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Numrering	Referens	Omslagsbild	Hitta
1.	Abulaiti, Yiming, et al. (författare) Search for an invisibly decaying Higgs boson or dark matter candidates produced in association with a Z boson in pp collisions at root s=13 TeV with the ATLAS detector 2018 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445 .- 0009-2614 .- 1873-4448. ; 776, s. 318-337 Tidskriftsartikel (refereegranskat)abstract A search for an invisibly decaying Higgs boson or dark matter candidates produced in association with a leptonically decaying Z boson in proton-proton collisions at root s = 13 TeV is presented. This search uses 36.1 fb(-1) of data collected by the ATLAS experiment at the Large Hadron Collider. No significant deviation from the expectation of the Standard Model backgrounds is observed. Assuming the Standard Model ZH production cross-section, an observed (expected) upper limit of 67% (39%) at the 95% confidence level is set on the branching ratio of invisible decays of the Higgs boson with mass m(H) = 125 GeV. The corresponding limits on the production cross-section of the ZH process with the invisible Higgs boson decays are also presented. Furthermore, exclusion limits on the dark matter candidate and mediator masses are reported in the framework of simplified dark matter models.
2.	Milstead, David A., et al. (författare) Measurement of differential cross sections of isolated-photon plus heavy-flavour jet production in pp collisions at s=8 TeV using the ATLAS detector 2018 Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 0009-2614 .- 1873-4448 .- 1873-2445. ; 776, s. 295-317 Tidskriftsartikel (refereegranskat)abstract This Letter presents the measurement of differential cross sections of isolated prompt photons produced in association with a b-jet or a c-jet. These final states provide sensitivity to the heavy-flavour content of the proton and aspects related to the modelling of heavy-flavour quarks in perturbative QCD. The measurement uses proton–proton collision data at a centre-of-mass energy of 8 TeV recorded by the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of up to 20.2 fb−1. The differential cross sections are measured for each jet flavour with respect to the transverse energy of the leading photon in two photon pseudorapidity regions: \|ηγ\|<1.37 and 1.56<\|ηγ\|<2.37. The measurement covers photon transverse energies 25
3.	Ohlsson, Tommy, 1973-, et al. (författare) Neutrino oscillations with three flavors in matter : Applications to neutrinos traversing the earth 2000 Ingår i: Physics Letters B. - : Elsevier Science B.V.. - 0370-2693 .- 1873-2445. ; 474:1-2, s. 153-162 Tidskriftsartikel (refereegranskat)abstract 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.
4.	Fjelstad, Jens, 1971-, et al. (författare) Equivalence of Chern-Simons gauge theory and WZNW model using a BRST symmetry 1999 Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 466:2-4, s. 227-233 Tidskriftsartikel (refereegranskat)abstract The equivalence between the Chern-Simons gauge theory on a three-dimensional manifold with boundary and the WZNW model on the boundary is established in a simple and general way using the BRST symmetry. Our approach is based on restoring gauge invariance of the Chern-Simons theory in the presence of a boundary. This gives a correspondence to the WZNW model that does not require solving any constraints, fixing the gauge or specifying boundary conditions.
5.	Jacobsson, Björn, et al. (författare) Effects of random matter density fluctuations on the neutrino oscillation transition probabilities in the Earth 2002 Ingår i: Physics Letters B. - 0370-2693 .- 1873-2445. ; 532:04-mar, s. 259-266 Tidskriftsartikel (refereegranskat)abstract 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.
6.	Ohlsson, Tommy, 1973-, et al. (författare) Bilarge leptonic mixing from Abelian horizontal symmetries 2002 Ingår i: Physics Letters B. - : Elsevier Science B.V.. - 0370-2693 .- 1873-2445. ; 537:02-jan, s. 95-102 Tidskriftsartikel (refereegranskat)abstract 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.
7.	Ohlsson, Tommy, 1973- (författare) Effects and influences on neutrino oscillations due to a thin density layer perturbation added to a matter density profile 2001 Ingår i: Physics Letters B. - : Elsevier Science B.V.. - 0370-2693 .- 1873-2445. ; 522:04-mar, s. 280-286 Tidskriftsartikel (refereegranskat)abstract 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.
8.	Ohlsson, Tommy, 1973- (författare) Equivalence between Gaussian averaged neutrino oscillations and neutrino decoherence 2001 Ingår i: Physics Letters B. - : Elsevier B.V.. - 0370-2693 .- 1873-2445. ; 502:04-jan, s. 159-166 Tidskriftsartikel (refereegranskat)abstract 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.
