Search for magnetic monopoles produced via the Schwinger mechanism.

Electrically charged particles can be created by the decay of strong enough electric fields, a phenomenon known as the Schwinger mechanism1. By electromagnetic duality, a sufficiently strong magnetic field would similarly produce magnetic monopoles, if they exist2. Magnetic monopoles are hypothetical fundamental particles that are predicted by several theories beyond the standard model3-7 but have never been experimentally detected. Searching for the existence of magnetic monopoles via the Schwinger mechanism has not yet been attempted, but it is advantageous, owing to the possibility of calculating its rate through semi-classical techniques without perturbation theory, as well as that the production of the magnetic monopoles should be enhanced by their finite size8,9 and strong coupling to photons2,10. Here we present a search for magnetic monopole production by the Schwinger mechanism in Pb-Pb heavy ion collisions at the Large Hadron Collider, producing the strongest known magnetic fields in the current Universe11. It was conducted by the MoEDAL experiment, whose trapping detectors were exposed to 0.235 per nanobarn, or approximately 1.8 × 109, of Pb-Pb collisions with 5.02-teraelectronvolt center-of-mass energy per collision in November 2018. A superconducting quantum interference device (SQUID) magnetometer scanned the trapping detectors of MoEDAL for the presence of magnetic charge, which would induce a persistent current in the SQUID. Magnetic monopoles with integer Dirac charges of 1, 2 and 3 and masses up to 75 gigaelectronvolts per speed of light squared were excluded by the analysis at the 95% confidence level. This provides a lower mass limit for finite-size magnetic monopoles from a collider search and greatly extends previous mass bounds.

First Search for Dyons with the Full MoEDAL Trapping Detector in 13 TeV pp Collisions.

The MoEDAL trapping detector consists of approximately 800 kg of aluminum volumes. It was exposed during run 2 of the LHC program to 6.46 fb^{-1} of 13 TeV proton-proton collisions at the LHCb interaction point. Evidence for dyons (particles with electric and magnetic charge) captured in the trapping detector was sought by passing the aluminum volumes comprising the detector through a superconducting quantum interference device (SQUID) magnetometer. The presence of a trapped dyon would be signaled by a persistent current induced in the SQUID magnetometer. On the basis of a Drell-Yan production model, we exclude dyons with a magnetic charge ranging up to five Dirac charges (5g_{D}) and an electric charge up to 200 times the fundamental electric charge for mass limits in the range 870-3120 GeV and also monopoles with magnetic charge up to and including 5g_{D} with mass limits in the range 870-2040 GeV.

Magnetic Monopole Search with the Full MoEDAL Trapping Detector in 13 TeV pp Collisions Interpreted in Photon-Fusion and Drell-Yan Production.

MoEDAL is designed to identify new physics in the form of stable or pseudostable highly ionizing particles produced in high-energy Large Hadron Collider (LHC) collisions. Here we update our previous search for magnetic monopoles in Run 2 using the full trapping detector with almost four times more material and almost twice more integrated luminosity. For the first time at the LHC, the data were interpreted in terms of photon-fusion monopole direct production in addition to the Drell-Yan-like mechanism. The MoEDAL trapping detector, consisting of 794 kg of aluminum samples installed in the forward and lateral regions, was exposed to 4.0 fb^{-1} of 13 TeV proton-proton collisions at the LHCb interaction point and analyzed by searching for induced persistent currents after passage through a superconducting magnetometer. Magnetic charges equal to or above the Dirac charge are excluded in all samples. Monopole spins 0, ½, and 1 are considered and both velocity-independent and-dependent couplings are assumed. This search provides the best current laboratory constraints for monopoles with magnetic charges ranging from two to five times the Dirac charge.

Novel type of CPT violation for correlated Einstein-Podolsky-Rosen states of neutral mesons.

We discuss modifications to the concept of an "antiparticle," induced by a breakdown of the CPT symmetry at a fundamental level, realized within an extended class of quantum gravity models. The resulting loss of particle-antiparticle identity in the neutral-meson system induces a breaking of the Einstein-Podolsky-Rosen correlation imposed by Bose statistics. This is parametrized by a complex parameter associated with the contamination by the "wrong symmetry" state. The physical consequences are studied, and novel observables of CPT violation in phi factories are proposed.

Observability of the neutrino charge radius.

It is shown that the probe-independent charge radius of the neutrino is a physical observable; as such, it may be extracted from experiment, at least in principle. This is accomplished by expressing a set of experimental nu(mu)-e cross sections in terms of the finite charge radius and two additional gauge- and renormalization-group-invariant quantities, corresponding to the electroweak effective charge and mixing angle.

The pinch technique at two loops

It is shown that the fundamental properties of gauge independence, gauge invariance, unitarity, and analyticity of the S matrix lead to the unambiguous generalization of the pinch technique algorithm to two loops.

Differences in adherence to buccal epithelial cells, in phagocytosis and in killing by neutrophils between human and non-human strains of Candida albicans.

The adherence of strains of Candida albicans to buccal epithelial cells as well as the phagocytosis of these organisms by human polymorphonuclear leucocytes (PMNL) was studied. The strains of C. albicans were obtained from patients' urine. from bird faeces and from soil. The strains of C. albicans obtained from patients and the environment displayed greater adhering ability (23.8 +/- 6.4 and 27.5 +/- 5.2 respectively) than the avian strains (14.4 +/- 2.2) (P < 0.01). Strains obtained from the environment were resistant to phagocytosis (81.6 +/- 0.2 organisms ingested per 200 PMNL) and killing (8.4 +/- 2.6%) by PMNL as compared to human and avian strains (P < 0.01). These observations indicate that environmental strains of C. albicans may be more virulent for human beings.

Polymorphonuclear leukocyte functions and multiple sclerosis.

We tested peripheral blood from 60 patients with definite multiple sclerosis (MS) and 60 healthy controls for polymorphonuclear leukocyte (PMNL) functions and found significant disorders in adherence (9.07% +/- 8.18% for patients versus 28.97% +/- 5.76% for controls), chemotaxis (18.32 +/- 3.1 for patients versus 30.49 +/- 4.52 for controls), phagocytosis (73.6 +/- 25.25 for patients versus 111.2 +/- 25.7 for controls), and bactericidal action (10.35% +/- 5% for patients versus 25.09% +/- 4.82% for controls). All differences were significant (p < 0.001). We confirmed the results by retesting 3 to 8 months later. The depressed PMNL functions in MS patients may explain their increased susceptibility to infections of the respiratory, digestive, and urinary tracts.

Adherence of Candida albicans to epithelial cells from normal and cancerous urinary bladders.

Patients with malignancies are at high risk to develop infections by Candida albicans. We have compared the adherence of C. albicans isolated from urine cultures to bladder epithelial cells obtained from healthy volunteers and patients with cancer of the bladder. The mean number of C. albicans adhering per epithelial cell from areas infiltrated from cancer was significantly higher as compared to cells obtained from intact areas of cancerous bladders and from normal bladders. The increased adherence of C. albicans to cancerous epithelial cells suggests that malignancies are associated with alterations of the epithelial cell surface which render the cells more susceptible to colonization by C. albicans. The increased colonization may predispose these patients to C. albicans infections.