WorldWideScience

Sample records for vertex corrections massless

  1. The scalar-photon 3-point vertex in massless quenched scalar QED

    International Nuclear Information System (INIS)

    Concha-Sánchez, Y; Gutiérrez-Guerrero, L X; Fernández-Rangel, L A

    2016-01-01

    Non perturbative studies of Schwinger-Dyson equations (SDEs) require their infinite, coupled tower to be truncated in order to reduce them to a practically solvable set. In this connection, a physically acceptable ansatz for the three point vertex is the most favorite choice. Scalar quantum electrodynamics (sQED) provides a simple and neat platform to address this problem. The most general form of the scalar-photon three point vertex can be expressed in terms of only two independent form factors, longitudinal and transverse. Ball and Chiu have demonstrated that the longitudinal vertex is fixed by requiring the Ward-Fradkin-Green- Takahashi identity (WFGTI), while the transverse vertex remains undetermined. In massless quenched sQED, we propose the transverse part of the non perturbative scalar-photon vertex. (paper)

  2. Conservation laws, vertex corrections, and screening in Raman spectroscopy

    Science.gov (United States)

    Maiti, Saurabh; Chubukov, Andrey V.; Hirschfeld, P. J.

    2017-07-01

    We present a microscopic theory for the Raman response of a clean multiband superconductor, with emphasis on the effects of vertex corrections and long-range Coulomb interaction. The measured Raman intensity, R (Ω ) , is proportional to the imaginary part of the fully renormalized particle-hole correlator with Raman form factors γ (k ⃗) . In a BCS superconductor, a bare Raman bubble is nonzero for any γ (k ⃗) and diverges at Ω =2 Δmax , where Δmax is the largest gap along the Fermi surface. However, for γ (k ⃗) = constant, the full R (Ω ) is expected to vanish due to particle number conservation. It was sometimes stated that this vanishing is due to the singular screening by long-range Coulomb interaction. In our general approach, we show diagrammatically that this vanishing actually holds due to vertex corrections from the same short-range interaction that gives rise to superconductivity. We further argue that long-range Coulomb interaction does not affect the Raman signal for any γ (k ⃗) . We argue that vertex corrections eliminate the divergence at 2 Δmax . We also argue that vertex corrections give rise to sharp peaks in R (Ω ) at Ω <2 Δmin (the minimum gap along the Fermi surface), when Ω coincides with the frequency of one of the collective modes in a superconductor, e.g., Leggett and Bardasis-Schrieffer modes in the particle-particle channel, and an excitonic mode in the particle-hole channel.

  3. Infrared behaviour of massless QED in space-time dimensions 2

    International Nuclear Information System (INIS)

    Mitra, Indrajit; Ratabole, Raghunath; Sharatchandra, H.S.

    2005-01-01

    We show that the logarithmic infrared divergences in electron self-energy and vertex function of massless QED in 2+1 dimensions can be removed at all orders of 1/N by an appropriate choice of a non-local gauge. Thus the infrared behaviour given by the leading order in 1/N is not modified by higher order corrections. Our analysis gives a computational scheme for the Amati-Testa model, resulting in a non-trivial conformal invariant field theory for all space-time dimensions 2< d<4

  4. Infrared behaviour of massless QED in space-time dimensions 2

    Energy Technology Data Exchange (ETDEWEB)

    Mitra, Indrajit [The Institute of Mathematical Sciences, C.I.T. Campus, Taramani P.O., Chennai 600113 (India) and Theory Group, Saha Institute of Nuclear Physics, 1/AF Bidhan-Nagar, Kolkata 700064 (India)]. E-mail: indra@theory.saha.ernet.in; Ratabole, Raghunath [The Institute of Mathematical Sciences, C.I.T. Campus, Taramani P.O., Chennai 600113 (India)]. E-mail: raghu@imsc.res.in; Sharatchandra, H.S. [The Institute of Mathematical Sciences, C.I.T. Campus, Taramani P.O., Chennai 600113 (India)]. E-mail: sharat@imsc.res.in

    2005-04-07

    We show that the logarithmic infrared divergences in electron self-energy and vertex function of massless QED in 2+1 dimensions can be removed at all orders of 1/N by an appropriate choice of a non-local gauge. Thus the infrared behaviour given by the leading order in 1/N is not modified by higher order corrections. Our analysis gives a computational scheme for the Amati-Testa model, resulting in a non-trivial conformal invariant field theory for all space-time dimensions 2

  5. Gauge covariant fermion-photon vertex in quenched, massless three dimensional quantum electrodynamics

    International Nuclear Information System (INIS)

    Tjiang, P.C.; Burden, C.J.

    1998-01-01

    Full text: We consider the problem of designing an Ansatz for the transverse part of the fermion-photon vertex in QED 3 . Our work is based on that of Ball and Chiu, who consider restrictions placed on the vertex by the U(1) Ward identity, and on subsequent modifications which attempt to satisfy the Landau-Khalatnikov transformation rules. A class of vertex Ansaetze including that proposed by Dong et al is tested using the gauge invariance of the vacuum polarisation scalar

  6. Simple vertex correction improves GW band energies of bulk and two-dimensional crystals

    DEFF Research Database (Denmark)

    Schmidt, Per Simmendefeldt; Patrick, Christopher E.; Thygesen, Kristian Sommer

    2017-01-01

    The GW self-energy method has long been recognized as the gold standard for quasiparticle (QP) calculations of solids in spite of the fact that the neglect of vertex corrections and the use of a density-functional theory starting point lack rigorous justification. In this work we remedy this situ......The GW self-energy method has long been recognized as the gold standard for quasiparticle (QP) calculations of solids in spite of the fact that the neglect of vertex corrections and the use of a density-functional theory starting point lack rigorous justification. In this work we remedy...

  7. Vertex corrections to the mean-field electrical conductivity in disordered electron systems

    Czech Academy of Sciences Publication Activity Database

    Pokorný, Vladislav; Janiš, Václav

    2013-01-01

    Roč. 25, č. 17 (2013), "175502-1"-"175502-10" ISSN 0953-8984 Institutional support: RVO:68378271 Keywords : disordered electron systems * electrical conductivity * vertex corrections Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.223, year: 2013

  8. Finite size vertex correction to the strong decay of ηc and χc states and a determination of αs(mc)

    International Nuclear Information System (INIS)

    Ping Ronggang; Jiang Huanqing; Zou Bingsong

    2002-01-01

    In previous calculations of the strong decay of a charmonium, the first-order momentum dependence of the quark propagator is kept. It was found that the finite-size vertex correction to the Γ(J/ψ→3g) process is large. The authors calculate the two-gluon decay widths of η e , χ c0 and χ c2 by including the full momentum dependence of the quark propagator. Comparing to the zero-order calculation the authors find that the finite-size vertex correction factor to the two-gluon decay widths of η c is 1.32, and for the two-gluon decays of χ c0 and χ c2 , the vertex correction factors are 1.45 and 1.26, respectively. With the corrected decay widths Γ(η c →2g) authors extract the value as α s (m c ) = 0.28 +- 0.05 which agrees with that calculated from the Γ(J/ψ→3g) process with the same correction. The finite-size vertex correction to the process Γ(η c →3g) is not as large as that to the process Γ(J/ψ→3g)

  9. Optical conductivity calculation of a k.p model semiconductor GaAs incorporating first-order electron-hole vertex correction

    Science.gov (United States)

    Nurhuda, Maryam; Aziz Majidi, Muhammad

    2018-04-01

    The role of excitons in semiconducting materials carries potential applications. Experimental results show that excitonic signals also appear in optical absorption spectra of semiconductor system with narrow gap, such as Gallium Arsenide (GaAs). While on the theoretical side, calculation of optical spectra based purely on Density Functional Theory (DFT) without taking electron-hole (e-h) interactions into account does not lead to the appearance of any excitonic signal. Meanwhile, existing DFT-based algorithms that include a full vertex correction through Bethe-Salpeter equation may reveal an excitonic signal, but the algorithm has not provided a way to analyze the excitonic signal further. Motivated to provide a way to isolate the excitonic effect in the optical response theoretically, we develop a method of calculation for the optical conductivity of a narrow band-gap semiconductor GaAs within the 8-band k.p model that includes electron-hole interactions through first-order electron-hole vertex correction. Our calculation confirms that the first-order e-h vertex correction reveals excitonic signal around 1.5 eV (the band gap edge), consistent with the experimental data.

  10. Investigations into light-front interactions for massless fields (I): non-constructibility of higher spin quartic amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Bengtsson, Anders K.H. [Academy of Textiles, Engineering and Economics, University of Borås,Allégatan 1, SE-50190 Borås (Sweden)

    2016-12-27

    The dynamical commutators of the light-front Poincaré algebra yield first order differential equations in the p{sup +} momenta for the interaction vertex operators. The homogeneous solution to the equation for the quartic vertex is studied. Consequences as regards the constructibility assumption of quartic higher spin amplitudes from cubic amplitudes are discussed. The existence of quartic contact interactions unrelated to cubic interactions by Poincaré symmetry indicates that the higher spin S-matrix is not constructible. Thus quartic amplitude based no-go results derived by BCFW recursion for Minkowski higher spin massless fields may be circumvented.

  11. On the zero crossing of the three-gluon vertex

    Energy Technology Data Exchange (ETDEWEB)

    Athenodorou, A. [Department of Physics, University of Cyprus, POB 20537, 1678 Nicosia (Cyprus); Binosi, D., E-mail: binosi@ectstar.eu [European Centre for Theoretical Studies in Nuclear Physics and Related Areas - ECT* and Fondazione Bruno Kessler, Villa Tambosi, Strada delle Tabarelle 286, I-38050 Villazzano (Italy); Boucaud, Ph. [Laboratoire de Physique Théorique (UMR8627), CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay (France); De Soto, F. [Dpto. Sistemas Físicos, Químicos y Naturales, Univ. Pablo de Olavide, 41013 Sevilla (Spain); Papavassiliou, J. [Department of Theoretical Physics and IFIC, University of Valencia-CSIC, E-46100, Valencia (Spain); Rodríguez-Quintero, J. [Department of Integrated Sciences, University of Huelva, E-21071 Huelva (Spain); Zafeiropoulos, S. [Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany)

    2016-10-10

    We report on new results on the infrared behavior of the three-gluon vertex in quenched Quantum Chromodynamics, obtained from large-volume lattice simulations. The main focus of our study is the appearance of the characteristic infrared feature known as ‘zero crossing’, the origin of which is intimately connected with the nonperturbative masslessness of the Faddeev–Popov ghost. The appearance of this effect is clearly visible in one of the two kinematic configurations analyzed, and its theoretical origin is discussed in the framework of Schwinger–Dyson equations. The effective coupling in the momentum subtraction scheme that corresponds to the three-gluon vertex is constructed, revealing the vanishing of the effective interaction at the exact location of the zero crossing.

  12. Infrared divergences of Green functions and renormalization in massless theories. 2

    International Nuclear Information System (INIS)

    Anikin, S.A.; Zav'yalova, O.I.; Karchev, N.I.

    1981-01-01

    General theorems are proved concerning the infrared finiteness of Green functions in theories including massless particles. Considerations are based on α-representation of Feynman diagrams. Necessory conditions are considered for proving theorems in the case of diagrams with massive lines. Under certain conditions the contribution of the considered sections into the Feynman amplitude is shown to be free from infrared divergences, but only for those subgraphs which involve all the massive lines and contain all the outer vertexes in one affinity component

  13. Twistor diagrams and massless Moeller scattering

    International Nuclear Information System (INIS)

    Hodges, A.P.

    1983-01-01

    The theory of twistor diagrams, as devised by Penrose, is intended to lead to a manifestly finite account of scattering amplitudes in quantum field theory. The theory is here extended to a more general type of interaction between massless fields than has hitherto been described. It is applied to the example of first-order massless Moeller scattering in quantum electrodynamics. It is shown that earlier studies of this example have failed to render a correct account, in particular by overlooking an infrared divergency, but that the scattering data can nevertheless be represented within the twistor formalism. (author)

  14. Cubic Interactions of Massless Bosonic Fields in Three Dimensions

    Science.gov (United States)

    Mkrtchyan, Karapet

    2018-06-01

    In this Letter, we take the first step towards construction of nontrivial Lagrangian theories of higher-spin gravity in a metriclike formulation in three dimensions. The crucial feature of a metriclike formulation is that it is known how to incorporate matter interactions into the description. We derive a complete classification of cubic interactions for arbitrary triples s1 , s2 , s3 of massless fields, which are the building blocks of any interacting theory with massless higher spins. We find that there is, at most, one vertex for any given triple of spins in 3D (with one exception, s1=s2=s3=1 , which allows for two vertices). Remarkably, there are no vertices for spin values that do not respect strict triangle inequalities and contain at least two spins greater than one. This translates into selection rules for three-point functions of higher-spin conserved currents in two dimensional conformal field theory. Furthermore, universal coupling to gravity for any spin is derived. Last, we argue that this classification persists in arbitrary Einstein backgrounds.

  15. Conservation of lepton charges, massive majorana and massless neutrinos

    International Nuclear Information System (INIS)

    Petcov, S.T.; Toshev, S.T.

    1984-01-01

    It is shown that the necessary and sufficient condition for the presence of k massless and (n-k) massive nondegenerate Majorana neutrinos in a theory with n neutrino flavours and a neutrino mass term of Majorana type is the existence of k standard and no other conserved lepton charges. Two-loop Majorana mass corrections for neutrinos, massless at tree level, are also briefly discussed. (orig.)

  16. Numerical evaluation of virtual corrections to multi-jet production in massless QCD

    DEFF Research Database (Denmark)

    Badger, S.; Yundin, V.; Biedermann, B.

    2013-01-01

    title: NJet. Catalogue identifier: AEPF_v1_0. Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEPF_v1_0.html. Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland. Licensing provisions: GNU General Public License, version 3. No. of lines in distributed program......, including test data, etc.: 250047. No. of bytes in distributed program, including test data, etc.: 2138947. Distribution format: tar.gz. Programming language: C++, Python. Computer: PC/Workstation. Operating system: No specific requirements - tested on Scientific Linux 5.2. and Mac OS X 10.......7.4. Classification: 11.5. External routines: QCDLoop (http://qcdloop.fnal.gov/), qd (http://crd.lbl.gov/dhbailey/mpdist/), both included in the distribution file. Nature of problem:. Evaluation of virtual corrections for multi-jet production in massless QCD. Solution method:. Purely numerical approach based on tree...

  17. Partially massless graviton on beyond Einstein spacetimes

    Science.gov (United States)

    Bernard, Laura; Deffayet, Cédric; Hinterbichler, Kurt; von Strauss, Mikael

    2017-06-01

    We show that a partially massless graviton can propagate on a large set of spacetimes which are not Einstein spacetimes. Starting from a recently constructed theory for a massive graviton that propagates the correct number of degrees of freedom on an arbitrary spacetime, we first give the full explicit form of the scalar constraint responsible for the absence of a sixth degree of freedom. We then spell out generic conditions for the constraint to be identically satisfied, so that there is a scalar gauge symmetry which makes the graviton partially massless. These simplify if one assumes that spacetime is Ricci symmetric. Under this assumption, we find explicit non-Einstein spacetimes (some, but not all, with vanishing Bach tensors) allowing for the propagation of a partially massless graviton. These include in particular the Einstein static Universe.

  18. Higher-order corrections in the cut vertex theory and the reciprocity relation in (PHI3)6 field theory

    International Nuclear Information System (INIS)

    Kubota, T.

    1980-01-01

    Higher-order corrections to deep inelastic and inclusive annihilation processes in the asymptotically free (PHI 3 ) 6 theory are calculated by using the method of cut vertices proposed by Mueller. Renormalization of the cut vertices is carried out up the two-loop level and it is found that, in the minimal subtraction scheme, the equality between the anomalous dimension of the space-like cut vertex and that of the corresponding time-like cut vertex does not hold beyond the leading order. Corrections to the coefficient functions are also calculated to study the Q 2 dependence of the moment up to the next-to-leading order. It is shown that the reciprocity relation suggested by Gribov and Lipatov on the basis of the leading-order calculation does not hold in the higher order. (orig.)

  19. Universality in all-{alpha}{sup Prime} order corrections to BPS/non-BPS brane world volume theories

    Energy Technology Data Exchange (ETDEWEB)

    Hatefi, Ehsan, E-mail: ehatefi@ictp.it [International Centre for Theoretical Physics, Strada Costiera 11, Trieste (Italy); Park, I.Y., E-mail: inyongpark05@gmail.com [Department of Natural and Physical Sciences, Philander Smith College, Little Rock, AR 72223 (United States)

    2012-11-21

    Knowledge of all-{alpha}{sup Prime} higher derivative corrections to leading order BPS and non-BPS brane actions would serve in future endeavor of determining the complete form of the non-abelian BPS and tachyonic effective actions. In this paper, we note that there is a universality in the all-{alpha}{sup Prime} order corrections to BPS and non-BPS branes. We compute amplitudes between one Ramond-Ramond C-field vertex operator and several SYM gauge/scalar vertex operators. Specifically, we evaluate in closed form string correlators of two-point amplitudes A{sup C{phi}}, A{sup CA}, a three-point amplitude A{sup C{phi}{phi}}, and a four-point amplitude A{sup C{phi}{phi}{phi}}. We carry out pole and contact term analysis. In particular we reproduce some of the contact terms and the infinite massless poles of A{sup C{phi}{phi}{phi}} by SYM vertices obtained through the universality.

  20. Diagrammatic expansion for positive spectral functions beyond GW: Application to vertex corrections in the electron gas

    Science.gov (United States)

    Stefanucci, G.; Pavlyukh, Y.; Uimonen, A.-M.; van Leeuwen, R.

    2014-09-01

    We present a diagrammatic approach to construct self-energy approximations within many-body perturbation theory with positive spectral properties. The method cures the problem of negative spectral functions which arises from a straightforward inclusion of vertex diagrams beyond the GW approximation. Our approach consists of a two-step procedure: We first express the approximate many-body self-energy as a product of half-diagrams and then identify the minimal number of half-diagrams to add in order to form a perfect square. The resulting self-energy is an unconventional sum of self-energy diagrams in which the internal lines of half a diagram are time-ordered Green's functions, whereas those of the other half are anti-time-ordered Green's functions, and the lines joining the two halves are either lesser or greater Green's functions. The theory is developed using noninteracting Green's functions and subsequently extended to self-consistent Green's functions. Issues related to the conserving properties of diagrammatic approximations with positive spectral functions are also addressed. As a major application of the formalism we derive the minimal set of additional diagrams to make positive the spectral function of the GW approximation with lowest-order vertex corrections and screened interactions. The method is then applied to vertex corrections in the three-dimensional homogeneous electron gas by using a combination of analytical frequency integrations and numerical Monte Carlo momentum integrations to evaluate the diagrams.

  1. Free massless scalar fields in two dimensions

    International Nuclear Information System (INIS)

    Hadjiivanov, L.K.

    1980-01-01

    A common Fock space for two free massless scalar fields, nonlocal with respect to each other, is constructed. The operators corresponding to the two formal charges are correctly defined and it is shown that they generate translationally invariant states from the vacuum

  2. A Novel Vertex Affinity for Community Detection

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Andy [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Sanders, Geoffrey [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Henson, Van [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Vassilevski, Panayot [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-05

    We propose a novel vertex affinity measure in this paper. The new vertex affinity quantifies the proximity between two vertices in terms of their clustering strength and is ideal for such graph analytics applications as community detection. We also developed a framework that combines simple graph searches and resistance circuit formulas to compute the vertex affinity efficiently. We study the properties of the new affinity measure empirically in comparison to those of other popular vertex proximity metrics. Our results show that the existing metrics are ill-suited for community detection due to their lack of fundamental properties that are essential for correctly capturing inter- and intra-cluster vertex proximity.

  3. Macroscopic (and microscopic massless modes

    Directory of Open Access Journals (Sweden)

    Michael C. Abbott

    2015-05-01

    Full Text Available We study certain spinning strings exploring the flat directions of AdS3×S3×S3×S1, the massless sector cousins of su(2 and sl(2 sector spinning strings. We describe these, and their vibrational modes, using the D(2,1;α2 algebraic curve. By exploiting a discrete symmetry of this structure which reverses the direction of motion on the spheres, and alters the masses of the fermionic modes s→κ−s, we find out how to treat the massless fermions which were previously missing from this formalism. We show that folded strings behave as a special case of circular strings, in a sense which includes their mode frequencies, and we are able to recover this fact in the worldsheet formalism. We use these frequencies to calculate one-loop corrections to the energy, with a version of the Beisert–Tseytlin resummation.

  4. Transport coefficients of Dirac ferromagnet: Effects of vertex corrections

    Science.gov (United States)

    Fujimoto, Junji

    2018-03-01

    As a strongly spin-orbit-coupled metallic model with ferromagnetism, we have considered an extended Stoner model to the relativistic regime, named Dirac ferromagnet in three dimensions. In a previous paper [J. Fujimoto and H. Kohno, Phys. Rev. B 90, 214418 (2014), 10.1103/PhysRevB.90.214418], we studied the transport properties giving rise to the anisotropic magnetoresistance (AMR) and the anomalous Hall effect (AHE) with the impurity potential being taken into account only as the self-energy. The effects of the vertex corrections (VCs) to AMR and AHE are reported in this paper. AMR is found not to change quantitatively when the VCs are considered, although the transport lifetime is different from the one-electron lifetime and the charge current includes additional contributions from the correlation with spin currents. The side-jump and the skew-scattering contributions to AHE are also calculated. The skew-scattering contribution is dominant in the clean case as can be seen in the spin Hall effect in the nonmagnetic Dirac electron system.

  5. Quantum gravitational corrections for spinning particles

    International Nuclear Information System (INIS)

    Fröb, Markus B.

    2016-01-01

    We calculate the quantum corrections to the gauge-invariant gravitational potentials of spinning particles in flat space, induced by loops of both massive and massless matter fields of various types. While the corrections to the Newtonian potential induced by massless conformal matter for spinless particles are well known, and the same corrections due to massless minimally coupled scalars http://dx.doi.org/10.1088/0264-9381/27/24/245008, massless non-conformal scalars http://dx.doi.org/10.1103/PhysRevD.87.104027 and massive scalars, fermions and vector bosons http://dx.doi.org/10.1103/PhysRevD.91.064047 have been recently derived, spinning particles receive additional corrections which are the subject of the present work. We give both fully analytic results valid for all distances from the particle, and present numerical results as well as asymptotic expansions. At large distances from the particle, the corrections due to massive fields are exponentially suppressed in comparison to the corrections from massless fields, as one would expect. However, a surprising result of our analysis is that close to the particle itself, on distances comparable to the Compton wavelength of the massive fields running in the loops, these corrections can be enhanced with respect to the massless case.

  6. Thermodynamic limit of particle-hole form factors in the massless XXZ Heisenberg chain

    Energy Technology Data Exchange (ETDEWEB)

    Kitanine, N. [Univ. de Bourgogne (France). IMB, UMR 5584 du CNRS; Kozlowski, K.K. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Maillet, J.M.; Terras, V. [ENS Lyon (France). UMR 5672 du CNRS, Lab. de Physique; Slavnov, N.A. [Steklov Mathematical Inst., Moscow (Russian Federation)

    2011-03-15

    We study the thermodynamic limit of the particle-hole form factors of the XXZ Heisenberg chain in the massless regime. We show that, in this limit, such form factors decrease as an explicitly computed power-law in the system size. Moreover, the corresponding amplitudes can be obtained as a product of a ''smooth'' and a ''discrete'' part: the former depends continuously on the rapidities of the particles and holes, whereas the latter has an additional explicit dependence on the set of integer numbers that label each excited state in the associated logarithmic Bethe equations. We also show that special form factors corresponding to zero-energy excitations lying on the Fermi surface decrease as a power-law in the system size with the same critical exponents as in the longdistance asymptotic behavior of the related two-point correlation functions. The methods we develop in this article are rather general and can be applied to other massless integrable models associated to the six-vertex R-matrix and having determinant representations for their form factors. (orig.)

  7. Flipped spinfoam vertex and loop gravity

    Energy Technology Data Exchange (ETDEWEB)

    Engle, Jonathan; Pereira, Roberto [CPT, CNRS Case 907, Universite de la Mediterranee, F-13288 Marseille (France); Rovelli, Carlo [CPT, CNRS Case 907, Universite de la Mediterranee, F-13288 Marseille (France)], E-mail: rovelli@cpt.univ-mrs.fr

    2008-07-21

    We introduce a vertex amplitude for 4d loop quantum gravity. We derive it from a conventional quantization of a Regge discretization of euclidean general relativity. This yields a spinfoam sum that corrects some difficulties of the Barrett-Crane theory. The second class simplicity constraints are imposed weakly, and not strongly as in Barrett-Crane theory. Thanks to a flip in the quantum algebra, the boundary states turn out to match those of SO(3) loop quantum gravity-the two can be identified as eigenstates of the same physical quantities-providing a solution to the problem of connecting the covariant SO(4) spinfoam formalism with the canonical SO(3) spin-network one. The vertex amplitude is SO(3) and SO(4)-covariant. It rectifies the triviality of the intertwiner dependence of the Barrett-Crane vertex, which is responsible for its failure to yield the correct propagator tensorial structure. The construction provides also an independent derivation of the kinematics of loop quantum gravity and of the result that geometry is quantized.

  8. Numerical indications on the semiclassical limit of the flipped vertex

    Energy Technology Data Exchange (ETDEWEB)

    Magliaro, Elena; Perini, Claudio; Rovelli, Carlo [Centre de Physique Theorique de Luminy , Case 907, F-13288 Marseille (France)

    2008-05-07

    We introduce a technique for testing the semiclassical limit of a quantum gravity vertex amplitude. The technique is based on the propagation of a semiclassical wave packet. We apply this technique to the newly introduced 'flipped' vertex in loop quantum gravity, in order to test the intertwiner dependence of the vertex. Under some drastic simplifications, we find very preliminary, but surprisingly good numerical evidence for the correct classical limit.

  9. Smooth massless limit of field theories

    International Nuclear Information System (INIS)

    Fronsdal, C.

    1980-01-01

    The massless limit of Fierz-Pauli field theories, describing fields with fixed mass and spin interacting with external sources, is examined. Results are obtained for spins, 1, 3/2, 2 and 3 using conventional models, and then for all half-integral spins in a relatively model-independent manner. It is found that the massless limit is smooth provided that the sources satisfy certain conditions. In the massless limit these conditions reduce to the conservation laws required by internal consistency of massless field theory. Smoothness simply requires that quantities that vanish in the massless case approach zero in a certain well-defined manner. (orig.)

  10. Covariant representations of massless Fermi fields

    International Nuclear Information System (INIS)

    Borek, R.

    1983-01-01

    The author shows in the framework of algebraic quantum field theory that representations of the quasi-local algebra of a free, massless spinor field exist which fulfil two axioms of von Neumann. Furthermore, the current algebra of a charged, massless fermion is considered. Finally, representations with the spectral condition of a charged, massless fermion and the quasi-local algebra of a free, massless Majorana particle are constructed. (HSI) [de

  11. Primary Vertex Reconstruction at the ATLAS Experiment

    CERN Document Server

    Grimm, Kathryn; The ATLAS collaboration

    2016-01-01

    Efficient and precise reconstruction of the primary vertex in an LHC collision is essential in both the reconstruction of the full kinematic properties of a hard-scatter event and of soft interactions as a measure of the amount of pile-up. The reconstruction of primary vertices in the busy, high pile-up environment of Run-2 of the LHC is a challenging task. New methods have been developed by the ATLAS experiment to reconstruct vertices in such environments. Advances in vertex seeding include methods taken from medical imaging, which allow for reconstruction of multiple vertices with small spatial separation. The adoption of this new seeding algorithm within the ATLAS adaptive vertex finding and fitting procedure will be discussed, and the first results of the new techniques from Run-2 data will be presented. Additionally, data-driven methods to evaluate vertex resolution will be presented with special focus on correct methods to evaluate the effect of the beam spot constraint; results from these methods in Ru...

  12. Partially massless fields during inflation

    Science.gov (United States)

    Baumann, Daniel; Goon, Garrett; Lee, Hayden; Pimentel, Guilherme L.