9.	Ohlsson, Tommy, 1973-, et al. (författare) Reconstruction of the Earth's matter density profile using a single neutrino baseline 2001 Ingår i: Physics Letters B. - : Elsevier Science B.V.. - 0370-2693 .- 1873-2445. ; 512:04-mar, s. 357-364 Tidskriftsartikel (refereegranskat)abstract 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.
10.	Rasmusson, M, et al. (författare) Photodissociation of bromobenzene in solution 2003 Ingår i: Chemical Physics Letters. - 0009-2614 .- 1873-4448. ; 367:5-6, s. 759-766 Tidskriftsartikel (refereegranskat)abstract The photodissociation of bromobenzene in solution was investigated with ultrafast transient absorption spectroscopy following excitation at 266 nm. Ab initio calculations of lower singlet and triplet states were performed in order to guide the interpretations. The main feature of the kinetics measured between 300 and 930 nm in acetonitrile is a 9 +/- 1ps decay, which we mainly assign to predissociation. Similar decays were observed in hexane, dichloromethane and tetrachloromethane at 400 and 800 nm. Other features in acetonitrile, such as complicated short-time dynamics between 420 and 620 nm and a long-lived component, might indicate the involvement of lower triplet states.
11.	Salek, Pawel, et al. (författare) Dynamical suppression of atomic peaks in resonant dissociative photoemission 2001 Ingår i: Chemical Physics Letters. - 0009-2614 .- 1873-4448. ; 343:3-4, s. 332-338 Tidskriftsartikel (refereegranskat)abstract Resonant excitation to the F1s-sigma* dissociative state in hydrogen fluoride gives a photoelectron spectrum where the spectator part contains strong atomic lines but a participator part where such lines are lacking. We demonstrate that this contrasting behaviour between the two parts is due to a strong dynamical suppression of the resonant contribution, making direct main state photoionization the dominating channel even at resonant conditions.
12.	Theander, M., et al. (författare) High luminescence from a substituted polythiophene in a solvent with low solubility 2001 Ingår i: Chemical Physics Letters. - 0009-2614 .- 1873-4448. ; 337:4-6, s. 277-283 Tidskriftsartikel (refereegranskat)abstract Steady-state and rime-resolved photoluminescence (PL) is used to probe different states of order in highly regular poly(3-(2'-methoxy-5'-octylphenyl)thiophene) (POMeOPT). In a good solvent (chloroform) the polymer has a PL yield of 0.33 and in a solvent with low solubility (mixture of chloroform and toluene) a new phase appears with higher PL yield (0.50). The new phase is attributed to micro-crystals formed by the regular part of the polymer which have low solubility in toluene. The crystallites have highly structured and redshifted electronic transitions compared with chains which are dissolved. (C) 2001 Published by Elsevier Science B.V.
13.	Adiels, L., et al. (författare) Search for narrow exotic states in annihilations on 4He 1984 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 138:1-3, s. 235-240 Tidskriftsartikel (refereegranskat)abstract After having found evidence for narrow exotic states in p annihilation, the production of such states on a nuclear target was studied with similar techniques. The γ spectrum associated with annihilation on 4He at rest was measured. The spectrum shows two peaks, at energies of 161.9 and 203.0 MeV, corresponding to intermediate narrow states of masses which seem to be related to states found in p annihilations. The confidence is better than 4 σ.
14.	Adiels, L., et al. (författare) Search for narrow signals in the [gamma]-spectrum from [Proton-antiproton] annihilation at rest 1986 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 182:3-4, s. 405-408 Tidskriftsartikel (refereegranskat)abstract The [gamma]-spectrum originating from pp[combining macron] annihilations at rest in liquid hydrogen was measured with two BGO spectrometers. A total of 24 ï¿œ 106[gamma]’s were accumulated. No narrow peaks indicating exotic states such as baryonium were observed. The upper limit for the branching ratio with 1040 [less-than-or-equals, slant] mx [less-than-or-equals, slant] 1770 MeV/c2 and with [lambda]x [less-than-or-equals, slant] 25 MeV/c2 is less than 10-3 with more than 99.96% confidence.
