The precision and predictive power of perturbative QCD (pQCD) prediction depends on both a precise, convergent, fixed-order series and a reliable way of estimating the contributions of unknown ...higher-order (UHO) terms. It has been shown that by applying the principle of maximum conformality (PMC), which applies the renormalization group equation recursively to set the effective magnitude of αsub.s of the process, the remaining conformal coefficients will be well matched with the corresponding αsub.s at each order, leading to a scheme-and-scale invariant and more convergent perturbative series. The PMC series, being satisfied with the standard renormalization group invariance, has a rigorous foundation. Thus it not only can be widely applied to virtually all high-energy hadronic processes, but also can be a reliable platform for estimating UHO contributions. In this paper, by using the total decay width Γ(H→γγ) which has been calculated up to Nsup.4LO QCD corrections, we first derive its PMC series by using the PMC single-scale setting approach and then estimate its unknown Nsup.5LO contributions by using a Bayesian analysis. The newly suggested Bayesian-based approach estimates the magnitude of the UHO contributions based on an optimized analysis of the probability density distribution, and the predicted UHO contribution becomes more accurate when more loop terms have been known to tame the probability density function. Using the top-quark pole mass Msub.t = 172.69 GeV and the Higgs mass Msub.H = 125.25 GeV as inputs, we obtain Γ(H→γγ)=9.56504 keV, and the estimated Nsup.5LO contribution to the total decay width is ΔΓsub.H=±1.65×10sup.−4 keV for the smallest credible interval of 95.5% degree of belief.
EN MEMORIA DE PETER HIGGS Bietenholz, Wolfgang; García-Hernandez, José Antonio
Revista cubana de física,
07/2024, Letnik:
41, Številka:
1
Journal Article
Recenzirano
Peter Higgs fue un físico teórico británico, famoso por su trabajo de 1964 donde propuso un mecanismo que puede generar masas para partículas elementales, conforme a la simetría de norma. Medio siglo ...después, dos experimentos del CERN confirmaron que este mecanismo esta realizado en la naturaleza. El 8 de abril nos llegó la triste noticia del fallecimiento del gran pionero de la física de partículas elementales. Este artículo es dedicado a su memoria, al mecanismo y a la partícula que llevan su nombre.
This book brings together the most important topics in experimental particle physics in the late twentieth century to give a brief but balanced overview of the subject. The author begins by reviewing ...particle physics and discussing electromagnetic and nuclear interactions. He then goes on to discuss three nearly universal aspects of particle physics experiments: beams, targets, and fast electronics. The second part of the book treats in detail the properties of various types of particle detector, such as scintillation counters, Cerenkov counters, proportional chambers, drift chambers, sampling calorimeters, and specialized detectors. Wherever possible the author attempts to enumerate the advantages and disadvantages of performance. Finally, he discusses aspects of specific experiments, such as properties of triggers, types of measurement, spectrometers, and the integration of detectors into coherent systems. First published in 1986, this title has been reissued as an Open Access publication.
A full amplitude analysis of Λ0b→J/ψpπ− decays is performed with a data sample acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3 fb−1. A ...significantly better description of the data is achieved when, in addition to the previously observed nucleon excitations N→pπ−, either the Pc(4380)+ and Pc(4450)+→J/ψp states, previously observed in Λ0b→J/ψpK− decays, or the Zc(4200)−→J/ψπ− state, previously reported in B0→J/ψK+π− decays, or all three, are included in the amplitude models. The data support a model containing all three exotic states, with a significance of more than three standard deviations. Within uncertainties, the data are consistent with the Pc(4380)+ and Pc(4450)+ production rates expected from their previous observation taking account of Cabibbo suppression.
The data sample of Λ0b→J/ψpK− decays acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3 fb−1, is inspected for the presence of J/ψp or ...J/ψK− contributions with minimal assumptions about K−p contributions. It is demonstrated at more than nine standard deviations that Λ0b→J/ψpK− decays cannot be described with K−p contributions alone, and that J/ψp contributions play a dominant role in this incompatibility. These model-independent results support the previously obtained model-dependent evidence for P+c→J/ψp charmonium-pentaquark states in the same data sample.
Tests for deviation from the Standard Model (SM) are guided by its apparent incompleteness and by pursuit of creation of a more general theory of elementary particles. We search in this study for ...manifestations of new physics in an indirect way, through changes in interactions of already known particles due to the effects of physics beyond the SM. The non-SM interactions are referred to as anomalous (or anomalous couplings). Electroweak Zgamma production is a process sensitive to anomalous quartic bosonic couplings. The phenomenology we apply, the effective field theory, enables a model-independent representation of the sought-for effects of new physics in the form of parametrization of the SM Lagrangian using higher-dimensional operators. Each such operator is preceded by a coefficient, which has the meaning of the theory's coupling constants. We present here a technique developed to set 1D limits on the values of these coefficients. This technique makes it possible to set for some operators the expected limits that are more stringent than the currently available ones.
The modern state of the Pauli Exclusion Principle (PEP) is discussed. PEP can be considered from two viewpoints. On the one hand, it asserts that particles with half-integer spin (fermions) are ...described by antisymmetric wave functions, and particles with integer spin (bosons) are described by symmetric wave functions. This is the so-called spin-statistics connection (SSC). As we will discuss, the physical reasons why SSC exists are still unknown. On the other hand, according to PEP, the permutation symmetry of the total wave functions can be only of two types: symmetric or antisymmetric, both belong to one-dimensional representations of the permutation group, all other types of permutation symmetry are forbidden; whereas the solution of the Schrödinger equation may have any permutation symmetry. It is demonstrated that the proof in some textbooks on quantum mechanics that only symmetric and antisymmetric states can exist is wrong. However, the scenarios, in which arbitrary permutation symmetry (degenerate permutation states) is permitted, lead to contradictions with the concepts of particle identity and their independence. Thus, the existence in our Nature of particles only in nondegenerate permutation states (symmetric and antisymmetric) is not accidental and so-called symmetrization postulate should not be considered as a postulate, since all other symmetry options for the total wave function may not be realized. From this an important conclusion follows: we may not expect that in the future some unknown elementary particles can be discovered that are not fermions or bosons.
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