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  • 201. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Lager, Sara
    Strandberg, Jonas
    Zverev, E.G.
    et al.,
    Search for single top quark production in pp collisions at root s=1.96 TeV2005Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 622, nr 3-4, s. 265-276Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a search for electroweak production of single top quarks in the s-channel and t-channel using neural networks for signal-background separation. We have analyzed 230 pb(-1) of data collected with the DO detector at the Fermilab Tevatron Collider at a center-of-mass energy of 1.96 TeV and find no evidence for a single top quark signal. The resulting 95% confidence level upper limits on the single top quark production cross sections are 6.4 pb in the s-channel and 5.0 ph in the t-channel.

  • 202. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Measurement of beta (t -> Wb)/beta(t -> Wq) at root s=1.96 TeV2006Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 639, nr 6, s. 616-622Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present the measurement of R = B(t -> Wb)/B(t -> Wq) in pp collisions at root s = 1.96 TeV, using 230 pb(-1) of data collected by the DO experiment at the Fermilab Tevatron Collider. We fit simultaneously R and the number (N-tt) of selected top quark pairs (tt), to the number of identified b-quark jets in events with one electron or one muon, three or more jets, and high transverse energy imbalance. To improve sensitivity, kinematical properties of events with no identified b-quark jets are included in the fit. We measure R = 1.03(-0.17)(0.19) (stat + syst), in good agreement with the standard model. We set lower limits of R > 0.61 and vertical bar V-tb vertical bar > 0.78 at 95% confidence level.

  • 203. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Measurement of the isolated photon cross section in p(p)over-bar collisions at root s=1.96 TeV2006Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 639, nr 3-4, s. 151-158Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The cross section for the inclusive production of isolated photons has been measured in p (p) over bar collisions at root s = 1.96 TeV with the DO detector at the Fermilab Tevatron Collider. The photons span transverse momenta 23 to 300 GeV and have pseudorapidity vertical bar n vertical bar < 0.9. The cross section is compared with the results from two next-to-leading order perturbative QCD calculations. The theoretical predictions agree with the measurement within uncertainties.

  • 204. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for pair production of second generation scalar leptoquarks in p(p)over-bar collisions at root s-=1.96 TeV2006Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 636, nr 3-4, s. 183-190Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on a search for the pair production of second generation scalar leptoquarks (LQ(2)) in p (p) over bar collisions at the center-of-mass energy, root s = 1.96 TeV, using data corresponding to an integrated luminosity of 294 19 pb(-1) recorded with the DO detector. No evidence for a leptoquark signal in the LQ(2)LQ(2) -> mu q mu q channel has been observed, and upper bounds on the product of cross section times branching fraction were set. This yields lower mass limits of m(LQ2) > 247 GeV/c(2) for beta = B(LQ(2) -> mu q) = 1 and m(LQ2) > 182 GeV/c(2) for beta = 1/2. Combining these limits with previous DO results, the lower limits on the mass of a second generation scalar leptoquark are m(LQ2) > 251 GeV/c(2) and m(LQ2) > 204 GeV/c(2) for beta = I and beta = 1/2, respectively.

  • 205. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for particles decaying into a Z boson and a photon in p(p)over-bar collisions at root s=1.96 TeV2006Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 641, nr 6, s. 415-422Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present the results of a search for a new particle X produced in p (p) over bar collisions at root s- = 1.96 TeV and subsequently decaying to Z gamma. The search uses 0.3 fb(-1) of data collected with the DO detector at the Fermilab Tevatron Collider. We set limits on the production cross section times the branching fraction sigma(p (p) over bar -> X) x B(X -> Z gamma) that range from 0.4 to 3.5 pb at the 95% C.L. for X with invariant masses between 100 and 1000 GeV/c(2), over a wide range of X decay widths.

  • 206. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for R-parity violating supersymmetry via the LL(E)over-bar couplings lambda(121), lambda(122) or lambda(133) in p(p)over-bar collisions at root s=1.96 TeV2006Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 638, nr 5-6, s. 441-449Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A search for gaugino pair production with a trilepton signature in the framework of R-parity violating supersymmetry via the couplings; lambda(121), lambda(122), or lambda(133) is presented. The data, corresponding to an integrated luminosity of L approximate to 360 pb(-1), were collected from April 2002 to August 2004 with the D0 detector at the Fermilab Tevatron Collider, at a center-of-mass energy of root s = 1.96 TeV. This analysis considers final states with three charged leptons with the flavor combinations eel, mu mu l, and ee tau (l = e or mu). No evidence for supersymmetry is found and limits at the 95% confidence level are set on the gaugino pair production cross section and lower bounds on the masses of the lightest neutralino and chargino are derived in two supersymmetric models.

  • 207. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for scalar leptoquarks in the acoplanar jet topology in p(p)over-bar collisions at root s=1.96 TeV2006Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 640, nr 5-6, s. 230-237Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A search for leptoquarks has been performed in 310 pb-1 of data from p over(p, ̄) collisions at a center-of-mass energy of 1.96 TeV, collected by the D0 detector at the Fermilab Tevatron Collider. The topology analyzed consists of acoplanar jets with missing transverse energy. The data show good agreement with standard model expectations, and a lower mass limit of 136 GeV has been set at the 95% C.L. for a scalar leptoquark decaying exclusively into a quark and a neutrino.

  • 208. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for squarks and gluinos in events with jets and missing transverse energy in p(p)over-bar collisions at root s-=1.96 TeV2006Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 638, nr 2-3, s. 119-127Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The results of a search for squarks and gluinos using data from p (p) over bar collisions recorded at a center-of-mass energy of 1.96 TeV by the DO detector at the Fermilab Tevatron Collider are reported. The topologies analyzed consist of acoplanar-jet and multijet events with large missing transverse energy. No evidence for the production of squarks or gluinos was found in a data sample of 310pb(-1). Lower limits of 325 and 241 GeV were derived at the 95% C.L. on the squark and gluino masses, respectively, within the framework of minimal supergravity with tan beta=3, A(0) = 0, and mu < 0.