15.	Adiels, L., et al. (författare) Search for narrow signals in the γ-spectrum from pp̄ annihilation at rest 1986 Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 182:3-4, s. 405-408 Tidskriftsartikel (refereegranskat)abstract The γ-spectrum originating from pp̄ annihilations at rest in liquid hydrogen was measured with two BGO spectrometers. A total of 24 × 10 6 γ's were accumulated. No narrow peaks indicating exotic states such as baryonium were observed. The upper limit for the branching ratio p p ̄ → γ + X with 1040 ≤ m x ≤ 1770 MeV/c 2 and with λ x ≤ 25 MeV/c 2 is less than 10 -3 with more than 99.96% confidence. © 1986.
16.	Allasia, D, et al. (författare) Inelastic J ψ production in deep inelastic scattering from hydrogen and deuterium and the gluon distribution of free nucleons 1991 Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 258:3-4, s. 493-498 Tidskriftsartikel (refereegranskat)abstract We present results on inelastic J/PSI-production from muon interactions with hydrogen and deuterium at an incident muon energy of 280 GeV. The measured cross section ratio per nucleon for muon-induced J/PSI-production in deuterium and hydrogen was found to be R(D2/H2) = 1.01 +/- 0.15. The colour singlet model is shown to provide a good description of the observed differential cross section apart from a normalisation factor. The comparison between the observed cross section and the colour singlet model prediction allows the extraction of the gluon structure function G(chi) of the nucleon. The momentum fraction-chi of the nucleon carried by the gluon is measured in the range of chi = [0.02, 0.30]. The normalised gluon distribution of free nucleons thus found can be parametrised as chi-G(chi) = 1/2 (eta + 1)(1 - chi)eta, with eta = 5.1 +/- 0.9 (stat).
17.	Allasia, D, et al. (författare) Measurement of the neutron and the proton F2 structure function ratio 1990 Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 249:2, s. 366-372 Tidskriftsartikel (refereegranskat)
18.	Almlöf, Jan (författare) Hydrogen bond studies. 71. Ab initio calculation of the vibrational structure and equilibrium geometry in HF−2 and DF−2 1972 Ingår i: Chemical Physics Letters. - 0009-2614 .- 1873-4448. ; 17:1, s. 49-52 Tidskriftsartikel (refereegranskat)abstract MO LCAO SCF calculations have been performed to investigate the molecular astructure and vibrational spectrum of the bifluoride ion in its normal and deuterated form. The potential energy for nuclear motions has been evaluated as a function of the molecular degrees of freedom, taking only linear geometries into account. The vibrational Schrödinger equation has been solved by expanding the vibrational part of the total wavefunction as a sum of products of linear harmonic-oscillator eigenfunctions. The calculated properties are in good agreement with experiments, and even the minute effects of deuteration are well reproduced.
19.	Amaudruz, P, et al. (författare) Measurements of Rd-Rp and RCa-Rc in deep inelastic muon scattering 1992 Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 294:1, s. 120-126 Tidskriftsartikel (refereegranskat)abstract Results are presented on the difference in R, the ratio of longitudinally to transversely polarised virtual photon absorption cross sections, for the deuteron and the proton. They are obtained by comparing the ratio of cross sections for the deep inelastic scattering of muons from deuterium and hydrogen targets at 90 and 280 GeV incident energy. The results cover the range x = 0.01 -0.30, at an average Q2 of 9 GeV2. The measured difference R(d)-R(p) shows no significant x dependence and is compatible with zero, as well as with expectations from perturbative QCD. We use the same method to obtain the difference R(Ca)-R(C) from cross section ratios measured on carbon and calcium targets at 90 and 200 GeV incident energy.
20.	Amaudruz, P, et al. (författare) Proton and deuteron F2 structure functions in deep inelastic muon scattering 1992 Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 295:1-2, s. 159-168 Tidskriftsartikel (refereegranskat)abstract The structure functions F2p and F2d measured by deep inelastic muon scattering at incident energies of 90 and 280 GeV are presented. These measurements cover a large kinematic range, 0.006 less-than-or-equal-to x less-than-or-equal-to 0.6 and 0.5 less-than-or-equal-to Q2 less-than-or-equal-to 55 GeV2, and include the first precise data at small x, where large scaling violations are observed. The data agree with earlier results from SLAC and BCDMS but exhibit differences with respect to those of EMC-NA2. Extrapolations to small x of recent phenomenological parton distributions are shown to disagree with the present results.
