Browsing by Subject "CP violation"

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  • Cordero-Cid, A.; Hernandez-Sanchez, J.; Keus, V.; King, S. F.; Moretti, S.; Rojas, D.; Sokolowska, D. (2016)
    We study an extension of the Standard Model (SM) in which two copies of the SM scalar SU(2) doublet which do not acquire a Vacuum Expectation Value (VEV), and hence are inert, are added to the scalar sector. We allow for CP-violation in the inert sector, where the lightest inert state is protected from decaying to SM particles through the conservation of a Z(2) symmetry. The lightest neutral particle from the inert sector, which has a mixed CP-charge due to CP-violation, is hence a Dark Matter (DM) candidate. We discuss the new regions of DM relic density opened up by CP-violation, and compare our results to the CP-conserving limit and the Inert Doublet Model (IDM). We constrain the parameter space of the CP-violating model using recent results from the Large Hadron Collider (LHC) and DM direct and indirect detection experiments.
  • Kärkkäinen, Timo (Helsingfors universitet, 2013)
    Neutrino oscillation is a particle physics phenomenon, where neutrino flavour is not conserved. The phenomenon was conjectured during the 1950s by Pontecorvo and confirmed during the 1990s by Super-Kamiokande collaboration. Consequently, neutrinos must have Dirac or Majorana mass and a relevant mass term must be included in standard model. Neutrino oscillation is the first confirmed beyond standard model phenomenon. It leads to nonconservation of quantum numbers L_e, L_μ and L_τ. Currently the scientific community has detected three different neutrinos, but has failed in designating the mass hierarchy and absolute mass of them. In addition, charge-parity symmetry violation (CP violation) is expected, but yet unconfirmed in the neutrino oscillation. This thesis includes a brief historical journey to neutrino physics and a lengthy discussion of electroweak sector of standard model (Glashow–Weinberg–Salam theory), with detailed phenomenology of neutrino oscillations. GLoBES simulation program and its partner AEDL language is introduced. Experiment definition methods in AEDL are covered extensively. The most important parameters are neutrino flux, source power, target mass and baseline length. Statistical methods are represented briefly. Main tool is χ2-test. Neutrino sources are assumed to be 700 kW SPS at CERN, Switzerland, 450 kW particle accelerator Protvino, Russia and 5 MW particle accelerator at Lund, Sweden. The target is LAGUNA detector at Pyhäsalmi mine, Finland. Using specifications of LAGUNA detector currently on drawing board and SPS as the neutrino source, the confidence limits for determining neutrino mass hierarchy and discovering nonzero CP violation are calculated. Mass hierarchy is almost conclusively determined, most of the δ_CP parameter space exceed the 5σ limit, which is considered the limit for a confirmed scientific discovery. CP violation discovery is confirmed within 5σ limit with 70 % of δ_CP parameter space. Including both the SPS and Protvino accelerator neutrino fluxes, the covered parameter space is increased significantly with both mass hierarchy determination and CP violation discovery. Including also Lund accelerator neutrino flux, mass hierarchy is conclusively determined. CP violation discovery is confirmed within 5σ limit with 65 % of δ_CP parameter space and within 90 % limit with 85 % of δ_CP parameter space. Pyhäsalmi mine is 2288 km from CERN neutrino source. The baseline is very close to bimagic baseline 2540 km, which allows extremely good statistics and sensitivity of oscillation parameters. In conclusion, Pyhäsalmi mine should be given priority, when candidate sites are considered.
  • Fujikawa, Kazuo; Tureanu, Anca (2021)
    We review several aspects of parity and CP violation in the framework of neutron-antineutron oscillations. We focus on the parity doubling theorem, which provides a criterion for neutron oscillation in the general theory with ∆B = 2 baryon number-violating interactions. We prove by explicit calculations that the violation of the conventional parity symmetry with P2 = 1 is the necessary condition for neutron oscillations to happen. While the CP violation is not manifest in the oscillation, it is nevertheless intrinsic to the system, and it is transferred, by the mixing matrix, to the neutron interactions and potentially observable as a contribution to the electric dipole moment.
  • Jukkala, Henri; Kainulainen, Kimmo; Koskivaara, Olli (2020)
    We study the phase space structure of exact quantum Wightman functions in spatially homogeneous, temporally varying systems. In addition to the usual mass shells, the Wightman functions display additional coherence shells around zero frequency k(0) = 0, which carry the information of the local quantum coherence of particle-antiparticle pairs. We find also other structures, which encode non-local correlations in time, and discuss their role and decoherence. We give a simple derivation of the cQPA formalism, a set of quantum transport equations, that can be used to study interacting systems including the local quantum coherence. We compute quantum currents created by a temporal change in a particle's mass, comparing the exact Wightman function approach, the cQPA and the semiclassical methods. We find that the semiclassical approximation, which is fully encompassed by the cQPA, works surprisingly well even for very sharp temporal features. This is encouraging for the application of semiclassical methods in electroweak baryogenesis with strong phase transitions.