  • 209. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for W ' boson production in the W ' -> t(b)over-bar decay channel2006Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 641, nr 6, s. 423-431Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a search for the production of a new heavy gauge boson W' that decays to a top quark and a bottom quark. We have analyzed 230 pb(-1) of data collected with the DO detector at the Fermilab Tevatron collider at a center-of-mass energy of 1.96 TeV. No significant excess of events above the standard model expectation is found in any region of the final state invariant mass distribution. We set upper limits on the production cross section of W' bosons times branching ratio to top quarks at the 95% confidence level for several different W, boson masses. We exclude masses between 200 and 610 GeV for a W' boson with standard-model-like couplings, between 200 and 630 GeV for a W, boson with right-handed couplings that is allowed to decay to both leptons and quarks, and between 200 and 670 GeV for a W' boson with right-handed couplings that is only allowed to decay to quarks.

  • 210.
    Abazov, V. M.
    et al.
    Joint Inst Nucl Res, Dubna, Russia..
    Åsman, Bengt
    KTH.
    Clement, Christophe
    KTH.
    Gollub, Nils
    KTH.
    Lager, S.
    Lund Univ, Lund, Sweden.;Royal Inst Technol, Stockholm, Sweden.;Stockholm Univ, S-10691 Stockholm, Sweden.;Uppsala Univ, Uppsala, Sweden..
    Soeldner-Rembold, S.
    Univ Manchester, Manchester, Lancs, England..
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Search for particles decaying into a Z boson and a photon in collisions p (p)over-bar at root s = 1.96 TeV (vol 641, pg 415, 2006)2009Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 670, nr 4-5, s. 455-458Artikel i tidskrift (Refereegranskat)
  • 211.
    Abazov, V. M.
    et al.
    Joint Inst Nucl Res, Dubna, Russia..
    Åsman, Björn
    KTH.
    Bandurin, D. V.
    Kansas State Univ, Manhattan, KS 66506 USA..
    Belanger-Champagne, C.
    Lund Univ, Lund, Sweden.;Royal Inst Technol, Stockholm, Sweden.;Stockholm Univ, S-10691 Stockholm, Sweden.;Uppsala Univ, Uppsala, Sweden..
    Clement, C.
    Lund Univ, Lund, Sweden.;Royal Inst Technol, Stockholm, Sweden.;Stockholm Univ, S-10691 Stockholm, Sweden.;Uppsala Univ, Uppsala, Sweden..
    Gollub, Nils
    KTH.
    Hansson, P.
    KTH.
    Strandberg, S
    KTH.
    Measurement of the isolated photon cross section in p(p)over-bar collisions at root s = 1.96 TeV (vol 639, pg 151, 2006)2008Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 658, nr 5, s. 285-289Artikel i tidskrift (Refereegranskat)
  • 212. Abazov, V.M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Measurement of sigma(p(p)over-bar -> Z plus X)Br(Z -> tau(+)tau(-)) at root s=1.96 TeV2009Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 670, nr 4-5, s. 292-299Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a measurement of the cross section for Z boson production times the branching fraction to tau lepton pairs sigma(p (p) over bar -> Z + X)Br(Z -> tau(+)tau(-)) in p (p) over bar collisions at root s = 1.96 TeV. The measurement is performed in the channel in which one tau lepton decays into a muon and neutrinos. and the other tau lepton decays hadronically or into an electron and neutrinos. The data sample corresponds to an integrated luminosity of 1.0 fb(-1) collected with the DO detector at the Fermilab Tevatron Collider. The sample contains 1511 candidate events with an estimated 20% background from jets or muons misidentified as tau leptons. We obtain sigma . Br = 240 +/- 8 (star) +/- 12 (sys) +/- 15 (lum) pb, which is consistent with the standard model prediction.

  • 213. Abazov, V.M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Search for a scalar or vector particle decaying into Z gamma in p(p)over-bar collisions at root s=1.96 TeV2009Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 671, nr 3, s. 349-355Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a search for a narrow scalar or vector resonance decaying into Z gamma with a subsequent Z boson decay into a pair of electrons or moons. The data for this search were collected with the D circle divide detecror at the Fermilab Tevatron p (p) over bar collider at a center of mass energy root s = 1.96 TeV. Using 1.1 (1.0) fb(-1) of data, we observe 49 (50) candidate events in the electron (muon) channel, in good agreement with the standard model prediction. From the combination of both channels, we derive 95% C.L. upper limits on the cross section times branching fraction (sigma x B) into Z gamma. These limits range from 0.19 (0.20) pb for a scalar (vector) resonance mass of 600 GeV/c(2) to 2.5 (3.1) pb for a mass of 140 GeV/c(2).

  • 214. Akrami, Yashar
    et al.
    Hassan, S. F.
    Koennig, Frank
    Schmidt-May, Angnis
    Solomon, Adam R.
    Bimetric gravity is cosmologically viable2015Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 748, s. 37-44Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bimetric theory describes gravitational interactions in the presence of an extra spin-2 field. Previous work has suggested that its cosmological solutions are generically plagued by instabilities. We show that by taking the Planck mass for the second metric, M-f, to be small, these instabilities can be pushed back to unobservably early times. In this limit, the theory approaches general relativity with an effective cosmological constant which is, remarkably, determined by the spin-2 interaction scale. This provides a late-time expansion history which is extremely close to Lambda CDM, but with a technically-natural value for the cosmological constant. We find M-f should be no larger than the electroweak scale in order for cosmological perturbations to be stable by big-bang nucleosynthesis. We further show that in this limit the helicity-0 mode is no longer strongly-coupled at low energy scales. (C) 2015 The Authors. Published by Elsevier B.V.

  • 215.
    Angelopoulos, A.
    et al.
    -.
    Apostolakis, A.
    -.
    Aslanides, E.
    -.
    Backenstoss, G.
    -.
    Bargassa, P.
    -.
    Behnke, O.
    -.
    Benelli, A.
    -.
    Bertin, V.
    -.
    Blanc, F.
    -.
    Bloch, P.
    -.
    Danielsson, Mats
    KTH, Tidigare Institutioner, Fysik.
    K 0–K̄0 mass and decay-width differences: CPLEAR evaluation1999Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 471, nr 2, s. 332-338Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The CPT-violation parameters Re(δ) and Im(δ) determined recently by CPLEAR are used to evaluate the K0 mass and decay-width differences, as given by the difference between the diagonal elements of the neutral-kaon mixing matrix (M−iΓ/2). The results – GeV and GeV – are consistent with CPT invariance. The CPT invariance is also shown to hold within a few times 10−3–10−4 for many of the amplitudes describing neutral-kaon decays to different final states.