    2018-04-01

    The representation theory of de Sitter space allows for a category of partially massless particles which have no flat space analog, but could have existed during inflation. We study the couplings of these exotic particles to inflationary perturbations and determine the resulting signatures in cosmological correlators. When inflationary perturbations interact through the exchange of these fields, their correlation functions inherit scalings that cannot be mimicked by extra massive fields. We discuss in detail the squeezed limit of the tensor-scalar-scalar bispectrum, and show that certain partially massless fields can violate the tensor consistency relation of single-field inflation. We also consider the collapsed limit of the scalar trispectrum, and find that the exchange of partially massless fields enhances its magnitude, while giving no contribution to the scalar bispectrum. These characteristic signatures provide clean detection channels for partially massless fields during inflation.

  13. Intertwiner dynamics in the flipped vertex

    Energy Technology Data Exchange (ETDEWEB)

    Alesci, Emanuele; Bianchi, Eugenio; Magliaro, Elena; Perini, Claudio, E-mail: alesci@fis.uniroma3.i, E-mail: e.bianchi@sns.i, E-mail: elena.magliaro@gmail.co, E-mail: claude.perin@libero.i [Centre de Physique Theorique de Luminy, Case 907, F-13288 Marseille (France)

    2009-09-21

    We continue the semiclassical analysis, started in a previous paper, of the intertwiner sector of the flipped vertex spinfoam model. We use independently both a semi-analytical and a purely numerical approach, finding the correct behavior of wavepacket propagation and physical expectation values. In the end, we show preliminary results about correlation functions.

  14. Algebraic characterization of the Witten vertex

    International Nuclear Information System (INIS)

    Embacher, F.

    1989-01-01

    The Witten vertex of open bosonic string field theory is characterized by a set of algebraic properties written down in the Fock-space operator formalism. The typical 3-string overlap structure as well as the correct ghost midpoint insertion are not required from the outset but arise as consequences. 20 refs. (Author)

  15. Massless radioactivity: a medical must?

    International Nuclear Information System (INIS)

    Wolterbeek, H.Th

    2013-01-01

    Full text: The authoritative body in the field of nomenclature for radiochemistry is the International Union of Pure and Applied Chemistry (IUPAC). The concepts of specific activity, radioactivity concentration, carrier, carrier-free, and no-carrier-added have been) and are also recently discussed as to their correctness, relevance, clarity and consistency. Here, specific activity (sa) is suggested as to be defined as the activity (a) of a specified radioisotope in an amount of substance divided by the mass (m) of the total number of atoms (sa=a/m). Qaim, in a recent review of the future of medical radionuclides, justly argues that both yield, radionuclide purity and specific activity should be increased: here, again, however, the term specific activity deserves attention. What should be the goal in increasing specific activity? Up to as near as possible to massless? Approaching massless in terms of the smallest achievable m value? Taking the radionuclide n X, in physics specific activity is defined as both activity and mass related to n X, in radiochemistry specific activity is defined as the activity of n X related to the mass of all X, but in nuclear medicine most interest is in what IUPAC calls activity concentration, that is, the activity of n X in relation to the mass or volume of the material in which n X is present. This means that, apparently, nuclear medicine asks for high activity concentration of n X in non-isotopic carriers. Does this always imply the highest possible n X specific activity? The presentation focuses on this issue: examples are given that show both the absence of any need for the highest possible specific activity (e.g. 99 Mo, 166 Ho) and the need for 'as-near-as-possible to massless' (e.g. 99m Tc, 177 Lu, α-particles), in all cases in dependence of the radionuclide's position in the production chain and its eventual application in nuclear diagnostics or - therapy

  16. Spin wave Feynman diagram vertex computation package

    Science.gov (United States)

    Price, Alexander; Javernick, Philip; Datta, Trinanjan

    Spin wave theory is a well-established theoretical technique that can correctly predict the physical behavior of ordered magnetic states. However, computing the effects of an interacting spin wave theory incorporating magnons involve a laborious by hand derivation of Feynman diagram vertices. The process is tedious and time consuming. Hence, to improve productivity and have another means to check the analytical calculations, we have devised a Feynman Diagram Vertex Computation package. In this talk, we will describe our research group's effort to implement a Mathematica based symbolic Feynman diagram vertex computation package that computes spin wave vertices. Utilizing the non-commutative algebra package NCAlgebra as an add-on to Mathematica, symbolic expressions for the Feynman diagram vertices of a Heisenberg quantum antiferromagnet are obtained. Our existing code reproduces the well-known expressions of a nearest neighbor square lattice Heisenberg model. We also discuss the case of a triangular lattice Heisenberg model where non collinear terms contribute to the vertex interactions.

  17. Studies of the Triple Pomeron Vertex in perturbative QCD and its applications in phenomenology

    International Nuclear Information System (INIS)

    Kutak, K.

    2006-12-01

    We study the properties of the Triple Pomeron Vertex in the perturbative QCD using the twist expansion method. Such analysis allows us to find the momenta configurations preferred by the vertex. When the momentum transfer is zero, the dominant contribution in the limit when N c →∞ comes from anticollinear pole. This is in agreement with result obtained without expanding, but by direct averaging of the Triple Pomeron Vertex over angles. Resulting theta functions show that the anticollinear configuration is optimal for the vertex. In the finite N c case the collinear term also contributes. Using the Triple Pomeron Vertex we construct a pomeron loop and we also consider four gluon propagation between two Triple Pomeron Vertices. We apply the Triple Pomeron Vertex to construct the Hamiltonian from which we derive the Balitsky-Kovchegov equation for an unintegrated gluon density. In order to apply this equation to phenomenology, we apply the Kwiecinski-Martin-Stasto model for higher order corrections to a linear part of the Balitsky-Kovchegov equation. We introduce the definition of the saturation scale which reflects properties of this equation. Finally, we use it for computation of observables, such as the F 2 structure function and diffractive Higgs boson production cross section. The impact of screening corrections on F 2 is negligible, but those effects turn out to be significant for diffractive Higgs boson production at LHC

  18. Partially massless higher-spin theory

    Energy Technology Data Exchange (ETDEWEB)

    Brust, Christopher [Perimeter Institute for Theoretical Physics,31 Caroline St. N, Waterloo, Ontario N2L 2Y5 (Canada); Hinterbichler, Kurt [CERCA, Department of Physics, Case Western Reserve University,10900 Euclid Ave, Cleveland, OH 44106 (United States)

    2017-02-16

    We study a generalization of the D-dimensional Vasiliev theory to include a tower of partially massless fields. This theory is obtained by replacing the usual higher-spin algebra of Killing tensors on (A)dS with a generalization that includes “third-order” Killing tensors. Gauging this algebra with the Vasiliev formalism leads to a fully non-linear theory which is expected to be UV complete, includes gravity, and can live on dS as well as AdS. The linearized spectrum includes three massive particles and an infinite tower of partially massless particles, in addition to the usual spectrum of particles present in the Vasiliev theory, in agreement with predictions from a putative dual CFT with the same symmetry algebra. We compute the masses of the particles which are not fixed by the massless or partially massless gauge symmetry, finding precise agreement with the CFT predictions. This involves computing several dozen of the lowest-lying terms in the expansion of the trilinear form of the enlarged higher-spin algebra. We also discuss nuances in the theory that occur in specific dimensions; in particular, the theory dramatically truncates in bulk dimensions D=3,5 and has non-diagonalizable mixings which occur in D=4,7.

  19. Partially massless higher-spin theory

    International Nuclear Information System (INIS)

    Brust, Christopher; Hinterbichler, Kurt

    2017-01-01

    We study a generalization of the D-dimensional Vasiliev theory to include a tower of partially massless fields. This theory is obtained by replacing the usual higher-spin algebra of Killing tensors on (A)dS with a generalization that includes “third-order” Killing tensors. Gauging this algebra with the Vasiliev formalism leads to a fully non-linear theory which is expected to be UV complete, includes gravity, and can live on dS as well as AdS. The linearized spectrum includes three massive particles and an infinite tower of partially massless particles, in addition to the usual spectrum of particles present in the Vasiliev theory, in agreement with predictions from a putative dual CFT with the same symmetry algebra. We compute the masses of the particles which are not fixed by the massless or partially massless gauge symmetry, finding precise agreement with the CFT predictions. This involves computing several dozen of the lowest-lying terms in the expansion of the trilinear form of the enlarged higher-spin algebra. We also discuss nuances in the theory that occur in specific dimensions; in particular, the theory dramatically truncates in bulk dimensions D=3,5 and has non-diagonalizable mixings which occur in D=4,7.

  20. Vertex reconstruction in CMS

    International Nuclear Information System (INIS)

    Chabanat, E.; D'Hondt, J.; Estre, N.; Fruehwirth, R.; Prokofiev, K.; Speer, T.; Vanlaer, P.; Waltenberger, W.

    2005-01-01

    Due to the high track multiplicity in the final states expected in proton collisions at the LHC experiments, novel vertex reconstruction algorithms are required. The vertex reconstruction problem can be decomposed into a pattern recognition problem ('vertex finding') and an estimation problem ('vertex fitting'). Starting from least-squares methods, robustifications of the classical algorithms are discussed and the statistical properties of the novel methods are shown. A whole set of different approaches for the vertex finding problem is presented and compared in relevant physics channels

  1. Vertex Reconstruction in CMS

    CERN Document Server

    Chabanat, E; D'Hondt, J; Vanlaer, P; Prokofiev, K; Speer, T; Frühwirth, R; Waltenberger, W

    2005-01-01

    Because of the high track multiplicity in the final states expected in proton collisions at the LHC experiments, novel vertex reconstruction algorithms are required. The vertex reconstruction problem can be decomposed into a pattern recognition problem ("vertex finding") and an estimation problem ("vertex fitting"). Starting from least-square methods, ways to render the classical algorithms more robust are discussed and the statistical properties of the novel methods are shown. A whole set of different approaches for the vertex finding problem is presented and compared in relevant physics channels.

  2. Studies of the Triple PomeronVertex in perturbative QCD and its applications in phenomenology

    Energy Technology Data Exchange (ETDEWEB)

    Kutak, K.

    2006-12-15

    We study the properties of the Triple Pomeron Vertex in the perturbative QCD using the twist expansion method. Such analysis allows us to find the momenta configurations preferred by the vertex. When the momentum transfer is zero, the dominant contribution in the limit when N{sub c}{yields}{infinity} comes from anticollinear pole. This is in agreement with result obtained without expanding, but by direct averaging of the Triple Pomeron Vertex over angles. Resulting theta functions show that the anticollinear configuration is optimal for the vertex. In the finite N{sub c} case the collinear term also contributes. Using the Triple Pomeron Vertex we construct a pomeron loop and we also consider four gluon propagation between two Triple Pomeron Vertices. We apply the Triple Pomeron Vertex to construct the Hamiltonian from which we derive the Balitsky-Kovchegov equation for an unintegrated gluon density. In order to apply this equation to phenomenology, we apply the Kwiecinski-Martin-Stasto model for higher order corrections to a linear part of the Balitsky-Kovchegov equation. We introduce the definition of the saturation scale which reflects properties of this equation. Finally, we use it for computation of observables, such as the F{sub 2} structure function and diffractive Higgs boson production cross section. The impact of screening corrections on F{sub 2} is negligible, but those effects turn out to be significant for diffractive Higgs boson production at LHC.

  3. Massive and massless gauge fields of any spin and symmetry

    International Nuclear Information System (INIS)

    Hussain, F.; Jarvis, P.D.

    1988-05-01

    An analysis of the BRST approach to massive and massless gauge fields of any spin and symmetry is presented. Previous results on massless gauge fields are extended to totally antisymmetric massless tensors and Kaehler-Dirac particles. Two methods for arriving at a BRST invariant, massive theory from the corresponding massless one are discussed. The first allows for an interpretation in terms of dimensional reduction, while the second keeps the BRST operator of the massless theory, but employs gauge invariant fields. (author). 10 refs

  4. Quasiparadoxes of massless QED

    International Nuclear Information System (INIS)

    Smilga, A.V.

    1990-04-01

    We show that the limit m e =0 in the conventional QED is not smooth. In contrast to the massless QED the massive QED, however small the mass is, involves finite probability chirality breaking processes. The chirality breaking effects may be observed provided the size of experimental installation is greater than the formation length ∼ E/m 2 . We discuss also the finite cross sections of virtual longitudinal photon production and scattering in massless QED recently found by Gorsky, Ioffe and Khodjamirian and argue that real longitudinal photons do not interact while the limit of zero virtuality is not smooth. (author). 23 refs, 4 figs

  5. All-order results for infrared and collinear singularities in massless gauge theories

    CERN Document Server

    Dixon, Lance J; Magnea, Lorenzo

    2010-01-01

    We review recent results concerning the all-order structure of infrared and collinear divergences in massless gauge theory amplitudes. While the exponentiation of these divergences for nonabelian gauge theories has been understood for a long time, in the past couple of years we have begun to unravel the all-order structure of the anomalous dimensions that build up the perturbative exponent. In the large-Nc limit, all infrared and collinear divergences are determined by just three functions; one of them, the cusp anomalous dimension, plays a key role also for non-planar contributions. Indeed, all infrared and collinear divergences of massless gauge theory amplitudes with any number of hard partons may be captured by a surprisingly simple expression constructed as a sum over color dipoles. Potential corrections to this expression, correlating four or more hard partons at three loops or beyond, are tightly constrained and are currently under study.

  6. A nonperturbative fermion-boson vertex

    International Nuclear Information System (INIS)

    Bashir, A.; Raya, A.

    2002-01-01

    We calculate the massive fermion propagator at one-loop order in QED3. The Ward-Takahashi identity (WTI) relates the propagator to the vertex. This allows us to split the vertex into its longitudinal and transverse parts. The former is fixed by the WTI. Following the scheme of Ball and Chiu later modified by Kizilersue et. al., we calculate the full vertex at one-loop order. A mere subtraction of the longitudinal part of the vertex gives us the transverse part. The α dependence in the transverse vertex can be eliminated by making use of the perturbative expressions for the wavefunction renormalization function and the mass function of complicated arguments of the incoming and outgoing fermion momenta. This leads us to a vertex which is nonperturbative in nature. We also calculate an effective vertex for which the arguments of the unknown functions have no angular dependence, making it particularly suitable for numerical studies of dynamical symmetry breaking

  7. SU(N)-QCD2 meson equation in next-to-leading order

    International Nuclear Information System (INIS)

    Durgut, M.; Pak, N.K.

    1982-08-01

    We compute the 1/N corrections to the meson equation in the regular cut-off scheme. We illustrate that although the quark and gluon self energy and vertex corrections do not vanish explicitly as in the singular cut-off scheme, their contributions to the meson Bethe-Salpeter equation get cancelled within the whole set of contributing diagrams. We also argue that 0(1/N) corrections to the meson equation remove the massless boson from the spectrum in accordance with the Coleman theorem. (author)

  8. Ground states of the massless Derezinski-Gerard model

    International Nuclear Information System (INIS)

    Ohkubo, Atsushi

    2009-01-01

    We consider the massless Derezinski-Gerard model introduced by Derezinski and Gerard in 1999. We give a sufficient condition for the existence of a ground state of the massless Derezinski-Gerard model without the assumption that the Hamiltonian of particles has compact resolvent.

  9. Stochastic massless fields I: Integer spin

    International Nuclear Information System (INIS)

    Lim, S.C.

    1981-04-01

    Nelson's stochastic quantization scheme is applied to classical massless tensor potential in ''Coulomb'' gauge. The relationship between stochastic potential field in various gauges is discussed using the case of vector potential as an illustration. It is possible to identify the Euclidean tensor potential with the corresponding stochastic field in physical Minkowski space-time. Stochastic quantization of massless fields can also be carried out in terms of field strength tensors. An example of linearized stochastic gravitational field in vacuum is given. (author)

  10. Soft behavior of a closed massless state in superstring and universality in the soft behavior of the dilaton

    Energy Technology Data Exchange (ETDEWEB)

    Vecchia, Paolo Di [The Niels Bohr Institute, University of Copenhagen,Blegdamsvej 17, DK-2100 Copenhagen Ø (Denmark); Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-10691 Stockholm (Sweden); Marotta, Raffaele [Istituto Nazionale di Fisica Nucleare, Sezione di Napoli,Complesso Universitario di Monte S. Angelo ed. 6, via Cintia, 80126, Napoli (Italy); Mojaza, Matin [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, Am Mühlenberg 1, 14476 Potsdam (Germany)

    2016-12-06

    We consider the tree-level scattering amplitudes in the NS-NS (Neveu-Schwarz) massless sector of closed superstrings in the case where one external state becomes soft. We compute the amplitudes generically for any number of dimensions and any number and kind of the massless closed states through the subsubleading order in the soft expansion. We show that, when the soft state is a graviton or a dilaton, the full result can be expressed as a soft theorem factorizing the amplitude in a soft and a hard part. This behavior is similar to what has previously been observed in field theory and in the bosonic string. Differently from the bosonic string, the supersymmetric soft theorem for the graviton has no string corrections at subsubleading order. The dilaton soft theorem, on the other hand, is found to be universally free of string corrections in any string theory.

  11. Soft behavior of a closed massless state in superstring and universality of the soft behavior of the dilaton

    DEFF Research Database (Denmark)

    di Vecchia, Paolo; Marotta, Raffaele; Mojaza, Matin

    2016-01-01

    We consider the tree-level scattering amplitudes in the NS-NS (Neveu-Schwarz) massless sector of closed superstrings in the case where one external state becomes soft. We compute the amplitudes generically for any number of dimensions and any number and kind of the massless closed states through...... the subsubleading order in the soft expansion. We show that, when the soft state is a graviton or a dilaton, the full result can be expressed as a soft theorem factorizing the amplitude in a soft and a hard part. This behavior is similar to what has previously been observed in field theory and in the bosonic string....... Differently from the bosonic string, the supersymmetric soft theorem for the graviton has no string corrections at subsubleading order. The dilaton soft theorem, on the other hand, is found to be universally free of string corrections in any string theory....

  12. Massless representations and admissibility condition for higher spin superalgebras

    Energy Technology Data Exchange (ETDEWEB)

    Konstein, S E; Vasiliev, M A

    1989-01-16

    Massless particle representations of various infinite-dimensional higher spin superalgebras proposed previously are constructed. We analyse which of higher spin superalgebras obey the requirement (the admissibility condition) of possessing massless unitary representations with the same spectra of spins as predicted by the structure of gauge fields originating from these superalgebras. It is argued that those higher spin superalgebras, which obey the admissibility condition, can serve as rigid supersymmetries in nontrivial consistent gauge theories of massless fields of all spins.

  13. Vertex algebras and algebraic curves

    CERN Document Server

    Frenkel, Edward

    2004-01-01

    Vertex algebras are algebraic objects that encapsulate the concept of operator product expansion from two-dimensional conformal field theory. Vertex algebras are fast becoming ubiquitous in many areas of modern mathematics, with applications to representation theory, algebraic geometry, the theory of finite groups, modular functions, topology, integrable systems, and combinatorics. This book is an introduction to the theory of vertex algebras with a particular emphasis on the relationship with the geometry of algebraic curves. The notion of a vertex algebra is introduced in a coordinate-independent way, so that vertex operators become well defined on arbitrary smooth algebraic curves, possibly equipped with additional data, such as a vector bundle. Vertex algebras then appear as the algebraic objects encoding the geometric structure of various moduli spaces associated with algebraic curves. Therefore they may be used to give a geometric interpretation of various questions of representation theory. The book co...

  14. Exploring excitonic signal in optical conductivity of ZnO through first-order electron-hole vertex correction

    Science.gov (United States)

    Khoirunnisa, Humaira; Aziz Majidi, Muhammad

    2018-04-01

    The emergence of exitonic signal in the optical response of a wide band-gap semiconductor has been a common knowledge in physics. There have been numerous experimental studies exploring the important role of excitons on influencing both the transport and optical properties of the materials. Despite the existence of much information on excitonic effects, there has not been much literature that explores detailed theoretical explanation on how the exitonic signal appears and how it evolves with temperature. Here, we propose a theoretical study on the optical conductivity of ZnO, a well-known wide band-gap semiconductor that we choose as a case study. ZnO has been known to exhibit excitonic states in its optical spectra in the energy range of ∼3.13-3.41 eV, with a high exciton binding energy of ∼60 meV. An experimental study on ZnO in 2014 revealed such a signal in its optical conductivity spectrum. We present a theoretical investigation on the appearance of excitonic signal in optical conductivity of ZnO. We model the wurtzite ZnO within an 8-band k.p approximation. We calculate the optical conductivity by incorporating the first-order vertex correction derived from the Feynman diagrams. Our calculation up to the first-order correction spectrum qualitatively confirms the existence of excitons in wurtzite ZnO.

  15. Measurement of the double-vertex reconstruction efficiency of the inclusive vertex finder with accidentally overlapping b-jets in ttbar events

    Energy Technology Data Exchange (ETDEWEB)

    Marchesini, Ivan; Nowatschin, Dominik; Ott, Jochen; Schmidt, Alexander; Tholen, Heiner [University of Hamburg (Germany)

    2015-07-01

    In LHC Run II, CMS b-tagging algorithms will employ a new core algorithm, named Inclusive Vertex Finder (IVF). The IVF is designed to perform decay vertex reconstruction of long-lived particles, such as B hadrons. Using only tracks from the silicon tracker, it does not depend on jet clustering and allows for higher reconstruction efficiency of decay vertices, which particularly applies to topologies with two or more decay vertices at low distance. Thus, the IVF will offer increased sensitivity for SM measurements (e.g. angular correlations), but also for the search of BSM physics (e.g. final states with boosted Higgs bosons decaying into b-quarks). For the first time, the dependence of the IVF reconstruction efficiency on the distance of vertices in the η-φ plane is investigated with a data-driven approach. We use a clean set of top quark pair events, selected from data recorded in 2012 in pp-collisions at 8 TeV with the CMS detector, and perform a template fit to a 2D-distribution of the masses of the vertices in an event. Correction factors are derived for the application to simulated events. We conclude that our technique will enable precise calibration of double vertexing with the IVF in the LHC Run II.

  16. Vertex detectors

    International Nuclear Information System (INIS)

    Lueth, V.

    1992-07-01

    The purpose of a vertex detector is to measure position and angles of charged particle tracks to sufficient precision so as to be able to separate tracks originating from decay vertices from those produced at the interaction vertex. Such measurements are interesting because they permit the detection of weakly decaying particles with lifetimes down to 10 -13 s, among them the τ lepton and charm and beauty hadrons. These two lectures are intended to introduce the reader to the different techniques for the detection of secondary vertices that have been developed over the past decades. The first lecture includes a brief introduction to the methods used to detect secondary vertices and to estimate particle lifetimes. It describes the traditional technologies, based on photographic recording in emulsions and on film of bubble chambers, and introduces fast electronic registration of signals derived from scintillating fibers, drift chambers and gaseous micro-strip chambers. The second lecture is devoted to solid state detectors. It begins with a brief introduction into semiconductor devices, and then describes the application of large arrays of strip and pixel diodes for charged particle tracking. These lectures can only serve as an introduction the topic of vertex detectors. Time and space do not allow for an in-depth coverage of many of the interesting aspects of vertex detector design and operation

  17. Massive and mass-less Yang-Mills and gravitational fields

    NARCIS (Netherlands)

    Veltman, M.J.G.; Dam, H. van

    1970-01-01

    Massive and mass-less Yang-Mills and gravitational fields are considered. It is found that there is a discrete difference between the zero-mass theories and the very small, but non-zero mass theories. In the case of gravitation, comparison of massive and mass-less theories with experiment, in

  18. String bits and the spin vertex

    OpenAIRE

    Jiang, YunfengInstitut de Physique Théorique, DSM, CEA, URA2306 CNRS Saclay, F-91191 Gif-sur-Yvette, France; Kostov, Ivan(Institut de Physique Théorique, DSM, CEA, URA2306 CNRS Saclay, F-91191 Gif-sur-Yvette, France); Petrovskii, Andrei(Institut de Physique Théorique, DSM, CEA, URA2306 CNRS Saclay, F-91191 Gif-sur-Yvette, France); Serban, Didina(Institut de Physique Théorique, DSM, CEA, URA2306 CNRS Saclay, F-91191 Gif-sur-Yvette, France)

    2015-01-01

    We initiate a novel formalism for computing correlation functions of trace operators in the planar N=4 SYM theory. The central object in our formalism is the spin vertex, which is the weak coupling analogy of the string vertex in string field theory. We construct the spin vertex explicitly for all sectors at the leading order using a set of bosonic and fermionic oscillators. We prove that the vertex has trivial monodromy, or put in other words, it is a Yangian invariant. Since the monodromy o...

  19. Mass generation in perturbed massless integrable models

    International Nuclear Information System (INIS)

    Controzzi, D.; Mussardo, G.

    2005-01-01

    We extend form-factor perturbation theory to non-integrable deformations of massless integrable models, in order to address the problem of mass generation in such systems. With respect to the standard renormalisation group analysis this approach is more suitable for studying the particle content of the perturbed theory. Analogously to the massive case, interesting information can be obtained already at first order, such as the identification of the operators which create a mass gap and those which induce the confinement of the massless particles in the perturbed theory

  20. The Weinberg-Witten theorem on massless particles: an essay

    International Nuclear Information System (INIS)

    Loebbert, F.

    2008-01-01

    In this essay we deal with the Weinberg-Witten theorem which imposes limitations on massless particles. First we motivate a classification of massless particles given by the Poincare group as the symmetry group of Minkowski spacetime. We then use the fundamental structure of the background in the form of Poincare covariance to derive restrictions on charged massless particles known as the Weinberg-Witten theorem. We address possible misunderstandings in the proof of this theorem motivated by several papers on this topic. In the last section the consequences of the theorem are discussed. We treat it in the context of known particles and as a constraint for emergent theories. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  1. Massless Interacting Scalar Fields in de Sitter space

    CERN Document Server

    López Nacir, Diana

    2016-10-28

    We present a method to compute the two-point functions for an $O(N)$ scalar field model in de Sitter spacetime, avoiding the well known infrared problems for massless fields. The method is based on an exact treatment of the Euclidean zero modes and a perturbative one of the nonzero modes, and involves a partial resummation of the leading secular terms. This resummation, crucial to obtain a decay of the correlation functions, is implemented along with a double expansion in an effective coupling constant $\\sqrt\\lambda$ and in $1/N$. The results reduce to those known in the leading infrared approximation and coincide with the ones obtained directly in Lorentzian de Sitter spacetime in the large $N$ limit. The new method allows for a systematic calculation of higher order corrections both in $\\sqrt\\lambda$ and in $1/N$.

  2. The effects of the massless O(αs2), O(ααs), O(α2) QCD and QED corrections and of the massive contributions to Γ(H0→bb-bar)

    International Nuclear Information System (INIS)

    Kataev, A.L.

    1992-11-01

    The expression for the decay width of H 0 →bb-bar process in terms of the b-quark pole mass is presented, with the order O(α s 2 ), O(αα s ) and O(α 2 ) massless corrections and of the order O(m b 2 /M H 2 ) QCD contributions taken into account. The results demonstrate that in the region 50 GeV H ≤2M W the higher order QCD effects reduce the Born expression for Γ Hb( b-bar) by over 50%. The theoretical uncertainties of the QCD predictions for Γ Hb( b-bar) are analyzed in detail. The importance of taking into account of the order O(m b 2 /M H 2 )-corrections for modelling the threshold effects is stressed. (author) 33 refs.; 7 figs

  3. (Quasi)Elastic Electron-Muon Large-Angle Scattering to a Two-Loop Approximation: Vertex Contributions

    CERN Document Server

    Bytev, V V; Shaikhatdenov, B G

    2002-01-01

    We consider a process of quasielastic e\\mu large-angle scattering at high energies with radiative corrections up to a two-loop level. The lowest order radiative correction arising both from one-loop virtual photon emission and a real soft emission are presented to a power accuracy. Two-loop level corrections are supposed to be of three gauge-invariant classes. One of them, so-called vertex contribution, is given in logarithmic approximation. Relation with the renormalization group approach is discussed.

