Search

In this paper, the interactions of low-energy muons (E < 10 MeV) with natural silicon, the basic material of microelectronics, are studied by Geant4 and SRIM simulation. The study is circumscribed to muons susceptible to slowdown/stop in the target and able to transfer sufficient energy to the semiconductor to create single events in silicon devices or related circuits. The capture of negative muons by silicon atoms is of particular interest, as the resulting nucleus evaporation and its effects can be catastrophic in terms of the emission of secondary ionizing particles ranging from protons to aluminum ions. We investigate in detail these different nuclear capture reactions in silicon and quantitatively evaluate their relative importance in terms of number of products, energy, linear energy transfer, and range distributions, as well as in terms of charge creation in silicon. Finally, consequences in the domain of soft errors in microelectronics are discussed. [ABSTRACT FROM AUTHOR]

Divergences that occur in density matrices of decay and scattering processes are shown to be regularized by tracing and unitarity or the optical theorem. These divergences are regularized by the lifetime of the decaying particle or the total scattering cross section. Also, these regularizations are shown to give the expected helicities of final particles. As an illustration, the density matrix is derived for the weak decay of a polarized muon at rest, µ- → νµ(e-ν¯e), with Lorentz invariant density matrix entries and unitarity upheld at tree level. The electron’s von Neumann entanglement entropy distributions are derived with respect to both the electron’s emission angle and energy. The angular entropy distribution peaks for an electron emitted backward with respect to the muon’s polarization given a minimum volume regularization larger than the cube of the muon’s Compton wavelength. The kinematic entropy distribution is maximal at half the muon’s rest mass energy. These results are similar to the electron’s angular and kinematic decay rate distributions. Both the density matrix and entanglement entropy can be cast in terms of either ratios of areas or volumes.

In this paper, we study the dominant nonuniversal contributions to muon decay for the five scalar leptoquarks (LQs) allowed by the Standard Model gauge symmetries. By using a common computational framework, we isolate the New-Physics (NP) one-loop corrections over the observable Δ r and explore the connection with the W boson mass. We highlight the role of nonuniversal terms considering, for the SU (2) doublet and triplet LQs, a completely degenerate scenario, thus cancelling/moderating the effects of the oblique parameters S, T and U. We determine simple formulas that exhibit the leading nonuniversal behavior generated by the introduction of extra Yukawa terms and confront them against a present tension in M W and the projected FCC-ee accuracy. [ABSTRACT FROM AUTHOR]

Time dilation (TD) is a principal concept in the special theory of relativity (STR). The Einstein TD formula is the relation between the proper time t 0 measured in a moving frame of reference with velocity v and the dilated time t measured by a stationary observer. In this paper, an integral approach is firstly presented to rededuce the Einstein TD formula. Then, the concept of TD is introduced and examined in view of the fractional calculus (FC) by means of the Caputo fractional derivative definition (CFD). In contrast to the explicit standard TD formula, it is found that the fractional TD (FTD) is governed by a transcendental equation in terms of the hyperbolic function and the fractional-order α. For small v compared with the speed of light c (i.e., v ≪ c ), our results tend to Newtonian mechanics, i.e., t → t 0 . For v comparable to c such as v = 0.9994 c , our numerical results are compared with the experimental ones for the TD of the muon particles μ + . Moreover, the influence of the arbitrary-order α on the FTD is analyzed. It is also declared that at a specific α , there is an agreement between the present theoretical results and the corresponding experimental ones for the muon particles μ + . [ABSTRACT FROM AUTHOR]

It is suggested that the precession of the boosted neutrino magnetic moments in the external magnetic field may explain the tension between the muon anomalous g-factor measured in the Muon g - 2 experiments and the theoretical value predicted by the Standard Model. As the neutrinos and positron resulting from the muon decay are entangled prior to the positron detection, the interaction of the neutrino dipoles with the magnetic field gives origin to an uncertainty in the time modulation of the positron angular distribution. The translated uncertainty in the muon g-factor, δ a μ ≈ (1.96 ± 0.68) ppm, presents 1 σ agreement with the anomaly measured at Fermilab, δ a μ ≈ (2.14 ± 0.50) ppm. A dependence of the anomaly on the positron energy is also predicted and can be experimentally verified. A fitting of the Brookhaven binned data suggests such a dependence, with χ r 2 = 0.86 , better than with an energy-independent anomaly, which gives χ r 2 = 0.78 . [ABSTRACT FROM AUTHOR]

