scholarly journals Dark decay channel analysis (n → χ + e+ e−) with the PERKEO II experiment

2019 ◽  
Vol 219 ◽  
pp. 05007
Author(s):  
Michael Klopf ◽  
Erwin Jericha ◽  
Bastian Märkisch ◽  
Heiko Saul ◽  
Torsten Soldner ◽  
...  
Keyword(s):  
Decay Channel ◽  
Branching Fraction ◽  
Percent Level ◽  
Dark Matter Particle ◽  
Mass Range ◽  
Neutron Lifetime ◽  
Percent Contribution ◽  
Channel Analysis ◽  
The One ◽  
Dark Decay

Discrepancies from beam and bottle type experiments measuring the neutron lifetime are on the 4σ level. In recent publications Fornal and Grinstein proposed that the puzzle could be solved if the neutron would decay on the one percent level via a dark decay mode [1], one possible branch being n → χ + e+e−. With data from the Perkeo II experiment we set limits on the branching fraction and exclude a one percent contribution for 96% of the allowed mass range for the dark matter particle. With this publication, we give a detailed description of the experiment and some selected details of the analysis.

scholarly journals Search for neutron dark decay: n → χ + e+e−

2019 ◽  
Vol 219 ◽  
pp. 05008
Author(s):  
X. Sun ◽  
E. Adamek ◽  
B. Allgeier ◽  
M. Blatnik ◽  
T.J. Bowles ◽  
...  
Keyword(s):  
Decay Channel ◽  
Branching Fraction ◽  
Dark Matter Particle ◽  
Final States ◽  
Neutron Lifetime ◽  
Dark Sector ◽  
Timing Information ◽  
Different Types ◽  
Dark Decay ◽  
Particle Decays

In January, 2018, Fornal and Grinstein proposed that a previously unobserved neutron decay branch to a dark matter particle (χ) could account for the discrepancy in the neutron lifetime observed in two different types of experiments. One of the possible final states discussed includes a single χ along with an e+e− pair. We use data from the UCNA (Ultracold Neutron Asymmetry) experiment to set limits on this decay channel. Coincident electron-like events are detected with ∼ 4π acceptance using a pair of detectors that observe a volume of stored Ultracold Neutrons (UCNs). We use the timing information of coincidence events to select candidate dark sector particle decays by applying a timing calibration and selecting events within a physically-forbidden timing region for conventional n → p + e- + ν̅e decays. The summed kinetic energy (Ee+e−) from such events is reconstructed and used to set limits, as a function of the χ mass, on the branching fraction for this decay channel.

scholarly journals Dark side of the neutron?

2019 ◽  
Vol 219 ◽  
pp. 05005 ◽  
Author(s):  
Bartosz Fornal ◽  
Benjamín Grinstein
Keyword(s):  
Particle Physics ◽  
Decay Channel ◽  
Branching Fraction ◽  
Dark Side ◽  
Neutron Lifetime ◽  
Dark Sector ◽  
The Difference ◽  
Dark Decay ◽  
Theoretical Developments

We discuss our recently proposed interpretation of the discrepancy between the bottle and beam neutron lifetime experiments as a sign of a dark sector. The difference between the outcomes of the two types of measurements is explained by the existence of a neutron dark decay channel with a branching fraction 1%. Phenomenologically consistent particle physics models for the neutron dark decay can be constructed and they involve a strongly self-interacting dark sector. We elaborate on the theoretical developments around this idea and describe the efforts undertaken to verify it experimentally.

scholarly journals Search for the doubly charmed baryon $$\Xi_{cc}^+$$

2019 ◽  
Vol 63 (2) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Production Cross ◽  
Branching Fraction ◽  
Mass Range ◽  
Proton Collision ◽  
Final State ◽  
Momentum Range ◽  
Proton Proton ◽  
Charmed Baryon ◽  
Upper Limits ◽  
Lhcb Detector