  4. (Quasi)Elastic Electron-Muon Large-Angle Scattering to a Two-Loop Approximation Vertex Contributions

    CERN Document Server

    Bytev, V V; Shaikhatdenov, B G

    2002-01-01

    We consider a process of quasielastic e\\mu large-angle scattering at high energies with radiative corrections up to a two-loop level. The lowest order radiative correction arising both from one-loop virtual photon emission and a real soft emission are presented to a power accuracy. Two-loop level corrections are supposed to be of three gauge-invariant classes. One of them, so-called vertex contribution, is given in logarithmic approximation. Relation with the renormalization group approach is discussed.

  5. Infrared behavior of massless field theories

    International Nuclear Information System (INIS)

    Sapirstein, J.R.

    1979-01-01

    Typical infrared effects in several gauge field theories with massless particles are investigated in perturbation theory. It is first shown that divergences occurring in individual Feynman graphs arising from integrations over the long-wavelength modes of the fields cancel when the graphs are grouped together in a particular way, in a generalization of the Bloch-Nordsieck treatment of QED. As one of the requirements of finiteness is renormalization of the vector propagator off shell, the charge in these theories is not directly related to classical experiment. In an effort to find the meaning of charge the low-energy theorem is considered. Although in lowest order the graphs reproduce the Thompson limit, it is found that loop corrections are singular in the low-energy limit; a simple definition of the charge is thus precluded. Finally, the behavior of the quark color magnetic moment is treated. An apparent infrared singularity of this moment is shown to be due to an improper use of perturbation theory, and is removed and replaced with a finite, field-dependent moment, by use of Furry picture propagators

  6. Trace anomaly of the stress-energy tensor for massless vector particles propagating in a general background metric

    International Nuclear Information System (INIS)

    Adler, S.L.; Lieberman, J.

    1978-01-01

    We reanalyze the problem of regularization of the stress-energy tensor for massless vector particles propating in a general background metric, using covariant point separation techniques applied to the Hadamard elementary solution. We correct an error, point out by Wald, in the earlier formulation of Adler, Lieberman, and Ng, and find a stress-energy tensor trace anomaly agreeing with that found by other regularization methods

  7. The three-photon vertex

    International Nuclear Information System (INIS)

    Delbourgo, R.

    1976-01-01

    Owing to weak interactions, the three-photon vertex is non-zero. From gauge invariance and symmetry requirements, it is proved that the C = -1P = - 1 vertex amplitudes are at least of order q 7 in the limit of soft photon momentum q and that if any two photons are placed on mass shell the form factors vanish identically. (author)

  8. The trace anomaly and massless scalar degrees of freedom

    Energy Technology Data Exchange (ETDEWEB)

    Gianotti, Maurizio [Los Alamos National Laboratory; Mottola, Emil [Los Alamos National Laboratory

    2008-01-01

    The trace anomaly of quantum fields in electromagnetic or gravitational backgrounds implies the existence of massless scalar poles in physical amplitudes involving the stress-energy tensor. Considering first the axial anomaly and using QED as an example, we compute the full one-loop triangle amplitude of the fermionic stress tensor with two current vertices, {open_square}T{sup {mu}{nu}}J{sup {alpha}}J{sup {beta}}, and exhibit the scalar pole in this amplitude associated with the trace anomaly, in the limit of zero electron mass m{yields}0. To emphasize the infrared aspect of the anomaly, we use a dispersive approach and show that this amplitude and the existence of the massless scalar pole is determined completely by its ultraviolet finite terms, together with the requirements of Poincare invariance of the vacuum, Bose symmetry under interchange of J{sup {alpha}} and J{sup {beta}}, and vector current and stress-tensor conservation. We derive a sum rule for the appropriate positive spectral function corresponding to the discontinuity of the triangle amplitude, showing that it becomes proportional to {delta}(k{sup 2}) and therefore contains a massless scalar intermediate state in the conformal limit of zero electron mass. The effective action corresponding to the trace of the triangle amplitude can be expressed in local form by the introduction of two scalar auxiliary fields which satisfy massless wave equations. These massless scalar degrees of freedom couple to classical sources, contribute to gravitational scattering processes, and can have long range gravitational effects.

  9. Hunting Down Massless Dark Photons in Kaon Physics

    Science.gov (United States)

    Fabbrichesi, M.; Gabrielli, E.; Mele, B.

    2017-07-01

    If dark photons are massless, they couple to standard-model particles only via higher dimensional operators, while direct (renormalizable) interactions induced by kinetic mixing, which motivates most of the current experimental searches, are absent. We consider the effect of possible flavor-changing magnetic-dipole couplings of massless dark photons in kaon physics. In particular, we study the branching ratio for the process K+→π+π0γ ¯ with a simplified-model approach, assuming the chiral quark model to evaluate the hadronic matrix element. Possible effects in the K0-K¯ 0 mixing are taken into account. We find that branching ratios up to O (10-7) are allowed—depending on the dark-sector masses and couplings. Such large branching ratios for K+→π+π0γ ¯ could be of interest for experiments dedicated to rare K+ decays like NA62 at CERN, where γ ¯ can be detected as a massless invisible system.

  10. Proposal for a CLEO precision vertex detector

    International Nuclear Information System (INIS)

    1991-01-01

    Fermilab experiment E691 and CERN experiment NA32 have demonstrated the enormous power of precision vertexing for studying heavy quark physics. Nearly all collider experiments now have or are installing precision vertex detectors. This is a proposal for a precision vertex detector for CLEO, which will be the pre-eminent heavy quark experiment for at least the next 5 years. The purpose of a precision vertex detector for CLEO is to enhance the capabilities for isolating B, charm, and tau decays and to make it possible to measure the decay time. The precision vertex detector will also significantly improve strange particle identification and help with the tracking. The installation and use of this detector at CLEO is an important step in developing a vertex detector for an asymmetric B factory and therefore in observing CP violation in B decays. The CLEO environment imposes a number of unique conditions and challenges. The machine will be operating near the γ (4S) in energy. This means that B's are produced with a very small velocity and travel a distance about 1/2 that of the expected vertex position resolution. As a consequence B decay time information will not be useful for most physics. On the other hand, the charm products of B decays have a higher velocity. For the long lived D + in particular, vertex information can be used to isolate the charm particle on an event-by-event basis. This helps significantly in reconstructing B's. The vertex resolution for D's from B's is limited by multiple Coulomb scattering of the necessarily rather low momentum tracks. As a consequence it is essential to minimize the material, as measured in radiation lengths, in the beam pip and the vertex detector itself. It is also essential to build the beam pipe and detector with the smallest possible radius

  11. The STAR Vertex Position Detector

    Energy Technology Data Exchange (ETDEWEB)

    Llope, W.J., E-mail: llope@rice.edu [Rice University, Houston, TX 77005 (United States); Zhou, J.; Nussbaum, T. [Rice University, Houston, TX 77005 (United States); Hoffmann, G.W. [University of Texas, Austin, TX 78712 (United States); Asselta, K. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Brandenburg, J.D.; Butterworth, J. [Rice University, Houston, TX 77005 (United States); Camarda, T.; Christie, W. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Crawford, H.J. [University of California, Berkeley, CA 94720 (United States); Dong, X. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Engelage, J. [University of California, Berkeley, CA 94720 (United States); Eppley, G.; Geurts, F. [Rice University, Houston, TX 77005 (United States); Hammond, J. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Judd, E. [University of California, Berkeley, CA 94720 (United States); McDonald, D.L. [Rice University, Houston, TX 77005 (United States); Perkins, C. [University of California, Berkeley, CA 94720 (United States); Ruan, L.; Scheblein, J. [Brookhaven National Laboratory, Upton, NY 11973 (United States); and others

    2014-09-21

    The 2×3 channel pseudo Vertex Position Detector (pVPD) in the STAR experiment at RHIC has been upgraded to a 2×19 channel detector in the same acceptance, called the Vertex Position Detector (VPD). This detector is fully integrated into the STAR trigger system and provides the primary input to the minimum-bias trigger in Au+Au collisions. The information from the detector is used both in the STAR Level-0 trigger and offline to measure the location of the primary collision vertex along the beam pipe and the event “start time” needed by other fast-timing detectors in STAR. The offline timing resolution of single detector channels in full-energy Au+Au collisions is ∼100 ps, resulting in a start time resolution of a few tens of picoseconds and a resolution on the primary vertex location of ∼1 cm.

  12. Two-loop master integrals for the leading QCD corrections to the Higgs coupling to a W pair and to the triple gauge couplings ZWW and γ{sup *}WW

    Energy Technology Data Exchange (ETDEWEB)

    Di Vita, Stefano [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Mastrolia, Pierpaolo; Primo, Amedeo [Padova Univ. (Italy). Dipt. di Fisica ed Astronomia; INFN, Padova (Italy); Schubert, Ulrich [Argonne National Laboratory, Argonne, IL (United States). High Energy Physics Div.

    2017-02-15

    We compute the two-loop master integrals required for the leading QCD corrections to the interaction vertex of a massive neutral boson X{sup 0}, e.g. H,Z or γ*, with a pair of W bosons, mediated by a SU(2){sub L} quark doublet composed of one massive and one massless flavor. All the external legs are allowed to have arbitrary invariant masses. The Magnus exponential is employed to identify a set of master integrals that, around d=4 space-time dimensions, obey a canonical system of differential equations. The canonical master integrals are given as a Taylor series in ε=(4-d)/2, up to order four, with coeffcients written as combination of Goncharov polylogarithms, respectively up to weight four. In the context of the Standard Model, our results are relevant for the mixed EW-QCD corrections to the Higgs decay to a W pair, as well as to the production channels obtained by crossing, and to the triple gauge boson vertices ZWW and γ{sup *}WW.

  13. Two-loop master integrals for the leading QCD corrections to the Higgs coupling to a W pair and to the triple gauge couplings ZWW and γ{sup ∗}WW

    Energy Technology Data Exchange (ETDEWEB)

    Vita, Stefano Di [DESY,Notkestraße 85, D-22607 Hamburg (Germany); Mastrolia, Pierpaolo; Primo, Amedeo [Dipartimento di Fisica ed Astronomia, Università di Padova,Via Marzolo 8, 35131 Padova (Italy); INFN - Sezione di Padova,Via Marzolo 8, 35131 Padova (Italy); Schubert, Ulrich [High Energy Physics Division, Argonne National Laboratory,Argonne, IL 60439 (United States)

    2017-04-03

    We compute the two-loop master integrals required for the leading QCD corrections to the interaction vertex of a massive neutral boson X{sup 0}, e.g. H,Z or γ{sup ∗}, with a pair of W bosons, mediated by a SU(2){sub L} quark doublet composed of one massive and one massless flavor. All the external legs are allowed to have arbitrary invariant masses. The Magnus exponential is employed to identify a set of master integrals that, around d=4 space-time dimensions, obey a canonical system of differential equations. The canonical master integrals are given as a Taylor series in ϵ=(4−d)/2, up to order four, with coefficients written as combination of Goncharov polylogarithms, respectively up to weight four. In the context of the Standard Model, our results are relevant for the mixed EW-QCD corrections to the Higgs decay to a W pair, as well as to the production channels obtained by crossing, and to the triple gauge boson vertices ZWW and γ{sup ∗}WW.

  14. Quantum Prisoners' Dilemma in Fluctuating Massless Scalar Field

    Science.gov (United States)

    Huang, Zhiming

    2017-12-01

    Quantum systems are easily affected by external environment. In this paper, we investigate the influences of external massless scalar field to quantum Prisoners' Dilemma (QPD) game. We firstly derive the master equation that describes the system evolution with initial maximally entangled state. Then, we discuss the effects of a fluctuating massless scalar field on the game's properties such as payoff, Nash equilibrium, and symmetry. We find that for different game strategies, vacuum fluctuation has different effects on payoff. Nash equilibrium is broken but the symmetry of the game is not violated.

  15. Biricodar. Vertex Pharmaceuticals.

    Science.gov (United States)

    Dey, Saibal

    2002-05-01

    Vertex is developing biricodar as a chemosensitizing agent designed to restore the effectiveness of chemotherapeutic agents in tumor multidrug resistance. By November 1998, phase II trials had commenced for biricodar, in combination with chemotherapy, for five common cancer indications: breast, ovarian, soft-tissue sarcomas, small cell lung cancer and prostate cancer. Phase II trials were ongoing in January 2002. By March 2000, Vertex was the sole developer of biricodar, as an agreement made in 1996 with BioChem Pharma (now Shire Pharmaceuticals), for the development and marketing of biricodar in Canada was terminated. Biricodar is the free base compound, which also has a citrate salt analog known as VX-710-3. Vertex has published three patents, WO-09615101, WO-09636630 and WO-09736869, disclosing derivatives of biricodar that are claimed for the treatment of multidrug resistant protein and P-glycoprotein-mediated multidrug resistant tumors. In January 2002, a Banc of America analyst report forecast that biricodar had a 30% chance of reaching the market with a launch date in the second half of 2005, with peak sales estimated at $250 million.

  16. Four loop massless propagators: An algebraic evaluation of all master integrals

    International Nuclear Information System (INIS)

    Baikov, P.A.; Chetyrkin, K.G.

    2010-01-01

    The old 'glue-and-cut' symmetry of massless propagators, first established in Ref. (Chetyrkin and Tkachov, 1981), leads -after reduction to master integrals is performed - to a host of non-trivial relations between the latter. The relations constrain the master integrals so tightly that they all can be analytically expressed in terms of only few, essentially trivial, watermelon-like integrals. As a consequence we arrive at explicit analytical results for all master integrals appearing in the process of reduction of massless propagators at three and four loops. The transcendental structure of the results suggests a clean explanation of the well-known mystery of the absence of even zetas (ζ 2n ) in the Adler function and other similar functions essentially reducible to massless propagators. Once a reduction of massless propagators at five loops is available, our approach should be also applicable for explicitly performing the corresponding five-loop master integrals.

  17. On massless representations of the Q-deformed Poincare algebra

    International Nuclear Information System (INIS)

    Ogievetsky, O.; Pillin, M.; Schmidke, W.B.; Wess, J.

    1993-01-01

    This talk is devoted to the construction of massless representations of the q-deformed Poincare algebra. In section 2 we give Hilbert space representations of the SL q (2, C)-covariant quantum space. We then show in the next section how the generators of the q-Poincare algebra can be expressed in terms of operators which live in the light cone. The q-deformed massless one-particle states are considered in section 4. (orig.)

  18. Massless gluino and pseudoscalar meson family

    International Nuclear Information System (INIS)

    Smilga, A.V.; Vysotskij, M.I.

    1982-01-01

    It is shown that masslessness of the glUino leads necessarily to the existence of the light isosinglet pseudoscalar boson not observed in experiment. Thus, any realistic supersymmetry model must include the mechanism for generating the gluino mass

  19. Time-dependent massless Dirac fermions in graphene

    Energy Technology Data Exchange (ETDEWEB)

    Khantoul, Boubakeur, E-mail: bobphys@gmail.com [Department of Mathematics, City University London, Northampton Square, London EC1V 0HB (United Kingdom); Department of Physics, University of Jijel, BP 98, Ouled Aissa, 18000 Jijel (Algeria); Fring, Andreas, E-mail: a.fring@city.ac.uk [Department of Mathematics, City University London, Northampton Square, London EC1V 0HB (United Kingdom)

    2015-10-30

    Using the Lewis–Riesenfeld method of invariants we construct explicit analytical solutions for the massless Dirac equation in 2+1 dimensions describing quasi-particles in graphene. The Hamiltonian of the system considered contains some explicit time-dependence in addition to one resulting from being minimally coupled to a time-dependent vector potential. The eigenvalue equations for the two spinor components of the Lewis–Riesenfeld invariant are found to decouple into a pair of supersymmetric invariants in a similar fashion as the known decoupling for the time-independent Dirac Hamiltonians. - Highlights: • An explicit analytical solution for a massless 2+1 dimensional time-dependent Dirac equation is found. • All steps of the Lewis–Riesenfeld method have been carried out.

  20. ''Massless'' vector field in de Sitter universe

    International Nuclear Information System (INIS)

    Garidi, T.; Gazeau, J.-P.; Rouhani, S.; Takook, M. V.

    2008-01-01

    We proceed to the quantization of the massless vector field in the de Sitter (dS) space. This work is the natural continuation of a previous article devoted to the quantization of the dS massive vector field [J. P. Gazeau and M. V. Takook, J. Math. Phys. 41, 5920 (2000); T. Garidi et al., ibid. 43, 6379 (2002).] The term ''massless'' is used by reference to conformal invariance and propagation on the dS lightcone whereas ''massive'' refers to those dS fields which unambiguously contract to Minkowskian massive fields at zero curvature. Due to the combined occurrences of gauge invariance and indefinite metric, the covariant quantization of the massless vector field requires an indecomposable representation of the de Sitter group. We work with the gauge fixing corresponding to the simplest Gupta-Bleuler structure. The field operator is defined with the help of coordinate-independent de Sitter waves (the modes). The latter are simple to manipulate and most adapted to group theoretical approaches. The physical states characterized by the divergencelessness condition are, for instance, easy to identify. The whole construction is based on analyticity requirements in the complexified pseudo-Riemannian manifold for the modes and the two-point function

  1. ``Massless'' vector field in de Sitter universe

    Science.gov (United States)

    Garidi, T.; Gazeau, J.-P.; Rouhani, S.; Takook, M. V.

    2008-03-01

    We proceed to the quantization of the massless vector field in the de Sitter (dS) space. This work is the natural continuation of a previous article devoted to the quantization of the dS massive vector field [J. P. Gazeau and M. V. Takook, J. Math. Phys. 41, 5920 (2000); T. Garidi et al., ibid. 43, 6379 (2002).] The term ``massless'' is used by reference to conformal invariance and propagation on the dS lightcone whereas ``massive'' refers to those dS fields which unambiguously contract to Minkowskian massive fields at zero curvature. Due to the combined occurrences of gauge invariance and indefinite metric, the covariant quantization of the massless vector field requires an indecomposable representation of the de Sitter group. We work with the gauge fixing corresponding to the simplest Gupta-Bleuler structure. The field operator is defined with the help of coordinate-independent de Sitter waves (the modes). The latter are simple to manipulate and most adapted to group theoretical approaches. The physical states characterized by the divergencelessness condition are, for instance, easy to identify. The whole construction is based on analyticity requirements in the complexified pseudo-Riemannian manifold for the modes and the two-point function.

  2. Four loop massless propagators: An algebraic evaluation of all master integrals

    Energy Technology Data Exchange (ETDEWEB)

    Baikov, P.A., E-mail: baikov@theory.sinp.msu.r [Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow 119991 (Russian Federation); Chetyrkin, K.G., E-mail: konstantin.chetyrkin@kit.ed [Institut fuer Theoretische Teilchenphysik, Karlsruhe Institute of Technology (KIT), D-76128 Karlsruhe (Germany)] [Institute for Nuclear Research, Russian Academy of Sciences, Moscow 117312 (Russian Federation)

    2010-10-01

    The old 'glue-and-cut' symmetry of massless propagators, first established in Ref. (Chetyrkin and Tkachov, 1981), leads -after reduction to master integrals is performed - to a host of non-trivial relations between the latter. The relations constrain the master integrals so tightly that they all can be analytically expressed in terms of only few, essentially trivial, watermelon-like integrals. As a consequence we arrive at explicit analytical results for all master integrals appearing in the process of reduction of massless propagators at three and four loops. The transcendental structure of the results suggests a clean explanation of the well-known mystery of the absence of even zetas ({zeta}{sub 2n}) in the Adler function and other similar functions essentially reducible to massless propagators. Once a reduction of massless propagators at five loops is available, our approach should be also applicable for explicitly performing the corresponding five-loop master integrals.

  3. New non-linear modified massless Klein-Gordon equation

    Energy Technology Data Exchange (ETDEWEB)

    Asenjo, Felipe A. [Universidad Adolfo Ibanez, UAI Physics Center, Santiago (Chile); Universidad Adolfo Ibanez, Facultad de Ingenieria y Ciencias, Santiago (Chile); Hojman, Sergio A. [Universidad Adolfo Ibanez, UAI Physics Center, Santiago (Chile); Universidad Adolfo Ibanez, Departamento de Ciencias, Facultad de Artes Liberales, Santiago (Chile); Universidad de Chile, Departamento de Fisica, Facultad de Ciencias, Santiago (Chile); Centro de Recursos Educativos Avanzados, CREA, Santiago (Chile)

    2017-11-15

    The massless Klein-Gordon equation on arbitrary curved backgrounds allows for solutions which develop ''tails'' inside the light cone and, therefore, do not strictly follow null geodesics as discovered by DeWitt and Brehme almost 60 years ago. A modification of the massless Klein-Gordon equation is presented, which always exhibits null geodesic propagation of waves on arbitrary curved spacetimes. This new equation is derived from a Lagrangian which exhibits current-current interaction. Its non-linearity is due to a self-coupling term which is related to the quantum mechanical Bohm potential. (orig.)

  4. Massless fermions and Kaluza--Klein theory with torsion

    International Nuclear Information System (INIS)

    Wu, Y.; Zee, A.

    1984-01-01

    A pure Kaluza--Klein theory contains no massless fermion in four-dimensional theory. We investigate the effect of introducing torsion on the internal manifold and find that there are massless fermions. The hope is that given an isometry group the representation to which these fermions belong is fixed, in contrast to the situation in Yang--Mills theory. We show that this is indeed the case, but the representations do not appear to be the ones favored by current theoretical prejudice. The cases with parallelizable torsions on a group manifold as the internal manifold are analyzed in detail

  5. Massive and massless supersymmetry: Multiplet structure and unitary irreducible representations

    International Nuclear Information System (INIS)

    Jarvis, P.D.

    1976-01-01

    UIR's of the supersymmetry algebra for the massive and massless cases are analyzed covariantly (without the use of induced representations) in terms of their component spins. For the massive case normalized basis vectors vertical-barp 2 >0, j 0 ; sigma; pjlambda> are constructed, where j 0 is the ''superspin'' and sigma is an additional quantum number serving to distinguish the different vertical-barpjlambda>, the constituent p 2 >0, spin-j UIR's of the Poincare group. For the massless case, normalized basis vectors vertical-barp 2 =0, lambda 0 ; plambda> are similarly constructed, where lambda 0 is the ''superhelicity.'' Matrix elements of the supersymmetry generators, in these bases, are explicitly given. The ''sigma basis'' is used to define weight diagrams for the massive UIR's of supersymmetry, and their properties are briefly described. Eigenfunctions ω/sub sigma/(theta) are also defined, and their connection with the reduction of higher spin massive superfields PHI/subJ/(x,theta) is discussed. Finally, it is shown how gauge dependence necessarily arises with certain massless superfields. The massless scalar superfield, both gauge-dependent and gauge-independent, is discussed as an example

  6. A Macdonald refined topological vertex

    Science.gov (United States)

    Foda, Omar; Wu, Jian-Feng

    2017-07-01

    We consider the refined topological vertex of Iqbal et al (2009 J. High Energy Phys. JHEP10(2009)069), as a function of two parameters ≤ft\\lgroup x, y \\right\\rgroup , and deform it by introducing the Macdonald parameters ≤ft\\lgroup q, t \\right\\rgroup , as in the work of Vuletić on plane partitions (Vuletić M 2009 Trans. Am. Math. Soc. 361 2789-804), to obtain ‘a Macdonald refined topological vertex’. In the limit q → t , we recover the refined topological vertex of Iqbal et al and in the limit x → y , we obtain a qt-deformation of the original topological vertex of Aganagic et al (2005 Commun. Math. Phys. 25 425-78). Copies of the vertex can be glued to obtain qt-deformed 5D instanton partition functions that have well-defined 4D limits and, for generic values of ≤ft\\lgroup q, t\\right\\rgroup , contain infinite-towers of poles for every pole present in the limit q → t .

  7. Vertex algebras and mirror symmetry

    International Nuclear Information System (INIS)

    Borisov, L.A.

    2001-01-01

    Mirror Symmetry for Calabi-Yau hypersurfaces in toric varieties is by now well established. However, previous approaches to it did not uncover the underlying reason for mirror varieties to be mirror. We are able to calculate explicitly vertex algebras that correspond to holomorphic parts of A and B models of Calabi-Yau hypersurfaces and complete intersections in toric varieties. We establish the relation between these vertex algebras for mirror Calabi-Yau manifolds. This should eventually allow us to rewrite the whole story of toric mirror symmetry in the language of sheaves of vertex algebras. Our approach is purely algebraic and involves simple techniques from toric geometry and homological algebra, as well as some basic results of the theory of vertex algebras. Ideas of this paper may also be useful in other problems related to maps from curves to algebraic varieties.This paper could also be of interest to physicists, because it contains explicit description of holomorphic parts of A and B models of Calabi-Yau hypersurfaces and complete intersections in terms of free bosons and fermions. (orig.)

  8. Can massless neutrinos dominate the universe

    International Nuclear Information System (INIS)

    Kolb, E.W.

    1980-01-01

    The restrictions from cosmological considerations on masses and lifetimes of neutral, weakly interacting fermions are reviewed. In particular, the possibility that the massless decay products of a heavy neutrino dominate the energy density of the present universe is discussed in detail. 4 figures

  9. Limit on possible energy-dependent velocities for massless particles

    International Nuclear Information System (INIS)

    Haines, T.J.; Alexandreas, D.E.; Allen, R.C.; Biller, S.; Berley, D.; Burman, R.L.; Cady, D.R.; Chang, C.Y.; Dingus, B.L.; Dion, G.M.; Ellsworth, R.W.; Goodman, J.A.; Hoffman, C.M.; Lloyd-Evans, J.; Nagle, D.E.; Potter, M.; Sandberg, V.D.; Wilkinson, C.A.; Yodh, G.B.

    1990-01-01

    A basic tenet of special relativity is that all massless particles travel at a constant, energy-independent velocity. Astrophysical data, including observation of the Crab pulsar at ∼100 MeV and the recent detection of the pulsar in Hercules X-1 at energies ≥100 TeV, are used to place new experimental constraints on energy-dependent deviations from constant velocity for massless particles. Previous experiments reached energies ∼10 GeV; this analysis improves the previous constraints by 7 orders of magnitude

  10. On the Pomeranchuk singularity in massless vector theories

    International Nuclear Information System (INIS)

    Bartels, J.; Hamburg Univ.

    1980-06-01

    It is shown that the Pomeron in massless (abelian of nonabelian) vector theories, as derived from a perturbative high energy description which satisfies unitarity, comes as a diffusion problem in the logarithmic scale of transverse momentum. For a realistic theory there are reasons to expect that this diffusion should come to a stop: (a) the long range forces of the massless gluons should be screened, (b) the Pomeranchuk singularity in the j-plane should be t-dependant, and (c) there should not be a discontinuity in the zero mass limit at t = 0 or in the t 0 limit of the massless case. In the third part we outline a scheme for summing all diagrams which are required by unitarity. It uses reggeon field theory in zero transverse dimensions and leads to: (i) the diffusion comes to a stop (zero drift and zero diffusion constant); (ii) the total cross section is constant (up to powers of lns); (iii) in order to give a meaning to the divergent perturbation expansion, one has to add a nonperturbative term of the order exp(-const/g 2 ). (orig.)

  11. Vertex Reconstruction in ATLAS Run II

    CERN Document Server

    Zhang, Matt; The ATLAS collaboration

    2016-01-01

    Vertex reconstruction is the process of taking reconstructed tracks and using them to determine the locations of proton collisions. In this poster we present the performance of our current vertex reconstruction algorithm, and look at investigations into potential improvements from a new seed finding method.

  12. The vertex Zagreb indices of some graph operations

    Directory of Open Access Journals (Sweden)

    N. De

    2016-12-01

    Full Text Available Recently, Tavakoli et al. introduced a new version of Zagreb indices, named as vertex Zagreb indices. In this paper explicit expressions of different graphs operations of vertex Zagreb indices are presented and also as an application, explicit formulas for vertex Zagreb indices of some chemical graphs are obtained.

  13. On a manifestation of the anomalies in the massless QED

    International Nuclear Information System (INIS)

    Gorskij, A.S.

    1989-01-01

    The questions concerned with the axial and conformal anomalies in the massless QED are discussed. It is shown that the interaction of the longitudinal real photons is proportional to the β function of the theory and the corresponding matrix element L |Θ αβ |γ L > where Θ αβ is energy-momentum tensor has a common features with the nonvanishing matrix element α |γ> in the massless limit. 7 refs.; 2 figs

  14. Fluctuations in two-dimensional six-vertex systems

    International Nuclear Information System (INIS)

    Youngblood, R.W.; Axe, J.D.; McCoy, B.M.

