77 research outputs found
Search for the Chiral Magnetic Wave with Anisotropic Flow of Identified Particles at RHIC-STAR
The chiral magnetic wave (CMW) has been theorized to propagate in the
Quark-Gluon Plasma formed in high-energy heavy-ion collisions. It could cause a
finite electric quadrupole moment of the collision system, and may be observed
as a dependence of elliptic flow, , on the asymmetry between positively
and negatively charged hadrons, . However, non-CMW mechanisms, such
as local charge conservation (LCC) and hydrodynamics with isospin effect, could
also contribute to the experimental observations. Here we present the STAR
measurements of elliptic flow and triangular flow of charged
pions, along with of charged kaons and protons, as functions of in Au+Au collisions at = 200 GeV. The slope parameters
of () and () are reported
and compared to investigate the LCC background. The similarity between pion and
kaon slopes suggests that the hydrodynamics is not the dominant mechanism. The
difference between the normalized and slopes,
together with the small slopes in p+Au and d+Au collisions at = 200 GeV, suggest that the CMW picture remains a viable interpretation
at RHIC.Comment: 4 pages, 2 figures. Proceedings of Quark Matter 2018, Venice, Ital
Investigating the NCQ scaling of elliptic flow at LHC with a multiphase transport model
The number of constituent quark (NCQ) scaling behavior of elliptic flow has
been systematically studied at the LHC energy within the framework of a
multiphase transport model (AMPT) in this work. We find that the parameters
used to generate the initial states and the collision centrality are important
for the existence of NCQ scaling even when hadronic rescattering contribution
is off in Pb-Pb collisions of TeV. By turning on the
hadron rescattering process, the hadronic evolution impacts are also found to
be significant. Extending the analysis to Pb-Pb collsions of
TeV, one would observe similar qualitative features
Charge-dependent transverse momentum and its impact on the search for the chiral magnetic wave
The chiral magnetic wave (CMW) is sought using the charge asymmetry () dependence of anisotropic flow in heavy-ion collisions. The charge
dependent transverse momentum (), however, could play a role as a
background. With the string fragmentation models, including PYTHIA, we
demonstrate the origin of the correlation and its
connection with the local charge conservation (LCC). The impact of and its behavior in varied kinematic windows are also discussed.
This study provides more insights for the search for the CMW and comprehending
the collective motion of the quark-gluon plasma.Comment: 6 pages, 6 figure
Investigating high energy proton proton collisions with a multi-phase transport model approach based on PYTHIA8 initial conditions
The striking resemblance of high multiplicity proton-proton (pp) collisions
at the LHC to heavy ion collisions challenges our conventional wisdom on the
formation of the Quark-Gluon Plasma (QGP). A consistent explanation of the
collectivity phenomena in pp will help us to understand the mechanism that
leads to the QGP-like signals in small systems. In this study, we introduce a
transport model approach connecting the initial conditions provided by PYTHIA8
with subsequent AMPT rescatterings to study the collective behavior in high
energy pp collisions. The multiplicity dependence of light hadron productions
from this model is in reasonable agreement with the pp TeV
experimental data. It is found in the comparisons that both the partonic and
hadronic final state interactions are important for the generation of the
radial flow feature of the pp transverse momentum spectra. The study also shows
that the long range two particle azimuthal correlation in high multiplicity pp
events is sensitive to the proton sub-nucleon spatial fluctuations
Interpreting the charge-dependent flow and constraining the chiral magnetic wave with event shape engineering
The charge asymmetry (Ach) dependence of anisotropic flow serves as an
important tool to search for the chiral magnetic wave (CMW) in heavy-ion
collisions. However, the background effect, such as the local charge
conservation (LCC) entwined with collective flow, has not yet been
unambiguously eliminated in the measurement. With the help of two models, the
AMPT with initial quadrupole moment and the blast wave (BW) incorporating LCC,
we discuss the features of the LCC-induced and the CMW-induced correlations
between Ach and the flow. More importantly, we first propose to use the Event
Shape Engineering (ESE) technique to distinguish the background and the signal
for the CMW study. This method would be highly desirable in the experimental
search for the CMW and provides more insights for understanding the
charge-dependent collective motion of the quark-gluon plasma.Comment: 7 pages, 5 figure
Global constraint on the magnitude of anomalous chiral effects in heavy-ion collisions
When searching for anomalous chiral effects in heavy-ion collisions, one of
the most crucial points is the relationship between the signal and the
background. In this letter, we present a simulation in a modified blast wave
model at LHC energy, which can simultaneously characterize the majority of
measurable quantities, in particular, the chiral magnetic effect (CME) and the
chiral magnetic wave (CMW) observables. Such a universal description, for the
first time, naturally and quantitatively unifies the CME and the CMW studies
and brings to light the connection with the local charge conservation (LCC)
background. Moreover, a simple phenomenological approach is performed to
introduce the signals, aiming at quantifying the maximum allowable strength of
the signals within experimental precision. Such a constraint provides a novel
perspective to understand the experimental data and sheds new light on the
study of anomalous chiral effects as well as charge dependent correlations.Comment: 8 pages, 5 figure
Frequent occurrence of unreduced gametes in Triticum turgidum-Aegilops tauschii hybrids.
