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  • 251. de Angelis, G.
    et al.
    Gadea, A.
    Farnea, E.
    Isocrate, R.
    Petkov, P.
    Marginean, N.
    Napoli, D. R.
    Dewald, A.
    Bellato, M.
    Bracco, A.
    Camera, F.
    Curien, D.
    De Poli, M.
    Fioretto, E.
    Fitzler, A.
    Kasemann, S.
    Kintz, N.
    Klug, T.
    Lenzi, S.
    Lunardi, S.
    Menegazzo, R.
    Pavan, P.
    Pedroza, J. L.
    Pucknell, V.
    Ring, C.
    Sampson, J.
    Wyss, Ramon
    KTH, Superseded Departments, Physics.
    Coherent proton-neutron contribution to octupole correlations in the neutron-deficient Xe-114 nucleus2002In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 535, no 04-jan, p. 93-102Article in journal (Refereed)
    Abstract [en]

    Gamma ray linear polarization and picosecond lifetimes have been measured for levels in the neutron deficient nucleus Xe-114 using the EUROBALL IV spectrometer and the Cologne plunger device. The EUCLIDES Si-ball was used to improve the reaction channel selectivity. The linear polarization results have, for the first time, unambiguously determined the electromagnetic character of the dipole transitions de-exciting the negative parity level sequence, providing clear evidence for enhanced octupole collectivity. The discovery of two E3 transitions and the measurement of the lifetimes of the states depopulated by these transitions have allowed a quantitative determination of the octupole collectivity in the A approximate to 112 mass region. The large measured B(E3) values, close to approximate to 70 W.u., are among the strongest observed hitherto and indicate a coherent proton-neutron contribution to the octupole moment.

  • 252.
    de Woul, Jonas
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Merle, Alexander
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Ohlsson, Tommy
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Establishing analogies between the physics of extra dimensions and carbon nanotubes2012In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 714, no 1, p. 44-47Article in journal (Refereed)
    Abstract [en]

    We point out a conceptual analogy between the physics of extra spatial dimensions and the physics of carbon nanotubes which arises for principle reasons, although the corresponding energy scales are at least ten orders of magnitude apart. For low energies, one can apply the Kaluza-Klein description to both types of systems, leading to two completely different but consistent interpretations of the underlying physics. In particular, we discuss in detail the Kaluza-Klein description of armchair and zig-zag carbon nanotubes. Furthermore, we describe how certain experimental results for carbon nanotubes could be re-interpreted in terms of the Kaluza-Klein description. Finally, we present ideas for new measurements that could allow to probe concepts of models with extra spatial dimensions in table-top experiments, providing further links between condensed matter and particle physics.

  • 253.
    Di Vecchia, Paolo
    et al.
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, Copenhagen, DK-2100, Denmark.
    Luna, A.
    Mani L. Bhaumik Institute for Theoretical Physics, Department of Physics and Astronomy, University of California at Los Angeles, CA 90095, United States.
    Naculich, S. G.
    Department of Physics, Bowdoin College, Brunswick, ME 04011, United States.
    Russo, R.
    Centre for Research in String Theory, School of Physics and Astronomy, Queen Mary University of London, 327 Mile End Road, London, E1 4NS, United Kingdom.
    Veneziano, G.
    Theory Department, CERN, Geneva 23, CH-1211, Switzerland.;Collége de France, 11 place M. Berthelot, Paris, 75005, France.
    White, C. D.
    Centre for Research in String Theory, School of Physics and Astronomy, Queen Mary University of London, 327 Mile End Road, London, E1 4NS, United Kingdom.
    A tale of two exponentiations in N=8 supergravity2019In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 798, article id 134927Article in journal (Refereed)
    Abstract [en]

    The structure of scattering amplitudes in supergravity theories continues to be of interest. Recently, the amplitude for 2→2 scattering in N=8 supergravity was presented at three-loop order for the first time. The result can be written in terms of an exponentiated one-loop contribution, modulo a remainder function which is free of infrared singularities, but contains leading terms in the high energy Regge limit. We explain the origin of these terms from a well-known, unitarity-restoring exponentiation of the high-energy gravitational S-matrix in impact-parameter space. Furthermore, we predict the existence of similar terms in the remainder function at all higher loop orders. Our results provide a non-trivial cross-check of the recent three-loop calculation, and a necessary consistency constraint for any future calculation at higher loops.

  • 254. Eggers, J.
    et al.
    Hoppe, Jens
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
    Singularity formation for time-like extremal hypersurfaces2009In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 680, no 3, p. 274-278Article in journal (Refereed)
    Abstract [en]

    We derive self-similar string solutions in a graph representation, near the point of singularity formation, which can be shown to extend to point-like singularities on M(em)branes, as well as to the radially symmetric case. Crown

  • 255.
    Ema, Yohei
    et al.
    Univ Tokyo, Fac Sci, Dept Phys, Bunkyo Ku, Tokyo 1130033, Japan..
    Karciauskas, Mindaugas
    Univ Jyvaskyla, Dept Phys, POB 35 YFL, FI-40014 Jyvaskyla, Finland..
    Lebedev, Oleg
    Univ Helsinki, POB 64, FI-00014 Helsinki, Finland.;Helsinki Inst Phys, POB 64, FI-00014 Helsinki, Finland..
    Rusak, Stanislav
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. Stockholm Univ, Roslagstullsbacken 23, SE-10691 Stockholm, Sweden..
    Zatta, Marco
    Univ Helsinki, POB 64, FI-00014 Helsinki, Finland.;Helsinki Inst Phys, POB 64, FI-00014 Helsinki, Finland..
    Higgs-inflaton mixing and vacuum stability2019In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 789, p. 373-377Article in journal (Refereed)
    Abstract [en]

    The quartic and trilinear Higgs field couplings to an additional real scalar are renormalizable, gauge and Lorentz invariant. Thus, on general grounds, one expects such couplings between the Higgs and an inflaton in quantum field theory. We find that the often omitted trilinear interaction is only weakly constrained by cosmology and could stabilize the electroweak vacuum by increasing the Higgs self coupling. The consequent Higgs-inflaton mixing can be as large as order one making a direct inflaton search possible at the LHC. Published by Elsevier B.V. This is an open access article under the CC BY license.

