Search for π0 decays to invisible particles Cortina Gil, E.; Minucci, E.; Padolski, S. ...
The journal of high energy physics,
02/2021, Letnik:
2021, Številka:
2
Journal Article
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A
bstract
The NA62 experiment at the CERN SPS reports a study of a sample of 4 × 10
9
tagged
π
0
mesons from
K
+
→
π
+
π
0
(
γ
), searching for the decay of the
π
0
to invisible particles. No signal ...is observed in excess of the expected background fluctuations. An upper limit of 4
.
4 × 10
−
9
is set on the branching ratio at 90% confidence level, improving on previous results by a factor of 60. This result can also be interpreted as a model- independent upper limit on the branching ratio for the decay
K
+
→
π
+
X
, where
X
is a particle escaping detection with mass in the range 0.110–0.155 GeV
/c
2
and rest lifetime greater than 100 ps. Model-dependent upper limits are obtained assuming
X
to be an axion-like particle with dominant fermion couplings or a dark scalar mixing with the Standard Model Higgs boson.
A
bstract
The NA62 experiment reports an investigation of the
$$ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $$
K
+
→
π
+
ν
ν
¯
mode from a sample of
K
+
decays collected in 2017 at the CERN SPS. The ...experiment has achieved a single event sensitivity of (0
.
389
±
0
.
024)
×
10
−
10
, corresponding to 2.2 events assuming the Standard Model branching ratio of (8
.
4
±
1
.
0)
×
10
−
11
. Two signal candidates are observed with an expected background of 1.5 events. Combined with the result of a similar analysis conducted by NA62 on a smaller data set recorded in 2016, the collaboration now reports an upper limit of 1
.
78
×
10
−
10
for the
$$ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $$
K
+
→
π
+
ν
ν
¯
branching ratio at 90% CL. This, together with the corresponding 68% CL measurement of (
$$ {0.48}_{-0.48}^{+0.72} $$
0.48
−
0.48
+
0.72
)
×
10
−
10
, are currently the most precise results worldwide, and are able to constrain some New Physics models that predict large enhancements still allowed by previous measurements.
Abstract
We report the results of a search for dark photon in-flight decays to
μ
+
μ
−
pairs at NA62. Dark photons could be produced by dumping protons onto a copper-iron absorber, reach the NA62 ...decay volume more than 80 m downstream of the dump and decay therein. The measurement is based on data collected in 2021 which correspond to 1.4 × 10
17
dumped protons.
Elucidating the wiring diagram of the human cell is a central goal of the postgenomic era. We combined genome engineering, confocal live-cell imaging, mass spectrometry, and data science to ...systematically map the localization and interactions of human proteins. Our approach provides a data-driven description of the molecular and spatial networks that organize the proteome. Unsupervised clustering of these networks delineates functional communities that facilitate biological discovery. We found that remarkably precise functional information can be derived from protein localization patterns, which often contain enough information to identify molecular interactions, and that RNA binding proteins form a specific subgroup defined by unique interaction and localization properties. Paired with a fully interactive website (opencell.czbiohub.org), our work constitutes a resource for the quantitative cartography of human cellular organization.
A
bstract
The results of a search for
π
0
decays to a photon and an invisible massive dark photon at the NA62 experiment at the CERN SPS are reported. From a total of 4.12 × 10
8
tagged
π
0
mesons, ...no signal is observed. Assuming a kinetic-mixing interaction, limits are set on the dark photon coupling to the ordinary photon as a function of the dark photon mass, improving on previous searches in the mass range 60–110 MeV/
c
2
. The present results are interpreted in terms of an upper limit of the branching ratio of the electro-weak decay
π
0
→
γ
ν
ν
¯
, improving the current limit by more than three orders of magnitude.