21.	Ambrosio, M, et al. (författare) Atmospheric neutrino oscillations from upward throughgoing muon multiple scattering in MACRO 2003 Ingår i: Physics Letters B. - 0370-2693 .- 1873-2445. ; 566:1-2, s. 35-44 Tidskriftsartikel (refereegranskat)abstract The energy of atmospheric neutrinos detected by MACRO was estimated using multiple Coulomb scattering of upward throughgoing muons. This analysis allows a test of atmospheric neutrino oscillations, relying on the distortion of the muon energy distribution. These results have been combined with those coming from the upward throughgoing muon angular distribution only. Both analyses are independent of the neutrino flux normalization and provide strong evidence, above the for level, in favour of neutrino oscillations. (C) 2003 Published by Elsevier B.V.
22.	Ambrosio, M, et al. (författare) Matter effects in upward-going muons and sterile neutrino oscillations 2001 Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 517:1-2, s. 59-66 Tidskriftsartikel (refereegranskat)abstract The angular distribution of upward-going muons produced by atmospheric neutrinos in the rock below the MACRO detector shows anomalies in good agreement with two flavor nu (mu) --> nu (tau) oscillations with maximum mixing and Deltam(2) around 0.0024 eV(2). Exploiting the dependence of magnitude of the matter effect on oscillation channel, and using a set of 809 upward-going muons observed in MACRO, we show that the two flavor nu (mu) --> nu (s) oscillation is disfavored with 99% C.L. with respect to nu (mu) --> nu (tau). (C) 2001 Elsevier Science B.V. All rights reserved.
23.	Andersson, Renée, et al. (författare) Photoionisation of molecular wavepackets – the NaK(C1Σ+) case 2002 Ingår i: Chemical Physics Letters. - 0009-2614 .- 1873-4448. ; 352, s. 106-112 Tidskriftsartikel (refereegranskat)
24.	Angelopoulos, A., et al. (författare) K 0–KÌ„0 mass and decay-width differences : CPLEAR evaluation 1999 Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 471:2, s. 332-338 Tidskriftsartikel (refereegranskat)abstract 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.
25.	Apostolakis, A, et al. (författare) A determination of the CP violation parameter η+- from the decay of strangeness-tagged neutral kaons 1999 Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 458:4, s. 545-552 Tidskriftsartikel (refereegranskat)abstract 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.
26.	Apostolakis, A., et al. (författare) Measurement of the energy dependence of the form factor f+ in K 0 e3 decay 2000 Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 473:1, s. 186-192 Tidskriftsartikel (refereegranskat)abstract 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.
27.	Ashman, J, et al. (författare) A measurement of the spin asymmetry and determination of the structure function g1 in deep inelastic muon-proton scattering 1988 Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 206:2, s. 364-370 Tidskriftsartikel (refereegranskat)
28.	Ashman, J, et al. (författare) Measurement of the ratios of deep inelastic muon-nucleus cross sections on various nuclei compared to deuterium 1988 Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 202:4, s. 603-610 Tidskriftsartikel (refereegranskat)
29.	Ataç, \bfA., et al. (författare) GDR decay in hot Hg isotopes. An approach to improve the sensitivity to GDR decay following fusion reactions 1990 Ingår i: Physics Letters B. - 0370-2693 .- 1873-2445. ; 252, s. 545-549 Tidskriftsartikel (refereegranskat)
30.	Babaev, Egor (författare) Mass generation without symmetry breakdown in the chiral Gross-Neveu model at finite temperature and finite N in 2+1 dimensions 2001 Ingår i: Physics Letters B. - 0370-2693 .- 1873-2445. ; 497:04-mar, s. 323-327 Tidskriftsartikel (refereegranskat)abstract 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.
31.	Barnes, Leslie A, et al. (författare) Symmetry breaking in O+4 : an application of the Brueckner coupled-cluster method 1994 Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 223:3, s. 207-214 Tidskriftsartikel (refereegranskat)abstract A recent calculation of the antisymmetric stretch frequency for the rectangular structure of quartet O4+ using the QCISD(T) method gave a value of 3710 cin-1. This anomalous frequency is shown to be a consequence of symmetry-breaking effects, which occur even though the QCISD(T) solution derived from a delocalized SCF reference function lies energetically well below the two localized (symmetry-broken) solutions at the equilibrium geometry. The symmetry breaking is almost eliminated at the CCSD level of theory, but the small remaining symmetry-breaking effects are magnified at the CCSD (T) level of theory so that the antisymmetric stretch frequency is still significantly in error. The Brueckner coupled-cluster method, however, leads to a symmetrical solution which is free of symmetry-breaking effects, with an antisymmetric stretch frequency of 1322 cm-1, in good agreement with our earlier calculations using the CASSCF/CASSI method.