    1979-01-01

    The character of polarization correlations in six-vertex systems is discussed. With the aid of a connection between the 1-d Heisenberg--Ising chain and the six-vertex problem, existing results for the chain correlations are used to obtain information about long-wavelength polarization correlations in six-vertex models. These results are compared with a neutron scattering study of 2-d polarization correlations in the layered compound copper formate tetrahydrate. Because the six-vertex model is equivalent to a particular roughening model, these results also explicitly predict the critical behavior of that roughening model just above its roughening temperature. The results correspond to the predictions of Kosterlitz and Thouless for the phase transition in the 2-d Coulomb gas. 5 figures

  15. Loop vertex expansion for higher-order interactions

    Science.gov (United States)

    Rivasseau, Vincent

    2018-05-01

    This note provides an extension of the constructive loop vertex expansion to stable interactions of arbitrarily high order, opening the way to many applications. We treat in detail the example of the (\\bar{φ } φ )^p field theory in zero dimension. We find that the important feature to extend the loop vertex expansion is not to use an intermediate field representation, but rather to force integration of exactly one particular field per vertex of the initial action.

  16. The spectrum of a vertex model and related spin one chain sitting in a genus five curve

    Directory of Open Access Journals (Sweden)

    M.J. Martins

    2017-11-01

    Full Text Available We derive the transfer matrix eigenvalues of a three-state vertex model whose weights are based on a R-matrix not of difference form with spectral parameters lying on a genus five curve. We have shown that the basic building blocks for both the transfer matrix eigenvalues and Bethe equations can be expressed in terms of meromorphic functions on an elliptic curve. We discuss the properties of an underlying spin one chain originated from a particular choice of the R-matrix second spectral parameter. We present numerical and analytical evidences that the respective low-energy excitations can be gapped or massless depending on the strength of the interaction coupling. In the massive phase we provide analytical and numerical evidences in favor of an exact expression for the lowest energy gap. We point out that the critical point separating these two distinct physical regimes coincides with the one in which the weights geometry degenerate into union of genus one curves.

  17. The spectrum of a vertex model and related spin one chain sitting in a genus five curve

    Science.gov (United States)

    Martins, M. J.

    2017-11-01

    We derive the transfer matrix eigenvalues of a three-state vertex model whose weights are based on a R-matrix not of difference form with spectral parameters lying on a genus five curve. We have shown that the basic building blocks for both the transfer matrix eigenvalues and Bethe equations can be expressed in terms of meromorphic functions on an elliptic curve. We discuss the properties of an underlying spin one chain originated from a particular choice of the R-matrix second spectral parameter. We present numerical and analytical evidences that the respective low-energy excitations can be gapped or massless depending on the strength of the interaction coupling. In the massive phase we provide analytical and numerical evidences in favor of an exact expression for the lowest energy gap. We point out that the critical point separating these two distinct physical regimes coincides with the one in which the weights geometry degenerate into union of genus one curves.

  18. Secondary vertex detection at the SLC

    International Nuclear Information System (INIS)

    Anon.

    1982-01-01

    The vertex topology of a high energy e + e - interaction contains a wealth of information. These interactions copiously produce the tau lepton and hadrons containing the c and b quarks; all these particles decay within a millimeter or so of the primary interaction point, giving these interactions a rich secondary vertex structure. With suitable detectors, one can hope to reconstruct these vertices and so tag events with tau's, c's and b's; measure lifetimes and mixing angles; and perhaps directly measure the flavor of c and b jets. The spatial resolution and track-pair resolution required of such detectors demand detector development, but several techniques, including solid state microstrip and CCD detectors, pressurized drift chambers, and holographic bubbble chambers look promising. Vertex detection in the colliding beam environment has already yielded a measurement of the tau lifetime. The SLC, with its micron-sized beam and one-centimeter sized beam pipe is uniquely suited for these studies. Compared to conventional storage rings, it offers a well-defined and minute primary interaction point, the possibility of locating a detector within a centimeter of the interaction (an order of magnitude improvement over LEP), negligibly thin beam pipes, and a repetition rate low enough to permit novel detectors and readout schemes. This report discusses the physics accessible with vertex detectors, depicts the physics environment at 100 GeV - particle multiplicities, momenta, angular correlations, and topologies of charm decays, sketches the elements of a vertex detector, and, through some model studies evaluates the spatial resolution and track-pair resolution requirements, and summarizes the detector technologies which seem most promising for vertex detection

  19. No parity anomaly in massless QED3: A BPHZL approach

    International Nuclear Information System (INIS)

    Del Cima, O.M.; Franco, D.H.T.; Piguet, O.; Schweda, M.

    2009-01-01

    In this Letter we call into question the perturbatively parity breakdown at 1-loop for the massless QED 3 frequently claimed in the literature. As long as perturbative quantum field theory is concerned, whether a parity anomaly owing to radiative corrections exists or not shall be definitely proved by using a renormalization method independent of any regularization scheme. Such a problem has been investigated in the framework of BPHZL renormalization method, by adopting the Lowenstein-Zimmermann subtraction scheme. The 1-loop parity-odd contribution to the vacuum-polarization tensor is explicitly computed in the framework of the BPHZL renormalization method. It is shown that a Chern-Simons term is generated at that order induced through the infrared subtractions - which violate parity. We show then that, what is called 'parity anomaly', is in fact a parity-odd counterterm needed for restauring parity.

  20. Locking mechanisms in degree-4 vertex origami structures

    Science.gov (United States)

    Fang, Hongbin; Li, Suyi; Xu, Jian; Wang, K. W.

    2016-04-01

    Origami has emerged as a potential tool for the design of mechanical metamaterials and metastructures whose novel properties originate from their crease patterns. Most of the attention in origami engineering has focused on the wellknown Miura-Ori, a folded tessellation that is flat-foldable for folded sheet and stacked blocks. This study advances the state of the art and expands the research field to investigate generic degree-4 vertex (4-vertex) origami, with a focus on facet-binding. In order to understand how facet-binding attributes to the mechanical properties of 4-vertex origami structures, geometries of the 4-vertex origami cells are analyzed and analytically expressed. Through repeating and stacking 4-vertex cells, origami sheets and stacked origami blocks can be constructed. Geometry analyses discover four mechanisms that will lead to the self-locking of 4-vertex origami cells, sheets, and stacked blocks: in-cell facet-binding, inlayer facet-binding, inter-layer facet binding, and in-layer and inter-layer facet-bindings. These mechanisms and the predicted self-locking phenomena are verified through 3D simulations and prototype experiments. Finally, this paper briefly introduces the unusual mechanical properties caused by the locking of 4-vertex origami structures. The research reported in this paper could foster a new breed of self-locking structures with various engineering applications.

  1. Scale transformation and massless limit in neutral-vector field theory. [Gauge transformation unified theory

    Energy Technology Data Exchange (ETDEWEB)

    Kubo, R; Takahashi, Y; Yokoyama, K

    1975-01-01

    In a wide class of neutral vector field theories, in which massive and massless fields are described in a unified way and a unique massless limit exists to quantum electrodynamics in covariant gauges, the commutability of the scale transformation and the massless limit is examined. It is shown that there occurs no anomaly with respect to the assignment for scale dimensions of relevant fields. Connection of scale transformation and gauge transformation is also discussed.

  2. On fermionic representation of the framed topological vertex

    International Nuclear Information System (INIS)

    Deng, Fusheng; Zhou, Jian

    2015-01-01

    The Gromov-Witten invariants of ℂ"3 with branes is encoded in the topological vertex which has a very complicated combinatorial expression. A simple formula for the topological vertex was proposed by Aganagic et al. in the fermionic picture. We will propose a similar formula for the framed topological vertex and prove it in the case when there are one or two branes.

  3. Vertex Reconstruction at STAR: Overview and Performance Evaluation

    Science.gov (United States)

    Smirnov, D.; Lauret, J.; Perevoztchikov, V.; Van Buren, G.; Webb, J.

    2017-10-01

    The STAR experiment at the Relativistic Heavy Ion Collider (RHIC) has a rich physics program ranging from studies of the Quark Gluon Plasma to the exploration of the spin structure of the proton. Many measurements carried out by the STAR collaboration rely on the efficient reconstruction and precise knowledge of the position of the primary-interaction vertex. Throughout the years two main vertex finders have been predominantly utilized in event reconstruction by the experiment: MinutVF and PPV with their application domains focusing on heavy ion and proton-proton events respectively. In this work we give a brief overview and discuss recent improvements to the vertex finding algorithms implemented in the STAR software library. In our studies we focus on the finding efficiency and the quality of the reconstructed primary vertex. We examine the effect of an additional constraint, imposed by an independent measurement of the beam line position, when it is applied during the fit. We evaluate the significance of the improved primary vertex resolution on identification of the secondary decay vertices occurring inside the beam pipe. Finally, we present a method and its software implementation developed to measure the performance of the primary vertex reconstruction algorithms.

  4. Massless spectra and gauge couplings at one-loop on non-factorisable toroidal orientifolds

    Science.gov (United States)

    Berasaluce-González, Mikel; Honecker, Gabriele; Seifert, Alexander

    2018-01-01

    So-called 'non-factorisable' toroidal orbifolds can be rewritten in a factorised form as a product of three two-tori by imposing an additional shift symmetry. This finding of Blaszczyk et al. [1] provides a new avenue to Conformal Field Theory methods, by which the vector-like massless matter spectrum - and thereby the type of gauge group enhancement on orientifold invariant fractional D6-branes - and the one-loop corrections to the gauge couplings in Type IIA orientifold theories can be computed in addition to the well-established chiral matter spectrum derived from topological intersection numbers among three-cycles. We demonstrate this framework for the Z4 × ΩR orientifolds on the A3 ×A1 ×B2-type torus. As observed before for factorisable backgrounds, also here the one-loop correction can drive the gauge groups to stronger coupling as demonstrated by means of a four-generation Pati-Salam example.

  5. New vertex reconstruction algorithms for CMS

    CERN Document Server

    Frühwirth, R; Prokofiev, Kirill; Speer, T.; Vanlaer, P.; Chabanat, E.; Estre, N.

    2003-01-01

    The reconstruction of interaction vertices can be decomposed into a pattern recognition problem (``vertex finding'') and a statistical problem (``vertex fitting''). We briefly review classical methods. We introduce novel approaches and motivate them in the framework of high-luminosity experiments like at the LHC. We then show comparisons with the classical methods in relevant physics channels

  6. Smarandachely Adjacent-Vertex-Distinguishing Proper Edge Chromatic Number of Cm∨Kn

    OpenAIRE

    Shunqin Liu

    2016-01-01

    According to different conditions, researchers have defined a great deal of coloring problems and the corresponding chromatic numbers. Such as, adjacent-vertex-distinguishing total chromatic number, adjacent-vertex-distinguishing proper edge chromatic number, smarandachely-adjacent-vertex-distinguishing proper edge chromatic number, smarandachely-adjacent-vertex-distinguishing proper total chromatic number. And we focus on the smarandachely adjacent-vertex-distinguishing proper edge chromatic...

  7. Vertex routing models

    International Nuclear Information System (INIS)

    Markovic, D; Gros, C

    2009-01-01

    A class of models describing the flow of information within networks via routing processes is proposed and investigated, concentrating on the effects of memory traces on the global properties. The long-term flow of information is governed by cyclic attractors, allowing to define a measure for the information centrality of a vertex given by the number of attractors passing through this vertex. We find the number of vertices having a nonzero information centrality to be extensive/subextensive for models with/without a memory trace in the thermodynamic limit. We evaluate the distribution of the number of cycles, of the cycle length and of the maximal basins of attraction, finding a complete scaling collapse in the thermodynamic limit for the latter. Possible implications of our results for the information flow in social networks are discussed.

  8. Genus Ranges of 4-Regular Rigid Vertex Graphs.

    Science.gov (United States)

    Buck, Dorothy; Dolzhenko, Egor; Jonoska, Nataša; Saito, Masahico; Valencia, Karin

    2015-01-01

    A rigid vertex of a graph is one that has a prescribed cyclic order of its incident edges. We study orientable genus ranges of 4-regular rigid vertex graphs. The (orientable) genus range is a set of genera values over all orientable surfaces into which a graph is embedded cellularly, and the embeddings of rigid vertex graphs are required to preserve the prescribed cyclic order of incident edges at every vertex. The genus ranges of 4-regular rigid vertex graphs are sets of consecutive integers, and we address two questions: which intervals of integers appear as genus ranges of such graphs, and what types of graphs realize a given genus range. For graphs with 2 n vertices ( n > 1), we prove that all intervals [ a, b ] for all a genus ranges. For graphs with 2 n - 1 vertices ( n ≥ 1), we prove that all intervals [ a, b ] for all a genus ranges. We also provide constructions of graphs that realize these ranges.

  9. Hydrodynamical model with massless constituents

    International Nuclear Information System (INIS)

    Chiu, C.B.; Wang, K.H.

    1974-01-01

    Within the constituent hydrodynamical model, it is shown that the total number of constituents is conserved, if these constituents are massless and satisfy the Fermi-Dirac distribution. A simple scheme for the transition from the constituent-phase to the hadron-phase is suggested, and the hadron inclusive momentum spectra are presented for this case. This phase transition scheme predicts the average transverse momentum of meson resonances which is compatible with the data. (U.S.)

  10. Vertex Accentuation in Female Pattern Hair Loss in Asians

    Directory of Open Access Journals (Sweden)

    Chavalit Supsrisunjai

    2016-05-01

    Full Text Available Background: The most common cause of hair loss seen in women is female pattern hair loss (FPHL, also known as female androgenetic alopecia. It affects the central part of the scalp, but spares the frontal hairline. Frontal accentuation was also described by Olsen. In Asian women, vertex thinning patterns are frequently developed, but there has been no report about vertex thinning pattern in female pattern hair loss. Objective: To find prevalence of vertex accentuation in female pattern hair loss (FPHL in Asian women. Methods: Scalp hair counting (n/cm2 were measured at 3 different areas; vertex, mid scalp and frontal area respectively by digital dermoscope (Dino digital AM-413T. Visual counting and photography were performed. Outcomes were evaluated by gross appearance of vertex thinning and/or hair density <120 /cm2 in any of 3 areas. Results: 143 patients were evaluated. Mean age was 45.54 years. Of the hair loss type, 36.4% were mid-scalp, 33.6% were vertex accentuation and 30.1% were frontal accentuation, respectively. Age was not significantly different among the 3 types of hair loss (P- value 0.859. Conclusion: Although the most common female pattern hair loss type is diffuse type (Ludwig type, vertex accentuation pattern is the second most common pattern in this study. This study is the first to mention “Vertex accentuation” to be another pattern for FPHL.

  11. Quasinormal modes for massless topological black holes

    International Nuclear Information System (INIS)

    Aros, Rodrigo; Martinez, Cristian; Troncoso, Ricardo; Zanelli, Jorge

    2003-01-01

    An exact expression for the quasinormal modes of scalar perturbation on a massless topological black hole in four and higher dimensions is presented. The massive scalar field is nonminimally coupled to the curvature, and the horizon geometry is assumed to have a negative constant curvature

  12. Cubic interaction in extended theories of massless higher-spin fields

    Energy Technology Data Exchange (ETDEWEB)

    Fradkin, E S; Vasiliev, M A

    1987-08-17

    A cubic interaction of all massless higher-spin fields with s greater than or equal to 1 is constructed, based on the extended higher-spin superalgebras suggested previously by one of us (M.V.). This interaction incorporates gravitational and Yang-Mills interactions of massless higher-spin fields, which turn out to be consistent in the cubic order. An essential novel feature of the gravitational higher-spin interaction is its non-analyticity in the cosmological constant. An explicit form is found for deformed higher-spin gauge transformations leaving the action invariant.

  13. Lectures on the Topological Vertex

    CERN Document Server

    Mariño, M

    2008-01-01

    In this lectures, I will summarize the approach to Gromov–Witten invariants on toric Calabi–Yau threefolds based on large N dualities. Since the large N duality/topological vertex approach computes Gromov–Witten invariants in terms of Chern–Simons knot and link invariants, Sect. 2 is devoted to a review of these. Section 3 reviews topological strings and Gromov–Witten invariants, and gives some information about the open string case. Section 4 introduces the class of geometries we will deal with, namely toric (noncompact) Calabi–Yau manifolds, and we present a useful graphical way to represent these manifolds which constitutes the geometric core of the theory of the topological vertex. Finally, in Sect. 5, we define the vertex and present some explicit formulae for it and some simple applications. A brief Appendix contains useful information about symmetric polynomials. It has not been possible to present all the relevant background and physical derivations in this set of lectures. However, these...

  14. Tunnelling of Massive/Massless Bosons from the Apparent Horizon of FRW Universe

    Directory of Open Access Journals (Sweden)

    Kimet Jusufi

    2017-01-01

    Full Text Available We investigate the Hawking radiation of vector particles from the apparent horizon of a Friedmann-Robertson-Walker (FRW universe in the framework of quantum tunnelling method. Furthermore we use Proca equation, a relativistic wave equation for a massive/massless spin-1 particle (massless γ photons, weak massive W± and Z0 bosons, strong massless gluons, and ρ and ω mesons together with a Painlevé space-time metric for the FRW universe. We solve the Proca equation via Hamilton-Jacobi (HJ equation and the WKB approximation method. We recover the same result for the Hawking temperature associated with vector particles as in the case of scalar and Dirac particles tunnelled from outside to the inside of the apparent horizon in a FRW universe.

  15. Random matrices and the six-vertex model

    CERN Document Server

    Bleher, Pavel

    2013-01-01

    This book provides a detailed description of the Riemann-Hilbert approach (RH approach) to the asymptotic analysis of both continuous and discrete orthogonal polynomials, and applications to random matrix models as well as to the six-vertex model. The RH approach was an important ingredient in the proofs of universality in unitary matrix models. This book gives an introduction to the unitary matrix models and discusses bulk and edge universality. The six-vertex model is an exactly solvable two-dimensional model in statistical physics, and thanks to the Izergin-Korepin formula for the model with domain wall boundary conditions, its partition function matches that of a unitary matrix model with nonpolynomial interaction. The authors introduce in this book the six-vertex model and include a proof of the Izergin-Korepin formula. Using the RH approach, they explicitly calculate the leading and subleading terms in the thermodynamic asymptotic behavior of the partition function of the six-vertex model with domain wa...

  16. Massless particles, electromagnetism, and Rieffel induction

    International Nuclear Information System (INIS)

    Landsman, N.P.; Wiedemann, U.A.

    1994-06-01

    The connection between space-time covariant representations (obtained by inducing from the Lorentz group) and irreducible unitary representations (induced from Wigner's little group) of the Poincare groups is re-examined in the massless case. In the situation relevant to physics, it is found that these are related by Marsden-Weinstein reduction with respect to a gauge group. An analogous phenomenon is observed for classical massless relativistic particles. This symplectic reduction procedure can be ('second') quantized using a generalization of the Rieffel induction technique in operator algebra theory, which is carried through in detail for electromagnetism. Starting from the so-called Fermi representation of the field algebra generated by the free abelian gauge field, we construct a new ('rigged') sesquilinear form on the representation space, which is positive semi-definite, and given in terms of a Gaussian weak distribution (promeasure) on the gauge group (taken to be a Hilbert Lie group). This eventually constructs the algebra of observables of quantum electromagnetism (directly in its vacuum representation) as a representation of the so-called algebra of weak observables induced by the trivial representation of the gauge group. (orig.)

  17. Logarithmic corrections to black hole entropy from Kerr/CFT

    Energy Technology Data Exchange (ETDEWEB)

    Pathak, Abhishek [Center for the Fundamental Laws of Nature, Harvard University,Cambridge, MA 02138 (United States); Porfyriadis, Achilleas P. [Center for the Fundamental Laws of Nature, Harvard University,Cambridge, MA 02138 (United States); Department of Physics, UCSB,Santa Barbara, CA 93106 (United States); Strominger, Andrew [Center for the Fundamental Laws of Nature, Harvard University,Cambridge, MA 02138 (United States); Varela, Oscar [Center for the Fundamental Laws of Nature, Harvard University,Cambridge, MA 02138 (United States); Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut),Am Mühlenberg 1, D-14476 Potsdam (Germany); Department of Physics, Utah State University,Logan, UT 84322 (United States)

    2017-04-14

    It has been shown by A. Sen that logarithmic corrections to the black hole area-entropy law are entirely determined macroscopically from the massless particle spectrum. They therefore serve as powerful consistency checks on any proposed enumeration of quantum black hole microstates. Sen’s results include a macroscopic computation of the logarithmic corrections for a five-dimensional near extremal Kerr-Newman black hole. Here we compute these corrections microscopically using a stringy embedding of the Kerr/CFT correspondence and find perfect agreement.

  18. Logarithmic corrections to black hole entropy from Kerr/CFT

    International Nuclear Information System (INIS)

    Pathak, Abhishek; Porfyriadis, Achilleas P.; Strominger, Andrew; Varela, Oscar

    2017-01-01

    It has been shown by A. Sen that logarithmic corrections to the black hole area-entropy law are entirely determined macroscopically from the massless particle spectrum. They therefore serve as powerful consistency checks on any proposed enumeration of quantum black hole microstates. Sen’s results include a macroscopic computation of the logarithmic corrections for a five-dimensional near extremal Kerr-Newman black hole. Here we compute these corrections microscopically using a stringy embedding of the Kerr/CFT correspondence and find perfect agreement.

  19. Certain extensions of vertex operator algebras of affine type

    International Nuclear Information System (INIS)

    Li Haisheng

    2001-01-01

    We generalize Feigin and Miwa's construction of extended vertex operator (super)algebras A k (sl(2)) for other types of simple Lie algebras. For all the constructed extended vertex operator (super)algebras, irreducible modules are classified, complete reducibility of every module is proved and fusion rules are determined modulo the fusion rules for vertex operator algebras of affine type. (orig.)

  20. Drift chamber vertex detectors for SLC/LEP

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, K G

    1988-03-01

    Factors influencing the design of drift chamber vertex detectors for SLC and LEP are discussed including global strategy, chamber gas, cell design, and signal processing. The designs of the vertex chambers for the L3 and OPAL experiments at LEP and the Mark II experiment at the SLC are described.

  1. Design of a secondary-vertex trigger system

    International Nuclear Information System (INIS)

    Husby, D.; Chew, P.; Sterner, K.; Selove, W.

    1995-06-01

    For the selection of beauty and charm events with high efficiency at the Tevatron, a secondary-vertex trigger system is under design. It would operate on forward-geometry events. The system would use on-line tracking of all tracks in the vertex detector, to identify events with clearly detached secondary vertices

  2. Graph Theory. 2. Vertex Descriptors and Graph Coloring

    Directory of Open Access Journals (Sweden)

    Lorentz JÄNTSCHI

    2002-12-01

    Full Text Available This original work presents the construction of a set of ten sequence matrices and their applications for ordering vertices in graphs. For every sequence matrix three ordering criteria are applied: lexicographic ordering, based on strings of numbers, corresponding to every vertex, extracted as rows from sequence matrices; ordering by the sum of path lengths from a given vertex; and ordering by the sum of paths, starting from a given vertex. We also examine a graph that has different orderings for the above criteria. We then proceed to demonstrate that every criterion induced its own partition of graph vertex. We propose the following theoretical result: both LAVS and LVDS criteria generate identical partitioning of vertices in any graph. Finally, a coloring of graph vertices according to introduced ordering criteria was proposed.

  3. A new tool for constrained vertex fitting in ATLAS

    CERN Document Server

    Colijn, Auke Pieter; Limper, Maaike; Prokofiev, Kirill

    2009-01-01

    The precise reconstruction of trajectories of charged and neutral particles and their decay vertices is crucial for many physics analyses. Studying the tracking performance on well known benchmark channels helps to understand the properties of the ATLAS detector during the initial phase of the LHC. In order to exploit the correlations between reconstructed parameters of final state tracks having the same mother particle, a new tool for vertex fitting with possibility of simultaneous application of kinematic constraints has been developed. Using this tool on a benchmark channel such as J/psi to μ+μ− helps to correct shifts in the reconstructed curvature induced by systematic deformations of the detector.

  4. Renormalization problem in nonrenormalizable massless PHI4 theory

    International Nuclear Information System (INIS)

    Symanzik, K.

    1975-05-01

    Nonrenormalizable massless PHI 4 theory is made finite by regularization via higher derivatives in the kinetic part of the Lagrangean. The theory is shown to remain finite in the infinite cutoff limit if certain integrals over functions of one variable, with computable Taylor expansion at the origin, are finite. The values of these integrals are the only unknowns in the double series in powers of g and gsup(2/epsilon) obtained for the Green's functions in massless (PHI 4 )sub(4 + epsilon) with generic epsilon. For epsilon = 1 and epsilon = 2, these series reduce to double series in powers of g and ln g. The problems of extension to (PHI 4 )sub(4 + epsilon) with mass, of causality and unitarity, of the relation to the BPHZ formalism, and of the indeterminacy of the result are discussed. (orig.) [de

  5. Drift chamber vertex detectors for SLC/LEP

    International Nuclear Information System (INIS)

    Hayes, K.G.

    1987-03-01

    The short but measurable lifetimes of the b and c quarks and the tau lepton have motivated the development of high precision tracking detectors capable of providing information on the decay vertex topology of events containing these particles. This paper reviews the OPAL, L3, and MARK II experiments vertex drift chambers

  6. Two-dimensional massless quantum electrodynamics in the Landau-gauge formalism and the Higgs mechanism

    International Nuclear Information System (INIS)

    Ito, K.R.

    1975-01-01

    The Schwinger model is considered in the Landau-gauge formalism of quantum electrodynamics. This model can be solved exactly on the assumption of no radiative corrections to the anomaly. It is found that the photon obtains a non-zero mass through the Higgs mechanism. In this case, the would-be Nambu-Goldstone boson is an associated boson which is constructed from a pair of two-component massless fermions. This would-be Nambu-Goldstone boson appears as a result of the spontaneous breaking of the gauge invariance of the first kind, and it becomes unphysical through the Higgs mechanism. However, as all the fermions themselves decouple from photons, they cannot appear as real particles in our world. (author)

  7. Jet Vertex Charge Reconstruction

    CERN Document Server

    Nektarijevic, Snezana; The ATLAS collaboration

    2015-01-01

    A newly developed algorithm called the jet vertex charge tagger, aimed at identifying the sign of the charge of jets containing $b$-hadrons, referred to as $b$-jets, is presented. In addition to the well established track-based jet charge determination, this algorithm introduces the so-called \\emph{jet vertex charge} reconstruction, which exploits the charge information associated to the displaced vertices within the jet. Furthermore, the charge of a soft muon contained in the jet is taken into account when available. All available information is combined into a multivariate discriminator. The algorithm has been developed on jets matched to generator level $b$-hadrons provided by $t\\bar{t}$ events simulated at $\\sqrt{s}$=13~TeV using the full ATLAS detector simulation and reconstruction.

  8. Single twistor description of massless, massive, AdS, and other interacting particles

    International Nuclear Information System (INIS)

    Bars, Itzhak; Picon, Moises

    2006-01-01

    The Penrose transform between twistors and the phase space of massless particles is generalized from the massless case to an assortment of other particle dynamical systems, including special examples of massless or massive particles, relativistic or nonrelativistic, interacting or noninteracting, in flat space or curved spaces. Our unified construction involves always the same twistor Z A with only four complex degrees of freedom and subject to the same helicity constraint. Only the twistor to phase space transform differs from one case to another. Hence, a unification of diverse particle dynamical systems is displayed by the fact that they all share the same twistor description. Our single twistor approach seems to be rather different and a strikingly economical construction of twistors compared to other past approaches that introduced multiple twistors to represent some similar but far more limited set of particle phase space systems

  9. Twisted vertex algebras, bicharacter construction and boson-fermion correspondences

    International Nuclear Information System (INIS)

    Anguelova, Iana I.

