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Goodness of fit by Neyman-Pearson testing
No full textThe Neyman-Pearson strategy for hypothesis testing can be employed for goodness of fit if the alternative hypothesis is selected from data by exploring a rich parametrised family of models, while controlling the impact of statistical fluctuations. The New Physics Learning Machine (NPLM) methodology has been developed as a concrete implementation of this idea, to target the detection of new physical effects in the context of high energy physics collider experiments. In this paper we conduct a comparison of this approach to goodness of fit with others, in particular with classifier-based strategies that share strong similarities with NPLM. From our comparison, NPLM emerges as the more sensitive test to small departures of the data from the expected distribution and not biased towards detecting specific types of anomalies. These features make it suited for agnostic searches for new physics at collider experiments. Its deployment in other scientific and industrial scenarios should be investigated
Efficient quantum algorithm to simulate open systems through a single environmental qubit
No full textWe present an efficient algorithm for simulating open quantum systems dynamics described by the Lindblad master equation on quantum computers, addressing key challenges in the field. In contrast to existing approaches, our method achieves two significant advancements. First, we employ a repetition of unitary gates on a set of n system qubits and, remarkably, only a single ancillary bath qubit representing the environment. It follows that, for the typical case of m locality of the Lindblad operators, we reach an exponential improvement of the number of ancilla in terms of m and up to a polynomial improvement in ancilla overhead for large n with respect to other approaches. Although stochasticity is introduced, requiring multiple circuit realizations, the sampling overhead is independent of the system size. Second, we show that, under fixed accuracy conditions, our algorithm enables a reduction in the number of Trotter steps compared to other approaches, substantially decreasing circuit depth. These advancements hold particular significance for near-term quantum computers, where minimizing both width and depth is critical due to inherent noise in their dynamics
Exploring nonstandard <math display="inline"><mi>H</mi><mi>b</mi><mover accent="true"><mi>b</mi><mo stretchy="false">¯</mo></mover></math> interactions at future electron-proton colliders
No full textIn this paper, we use the charged-current Higgs boson production process at future electron-proton colliders, e-p→Hjνe, with the subsequent decay of the Higgs boson into a bb¯ pair, to probe the Standard Model effective field theory with dimension-six operators involving the Higgs boson and the bottom quark. The study is performed for two proposed future high-energy electron-proton colliders, the Large Hadron Electron Collider (LHeC) and the Future Circular Collider (FCC-he) at the center-of-mass energies of 1.3 TeV and 3.46 TeV, respectively. Constraints on the CP-even and CP-odd Hbb¯ couplings are derived by analyzing the simulated signal and background samples. A realistic detector simulation is performed and a multivariate technique using the gradient boosted decision trees algorithm is employed to discriminate the signal from background. Expected limits are obtained at 95% confidence level for the LHeC and FCC-he assuming the integrated luminosities of 1, 2 and 10 ab-1. We find that using 1 ab-1 of data, the CP-even and CP-odd Hbb¯ couplings can be constrained with accuracies of the order of 10-3 and 10-2, respectively, and a significant region of the unprobed parameter space becomes accessible
Radiative corrections to the R and R invariants from torsion fluctuations on maximally symmetric spaces
No full textWe derive the runnings of the R and R operators that stem from integrating out quantum torsion fluctuations on a maximally symmetric Euclidean background, while treating the metric as a classical field. Our analysis is performed in a manifestly covariant way, exploiting both the recently-introduced spin-parity decomposition of torsion perturbations and the heat kernel technique. The Lagrangian we start with is the most general one for 1-loop computations on maximally symmetric backgrounds involving kinetic terms and couplings to the scalar curvature that is compatible with a gauge-like symmetry for the torsion. The latter removes the twice-longitudinal vector mode from the spectrum, and it yields operators of maximum rank four. We also examine the conditions required to avoid ghost instabilities and ensure the validity of our assumption to neglect metric quantum fluctuations, demonstrating the compatibility between these two assumptions. Then, we use our findings in the context of Starobinsky's inflation to calculate the contributions from the torsion tensor to the β-function of the R term. While this result is quantitatively reliable only at the 0-th order in the slow-roll parameters or during the very early stages of inflation — due to the background choice — it qualitatively illustrates how to incorporate quantum effects of torsion in the path integral formalism
Phase-space analysis in non-minimal symmetric-teleparallel dark energy