  • 216.
    Angelopoulos, Angelos
    et al.
    -.
    Aslanides, E.
    -.
    Backenstoss, G.
    -.
    Bargassa, P.
    -.
    Behnke, O.
    -.
    Benelli, A.
    -.
    Bertin, V.
    -.
    Blanc, F.
    -.
    Bloch, P.
    -.
    Carlson, P.
    -.
    Danielsson, Mats
    KTH, Tidigare Institutioner, Fysik.
    K0⇋ K̄0 transitions monitored by strong interactions: a new determination of the K L–K S mass difference2001Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 503, nr 1, s. 49-57Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The CPLEAR set-up (modified) has been used to determine the KL–KS mass difference by a method where neutral-kaon strangeness oscillations are monitored through kaon strong interactions, rather than semileptonic decays, thus requiring no assumptions on CPT invariance for the decay amplitudes. The result, Δm=(0.5343±0.0063stat±0.0025syst)×1010ℏ/s, provides a valuable input for CPT tests.

  • 217. Apostolakis, A
    et al.
    Aslanides, E.
    -.
    Backenstoss, G.
    -.
    Bargassa, P.
    -.
    Behnke, O.
    -.
    Benelli, A.
    -.
    Bertin, V.
    -.
    Blanc, F.
    -.
    Bloch, P.
    -.
    Carlson, P.
    KTH, Skolan för teknikvetenskap (SCI).
    Danielsson, Mats
    KTH, Tidigare Institutioner, Fysik.
    A determination of the CP violation parameter η+- from the decay of strangeness-tagged neutral kaons1999Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 458, nr 4, s. 545-552Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    LEAR offered unique opportunities to study the symmetries which exist between matter and antimatter. At variance with other approaches at this facility, CPLEAR was an experiment devoted to the study of CP, T and CPT symmetries in the neutral-kaon system. A variety of measurements allowed us to determine with high precision the parameters which describe the time evolution of the neutral kaons and their antiparticles, including decay amplitudes, and the related symmetry properties. Limits concerning quantum-mechanical predictions (EPR, coherence of the wave function) or the equivalence principle of general relativity have been obtained. An account of the main features of the experiment and its performances is given here, together with the results achieved.

  • 218.
    Apostolakis, A.
    et al.
    -.
    Aslanides, E.
    -.
    Backenstoss, G.
    -.
    Bargassa, P.
    -.
    Behnke, O.
    -.
    Benelli, A.
    -.
    Bertin, V.
    -.
    Blanc, F.
    -.
    Bloch, P.
    -.
    Carlson, P.
    Danielsson, Mats
    KTH, Tidigare Institutioner, Fysik.
    Measurement of the energy dependence of the form factor f+ in K 0 e3 decay2000Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 473, nr 1, s. 186-192Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Neutral-kaon decays to πeν were analysed to determine the q2 dependence of the K0e3 electroweak form factor f+. Based on 365612 events, this form factor was found to have a linear dependence on q2 with a slope λ+=0.0245±0.0012stat±0.0022syst.

  • 219. Arnlind, Joakim
    et al.
    Hoppe, Jens
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Matematik (Avd.). Sogang University, South Korea .
    The world as quantized minimal surfaces2013Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 723, nr 4-5, s. 397-400Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is pointed out that the equations Sigma(d)(i=1)[X-i, [X-i, X-j]] = 0 (and its super-symmetrizations, playing a central role in M-theory matrix models) describe non-commutative minimal surfaces - and can be solved as such.

  • 220.
    Arnlind, Joakim
    et al.
    KTH, Tidigare Institutioner, Matematik.
    Hoppe, Jens
    KTH, Tidigare Institutioner, Matematik.
    Theisen, Stefan
    Albert Einstein Inst.
    Spinning Membranes2004Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 599, nr 1-2, s. 118-128Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present new solutions of the classical equations of motion of bosonic (matrix-)membranes. Those relating to minimal surfaces in spheres provide spinning membrane solutions in AdS(p) X S-q, as well as in flat space-time. Nontrivial reductions of the BMN matrix model equations are also given.

  • 221. ATLAS Collaboration,
    et al.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    et al.,
    Measurement of exclusive γγ→ℓ+ℓ- production in proton-proton collisions at √s=7 TeV with the ATLAS detector2015Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 749, s. 242-261Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This Letter reports a measurement of the exclusive γγ→ℓ+ℓ- (ℓ=e, μ) cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV by the ATLAS experiment at the LHC, based on an integrated luminosity of 4.6 fb-1. For the electron or muon pairs satisfying exclusive selection criteria, a fit to the dilepton acoplanarity distribution is used to extract the fiducial cross-sections. The cross-section in the electron channel is determined to be σγγ→e+e-excl.=0.428 ± 0.035 (stat.) ± 0.018 (syst.) pb for a phase-space region with invariant mass of the electron pairs greater than 24 GeV, in which both electrons have transverse momentum pT>12 GeV and pseudorapidity |η|<2.4. For muon pairs with invariant mass greater than 20 GeV, muon transverse momentum pT>10 GeV and pseudorapidity |η|<2.4, the cross-section is determined to be σγγ→μ+μ-excl.=0.628 ± 0.032 (stat.) ± 0.021 (syst.) pb. When proton absorptive effects due to the finite size of the proton are taken into account in the theory calculation, the measured cross-sections are found to be consistent with the theory prediction.

