2,715 research outputs found
Explaining LIGO's observations via isolated binary evolution with natal kicks
We compare binary evolution models with different assumptions about
black-hole natal kicks to the first gravitational-wave observations performed
by the LIGO detectors. Our comparisons attempt to reconcile merger rate,
masses, spins, and spin-orbit misalignments of all current observations with
state-of-the-art formation scenarios of binary black holes formed in isolation.
We estimate that black holes (BHs) should receive natal kicks at birth of the
order of (50) km/s if tidal processes do (not) realign
stellar spins. Our estimate is driven by two simple factors. The natal kick
dispersion is bounded from above because large kicks disrupt too many
binaries (reducing the merger rate below the observed value). Conversely, the
natal kick distribution is bounded from below because modest kicks are needed
to produce a range of spin-orbit misalignments. A distribution of misalignments
increases our models' compatibility with LIGO's observations, if all BHs are
likely to have natal spins. Unlike related work which adopts a concrete BH
natal spin prescription, we explore a range of possible BH natal spin
distributions. Within the context of our models, for all of the choices of
used here and within the context of one simple fiducial parameterized
spin distribution, observations favor low BH natal spin.Comment: 19 pages, 14 figures, as published in PR
PHENIX first measurement of the J/psi elliptic flow parameter v2 in Au+Au collisions at sqrt(sNN) = 200 GeV
Recent results indicate that the J/psi suppression pattern differs with
rapidity showing a larger suppression at forward rapidity. J/psi suppression
mechanisms based on energy density (such as color screening, interaction with
co-movers, etc.) predict the opposite trend. On the other hand, it is expected
that more c\bar{c} pairs should be available to form quarkonia at mid-rapidity
via recombination. Some models provide a way to differentiate J/psi production
from initially produced c\bar{c} pairs and final state recombination of
uncorrelated pairs, via the rapidity and transverse momentum dependence of the
elliptic flow (v2).
During 2007 data taking at RHIC, a large sample of Au+Au collisions at
sqrt(sNN)=200 GeV was collected. The statistics has been increased compared to
previous 2004 data set, thus allowing a more precise measurement of the J/psi
production at both mid and forward rapidity. Furthermore, the PHENIX experiment
benefited from the addition of a new detector, which improves the reaction
plane resolution and allows us to measure the J/psi v2. Comparing this
measurement to the positive D-mesons v2 (through non-photonic electron decays)
will help constraining the J/psi production mechanisms and getting a more
precise picture of the proportion of J/psi coming from direct production or
charm quark coalescence.
Details on how the J/psi v2 is measured at both rapidities are presented. The
J/psi v2 as a function of transverse momentum are compared to existing models.Comment: 4 pages, 3 figures, Quark Matter 2008 proceeding
The Impact of Olfactory Disorders in the United Kingdom
Olfactory disorders are believed to affect 5% of the general population and have been shown to bear significant psychosocial consequences to sufferers. Although more common than blindness and profound deafness in the United Kingdom, the impact of these disorders has not been assessed to date and the plight of British patients has yet to be quantified. In 2012, a patient support organization, Fifth Sense, was founded to provide information and support to sufferers of chemosensory disorders. Following a recent members conference, a survey of the membership was conducted anonymously using a series of questions based on an existing olfactory disorders questionnaire. From 496 respondents, this has demonstrated high rates of depression (43%) and anxiety (45%), impairment of eating experience (92%), isolation (57%), and relationship difficulties (54%). Women appear to have significantly more issues than men in terms of social and domestic dysfunction relating to olfactory loss (P = 0.01). Qualitative disorders also affected more than 1 in 5 members with parosmia reported in 19% and phantosmia in 24%. This paper discusses the details of the British story of anosmia and other related disorders as depicted by those most affected
The geographical distribution and prevalence of Echinococcus multilocularis in animals in the European Union and adjacent countries : a systematic review and meta-analysis
Background
This study aimed to provide a systematic review on the geographical distribution of Echinococcus multilocularis in definitive and intermediate hosts in the European Union (EU) and adjacent countries (AC). The relative importance of the different host species in the life-cycle of this parasite was highlighted and gaps in our knowledge regarding these hosts were identified.
Methods
Six databases were searched for primary research studies published from 1900 to 2015. From a total of 2,805 identified scientific papers, 244 publications were used for meta-analyses.
Results
Studies in 21 countries reported the presence of E. multilocularis in red foxes, with the following pooled prevalence (PP): low (≤ 1 %; Denmark, Slovenia and Sweden); medium (> 1 % to 10 %; Czech Republic, Estonia, France, Germany, Latvia, Lithuania, Poland, Slovakia, Liechtenstein and Switzerland). Studies from Finland, Ireland, the United Kingdom and Norway reported the absence of E. multilocularis in red foxes. However, E. multilocularis was detected in Arctic foxes from the Arctic Archipelago of Svalbard in Norway.
