Now showing 1 - 10 of 26
  • Publication
    Composite Resonances effects on EWPT and Higgs diphoton decay rate
    (2015-01-01)
    Cárcamo Hernández, A. E.
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    In scenarios of strongly coupled electroweak symmetry breaking, heavy composite particles of different spin and parity may arise and cause observable effects on signals that appear at loop levels. The recently observed process of Higgs to γγ at the LHC is one of such signals. We study the new constraints that are imposed on composite models from , together with the existing constraints from the high precision electroweak tests. We use an effective chiral Lagrangian to describe the effective theory that contains the Standard Model spectrum and the extra composites below the electroweak scale. Considering the effective theory cutoff at , consistency with the T and S parameters and the newly observed can be found for a rather restricted range of masses of vector and axial-vector composites from 1.5 TeV to 1.7 TeV and 1.8 TeV to 1.9 TeV, respectively, and only provided a non-standard kinetic mixing between the and fields is included.
  • Publication
    The experimental facility for the Search for Hidden Particles at the CERN SPS
    (2019-03-25)
    Ahdida, C.
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    Albanese, R.
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    Alexandrov, A.
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    Anokhina, A.
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    Aoki, S.
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    Arduini, G.
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    Atkin, E.
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    Azorskiy, N.
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    Back, J. J.
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    Bagulya, A.
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    Santos, F. Baaltasar Dos
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    Baranov, A.
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    Bardou, F.
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    Barker, G. J.
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    Battistin, M.
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    Bauche, J.
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    Bay, A.
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    Bayliss, V.
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    Bencivenni, G.
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    Berdnikov, A. Y.
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    Berdnikov, Y. A.
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    Berezkina, I.
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    Bertani, M.
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    Betancourt, C.
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    Bezshyiko, I.
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    Bezshyyko, O.
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    Bick, D.
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    Bieschke, S.
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    Blanco, A.
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    Boehm, J.
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    Bogomilov, M.
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    Bondarenko, K.
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    Bonivento, W. M.
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    Borburgh, J.
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    Boyarsky, A.
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    Brenner, R.
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    Breton, D.
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    Brundler, R.
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    Bruschi, M.
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    Büscher, V.
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    Buonaura, A.
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    Buontempo, S.
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    Cadeddu, S.
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    Calcaterra, A.
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    Calviani, M.
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    Campanelli, M.
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    Casolino, M.
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    Charitonidis, N.
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    Chau, P.
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    Chauveau, J.
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    Chepurnov, A.
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    Chernyavskiy, M.
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    Choi, K. Y.
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    Chumakov, A.
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    Ciambrone, P.
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    Cornelis, K.
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    Cristinziani, M.
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    Crupano, A.
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    Dallavalle, G. M.
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    Datwyler, A.
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    D'ambrosio, N.
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    D'appollonio, G.
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    Saraiva, J. De Carvalho
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    Lellis, G. De
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    De Magistris, M.
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    Roeck, A. De
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    De Serio, M.
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    De Simone, D.
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    Dedenko, L.
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    Dergachev, P.
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    Di Crescenzo, A.
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    Di Marco, N.
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    Dmitrievskiy, S.
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    Dougherty, L. A.
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    Dolmatov, A.
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    Domenici, D.
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    Donskov, S.
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    Drohan, V.
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    Dubreuil, A.
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    Ebert, J.
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    Enik, T.
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    Etenko, A.
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    Fabbri, F.
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    Fabbri, L.
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    Fabich, A.
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    Fedin, O.
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    Fedotovs, F.
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    Felici, G.
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    Ferro-Luzzi, M.
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    Filippov, K.
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    Fini, R. A.
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    Fonte, P.
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    Franco, C.
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    V. Lyubovitskij
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    Froeschl, R.
    The Search for Hidden Particles (SHiP) Collaboration has shown that the CERN SPS accelerator with its 400 GeV c proton beam offers a unique opportunity to explore the Hidden Sector [1–3]. The proposed experiment is an intensity frontier experiment which is capable of searching for hidden particles through both visible decays and through scattering signatures from recoil of electrons or nuclei. The high-intensity experimental facility developed by the SHiP Collaboration is based on a number of key features and developments which provide the possibility of probing a large part of the parameter space for a wide range of models with light long-lived superweakly interacting particles with masses up to O¹10º GeV c2 in an environment of extremely clean background conditions. This paper describes the proposal for the experimental facility together with the most important feasibility studies. The paper focuses on the challenging new ideas behind the beam extraction and beam delivery, the proton beam dump, and the suppression of beam-induced background.
