1,433 research outputs found
Physique du Higgs aux collisionneurs et
No full textCours donné par Patrick Janot et transcrit par N. Besson et Y. ArnoudNational audienceMesures de précision des paramètres du/des boson(s) de Higgs sur collisionneurs à particules fondamentales. Projets de techniques d'accélération des muons
Physique du Higgs aux collisionneurs et
No full textCours donné par Patrick Janot et transcrit par N. Besson et Y. ArnoudNational audienceMesures de précision des paramètres du/des boson(s) de Higgs sur collisionneurs à particules fondamentales. Projets de techniques d'accélération des muons
Top-quark electroweak couplings at the FCC-ee
No full textAn optimal-observable analysis of the lepton angular and energy distributions from top-quark pair production with semi-leptonic decays in e+e- collisions is used to predict the potential sensitivity of the FCC-ee to the couplings of the top quark to the photon and the Z.An optimal-observable analysis of the lepton angular and energy distributions from top-quark pair production with semi-leptonic decays in ee collisions is used to predict the potential sensitivity of the FCC-ee to the couplings of the top quark to the photon and the Z.An optimal-observable analysis of the lepton angular and energy distributions from top-quark pair production with semi-leptonic decays in e+e- collisions is used to predict the potential sensitivity of the FCC-ee to the couplings of the top quark to the photon and the Z
Direct measurement of αQED(m Z 2 ) at the FCC-ee
No full textWhen the measurements from the FCC-ee become available, an improved determination of the standard-model "input" parameters will be needed to fully exploit the new precision data towards either constraining or fitting the parameters of beyond-the-standard-model theories. Among these input parameters is the electromagnetic coupling constant estimated at the Z mass scale, alpha_QED(mZ). The measurement of the muon forward- backward asymmetry at the FCC-ee, just below and just above the Z pole, can be used to make a direct determination of alpha_QED(mZ) with an accuracy deemed adequate for an optimal use of the FCC-ee precision data.When the measurements from the FCC-ee become available, an improved determination of the standard-model “input” parameters will be needed to fully exploit the new precision data towards either constraining or fitting the parameters of beyond-the-standard-model theories. Among these input parameters is the electromagnetic coupling constant estimated at the Z mass scale, α(m ). The measurement of the muon forwardbackward asymmetry at the FCC-ee, just below and just above the Z pole, can be used to make a direct determination of α(m ) with an accuracy deemed adequate for an optimal use of the FCC-ee precision data.When the measurements from the FCC-ee become available, an improved determination of the standard-model "input" parameters will be needed to fully exploit the new precision data towards either constraining or fitting the parameters of beyond-the-standard-model theories. Among these input parameters is the electromagnetic coupling constant estimated at the Z mass scale, alpha_QED(mZ). The measurement of the muon forward-backward asymmetry at the FCC-ee, just below and just above the Z pole, can be used to make a direct determination of alpha_QED(mZ) with an accuracy deemed adequate for an optimal use of the FCC-ee precision data
Precision measurements of the top quark couplings at the FCC
No full textThe design study of the Future Circular Colliders (FCC) in a 100-km ring in the Geneva area has started at CERN at the beginning of 2014, as an option for post-LHC particle accelerators. The study has an emphasis on proton-proton and electron-positron high-energy frontier machines. In the current plans, the first step of the FCC physics programme would exploit a high-luminosity e+e- collider called FCC-ee, with centre-of-mass energies ranging from below the Z pole to the t-tbar threshold and beyond, followed by 100\,TeV proton-proton collisions as ultimate goal. When combined, these two steps offer a large palette of complementary measurements and sensitivity for new physics. In particular, the association of the FCC-ee and the FCC-hh allows measurements of the top-quark electroweak and Yukawa couplings to be performed with unrivaled precision.The design study of the Future Circular Colliders (FCC) in a 100-km ring in the Geneva area has started at CERN at the beginning of 2014, as an option for post-LHC particle accelerators. The study has an emphasis on proton-proton and electron-positron high-energy frontier machines. In the current plans, the first step of the FCC physics programme would exploit a high-luminosity e+e- collider called FCC-ee, with centre-of-mass energies ranging from below the Z pole to the t-tbar threshold and beyond, followed by 100\,TeV proton-proton collisions as ultimate goal. When combined, these two steps offer a large palette of complementary measurements and sensitivity for new physics. In particular, the association of the FCC-ee and the FCC-hh allows measurements of the top-quark electroweak and Yukawa couplings to be performed with unrivaled precision
The infamous 95 GeV excess at LEP: two b or not two b?