Time dilation (TD) is a principal concept in the special theory of relativity (STR). The Einstein TD formula is the relation between the proper time t0 measured in a moving frame of reference with velocity v and the dilated time t measured by a stationary observer. In this paper, an integral approach is firstly presented to rededuce the Einstein TD formula. Then, the concept of TD is introduced and examined in view of the fractional calculus (FC) by means of the Caputo fractional derivative definition (CFD). In contrast to the explicit standard TD formula, it is found that the fractional TD (FTD) is governed by a transcendental equation in terms of the hyperbolic function and the fractional-order α. For small v compared with the speed of light c (i.e., v≪c), our results tend to Newtonian mechanics, i.e., t→t0. For v comparable to c such as v=0.9994c, our numerical results are compared with the experimental ones for the TD of the muon particles μ+. Moreover, the influence of the arbitrary-order α on the FTD is analyzed. It is also declared that at a specific α, there is an agreement between the present theoretical results and the corresponding experimental ones for the muon particles μ+.

The history of using machine learning algorithms to analyze statistical models is quite long. The development of computer technology has given these algorithms a new breath. Nowadays deep learning is mainstream and most popular area in machine learning. However, the authors believe that many researchers are trying to use deep learning methods beyond their applicability. This happens because of the widespread availability of software systems that implement deep learning algorithms, and the apparent simplicity of research. All this motivate the authors to compare deep learning algorithms and classical machine learning algorithms. The Large Hadron Collider experiment is chosen for this task, because the authors are familiar with this scientific field, and also because the experiment data is open source. The article compares various machine learning algorithms in relation to the problem of recognizing the decay reaction + + + at the Large Hadron Collider. The authors use open source implementations of machine learning algorithms. We compare algorithms with each other based on calculated metrics. As a result of the research, we can conclude that all the considered machine learning methods are quite comparable with each other (taking into account the selected metrics), while different methods have different areas of applicability.

The Sterile Neutrino Search at the J-PARC Spallation Neutron Source (JSNS |$^2$|⁠) experiment aims to search for sterile neutrino oscillations using a neutrino beam from muon decays at rest. The JSNS |$^2$| detector contains 17 tons of 0.1 |$\%$| gadolinium (Gd) loaded liquid scintillator (LS) as a neutrino target. Detector construction was completed in the spring of 2020. A slow control and monitoring system (SCMS) was implemented for reliable control and quick monitoring of the detector operational status and environmental conditions. It issues an alarm if any of the monitored parameters exceed a preset acceptable range. The SCMS monitors the high voltage of the photomultiplier tubes, the LS level in the detector, possible LS overflow and leakage, the temperature and air pressure in the detector, the humidity of the experimental hall, and the LS flow rate during filling and extraction. An initial 10 days of data-taking with a neutrino beam was done following a successful commissioning of the detector and SCMS in 2020 June. In this paper, we present a description of the assembly and installation of the SCMS and its performance. [ABSTRACT FROM AUTHOR]

In order to study a change in electrochemical, structural, and magnetic properties for lithium manganese oxide spinels Li[LixMn2-x]O4 (LMO) with 0 ≤ x ≤ 1/3, muon-spin rotation and relaxation (μSR) spectra were recorded under pressure (P) up to 2.1 GPa. At ambient P, P = 0.1 MPa, the antiferromagnetic or spin-glass-like transition temperature (Tm) at P = 0.1 MPa monotonically decreases with increasing x. On the contrary, the slope of the Tm vs. P (dTm/dP) rapidly increases from 0.9(1) K/GPa at x = 0 to 1.4 K/GPa at x = 0.1, then drops to 0.7(1) K/GPa at x = 0.15, and finally keeps constant (∼0.4 K/GPa) with further increasing x. Considering the structural change of LMO with x, the decrease in the distance between Mn ions (dMn-Mn) is likely to play an essential role for determining Tm under P. According to cyclic voltammetry on LMO, the peak current at both anodic and cathodic directions shows the maximum at x = 0.1, indicating the highest diffusivity of Li+ ions (DLi) at x = 0.1. [ABSTRACT FROM AUTHOR]

