962 research outputs found

    Charmonium Spectroscopy (X,Y,Z) at the B Factories

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    Since 2003 several states in the charmonium mass region were discovered. While in the conventional c c-bar spectrum some states are missing, the number of states observed up to now is larger than empty spaces in the c c-bar spectrum. This, together with other difficulties to explain observed states as a c c-bar mesons triggered discussions on a possible exotic interpretations. In this proceedings we present current experimental status from B-factories of the so called X, Y and Z states.Comment: Prepared for Beauty 2009 conference, Heidelberg, German

    Tevatron Experimental Issues at High Luminosities

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    In this paper we describe the detector components, triggers and analysis techniques for flavor physics at the Tevatron experiments CDF and DO. As Tevatron performs very well and runs at higher luminosities regularly we also touch issues related to it and efforts to improve detectors and triggers for such running.Comment: Prepared for Beauty 2009 conference, Heidelberg, German

    B Physics (Experiment)

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    In past few years the flavor physics made important transition from the work on confirmation the standard model of particle physics to the phase of search for effects of a new physics beyond standard model. In this paper we review current state of the physics of b-hadrons with emphasis on results with a sensitivity to new physics.Comment: To appear in the proceedings of the "Physics at the LHC 2010" conference. Added few missing reference

    Angular distribution of polarised Λb\Lambda_b baryons decaying to Λℓ+ℓ−\Lambda \ell^+\ell^-

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    Rare b→sℓ+ℓ−b \to s\ell^+\ell^- flavour-changing-neutral-current processes provide important tests of the Standard Model of particle physics. Angular observables in exclusive b→sℓ+ℓ−b \to s\ell^+\ell^- processes can be particularly powerful as they allow hadronic uncertainties to be controlled. Amongst the exclusive processes that have been studied by experiments, the decay Λb→Λℓ+ℓ−\Lambda_b\to \Lambda\ell^+\ell^- is unique in that the Λb\Lambda_b baryon can be produced polarised. In this paper, we derive an expression for the angular distribution of the Λb→Λℓ+ℓ−\Lambda_b\to \Lambda\ell^+\ell^- decay for the case where the Λb\Lambda_b baryon is produced polarised. This extends the number of angular observables in this decay from 10 to 34. Standard Model expectations for the new observables are provided and the sensitivity of the observables is explored under a variety of new physics models. At low-hadronic recoil, four of the new observables have a new short distance dependence that is absent in the unpolarised case. The remaining observables depend on the same short distance contributions as the unpolarised observables, but with different dependence on hadronic form-factors. These relations provide possibilities for novel tests of the SM that could be carried out with the data that will become available at the LHC or a future e+e−e^+e^- collider

    Summary of WG4: 'Lifetime, Mixing and Weak Mixing Phase in Charm and Beauty, Including Direct Determination of V_tx

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    We present the summary of the Working Group on lifetimes, mixing and weak mixing phases in charm and beauty mesons at the CKM 2010 workshop. In the past year or so good progress was achieved on both experimental and theoretical sides. While this yields improvement in our understanding of neutral meson mixing, further work is necessary to achieve the highest possible precision in order to investigate current hints for deviations between experiment and standard model predictions. With the recent LHC startup we see bright prospects for the near term future for huge improvements

    Angular distribution of Λ b 0 → p K − ℓ + ℓ − decays comprising Λ resonances with spin ≀ 5 / 2

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    This paper describes the angular distribution of Λb0→Λ→pK−ℓ+ℓ− decays. A full expression is given for the case of multiple interfering spin-states with spin ≀52. This distribution is relevant for future measurements of Λb0→pK−ℓ+ℓ− decays, where different states cannot easily be separated based on their mass alone. New observables arise when considering spin-52 states as well as interference between states. An exploration of their behaviour for a variety of beyond the Standard Model scenarios shows that some of these observables exhibit interesting sensitivity to the Wilson coefficients involved in b → sℓ+ℓ− transitions. Others are insensitive to the Wilson coefficients and can be used to verify the description of Λb0→Λ form-factors. A basis of weighting functions that can be used to determine all of the angular observables described in this paper in a moment analysis of the experimental data is also provided

    Absolute luminosity measurements with the LHCb detector at the LHC

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    Absolute luminosity measurements are of general interest for colliding-beam experiments at storage rings. These measurements are necessary to determine the absolute cross-sections of reaction processes and are valuable to quantify the performance of the accelerator. Using data taken in 2010, LHCb has applied two methods to determine the absolute scale of its luminosity measurements for proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In addition to the classic ''van der Meer scan'' method a novel technique has been developed which makes use of direct imaging of the individual beams using beam-gas and beam-beam interactions. This beam imaging method is made possible by the high resolution of the LHCb vertex detector and the close proximity of the detector to the beams, and allows beam parameters such as positions, angles and widths to be determined. The results of the two methods have comparable precision and are in good agreement. Combining the two methods, an overal precision of 3.5% in the absolute luminosity determination is reached. The techniques used to transport the absolute luminosity calibration to the full 2010 data-taking period are presented

    A model-independent Dalitz plot analysis of B±→DK± with D→K0Sh+h− (h=π,K) decays and constraints on the CKM angle Îł

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    A binned Dalitz plot analysis of B ±→DK ± decays, with D→KS0π+π- and D→KS0K+K-, is performed to measure the CP-violating observables x ± and y ± which are sensitive to the CKM angle Îł. The analysis exploits 1.0 fb -1 of data collected by the LHCb experiment. The study makes no model-based assumption on the variation of the strong phase of the D decay amplitude over the Dalitz plot, but uses measurements of this quantity from CLEO-c as input. The values of the parameters are found to be x -=(0.0±4.3±1.5±0.6)×10 -2, y -=(2.7±5.2±0.8±2.3)×10 -2, x +=(-10.3±4.5±1.8±1.4)×10 -2 and y +=(-0.9±3.7±0.8±3.0)×10 -2. The first, second, and third uncertainties are the statistical, the experimental systematic, and the error associated with the precision of the strong-phase parameters measured at CLEO-c, respectively. These results correspond to Îł=(44-38+43)°, with a second solution at γ→γ+180°, and r B=0.07±0.04, where r B is the ratio between the suppressed and favoured B decay amplitudes
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