Collective Quartics and Dangerous Singlets in Little Higgs

Any extension of the standard model that aims to describe TeV-scale physics without fine-tuning must have a radiatively-stable Higgs potential. In little Higgs theories, radiative stability is achieved through so-called collective symmetry breaking. In this letter, we focus on the necessary conditions for a little Higgs to have a collective Higgs quartic coupling. In one-Higgs doublet models, a collective quartic requires an electroweak triplet scalar. In two-Higgs doublet models, a collective quartic requires a triplet or singlet scalar. As a corollary of this study, we show that some little Higgs theories have dangerous singlets, a pathology where collective symmetry breaking does not suppress quadratically-divergent corrections to the Higgs mass.Comment: 4 pages; v2: clarified the existing literature; v3: version to appear in JHE

Reference Distorted Prices

I show that when consumers (mis)perceive prices relative to reference prices, budgets turn out to be soft, prices tend to be lower and the average quality of goods sold decreases. These observations provide explanations for decentralized purchase decisions, for people being happy with a purchase even when they have paid their evaluation, and for why trade might affect high quality local firms 'unfairly'

Physical and magnetic properties of Ba(Fe1−x_{1-x}Rux_x)2_2As2_2 single crystals

Single crystals of Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$, $x<0.37$, have been grown and characterized by structural, magnetic and transport measurements. These measurements show that the structural/magnetic phase transition found in pure BaFe$_2$As$_2$ at 134 K is suppressed monotonically by Ru doping, but, unlike doping with TM=Co, Ni, Cu, Rh or Pd, the coupled transition seen in the parent compound does not detectably split into two separate ones. Superconductivity is stabilized at low temperatures for $x>0.2$ and continues through the highest doping levels we report. The superconducting region is dome like, with maximum T$_c$ ($\sim16.5$ K) found around $x\sim 0.29$. A phase diagram of temperature versus doping, based on electrical transport and magnetization measurements, has been constructed and compared to those of the Ba(Fe$_{1-x}$TM$_x$)$_2$As$_2$ (TM=Co, Ni, Rh, Pd) series as well as to the temperature-pressure phase diagram for pure BaFe$_2$As$_2$. Suppression of the structural/magnetic phase transition as well as the appearance of superconductivity is much more gradual in Ru doping, as compared to Co, Ni, Rh and Pd doping, and appears to have more in common with BaFe$_2$As$_2$ tuned with pressure; by plotting $T_S/T_m$ and $T_c$ as a function of changes in unit cell dimensions, we find that changed in the $c/a$ ratio, rather than changes in $c$, $a$ or V, unify the $T(p)$ and $T(x)$ phase diagrams for BaFe$_2$As$_2$ and Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$ respectively.Comment: 16 pages, 10 figure

Social justice in the context of adaptation to climate change – reflecting on different policy approaches to distribute and allocate flood risk management

Editorial to a special edition of the journal. Consequences of extreme hydrological events, such as those recently experienced in United States (e.g. Hurricane Harvey or Irma in 2017), floods in South Asia in 2017, or the Central European floods in 2013 and 2016, have again focused the attention of society, policy makers and academic scholars on questions of how to reduce vulnerability to such events, especially when faced with the dual challenges of climate and societal change. Not only is the likelihood of floods increasing (e.g. IPCC 2014), but, due to continuing development in hazard-prone zones, the so called bullseye effect which argues that increasing disaster frequency is largely due to increasing exposure, and the resulting higher degree of vulnerability in floodplains, it becomes more and more challenging to protect all properties to the same standard (see discussion around residual risk, Ashley et al. 2014; Jongman et al. 2015; Fuchs et al. 2017a). Hence, the outcome of current flood risk management strategies in many situations are necessitating changes to the current social contract between state and society, requiring a re-design of the role of central government and individual citizens and communities in terms of sharing responsibilities (Adger et al. 2013; Doorn 2016). In particular, government often encourages society to take the lead in the responsibility for flood risk management, but apparently with conflicts and misunderstandings arising (Harris 2012; Kuhlicke et al. 2016; Fuchs et al. 2017b) as well as potentially introducing inequalities in flood risk management outcomes. In Europe, we can already observe these aspects in recent developments, which have led to a re-arrangement of roles and responsibilities for flood risk management, such as introduction of Partnership Funding in England and Wales or Canada ‘risk-based’ stormwater charge (Thaler and Priest 2014; Geaves and Penning-Rowsell 2016; Thaler and Levin-Keitel 2016; Henstra and Thistlethwaite 2017). However, discussion and research concerning the implications of social justice and injustice in these new flood risk management debates is scarce (Johnson et al. 2007; Doorn 2015; Thaler and Hartmann 2016)

Little Technicolor

Inspired by the AdS/CFT correspondence, we show that any G/H symmetry breaking pattern can be described by a simple two-site moose diagram. This construction trivially reproduces the CCWZ prescription in the context of Hidden Local Symmetry. We interpret this moose in a novel way to show that many little Higgs theories can emerge from ordinary chiral symmetry breaking in scaled-up QCD. We apply this reasoning to the simple group little Higgs to see that the same low energy degrees of freedom can arise from a variety of UV complete theories. We also show how models of holographic composite Higgs bosons can turn into brane-localized little technicolor theories by "integrating in" the IR brane.Comment: 26 pages, 2 figures; v2: references added; v3: added section on vacuum alignment to match JHEP versio

Limit laws for distorted return time processes for infinite measure preserving transformations

We consider conservative ergodic measure preserving transformations on infinite measure spaces and investigate the asymptotic behaviour of distorted return time processes with respect to sets satisfying a type of Darling-Kac condition. We identify two critical cases for which we prove uniform distribution laws. For this we introduce the notion of uniformly returning sets and discuss some of their properties.Comment: 18 pages, 2 figure