The physical origin of the Blazhko effect (BL), a phenomenon of a single or multiple periodic modulation(s) of the light curve, is under debate. Efficiently identifying and characterizing the BL is essential in understanding its origins and accounting for its effect on numerous applications of RRabs in the era of large time-domain surveys. In this study, we make use of Resnet 34, a well-known convolutional neural network (CNN) architecture, to identify RRab stars with BL from phased light curves collected from OGLE. Using reliably classified RRabs from frequency analysis to train, validate, and test our model, we show that our CNN method reaches accuracies up to 94%. We then applied our CNN method to some additional RRabs located in the Magellanic Cloud (MC) and the Galactic Bulge (GB), leading to the discovery of 113 and 2496 BL candidates, respectively. The identification accuracy for the MC Sample is estimated to be 91% after cross-matching the CNN classification results with those from frequency analysis. Similarly, the light-curve parameters of these classified BL/non-BL candidates by our CNN method from the GB region resemble those observed in the literature, confirming the reliability of our CNN classifications. Our CNN method is subject to issues related to light-curve quality and sampling, but its overall reliance on light-curve quality is comparable to that of frequency analysis. Furthermore, we find that BL modulation could be primarily characterized by variations in light-curve structure.
The CMS collaboration, A. Tumasyan, W. Adam
et al.
Abstract A search for the exotic decay of the Higgs boson to a pair of light pseudoscalars, each of which subsequently decays into a pair of photons, is presented. The search uses data from proton-proton collisions at s $$ \sqrt{s} $$ = 13 TeV recorded with the CMS detector at the LHC that corresponds to an integrated luminosity of 132 fb −1. The analysis probes pseudoscalar bosons with masses in the range 15–62 GeV, coming from the Higgs boson decay, which leads to four well-isolated photons in the final state. No significant deviation from the background-only hypothesis is observed. Upper limits are set on the product of the Higgs boson production cross section and branching fraction into four photons. The observed (expected) limits range from 0.80 (1.00) fb for a pseudoscalar boson mass of 15 GeV to 0.26 (0.24) fb for a mass of 62 GeV at 95% confidence level.
Nuclear and particle physics. Atomic energy. Radioactivity
Shukhrat N. Mardonov, Bobir A. Toshmatov, Bobomurat J. Ahmedov
et al.
The concept of polaron quasiparticles was first introduced in the pioneering papers by Landau and Feynman in the 1930s and 1940s. It describes the phenomenon of an external particle producing a bound state in an embedded medium. Since then, the study of polaron quasiparticles has been an active area of research in condensed matter physics, with a wide range of applications in magnetic phenomena and lattice deformation properties. In this paper, we provide a comprehensive review of the polaron quasiparticle phenomenon, including its historical origins, theoretical developments, and current research. We also study the various applications of polaron quasiparticles in condensed matter physics, including in magnetic phenomena and lattice deformation properties. The review concludes with an outlook on future directions of research in this field. In particular, we study the motion of external embedded particles in a quasi-two-dimensional Bose–Einstein condensate confined by the quantum harmonic oscillator. We found that the dynamics of attracting particles with static Bose–Einstein condensate exhibit circular and precessional elliptic trajectories due to centripetal force. Polaron-forming embedded particles in the condensate lead to a strongly nonlinear trajectory of the polaron and dynamics of condensate depending on the initial parameters of the condensate and polaron.