  • 256. Fritzsch, H.
    et al.
    Zhou, Shun
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Neutrino mixing angles from texture zeros of the lepton mass matrices2013In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 718, no 4-5, p. 1457-1464Article in journal (Refereed)
    Abstract [en]

    Taking into account the latest neutrino oscillation data, we study texture zeros of the lepton mass matrices. Assuming the Dirac neutrino mass matrix MD, the charged-lepton mass matrix Ml and the mass matrix of heavy right-handed Majorana neutrinos MR to have three texture zeros, we show that the observed neutrino mixing angles can naturally be obtained. The phenomenological implications for the neutrino mass spectrum, the CP-violating phases, the tritium beta decay and the neutrinoless double-beta decay are explored.

  • 257. Gorska, M.
    et al.
    Caceres, L.
    Grawe, H.
    Pfuetzner, M.
    Jungclaus, A.
    Pietri, S.
    Werner-Malento, E.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Andgren, Karin
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Khaplanov, Anton
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Evolution of the N=82 shell gap below Sn-132 inferred from core excited states in In-1312009In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 672, no 4-5, p. 313-316Article in journal (Refereed)
    Abstract [en]

    The gamma-ray decay of ail excited state in In-131, the one proton hole neighbor of the doubly magic (132)sn has been measured. A high-spin, core-excited isomer with T-1/2 = 630(60) us was identified following production by both relativistic fragmentation of a Xe-136 beam and fission Of a U-238 beam. This state deexcites by a single gamma-ray branch of 3782(2) keV from which direct evidence for the size of the N = 82 shell gal) is inferred. The results are discussed in comparison to a shell-model Calculation including configurations across the closed shells at N = 82 and Z = 50.

  • 258.
    Gudnason, Sven Bjarke
    et al.
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Nitta, Muneto
    Effective field theories on solitons of generic shapes2015In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 747, p. 173-177Article in journal (Refereed)
    Abstract [en]

    A class of effective field theories for moduli or collective coordinates on solitons of generic shapes is constructed. As an illustration, we consider effective field theories living on solitons in the O(4) non-linear sigma model with higher-derivative terms.

  • 259.
    Holma, Pontus
    et al.
    KTH, School of Engineering Sciences (SCI), Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, Roslagstullsbacken 21, SE-10691 Stockholm, Sweden..
    Ohlsson, Tommy
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. KTH Royal Inst Technol, Sch Engn Sci, AlbaNova Univ Ctr, Dept Phys, Roslagstullsbacken 21, SE-10691 Stockholm, Sweden..
    Phenomenological predictions for pentaquark masses from fits to baryon masses2020In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 800, article id 135108Article in journal (Refereed)
    Abstract [en]

    We investigate the mass spectra of exotic hadrons known as pentaquarks. We extend a simple phenomenological model based on the Gursey-Radicati mass formula for hadrons to include both charmed and bottom baryons as well as to be able to predict masses of pentaquark states including both charm and bottom quark-antiquark pairs. In particular, we perform numerical fits of this model, which includes seven free parameters, to masses of 21 baryons. We find that the model can be well fitted to the experimental values of the baryon masses and observe that the predicted value of about 4400 MeV for the mass of the pentaquark P-c(4380)(+) lies within the experimental range reported by the LHCb experiment. In addition, the predicted value of about 4500 MeV for the mass of the pentaquark P-c(4450)(+) is close to the experimental value. Finally, in the future, other predicted values for masses of additional pentaquarks could be shown to agree with upcoming experimental results.

  • 260.
    Hoppe, Jens
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
    Fundamental structures of M(brane) theory2011In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 695, no 1-4, p. 384-386Article in journal (Refereed)
    Abstract [en]

    A dynamical symmetry, as well as special diffeomorphism algebras generalizing the Witt-Virasoro algebra, related to Poincare invariance and crucial with regard to quantization, questions of integrability, and M(atrix) theory, are found to exist in the theory of relativistic extended objects of any dimension.

  • 261.
    Hoppe, Jens
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
    Reformulating M-brane equations2008In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 663, no 4, p. 351-352Article in journal (Refereed)
    Abstract [en]

    A Lorentz invariant formulation of Born-Infeld M-brane equations that are not diffeomorphism invariant is presented, and their relation to the standard "extremal-volume" equations clarified.

  • 262.
    Hossenfelder, Sabine
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. Stockholm University, Sweden.
    A relativistic acoustic metric for planar black holes2016In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 752, p. 13-17Article in journal (Refereed)
    Abstract [en]

    We demonstrate here that the metric of a planar black hole in asymptotic anti-de Sitter space can, on a slice of dimension 3. +. 1, be reproduced as a relativistic acoustic metric. This completes an earlier calculation in which the non-relativistic limit was used, and also serves to obtain a concrete form of the Lagrangian.