  • Publication
    ANDES: An Underground Laboratory in South America
    ANDES (Agua Negra Deep Experiment Site) is an underground laboratory, proposed to be built inside the Agua Negra road tunnel that will connect Chile (IV Region) with Argentina (San Juan Province) under the Andes Mountains. The Laboratory will be 1750 meters under the rock, becoming the 3rd deepest underground laboratory of this kind in the world, and the first in the Southern Hemisphere. ANDES will be an international Laboratory, managed by a Latin American consortium. The laboratory will host experiments in Particle and Astroparticle Physics, such as Neutrino and Dark Matter searches, Seismology, Geology, Geophysics and Biology. It will also be used for the development of low background instrumentation and related services. Here we present the general features of the proposed laboratory, the current status of the proposal and some of its opportunities for science.
  • Publication
    Reconstruction of 400 GeV/c proton interactions with the SHiP-charm project
    (2024-06-01)
    Ahdida, C.
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    Akmete, A.
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    Bieschke, S.
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    Borburgh, J.
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    Chumakov, A.
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    Cornelis, K.
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    D’Ambrosio, N.
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    D’Appollonio, G.
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    de Asmundis, R.
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    De Carvalho Saraiva, J.
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    Di Giulio, L.
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    Dijkstra, H.
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    Dougherty, L. A.
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    Drohan, V.
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    Durhan, O.
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    Ehlert, M.
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    Elikkaya, E.
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    Graverini, E.
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    Grenard, J. L.
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    Lyubovitskij, V.
    AbstractThe SHiP-charm project was proposed to measure the associated charm production induced by 400 GeV/c protons in a thick target, including the contribution from cascade production. An optimisation run was performed in July 2018 at CERN SPS using a hybrid setup. The high resolution of nuclear emulsions acting as vertex detector was complemented by electronic detectors for kinematic measurements and muon identification. Here we present first results on the analysis of nuclear emulsions exposed in the 2018 run, which prove the capability of reconstructing proton interaction vertices in a harsh environment, where the signal is largely dominated by secondary particles produced in hadronic and electromagnetic showers within the lead target.
  • Publication
    The effect of composite resonances on Higgs decay into two photons
    (2014-01-01)
    Cárcamo Hernández, A. E.
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    In scenarios of strongly coupled electroweak symmetry breaking, heavy composite particles of different spin and parity may arise and cause observable effects on signals that appear at loop levels. The recently observed process of Higgs to $\gamma \gamma$ at the LHC is one of such signals. We study the new constraints that are imposed on composite models from $H\to \gamma\gamma$, together with the existing constraints from the high precision electroweak tests. We use an effective chiral Lagrangian to describe the effective theory that contains the Standard Model spectrum and the extra composites below the electroweak scale. Considering the effective theory cutoff at $\Lambda = 4\pi v \sim 3 $ TeV, consistency with the $T$ and $S$ parameters and the newly observed $H\to \gamma \gamma$ can be found for a rather restricted range of masses of vector and axial-vector composites from $1.5$ TeV to $1.7$ TeV and $1.8$ TeV to $1.9$ TeV, respectively, and only provided a non-standard kinetic mixing between the $W^{3}$ and $B^{0}$ fields is included.
  • Publication
    Neutrino emission rates in highly magnetized neutron stars revisited
    (2005-08-01)
    Riquelme, M.
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    Reisenegger, A.
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    Espinosa, O.
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    Magnetars are a subclass of neutron stars whose intense soft-gamma-ray bursts and quiescent X-ray emission are believed to be powered by the decay of a strong internal magnetic field. We reanalyze neutrino emission in such stars in the plausibly relevant regime in which the Landau band spacing $\Delta E$ of both protons and electrons is much larger than kT (where k is the Boltzmann constant and T is the temperature), but still much smaller than the Fermi energies. Focusing on the direct Urca process, we find that the emissivity oscillates as a function of density or magnetic field, peaking when the Fermi level of the protons or electrons lies about $\sim$3 kT above the bottom of any of their Landau bands. The oscillation amplitude is comparable to the average emissivity when $\Delta E$ is roughly the geometric mean of kT and the Fermi energy (excluding mass), i.e., at fields much weaker than required to confine all particles to the lowest Landau band. Since the density and magnetic field strength vary continuously inside the neutron star, there will be alternating surfaces of high and low emissivity. Globally, these oscillations tend to average out, making it unclear whether there will be any observable effects.
  • Publication
    Probing the Dirac or Majorana nature of the heavy neutrinos in pure leptonic decays at the LHC
    (2018-03-01)
    Arbelaéz, Carolina
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    Vasquez, Juan Carlos
    We propose a strategy for distinguishing the Dirac / Majorana character of heavy neutrinos with masses below the W boson mass, using purely leptonic decays at the LHC. The strategy makes use of a forward-backward asymmetry of the opposite charge lepton in the W+→l+l+l′−ν decay. In order to check the experimental feasibility of the model, we show, through a numerical analysis, that in the decay W+→e+e+μ−ν the two positrons in the final state can be distinguished for different ranges of the heavy neutrino masses. Finally, we estimated the number of events of W+→e+e+μ−ν for a Dirac and Majorana N neutrino. For an integrated luminosity of 120 fb−1 at LHC RUN II, signals can be found if heavy-to-light neutrino mixings are |UNμ|^2,|UNe|^2≳10−6.