    2013-01-01

    The boson-fermion correspondences are an important phenomena on the intersection of several areas in mathematical physics: representation theory, vertex algebras and conformal field theory, integrable systems, number theory, cohomology. Two such correspondences are well known: the types A and B (and their super extensions). As a main result of this paper we present a new boson-fermion correspondence of type D-A. Further, we define a new concept of twisted vertex algebra of order N, which generalizes super vertex algebra. We develop the bicharacter construction which we use for constructing classes of examples of twisted vertex algebras, as well as for deriving formulas for the operator product expansions, analytic continuations, and normal ordered products. By using the underlying Hopf algebra structure we prove general bicharacter formulas for the vacuum expectation values for two important groups of examples. We show that the correspondences of types B, C, and D-A are isomorphisms of twisted vertex algebras

  10. The Mark III vertex chamber

    International Nuclear Information System (INIS)

    Adler, J.; Bolton, T.; Bunnell, K.

    1987-07-01

    The design and construction of the new Mark III vertex chamber is described. Initial tests with cosmic rays prove the ability of track reconstruction and yield triplet resolutions below 50 μm at 3 atm using argon/ethane (50:50). Also performed are studies using a prototype of a pressurized wire vertex chamber with 8 mm diameter straw geometry. Spatial resolution of 35mm was obtained using dimethyl ether (DME) at 1 atm and 30 μm using argon/ethane (50/50 mixture) at 4 atm. Preliminary studies indicate the DME to adversely affect such materials as aluminized Mylar and Delrin

  11. On the local vertex antimagic total coloring of some families tree

    Science.gov (United States)

    Febriani Putri, Desi; Dafik; Hesti Agustin, Ika; Alfarisi, Ridho

    2018-04-01

    Let G(V, E) be a graph of vertex set V and edge set E. Local vertex antimagic total coloring developed from local edge and local vertex antimagic coloring of graph. Local vertex antimagic total coloring is defined f:V(G)\\cup E(G)\\to \\{1,2,3,\\ldots,|V(G)|+|E(G)|\\} if for any two adjacent vertices v 1 and v 2, w({v}1)\

  12. The LHCb VERTEX LOCATOR performance and VERTEX LOCATOR upgrade

    International Nuclear Information System (INIS)

    Rodríguez Pérez, P

    2012-01-01

    LHCb is an experiment dedicated to the study of new physics in the decays of beauty and charm hadrons at the Large Hadron Collider (LHC) at CERN. The Vertex Locator (VELO) is the silicon detector surrounding the LHCb interaction point. The detector operates in a severe and highly non-uniform radiation environment. The small pitch and analogue readout result in a best single hit precision of 4 μm. The upgrade of the LHCb experiment, planned for 2018, will transform the entire readout to a trigger-less system operating at 40 MHz event rate. The vertex detector will have to cope with radiation levels up to 10 16 1 MeVn eq /cm 2 , more than an order of magnitude higher than those expected at the current experiment. A solution is under development with a pixel detector, based on the Timepix/Medipix family of chips with 55 x 55 μm pixels. In addition a micro-strip solution is also under development, with finer pitch, higher granularity and lower mass than the current detector. The current status of the VELO will be described together with recent testbeam results.

  13. No parity anomaly in massless QED{sub 3}: A BPHZL approach

    Energy Technology Data Exchange (ETDEWEB)

    Del Cima, O.M. [Universidade Federal Fluminense (UFF), Polo Universitario de Rio das Ostras (PURO), Departamento de Ciencia e Tecnologia, Rua Recife s/n, 28890-000, Rio das Ostras, RJ (Brazil)], E-mail: wadodelcima@if.uff.br; Franco, D.H.T. [Universidade Federal de Vicosa (UFV), Departamento de Fisica - Campus Universitario, Avenida Peter Henry Rolfs s/n, 36570-000, Vicosa, MG (Brazil)], E-mail: dhtfranco@gmail.com; Piguet, O. [Universidade Federal do Espirito Santo (UFES), CCE, Departamento de Fisica, Campus Universitario de Goiabeiras, 29060-900, Vitoria, ES (Brazil)], E-mail: opiguet@pq.cnpq.br; Schweda, M. [Institut fuer Theoretische Physik, Technische Universitaet Wien (TU-Wien), Wiedner Hauptstrasse 8-10, A-1040, Vienna (Austria)], E-mail: mschweda@tph.tuwien.ac.at

    2009-09-14

    In this Letter we call into question the perturbatively parity breakdown at 1-loop for the massless QED{sub 3} frequently claimed in the literature. As long as perturbative quantum field theory is concerned, whether a parity anomaly owing to radiative corrections exists or not shall be definitely proved by using a renormalization method independent of any regularization scheme. Such a problem has been investigated in the framework of BPHZL renormalization method, by adopting the Lowenstein-Zimmermann subtraction scheme. The 1-loop parity-odd contribution to the vacuum-polarization tensor is explicitly computed in the framework of the BPHZL renormalization method. It is shown that a Chern-Simons term is generated at that order induced through the infrared subtractions - which violate parity. We show then that, what is called 'parity anomaly', is in fact a parity-odd counterterm needed for restauring parity.

  14. The BaBar silicon vertex tracker

    International Nuclear Information System (INIS)

    Bozzi, C.; Carassiti, V.; Ramusino, A. Cotta; Dittongo, S.; Folegani, M.; Piemontese, L.; Abbott, B.K.; Breon, A.B.; Clark, A.R.; Dow, S.; Fan, Q.; Goozen, F.; Hernikl, C.; Karcher, A.; Kerth, L.T.; Kipnis, I.; Kluth, S.; Lynch, G.; Levi, M.; Luft, P.; Luo, L.; Nyman, M.; Pedrali-Noy, M.; Roe, N.A.; Zizka, G.; Roberts, D.; Barni, D.; Brenna, E.; Defendi, I.; Forti, A.; Giugni, D.; Lanni, F.; Palombo, F.; Vaniev, V.; Leona, A.; Mandelli, E.; Manfredi, P.F.; Perazzo, A.; Re, V.; Angelini, C.; Batignani, G.; Bettarini, S.; Bondioli, M.; Bosi, F.; Calderini, G.; Carpinelli, M.; Dutra, F.; Forti, F.; Gagliardi, D.; Giorgi, M.A.; Lusiani, A.; Mammini, P.; Morganti, M.; Morsani, F.; Paoloni, E.; Profeti, A.; Rama, M.; Rampino, G.; Rizzo, G.; Sandrelli, F.; Simi, G.; Triggiani, G.; Tritto, S.; Vitale, R.; Burchat, P.; Cheng, C.; Kirkby, D.; Meyer, T.; Roat, C.; Bona, M.; Bianchi, F.; Daudo, F.; Girolamo, B. Di; Gamba, D.; Giraudo, G.; Grosso, P.; Romero, A.; Smol, A.; Trapani, P.; Zanin, D.; Bosisio, L.; Ricca, G. Della; Lanceri, L.; Pompili, A.; Poropat, P.; Prest, M.; Rastelli, C.; Vallazza, E.; Vuagnin, G.; Hast, C.; Potter, E.P.; Sharma, V.; Burke, S.; Callahan, D.; Campagnari, C.; Dahmes, B.; Eppich, A.; Hale, D.; Hall, K.; Hart, P.; Kuznetsova, N.; Kyre, S.; Levy, S.; Long, O.; May, J.; Richman, J.; Verkerke, W.; Witherell, M.; Beringer, J.; Eisner, A.M.; Frey, A.; Grillo, A.; Grothe, M.; Johnson, R.; Kroeger, W.; Lockman, W.; Pulliam, T.; Rowe, W.; Schmitz, R.; Seiden, A.; Spencer, E.; Turri, M.; Wilder, M.; Charles, E.; Elmer, P.; Nielsen, J.; Orejudos, W.; Scott, I.; Walsh, J.; Zobernig, H.

    2000-01-01

    The BaBar Silicon Vertex Tracker (SVT) is designed to provide the high-precision vertexing necessary for making measurements of CP violation at the SLAC B-Factory PEP-II. The instrument consists of five layers of double-sided silicon strip detectors and has been installed in the BaBar experiment and taking colliding beam data since May 1999. An overview of the design as well as performance and experience from the initial running will be presented

  15. Loop expansion in massless three-dimensional QED

    International Nuclear Information System (INIS)

    Guendelman, E.I.; Radulovic, Z.M.

    1983-01-01

    It is shown how the loop expansion in massless three-dimensional QED can be made finite, up to three loops, by absorbing the infrared divergences in a gauge-fixing term. The same method removes leading and first subleading singularities to all orders of perturbation theory, and all singularities of the fermion self-energy to four loops

  16. Plethystic vertex operators and boson-fermion correspondences

    International Nuclear Information System (INIS)

    Fauser, Bertfried; Jarvis, Peter D; King, Ronald C

    2016-01-01

    We study the algebraic properties of plethystic vertex operators, introduced in (2010 J. Phys. A: Math. Theor. 43 405202), underlying the structure of symmetric functions associated with certain generalized universal character rings of subgroups of the general linear group, defined to stabilize tensors of Young symmetry type characterized by a partition of arbitrary shape π . Here we establish an extension of the well-known boson-fermion correspondence involving Schur functions and their associated (Bernstein) vertex operators: for each π , the modes generated by the plethystic vertex operators and their suitably constructed duals, satisfy the anticommutation relations of a complex Clifford algebra. The combinatorial manipulations underlying the results involve exchange identities exploiting the Hopf-algebraic structure of certain symmetric function series and their plethysms. (paper)

  17. Plethystic vertex operators and boson-fermion correspondences

    Science.gov (United States)

    Fauser, Bertfried; Jarvis, Peter D.; King, Ronald C.

    2016-10-01

    We study the algebraic properties of plethystic vertex operators, introduced in (2010 J. Phys. A: Math. Theor. 43 405202), underlying the structure of symmetric functions associated with certain generalized universal character rings of subgroups of the general linear group, defined to stabilize tensors of Young symmetry type characterized by a partition of arbitrary shape π. Here we establish an extension of the well-known boson-fermion correspondence involving Schur functions and their associated (Bernstein) vertex operators: for each π, the modes generated by the plethystic vertex operators and their suitably constructed duals, satisfy the anticommutation relations of a complex Clifford algebra. The combinatorial manipulations underlying the results involve exchange identities exploiting the Hopf-algebraic structure of certain symmetric function series and their plethysms.

  18. Translation-invariant global charges in a local scattering theory of massless particles

    International Nuclear Information System (INIS)

    Strube, D.

    1989-01-01

    The present thesis is dedicated to the study for specifically translation-invariant charges in the framework of a Wightman field theory without mass gap. The aim consists thereby in the determination of the effect of the charge operator on asymptotic scattering states of massless particles. In the first section the most important results in the massive case and of the present thesis in the massless case are presented. The object of the second section is the construction of asymptotic scattering states. In the third section the charge operator, which is first only defined on strictly local vectors, is extended to these scattering states, on which it acts additively. Finally an infinitesimal transformation of scalar asymptotic fields is determined. By this for the special case of translation-invariant generators and scalar massless asymptotic fields the same results is present as in the massive case. (orig./HSI) [de

  19. Vertex-Detector R&D for CLIC

    OpenAIRE

    Dannheim, Dominik

    2013-01-01

    A detector concept based on hybrid planar pixel-detector technology is under development for the CLIC vertex detector. It comprises fast, low-power and small-pitch readout ASICs implemented in 65 nm CMOS technology (CLICpix) coupled to ultra-thin sensors via low-mass interconnects. The power dissipation of the readout chips is reduced by means of power pulsing, allowing for a cooling system based on forced gas flow. In this paper the CLIC vertex-detector requirements are reviewed and the curr...

  20. Pion-nucleon vertex function with one nucleon off shell

    International Nuclear Information System (INIS)

    Mizutani, T.; Rochus, P.

    1979-01-01

    The pion-nucleon vertex function with an off-mass-shell nucleon is obtained through sideways dispersion relations with the P 11 and S 11 pion-nucleon phase shifts as only input. Contrary to the recent calculation of Nutt and Shakin, we find that the proper and improper vertex functions behave quite differently, indicating the importance of the nucleon propagator dressing. In particular the proper vertex function is found to have two poles in the unphysical region

  1. Perturbative quantum field theory via vertex algebras

    International Nuclear Information System (INIS)

    Hollands, Stefan; Olbermann, Heiner

    2009-01-01

    In this paper, we explain how perturbative quantum field theory can be formulated in terms of (a version of) vertex algebras. Our starting point is the Wilson-Zimmermann operator product expansion (OPE). Following ideas of a previous paper (S. Hollands, e-print arXiv:0802.2198), we consider a consistency (essentially associativity) condition satisfied by the coefficients in this expansion. We observe that the information in the OPE coefficients can be repackaged straightforwardly into 'vertex operators' and that the consistency condition then has essentially the same form as the key condition in the theory of vertex algebras. We develop a general theory of perturbations of the algebras that we encounter, similar in nature to the Hochschild cohomology describing the deformation theory of ordinary algebras. The main part of the paper is devoted to the question how one can calculate the perturbations corresponding to a given interaction Lagrangian (such as λφ 4 ) in practice, using the consistency condition and the corresponding nonlinear field equation. We derive graphical rules, which display the vertex operators (i.e., OPE coefficients) in terms of certain multiple series of hypergeometric type.

  2. Belle II silicon vertex detector

    Energy Technology Data Exchange (ETDEWEB)

    Adamczyk, K. [H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342 (Poland); Aihara, H. [Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan); Angelini, C. [Dipartimento di Fisica, Università di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Aziz, T.; Babu, V. [Tata Institute of Fundamental Research, Mumbai 400005 (India); Bacher, S. [H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342 (Poland); Bahinipati, S. [Indian Institute of Technology Bhubaneswar, Satya Nagar (India); Barberio, E.; Baroncelli, Ti.; Baroncelli, To. [School of Physics, University of Melbourne, Melbourne, Victoria 3010 (Australia); Basith, A.K. [Indian Institute of Technology Madras, Chennai 600036 (India); Batignani, G. [Dipartimento di Fisica, Università di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Bauer, A. [Institute of High Energy Physics, Austrian Academy of Sciences, 1050 Vienna (Austria); Behera, P.K. [Indian Institute of Technology Madras, Chennai 600036 (India); Bergauer, T. [Institute of High Energy Physics, Austrian Academy of Sciences, 1050 Vienna (Austria); Bettarini, S. [Dipartimento di Fisica, Università di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Bhuyan, B. [Indian Institute of Technology Guwahati, Assam 781039 (India); Bilka, T. [Faculty of Mathematics and Physics, Charles University, 121 16 Prague (Czech Republic); Bosi, F. [INFN Sezione di Pisa, I-56127 Pisa (Italy); Bosisio, L. [Dipartimento di Fisica, Università di Trieste, I-34127 Trieste (Italy); INFN Sezione di Trieste, I-34127 Trieste (Italy); and others

    2016-09-21

    The Belle II experiment at the SuperKEKB collider in Japan is designed to indirectly probe new physics using approximately 50 times the data recorded by its predecessor. An accurate determination of the decay-point position of subatomic particles such as beauty and charm hadrons as well as a precise measurement of low-momentum charged particles will play a key role in this pursuit. These will be accomplished by an inner tracking device comprising two layers of pixelated silicon detector and four layers of silicon vertex detector based on double-sided microstrip sensors. We describe herein the design, prototyping and construction efforts of the Belle-II silicon vertex detector.

  3. Operator Product Formulas in the Algebraic Approach of the Refined Topological Vertex

    International Nuclear Information System (INIS)

    Cai Li-Qiang; Wang Li-Fang; Wu Ke; Yang Jie

    2013-01-01

    The refined topological vertex of Iqbal—Kozçaz—Vafa has been investigated from the viewpoint of the quantum algebra of type W 1+∞ by Awata, Feigin, and Shiraishi. They introduced the trivalent intertwining operator Φ which is normal ordered along with some prefactors. We manage to establish formulas from the infinite operator product of the vertex operators and the generalized ones to restore this prefactor, and obtain an explicit formula for the vertex realization of the topological vertex as well as the refined topological vertex

  4. Nonplanar loops leave the Veneziano model photon massless

    NARCIS (Netherlands)

    Foda, O.

    1987-01-01

    The absence of a pole at p2=0 in the orientable nonplanar one-loop photon self-energy in the Veneziano model is verified. Thus the photon remains massless, and spontaneous symmetry breaking - at least as reported in this context in the literature - is not found.

  5. Nonplanar loops leave the Veneziano model photon massless

    International Nuclear Information System (INIS)

    Foda, O.

    1987-01-01

    The absence of a pole at p 2 =0 in the orientable nonplanar one-loop photon self-energy in the Veneziano model is verified. Thus the photon remains massless, and spontaneous symmetry breaking - at least as reported in this context in the literature - is not found. (orig.)

  6. Nonplanar loops leave the Veneziano model photon massless

    Energy Technology Data Exchange (ETDEWEB)

    Foda, O.

    1987-04-16

    The absence of a pole at p/sup 2/=0 in the orientable nonplanar one-loop photon self-energy in the Veneziano model is verified. Thus the photon remains massless, and spontaneous symmetry breaking - at least as reported in this context in the literature - is not found.

  7. Extended higher-spin superalgebras and their massless representations

    Energy Technology Data Exchange (ETDEWEB)

    Konstein, S E; Vasiliev, M A [AN SSSR, Moscow (USSR). Fizicheskij Inst.

    1990-02-12

    Three two-parameter sequences of infinite-dimensional extended higher-spin superalgebras are constructed, which give rise to consistent equations of motion of interacting gauge fields of all spins in four dimensions. In the Yang-Mills sector of spin-1 gauge fields, these higher-spin superalgebras reduce to u(n) + u(m), o(n) + o(m) and usp(n) + usp(m) with arbitrary integer parameters n {ge} 0 and m {ge} 0 (n and m are assumed to be even for symplectic algebras). Massless unitary representations of the proposed higher-spin superalgebras are analyzed. It is shown that all these superalgebras obey the admissibility condition which requires them to possess massless unitary representations with just the same spectra of spins as follows from the structure of the related higher-spin gauge fields. We argue that the infinite-dimensional (super)algebras listed in this article classify all possible higher-spin rigid (super)symmetries in four dimensions. (orig.).

  8. Vertex epidural haematoma manifesting with bilateral upper limb ...

    African Journals Online (AJOL)

    Vertex epidural haematomas (VEDH) are rare and difficulties are encountered in diagnosis and management. This is a case report of a patient with a vertex epidural haematoma who presented with signs of severe head injury with upper limb decerebrate posture. We discuss the challenges of radiological investigation and ...

  9. Vertex Reconstruction for AEGIS’ FACT Detector

    CERN Document Server

    Themistokleous, Neofytos

    2017-01-01

    My project dealt with the development of a vertex reconstruction technique to discriminate antihydrogen from background signals in the AEGIS apparatus. It involved the creation of a Toy Monte-Carlo to simulate particle annihilation events, and a vertex reconstruction utility based on the Bayesian theory of probability. The first results based on 107 generated events with single track in the detector are encouraging. For such events, the algorithm can reconstruct the z-coordinate accurately , while for the r-coordinate the result is less accurate.

  10. Quark-gluon vertex dressing and meson masses beyond ladder-rainbow truncation

    International Nuclear Information System (INIS)

    Matevosyan, Hrayr H.; Thomas, Anthony W.; Tandy, Peter C.

    2007-01-01

    We include a generalized infinite class of quark-gluon vertex dressing diagrams in a study of how dynamics beyond the ladder-rainbow truncation influences the Bethe-Salpeter description of light-quark pseudoscalar and vector mesons. The diagrammatic specification of the vertex is mapped into a corresponding specification of the Bethe-Salpeter kernel, which preserves chiral symmetry. This study adopts the algebraic format afforded by the simple interaction kernel used in previous work on this topic. The new feature of the present work is that in every diagram summed for the vertex and the corresponding Bethe-Salpeter kernel, each quark-gluon vertex is required to be the self-consistent vertex solution. We also adopt from previous work the effective accounting for the role of the explicitly non-Abelian three-gluon coupling in a global manner through one parameter determined from recent lattice-QCD data for the vertex. Within the current model, the more consistent dressed vertex limits the ladder-rainbow truncation error for vector mesons to be never more than 10% as the current quark mass is varied from the u/d region to the b region

  11. Internal space-time symmetries of massive and massless particles and their unification

    International Nuclear Information System (INIS)

    Kim, Y.S.

    2001-01-01

    It is noted that the internal space-time symmetries of relativistic particles are dictated by Wigner's little groups. The symmetry of massive particles is like the three-dimensional rotation group, while the symmetry of massless particles is locally isomorphic to the two-dimensional Euclidean group. It is noted also that, while the rotational degree of freedom for a massless particle leads to its helicity, the two translational degrees of freedom correspond to its gauge degrees of freedom. It is shown that the E(2)-like symmetry of of massless particles can be obtained as an infinite-momentum and/or zero-mass limit of the O(3)-like symmetry of massive particles. This mechanism is illustrated in terms of a sphere elongating into a cylinder. In this way, the helicity degree of freedom remains invariant under the Lorentz boost, but the transverse rotational degrees of freedom become contracted into the gauge degree of freedom

  12. Propagation of the trip behavior in the VENUS vertex chamber

    International Nuclear Information System (INIS)

    Ohama, Taro; Yamada, Yoshikazu.

    1995-03-01

    The high voltage system of the VENUS vertex chamber occasionally trips by a discharge somewhere among cathode electrodes during data taking. This trip behavior induces often additional trips at other electrodes such as the skin and the grid electrodes in the vertex chamber. This propagation mechanism of trips is so complicated in this system related with multi-electrodes. Although the vertex chamber is already installed inside the VENUS detector and consequently the discharge is not able to observe directly, a trial to estimate the propagation has been done using only the information which appears around the trip circuits and the power supply of the vertex chamber. (author)

  13. Mechanical design of the CDF SVX II silicon vertex detector

    International Nuclear Information System (INIS)

    Skarha, J.E.

    1994-08-01

    A next generation silicon vertex detector is planned at CDF for the 1998 Tevatron collider run with the Main Injector. The SVX II silicon vertex detector will allow high luminosity data-taking, enable online triggering of secondary vertex production, and greatly increase the acceptance for heavy flavor physics at CDF. The design specifications, geometric layout, and early mechanical prototyping work for this detector are discussed

  14. A covariant representation of the Ball–Chiu vertex

    International Nuclear Information System (INIS)

    Ahmadiniaz, Naser; Schubert, Christian

    2013-01-01

    In nonabelian gauge theory the three-gluon vertex function contains important structural information, in particular on infrared divergences, and is also an essential ingredient in the Schwinger–Dyson equations. Much effort has gone into analyzing its general structure, and at the one-loop level also a number of explicit computations have been done, using various approaches. Here we use the string-inspired formalism to unify the calculations of the scalar, spinor and gluon loop contributions to the one-loop vertex, leading to an extremely compact representation in all cases. The vertex is computed fully off-shell and in dimensionally continued form, so that it can be used as a building block for higher-loop calculations. We find that the Bern–Kosower loop replacement rules, originally derived for the on-shell case, hold off-shell as well. We explain the relation of the structure of this representation to the low-energy effective action, and establish the precise connection with the standard Ball–Chiu decomposition of the vertex. This allows us also to predict that the vanishing of the completely antisymmetric coefficient function S of this decomposition is not a one-loop accident, but persists at higher-loop orders. The sum rule found by Binger and Brodsky, which leads to the vanishing of the one-loop vertex in N=4 SYM theory, in the present approach relates to worldline supersymmetry

  15. A covariant representation of the Ball–Chiu vertex

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadiniaz, Naser, E-mail: naser@ifm.umich.mx [Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio C-3, Apdo. Postal 2-82, C.P. 58040, Morelia, Michoacán (Mexico); Dipartimento di Fisica, Università di Bologna and INFN, Sezione di Bologna, Via Irnerio 46, I-40126 Bologna (Italy); Schubert, Christian, E-mail: schubert@ifm.umich.mx [Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio C-3, Apdo. Postal 2-82, C.P. 58040, Morelia, Michoacán (Mexico); Dipartimento di Fisica, Università di Bologna and INFN, Sezione di Bologna, Via Irnerio 46, I-40126 Bologna (Italy); Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, Mühlenberg 1, D-14476 Potsdam (Germany)

    2013-04-21

    In nonabelian gauge theory the three-gluon vertex function contains important structural information, in particular on infrared divergences, and is also an essential ingredient in the Schwinger–Dyson equations. Much effort has gone into analyzing its general structure, and at the one-loop level also a number of explicit computations have been done, using various approaches. Here we use the string-inspired formalism to unify the calculations of the scalar, spinor and gluon loop contributions to the one-loop vertex, leading to an extremely compact representation in all cases. The vertex is computed fully off-shell and in dimensionally continued form, so that it can be used as a building block for higher-loop calculations. We find that the Bern–Kosower loop replacement rules, originally derived for the on-shell case, hold off-shell as well. We explain the relation of the structure of this representation to the low-energy effective action, and establish the precise connection with the standard Ball–Chiu decomposition of the vertex. This allows us also to predict that the vanishing of the completely antisymmetric coefficient function S of this decomposition is not a one-loop accident, but persists at higher-loop orders. The sum rule found by Binger and Brodsky, which leads to the vanishing of the one-loop vertex in N=4 SYM theory, in the present approach relates to worldline supersymmetry.

  16. QCD calculation of π0γγ vertex at equal Euclidean q2 of both photons

    International Nuclear Information System (INIS)

    Voloshin, M.B.

    1982-01-01

    The form factor of the π 6 γγ vertex at equal space-like four- momentum q 2 of the photons (q 1 2 =q 2 2 =-Q 2 ) and a small four- momentum p 2 of the pion is calculated within QCD. Explicit expressions for leading perturbative and non perturbative preasymptotic corrections are derived. To find the latter correction matrix elements of operators of dimension d=5 between the pion and vacuum are calculated. The result for the form factor smoothly matches at Q 2 approximately 0.5 GeV 2 the estimate based on the vector mesom dominance model [ru

  17. Connecting dark matter annihilation to the vertex functions of Standard Model fermions

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Jason; Light, Christopher, E-mail: jkumar@hawaii.edu, E-mail: lightc@hawaii.edu [Department of Physics and Astronomy, University of Hawaii, Honolulu, HI 96822, Hawaii (United States)

    2017-07-01

    We consider scenarios in which dark matter is a Majorana fermion which couples to Standard Model fermions through the exchange of charged mediating particles. The matrix elements for various dark matter annihilation processes are then related to one-loop corrections to the fermion-photon vertex, where dark matter and the charged mediators run in the loop. In particular, in the limit where Standard Model fermion helicity mixing is suppressed, the cross section for dark matter annihilation to various final states is related to corrections to the Standard Model fermion charge form factor. These corrections can be extracted in a gauge-invariant manner from collider cross sections. Although current measurements from colliders are not precise enough to provide useful constraints on dark matter annihilation, improved measurements at future experiments, such as the International Linear Collider, could improve these constraints by several orders of magnitude, allowing them to surpass the limits obtainable by direct observation.

  18. Performance of the LHCb Vertex Locator

    CERN Document Server

    Bjørnstad, Pal Marius

    2011-01-01

    The Vertex Locator is a silicon microstrip detector which provides the LHCb experiment with high precision measurements of tracks and decay vertices. The VELO sensors are exposed to a radiation dose of (2.5-6.5) x 10$^{13}n_{eq}$/cm$^2$ per fb$^{-1}$ in the area which is most irradiated. A best hit resolution of 4$mu$ is obtained for angled tracks, in agreement with expectations. The VELO has a vertex position resolution down to 11$mu$m in the transverse direction and an excellent momentum dependent performance.

  19. Improving vertex position determination by using a kinematic fit

    International Nuclear Information System (INIS)

    Forden, G.E.; Saxon, D.H.

    1985-05-01

    A method is developed for improving decay vertex reconstruction by using kinematic fits. This is applied to generated charm meson decays. An improvement of 16% in the vertex position measurement along the flight path is achieved. (author)

  20. Subgraphs in vertex neighborhoods of K-free graphs

    DEFF Research Database (Denmark)

    Bang-Jensen, J.; Brandt, Stephan

    2004-01-01

    In a K-free graph, the neighborhood of every vertex induces a K-free subgraph. The K-free graphs with the converse property that every induced K-free subgraph is contained in the neighborhood of a vertex are characterized, based on the characterization in the case r = 3 due to Pach [8]....

