50175 research outputs found
Sort by
Search for a low-mass tau(-)tau(+) resonance in association with a bottom quark in proton-proton collisions at root s=13 TeV
No full textA general search is presented for a low-mass (-+) resonance produced in association with a bottom quark. The search is based on proton-proton collision data at a center-of-mass energy of 13 TeV collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 35.9 fb(-1). The data are consistent with the standard model expectation. Upper limits at 95% confidence level on the cross section times branching fraction are determined for two signal models: a light pseudoscalar Higgs boson decaying to a pair of leptons produced in association with bottom quarks, and a low-mass boson X decaying to a -lepton pair that is produced in the decay of a bottom-like quark B such that B bX. Masses between 25 and 70 GeV are probed for the light pseudoscalar boson with upper limits ranging from 250 to 44 pb. Upper limits from 20 to 0.3 pb are set on B masses between 170 and 450 GeV for X boson masses between 20 and 70 GeV
Control of Aerodynamic Drag and Heating of Nose Cones Through Taper Spikes
No full textThe present work numerically and experimentally investigates Mach 5.8 flow past passively modified nose cone configurations such as taper/stepped taper spiked, spherically blunted, and parabolic nose cones at a fineness ratio of 3.6 and zero angle of attack in order to determine the best passively modified geometry that provides the control of both the aerodynamic drag coefficient and surface heat flux. The velocity vectors show the flow directions/recirculation zones and so on at the root of the taper as well as stepped taper spikes, whereas the Mach number contours show the features of shock in front of the taper/stepped taper spikes as well as the nose tip of the taper/stepped taper spiked blunted and parabolic nose cones. The present study reveals that the ``stepped taper spiked parabolic nose cone'' configuration provides lowest aerodynamic drag coefficient and surface heat flux as compared with all the other nose cone configurations investigated. The modifications in the flow/shock features such as the conversion of strong curved shock into weaker oblique shock waves, flow deceleration, and so on, at the root of the spike due to backward-facing steps in ``stepped taper spiked parabolic nose cone'' may be the reason for achieving lower aerodynamic drag/heating
Search for a Light Charged Higgs Boson Decaying to a W Boson and a CP-Odd Higgs Boson in Final States with e mu mu or mu mu mu in Proton-Proton Collisions at root s=13 TeV
No full textA search for a light charged Higgs boson (H+) decaying to a W boson and a CP-odd Higgs boson (A) in final states with e mu mu or mu mu mu is performed using data from pp collisions at root s = 13 TeV, recorded by the CMS detector at the LHC and corresponding to an integrated luminosity of 35.9 fb(-1). In this search, it is assumed that the H+ boson is produced in decays of top quarks, and the A boson decays to two oppositely charged muons. The presence of signals for H+ boson masses between 100 and 160 GeV and A boson masses between 15 and 75 GeV is investigated. No evidence for the production of the H+ boson is found. Upper limits at 95% confidence level are obtained on the combined branching fraction for the decay chain, t -> bH(+) -> bW(+)A -> bW(+)mu(+)mu(-), of 1.9 x 10(-6) to 8.6 x 10(-6), depending on the masses of the H+ and A bosons. These are the first limits for these decay modes of the H+ and A bosons
Search for new physics in top quark production in dilepton final states in proton-proton collisions at root s=13 TeV
No full textA search for new physics in top quark production is performed in proton-proton collisions at 13 TeV. The data set corresponds to an integrated luminosity of 35.9 fb(-1) collected in 2016 with the CMS detector. Events with two opposite-sign isolated leptons (electrons or muons), and b quark jets in the final state are selected. The search is sensitive to new physics in top quark pair production and in single top quark production in association with a W boson. No significant deviation from the standard model expectation is observed. Results are interpreted in the framework of effective field theory and constraints on the relevant effective couplings are set, one at a time, using a dedicated multivariate analysis. This analysis differs from previous searches for new physics in the top quark sector by explicitly separating tW from t (t) over bar events and exploiting the specific sensitivity of the tW process to new physics
Conducting LaVO3/SrTiO3 Interface: Is Cationic Stoichiometry Mandatory?
