Implications of a scalar dark force for terrestrial experiments

A long-range intergalactic force between dark matter (DM) particles, mediated by an ultralight scalar, is tightly constrained by galactic dynamics and large scale structure formation. We examine the implications of such a ‘‘dark force” for several terrestrial experiments, including Eötvös tests of the Weak Equivalence Principle (WEP), direct-detection DM searches, and collider studies. The presence of a dark force implies a nonvanishing effect in Eötvös tests that could be probed by current and future experiments depending on the DM model. For scalar DM that is a singlet under the standard model gauge groups, a dark force of astrophysically relevant magnitude is ruled out in large regions of parameter space by the DM relic density and WEP constraints. WEP tests also imply constraints on the Higgs-exchange contributions to the spin-independent (SI) DM-nucleus direct-detection cross section. For WIMP scenarios, these considerations constrain Higgs-exchange contributions to the SI cross section to be subleading compared to gauge-boson mediated contributions. In multicomponent DM scenarios, a dark force would preclude large shifts in the rate for Higgs decay to two photons associated with DM-multiplet loops that might otherwise lead to measurable deviations at the LHC or a future linear collider. The combination of observations from galactic dynamics, large scale structure formation, Eötvös experiments, DM-direct-detection experiments, and colliders can further constrain the size of new long-range forces in the dark sector

Yukawa and triscalar processes in electroweak baryogenesis

We derive the contributions to the quantum transport equations for electroweak baryogenesis due to decays and inverse decays induced by triscalar and Yukawa interactions. In the minimal supersymmetric standard model (MSSM), these contributions give rise to couplings between Higgs and fermion supermultiplet densities, thereby communicating the effects of CP-violation in the Higgs sector to the baryon sector. We show that the decay and inverse decay-induced contributions that arise at zeroth order in the strong coupling, alphas, can be substantially larger than the [script O](alphas) terms that are generated by scattering processes and that are usually assumed to dominate. We revisit the often-used approximation of fast Yukawa-induced processes and show that for realistic parameter choices it is not justified. We solve the resulting quantum transport equations numerically with special attention to the impact of Yukawa rates and study the dependence of the baryon-to-entropy ratio YB on MSSM parameters

Pion Leptonic Decays and Supersymmetry

We compute supersymmetric contributions to pion leptonic (\pi_{l2}) decays in the Minimal Supersymmetric Standard Model (MSSM). When R-parity is conserved, the largest contributions to the ratio R_{e/\mu} = \Gamma[ \pi^+ \to e^+ \nu_e(\gamma)]/\Gamma[ \pi^+ \to \mu^+ \nu_\mu(\gamma)] arise from one-loop (V-A)x(V-A) corrections. These contributions can be potentially as large as the sensitivities of upcoming experiments; if measured, they would imply significant bounds on the chargino and slepton sectors complementary to current collider limits. We also analyze R-parity violating interactions, which may produce a detectable deviation in R_{e/\mu} while remaining consistent with all other precision observables.Comment: 12 pages, 11 figures; included additional electroweak constraints in analysis, simplified abstract, ref. adde

Identification and cost of adverse events in metastatic breast cancer in taxane and capecitabine based regimens.

PurposeWe sought to compare the economic impact of treatment-related adverse events (AEs) in patients with metastatic breast cancer (mBC) using taxane- or capecitabine-based treatment regimens as either first- or second-line (FL or SL) therapy in the US.MethodsWe used healthcare claims data from the Truven Health Analytics MarketScan® Commercial Databases to conduct a retrospective cohort study comparing the economic impact of AEs amongst taxane- and capecitabine-treated mBC patients in the US. We selected women diagnosed with mBC between 2008-2010 who received a taxane or capecitabine as first- or second-line (FL or SL) chemotherapy. Costs related to hospitalization, outpatient services, emergency department visits, chemotherapy and other medications were tabulated and combined to determine total healthcare costs. The incremental monthly costs associated with the presence of AEs compared to no AEs were estimated using generalized linear models, controlling for age and Charlson Comorbidity Index.ResultsWe identified 15,443 mBC patients meeting inclusion criteria. Adjusted total monthly costs were significantly higher in those who experienced AEs than in those without AEs in both lines of treatment (FL incremental cost: taxanes $1,142, capecitabine$1,817; SL incremental cost: taxanes $1,448, capecitabine$4,437). Total costs increased with the number of AEs and were primarily driven by increased hospitalization amongst those with AEs.ConclusionsAdverse events in taxane- or capecitabine-treated mBC patients are associated with significant increases in costs. Selecting treatment options associated with fewer AEs may reduce costs and improve outcomes in these patients

