11 research outputs found
New results on the hadronic vacuum polarization to the muon g-2
Results on the lowest-order hadronic vacuum polarization contribution to the
muon magnetic anomaly are presented. They are based on the latest published
experimental data used as input to the dispersion integral. Thus recent results
on tau to nutau pi pi0 decays from Belle and on e+ e- annihilation to pi+ pi-
from BABAR and KLOE are included. The new data, together with improved
isospin-breaking corrections for tau decays, result into a much better
consistency among the different results. A discrepancy between the Standard
Model prediction and the direct g-2 measurement is found at the level of 3
sigma.Comment: proceedings of the PhiPsi09 conference, Oct. 13-16, 2009, Beijing,
Chin
Study of the process in the energy range GeV with SND
The process is studied in
the center-of-mass energy region GeV using data with an integral
luminosity of about 35 pb collected with the SND detector at the
VEPP-2000 collider. In the energy range under study, the value of the
measured Born cross section varies from 0.7 to 18 nb. The statistical
uncertainty of the cross section is %, while the systematic uncertainty
is in the range of %. The results are consistent with previous
measurements but have better accuracy.Comment: 13 pages, 11 figure
Measurement of the neutron timelike electromagnetic form factor with the SND detector
The results of the measurement of the cross section
and effective neutron timelike form factor are presented. The data taking was
carried out in 2020-2021 at the VEPP-2000 collider in the
center-of-mass energy range from 1891 to 2007 MeV. The general purpose
nonmagnetic detector SND is used to detect neutron-antineutron events. The
event selection is performed using the time-of-flight technique. The measured
cross section is 0.4-0.6 nb. The neutron form factor in the energy range under
study varies from 0.3 to 0.2.Comment: 13 pages, 8 figure
Study of the process in the energy range = 1.07 -- 2 GeV
The cross section is measured in the center-of-mass
energy range from 1.07 to 2.00 GeV in the decay channel ,
. The data set with an integrated luminosity of 242
pb accumulated in the experiment with the SND detector at the VEPP-2000
collider is analyzed.Comment: 12 pages, 3 figures
Study of the process in the energy range \sqrt{s} = \mbox{1.05-2.00} GeV with the SND detector
The process is studied in the center-of-mass
energy range 1.05-2.00 GeV using data with an integrated luminosity of 94.5
pb collected by the SND detector at the VEPP-2000 collider. The
cross section is measured for the first time. It is
shown that the dominant mechanism of this reaction is the transition through
the intermediate state. The measured cross section of the
subprocess is consistent with previous
measurements in the mode. It is found, with a
significance of 5.6, that the process is not
completely described by hadronic vector-pseudoscalar intermediate states. The
cross section of this missing contribution, which can originate from radiation
processes, e. g. , is measured. It is found to be
15-20 pb in the wide energy range from 1.3 to 1.9 GeV.Comment: 10 pages, 6 figures, to be submitted to European Physical Journal
Study of dynamics of the process in the energy range 1.15--2.00 GeV
The dynamics of the process is studied in the
energy region from 1.15 to 2.00 GeV using data accumulated with the SND
detector at the VEPP-2000 collider. The Dalitz plot distribution and
mass spectrum are analyzed in a model including the intermediate
states , , and . As a result, the
energy dependences of the and cross sections and
the relative phases between the amplitude and the and amplitudes are obtained. The cross section
has a peak in the energy region of the resonance (1.55-1.75
GeV). In this energy range the contributions of the and
states are of the same order of magnitude. No resonance
structure near 1.65 GeV is observed in the cross section. We
conclude that the intermediate state gives a significant
contribution to the decay of , whereas the
mechanism dominates in the decay
.Comment: 9 pages, 7 figures, 3 table
Observation of Collider Muon Neutrinos with the SND@LHC Experiment
We report the direct observation of muon neutrino interactions with the SND@LHC detector at the Large Hadron Collider. A dataset of proton-proton collisions at
√
s
=
13.6
TeV
collected by SND@LHC in 2022 is used, corresponding to an integrated luminosity of
36.8
fb
−
1
. The search is based on information from the active electronic components of the SND@LHC detector, which covers the pseudorapidity region of
7.2
<
η
<
8.4
, inaccessible to the other experiments at the collider. Muon neutrino candidates are identified through their charged-current interaction topology, with a track propagating through the entire length of the muon detector. After selection cuts, 8
ν
μ
interaction candidate events remain with an estimated background of 0.086 events, yielding a significance of about 7 standard deviations for the observed
ν
μ signal
Scattering and Neutrino Detector at the LHC
We propose to build and operate a detector that will, for the first time, measure the process at the LHC and search for feebly interacting particles (FIPs) in an unexplored domain. The TI18 tunnel has been identified as a suitable site to perform these measurements due to very low machine-induced background. The detector will be off-axis with respect to the ATLAS interaction point (IP1) and, given the pseudo-rapidity range accessible, the corresponding neutrinos will mostly come from charm decays: the proposed experiment will thus make the first test of the heavy flavour production in a pseudo-rapidity range that is not accessible to the current LHC detectors. In order to efficiently reconstruct neutrino interactions and identify their flavour, the detector will combine in the target region nuclear emulsion technology with scintillating fibre tracking layers and it will adopt a muon identification system based on scintillating bars that will also play the role of a hadronic calorimeter. A time of flight measurement will also be achieved thanks to a dedicated timing detector. The operation of this detector will provide an important test of neutrino reconstruction in a high occupancy environment in view of a possible experiment at HL-LHC or at the SPS Beam Dump Facility
Answers to the questions raised by the LHCC referees
The document reports all the questions raised by the LHCC referees and the corresponding answers by the Collaboration