103,155 research outputs found
Standard model physics at the LHC
No full textIn this brief overview, we summarize theoretical advances and discuss selected topics of Standard Model physics at the Large Hadron Collider (LHC). In particular we show some illustrative recent results in the determination of parton densities and in the calculation of QCD radiative corrections
La composizione di “Camma” nel carteggio tra Adelaide Ristori, Giuseppe Montanelli e Lauretta Cipriani Parra
No full textAmong Adelaide Ristori’s great successes, Camma, premiered in Paris on April 23rd, 1857, was written for her by Giuseppe Montanelli. From the perspective of a dramaturgical investigation into how a Grande Attrice chose and construct her repertoire, the correspondence between Montanelli and Ristori is an important case study: the author sends the various acts of the tragedy, as they were completed, to the actress, who gradually comments on their value and offers suggestions for their better stage success, well aware of the strategies to best enhance her own abilities and the expectations of the audience. Ristori’s answers, always lucid, focused and decisive, allow us to recognize to what extent a Grande Attrice would intervene on a text, tailor-made for her, considering her strengths and abilities. Thus, this essay is about the compositional strategies of the textual score and is based on an in-depth reading of the correspondence, investigated especially with regard to the actress’s interventions, whose actual realisation and success are then compared with the final script and the review of the tragedy’s outcome with audiences and critics
Improved factorization for threshold resummation in heavy quark to heavy quark decays
No full textAbstract We consider the resummation of soft-gluon effects in heavy quark to heavy quark decays, namely the processes Q 1 → Q 2 + ( non QCD partons ) , where Q 1 and Q 2 are two different heavy quarks. We construct a new factorization scheme for threshold resummed spectra, which allows us to consistently evaluate the distribution of the final hadron invariant mass m X in all the kinematic regions, i.e. when m X is smaller, of the same order, or larger than the mass of the final quark Q 2 . A dependence of the improved Coefficient function on the threshold variable is introduced, which can however be relegated to a small interval of this variable by means of the so-called Partition of Unity. We explicitly apply our improved scheme to the b → X s + γ decay at next-to-leading logarithmic accuracy
Heavy-quark fragmentation: perturbative resummation with the analytic coupling model
No full textWe describe a model to include non-perturbative corrections to heavy-quark fragmentation, based on next-to-next-to-leading logarithmic threshold resummation and on an effective QCD coupling not containing the Landau pole. We present a phenomenological comparison between the predictions of the model and experimental data from B and D meson fragmentation in e(+)e(-) annihilation
Vub from inclusive B decays and the analytic coupling model
No full textWe extract |Vub| comparing various experimental spectra of inclusive charmless semileptonic B decays (B → Xulνl), with the prediction of a model based on NNLL soft gluon resummation and on an analytic QCD coupling not containing the Landau pole. The value extracted is |Vub|=(3.69±0.13exp±0.31th)×10−3. This value is in good agreement with the value extracted from exclusive decays, while the agreement is less good with respect to previous inclusive measurements
Transverse-momentum resummation: Vector boson production and decay at hadron colliders
No full textWe consider the W and Z/γ∗ bosons transverse-momentum (qT) distribution at hadron colliders. We include the leptonic decay of vector bosons with the corresponding spin correlations, the finite width effects and the fully-differential dependence on leptonic variables. At small values of qT, we resum to all-orders the logarithmically-enhanced perturbative QCD contributions up to next-to-next-to-leading logarithmic accuracy. Resummed results are consistently combined with the next-to-leading fixed-order result at intermediate and large values of qT. We present a preliminary comparison with some of the available LHC data
Lepton charge asymmetry from W decays at hadron colliders in NNLO QCD
No full textWe present the next-to-next-to-leading order (NNLO) QCD computation of the charged leptons asymmetry from W± boson decays in hadron collisions. Our calculation includes the dependence on the lepton kinematical cuts applied in actual experimental analyses. We compare numerical results on the charge asymmetry in pp ̄ collisions with some of the available Tevatron data. We show illustrative results for the asymmetry in pp collisions at LHC energy
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