Explore the vast range of titles available.

A bstract This article presents searches for the Zγ decay of the Higgs boson and for narrow high-mass resonances decaying to Z γ, exploiting Z boson decays to pairs of electrons or muons. The data analysis uses 36.1 fb −1 of pp collisions at s = 13 recorded by the ATLAS detector at the CERN Large Hadron Collider. The data are found to be consistent with the expected Standard Model background. The observed (expected — assuming Standard Model pp → H → Z γ production and decay) upper limit on the production cross section times the branching ratio for pp → H → Z γ is 6.6. (5.2) times the Standard Model prediction at the 95% confidence level for a Higgs boson mass of 125.09 GeV. In addition, upper limits are set on the production cross section times the branching ratio as a function of the mass of a narrow resonance between 250 GeV and 2.4 TeV, assuming spin-0 resonances produced via gluon-gluon fusion, and spin-2 resonances produced via gluon-gluon or quark-antiquark initial states. For high-mass spin-0 resonances, the observed (expected) limits vary between 88 fb (61 fb) and 2.8 fb (2.7 fb) for the mass range from 250 GeV to 2.4 TeV at the 95% confidence level.

Warm air heaters are now widely used in enclosed environments, either as primary or auxiliary heating facilities. However, the influence of these heaters on the indoor air quality has received scant attention, and the currently available data is insufficient. Therefore, this study experimentally investigated the particle concentrations, air velocity, temperature, and relative humidity in a storeroom equipped with a warm air heater. To assess the effects of the heater on the dispersion and deposition of 0.3, 0.5, 1.0, 3.0, and 5.0 µm particles, we analyzed 18 scenarios with various settings for the output power and outlet orientation. The results indicated higher particle deposition rates when the heater was operating. Furthermore, the particles’ decay rate loss coefficients increased with the heater’s output power and the particles’ proximity tothe heater’s air outlet but were also influenced by the direction of the warm air flow.

We review lattice results related to pion, kaon, D-meson, B-meson, and nucleon physics with the aim of making them easily accessible to the nuclear and particle physics communities. More specifically, we report on the determination of the light-quark masses, the form factor f+(0) arising in the semileptonic K→π transition at zero momentum transfer, as well as the decay constant ratio fK/fπ and its consequences for the CKM matrix elements Vus and Vud. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of SU(2)L×SU(2)R and SU(3)L×SU(3)R Chiral Perturbation Theory. We review the determination of the BK parameter of neutral kaon mixing as well as the additional four B parameters that arise in theories of physics beyond the Standard Model. For the heavy-quark sector, we provide results for mc and mb as well as those for D- and B-meson decay constants, form factors, and mixing parameters. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. We review the status of lattice determinations of the strong coupling constant αs. Finally, in this review we have added a new section reviewing results for nucleon matrix elements of the axial, scalar and tensor bilinears, both isovector and flavor diagonal.

We present the first attempt to extract |Vcb| from the Λb→Λc+ℓν¯ℓ decay without relying on |Vub| inputs from the B meson decays. Meanwhile, the hadronic Λb→ΛcM(c) decays with M=(π-,K-) and Mc=(D-,Ds-) measured with high precisions are involved in the extraction. Explicitly, we find that |Vcb|=(44.6±3.2)×10-3, agreeing with the value of (42.11±0.74)×10-3 from the inclusive B→Xcℓν¯ℓ decays. Furthermore, based on the most recent ratio of |Vub|/|Vcb| from the exclusive modes, we obtain |Vub|=(4.3±0.4)×10-3, which is close to the value of (4.49±0.24)×10-3 from the inclusive B→Xuℓν¯ℓ decays. We conclude that our determinations of |Vcb| and |Vub| favor the corresponding inclusive extractions in the B decays.

The standard model of particle physics currently provides our best description of fundamental particles and their interactions. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Previous measurements have shown that a wide range of particle decays are consistent with this principle of lepton universality. This article presents evidence for the breaking of lepton universality in beauty-quark decays, with a significance of 3.1 standard deviations, based on proton–proton collision data collected with the LHCb detector at CERN’s Large Hadron Collider. The measurements are of processes in which a beauty meson transforms into a strange meson with the emission of either an electron and a positron, or a muon and an antimuon. If confirmed by future measurements, this violation of lepton universality would imply physics beyond the standard model, such as a new fundamental interaction between quarks and leptons. The Large Hadron Collider beauty collaboration reports a test of lepton flavour universality in decays of bottom mesons into strange mesons and a charged lepton pair, finding evidence of a violation of this principle postulated in the standard model.

Despite being a recognized health hazard, burning incense remains in widespread use. A number of studies have investigated the emissions of air pollulants from incense burning, but less attention has been given to particle decay following incense burning. We have studied the elemental composition and indoor emission characteristics of incense sticks in terms of the size distribution and concentrations of fine particles. The results of chemical analysis and energy dispersive X-ray spectroscopy showed that the primary constituents of the emissions were CaCO3 and SiO2, together with lesser amounts of Mg, K, Al, Fe, and Cl. Analysis using a scanning mobility particle sizer revealed that the maximum total particle concentration at the end of the burning period was up to 30-fold higher than that of the initial background levels and that it remained elevated even 100 min after the incense sticks had been completely burned up. Emitted incense particles decayed in a biexponential manner, with particles of up to 100 nm in size decaying with lifetimes of several tens of minutes, while nanoparticles with diameters of 100–700 nm having lifetimes of > 100 min, as their removal mechanisms are slower. The peak particle size immediately following the end of incense burning was 85 nm, and this increased to 110 nm at 100 min after completion of burning. This result indicates that a high proportion of emitted particles can be inhaled into the alveolar region of the lung, where the potential for adverse health effects is the greatest. These findings provide a more detailed insight into particle decay mechanisms under conditions of low ventilation, with implications for human health.

