199 research outputs found
Italy’s constitutional referendum: yet another reform to improve the country’s governability
Italy will hold a constitutional referendum on 20-21 September which proposes to reduce the size of both chambers of the Italian parliament. Matthew E. Bergman provides the background to the vote and assesses the potential political consequences
What the manifestos tell us about the 2021 Dutch general election
The Netherlands will hold a general election on 17 March. Matthew E Bergman presents a comprehensive analysis of what the main parties’ manifestos indicate about the country’s current electoral dynamics
Austria's election: four things to know about the result
Austria's legislative election, held on 15 October, saw the Austrian People's Party, led by Sebastian Kurz, emerge as the largest party. Manès Weisskircher and Matthew E. Bergman highlight four things worth knowing about the results of an election that might not only be a game changer for Austrian politics, but which also reflected some of the key political developments in contemporary Western Europe
Party and leadership effects on referendum voting. The Italian 2020 constitutional referendum
Unlike other ballots, referendums do not provide voters a list of parties or candidates to choose from. Here we argue that referendum voting behaviour, however, can be understood through the lends of partisanship and the socio-economic context during the voting period. The personalisation of contemporary politics would also suggest an important role of political leadership in swaying voting decisions. The article applies this theory in analysis of the vote YES of the 2020 Italian Constitutional Referendum. We attribute the success of the 2020 referendum to the role of partisanship, leader favorability, systemic and elite discontent, and the role that interest played in voting decision. Exploring the role that party leaders may have in the voting behaviour on referenda is an area for future research, especially in an era of the presidentialized political parties
Do Nondomestic Undergraduates Choose a Major Field In Order to Maximize Grade Point Averages?
The authors investigated whether undergraduates attending an American West Coast public university who were not U.S. citizens (nondomestic) maximized their grade point averages (GPA) through their choice of major field. Multiple regression hierarchical linear modeling analyses showed that major field’s effect size was small for these undergraduates’ academic marks in mandatory English writing classes and their term GPAs in the five most recent academic years. Engineering and economics, but not science, were significant predictors of writing marks. Economics, but not engineering or science, was a significant predictor of GPAs
Quantum Hall Effect in a Holographic Model
We consider a holographic description of a system of strongly coupled
fermions in 2+1 dimensions based on a D7-brane probe in the background of
D3-branes, and construct stable embeddings by turning on worldvolume fluxes. We
study the system at finite temperature and charge density, and in the presence
of a background magnetic field. We show that Minkowski-like embeddings that
terminate above the horizon describe a family of quantum Hall states with
filling fractions that are parameterized by a single discrete parameter. The
quantization of the Hall conductivity is a direct consequence of the
topological quantization of the fluxes. When the magnetic field is varied
relative to the charge density away from these discrete filling fractions, the
embeddings deform continuously into black-hole-like embeddings that enter the
horizon and that describe metallic states. We also study the thermodynamics of
this system and show that there is a first order phase transition at a critical
temperature from the quantum Hall state to the metallic state.Comment: v2: 27 pages, 12 figures. There is a major revision in the
quantitative analysis. The qualitative results and conclusions are unchanged,
with one exception: we show that the quantum Hall state embeddings, which
exist for discrete values of the filling fraction, deform continuously into
metallic state embeddings away from these filling fraction
Holographic Nuclear Physics
We analyze the phases of the Sakai-Sugimoto model at finite temperature and
baryon chemical potential. Baryonic matter is represented either by 4-branes in
the 8-branes or by strings stretched from the 8-branes to the horizon. We find
the explicit configurations and use them to determine the phase diagram and
equation of state of the model. The 4-brane configuration (nuclear matter) is
always preferred to the string configuration (quark matter), and the latter is
also unstable to density fluctuations. In the deconfined phase the phase
diagram has three regions corresponding to the vacuum, quark-gluon plasma, and
nuclear matter, with a first-order and a second-order phase transition
separating the phases. We find that for a large baryon number density, and at
low temperatures, the dominant phase has broken chiral symmetry. This is in
qualitative agreement with studies of QCD at high density.Comment: 27 pages, 26 figures. v2: Added a comment about higher derivative
corrections to the DBI action in the smeared instanton in section 2.1. v3:
References added, version published in JHEP. v4: misprints correcte
Striped instability of a holographic Fermi-like liquid
We consider a holographic description of a system of strongly-coupled
fermions in 2+1 dimensions based on a D7-brane probe in the background of
D3-branes. The black hole embedding represents a Fermi-like liquid. We study
the excitations of the Fermi liquid system. Above a critical density which
depends on the temperature, the system becomes unstable towards an
inhomogeneous modulated phase which is similar to a charge density and spin
wave state. The essence of this instability can be effectively described by a
Maxwell-axion theory with a background electric field. We also consider the
fate of zero sound at non-zero temperature.Comment: 16 pages, 9 figures; v2: added discussion and one figure. Typos
correcte
Fluctuations of a holographic quantum Hall fluid
We analyze the neutral spectrum of the holographic quantum Hall fluid
described by the D2-D8' model. As expected for a quantum Hall state, we find
the system to be stable and gapped and that, at least over much of the
parameter space, the lowest excitation mode is a magneto-roton. In addition, we
find magneto-rotons in higher modes as well. We show that these magneto-rotons
are direct consequences of level crossings between vector and scalar modes.Comment: 20 pages, 8 figures; v.2 figures improved, 2 figures added, and text
clarified particularly in Sec. 5, to appear in JHE
Response of Holographic QCD to Electric and Magnetic Fields
We study the response of the Sakai-Sugimoto holographic model of large N_c
QCD at nonzero temperature to external electric and magnetic fields. In the
electric case we find a first-order insulator-conductor transition in both the
confining and deconfining phases of the model. In the deconfining phase the
conductor is described by the parallel 8-brane-anti-8-brane embedding with a
current of quarks and anti-quarks. We compute the conductivity and show that it
agrees precisely with a computation using the Kubo formula. In the confining
phase we propose a new kind of 8-brane embedding, corresponding to a baryonic
conductor. In the magnetic field case we show that the critical temperature for
chiral-symmetry restoration in the deconfined phase increases with the field
and approaches a finite value in the limit of an infinite magnetic field. We
also illustrate the nonlinear behavior of the electric and magnetic
susceptibilities in the different phases.Comment: 18 pages, 19 figures; reference added, version published in JHE
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