Conclusions
Raccoon dogs (PP 2.2 %), golden jackals (PP 4.7 %) and wolves (PP 1.4 %) showed a higher E. multilocularis PP than dogs (PP 0.3 %) and cats (PP 0.5 %). High E. multilocularis PP in raccoon dogs and golden jackals correlated with high PP in foxes. For intermediate hosts (IHs), muskrats (PP 4.2 %) and arvicolids (PP 6.0 %) showed similar E. multilocularis PP as sylvatic definitive hosts (DHs), excluding foxes. Nutrias (PP 1.0 %) and murids (PP 1.1 %) could play a role in the life-cycle of E. multilocularis in areas with medium to high PP in red foxes. In areas with low PP in foxes, no other DH was found infected with E. multilocularis. When fox E. multilocularis PP was >3 %, raccoon dogs and golden jackals could play a similar role as foxes. In areas with high E. multilocularis fox PP, the wolf emerged as a potentially important DH. Dogs and cats could be irrelevant in the life-cycle of the parasite in Europe, although dogs could be important for parasite introduction into non-endemic areas. Muskrats and arvicolids are important IHs. Swine, insectivores, murids and nutrias seem to play a minor or no role in the life-cycle of the parasite within the EU and ACs
Measurements of double-helicity asymmetries in inclusive production in longitudinally polarized collisions at GeV
We report the double helicity asymmetry, , in inclusive
production at forward rapidity as a function of transverse momentum
and rapidity . The data analyzed were taken during
GeV longitudinally polarized collisions at the Relativistic Heavy Ion
Collider (RHIC) in the 2013 run using the PHENIX detector. At this collision
energy, particles are predominantly produced through gluon-gluon
scatterings, thus is sensitive to the gluon polarization
inside the proton. We measured by detecting the decay
daughter muon pairs within the PHENIX muon spectrometers in the
rapidity range . In this kinematic range, we measured the
to be ~(stat)~~(syst). The
can be expressed to be proportional to the product of the
gluon polarization distributions at two distinct ranges of Bjorken : one at
moderate range where recent RHIC data of jet and
double helicity spin asymmetries have shown evidence for significant gluon
polarization, and the other one covering the poorly known small- region . Thus our new results could be used to further
constrain the gluon polarization for .Comment: 335 authors, 10 pages, 4 figures, 3 tables, 2013 data. Version
accepted for publication by Phys. Rev. D. Plain text data tables for the
points plotted in figures for this and previous PHENIX publications are (or
will be) publicly available at http://www.phenix.bnl.gov/papers.htm
Centrality categorization for R_{p(d)+A} in high-energy collisions
High-energy proton- and deuteron-nucleus collisions provide an excellent tool
for studying a wide array of physics effects, including modifications of parton
distribution functions in nuclei, gluon saturation, and color neutralization
and hadronization in a nuclear environment, among others. All of these effects
are expected to have a significant dependence on the size of the nuclear target
and the impact parameter of the collision, also known as the collision
centrality. In this article, we detail a method for determining centrality
classes in p(d)+A collisions via cuts on the multiplicity at backward rapidity
(i.e., the nucleus-going direction) and for determining systematic
uncertainties in this procedure. For d+Au collisions at sqrt(s_NN) = 200 GeV we
find that the connection to geometry is confirmed by measuring the fraction of
events in which a neutron from the deuteron does not interact with the nucleus.
As an application, we consider the nuclear modification factors R_{p(d)+A}, for
which there is a potential bias in the measured centrality dependent yields due
to auto-correlations between the process of interest and the backward rapidity
multiplicity. We determine the bias correction factor within this framework.
This method is further tested using the HIJING Monte Carlo generator. We find
that for d+Au collisions at sqrt(s_NN)=200 GeV, these bias corrections are
small and vary by less than 5% (10%) up to p_T = 10 (20) GeV. In contrast, for
p+Pb collisions at sqrt(s_NN) = 5.02 TeV we find these bias factors are an
order of magnitude larger and strongly p_T dependent, likely due to the larger
effect of multi-parton interactions.Comment: 375 authors, 18 pages, 16 figures, 4 tables. Submitted to Phys. Rev.
C. Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
J/psi suppression at forward rapidity in Au+Au collisions at sqrt(s_NN)=39 and 62.4 GeV
We present measurements of the J/psi invariant yields in sqrt(s_NN)=39 and
62.4 GeV Au+Au collisions at forward rapidity (1.2<|y|<2.2). Invariant yields
are presented as a function of both collision centrality and transverse
momentum. Nuclear modifications are obtained for central relative to peripheral
Au+Au collisions (R_CP) and for various centrality selections in Au+Au relative
to scaled p+p cross sections obtained from other measurements (R_AA). The
observed suppression patterns at 39 and 62.4 GeV are quite similar to those
previously measured at 200 GeV. This similar suppression presents a challenge
to theoretical models that contain various competing mechanisms with different
energy dependencies, some of which cause suppression and others enhancement.Comment: 365 authors, 10 pages, 11 figures, 4 tables. Submitted to Phys. Rev.
C. Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
Upsilon (1S+2S+3S) production in d+Au and p+p collisions at sqrt(s_NN)=200 GeV and cold-nuclear matter effects
The three Upsilon states, Upsilon(1S+2S+3S), are measured in d+Au and p+p
collisions at sqrt(s_NN)=200 GeV and rapidities 1.2<|y|<2.2 by the PHENIX
experiment at the Relativistic Heavy-Ion Collider. Cross sections for the
inclusive Upsilon(1S+2S+3S) production are obtained. The inclusive yields per
binary collision for d+Au collisions relative to those in p+p collisions
(R_dAu) are found to be 0.62 +/- 0.26 (stat) +/- 0.13 (syst) in the gold-going
direction and 0.91 +/- 0.33 (stat) +/- 0.16 (syst) in the deuteron-going
direction. The measured results are compared to a nuclear-shadowing model,
EPS09 [JHEP 04, 065 (2009)], combined with a final-state breakup cross section,
sigma_br, and compared to lower energy p+A results. We also compare the results
to the PHENIX J/psi results [Phys. Rev. Lett. 107, 142301 (2011)]. The rapidity
dependence of the observed Upsilon suppression is consistent with lower energy
p+A measurements.Comment: 495 authors, 11 pages, 9 figures, 5 tables. Submitted to Phys. Rev.
C. Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
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