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Study of the <math display="inline"><msub><mi>f</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></math> and <math display="inline"><mrow><msub><mrow><mi>f</mi></mrow><mrow><mn>0</mn></mrow></msub><mo stretchy="false">(</mo><mn>500</mn><mo stretchy="false">)</mo></mrow></math> Scalar Mesons through the Decay <math display="inline"><mrow><msubsup><mrow><mi>D</mi></mrow><mrow><mi>s</mi></mrow><mrow><mo>+</mo></mrow></msubsup><mo stretchy="false">→</mo><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>-</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub></mrow></math>
No full textUsing e+e- collision data corresponding to an integrated luminosity of 7.33 fb-1 recorded by the BESIII detector at center-of-mass energies between 4.128 and 4.226 GeV, we present an analysis of the decay Ds+→π+π-e+νe, where the Ds+ is produced via the process e+e-→Ds*±Ds∓. We observe the f0(980) in the π+π- system and the branching fraction of the decay Ds+→f0(980)e+νe with f0(980)→π+π- measured to be (1.72±0.13stat±0.10syst)×10-3, where the uncertainties are statistical and systematic, respectively. The dynamics of the Ds+→f0(980)e+νe decay are studied with the simple pole parametrization of the hadronic form factor and the Flatté formula describing the f0(980) in the differential decay rate, and the product of the form factor f+f0(0) and the c→s Cabibbo-Kobayashi-Maskawa matrix element |Vcs| is determined for the first time to be f+f0(0)|Vcs|=0.504±0.017stat±0.035syst. Furthermore, the decay Ds+→f0(500)e+νe is searched for the first time but no signal is found. The upper limit on the branching fraction of Ds+→f0(500)e+νe, f0(500)→π+π- decay is set to be 3.3×10-4 at 90% confidence level
Observation of Cabibbo-Suppressed Two-Body Hadronic Decays and Precision Mass Measurement of the <math display="inline"><mrow><msubsup><mrow><mi mathvariant="normal">Ω</mi></mrow><mrow><mi>c</mi></mrow><mrow><mn>0</mn></mrow></msubsup></mrow></math> Baryon
No full textThe first observation of the singly Cabibbo-suppressed Ωc0→Ω-K+ and Ωc0→Ξ-π+ decays is reported, using proton-proton collision data at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb-1, collected with the LHCb detector between 2016 and 2018. The branching fraction ratios are measured to be B(Ωc0→Ω-K+)B(Ωc0→Ω-π+)=[6.08±0.51(stat)±0.40(syst)]%,B(Ωc0→Ξ-π+)B(Ωc0→Ω-π+)=[15.81±0.87(stat)±0.44(syst)±0.16(ext)]%. In addition, using the Ωc0→Ω-π+ decay channel, the Ωc0 baryon mass is measured to be M(Ωc0)=2695.28±0.07(stat)±0.27(syst)±0.30(ext) MeV, improving the precision of the previous world average by a factor of 4
Autoencoder-Based Anomaly Detection System for Online Data Quality Monitoring of the CMS Electromagnetic Calorimeter
No full textThe CMS detector is a general-purpose apparatus that detects high-energy collisions produced at the LHC. Online data quality monitoring of the CMS electromagnetic calorimeter is a vital operational tool that allows detector experts to quickly identify, localize, and diagnose a broad range of detector issues that could affect the quality of physics data. A real-time autoencoder-based anomaly detection system using semi-supervised machine learning is presented enabling the detection of anomalies in the CMS electromagnetic calorimeter data. A novel method is introduced which maximizes the anomaly detection performance by exploiting the time-dependent evolution of anomalies as well as spatial variations in the detector response. The autoencoder-based system is able to efficiently detect anomalies, while maintaining a very low false discovery rate. The performance of the system is validated with anomalies found in 2018 and 2022 LHC collision data. In addition, the first results from deploying the autoencoder-based system in the CMS online data quality monitoring workflow during the beginning of Run 3 of the LHC are presented, showing its ability to detect issues missed by the existing system
Electric shocks: bounding Einstein-Maxwell theory with time delays on boosted RN backgrounds
No full textThe requirement that particles propagate causally on non-trivial backgrounds implies interesting constraints on higher-derivative operators. This work is part of a systematic study of the positivity bounds derivable from time delays on shockwave backgrounds. First, we discuss shockwaves in field theory, which are infinitely boosted Coulomb-like field configurations. We show how a positive time delay implies positivity of four-derivative operators in scalar field theory and electromagnetism, consistent with the results derived using dispersion relations, and we comment on how additional higher-derivative operators could be included.We then turn to gravitational shockwave backgrounds. We compute the infinite boost limit of Reissner-Nordström black holes to derive charged shockwave backgrounds. We consider photons traveling on these backgrounds and interacting through four-derivative corrections to Einstein-Maxwell theory. The inclusion of gravity introduces a logarithmic term into the time delay that interferes with the straightforward bounds derivable in pure field theory, a fact consistent with CEMZ and with recent results from dispersion relations. We discuss two ways to extract a physically meaningful quantity from the logarithmic time delay — by introducing an IR cutoff, or by considering the derivative of the time delay — and comment on the bounds implied in each case. Finally, we review a number of additional shockwave backgrounds which might be of use in future applications, including spinning shockwaves, those in higher dimensions or with a cosmological constant, and shockwaves from boosted extended objects
Lattice Boltzmann method for warm fluid simulations of plasma wakefield acceleration
No full textA comprehensive characterization of lattice Boltzmann (LB) schemes to perform warm fluid numerical simulations of particle wakefield acceleration (PWFA) processes is discussed in this paper. The LB schemes we develop hinge on the moment matching procedure, allowing the fluid description of a warm relativistic plasma wake generated by a driver pulse propagating in a neutral plasma. We focus on fluid models equations resulting from two popular closure assumptions of the relativistic kinetic equations, i.e., the local equilibrium and the warm plasma closure assumptions. The developed LB schemes can, thus, be used to disclose insights on the quantitative differences between the two closure approaches in the dynamics of PWFA processes. Comparisons between the proposed schemes and available analytical results are extensively addressed
