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Search Results: 1 - 10 of 351510 matches for " P. G. Mercadante "
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Search for supersymmetry at the LHC
Mercadante, P. G.;
Brazilian Journal of Physics , 2004, DOI: 10.1590/S0103-97332004000700020
Abstract: it is generally accepted that the lhc is the accelerator facility at which weak scale supersymmetry will either be discovered or definitely excluded. i give a brief introduction to weak scale supersymmetry presenting the general argument that limit the supersymmetrical spectrum to be below tev energies. we will see that the lhc is able to search for supersymmetry in several of its realization far above the expected spectrum masses. however, in the last section we will see some well motivated scenarios where supersymmetric sparticles might be very heavy, thus beyond the lhc reach. such scenarios deserve a more detailed study to push the lhc reach.
Analyses of Long Lived Slepton NLSP in GMSB Model at Linear Collider
P. G. Mercadante,H. Yamamoto
Physics , 1999,
Abstract: We performed an analysis on the detection of a long lived stau at a linear collider with $\sqrt{s}=500$ GeV. In GMSB models a long lived NLSP is predicted for large value of the supersymmetry breaking scale F. Furthermore in a large portion of the parameter space this particle is a stau. Such heavy charged particles will leave a track in the tracking volume and hit the muon detector. In order to disentangle this signal from the muon background we explore kinematics and particle identification tools: time of flight device, dE/dX and Cerenkov devices.
Searching for Bottom Squarks at Luminosity Upgrades of the Fermilab Tevatron
Howard Baer,P. G. Mercadante,Xerxes Tata
Physics , 1998, DOI: 10.1103/PhysRevD.59.015010
Abstract: Because of their Yukawa interactions, third generation squarks may be substantially lighter than those of the first two generations. Assuming that $\tb_1 \to b\tz_1$ and $\tz_1$ escapes experimental detection, we show that experiments at the Main Injector upgrade (integrated luminosity of $2 fb^{-1}$) of the Tevatron should be sensitive to $b$-squark masses up to 210 GeV for $m_{\tz_1} \leq 120$ GeV. For integrated luminosities of $10 fb^{-1}$ (25 $fb^{-1}$) the sbottom mass reach increases by 20 GeV (35 GeV). If the channel $\tb_1 \to b\tz_2$ is also accessible, the reach becomes model-dependent and may be degraded relative to the case where only the decay to $\tz_1$ is allowed. In models with gaugino mass unification and $\mu$ much larger than gaugino masses, we argue that this degradation is unlikely to be larger than 30-40 GeV.
Anomalous g^5_z coupling at $γγ$ colliders
O. J. P. Eboli,M. B. Magro,P. G. Mercadante
Physics , 1995, DOI: 10.1103/PhysRevD.52.3836
Abstract: We study the constraints on the anomalous coupling $g^Z_5$ that can be obtained from the analysis of the reaction $\gamma\gamma \rightarrow W^+ W^- Z$ at future linear $e^+e^-$ colliders. We find out that a $0.5$ ($1$) TeV $e^+e^-$ collider operating in the $\gamma\gamma$ mode can probe values of $g_5^Z$ of the order of $0.15$ ($4.5 \times 10^{-2}$) for an integrated luminosity of $10$ fb$^{-1}$. This shows that the ability to search for this anomalous interaction of the $\gamma\gamma$ mode is better than the one of the usual $e^+e^-$ mode, and it is similar to the ability of the $e\gamma$ mode.
Extending SUSY reach at the CERN large hadron collider using b-tagging
Mercadante, P. G.;Mizukoshi, J. K.;Tata, Xerxes;
Brazilian Journal of Physics , 2007, DOI: 10.1590/S0103-97332007000400013
Abstract: we analyze the potential of the cern large hadron collider on the reach of the focus point (fp) region in the msugra parameter space. this region, consistent with wmap results, is characterized by multi-tev masses for the superpartners of quarks and leptons and relatively light charginos and neutralinos. moreover, since the lsp has a substantial higgsino component, it is expected that the gluino decays predominantly to third generation quarks, producing a final state with multiple hard b jets. analyzing events with $\not\!\!{e_t}+n$t+ n jets + tagged b-jets, we show that the lhc reach can improve as much as 20% from current projections. although we performed the analysis specifically for the fp region, the b-tagging should be important to enhance the susy signal in a variety of models where a relatively light gluino decays mostly to third generation quarks.