  1. Super-acceleration from massless, minimally coupled phi sup 4

    CERN Document Server

    Onemli, V K

    2002-01-01

    We derive a simple form for the propagator of a massless, minimally coupled scalar in a locally de Sitter geometry of arbitrary spacetime dimension. We then employ it to compute the fully renormalized stress tensor at one- and two-loop orders for a massless, minimally coupled phi sup 4 theory which is released in Bunch-Davies vacuum at t=0 in co-moving coordinates. In this system, the uncertainty principle elevates the scalar above the minimum of its potential, resulting in a phase of super-acceleration. With the non-derivative self-interaction the scalar's breaking of de Sitter invariance becomes observable. It is also worth noting that the weak-energy condition is violated on cosmological scales. An interesting subsidiary result is that cancelling overlapping divergences in the stress tensor requires a conformal counterterm which has no effect on purely scalar diagrams.

  2. The gravitational shock wave of a massless particle

    NARCIS (Netherlands)

    Hooft, G. 't; Dray, T

    1985-01-01

    The (spherical) gravitational shock wave due to a massless particle moving at the speed of light along the horizon of the Schwarzchild black hole is obtained. Special cases of our procedure yield previous results by Aichelburg and Sexl[1] for a photon in Minkowski vpace and by Penrose [2] for

  3. Dynamical electron-phonon coupling, G W self-consistency, and vertex effect on the electronic band gap of ice and liquid water

    Science.gov (United States)

    Ziaei, Vafa; Bredow, Thomas

    2017-06-01

    We study the impact of dynamical electron-phonon (el-ph) effects on the electronic band gap of ice and liquid water by accounting for frequency-dependent Fan contributions in the el-ph mediated self-energy within the many-body perturbation theory (MBPT). We find that the dynamical el-ph coupling effects greatly reduce the static el-ph band-gap correction of the hydrogen-rich molecular ice crystal from-2.46 to -0.23 eV in great contrast to the result of Monserrat et al. [Phys. Rev. B 92, 140302 (2015), 10.1103/PhysRevB.92.140302]. This is of particular importance as otherwise the static el-ph gap correction would considerably reduce the electronic band gap, leading to considerable underestimation of the intense peaks of optical absorption spectra of ice which would be in great disagreement to experimental references. By contrast, the static el-ph gap correction of liquid water is very moderate (-0.32 eV), and inclusion of dynamical effects slightly reduces the gap correction to -0.19 eV. Further, we determine the diverse sensitivity of ice and liquid water to the G W self-consistency and show that the energy-only self-consistent approach (GnWn ) exhibits large implicit vertex character in comparison to the quasiparticle self-consistent approach, for which an explicit calculation of vertex corrections is necessary for good agreement with experiment.

  4. A new method for computing the quark-gluon vertex

    International Nuclear Information System (INIS)

    Aguilar, A C

    2015-01-01

    In this talk we present a new method for determining the nonperturbative quark-gluon vertex, which constitutes a crucial ingredient for a variety of theoretical and phenomenological studies. This new method relies heavily on the exact all-order relation connecting the conventional quark-gluon vertex with the corresponding vertex of the background field method, which is Abelian-like. The longitudinal part of this latter quantity is fixed using the standard gauge technique, whereas the transverse is estimated with the help of the so-called transverse Ward identities. This method allows the approximate determination of the nonperturbative behavior of all twelve form factors comprising the quark-gluon vertex, for arbitrary values of the momenta. Numerical results are presented for the form factors in three special kinematical configurations (soft gluon and quark symmetric limit, zero quark momentum), and compared with the corresponding lattice data. (paper)

  5. A note on arbitrarily vertex decomposable graphs

    Directory of Open Access Journals (Sweden)

    Antoni Marczyk

    2006-01-01

    Full Text Available A graph \\(G\\ of order \\(n\\ is said to be arbitrarily vertex decomposable if for each sequence \\((n_{1},\\ldots,n_k\\ of positive integers such that \\(n_{1}+\\ldots+n_{k}=n\\ there exists a partition \\((V_{1},\\ldots,V_{k}\\ of the vertex set of \\(G\\ such that for each \\(i \\in \\{1,\\ldots,k\\}\\, \\(V_{i}\\ induces a connected subgraph of \\(G\\ on \\(n_i\\ vertices. In this paper we show that if \\(G\\ is a two-connected graph on \\(n\\ vertices with the independence number at most \\(\\lceil n/2\\rceil\\ and such that the degree sum of any pair of non-adjacent vertices is at least \\(n-3\\, then \\(G\\ is arbitrarily vertex decomposable. We present another result for connected graphs satisfying a similar condition, where the bound \\(n-3\\ is replaced by \\(n-2\\.

  6. Performance-Optimization Studies for the CLIC Vertex Detector

    CERN Document Server

    AUTHOR|(CDS)2085406; Roloff, Philipp

    The Compact Linear Collider (CLIC) is a mutli-TeV linear e+e- collider currently under development at CERN. In the post-LHC era, CLIC will allow to explore a great number of searches for New Physics such as the precise measurements of the Higgs boson. In this master thesis, we mainly focus on the development and the improvement of the vertex detector. The vertex detector requires excellent spatial resolution, low mass, geometrical coverage down to low polar angles, high rate readout for the sensors and new cooling technologies for heat removal. Considering such requirements, the CLIC vertex detector technology is far more advanced in comparison to the technologies currently used in particle physics. This project consists of two main parts. In the first part, we study the vertex detector and optimize its geometry for the use of airflow cooling techniques and also for flavor tagging. In the second part, we implement a decoder which can respect the timing constraints for the CLICpix chip, a silicon pixel detect...

  7. Measurement of Rb Using a Vertex Mass Tag

    International Nuclear Information System (INIS)

    Steiner, R.; Benvenuti, A.C.; Coller, J.A.; Hedges, S.J.; Johnson, A.S.; Shank, J.T.; Whitaker, J.S.; Allen, N.J.; Cotton, R.; Dervan, P.J.; Hasan, A.; McKemey, A.K.; Watts, S.J.; Caldwell, D.O.; Lu, A.; Yellin, S.J.; Cavalli-Sforza, M.; Coyne, D.G.; Fernandez, J.P.; Liu, X.; Reinertsen, P.L.; Schalk, T.; Schumm, B.A.; DOliveira, A.; Johnson, R.A.; Meadows, B.T.; Nussbaum, M.; Dima, M.; Harton, J.L.; Smy, M.B.; Staengle, H.; Wilson, R.J.; Baranko, G.; Fahey, S.; Fan, C.; Krishna, N.M.; Lauber, J.A.; Nauenberg, U.; Wagner, D.L.; Bazarko, A.O.; Bolton, T.; Rowson, P.C.; Shaevitz, M.H.; Camanzi, B.; Mazzucato, E.; Piemontese, L.; Calcaterra, A.; De Sangro, R.; Peruzzi, I.; Piccolo, M.; Eisenstein, B.I.; Gladding, G.; Karliner, I.; Shapiro, G.; Steiner, H.; Bardon, O.; Burrows, P.N.; Busza, W.; Cowan, R.F.; Dong, D.N.; Fero, M.J.; Gonzalez, S.; Kendall, H.W.; Lath, A.; Lia, V.; Osborne, L.S.; Quigley, J.; Taylor, F.E.; Torrence, E.; Verdier, R.; Williams, D.C.

    1998-01-01

    We report a new measurement of R b =Γ Z 0 →bbar b /Γ Z 0 →hadrons using a double tag technique, where the b hemisphere selection is based on the reconstructed mass of the B hadron decay vertex. The measurement was performed using a sample of 130x10 3 hadronic Z 0 events, collected with the SLD detector at SLC. The method utilizes the 3D vertexing abilities of the CCD pixel vertex detector and the small stable SLC beams to obtain a high b -tagging efficiency and purity. We obtain R b =0.2142±0.0034(stat) ±0.0015(syst)±0.0002( R c ) . copyright 1998 The American Physical Society

  8. The NA50 segmented target and vertex recognition system

    International Nuclear Information System (INIS)

    Bellaiche, F.; Cheynis, B.; Contardo, D.; Drapier, O.; Grossiord, J.Y.; Guichard, A.; Haroutunian, R.; Jacquin, M.; Ohlsson-Malek, F.; Pizzi, J.R.

    1997-01-01

    The NA50 segmented target and vertex recognition system is described. The segmented target consists of 7 sub-targets of 1-2 mm thickness. The vertex recognition system used to determine the sub-target where an interaction has occured is based upon quartz elements which produce Cerenkov light when traversed by charged particles from the interaction. The geometrical arrangement of the quartz elements has been optimized for vertex recognition in 208 Pb-Pb collisions at 158 GeV/nucleon. A simple algorithm provides a vertex recognition efficiency of better than 85% for dimuon trigger events collected with a 1 mm sub-target set-up. A method for recognizing interactions of projectile fragments (nuclei and/or groups of nucleons) is presented. The segmented target allows a large target thickness which together with a high beam intensity (∼10 7 ions/s) enables high statistics measurements. (orig.)

  9. Two-dimensional massless quantum electrodynamics in the Landau-gauge formalism and the Higgs mechanism. [Schwinger model

    Energy Technology Data Exchange (ETDEWEB)

    Ito, K R [Kyoto Univ. (Japan). Research Inst. for Mathematical Sciences

    1975-03-01

    The Schwinger model is considered in the Landau-gauge formalism of quantum electrodynamics. This model can be solved exactly on the assumption of no radiative corrections to the anomaly. It is found that the photon obtains a non-zero mass through the Higgs mechanism. In this case, the would-be Nambu-Goldstone boson is an associated boson which is constructed from a pair of two-component massless fermions. This would-be Nambu-Goldstone boson appears as a result of the spontaneous breaking of the gauge invariance of the first kind, and it becomes unphysical through the Higgs mechanism. However, as all the fermions themselves decouple from photons, they cannot appear as real particles in our world.

  10. Quantum vertex model for reversible classical computing.

    Science.gov (United States)

    Chamon, C; Mucciolo, E R; Ruckenstein, A E; Yang, Z-C

    2017-05-12

    Mappings of classical computation onto statistical mechanics models have led to remarkable successes in addressing some complex computational problems. However, such mappings display thermodynamic phase transitions that may prevent reaching solution even for easy problems known to be solvable in polynomial time. Here we map universal reversible classical computations onto a planar vertex model that exhibits no bulk classical thermodynamic phase transition, independent of the computational circuit. Within our approach the solution of the computation is encoded in the ground state of the vertex model and its complexity is reflected in the dynamics of the relaxation of the system to its ground state. We use thermal annealing with and without 'learning' to explore typical computational problems. We also construct a mapping of the vertex model into the Chimera architecture of the D-Wave machine, initiating an approach to reversible classical computation based on state-of-the-art implementations of quantum annealing.

  11. Multipole expansion of vertex functions with two final particles

    International Nuclear Information System (INIS)

    Daumens, Michel

    1977-01-01

    The expansions of the usual vertex functions are generalized to the vertex functions with two final particles. For four vector functions, expressions are similar to those of Chew, Goldberger, Low and Nambu, and of Adler and the consequences of the isobaric model are studied [fr

  12. Fermionic construction of vertex operators for twisted affine algebras

    International Nuclear Information System (INIS)

    Frappat, L.; Sorba, P.; Sciarrino, A.

    1988-03-01

    We construct vertex operator representations of the twisted affine algebras in terms of fermionic (or parafermionic in some cases) elementary fields. The folding method applied to the extended Dynkin diagrams of the affine algebras allows us to determine explicitly these fermionic fields as vertex operators

  13. Tracking and vertexing for B physics at hadron accelerators

    International Nuclear Information System (INIS)

    Johnson, R.; Purohit, M.; Weidemann, A.W.

    1993-01-01

    In this note, the authors report on some of the activities of the Tracking and Vertexing Working Group of this Workshop. Track and vertex finding is essential to exploit the high production rate of B-mesons at hadron accelerators, both for triggering and analysis. Here, they review the tracking and vertex-finding systems of some of the major existing and proposed collider and fixed-target experiments at existing and future hadron accelerators, with a view towards their usefulness for B-physics. The capabilities of both general-purpose detectors and those of dedicated B-physics experiments are considered

  14. Statistical description of massless excitations within a sphere with a linear equation of state and the dark energy case

    Science.gov (United States)

    Viaggiu, S.

    2018-04-01

    In this paper, we continue the investigations present in Refs. 1-3. In particular, we extend the theorem proved in Ref. 3 to any massless excitation in a given spherical box. As a first interesting result, we show that it is possible, contrary to the black hole case studied in detail in Refs. 1-3, to build macroscopic configurations with a dark energy equation of state. To this purpose, by requiring a stable configuration, a macroscopic dark fluid is obtained with an internal energy U scaling as the volume V, but with a fundamental correction looking like ˜ 1/R motivated by quantum fluctuations. Thanks to the proposition in Sec. 3 (and in Ref. 3 for gravitons), one can depict the dark energy in terms of massless excitations with a discrete spectrum. This fact opens the possibility to test a possible physical mechanism converting usual radiation into dark energy in a macroscopic configuration, also in a cosmological context. In fact, for example, in a Friedmann flat universe with a cosmological constant, particles are marginally trapped at the Hubble horizon for any given comoving observer.

  15. Gravitational interaction of massless higher-spin fields

    Energy Technology Data Exchange (ETDEWEB)

    Fradkin, E S; Vasiliev, M A

    1987-04-30

    We show that, despite a widespread belief, the gravitational interaction of massless higher-spin fields (s>2) does exist at least in the first nontrivial order. The principal novel feature of the gravitational higher-spin interaction is its non-analyticity in the cosmological constant. Our construction is based on an infinite-dimensional higher-spin superalgebra proposed previously that leads to an infinite system of all spins s>1.

  16. The quintic interaction vertex in light-cone gravity

    International Nuclear Information System (INIS)

    Ananth, Sudarshan

    2008-01-01

    We consider pure gravity in light-cone gauge and derive the complete quintic interaction vertex. Up to quartic order, the Kawai-Lewellen-Tye (KLT) relations can be made manifest at the level of the Einstein-Hilbert Lagrangian. The quintic interaction vertex represents an essential first step in further extending the off-shell validity of the KLT relations to higher order vertices

  17. Track and vertex reconstruction in the ATLAS experiment

    International Nuclear Information System (INIS)

    Lacuesta, V

    2013-01-01

    The track and vertex reconstruction algorithms of the ATLAS Inner Detector have demonstrated excellent performance in the early data from the LHC. However, the rapidly increasing number of interactions per bunch crossing introduces new challenges both in computational aspects and physics performance. The combination of both silicon and gas based detectors provides high precision impact parameter and momentum measurement of charged particles, with high efficiency and small fake rate. Vertex reconstruction is used to identify with high efficiency the hard scattering process and to measure the amount of pile-up interactions, both aspects are crucial for many physics analyses. The performance of track and vertex reconstruction efficiency and resolution achieved in the 2011 and 2012 data-taking period are presented.

  18. Track and Vertex Reconstruction in the ATLAS Experiment

    CERN Document Server

    Lacuesta, V; The ATLAS collaboration

    2012-01-01

    The track and vertex reconstruction algorithms of the ATLAS Inner Detector have demonstrated excellent performance in the early data from the LHC. However, the rapidly increas- ing number of interactions per bunch crossing introduces new challenges both in computational aspects and physics performance. The combination of both silicon and gas based detectors provides high precision impact parameter and momentum measurement of charged particles, with high efficiency and small fake rate. Vertex reconstruction is used to identify with high efficiency the hard scattering process and to measure the amount of pile-up interactions, both aspects are cru- cial for many physics analyses. The performance of track and vertex reconstruction efficiency and resolution achieved in the 2011 and 2012 data-taking period are presented.

  19. Track and Vertex Reconstruction in the ATLAS Experiment

    CERN Document Server

    Lacuesta, V; The ATLAS collaboration

    2012-01-01

    The track and vertex reconstruction algorithms of the ATLAS Inner Detector have demonstrated excellent performance in the early data from the LHC. However, the rapidly increas- ing number of interactions per bunch crossing introduces new challenges both in computational aspects and physics performance. The combination of both silicon and gas based detectors pro- vides high precision impact parameter and momentum measurement of charged particles, with high efficiency and small fake rate. Vertex reconstruction is used to identify with high efficiency the hard scattering process and to measure the amount of pile-up interactions, both aspects are cru- cial for many physics analyses. The performance of track and vertex reconstruction efficiency and resolution achieved in the 2011 and 2012 data-taking period are presented.

  20. Behaviour of Charged Spinning Massless Particles

    Directory of Open Access Journals (Sweden)

    Ivan Morales

    2017-12-01

    Full Text Available We revisit the classical theory of a relativistic massless charged point particle with spin and interacting with an external electromagnetic field. In particular, we give a proper definition of its kinetic energy and its total energy, the latter being conserved when the external field is stationary. We also write the conservation laws for the linear and angular momenta. Finally, we find that the particle’s velocity may differ from c as a result of the spin—electromagnetic field interaction, without jeopardizing Lorentz invariance.

  1. Vertex Reconstruction in the ATLAS Experiment at the LHC

    CERN Document Server

    Bouhova-Thacker, E; The ATLAS collaboration; Kostyukhin, V; Liebig, W; Limper, M; Piacquadio, G; Lichard, P; Weiser, C; Wildauer, A

    2009-01-01

    In the harsh environment of the Large Hadron Collider at CERN (design luminosity of $10^{34}$ cm$^{-2}$ s$^{-1}$) efficient reconstruction of vertices is crucial for many physics analyses. Described in this paper are the strategies for vertex reconstruction used in the ATLAS experiment and their implementation in the software framework Athena. The algorithms for the reconstruction of primary and secondary vertices as well as for finding of photon conversions and vertex reconstruction in jets are described. A special emphasis is made on the vertex fitting with application of additional constraints. The implementation of mentioned algorithms follows a very modular design based on object-oriented C++ and use of abstract interfaces. The user-friendly concept allows event reconstruction and physics analyses to compare and optimize their choice among different vertex reconstruction strategies. The performance of implemented algorithms has been studied on a variety of Monte Carlo samples and results are presented.

  2. CCD-based vertex detectors

    CERN Document Server

    Damerell, C J S

    2005-01-01

    Over the past 20 years, CCD-based vertex detectors have been used to construct some of the most precise 'tracking microscopes' in particle physics. They were initially used by the ACCMOR collaboration for fixed target experiments in CERN, where they enabled the lifetimes of some of the shortest-lived charm particles to be measured precisely. The migration to collider experiments was accomplished in the SLD experiment, where the original 120 Mpixel detector was later upgraded to one with 307 Mpixels. This detector was used in a range of physics studies which exceeded the capability of the LEP detectors, including the most precise limit to date on the Bs mixing parameter. This success, and the high background hit densities that will inevitably be encountered at the future TeV-scale linear collider, have established the need for a silicon pixel-based vertex detector at this machine. The technical options have now been broadened to include a wide range of possible silicon imaging technologies as well as CCDs (mon...

  3. Quantum Scalar Corrections to the Gravitational Potentials on de Sitter Background

    NARCIS (Netherlands)

    Park, Sohyun; Prokopec, Tomislav; Woodard, R. P.

    We employ the graviton self-energy induced by a massless, minimally coupled (MMC) scalar on de Sitter background to compute the quantum corrections to the gravitational potentials of a static point particle with a mass $M$. The Schwinger-Keldysh formalism is used to derive real and causal effective

  4. Vertex function of an electron in a constant electromagnetic field

    International Nuclear Information System (INIS)

    Morozov, D.A.; Narozhnyj, N.B.; Ritus, V.I.

    1981-01-01

    The third order with respect to radiation field vertex function for an electron located in a constant crossed field of arbitrary intensity is determined. It is shown that radiative interaction smears out the Airy function which describes the intensity of the interaction between electrons and photons in an external field as a function of the nonconserving momentum component. The qualitative relation Vsup((3)) approximately αchisup(2/3)Vsup((1)) between the third and first order vertex functions is found for large values of the dynamic parameter chi=((eFp)sup(2))sup(1/2)msup(-2). It is also shown that radiative interaction does not alter the order of magnitude of the squared mass of the system transferred at the vertex. The vertex function satisfies the Ward identity modified by the external field [ru

  5. The high energy behavior of QCD. The effective action and the triple-Pomeron-vertex

    Energy Technology Data Exchange (ETDEWEB)

    Hentschinski, Martin

    2009-07-15

    We study integrations over light-cone momenta in the high energy effective action of QCD. After a brief review of the effective action, we arrive on a regularization mechanism from matching of effective action diagrams with QCD diagrams, which we apply to a re-derivation of the reggeized gluon and of the BFKL-equation. We study consequences of the proposed regularization on the analytic structure of 2{yields}3 and 2{yields}4 production amplitudes in the Multi-Regge-Kinematics. We derive a certain part of the 1-loop corrections to the production vertex and demonstrate that they yield the on-set of corrections demanded by the Steinmann-relations. The Reggeon-Particle-2-Reggeon vertex is determined and applied to the construction of various signature configurations of the production amplitudes. We extend the proposed regularization method to states of three and four reggeized gluons and propose a supplement to the effective Lagrangian. We derive vertices for the 1-3 and 2-4 reggeized-gluon-transition inside the elastic amplitude and verify that signature conservation is obeyed. Integral equations for the state of three and four reggeized gluons are formulated and shown to be in accordance with a result by Bartels and Wuesthoff. In a second part we investigate the high-energy behavior of QCD for different surface topologies of color graphs. After a brief review of the planar limit (bootstrap and gluon reggeization) and of the cylinder topology (BFKL) we investigate the 3{yields}3 scattering in the triple Regge limit which belongs to the pair-of-pants topology. We re-derive the triple Pomeron vertex function and show that it belongs to a specific set of graphs in color space which we identify as the analog of the Mandelstam diagram. We then extend the study to the high-energy behavior of N=4 SYM where we find a new class of color graphs not present in QCD. (orig.)

  6. The high energy behavior of QCD. The effective action and the triple-Pomeron-vertex

    International Nuclear Information System (INIS)

    Hentschinski, Martin

    2009-07-01

    We study integrations over light-cone momenta in the high energy effective action of QCD. After a brief review of the effective action, we arrive on a regularization mechanism from matching of effective action diagrams with QCD diagrams, which we apply to a re-derivation of the reggeized gluon and of the BFKL-equation. We study consequences of the proposed regularization on the analytic structure of 2→3 and 2→4 production amplitudes in the Multi-Regge-Kinematics. We derive a certain part of the 1-loop corrections to the production vertex and demonstrate that they yield the on-set of corrections demanded by the Steinmann-relations. The Reggeon-Particle-2-Reggeon vertex is determined and applied to the construction of various signature configurations of the production amplitudes. We extend the proposed regularization method to states of three and four reggeized gluons and propose a supplement to the effective Lagrangian. We derive vertices for the 1-3 and 2-4 reggeized-gluon-transition inside the elastic amplitude and verify that signature conservation is obeyed. Integral equations for the state of three and four reggeized gluons are formulated and shown to be in accordance with a result by Bartels and Wuesthoff. In a second part we investigate the high-energy behavior of QCD for different surface topologies of color graphs. After a brief review of the planar limit (bootstrap and gluon reggeization) and of the cylinder topology (BFKL) we investigate the 3→3 scattering in the triple Regge limit which belongs to the pair-of-pants topology. We re-derive the triple Pomeron vertex function and show that it belongs to a specific set of graphs in color space which we identify as the analog of the Mandelstam diagram. We then extend the study to the high-energy behavior of N=4 SYM where we find a new class of color graphs not present in QCD. (orig.)

  7. How to translate a massless particle (the Weyl neutrino)

    International Nuclear Information System (INIS)

    Berger, S.B.

    1979-01-01

    Previous work indicated a deep connection between translations and rotations for a Weyl neutrino (a massless particle). In the letter the explicit form of a translation in the z-direction is given assuming a translation operator of the form esup(i anti g.anti x). (author)

  8. The massless supersymmetric ladder with L rungs

    International Nuclear Information System (INIS)

    Rossi, G.C.; Stanev, Ya.S.

    2009-01-01

    We show that in the massless N=1 supersymmetric Wess-Zumino theory it is possible to devise a computational strategy by which the x-space calculation of the ladder 4-point correlators can be carried out without introducing any regularization. As an application we derive a representation valid at all loop orders in terms of conformal invariant integrals. We obtain an explicit expression of the 3-loop ladder diagram for collinear external points

  9. Graphs with No Induced Five-Vertex Path or Antipath

    DEFF Research Database (Denmark)

    Chudnovsky, Maria; Esperet, Louis; Lemoine, Laetitia

    2017-01-01

    We prove that a graph G contains no induced five-vertex path and no induced complement of a five-vertex path if and only if G is obtained from 5-cycles and split graphs by repeatedly applying the following operations: substitution, split unification, and split unification in the complement, where...

  10. Primary vertex reconstruction at the ATLAS experiment

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00301388; The ATLAS collaboration; Casper, D.; Hooberman, B.; Gui, B.; Lee, G.; Maurer, J.; Morley, A.; Pagan Griso, S.; Petersen, B.; Prokofiev, K.; Shan, L.; Shope, D.; Wharton, A.; Whitmore, B.; Zhang, M.

    2017-01-01

    These proceedings present the method and performance of primary vertex reconstruction at the ATLAS experiment during Runs 1 and 2 at the LHC. The studies presented focus on data taken during 2012 at a centre-of-mass energy of $\\sqrt{s} = 8$ TeV, and during 2015-2016 at $\\sqrt{s} = 13$ TeV. Some predictions toward future runs are also presented. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed.

  11. BRST invariant mixed string vertex for the bosonic string

    International Nuclear Information System (INIS)

    Clarizia, A.; Pezzella, F.

    1987-09-01

    We construct a BRST invariant (N+M)-string vertex including both open and closed string states. When we saturate it with N open string and M closed string physical states it reproduces their corresponding scattering amplitude. As a particular case we obtain BRST invariant vertex for the open-closed string transition. (orig.)

  12. Vertex functions at finite momentum: Application to antiferromagnetic quantum criticality

    Science.gov (United States)

    Wölfle, Peter; Abrahams, Elihu

    2016-02-01

    We analyze the three-point vertex function that describes the coupling of fermionic particle-hole pairs in a metal to spin or charge fluctuations at nonzero momentum. We consider Ward identities, which connect two-particle vertex functions to the self-energy, in the framework of a Hubbard model. These are derived using conservation laws following from local symmetries. The generators considered are the spin density and particle density. It is shown that at certain antiferromagnetic critical points, where the quasiparticle effective mass is diverging, the vertex function describing the coupling of particle-hole pairs to the spin density Fourier component at the antiferromagnetic wave vector is also divergent. Then we give an explicit calculation of the irreducible vertex function for the case of three-dimensional antiferromagnetic fluctuations, and show that it is proportional to the diverging quasiparticle effective mass.

  13. Performance of the ALICE secondary vertex b-tagging algorithm

    CERN Document Server

    INSPIRE-00262232

    2016-11-04

    The identification of jets originating from beauty quarks in heavy-ion collisions is important to study the properties of the hot and dense matter produced in such collisions. A variety of algorithms for b-jet tagging was elaborated at the LHC experiments. They rely on the properties of B hadrons, i.e. their long lifetime, large mass and large multiplicity of decay products. In this work, the b-tagging algorithm based on displaced secondary-vertex topologies is described. We present Monte Carlo based performance studies of the algorithm for charged jets reconstructed with the ALICE tracking system in p-Pb collisions at $\\sqrt{s_\\text{NN}}$ = 5.02 TeV. The tagging efficiency, rejection rate and the correction of the smearing effects of non-ideal detector response are presented.

  14. Renormalization and operator product expansion in theories with massless particles

    International Nuclear Information System (INIS)

    Anikin, S.A.; Smirnov, V.A.