We consider the Dirac quantization in the first-class formalism to investigate the hypersphere soliton model (HSM) defined on the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>S</mi><mn>3</mn></msup></semantics></math></inline-formula> hypersphere. To do this, we construct the first-class Hamiltonian possessing the Weyl ordering correction. In the HSM, we evaluate the baryon physical quantities such as the baryon masses, magnetic moments, axial coupling constant and charge radii, most predicted values of which are in good agreement with the corresponding experimental data. Moreover, shuffling the baryon and transition magnetic moments, we find the model independent sum rules. In the HSM we also evaluate the baryon intrinsic frequencies such as <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>ω</mi><mi>N</mi></msub><mo>=</mo><mn>0.87</mn><mo>×</mo><msup><mn>10</mn><mn>23</mn></msup><mspace width="3.33333pt"></mspace><msup><mrow><mi mathvariant="normal">s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>ω</mi><mo>Δ</mo></msub><mo>=</mo><mn>1.74</mn><mo>×</mo><msup><mn>10</mn><mn>23</mn></msup><mspace width="3.33333pt"></mspace><msup><mrow><mi mathvariant="normal">s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></semantics></math></inline-formula> of the nucleon and delta baryon, respectively, to yield the identity <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>ω</mi><mo>Δ</mo></msub><mo>=</mo><mn>2</mn><msub><mi>ω</mi><mi>N</mi></msub></mrow></semantics></math></inline-formula>. Next, making use of the Nambu-Goto string action and its extended rotating bosonic string theory, we formulate the stringy photon model to obtain the energy of the string configuration, which consists of the rotational and vibrational energies of the open string. Exploiting this total string energy, we evaluate the photon intrinsic frequency <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>ω</mi><mi>γ</mi></msub><mo>=</mo><mn>9.00</mn><mo>×</mo><msup><mn>10</mn><mn>23</mn></msup><mspace width="3.33333pt"></mspace><msup><mrow><mi mathvariant="normal">s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></semantics></math></inline-formula>, which is comparable to the corresponding baryon intrinsic frequencies. We also predict the photon size <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mo>⟨</mo><msup><mi>r</mi><mn>2</mn></msup><mo>⟩</mo></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msup><mrow><mo>(</mo><mi>photon</mi><mo>)</mo></mrow><mo>=</mo><mn>0.17</mn><mspace width="3.33333pt"></mspace><mi>fm</mi></mrow></semantics></math></inline-formula>, which is approximately 21% of the proton magnetic charge radius.
In 2018, in preparation for the Beam Energy Scan II, the STAR detector was upgraded with the Event Plane Detector (EPD). The instrument enhanced STAR’s capabilities in centrality determination for fluctuation measurements, event plane resolution for flow measurements, and in triggering overall. Due to its fine radial granularity, it can also be utilized to measure pseudorapidity distributions of the produced charged primary particles, in EPD’s pseudorapidity coverage of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2.15</mn><mo><</mo><mo>|</mo><mi>η</mi><mo>|</mo><mo><</mo><mn>5.09</mn></mrow></semantics></math></inline-formula>. As such a measurement cannot be done directly, the response of the detector to the primary particles has to be understood well. The detector response matrix was determined via Monte Carlo simulations, and corrected charged particle pseudorapidity distributions were obtained in Au + Au collisions at the center of mass collision energies <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msqrt><msub><mi>s</mi><msub><mrow></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></msub></msqrt></semantics></math></inline-formula> = 19.6 and 27.0 GeV using an iterative unfolding procedure. Several systematic checks of the method were also done.
The measurements of coherent elastic neutrino-nucleus scattering (CEνNS) experiments have opened up the possibility to constrain neutrino physics beyond the standard model of elementary particle physics. Furthermore, by considering neutrino-electron scattering in the keV-energy region, it is possible to set additional limits on new physics processes. Here, we present constraints that are derived from Conus germanium data on beyond the standard model (BSM) processes like tensor and vector non-standard interactions (NSIs) in the neutrino-quark sector, as well as light vector and scalar mediators. Thanks to the realized low background levels in the Conus experiment at ionization energies below 1 keV, we are able to set the world’s best limits on tensor NSIs from CEνNS and constrain the scale of corresponding new physics to lie above 360 GeV. For vector NSIs, the derived limits strongly depend on the assumed ionization quenching factor within the detector material, since small quenching factors largely suppress potential signals for both, the expected standard model CEνNS process and the vector NSIs. Furthermore, competitive limits on scalar and vector mediators are obtained from the CEνNS channel at reactor-site which allow to probe coupling constants as low as 5 ∙ 10−5 of low mediator masses, assuming the currently favored quenching factor regime. The consideration of neutrino-electron scatterings allows to set even stronger constraints for mediator masses below ∼ 1 MeV and ∼ 10 MeV for scalar and vector mediators, respectively.