In this talk, we present successful aspects of the tetraquark mixing model for the two light-meson nonets in the J PC = 0 ++ channel, the light nonet [ a 0 (980), K * 0 (700) , ƒ 0 (500), ƒ 0 (980)] and the heavy nonet [ a 0 (1450), K 0 * (1430) , ƒ 0 (1370), ƒ 0 (1500)]. In particular, we focus on how their experimental partial decay widths extracted from Particle Data Group (PDG) can support this mix ing model. Currently, the experimental data exhibit an unnatural tendency that partial widths of the light nonet are consistently larger than those of the heavy nonet. This unnatural tendency can be explained if the coupling into two pseudoscalar mesons is enhanced in the light nonet and suppressed in the heavy nonet as predicted by the tetraquark mixing model. Therefore, this could be strong evidence to support for the tetraquark mixing model.

A bstract Axion-like particles (ALPs), which are gauge-singlets under the Standard Model (SM), appear in many well-motivated extensions of the SM. Describing the interactions of ALPs with SM fields by means of an effective Lagrangian, we discuss ALP decays into SM particles at one-loop order, including for the first time a calculation of the a → πππ decay rates for ALP masses below a few GeV. We argue that, if the ALP couples to at least some SM particles with couplings of order (0.01 − 1) TeV −1 , its mass must be above 1 MeV. Taking into account the possibility of a macroscopic ALP decay length, we show that large regions of so far unconstrained parameter space can be explored by searches for the exotic, on-shell Higgs and Z decays h → Za , h → aa and Z → γa in Run-2 of the LHC with an integrated luminosity of 300 fb −1 . This includes the parameter space in which ALPs can explain the anomalous magnetic moment of the muon. Considering subsequent ALP decays into photons and charged leptons, we show that the LHC provides unprecedented sensitivity to the ALP-photon and ALP-lepton couplings in the mass region above a few MeV, even if the relevant ALP couplings are loop suppressed and the a → γγ and a → ℓ + ℓ − branching ratios are significantly less than 1. We also discuss constraints on the ALP parameter space from electroweak precision tests.

A bstract Axions and axion-like particles (ALPs) are well-motivated low-energy relics of high-energy extensions of the Standard Model (SM). We investigate the phenomenology of an ALP with flavor-changing couplings, and present a comprehensive analysis of quark and lepton flavor-changing observables within a general ALP effective field theory. Observables studied include rare meson decays, flavor oscillations of neutral mesons, rare lepton decays, and dipole moments. We derive bounds on the general ALP couplings as a function of its mass, consistently taking into account the ALP lifetime and branching ratios. We further calculate quark flavor-changing effects that are unavoidably induced by running and matching between the new physics scale and the scale of the measurements. This allows us to derive bounds on benchmark ALP models in which only a single (flavorless or flavor-universal) ALP coupling to SM particles is present at the new physics scale, and in this context we highlight the complementarity and competitiveness of flavor bounds with constraints derived from collider, beam dump and astrophysical measurements. We find that searches for ALPs produced in meson decays provide some of the strongest constraints in the MeV-GeV mass range, even for the most flavorless of ALP models. Likewise, we discuss the interplay of flavor-conserving and flavor-violating couplings of the ALP to leptons, finding that constraints from lepton flavor-violating observables generally depend strongly on both. Additionally, we analyze whether an ALP can provide an explanation for various experimental anomalies including those observed in rare B -meson decays, measurements at the ATOMKI and KTeV experiments, and in the anomalous magnetic moments of the muon and the electron.

A bstract Evidence for Higgs boson decay to a pair of muons is presented. This result combines searches in four exclusive categories targeting the production of the Higgs boson via gluon fusion, via vector boson fusion, in association with a vector boson, and in association with a top quark-antiquark pair. The analysis is performed using proton-proton collision data at s = 13 TeV, corresponding to an integrated luminosity of 137 fb − 1 , recorded by the CMS experiment at the CERN LHC. An excess of events over the back- ground expectation is observed in data with a significance of 3.0 standard deviations, where the expectation for the standard model (SM) Higgs boson with mass of 125.38 GeV is 2.5. The combination of this result with that from data recorded at s = 7 and 8 TeV, corresponding to integrated luminosities of 5.1 and 19.7 fb − 1 , respectively, increases both the expected and observed significances by 1%. The measured signal strength, relative to the SM prediction, is 1.19 − 0.39 + 0.40 stat − 0.14 + 0.15 syst . This result constitutes the first evidence for the decay of the Higgs boson to second generation fermions and is the most precise measurement of the Higgs boson coupling to muons reported to date.