Search

Theories with compact extra dimensions are sometimes unstable to decay into a bubble of nothing -- an instability resulting in the destruction of spacetime. We investigate the existence of these bubbles in theories where the moduli fields that set the size of the extra dimensions are stabilized at a positive vacuum energy -- a necessary ingredient of any theory that aspires to describe the real world. Using bottom-up methods, and focusing on a five-dimensional toy model, we show that four-dimensional de Sitter vacua admit bubbles of nothing for a wide class of stabilizing potentials. We show that, unlike ordinary Coleman-De Luccia tunneling, the corresponding decay rate remains non-zero in the limit of vanishing vacuum energy. Potential implications include a lower bound on the size of compactified dimensions., Comment: references added; matches journal version

Aromatic organic compounds, because of their small excitation energies ~ O(few eV) and scintillating properties, are promising targets for detecting dark matter of mass ~ O(few MeV). Additionally, their planar molecular structures lead to large anisotropies in the electronic wavefunctions, yielding a significant daily modulation in the event rate expected to be observed in crystals of these molecules. We characterize the daily modulation rate of dark matter interacting with an anisotropic scintillating organic crystal such as trans-stilbene, and show that daily modulation is an ~ O(1) fraction of the total rate for small DM masses and comparable to, or larger than, the ~ 10% annual modulation fraction at large DM masses. As we discuss in detail, this modulation provides significant leverage for detecting or excluding dark matter scattering, even in the presence of a non-negligible background rate. Assuming a non-modulating background rate of 1/min/kg that scales with total exposure, we find that a 100 kg yr experiment is sensitive to the cross section corresponding to the correct relic density for dark matter masses between 1.3-14 MeV (1.5-1000 MeV) if dark matter interacts via a heavy (light) mediator. This modulation can be understood using an effective velocity scale v* = Delta E/q*, where Delta E is the electronic transition energy and q* is a characteristic momentum scale of the electronic orbitals. We also characterize promising future directions for development of scintillating organic crystals as dark matter detectors., Comment: 22 pages, 11 figures; v2: matches journal version up to typo fixed in eq. (12)

Effective field theory arguments suggest that if BSM sectors contain new sources of CP-violation that couple to QCD, these sources will renormalize the $\theta$ term and frustrate ultraviolet solutions to the strong CP problem. Simultaneously, they will generate distinctive patterns of low-energy electric dipole moments in hadronic, nuclear, atomic, and molecular systems. Observing such patterns thus provides evidence that strong CP is solved by an infrared relaxation mechanism. We illustrate the renormalization of $\theta$ and the collections of EDMs generated in a several models of BSM physics, confirming effective field theory expectations, and demonstrate that measurements of ratios of electric dipole moments at planned experiments can provide valuable input on the resolution of the strong CP problem., Comment: 29 pages, 4 figures

In this work we present a new class of N=1 supersymmetric confining gauge theories, with strikingly simple infrared theories that descend from intricate interconnected networks of product gauge groups. A diagram of the gauge groups and the charged matter content of the ultraviolet theory has the structure of a triangular lattice, with $SU(N)$ or $SU(3 N)$ gauge groups at each of the vertices, connected by bifundamental chiral superfields. This structure admits a $U(1)_R$ conserving superpotential with marginal trilinear operators. With the introduction of this superpotential, the $SU(3N)$ and $SU(N)$ gauge groups confine: in the far infrared limit of the supersymmetric theory, the relevant degrees of freedom are gauge invariant "mesons" and "baryons." In this paper we show how the properties of the infrared degrees of freedom depend on the topology and shape of the moose/quiver ``lattice'' of the original gauge theory. We investigate various deformations of the theory, and propose some phenomenological applications for BSM models., Comment: 42 pages, 12 figures, 1 table, 1 appendix