  • Publication
    CP violation with Majorana neutrinos in K meson decays
    (2015-01-01) ;
    Campos, Miguel
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    Kim, C. S.
    We study the possibility of having CP asymmetries in the decay K± → π ∓` ±` ± (` = e, µ). This decay violates Lepton Number by two units and occurs only if there are Majorana particles that mediate the transition. Even though the absolute rate is highly suppressed by current bounds, we search for Majorana neutrino scenarios where the CP asymmetry arising from the lepton sector could be sizeable. This is indeed the case if there are two or more Majorana neutrinos with similar masses in the range around 102 MeV. In particular, the asymmetry is potentially near unity if two neutrinos are nearly degenerate, in the sense ∆mN ∼ ΓN . The full decay, however, may be difficult to detect not only because of the suppression caused by the heavy-to-light lepton mixing, but also because of the long lifetime of the heavy neutrino, which would induce large space separation between the two vertices where the charge leptons are produced. This particular problem should be less serious in heavier meson decays, as they involve heavier neutrinos with shorter lifetimes.
  • Publication
    The magnet of the scattering and neutrino detector for the SHiP experiment at CERN
    (2020-01-23)
    Arduini, G.
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    Atkin, E.
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    A. Chumakov
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    Back, J. J.
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    Bagulya, A.
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    Baaltasar Dos Santos, F.
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    Baranov, A.
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    Bardou, F.
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    Barker, G. J.
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    Battistin, M.
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    Bauche, J.
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    Bay, A.
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    Bayliss, V.
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    Bencivenni, G.
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    Berdnikov, A. Y.
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    Berdnikov, Y. A.
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    Berezkina, I.
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    Bertani, M.
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    Betancourt, C.
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    Bezshyiko, I.
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    Bezshyyko, O.
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    Bick, D.
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    Bieschke, S.
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    Blanco, A.
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    Boehm, J.
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    Bogomilov, M.
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    Bondarenko, K.
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    Bonivento, W. M.
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    Borburgh, J.
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    Boyarsky, A.
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    Brenner, R.
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    Breton, D.
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    Brundler, R.
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    Bruschi, M.
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    Büscher, V.
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    Buonaura, A.
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    Buontempo, S.
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    Cadeddu, S.
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    Calcaterra, A.
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    Calviani, M.
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    Campanelli, M.
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    Casolino, M.
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    Charitonidis, N.
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    Chau, P.
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    Chauveau, J.
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    Chepurnov, A.
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    Chernyavskiy, M.
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    Choi, K. Y.
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    Chumakov, A.
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    Ciambrone, P.
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    Congedo, L.
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    Cornelis, K.
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    Cristinziani, M.
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    Crupano, A.
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    Dallavalle, G. M.
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    Datwyler, A.
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    D'Ambrosio, N.
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    D'Appollonio, G.
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    de Carvalho Saraiva, J.
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    de Lellis, G.
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    Dipinto, P.
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    Dmitrenko, V.
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    Dmitrievskiy, S.
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    Dougherty, L. A.
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    Dolmatov, A.
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    Domenici, D.
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    Donskov, S.
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    Drohan, V.
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    Dubreuil, A.
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    Ehlert, M.
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    Fedin, O.
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    Fedotovs, F.
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    Felici, G.
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    V. Lyubovitskij
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    S. Kovalenko
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    Hayk Hakobyan
    The Search for Hidden Particles (SHiP) experiment proposal at CERN demands a dedicated dipole magnet for its scattering and neutrino detector. This requires a very large volume to be uniformly magnetized at B > 1:2 T, with constraints regarding the inner instrumented volume as well as the external region, where no massive structures are allowed and only an extremely low stray field is admitted. In this paper we report the main technical challenges and the relevant design options providing a comprehensive design for the magnet of the SHiP Scattering and Neutrino Detector.
    Scopus© Citations 5
  • Publication
    Majorana vs. Dirac sterile neutrinos at the LHC
    (2018-06-25) ;
    Kim, C. S.
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    Wang, Kechen
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    Zhang, Jue
    We study leptonic decays W± → e±e±μ∓ν and W± → μ±μ±e∓ν which would occur at the LHC if there exist sterile neutrinos with masses below MW . We also study ways to discriminate their Majorana or Dirac character, a rather non trivial task, because lepton number conservation cannot be checked due to the missing neutrino in the final state. We find that it is indeed possible to discriminate between Majorana vs. Dirac sterile neutrinos by comparing the production of e±e±μ∓ vs. μ±μ±e∓ if the N-e and N-μ mixings are sufficiently different. Alternatively, one could also distinguish the Majorana vs. Dirac character by studying the energy spectra of the opposite charge lepton, a method that works even for equal N-e and N-μ mixings.