Abstract Spontaneous chromosome doubling via union of unreduced (2n) gametes has been thought to be the way that common wheat (Triticum aestivum L.) was originated from the hybridization of T. turgidum L. with Ae. tauschii Cosson. Previous works have observed unreduced gametes in F 1 hybrids of Ae. tauschii with six of the eight T. turgidum subspecies. It is not clear, however, whether the formation of these unreduced gametes is a norm in the F 1 hybrids. In the present study, we tried to answer this question by assessing the occurrence frequency of unreduced gametes in 115 T. turgidum-Ae. tauschii hybrid combinations, involving 76 genotypes of seven T. turgdium subspecies and 24 Ae. tauschii accessions. Our data show that these hybrid combinations differed significantly (P B 0.01, F = 11.40) in selfed seedset, an indicator for production of unreduced gametes. This study clearly showed that meiotic restitution genes are widely distributed within T. turgidum. However, significant differences were found between as well as within T. turgidum subspecies and in the interaction of the T. turgidum genotypes with those of Ae. taushii. The possible application of the meiotic restitution genes from T. turgidum in production of double haploids is also discussed
Viral Small Interfering RNAs Target Host Genes to Mediate Disease Symptoms in Plants
The Cucumber mosaic virus (CMV) Y-satellite RNA (Y-Sat) has a
small non-protein-coding RNA genome that induces yellowing symptoms in infected
Nicotiana tabacum (tobacco). How this RNA pathogen induces
such symptoms has been a longstanding question. We show that the yellowing
symptoms are a result of small interfering RNA (siRNA)-directed RNA silencing of
the chlorophyll biosynthetic gene, CHLI. The CHLI mRNA contains a 22-nucleotide
(nt) complementary sequence to the Y-Sat genome, and in Y-Sat-infected plants,
CHLI expression is dramatically down-regulated. Small RNA sequencing and
5β² RACE analyses confirmed that this 22-nt sequence was targeted for mRNA
cleavage by Y-Sat-derived siRNAs. Transformation of tobacco with a RNA
interference (RNAi) vector targeting CHLI induced Y-Sat-like symptoms. In
addition, the symptoms of Y-Sat infection can be completely prevented by
transforming tobacco with a silencing-resistant variant of the CHLI gene. These
results suggest that siRNA-directed silencing of CHLI is solely responsible for
the Y-Sat-induced symptoms. Furthermore, we demonstrate that two
Nicotiana species, which do not develop yellowing symptoms
upon Y-Sat infection, contain a single nucleotide polymorphism within the
siRNA-targeted CHLI sequence. This suggests that the previously observed species
specificity of Y-Sat-induced symptoms is due to natural sequence variation in
the CHLI gene, preventing CHLI silencing in species with a mismatch to the Y-Sat
siRNA. Taken together, these findings provide the first demonstration of small
RNA-mediated viral disease symptom production and offer an explanation of the
species specificity of the viral disease
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