We have investigated $B \to (K,K^\ast)(l\bar l,\nu \bar\nu)$ decay channels and predicted some form-factor-dependent observables (e.g. branching ratio, forward–backward asymmetry, and lepton polarization asymmetry) considering a new physics contribution from the non-universal $Z^\prime$ model. We have found that there is an appreciable difference between the standard model and $Z^\prime$ model predictions. Recently, the lepton flavor non-universality parameters $R_K$ and $R_{K^\ast} $ have been measured by the LHCb Collaboration and found to be different from their standard model predictions. These deviations provide a hint of flavor non-universality in the lepton sector and motivate our research to look for new physics beyond the standard model. The $R_{K}$ and $R_{K^\ast}$ anomalies may be due to new physics in either the electron or the muon sector, or both. In our work, we have shown that the experimental results for $R_K$ and $R_{K^\ast}$ could be achieved in a non-universal $Z^\prime$ model considering the new physics couplings to the muon sector only. [ABSTRACT FROM AUTHOR]

Abstract ALICE is the experiment specifically designed to study the Quark-Gluon Plasma (QGP) in heavy-ion collisions at the CERN LHC. The ALICE detector will be upgraded during the Long Shutdown 2, planned for 2019-2020, in order to cope with the maximum interaction rate of 50 kHz of Pb-Pb collisions foreseen for Runs 3 and 4. The ambitious programme of high-precision measurements, expected for muon physics after 2020, requires an upgrade of the front-end and readout electronics of the existing Muon Spectrometer. This concerns the Cathode Pad Chambers (CPC) used for tracking and the Resistive Plate Chambers (RPC) used for triggering and for muon identification. The Muon Forward Tracker (MFT), an internal tracker added in front of the front absorber of the existing Muon Spectrometer, is also part of the ALICE detector upgrade programme. It is based on an assembly of circular planes made of Monolithic Active Pixel Sensors (MAPS), covering the pseudorapidity range 2.5 < η < 3.6. The MFT will improve present measurements and enable new ones. A selection of results from physics performance studies will be presented, together with an overview of the technical aspects of the upgrade project. [ABSTRACT FROM AUTHOR]

The Latin American Giant Observatory (LAGO) consists of a network of water Cherenkov detectors (WCDs) installed in the Latin American region at various latitudes, from Sierra Negra in Mexico, 18 ° 5 9 ′ N 97 ° 1 8 ′ W to the Antarctic Peninsula, 64 ° 1 4 ′ S 56 ° 3 8 ′ W and altitudes from Lima, Peru at 20 m a.s.l. to Chacaltaya, Bolivia at 5500 m a.s.l. The detectors of the network are built from commercial water tanks, so they have several geometries (cylindrical in general) and different water purification methods. All these features generate different profiles in the response to air shower particles measured by our detectors and produce pulse-shaped electronic signals. Common sources of noise in a WCD come from light leakage, electronic noise, and noise associated with the operation of photomultiplier tubes (PMTs) such as thermionic emission and after-pulses; they all could produce detectable pulses recorded by the LAGO data acquisition (DAQ) system. In LAGO WCDs, these noise signals are expected to present a short pulse width (of a few nanoseconds), while secondary radiation typically produces pulses of several tens of nanoseconds. We used data from the LAGO DAQ system, which digitises pulses at 40 MHz sampling rate on windows of 300 ns (12 temporal bins) and with a 10-bit resolution. The LAGO DAQ configuration uses a single threshold-based trigger in the third temporal bin. We proposed a secondary trigger threshold at the fourth bin to improve the noise rejection. In this work, we show how the optimal values for these triggers are now obtained from the measurement of the muon lifetime within the water volume and the resulting Michel spectrum. Our results were also simulated using the LAGO ARTI simulation framework to estimate the expected flux of secondary particles at the detector site; and the Meiga framework, a Geant4-based simulator used to estimate the WCDs response to the atmospheric radiation flux. [ABSTRACT FROM AUTHOR]