Top pair production with an extra gluon at the Tevatron
V. Barger,P. G. Mercadante,R. J. N. Phillips
Physics , 1995, DOI: 10.1016/0370-2693(95)01594-9
Abstract: We calculate top pair production and decay at the Tevatron $p\bar p$ collider, with the emission of an extra gluon, and study the corresponding $W+5$\,jet top signals including full spin correlations in the $W \to \ell\nu$ leptonic and $W\to jj$ hadronic decays. We study the feasibility of reconstructing $W+5$\,jet top events with a single $b$-tag, including realistic energy resolution. Our suggested basic procedure based on kinematic fitting achieves about 74\% reconstruction efficiency, with 74\% of the reconstructed events correctly classified (purity); this improves to 82\% efficiency with 77\% purity in double-$b$-tagged events. We suggest possible refinements, based on virtuality criteria, that give higher purity at the cost of lower reconstruction efficiency.
The Reach of Tevatron Upgrades in Gauge-Mediated Supersymmetry Breaking Models
Howard Baer,P. G. Mercadante,Xerxes Tata,Yili Wang
Physics , 1999, DOI: 10.1103/PhysRevD.60.055001
Abstract: We examine signals for sparticle production at the Tevatron within the framework of gauge mediated supersymmetry breaking models for four different model lines, each of which leads to qualitatively different signatures. We identify cuts to enhance the signal above Standard Model backgrounds, and use ISAJET to evaluate the SUSY reach of experiments at the Fermilab Main Injector and at the proposed TeV33. For the model lines that we have examined, we find that the reach is at least as large, and frequently larger, than in the mSUGRA framework. For two of these model lines, we find that the ability to identify $b$-quarks and $\tau$-leptons with high efficiency and purity is essential for the detection of the signal.
Direct Signals for Large Extra Dimensions in the Production of Fermion Pairs at Linear Colliders
O. J. P. Eboli,M. B. Magro,P. Mathews,P. G. Mercadante
Physics , 2001, DOI: 10.1103/PhysRevD.64.035005
Abstract: We analyze the potentiality of the new generation of $e^+e^-$ linear colliders to search for large extra dimensions via the production of fermion pairs in association with Kaluza-Klein gravitons (G), i.e. $e^+e^- \leftarrow f\bar{f}G$. This process leads to a final state exhibiting a significant amount of missing energy in addition to acoplanar lepton or jet pairs. We study in detail this reaction using full tree level contibutions due to the graviton emission and the standard model backgrounds. After choosing the cuts to enhance the signal, we show that a linear collider with a center-of-mass energy of 500 GeV will be able to probe quantum gravity scales from 0.96(0.86) up to 4.1(3.3) TeV at 2(5)$\sigma$ level, depending on the number of extra dimensions.
Searching for Leptoquarks in electron-photon Collisions
O. J. P. Eboli,E. M. Gregores,M. B. Magro,P. G. Mercadante,S. F. Novaes
Physics , 1993, DOI: 10.1016/0370-2693(93)90547-U
Abstract: We study the production of composite scalar leptoquarks in $e\gamma$ colliders, and we show that an $e^+e^-$ machine operating in its $e\gamma$ mode is the best way to look for these particles in $e^+e^-$ collisions, due to the hadronic content of the photon.
Quartic Anomalous Couplings in $γγ$ Colliders
O. J. P. Eboli,M. B. Magro,P. G. Mercadante,S. F. Novaes
Physics , 1995, DOI: 10.1103/PhysRevD.52.15
Abstract: We study the constraints on the vertices $W^+W^- Z\gamma$, $W^+W^-\gamma\gamma$, and $ZZ\gamma\gamma$ that can be obtained from triple-gauge-boson production at the next generation of linear $e^+e^-$ colliders operating in the $\gamma\gamma$ mode. We analyze the processes $\gamma\gamma \to W^+W^-V$ ($V=Z$, or $\gamma$) and show that these reactions increase the potential of $e^+e^-$ machines to search for anomalous four-gauge-boson interactions.
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