Flaviviruses constitute a public health concern because of their global burden and the lack of specific antiviral treatment. Here we investigated the antiviral activity of the alkaloid anisomycin ...against dengue (DENV) and Zika (ZIKV) viruses. At non-cytotoxic concentrations, anisomycin strongly inhibited the replication of reference strains and clinical isolates of all DENV serotypes and Asian and African strains of ZIKV in Vero cells. Anisomycin also prevented DENV and ZIKV multiplication in human cell lines. While initial steps of DENV and ZIKV replicative cycle were unaffected, a high inhibition of viral protein expression was demonstrated after treatment with anisomycin. DENV RNA synthesis was strongly reduced in anisomycin treated cultures, but the compound did not exert a direct inhibitory effect on 2′ O-methyltransferase or RNA polymerase activities of DENV NS5 protein. Furthermore, anisomycin-mediated activation of p38 signaling was not related to the antiviral action of the compound. The evaluation of anisomycin efficacy in a mouse model of ZIKV morbidity and mortality revealed that animals treated with a low dose of anisomycin exhibited a significant reduction in viremia levels and died significantly later than the control group. This protective effect was lost at higher doses, though. In conclusion, anisomycin is a potent and selective in vitro inhibitor of DENV and ZIKV that impairs a post-entry step of viral replication; and a low-dose anisomycin treatment may provide some minimal benefit in a mouse model.
•Anisomycin exerted a selective and potent antiviral activity against dengue (DENV) and Zika (ZIKV) viruses in cell cultures.•A strong inhibition of viral protein expression and RNA synthesis was demonstrated after treatment with anisomycin.•The antiviral effect of anisomycin was not mediated by inhibition of NS5 functions nor by the activation of p38 signaling.•A low dose of anisomycin exhibited a significant reduction in viremia levels in ZIKV infected AG129 mice.
The pre-merging system of galaxy clusters Abell 3391-Abell 3395 located at a mean redshift of 0.053 has been observed at 1 GHz in an ASKAP/EMU Early Science observation as well as in X-rays with ...eROSITA. The projected separation of the X-ray peaks of the two clusters is ~50′ or ~3.1 Mpc. Here we present an inventory of interesting radio sources in this field around this cluster merger. While the eROSITA observations provide clear indications of a bridge of thermal gas between the clusters, neither ASKAP nor MWA observations show any diffuse radio emission coinciding with the X-ray bridge. We derive an upper limit on the radio emissivity in the bridge region of 〈
J
〉
1 GHz
< 1.2 × 10
−44
W Hz
−1
m
−3
. A non-detection of diffuse radio emission in the X-ray bridge between these two clusters has implications for particle-acceleration mechanisms in cosmological large-scale structure. We also report extended or otherwise noteworthy radio sources in the 30 deg
2
field around Abell 3391-Abell 3395. We identified 20 Giant Radio Galaxies, plus 7 candidates, with linear projected sizes greater than 1 Mpc. The sky density of field radio galaxies with largest linear sizes of >0.7 Mpc is ≈1.7 deg
−2
, three times higher than previously reported. We find no evidence for a cosmological evolution of the population of Giant Radio Galaxies. Moreover, we find seven candidates for cluster radio relics and radio halos.
The K+→π+νν‾ decay is theoretically one of the cleanest meson decays and so a good place to look for indirect effects of new physics complementary to LHC searches. The NA62 experiment at CERN is ...designed to measure the branching ratio of this decay with 10% precision. NA62 was commissioned in October 2014, took data in pilot runs in 2014 and 2015. The NA62 experimental setup is illustrated and data quality is reported.
Cosmological simulations predict that an intergalactic magnetic field (IGMF) pervades the large scale structure (LSS) of the Universe. Measuring the IGMF is important to determine its origin (i.e. ...primordial or otherwise). Using data from the LOFAR Two Metre Sky Survey (LoTSS), we present the Faraday rotation measure (RM) and depolarisation properties of the giant radio galaxy J1235+5317, at a redshift of z = 0.34 and 3.38 Mpc in size. We find a mean RM difference between the lobes of 2.5 ± 0.1 rad m−2, in addition to small scale RM variations of ∼0.1 rad m−2 . From a catalogue of LSS filaments based on optical spectroscopic observations in the local universe, we find an excess of filaments intersecting the line of sight to only one of the lobes. Associating the entire RM difference to these LSS filaments leads to a gas density-weighted IGMF strength of ∼0.3 μG. However, direct comparison with cosmological simulations of the RM contribution from LSS filaments gives a low probability (∼5%) for an RM contribution as large as 2.5 rad m−2, for the case of IGMF strengths of 10–50 nG. It is likely that variations in the RM from the Milky Way (on 11′ scales) contribute significantly to the mean RM difference, and a denser RM grid is required to better constrain this contribution. In general, this work demonstrates the potential of the LOFAR telescope to probe the weak signature of the IGMF. Future studies, with thousands of sources with high accuracy RMs from LoTSS, will enable more stringent constraints on the nature of the IGMF.
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