1,480 research outputs found
Conference Summary of QNP2018
This report is the summary of the Eighth International Conference on Quarks
and Nuclear Physics (QNP2018). Hadron and nuclear physics is the field to
investigate high-density quantum many-body systems bound by strong
interactions. It is intended to clarify matter generation of universe and
properties of quark-hadron many-body systems. The QNP is an international
conference which covers a wide range of hadron and nuclear physics, including
quark and gluon structure of hadrons, hadron spectroscopy, hadron interactions
and nuclear structure, hot and cold dense matter, and experimental facilities.
First, I introduce the current status of the hadron and nuclear physics field
related to this conference. Next, the organization of the conference is
explained, and a brief overview of major recent developments is discussed by
selecting topics from discussions at the plenary sessions. They include
rapidly-developing field of gravitational waves and nuclear physics, hadron
interactions and nuclear structure with strangeness, lattice QCD, hadron
spectroscopy, nucleon structure, heavy-ion physics, hadrons in nuclear medium,
and experimental facilities of EIC, GSI-FAIR, JLab, J-PARC, Super-KEKB, and
others. Nuclear physics is at a fortunate time to push various projects at
these facilities. However, we should note that the projects need to be
developed together with related studies in other fields such as gravitational
physics, astrophysics, condensed-matter physics, particle physics, and
fundamental quantum physics.Comment: 10 pages, LaTeX, 1 style file, 3 figure files, Proceedings of Eighth
International Conference on Quarks and Nuclear Physics (QNP2018), November
13-17, 2018, Tsukuba, Japa
Effects of radiation damage caused by proton irradiation on Multi-Pixel Photon Counters (MPPCs)
We have investigated the effects caused by proton-induced radiation damage on
Multi-Pixel Photon Counter (MPPC), a pixelized photon detector developed by
Hamamatsu Photonics. The leakage current of irradiated MPPC samples linearly
increases with total irradiated doses due to radiation damage, which is not
completely recovered even after a year from the irradiation. No significant
change has been observed in the gains at least up to 8.0 Gy (
n/mm in 1 MeV neutron equivalent fluence, ). The device has
completely lost its photon-counting capability due to baseline fluctuations and
noise pile-up after 21 Gy irradiation ( n/mm in ), which might be problematic for some applications, such as ring-imaging
Cherenkov detectors. We have found that the pulse-height resolution has been
slightly deteriorated after 42 Gy irradiation ( n/mm in
), where the measured sample has been illuminated with a few
hundred photons. This effect should be considered in the case of
energy-measurement applications.Comment: 18 pages, 10 figure
Angles from Decays with Charm
Proceedings of the CKM 2005 Workshop (WG5), UC San Diego, 15-18 March 2005.Comment: 62 pages, 55 figures. Proceedings of the CKM 2005 Workshop (WG5), UC
San Diego, 15-18 March 200
Measurement of the cross-section and forward-backward charge asymmetry for the b and c-quark in e+e- annihilation with inclusive muons at sqrt(s) = 58 GeV
We have studied inclusive muon events using all the data collected by the
TOPAZ detector at sqrt(s)=58 GeV with an integrated luminosity of 273pb-1. From
1328 inclusive muon events, we measured the ratio R_qq of the cross section for
qq-bar production to the total hadronic cross section and forward-backward
asymmetry A^q_FB for b and c quarks. The obtained results are R_bb =
0.13+-0.02(stat)+-0.01(syst), R_cc = 0.36+-0.05(stat)+-0.05(syst), A^b_FB =
-0.20+-0.16(stat)+-0.01(syst) and A^c_FB = -0.17+-0.14(stat)+-0.02(syst), in
fair agreement with a prediction of the standard model.Comment: To be published in EPJ C. 24 pages, 12 figure
A Measurement of the Cross Section in Two-Photon Processes
We have measured the inclusive production cross section in a
two-photon collision at the TRISTAN collider. The mean of
the collider was 57.16 GeV and the integrated luminosity was 150 . The
differential cross section () was obtained in the
range between 1.6 and 6.6 GeV and compared with theoretical predictions, such
as those involving direct and resolved photon processes.Comment: 8 pages, Latex format (article), figures corrected, published in
Phys. Rev. D 50 (1994) 187
Production in Two-Photon Processes at TRISTAN
We have carried out an inclusive measurement of production
in two-photon processes at TRISTAN. The mean was 58 GeV and the
integrated luminosity was 199 pb. High-statistics samples were
obtained under such conditions as no-, anti-electron, and remnant-jet tags. The
remnant-jet tag, in particular, allowed us, for the first time, to measure the
cross sections separately for the resolved-photon and direct processes.Comment: 20 pages, Latex format, 4 figures and KEK-mark included. Table 1
revised. To be published in Phys. Lett.
Measurement of inclusive electron cross section in collisions at TRISTAN
We have studied open charm production in collisions with the
TOPAZ detector at the TRISTAN collider. In this study, charm
quarks were identified by electrons (and positrons) from semi-leptonic decays
of charmed hadrons. The data corresponded to an integrated luminosity of 95.3
pb at a center-of-mass energy of 58 GeV. The results are presented as
the cross sections of inclusive electron production in
collisions with an anti-tag condition, as well as the subprocess cross
sections, which correspond to resolved-photon processes. The latter were
measured by using a sub-sample with remnant jets. A comparison with various
theoretical predictions based on direct and resolved-photon processes showed
that our data prefer that with relatively large gluon contents in a photon at
small , with the next-to-leading order correction, and with a
charm-quark mass of 1.3 GeV.Comment: 26 pages, Latex format (article), 5 figures included, to be published
in Phys. Lett.
Measurement of the forward-backward asymmetries for charm- and bottom-quark pair productions at =58GeV with electron tagging
We have measured, with electron tagging, the forward-backward asymmetries of
charm- and bottom-quark pair productions at =58.01GeV, based on
23,783 hadronic events selected from a data sample of 197pb taken with
the TOPAZ detector at TRISTAN. The measured forward-backward asymmetries are
and , which are consistent with the standard model
predictions.Comment: 19 pages, Latex format (article), 5 figures included. to be published
in Phys. Lett.
An inclusive measurement of the photon energy spectrum in b->s gamma decays
We report a fully inclusive measurement of the flavour changing neutral
current decay b->s gamma in the energy range 1.8 GeV < E* < 2.8 GeV, covering
95% of the total spectrum. Using 140 fb^-1 we obtain BF(b->s gamma)= 3.55 +/-
0.32 +0.30-0.31 +0.11-0.07, where the errors are statistical, systematic and
from theory corrections. We also measure the first and second moments of the
photon energy spectrum above 1.8 GeV and obtain = 2.292 +/- 0.026 +/- 0.034
GeV and -^2 = 0.0305 +/- 0.0074 +/- 0.0063 GeV^2, where the errors are
statistical and systematic.Comment: RevTex4, 6 pages, Submitted to Phys.Rev.Lett. Replaced: added table
of systematic errors. New results take into account radiative J/Psi decay
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