Tetrads are introduced in order to study the relationship between tetrad gauge states of space–time and particle interactions, specially in weak processes at low energy. Through several examples like inverse muon decay, elastic neutrino–electron scattering, it is explicitly shown how to assign to each vertex of the corresponding low-order Feynman diagram in a weak interaction, a particular set of tetrad vectors. The relationship between the tetrads associated to different vertices is exhibited explicitly to be generated by a SU(2) local tetrad gauge transformation. We are establishing a direct link between standard gauge and tetrad gauge states of space–time using the quantum field theories perturbative formulations. [ABSTRACT FROM AUTHOR]

The angular asymmetry in decays of polarized muons and tau leptons is discussed. Both the standard V – A Fermi model and the general parametrization via Michel parameters are considered. Numerical importance of contributions suppressed by charged lepton mass ratio is underlined. Contribution of the second order QED correction is estimated in the leading logarithm approximation. [ABSTRACT FROM AUTHOR]

Abstract The K − over K + multiplicity ratio is measured in deep-inelastic scattering, for the first time for kaons carrying a large fraction z of the virtual-photon energy. The data were obtained by the COMPASS collaboration using a 160 GeV muon beam and an isoscalar 6LiD target. The regime of deep-inelastic scattering is ensured by requiring Q 2 > 1 (GeV / c) 2 for the photon virtuality and W > 5 GeV / c 2 for the invariant mass of the produced hadronic system. Kaons are identified in the momentum range from 12 GeV/ c to 40 GeV/ c , thereby restricting the range in Bjorken- x to 0.01 < x < 0.40. The z -dependence of the multiplicity ratio is studied for z > 0.75. For very large values of z , i.e. z > 0.8 , we observe the kaon multiplicity ratio to fall below the lower limits expected from calculations based on leading and next-to-leading order perturbative quantum chromodynamics. Also, the kaon multiplicity ratio shows a strong dependence on the missing mass of the single-kaon production process. This suggests that within the perturbative quantum chromodynamics formalism an additional correction may be required, which takes into account the phase space available for hadronisation. [ABSTRACT FROM AUTHOR]

The J-PARC E36 experiment is searching for lepton universality violation with a stopped kaon beam by measuring the ratio of the K + decay widths Γ ( K e 2 ) ∕ Γ ( K μ 2 ) = Γ ( K + → e + ν e ) ∕ Γ ( K + → μ + ν μ ) . Since the radiative K + → e + ν e γ decays are backgrounds to be removed in this measurement, the radiated γ rays were detected in a CsI(Tl) calorimeter. The energy calibration for the 768 CsI(Tl) modules was performed using mono-chromatic μ + s from the K μ 2 decays. The delayed e + signals from the muon decays were required in order to improve the S/N ratio of the K μ 2 peak by suppressing background events. In addition, a new energy calibration method of the CsI(Tl) calorimeter using stopped cosmic muons has been established. [ABSTRACT FROM AUTHOR]

We set observational constraints on the second clock effect, predicted by Weyl unified field theory, by investigating recent data on the dilated lifetime of muons accelerated by a magnetic field. These data were obtained in an experiment carried out in CERN aiming at measuring the anomalous magnetic moment of the muon. In our analysis we employ the definition of invariant proper time proposed by V. Perlick, which seems to be the appropriate notion to be worked out in the context of Weyl space–time. [ABSTRACT FROM AUTHOR]

The muon-to-electron conversion in aluminum, titanium and gold nuclei is studied in the context of a class of mirror fermion model with non-sterile right-handed neutrinos having masses at the electroweak scale. We show that the electric and magnetic dipole operators from the photon exchange diagrams provide the dominant contributions, which enables us to derive a simple formula to relate the conversion rate with the on-shell radiative decay rate of muon into electron at the limit of zero momentum transfer and large mirror lepton masses. Current experimental limits (SINDRUM II) and projected sensitivities (Mu2e, COMET and PRISM) for the muon-to-electron conversion rates in various nuclei and latest limit from MEG for the radiative decay rate of muon into electron are used to put constraints on the parameter space of the model. Sensitivities to the new Yukawa couplings can reach the range of one tenth to one hundred-thousandth, depending on the mixing scenarios and mirror fermion masses in the model as well as the nuclei targets used in future experiments. [ABSTRACT FROM AUTHOR]