  • 263.
    Ideguchi, Eiji
    et al.
    KTH, Superseded Departments, Physics.
    Cederwall, Bo
    KTH, Superseded Departments, Physics.
    Wyss, Ramon
    KTH, Superseded Departments, Physics.
    Bäck, Torbjörn
    KTH, Superseded Departments, Physics.
    Lagergren, Karin
    KTH, Superseded Departments, Physics.
    Johnson, Arne
    KTH, Superseded Departments, Physics.
    Klamra, Wlodzimierz
    KTH, Superseded Departments, Physics.
    Cederkäll, Joakim
    KTH, Superseded Departments, Physics.
    Devlin, M
    Elson, J
    LaFosse, R
    Lerma, F
    Sarantites, G
    Tomov, V
    Hausmann, M
    Jungclaus, A
    Napoli, R
    Carpenter, P
    Janssens, F
    Kondev, G
    Lauritsen, T
    Lister, J
    Seweryniak, D
    Wiedenhoever, I
    Clark, M
    Fallon, P
    Lee, Y
    Macchiavelli, O
    Macleod, W
    Superdeformation in 91Tc2000In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 492, no 3-4, p. 245-253Article in journal (Refereed)
    Abstract [en]

    A high-spin rotational band with 11 gamma -ray transitions has barn observed in Tc-91. The dynamical moment of inertia as well as the transition quadrupole moment of 8.1(-1.4)(+1.9) eb measured for this band show the characteristics of a superdeformed band. However, the shape is more elongated than in the neighbouring A = 80-90 superdeformed nuclei. Theoretical interpretations of the band within the cranked Strutinsky approach based on two different Woods-Saxon potential parameterisations are presented. Even though an unambiguous configuration assignment proved difficult, both calculations indicate a larger deformation and at least three additional high-N intruder orbitals occupied compared to the lighter SD nuclei. (C) 2000 Elsevier Science B.V. All rights reserved.

  • 264. Jackson, P. D.
    et al.
    Lund-Jensen, Bengt
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Sidebo, P. Edvin
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Zwalinski, L.
    et al.,
    Search for charged Higgs bosons produced in association with a top quark and decaying via H± → τν using pp collision data recorded at s=13 TeV by the ATLAS detector2016In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 759, p. 555-574Article in journal (Refereed)
  • 265. Jacobsson, Björn
    et al.
    Ohlsson, Tommy
    KTH, Superseded Departments, Physics.
    Snellman, Håkan
    KTH, Superseded Departments, Physics.
    Winter, Walter
    Effects of random matter density fluctuations on the neutrino oscillation transition probabilities in the Earth2002In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 532, no 04-mar, p. 259-266Article in journal (Refereed)
    Abstract [en]

    In this Letter, we investigate the effects of random fluctuations of the Earth matter density for long baselines on the neutrino oscillation transition probabilities. We especially identify relevant parameters characterizing the matter density noise and calculate their effects by averaging over statistical ensembles of a large number of matter density profiles. For energies and baselines appropriate to neutrino factories, absolute errors on the relevant appearance probabilities are at the level of \DeltaP(alphabeta)\ similar to 10(-4) (with perhaps \P-mue similar to 1% for neutrinos), whereby a modest improvement in understanding of the geophysical data should render such effects unimportant.

  • 266. Jimenez, Jose Beltran
    et al.
    Koivisto, Tomi S.
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Spacetimes with vector distortion: Inflation from generalised Weyl geometry2016In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 756, p. 400-404Article in journal (Refereed)
    Abstract [en]

    Spacetime with general linear vector distortion is introduced. Thus, the torsion and the nonmetricity of the affine connection are assumed to be proportional to a vector field (and not its derivatives). The resulting two-parameter family of non-Riemannian geometries generalises the conformal Weyl geometry and some other interesting special cases. Taking into account the leading nonlinear correction to the Einstein-Hilbert action results uniquely in the one-parameter extension of the Starobinsky inflation known as the alpha-attractor. The most general quadratic curvature action introduces, in addition to the canonical vector kinetic term, novel ghost-free vector-tensor interactions.

  • 267. Joss, D. T.
    et al.
    Darby, I. G.
    Page, R. D.
    Uusitalo, J.
    Eeckhaudt, S.
    Grahn, T.
    Greenlees, P. T.
    Jones, P. M.
    Julin, R.
    Juutinen, S.
    Ketelhut, S.
    Leino, M.
    Leppänen, A. -P
    Nyman, M.
    Pakarinen, J.
    Rahkila, P.
    Sarén, J.
    Scholey, C.
    Steer, A.
    Cannon, A. J.
    Stevenson, P. D.
    Al-Khalili, J. S.
    Ertürk, S.
    Venhart, M.
    Gall, B.
    Hadinia, Baharak
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Simpson, J.
    Probing the limit of nuclear existence: Proton emission from Re-1592006In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 641, no 1, p. 34-37Article in journal (Refereed)
    Abstract [en]

    The observation of the new nuclide Re-159(75)84 provides important insights into the evolution of single-particle structure and the mass surface in heavy nuclei beyond the proton drip line. This nuclide, 26 neutrons away from the nearest stable rhenium isotope, was synthesised in the reaction Cd-106(Ni-58, p4n) and identified via its proton radioactivity using the RITU gas-filled separator and the GREAT focal-plane spectrometer. Comparisons of the measured proton energy (E-p = 1805 +/- 20 keV) and decay half-life (t(1/2) = 21 +/- 4 mu s) with values calculated using the WKB method indicate that the proton is emitted from an h(11/2) state. The implications of these results for future experimental investigations into even more proton unbound nuclei using in-flight separation techniques are considered.

  • 268. Joss, D. T.
    et al.
    Page, R. D.
    Herzán, A.
    Donosa, L.
    Uusitalo, J.
    Carroll, R. J.
    Darby, I. G.
    Andgren, Karin
    KTH, School of Engineering Sciences (SCI), Physics.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Eeckhaudt, S.
    Grahn, T.
    Greenlees, P. T.
    Hadinia, Baharak
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Jakobsson, Ulrika
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics. University of Jyvaskyla, Finland.
    Jones, P. M.
    Julin, R.
    Juutinen, S.
    Leino, M.
    Leppanen, A. -P
    Nyman, M.
    O'Donnell, D.
    Pakarinen, J.
    Rahkila, P.
    Sandzelius, M.
    Sarén, J.
    Scholey, C.
    Seweryniak, D.
    Simpson, J.
    Sorri, J.
    Spectroscopy at the two-proton drip line: Excited states in 158W2017In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 772, p. 703-707Article in journal (Refereed)
    Abstract [en]

    Excited states have been identified in the heaviest known even-Z N=84 isotone 158W, which lies in a region of one-proton emitters and the two-proton drip line. The observation of γ-ray transitions feeding the ground state establishes the excitation energy of the yrast 6+ state confirming the spin-gap nature of the α-decaying 8+ isomer. The 8+ isomer is also expected to be unbound to two-proton emission but no evidence for this decay mode was observed. An upper limit for the two-proton decay branch has been deduced as b2p≤ 0.17% at the 90% confidence level. The possibility of observing two-proton emission from multiparticle isomers in nearby nuclides is considered.

