A search for long-lived particles (LLPs) produced in decays of standard model (SM) Higgs bosons is presented. The data sample consists of 137 fb^{-1} of proton-proton collisions at sqrt[s]=13 TeV, recorded at the LHC in 2016-2018. A novel technique is employed to reconstruct decays of LLPs in the end cap muon detectors. The search is sensitive to a broad range of LLP decay modes and to masses as low as a few GeV. No excess of events above the SM background is observed. The most stringent limits to date on the branching fraction of the Higgs boson to LLPs subsequently decaying to quarks and τ^{+}τ^{-} are found for proper decay lengths greater than 6, 20, and 40 m, for LLP masses of 7, 15, and 40 GeV, respectively.
The dependence of the ratio between the B_{s}^{0} and B^{+} hadron production fractions, f_{s}/f_{u}, on the transverse momentum (p_{T}) and rapidity of the B mesons is studied using the decay channels B_{s}^{0}→J/ψϕ and B^{+}→J/ψK^{+}. The analysis uses a data sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the CMS experiment in 2018 and corresponding to an integrated luminosity of 61.6 fb^{-1}. The f_{s}/f_{u} ratio is observed to depend on the B p_{T} and to be consistent with becoming asymptotically constant at large p_{T}. No rapidity dependence is observed. The ratio of the B^{0} to B^{+} meson production fractions, f_{d}/f_{u}, is also measured, for the first time in proton-proton collisions, using the B^{0}→J/ψK^{*0} decay channel. The result is found to be within 1 standard deviation of unity and independent of p_{T} and rapidity, as expected from isospin invariance.
We present an observation of photon-photon production of τ lepton pairs in ultraperipheral lead-lead collisions. The measurement is based on a data sample with an integrated luminosity of 404 μb^{-1} collected by the CMS experiment at a center-of-mass energy per nucleon pair of sqrt[s_{NN}]=5.02 TeV. The γγ→τ^{+}τ^{-} process is observed for τ^{+}τ^{-} events with a muon and three charged hadrons in the final state. The measured fiducial cross section is σ(γγ→τ^{+}τ^{-})=4.8±0.6(stat)±0.5(syst) μb, where the second (third) term corresponds to the statistical (systematic) uncertainty in σ(γγ→τ^{+}τ^{-}) in agreement with leading-order QED predictions. Using σ(γγ→τ^{+}τ^{-}), we estimate a model-dependent value of the anomalous magnetic moment of the τ lepton of a_{τ}=0.001_{-0.089}^{+0.055}.
The first search exploiting the vector boson fusion process to probe heavy Majorana neutrinos and the Weinberg operator at the LHC is presented. The search is performed in the same-sign dimuon final state using a proton-proton collision dataset recorded at sqrt[s]=13 TeV, collected with the CMS detector and corresponding to a total integrated luminosity of 138 fb^{-1}. The results are found to agree with the predictions of the standard model. For heavy Majorana neutrinos, constraints on the squared mixing element between the muon and the heavy neutrino are derived in the heavy neutrino mass range 50 GeV-25 TeV; for masses above 650 GeV these are the most stringent constraints from searches at the LHC to date. A first test of the Weinberg operator at colliders provides an observed upper limit at 95% confidence level on the effective μμ Majorana neutrino mass of 10.8 GeV.
A search for the standard model Higgs boson decaying to a charm quark-antiquark pair, H→cc[over ¯], produced in association with a leptonically decaying V (W or Z) boson is presented. The search is performed with proton-proton collisions at sqrt[s]=13 TeV collected by the CMS experiment, corresponding to an integrated luminosity of 138 fb^{-1}. Novel charm jet identification and analysis methods using machine learning techniques are employed. The analysis is validated by searching for Z→cc[over ¯] in VZ events, leading to its first observation at a hadron collider with a significance of 5.7 standard deviations. The observed (expected) upper limit on σ(VH)B(H→cc[over ¯]) is 0.94 (0.50_{-0.15}^{+0.22})pb at 95% confidence level (C.L.), corresponding to 14 (7.6_{-2.3}^{+3.4}) times the standard model prediction. For the Higgs-charm Yukawa coupling modifier, κ_{c}, the observed (expected) 95% C.L. interval is 1.1c}|<5.5 (|κ_{c}|<3.4), the most stringent constraint to date.