  • Keus, Venus; Koivunen, Niko; Tuominen, Kimmo (2018)
    We study popular scalar extensions of the Standard Model, namely the singlet extension, the 2-Higgs doublet model (2HDM) and its extension by a singlet scalar. We focus on the contributions of the added scalars to the anomalous magnetic moment of the muon, (g - 2)(mu), in the presence of CP-violation, and the electric dipole moment of the electron (eEDM) in these models. In the absence of CP-violation, CP-even and CP-odd scalars contribute with an opposite sign to the anomalous magnetic moment of the muon and as a result these models generally require very light scalars to explain the observed discrepancy in (g - 2)(mu). We study the effect of CP-violation on the anomalous magnetic moment of the muon and its compatibility with the eEDM constraints. We show that given the current status of the global set of constraints applied on all values of cot beta, in the CP-violating scalar extensions, there exist no viable parameter space in agreement with both a(mu), and eEDM bounds.
  • Agarwalla, S. K.; Agostino, L.; Aittola, M.; Alekou, A.; Andrieu, B.; Angus, D.; Antoniou, F.; Ariga, A.; Ariga, T.; Asfandiyarov, R.; Autiero, D.; Ballett, P.; Bandac, I.; Banerjee, D.; Barker, G. J.; Barr, G.; Bartmann, W.; Bay, F.; Berardi, V.; Bertram, I.; Besida, O.; Blebea-Apostu, A. M.; Blondel, A.; Bogomilov, M.; Borriello, E.; Boyd, S.; Brancus, I.; Bravar, A.; Buizza-Avanzini, M.; Cafagna, F.; Calin, M.; Calviani, M.; Campanelli, M.; Cantini, C.; Caretta, O.; Cata-Danil, G.; Catanesi, M. G.; Cervera, A.; Chakraborty, S.; Chaussard, L.; Chesneanu, D.; Chipesiu, F.; Christodoulou, G.; Coleman, J.; Crivelli, P.; Davenne, T.; Dawson, J.; De Bonis, I.; De Jong, J.; Declais, Y.; Sanchez, P. Del Amo; Delbart, A.; Densham, C.; Di Lodovico, F.; Di Luise, S.; Duchesneau, D.; Dumarchez, J.; Efthymiopoulos, I.; Eliseev, A.; Emery, S.; Enqvist, K.; Enqvist, T.; Epprecht, L.; Ereditato, A.; Erykalov, A. N.; Esanu, T.; Finch, A. J.; Fitton, M. D.; Franco, D.; Galymov, V.; Gavrilov, G.; Gendotti, A.; Giganti, C.; Goddard, B.; Gomez, J. J.; Gomoiu, C. M.; Gornushkin, Y. A.; Gorodetzky, P.; Grant, N.; Haesler, A.; Haigh, M. D.; Hasegawa, T.; Haug, S.; Hierholzer, M.; Hissa, J.; Horikawa, S.; Huitu, K.; Ilic, J.; Ioannisian, A. N.; Izmaylov, A.; Jipa, A.; Kainulainen, K.; Kalliokoski, T.; Karadzhov, Y.; Kawada, J.; Khabibullin, M.; Khotjantsev, A.; Kokko, E.; Kopylov, A. N.; Kormos, L. L.; Korzenev, A.; Kosyanenko, S.; Kreslo, I.; Kryn, D.; Kudenko, Y.; Kudryavtsev, V. A.; Kumpulainen, J.; Kuusiniemi, P.; Lagoda, J.; Lazanu, I.; Levy, J. -M.; Litchfield, R. P.; Loo, K.; Loveridge, P.; Maalampi, J.; Magaletti, L.; Margineanu, R. M.; Marteau, J.; Martin-Mari, C.; Matveev, V.; Mavrokoridis, K.; Mazzucato, E.; McCauley, N.; Mercadante, A.; Mineev, O.; Mirizzi, A.; Mitrica, B.; Morgan, B.; Murdoch, M.; Murphy, S.; Mursula, K.; Narita, S.; Nesterenko, D. A.; Nguyen, K.; Nikolics, K.; Noah, E.; Novikov, Yu.; O'Keeffe, H.; Odell, J.; Oprima, A.; Palladino, V.; Papaphilippou, Y.; Pascoli, S.; Patzak, T.; Payne, D.; Pectu, M.; Pennacchio, E.; Periale, L.; Pessard, H.; Pistillo, C.; Popov, B.; Przewlocki, P.; Quinto, M.; Radicioni, E.; Ramachers, Y.; Ratoff, P. N.; Ravonel, M.; Rayner, M.; Resnati, F.; Ristea, O.; Robert, A.; Rondio, E.; Rubbia, A.; Rummukainen, K.; Sacco, R.; Saftoiu, A.; Sakashita, K.; Sarkamo, J.; Sato, F.; Saviano, N.; Scantamburlo, E.; Sergiampietri, F.; Sgalaberna, D.; Shaposhnikova, E.; Slupecki, M.; Sorel, M.; Spooner, N. J. C.; Stahl, A.; Stanca, D.; Steerenberg, R.; Sterian, A. R.; Sterian, P.; Still, B.; Stoica, S.; Strauss, T.; Suhonen, J.; Suvorov, V.; Szeptycka, M.; Terri, R.; Thompson, L. F.; Toma, G.; Tonazzo, A.; Touramanis, C.; Trzaska, W. H.; Tsenov, R.; Tuominen, Kimmo Ilmari; Vacheret, A.; Valram, M.; Vankova-Kirilova, G.; Vanucci, F.; Vasseur, G.; Velotti, F.; Velten, P.; Viant, T.; Vincke, H.; Virtanen, A.; Vorobyev, A.; Wark, D.; Weber, A.; Weber, M.; Wiebusch, C.; Wilson, J. R.; Wu, S.; Yershov, N.; Zalipska, J.; Zito, M. (2014)