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The available data on neutron scattering were analyzed to constrain a hypothetical new short-range interaction. We show that these constraints are several orders of magnitude better than those usually cited in the range between 1 pm and 5 nm. This distance range occupies an intermediate space between collider searches for strongly coupled heavy bosons and searches for new weak macroscopic forces. We emphasise the reliability of the neutron constraints in so far as they provide several independent strategies. We have identified the most promising way to improve them.
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We describe a proposed experimental search for exotic spin-coupled interactions using a solid-state paramagnetic insulator. The experiment is sensitive to the net magnetization induced by the exotic interaction between the unpaired insulator electrons with a dense, non-magnetic mass in close proximity. An existing experiment has been used to set limits on the electric dipole moment of the electron by probing the magnetization induced in a cryogenic gadolinium gallium garnet sample on application of a strong electric field. With suitable additions, including a movable source mass, this experiment can be used to explore monopole-dipole forces on polarized electrons with unique or unprecedented sensitivity. The solid-state, non-magnetic construction, combined with the low-noise conditions and extremely sensitive magnetometry available at cryogenic temperatures could lead to a sensitivity over ten orders of magnitude greater than exiting limits in the range below 1 mm.
We investigate some consequences if neutrinoless double beta decays of nuclei are dominated by short range interactions. To illustrate our results, we assume that such decays proceed mainly through short range interactions involving two-W-bosons exchanges and confine ourselves to only include new scalars without new gauge interactions for SM fermions. For the neutrino mass problem we propose to solve it by adopting that the active light neutrinos have predominantly Dirac masses and the small Majorana masses induced by the new scalars render them pseudo(quasi)-Dirac particles. This particular aspect of neutrinos may be detectable in the next generation of neutrino oscillation experiments and/or neutrino telescopes. If so this opens a new connection between neutrinoless double beta decays and neutrino physics. We also noted the new physics signals such as high charged scalar states that can be explored in hadron colliders. In particular, we find that a high energy e^- e^- collider will be very useful in testing the origin of lepton number violation which complements neutrinoless double decays studies.
In calculating the energy corrections to the hydrogen levels we can identify two different types of modifications of the Coulomb potential $V_{C}$, with one of them being the standard quantum electrodynamics corrections, $delta V$, satisfying $left|delta Vright|llleft|V_{C}right|$ over the whole range of the radial variable $r$. The other possible addition to $V_{C}$ is a potential arising due to the finite size of the atomic nucleus and as a matter of fact, can be larger than $V_{C}$ in a very short range. We focus here on the latter and show that the electric potential of the proton displays some undesirable features. Among others, the energy content of the electric field associated with this potential is very close to the threshold of $e^+e^-$ pair production. We contrast this large electric field of the Maxwell theory with one emerging from the non-linear Euler-Heisenberg theory and show how in this theory the short range electric field becomes smaller and is well below the pair production threshold.
We investigate many-body spin squeezing dynamics in an XXZ model with interactions that fall off with distance $r$ as $1/r^alpha$ in $D=2$ and $3$ spatial dimensions. In stark contrast to the Ising model, we find a broad parameter regime where spin squeezing comparable to the infinite-range $alpha=0$ limit is achievable even when interactions are short-ranged, $alpha>D$. A region of collective behavior in which optimal squeezing grows with system size extends all the way to the $alphatoinfty$ limit of nearest-neighbor interactions. Our predictions, made using the discrete truncated Wigner approximation (DTWA), are testable in a variety of experimental cold atomic, molecular, and optical platforms.
We report a study on the low-energy properties of the elastic $s-$wave scattering of a neutron ($n$) in the carbon isotope $^{19}$C near the critical condition for the occurrence of an excited Efimov state in the three-body $n-n-^{18}$C system. For the separation energy of the two halo neutrons in $^{20}$C we use the available experimental data. We also investigate to which extent the universal scaling laws, strictly valid in the zero-range limit, will survive when using finite-range interactions. By allowing to vary the $n-^{18}$C binding energy, a scaling behavior for the real and imaginary parts of the $s-$wave phase-shift $delta_0$ is verified, emerging some universal characteristics given by the pole-position of $kcot(delta_0^R)$ and effective-range parameters.
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