Observation of WWγ Production and Search for Hγ Production in Proton-Proton Collisions at sqrt[s]=13 TeV

The observation of WWγ production in proton-proton collisions at a center-of-mass energy of 13 TeV with an integrated luminosity of 138  fb^{-1} is presented. The observed (expected) significance is 5.6 (5.1) standard deviations. Events are selected by requiring exactly two leptons (one electron and one muon) of opposite charge, moderate missing transverse momentum, and a photon. The measured fiducial cross section for WWγ is 5.9±0.8(stat)±0.8(syst)±0.7(modeling)  fb, in agreement with the next-to-leading order quantum chromodynamics prediction. The analysis is extended with a search for the associated production of the Higgs boson and a photon, which is generated by a coupling of the Higgs boson to light quarks. The result is used to constrain the Higgs boson couplings to light quarks.

New Structures in the J/ψJ/ψ Mass Spectrum in Proton-Proton Collisions at sqrt[s]=13 TeV

A search is reported for near-threshold structures in the J/ψJ/ψ invariant mass spectrum produced in proton-proton collisions at sqrt[s]=13  TeV from data collected by the CMS experiment, corresponding to an integrated luminosity of 135  fb^{-1}. Three structures are found, and a model with quantum interference among these structures provides a good description of the data. A new structure is observed with a local significance above 5 standard deviations at a mass of 6638_{-38}^{+43}(stat)_{-31}^{+16}(syst)  MeV. Another structure with even higher significance is found at a mass of 6847_{-28}^{+44}(stat)_{-20}^{+48}(syst)  MeV, which is consistent with the X(6900) resonance reported by the LHCb experiment and confirmed by the ATLAS experiment. Evidence for another new structure, with a local significance of 4.7 standard deviations, is found at a mass of 7134_{-25}^{+48}(stat)_{-15}^{+41}(syst)  MeV. Results are also reported for a model without interference, which does not fit the data as well and shows mass shifts up to 150 MeV relative to the model with interference.

Search for Scalar Leptoquarks Produced via τ-Lepton-Quark Scattering in pp Collisions at sqrt[s]=13 TeV

The first search for scalar leptoquarks produced in τ-lepton-quark collisions is presented. It is based on a set of proton-proton collision data recorded with the CMS detector at the LHC at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 138  fb^{-1}. The reconstructed final state consists of a jet, significant missing transverse momentum, and a τ lepton reconstructed through its hadronic or leptonic decays. Limits are set on the product of the leptoquark production cross section and branching fraction and interpreted as exclusions in the plane of the leptoquark mass and the leptoquark-τ-quark coupling strength.

Search for Inelastic Dark Matter in Events with Two Displaced Muons and Missing Transverse Momentum in Proton-Proton Collisions at sqrt[s]=13 TeV

A search for dark matter in events with a displaced nonresonant muon pair and missing transverse momentum is presented. The analysis is performed using an integrated luminosity of 138  fb^{-1} of proton-proton (pp) collision data at a center-of-mass energy of 13 TeV produced by the LHC in 2016-2018. No significant excess over the predicted backgrounds is observed. Upper limits are set on the product of the inelastic dark matter production cross section σ(pp→A^{'}→χ_{1}χ_{2}) and the decay branching fraction B(χ_{2}→χ_{1}μ^{+}μ^{-}), where A^{'} is a dark photon and χ_{1} and χ_{2} are states in the dark sector with near mass degeneracy. This is the first dedicated collider search for inelastic dark matter.

Luminosity determination using Z boson production at the CMS experiment

The measurement of Z boson production is presented as a method to determine the integrated luminosity of CMS data sets. The analysis uses proton-proton collision data, recorded by the CMS experiment at the CERN LHC in 2017 at a center-of-mass energy of 13Te V . Events with Z bosons decaying into a pair of muons are selected. The total number of Z bosons produced in a fiducial volume is determined, together with the identification efficiencies and correlations from the same data set, in small intervals of 20pb - 1 of integrated luminosity, thus facilitating the efficiency and rate measurement as a function of time and instantaneous luminosity. Using the ratio of the efficiency-corrected numbers of Z bosons, the precisely measured integrated luminosity of one data set is used to determine the luminosity of another. For the first time, a full quantitative uncertainty analysis of the use of Z  bosons for the integrated luminosity measurement is performed. The uncertainty in the extrapolation between two data sets, recorded in 2017 at low and high instantaneous luminosity, is less than 0.5%. We show that the Z boson rate measurement constitutes a precise method, complementary to traditional methods, with the potential to improve the measurement of the integrated luminosity.