A search for nonresonant Higgs boson (H) pair production via gluon and vector boson (V) fusion is performed in the four-bottom-quark final state, using proton-proton collision data at 13 TeV corresponding to 138 fb^{-1} collected by the CMS experiment at the LHC. The analysis targets Lorentz-boosted H pairs identified using a graph neural network. It constrains the strengths relative to the standard model of the H self-coupling and the quartic VVHH couplings, κ_{2V}, excluding κ_{2V}=0 for the first time, with a significance of 6.3 standard deviations when other H couplings are fixed to their standard model values.
A search for the standard model (SM) Higgs boson (H) produced with transverse momentum (p_{T}) greater than 450 GeV and decaying to a charm quark-antiquark (cc[over ¯]) pair is presented. The search is performed using proton-proton collision data collected at sqrt[s]=13 TeV by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138 fb^{-1}. Boosted H→cc[over ¯] decay products are reconstructed as a single large-radius jet and identified using a deep neural network charm tagging technique. The method is validated by measuring the Z→cc[over ¯] decay process, which is observed in association with jets at high p_{T} for the first time with a signal strength of 1.00_{-0.14}^{+0.17}(syst)±0.08(theo)±0.06(stat), defined as the ratio of the observed process rate to the SM expectation. The observed (expected) upper limit on σ(H)B(H→cc[over ¯]) is set at 47 (39) times the SM prediction at 95% confidence level.
We present the first direct search for exotic Higgs boson decays H→AA, A→γγ in events with two photonlike objects. The hypothetical particle A is a low-mass spin-0 particle decaying promptly to a merged diphoton reconstructed as a single photonlike object. We analyze the data collected by the CMS experiment at sqrt[s]=13 TeV corresponding to an integrated luminosity of 136 fb^{-1}. No excess above the estimated background is found. We set upper limits on the branching fraction B(H→AA→4γ) of (0.9-3.3)×10^{-3} at 95% confidence level for masses of A in the range 0.1-1.2 GeV.
The first observation of the production of W^{±}W^{±} bosons from double parton scattering processes using same-sign electron-muon and dimuon events in proton-proton collisions is reported. The data sample corresponds to an integrated luminosity of 138 fb^{-1} recorded at a center-of-mass energy of 13 TeV using the CMS detector at the CERN LHC. Multivariate discriminants are used to distinguish the signal process from the main backgrounds. A binned maximum likelihood fit is performed to extract the signal cross section. The measured cross section for production of same-sign W bosons decaying leptonically is 80.7±11.2(stat) _{-8.6}^{+9.5}(syst)±12.1(model) fb, whereas the measured fiducial cross section is 6.28±0.81(stat)±0.69(syst)±0.37(model) fb. The observed significance of the signal is 6.2 standard deviations above the background-only hypothesis.
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.
The first evidence for the Higgs boson decay to a Z boson and a photon is presented, with a statistical significance of 3.4 standard deviations. The result is derived from a combined analysis of the searches performed by the ATLAS and CMS Collaborations with proton-proton collision datasets collected at the CERN Large Hadron Collider (LHC) from 2015 to 2018. These correspond to integrated luminosities of around 140 fb^{-1} for each experiment, at a center-of-mass energy of 13 TeV. The measured signal yield is 2.2±0.7 times the standard model prediction, and agrees with the theoretical expectation within 1.9 standard deviations.
Quasireal photons exchanged in relativistic heavy ion interactions are powerful probes of the gluonic structure of nuclei. The coherent J/ψ photoproduction cross section in ultraperipheral lead-lead collisions is measured as a function of photon-nucleus center-of-mass energies per nucleon (W_{γN}^{Pb}) over a wide range of 40
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.
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.
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.
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.
