scholarly journals COMET Phase-I technical design report

2020 ◽  
Vol 2020 (3) ◽  
Author(s):  
R Abramishvili ◽  
G Adamov ◽  
R R Akhmetshin ◽  
A Allin ◽  
J C Angélique ◽  
...  
Keyword(s):  
Phase I ◽  
Proton Beam ◽  
Branching Ratio ◽  
Background Level ◽  
Expected Number ◽  
Technical Design ◽  
Lepton Flavor ◽  
Upper Limit ◽  
Technical Design Report ◽  
Background Events

Abstract The Technical Design for the COMET Phase-I experiment is presented in this paper. COMET is an experiment at J-PARC, Japan, which will search for neutrinoless conversion of muons into electrons in the field of an aluminum nucleus ($\mu$–$e$ conversion, $\mu^{-}N \rightarrow e^{-}N$); a lepton flavor-violating process. The experimental sensitivity goal for this process in the Phase-I experiment is $3.1\times10^{-15}$, or 90% upper limit of a branching ratio of $7\times 10^{-15}$, which is a factor of 100 improvement over the existing limit. The expected number of background events is 0.032. To achieve the target sensitivity and background level, the 3.2 kW 8 GeV proton beam from J-PARC will be used. Two types of detectors, CyDet and StrECAL, will be used for detecting the $\mu$–$e$ conversion events, and for measuring the beam-related background events in view of the Phase-II experiment, respectively. Results from simulation on signal and background estimations are also described.

scholarly journals A SEARCH FOR LEPTON FLAVOR VIOLATION IN TAU DECAYS ATBABAR

2005 ◽  
Vol 20 (15) ◽  
pp. 3343-3345
Author(s):  
◽  
OLGA IGONKINA
Keyword(s):  
Background Level ◽  
Lepton Flavor Violation ◽  
Tau Decays ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Upper Limit ◽  
Upper Limits

We present a recent BABAR search for lepton flavor violation in tau decays. The search for τ → ℓℓℓ(ℓ = e, μ) decays is based on a data sample of 91.6 fb-1. No signal is found in any of six channels and 90% CL upper limits are set in the range of (1 - 3) × 10-7. The search for τ → μγ decay is done with a 63 fb-1data sample. The number of observed events is consistent with expected background level and a preliminary upper limit is set at 2 × 10-6at 90% CL.

scholarly journals MEG final results and progress towards MEG II

2019 ◽  
Author(s):  
Toshiyuki Iwamoto
Keyword(s):  
Branching Ratio ◽  
Muon Beam ◽  
Muon Decay ◽  
Lepton Flavor ◽  
Upper Limit ◽  
Order Of Magnitude

The MEG experiment, which is to search for lepton flavor violating muon decay, had been successfully finished in 2013. The final sensitivity of the experiment was \boldsymbol{5.3 \times 10^{-13}}5.3×10−13, and since the experiment did not find any signal, the upper limit of the branching ratio of the \boldsymbol{\mu^{+} \rightarrow \mathrm{e}^{+} \gamma}𝛍+→e+𝛄 was set to be \boldsymbol{4.2 \times 10^{-13}}4.2×10−13 at 90% CL. The MEG II experiment will improve the sensitivity by an order of magnitude with three years data taking, and the target sensitivity is \boldsymbol{6 \times 10^{-14}}6×10−14. In 2018 after the detector integration, the muon beam data taking will be planned with limited number of readout channels. In 2019, the engineering run and the physics run will be started.

scholarly journals LEPTON FLAVOR VIOLATING li→ljγγ DECAYS INDUCED BY SCALAR UNPARTICLE

2008 ◽  
Vol 23 (39) ◽  
pp. 3331-3339 ◽  
Author(s):  
E. O. ILTAN
Keyword(s):  
Branching Ratio ◽  
The Other ◽  
Radiative Decays ◽  
Lepton Flavor Violation ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Upper Limit ◽  
Upper Limits ◽  
Scaling Dimension ◽  
Photon Coupling