Constraints on quantum spacetime-induced decoherence from neutrino oscillations
No full textWe investigate the implications of decoherence induced by quantum spacetime properties on neutrino oscillation phenomena. We develop a general formalism where the evolution of neutrinos is governed by a Lindblad-type equation and we compute the oscillation damping factor for various models that have been proposed in the literature. Furthermore, we discuss the sensitivity to these effects of different types of neutrino oscillation experiments, encompassing astrophysical, atmospheric, solar, and reactor neutrino experiments. By using neutrino oscillation data from long-baseline reactors and atmospheric neutrino observations, we establish stringent constraints on the energy scale governing the strength of the decoherence induced by stochastic metric fluctuations, amounting to, respectively, EQG≥2.6×1034 GeV and EQG≥2.5×1055 GeV
Probing the galactic and extragalactic gravitational wave backgrounds with space-based interferometers
No full textWe employ the formalism developed in [1] and [2] tostudy the prospect of detecting an anisotropic Stochastic Gravitational Wave Background (SGWB)with the Laser Interferometer Space Antenna (LISA) alone, and combined with the proposedspace-based interferometer Taiji. Previous analyses have been performed in the frequency domainonly. Here, we study the detectability of the individual coefficients of the expansion of the SGWBin spherical harmonics, by taking into account the specific motion of the satellites. Thisrequires the use of time-dependent response functions, which we include in our analysis to obtainan optimal estimate of the anisotropic signal. We focus on two applications. Firstly, thereconstruction of the anisotropic galactic signal without assuming any prior knowledge of itsspatial distribution. We find that both LISA and LISA with Taiji cannot put tight constraints onthe harmonic coefficients for realistic models of the galactic SGWB. We then focus on thediscrimination between a galactic signal of known morphology but unknown overall amplitude and anisotropic extragalactic SGWB component of astrophysical origin. In this case, we find that the twosurveys can confirm, at a confidence level ≳ 3σ, the existence of both the galacticand extragalactic background if both have amplitudes as predicted in standard models. We also findthat, in the LISA-only case, the analysis in the frequency domain (under the assumption of a timeaverage of data taken homogeneously across the year) provides a nearly identical determination ofthe two amplitudes as compared to the optimal analysis
The maximal frequency of cosmic gravitons
No full textWe show that the maximal frequency of cosmic gravitons must not exceed the THz domain. From a classical viewpoint, both in conventional inflationary scenarios and in bouncing models the largest frequency of the spectrum overshoots the MHz band even if its specific signature is model dependent. According to a quantum mechanical perspective the maximal frequency is instead associated with the range of energies where a single pair of gravitons with opposite (comoving) three-momenta is produced. The upper limit on the largest frequency determines the minimal chirp amplitude [typically O(10−32)] required for a direct detection of a cosmic signal in the THz band. Below this limiting frequency the minimal chirp amplitude can be enhanced so that the optimal range ultimately depends on the physical properties of the diffuse backgrounds. In case a hypothetical instrument (at present just a figment of a hopeful imagination) would reach chirp amplitudes down to O(10−30) in the MHz or GHz bands, the Bose-Einstein correlations could be used to probe the properties of cosmic gravitons and their super-Poissonian statistics
Anomaly constraints for heterotic strings and supergravity in six dimensions
No full textThe landscape of six-dimensional supergravities is dramatically constrained by the cancellation of gauge and gravitational anomalies, but the full extent of its implications has not been uncovered. We explore the cancellation of global anomalies of the Dai-Freed type in this setting with abelian and simply laced gauge groups, finding novel constraints. In particular, we exclude arbitrarily large abelian charges in an infinite family of theories for certain types of quadratic refinements, including a specific one defined in the literature. We also show that the Gepner orientifold with no tensor multiplets is anomaly-free for a different choice, as well as a number of heterotic models with and without spacetime supersymmetry in six dimensions. The latter analysis extends previous results in ten dimensions to some lower-dimensional settings in the heterotic landscape
On energy and particle production in cosmology: the particular case of the gravitino
No full textIt is well-known that the number of particles produced in cosmology, commonly defined in the literature from the Fock space of the instantaneous hamiltonian of the canonically normalized fields, is ambiguous. On the other hand, the energy computed from the energy-momentum tensor should be physical. We compare the corresponding Fock spaces and relate them through a Bogolyubov transformation. We find that for particles of spin 0, 1 and 3/2 the two Fock spaces are different, whereas they are the same for spin 1/2 fermions. For spin 0 and 1, for particles of high momenta the two Fock spaces align, as intuitively expected. For the spin 3/2, one finds two puzzles. The first one is that the two corresponding Fock spaces do not match even in the limit of high momenta. The second is that whereas we provide evidence for the equivalence theorem between longitudinal gravitinos and the goldstino in terms of an exact matching between the lagrangians and the instantaneous hamiltonians for the canonically normalized fields, the energy operator computed from the Rarita-Schwinger action does not seem to be captured in a simple way by the goldstino action. Our results suggest a re-analysis of non-thermal gravitino production in cosmology