304 research outputs found
Rashbons: Properties and their significance
In presence of a synthetic non-Abelian gauge field that induces a Rashba like
spin-orbit interaction, a collection of weakly interacting fermions undergoes a
crossover from a BCS ground state to a BEC ground state when the strength of
the gauge field is increased [Phys. Rev. B {\bf 84}, 014512 (2011)]. The BEC
that is obtained at large gauge coupling strengths is a condensate of tightly
bound bosonic fermion-pairs whose properties are solely determined by the
Rashba gauge field -- hence called rashbons. In this paper, we conduct a
systematic study of the properties of rashbons and their dispersion. This study
reveals a new qualitative aspect of the problem of interacting fermions in
non-Abelian gauge fields, i.e., that the rashbon state induced by the gauge
field for small centre of mass momenta of the fermions ceases to exist when
this momentum exceeds a critical value which is of the order of the gauge
coupling strength. The study allows us to estimate the transition temperature
of the rashbon BEC, and suggests a route to enhance the exponentially small
transition temperature of the system with a fixed weak attraction to the order
of the Fermi temperature by tuning the strength of the non-Abelian gauge field.
The nature of the rashbon dispersion, and in particular the absence of the
rashbon states at large momenta, suggests a regime of parameter space where the
normal state of the system will be a dynamical mixture of uncondensed rashbons
and unpaired helical fermions. Such a state should show many novel features
including pseudogap physics.Comment: 8 pages, 6 figure
Safety and efficacy of intracoronary hypoxia-preconditioned bone marrow mononuclear cell administration for acute myocardial infarction patients: The CHINA-AMI randomized controlled trial
published_or_final_versio
An amplitude analysis of the system produced in radiative decays
An amplitude analysis of the system produced in radiative
decays is presented. In particular, a piecewise function that
describes the dynamics of the system is determined as a
function of from an analysis of the
decays collected by the BESIII detector.
The goal of this analysis is to provide a description of the scalar and tensor
components of the system while making minimal assumptions about
the properties or number of poles in the amplitude. Such a model-independent
description allows one to integrate these results with other related results
from complementary reactions in the development of phenomenological models,
which can then be used to directly fit experimental data to obtain parameters
of interest. The branching fraction of is
determined to be , where the uncertainty is
systematic only and the statistical uncertainty is negligible.Comment: Submitted to Phys. Rev. D 19 pages, 4 figure
Measurement of the branching fractions of and in
We study decays to final states involving the with a
482pb data sample collected at = 4.009GeV with the
\mbox{BESIII} detector at the BEPCII collider. We measure the branching
fractions = (8.81.80.5)
and = ()
where the first uncertainty is statistical and the second is systematic. In
addition, we estimate an upper limit on the non-resonant branching ratio
at the 90
confidence level. Our results are consistent with CLEO's recent measurements
and help to resolve the disagreement between the theoretical prediction and
CLEO's previous measurement of
Measurement of the leptonic decay width of using initial state radiation
Using a data set of 2.93 fb taken at a center-of-mass energy of
= 3.773 GeV with the BESIII detector at the BEPCII collider, we
measure the process and determine the product of the branching fraction and the
electronic width ~eV. Using the earlier-published BESIII result for
= (5.973 0.007 0.037)\%, we derive the electronic width ~= (5.58
0.05 0.08) keV.Comment: 8 pages, 2 figure
Measurement of the Matrix Elements for the Decays and
Based on a sample of events collected with the
BESIII detector at the BEPCII collider, Dalitz plot analyses of selected 79,625
events, 33,908
events and 1,888
events are performed. The measured
matrix elements of are in reasonable agreement
with previous measurements. The Dalitz plot slope parameters of
and
are determined to be and , respectively, where the first uncertainties are statistical and the
second systematic. Both values are consistent with previous measurements, while
the precision of the latter one is improved by a factor of three. Final state
interactions are found to have an important role in those decays.Comment: 12 pages, 7 figure
Measurement of the proton form factor by studying
Using data samples collected with the BESIII detector at the BEPCII collider,
we measure the Born cross section of at 12
center-of-mass energies from 2232.4 to 3671.0 MeV. The corresponding effective
electromagnetic form factor of the proton is deduced under the assumption that
the electric and magnetic form factors are equal . In
addition, the ratio of electric to magnetic form factors, , and
are extracted by fitting the polar angle distribution of the proton
for the data samples with larger statistics, namely at 2232.4 and
2400.0 MeV and a combined sample at = 3050.0, 3060.0 and 3080.0 MeV,
respectively. The measured cross sections are in agreement with recent results
from BaBar, improving the overall uncertainty by about 30\%. The
ratios are close to unity and consistent with BaBar results in
the same region, which indicates the data are consistent with the
assumption that within uncertainties.Comment: 13 pages, 24 figure
Observation of the isospin-violating decay
Using a sample of 1.31 billion events collected with the BESIII
detector at the BEPCII collider, the decays and are
investigated. The isospin violating decay
with , is observed for the first time. The width of the
obtained from the dipion mass spectrum is found to be much smaller
than the world average value. In the mass spectrum, there
is evidence of production. By studying the decay , the branching fractions of and
, as well as their ratio, are also measured.Comment: 10 pages, 10 figures, published in Phys. Rev.
Search for the weak decay and precise measurement of the branching fraction
We present the first search for the rare decay of into
in , using a sample of
events collected with the BESIII detector. No
significant signal is observed, and the upper limit at the 90\% confidence
level for the ratio is determined to be
. In addition, we report the measurement of the branching
fraction of to be
, which agrees
with previous results from BESII
Search for and improved measurement of the branching fraction for
Using fb of electron-positron annihilation data collected at
~GeV with the BESIII detector, we report the results of a
search for the flavor-changing neutral current process
using a double-tag technique. We find no signal and set an upper limit at
confidence level for the branching fraction of . We also investigate -meson decay into two neutral
pions, obtaining a branching fraction of , the most
precise measurement to date and consistent with the current world averageComment: Minor revisions, version published in Physical Review
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