scholarly journals Muonium-Antimuonium Conversion

2021 ◽  
Author(s):  
Lorenz Willmann ◽  
Klaus Jungmann
Keyword(s):  
Time Evolution ◽  
Upper Bound ◽  
Theoretical Models ◽  
Lepton Number ◽  
Conversion Process ◽  
Standard Theory ◽  
Muonium Atom ◽  
Further Development ◽  
Spontaneous Conversion ◽  
Lepton Number Violating

The MACS experiment performed at PSI in the 1990s provided an yet unchallenged upper bound on the probability for a spontaneous conversion of the muonium atom, { M=}({\mu^+e^-})M=(μ+e−), into its antiatom, antimuonium {\overline{{M}} = }({\mu^-e^+})M¯=(μ−e+). It comprises the culmination of a series of measurements at various accelerator laboratories worldwide. The experimental limits on the process have provided input and steering for the further development of a variety of theoretical models beyond the standard theory, in particular for models which address lepton number violating processes and matter-antimatter oscillations. Several models beyond the standard theory could be strongly disfavored. There is interest in a new measurement and improved sensitivity could be reached by exploiting the time evolution of the conversion process, e.g., at intense pulsed muonium sources.

scholarly journals Knotting the MECO Network

Entropy ◽  
2021 ◽  
Vol 23 (2) ◽  
pp. 141
Author(s):  
Reinhard Folk
Keyword(s):  
Statistical Physics ◽  
Condensed Matter ◽  
Theoretical Models ◽  
Iron Curtain ◽  
Solid State Physics ◽  
Scientific Exchange ◽  
History Of ◽  
Traditional Fields ◽  
Historical Resources ◽  
Further Development

The Conferences of the Middle European Cooperation in Statistical Physics (MECO) were created as an attempt to establish and maintain an exchange between scientists in the fields of statistical and condensed matter physics from Western and Eastern countries, overcoming the hurdles of the Iron Curtain. Based on personal remembrance and historical resources, the genesis and further development of MECO meetings is described. The annual meetings were interrupted in 1991 by the Yugoslav War but were re-established in 1993 and continue today. Although the fall of the Iron Curtain and the European Research programs changed the situation for the meetings considerably, the ties created by MECO still are useful to help scientific exchange. The history of European (and not only) statistical physics and the history of the MECO are tightly intertwined. It started in a time where an essential breakthrough has been achieved in statistical physics describing the features near phase transitions. In addition to the merging of solid-state physics and field theory concepts, the application of numerical methods (Monte Carlo methods) added a new pillar besides exact solutions and experiments to check theoretical models. In the following, the scientific emphasis (in general) has changed from the traditional fields of the first MECO to complexity and interdisciplinary themes as well.

scholarly journals NEUTRINO COUPLING TO COSMOLOGICAL BACKGROUND: A REVIEW ON GRAVITATIONAL BARYO/LEPTOGENESIS

2013 ◽  
Vol 22 (12) ◽  
pp. 1330030 ◽  
Author(s):  
GAETANO LAMBIASE ◽  
SUBHENDRA MOHANTY ◽  
ARAGAM R. PRASANNA
Keyword(s):  
Field Theory ◽  
Gravitational Field ◽  
Thermal Equilibrium ◽  
Energy Levels ◽  
Lepton Number ◽  
Cpt Symmetry ◽  
Cosmological Background ◽  
The Universe ◽  
General Conditions ◽  
Lepton Number Violating

In this paper, we review the theories of origin of matter–antimatter asymmetry in the universe. The general conditions for achieving baryogenesis and leptogenesis in a CPT conserving field theory have been laid down by Sakharov. In this review, we discuss scenarios where a background scalar or gravitational field spontaneously breaks the CPT symmetry and splits the energy levels between particles and antiparticles. Baryon or Lepton number violating processes in proceeding at thermal equilibrium in such backgrounds gives rise to Baryon or Lepton number asymmetry.

