A first alignment of the LHCb Vertex Locator has been obtained from beam induced tracks at the LHC. A 450
GeV/
c protons were collided on a beam absorber during the LHC synchronisation tests of the ...anti-clockwise beam in August and September 2008. The resulting particle tracks have been reconstructed by the Vertex Locator. This was the first full reconstruction of tracks induced by the LHC beam. The quality of the data obtained is discussed. A total of 2200 tracks were reconstructed from the full data sample, and a first spatial alignment was obtained. The detector is aligned to an accuracy of
5
μ
m
in the sensor plane. The results confirm that all detector modules have not been displaced from their surveyed positions by more than
10
μ
m
.
Status of the NA62 Experiment Piccini, M.
EPJ Web of Conferences,
2020, Volume:
234
Journal Article, Conference Proceeding
Peer reviewed
Open access
The decay $ {K^ + } \to {\pi ^ + }v\bar v $, with a very precisely predicted branching ratio of less than 10
−10
in the Standard Model framework, is one of the best candidates to reveal indirect ...effects of new physics at the highest mass scales. The NA62 experiment at CERN SPS is designed to measure the branching ratio of such decay with a decay-in-flight technique, novel for this channel. The main goal of NA62 is to measure such Branching Ratio of $ {K^ + } \to {\pi ^ + }v\bar v $ with an accuracy better than 20%. This will be achieved by collecting up to 100 $ {K^ + } \to {\pi ^ + }v\bar v $ events with a background contamination at the level of 10%. The NA62 detector was commissioned in 2014 and 2015 and the experiment took physics data from 2015 to 2018. NA62 has already published the result of the 2016 data analysis. The 2017 data analysis is in progress, the single event sensitivity reached and the evaluation of the main backgrounds will be shown in this contribution.
The acoplanar photon pairs produced in the reaction
e
+
e
−
→
ν
ν
¯
γ
γ
are analysed in the 700 pb
−1 of data collected by the ALEPH detector at centre-of-mass energies between 183 and 209 GeV. No ...deviation from the Standard Model predictions is seen in any of the distributions examined. The resulting 95% C.L. limits set on the anomalous QGCs,
a
0
Z
,
a
c
Z
,
a
0
W
and
a
c
W
, are
−
0.012
<
a
0
Z
/
Λ
2
<
+
0.019
GeV
−
2
,
−
0.041
<
a
c
Z
/
Λ
2
<
+
0.044
GeV
−
2
,
−
0.060
<
a
0
W
/
Λ
2
<
+
0.055
GeV
−
2
,
−
0.099
<
a
c
W
/
Λ
2
<
+
0.093
GeV
−
2
, where
Λ is the energy scale of the new physics responsible for the anomalous couplings.
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.
CD28 is a costimulatory receptor found on the surface of most T lymphocytes. Engagement of CD28 induces interleukin 2 (IL-2) production and cell proliferation when combined with an additional signal ...such as treatment with phorbol ester, an activator of protein kinase C. Recent studies have established that after CD28 ligation, the cytoplasmic domain of CD28 can bind to the 85-kDa subunit of phosphatidylinositol 3-kinase (PI3 kinase). There is a concomitant increase in PI3 lipid kinase activity that may be important in CD28 signaling. Despite the requirement of phorbol 12-myristate 13-acetate (PMA) for effector function, we have found, however, that treatment of Jurkat T cells with the phorbol ester PMA dramatically inhibits (i) the association of PI3 kinase with CD28, (ii) the ability of p85 PI3 kinase to be immunoprecipitated by anti-phosphotyrosine antibodies, and (iii) the induction of PI3 kinase activity after stimulation of the cells with the anti-CD28 monoclonal antibody 9.3. These changes occur within minutes of PMA treatment and are persistent. In addition, we have found that wortmannin, a potent inhibitor of PI3 kinase, does not interfere with the induction of IL-2 after stimulation of Jurkat T cells with anti-CD28 monoclonal antibody and PMA. We conclude that PI3 kinase activity may not be required for CD28-dependent IL-2 production from Jurkat T cells in the presence of PMA.
The cross sections for single vector boson production in the Weν and Zee channels are measured from the data collected by the ALEPH detector at LEP for centre-of-mass energies between 183 and 209 ...GeV. These data correspond to a total integratedluminosity of 683 pb−1. Single-W production is studied in both hadronic and leptonic decay channels. Hadronic and dimuon decays are used for single-Z production. The measured cross sections agree with the Standard Model predictions.
The RICH detector of the NA62 experiment is one of the key detectors to achieve the muon rejection needed in the search for the {K^ + } \to {\pi ^ + }\nu \bar \nu decay, performed by NA62. Since ...BR({K^ + } \to {\mu ^ + }\nu ) is higher than BR({K^ + } \to {\pi ^ + }\nu \bar \nu ) by more than 9 orders of magnitude, it represents one of the most relevant background contributions. Its rejection is performed with kinematic reconstruction of the event and identification of the charged particles in the final state (pions against muons). The Ring Imaging Cherenkov detector (RICH) gives a muon rejection higher than a factor 100 in the momentum range 15-35 GeV/c, and measures the track crossing time with a resolution better than 100 ps. It is also exploited to provide trigger for charged particles. In this contribution the RICH detector will be described, together with its basic performance, the mirrors alignment procedure and its usage in {K^ + } \to {\pi ^ + }\nu \bar \nu search.
The W + W- production cross section is measured from a data sample corresponding to a total integrated luminosity of 683 pb-1, collected by the ALEPH experiment at LEP at centre-of-mass energies from ...183 to 209 GeV. Individual cross sections for the different topologies arising from W decays into leptons or hadrons, as well as the total W-pair cross section are given at eight centre-of-mass energies. The results are found to be in agreement with recently developed Standard Model calculations at the one percent level. The hadronic branching fraction of the W boson is measured to be \({\mathrm B}({\mathrm W}\rightarrow {\mathrm{q\bar{q}}})\) = 67.13 \(\pm\) 0.37(stat.) \(\pm\) 0.15(syst.)%, from which the CKM matrix element \(\vert\ensuremath{V}_{\mathrm{cs}}\vert\) is determined to be 0.958 \(\pm\) 0.017(stat.) \(\pm\) 0.008(syst.)
Search for K+→π+νν‾ at NA62 Aglieri Rinella, G.; Angelucci, B.; Antonelli, A. ...
Nuclear and particle physics proceedings,
January-March 2017, Volume:
282-284
Journal Article
Peer reviewed
Among the meson decays, K→πνν‾ are the cleanest environment, from the theoretical point of view, where to search for new physics effects. The NA62 Experiment at CERN SPS aims to measure the ...BR(K+→π+νν‾) with a 10% precision by the end of 2018. It has been commissioned with technical runs in 2014 and 2015, and some preliminary results of the detector performances and quality of data are here reported.
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