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In this talk I briefly summarize different models for σ tot 2γ (e + e - →γγ→ hadrons) and contrast model predictions with the data. I will then discuss the capability of the future e + e - and γγ colliders to distinguish between various... more
In this talk I briefly summarize different models for σ tot 2γ (e + e - →γγ→ hadrons) and contrast model predictions with the data. I will then discuss the capability of the future e + e - and γγ colliders to distinguish between various models and end with an outlook for future work.
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The PHOTON 2017 conference ("International Conference on the Structure and the Interactions of the Photon", including the 22th "International Workshop on Photon-Photon Collisions", and the "International Workshop... more
The PHOTON 2017 conference ("International Conference on the Structure and the Interactions of the Photon", including the 22th "International Workshop on Photon-Photon Collisions", and the "International Workshop on High Energy Photon Colliders") was held at CERN (Geneva) from 22th to 26th May, 2017. The conference is part of a series that was initiated in 1973 in Paris as "International Colloquium on Photon-Photon Collisions at Electron-Positron Storage Rings". The latest Photon conferences took place in Novosibirsk (2015), Paris (2013), Spa (2011), Hamburg (2009), Paris (2007), Warsaw (2005), Frascati (2003), Ascona (2001), Freiburg (2000), Ambleside (1999), and Egmond aan Zee (1997). The topics of the conference included (i) photon-photon processes in e + e - , proton-proton (pp) and nucleus-nucleus (AA) collisions at current and future colliders, (ii) photon-hadron interactions in e ± p, pp, and AA collisions, (iii) final-state photon prod...
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Supersymmetric scenarios with a very weakly interacting lightest superpartner (LSP)—like the gravitino or axino—naturally give rise to a long-lived next-to-LSP (NLSP). If the NLSP is a charged slepton it leaves a very distinct signature... more
Supersymmetric scenarios with a very weakly interacting lightest superpartner (LSP)—like the gravitino or axino—naturally give rise to a long-lived next-to-LSP (NLSP). If the NLSP is a charged slepton it leaves a very distinct signature in a collider experiment. At the ILC/CLIC it will be possible to capture a significant fraction of the produced charged sleptons and observe their decays. These decays potentially reveal the nature of the LSP and thus provide a unique possibility to measure the properties of a very weakly interacting LSP which otherwise is most likely hidden from any other observation, like direct or indirect dark matter searches. We review the proposals that have been made to measure the LSP properties at the ILC/CLIC and compare its potential to the capability of the LHC.
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We investigate the double parton scattering production ofW±+jets in proton colliders. At high energies an observable signal is expected from double parton collisions when events with small transverse momentumW together with two jets... more
We investigate the double parton scattering production ofW±+jets in proton colliders. At high energies an observable signal is expected from double parton collisions when events with small transverse momentumW together with two jets balancing inpT are selected. Double parton scattering is also a potentially serious background to several rare processes whose signal is aW++W-(?ev+jets) final state. A simplepTW cut seems to be sufficient to separate the genuineW-pair events from the double scattering background.
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The International Linear Collider (ILC) is a 200-500 GeV center-of-mass high-luminosity linear electron-positron collider, based on 1.3 GHz superconducting radio-frequency (SCRF) accelerating cavities. The ILC has a total footprint of... more
The International Linear Collider (ILC) is a 200-500 GeV center-of-mass high-luminosity linear electron-positron collider, based on 1.3 GHz superconducting radio-frequency (SCRF) accelerating cavities. The ILC has a total footprint of about 31 km and is designed for a peak luminosity of 2x10^ 34 cm^-2 s^-1. The complex includes a polarized electron source, an undulator-based positron source, two 6.7 km circumference damping rings, two-stage bunch compressors, two 11 km long main linacs and a 4.5 km long beam ...
