118 research outputs found

    Nucleonic gamma-ray production in Pulsar Wind Nebulae

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    Observations of the inner radian of the Galactic disk at very high energy (VHE) gamma-rays have revealed at least 16 new sources. Besides shell type super-nova remnants, pulsar wind nebulae (PWN) appear to be a dominant source population in the catalogue of VHE gamma-ray sources. Except for the Crab nebula, the newly discovered PWN are resolved at VHE gamma-rays to be spatially extended (5-20 pc). Currently, at least 3 middle aged (t>10t>10 kyrs) PWN (Vela X, G18.0-0.7, and G313.3+0.6 in the ``Kookaburra'' region) and 1 young PWN MSH 15-5{\it2} (t=1.55t=1.55 kyrs) have been identified to be VHE emitting PWN (sometimes called ``TeV Plerions''). Two more candidate ``TeV Plerions'' have been identifed and have been reported at this conference [1]. In this contribution, the gamma-ray emission from Vela X is explained by a nucleonic component in the pulsar wind. The measured broad band spectral energy distribution is compared with the expected X-ray emission from primary and secondary electrons. The observed X-ray emission and TeV emission from the three middle aged PWN are compared with each other.Comment: 6 pages, 3 figures, to appear in proceedings "The Multi-Messenger Approach to High-Energy Gamma-Ray Sources", Barcelona July 200

    Study of the lineshape of the chi(c1) (3872) state

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    A study of the lineshape of the chi(c1) (3872) state is made using a data sample corresponding to an integrated luminosity of 3 fb(-1) collected in pp collisions at center-of-mass energies of 7 and 8 TeV with the LHCb detector. Candidate chi(c1)(3872) and psi(2S) mesons from b-hadron decays are selected in the J/psi pi(+)pi(-) decay mode. Describing the lineshape with a Breit-Wigner function, the mass splitting between the chi(c1 )(3872) and psi(2S) states, Delta m, and the width of the chi(c1 )(3872) state, Gamma(Bw), are determined to be (Delta m=185.598 +/- 0.067 +/- 0.068 Mev,)(Gamma BW=1.39 +/- 0.24 +/- 0.10 Mev,) where the first uncertainty is statistical and the second systematic. Using a Flatte-inspired model, the mode and full width at half maximum of the lineshape are determined to be (mode=3871.69+0.00+0.05 MeV.)(FWHM=0.22-0.04+0.13+0.07+0.11-0.06-0.13 MeV, ) An investigation of the analytic structure of the Flatte amplitude reveals a pole structure, which is compatible with a quasibound D-0(D) over bar*(0) state but a quasivirtual state is still allowed at the level of 2 standard deviations

    Measurement of the CKM angle γγ in B±→DK±B^\pm\to D K^\pm and B±→Dπ±B^\pm \to D π^\pm decays with D→KS0h+h−D \to K_\mathrm S^0 h^+ h^-

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    A measurement of CPCP-violating observables is performed using the decays B±→DK±B^\pm\to D K^\pm and B±→Dπ±B^\pm\to D \pi^\pm, where the DD meson is reconstructed in one of the self-conjugate three-body final states KSπ+π−K_{\mathrm S}\pi^+\pi^- and KSK+K−K_{\mathrm S}K^+K^- (commonly denoted KSh+h−K_{\mathrm S} h^+h^-). The decays are analysed in bins of the DD-decay phase space, leading to a measurement that is independent of the modelling of the DD-decay amplitude. The observables are interpreted in terms of the CKM angle Îł\gamma. Using a data sample corresponding to an integrated luminosity of 9 fb−19\,\text{fb}^{-1} collected in proton-proton collisions at centre-of-mass energies of 77, 88, and 13 TeV13\,\text{TeV} with the LHCb experiment, Îł\gamma is measured to be (68.7−5.1+5.2)∘\left(68.7^{+5.2}_{-5.1}\right)^\circ. The hadronic parameters rBDKr_B^{DK}, rBDπr_B^{D\pi}, ÎŽBDK\delta_B^{DK}, and ÎŽBDπ\delta_B^{D\pi}, which are the ratios and strong-phase differences of the suppressed and favoured B±B^\pm decays, are also reported

    Measurement of CP asymmetries and branching fraction ratios of B− decays to two charm mesons

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    The CPCP asymmetries of seven B−B^- decays to two charm mesons are measured using data corresponding to an integrated luminosity of 9fb−19\text{fb}^{-1} of proton-proton collisions collected by the LHCb experiment. Decays involving a D∗0D^{*0} or Ds∗−D^{*-}_s meson are analysed by reconstructing only the D0D^0 or Ds−D^-_s decay products. This paper presents the first measurement of ACP(B−→Ds∗−D0)\mathcal{A}^{CP}(B^- \rightarrow D^{*-}_s D^0) and ACP(B−→Ds−D∗0)\mathcal{A}^{CP}(B^- \rightarrow D^{-}_s D^{*0}), and the most precise measurement of the other five CPCP asymmetries. There is no evidence of CPCP violation in any of the analysed decays. Additionally, two ratios between branching fractions of selected decays are measured.The CP asymmetries of seven B−^{−} decays to two charm mesons are measured using data corresponding to an integrated luminosity of 9 fb−1^{−1} of proton-proton collisions collected by the LHCb experiment. Decays involving a D∗0^{*0} or Ds∗− {D}_s^{\ast -} meson are analysed by reconstructing only the D0^{0} or Ds− {D}_s^{-} decay products. This paper presents the first measurement of ACP \mathcal{A} ^{CP}(B−^{−}→Ds∗− {D}_s^{\ast -} D0^{0}) and ACP \mathcal{A} ^{CP}(B−^{−}→Ds− {D}_s^{-} D∗0^{∗0}), and the most precise measurement of the other five CP asymmetries. There is no evidence of CP violation in any of the analysed decays. Additionally, two ratios between branching fractions of selected decays are measured.[graphic not available: see fulltext]The CPCP asymmetries of seven B−B^- decays to two charm mesons are measured using data corresponding to an integrated luminosity of 9 fb−19\text{ fb}^{-1} of proton-proton collisions collected by the LHCb experiment. Decays involving a D∗0D^{*0} or Ds∗−D^{*-}_s meson are analysed by reconstructing only the D0D^0 or Ds−D^-_s decay products. This paper presents the first measurement of ACP(B−→Ds∗−D0)\mathcal{A}^{CP}(B^- \rightarrow D^{*-}_s D^0) and ACP(B−→Ds−D∗0)\mathcal{A}^{CP}(B^- \rightarrow D^{-}_s D^{*0}), and the most precise measurement of the other five CPCP asymmetries. There is no evidence of CPCP violation in any of the analysed decays. Additionally, two ratios between branching fractions of selected decays are measured
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