In this paper, we establish a new non-dimensional global geomagnetic disturbance index <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msubsup><mi>J</mi><mi>p</mi><mi>G</mi></msubsup></semantics></math></inline-formula> by applying the spectral whitening method to the horizontal components of geomagnetic fields observed at eight ground-based stations distributed at low and middle latitudes during years 1998 to 2014. This index can describe the development of geomagnetic storms and its relationship with the Dst index has been verified, which gives a correlation coefficient (CC) of about 0.72. We also check the response of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msubsup><mi>J</mi><mi>p</mi><mi>G</mi></msubsup></semantics></math></inline-formula> to the arrival of upstream solar wind energy based on a proxy that the ring current injection term <i>Q</i>. The variation of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msubsup><mi>J</mi><mi>p</mi><mi>G</mi></msubsup></semantics></math></inline-formula> in course of geomagnetic storms is similar to the variation of <i>Q</i>, and the recorded minimum values of <i>Q</i> (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>Q</mi><mrow><mi>m</mi><mi>i</mi><mi>n</mi></mrow></msub></semantics></math></inline-formula>) and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msubsup><mi>J</mi><mi>p</mi><mi>G</mi></msubsup></semantics></math></inline-formula> (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow><msubsup><mi>J</mi><mi>p</mi><mi>G</mi></msubsup></mrow><mrow><mi>m</mi><mi>i</mi><mi>n</mi></mrow></msub></semantics></math></inline-formula>) for 30 great storms yields a relatively better CC of about 0.82. These results illustrate that <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msubsup><mi>J</mi><mi>p</mi><mi>G</mi></msubsup></semantics></math></inline-formula> can effectively depict the storm evolution and is well related to the associated <i>Q</i> in amplitude, which provides an alternative means of geomagnetic storm forecasting. In addition, we note that the time difference between <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>Q</mi><mrow><mi>m</mi><mi>i</mi><mi>n</mi></mrow></msub></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow><msubsup><mi>J</mi><mi>p</mi><mi>G</mi></msubsup></mrow><mrow><mi>m</mi><mi>i</mi><mi>n</mi></mrow></msub></semantics></math></inline-formula>, as well as the time difference when <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msubsup><mi>J</mi><mi>p</mi><mi>G</mi></msubsup></semantics></math></inline-formula> recovers from <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow><msubsup><mi>J</mi><mi>p</mi><mi>G</mi></msubsup></mrow><mrow><mi>m</mi><mi>i</mi><mi>n</mi></mrow></msub></semantics></math></inline-formula> to half and/or one-third of its value, are shorter than those of the corresponding Dst index. And especially, for multiple storms that occurred continuously on a short time scale, the recovery of the Dst index to a quiet period level can be affected by the following solar wind energy input, while the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msubsup><mi>J</mi><mi>p</mi><mi>G</mi></msubsup></semantics></math></inline-formula> index does not and exhibits independently.
Overlap fermion on the lattice has been shown to properly reproduce topological aspects of gauge fields. In this paper, we review the derivation of Overlap fermion formalism in a torus of three space-time dimensions. Using the formalism, we show how to use the Overlap fermion determinants in the massless and infinite mass limits to construct different continuum topological gauge actions, such as the level-<i>k</i> Chern–Simons action, “half-CS” term and the mixed Chern–Simons (BF) coupling, in a gauge-invariant lattice UV regulated manner. Taking special Abelian and non-Abelian background fields, we demonstrate numerically how the lattice formalism beautifully reproduces the continuum expectations, such as the flow of action under large gauge transformations.
