3,091 research outputs found

    CP violation in charm and beauty decays at LHCb

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    LHCb is a dedicated heavy flavour physics precision experiment at the LHC searching for New Physics (NP) beyond the Standard Model (SM) through the study of very rare decays of beauty and charm-flavoured hadrons and precision measurements of CP-violating observables. In this review I will present a selection of recent precision measurements of CP-violating observables in the decays of beauty and charm-flavoured hadrons. These measurements are based on an integrated luminosity of up to 1.0fb−11.0 \rm{fb}^{-1} collected by LHCb in 2011.Comment: Invited talk at Fourth Workshop on Theory, Phenomenology and Experiments in Flavour Physics, 11 - 13 June 2012, Anacapri, Ital

    Higgs Searches and Prospects from LEP2

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    The status of the search at LEP2 for the Higgs in the Standard Model (SM) and in the minimal supersymmetric extension of the Standard Model MSSM) is reviewed. A preliminary lower limit of 95.5/c^2 at 95% C.L. on the SM Higgs is obtained after a preliminary analysis of the data collected at sqrt(s)= 189 GeV. For standard choices of MSSM parameter sets, the search for the neutral Higgs bosons h and A leads to preliminary 95% C.L. exclusion lower limits of 83.5GeV/c^2 and 84.5 GeV/c^2, respectively.Comment: 6 page

    Exotic charmonium-like spectroscopy at LHCb: a study of the X(3872) and of the Z(4430)^-

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    I will report on the recent LHCb results on the evidence for the decay X(3872)→ψ(2S)ÎłX(3872)\rightarrow\psi(2S) \gamma, and on the improved measurement of the mass and width of the Z(4430)−Z(4430)^-, the determination of its quantum numbers and the observation of its resonant character.Comment: Presented at The Second Annual Conference on Large Hadron Collider Physics Columbia University, New York, U.S.A June 2-7, 201

    LHCb: detector performance and first physics results

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    LHCb is a dedicated detector for bb and cc physics at the LHC. I will present a concise review of the detector design and performance together with a selection of early physics results and prospects. The integrated luminosity of 37pb−137 \rm{pb}^{-1} collected in 2010 has already allowed LHCb to perform a number of a very significant measurements, while the data expected for 2011 have the potential of revealing New Physics effects in the BsB_s sector.Comment: Proceedings for CORFU2010-WEEK

    Precision Physics at the LHC

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    A large number of precision measurements will be possible with the ATLAS and CMS experiments at the CERN Large Hadron Collider (LHC). Examples from W physics, Drell-Yan production of lepton pairs, Triple-Gauge Couplings,top physics, Higgs and Supersymmetry are discussed.Comment: 13 pages, 9 figures, presented ate the 5th Zeuthen Workshop on Elementary Particle Theory on "Loops and Legs in Quantum Field Theory" Bastel/Konigstein, Germany, April 200

    B Physics at LHCb

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    LHCb is a dedicated detector for b physics at the LHC. In this article we present a concise review of the detector design and performance together with the main physics goals and their relevance for a precise test of the Standard Model and search of New Physics beyond it.Comment: 26 pages, Contribution to "Perspectives on LHC Physics", ed. G.Kane and A.Pierc

    Cosmic Flows on 100 Mpc/h Scales: Standardized Minimum Variance Bulk Flow, Shear and Octupole Moments

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    The low order moments, such as the bulk flow and shear, of the large scale peculiar velocity field are sensitive probes of the matter density fluctuations on very large scales. In practice, however, peculiar velocity surveys are usually sparse and noisy, which can lead to the aliasing of small scale power into what is meant to be a probe of the largest scales. Previously, we developed an optimal ``minimum variance'' (MV) weighting scheme, designed to overcome this problem by minimizing the difference between the measured bulk flow (BF) and that which would be measured by an ideal survey. Here we extend this MV analysis to include the shear and octupole moments, which are designed to have almost no correlations between them so that they are virtually orthogonal. We apply this MV analysis to a compilation of all major peculiar velocity surveys, consisting of 4536 measurements. Our estimate of the BF on scales of ~ 100 Mpc/h has a magnitude of |v|= 416 +/- 78 km/s towards Galactic l = 282 degree +/- 11 degree and b = 6 degree +/- 6 degree. This result is in disagreement with LCDM with WMAP5 cosmological parameters at a high confidence level, but is in good agreement with our previous MV result without an orthogonality constraint, showing that the shear and octupole moments did not contaminate the previous BF measurement. The shear and octupole moments are consistent with WMAP5 power spectrum, although the measurement noise is larger for these moments than for the BF. The relatively low shear moments suggest that the sources responsible for the BF are at large distances.Comment: 13 Pages, 7 figures, 4 tables. Some changes to reflect the published versio

