scholarly journals New results on low energy exclusive hadronic final states from BABAR

2018 ◽  
Vol 172 ◽  
pp. 04002
Author(s):  
J. William Gary
Keyword(s):  
Standard Deviation ◽  
Cross Section ◽  
Cross Sections ◽  
Particle Physics ◽  
Low Energy ◽  
Final States ◽  
Muon Anomalous Magnetic Moment ◽  
The Standard Model ◽  
Babar Experiment ◽  
Hadronic Final States

The 3.6 standard deviation discrepancy between the standard model (SM) prediction for the muon anomalous magnetic moment gμ - 2 and the corresponding experimental measurement is one of the most persistent and intriguing potential signals in particle physics for physics beyond the SM. The largest uncertainty in the SM prediction for gμ - 2 arises from the uncertainty in the measured low energy inclusive e+e- → hadrons cross section. New results from the BABAR experiment at SLAC for the e+e- → π+ π- π0 π0 and e+e- → KK ππ cross sections are presented that significantly reduce this uncertainty. New BABAR results for other low energy exclusive hadronic processes are also discussed.

scholarly journals Measurement of the γ*γ*→ η' transition form factor and of the e+e−→ π+π−π0π0π0 and π+π−π0π0η cross sections by BABAR

2019 ◽  
Vol 206 ◽  
pp. 05004
Author(s):  
J. William Gary
Keyword(s):  
Form Factor ◽  
Cross Sections ◽  
Transition Form Factor ◽  
Branching Fractions ◽  
Low Energy ◽  
Final States ◽  
Transition Form ◽  
Intermediate Resonance ◽  
Babar Experiment ◽  
Hadronic Final States

Two recent studies from the BABAR experiment at SLAC on low-energy hadronic final states in e+e− annihilations are presented. The first study provides the first-ever measurement of the γ*γ*→ η' transition factor, where γ* denotes an off-shell photon. The second study provides the first-ever measurements of the e+e−→ π+ π−π0π0π0 and π+π−π0π0η cross sections, including studies of the intermediate resonance states and the corresponding J/ψ and ψ(2S) branching fractions.

EXPERIMENTS ON WIMPS, SIMPS, AND HOT DARK MATTER

1994 ◽  
Vol 03 (supp01) ◽  
pp. 43-52
Author(s):  
DAVID O. CALDWELL
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Cross Sections ◽  
Particle Physics ◽  
Direct Detection ◽  
Dark Matter Particle ◽  
Dirac Particles ◽  
The Standard Model ◽  
Ionization Detectors ◽  
The Universe

The particle which constitutes more than 90% of the mass of the universe is not one of those in the Standard Model of particle physics. The search for this dark matter particle has now eliminated or severely restricted many candidates. While accelerator-produced results and indirect searches have helped, the most extensive exclusions have come from attempts at direct detection using semiconductor ionization detectors. The region excluded by direct detection extends over 12 orders of magnitude in particle mass and 20 orders of magnitude in cross section for Dirac particles. The need is now to get to cross sections less than one-tenth the weak cross section for Dirac masses >20 GeV and to use detectors having nuclei with spin for Majorana masses ≳10 GeV. Light neutrinos, while not detectable directly, can be eliminated as dominant dark matter if the 17-keV neutrino exists.

scholarly journals The NUMEN Project: Toward New Experiments with High-Intensity Beams

Universe ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 72
Author(s):  
Clementina Agodi ◽  
Antonio D. Russo ◽  
Luciano Calabretta ◽  
Grazia D’Agostino ◽  
Francesco Cappuzzello ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
High Intensity ◽  
Particle Physics ◽  
Nuclear Physics ◽  
High Sensitivity ◽  
Experimental Information ◽  
Double Charge Exchange ◽  
Superconducting Cyclotron ◽  
Double Charge

The search for neutrinoless double-beta (0νββ) decay is currently a key topic in physics, due to its possible wide implications for nuclear physics, particle physics, and cosmology. The NUMEN project aims to provide experimental information on the nuclear matrix elements (NMEs) that are involved in the expression of 0νββ decay half-life by measuring the cross section of nuclear double-charge exchange (DCE) reactions. NUMEN has already demonstrated the feasibility of measuring these tiny cross sections for some nuclei of interest for the 0νββ using the superconducting cyclotron (CS) and the MAGNEX spectrometer at the Laboratori Nazionali del Sud (LNS.) Catania, Italy. However, since the DCE cross sections are very small and need to be measured with high sensitivity, the systematic exploration of all nuclei of interest requires major upgrade of the facility. R&D for technological tools has been completed. The realization of new radiation-tolerant detectors capable of sustaining high rates while preserving the requested resolution and sensitivity is underway, as well as the upgrade of the CS to deliver beams of higher intensity. Strategies to carry out DCE cross-section measurements with high-intensity beams were developed in order to achieve the challenging sensitivity requested to provide experimental constraints to 0νββ NMEs.