  • 222. Augustyniak, W.
    et al.
    Barion, L.
    Barsov, S.
    Bechstedt, U.
    Benati, P.
    Bertelli, S.
    Carassiti, V.
    Chiladze, D.
    Ciullo, G.
    Contalbrigo, M.
    Dalpiaz, P. F.
    Dymov, S.
    Engels, R.
    Erwen, W.
    Fiorini, M.
    Gaisser, M.
    Gebel, R.
    Goslaswski, P.
    Grigoriev, K.
    Guidoboni, G.
    Kacharava, A.
    Khoukaz, A.
    Kulikov, A.
    Kleines, H.
    Langenberg, G.
    Lehrach, A.
    Lenisa, P.
    Lomidze, N.
    Lorentz, B.
    Macharashvili, G.
    Maier, R.
    Marianski, B.
    Martin, S.
    McHedlishvili, D.
    Merzliakov, S.
    Meshkov, I. N.
    Meyer, H. O.
    Mielke, M.
    Mikirtychiants, M.
    Mikirtychiants, S.
    Nass, A.
    Nekipelov, M.
    Nikolaev, N.
    Nioradze, M.
    Oellers, D.
    Papenbrock, M.
    Pappalardo, L.
    Pesce, A.
    Polyanskiy, A.
    Prasuhn, D.
    Rathmann, F.
    Sarkadi, J.
    Smirnov, A.
    Seyfarth, H.
    Shmakova, V.
    Statera, M.
    Steffens, E.
    Stein, H. J.
    Stockhorst, H.
    Straatman, H.
    Ströher, H.
    Tabidze, M.
    Tagliente, G.
    Thörngren Engblom, Pia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Trusov, S.
    Trzcinski, A.
    Valdau, Y.
    Vasiliev, A.
    von Würtemberg, K. M.
    Weidemann, C.
    Wüstner, P.
    Zupranski, P.
    Polarization of a stored beam by spin-filtering2012Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 718, nr 1, s. 64-69Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The PAX Collaboration has successfully performed a spin-filtering experiment with protons at the COSY-ring. The measurement allowed the determination of the spin-dependent polarizing cross section, that compares well with the theoretical prediction from the nucleon-nucleon potential. The test confirms that spin-filtering can be adopted as a method to polarize a stored beam and that the present interpretation of the mechanism in terms of the proton-proton interaction is correct. The outcome of the experiment is of utmost importance in view of the possible application of the method to polarize a beam of stored antiprotons.

  • 223. Babaev, Egor
    Mass generation without symmetry breakdown in the chiral Gross-Neveu model at finite temperature and finite N in 2+1 dimensions2001Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 497, nr 04-mar, s. 323-327Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The chiral Gross-Neveu model is one of the most popular toy models for QCD being a generic testing field for many ideas in particle physics. It has been studied in the past in detail in the limit of infinite number of flavors of fermions. Quite astonishingly, the study of this model was not carried through in all its facets. The most important omission is the study of the onset of quasi-long-range order in the decoupled massless phase field. The present work eliminates this deficiency. In this paper we derive behavior of the Kosterlitz-Thouless transition in this model at finite temperature in 2 + 1 dimensions in the regime when the number N of field components is large but finite. We also prove the anticipated before key feature of the model, namely, that in the regime of infinite N the temperature of the Kosterlitz-Thouless transition merges with the critical temperature T*, given by a mean-field equation for the gap modulus, thus recovering the BCS-like scenario [(T* - T-KT)/T* --> 0] of the phase transition at N --> infinity.

  • 224.
    Ban, Shufang
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Meng, J.
    Satula, W.
    Wyss, Ramon
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Nuclear symmetry energy in relativistic mean field theory2006Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 633, nr 2-3, s. 231-236Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The physical origin of the nuclear symmetry energy is studied within the relativistic mean field (RMF) theory. Based on the nuclear binding energies calculated with and without mean isovector potential for several isobaric chains we confirm earlier Skyrme-Hartree-Fock result that the nuclear symmetry energy strength depends on the mean level spacing epsilon(A) and an effective mean isovector potential strength K(A). A detailed analysis of the isospin dependence of these two components contributing to the nuclear symmetry energy reveals a quadratic dependence due to the mean-isoscalar potential, similar to epsilon T-2, and, completely unexpectedly, the presence of a strong linear component similar to kappa T(T + 1 + epsilon/kappa) in the isovector potential. The latter generates a nuclear symmetry energy in RMF theory that is proportional to E-sym similar to T(T + 1) at variance to the non-relativistic calculation. The origin of the linear term in RMF theory needs to be further explored.

  • 225.
    Baum, Sebastian
    et al.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Stockholm Univ, Dept Phys, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden.;Stockholm Univ, Roslagstullsbacken 23, S-10691 Stockholm, Sweden..
    Freese, Katherine
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Stockholm Univ, Dept Phys, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden.; Stockholm Univ, Roslagstullsbacken 23, S-10691 Stockholm, Sweden.;Univ Michigan, Dept Phys, Leinweber Ctr Theoret Phys, Ann Arbor, MI 48109 USA..
    Kelso, Chris
    Univ North Florida, Dept Phys, Jacksonville, FL 32224 USA..
    Dark Matter implications of DAMA/LIBRA-phase2 results2019Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 789, s. 262-269Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recently, the DAMA/LIBRA collaboration released updated results from their search for the annual modulation signal from Dark Matter (DM) scattering in the detector. Besides approximately doubling the exposure of the DAMA/LIBRA data set, the updated photomultiplier tubes of the experiment allow a lower recoil energy threshold of I keV electron equivalent compared to the previous threshold of 2 keV electron equivalent. We study the compatibility of the observed modulation signal with DM scattering. Due to a conspiracy of multiple effects, the new data at low recoil energies is very powerful for testing the DM hypothesis. We find that canonical (isospin conserving) spin-independent DM-nucleon interactions are no longer a good fit to the observed modulation signal in the standard halo model. The canonical spin independent case is disfavored by the new data, with best fit points of a DM mass of similar to 8 GeV, disfavored by 5.2 sigma, or a mass of similar to 54GeV, disfavored by 2.5 sigma. Allowing for isospin violating spin independent interactions, we find a region with a good fit to the data with suppressed effective couplings to iodine for DM masses of similar to 10 GeV. We also consider spin-dependent DM-nucleon interactions, which yield good fits for similar DM masses of similar to 10 GeV or similar to 45 GeV. Elsevier B.V.

  • 226. Beausang, C W
    et al.
    Fallon, P
    Appelbe, D E
    Aztalos, S
    Clark, R M
    Clarke, S
    Cederwall, Bo
    Deleplanque, M A
    Diamond, R M
    Erturk, S
    Kelly, W
    Lee, I Y
    Macchaivelli, A O
    Patterson, D C
    Smith, M B
    Stephens, F S
    Twin, P J
    Wilson, A N
    Lifetimes of yrast and excited superdeformed states in Gd-150: effect of particle-hole excitations on the deformation1998Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 417, nr 1-2, s. 13-19Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The quadrupole moments and deformations have been measured for six superdeformed bands in Gd-150. The results indicate evidence for deformation driving properties of both the high-hi intruder and also low-N natural parity states at the superdeformed Fermi surface. Several new transitions have been identified and placed in the low spin non-yrast portion of one of the SD bands.

