We search for new charmless decays of neutral b hadrons to pairs of charged hadrons, using 1 fb(-1) of data collected by the CDF II detector at the Fermilab Tevatron. We report the first observation ...of the Bs0-->K-pi+ decay and measure B(Bs0-->K-pi+)=(5.0+/-0.7(stat)+/-0.8(syst))x10(-6). We also report the first observation of charmless b-baryon decays, and measure B(Lambdab0-->ppi-)=(3.5+/-0.6(stat)+/-0.9(syst))x10(-6) and B(Lambdab0-->pK-)=(5.6+/-0.8(stat)+/-1.5(syst))x10(-6). No evidence is found for other modes, and we set the limit B(Bs0-->pi+pi;-)<1.2x10(-6) at 90% C.L.
We report a measurement of the single-top-quark production cross section in 2.2 fb;{-1} of pp collision data collected by the Collider Detector at Fermilab at sqrts=1.96 TeV. Candidate events are ...classified as signal-like by three parallel analyses which use likelihood, matrix element, and neural network discriminants. These results are combined in order to improve the sensitivity. We observe a signal consistent with the standard model prediction, but inconsistent with the background-only model by 3.7 standard deviations with a median expected sensitivity of 4.9 standard deviations. We measure a cross section of 2.2(-0.6)(+0.7)(stat+syst) pb, extract the Cabibbo-Kobayashi-Maskawa matrix-element value |V(tb)|=0.88(-0.12)(+0.13)(stat+syst)+/-0.07(theory), and set the limit |V(tb)|>0.66 at the 95% C.L.
The TOTEM experiment at the CERN LHC has measured elastic proton-proton scattering at the centre-of-mass energy Formula omittedTeV and four-momentum transfers squared, |t|, from Formula omitted to ...0.2 GeV Formula omitted. Near the lower end of the t-interval the differential cross-section is sensitive to the interference between the hadronic and the electromagnetic scattering amplitudes. This article presents the elastic cross-section measurement and the constraints it imposes on the functional forms of the modulus and phase of the hadronic elastic amplitude. The data exclude the traditional Simplified West and Yennie interference formula that requires a constant phase and a purely exponential modulus of the hadronic amplitude. For parametrisations of the hadronic modulus with second- or third-order polynomials in the exponent, the data are compatible with hadronic phase functions giving either central or peripheral behaviour in the impact parameter picture of elastic scattering. In both cases, the Formula omitted-parameter is found to be Formula omitted. The results for the total hadronic cross-section are Formula omitted mb and Formula omitted mb for central and peripheral phase formulations, respectively. Both are consistent with previous TOTEM measurements.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Here, the TOTEM experiment at the CERN LHC has measured elastic proton–proton scattering at the centre-of-mass energy s√=8TeV and four-momentum transfers squared, |t|, from 6 × 10–4 to 0.2 GeV2. Near ...the lower end of the t-interval the differential cross-section is sensitive to the interference between the hadronic and the electromagnetic scattering amplitudes. This article presents the elastic cross-section measurement and the constraints it imposes on the functional forms of the modulus and phase of the hadronic elastic amplitude. The data exclude the traditional Simplified West and Yennie interference formula that requires a constant phase and a purely exponential modulus of the hadronic amplitude. For parametrisations of the hadronic modulus with second- or third-order polynomials in the exponent, the data are compatible with hadronic phase functions giving either central or peripheral behaviour in the impact parameter picture of elastic scattering. In both cases, the ρ-parameter is found to be 0.12±0.03. The results for the total hadronic cross-section are σtot = (102.9±2.3) mb and (103.0±2.3) mb for central and peripheral phase formulations, respectively. Both are consistent with previous TOTEM measurements.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
36.
The TOTEM experiment Avati, V.; Bergholm, V.; Boccone, V. ...
The European physical journal. C, Particles and fields,
07/2004, Letnik:
34, Številka:
S1
Journal Article
Recenzirano
Odprti dostop
AbstractTOTEM will measure the total pp cross-section at LHC by using a luminosity independent method based on simultaneous evaluation of the total elastic and inelastic rates. For an extended ...coverage of the inelastic and diffractive events, two forward tracking telescope are employed. The elastically or diffractively scattered protons are measured by a set of special detectors, which can be moved close to the circulating protons beams. The paper describes the physics reach of the experiment and the detectors which are being considered.PACS: 25.70.Ef – 21.60.Gx – 27.30.+t
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The pseudorapidity density of charged particles dNch/dη is measured by the TOTEM experiment in proton–proton collisions at √s = 8 TeV within the range 3.9 < η < 4.7 and –6.95 < η < –6.9. Data were ...collected in a low intensity LHC run with collisions occurring at a distance of 11.25 m from the nominal interaction point. The data sample is expected to include 96–97 % of the inelastic proton–proton interactions. The measurement reported here considers charged particles with pT > 0 MeV/c, produced in inelastic interactions with at least one charged particle in –7 < η < –6 or 3.7 < η < 4.8. The dNch/dη has been found to decrease with |η|, from 5.11 ± 0.73 at η = 3.95 to 1.81 ± 0.56 at η = –6.925. Several Monte Carlo generators are compared to the data and are found to be within the systematic uncertainty of the measurement.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Status of the TOTEM experiment at LHC Baechler, J.; Antchev, G.; Aspell, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2013, Letnik:
718
Journal Article
Recenzirano
The TOTEM experiment is dedicated to the measurement of the total proton–proton cross-section with the luminosity-independent method and the study of elastic and diffractive scattering processes. Two ...tracking telescopes, T1 and T2, integrated in the CMS detector, cover the pseudo-rapidity region between 3.1 and 6.5 on both sides of the interaction point IP5. The Roman Pot (RP) stations are located at distances of ±147m and ±220m with respect to the interaction point to measure the very forward scattered protons at very small angles. During the LHC technical stop in winter 2010/2011, the TOTEM experiment was completed with the installation of the T1 telescope and the RP stations at ±147m. In 2011, the LHC machine provided special optics with the large ß⁎=90m, allowing TOTEM to measure the elastic scattering differential cross-section, down to the four-momentum transfer squared |t|=2×10−2GeV2. Using the optical theorem and extrapolation of the differential cross-section to t=0 (optical point), the total p–p cross-section at the LHC energy of s=7TeV could be computed for the first time. Furthermore we measured with standard LHC beam optics and the energy of s=7TeV the forward charged particle pseudorapidity density dn/dη in the range of 5.3<|η|<6.4. The status of the experiment, the performance of the detectors with emphasis on the RPs are described and the first physics results are presented.
We present a search for supersymmetric neutrino {nu}-tilde production using the Tevatron pp collision data collected with the CDF II detector and corresponding to an integrated luminosity of 1 fb{sup ...-1}. We focus on the scenarios predicted by the R-parity violating (RPV) supersymmetric models in which sneutrinos decay to two charged leptons of different flavor. With the data consistent with the standard model expectations, we set upper limits on {sigma}(pp{yields}{nu}-tilde)xBR({nu}-tilde{yields}e{mu},{mu}{tau},e{tau}) and use these results to constrain the RPV couplings as a function of the sneutrino mass.
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