalize through gravitational self-interactio…

Superconformal Sum Rules and the Spectral Density Flow of the Composite Dilaton (ADD) Multiplet in $\mathcal{N}=1$ Theories

We discuss the signature of the anomalous breaking of the superconformal symmetry in $\mathcal{N}=1$ super Yang Mills theory, mediated by the Ferrara-Zumino hypercurrent ($\mathcal{J}$) with two vector ($\mathcal V$) supercurrents $(\mathcal{JVV})$ and its manifestation in the anomaly action, in the form of anomaly poles. This allows to investigate in a unified way both conformal and chiral anomalies. The analysis is performed in parallel to the Standard Model, for comparison. We investigate, in particular, massive deformations of the $\mathcal{N}=1$ theory and the spectral densities of the an…

Probing relic neutrino decays with 21 cm cosmology

We show how 21 cm cosmology can test relic neutrino radiative decays into sterile neutrinos. Using recent EDGES results, we derive constraints on the lifetime of the decaying neutrinos. If the EDGES anomaly will be confirmed, then there are two solutions, one for much longer and one for much shorter lifetimes than the age of the universe, showing how relic neutrino radiative decays can explain the anomaly in a simple way. We also show how to combine EDGES results with those from radio background observations, showing that potentially the ARCADE 2 excess can be also reproduced together with the…

$Z \to b {\bar b}$ in a composite model of fermions

A composite model of fermions is proposed to explain the "anomaly" in $Z \rightarrow b {\bar b}$ and, to a lesser extent, in $Z \rightarrow c {\bar c}$. It contains a {\em nonsequential} fourth family whose mass of one member (the charge -1/3 quark) is constrained to be between 47 GeV and 49 GeV. The charge +2/3 quark is constrained to lie between 67 GeV and 107 GeV. This opens up the exciting prospect for near-future discoveries at LEP2 and possibly at the Tevatron.

The EDGES 21 cm Anomaly and Properties of Dark Matter

The recently claimed anomaly in the measurement of the 21 cm hydrogen absorption signal by EDGES at $z\sim 17$, if cosmological, requires the existence of new physics. The possible attempts to resolve the anomaly rely on either (i) cooling the hydrogen gas via new dark matter-hydrogen interactions or (ii) modifying the soft photon background beyond the standard CMB one, as possibly suggested also by the ARCADE~2 excess. We argue that solutions belonging to the first class are generally in tension with cosmological dark matter probes once simple dark sector models are considered. Therefore, we …

最小复合 $S_1$ 轻子夸克的味道与 $b\to cτ\barν$ 反常

The flavor of a minimal composite $S_1$ leptoquark and the $b\to cτ\barν$ anomaly

针对 $B\to D^{(*)}$ 衰变中的轻子味道普适性反常，在复合希格斯模型中引入最小复合 $S_1$ 轻子夸克，计算其势能并预测 $R_{D^{(*)}}$ 等观测量，发现实验值比理论预测高约 $2σ$，同时给出对耦合和质量的约束。

An Ultraviolet Chiral Theory of the Top for the Fundamental Composite (Goldstone) Higgs

We introduce a scalar-less anomaly free chiral gauge theory that serves as natural ultraviolet completion of models of fundamental composite (Goldstone) Higgs dynamics. The new theory is able to generate the top mass and furthermore features a built-in protection mechanism that naturally suppresses the bottom mass. At low energies the theory predicts new fractionally charged fermions, and a number of four-fermion operators that, besides being relevant for the generation of the top mass, also lead to an intriguing phenomenology for the new states predicted by the theory.