Cosmological constant, axial anomalies and photon mass dynamos from chiral Fermionic torsion

Motivated by Palle’s investigation on the handness of chirality of vorticity in Einstein–Cartan cosmology [Entropy 5 (2014)], several aspects of chiral torsional handness in magnetogenesis and cosmology are presented. In the first one, we obtain torsion bounds from massive photons and axial anomalies. In the second, we deal with magnetogenesis from photon mass and in the third, we discuss chiral torsion degrees of freedom to obtain a torsion cosmological constant dependent solution. The torsion solution decays fast and implies a strong suppression of torsion at present universe. Our result contains the Poplawski [Phys. Lett. B (2010)] results in the case axial torsion vector associated to Einstein–Cartan fermionic sector matter and conformal anomalies of quarks. In the third example, a magnetic field bound from chiral torsionic dynamos is obtained as [Formula: see text]. In the non-minimal cosmological models, chiral dynamos are sourced by massive photons, London currents and chiral magnetic effect (CME). Chiral chemical potential is found to be mimic by torsion. Cosmological constant bound [Formula: see text] is found. At the early universe, the cosmological constant [Formula: see text] is obtained. Torsion used in the present universe is [Formula: see text]. In the last and fourth example, chiral anisotropic currents are obtained and magnetic helicity is shown to depend upon torsion when the chiral chemical potential is non-constant.

The Swampland Conjectures: A Bridge from Quantum Gravity to Particle Physics

The swampland is the set of seemingly consistent low-energy effective field theories that cannot be consistently coupled to quantum gravity. In this review we cover some of the conjectural properties that effective theories should possess in order not to fall in the swampland, and we give an overview of their main applications to particle physics. The latter include predictions on neutrino masses, bounds on the cosmological constant, the electroweak and QCD scales, the photon mass, the Higgs potential and some insights about supersymmetry.

Dark photon production via $$\gamma \gamma \rightarrow \gamma A'$$

The dark photon is a new gauge boson which arises from an extra $$U'(1)$$ U ′ ( 1 ) gauge symmetry. In this paper, a novel dark photon production mechanism based on MeV-scale $$\gamma $$ γ –$$\gamma $$ γ collider is considered: $$\gamma \gamma \rightarrow \gamma A'$$ γ γ → γ A ′ . With the aid of PACKAGE-X, differential cross section of $$\gamma \gamma \rightarrow \gamma A'$$ γ γ → γ A ′ is obtained, as a function of the kinetic mixing parameter $$\varepsilon $$ ε and dark photon mass $$m_{A'}$$ m A ′ . Taking the light-by-light scattering as background, the constraints on the dark photon parameter space for different time intervals in a MeV-scale $$\gamma $$ γ –$$\gamma $$ γ collider are also given.

Search for the dark photon in B0 → A′A′, A′ → e+e−, μ+μ−, and π+π− decays at Belle

We present a search for the dark photon A′ in the B0 → A′A′ decays, where A′ subsequently decays to e+e−, μ+μ−, and π+π−. The search is performed by analyzing 772 × 106$$ B\overline{B} $$ B B ¯ events collected by the Belle detector at the KEKB e+e− energy-asymmetric collider at the ϒ(4S) resonance. No signal is found in the dark photon mass range 0.01 GeV/c2 ≤ mA′ ≤ 2.62 GeV/c2, and we set upper limits of the branching fraction of B0 → A′A′ at the 90% confidence level. The products of branching fractions, $$ \mathrm{\mathcal{B}}\left({B}^0\to A^{\prime }A^{\prime}\right)\times \mathrm{\mathcal{B}}{\left(A\prime \to {e}^{+}{e}^{-}\right)}^2 $$ ℬ B 0 → A ′ A ′ × ℬ A ′ → e + e − 2 and $$ \mathrm{\mathcal{B}}\left({B}^0\to A^{\prime }A^{\prime}\right)\times \mathrm{\mathcal{B}}{\left(A\prime \to {\mu}^{+}{\mu}^{-}\right)}^2 $$ ℬ B 0 → A ′ A ′ × ℬ A ′ → μ + μ − 2 , have limits of the order of 10−8 depending on the A′ mass. Furthermore, considering A′ decay rate to each pair of charged particles, the upper limits of $$ \mathrm{\mathcal{B}}\left({B}^0\to A^{\prime }A^{\prime}\right) $$ ℬ B 0 → A ′ A ′ are of the order of 10−8–10−5. From the upper limits of $$ \mathrm{\mathcal{B}}\left({B}^0\to A^{\prime }A^{\prime}\right) $$ ℬ B 0 → A ′ A ′ , we obtain the Higgs portal coupling for each assumed dark photon and dark Higgs mass. The Higgs portal couplings are of the order of 10−2–10−1 at $$ {m}_{h\prime}\simeq {m}_{B^0} $$ m h ′ ≃ m B 0 ± 40 MeV/c2 and 10−1–1 at $$ {m}_{h\prime}\simeq {m}_{B^0} $$ m h ′ ≃ m B 0 ± 3 GeV/c2.