No full textWe modify the symmetric-teleparallel dark energy through the addition of a further Yukawa-like term, in which the non-metricity scalar, Q, is non-minimally coupled to a scalar field Lagrangian where the phion acts as quintessence, describing dark energy. We investigate regions of stability and find late-time attractors. To do so, we conduct a stability analysis for different types of physical potentials describing dark energy, namely the power-law, inverse power-law, and exponential potentials. Within these choices, we furthermore single out particular limiting cases, such as the constant, linear and inverse potentials. For all the considered scenarios, regions of stability are calculated in terms of the signs of the coupling constant and the exponent, revealing a clear degeneracy among coefficients necessary to ensure stability. We find that a generic power-law potential with \alpha > 0 is not suitable as a non-minimal quintessence potential and we put severe limits on the use of inverse potential, as well. In addition, the equations of state of each potential have been also computed. We find the constant potential seems to be favored than other treatments, since the critical point appears independent of the non-minimal coupling
TomOpt: differential optimisation for task- and constraint-aware design of particle detectors in the context of muon tomography
No full textWe describe a software package, TomOpt, developed to optimise the geometrical layout and specifications of detectors designed for tomography by scattering of cosmic-ray muons. The software exploits differentiable programming for the modeling of muon interactions with detectors and scanned volumes, the inference of volume properties, and the optimisation cycle performing the loss minimisation. In doing so, we provide the first demonstration of end-to-end-differentiable and inference-aware optimisation of particle physics instruments. We study the performance of the software on a relevant benchmark scenario and discuss its potential applications. Our code is available on Github (Strong et al 2024 available at: https://github.com/GilesStrong/tomopt)
<math display="inline"><msub><mi>γ</mi><mn>5</mn></msub></math> schemes and the interplay of SMEFT operators in the Higgs-gluon coupling
No full textWe calculate the four-top-quark operator contributions to Higgs production via gluon fusion in the Standard Model effective field theory. The four-top operators enter for the first time via two-loop diagrams. Owing to their chiral structure they contain γ5, so special care needs to be taken when using dimensional regularization for the loop integrals. We use two different schemes for the continuation of γ5 to D space-time dimensions in our calculations and present a mapping for the parameters in the two schemes. This generically leads to an interplay of different operators, such as four-top operators, chromomagnetic operators, or Yukawa-type operators at the loop level. We validate our results by examples of matching onto UV models
Deep-underground dark matter search with a COSINUS detector prototype
No full textSodium iodide (NaI)-based cryogenic scintillating calorimeters using quantum sensors for signal readout have shown promising first results toward a model-independent test of the annually modulating signal detected by the DAMA/LIBRA dark matter experiment. The COSINUS Collaboration has previously reported on the first above-ground measurements using a dual-channel readout of phonons and light based on transition edge sensors (TESs) that allows for particle discrimination on an event-by-event basis. In this article, we outline the first underground measurement of a NaI cryogenic calorimeter readout via the novel remoTES scheme. A 3.67 g NaI absorber with an improved silicon light detector design was operated at the Laboratori Nazionali del Gran Sasso, Italy. A significant improvement in the discrimination power of e-/γ events to nuclear recoils was observed with a fivefold improvement in the nuclear recoil baseline resolution, achieving σ=441 eV. Furthermore, we present a limit on the spin-independent dark matter nucleon elastic scattering cross section, achieving a sensitivity of O(pb) with an exposure of only 11.6 g d
The Sun as a target for axion dark matter detection
No full textThe exploration of the parameter space of axion and axion-like particle dark matter is a major aim of the future program of astroparticle physics investigations. In this context, we present a possible strategy that focuses on detecting radio emissions arising from the conversion of dark matter axions in the Sun's magnetic field, including conversion in sunspots. We demonstrate that near-future low-frequency radio telescopes, such as the SKA Low, may access regions of unexplored parameter space for masses ma≲10−6 eV
Study of the measurement of the <math display="inline"><mi>τ</mi></math> lepton anomalous magnetic moment in high energy lead-lead collisions at the LHC
No full textThe τ lepton anomalous magnetic moment aτ=gτ-22 was measured, so far, with a precision of only several percents, despite its high sensitivity to physics beyond the Standard Model such as compositeness or supersymmetry. A new study is presented to improve the sensitivity of the aτ measurement with photon-photon interactions from ultraperipheral lead-lead collisions at the LHC. The theoretical approach used in this work is based on an effective Lagrangian and on a photon flux implemented in the madgraph5 Monte Carlo simulation. Using a multivariate analysis to discriminate the signal from the background processes, a sensitivity to the anomalous magnetic moment aτ=0+0.015−0.019 is obtained at 95% confidence level with a dataset corresponding to an integrated luminosity of 2 nb-1 of lead-lead collisions and assuming a conservative 10% systematic uncorrelated uncertainty for signal and background. The present results using multivariate analysis are compared to similar results obtained using sequential cuts, as done in previous measurements, showing an improvement of about 35% in the sensitivity to aτ