4,507 research outputs found
Role of medium modifications for neutrino-pair processes from nucleon-nucleon bremsstrahlung - Impact on the protoneutron star deleptonization
In this article the neutrino-pair production from nucleon-nucleon (NN)
bremsstrahlung is explored via medium-modifications of the strong interactions
at the level of the one-pion exchange approximation. It governs the bulk part
of the NN interaction at low densities relevant for the neutrino physics in
core-collapse supernova studies. The resulting medium modified one-pion
exchange rate for the neutrino-pair processes is implemented in simulations of
core collapse supernovae in order to study the impact on the neutrino signal
emitted from the deleptonization of the nascent proto-neutron star.
Consequences for the nucleosynthesis of heavy elements of the material ejected
from the PNS surface are discussed.Comment: 9 pages, 7 figures, accepted for publication in Astronomy &
Astrophysic
Music and Aggression: The Impact of Sexual-Aggressive Song Lyrics on Aggression-Related Thoughts, Emotions, and Behavior Toward the Same and the Opposite Sex
Three studies examined the impact of sexual-aggressive song lyrics on aggressive thoughts, emotions, and behavior toward the same and the opposite sex. In Study 1, the authors directly manipulated whether male or female participants listened to misogynous or neutral song lyrics and measured actual aggressive behavior. Male participants who were exposed to misogynous song lyrics administered more hot chili sauce to a female than to a male confederate. Study 2 shed some light on the underlying psychological processes: Male participants who heard misogynous song lyrics recalled more negative attributes of women and reported more feelings of vengeance than when they heard neutral song lyrics. In addition, men-hating song lyrics had a similar effect on aggression-related responses of female participants toward men. Finally, Study 3 replicated the findings of the previous two studies with an alternative measure of aggressive behavior as well as a more subtle measure of aggressive cognitions. The results are discussed in the framework of the General Aggression Model
Drones for parcel and passenger transportation: A literature review
Delivery drones and âair taxisâ are currently among the most intensely discussed emerging technologies, likely to expand mobility into the âthird dimensionâ of low-level airspace. This paper presents a systematic literature review of 111 interdisciplinary publications (2013 - 03/2019). The review systematizes the current socio-technical debate on civil drones for transportation purposes allowing for a (critical) interim assessment. To guide the review process four dimensions of analysis were defined. A total of 2581 relevant quotations were subdivided into anticipated barriers (426), potential problems (1037), proposed solutions (737) and expected benefits (381). We found that the debate is characterized by predominantly technical and regulatory problems and barriers which are considered to prevent or impede the use of drones for parcel and passengers transportation. At the same time, definite economic expectations are juxtaposed with quite complex and differentiated concerns regarding societal and environmental impacts. Scrutinizing the most prevalent transportation-related promises of traffic reduction, travel time saving and environmental relief we found that there is a strong need to provide scientific evidence for the promises linked to the use of drones for transportation. We conclude that the debate on drones for transportation needs further qualification, emphasizing societal benefits and public involvement more strongly.TU Berlin, Open-Access-Mittel - 201
Consequences of simultaneous chiral symmetry breaking and deconfinement for the isospin symmetric phase diagram
The thermodynamic bag model (tdBag) has been applied widely to model quark
matter properties in both heavy-ion and astrophysics communities. Several
fundamental physics aspects are missing in tdBag, e.g., dynamical chiral
symmetry breaking (DSB) and repulsions due to the vector interaction are
both included explicitly in the novel vBag quark matter model of Kl\"ahn and
Fischer (2015) (Astrophys. J. 810, 134 (2015)). An important feature of vBag is
the simultaneous DSB and deconfinement, where the latter links vBag to a
given hadronic model for the construction of the phase transition. In this
article we discuss the extension to finite temperatures and the resulting phase
diagram for the isospin symmetric medium.Comment: 6 pages, 2 figures, Contribution to the Topical Issue Exploring
strongly interacting matter at high densities - NICA White Paper edited by
David Blaschke et a
Beyond Rainbow-Ladder in bound state equations
In this work we devise a new method to study quark anti-quark interactions
beyond simple ladder-exchange that yield massless pions in the chiral limit.
The method is based on the requirement to have a representation of the
quark-gluon vertex that is explicitly given in terms of quark dressings
functions. We outline a general procedure to generate the Bethe-Salpeter kernel
for a given vertex representation. Our method allows not only the
identification of the mesons' masses but also the extraction of their
Bethe-Salpeter wave functions exposing their internal structure. We exemplify
our method with vertex models that are of phenomenological interest.Comment: 13 pages, 6 figures; v2: typos corrected, colors improve
The role of momentum dependent dressing functions and vector meson dominance in hadronic light-by-light contributions to the muon g-2
We present a refined calculation of the quark-loop contribution to hadronic
light-by-light scatter- ing that focuses upon the impact of the transverse
components of the quark-photon vertex. These structures are compared and
contrasted with those found within the extended NJL-models. We discuss
similarities and differences between the two approaches and further clarify the
important role of momentum dependent dressing functions. As expected we find
that the transverse structures of the quark-photon vertex lead to a suppression
of the quark-loop contribution to the anomalous magnetic moment of the muon.
However, we find evidence that this suppression is overestimated within models
with simple approximations for the quark-photon interaction.Comment: 13 pages, 5 figures, v2: typos corrected, references added, version
submitted to PR
A fresh look at hadronic light-by-light scattering in the muon g-2 with the Dyson-Schwinger approach
We present first results for the hadronic light-by-light scattering
contribution to the anomalous magnetic moment of the muon a_{\mu} in the
framework of Dyson-Schwinger and Bethe-Salpeter equations. We determine the
quark loop and pseudoscalar ({\pi}^0, {\eta}, {\eta}') meson exchange diagram
using a phenomenological model for the combined strength of the gluon
propagator and the quark-gluon interaction as the only input. Our result for
meson exchange, a_{\mu}^{LBL;PS}=(84 \pm 13) x 10^{-11}, is commensurate with
previous calculations. However, our number for the quark loop contribution,
a_{\mu}^{LBL;quarkloop} = (107 \pm 2 \pm 46) x 10^{-11}, is significantly
larger due to dressing effects in the quark propagator and the quark-photon
vertex. Taken at face value, this then leads to a revised estimate of the total
a_{\mu}=116 591 865.0(96.6) x 10^{-11}, which reduces the difference between
theory and experiment to about 1.9 {\sigma}.Comment: 5 pages, 7 figures, v2: title slightly changed, minor corrections,
version accepted by EP
Low-momentum pion enhancement from schematic hadronization of a gluon-saturated initial state
We study the particle production in the early stage of the ultrarelativistic
heavy-ion collisions. To this end the Boltzmann kinetic equations for gluons
and pions with elastic rescattering are considered together with a simple model
for the parton-hadron conversion process (hadronisation). It is shown that the
overpopulation of the gluon phase space in the initial state leads to an
intermediate stage of Bose enhancement in the low-momentum gluon sector which
due to the gluon-pion conversion process is then reflected in the final
distribution function of pions. This pattern is very similar to the
experimental finding of a low-momentum pion enhancement in the ALICE experiment
at CERN LHC. Relations to the thermal statistical model of hadron production
and the phenomenon of thermal and chemical freeze-out are discussed in this
context
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