Dark-Sector Search via Pion-Produced η and η^{'} Mesons Decaying Invisibly in the NA64h Detector.

We present the first results from a proof-of-concept search for dark sectors via invisible decays of pseudoscalar η and η^{'} mesons in the NA64h experiment at the CERN SPS. Our novel technique uses the charge-exchange reaction of 50 GeV π^{-} on nuclei of an active target as the source of neutral mesons. The η,η^{'}→invisible events would exhibit themselves via a striking signature-the complete disappearance of the incoming beam energy in the detector.

Search for Light Dark Matter with NA64 at CERN.

Thermal dark matter models with particle χ masses below the electroweak scale can provide an explanation for the observed relic dark matter density. This would imply the existence of a new feeble interaction between the dark and ordinary matter. We report on a new search for the sub-GeV χ production through the interaction mediated by a new vector boson, called the dark photon A^{'}, in collisions of 100 GeV electrons with the active target of the NA64 experiment at the CERN SPS.

Search for a New B-L Z^{'} Gauge Boson with the NA64 Experiment at CERN.

A search for a new Z^{'} gauge boson associated with (un)broken B-L symmetry in the keV-GeV mass range is carried out for the first time using the missing-energy technique in the NA64 experiment at the CERN SPS. From the analysis of the data with 3.22×10^{11} electrons on target collected during 2016-2021 runs, no signal events were found.

Multidimensional, High Precision Measurements of Beam Single Spin Asymmetries in Semi-inclusive π^{+} Electroproduction off Protons in the Valence Region.

High precision measurements of the polarized electron beam-spin asymmetry in semi-inclusive deep inelastic scattering (SIDIS) from the proton have been performed using a 10.6 GeV incident electron beam and the CLAS12 spectrometer at Jefferson Lab. We report here a high precision multidimensional study of single π^{+} SIDIS data over a large kinematic range in Bjorken x, fractional energy, and transverse momentum of the hadron as well as photon virtualities Q^{2} ranging from 1-7  GeV^{2}.

Improved Λp Elastic Scattering Cross Sections between 0.9 and 2.0 GeV/c as a Main Ingredient of the Neutron Star Equation of State.

Strange matter is believed to exist in the cores of neutron stars based on simple kinematics. If this is true, then hyperon-nucleon interactions will play a significant part in the neutron star equation of state. Yet, compared to other elastic scattering processes, there is very little data on Λ-N scattering.

First Measurement of Timelike Compton Scattering.

We present the first measurement of the timelike Compton scattering process, γp→p^{'}γ^{*}(γ^{*}→e^{+}e^{-}), obtained with the CLAS12 detector at Jefferson Lab. The photon beam polarization and the decay lepton angular asymmetries are reported in the range of timelike photon virtualities 2.25 View Article and Find Full Text PDF

Observation of Beam Spin Asymmetries in the Process ep→e^{'}π^{+}π^{-}X with CLAS12.

The observation of beam spin asymmetries in two-pion production in semi-inclusive deep inelastic scattering off an unpolarized proton target is reported. The data presented here were taken in the fall of 2018 with the CLAS12 spectrometer using a 10.6 GeV longitudinally spin-polarized electron beam delivered by CEBAF at JLab.

Photoproduction of the f_{2}(1270) Meson Using the CLAS Detector.

The quark structure of the f_{2}(1270) meson has, for many years, been assumed to be a pure quark-antiquark (qq[over ¯]) resonance with quantum numbers J^{PC}=2^{++}. Recently, it was proposed that the f_{2}(1270) is a molecular state made from the attractive interaction of two ρ mesons. Such a state would be expected to decay strongly to final states with charged pions due to the dominant decay ρ→π^{+}π^{-}, whereas decay to two neutral pions would likely be suppressed.

Beam Spin Asymmetry in Semi-Inclusive Electroproduction of Hadron Pairs.

A first measurement of the longitudinal beam spin asymmetry A_{LU} in the semi-inclusive electroproduction of pairs of charged pions is reported. A_{LU} is a higher-twist observable and offers the cleanest access to the nucleon twist-3 parton distribution function e(x). Data have been collected in the Hall-B at Jefferson Lab by impinging a 5.

Extraction of Beam-Spin Asymmetries from the Hard Exclusive π^{+} Channel off Protons in a Wide Range of Kinematics.

We have measured beam-spin asymmetries to extract the sinϕ moment A_{LU}^{sinϕ} from the hard exclusive e[over →]p→e^{'}nπ^{+} reaction above the resonance region, for the first time with nearly full coverage from forward to backward angles in the center of mass. The A_{LU}^{sinϕ} moment has been measured up to 6.6  GeV^{2} in -t, covering the kinematic regimes of generalized parton distributions (GPD) and baryon-to-meson transition distribution amplitudes (TDA) at the same time.

Novel Way to Search for Light Dark Matter in Lepton Beam-Dump Experiments.

A novel mechanism to produce and detect light dark matter in experiments making use of GeV electrons (and positrons) impinging on a thick target (beam dump) is proposed. The positron-rich environment produced by the electromagnetic shower allows us to produce an A^{'} via nonresonant (e^{+}+e^{-}→γ+A^{'}) and resonant (e^{+}+e^{-}→A^{'}) annihilation on atomic electrons. The latter mechanism, for some selected kinematics, results in a larger sensitivity with respect to limits derived by the commonly used A^{'}-strahlung.

[Effectiveness and innocuousness of the association of calcium dobesilate, dexamethasone acetate and lidocaine versus prednisolone capronate with dibucaine clorohydrate in the treatment of hemorrhoids-].

The objective of the present study was to compare properties of two associations in the topical treatment of hemorrhoids. They were included 40 patient with diagnosis of internal hemorrhoids grade 1 or 2, which was indicated topic treatment after the realization of an interrogatory and anoscopy. The treatment received according to a randomized and double blind design: A = dobesilate of calcium with acetato of dexamethasone and lidocaine or B = Capronato of Prednisolone with Clorhidrato of dibucaina, applied twice a day.

[Primary immunoproliferative small intestinal disease].

We report two cases of Primary small Intestinal Lymphoma (IPSID), in adults. The clinical presentation was, watery diarrhea and weight loss. The histology of this cases was non-Hodgkin's Lymphoma, and the treatment was chemotherapy.

[Use of glucomannan dietary fiber in changes in intestinal habit].

It has been proven that fiber is effective in the treatment of multiple nosological entities, specially of the colonic pathology. In the present study, two dose of Glucomannan (3 gr/day and 4 gr/day) were evaluated within the modification of the intestinal habit and stool characteristics. 60 patients were included in a random, parallel, double blind, cross over trial study versus placebo.

[Hepatic tolerance of aceclofenac].

NSAID's are largely used drugs. Among the reported side effects of this type of drugs is liver damage. 73 patients suffering from diverse rheumatological pathologies (arthrosis 46.

[Percutaneous liver biopsy in outpatients].

We studied prospectively 44 patients with diffuse liver disease. We performed percutaneous liver biopsy in these outpatients. They were required to be in absolute response during the following 4-6 hours after the biopsy was completed.

[Retrograde endoscopic cholangiopancreatography. Incidence of bacteremia].

ERCP like all the endoscopic procedures, implies some risks of complications, between them, infections. Bacteremia may occur in any endoscopic and gastrointestinal procedure. The rate on ERCP is about 0 to 5.