  • 269. King, S L
    et al.
    Simpson, J
    Page, R D
    Amzal, N
    Bäck, Torbjörn
    Cederwall, Bo
    Cocks, J F C
    Cullen, D M
    Greenlees, P T
    Harder, M K
    Helariutta, K
    Jones, P
    Julin, R
    Juutinen, S
    Kankaanpaa, H
    Keenan, A
    Kettunen, H
    Kuusiniemi, P
    Leino, M
    Lemmon, R
    Muikku, M
    Savelius, A
    Uusitalo, J
    Van Isacker, P
    First observation of excited states in the neutron deficient nuclei (PT)-P-168 and Pt-1701998In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 443, no 1-4, p. 82-88Article in journal (Refereed)
    Abstract [en]

    Excited states have been observed for the first time in (XPt)-X-168 and Pt-170 using the alpha-decay recoil-tagging technique. The trend of decreasing deformation moving away from the N = 104 mid-shell continues far Pt-170 but the structure of Pt-168 is significantly different. The low spin level energy systematics in Pt168-184 are presented and discussed within the framework of the interacting boson model. (C) 1998 Elsevier Science B.V. All rights reserved.

  • 270.
    Konstandin, Thomas
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Ohlsson, Tommy
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    The effective matter potential for highly relativistic neutrinos2006In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 634, no 03-feb, p. 267-271Article in journal (Refereed)
    Abstract [en]

    We investigate matter effects on highly relativistic neutrinos. The self-energy of neutrinos is determined in an electron or neutrino background taking into account resonance and finite width effects of the gauge bosons. We find minor changes compared to the formerly used formula for the propagator function and large deviations of the effective width from the decay width of the gauge bosons considering higher moments of the electron or neutrino distribution function.

  • 271. LAFOSSE, DR
    et al.
    HUA, PF
    SARANTITES, DG
    BAKTASH, C
    AKOVALI, YA
    BRINKMAN, M
    Cederwall, Bo
    CRISTANCHO, F
    DORING, J
    GROSS, CJ
    JIN, HQ
    KOROLIJA, M
    LANDULFO, E
    LEE, IY
    MACCHIAVELLI, AO
    MAIER, MR
    RATHBUN, W
    SALADIN, JX
    STRACENER, DW
    TABOR, SL
    VANDERMOLLEN, A
    WERNER, TR
    CHARACTERIZATION OF THE FIRST SUPERDEFORMED BAND IN THE A-APPROXIMATE-TO-80 REGION1995In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 354, no 1-2, p. 34-40Article in journal (Refereed)
    Abstract [en]

    The recently discovered superdeformed band in one of the strontium isotopes has been identified as belonging to Sr-83 from a study with the Gammasphere array and the Microball charged-particle detector system. From its decay pattern, a spin of (81 +/- 2)/2 ($) over bar h is deduced for the highest level of this band. Evidence for very fast transition rates and agreement of the characteristics of this band with the theoretical predictions establish the yrast superdeformed nature of this band in Sr-83.

  • 272.
    Langmann, Edwin
    KTH, School of Engineering Sciences (SCI), Physics, Mathematical Physics. KTH, School of Engineering Sciences (SCI), Physics, Condensed Matter Theory.
    (3+1)-Dimensional Schwinger Terms and Non-commutative Geometry1994In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 338, p. 241-248Article in journal (Refereed)
  • 273.
    Langmann, Edwin
    KTH, School of Engineering Sciences (SCI), Physics, Mathematical Physics. KTH, School of Engineering Sciences (SCI), Physics, Condensed Matter Theory.
    Gauge Theories on a Cylinder1992In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 296, p. 117-120Article in journal (Refereed)
  • 274.
    Langmann, Edwin
    KTH, School of Engineering Sciences (SCI), Physics, Mathematical Physics. KTH, School of Engineering Sciences (SCI), Physics, Condensed Matter Theory.
    Gribov ambiguity and non-trivial vacuum structure of gauge theories on a cylinder1993In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 303, p. 303-307Article in journal (Refereed)
  • 275.
    Langmann, Edwin
    KTH, School of Engineering Sciences (SCI), Physics, Mathematical Physics. KTH, School of Engineering Sciences (SCI), Physics, Condensed Matter Theory.
    Novel integrable spin-particle models from gauge theories on a cylinder1998In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 429, p. 336-342Article in journal (Refereed)
  • 276.
    Langmann, Edwin
    KTH, School of Engineering Sciences (SCI), Physics, Mathematical Physics. KTH, School of Engineering Sciences (SCI), Physics, Condensed Matter Theory.
    QCD(1+1) with massless quarks and gauge covariant Sugawara construction1994In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 341, p. 195-204Article in journal (Refereed)
  • 277.
    Langmann, Edwin
    KTH, School of Engineering Sciences (SCI), Physics, Mathematical Physics. KTH, School of Engineering Sciences (SCI), Physics, Condensed Matter Theory.
    Strong coupling gauge theory, quantum spin systems and the spontaneous breaking of chiral symmetry1992In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 297, p. 175-180Article in journal (Refereed)
  • 278.
    Langmann, Edwin
    KTH, School of Engineering Sciences (SCI), Physics, Mathematical Physics. KTH, School of Engineering Sciences (SCI), Physics, Condensed Matter Theory.
    Towards a string representation of infrared SU(2) Yang-Mills theory1999In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 463, p. 252-256Article in journal (Refereed)
  • 279.
    Langmann, Edwin
    et al.
    KTH, Superseded Departments, Physics.
    Szabo, R. J.
    Duality in scalar field theory on noncommutative phase spaces2002In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 533, no 02-jan, p. 168-177Article in journal (Refereed)
    Abstract [en]

