The X-ray spectrum of OJ 287 has exhibited diverse variations with broadband spectral behavior representative of all the spectral classes of blazars. These changes have been explained either via new emission components or as the sum of the jet synchrotron and its inverse Compton part. In the current work, we focus on the systematic spectral investigation of the lowest X-ray state recorded by the Swift facility to understand X-ray spectral changes. Considering optical-to-X-ray observations jointly, we found a power-law optical–UV spectrum with a photon spectrum of 2.71 ± 0.03 extending to X-ray energies. Accounting for this contribution in X-rays, we inferred a power-law photon X-ray spectrum of 1.22 ± 0.20 that improves to 1.29 ± 0.06 when considering other observations with similar X-ray spectra. An extended optical–UV spectrum with an associated low hard X-ray spectrum is further strengthened by the natural explanation of another optical–UV state of similar flux with a very different optical–UV-to-X-ray spectrum by its synchrotron and this hard X-ray spectrum. This is the hardest reported X-ray spectrum (0.3–10 keV), consistent with the Swift-BAT X-ray spectrum. We further found that this X-ray spectrum can reproduce most of the flat X-ray spectra when combined with the corresponding optical–UV continuum during the low and intermediate flux states, strengthening the synchrotron as the primary driver of most of the X-ray spectral changes in the LBL state of the source. Compared with the sharp steepening/cutoff of the optical–UV spectrum during bright phases, the inferred extended spectrum implies a comparatively larger emission region and could be associated with large-scale jet emission. The optical–UV spectrum implies a high-energy power-law particle spectrum of ∼4.4, while X-ray implies a hard low-energy particle spectrum of 1.3–1.6 that alternatively can also result from a higher lower-energy cutoff in the particle spectrum.
The burgeoning field of multi-messenger astronomy is poised to revolutionize our understanding of the most enigmatic astrophysical phenomena in the Universe. At the same time, it has opened a new window of opportunity to probe various particle physics phenomena. This is illustrated here with a few example new physics scenarios, namely, decaying heavy dark matter, pseudo-Dirac neutrinos and light dark sector physics, for which new constraints are derived using recent multi-messenger observations.
Chiara Caprini, Anna Heffernan, Richard Brito
et al.
The LISA mission is an international collaboration between ESA, its member states, and NASA, for the detection of gravitational waves from space. It was adopted in January 2024 and is scheduled for launch in the mid-2030's. It will be a constellation of three identical spacecraft forming a near-equilateral triangle in an heliocentric orbit, transferring laser beams over $2.5 \cdot 10^6$ km long arms. Laser interferometry is used to track separations between test masses, thus measuring spacetime strain variations as a function of time. LISA Science Objectives tackle many open questions in astrophysics, fundamental physics and cosmology, including ESA's Cosmic Vision questions "What are the fundamental laws of the universe?" and "How did the universe originate and of what is it made?". In this contribution, based on the LISA Red Book, we present a summary of the LISA Science Objectives relevant for the European Strategy for Particle Physics.
The third edition of this successful textbook has been redesigned to reflect the progress of the field in the last decade, including the latest studies of the Higgs boson, quark–gluon plasma, progress in flavour and neutrino physics and the discovery of gravitational waves. It provides undergraduate students with complete coverage of the basic elements of the Standard Model of particle physics, assuming only introductory courses in nuclear physics, special relativity and quantum mechanics. Examples of fundamental experiments are highlighted before discussions of the theory, giving students an appreciation of how experiment and theory interplay in the development of physics. The author examines leptons, hadrons and quarks, before presenting the dynamics and the surprising properties of the charges of the different forces, concluding with a discussion on neutrino properties beyond the Standard Model. This title is also available as open access on Higher Education from Cambridge University Press.
Igor D. Volodin, Maria O. Riazantseva, Liudmila S. Rakhmanova
et al.
This paper is devoted to the analysis of fluctuations in the solar wind plasma and interplanetary magnetic field parameters observed by Solar Orbiter and WIND spacecraft at different scales ranging from ~10<sup>3</sup> to 10<sup>7</sup> km. We consider two long data intervals where the distances between the spacecraft are 0.1 and 0.5 AU, respectively, and they are located close to the Sun–Earth line. Transformation of the fluctuation’s properties on the way from the Sun to Earth is analyzed for different types of solar wind associated with quasi-stationary and transient solar phenomena. The time series of bulk speed are shown to undergo a slight modification, even for large spacecraft separation, while the time series of the interplanetary magnetic field magnitude and components as well as proton density may be transformed even at a relatively short distance. Though the large-scale solar wind structures propagate the distance up to 0.5 AU without significant change, local structures at smaller scales may be modified. The statistical properties of the fluctuations such as relative standard deviation or probability distribution function and its moments remain nearly unchanged at different distances between the two spacecraft and are likely to depend mostly on the type of the solar wind.
