Generic Loop Effects of New Scalars and Fermions in b→sℓ+ℓ−b\to s\ell^+\ell^-, (g−2)μ(g-2)_\mu and a Vector-like 4th4^{\rm th} Generation

In this article we investigate in detail the possibility of accounting for the $b\to s\ell^+\ell^-$ and $(g-2)_\mu$ anomalies via loop contributions involving with new scalars and fermions. For this purpose, we first write down the most general Lagrangian which can generate the desired effects and then calculate the generic expressions for all relevant $b\to s$ Wilson coefficients. Here we extend previous analysis by allowing that the new particles can also couple to right-handed Standard Model (SM) fermions as preferred by recent $b\to s\ell^+\ell^-$ data and the anomalous magnetic moment of the muon. In the second part of this article we illustrate this generic approach for a UV complete model in which we supplement the Standard Model by a $4^{\rm th}$ generation of vector-like fermions and a real scalar field. This model allows one to coherently address the observed anomalies in $b\to s\ell^+\ell^-$ transitions and in $a_\mu$ without violating the bounds from other observables (in particular $B_s -\bar B_s$ mixing) or LHC searches. In fact, we find that our global fit to this model, after the recent experimental updates, is very good and prefers couplings to right-handed SM fermions, showing the importance of our generic setup and calculation performed in the first part of the article.Comment: 44 pages, 10 figures, 7 table

Muon g-2 and B Anomalies from Dark Matter

In light of the recent result of the muon g−2 experiment and the update on the test of lepton flavor universality RK published by the LHCb Collaboration, we systematically study for the first time a set of models with minimal field content that can simultaneously give (i) a thermal dark matter candidate; (ii) large loop contributions to b→sℓℓ processes able to address RK and the other B anomalies; (iii) a natural solution to the muon g−2 discrepancy through chirally enhanced contributions. Moreover, this type of model with heavy particles and chiral enhancement can evade the strong limits from direct searches but can be tested at present and future colliders and direct-detection searches

Systematic approach to B-physics anomalies and t-channel dark matter

We study renormalizable models with minimal field content that can provide a viable dark matter candidate through the standard freeze-out paradigm and, simultaneously, accommodate the observed anomalies in semileptonic B-meson decays at one loop. Following the hypothesis of minimality, this outcome can be achieved by extending the particle spectrum of the Standard Model either with one vectorlike fermion and two scalars or two vectorlike fermions and one scalar. The dark matter annihilations are mediated by t-channel exchange of other new particles contributing to the B anomalies, thus resulting in a correlation between flavor observables and dark matter abundance. Again based on minimality, we assume the new states to couple only with left-handed muons and second and third generation quarks. Besides an ad hoc symmetry needed to stabilize the dark matter, the interactions of the new states are dictated only by gauge invariance. We present here for the first time a systematic classification of the possible models of this kind, according to the quantum numbers of the new fields under the Standard Model gauge group. Within this general setup we identify a group of representative models that we systematically study, applying the most updated constraints from flavor observables, dedicated dark matter experiments, and LHC searches of leptons and/or jets and missing energy, and of disappearing charged tracks

Solar axions cannot explain the XENON1T excess

We argue that the interpretation in terms of solar axions of the recent XENON1T excess is not tenable when confronted with astrophysical observations of stellar evolution. We discuss the reasons why the emission of a flux of solar axions sufficiently intense to explain the anomalous data would radically alter the distribution of certain type of stars in the color-magnitude diagram in first place, and would also clash with a certain number of other astrophysical observables. Quantitatively, the significance of the discrepancy ranges from $3.3\sigma$ for the rate of period change of pulsating White Dwarfs, and exceedes $19\sigma$ for the $R$-parameter and for $M_{I,{\rm TRGB}}$.Comment: 6 pages, 2 figures, 1 table. Version accepted for publication on PR

What is the scale of new physics behind the muon g−2g-2?

We study the constraints imposed by perturbative unitarity on the new physics interpretation of the muon $g-2$ anomaly. Within a Standard Model Effective Field Theory (SMEFT) approach, we find that scattering amplitudes sourced by effective operators saturate perturbative unitarity at about 1 PeV. This corresponds to the highest energy scale that needs to be probed in order to resolve the new physics origin of the muon $g-2$ anomaly. On the other hand, simplified models (e.g.~scalar-fermion Yukawa theories) in which renormalizable couplings are pushed to the boundary of perturbativity still imply new on-shell states below 200 TeV. We finally suggest that the highest new physics scale responsible for the anomalous effect can be reached in non-renormalizable models at the PeV scale.Comment: 16 pages, 4 figure