Spherically symmetric solution in 4D Einstein–Gauss–Bonnet gravity coupled to modified logarithmic nonlinear electrodynamics (ModLogNED) is found. This solution at infinity possesses the charged black hole Reissner–Nordström behavior. We study the black hole thermodynamics, entropy, shadow, energy emission rate and quasinormal modes. It was shown that black holes can possess the phase transitions and at some range of event horizon radii black holes are stable. The entropy has the logarithmic correction to the area law. The shadow radii were calculated for variety of parameters. We found that there is a peak of the black hole energy emission rate. The real and imaginary parts of the quasinormal modes frequencies were calculated. The energy conditions of ModLogNED are investigated.
We justify and extend the standard model of elementary particle physics by generalizing the theory of relativity and quantum mechanics. The usual assumption that space and time are continuous implies, indeed, that it should be possible to measure arbitrarily small intervals of space and time, but we ignore if that is true or not. It is thus more realistic to consider an extremely small “quantum of length” of yet unknown value a. It is only required to be a universal constant for all inertial frames, like c and h. This yields a logically consistent theory and accounts for elementary particles by means of four new quantum numbers. They define “particle states” in terms of modulations of wave functions at the smallest possible scale in space-time. The resulting classification of elementary particles accounts also for dark matter. Antiparticles are redefined, without needing negative energy states and recently observed “anomalies” can be explained.
The CMS collaboration, A. M. Sirunyan, A. Tumasyan
et al.
Abstract Measurements of the total and differential fiducial cross sections for the Z boson decaying into two neutrinos are presented at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV. The data were collected by the CMS detector in 2016 and correspond to an integrated luminosity of 35.9 fb −1. In these measurements, events are selected containing an imbalance in transverse momentum and one or more energetic jets. The fiducial differential cross section is measured as a function of the Z boson transverse momentum. The results are combined with a previous measurement of charged-lepton decays of the Z boson. The measured total fiducial cross section for events with Z boson transverse momentum greater than 200 GeV is 3000 − 170 + 180 $$ {3000}_{-170}^{+180} $$ fb.
Nuclear and particle physics. Atomic energy. Radioactivity
The search for special and rare celestial objects has always played an important role in astronomy. Cataclysmic Variables (CVs) are special and rare binary systems with accretion disks. Most CVs are in the quiescent period, and their spectra have the emission lines of Balmer series, HeI, and HeII. A few CVs in the outburst period have the absorption lines of Balmer series. Owing to the scarcity of numbers, expanding the spectral data of CVs is of positive significance for studying the formation of accretion disks and the evolution of binary star system models. At present, the research for astronomical spectra has entered the era of Big Data. The Large Sky Area Multi-Object Fiber Spectroscopy Telescope (LAMOST) has produced more than tens of millions of spectral data. the latest released LAMOST-DR7 includes 10.6 million low-resolution spectral data in 4926 sky regions, providing ideal data support for searching CV candidates. To process and analyze the massive amounts of spectral data, this study employed the Light Gradient Boosting Machine (LightGBM) algorithm, which is based on the ensemble tree model to automatically conduct the search in LAMOST-DR7. Finally, 225 CV candidates were found and four new CV candidates were verified by SIMBAD and published catalogs. This study also built the Gradient Boosting Decision Tree (GBDT), Adaptive Boosting (AdaBoost), and eXtreme Gradient Boosting (XGBoost) models and used Accuracy, Precision, Recall, the F1-score, and the ROC curve to compare the four models comprehensively. Experimental results showed that LightGBM is more efficient. The search for CVs based on LightGBM not only enriches the existing CV spectral library, but also provides a reference for the data mining of other rare celestial objects in massive spectral data.
Alessio Pignalberi, Igino Coco, Fabio Giannattasio
et al.
The electron temperature (<i>T</i>e) behavior at small scales (both spatial and temporal) in the topside ionosphere is investigated through in situ observations collected by Langmuir Probes on-board the European Space Agency Swarm satellites from the beginning of 2014 to the end of 2020. <i>T</i>e observations are employed to calculate the Rate Of change of electron TEmperature Index (ROTEI), which represents the standard deviation of the <i>T</i>e time derivative calculated over a window of fixed width. As a consequence, ROTEI provides a description of the small-scale variations of <i>T</i>e along the Swarm satellites orbit. The extension of the dataset and the orbital configuration of the Swarm satellites allowed us to perform a statistical analysis of ROTEI to unveil its mean spatial, diurnal, seasonal, and solar activity variations. The main ROTEI statistical trends are presented and discussed in the light of the current knowledge of the phenomena affecting the distribution and dynamics of the ionospheric plasma, which play a key role in triggering <i>T</i>e small-scale variations. The appearance of unexpected high values of ROTEI at mid and low latitudes for specific magnetic local time sectors is revealed and discussed in association with the presence of <i>T</i>e spikes recorded by Swarm satellites under very specific conditions.