scholarly journals Baryogenesis via lepton-number-violating scalar interactions

1994 ◽  
Vol 49 (4) ◽  
pp. 2118-2121 ◽  
Author(s):  
Patrick J. O'Donnell ◽  
Utpal Sarkar
Keyword(s):  
Lepton Number ◽  
Lepton Number Violating

scholarly journals CPviolation in lepton number violating semihadronic decays ofK,D,Ds,B,Bc

2014 ◽  
Vol 89 (9) ◽  
Author(s):  
Gorazd Cvetič ◽  
C. S. Kim ◽  
Jilberto Zamora-Saá
Keyword(s):  
Lepton Number ◽  
Lepton Number Violating

scholarly journals Flavour effects in gravitational leptogenesis

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Rome Samanta ◽  
Satyabrata Datta
Keyword(s):  
Mass Spectrum ◽  
Chemical Potential ◽  
Mass Scale ◽  
Lepton Number ◽  
Type I ◽  
Lepton Asymmetry ◽  
Seesaw Mechanism ◽  
Set Up ◽  
The Right ◽  
Lepton Number Violating

Abstract Within the Type-I seesaw mechanism, quantum effects of the right-handed (RH) neutrinos in the gravitational background lead to an asymmetric propagation of lepton and anti-leptons which induces a Ricci scalar and neutrino Dirac-Yukawa coupling dependent chemical potential and therefore a lepton asymmetry in equilibrium. At high temperature, lepton number violating scattering processes try to maintain a dynamically generated lepton asymmetry in equilibrium. However, when the temperature drops down, the interactions become weaker, and the asymmetry freezes out. The frozen out asymmetry can act as a pre-existing asymmetry prior to the standard Fukugita-Yanagida leptogenesis phase (Ti ∼ Mi, where Mi is the mass of ith RH neutrino). It is then natural to consider the viability of gravitational leptogenesis for a given RH mass spectrum which is not consistent with successful leptogenesis from decays. Primary threat to this gravity-induced lepton asymmetry to be able to successfully reproduce the observed baryon-to-photon ratio is the lepton number violating washout processes at Ti ∼ Mi. In a minimal seesaw set up with two RH neutrinos, these washout processes are strong enough to erase a pre-existing asymmetry of significant magnitude. We show that when effects of flavour on the washout processes are taken into account, the mechanism opens up the possibility of successful leptogenesis (gravitational) for a mass spectrum M2 » 109GeV » M1 with M1 ≳ 6.3 × 106 GeV. We then briefly discuss how, in general, the mechanism leaves its imprints on the low energy CP phases and absolute light neutrino mass scale.

scholarly journals Distinguishing between lepton number violating scalars at the LHC

2013 ◽  
Vol 60 ◽  
pp. 17002 ◽  
Author(s):  
Francisco del Aguila ◽  
Mikael Chala ◽  
Arcadi Santamaria ◽  
Jose Wudka
Keyword(s):  
Lepton Number ◽  
Lepton Number Violating

scholarly journals Search for lepton number violating charged current processes with neutrino beams

2013 ◽  
Vol 719 (4-5) ◽  
pp. 373-377 ◽  
Author(s):  
Shinya Kanemura ◽  
Yoshitaka Kuno ◽  
Toshihiko Ota
Keyword(s):  
Lepton Number ◽  
Charged Current ◽  
Lepton Number Violating

scholarly journals Neutrino masses in lepton number violating mSUGRA

2008 ◽  
Author(s):  
Steve C. H. Kom ◽  
Pyungwon Ko ◽  
Deog Ki Hong
Keyword(s):  
Lepton Number ◽  
Neutrino Masses ◽  
Lepton Number Violating

THERMAL LEPTOGENESIS IN SO(10) GUT

2008 ◽  
Vol 23 (17n20) ◽  
pp. 1464-1469 ◽  
Author(s):  
XIANGDONG JI
Keyword(s):  
Thermal Equilibrium ◽  
Baryon Number ◽  
Lepton Number ◽  
Grand Unification ◽  
The Universe ◽  
Lepton Number Violating

I discuss the possibility of generating the observed baryon number in the universe through the lepton-number violating processes in a class of SO(10) grand unification theories. The key ingredient is the CP violating decay of the heavy right-handed neutrinos out of thermal equilibrium.

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