STOPPING CROSS SECTIONS IN CARBON FOR LOW-ENERGY ATOMS WITH

1963 ◽  
Vol 41 (9) ◽  
pp. 1424-1442 ◽  
Author(s):  
J. H. Ormrod ◽  
H. E. Duckworth
Keyword(s):  
Monte Carlo ◽  
Cross Section ◽  
Atomic Number ◽  
Cross Sections ◽  
Monte Carlo Calculation ◽  
Low Energy ◽  
Energy Interval ◽  
Nuclear Scattering

The electronic stopping cross sections in carbon for atomic projectiles with [Formula: see text] have been determined in the energy interval from 10 to 140 kev. In doing so a Monte Carlo calculation was used to subtract from each experimentally observed cross section the contribution which arises from nuclear scattering. The trend of the results thus obtained agrees well with theory. In addition, however, a periodic dependence of Sε on the atomic number of the projectile is observed.

Hadron reactions study with the CMD-3 detector in e+e− collisions

2016 ◽  
Vol 31 (33) ◽  
pp. 1630038
Author(s):  
E. P. Solodov ◽  
A. N. Amirkhanov ◽  
A. V. Anisenkov ◽  
V. M. Aulchenko ◽  
V. S. Banzarov ◽  
...  
Keyword(s):  
Energy Range ◽  
Invariant Mass ◽  
Energy Dependence ◽  
Cross Section ◽  
Cross Sections ◽  
Final States ◽  
Preliminary Results ◽  
Mass Distributions ◽  
Electron Positron ◽  
Intermediate States

The CMD-3 detector has been taking data since December 2010 at the VEPP-2000 electron–positron collider. The collected data sample corresponds to about 60 inverse picobarn of integrated luminosity in the c.m. energy range from 0.32 GeV to 2.0 GeV. Preliminary results of the analysis of various hadronic cross-sections, in particular, [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], 3[Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] are presented. The processes with multi-hadron final states have several intermediate states which have to be taken into account to correctly describe the angular and invariant mass distributions, as well as cross-section energy dependence.

scholarly journals Взаимодействие низкоэнергетических электронов с молекулами D-рибозы

2021 ◽  
Vol 129 (12) ◽  
pp. 1471
Author(s):  
И.В. Чернышова ◽  
Е.Э. Контрош ◽  
О.Б. Шпеник
Keyword(s):  
Total Cross Section ◽  
Energy Range ◽  
Cross Section ◽  
Electron Scattering ◽  
Cross Sections ◽  
Electron Attachment ◽  
Low Energy ◽  
Dissociative Electron Attachment ◽  
Low Energy Electrons ◽  
First Time

Abstract– The interactions of low-energy electrons (<20 eV) with D-ribose molecules, namely, electron scattering and dissociative attachment, are studied. The results of these studies showed that the fragmentation of D-ribose molecules occurs effectively even at an electron energy close to zero. as well as in the energy range 5.50–9.50 eV. In the total cross section of electron scattering by molecules, resonance features at energies of 5.00–9.00 eV in the region of formation of ionic fragments C3H4O2–, C2H3O2–, OH–, associated with the destruction of molecular heterocycles, were experimentally discovered for the first time. The correlation of the features observed in the scattering and dissociative electron attachment cross sections is analyzed.

scholarly journals Searches for new physics with free neutrons and radioactive atomic nuclei

2021 ◽  
Vol 52 (4) ◽  
pp. 22-25
Author(s):  
N. Severijns
Keyword(s):  
Standard Model ◽  
Particle Physics ◽  
New Physics ◽  
Low Energy ◽  
Atomic Nuclei ◽  
The Standard Model ◽  
New Particles

The Standard Model of Particle Physics is very successful but does not explain several experimental observations. Extensions of it, invoking new particles or phenomena, could overcome this. Experiments in different energy domains allow testing these extensions and searching for new particles. Here focus is on low-energy experiments with neutrons and radioactive nuclei.

scholarly journals Synthesis on Heavy Higgs from the Standard Model to 2HDM and Beyond

2020 ◽  
Vol 18 ◽  
pp. 110-142
Author(s):  
Abdeljalil Habjia
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Cross Sections ◽  
Particle Physics ◽  
Hadron Collider ◽  
Signal Strength ◽  
Beyond The Standard Model ◽  
Decay Channels ◽  
Higgs Decay ◽  
The Standard Model