    Supersymmetric Electroweak Renormalization of the Z-Width in the MSSM (I)

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    Within the framework of the MSSM, we compute the complete set of electroweak one-loop supersymmetric quantum effects on the width ΓZ\Gamma_Z of the ZZ-boson in the on-shell renormalization scheme. Numerical analyses of the corrections to the various partial widths into leptons and quarks are presented. On general grounds, the average size of the electroweak SUSY corrections to ΓZ\Gamma_Z may well saturate the level of the present theoretical uncertainties, even if considering the full supersymmetric spectrum lying in the neighbourhood of the unaccessible LEP 200 range. Remarkably enough, for the present values of the top quark mass, the electroweak SUSY effects could be, globally, very close or even bigger than the electroweak SM corrections, but opposite in sign. Therefore, in the absence of theoretical errors, there are large regions of parameter space where one could find that, effectively, the electroweak SM corrections are ``missing'', or even having the ``wrong'' sign. This should be helpful in discriminating between the SM and the MSSM. However, an accurate prediction of the electroweak quantum effects on ΓZ\Gamma_Z will only be possible, if Δr\Delta r and αs\alpha_s are pinned down in the future with enough precision.Comment: 17 p. in LaTeX. Preprint UAB-FT-343. Error in figure caption #3 corrected. Results unchange

    The Values of mtm_t and αsˉ\bar{\alpha_s} Derived from the Non-Observation of Electroweak Radiative Corrections at LEP: Global Fit

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    A set of equations representing the W/ZW/Z mass ratio and various observables of ZZ decays in terms of αˉ≥α(mZ)\bar\alpha \equiv\alpha (m_Z), GÎŒG_{\mu}, mZm_Z, mtm_t, mHm_H, αˉs≥αs(mZ)\bar\alpha_{s} \equiv\alpha_{s} (m_Z), mbm_b and mτm_\tau (all other fermion masses being neglected) are compared with the latest data of the four LEP detectors, which at the level of one standard deviation coincide with their Born values. Our global fit gives: mt=161−16−22+15+16αˉs=0.119±0.006±0.002m_t = 161^{+ 15 +16}_{-16 -22} \bar\alpha_{s} = 0.119 \pm 0.006 \pm 0.002, where the central values correspond to mH=300m_H = 300 GeV, the first errors are statistical and the second ones represent shifts of the central values corresponding to mH=1000m_H = 1000 GeV(++) and 60 GeV(−-). The predicted mass of the top is smaller than in the recent fits by 4 GeV. The {\it predicted} values of mW/mZm_W/m_Z and the LEP observables, based on the fitted values of mtm_t and αˉs\bar{\alpha}_s, show a weak dependence on mHm_H and differ by several {\it predicted} standard deviations from the corresponding Born values. The uncertainties of the predicted values and their deviations from the corresponding Born values determine the experimental accuracy required to observe electroweak radiative corrections.Comment: LaTex, 15 pages (including 3 figures as EPS files at the end

    Search for the glueball candidates f0(1500) and fJ(1710) in gamma gamma collisions

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    Data taken with the ALEPH detector at LEP1 have been used to search for gamma gamma production of the glueball candidates f0(1500) and fJ(1710) via their decay to pi+pi-. No signal is observed and upper limits to the product of gamma gamma width and pi+pi- branching ratio of the f0(1500) and the fJ(1710) have been measured to be Gamma_(gamma gamma -> f0(1500)). BR(f0(1500)->pi+pi-) < 0.31 keV and Gamma_(gamma gamma -> fJ(1710)). BR(fJ(1710)->pi+pi-) < 0.55 keV at 95% confidence level.Comment: 10 pages, 3 figure
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