No full textThe origin of the conductivity at the interface of two insulating perovskite oxides is a matter of intensive studies. The conductivity generated at the interface of insulating LaVO3 (LVO) and SrTiO3 (STO) is explained in terms of polar catastrophe. Here, the authors grown LVO films on (001) TiO2-terminated STO substrate employing pulsed laser deposition technique and demonstrate a transition from conducting to insulating interface by changing the La-stoichiometry by only 1%, whereby such transition takes place for La-deficient films. The effect of cation (non)stoichiometry of LVO film on both carrier density and mobility is studied and compared with previously reported LaAlO3-STO interface. This observation suggests a revisit to the explanation of possible origin of such conductivity beyond the polar catastrophe scenario and can be instrumental in search for novel conducting interfaces
Measurement of the average very forward energy as a function of the track multiplicity at central pseudorapidities in proton-proton collisions at root s=13 TeV
No full textThe average total energy as well as its hadronic and electromagnetic components are measured with the CMS detector at pseudorapidities -6.6 < eta < -5.2 in proton-proton collisions at a centre-of-mass energy root s = 13 TeV. The results are presented as a function of the charged particle multiplicity in the region vertical bar eta vertical bar < 2. This measurement is sensitive to correlations induced by the underlying event structure over a very wide pseudorapidity region. The predictions of Monte Carlo event generators commonly used in collider experiments and ultra-high energy cosmic ray physics are compared to the data. All generators considered overestimate the fraction of energy going into hadrons
Hormonal regulation and function of an RNA helicase, Ddx5 in corpus luteum of adult Wistar rats
No full textCorpus luteum (CL) is an endocrine tissue involved in regulation of reproductive cycle and early pregnancy establishment. In the present study DEAD-box helicase-5 (Ddx5), a member of the DEAD box family of RNA helicases was investigated for its expression, regulation and function in CL of Wistar rats. Ddx5 was expressed in adult rat CL. Primary cell culture from supra-ovulated ovaries were established for in vitro studies. Addition of luteinizing hormone (LH; 100 ng/ml), a luteotrophic factor in primary cell culture, decreased Ddx5 RNA expression (foldchange:0.6 +/- 0.075) while prostaglandin alpha (PGF(2 alpha); 1 mu M), a luteolytic factor caused an increase (foldchange:2.4 +/- 0.4) compared to control group. Under in vivo conditions, the administration of PGF(2 alpha) or gonadotropin-releasing hormone antagonist; cetrorelix (CET) caused luteolysis as well as an increase in the protein level of Ddx5 (foldchange:1.9 +/- 0.27 and 1.4 +/- 0.09 viz.; p < 0.05) in CL of adult rats. LH was administered post CET treatment which suppressed Ddx5 protein expression (foldchange:0.8 +/- 0.16; p < 0.05) compared to CET treated group. Further, it was observed that the expression of Ddx5 was upregulated (fold-change:1.5 +/- 0.23; p < 0.05) in CL during late pregnancy compared to mid pregnancy concomitant to luteolysis in adult rats. Overall, the results suggest for the first time that Ddx5 is expressed in rat CL and regulated by luteolytic and luteotrophic factors in an inverse fashion. Further, the data significantly correlates ddx5 expression to CL regression suggesting involvement of ddx5 in luteolysis. These results suggest a significant role of Ddx5 in female reproduction biology and warrant in depth examination of the function of Ddx5 in CL
Constraints on anomalous HVV couplings from the production of Higgs bosons decaying to tau lepton pairs
No full textA study is presented of anomalous HVV interactions of the Higgs boson, including its CP properties. The study uses Higgs boson candidates produced mainly in vector boson fusion and gluon fusion that subsequently decay to a pair of tau leptons. The data were recorded by the CMS experiment at the LHC in 2016 at a center-of-mass energy of 13 TeV and correspond to an integrated luminosity of 35.9 fb(-1). A matrix element technique is employed for the analysis of anomalous interactions. The results are combined with those from the H -> 4l decay channel presented earlier, yielding the most stringent constraints on anomalous Higgs boson couplings to electroweak vector bosons expressed as effective cross section fractions and phases: the CP-violating parameter f(a3) cos(phi(a3)) = (0.00 +/- 0.27) x 10(-3) and the CP-conserving parameters f(a2) cos(phi(a2)) = (0.08)(-0.21)(+1.04)) x 10(-3), f(Lambda 1) cos(phi(Lambda 1)) = (0.00)(-0.09)(+0.53)) x 10(-3), and f(Lambda 1)(Z gamma) cos(phi(Z gamma)(Lambda 1)) = (0.0(-1.3)(+1.1)) x 10(-3). The current dataset does not allow for precise constraints on CP properties in the gluon fusion process. The results are consistent with standard model expectations
The TCP4 Transcription Factor Directly Activates TRICHOMELESS1 and 2 and Suppresses Trichome Initiation(1)(OPEN])
No full textTrichomes are the first line of defense on the outer surface of plants against biotic and abiotic stresses. Because trichomes on leaf surfaces originate from the common epidermal progenitor cells that also give rise to pavement cells and stomata, their density and distribution are under strict genetic control. Regulators of trichome initiation have been identified and incorporated into a biochemical pathway wherein an initiator complex promotes trichome fate in an epidermal progenitor cell, while an inhibitor complex suppresses it in the neighboring cells. However, it is unclear how these regulator proteins, especially the negative regulators, are induced by upstream transcription factors and integrated with leaf morphogenesis. Here, we show that the Arabidopsis (Arabidopsis thaliana) class II TCP proteins activate TRICHOMELESS1 (TCL1) and TCL2, the two established negative regulators of trichome initiation, and reduce trichome density on leaves. Loss-of-function of these TCP proteins increased trichome density whereas TCP4 gain-of-function reduced trichome number. TCP4 binds to the upstream regulatory elements of both TCL1 and TCL2 and directly promotes their transcription. Further, the TCP-induced trichome suppression is independent of the SQUAMOSA PROMOTER BINDING PROTEIN LIKE family of transcription factors, proteins that also reduce trichome density at later stages of plant development. Our work demonstrates that the class II TCP proteins couple leaf morphogenesis with epidermal cell fate determination
Room temperature multiferroic properties of hexagonal Lu0.85Sr0.15FeO3 ceramics
No full textThe structural, electric and magnetic properties of bulk hexagonal Lu1-xSr x FeO3 (x = 0 and 0.15) ceramics are investigated. XRD data and rietveld refinement confirm the hexagonal structure with P63cm space group. Magnetic measurements for Sr-doped sample indicate a ferromagnetic-like behavior at the room temperature with a very high coercivity of the order of � 4.4 kOe. P-E hysteresis loops show an enhanced ferroelectric property with Sr doping. Hence, towards the realization of applications, the multiferroic properties of hexagonal LuFeO3 are improved remarkably by 15 Sr substitution at Lu site