In the context of particle physics, within the ATLAS and CMS experiments at large hadron collider (LHC), this work presents the discussion of the discovery of a particle compatible with the Higgs boson by the combination of several decay channels, with a mass of the order of 125.5 GeV. With increased statistics, that is the full set of data collected by the ATLAS and CMS experiments at LHC ( s1/2 = 7GeV and s1/2 = 8GeV ), the particle is also discovered individually in the channel h-->γγ with an observed significance of 5.2σ and 4.7σ, respectively. The analysis dedicated to the measurement of the mass mh and signal strength μ which is defined as the ratio of σ(pp --> h) X Br(h-->X) normalized to its Standard Model where X = WW*; ZZ*; γγ ; gg; ff. The combined results in h-->γγ channel gave the measurements: mh = 125:36 ± 0:37Gev, (μ = 1:17 ± 0:3) and the constraint on the width Γ(h) of the Higgs decay of 4.07 MeV at 95%CL. The spin study rejects the hypothesis of spin 2 at 99 %CL. The odd parity (spin parity 0- state) is excluded at more than 98%CL. Within the theoretical and experimental uncertainties accessible at the time of the analysis, all results: channels showing the excess with respect to the background-only hypothesis, measured mass and signal strength, couplings, quantum numbers (JPC), production modes, total and differential cross-sections, are compatible with the Standard Model Higgs boson at 95%CL. Although the Standard Model is one of the theories that have experienced the greatest number of successes to date, it is imperfect. The inability of this model to describe certain phenomena seems to suggest that it is only an approximation of a more general theory. Models beyond the Standard Model, such as 2HDM, MSSM or NMSSM, can compensate some of its limitations and postulate the existence of additional Higgs bosons.

scholarly journals Form Factor Measurements at BESIII for an Improved Standard Model Prediction of the Muon g-2

2018 ◽  
Vol 46 ◽  
pp. 1860026
Author(s):  
Marco Destefanis
Keyword(s):  
Form Factor ◽  
Standard Model ◽  
Model Prediction ◽  
Particle Physics ◽  
Standard Model Prediction ◽  
Final States ◽  
Direct Measurements ◽  
The Standard Model ◽  
Data Driven Approach

The anomalous part of the magnetic moment of the muon, (g-2)[Formula: see text], allows for one of the most precise tests of the Standard Model of particle physics. We report on recent results by the BESIII Collaboration of exclusive hadronic cross section channels, such as the 2[Formula: see text], 3[Formula: see text], and 4[Formula: see text] final states. These measurements are of utmost importance for an improved calculation of the hadronic vacuum polarization contribution of (g-2)[Formula: see text], which currenty is limiting the overall Standard Model prediction of this quantity. BESIII has furthermore also intiatated a programme of spacelike transition form factor measurements, which can be used for a determination of the hadronic light-by-light contribution of (g-2)[Formula: see text] in a data-driven approach. These results are of relevance in view of the new and direct measurements of (g-2)[Formula: see text] as foreseen at Fermilab/USA and J-PARC/Japan.

scholarly journals EXPERIMENTAL TESTS ON THE LIFETIME ASYMMETRY

2011 ◽  
Vol 26 (13) ◽  
pp. 987-998 ◽  
Author(s):  
ZHI-QIANG SHI ◽  
GUANG-JIONG NI
Keyword(s):  
Cross Section ◽  
Z Boson ◽  
Particle Physics ◽  
Test Problem ◽  
Precise Measurement ◽  
Experimental Tests ◽  
Moller Scattering ◽  
The Standard Model ◽  
Integrated Cross Section ◽  
Important Significance

The experimental test problem of the left–right polarization-dependent lifetime asymmetry is discussed. It shows that the existing experiments cannot demonstrate the lifetime asymmetry to be right or wrong after analyzing the measurements on the neutron, the muon and the tau lifetime, as well as the g-2 experiment. However, it is pointed out emphatically that the SLD and the E158 experiments, the measurements of the left–right integrated cross section asymmetry in Z boson production by e+e- collisions and by electron–electron Møller scattering, can indirectly demonstrate the lifetime asymmetry. In order to directly demonstrate the lifetime asymmetry, we propose some possible experiments on the decays of polarized muons. The precise measurement of the lifetime asymmetry could have important significance for building a muon collider, also in cosmology and astrophysics. It would provide a sensitive test of the standard model in particle physics and allow for exploration of the possible V+A interactions.

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