On the Strength of First Order Phase Transitions

Electroweak baryogenesis may solve one of the most fundamental questions we can ask about the universe, that of the origin of matter. It has become clear in the past few years that it also poses a multi-faceted challenge. In order to compute the tiny primordial baryonic excess, we probably must invoke physics beyond the standard model (an exciting prospect for most people), we must push perturbation theory to its ``limits'' (or beyond), and we must deal with nonequilibrium aspects of the phase transition. In this talk, I focus mainly on the latter issue, that of nonequilibrium aspects of first order transitions. In particular, I discuss the elusive question of ``weakness''. What does it mean to have a weak first order transition, and how can we distinguish between weak and strong? I argue that weak and strong transitions have very different dynamics; while strong transitions proceed by the usual bubble nucleation mechanism, weak transitions are characterized by a mixing of phases as the system reaches the critical temperature from above. I show that it is possible to clearly distinguish between the two, and discuss consequences for studies of first order transitions in general. (Invited talk given at the ``Electroweak Physics and the Early Universe'' workshop, Sintra, March 23-25, 1994.)Comment: 16 pages, 4 figures not included (can be obtained from hep-ph/9403310, or by request) RevTeX, DART-HEP-94/0

Nutraceutical therapies for atherosclerosis

Atherosclerosis is a chronic inflammatory disease affecting large and medium arteries and is considered to be a major underlying cause of cardiovascular disease (CVD). Although the development of pharmacotherapies to treat CVD has contributed to a decline in cardiac mortality in the past few decades, CVD is estimated to be the cause of one-third of deaths globally. Nutraceuticals are natural nutritional compounds that are beneficial for the prevention or treatment of disease and, therefore, are a possible therapeutic avenue for the treatment of atherosclerosis. The purpose of this Review is to highlight potential nutraceuticals for use as antiatherogenic therapies with evidence from in vitro and in vivo studies. Furthermore, the current evidence from observational and randomized clinical studies into the role of nutraceuticals in preventing atherosclerosis in humans will also be discussed

Search for heavy resonances decaying into a W or Z boson and a Higgs boson in final states with leptons and b-jets in 36 fb(-1) of root s=13 TeV pp collisions with the ATLAS detector

A search is conducted for new resonances decaying into a W or Z boson and a 125 GeV Higgs boson in the νν¯¯¯bb¯¯, ℓ±νbb¯¯, and ℓ+ℓ−bb¯¯ final states, where ℓ± = e± or μ±, in pp collisions at s√=13 TeV. The data used correspond to a total integrated luminosity of 36.1 fb−1 collected with the ATLAS detector at the Large Hadron Collider during the 2015 and 2016 data-taking periods. The search is conducted by examining the reconstructed invariant or transverse mass distributions of W h and Zh candidates for evidence of a localised excess in the mass range of 220 GeV up to 5 TeV. No significant excess is observed and the results are interpreted in terms of constraints on the production cross-section times branching fraction of heavy W ′ and Z′ resonances in heavy-vector-triplet models and the CP-odd scalar boson A in two-Higgs-doublet models. Upper limits are placed at the 95% confidence level and range between 9.0 × 10−4 pb and 7.3 × 10−1 pb depending on the model and mass of the resonance

Renormalization-group theory of spinodal decomposition

Renormalization-group (RG) methods developed previously for the study of the growth of order in unstable systems are extended to treat the spinodal decomposition of the two-dimensional spin-exchange kinetic Ising model. The conservation of the order parameter and fixed-length sum rule are properly preserved in the theory. Various correlation functions in both coordinate and momentum space are calculated as functions of time. The scaling function for the structure factor is extracted. We compare our results with direct Monte Carlo (MC) simulations and find them in good agreement. The time rescaling parameter entering the RG analysis is temperature dependent, as was determined in previous work through a RG analysis of MC simulations. The results exhibit a long-time logarithmic growth law for the typical domain size, both analytically and numerically. In the time region where MC simulations have previously been performed, the logarithmic growth law can be fitted to a power law with an effective exponent. This exponent is found to be in excellent agreement with the result of MC simulations. The logarithmic growth law agrees with a physical model of interfacial motion which involves an interplay between the local curvature and an activated jump across the interface. © 1985 The American Physical Society.link_to_subscribed_fulltex

