1,915 research outputs found

    Non-Abelian Vortices with a Twist

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    Non-Abelian flux-tube (string) solutions carrying global currents are found in the bosonic sector of 4-dimensional N=2 super-symmetric gauge theories. The specific model considered here posseses U(2)local x SU(2)global symmetry, with two scalar doublets in the fundamental representation of SU(2). We construct string solutions that are stationary and translationally symmetric along the x3 direction, and they are characterized by a matrix phase between the two doublets, referred to as "twist". Consequently, twisted strings have nonzero (global) charge, momentum, and in some cases even angular momentum per unit length. The planar cross section of a twisted string corresponds to a rotationally symmetric, charged non-Abelian vortex, satisfying 1st order Bogomolny-type equations and 2nd order Gauss-constraints. Interestingly, depending on the nature of the matrix phase, some of these solutions even break rotational symmetry in R3. Although twisted vortices have higher energy than the untwisted ones, they are expected to be linearly stable since one can maintain their charge (or twist) fixed with respect to small perturbations.Comment: 18 pages, 5 figure

    A History of the Cold War

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    It\u27s Complicated: Romantic Breakups and Their Aftermath on Facebook

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    Little research examines the ways in which Facebook affects breakups. This exploratory study aimed to determine the prevalence of breakup practices unique to Facebook; to gain an understanding of the relationship between Facebook use and distress following a breakup; and to determine what strategies people use to cope with romantic breakups in the Facebook era. This topic was examined using a mixed methods approach that included a survey and semi-structured interviews. Findings show that content on Facebook can be a source of distress for individuals who have recently experienced a romantic breakup. People who engaged in high levels of interpersonal electronic surveillance experienced more breakup distress and Facebook breakup distress than people who did not. Coping mechanisms for dealing with distress caused by content on Facebook following a breakup are complex, as many coping mechanisms can create new distressing situations

    Applications of Commutator-Type Operators to pp-Groups

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    For a p-group G admitting an automorphism ϕ\phi of order pnp^n with exactly pmp^m fixed points such that ϕpn1\phi^{p^{n-1}} has exactly pkp^k fixed points, we prove that G has a fully-invariant subgroup of m-bounded nilpotency class with (p,n,m,k)(p,n,m,k)-bounded index in G. We also establish its analogue for Lie p-rings. The proofs make use of the theory of commutator-type operators.Comment: 11 page

    Quantum dynamics and entanglement of a 1D Fermi gas released from a trap

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    We investigate the entanglement properties of the nonequilibrium dynamics of one-dimensional noninteracting Fermi gases released from a trap. The gas of N particles is initially in the ground state within hard-wall or harmonic traps, then it expands after dropping the trap. We compute the time dependence of the von Neumann and Renyi entanglement entropies and the particle fluctuations of spatial intervals around the original trap, in the limit of a large number N of particles. The results for these observables apply to one-dimensional gases of impenetrable bosons as well. We identify different dynamical regimes at small and large times, depending also on the initial condition, whether it is that of a hard-wall or harmonic trap. In particular, we analytically show that the expansion from hard-wall traps is characterized by the asymptotic small-time behavior S(1/3)ln(1/t)S \approx (1/3)\ln(1/t) of the von Neumann entanglement entropy, and the relation Sπ2V/3S\approx \pi^2 V/3 where V is the particle variance, which are analogous to the equilibrium behaviors whose leading logarithms are essentially determined by the corresponding conformal field theory with central charge c=1c=1. The time dependence of the entanglement entropy of extended regions during the expansion from harmonic traps shows the remarkable property that it can be expressed as a global time-dependent rescaling of the space dependence of the initial equilibrium entanglement entropy.Comment: 19 pages, 18 fig

    Exponential families of mixed Poisson distributions

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    If I=(I1,…,Id) is a random variable on [0,∞)d with distribution μ(dλ1,…,dλd), the mixed Poisson distribution MP(μ) on View the MathML source is the distribution of (N1(I1),…,Nd(Id)) where N1,…,Nd are ordinary independent Poisson processes which are also independent of I. The paper proves that if F is a natural exponential family on [0,∞)d then MP(F) is also a natural exponential family if and only if a generating probability of F is the distribution of v0+v1Y1+cdots, three dots, centered+vqYq for some qless-than-or-equals, slantd, for some vectors v0,…,vq of [0,∞)d with disjoint supports and for independent standard real gamma random variables Y1,…,Yq

    The Effects of Special Mule Deer Buck Regulations on Mule Deer Populations and Harvest

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    We evaluated the effects of 3 restrictive season types on mule deer population and harvest characteristics in 41 Montana hunting districts (HDs). Using a mixed-effects, before-after-control-impact modeling framework, we analyzed 6 harvest and hunter use response variables, and 4 population response variables. Buck : doe ratios increased by 0.42 bucks:100 does and 0.33 bucks :100 does per year, following changes to a shortened season and limited permits, respectively. We found no significant change in buck : doe ratios in unlimited permit HDs. All restrictive season types resulted in declines in hunter numbers and days. HDs with no restrictions, with limited permits and with unlimited permits also showed a downward annual trend in hunter numbers. In shortened season HDs, a significant loss in hunter numbers was followed by a slow return of hunters back to those HDs. Limited permit HDs had a statistically greater proportion of bucks with ?4 points on at least one antler, a lower number of bucks harvested annually, and a smaller total number of ?4 point bucks harvested than in HDs with no buck restrictions. For those same 3 response variables, unlimited and shortened season HDs were not different than HDs without restrictions. In all three restricted regulation HDs there was an annual increase in the observed spring fawn : adult ratios even though the general trend was for a decreasing fawn : adult ratio of 0.83 fawns:100 adults per year in HDs with no restrictions

    Is it time for studying real-life debiasing? Evaluation of the effectiveness of an analogical intervention technique.

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    The aim of this study was to initiate the exploration of debiasing methods applicable in real-life settings for achieving lasting improvement in decision making competence regarding multiple decision biases. Here, we tested the potentials of the analogical encoding method for decision debiasing. The advantage of this method is that it can foster the transfer from learning abstract principles to improving behavioral performance. For the purpose of the study, we devised an analogical debiasing technique for 10 biases (covariation detection, insensitivity to sample size, base rate neglect, regression to the mean, outcome bias, sunk cost fallacy, framing effect, anchoring bias, overconfidence bias, planning fallacy) and assessed the susceptibility of the participants (N = 154) to these biases before and 4 weeks after the training. We also compared the effect of the analogical training to the effect of 'awareness training' and a 'no-training' control group. Results suggested improved performance of the analogical training group only on tasks where the violations of statistical principles are measured. The interpretation of these findings require further investigation, yet it is possible that analogical training may be the most effective in the case of learning abstract concepts, such as statistical principles, which are otherwise difficult to master. The study encourages a systematic research of debiasing trainings and the development of intervention assessment methods to measure the endurance of behavior change in decision debiasing
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