Mango (Mangifera indica L.) is grown on approximately 20,000 ha in Taiwan. It is an economically important crop and the income of many fruit farmers comes primarily from mango production. During 2006 and 2007, a stem-end rot disease was observed 1 week after harvest on 28 to 36% of stored mangoes picked from six orchards in the Pingtung, Tainan, and Kaoshiung regions. Two popular mango cultivars, Keitt and Irwin, showed greater susceptibility to this disease, while 'Haden' was found to be moderately susceptible. In storage, symptoms initially appeared as light-to-dark brown lesions surrounding peduncles. Rot symptoms advanced slowly but eventually penetrated the mesocarp, which consequently reduced the commercial value of fruits. The fungus formed abundant pycnidia (0.1 to 0.6 mm in diameter) on infected fruits in advanced stages of symptom development. Pieces of symptomatic fruits plated on acidified potato dextrose agar (PDA) and incubated at 25 ± 1°C consistently yielded the same fungus. A single conidial isolate was cultured. Pycnidia developed on PDA after continuous exposure to light for 9 to 14 days. On the basis of morphological characteristics, the fungus was identified as Phomopsis mangiferae L. (2,3). Pycnidia released two types of conidia: α-conidia (5 to 10 × 2.3 to 4.0 μm) were hyaline and oval to fusoid; and β-conidia (15.0 to 37.5 × 1.3 to 2.5 μm) were hyaline and filiform with characteristic curves. Conidiophores were hyaline, filiform, simple or branched, septate, and 15 to 75 μm long. Cultures incubated under continuous fluorescent light (185 ± 35 μE·m-2·s-1) at 25°C for 3 days were used as inoculum for pathogenicity tests. Five fruits from 'Keitt' were wounded with a sterilized scalpel and each wound (2 × 2 × 2 mm) was inoculated with either a 5-mm mycelium agar plug or a 0.5-ml spore suspension (105 conidia per ml) of the fungus. Five wounded fruits inoculated with 5-mm PDA plugs or sterile water alone served as controls. Inoculated areas were covered with moist, sterile cotton. Fruits were enclosed in plastic bags and incubated at 24°C for 3 days. The test was performed three times. The same symptoms were observed on all inoculated fruits, whereas no decay was observed on control fruits. Reisolations from the inoculated fruits consistently yielded P. mangiferae, thus fulfilling Koch's postulates. This disease has previously been reported in Australia, Brazil, China, Cuba, India, Malaysia, and the United States (1). To our knowledge, this is the first report of P. mangiferae causing stem-end rot disease on mangoes in Taiwan. Our report necessitates taking preventive strategies in the field, prior to or after harvest, to contain postharvest losses in mangoes. References: (1) G. I. Johnson. Page 39 in: Compendium of Tropical Fruit Diseases. R. C. Ploetz et al., eds. The American Phytopathological Society. St. Paul, MN, 1994. (2) R. C. Ploetz, ed. Page 354 in: Diseases of Tropical Fruit Crops. CABI Publishing. Wallingford, UK, 2003. (3) E. Punithalingam. No. 1168 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1993.
In March 2005, a fruit rot disease was found in several commercial strawberry (Fragaria × ananassa Duchesne) fields at Fongyuan, 24.25°N, 120.72°E, in Taichung County in central Taiwan. The disease was rare and was negligible in most cultivated areas. However, disease incidence has increased by 4 to 5% over the last 2 years and causes significant postharvest losses. In storage, symptoms on berries include light brown-to-black, sunken, irregularly shaped lesions. The lesions gradually enlarge and become firm with a dark green-to-black, velvety surface composed of mycelia, conidiophores, and conidia. Twelve single conidial isolates (AF-1 to AF-12) of a fungus were isolated by placing portions of symptomatic fruit from four locations onto acidified potato dextrose agar (PDA) and incubating at 24 ± 1°C. One isolate from each of the four locations, AF-2, 6, 9, and 12, was selected for identification and pathogenicity studies. The fungus was identified as an Alternaria sp. according to the morphological descriptions of A. tenuissima (2,3). Conidiophores were simple or branched, straight or flexuous, septate, pale to light brown, 3.0 to 5.0 μm in diameter, and bore two to six conidia in a chain. Conidia were dark brown, obclavate or oval, and multicellular with seven transverse (in most cases) and numerous longitudinal septa. Conidia were 15.5 to 56.5 μm (average 35.0 μm) long × 6.0 to 15.0 μm (average 11.0 μm) wide at the broadest point. The pathogen was consistently isolated from berries in the field or in storage. Pathogenicity tests were conducted by inoculating 12 surface-sterilized berries with each of the four isolates. Approximately 300 μl of a spore suspension (2 × 105 conidia per ml) was placed at two points on the uninjured surface of each fruit and allowed to dry for 5 min. Control fruits were treated with sterile water. The berries were then enclosed in a plastic bag and incubated at 24 ± 1°C for 2 days. Disease symptoms similar to those described above were observed on 95% of inoculated berries 3 days after inoculation, while no symptoms developed in control berries. Reisolation from the inoculated berries consistently yielded the Alternaria sp. described above. Pathogenicity tests were performed three times. Previously, strawberry fruit rot caused by A. tenuissima was reported from Florida (2) and Malaysia (1), however, to our knowledge, this is the first report of fruit rot of strawberry caused by a species of Alternaria in Taiwan. References: (1) W. D. Cho et al. List of Plant Diseases in Korea. Korean Society of Plant Pathology, 2004. (2) C. M. Howard and E. E. Albregts. Phytopathology 63:938, 1973. (3) R. D. Milholland. Phytopathology 63:1395, 1973.
