30,571 research outputs found
Measuring the ratio of and couplings through production
For a generic Higgs boson, measuring the relative sign and magnitude of its
couplings with the and bosons is essential in determining its origin.
Such a test is also indispensable for the 125-GeV Higgs boson. We propose that
the ratio of the and couplings can be directly
determined through the production, where denotes a generic Higgs
boson, owing to the tree-level interference effect. While this is impractical
at the LHC due to the limited sensitivity, it can be done at future
colliders, such as a 500-GeV ILC with the beam polarization
in the and
channels. The discovery potential of a
general ratio and the power to discriminate it from the SM value are studied in
detail. Combining the cross section of with the
measurements of coupling at the HL-LHC, one can further improve the
sensitivity of .Comment: 24 pages, 10 figures, 2 table
Nuclear stopping and sideward-flow correlation from 0.35A to 200A GeV
The correlation between the nuclear stopping and the scale invariant nucleon
sideward flow at energies ranging from those available at the GSI heavy ion
synchrotron (SIS) to those at the CERN Super Proton Synchrotron (SPS) is
studied within ultrarelativistic quantum molecular dynamics (UrQMD). The
universal behavior of the two experimental observables for various colliding
systems and scale impact parameters are found to be highly correlated with each
other. As there is no phase transition mechanism involved in the UrQMD, the
correlation may be broken down by the sudden change of the bulk properties of
the nuclear matter, such as the formation of quark-gluon plasma (QGP), which
can be employed as a QGP phase transition signal in high-energy heavy ion
collisions. Furthermore, we also point out that the appearance of a breakdown
of the correlation may be a powerful tool for searching for the critical point
on the QCD phase diagram.Comment: 5 pages, 4 figure
Bar-induced central star formation as revealed by integral field spectroscopy from CALIFA
We investigate the recent star formation history (SFH) in the inner region of
57 nearly face-on spiral galaxies selected from the Calar Alto Legacy Integral
Field Area (CALIFA) survey. For each galaxy we use the integral field
spectroscopy from CALIFA to obtain two-dimensional maps and radial profiles of
three parameters that are sensitive indicators of the recent SFH: the 4000\AA\
break (D(4000)), and the equivalent width of H absorption
(EW(H)) and H emission (EW(H)). We have also
performed photometric decomposition of bulge/bar/disk components based on SDSS
optical image. We identify a class of 17 "turnover" galaxies whose central
region present significant drop in D(4000), and most of them
correspondingly show a central upturn in EW(H) and EW(H).
This indicates that the central region of the turnover galaxies has experienced
star formation in the past 1-2 Gyr, which makes the bulge younger and more
star-forming than surrounding regions. We find almost all (15/17) the turnover
galaxies are barred, while only half of the barred galaxies in our sample
(15/32) are classified as a turnover galaxy. This finding provides strong
evidence in support of the theoretical expectation that the bar may drive gas
from the disc inward to trigger star formation in galaxy center, an important
channel for the growth/rejuvenation of pseudobulges in disc galaxies.Comment: 19 pages, 10 figures, ApJ accepte
Search for a heavy dark photon at future colliders
A coupling of a dark photon from a with the standard model
(SM) particles can be generated through kinetic mixing represented by a
parameter . A non-zero also induces a mixing between
and if dark photon mass is not zero. This mixing can be large when
is close to even if the parameter is small. Many
efforts have been made to constrain the parameter for a low dark
photon mass compared with the boson mass . We study the
search for dark photon in for a
dark photon mass as large as kinematically allowed at future
colliders. For large , care should be taken to properly treat possible
large mixing between and . We obtain sensitivities to the parameter
for a wide range of dark photon mass at planed colliders,
such as Circular Electron Positron Collider (CEPC), International Linear
Collider (ILC) and Future Circular Collider (FCC-ee). For the dark photon mass
, the
exclusion limits on the mixing parameter are . The CEPC with and FCC-ee with
are more sensitive than the constraint from current
LHCb measurement once the dark photon mass . For , the sensitivity at
the FCC-ee with and is better
than that at the 13~TeV LHC with , while the sensitivity at
the CEPC with and can be even
better than that at 13~TeV LHC with for
.Comment: 21 pages, 5 figures, 2 table
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