  • 227.
    Bergström, Johannes
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Teoretisk partikelfysik.
    Ohlsson, Tommy
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Teoretisk partikelfysik.
    Zhang, He
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Teoretisk partikelfysik.
    Threshold effects on renormalization group running of neutrino parameters in the low-scale seesaw model2011Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 698, nr 4, s. 297-305Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We show that, in the low-scale type-I seesaw model, renormalization group running of neutrino parameters may lead to significant modifications of the leptonic mixing angles in view of so-called seesaw threshold effects. Especially, we derive analytical formulas for radiative corrections to neutrino parameters in crossing the different seesaw thresholds, and show that there may exist enhancement factors efficiently boosting the renormalization group running of the leptonic mixing angles. We find that, as a result of the seesaw threshold corrections to the leptonic mixing angles, various flavor symmetric mixing patterns (e.g., bi-maximal and tri-bimaximal mixing patterns) can be easily accommodated at relatively low energy scales, which is well within the reach of running and forthcoming experiments (e.g., the LHC).

  • 228.
    Betan, Rodolfo Id
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Liotta, Roberto J.
    KTH, Tidigare Institutioner, Fysik.
    Sandulescu, Nicolae
    Vertse, Tamas
    KTH, Tidigare Institutioner, Fysik.
    A shell model representation with antibound states2004Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 584, nr 1-2, s. 48-57Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An unified shell model scheme is introduced that evaluates simultaneously the contributions of bound single-particle states, Gamow resonances and antibound states to processes occurring in the continuum part of nuclear spectra. This new scheme allows us to study the effect of the antibound pole and the remaining part of the complex continuum separately. The calculations, performed in the complex energy plane, are applied to the study of weakly bound nuclei. The influence of antibound states upon physical quantities in light as well as in heavy nuclei is assessed.

  • 229.
    Bette, Andreas
    et al.
    KTH.
    de Azcarraga, J A
    Lukierski, J
    Miquel-Espanya, C
    Massive relativistic free fields with Lorentz spins and electric charges2004Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 595, s. 491-497Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The sixteen real coordinates of two-twistor space are transformed by a nonlinear mapping into an enlarged space-time framework. The standard relativistic phase space of coordinates (X-mu, P-mu) is supplemented by a six-parameter spin phase manifold (two pairs (eta(alpha), sigma(alpha)) and ((&eta;) over bar (alpha), (&sigma;) over bar (alpha)) of canonically conjugated Weyl spinors constrained by two second class constraints) and the electric charge phase space (e, phi). The free two-twistor classical mechanics is rewritten in this enlarged relativistic phase space as a model for a relativistic particle. Definite values for the mass, spin and the electric charge of the particle are introduced by means of three first class constraints.

  • 230. Bi, Huan-Yu
    et al.
    Wu, Xing-Gang
    Ma, Yang
    Ma, Hong-Hao
    Brodsky, Stanley J.
    Mojaza, Matin
    Degeneracy relations in QCD and the equivalence of two systematic all-orders methods for setting the renormalization scale2015Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 748, s. 13-18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Principle of Maximum Conformality (PMC) eliminates QCD renormalization scale-setting uncertainties using fundamental renormalization group methods. The resulting scale-fixed pQCD predictions are independent of the choice of renormalization scheme and show rapid convergence. The coefficients of the scale-fixed couplings are identical to the corresponding conformal series with zero beta-function. Two all-orders methods for systematically implementing the PMC-scale setting procedure for existing high order calculations are discussed in this article. One implementation is based on the PMC-BLM correspondence (PMC-I); the other, more recent, method (PMC-II) uses the R-delta-scheme, a systematic generalization of the minimal subtraction renormalization scheme. Both approaches satisfy all of the principles of the renormalization group and lead to scale-fixed and scheme-independent predictions at each finite order. In this work, we show that PMC-I and PMC-II scale-setting methods are in practice equivalent to each other. We illustrate this equivalence for the four-loop calculations of the annihilation ratio Re+e- and the Higgs partial width Gamma(H -> b (b) over bar). Both methods lead to the same resummed ('conformal') series up to all orders. The small scale differences between the two approaches are reduced as additional renormalization group {beta(i)}-terms in the pQCD expansion are taken into account. We also show that special degeneracy relations, which underly the equivalence of the two PMC approaches and the resulting conformal features of the pQCD series, are in fact general properties of non-Abelian gauge theory. (C) 2015 The Authors. Published by Elsevier B.V.

  • 231. Bianco, L.
    et al.
    Page, R. D.
    Darby, I. G.
    Joss, D. T.
    Simpson, J.
    Al-Khalili, J. J.
    Cannon, A. J.
    Cederwall, Bo
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Eeckhaudt, S.
    Erturk, S.
    Gall, B.
    Hornillos, M. B. Gomez
    Grahn, T.
    Greenlees, P. T.
    Hadinia, Baharak
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Heyde, K.
    Jakobsson, U.
    Jones, P. M.
    Julin, R.
    Juutinen, S.
    Ketelhut, S.
    Labiche, M.
    Leino, M.
    Leppanen, A. -P
    Nyman, M.
    O'Donnell, D.
    Paul, E. S.
    Petri, M.
    Peura, P.
    Puurunen, A.
    Rahkila, P.
    Ruotsalainen, P.
    Sandzelius, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Sapple, P. J.
    Saren, J.
    Scholey, C.
    Smirnova, N. A.
    Steer, A. N.
    Stevenson, P. D.
    Suckling, E. B.
    Thomson, J.
    Uusitalo, J.
    Venhart, M.
    Discovery of W-157 and Os-1612010Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 690, nr 1, s. 15-18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The nuclides W-157 and Os-161 have been discovered ill reactions of Ni-58 ion beams with a Cd-106 target. The Os-161 alpha-decay energy and half-life were 6890 +/- 12 keV and 640 +/- 60 mu s. The daughter W-157 nuclei beta-decayed with a half-life of 275 +/- 40 ms, populating both low-lying alpha-decaying states in Ta-157, which is consistent with a 7/2(-) ground state in W-157. Fine structure observed in the alpha decay of Os-161 places the lowest excited state in W-157 with 1(pi) = 9/2(-) at 318 +/- 30 key. The branching ratio of 5.5(-2.2)(+3.1)% indicates that Os-161 also has a 7/2(-) ground state. Shell-model calculations analysing the effects of monopole shifts and a tensor force on the relative energies of 2f(7/2) and 1h(9/2) neutron states in N = 83 isotones are presented. (C) 2010 Elsevier B.V. All rights reserved.