Observation of the Rare Decay of the η Meson to Four Muons

A search for the rare η→μ^{+}μ^{-}μ^{+}μ^{-} double-Dalitz decay is performed using a sample of proton-proton collisions, collected by the CMS experiment at the CERN LHC with high-rate muon triggers during 2017 and 2018 and corresponding to an integrated luminosity of 101  fb^{-1}. A signal having a statistical significance well in excess of 5 standard deviations is observed. Using the η→μ^{+}μ^{-} decay as normalization, the branching fraction B(η→μ^{+}μ^{-}μ^{+}μ^{-})=[5.0±0.8(stat)±0.7(syst)±0.7(B_{2μ})]×10^{-9} is measured, where the last term is the uncertainty in the normalization channel branching fraction. This work achieves an improved precision of over 5 orders of magnitude compared to previous results, leading to the first measurement of this branching fraction, which is found to agree with theoretical predictions.

Selective inhibition of cyclooxygenase-2 (COX-2) reduces prostaglandin E2 production and attenuates systemic disease sequelae in experimental pancreatitis

BACKGROUND/AIMS

Prostaglandins and prostaglandin-derived mediators play an important role in mediating the systemic inflammatory response in acute pancreatitis. COX (cyclooxygenase) is the key enzyme of prostaglandin synthesis. Whereas COX-1 produces prostaglandin mediators for physiological reactions, COX-2 is overexpressed in acute pancreatitis. The aim of this study was to investigate whether a selective COX-2 inhibitor alters prostaglandin production and attenuates systemic disease sequelae in severe acute pancreatitis in rats.

METHODOLOGY

Severe acute pancreatitis was induced in 36 rats by standardized intraductal infusion of bile salt and intravenous cerulein infusion. Six hours after acute pancreatitis induction, rats were randomized to receive either no COX inhibition (saline), nonselective COX inhibition by indomethacin (3 mg/kg, i.v.) or selective COX-2 inhibition by NS-398 (10 mg/kg, i.v.). Serum concentrations of prostaglandin E2 were measured before and after acute pancreatitis induction and 24 hrs after starting therapy. Routine cardiorespiratory and renal parameters were monitored to assess organ function.

RESULTS

Animals treated with the selective COX-2 inhibitor had significantly lower prostaglandin E2 values (211 +/- 17 vs. 366 +/- 37 and 435 +/- 13 pg/mL), produced more urine (18 +/- 4 vs. 13 +/- 3 and 12 +/- 3 mL/6-24 h) and had significantly fewer episodes of respiratory distress (defined as a pO2 < 80 mmHg or pCO2 > 50 mmHg for > 15 min; 12 vs. 57 and 71%) during the observation period than animals without or with nonselective COX inhibition.

CONCLUSIONS

Selective inhibition of COX-2 reduces prostaglandin E2 serum levels in this model of acute pancreatitis. This together with improved renal and respiratory function suggests an attenuation of the systemic response to pancreatic injury. COX-2 inhibition may be another step toward optimizing therapy in severe acute pancreatitis.

[Diagnosis of acute appendicitis. Is physical examination enough to reach a surgical decision?]

In the large majority of cases, acute appendicitis can be diagnosed on the basis of the medical history and the patient's symptoms. Urine should be drawn from every patient for urinstix and bacteriological testing, as well as blood for a blood count, electrolytes and coagulation parameters. A US should be performed, in particular to exclude possible other diagnoses. Women should be examined by a gynecologist. Once the diagnosis has been established, the patient must be sent for surgery without delay. Should there be reason for doubt, further diagnostic measures (in particular CT) should be carried out as permitted by the urgency of the case. In life-threatening situations, laparoscopy should be done immediately, and preparations made for laparotomy should this be necessary. If the symptoms are such that a wait-and-see attitude is justified, continued observation and follow-up examinations are recommended. The diagnosis of acute appendicitis can be difficult, and every patient who rouses relevant suspicion, should be seen by a surgeon.