32.	Baudin, M., et al. (författare) MD simulations of a doped ceria surface - very large surface ion motion 2001 Ingår i: Chemical Physics Letters. - 0009-2614 .- 1873-4448. ; 335:06-maj, s. 517-523 Tidskriftsartikel (refereegranskat)abstract Mean-square displacements (MSDs) and individual-ion square-displacements (ISDs) for the different constituents in Ca-doped CeO2(0 1 1) slabs at 300 K have been studied as a function of depth from the surface. Constant pressure-constant temperature MD simulations were used. The MSDs are 2-3 times larger at the surface than in the bulk, but ISDs as large as ca. 150 times the surface MSD value were observed during short-time periods for anions next to an anion vacancy at the surface. The chemical implications of this kind of motion are important, since transient structural distortions of this magnitude will lead to large electron re-distributions.
33.	Beausang, C W, et al. (författare) Lifetimes of yrast and excited superdeformed states in Gd-150 : effect of particle-hole excitations on the deformation 1998 Ingår i: Physics Letters B. - 0370-2693 .- 1873-2445. ; 417:1-2, s. 13-19 Tidskriftsartikel (refereegranskat)abstract 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.
34.	Berggren, Magnus, et al. (författare) Controlling inter-chain and intra-chain excitations of a poly(thiophene) derivative in thin films 1999 Ingår i: Chemical Physics Letters. - : Elsevier. - 0009-2614 .- 1873-4448. ; 304:1-2, s. 84-90 Tidskriftsartikel (refereegranskat)abstract The decay of photoexcitations in polythiophene chains has been studied in solid solutions of the polymer from room temperature to 4 K. A strong blue shift of the emission spectrum is observed in the polymer blend, as compared to the homopolymer. Dispersion of the polythiophene suppresses the non-radiative processes, which are suggested to be correlated to close contacts of polymer chains. Quantum chemistry modeling of the excited state distributed on two chains corroborate this conclusion.
35.	Bergström, Lars, et al. (författare) Estimates of recoil nucleon spectra in high-energy hadron-nucleus collisions 1977 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 68:2, s. 177-179 Tidskriftsartikel (refereegranskat)abstract It is shown that recent data on the recoil nucleon spectrum in 10.5 GeV/c pion-neon collisions are in excellent agreement with a parameter free estimate from the so called tube model for high-energy hadron-nucleus collisions. A simple independent collision model is also treated.
36.	Bergström, Lars, et al. (författare) Is the recently published counterproof of the tube model credible? 1978 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 78:2-3, s. 337-341 Tidskriftsartikel (refereegranskat)abstract It is shown that recent data from pion and proton collision with emulsion nuclei at 200 GeV/c are in perfect agreement with expectations from the collective tube model. The opposite conclusion in publications by Azimov et al. came about because the authors ignored the important effects of target fragmentation.
37.	Bernhardsson, Anders, et al. (författare) Direct self-consistent reaction field with Pauli repulsion : Solvation effects on methylene peroxide 1996 Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 251:3-4, s. 141-149 Tidskriftsartikel (refereegranskat)abstract The properties of methylene peroxide in the gas phase and water have been examined. The solution effects have been modeled with a cavity. To make it possible to optimize the geometry of the cavity, we have added an approximate description of the Pauli repulsion between the solvent and the solute. An efficient direct implementation of the calculation of multicenter multipole operators is also described. We have applied the method to calculate the electric properties of methylene peroxide, a system that is characterized by its near degeneracy between a biradical and a zwitterionic state. As expected, it is shown that solvent effects will stabilize the ionic configuration, resulting in a considerably weakened OO bond and an increased double bond character in the CO bond. The theoretical study has been performed using the multiconfigurational (CAS) SCF method and second-order perturbation theory (CASPT2).
