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Abstract We report on a long-lasting, elevated gamma-ray flux state from VER J0521+211 observed by VERITAS, MAGIC, and Fermi-LAT in 2013 and 2014. The peak integral flux above 200 GeV measured with the nightly binned light curve is (8.8 ± 0.4) × 10 −7 photons m −2 s −1 , or ∼37% of the Crab Nebula flux. Multiwavelength observations from X-ray, UV, and optical instruments are also presented. A moderate correlation between the X-ray and TeV gamma-ray fluxes was observed, and the X-ray spectrum appeared harder when the flux was higher. Using the gamma-ray spectrum and four models of the extragalactic background light (EBL), a conservative 95% confidence upper limit on the redshift of the source was found to be z ≤ 0.31. Unlike the gamma-ray and X-ray bands, the optical flux did not increase significantly during the studied period compared to the archival low-state flux. The spectral variability from optical to X-ray bands suggests that the synchrotron peak of the spectral energy distribution (SED) may become broader during flaring states, which can be adequately described with a one-zone synchrotron self-Compton model varying the high-energy end of the underlying particle spectrum. The synchrotron peak frequency of the SED and the radio morphology of the jet from the MOJAVE program are consistent with the source being an intermediate-frequency-peaked BL Lac object. 

Abstract The exclusive photoproduction of $$\mathrm {\Upsilon }\mathrm {(nS)} $$ Υ ( nS ) meson states from protons, $$\gamma \mathrm {p} \rightarrow \mathrm {\Upsilon }\mathrm {(nS)} \,\mathrm {p}$$ γ p → Υ ( nS ) p (with $$\mathrm {n}=1,2,3$$ n = 1 , 2 , 3 ), is studied in ultraperipheral $$\mathrm {p}$$ p Pb collisions at a centre-of-mass energy per nucleon pair of $$\sqrt{\smash [b]{s_{_{\mathrm {NN}}}}} = 5.02\,\text {TeV} $$ s NN = 5.02 TeV . The measurement is performed using the $$\mathrm {\Upsilon }\mathrm {(nS)} \rightarrow \mu ^+\mu ^-$$ Υ ( nS ) → μ + μ - decay mode, with data collected by the CMS experiment corresponding to an integrated luminosity of 32.6 $$\,\text {nb}^{-1}$$ nb - 1 . Differential cross sections as functions of the $$\mathrm {\Upsilon }\mathrm {(nS)} $$ Υ ( nS ) transverse momentum squared $$p_{\mathrm {T}} ^2$$ p T 2 , and rapidity y , are presented. The $$\mathrm {\Upsilon (1S)}$$ Υ ( 1 S ) photoproduction cross section is extracted in the rapidity range $$|y |< 2.2$$ | y | < 2.2 , which corresponds to photon–proton centre-of-mass energies in the range $$91 more » « less

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Abstract The mass of the top quark is measured using a sample of $${{\text {t}}\overline{{\text {t}}}}$$ t t ¯ events collected by the CMS detector using proton-proton collisions at $$\sqrt{s}=13$$ s = 13 $$\,\text {TeV}$$ TeV at the CERN LHC. Events are selected with one isolated muon or electron and at least four jets from data corresponding to an integrated luminosity of 35.9 $$\,\text {fb}^{-1}$$ fb - 1 . For each event the mass is reconstructed from a kinematic fit of the decay products to a $${{\text {t}}\overline{{\text {t}}}}$$ t t ¯ hypothesis. Using the ideogram method, the top quark mass is determined simultaneously with an overall jet energy scale factor (JSF), constrained by the mass of the W boson in $${\text {q}} \overline{{\text {q}}} ^\prime $$ q q ¯ ′ decays. The measurement is calibrated on samples simulated at next-to-leading order matched to a leading-order parton shower. The top quark mass is found to be $$172.25 \pm 0.08\,\text {(stat+JSF)} \pm 0.62\,\text {(syst)} \,\text {GeV} $$ 172.25 ± 0.08 (stat+JSF) ± 0.62 (syst) GeV . The dependence of this result on the kinematic properties of the event is studied and compared to predictions of different models of $${{\text {t}}\overline{{\text {t}}}}$$ t t ¯ production, and no indications of a bias in the measurements are observed. 

Abstract A search is presented for physics beyond the standard model, based on measurements of dijet angular distributions in proton–proton collisions at $$\sqrt{s}=13\hbox {TeV}$$ s = 13 TeV . The data collected with the CMS detector at the LHC correspond to an integrated luminosity of 35.9 $$\,\text {fb}^{-1}$$ fb - 1 . The observed distributions, corrected to particle level, are found to be in agreement with predictions from perturbative quantum chromodynamics that include electroweak corrections. Constraints are placed on models containing quark contact interactions, extra spatial dimensions, quantum black holes, or dark matter, using the detector-level distributions. In a benchmark model where only left-handed quarks participate, contact interactions are excluded at the 95% confidence level up to a scale of 12.8 or 17.5TeV, for destructive or constructive interference, respectively. The most stringent lower limits to date are set on the ultraviolet cutoff in the Arkani–Hamed–Dimopoulos–Dvali model of extra dimensions. In the Giudice–Rattazzi–Wells convention, the cutoff scale is excluded up to 10.1TeV. The production of quantum black holes is excluded for masses below 5.9 and 8.2TeV, depending on the model. For the first time, lower limits between 2.0 and 4.6TeVare set on the mass of a dark matter mediator for (axial-)vector mediators, for the universal quark coupling $$g_{\mathrm {\mathrm {q}}} =1.0$$ g q = 1.0 .