Richard H. Benavides, Yithsbey Giraldo, William A. Ponce
et al.
We study the possibility of obtaining the Standard Model (SM) of particle physics as an effective theory of a more fundamental one, whose electroweak sector includes two non-universal local $U(1)$ gauge groups, with the chiral anomaly cancellation taking place through an interplay among families. As a result of the spontaneous symmetry breaking, a massive gauge boson $Z'$ arises, which couples differently to the third family of fermions (by assumption, we restrict ourselves to the scenario in which the $Z'$ couples in the same way to the first two families). Two Higgs doublets and one scalar singlet are necessary to generate the SM fermion masses and break the gauge symmetries. We show that in our model, the flavor-changing neutral currents (FCNC) of the Higgs sector are identically zero if each right-handed SM fermion is only coupled with a single Higgs doublet. This result represents a FCNC cancellation mechanism different from the usual procedure in Two-Higgs Doublet Models~(2HDM). The non-universal nature of our solutions requires the presence of three right-handed neutrino fields, one for each family. Our model generates all elements of the Dirac mass matrix for quarks and leptons, which is quite non-trivial for non-universal models. Thus, we can fit all the masses and mixing angles with two scalar doublets. Finally, we show the distribution of solutions for the scalar boson masses in our model by scanning well-motivated intervals for the model parameters. We consider two possibilities for the scalar potential and compare these results with the Higgs-like resonant signals recently reported by the ATLAS and CMS experiments at the LHC. Finally, we also report collider, electroweak, and flavor constraints on the model parameters.
Abstract A study of the charge conjugation and parity ( $$\textit{CP}$$ CP ) properties of the interaction between the Higgs boson and $$\tau $$ τ -leptons is presented. The study is based on a measurement of $$\textit{CP}$$ CP -sensitive angular observables defined by the visible decay products of $$\tau $$ τ -leptons produced in Higgs boson decays. The analysis uses 139 fb $$^{-1}$$ - 1 of proton–proton collision data recorded at a centre-of-mass energy of $$\sqrt{s}= 13$$ s = 13 TeV with the ATLAS detector at the Large Hadron Collider. Contributions from $$\textit{CP}$$ CP -violating interactions between the Higgs boson and $$\tau $$ τ -leptons are described by a single mixing angle parameter $$\phi _{\tau }$$ ϕ τ in the generalised Yukawa interaction. Without constraining the $$H\rightarrow \tau \tau $$ H → τ τ signal strength to its expected value under the Standard Model hypothesis, the mixing angle $$\phi _{\tau }$$ ϕ τ is measured to be $$9^{\circ } \pm 16^{\circ }$$ 9 ∘ ± 16 ∘ , with an expected value of $$0^{\circ } \pm 28^{\circ }$$ 0 ∘ ± 28 ∘ at the 68% confidence level. The pure $$\textit{CP}$$ CP -odd hypothesis is disfavoured at a level of 3.4 standard deviations. The results are compatible with the predictions for the Higgs boson in the Standard Model.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
Dark matter is a popular candidate to a new source of primary-charged particles, especially positrons in cosmic rays, which are proposed to account for observable anomalies. While this hypothesis of decaying or annihilating DM is mostly applied for our Galaxy, it could possibly lead to some interesting phenomena when applied for the other ones. In this work, we look into the hypothetical asymmetry in gamma radiation from the upper and lower hemisphere of the dark matter halo of the Andromeda galaxy due to inverse Compton scattering of starlight on the DM-produced electrons and positrons. While our 2D toy model raises expectations for the possible effect, a more complex approach gives negligible effect for the dark halo case, but shows some prospects for a dark disk model.
A review of the basic Hansen’s ideal frame algorithms for accurate numerical integration of perturbed elliptic motion is carried out. The fundamental approaches rely on the use of nonsingular variables and differ in the ways in which the ellipse in the orbital plane is determined. It is well known that the accuracy of the propagation of the orbit geometry is notably increased when using time-regularization techniques to transform the independent variable. However, this is at the expense of adding a differential equation to compute the time, which gathers the Lyapunov-type instabilities that are removed from the coordinates. The asynchronism resulting from errors in the numerical integration of the time may be palliated with the use of time elements, to which end a constant and a linear nonsingular time element are presented, which are new to our knowledge.