CORSIKA (COsmic Ray SImulations for Kascade) has various features in the creation of the extensive air showers with several characteristics where the users can configure the input card to achieve the desired result. ECUT is a parameter defined as the low energy cutoff of the particle kinetic energy for hadrons, muons, electrons, and photons. We investigate the effect of the different ECUT values on the detected particles in 107 - 5 × 108 GeV primary particle energy range where π-π0 decay channel chosen with 5 km shower development length. The selected ECUT values in this study are 0.05 and 0.1 GeV for both hadrons and muons and 0.05 GeV for electrons and photons. The effect of the reducing by half on the energy cutoff value is studied for the detector array located on an inclined plane, which is planned for upward τ detection. [ABSTRACT FROM AUTHOR]

The product of the electronic width of the ψ (2S) meson and the branching fraction of its decay to the muon pair was measured in the e + e − → ψ (2S) → μ + μ − process using nine data sets corresponding to an integrated luminosity of about 6.5 pb −1 collected with the KEDR detector at the VEPP-4M electron–positron collider: Γ e e × B μ μ = 19.3 ± 0.3 ± 0.5 eV . Adding the previous KEDR results on hadronic and leptonic channels, the values of the ψ (2S) electronic width were obtained under two assumptions: either with the assumption of lepton universality Γ e e = 2.279 ± 0.015 ± 0.042 keV or without it, summing up hadronic and three independent leptonic channels Γ e e = 2.282 ± 0.015 ± 0.042 keV . [ABSTRACT FROM AUTHOR]

The Dark Matter Particle Explorer (DAMPE) satellite detector announced its first result for measuring the cosmic-ray electron/positron (CRE) energy spectrum up to 4.6 TeV, including a tentative peak-like event excess at (1.3–1.5) TeV. In this work, we uncover a significant hidden excess in the DAMPE CRE spectrum over the energy range (0.6–1.1) TeV, which has a non-peak-like structure. We propose a new mechanism to explain this excess by a set of 1.5 TeV μ ± events with subsequent decays into e ± plus neutrinos. For explaining this new excess together with the peak excess around 1.4 TeV, we demonstrate that the flavor structure of the original lepton final-state produced by dark matter (DM) annihilations (or other mechanism) should have a composition ratio N e : ( N μ + 1 6 N τ ) = 1 : y , with y ≃ 2.6 – 10.8 . For lepton portal DM models, this puts nontrivial constraint on the lepton-DM-mediator couplings λ e : ( λ μ 4 + 1 6 λ τ 4 ) 1 4 = 1 : y 1 4 with a narrow range y 1 4 ≃ 1.3 – 1.8 . [ABSTRACT FROM AUTHOR]

The muon gyromagnetic anomaly aμ has been measured with a precision δaμ=aμ = 540 ppb using magic-momentum muon decays recorded up to 2001 by the E821 BNL experiment. Two projects aim at significantly improving that experimental precision: the E989 Collaboration at Fermilab plans to collect 21 times the BNL statistics and to improve by a factor four the uncertainty, the E34 Collaboration is designing a new experiment at J-PARC with a novel approach based on the production, injection and storage of ultra-cold low-energy muons. E34 aims at matching the BNL precision in a first phase, and to provide a significantly higher precision measurement in a second phase. [ABSTRACT FROM AUTHOR]

It is shown that during the stopping and decaying of positively charged muon (μ+) in a nuclear emulsion, there arises with a probability of about 10−2 electron with energies between 10 and 180 keV. The energy spectrum and angular distribution of these electrons are measured. A hypothesis on the possible mechanism behind the appearance of electrons corresponding to μ+ decay is put forth. [ABSTRACT FROM AUTHOR]