We study the radiative lepton flavor violating li→ljγγ decays in the case that the lepton flavor violation is induced by the scalar unparticle mediation. We restrict the scaling dimension du and the scalar unparticle–photon–photon coupling by using the experimental upper limit of the branching ratio of the decay μ→eγγ. Furthermore, we predict the BRs of the other radiative decays by using the restrictions we get. We observe that the measurements of upper limits of BRs of these decays ensure considerable information for testing the possible signals coming from unparticle physics.

scholarly journals MEG II and Mu3e status and plan

2019 ◽  
Vol 212 ◽  
pp. 01004
Author(s):  
Paolo W. Cattaneo ◽  
André Schöning
Keyword(s):  
Branching Ratio ◽  
Muon Beam ◽  
Muon Decay ◽  
Single Event ◽  
Lepton Flavor ◽  
Upper Limit ◽  
Order Of Magnitude

The MEG experiment searching for lepton flavor violating muon decay, finished data taking successfully in 2013. The final sensitivity of the experiment was 5.3 × 10−13, and since the experiment did not find any signal, the upper limit of the branching ratio of the µ → e+γ was set to be 4.2 × 10−13 at 90% C.L.. The MEG II experiment will have a target sensitivity improved by an order of magnitude down to 6 ×10−14 with three years data taking. In 2018 after the detector integration, the muon beam data taking took place with a limited number of readout channels. In 2019, the engineering run and the physics run will be started. The Mu3e experiment will search for the lepton flavor violating decay µ+→ e+e−e+ with unprecedented sensitivity. Construction of the detector is going to start in 2020 and for the first phase a single event sensitivity of 2 × 10−15 is expected.

scholarly journals Search for π0 decays to invisible particles

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
E. Cortina Gil ◽  
◽  
A. Kleimenova ◽  
E. Minucci ◽  
S. Padolski ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Confidence Level ◽  
Branching Ratio ◽  
Standard Model Higgs Boson ◽  
Scalar Mixing ◽  
Upper Limit ◽  
Upper Limits ◽  
The Standard Model ◽  
Model Independent

Abstract The NA62 experiment at the CERN SPS reports a study of a sample of 4 × 109 tagged π0 mesons from K+ → π+π0(γ), searching for the decay of the π0 to invisible particles. No signal is observed in excess of the expected background fluctuations. An upper limit of 4.4 × 10−9 is set on the branching ratio at 90% confidence level, improving on previous results by a factor of 60. This result can also be interpreted as a model- independent upper limit on the branching ratio for the decay K+ → π+X, where X is a particle escaping detection with mass in the range 0.110–0.155 GeV/c2 and rest lifetime greater than 100 ps. Model-dependent upper limits are obtained assuming X to be an axion-like particle with dominant fermion couplings or a dark scalar mixing with the Standard Model Higgs boson.

scholarly journals Follow-up of the IceCube alerts with the Baikal-GVD telescope

2021 ◽  
Vol 16 (11) ◽  
pp. C11008
Author(s):  
V.Y. Dik ◽  
V.A. Allakhverdyan ◽  
A.D. Avrorin ◽  
A.V. Avrorin ◽  
V.M. Aynutdinov ◽  
...  
Keyword(s):  
Time Windows ◽  
High Energy ◽  
Muon Neutrino ◽  
Significant Excess ◽  
Expected Number ◽  
Online Mode ◽  
High Energy Muon ◽  
Upper Limits ◽  
Background Events

Abstract The high-energy muon neutrino events of the IceCube telescope, that are triggered as neutrino alerts in one of two probability ranks of astrophysical origin, “gold” and “bronze”, have been followed up by the Baikal-GVD in a fast quasi-online mode since September 2020. Search for correlations between alerts and GVD events reconstructed in two modes, muon-track and cascades (electromagnetic or hadronic showers), for the time windows ±1 h and ±12 h does not indicate statistically significant excess of the measured events over the expected number of background events. Upper limits on the neutrino fluence will be presented for each alert.

scholarly journals Upper limit on the branching ratio for the decay τ-→Π-ηvτ

1987 ◽  
Vol 197 (4) ◽  
pp. 561-564 ◽  
Author(s):  
K.K. Gan ◽  
G.S. Abrams ◽  
D. Amidei ◽  
A.R. Baden ◽  
T. Barklow ◽  
...  
Keyword(s):  
Branching Ratio ◽  
Upper Limit
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