AbstractA search for the doubly charmed baryon $$\Xi_{cc}^+$$Ξcc+ is performed through its decay to the $$\Lambda_c^ + {K^ -}{\pi ^ +}$$Λc+K−π+ final state, using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV. The data correspond to a total integrated luminosity of 9 fb−1. No significant signal is observed in the mass range from 3.4 to 3.8 GeV/c2. Upper limits are set at 95% credibility level on the ratio of the $$\Xi_{cc}^+$$Ξcc+ production cross-section times the branching fraction to that of $$\Lambda_c^ + $$Λc+ and $$\Xi_{cc}^{+ +}$$Ξcc++ baryons. The limits are determined as functions of the $$\Xi_{cc}^+$$Ξcc+ mass for different lifetime hypotheses, in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 4 to 15 GeV/c.

scholarly journals A possible dividing line between massive planets and brown-dwarf companions

2010 ◽  
Vol 6 (S276) ◽  
pp. 117-120 ◽  
Author(s):  
Johannes Sahlmann ◽  
Damien Ségransan ◽  
Didier Queloz ◽  
Stéphane Udry
Keyword(s):  
Radial Velocity ◽  
Formation Process ◽  
Brown Dwarfs ◽  
Mass Range ◽  
Velocity Measurements ◽  
Brown Dwarf ◽  
The One ◽  
The Individual ◽  
Dividing Line

AbstractBrown dwarfs are intermediate objects between planets and stars. The lower end of the brown-dwarf mass range overlaps with the one of massive planets and therefore the distinction between planets and brown-dwarf companions may require to trace the individual formation process. We present results on new potential brown-dwarf companions of Sun-like stars, which were discovered using CORALIE radial-velocity measurements. By combining the spectroscopic orbits and Hipparcos astrometric measurements, we have determined the orbit inclinations and therefore the companion masses for many of these systems. This has revealed a mass range between 25 and 45 Jupiter masses almost void of objects, suggesting a possible dividing line between massive planets and sub-stellar companions.

scholarly journals Probing μτ flavor-violating solutions for the muon g − 2 anomaly at Belle II

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Syuhei Iguro ◽  
Yuji Omura ◽  
Michihisa Takeuchi
Keyword(s):  
Particle Physics ◽  
Standard Model Prediction ◽  
Mass Range ◽  
Loop Correction ◽  
Lepton Flavor ◽  
Highly Sensitive ◽  
The Standard Model ◽  
Belle Ii ◽  
The One ◽  
Mass Enhancement

Abstract The discrepancy between the measured value and the Standard Model prediction of the muon anomalous magnetic moment is one of the most important issues in the particle physics. It is known that introducing a mediator boson X with the μτ lepton flavor violating (LFV) couplings is one good solution to explain the discrepancy, due to the τ mass enhancement in the one-loop correction. In this paper, we study the signal of this model, i.e. the same-sign leptons, in the Belle II experiment, assuming the flavor-diagonal couplings are suppressed. We show that the Belle II experiment is highly sensitive to the scenario in the mediator mass range of O(1–10) GeV, using the e+e−→ μ±τ∓X → μ±μ±τ∓τ∓ process induced by the X .

SIGNALS FOR LIGHT DARK MATTER AXINO

2007 ◽  
Vol 22 (25n28) ◽  
pp. 2113-2120
Author(s):  
HANG BAE KIM
Keyword(s):  
Dark Matter ◽  
Parity Violation ◽  
Particle Physics ◽  
Cold Dark Matter ◽  
Line Emission ◽  
Dark Matter Particle ◽  
Mass Range ◽  
Γ Rays ◽  
Γ Ray ◽  
The Continuum

Light dark matter aims at explaining the 511 keV γ-ray line emission from the galactic bulge as well as cold dark matter in our universe. The former is achieved via the annihilations or decays of light dark matter particles, which implies interesting observational consequences in addition to 511 keV γ-rays. We consider the axino in the 1 ~ 10 MeV mass range as the light dark matter particle and discuss the particle physics models for it, its cosmological production, and its decay arising from R-parity violation. For additional observational signals, we consider the connection to the neutrino data made by bilinear R-parity violations and the continuum γ-ray emission from light dark matter particles.