    We describe a novel duality symmetry of Phi(2n)(4)-theory defined on noncommutative Euclidean space and with noncommuting momentum coordinates. This duality acts on the fields by Fourier transformation and scaling. It is an extension, to interactions defined with a star-product, of that which arises in quantum field theories of non-interacting scalar particles coupled to a constant background electromagnetic field. The dual models are in general of the same original form but with transformed coupling parameters, while in certain special cases all parameters are essentially unchanged. Using a particular regularization we show, to all orders of perturbation theory, that this duality also persists at the quantum level. We also point out various other properties of this class of noncommutative field theories.

  • 280.
    Langmann, Edwin
    et al.
    KTH, Superseded Departments, Physics.
    Szabo, R. J.
    Zarembo, K.
    Exact solution of noncommutative field theory in background magnetic fields2003In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 569, no 02-jan, p. 95-101Article in journal (Refereed)
    Abstract [en]

    We obtain the exact nonperturbative solution of a scalar field theory defined on a space with noncommuting position and momentum coordinates. The model describes nonlocally interacting charged particles in a background magnetic field. It is an exactly solvable quantum field theory which has nontrivial interactions only when it is defined with a finite ultraviolet cutoff. We propose that small perturbations of this theory can produce solvable models with renormalizable interactions.

  • 281. Lowe, David A.
    et al.
    Thorlacius, Larus
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. Stockholm University, Sweden.
    Black hole complementarity: The inside view2014In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 737, p. 320-324Article in journal (Refereed)
    Abstract [en]

    Within the framework of black hole complementarity, a proposal is made for an approximate interior effective field theory description. For generic correlators of local operators on generic black hole states, it agrees with the exact exterior description in a region of overlapping validity, up to corrections that are too small to be measured by typical infalling observers.

  • 282. Magierski, P.
    et al.
    Wyss, Ramon
    KTH, Superseded Departments, Physics.
    Selfconsistent effective interactions and symmetry restoration2000In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 486, no 02-jan, p. 54-60Article in journal (Refereed)
    Abstract [en]

    The present paper clarifies on the quantum level the concept of selfconsistent interactions and symmetry restoration by means of the generalized scaling fields. It is shown that the concept of symmetry restoration in RPA order fan directly be related to the concept of selfconsistent interations. The difference of the two methods originates from the coupling of the kinetic energy operator to the perturbing field. The presented method is superior to the semiclassical approach. It also yields, in its limiting case, the multipole-multipole effective interaction.

  • 283.
    Malinsky, Michal
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Ohlsson, Tommy
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Xing, Zhi-zhong
    Zhang, He
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Non-unitary neutrino mixing and CP violation in the minimal inverse seesaw model2009In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 679, no 3, p. 242-248Article in journal (Refereed)
    Abstract [en]

    We propose a simplified version of the inverse seesaw model, in which only two pairs of the gauge-singlet neutrinos are introduced, to interpret the observed neutrino mass hierarchy and lepton flavor mixing at or below the TeV scale. This "minimal" inverse seesaw scenario (MISS) is technically natural and experimentally testable. In particular, we show that the effective parameters describing the non-unitary neutrino mixing matrix are strongly correlated in the MISS, and thus, their upper bounds can be constrained by current experimental data in a more restrictive way. The Jarlskog invariants of non-unitary CP violation are calculated, and the discovery potential of such new CP-violating effects in the near detector of a neutrino factory is discussed.

  • 284.
    Melbéus, Henrik
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Merle, Alexander
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Ohlsson, Tommy
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Continuum photon spectrum from Z1Z1 annihilations in universal extra dimensions2012In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 706, no 4-5, p. 329-332Article in journal (Refereed)
    Abstract [en]

    We calculate the continuum photon spectrum from the pair annihilation of a Z1 LKP in non-minimal universal extra dimensions. We find that, due to the preferred annihilation into W+ W- pairs, the continuum flux of collinear photons is relatively small compared to the standard case of the B1 as the LKP. This conclusion applies in particular to the spectral endpoint, where also the additional fermionic contributions are not large enough to increase the flux significantly. When searching for the line signal originating from Z1 Z1 annihilations, this is actually a perfect situation, since the continuum signal can be regarded as background to the smoking gun signature of a peak in the photon flux at an energy that is nearly equal to the mass of the dark matter particle. This signal, in combination with (probably) a non-observation of the continuum signal at lower photon energies, constitutes a perfect handle to probe the hypothesis of the Z1 LKP being the dominant component of the dark matter observed in the Universe.

  • 285.
    Melbéus, Henrik
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics. Royal Inst Technol KTH, Dept Theoret Phys, Sch Engn Sci, S-10691 Stockholm, Sweden..
    Merle, Alexander
    KTH, School of Engineering Sciences (SCI), Theoretical Physics. Royal Inst Technol KTH, Dept Theoret Phys, Sch Engn Sci, S-10691 Stockholm, Sweden..
    Ohlsson, Tommy
    KTH, School of Engineering Sciences (SCI), Theoretical Physics. Royal Inst Technol KTH, Dept Theoret Phys, Sch Engn Sci, S-10691 Stockholm, Sweden..
    Erratum to: Continuum photon spectrum from Z(1)Z(1) annihilations in universal extra dimensions2012In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 713, no 3, p. 350-350Article in journal (Refereed)
  • 286.
    Melbéus, Henrik
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Merle, Alexander
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Ohlsson, Tommy
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Higgs dark matter in UEDs: A good WIMP with bad detection prospects2012In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 715, no 1-3, p. 164-169Article in journal (Refereed)
    Abstract [en]