No full textA small deviation observed around 95 GeV in the diphoton invariant mass distribution in the LHC Run 2 data has been subject to considerable attention in the past couple of years. The interpretation of this excess as the manifestation of an additional scalar particle at this mass is often claimed to be supported by a previously observed, even smaller, excess in the invariant mass distribution in LEP data. This short note aims at confronting this claim to factual experimental observations, through a careful scrutiny of the detailed LEP public notes written at the time on the topic. It is found that the LEP data strongly disfavour the production of a new 95 GeV scalar particle, as well as any other new physics interpretation in the 95–100 GeV mass range.A small deviation observed around 95 GeV in the diphoton invariant mass distribution in the LHC Run 2 data has been subject to considerable attention in the past couple of years. The interpretation of this excess as the manifestation of an additional scalar particle at this mass is often claimed to be supported by a previously observed, even smaller, excess in the bb̄ invariant mass distribution in LEP data. This short note aims at confronting this claim to factual experimental observations, through a careful scrutiny of the detailed LEP public notes written at the time on the topic. It is found that the LEP data strongly disfavour the production of a new 95 GeV scalar particle, as well as any other new physics interpretation in the 95-100 GeV mass range
A positron annihilation study of crystalline, quasicrystalline and amorphous Al-Cu-T (T=Fe,V) alloys
No full textPT: J; CR: BANCEL PA, 1989, PHYS REV LETT, V63, P2741 BETTERTON JO, 1952, J I MET, V80, P459 BRANDT W, 1967, POSITRON ANNIHILATIO, P155 CALVAYRAC Y, 1990, J PHYS-PARIS, V51, P417 CHIDAMBARAM R, 1990, B AM PHYS SOC, V35, P331 CHIDAMBARAM R, 1990, J PHYS-CONDENS MAT, V2, P251 DUNLAP RA, 1986, J PHYS F MET PHYS, V16, P11 DUNLAP RA, 1986, J PHYS F MET PHYS, V16, P1247 DUNLAP RA, 1987, J PHYS F MET PHYS, V17, L39 DUNLAP RA, 1988, CAN J PHYS, V66, P476 GURYAN CA, 1989, PHYS REV LETT, V62, P2409 HEINEY PA, 1987, SCIENCE, V238, P660 HIRAGA K, 1988, JPN J APPL PHYS, V27, L951 HUMEROTHERY W, 1962, STRUCTURE METALS ALL JANOT C, 1988, J NONCRYSTALLINE SOL, V106, P193 JANOT C, 1989, J PHYS-CONDENS MAT, V1, P1029 JANSSEN T, 1986, ACTA CRYSTALLOGR A, V42, P261 KIZUKA T, 1989, PHYS REV B, V40, P796 LAWTHER DW, 1989, CAN J PHYS, V67, P463 PEARSON WB, 1972, CRYSTAL CHEM PHYSICS, CH4 SANYAL MK, 1989, J PHYS-CONDENS MATT, V1, P3733 SCHULTZ PJ, 1988, REV MOD PHYS, V60, P701 SHECHTMAN D, 1984, PHYS REV LETT, V53, P1951 SIEGEL RW, 1980, ANNU REV MATER SCI, V10, P393 TSAI AP, 1987, JPN J APPL PHYS, V26, P1505 VAKS VG, 1988, PHYS LETT A, V132, P131 WAGNER JL, 1988, PHYS REV B, V38, P7436 WAGNER JL, 1989, PHYS REV B, V39, P8091; NR: 28; TC: 10; J9: J PHYS-CONDENS MATTER; PG: 6; GA: DN624Source type: Electronic(1
The light gluino mass window revisited
No full textThe precise measurements of the ``electroweak observables'' performed at LEP and SLC are well consistent with the standard model predictions. Deviations from the standard model arising from vacuum polarization diagrams (also called ``weak loop corrections'') have been constrained in a model-independent manner with the epsilon formalism. Within the same formalism, additional deviations from new physics production processes can also be constrained, still in a model-independent way. For instance, a 95% C.L. limit of Delta Gamma_had} q qbar gluino gluino process, it allows an absolute lower limit to be set on the gluino mass, m_gluino > 6.3 GeV/c2 at 95% C.L., which definitely closes the so-called light gluino mass window. The precise measurements of the "electroweak observables" performed at LEP and SLC are well consistent with the standard model predictions. Deviations from the standard model arising from vacuum polarization diagrams (also called "weak loop corrections") have been constrained in a model-independent manner with the formalism. Within the same formalism, additional deviations from new physics production processes can also be constrained, still in a model-independent way. For instance, a 95% C.L. limit of had6.3 GeV /c 2 at 95% C.L., which definitely closes the so-called light gluino mass window.The precise measurements of the ``electroweak observables'' performed at LEP and SLC are well consistent with the standard model predictions. Deviations from the standard model arising from vacuum polarization diagrams (also called ``weak loop corrections'') have been constrained in a model-independent manner with the epsilon formalism. Within the same formalism, additional deviations from new physics production processes can also be constrained, still in a model-independent way. For instance, a 95% C.L. limit of Delta Gamma_had} q qbar gluino gluino process, it allows an absolute lower limit to be set on the gluino mass, m_gluino > 6.3 GeV/c2 at 95% C.L., which definitely closes the so-called light gluino mass window
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