Unsupervised Quark/Gluon Jet Tagging With Poissonian Mixture Models

The classification of jets induced by quarks or gluons is important for New Physics searches at high-energy colliders. However, available taggers usually rely on modeling the data through Monte Carlo simulations, which could veil intractable theoretical and systematical uncertainties. To significantly reduce biases, we propose an unsupervised learning algorithm that, given a sample of jets, can learn the SoftDrop Poissonian rates for quark- and gluon-initiated jets and their fractions. We extract the Maximum Likelihood Estimates for the mixture parameters and the posterior probability over them. We then construct a quark-gluon tagger and estimate its accuracy in actual data to be in the 0.65-0.7 range, below supervised algorithms but nevertheless competitive. We also show how relevant unsupervised metrics perform well, allowing for an unsupervised hyperparameter selection. Further, we find that this result is not affected by an angular smearing introduced to simulate detector effects for central jets. The presented unsupervised learning algorithm is simple; its result is interpretable and depends on very few assumptions.

Surgical treatment in combined hamartoma of the retina and retinal pigment epithelium

CASE REPORT

The case is presented of a 39 year-old man with a combined hamartoma of the retina and retinal pigment epithelium, who experienced progressive visual loss and worsening of metamorphopsia. The patient underwent vitrectomy and epiretinal component peeling, with improvement in visual acuity, metamorphopsia, and retinal architecture, assessed by optical coherence tomography.

DISCUSSION

Selected patients with combined hamartomas of the retina and retinal pigment epithelium may benefit from surgical management.

Churg-Strauss syndrome associated with antiphospholipid antibodies in a patient with retinal vasculitis

CASE REPORT

We present the case of a 69-year-old woman with unilateral retinal vasculitis. Investigations showed asthma, rhinosinusitis, nasal polyposis, peripheral blood eosinophilia, increased sedimentation rate, proteinuria, and antiphospholipid antibodies. Anti-neutrophil cytoplasmic antibodies (ANCA) were negative.

DISCUSSION

Although her anti-neutrophil cytoplasmatic antibody (ANCA) status was negative, taking into account the other clinical and laboratory features, retinal vasculitis was thought to be an ocular manifestation of Churg-Strauss syndrome. Treatment was started with high-dose corticosteroids and anticoagulant therapy.