scholarly journals A factorisation-aware Matrix element emulator

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
D. Maître ◽  
H. Truong
Keyword(s):  
Neural Network ◽  
Phase Space ◽  
Matrix Element ◽  
Percent Level ◽  
Matrix Elements ◽  
Leading Order ◽  
Jet Production ◽  
The Neural Network ◽  
The Matrix ◽  
The One

Abstract In this article we present a neural network based model to emulate matrix elements. This model improves on existing methods by taking advantage of the known factorisation properties of matrix elements. In doing so we can control the behaviour of simulated matrix elements when extrapolating into more singular regions than the ones used for training the neural network. We apply our model to the case of leading-order jet production in e+e− collisions with up to five jets. Our results show that this model can reproduce the matrix elements with errors below the one-percent level on the phase-space covered during fitting and testing, and a robust extrapolation to the parts of the phase-space where the matrix elements are more singular than seen at the fitting stage.

scholarly journals Pelaksanaan Jaminan Pembiayaan Mudharabah di Bank Syariah

2019 ◽  
Vol 11 (2) ◽  
pp. 228
Author(s):  
Isnaini Isnaini
Keyword(s):  
Secondary Data ◽  
Profit Sharing ◽  
National Council ◽  
Existing Problems ◽  
Percent Contribution ◽  
The One

This study discusses the issues of securities financing of mudharabah in sharia banking. In response to this investigation, the study used qualitative normative jurisprudence methods by analyzing primary and secondary data to generate answers to existing problems. The result of this study is that the application of mudharabah financing securities in Shariah banks still apply the guarantee to mudharib. A mudharabah transaction is a form of cooperation between two or more parties in which the owner of the capital (shahibul maal) entrusts a certain amount of capital to the management (mudharib) with a profit sharing agreement. This form underscores cooperation with the one hundred percent contribution from shahibul maal and entrepreneurs from mudharib. Mudharabah is an agreement entered into between the two contracting parties. In Indonesia, the practice of using guarantees for mudharabah financing was enacted by Law No. 10 of 1998 on banking and Law No. 21 of 2008 on sharia banking and Fatwa of the Shariah Council of the National Council of Indonesian Scholars (DSN-MUI) Number: 07 / DSN-MUI / IV / 2000 which also allows for a guarantee. 

scholarly journals Recent results from BABAR

2020 ◽  
Vol 235 ◽  
pp. 04001
Author(s):  
J. William Gary
Keyword(s):  
Data Collection ◽  
Direct Measurement ◽  
Decay Channel ◽  
Branching Fraction ◽  
Branching Fractions ◽  
Babar Collaboration ◽  
Lepton Number ◽  
Lepton Flavor ◽  
The Third

The BABAR Collaboration at SLAC continues to produce a wide variety of publications on interesting and unique topics despite having ceased data-collection operations more than 10 years ago. Presented here are the results of three recent studies. The first is on the direct measurement of the B± → K± X(3872) branching fraction, allowing the first determination of the branching fractions of the exotic X(3872) charmonium state. The second is a publication on the first observation of the D0 → K−π+e+e− branching fraction. The third is on searches for lepton flavor and lepton number violating decays in D0 meson decays, resulting in improvements over existing limits by factors that vary from 20 to almost 800 depending on the D0 decay channel.

scholarly journals Neutron’s dark secret

2020 ◽  
Vol 35 (31) ◽  
pp. 2030019
Author(s):  
Bartosz Fornal ◽  
Benjamín Grinstein
Keyword(s):  
Standard Model ◽  
Particle Physics ◽  
Current Status ◽  
Neutron Lifetime ◽  
Dark Sector ◽  
Lifetime Measurements ◽  
The Standard Model ◽  
Dark Decay ◽  
Theoretical Developments

The existing discrepancy between neutron lifetime measurements in bottle and beam experiments has been interpreted as a sign of the neutron decaying to dark particles. We summarize the current status of this proposal, including a discussion of particle physics models involving such a portal between the Standard Model and a baryonic dark sector. We also review further theoretical developments around this idea and elaborate on the prospects for verifying the neutron dark decay hypothesis in current and upcoming experiments.

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