Abstract The standard model (SM) production of four top quarks ($$\text {t} {}{\overline{\text {t}}} \text {t} {}{\overline{\text {t}}} $$ tt¯tt¯ ) in proton–proton collisions is studied by the CMS Collaboration. The data sample, collected during the 2016–2018 data taking of the LHC, corresponds to an integrated luminosity of 137$$\,\text {fb}^{-1}$$ fb-1 at a center-of-mass energy of 13$$\,\text {TeV}$$ TeV . The events are required to contain two same-sign charged leptons (electrons or muons) or at least three leptons, and jets. The observed and expected significances for the $$\text {t} {}{\overline{\text {t}}} \text {t} {}{\overline{\text {t}}} $$ tt¯tt¯ signal are respectively 2.6 and 2.7 standard deviations, and the $$\text {t} {}{\overline{\text {t}}} \text {t} {}{\overline{\text {t}}} $$ tt¯tt¯ cross section is measured to be $$12.6^{+5.8}_{-5.2}\,\text {fb} $$ 12.6-5.2+5.8fb . The results are used to constrain the Yukawa coupling of the top quark to the Higgs boson, $$y_{\text {t}}$$ yt , yielding a limit of $$|y_{\text {t}}/y_{\text {t}}^{\mathrm {SM}} | < 1.7$$ |yt/ytSM|<1.7 at $$95\%$$ 95% confidence level, where $$y_{\text {t}}^{\mathrm {SM}}$$ ytSM is the SM value of $$y_{\text {t}}$$ yt . They are also used to constrain the oblique parameter of the Higgs boson in an effective field theory framework, $$\hat{H}<0.12$$ H^<0.12 . Limits are set on the production of a heavy scalar or pseudoscalar boson in Type-II two-Higgs-doublet and simplified dark matter models, with exclusion limits reaching 350–470$$\,\text {GeV}$$ GeV and 350–550$$\,\text {GeV}$$ GeV for scalar and pseudoscalar bosons, respectively. Upper bounds are also set on couplings of the top quark to new light particles.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
The CMS collaboration, A. M. Sirunyan, A. Tumasyan
et al.
Abstract A measurement is presented of the cross section for electroweak production of a Z boson and a photon in association with two jets (Zγjj) in proton-proton collisions. The Z boson candidates are selected through their decay into a pair of electrons or muons. The process of interest, electroweak Zγjj production, is isolated by selecting events with a large dijet mass and a large pseudorapidity gap between the two jets. The measurement is based on data collected at the CMS experiment at s $$ \sqrt{s} $$ = 13 TeV, corresponding to an integrated luminosity of 35.9 fb −1. The observed significance of the signal is 3.9 standard deviations, where a significance of 5.2 standard deviations is expected in the standard model. These results are combined with published results by CMS at s $$ \sqrt{s} $$ = 8 TeV, which leads to observed and expected respective significances of 4.7 and 5.5 standard deviations. From the 13 TeV data, a value is obtained for the signal strength of electroweak Zγjj production and bounds are given on quartic vector boson interactions in the framework of dimension-eight effective field theory operators.
Nuclear and particle physics. Atomic energy. Radioactivity
We discuss whether it is possible to construct a stable, static, spherically symmetric Lorentzian wormhole in beyond Horndeski theory. The deep analogy between the cosmological bounce and wormhole scenarios is described in detail. We show explicitly that going beyond Horndeski enables one to evade the no-go theorem formulated for the wormholes in the general Horndeski case.