    We study the first Kaluza-Klein excitation of the Higgs boson in universal extra dimensions as a dark matter candidate. The first-level Higgs boson could be the lightest Kaluza-Klein particle, which is stable due to the conservation of Kaluza-Klein parity, in non-minimal models where boundary localized terms modify the mass spectrum. We calculate the relic abundance and find that it agrees with the observed dark matter density if the mass of the first-level Higgs boson is slightly above 2 TeV, not considering coannihilations and assuming no relative mass splitting among the first-level Kaluza-Klein modes. In the case of coannihilations and a non-zero mass splitting, the mass of the first-level Higgs boson can range from 1 TeV to 4 TeV. We study also the prospects for detection of this dark matter candidate in direct as well as indirect detection experiments. Although the first-level Higgs boson is a typical weakly interacting massive particle, an observation in any of the conventional experiments is very challenging.

  • 287.
    Meyer, HO
    et al.
    Uppsala universitet, Institutionen för kärn- och partikelfysik.
    Knutson, LD
    Balewski, JT
    Daehnick, WW
    Doskow, J
    Haeberli, W
    Lorentz, B
    Pollock, RE
    Pancella, PV
    von, Przewoski B
    Rathmann, F
    Rinckel, T
    Saha, SK
    Schwartz, B
    Thorngren-Engblom, P
    Wellinghausen, A
    Wise, T
    Observation of a large longitudinal analyzing power in a nuclear reaction2000In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 480, no 1-2, p. 7-11Article in journal (Refereed)
    Abstract [en]

    We have measured the longitudinal analyzing power A(z) of the pp --> pp pi(0) reaction at 375 MeV bombarding energy. We find that for certain angle combinations of the outgoing particles the observed A(z) is as large as 0.3, demonstrating that sizeable lo

  • 288. NISIUS, D
    et al.
    JANSSENS, RVF
    FALLON, P
    CROWELL, B
    AHMAD, I
    BEAUSANG, CW
    CARPENTER, MP
    CEDERWALL, BO
    DALY, PJ
    DELEPLANQUE, MA
    DIAMOND, RM
    GASSMANN, D
    GRABOWSKI, ZW
    HENRY, RG
    KHOO, TL
    LAURITSEN, T
    LEE, IY
    MACCHIAVELLI, AO
    MAYER, RH
    STEPHENS, FS
    TWIN, PJ
    IDENTICAL SUPERDEFORMED BAND IN DY-151 - FURTHER EVIDENCE FOR THE PSEUDOSPIN COUPLING SCHEME1995In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 346, no 1-2, p. 15-20Article in journal (Refereed)
    Abstract [en]

    One of the four new excited superdeformed bands found in Dy-151 is characterized by transition energies that lie midway between the gamma-ray energies of the yrast superdeformed band in Dy-152. This result adds significant new information on the issue of ''identical'' bands, as it confirms predictions based on the strong coupling model and the pseudospin coupling scheme.

  • 289.
    Oellers, D.
    et al.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Barion, L.
    Università di Ferrara and INFN, 44100 Ferrara, Italy.
    Barsov, S.
    St. Petersburg Nuclear Physics Institute, 188350 Gatchina, Russia.
    Bechstedt, U.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Benati, P.
    Università di Ferrara and INFN, 44100 Ferrara, Italy.
    Bertelli, S.
    Università di Ferrara and INFN, 44100 Ferrara, Italy.
    Chiladze, D.
    High Energy Physics Institute, Tbilisi State University, 0186 Tbilisi, Georgia.
    Ciullo, G.
    Università di Ferrara and INFN, 44100 Ferrara, Italy.
    Contalbrigo, M.
    INFN, Sezione di Ferrara, 44100 Ferrara, Italy.
    Dalpiaz, P.F.
    Università di Ferrara and INFN, 44100 Ferrara, Italy.
    Dietrich, J.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Dolfus, N.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Dymov, S.
    Physikalisches Institut II, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
    Engels, R.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Erven, W.
    Jülich Center for Hadron Physics, 52425 Jülich, Germany.
    Garishvili, A.
    High Energy Physics Institute, Tbilisi State University, 0186 Tbilisi, Georgia.
    Gebel, R.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Goslawski, P.
    Institut für Kernphysik, Universität Münster, 48149 Münster, Germany.
    Grigoryev, K.
    St. Petersburg Nuclear Physics Institute, 188350 Gatchina, Russia.
    Hadamek, H.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Kacharava, A.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Khoukaz, A.
    Institut für Kernphysik, Universität Münster, 48149 Münster, Germany.
    Kulikov, A.
    Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980 Dubna, Russia.
    Langenberg, G.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Lehrach, A.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Lenisa, P.
    Università di Ferrara and INFN, 44100 Ferrara, Italy.
    Lomidze, N.
    High Energy Physics Institute, Tbilisi State University, 0186 Tbilisi, Georgia.
    Lorentz, B
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Macharashvili, G.
    Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980 Dubna, Russia.
    Maier, R.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Martin, S.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Merzliakov, S.
    Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980 Dubna, Russia.
    Meshkov, I.N.
    Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980 Dubna, Russia.
    Meyer, H.O.
    Physics Department, Indiana University, Bloomington, IN 47405, USA.
    Mielke, M.
    Institut für Kernphysik, Universität Münster, 48149 Münster, Germany.
    Mikirtychiants, M.
    St. Petersburg Nuclear Physics Institute, 188350 Gatchina, Russia.
    Mikirtychiants, S.
    St. Petersburg Nuclear Physics Institute, 188350 Gatchina, Russia.
    Nass, A.
    Physikalisches Institut II, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
    Nekipelov, M.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Nikolaev, N.N.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Nioradze, M.
    High Energy Physics Institute, Tbilisi State University, 0186 Tbilisi, Georgia.
    d'Orsaneo, G.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Papenbrockj, M.
    Institut für Kernphysik, Universität Münster, 48149 Münster, Germany.
    Prasuhn, D.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Rathmann, F.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Sarkadi, J.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    R. Schleichert, R.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Smirnov, A.
    Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980 Dubna, Russia.
    Seyfarth, H.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Sowinski, J.
    Physics Department, Indiana University, Bloomington, IN 47405, USA.
    Spoelgen, D.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Stancari, G.
    INFN, Sezione di Ferrara, 44100 Ferrara, Italy.
    Stancari, M.
    Università di Ferrara and INFN, 44100 Ferrara, Italy.
    Statera, M.
    Università di Ferrara and INFN, 44100 Ferrara, Italy.
    Steffens, E.
    Physikalisches Institut II, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
    Stein, H.J.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Stockhorst, H.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Straatmann, H.
    Zentralabteilung Technologie, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Ströher, H.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Tabidze, M.
    High Energy Physics Institute, Tbilisi State University, 0186 Tbilisi, Georgia.
    Tagliente, G.
    INFN, Sezione di Bari, 70126 Bari, Italy.
    Thörngren Engblom, Pia
    Stockholms universitet, Fysikum.
    Trusov, S.
    Institut für Kern- und Hadronenphysik, Forschungszentrum Rossendorf, 01314 Dresden, Germany.
    Vasilyev, A.
    St. Petersburg Nuclear Physics Institute, 188350 Gatchina, Russia.
    Weidemann, Chr.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Welsch, D.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Wieder, P.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Wüstner, P.
    Zentralinstitut für Elektronik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Zupranski, P.
    Department of Nuclear Reactions, Andrzej Soltan, Institute for Nuclear Studies, 00-681 Warsaw, Poland.
    Polarizing a stored proton beam by spin flip?2009In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 674, no 4-5, p. 269-275Article in journal (Refereed)
    Abstract [en]

