3,973 research outputs found
Study of the process in the c.m. energy range from threshold to 2 GeV with the CMD-3 detector
Using a data sample of 6.8 pb collected with the CMD-3 detector at the
VEPP-2000 collider we select about 2700 events of the process and measure its cross section at 12 energy ponts with about
6\% systematic uncertainty. From the angular distribution of produced nucleons
we obtain the ratio
Measurement of the cross section from threshold to 1.2 GeV with the CMD-3 detector
The cross section of the process has been measured in
the center of mass energy range from 0.32 to 1.2 GeV with the CMD-3 detector at
the electron-positron collider VEPP-2000. The measurement is based on a full
dataset collected below 1 GeV during three data taking seasons, corresponding
to an integrated luminosity of about 62 pb. In the dominant
-resonance region, a systematic uncertainty of 0.7% has been reached. At
energies around -resonance the production cross section was
measured for the first time with high energy resolution. The forward-backward
charge asymmetry in the production has also been measured. It
shows the strong deviation from the theoretical prediction based on
conventional sQED framework and is in good agreement with GVDM and
dispersive-based predictions. The impact of presented results on the evaluation
of the hadronic contribution to the anomalous magnetic moment of muon is
discussed.Comment: 52 pages, 36 figures; cosmetic changes of the text, fix fig.2 , fix
comment on used selection cuts in the attached radiative correction tabl
Measurement of the pion formfactor with CMD-3 detector and its implication to the hadronic contribution to muon (g-2)
The cross section of the process has been measured in
the center of mass energy range from 0.32 to 1.2 GeV with the CMD-3 detector at
the electron-positron collider VEPP-2000. The measurement is based on an
integrated luminosity of about 88 pb out of which 62 pb
constitutes a full dataset collected by CMD-3 at center-of-mass energies below
1 GeV. In the dominant region near -resonance a systematic uncertainty of
0.7% has been reached. The impact of presented results on the evaluation of the
hadronic contribution to the anomalous magnetic moment of muon is discussed.Comment: 6 pages, 3 figure
Search for flavour-changing neutral currents in processes with one top quark and a photon using 81 fbâ1 of pp collisions at s=13TeV with the ATLAS experiment
A search for flavour-changing neutral current (FCNC) events via the coupling of a top quark, a photon, and an up or charm quark is presented using 81 fbâ1 of protonâproton collision data taken at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Events with a photon, an electron or muon, a b-tagged jet, and missing transverse momentum are selected. A neural network based on kinematic variables differentiates between events from signal and background processes. The data are consistent with the background-only hypothesis, and limits are set on the strength of the tqÎł coupling in an effective field theory. These are also interpreted as 95% CL upper limits on the cross section for FCNC tÎł production via a left-handed (right-handed) tuÎł coupling of 36 fb (78 fb) and on the branching ratio for tâÎłu of 2.8Ă10â5 (6.1Ă10â5). In addition, they are interpreted as 95% CL upper limits on the cross section for FCNC tÎł production via a left-handed (right-handed) tcÎł coupling of 40 fb (33 fb) and on the branching ratio for tâÎłc of 22Ă10â5 (18Ă10â5)
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Combination of searches for Higgs boson pairs in pp collisions at s=13TeV with the ATLAS detector
This letter presents a combination of searches for Higgs boson pair production using up to 36.1 fbâ1 of protonâproton collision data at a centre-of-mass energy s=13 TeV recorded with the ATLAS detector at the LHC. The combination is performed using six analyses searching for Higgs boson pairs decaying into the bbÂŻbbÂŻ, bbÂŻW+Wâ, bbÂŻÏ+Ïâ, W+WâW+Wâ, bb¯γγ and W+Wâγγ final states. Results are presented for non-resonant and resonant Higgs boson pair production modes. No statistically significant excess in data above the Standard Model predictions is found. The combined observed (expected) limit at 95% confidence level on the non-resonant Higgs boson pair production cross-section is 6.9 (10) times the predicted Standard Model cross-section. Limits are also set on the ratio (Îșλ) of the Higgs boson self-coupling to its Standard Model value. This ratio is constrained at 95% confidence level in observation (expectation) to â5.0<Îșλ<12.0 (â5.8<Îșλ<12.0). In addition, limits are set on the production of narrow scalar resonances and spin-2 KaluzaâKlein RandallâSundrum gravitons. Exclusion regions are also provided in the parameter space of the habemus Minimal Supersymmetric Standard Model and the Electroweak Singlet Model
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