Pedro Machado, José E. Silva, Francisco Brasil
et al.
We present a new study of Jupiter’s atmosphere dynamics using for the first time the extremely high-resolution capabilities of VLT/ESPRESSO to retrieve wind velocities in Jupiter’s troposphere, with a dedicated ground-based Doppler velocimetry method. This work is primarily a proof-of-concept for retrieving Jupiter’s winds using VLT/ESPRESSO Doppler velocities. These results are complemented by a re-analysis of Cassini’s data from its fly-by of Jupiter in December 2000, performing cloud tracking at visible wavelengths, for cross comparison with Doppler velocimetry results, along with previous cloud-tracking results. We explore the effectiveness of this refined method to measure winds in Jupiter, using high-resolution spectroscopy data obtained from ESPRESSO observations performed in July 2019, with a Doppler velocimetry method based on backscattered solar radiation in the visible range. Coupled with our ground-based results, we retrieved a latitudinal and longitudinal profile of Jupiter’s winds along select bands of the atmosphere. Comparing the results between cloud-tracking methods, based on previous reference observations, and our new Doppler velocimetry approach, we found a good agreement between them, demonstrating the effectiveness of this technique. The winds obtained in this exploratory study have a two-fold relevance: they contribute to the temporal and spatial variability study of Jupiter’s troposphere dynamics, and the results presented here also validate the use of this Doppler technique to study the dynamics of Jupiter’s atmosphere and pave the way for further exploration of a broader region of Jupiter’s disk for a more comprehensive retrieval of winds and to evaluate their spatial and temporal variability.
In this study, we analyzed the optical observations of a subluminous Type Ia supernova (SN Ia) 2017fzw, which exhibited high photospheric velocity (HV) at <i>B</i>-band maximum light. The absolute <i>B</i>-band peak magnitude was determined to be <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mi>M</mi><mrow><mi>m</mi><mi>a</mi><mi>x</mi></mrow><mi>B</mi></msubsup><mo>=</mo><mo>−</mo><mn>18.65</mn><mo>±</mo><mn>0.13</mn></mrow></semantics></math></inline-formula> mag, similar to 91bg-like SNe Ia. An estimation of the rate of decline for the <i>B</i>-band light curve was determined to be <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><msub><mi>m</mi><mn>15</mn></msub><mrow><mo>(</mo><mi>B</mi><mo>)</mo></mrow><mo>=</mo><mn>1.60</mn><mo>±</mo><mn>0.06</mn></mrow></semantics></math></inline-formula> mag. The spectra of SN 2017fzw were similar to those of 91bg-like SNe Ia, with prominent Ti <span style="font-variant: small-caps;">ii</span> and Si <span style="font-variant: small-caps;">ii</span> <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>λ</mi><mn>5972</mn></mrow></semantics></math></inline-formula> features at early phases, gradually transitioning to spectra resembling normal (mainly HV subclass) SNe Ia at later phases, with a stronger Ca <span style="font-variant: small-caps;">ii</span> NIR feature. Notably, throughout all phases of observation, SN 2017fzw displayed spectral evolution characteristics that were comparable to those of HV SNe Ia, and at peak brightness, the Si <span style="font-variant: small-caps;">ii</span> <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>λ</mi><mn>6355</mn></mrow></semantics></math></inline-formula> velocity was determined to be 13,800 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>±</mo><mo> </mo><mn>415</mn></mrow></semantics></math></inline-formula> km s<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></semantics></math></inline-formula> and a more pronounced Ca <span style="font-variant: small-caps;">ii</span> NIR feature was also detected. Based on these findings, we classify SN 2017fzw as a transitional object with properties of both normal and 91bg-like SNe Ia, providing support for the hypothesis of a continuous distribution of supernovae between these two groups.
The present study aims to investigate the thermal properties of low-quantum structures (LQS) with a described non-central potential. Additionally, the study investigates the influence of relativistic parameters such as the constituent mass (effective mass) of particles and the effect of thermal properties. The magnitude of distortion of an LQS due to a non-central potential was found to have a profound effect on the system's quantum and thermal properties, which is crucial to understanding the behavior of practical quantum systems in an LQS. This paper studies the critical concepts in the fundamental optimization of mass and thermal properties of interactions in LQS based on canonical operators. It explores and analytically calculates the radial part of the Schrödinger equation at finite temperatures with two intertwined spaces using the normal ordering method in a combination of the Coulomb potential and the distortion potential. We provide analytical expressions for the ground state energy eigenvalues to define the zeroth approximation with the quantum and thermal effect and properties. Results showed that the energy of a system decreases with an increase in temperature and strength of the distortion.