    We discuss polarizing a proton beam in a storage ring, either by selective removal or by spin flip of the stored ions. Prompted by recent, conflicting calculations, we have carried out a measurement of the spin-flip cross section in low-energy electron–proton scattering. The experiment uses the cooling electron beam at COSY as an electron target. The measured cross sections are too small for making spin flip a viable tool in polarizing a stored beam. This invalidates a recent proposal to use co-moving polarized positrons to polarize a stored antiproton beam.

  • 290.
    Ohlsson, Tommy
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Bimaximal fermion mixing from the quark and leptonic mixing matrices2005In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 622, no 02-jan, p. 159-164Article in journal (Refereed)
    Abstract [en]

    In this Letter. we show how the mixing angles of the standard parameterization add when multiplying the quark and leptonic mixing matrices. i.e., we derive explicit sum rules for the quark and leptonic mixing angles. In this connection, we also discuss other recently proposed sum rules for the mixing angles assuming bimaximal fermion mixing. In addition, we find that the present experimental and phenomenological data of the mixing angles naturally fulfill our sum rules, and thus, give rise to bilarge or bimaximal fermion mixing.

  • 291.
    Ohlsson, Tommy
    KTH, Superseded Departments, Physics.
    Effects and influences on neutrino oscillations due to a thin density layer perturbation added to a matter density profile2001In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 522, no 04-mar, p. 280-286Article in journal (Refereed)
    Abstract [en]

    In this Letter, we show the effects on the transition probabilities for neutrino oscillations due to a thin constant density layer perturbation added to an arbitrary matter density profile, In the case of two neutrino flavors, we calculate the effects both analytically and numerically, whereas in the case of three neutrino flavors, we perform the studies purely numerically. As an realistic example we consider the effects of the Earth's atmosphere when added to the Earth's matter density profile on the neutrino oscillation transition probabilities for atmospheric neutrinos.

  • 292.
    Ohlsson, Tommy
    KTH, Superseded Departments, Physics.
    Equivalence between Gaussian averaged neutrino oscillations and neutrino decoherence2001In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 502, no 04-jan, p. 159-166Article in journal (Refereed)
    Abstract [en]

    In this Letter, we show that a Gaussian averaged neutrino oscillation model is equivalent to a neutrino decoherence model. Without loss of generality, the analysis is performed with two neutrino flavors. We also estimate the damping (or decoherence) parameter for atmospheric neutrinos and compare it to earlier obtained results.

  • 293.
    Ohlsson, Tommy
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Popa, Christoph
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Zhang, He
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Non-unitarity of the leptonic mixing matrix in the TeV-scale type-I seesaw model2010In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 692, no 4, p. 257-260Article in journal (Refereed)
    Abstract [en]

    The non-unitarity effects in leptonic flavor mixing are regarded as one of the generic features of the type-1 seesaw model. Therefore, we explore these effects in the TeV-scale type-1 seesaw model, and show that there exist non-trivial correlations among the non-unitarity parameters, stemming from the typical flavor structure of the low-scale seesaw model. In general, it follows from analytical discussions and numerical results that all the six non-unitarity parameters are related to three model parameters, while the widely studied parameters eta(e tau) and eta(mu tau) cannot be phenomenologically significant simultaneously.

  • 294.
    Ohlsson, Tommy
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Riad, Stella
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Running of neutrino parameters and the Higgs self-coupling in a six-dimensional UED model2013In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 718, no 3, p. 1002-1007Article in journal (Refereed)
    Abstract [en]

    We investigate a six-dimensional universal extra-dimensional model in the extension of an effective neutrino mass operator. We derive the β-functions and renormalization group equations for the Yukawa couplings, the Higgs self-coupling, and the effective neutrino mass operator in this model. Especially, we focus on the renormalization group running of physical parameters such as the Higgs self-coupling and the leptonic mixing angles. The recent measurements of the Higgs boson mass by the ATLAS and CMS Collaborations at the LHC as well as the current three-flavor global fits of neutrino oscillation data have been taken into account. We set a bound on the six-dimensional model, using the vacuum stability criterion, that allows five Kaluza-Klein modes only, which leads to a strong limit on the cutoff scale. Furthermore, we find that the leptonic mixing angle θ12 shows the most sizeable running, and that the running of the angles θ13 and θ23 are negligible. Finally, it turns out that the findings in this six-dimensional model are comparable with what is achieved in the corresponding five-dimensional model, but the cutoff scale is significantly smaller, which means that it could be detectable in a closer future.