Congestion and incentives in the age of driverless fleets

The diffusion of autonomous vehicles (AVs) will expand the tools to manage congestion. Differently than fleets of traditional vehicles, operators of fleets of AVs will be able to assign different travelers to different routes, potentially inducing different congestion levels (and speed). We look at the effects of the technological transition from traditional to autonomous vehicles. Our model exhibits a unit mass of heterogeneous individuals. Some of them use the services of a fleet, while others do not, and travel independently. With few fleet users, the fleet technology (traditional vs automated vehicles) is immaterial to welfare. On the contrary, when there are many fleet users, we show that, if fleets do not price any individuals out of the market, the differentiation in congestion across routes under the automated fleet is welfare-reducing. When, instead, fleets price some individuals out of the market, the welfare effects of the transition are ambiguous and depend on the interplay between the extent of rationing by both types of fleets and the extent of differentiation by the AVs fleet. Finally, we characterize the tax restoring the first best with AVs. It involves charging different taxes across lanes, starkly different between independent travelers and the fleet. While independent travelers should be charged lane-specific congestion charges, the fleet should be imposed a scheme involving a congestion-based tax and a subsidy

OpenMask3D: Open-Vocabulary 3D Instance Segmentation

We introduce the task of open-vocabulary 3D instance segmentation. Traditional approaches for 3D instance segmentation largely rely on existing 3D annotated datasets, which are restricted to a closed-set of object categories. This is an important limitation for real-life applications where one might need to perform tasks guided by novel, open-vocabulary queries related to objects from a wide variety. Recently, open-vocabulary 3D scene understanding methods have emerged to address this problem by learning queryable features per each point in the scene. While such a representation can be directly employed to perform semantic segmentation, existing methods have limitations in their ability to identify object instances. In this work, we address this limitation, and propose OpenMask3D, which is a zero-shot approach for open-vocabulary 3D instance segmentation. Guided by predicted class-agnostic 3D instance masks, our model aggregates per-mask features via multi-view fusion of CLIP-based image embeddings. We conduct experiments and ablation studies on the ScanNet200 dataset to evaluate the performance of OpenMask3D, and provide insights about the open-vocabulary 3D instance segmentation task. We show that our approach outperforms other open-vocabulary counterparts, particularly on the long-tail distribution. Furthermore, OpenMask3D goes beyond the limitations of close-vocabulary approaches, and enables the segmentation of object instances based on free-form queries describing object properties such as semantics, geometry, affordances, and material properties.Comment: project page: https://openmask3d.github.io

Microstrip Resonators and Broadband Lines for X-band EPR Spectroscopy of Molecular Nanomagnets

We present a practical setup to perform continuous-wave X-band electron paramagnetic resonance spectroscopy by using planar microstrip lines and general purpose instrumentation. We fabricated Ag/alumina and Nb/sapphire microstrip resonators and transmission lines and compared their performance down to 2 K and under applied magnetic field. We used these devices to study single crystals of molecular Cr3 nanomagnets. By means of X-band planar resonators we measured angle-dependent spectra at fixed frequency, while broadband transmission lines were used to measure continuous wave spectra with varying frequency in the range 2–25 GHz. The spectra acquired at low temperatures allowed to extract the essential parameters of the low-lying energy levels of Cr3 and demonstrate that this method is particularly suitable to study small crystals of molecular nanomagnets

Acute hemodynamic effects of inhaled nitric oxide, dobutamine and a combination of the two in patients with mild to moderate secondary pulmonary hypertension

INTRODUCTION: The use of low-dose dobutamine to maintain hemodynamic stability in pulmonary hypertension may have a detrimental effect on gas exchange. The aim of this study was to investigate whether inhaled nitric oxide (INO), dobutamine and a combination of the two have beneficial effects in patients with end-stage airway lung disease and pulmonary hypertension. METHOD: Hemodynamic evaluation was assessed 10 min after the administration of each drug and of their combination, in 28 candidates for lung transplantation. RESULTS: Administration of INO caused a reduction in mean pulmonary arterial pressure (MPAP), an increase in PaO(2) with a significant reduction in venous admixture effect (Q(s)/Q(t)).Dobutamine administration caused an increase in cardiac index and MPAP, with a decrease in PaO(2) as a result of a higher Q(s)/Q(t). Administration of a combination of the two drugs caused an increase in the cardiac index without MPAP modification and an increase in PaO(2) and Q(s)/Q(t). CONCLUSION: Dobutamine and INO have complementary effects on pulmonary circulation. Their association may be beneficial in the treatment of patients with mild to moderate pulmonary hypertension

Ultrastrong coupling between electron tunneling and mechanical motion

The ultrastrong coupling of single-electron tunneling and nanomechanical motion opens exciting opportunities to explore fundamental questions and develop new platforms for quantum technologies. We have measured and modelled this electromechanical coupling in a fully-suspended carbon nanotube device and report a ratio of $g_m/\omega_m = 1.3$, where $g_m/2\pi = 420\pm20$~MHz is the coupling strength and $\omega_m/2\pi=324$~MHz is the mechanical resonance frequency. This is well within the ultrastrong coupling regime and the highest among current electromechanical platforms. Even higher ratios could be achieved with improvement on device design