Elimination of the Blue Loops in the Evolution of Intermediate-mass Stars by the Neutrino Magnetic Moment and Large Extra Dimensions

Abstract

For searching beyond Standard Model physics, stars are laboratories which complement terrestrial experiments. Massless neutrinos in the Standard Model of particle physics cannot have a magnetic moment, but massive neutrinos have a finite magnetic moment in the minimal extension of the Standard Model. Large extra dimensions are a possible solution of the hierarchy problem. Both of these provide additional energy loss channels in stellar interiors via the electromagnetic interaction and radiation into extra dimensions, respectively, and thus affect stellar evolution. We perform simulations of stellar evolution with such additional energy losses and find that they eliminate the blue loops in the evolution of intermediate-mass stars. The existence of Cepheid stars can be used to constrain the neutrino magnetic moment and large extra dimensions. In order for Cepheids to exist, the neutrino magnetic moment should be smaller than the range ∼ 2×10 −10 to 4×10 −11 µ B , where µ B is the Bohr magneton, and the fundamental scale in the (4+2)-spacetime should be larger than ∼ 2 to 5 TeV, depending on the rate of the 12 C(α, γ) 16 O reaction. The fundamental scale also has strong dependence on the metallicity. This value of the magnetic moment is in the range explored in the reactor experiments, but higher than the limit inferred from globular clusters. Similarly the fundamental scale value we constrain corresponds to a size of the compactified dimensions comparable to those explored in the torsion balance experiments, but is smaller than the limits inferred from collider experiments and low-mass stars.

Beyond the Standard Model Explanations of GW190521

“…This allows for a novel loss mechanism in the interiors of stars whereby SM particles can produce Kaluza-Klein (KK) modes of the graviton. We have implemented the losses due to KK modes resulting from photon-photon annihilation, gravi-Compton-Primakoff scattering, and gravi-bremsstrahlung processes into MESA using the rates given in [35] for n additional compactified spatial dimensions. The most important mechanism is photon-photon annihilation, which scales as T n+7 .…”

“…The case n = 1 is strongly constrained by solar system tests and for n ≥ 3 the constraints from collider experiments are expected to be substantially stronger than those available from stellar evolution [35], so we focus on n = 2. The effects of losses are similar to those resulting from light particle emission: the ratio of 12 C to 16 O after core helium burning is enhanced, quenching the PISN and forming heavier black holes.…”

“…The effects of losses are similar to those resulting from light particle emission: the ratio of 12 C to 16 O after core helium burning is enhanced, quenching the PISN and forming heavier black holes. With the constraint R LED ≤ 30µm [35][36][37], the LED scenario is capable of accounting for the GW190521 progenitor masses if the mass scale associated with the extra dimensions satisfies M s < 1 − 2 TeV for n = 2. For n = 2, CMS constrains M s 3.9 TeV [38], which is again in some tension with the value needed to produce a black hole as massive as the primary object in GW190521, though this constraint depends on the compactification geometry and details of the collider signal process, and the viability of compactifications with mass scale 2 TeV calls for a thorough investigation.…”

Enhancement of Lithium in Red Clump Stars by the Additional Energy Loss Induced by New Physics

“…The NMM induces the additional energy loss and affects various stages of stellar evolution for wider mass-range of stars. The effect on the evolution of intermediate-mass stars has recently been studied in detail (Mori et al 2020) and it was found that in the presence of a sufficiently large NMM the duration of blue giants is shorter and the blue loops are eliminated. Stellar plasma of low-mass stars also is effected by NMM and the helium flash delays (Haft, Raffelt & Weiss 1994).…”