Sub-GeV dark matter (DM) which interacts with electrons can excite electrons occupying molecular orbitals in a scattering event. In particular, aromatic compounds such as benzene or xylene have an electronic excitation energy of a few eV, making them sensitive to DM as light as a few MeV. These compounds are often used as solvents in organic scintillators, where the deexcitation process leads to a photon which propagates until it is absorbed and reemitted by a dilute fluor. The fluor photoemission is not absorbed by the bulk, but is instead detected by a photon detector such as a photomultiplier tube. We develop the formalism for DM--electron scattering in aromatic organic molecules, calculate the expected rate in p-xylene, and apply this calculation to an existing measurement of the single photo-electron emission rate in a low-background EJ-301 scintillator cell. Despite the fact that this measurement was performed in a shallow underground laboratory under minimal overburden, the DM--electron scattering limits extracted from these data are already approaching leading constraints in the 3--100 MeV DM mass range. We discuss possible next steps in the evolution of this direct detection technique, in which scalable organic scintillators are used in solid or liquid crystal phases and in conjunction with semiconductor photodetectors to improve sensitivity through directional signal information and potentially lower dark rates.

We discuss the cosmology of models in which the standard model Yukawa couplings depend on scalar field(s), often referred to as flavons. We find that thermal corrections of the flavon potential tend to decrease the Yukawa couplings, providing an important input to model-building. Working in the specific framework of Froggatt-Nielsen models, we compute the abundance of flavons in the early universe generated both via freeze-in and from coherent oscillations induced by thermal corrections to their potential, and discuss constraints on flavon models from cosmology. We find that cosmology places important constraints on theories containing flavons even for regions of parameter space inaccessible to collider searches., 26 pages, 5 figures, 5 appendices

We propose a new set of s-confining theories with product gauge groups and no tree-level superpotential, based on a model with one antisymmetric matter field and four flavors of quarks. For each product group we find a set of gauge-invariant operators which satisfy the 't Hooft anomaly matching conditions, and we identify the dynamically generated superpotential which reproduces the classical constraints between operators. Several of these product gauge theories confine without breaking chiral symmetry, even in cases where the classical moduli space is quantum-modified. These results may be useful for composite model building, particularly in cases where small meson operators are absent, or for theories with multiple natural energy scales, and may provide new ways to break supersymmetry dynamically., Comment: 28 pages, 8 tables, one appendix

MSSM4G models, in which the minimal supersymmetric standard model is extended to include vectorlike copies of standard model particles, are promising possibilities for weak-scale supersymmetry. In particular, two models, called QUE and QDEE, realize the major virtues of supersymmetry (naturalness consistent with the 125 GeV Higgs boson, gauge coupling unification, and thermal relic neutralino dark matter) without the need for fine-tuned relations between particle masses. We determine the implications of these models for dark matter and collider searches. The QUE and QDEE models revive the possibility of heavy bino dark matter with mass in the range 300--700 GeV, which is not usually considered. Dark matter direct detection cross sections are typically below current limits, but are naturally expected above the neutrino floor and may be seen at next-generation experiments. Indirect detection prospects are bright at the Cherenkov Telescope Array, provided the fourth-generation leptons have mass above 350 GeV or decay to taus. In a completely complementary way, discovery prospects at the LHC are dim if the fourth-generation leptons are heavy or decay to taus, but are bright for fourth-generation leptons with masses below 350 GeV that decay either to electrons or to muons. We conclude that the combined set of direct detection, CTA, and LHC experiments will discover or exclude these MSSM4G models in the coming few years, assuming the Milky Way has an Einasto dark matter profile.

We explore the reach of a 100 TeV proton collider to discover KK gluons in a warped extra dimension. These particles are templates for color adjoint vectors that couple dominantly to the top quark. We examine their production rate at NLO in the six-flavor m-ACOT scheme for a variety of reference models defining their coupling to quarks, largely inspired by the RS model of a warped extra dimension. In agreement with previous calculations aimed at lower energy machines, we find that the NLO corrections are typically negative, resulting in a $K$-factor of around 0.7 (depending on the model) and with a residual scale dependence on the order of $\pm 20\%$, greater than the variation from the scale exhibited by the na\"{i}ve LO estimate., Comment: 33 pages, 5 figures, 2 tables