In a typical approach to extensive air shower (EAS) investigations, horizontal arrays are used and near-vertical EAS are detected. In contrast, in this work vertically arranged muon detectors are used to study inclined EAS. At large zenith angles, EAS consisting solely of muon component are employed. The transverse dimensions of EAS rapidly increase when the zenith angle increases. Hence, EAS in a wide energy interval can be explored by means of a relatively small detector. Here we present results of the analysis of the data on inclined muon bundles accumulated from 2002 to 2016 in the DECOR experiment. For the first time, these results demonstrate with more than 3σ significance the existence of the second knee in the EAS muon component spectrum near 10 17  eV primary energy. An excess of muon bundles at energies about 1 EeV found earlier in DECOR data has been confirmed and analyzed in detail. It is highly likely that the obtained outcomes indicate the appearance of new processes of muon generation. [ABSTRACT FROM AUTHOR]

The Large High Altitude Air Shower Observatory (LHAASO) will be constructed at 4400 m asl in Daocheng, Sichuan Province, with the aim of discovering sources of ultra-high energy cosmic rays and studying cosmic ray physics. The whole array includes 1171 muon detectors (MDs), constituting the largest muon detector array in the world. The special high altitude and wide-field environment requires simple and stable calibration as well as monitoring method of MDs. In this paper, the muon decay events will be selected for calibrating the charge and monitoring the water level of each MD. In the prototype muon detector, the simulation and experiment results reveal that the charge of the decay electron is approximately 0.147 times that of the vertical equivalent muon for a standard MD, and the Q V E M ∕ Q e shows a linear correlation with the water level. [ABSTRACT FROM AUTHOR]

If light new physics with lepton-flavor-violating couplings exists, the prime discovery channel might not be ℓ → ℓ ′ γ but rather ℓ → ℓ ′ X , where the new boson X could be an axion, majoron, familon or Z ′ gauge boson. The most conservative bound then comes from ℓ → ℓ ′ + inv , but if the on-shell X can decay back into leptons or photons, displaced-vertex searches could give much better limits. We show that only a narrow region in parameter space allows for displaced vertices in muon decays, μ → e X , X → γ γ , e e , whereas tauon decays can have much more interesting signatures. [ABSTRACT FROM AUTHOR]

In this article, we will introduce the need for symmetry between a possible positive hidden variable in time, +fr [E. Brodet, Phys. Essays 23, 613 (2010)], and a negative hidden variable in time, -fr, in the context of a complete deterministic explanation of the decay time process of an unstable particle such as a muon. As discussed by Brodet [Phys. Essays 23, 613 (2010)], it is possible that behind each decay time value, ti of unstable particles such as muons, STANDS a hidden variable in time, fr(i). The possible link between fr(i) and the muon's Breit-Wigner distribution and to its uncertainty in time was discussed [E. Brodet, Prog. Phys. 12, 231 (2016)], and subsequently, it was argued that each fr(i) may be related to two masses Mi(1) and Mi(2) according to the Breit-Wigner shape. The above suggestion still leaves the muon decay process not completely deterministic as particles that share the same fr(i) may have two different masses Mi(1) and Mi(2). Therefore, in order to explain the muon's decay process in a complete deterministic way, it would be possible to suggest a symmetry between +fr and -fr which share the same measured decay time, ti, and describe the muon decay time distribution using a distribution of fr(i) values with positive or negative signs. This is where +fr(i) may correspond to Mi(2) and -fr(i) may correspond to Mi(1). It will be discussed how the above symmetry may be generalized and be related to the absolute position of a particle as given in Brodet [Appl. Phys. Res. 9, 65 (2017)] and consequently to the energy and momentum of a particle and to its internal properties such as spin and charge. A possible experimental way to identify the above symmetry is discussed. [ABSTRACT FROM AUTHOR]

The NA62 experiment recorded a large sample of K + → μ + ν μ decays in 2007. A peak search has been performed in the reconstructed missing mass spectrum. In the absence of a signal, limits in the range 2 × 10 − 6 to 10 − 5 have been set on the squared mixing matrix element | U μ 4 | 2 between muon and heavy neutrino states, for heavy neutrino masses in the range 300–375 MeV/ c 2 . The result extends the range of masses for which upper limits have been set on the value of | U μ 4 | 2 in previous production search experiments. [ABSTRACT FROM AUTHOR]