  • 232. Blennow, Mattias
    et al.
    Melbéus, Henrik
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Teoretisk partikelfysik.
    Ohlsson, Tommy
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Teoretisk partikelfysik.
    Zhang, He
    RG running in a minimal UED model in light of recent LHC Higgs mass bounds2012Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 712, nr 4-5, s. 419-424Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study how the recent ATLAS and CMS Higgs mass bounds affect the renormalization group running of the physical parameters in universal extra dimensions. Using the running of the Higgs self-coupling constant, we derive bounds on the cutoff scale of the extra-dimensional theory itself. We show that the running of physical parameters, such as the fermion masses and the CKM mixing matrix, is significantly restricted by these bounds. In particular, we find that the running of the gauge couplings cannot be sufficient to allow gauge unification at the cutoff scale.

  • 233.
    Blennow, Mattias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Teoretisk partikelfysik.
    Ohlsson, Tommy
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Teoretisk partikelfysik.
    Effective neutrino mixing and oscillations in dense matter2005Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 609, nr 3-4, s. 330-338Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigate the effective case of two-flavor neutrino oscillations in infinitely dense matter by using a perturbative approach. We begin by briefly summarizing the conditions for the three-flavor neutrino oscillation probabilities to take on the same form as the corresponding two-flavor probabilities. Then, we proceed with the infinitely dense matter calculations. Finally, we study the validity of the approximation of infinitely dense matter when the effective matter potential is large, but not infinite, this is done by using both analytic and numeric methods.

  • 234.
    Blennow, Mattias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik.
    Ohlsson, Tommy
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Teoretisk partikelfysik.
    Skrotzki, Julian
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik.
    Effects of non-standard interactions in the MINOS experiment2008Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 660, nr 5, s. 522-528Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigate the effects of non-standard interactions on the determination of the neutrino oscillation parameters Delta m(31)(2), theta(23), and theta(13) in the MINOS experiment. We show that adding non-standard interactions to the analysis lead to an extension of the allowed parameter space to larger values of Delta m(31)(2) and smaller theta(23), and basically removes all predictability for theta(13). In addition, we discuss the sensitivities to the non-standard interaction parameters of the MINOS experiment alone. In particular, we examine the degeneracy between theta(13) and the non-standard interaction parameter epsilon(e tau). We find that this degeneracy is responsible for the removal of the theta(13) predictability and that the possible bound on vertical bar epsilon(e tau)vertical bar is competitive with direct bounds only if a more stringent external bound on theta(13) is applied.

  • 235. Bock, Sebastian
    et al.
    Lafaye, Remi
    Univ Savoie, LAPP, CNTS IN2P3, Annecy Le Vieux, France.
    Plehn, Tilman
    Rauch, Michael
    Zerwas, Dirk
    Zerwas, P.M.
    Measuring Hidden Higgs and Strongly-Interacting Higgs Scenarios2010Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 694, nr 1, s. 44-53Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Higgs couplings can be affected by physics beyond the Standard Model We study modifications through interactions with a hidden sector and in specific composite Higgs models accessible at the LHC Both scenarios give rise to congruent patterns of universal or partially universal shifts In addition Higgs decays to the hidden sector may lead to invisible decay modes which we also exploit Experimental bounds on such potential modifications will measure the concordance of an observed Higgs boson with the Standard Model

  • 236.
    Boso, A.
    et al.
    Univ Padua, Dipartimento Fis & Astron Galileo Galilei, I-35131 Padua, Italy.;Ist Nazl Fis Nucl, Sez Padova, I-35131 Padua, Italy.;Natl Phys Lab, Hampton Rd, Teddington TW11 0LW, Middx, England..
    Cederwall, Bo
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Wieland, O.
    Ist Nazl Fis Nucl, Sez Milano, I-20133 Milan, Italy..
    Isospin dependence of electromagnetic transition strengths among an isobaric triplet2019Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 797, artikel-id UNSP 134835Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electric quadrupole matrix elements, M-p, for the J(pi) = 2(+) -> 0(+), Delta T = 0, T = 1 transitions across the A = 46 isobaric multiplet Cr-46-V-46-Ti-46 have been measured at GSI with the FRS-LYCCA-AGATA setup. This allows direct insight into the isospin purity of the states of interest by testing the linearity of M-p with respect to T-z. Pairs of nuclei in the T = 1 triplet were studied using identical reaction mechanisms in order to control systematic errors. The M-p values were obtained with two different methodologies: (i) a relativistic Coulomb excitation experiment was performed for Cr-46 and Ti-46; (ii) a "stretched target" technique was adopted here, for the first time, for lifetime measurements in V-46 and Ti-46. A constant value of M-p across the triplet has been observed. Shell-model calculations performed within the fp shell fail to reproduce this unexpected trend, pointing towards the need of a wider valence space. This result is confirmed by the good agreement with experimental data achieved with an interaction which allows excitations from the underlying sd shell. A test of the linearity rule for all published data on complete T = 1 isospin triplets is presented.

  • 237.
    Boucenna, Sofiane M.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, Roslagstullsbacken 21, SE-10691 Stockholm, Sweden..
    Ohlsson, Tommy
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, Roslagstullsbacken 21, SE-10691 Stockholm, Sweden.;Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Pernow, Marcus
    KTH, Skolan för teknikvetenskap (SCI), Fysik. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, Roslagstullsbacken 21, SE-10691 Stockholm, Sweden..
    A minimal non-supersymmetric SO(10) model with Peccei-Quinn symmetry2019Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 792, s. 251-257Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a minimal non-supersymmetric SO(10) GUT breaking directly to the Standard Model gauge group. Precise gauge coupling unification is achieved due to the presence of two color-octet scalars, one of which is accessible to LHC searches. Proton lifetime is predicted to be below 4.5 x 10(34) years, which is within the projected five-year sensitivity of the proposed Hyper-Kamiokande experiment. We find that the Standard Model observables are reproduced to a reasonable accuracy in a numerical fit, which also predicts the unknown neutrino parameters. Finally, the two scalar representations stabilize the electroweak vacuum and the dark matter is comprised of axions.

