arXiv subjects
Publications and source records attributed to Michelangelo L. Mangano.
In a recent note, arXiv:0808.1415, it was argued that a hypothetical metastable black hole scenario could pose collider risk not excluded by our previous study. We comment on inconsistency of this proposed scenario.
I discuss the basic elements of the process that will lead to the discovery of possible new phenomena at the LHC. We review the status of the tools available to model the Standard Model backgrounds, and the role that such tools can play in the discovery phase, and in the exploration of the features and parameters of such new phenomena.
We study the potential of radiative decays of the Upsilon(1S) and of the phi mesons to search for a light pseudoscalar Higgs boson, proposed as a possible interpretation of Sigma+ --> p mu+mu- events observed by the HyperCP collaboration at Fermilab. We conclude that the detection of this signal should certainly be possible with the current CLEO Upsilon(1S) data, and is within the reach of KLOE in at least part of the range of couplings suggested by the HyperCP findings.
We study the matching of multijet matrix elements and shower evolution in the case of top production in hadronic collisions at the Tevatron and at the LHC. We present the results of the matching algorithm implemented in the ALPGEN Monte Carlo generator, and compare them with results obtained at the parton level, and with the predictions of the MC@NLO approach. We highlight the consistency of the matching algorithm when applied to these final states, and the excellent agreement obtained with MC@NLO for most inclusive quantities. We nevertheless identify also a remarkable difference in the rapidity spectrum of the leading jet accompanying the top quark pair, and comment on the likely origin of this discrepancy.
In this report we review recent developments in perturbation theory methods for gauge theories. We present techniques and results that are useful in the calculation of cross sections for processes with many final state partons which have applications in the study of multi-jet phenomena in high-energy Colliders.
I review here the history of bottom quark cross section measurements and theoretical predictions. Starting form the early days of UA1, and going through the sequence of the large excesses reported during run 0 and I at the Tevatron by CDF and D0, I summarize how both data and theory have evolved in time, thanks to improved experimental techniques, more data, and improved control over the main ingredients of the theoretical calculations. I conclude with the discussion of the preliminary data from run II, which appear to finally give a satisfactory picture of the data vs theory comparison.
We study in this paper the production, in hadronic collisions, of final states with W gauge bosons, heavy quark pairs and n extra jets (with n up to 4). The complete partonic tree-level QCD matrix elements are evaluated using the ALPHA algorithm, and the events generated at the parton level are then evolved through the QCD shower and eventually hadronised using the coherent shower evolution provided by the HERWIG Monte Carlo. We discuss the details of our Monte Carlo implementation, and present results of phenomenological interest for the Tevatron Collider and for the LHC. We also comment on the impact of our calculation on the backgrounds to W (H -> b bbar) production, when only one b jet is tagged.
We discuss the determination of polarized parton distributions from charged-current deep-inelastic scattering experiments. We summarize the next-to-leading order treatment of charged-current polarized structure functions, their relation to polarized parton distributions and scale dependence, and discuss their description by means of a next-to-leading order evolution code. We discuss current theoretical expectations and positivity constraints on the unmeasured C-odd combinations Delta q-Delta qbar of polarized quark distributions, and their determination in charged-current deep-inelastic scattering experiments. We give estimates of the expected errors on charged-current structure functions at a future neutrino factory, and perform a study of the accuracy in the determination of polarized parton distributions that would be possible at such a facility. We show that these measurements have the potential to distinguish between different theoretical scenarios for the proton spin structure.
We review the physics of heavy quark and quarkonium production in high energy hadronic collisions. We discuss the status of the theoretical calculations and compare the current results with the most recent measurements from the Tevatron collider experiments.
We review recent progress made in the theory of quarkonium production in hadronic collisions.
We present a calculation of the charm and gluon fragmentation contributions to inclusive $J/ψ$ and $ψ'$ production at large transverse momentum at the Tevatron. For $ψ$ production, we include both fragmentation directly into $ψ$ and fragmentation into $χ_c$ followed by the radiative decay $χ_c \to ψ+ γ$. We find that fragmentation overwhelms the leading-order mechanisms for prompt $ψ$ production at large $p_T$, and that the dominant contributions come from fragmentation into $χ_c$. Our results are consistent with recent data on $ψ$ production from the CDF and D0 experiments. In the case of prompt $ψ'$ production, the dominant mechanism at large $p_T$ is charm fragmentation into $ψ'$. We find serious disagreement between our theoretical predictions and recent $ψ'$ data from the Tevatron.
We present the preliminary results of a calculation of the fragmentation contribution to charmonium production at large transverse momentum in $p\bar{p}$ colliders. The fragmentation of gluons and charm quarks is the dominant direct production mechanism for sufficiently large $p_{\perp}$. We find that for both $J/ψ$ and $ψ'$ production fragmentation dominates over the conventional gluon-gluon fusion mechanism for $p_{\perp}$ greater than about 6 GeV.} Presented at the Workshop on Physics at Current Accelerator and the Supercollider, Argonne National Laboratory, June 1993.