38.	Biglino, D., et al. (författare) Pulsed EPR study of the (NO)2-Na+ triplet state adsorption complex 2001 Ingår i: Chemical Physics Letters. - 0009-2614 .- 1873-4448. ; 349:5-6, s. 511-516 Tidskriftsartikel (refereegranskat)abstract The (NO)2-Na+ triplet state complex stabilised in Na-A zeolites at low temperature was studied by pulsed EPR. The 3-pulse ESEEM spectra at 5 K were analysed by simulations in the time-domain, followed by Fourier transformation. The ESEEM was attributed to the interaction with Na+. The hyperfine coupling A(23Na)=(4.6, 4.6, 8.2) MHz and nuclear quadrupole Q(23Na)=(0.3, 0,3, -0.6) MHz tensors are of comparable magnitude as in the NO-Na+ complex determined earlier. The complexes are proposed to be either pairs of NO-Na+ or ON-Na+-NO.
39.	Bittererova, M., et al. (författare) Ab initio study of the ground state and the first excited state of the rectangular (D-2h) N-4 molecule 2001 Ingår i: Chemical Physics Letters. - 0009-2614 .- 1873-4448. ; 347:03-jan, s. 220-228 Tidskriftsartikel (refereegranskat)abstract The dissociation pathway of D-2h N-4 has been investigated at the CASSCF level of theory. A new C-2v transition state to dissociation was found and characterized on the potential energy surface. The effective barrier of dissociation from D-2h N-4 to 2N(2) is estimated to 6.5 kcal/mol from MR-AQCCNTZ//CAS(12,12)/VTZ calculations. Vertical excitation energies and oscillator strengths for the lowest 20 singlet states of D-2h N-4 have been calculated using the EOM-CCSD method. The geometry of the first excited state B-1(3u), considered as the lowest optically accessible state, has been optimized and characterized at various computational levels. This state might be useful for detection of D-2h N-4 by means of laser-induced fluorescence (LIF) spectroscopy.
40.	Bittererova, M., et al. (författare) Theoretical study of the singlet electronically excited states of N-4 2001 Ingår i: Chemical Physics Letters. - 0009-2614 .- 1873-4448. ; 340:06-maj, s. 597-603 Tidskriftsartikel (refereegranskat)abstract Vertical excitation energies for the lowest eleven singlet states of T-d N-4 were calculated using the TD-DFT method with the B3LYP functional, and at the EOM-CCSD level of theory. The vertical excitation energies for the five lowest-lying excited states were also obtained using the state-averaged CASSCF, CASPT2, CASPT3, and MRCI + Q methods. Our results show that the five lowest-lying states are of valence character. EOM-CCSD/d-aug-cc-pVTZ calculations predict that there are two weakly allowed optical transitions of T-2 symmetry at 10.44 and 10.82 eV. The transition to the third T-2 state, which is predicted to be at 10.89 eV, has an oscillator strength about one order of magnitude higher.
41.	Blom, Jonas, et al. (författare) Novel integrable spin-particle models from gauge theories on a cylinder 1998 Ingår i: Physics Letters B. - 0370-2693 .- 1873-2445. ; 429, s. 336-342 Tidskriftsartikel (refereegranskat)
42.	Bondar, A., et al. (författare) The pp → ppπ0 reaction near the kinematical threshold 1995 Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 356:1, s. 8-12 Tidskriftsartikel (refereegranskat)abstract The reaction pp → ppπ0 has been measured using electron-cooled protons incident on an internal gas-jet target at seven different incident beam energies, from 280.7 MeV (1 MeV above the reaction threshold) up to 310.2 MeV. The pions were measured by their decay photons. In the overlapping energy region, the measured total cross sections agree with those measured in a recent Indiana experiment. The angular distributions are consistent with a 3P0 → 1S0S0 transition in the full energy range studied. The kinematical distributions are well described when taking into account the final state and the Coulomb interactions.
43.	Boschloo, Gerrit, et al. (författare) Photoinduced absorption spectroscopy of dye-sensitized nanostructured TiO2 2003 Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 370:04-mar, s. 381-386 Tidskriftsartikel (refereegranskat)abstract Photoinduced absorption (PIA) spectroscopy was used to investigate dye-sensitized electrodes and solar cells under illumination conditions comparable to sunlight. In the absence of redox electrolyte, cis-Ru (dcbpy)(2)(NCS)(2)-sensitized nanostructured TiO2 films show a long-lived photoinduced charge-separation (oxidized dye molecules/injected electrons in TiO2), with a lifetime of about 10(-3) s under full sun illumination. The PIA spectrum of a complete dye-sensitized cell is due to electrons in TiO2 and iodine radicals (12) in the electrolyte. The lifetime of this charge-separated state at open-circuit conditions was determined to be 0.15 s (0.27 sun illumination).