  • 295.
    Ohlsson, Tommy
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Schwetz, Thomas
    Zhang, He
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Non-standard neutrino interactions in the Zee-Babu model2009In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 681, no 3, p. 269-275Article in journal (Refereed)
    Abstract [en]

    We investigate non-standard neutrino interactions (NSIs) in the Zee-Babu model. The size of NSIs predicted by this model is obtained from a full scan over the parameter space. taking into account constraints from low-energy experiments such as searches for lepton flavor violation (LFV) and the requirement to obtain a viable neutrino mass matrix. The dependence on the scale of new physics as well as on the type of the neutrino mass hierarchy is discussed. We find that NSIs at the source of a future neutrino factory may be at an observable level in the nu(e) -> nu(tau) and/or nu(mu) -> nu(tau) channels. In particular, if the doubly charged scalar of the model has a mass in reach of the LHC and if the neutrino mass hierarchy is inverted, a highly predictive scenario is obtained with observable signals at the LHC, in upcoming neutrino oscillation experiments, in LFV processes, and for NSIs at a neutrino factory.

  • 296.
    Ohlsson, Tommy
    et al.
    KTH, Superseded Departments, Physics.
    Seidl, Gerhart
    Bilarge leptonic mixing from Abelian horizontal symmetries2002In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 537, no 02-jan, p. 95-102Article in journal (Refereed)
    Abstract [en]

    We construct and present a model for leptonic mixing based on higher-dimensional operators, using the Froggatt-Nielsen mechanism. and Abelian horizontal symmetries (flavor symmetries) of continuous and discrete type. Our model naturally yields bilarge leptonic mixing. coming from both the charged leptons and the neutrinos, and an inverted neutrino mass hierarchy spectrum. The obtained values of the parameters, i.e.. the leptonic mixing parameters and the neutrino mass squared differences, are all consistent with the atmospheric neutrino data and the Mikheyev-Smirnov-Wolfenstein large mixing angle solution for the solar neutrino problem.

  • 297.
    Ohlsson, Tommy
    et al.
    KTH, Superseded Departments, Physics.
    Snellman, Håkan
    KTH, Superseded Departments, Physics.
    Neutrino oscillations with three flavors in matter: Applications to neutrinos traversing the earth2000In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 474, no 1-2, p. 153-162Article in journal (Refereed)
    Abstract [en]

    Analytic formulas are presented for three flavor neutrino oscillations in matter in the plane wave approximation. We calculate in particular the time evolution operator in both mass and flavor bases. We also find the transition probabilities expressed as functions of the vacuum mass squared differences, the vacuum mixing angles, and the matter density parameter. The application of this to neutrino oscillations for both atmospheric and long baseline neutrinos in a mantle-core-mantle step function model of the Earth's matter density profile is discussed.

  • 298.
    Ohlsson, Tommy
    et al.
    KTH, Superseded Departments, Physics.
    Winter, Walter
    Reconstruction of the Earth's matter density profile using a single neutrino baseline2001In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 512, no 04-mar, p. 357-364Article in journal (Refereed)
    Abstract [en]

    In this Letter, we show numerically that a symmetric Earth matter density profile can, in principle, be reconstructed from a single baseline energy spectrum up to a certain precision. For the numerical evaluations in the high-dimensional parameter space we use a genetic algorithm.

  • 299.
    Ohlsson, Tommy
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Zhang, He
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Non-standard interaction effects at reactor neutrino experiments2009In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 671, no 1, p. 99-104Article in journal (Refereed)
    Abstract [en]

    We study non-standard interactions (NSIs) at reactor neutrino experiments, and in particular, the mimicking effects on theta(13). We present generic formulas for oscillation probabilities including NSIs from sources and detectors. Instructive mappings between the fundamental leptonic mixing parameters and the effective leptonic mixing parameters are established. In addition, NSI corrections to the mixing angles theta(13) and theta(12) are discussed in detailed. Finally, we show that, even for a vanishing theta(13), all Oscillation phenomenon may still be observed ill future short baseline reactor neutrino experiments, such as Double Chooz and Daya Bay, due to the existences of NSIs.

  • 300.
    Ohlsson, Tommy
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Zhang, He
    Zhou, Shun
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Nonstandard interaction effects on neutrino parameters at medium-baseline reactor antineutrino experiments2014In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 728, p. 148-155Article in journal (Refereed)
    Abstract [en]

    Precision measurements of leptonic mixing parameters and the determination of the neutrino mass hierarchy are the primary goals of the forthcoming medium-baseline reactor antineutrino experiments, such as JUNO and RENO-50. In this work, we investigate the impact of nonstandard neutrino interactions (NSIs) on the measurements of {sin(2) theta(12), Delta m(21)(2)} and {sin(2) theta(13), Delta m(31)(2)}. and on the sensitivity to the neutrino mass hierarchy, at the medium-baseline reactor experiments by assuming a typical experimental setup. It turns out that the true mixing parameter sin(2) theta(12) can be excluded at a more than 3 sigma level if the NSI parameter epsilon(e mu), or epsilon(e tau), is as large as 2% in the most optimistic case. However, the discovery reach of NSI effects has been found to be small, and depends crucially on the CP-violating phases. Finally, we show that NSI effects could enhance or reduce the discrimination power of the JUNO and RENO-50 experiments between the normal and inverted neutrino mass hierarchies.

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