scholarly journals Experimental Review of ΛΛ¯ Production

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 144
Author(s):  
Xiaorong Zhou ◽  
Liang Yan ◽  
Rinaldo Baldini Ferroli ◽  
Guangshun Huang
Keyword(s):  
Positron Annihilation ◽  
Cross Section ◽  
Production Cross ◽  
High Energy ◽  
Threshold Region ◽  
Initial State ◽  
Precision Data ◽  
Electron Positron Annihilation ◽  
Electron Positron ◽  
State Radiation

Exclusive hyperon-antihyperon production provides a unique insight for understanding of the intrinsic dynamics when strangeness is involved. In this paper, we review the results of ΛΛ¯ production via different reactions from various experiments, e.g., via p¯p annihilation from the LEAR experiment PS185, via electron-positron annihilation using the energy scan method at the CLEO-c and BESIII experiments and the initial-state-radiation approach utilized at the BaBar experiment. The production cross section of ΛΛ¯ near the threshold is sensitive to QCD based prediction. Experimental high precision data for p¯p→Λ¯Λ close to the threshold region is obtained. The cross section of e+e−→ΛΛ¯ is measured from its production threshold to high energy. A non-zero cross section for e+e−→ΛΛ¯ near threshold is observed at BaBar and BESIII, which is in disagreement with the pQCD prediction. However, more precise data is needed to confirm this observation. Future experiments, utilizing p¯p reaction such as PANDA experiment or electron-positron annihilation such as the BESIII and BelleII experiments, are needed to extend the experimental data and to understand the ΛΛ¯ production.

Vector meson production in electron positron annihilation process

2021 ◽  
pp. 2150120
Author(s):  
Weihua Yang ◽  
Fei Huang
Keyword(s):  
Differential Cross Section ◽  
Vector Meson ◽  
Positron Annihilation ◽  
Cross Section ◽  
Differential Cross ◽  
High Energy ◽  
Annihilation Process ◽  
Electron Positron Annihilation ◽  
Electron Positron ◽  
Fragmentation Functions

When tunneling events induced by nontrivial configurations of the quantum chromodynamics gauge fields are taken into consideration, parity violating quantities emerge. Based on this consideration, parity-odd fragmentation functions can be introduced in the high energy reactions. In this paper, we calculate the differential cross-section in terms of both the parity-even and parity-odd fragmentation functions in semi-inclusive electron positron annihilation process. Semi-inclusive implies that not only a vector meson in one jet but also the back-to-back jet is measured in this reaction. According to the differential cross-section, we further calculate the azimuthal asymmetries and hadron polarizations in terms of fragmentation functions. A method of measuring the parity violating effects in the semi-inclusive annihilation process is suggested.

scholarly journals Suppression of electroweak instanton processes in high-energy collisions

2021 ◽  
pp. 2150032
Author(s):  
Valentin V. Khoze ◽  
Daniel L. Milne
Keyword(s):  
Cross Section ◽  
Production Cross ◽  
High Energy ◽  
Optical Theorem ◽  
Initial State ◽  
The Past ◽  
The Standard Model ◽  
Low Energies ◽  
High Energy Collisions ◽  
High Energy Regime

Electroweak instantons are a prediction of the Standard Model and have been studied in great detail in the past although they have not been observed. Earlier calculations of the instanton production cross-section at colliders revealed that it was exponentially suppressed at low energies, but may grow large at energies (much) above the sphaleron mass. Such calculations faced difficulty in the breakdown of the instanton perturbation theory in the high-energy regime. In this paper, we review the calculation for the electroweak instanton cross-section using the optical theorem, including quantum effects arising from interactions in the initial state and show that this leads to an exponential suppression of the cross-section at all energies, rendering the process unobservable.

scholarly journals Sensitivity of future linear $$\hbox {e}^+\hbox {e}^-$$ colliders to processes of dark matter production with light mediator exchange

2021 ◽  
Vol 81 (10) ◽  
Author(s):  
Jan Kalinowski ◽  
Wojciech Kotlarski ◽  
Krzysztof Mȩkała ◽  
Paweł Sopicki ◽  
Aleksander Filip Żarnecki
Keyword(s):  
Dark Matter ◽  
Linear Collider ◽  
Production Cross ◽  
Photon Emission ◽  
International Linear Collider ◽  
High Energy ◽  
Initial State ◽  
Final State ◽  
State Radiation ◽  
Wide Range

AbstractAs any $$e^+e^-$$ e + e - scattering process can be accompanied by a hard photon emission from the initial state radiation, the analysis of the energy spectrum and angular distributions of those photons can be used to search for hard processes with an invisible final state. Thus high energy $$e^+e^-$$ e + e - colliders offer a unique possibility for the most general search of dark matter (DM) based on the mono-photon signature. We consider production of DM particles at the International Linear Collider (ILC) and Compact Linear Collider (CLIC) experiments via a light mediator exchange. Detector effects are taken into account within the Delphes fast simulation framework. Limits on the light DM production in a simplified model are set as a function of the mediator mass and width based on the expected two-dimensional distributions of the reconstructed mono-photon events. The experimental sensitivity is extracted in terms of the DM production cross section. Limits on the mediator couplings are then presented for a wide range of mediator masses and widths. For light mediators, for masses up to the centre-of-mass energy of the collider, coupling limits derived from the mono-photon analysis are more stringent than those expected from direct resonance searches in decay channels to SM particles.

The hadronic cross section of electron-positron annihilation at 9.5 GeV and the ϒ and ϒ′ resonance parameters

1982 ◽  
Vol 116 (5) ◽  
pp. 383-386 ◽  
Author(s):  
H. Albrecht ◽  
R. Childers ◽  
C.W. Darden ◽  
G. Drews ◽  
H. Hasemann ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Cross Section ◽  
Resonance Parameters ◽  
Hadronic Cross Section ◽  
Electron Positron Annihilation ◽  
Electron Positron
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