Abstract A search for a new heavy scalar particle X decaying into a Standard Model (SM) Higgs boson and a new singlet scalar particle S is presented. The search uses a proton-proton (pp) collision data sample with an integrated luminosity of 140 fb −1 recorded at a centre-of-mass energy of s $$ \sqrt{s} $$ = 13 TeV with the ATLAS detector at the Large Hadron Collider. The most sensitive mass parameter space is explored in X mass ranging from 500 to 1500 GeV, with the corresponding S mass in the range 200–500 GeV. The search selects events with two hadronically decaying τ-lepton candidates from H → τ + τ − decays and one or two light leptons (ℓ = e, μ) from S → VV (V = W, Z) decays while the remaining V boson decays hadronically or to neutrinos. A multivariate discriminant based on event kinematics is used to separate the signal from the background. No excess is observed beyond the expected SM background and 95% confidence level upper limits between 72 fb and 542 fb are derived on the cross-section σ(pp → X → SH) assuming the same SM-Higgs boson-like decay branching ratios for the S → VV decay. Upper limits on the visible cross-sections σ(pp → X → SH → WWττ) and σ(pp → X → SH → ZZττ) are also set in the ranges 3–26 fb and 6–33 fb, respectively.
Nuclear and particle physics. Atomic energy. Radioactivity
Khadije Jafarzade, Mahdi Kord Zangeneh, Francisco S. N. Lobo
An alternative theory of gravity that has attracted much attention recently is the novel four-dimensional Einstein-Gauss-Bonnet (4D EGB) gravity. The theory is rescaled by the Gauss-Bonnet (GB) coupling constant <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>α</mi><mo>→</mo><mi>α</mi><mo>/</mo><mo>(</mo><mi>D</mi><mo>−</mo><mn>4</mn><mo>)</mo></mrow></semantics></math></inline-formula> in <i>D</i> dimensions and redefined as four-dimensional gravity in the limit <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>D</mi><mo>→</mo><mn>4</mn></mrow></semantics></math></inline-formula>. Thus, in this manner, the GB term yields a non-trivial contribution to the gravitational dynamics. In fact, regularized black hole solutions and applications in the novel 4D EGB gravity have also been extensively explored. In this work, motivated by recent astrophysical observations, we present an in-depth study of the optical features of AdS black holes in the novel 4D EGB gravity coupled to exponential nonlinear electrodynamics (NED), such as the shadow geometrical shape, the energy emission rate, the deflection angle and quasinormal modes. Taking into account these dynamic quantities, we investigate the effects on the black hole solution by varying the parameters of the models. More specifically, we show that the variation of the GB and NED parameters, and of the cosmological constant, imprints specific signatures on the optical features of AdS black holes in the novel 4D EGB gravity coupled to nonlinear electrodynamics, thus leading to the possibility of directly testing these black hole models by using astrophysical observations.
Defining interdisciplinary physics today requires first a reformulation of what is physics today, which in turn calls for clarifying what makes a physicist. This assessment results from my forty year journey arguing and fighting to build sociophysics. My view on interdisciplinary physics has thus evolved jumping repeatedly to opposite directions before settling down to the following claim: today physics is what is done by physicists who handle a problem the "physicist's way". However the training of physicists should stay restricted to inert matter. Yet adding a focus on the universality of the physicist approach as a generic path to investigate a topic. Consequently, interdisciplinary physics should become a cabinet of curiosities including an incubator. The cabinet of curiosities would welcome all one shots papers related to any kind of object provided it is co-authored at least by one physicist. Otherwise the paper should uses explicitly technics from physics. In case a topic gets many papers, it would be moved to the incubator to foster the potential emergence of a new appropriate subfield of physics. A process illustrated by the subsection social physics in Frontiers in physics.
This article describes reflections on the Fifth International Conference on Women in Physics which was a conference attended by 215 female physicists and a few male physicists from 49 different countries. The article focuses on the barriers that women face in their professional advancement in physics and the extent to which the situation is different in various countries.
The purpose of this paper is to analyse the back reaction problem, between Hawking radiation and the black hole, in a simplified model for the black hole evaporation in the quantum geometrodynamics context. The idea is to transcribe the most important characteristics of the Wheeler-DeWitt equation into a Schrödinger’s type of equation. Subsequently, we consider Hawking radiation and black hole quantum states evolution under the influence of a potential that includes back reaction. Finally, entropy is estimated as a measure of the entanglement between the black hole and Hawking radiation states in this model.