  • 238.
    Cederwall, Bo
    et al.
    KTH, Tidigare Institutioner                               , Fysik.
    Bäck, Torbjörn
    KTH, Tidigare Institutioner                               , Fysik.
    Bark, R
    Tormanen, S
    Odegard, S
    King, L
    Simpson, J
    Page, D
    Amzal, N
    Cullen, M
    Greenlees, T
    Keenan, A
    Lemmon, R
    Cocks, C
    Helariutta, K
    Jones, M
    Julin, R
    Juutinen, S
    Kettunen, H
    Kankaanpaa, H
    Kuusiniemi, P
    Leino, M
    Muikku, M
    Rahkila, P
    Savelius, A
    Uusitalo, J
    Magierski, P
    Wyss, Ramon
    KTH, Tidigare Institutioner                               , Fysik.
    Collective rotational-vibrational transition in the very neutron-deficient nuclei (171,172)-Pt1998Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 443, nr 1-4, s. 69-76Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Excited states have been identified for the first time in very neutron deficient Pt-171.172 nuclei using the recoil-or-decay tagging technique. The ground-state band in Pt-172 has been established up to I-pi = 8+. A similar level sequence, presumably built on the I-pi = 13/2(+) state, is observed for Pt-171. The data are compared with theoretical calculations based on the mean field approach and the random phase approximation and are put into the context of the systematics of platinum isotopes. (C) 1998 Elsevier Science B.V. All rights reserved.

  • 239. Cederwall, Bo
    et al.
    HACKMAN, G
    GALINDOURIBARRI, A
    RADFORD, DC
    BECKER, JA
    BRINKMAN, MJ
    DELEPLANQUE, MA
    DIAMOND, RM
    DRAPER, JE
    DUYAR, C
    FALLON, P
    FARRIS, LP
    HENRY, EA
    HUGHES, JR
    LEE, IY
    MACCHIAVELLI, AO
    MULLINS, SM
    RUBEL, E
    STEPHENS, FS
    STOYER, MA
    WADDINGTON, JC
    PROPERTIES OF SUPERDEFORMED BANDS IN DY-1531995Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 346, nr 3-4, s. 244-250Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two new superdeformed (SD) bands in Dy-153, in addition to the three previously observed, have been studied with the GAMMASPHERE detector array. Assignments to single-neutron orbits in the SD potential are made based on the band properties. Evidence for a band interaction at very high spins, possibly involving the first N = 7 proton intruder orbital, is observed in the strongest populated SD band. Furthermore, evidence far a Delta I = 2 staggering is also found in this SD band.

  • 240.
    Choubey, S.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik.
    Pramanik, D.
    Constraints on sterile neutrino oscillations using DUNE near detector2017Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 764, s. 135-141Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    DUNE (Deep Underground Neutrino Experiment) is a proposed long-baseline neutrino experiment in the US with a baseline of 1300 km from Fermi National Accelerator Laboratory (Fermilab) to Sanford Underground Research Facility, which will house a 40 kt Liquid Argon Time Projection Chamber (LArTPC) as the far detector. The experiment will also have a fine grained near detector for accurately measuring the initial fluxes. We show that the energy range of the fluxes and baseline of the DUNE near detector is conducive for observing νμ→νe oscillations of Δm2∼ eV2 scale sterile neutrinos, and hence can be effectively used for testing to very high accuracy the reported oscillation signal seen by the LSND and MiniBooNE experiments. We study the sensitivity of the DUNE near detector to sterile neutrino oscillations by varying the baseline, detector fiducial mass and systematic uncertainties. We find that the detector mass and baseline of the currently proposed near detector at DUNE will be able to test the entire LSND parameter region with good precision. The dependence of sensitivity on baseline and detector mass is seen to give interesting results, while dependence on systematic uncertainties is seen to be small.

  • 241.
    Choubey, Sandhya
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Teoretisk partikelfysik. Harish-Chandra Research Institute, India .
    Ohlsson, Tommy
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Teoretisk partikelfysik.
    Bounds on non-standard neutrino interactions using PINGU2014Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 739, s. 357-364Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigate the impact of non-standard neutrino interactions (NSIs) on atmospheric neutrinos using the proposed PINGU experiment. In particular, we focus on the matter NSI parameters epsilon(mu tau) and vertical bar epsilon(tau tau)-epsilon(mu mu)vertical bar that have previously been constrained by the Super-Kamiokande experiment. First, we present approximate analytical formulas for the difference of the muon neutrino survival probability with and without the above-mentioned NSI parameters. Second, we calculate the atmospheric neutrino events at PINGU in the energy range (2-100) GeV, which follow the trend outlined on probability level. Finally, we perform a statistical analysis of PINGU. Using three years of data, we obtain bounds from PINGU given by -0.0043 (-0.0048) < epsilon(mu tau) < 0.0047 (0.0046) and -0.03 (-0.016) < epsilon(tau tau) < 0.017 (0.032) at 90% confidence level for normal (inverted) neutrino mass hierarchy, which improve the Super-Kamiokande bounds by one order of magnitude. In addition, we show the expected allowed contour region in the epsilon-ettplane if NSIs exist in Nature and the result suggests that there is basically no correlation between epsilon(mu tau) and epsilon(tau tau).

  • 242. CLARK, RM
    et al.
    DELEPLANQUE, MA
    Cederwall, Bo
    DIAMOND, RM
    FALLON, P
    LEE, IY
    MACCHIAVELLI, AO
    STEPHENS, FS
    BECKER, JA
    BRINKMAN, MJ
    FARRIS, LP
    HENRY, EA
    HUGHES, JR
    STOYER, MA
    DRAPER, JE
    DUYAR, C
    RUBEL, E
    HUBEL, H
    KORTEN, W
    WILLSAU, P
    A PAIR OF IDENTICAL SUPERDEFORMED BANDS IN ND-1361995Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 343, nr 1-4, s. 59-63Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-spin states in Nd-136 were populated via the Mo-100(Ar-40, 4n) reaction at beam energies of 176 and 182 MeV, and resulting gamma-rays were detected using the GAMMASPHERE spectrometer. Analysis of the data has revealed the existence of an excited superdeformed (SD) band in Nd-136. Th, yrast SD band in Nd-136 has been extended by the addition of four (possibly five) transitions at high frequency. The new band displays the remarkable property of having transition energies identical (to within +/- 1 keV) to those of the half-points of the yrast SD band of Nd-136. Possible explanations in terms of cranked Woods-Saxon single-particle calculations are discussed.