    1985-01-01

    Renormalization procedure in theories including massless particles is presented. With the help of counterterm formalism the operator product expansion for arbitrary composite fields is derived. The coefficient functions are explicitly expressed in terms of certain Green's functions. (author)

  15. Self-locking degree-4 vertex origami structures.

    Science.gov (United States)

    Fang, Hongbin; Li, Suyi; Wang, K W

    2016-11-01

    A generic degree-4 vertex (4-vertex) origami possesses one continuous degree-of-freedom for rigid folding, and this folding process can be stopped when two of its facets bind together. Such facet-binding will induce self-locking so that the overall structure stays at a pre-specified configuration without additional locking elements or actuators. Self-locking offers many promising properties, such as programmable deformation ranges and piecewise stiffness jumps, that could significantly advance many adaptive structural systems. However, despite its excellent potential, the origami self-locking features have not been well studied, understood, and used. To advance the state of the art, this research conducts a comprehensive investigation on the principles of achieving and harnessing self-locking in 4-vertex origami structures. Especially, for the first time, this study expands the 4-vertex structure construction from single-component to dual-component designs and investigates their self-locking behaviours. By exploiting various tessellation designs, this research discovers that the dual-component designs offer the origami structures with extraordinary attributes that the single-component structures do not have, which include the existence of flat-folded locking planes, programmable locking points and deformability. Finally, proof-of-concept experiments investigate how self-locking can effectively induce piecewise stiffness jumps. The results of this research provide new scientific knowledge and a systematic framework for the design, analysis and utilization of self-locking origami structures for many potential engineering applications.

  16. The Mark III vertex chamber and prototype test results

    International Nuclear Information System (INIS)

    Grab, C.

    1987-07-01

    A vertex chamber has been constructed for use in the Mark III experiment. The chamber is positioned inside the current main drift chamber and will be used to trigger data collection, to aid in vertex reconstruction, and to improve the momentum resolution. This paper discusses the chamber's construction and performance and tests of the prototype

  17. RAVE-a Detector-independent vertex reconstruction toolkit

    Energy Technology Data Exchange (ETDEWEB)

    Waltenberger, Wolfgang [Institute of High Energy Physics, Austrian Academy of Sciences A-1050 Vienna (Austria)], E-mail: walten@hephy.oeaw.ac.at; Mitaroff, Winfried; Moser, Fabian [Institute of High Energy Physics, Austrian Academy of Sciences A-1050 Vienna (Austria)

    2007-10-21

    A detector-independent toolkit for vertex reconstruction (RAVE) is being developed, along with a standalone framework (VERTIGO) for testing, analyzing and debugging. The core algorithms represent state of the art for geometric vertex finding and fitting by both linear (Kalman filter) and robust estimation methods. Main design goals are ease of use, flexibility for embedding into existing software frameworks, extensibility, and openness. The implementation is based on modern object-oriented techniques, is coded in C++ with interfaces for Java and Python, and follows an open-source approach. A beta release is available.

  18. RAVE-a Detector-independent vertex reconstruction toolkit

    International Nuclear Information System (INIS)

    Waltenberger, Wolfgang; Mitaroff, Winfried; Moser, Fabian

    2007-01-01

    A detector-independent toolkit for vertex reconstruction (RAVE) is being developed, along with a standalone framework (VERTIGO) for testing, analyzing and debugging. The core algorithms represent state of the art for geometric vertex finding and fitting by both linear (Kalman filter) and robust estimation methods. Main design goals are ease of use, flexibility for embedding into existing software frameworks, extensibility, and openness. The implementation is based on modern object-oriented techniques, is coded in C++ with interfaces for Java and Python, and follows an open-source approach. A beta release is available

  19. On Pathos Adjacency Cut Vertex Jump Graph of a Tree

    OpenAIRE

    Nagesh.H.M; R.Chandrasekhar

    2014-01-01

    In this paper the concept of pathos adjacency cut vertex jump graph PJC(T) of a tree T is introduced. We also present a characterization of graphs whose pathos adjacency cut vertex jump graphs are planar, outerplanar, minimally non-outerplanar, Eulerian and Hamiltonian.

  20. Operadic formulation of topological vertex algebras and gerstenhaber or Batalin-Vilkovisky algebras

    International Nuclear Information System (INIS)

    Huang Yizhi

    1994-01-01

    We give the operadic formulation of (weak, strong) topological vertex algebras, which are variants of topological vertex operator algebras studied recently by Lian and Zuckerman. As an application, we obtain a conceptual and geometric construction of the Batalin-Vilkovisky algebraic structure (or the Gerstenhaber algebra structure) on the cohomology of a topological vertex algebra (or of a weak topological vertex algebra) by combining this operadic formulation with a theorem of Getzler (or of Cohen) which formulates Batalin-Vilkovisky algebras (or Gerstenhaber algebras) in terms of the homology of the framed little disk operad (or of the little disk operad). (orig.)

  1. Vertex Reconstruction and Performance in ATLAS

    CERN Document Server

    Whitmore, Ben William; The ATLAS collaboration

    2017-01-01

    Efficient and precise reconstruction of the primary vertices in LHC collisions is essential in both the reconstruction of the full kinematic properties of a hard-scatter event and of soft interactions as a measure of the amount of pile-up. The reconstruction of the primary vertices in the busy, high pile up environment of the LHC is a challenging task. The challenges and novel methods developed by the ATLAS experiment to reconstruct vertices in such environments will be presented. The performance of the current vertexing algorithms using Run-2 data will be presented and compared to results from simulation. Additionally, data-driven methods to evaluate vertex resolution, and details of upgrades to the ATLAS inner detector will be presented.

  2. Random tree growth by vertex splitting

    International Nuclear Information System (INIS)

    David, F; Dukes, W M B; Jonsson, T; Stefánsson, S Ö

    2009-01-01

    We study a model of growing planar tree graphs where in each time step we separate the tree into two components by splitting a vertex and then connect the two pieces by inserting a new link between the daughter vertices. This model generalizes the preferential attachment model and Ford's α-model for phylogenetic trees. We develop a mean field theory for the vertex degree distribution, prove that the mean field theory is exact in some special cases and check that it agrees with numerical simulations in general. We calculate various correlation functions and show that the intrinsic Hausdorff dimension can vary from 1 to ∞, depending on the parameters of the model

  3. Pion production and absorption in nuclear reactions. I. The vertex function

    International Nuclear Information System (INIS)

    Nutt, W.T.; Shakin, C.M.

    1977-01-01

    We have performed a model calculation of the pion-nucleon vertex function for the case in which one nucleon is allowed to go far off its mass shell. We discuss the relevance of this vertex function for the calculation of pion production and absorption in nuclear reactions, such as (π + ,p), (p,π + ), and for the pionic disintegration of the deuteron. The model used is based upon an approximation to an exact equation for the vertex function derived from a field-theoretic model with pseudoscalar coupling. Our calculations indicate a strong dependence of the vertex function on the invariant mass of the off-shell nucleon. The results are dominated by the presence of the 1470 MeV, P 11 resonance

  4. Silicon Technologies for the CLIC Vertex Detector

    CERN Document Server

    Spannagel, Simon

    2017-01-01

    CLIC is a proposed linear e$^+$e$^−$ collider designed to provide particle collisions at center-of-mass energies of up to 3 TeV. Precise measurements of the properties of the top quark and the Higgs boson, as well as searches for Beyond the Standard Model physics require a highly performant CLIC detector. In particular the vertex detector must provide a single point resolution of only a few micrometers while not exceeding the envisaged material budget of around 0.2%$~X_0$ per layer. Beam-beam interactions and beamstrahlung processes impose an additional requirement on the timestamping capabilities of the vertex detector of about 10 ns. These goals can only be met by using novel techniques in the sensor and ASIC design as well as in the detector construction. The R&D program for the CLIC vertex detector explores various technologies in order to meet these demands. The feasibility of planar sensors with a thickness of 50–150$~\\mu$m, including different active edge designs, are evaluated using Timepix3 A...

  5. Complex growing networks with intrinsic vertex fitness

    International Nuclear Information System (INIS)

    Bedogne, C.; Rodgers, G. J.

    2006-01-01

    One of the major questions in complex network research is to identify the range of mechanisms by which a complex network can self organize into a scale-free state. In this paper we investigate the interplay between a fitness linking mechanism and both random and preferential attachment. In our models, each vertex is assigned a fitness x, drawn from a probability distribution ρ(x). In Model A, at each time step a vertex is added and joined to an existing vertex, selected at random, with probability p and an edge is introduced between vertices with fitnesses x and y, with a rate f(x,y), with probability 1-p. Model B differs from Model A in that, with probability p, edges are added with preferential attachment rather than randomly. The analysis of Model A shows that, for every fixed fitness x, the network's degree distribution decays exponentially. In Model B we recover instead a power-law degree distribution whose exponent depends only on p, and we show how this result can be generalized. The properties of a number of particular networks are examined

  6. Conformally covariant massless spin-two field equations

    International Nuclear Information System (INIS)

    Drew, M.S.; Gegenberg, J.D.

    1980-01-01

    An explicit proof is constructed to show that the field equations for a symmetric tensor field hsub(ab) describing massless spin-2 particles in Minkowski space-time are not covariant under the 15-parameter group SOsub(4,2); this group is usually associated with conformal transformations on flat space, and here it will be considered as a global gauge group which acts upon matter fields defined on space-time. Notwithstanding the above noncovariance, the equations governing the rank-4 tensor Ssub(abcd) constructed from hsub(ab) are shown to be covariant provided the contraction Ssub(ab) vanishes. Conformal covariance is proved by demonstrating the covariance of the equations for the equivalent 5-component complex field; in fact, covariance is proved for a general field equation applicable to massless particles of any spin >0. It is shown that the noncovariance of the hsub(ab) equations may be ascribed to the fact that the transformation behaviour of hsub(ab) is not the same as that of a field consisting of a gauge only. Since this is in contradistinction to the situation for the electromagnetic-field equations, the vector form of the electromagnetic equations is cast into a form which can be duplicated for the hsub(ab)-field. This procedure results in an alternative, covariant, field equation for hsub(ab). (author)

  7. Connections for Small Vertex Models

    Indian Academy of Sciences (India)

    This paper is a first attempt at calssifying connections on small vertex models i.e., commuting squares of the form displayed in (1.2) below. ... obtain necessary conditions for two such `model connections' in (2, ) to be ... Current Issue : Vol.

  8. Wrong vertex displacements due to Lee-Wick resonances at LHC

    International Nuclear Information System (INIS)

    Alvarez, E.; Schat, C.; Rold, L. da; Szynkman, A.

    2009-01-01

    We show how a resonance from the recently proposed Lee-Wick Standard Model could lead to wrong vertex displacements at LHCb. We study which could be the possible 'longest lived' Lee-Wick particle that could be created at LHC, and we study its possible decays and detections. We conclude that there is a region in the parameter space which would give wrong vertex displacements as a unique signature of the Lee-Wick Standard Model at LHCb. Further numerical simulation shows that LHC era could explore these wrong vertex displacements through Lee-Wick leptons below 500 GeV. (author)

  9. Calculation of track and vertex errors for detector design studies

    International Nuclear Information System (INIS)

    Harr, R.

    1995-01-01

    The Kalman Filter technique has come into wide use for charged track reconstruction in high-energy physics experiments. It is also well suited for detector design studies, allowing for the efficient estimation of optimal track covariance matrices without the need of a hit level Monte Carlo simulation. Although much has been published about the Kalman filter equations, there is a lack of previous literature explaining how to implement the equations. In this paper, the operators necessary to implement the Kalman filter equations for two common detector configurations are worked out: a central detector in a uniform solenoidal magnetic field, and a fixed-target detector with no magnetic field in the region of the interactions. With the track covariance matrices in hand, vertex and invariant mass errors are readily calculable. These quantities are particularly interesting for evaluating experiments designed to study weakly decaying particles which give rise to displaced vertices. The optimal vertex errors are obtained via a constrained vertex fit. Solutions are presented to the constrained vertex problem with and without kinematic constraints. Invariant mass errors are obtained via propagation of errors; the use of vertex constrained track parameters is discussed. Many of the derivations are new or previously unpublished

  10. Symmetry breaking due to quantum fluctuations in massless field theories

    International Nuclear Information System (INIS)

    Ghose, P.; Datta, A.

    1977-10-01

    It is shown that quantum fluctuations can act as the driving mechanism for the spontaneous breakdown of both scale and the discrete phi→-phi symmetries in a lamdaphi 4 theory which is massless and scale invariant in the tree approximation. Consequently dimensional transformation occurs and the dimensionless and only parameter lambda in the theory is fixed and replaced by the vacuum expectation value of the field. These results are shown to be consistent with the appropriate renormalization group equation for the theory. A scalar electrodynamics which is massless and scale invariant in the tree approximation is also considered, and it is shown that the Higgs meson in such a theory is much heavier than the vector meson for small values of the gauge coupling constant e. Another interesting consequence of such a theory is that it possesses vortex-line solutions only when quantum fluctuations are taken into account

  11. Vertex dynamics in multi-soliton solutions of Kadomtsev–Petviashvili II equation

    International Nuclear Information System (INIS)

    Zarmi, Yair

    2014-01-01

    A functional of the solution of the Kadomtsev–Petviashvili II equation maps multi-soliton solutions onto systems of vertices—structures that are localized around soliton junctions. A solution with one junction is mapped onto a single vertex, which emulates a free, spatially extended, particle. In solutions with several junctions, each junction is mapped onto a vertex. Moving in the x–y plane, the vertices collide, coalesce upon collision and then split up. When well separated, they emulate free particles. Multi-soliton solutions, whose structure does not change under space–time inversion as |t| → ∞, are mapped onto vertex systems that undergo elastic collisions. Solutions, whose structure does change, are mapped onto systems that undergo inelastic collisions. The inelastic vertex collisions generated from the infinite family of (M,1) solutions (M external solitons, (M − 2) Y-shaped soliton junctions, M ⩾ 4) play a unique role: the only definition of vertex mass consistent with momentum conservation in these collisions is the spatial integral of the vertex profile. This definition ensures, in addition, that, in these collisions, the total mass and kinetic energy due to the motion in the y-direction are conserved. In general, the kinetic energy due to the motion in the x-direction is not conserved in these collisions. (paper)

  12. Construction of vertex operators using operator formalism techniques

    International Nuclear Information System (INIS)

    Gato, B.; Massachusetts Inst. of Tech., Cambridge

    1989-01-01

    We derive vertex operators in oscillator form as an application of the conserved charges method developed by Vafa for the operator formalism in higher genus Riemann surfaces. This construction proves to be clear, direct and valid for the bosonic and fermionic strings as wells as for twisted strings on orbifolds. We discuss the method and construct vertex operators for the bosonic string moving on Z N orbifolds and for the fermionic string in the NSR formulation. (orig.)

  13. The vertex detector for the Lepton/Photon collaboration

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, J.P.; Boissevain, J.G.; Fox, D.; Hecke, H. van; Jacak, B.V.; Kapustinsky, J.S.; Leitch, M.J.; McGaughey, P.L.; Moss, J.M.; Sondheim, W.E. [Los Alamos National Lab., NM (United States)

    1991-12-31

    The conceptual design of the vertex detector for the Lepton/Photon Collaboration at RHIC is described, including simulations of its expected performance. The design consists of two con- centric layers of single-sided Si strips. The expected performance as a multiplicity detector and in measuring the pseudo-rapidity ({nu}) distribution is discussed as well as the expected vertex finding efficiency and accuracy. Various options which could be used to reduce the cost of the detector are also discussed.

  14. The vertex detector for the Lepton/Photon Collaboration

    International Nuclear Information System (INIS)

    Sullivan, J.P.; Boissevain, J.G.; Fox, D.; van Hecke, H.; Jacak, B.V.; Kapustinsky, J.S.; Leitch, M.J.; McGaughey, P.L.; Moss, J.M.; Sondheim, W.E.

    1991-01-01

    The conceptual design of the vertex detector for the Lepton/Photon Collaboration at RHIC is described, including simulations of its expected performance. The design consists of two concentric layers of single-sided Si strips. The expected performance as a multiplicity detector and in measuring the pseudo-rapidity η distribution is discussed as well as the expected vertex finding efficiency and accuracy. Various options which could be used to reduce the cost of the detector are also discussed

  15. Intrinsic-normal-ordered vertex operators from the multiloop N-tachyon amplitude

    International Nuclear Information System (INIS)

    Aldazabal, G.; Nunez, C.; Bonini, M.; Iengo, R.

    1987-09-01

    We construct vertex operators for arbitrary mass level states of the closed bosonic string. Starting from a generalization of the Koba-Nielsen amplitude which is suitable for an arbitrary genus Riemann surface, we read the vertex operators from the residues of the poles for the intermediate states. Since the original expression is metric independent and normal ordered without the need of inventing any regularization scheme, our vertex operators also possess these properties. We discuss their general features. (author). 17 refs

  16. A quantum hybrid with a thin antenna at the vertex of a wedge

    Energy Technology Data Exchange (ETDEWEB)

    Carlone, Raffaele, E-mail: raffaele.carlone@unina.it [Università “Federico II” di Napoli, Dipartimento di Matematica e Applicazioni “R. Caccioppoli”, MSA, via Cinthia, I-80126, Napoli (Italy); Posilicano, Andrea, E-mail: andrea.posilicano@uninsubria.it [DiSAT, Università dell' Insubria, via Valleggio 11, I-22100, Como (Italy)

    2017-03-26

    We study the spectrum, resonances and scattering matrix of a quantum Hamiltonian on a “hybrid surface” consisting of a half-line attached by its endpoint to the vertex of a concave planar wedge. At the boundary of the wedge, outside the vertex, homogeneous Dirichlet conditions are imposed. The system is tunable by varying the measure of the angle at the vertex. - Highlights: • Spectral characterization of a quantum Hamiltonian on “hybrid surface” consisting of a halfline attached to the vertex of a concave planar wedge. • The system is tunable by varying the measure of the angle at the vertex. • Relation between the conduction properties inside the hybrid and formation of resonances. • Easy generalization of the results to more complicated structures.

  17. Infrared magneto-spectroscopy of two-dimensional and three-dimensional massless fermions: A comparison

    Energy Technology Data Exchange (ETDEWEB)

    Orlita, M., E-mail: milan.orlita@lncmi.cnrs.fr [Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, 38042 Grenoble (France); Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 Prague 2 (Czech Republic); Faugeras, C.; Barra, A.-L.; Martinez, G.; Potemski, M. [Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, 38042 Grenoble (France); Basko, D. M. [LPMMC UMR 5493, Université Grenoble 1/CNRS, B.P. 166, 38042 Grenoble (France); Zholudev, M. S. [Laboratoire Charles Coulomb (L2C), UMR CNRS 5221, GIS-TERALAB, Université Montpellier II, 34095 Montpellier (France); Institute for Physics of Microstructures, RAS, Nizhny Novgorod GSP-105 603950 (Russian Federation); Teppe, F.; Knap, W. [Laboratoire Charles Coulomb (L2C), UMR CNRS 5221, GIS-TERALAB, Université Montpellier II, 34095 Montpellier (France); Gavrilenko, V. I. [Institute for Physics of Microstructures, RAS, Nizhny Novgorod GSP-105 603950 (Russian Federation); Mikhailov, N. N.; Dvoretskii, S. A. [A.V. Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation); Neugebauer, P. [Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany); Berger, C. [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Institut Néel/CNRS-UJF BP 166, F-38042 Grenoble Cedex 9 (France); Heer, W. A. de [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2015-03-21

    Here, we report on a magneto-optical study of two distinct systems hosting massless fermions—two-dimensional graphene and three-dimensional HgCdTe tuned to the zero band gap condition at the point of the semiconductor-to-semimetal topological transition. Both materials exhibit, in the quantum regime, a fairly rich magneto-optical response, which is composed from a series of intra- and interband inter-Landau level resonances with for massless fermions typical √(B) dependence. The impact of the system's dimensionality and of the strength of the spin-orbit interaction on the optical response is also discussed.

  18. The CDF online silicon vertex tracker

    International Nuclear Information System (INIS)

    Ashmanskas, W.

    2001-01-01

    The CDF Online Silicon Vertex Tracker reconstructs 2-D tracks by linking hit positions measured by the Silicon Vertex Detector to the Central Outer Chamber tracks found by the eXtremely Fast Tracker. The system has been completely built and assembled and it is now being commissioned using the first CDF run II data. The precision measurement of the track impact parameter will allow triggering on B hadron decay vertices and thus investigating important areas in the B sector, like CP violation and B s mixing. In this paper we briefly review the architecture and the tracking algorithms implemented in the SVT and we report on the performance of the system achieved in the early phase of CDF run II

  19. The CDF online Silicon Vertex Tracker

    International Nuclear Information System (INIS)

    Ashmanskas, W.; Bardi, A.; Bari, M.; Belforte, S.; Berryhill, J.; Bogdan, M.; Carosi, R.; Cerri, A.; Chlachidze, G.; Culbertson, R.; Dell'Orso, M.; Donati, S.; Fiori, I.; Frisch, H.J.; Galeotti, S.; Giannetti, P.; Glagolev, V.; Moneta, L.; Morsani, F.; Nakaya, T.; Passuello, D.; Punzi, G.; Rescigno, M.; Ristori, L.; Sanders, H.; Sarkar, S.; Semenov, A.; Shochet, M.; Speer, T.; Spinella, F.; Wu, X.; Yang, U.; Zanello, L.; Zanetti, A.M.

    2002-01-01

    The CDF Online Silicon Vertex Tracker (SVT) reconstructs 2D tracks by linking hit positions measured by the Silicon Vertex Detector to the Central Outer Chamber tracks found by the eXtremely Fast Tracker (XFT). The system has been completely built and assembled and it is now being commissioned using the first CDF run II data. The precision measurement of the track impact parameter will allow triggering on B hadron decay vertices and thus investigating important areas in the B sector, like CP violation and B s mixing. In this paper we briefly review the architecture and the tracking algorithms implemented in the SVT and we report on the performance of the system achieved in the early phase of CDF run II

  20. Performance of the ATLAS primary vertex reconstruction algorithms

    CERN Document Server

    Zhang, Matt

    2017-01-01

    The reconstruction of primary vertices in the busy, high pile up environment of the LHC is a challenging task. The challenges and novel methods developed by the ATLAS experiment to reconstruct vertices in such environments will be presented. Such advances in vertex seeding include methods taken from medical imagining, which allow for reconstruction of very nearby vertices will be highlighted. The performance of the current vertexing algorithms using early Run-2 data will be presented and compared to results from simulation.

  1. Automated computation of one-loop integrals in massless theories

    International Nuclear Information System (INIS)

    Hameren, A. van; Vollinga, J.; Weinzierl, S.

    2005-01-01

    We consider one-loop tensor and scalar integrals, which occur in a massless quantum field theory, and we report on the implementation into a numerical program of an algorithm for the automated computation of these one-loop integrals. The number of external legs of the loop integrals is not restricted. All calculations are done within dimensional regularization. (orig.)

  2. Vertex operators for a bosonic string

    International Nuclear Information System (INIS)

    Sasaki, Ryu; Yamanaka, Itaru.

    1985-09-01

    Based on the operator formalism and the Virasoro algebra, we present a simple method of constructing vertex operators describing the emission and absorption of general particles in bosonic string theories. (author)

  3. Dynamics of massless higher spins in the second order in curvatures

    Energy Technology Data Exchange (ETDEWEB)

    Vasiliev, M A [International Centre for Theoretical Physics, Trieste (Italy)

    1990-04-05

    The consistent equations of motion of interacting massless fields of all spins s=0, 1/2, 1, ..., {infinity} are constructed explicitly to the second order of the expansion in powers of the higher spin strengths. (orig.).

  4. Algebraic Bethe ansatz for 19-vertex models with reflection conditions

    International Nuclear Information System (INIS)

    Utiel, Wagner

    2003-01-01

    In this work we solve the 19-vertex models with the use of algebraic Bethe ansatz for diagonal reflection matrices (Sklyanin K-matrices). The eigenvectors, eigenvalues and Bethe equations are given in a general form. Quantum spin chains of spin one derived from the 19-vertex models were also discussed

  5. A practical introduction to electroweak radiative corrections

    International Nuclear Information System (INIS)

    Drees, M.

    1991-05-01

    This is a brief introduction into electroweak radiative corrections within the Standard Model, with the emphasis on performing actual calculations. To this end, a complete set of expressions is given that allows the computation of the ρ parameter, the W mass, and Z→fanti f decays for massless fermions, where the anti Manti S scheme has been used. I conclude with an assessment of what we have learned so far from electroweak precision experiments, and a brief outlook. (orig.)

  6. Meson-baryon-baryon vertex function and the Ward-Takahashi identity

    International Nuclear Information System (INIS)

    Wang, S.; Banerjee, M.K.

    1996-01-01

    Ohta proposed a solution for the well-known difficulty of satisfying the Ward-Takahashi identity for a photo-meson-baryon-baryon amplitude (γMBB) when a dressed meson-baryon-baryon (MBB) vertex function is present. He obtained a form for the γMBB amplitude which contained, in addition to the usual pole terms, longitudinal seagull terms which were determined entirely by the MBB vertex function. He arrived at his result by using a Lagrangian which yields the MBB vertex function at tree level. We show that such a Lagrangian can be neither Hermitian nor charge conjugation invariant. We have been able to reproduce Ohta close-quote s result for the γMBB amplitude using the Ward-Takahashi identity and no other assumption, dynamical or otherwise, and the most general form for the MBB and γMBB vertices. However, contrary to Ohta close-quote s finding, we find that the seagull terms are not robust. The seagull terms extracted from the γMBB vertex occur unchanged in tree graphs, such as in an exchange current amplitude. But the seagull terms which appear in a loop graph, as in the calculation of an electromagnetic form factor, are, in general, different. The whole procedure says nothing about the transverse part of the (γMBB) vertex and its contributions to the amplitudes in question. copyright 1996 The American Physical Society

  7. Introduction to vertex algebras, Borcherds algebras and the Monster Lie algebras

    International Nuclear Information System (INIS)

    Gebert, R.W.

    1993-09-01

    The theory of vertex algebras constitutes a mathematically rigorous axiomatic formulation of the algebraic origins of conformal field theory. In this context Borcherds algebras arise as certain ''physical'' subspaces of vertex algebras. The aim of this review is to give a pedagogical introduction into this rapidly-developing area of mathematics. Based on the machinery of formal calculus we present the axiomatic definition of vertex algebras. We discuss the connection with conformal field theory by deriving important implications of these axioms. In particular, many explicit calculations are presented to stress the eminent role of the Jacobi identity axiom for vertex algebras. As a class of concrete examples the vertex algebras associated with even lattices are constructed and it is shown in detail how affine Lie algebras and the fake Monster Lie algebra naturally appear. This leads us to the abstract definition of Borcherds algebras as generalized Kac-Moody algebras and their basic properties. Finally, the results about the simplest generic Borcherds algebras are analysed from the point of view of symmetry in quantum theory and the construction of the Monster Lie algebra is sketched. (orig.)

  8. The CDF Silicon Vertex Trigger

    International Nuclear Information System (INIS)

    Dell'Orso, Mauro

    2006-01-01

    Motivations, design, performance and ongoing upgrade of the CDF Silicon Vertex Trigger are presented. The system provides CDF with a powerful tool for online tracking with offline quality in order to enhance the reach on B-physics and large P t -physics coupled to b quarks

  9. Higher order corrections to Higgs boson decays in the MSSM with complex parameters

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Karina E. [Bonn Univ. (Germany). Bethe Center for Theoretical Physics; Rzehak, Heidi [Freiburg Univ. (Germany). Physikalisches Inst.; Weiglein, Georg [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2011-03-15

    We discuss Higgs boson decays in the CP-violating MSSM, and examine their phe- nomenological impact using cross section limits from the LEP Higgs searches. This includes a discussion of the full 1-loop results for the partial decay widths of neutral Higgs bosons into lighter neutral Higgs bosons (h{sub a}{yields}h{sub b}h{sub c}) and of neutral Higgs bosons into fermions (h{sub a}{yields}f anti f). In calculating the genuine vertex corrections, we take into account the full spectrum of supersymmetric particles and all complex phases of the supersymmetric parameters. These genuine vertex corrections are supplemented with Higgs propagator corrections incorporating the full one-loop and the dominant two-loop contributions, and we illustrate a method of consistently treating diagrams involving mixing with Goldstone and Z bosons. In particular, the genuine vertex corrections to the process h{sub a}{yields}h{sub b}h{sub c} are found to be very large and, where this process is kinematically allowed, can have a significant effect on the regions of the CPX bench- mark scenario which can be excluded by the results of the Higgs searches at LEP. However, there remains an unexcluded region of CPX parameter space at a lightest neutral Higgs boson mass of {proportional_to}45 GeV. In the analysis, we pay particular attention to the conversion between parameters defined in different renormalisation schemes and are therefore able to make a comparison to the results found using renormalisation group improved/effective potential calculations. (orig.)