Flavored Quantum Boltzmann Equations

We derive from first principles, using non-equilibrium field theory, the quantum Boltzmann equations that describe the dynamics of flavor oscillations, collisions, and a time-dependent mass matrix in the early universe. Working to leading non-trivial order in ratios of relevant time scales, we study in detail a toy model for weak scale baryogenesis: two scalar species that mix through a slowly varying time-dependent and CP-violating mass matrix, and interact with a thermal bath. This model clearly illustrates how the CP asymmetry arises through coherent flavor oscillations in a non-trivial background. We solve the Boltzmann equations numerically for the density matrices, investigating the impact of collisions in various regimes.Comment: 41 pages, 7 figures. v2: references added, minor corrections and clarification

Lepton-mediated electroweak baryogenesis

We investigate the impact of the tau and bottom Yukawa couplings on the transport dynamics for electroweak baryogenesis in supersymmetric extensions of the Standard Model. Although it has generally been assumed in the literature that all Yukawa interactions except those involving the top quark are negligible, we find that the tau and bottom Yukawa interaction rates are too fast to be neglected. We identify an illustrative "lepton-mediated electroweak baryogenesis" scenario in which the baryon asymmetry is induced mainly through the presence of a left-handed leptonic charge. We derive analytic formulae for the computation of the baryon asymmetry that, in light of these effects, are qualitatively different from those in the established literature. In this scenario, for fixed CP-violating phases, the baryon asymmetry has opposite sign compared to that calculated using established formulae.Comment: 26 pages, 5 figure

Invasive plants rapidly reshape soil properties in a grassland ecosystem

© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in mSystems 2 (2017): e00178-16, doi:10.1128/mSystems.00178-16.Plant invasions often reduce native plant diversity and increase net primary productivity. Invaded soils appear to differ from surrounding soils in ways that impede restoration of diverse native plant communities. We hypothesize that invader-mediated shifts in edaphic properties reproducibly alter soil microbial community structure and function. Here, we take a holistic approach, characterizing plant, prokaryotic, and fungal communities and soil physicochemical properties in field sites, invasion gradients, and experimental plots for three invasive plant species that cooccur in the Rocky Mountain West. Each invader had a unique impact on soil physicochemical properties. We found that invasions drove shifts in the abundances of specific microbial taxa, while overall belowground community structure and functional potential were fairly constant. Forb invaders were generally enriched in copiotrophic bacteria with higher 16S rRNA gene copy numbers and showed greater microbial carbohydrate and nitrogen metabolic potential. Older invasions had stronger effects on abiotic soil properties, indicative of multiyear successions. Overall, we show that plant invasions are idiosyncratic in their impact on soils and are directly responsible for driving reproducible shifts in the soil environment over multiyear time scales.Sean Gibbons was supported by an EPA STAR Graduate Fellowship and National Institutes of Health training grant 5T-32EB-009412. Other funding for this project was provided by MPG Ranch and DOE contract DE-AC02-06CH11357

Supergauge interactions and electroweak baryogenesis

We present a complete treatment of the diffusion processes for supersymmetric electroweak baryogenesis that characterizes transport dynamics ahead of the phase transition bubble wall within the symmetric phase. In particular, we generalize existing approaches to distinguish between chemical potentials of particles and their superpartners. This allows us to test the assumption of superequilibrium (equal chemical potentials for particles and sparticles) that has usually been made in earlier studies. We show that in the Minimal Supersymmetric Standard Model, superequilibrium is generically maintained -- even in the absence of fast supergauge interactions -- due to the presence of Yukawa interactions. We provide both analytic arguments as well as illustrative numerical examples. We also extend the latter to regions where analytical approximations are not available since down-type Yukawa couplings or supergauge interactions only incompletely equilibrate. We further comment on cases of broken superequilibrium wherein a heavy superpartner decouples from the electroweak plasma, causing a kinematic bottleneck in the chain of equilibrating reactions. Such situations may be relevant for baryogenesis within extensions of the MSSM. We also provide a compendium of inputs required to characterize the symmetric phase transport dynamics.Comment: 49 pages, 9 figure