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ABSTRACT
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The field of particle physics is at the crossroads. The discovery of a Higgs-like boson completed the Standard Model (SM), but the lacking observation of convincing resonances Beyond the SM (BSM) offers no guidance for the future of... more
The field of particle physics is at the crossroads. The discovery of a Higgs-like boson completed the Standard Model (SM), but the lacking observation of convincing resonances Beyond the SM (BSM) offers no guidance for the future of particle physics. On the other hand, the motivation for New Physics has not diminished and is, in fact, reinforced by several striking anomalous results in many experiments. Here we summarise the status of the most significant anomalies, including the most recent results for the flavour anomalies, the multi-lepton anomalies at the LHC, the Higgs-like excess at around 96 GeV, and anomalies in neutrino physics, astrophysics, cosmology, and cosmic rays. While the LHC promises up to 4 $$\hbox {ab}^{-1}$$ ab - 1 of integrated luminosity and far-reaching physics programmes to unveil BSM physics, we consider the possibility that the latter could be tested with present data, but that systemic shortcomings of the experiments and their search strategies may preclu...
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The Large Hadron–Electron Collider (LHeC) is designed to move the field of deep inelastic scattering (DIS) to the energy and intensity frontier of particle physics. Exploiting energy-recovery technology, it collides a novel, intense... more
The Large Hadron–Electron Collider (LHeC) is designed to move the field of deep inelastic scattering (DIS) to the energy and intensity frontier of particle physics. Exploiting energy-recovery technology, it collides a novel, intense electron beam with a proton or ion beam from the High-Luminosity Large Hadron Collider (HL-LHC). The accelerator and interaction region are designed for concurrent electron–proton and proton–proton operations. This report represents an update to the LHeC’s conceptual design report (CDR), published in 2012. It comprises new results on the parton structure of the proton and heavier nuclei, QCD dynamics, and electroweak and top-quark physics. It is shown how the LHeC will open a new chapter of nuclear particle physics by extending the accessible kinematic range of lepton–nucleus scattering by several orders of magnitude. Due to its enhanced luminosity and large energy and the cleanliness of the final hadronic states, the LHeC has a strong Higgs physics prog...
Research Interests: Physics, Nuclear Physics, Particle Physics, Quantum Chromodynamics, Large Hadron Collider, and 15 moreKinematics, Calibration, Electron, Acceptance, FCC, Lattice, Buildings, Magnet, Ion Beam, New Physics, Electron Beam, Collider, Deep Inelastic Scattering, Energy recovery, and nucleus structure function
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The Circular Electron Positron Collider (CEPC) is a large international scientific facility proposed by the Chinese particle physics community to explore the Higgs boson and provide critical tests of the underlying fundamental physics... more
The Circular Electron Positron Collider (CEPC) is a large international scientific facility proposed by the Chinese particle physics community to explore the Higgs boson and provide critical tests of the underlying fundamental physics principles of the Standard Model that might reveal new physics. The CEPC, to be hosted in China in a circular underground tunnel of approximately 100 km in circumference, is designed to operate as a Higgs factory producing electron-positron collisions with a center-of-mass energy of 240 GeV. The collider will also operate at around 91.2 GeV, as a Z factory, and at the WW production threshold (around 160 GeV). The CEPC will produce close to one trillion Z bosons, 100 million W bosons and over one million Higgs bosons. The vast amount of bottom quarks, charm quarks and tau-leptons produced in the decays of the Z bosons also makes the CEPC an effective B-factory and tau-charm factory. The CEPC will have two interaction points where two large detectors wil...
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We survey the expected polarization of the top produced in the decay of a scalar top quark, $ \widetilde{t}\to t\widetilde{\chi}_i^0,i=1-2 $ . The phenomenology is quite interesting, since the expected polarization depends both on the... more
We survey the expected polarization of the top produced in the decay of a scalar top quark, $ \widetilde{t}\to t\widetilde{\chi}_i^0,i=1-2 $ . The phenomenology is quite interesting, since the expected polarization depends both on the mixing in the stop and neutralino sectors and on the mass differences between the stop and the neutralino. We find that a mixed stop behaves almost like a right-handed stop due to the larger hypercharge that enters the stop/top/gaugino coupling and that these polarisation effects disappear, when $ {m_{{{{{\widetilde{t}}}_1}}}}\approx {m_t}+{m_{{\widetilde{\chi}_i^0}}} $ . After a discussion on the expected top polarization from the decay of a scalar top quark, we focus on the interplay of polarization and kinematics at the LHC. We discuss different probes of the top polarization in terms of lab-frame observables. We find that these observables faithfully reflect the polarization of the parent top-quark, but also have a non-trivial dependence on the kin...