  • 243. CRISTANCHO, F
    et al.
    LAFOSSE, DR
    BAKTASH, C
    WINCHELL, DF
    Cederwall, Bo
    DORING, J
    GROSS, CJ
    HUA, PF
    JIN, HQ
    KOROLIJA, M
    LANDULFO, E
    LEE, IY
    MACCHIAVELLI, AO
    MAIER, MR
    RATHBUN, W
    SALADIN, JX
    SARANTITES, D
    STRACENER, DW
    TABOR, SL
    VANDERMOLLEN, A
    WERNER, TR
    MULTIPLE SUPERDEFORMED BANDS IN SR-811995Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 357, nr 3, s. 281-286Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Four superdeformed bands extending over five to twelve transitions have been identified in Sr-81 from a study With the Gammasphere array and the Microball charged-particle array, One of the bands shows an upbend in the dynamic moment of inertia at a rotational frequency of 1.2 MeV and all bands exhibit a nearly constant moment of inertia below that frequency.

  • 244. Darby, I. G.
    et al.
    Page, R. D.
    Joss, D. T.
    Simpson, J.
    Bianco, L.
    Cooper, R. J.
    Eeckhaudt, S.
    Erturk, S.
    Gall, B.
    Grahn, T.
    Greenlees, P. T.
    Hadinia, Baharak
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Jones, P. M.
    Judson, D. S.
    Julin, R.
    Juutinen, S.
    Ketelhut, S.
    Leino, M.
    Leppanen, A. -P
    Nyman, M.
    Rahkila, P.
    Saren, J.
    Scholey, C.
    Steer, A. N.
    Uusitalo, J.
    Venhart, M.
    Decay of the high-spin isomer in Re-160: Changing single-particle structure beyond the proton drip line2011Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 695, nr 1-4, s. 78-81Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new high-spin isomeric state (t(1/2) = 2.8 +/- 0.1 mu s) in Re-160 has been identified. This high-spin isomer is unique in that it only decays by gamma-decay and not by proton or alpha-particle emission as is the case in every other proton emitter between Z = 64 and 80. Shell model calculations indicate how the convergence of the h(9/2) and f(7/2) neutron levels in this region could open up a gamma-decay path from the high-spin isomer to the low-spin ground state of 160Re. providing a natural explanation for this anomalous absence of charged-particle emission. The consequences of these observations for future searches for proton emission from even more exotic nuclei and in-beam spectroscopic studies are considered.

  • 245. Davies, P. J.
    et al.
    Grawe, H.
    Moschner, K.
    Blazhev, A.
    Wadsworth, R.
    Boutachkov, P.
    Ameil, F.
    Yagi, A.
    Baba, H.
    Bäck, Torbjörn
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Dewald, M.
    Doornenbal, P.
    Faestermann, T.
    Gengelbach, A.
    Gerl, J.
    Gernhaeeuserk, R.
    Go, S.
    Gorska, M.
    Gregor, E.
    Isobe, T.
    Jenkins, D. G.
    Hotaka, H.
    Jolie, J.
    Kojouharov, I.
    Kurz, N.
    Lewitowicz, M.
    Lorusso, G.
    Maier, L.
    Merchan, E.
    Naqvi, F.
    Nishibata, H.
    Nishimura, D.
    Nishimura, S.
    Nowacki, F.
    Pietralla, N.
    Schaffne, H.
    Soderstrom, P-A
    Jung, H. S.
    Steiger, K.
    Sumikama, T.
    Taprogge, J.
    Thoele, P.
    Warr, N.
    Watanabe, H.
    Werner, V.
    Xu, Z. Y.
    Yoshinaga, K.
    Zhu, Y.
    The role of core excitations in the structure and decay of the 16(+) spin-gap isomer in Cd-962017Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 767, s. 474-479Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The first evidence for beta-delayed proton emission from the 16(+) spin gap isomer in Cd-96 is presented. The data were obtained from the Rare Isotope Beam Factory, at the RIKEN Nishina Center, using the BigRIPS spectrometer and the EURICA decay station. beta p branching ratios for the ground state and 16(+) isomer have been extracted along with more precise lifetimes for these states and the lifetime for the ground state decay of Cd-95. Large scale shell model (LSSM) calculations have been performed and WKB estimates made for l = 0, 2, 4 proton emission from three resonance-like states in Ag-96, that are populated by the beta decay of the isomer, and the results compared to the new data. The calculations suggest that l = 2 proton emission from the resonance states, which reside similar to 5 MeV above the proton separation energy, dominates the proton decay. The results highlight the importance of core-excited wavefunction components for the 16(+) state.

  • 246. 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, Tidigare Institutioner                               , Fysik.
    Coherent proton-neutron contribution to octupole correlations in the neutron-deficient Xe-114 nucleus2002Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 535, nr 04-jan, s. 93-102Artikel i tidskrift (Refereegranskat)
    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.

  • 247.
    de Woul, Jonas
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik.
    Merle, Alexander
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik.
    Ohlsson, Tommy
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Teoretisk partikelfysik.
    Establishing analogies between the physics of extra dimensions and carbon nanotubes2012Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 714, nr 1, s. 44-47Artikel i tidskrift (Refereegranskat)
    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.

  • 248.
    Di Vecchia, Paolo
    et al.
    KTH, Centra, 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 supergravity2019Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 798, artikel-id 134927Artikel i tidskrift (Refereegranskat)
    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.

  • 249. Eggers, J.
    et al.
    Hoppe, Jens
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Matematik (Avd.).
    Singularity formation for time-like extremal hypersurfaces2009Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 680, nr 3, s. 274-278Artikel i tidskrift (Refereegranskat)
    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

  • 250.
    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, Centra, 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 stability2019Ingår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 789, s. 373-377Artikel i tidskrift (Refereegranskat)
    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.

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