During March 2007, a fruit rot disease was observed in several loquat (Eriobotrya japonica (Thunberg) Lindley) fields located in Taichung, Nantou, and Miaoli counties. Loquat is a valuable fruit crop grown predominantly in central Taiwan, and hence, even a minor yield loss by this new disease is economically significant. Symptoms on fruits initially appeared as small lesions (<1 mm) that later developed into light-to-dark brown, circular, larger (7 mm), sunken lesions, indicating invasion of a pathogen into the fruit. Pieces of rotted fruit tissue (1 × 1 × 1 mm) were immersed for 1 min in 3% commercial bleach, followed by 70% ethanol, cultured on potato dextrose agar (PDA), and incubated under constant fluorescent light (185 ± 35 μE·m-2·s-1) at 24°C for 2 days. Three single conidial isolates (AS1 to AS3) were selected and used in morphological and pathogenicity studies. All three isolates were identified as an Alternaria sp. (1-3) and formed abundant, dark brown mycelium when cultured on PDA with light at 24°C. Conidiophores were 60 to 89 × 3 to 5 μm, densely fasciculate, cylindrical, simple or branched, and had distinct conidial scars. Conidia were 12 to 74 × 6 to 14 μm, golden brown, straight or curved, obclavate with beaks measuring half the length of the conidium, and observed in chains of 10 or more spores with four to seven transverse septa and several longitudinal septa. Pathogenicity tests were conducted twice by inoculating eight surface-sterilized wounded or unwounded fruits with each of the three isolates in each experiment. Two cuts (1 × 1 × 1 mm) were made on each fruit 3 cm apart with a sterile scalpel, and a 300-μl spore suspension (2 × 105 conidia per ml) was placed on each wound. Similarly, a 300-μl spore suspension was placed on unwounded fruits and air dried for 5 min. Control fruits were similarly treated with sterile water. Inoculated fruits were enclosed in a plastic bag and kept at 24 ± 1°C. Symptoms of soft rot were observed on 60% (unwounded) and 100% (wounded) of inoculated fruits 5 days after inoculation, while control fruits did not develop disease symptoms. Reisolation from the symptomatic fruits consistently yielded an Alternaria sp. This fungus previously has been reported as the causal agent of fruit rot or black spot of papaya, mango, kiwifruit, pear, and carambola from Australia, India, Malaysia, South Africa, and the United States (1-3). To our knowledge, this is the first report of fruit rot of loquat caused by an Alternaria sp. in Taiwan. To manage this disease, growers may resort to fungicidal sprays followed by bagging of fruits to reduce pre- and postharvest losses. References: (1) A. L. Jones and H. S. Aldwinckle. Compendium of Apple and Pear Diseases. The American Phytopathological Society. St. Paul, MN, 1990. (2) R. C. Ploetz. Diseases of Tropical Fruit Crops. CABI Publishing. Wallingford, Oxfordshire, UK, 2003. (3) R. C. Ploetz et al. Compendium of Tropical Fruit Diseases. The American Phytopathological Society. St. Paul, MN, 1994.
Cardiomegaly is the main imaging finding for canine heart diseases. There are many advances in the field of medical diagnosing based on imaging with deep learning for human being. However there are also increasing realization of the potential of using deep learning in veterinary medicine. We reported a clinically applicable assisted platform for diagnosing the canine cardiomegaly with deep learning. VHS (vertebral heart score) is a measuring method used for the heart size of a dog. The concrete value of VHS is calculated with the relative position of 16 key points detected by the system, and this result is then combined with VHS reference range of all dog breeds to assist in the evaluation of the canine cardiomegaly. We adopted HRNet (high resolution network) to detect 16 key points (12 and four key points located on vertebra and heart respectively) in 2274 lateral X-ray images (training and validation datasets) of dogs, the model was then used to detect the key points in external testing dataset (396 images), the AP (average performance) for key point detection reach 86.4 %. Then we applied an additional post processing procedure to correct the output of HRNets so that the AP reaches 90.9 %. This result signifies that this system can effectively assist the evaluation of canine cardiomegaly in a real clinical scenario.