Growth of order in order-disorder transitions: Tests of universality

Renormalization-group methods developed previously to treat the growth of order in unstable systems are extended and applied to the antiferromagnetic spin-exchange (AF SE) model for order-disorder transitions in binary alloys. The number-conservation law and fixed-length sum rule are properly preserved. Various scaling behaviors are identified and the corresponding scaling functions are determined and compared to those found in previous work on the spin-flip kinetic Ising (SF KI) model. While the AF SE and SF KI models both have a nonconserved scalar order parameter, their microscopic dynamics is very different, and no quantities are conserved in the SF case. We investigate the dependence of the growth kinetics on these differences. We find that the scaling function for the quasistatic structure factor is universal for the models that we have studied. The scaling functions reflecting the dependence of the growth on the correlation length of the final equilibrium state, while quite similar for the various models, depend on both the presence of the conservation law and the choice of exchange probability. We have also carried out detailed comparisons of our results with Monte Carlo simulations for the scaling function for the structure factor, and the time dependence of the nearest-neighbor correlation function. The agreement between the theory and the simulations is excellent. In addition, we have carried out Monte Carlo simulations which verify directly the existence of the self-similar behavior on which our theory is founded. © 1985 The American Physical Society.link_to_subscribed_fulltex

Kinetics of first-order phase transitions: Monte Carlo simulations, renormalization-group methods, and scaling for critical quenches

Using a combination of renormalization-group (RG) methods and Monte Carlo simulations, we study the growth kinetics of the spin-flip (SFKI) and the spin-exchange (SEKI) kinetic Ising models subjected to a critical quench (in zero external field) from infinite to low temperatures. The method developed here allows one to establish, in a nonperturbative fashion, the RG equations developed by us elsewhere. In the case of the SFKI model we find agreement, as expected, with the curvature-driven dynamics of Lifshitz, Cahn, and Allen which gives a growth law for a typical domain size of L(t)t1/2. Our results for the SEKI model (spinodal decomposition) are qualitatively different from the SFKI case. While both show scaling behavior for quenches to nonzero temperatures, the growth kinetics for the SE case show a long-time logarithmic growth L(t)lnt. For intermediate times one can fit an effective exponent L(t)ta(t) where a(t) agrees well with existing direct Monte Carlo studies. This logarithmic behavior is associated with the freezing of this system for quenches to zero temperature. © 1985 The American Physical Society.link_to_subscribed_fulltex

Angular dependence of superconductivity in superconductor/spin-valve heterostructures

We report measurements of the superconducting transition temperature, Tc, in CoO/Co/Cu/Co/Nb multilayers as a function of the angle α between the magnetic moments of the Co layers. Our measurements reveal that Tc(α) is a nonmonotonic function, with a minimum near α=π/2. Numerical self-consistent solutions of the Bogoliubov-de Gennes equations quantitatively and accurately describe the behavior of Tc as a function of α and layer thicknesses in these superconductor/spin-valve heterostructures. We show that experimental data and theoretical evidence agree in relating Tc(α) to enhanced penetration of the triplet component of the condensate into the Co/Cu/Co spin valve in the maximally noncollinear magnetic configuration. © 2014 American Physical Society

Angular dependence of superconductivity in superconductor/spin-valve heterostructures

We report measurements of the superconducting transition temperature, Tc, in CoO/Co/Cu/Co/Nb multilayers as a function of the angle α between the magnetic moments of the Co layers. Our measurements reveal that Tc(α) is a nonmonotonic function, with a minimum near α=π/2. Numerical self-consistent solutions of the Bogoliubov-de Gennes equations quantitatively and accurately describe the behavior of Tc as a function of α and layer thicknesses in these superconductor/spin-valve heterostructures. We show that experimental data and theoretical evidence agree in relating Tc(α) to enhanced penetration of the triplet component of the condensate into the Co/Cu/Co spin valve in the maximally noncollinear magnetic configuration. © 2014 American Physical Society

Search for new phenomena in a lepton plus high jet multiplicity final state with the ATLAS experiment using √s=13 TeV proton-proton collision data

A search for new phenomena in final states characterized by high jet multiplicity, an isolated lepton (electron or muon) and either zero or at least three b-tagged jets is presented. The search uses 36.1 fb−1 of √s=13 TeV proton-proton collision data collected by the ATLAS experiment at the Large Hadron Collider in 2015 and 2016. The dominant sources of background are estimated using parameterized extrapolations, based on observables at medium jet multiplicity, to predict the b-tagged jet multiplicity distribution at the higher jet multiplicities used in the search. No significant excess over the Standard Model expectation is observed and 95% confidence-level limits are extracted constraining four simplified models of R-parity-violating supersymmetry that feature either gluino or top-squark pair production. The exclusion limits reach as high as 2.1 TeV in gluino mass and 1.2 TeV in top-squark mass in the models considered. In addition, an upper limit is set on the cross-section for Standard Model tt¯tt¯ production of 60 fb (6.5 × the Standard Model prediction) at 95% confidence level. Finally, model-independent limits are set on the contribution from new phenomena to the signal-region yields