44.	Brändas, Erkki, et al. (författare) Wave function constructed from complex hybrids 1969 Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 3:5, s. 315-318 Tidskriftsartikel (refereegranskat)abstract The influence on the total wave function of an atomic basis consisting of complex hybrids is considered. The complex character of the wave function in the MO-LCAO scheme ss well as in the VB method is derived, and its consequences with respect to time reversal symmetry are discussed.
45.	Calén, H., et al. (författare) Deuteron breakup by 1.15 GeV protons and excitation of the Δ isobar 1993 Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 303:1-2, s. 10-15 Tidskriftsartikel (refereegranskat)abstract The pd→npp reaction has been measured using circulating 1.15 GeV protons, a gas jet target and scintillation detectors selecting scattered protons with energy above 30 MeV. The distribution of the two-proton invariant mass has a maximum at 2.13 ± 0.01 GeV/c2 and a width of 130 ± 10 MeV/c2 (FWHM). We see no evidence of narrow (Γ < 30 MeV/c2) peaks in the phase-space region selected. The mass of X, excited in the pN→nX elementary process, is 40 MeV/c2 smaller than the mass of a real Δ isobar.
46.	Calén, H., et al. (författare) The pp → ppη reaction near the kinematical threshold 1996 Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 366:1-4, s. 39-43 Tidskriftsartikel (refereegranskat)abstract The pp → ppη reaction has been measured at six energies close to threshold, from 1258 MeV to 1352 MeV, using an internal cluster gas jet target in the CELSIUS storage ring. The η is detected through its decay photons, in an array of CsI detectors, and the forward-going protons are detected in a plastic scintillator spectrometer. A complete event reconstruction is obtained at the higher energies in the measured interval. The new data, together with earlier data, give an accurate determination of the energy dependence close to threshold. The influence of the η-proton FSI is seen in the total cross section data as well as in a Dalitz plot of the η-p invariant mass distributions.
47.	Carius, Staffan, et al. (författare) The log-normal distribution for cascade multiplicities in hadron collisions 1990 Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 252:4, s. 647-652 Tidskriftsartikel (refereegranskat)abstract We introduce the log-normal distribution as a simple parametrization of multiplicities in hadron-hadron minimum-bias scattering and show that it fits data at all available energies, including the highest energy (pp̄ at √s=900 GeV) were the negative binomial distribution cannot describe the data well. The log-normal distribution is a two-parameter statistical probability function that has a simple and appealing physical interpretation. In statistics theory it arises in the case of multi-step cascade processes where each step multiplies the previous outcome. This gives a natural connection to state-of-the-art models for multiparticle production involving QCD parton cascades and hadronization.
48.	Carravetta, V., et al. (författare) An ab initio method for computing multi-atom resonant photoemission 2002 Ingår i: Chemical Physics Letters. - 0009-2614 .- 1873-4448. ; 354:02-jan, s. 100-108 Tidskriftsartikel (refereegranskat)abstract We present an ab initio method for computing multi-atom resonant photoemission (MARPE) in molecules and use this method to investigate the possibility of having a sizable MARPE effect. The MARPE cross section is obtained by making multi-center expansions of both the dipole matrix element - direct emission - and the hamiltonian matrix element between the resonant state and the autoionizing states - resonant emission. We show by sample calculations that the resonant contribution exhibits a strong distance dependence of the atoms participating in the MARPE process, and that it is energy dependent and element specific for the neighboring atoms. The ratio of resonant MARPE and direct photoionization cross sections is found to amount to less than one percent which probably makes the molecular MARPE effect difficult to apply in practice.
49.	Cederwall, Bo, et al. (författare) Collective rotational-vibrational transition in the very neutron-deficient nuclei (171,172)-Pt 1998 Ingår i: Physics Letters B. - AMSTERDAM, NETHERLANDS : ELSEVIER SCIENCE. - 0370-2693 .- 1873-2445. ; 443:1-4, s. 69-76 Tidskriftsartikel (refereegranskat)abstract 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.
50.	Cederwall, Bo, et al. (författare) PROPERTIES OF SUPERDEFORMED BANDS IN DY-153 1995 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 346:3-4, s. 244-250 Tidskriftsartikel (refereegranskat)abstract 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.

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