  10. BTeV detached vertex trigger

    International Nuclear Information System (INIS)

    Gottschalk, E.E.

    2001-01-01

    BTeV is a collider experiment that has been approved to run in the Tevatron at Fermilab. The experiment will conduct precision studies of CP violation using a forward-geometry detector. The detector will be optimized for high-rate detection of beauty and charm particles produced in collisions between protons and anti-protons. BTeV will trigger on beauty and charm events by taking advantage of the main difference between these heavy quark events and more typical hadronic events - the presence of detached beauty and charm decay vertices. The first stage of the BTeV trigger will receive data from a pixel vertex detector at a rate of 100 gb s -1 , reconstruct tracks and vertices for every beam crossing, reject 99% of beam crossings that do not produce beauty or charm particles, and trigger on beauty events with high efficiency. An overview of the trigger design and its influence on the design of the pixel vertex detector is presented

  11. Stochastic higher spin six vertex model and Macdonald measures

    Science.gov (United States)

    Borodin, Alexei

    2018-02-01

    We prove an identity that relates the q-Laplace transform of the height function of a (higher spin inhomogeneous) stochastic six vertex model in a quadrant on one side and a multiplicative functional of a Macdonald measure on the other. The identity is used to prove the GUE Tracy-Widom asymptotics for two instances of the stochastic six vertex model via asymptotic analysis of the corresponding Schur measures.

  12. Pion-nucleon vertex function with an off-shell nucleon

    International Nuclear Information System (INIS)

    Nutt, W.T.; Shakin, C.M.

    1977-01-01

    A model calculation for the π-N vertex function is presented in the case in which there is a single off-mass-shell nucleon and a (nearly) on-mass-shell pion. Very strong effects due to the P 11 resonance at 1470 MeV are found. A simple parametrization of the vertex function is prvided in the case that at least one nucleon is on its mass shell. (Auth.)

  13. Worldline calculation of the three-gluon vertex

    International Nuclear Information System (INIS)

    Ahmadiniaz, N.; Schubert, C.

    2012-01-01

    The three-gluon vertex is a basic object of interest in nonabelian gauge theory. At the one-loop level, it has been calculated and analyzed by a number of authors. Here we use the worldline formalism to unify the calculations of the scalar, spinor and gluon loop contributions to the one-loop vertex, leading to an extremely compact representation in terms of field strength tensors. We verify its equivalence with previously obtained representations, and explain the relation of its structure to the low-energy effective action. The sum rule found by Binger and Brodsky for the scalar, spinor and gluon loop contributions in the present approach relates to worldline supersymmetry.

  14. Simulations with the PANDA micro-vertex-detector

    International Nuclear Information System (INIS)

    Kliemt, Ralf

    2013-01-01

    The PANDA experiment will be built at the upcoming FAIR facility at GSI in Darmstadt, featuring antiproton-proton reactions hadron physics in a medium energy range. Charm physics will play an important role and therefore secondary decays relatively close to the interaction zone as well. The MVD will be the detector closest to these and will provide high-quality vertex position measurements. Alongside the detector layout and hardware development a detailed detector simulation and reconstruction software is required. This work contains the detailed description and the performance studies of the software developed for the MVD. Furthermore, vertexing tools are introduced and their performance is studied for the MVD.

  15. Simulations with the PANDA micro-vertex-detector

    Energy Technology Data Exchange (ETDEWEB)

    Kliemt, Ralf

    2013-07-17

    The PANDA experiment will be built at the upcoming FAIR facility at GSI in Darmstadt, featuring antiproton-proton reactions hadron physics in a medium energy range. Charm physics will play an important role and therefore secondary decays relatively close to the interaction zone as well. The MVD will be the detector closest to these and will provide high-quality vertex position measurements. Alongside the detector layout and hardware development a detailed detector simulation and reconstruction software is required. This work contains the detailed description and the performance studies of the software developed for the MVD. Furthermore, vertexing tools are introduced and their performance is studied for the MVD.

  16. Six-vertex model and Schramm-Loewner evolution

    Science.gov (United States)

    Kenyon, Richard; Miller, Jason; Sheffield, Scott; Wilson, David B.

    2017-05-01

    Square ice is a statistical mechanics model for two-dimensional ice, widely believed to have a conformally invariant scaling limit. We associate a Peano (space-filling) curve to a square ice configuration, and more generally to a so-called six-vertex model configuration, and argue that its scaling limit is a space-filling version of the random fractal curve SL E κ, Schramm-Loewner evolution with parameter κ , where 4 <κ ≤12 +8 √{2 } . For square ice, κ =12 . At the "free-fermion point" of the six-vertex model, κ =8 +4 √{3 } . These unusual values lie outside the classical interval 2 ≤κ ≤8 .

  17. Vacuum polarization of massless fields in black holes

    International Nuclear Information System (INIS)

    Zel'nikov, A.I.; Frolov, V.P.

    1987-01-01

    This chapter contains a detailed survey of the fundamental results from an investigation of the contribution of massless fields to vacuum polarization near black holes. A method is developed for calculating the vacuum average energy-momentum tensor for the electromagnetic field on the surface of a black hole. An explicit value is derived for the renormalized energy-momentum tensor of an electromagnetic field near the event horizon of a rotating black hole

  18. Instanton density in a theory with massless quarks

    International Nuclear Information System (INIS)

    Shifman, M.A.; Vainshtein, A.I.; Zakharov, V.I.

    1979-01-01

    Effect of the complex structure of the QCD vacuum on the density of small-sized instantons is discussed. The method which allows to account for this effect of vacuum quark and gluon condensate is developed. Evaluation of the instanton density is given in the framework of the theory with one, two or three massless quarks. The results of the paper are presented for the cases of SU(2) and SU(3) color groups

  19. Network Unfolding Map by Vertex-Edge Dynamics Modeling.

    Science.gov (United States)

    Verri, Filipe Alves Neto; Urio, Paulo Roberto; Zhao, Liang

    2018-02-01

    The emergence of collective dynamics in neural networks is a mechanism of the animal and human brain for information processing. In this paper, we develop a computational technique using distributed processing elements in a complex network, which are called particles, to solve semisupervised learning problems. Three actions govern the particles' dynamics: generation, walking, and absorption. Labeled vertices generate new particles that compete against rival particles for edge domination. Active particles randomly walk in the network until they are absorbed by either a rival vertex or an edge currently dominated by rival particles. The result from the model evolution consists of sets of edges arranged by the label dominance. Each set tends to form a connected subnetwork to represent a data class. Although the intrinsic dynamics of the model is a stochastic one, we prove that there exists a deterministic version with largely reduced computational complexity; specifically, with linear growth. Furthermore, the edge domination process corresponds to an unfolding map in such way that edges "stretch" and "shrink" according to the vertex-edge dynamics. Consequently, the unfolding effect summarizes the relevant relationships between vertices and the uncovered data classes. The proposed model captures important details of connectivity patterns over the vertex-edge dynamics evolution, in contrast to the previous approaches, which focused on only vertex or only edge dynamics. Computer simulations reveal that the new model can identify nonlinear features in both real and artificial data, including boundaries between distinct classes and overlapping structures of data.

  20. Instantons and Massless Fermions in Two Dimensions

    Science.gov (United States)

    Callan, C. G. Jr.; Dashen, R.; Gross, D. J.

    1977-05-01

    The role of instantons in the breakdown of chiral U(N) symmetry is studied in a two dimensional model. Chiral U(1) is always destroyed by the axial vector anomaly. For N = 2 chiral SU(N) is also spontaneously broken yielding massive fermions and three (decoupled) Goldstone bosons. For N greater than or equal to 3 the fermions remain massless. Realistic four dimensional theories are believed to behave in a similar way but the critical N above which the fermions cease to be massive is not known in four dimensions.

  1. The massless two-loop two-point function

    International Nuclear Information System (INIS)

    Bierenbaum, I.; Weinzierl, S.

    2003-01-01

    We consider the massless two-loop two-point function with arbitrary powers of the propagators and derive a representation from which we can obtain the Laurent expansion to any desired order in the dimensional regularization parameter ε. As a side product, we show that in the Laurent expansion of the two-loop integral only rational numbers and multiple zeta values occur. Our method of calculation obtains the two-loop integral as a convolution product of two primitive one-loop integrals. We comment on the generalization of this product structure to higher loop integrals. (orig.)

  2. Research program in elementary particle theory: Outstanding junior investigator program

    International Nuclear Information System (INIS)

    Bowick, M.J.

    1989-01-01

    This report briefly discusses the following topics: high-temperature strings; axionic black holes and wormholes; equations of motion for massless modes as vanishing curvature; vertex algebras and string theory; and massive axions

  3. The RAVE/VERTIGO vertex reconstruction toolkit and framework

    Science.gov (United States)

    Waltenberger, W.; Mitaroff, W.; Moser, F.; Pflugfelder, B.; Riedel, H. V.

    2008-07-01

    A detector-independent toolkit for vertex reconstruction (RAVE1) is being developed, along with a standalone framework (VERTIGO2) for testing, analyzing and debugging. The core algorithms represent state-of-the-art for geometric vertex finding and fitting by both linear (Kalman filter) and robust estimation methods. Main design goals are ease of use, flexibility for embedding into existing software frameworks, extensibility, and openness. The implementation is based on modern object-oriented techniques, is coded in C++ with interfaces for Java and Python, and follows an open-source approach. A beta release is available.

  4. On the Relation between Edge and Vertex Modelling in Shape Analysis

    DEFF Research Database (Denmark)

    Hobolth, Asger; Kent, John Thomas; Dryden, Ian L.

    2002-01-01

    Objects in the plane with no obvious landmarks can be described by either vertex transformation vectors or edge transformation vectors. In this paper we provide the relation between the two transformation vectors. Grenander & Miller (1994) use a multivariate normal distribution with a block...... circulant covariance matrix to model the edge transformation vector. This type of model is also feasible for the vertex transformation vector and in certain cases the free parameters of the two models match up in a simple way. A vertex model and an edge model are applied to a data set of sand particles...

  5. Effects of Vertex Activity and Self-organized Criticality Behavior on a Weighted Evolving Network

    International Nuclear Information System (INIS)

    Zhang Guiqing; Yang Qiuying; Chen Tianlun

    2008-01-01

    Effects of vertex activity have been analyzed on a weighted evolving network. The network is characterized by the probability distribution of vertex strength, each edge weight and evolution of the strength of vertices with different vertex activities. The model exhibits self-organized criticality behavior. The probability distribution of avalanche size for different network sizes is also shown. In addition, there is a power law relation between the size and the duration of an avalanche and the average of avalanche size has been studied for different vertex activities

  6. AdS3/CFT2, finite-gap equations and massless modes

    International Nuclear Information System (INIS)

    Lloyd, Thomas; Stefański, Bogdan Jr.

    2014-01-01

    It is known that string theory on AdS 3 ×M 7 backgrounds, where M 7 =S 3 ×S 3 ×S 1 or S 3 ×T 4 , is classically integrable. This integrability has been previously used to write down a set of integral equations, known as the finite-gap equations. These equations can be solved for the closed string spectrum of the theory. However, it has been known for some time that the finite-gap equations on these AdS 3 ×M 7 backgrounds do not capture the dynamics of the massless modes of the closed string theory. In this paper we re-examine the derivation of the AdS 3 ×M 7 finite-gap system. We find that the conditions that had previously been imposed on these integral equations in order to implement the Virasoro constraints are too strict, and are in fact not required. We identify the correct implementation of the Virasoro constraints on finite-gap equations and show that this new, less restrictive condition captures the complete closed string spectrum on AdS 3 ×M 7

  7. Spikes and matter inhomogeneities in massless scalar field models

    International Nuclear Information System (INIS)

    Coley, A A; Lim, W C

    2016-01-01

    We shall discuss the general relativistic generation of spikes in a massless scalar field or stiff perfect fluid model. We first investigate orthogonally transitive (OT) G 2 stiff fluid spike models both heuristically and numerically, and give a new exact OT G 2 stiff fluid spike solution. We then present a new two-parameter family of non-OT G 2 stiff fluid spike solutions, obtained by the generalization of non-OT G 2 vacuum spike solutions to the stiff fluid case by applying Geroch’s transformation on a Jacobs seed. The dynamics of these new stiff fluid spike solutions is qualitatively different from that of the vacuum spike solutions in that the matter (stiff fluid) feels the spike directly and the stiff fluid spike solution can end up with a permanent spike. We then derive the evolution equations of non-OT G 2 stiff fluid models, including a second perfect fluid, in full generality, and briefly discuss some of their qualitative properties and their potential numerical analysis. Finally, we discuss how a fluid, and especially a stiff fluid or massless scalar field, affects the physics of the generation of spikes. (paper)

  8. Production of massless bottom jets in p anti p and pp collisions at next-to-leading order of QCD

    International Nuclear Information System (INIS)

    Bierenbaum, Isabella; Kramer, Gustav

    2016-03-01

    We present predictions for the inclusive production of bottom jets in proton-antiproton collisions at 1.96 TeV and proton-proton collisions at 7 TeV. The bottom quark is considered massless. In this scheme, we find that at small transverse momentum (p T ) the ratio of the next-to-leading order to the leading-order cross section (K factor) is smaller than one. It increases with increasing p T and approaches one at larger p T at a value depending essentially on the choice of the renormalization scale. Adding non-perturbative corrections obtained from PYTHIA Monte Carlo calculations leads to reasonable agreement with experimental b-jet cross sections obtained by the CDF and the CMS collaborations.

  9. Status and prospects of the LHCb Vertex Locator

    CERN Document Server

    van Beuzekom, Martin

    2007-01-01

    The Vertex Locator of the LHCb experiment is a dedicated subdetector for the reconstruction of primary and secondary vertices in b-hadron decays. The vertex detector features two halves with 21 modules each, mounted on retractable bases. Each module consists of two half-disk silicon micro-strip sensors measuring hits in R and $\\Phi$ coordinates. The strip pitch ranges from 40 to about 100 $\\mu$m. A vacuum boy with a 300 $\\mu$m thick aluminium foil shields the sensors from the wakefields of the proton beams which are passing at a distance of 8 mm from the active area of the sensors. Because of the harsh non-uniform radiation environment we opted for n-on-n strips in diffusion oxygenated float zone silicon. The current status of the vertex detector, which has recently entered the commissioning phase, will be discussed. Given the limited lifetime of the detector due to the radiation environment, developments for a detector replacement with n-on-p type modules have already started. Possible upgrade scenarios fo...

  10. Chiral vertex operators in off-conformal theory: Sine-Gordon example

    International Nuclear Information System (INIS)

    Chang, S.; Rajaraman, R.

    1996-01-01

    We study chiral vertex operators in sine-Gordon (SG) theory, viewed as an off-conformal system. We find that these operators, which would have been primary fields in the conformal limit, have interesting properties in the SG model. Some of them commute with the cosine interaction term in the Hamiltonian at a finite separation. Their Heisenberg equations of motion are local in space. An example of such vertex operators is Mandelstam close-quote s bosonic representation of the Fermi field. Another example is a set of vertex operators of topological number 2. We show how to construct conserved nonlocal currents from these operators. In the presence of the nonconformal interactions, these nonlocal currents have unique Lorentz spins. copyright 1996 The American Physical Society

  11. Gauge-invariant dressed fermion propagator in massless QED3

    International Nuclear Information System (INIS)

    Mitra, Indrajit; Ratabole, Raghunath; Sharatchandra, H.S.

    2006-01-01

    The infrared behaviour of the gauge-invariant dressed fermion propagator in massless QED 3 is discussed for three choices of dressing. It is found that only the propagator with the isotropic (in three Euclidean dimensions) choice of dressing is acceptable as the physical fermion propagator. It is explained that the negative anomalous dimension of this physical fermion does not contradict any field-theoretical requirement

  12. The ARGUS vertex trigger

    International Nuclear Information System (INIS)

    Koch, N.; Kolander, M.; Kolanoski, H.; Siegmund, T.; Bergter, J.; Eckstein, P.; Schubert, K.R.; Waldi, R.; Imhof, M.; Ressing, D.; Weiss, U.; Weseler, S.

    1995-09-01

    A fast second level trigger has been developed for the ARGUS experiment which recognizes tracks originating from the interaction region. The processor compares the hits in the ARGUS Micro Vertex Drift Chamber to 245760 masks stored in random access memories. The masks which are fully defined in three dimensions are able to reject tracks originating in the wall of the narrow beampipe of 10.5 mm radius. (orig.)

  13. Gauge structure of neutral-vector field theory. [Massive vector fields, massless limits

    Energy Technology Data Exchange (ETDEWEB)

    Kubo, R; Yokoyama, [Hiroshima univ., Takehara (Japan). Research Inst. for Theoretical Physics

    1975-03-01

    General aspects of gauge structure of neutral-vector field theory are investigated from an extended standpoint, where massive vector fields are treated in a form corresponding to the electromagnetic fields in a general gauge formalism reported previously. All results obtained are shown to have unique massless limits. It is shown that a generalized q-number gauge transformation for fields makes the theory invariant in cooperation with a simultaneous transformation for relevant gauge parameters. A method of differentiation with respect to a gauge variable is found to clarify some essential features of the gauge structure. Two possible types of gauge structure also emerge correspondingly to the massless case. A neutral-vector field theory proposed in a preceding paper is included in the present framework as the most preferable case.

  14. The Micro-Vertex-Detector for the P-bar ANDA experiment

    International Nuclear Information System (INIS)

    Zotti, Laura

    2013-01-01

    P-bar ANDA is a fixed target experiment that will be carried out at the future FAIR facility. P-bar ANDA will provide an excellent tool to address fundamental question in the field of hadronic physics, with a physic program that extends from the investigation of QCD (providing insight in the mechanisms of mass generation and confinement) to the test of fundamental symmetries. The Micro-Vertex-Detector located in the innermost part of the central tracking system will be composed by hybrid pixel and double-sided micro-strip silicon detectors. The Micro-Vertex-Detector will play an important role for the P-bar ANDA physics goals. The possibility to reconstruct the secondary vertices and the applicability of a precise D meson tagging is essential for the spectroscopy in the open charm sector and the charmonium mass region. To this aim the Micro-Vertex-Detector features a spatial resolution better than 100μm, a time resolution better than 20ns, a limited material budget, and a high data rate capability in a triggerless environment. An overview of the Micro-Vertex-Detector related to the physics goals will be presented.

  15. Multi-flavor massless QED{sub 2} at finite densities via Lefschetz thimbles

    Energy Technology Data Exchange (ETDEWEB)

    Tanizaki, Yuya [RIKEN BNL Research Center, Brookhaven National Laboratory,Upton, NY 11973-5000 (United States); Tachibana, Motoi [Department of Physics, Saga University,Saga 840-8502 (Japan)

    2017-02-15

    We consider multi-flavor massless (1+1)-dimensional QED with chemical potentials at finite spatial length and the zero-temperature limit. Its sign problem is solved using the mean-field calculation with complex saddle points.

  16. Partially-massless higher-spin algebras and their finite-dimensional truncations

    International Nuclear Information System (INIS)

    Joung, Euihun; Mkrtchyan, Karapet

    2016-01-01

    The global symmetry algebras of partially-massless (PM) higher-spin (HS) fields in (A)dS d+1 are studied. The algebras involving PM generators up to depth 2 (ℓ−1) are defined as the maximal symmetries of free conformal scalar field with 2 ℓ order wave equation in d dimensions. We review the construction of these algebras by quotienting certain ideals in the universal enveloping algebra of (A)dS d+1 isometries. We discuss another description in terms of Howe duality and derive the formula for computing trace in these algebras. This enables us to explicitly calculate the bilinear form for this one-parameter family of algebras. In particular, the bilinear form shows the appearance of additional ideal for any non-negative integer values of ℓ−d/2 , which coincides with the annihilator of the one-row ℓ-box Young diagram representation of so d+2 . Hence, the corresponding finite-dimensional coset algebra spanned by massless and PM generators is equivalent to the symmetries of this representation.

  17. The RAVE/VERTIGO vertex reconstruction toolkit and framework

    Energy Technology Data Exchange (ETDEWEB)

    Waltenberger, W; Mitaroff, W; Moser, F; Pflugfelder, B; Riedel, H V [Austrian Academy of Sciences, Institute of High Energy Physics, A-1050 Vienna (Austria)], E-mail: walten@hephy.oeaw.ac.at

    2008-07-15

    A detector-independent toolkit for vertex reconstruction (RAVE{sup 1}) is being developed, along with a standalone framework (VERTIGO{sup 2}) for testing, analyzing and debugging. The core algorithms represent state-of-the-art for geometric vertex finding and fitting by both linear (Kalman filter) and robust estimation methods. Main design goals are ease of use, flexibility for embedding into existing software frameworks, extensibility, and openness. The implementation is based on modern object-oriented techniques, is coded in C++ with interfaces for Java and Python, and follows an open-source approach. A beta release is available.

  18. Parity violation and the masslessness of the neutrino

    International Nuclear Information System (INIS)

    Mannheim, P.D.

    1978-09-01

    It is proposed that the weak interaction be obtained by gauging the strong interaction chiral flavor group. The neutrinos are then four-component spinors. Pairs of right-handed neutrinos are allowed to condense into the vacuum. This produces maximal parity violation in both the quark and lepton sectors of the weak interaction, keeps the neutrinos massless, and also leads to the conventional Weinberg mixing pattern. The approach also in principle provides a way of calculating the Cabibbo angle. 11 references

  19. Parity violation and the masslessness of the neutrino

    Energy Technology Data Exchange (ETDEWEB)

    Mannheim, P.D.

    1978-09-01

    It is proposed that the weak interaction be obtained by gauging the strong interaction chiral flavor group. The neutrinos are then four-component spinors. Pairs of right-handed neutrinos are allowed to condense into the vacuum. This produces maximal parity violation in both the quark and lepton sectors of the weak interaction, keeps the neutrinos massless, and also leads to the conventional Weinberg mixing pattern. The approach also in principle provides a way of calculating the Cabibbo angle. 11 references.

  20. The OPAL vertex detector prototype

    International Nuclear Information System (INIS)

    Roney, J.M.; Armitage, J.C.; Carnegie, R.K.; Giles, G.L.; Hemingway, R.J.; McPherson, A.C.; Pinfold, J.L.; Waterhouse, J.; Godfrey, L.; Hargrove, C.K.

    1989-01-01

    The prototype test results of a high resolution charged particle tracking detector are reported. The detector is designed to measure vertex topologies of particles produced in the e + e - collisions of the OPAL experiment at LEP. The OPAL vertex detector is a 1 m long, 0.46 m diameter cylindrical drift chamber consisting of an axial and stereo layer each of which is divided into 36 jet cells. A prototype chamber containing four axial and two stereo cells was studied using a pion test beam at CERN. The studies examined the prototype under a variety of operating conditions. An r-Φ resolution of 60 μm was obtained when the chamber was operated with argon (50%)-ethane (50%) at 3.75 bar, and when CO 2 (80%)-isobutane (20%) at 2.5 bar was used a 25 μm resolution was achieved. A z measurement using end-to-end time difference has a resolution of 3.5 cm. The details of these prototype studies are discussed in this paper. (orig.)

  1. Zero-mode effects in the lattice thermodynamics of massless bose field

    International Nuclear Information System (INIS)

    Gorenstein, M.I.; Lipskikh, S.I.; Sorin, A.S.

    1985-01-01

    The thermodynamics of free massless Bose field on a lattice is discussed. The coefficients characterizing the finite size effects are obtained. The use of these coefficients in the Yang-Mills thermodynamics allows one to make Monte-Carlo calculations, carried out on the different size lattices, self-consistent

  2. Technologies for Future Vertex and Tracking Detectors at CLIC

    CERN Document Server

    Spannagel, Simon

    2018-01-01

    CLIC is a proposed linear e$^{+}$e$^{-}$ collider with center-of-mass energies of up to 3 TeV. Its main objectives are precise top quark and Higgs boson measurements, as well as searches for Beyond Standard Model physics. To meet the physics goals, the vertex and tracking detectors require not only a spatial resolution of a few micrometers and a very low material budget, but also timing capabilities with a precision of a few nanoseconds to allow suppression of beam-induced backgrounds. Different technologies using hybrid silicon detectors are explored for the vertex detectors, such as dedicated readout ASICs, small-pitch active edge sensors as well as capacitively coupled High-Voltage CMOS sensors. Monolithic sensors are considered as an option for the tracking detector, and a prototype using a CMOS process with a high-resistivity epitaxial layer is being designed. Different designs using a silicon-on-insulator process are under investigation for both vertex and tracking detector. All prototypes are evaluate...

  3. Spectral asymmetry of the massless Dirac operator on a 3-torus

    International Nuclear Information System (INIS)

    Downes, Robert J.; Vassiliev, Dmitri; Levitin, Michael

    2013-01-01

    Consider the massless Dirac operator on a 3-torus equipped with Euclidean metric and standard spin structure. It is known that the eigenvalues can be calculated explicitly: the spectrum is symmetric about zero and zero itself is a double eigenvalue. The aim of the paper is to develop a perturbation theory for the eigenvalue with smallest modulus with respect to perturbations of the metric. Here the application of perturbation techniques is hindered by the fact that eigenvalues of the massless Dirac operator have even multiplicity, which is a consequence of this operator commuting with the antilinear operator of charge conjugation (a peculiar feature of dimension 3). We derive an asymptotic formula for the eigenvalue with smallest modulus for arbitrary perturbations of the metric and present two particular families of Riemannian metrics for which the eigenvalue with smallest modulus can be evaluated explicitly. We also establish a relation between our asymptotic formula and the eta invariant

  4. Aleph silicon microstrip vertex detector

    CERN Multimedia

    Laurent Guiraud

    1998-01-01

    This microstrip vertex locator was located at the heart of the ALEPH experiment, one of the four experiments at the Large Electron-Positron (LEP) collider. In the experiments at CERN's LEP, which ran from 1989 to 2000, modern silicon microvertex detectors, such as those used at ALEPH, monitored the production of short-lived particles close to the beam pipe.

  5. The ARGUS silicon vertex detector

    International Nuclear Information System (INIS)

    Michel, E.; Ball, S.; Ehret, K.; Geyer, C.; Hesselbarth, J.; Hoelscher, A.; Hofmann, W.; Holzer, B.; Huepper, A.; Khan, S.; Knoepfle, K.T.; Seeger, M.; Spengler, J.; Brogle, M.; Horisberger, R.

    1994-01-01

    A silicon microstrip vertex detector has been built as an upgrade to the ARGUS detector for increased precision and efficiency in the reconstruction of decay vertices. This paper discusses the mechanical and electronic design of this device and presents first results from its successful test operation yielding an impact parameter resolution of about 18 μm. ((orig.))

  6. Quark mass corrections to the perturbative thrust and its effect on the ...

    Indian Academy of Sciences (India)

    atic approach for handling power corrections using perturbation theory. ... The numerator of the above is given up to З(αs) and to З(ξ) by (σ0 = (4πα2/s)e2 i is the .... MARK II. AMY. ALEPH. DELPHI. OPAL. Massless formula. Massive formula ... We can also estimate the theoretical uncertainties on these quantities by vary-.

  7. Tracking and vertexing with the ATLAS detector at the LHC

    International Nuclear Information System (INIS)

    Hirsch, F.

    2011-01-01

    The Inner Detector of the ATLAS experiment at the Large Hadron Collider at CERN contains three tracking systems: The silicon Pixel Detector, the Silicon Microstrip Tracker and the Transition Radiation Tracker. In combination these detectors provide excellent track and vertex reconstruction efficiencies and resolutions. This paper describes studies which show the performance of track and vertex reconstruction on data collected at 7 TeV center-of-mass energy.

  8. Three-coloring graphs with no induced seven-vertex path II : using a triangle

    OpenAIRE

    Chudnovsky, Maria; Maceli, Peter; Zhong, Mingxian

    2015-01-01

    In this paper, we give a polynomial time algorithm which determines if a given graph containing a triangle and no induced seven-vertex path is 3-colorable, and gives an explicit coloring if one exists. In previous work, we gave a polynomial time algorithm for three-coloring triangle-free graphs with no induced seven-vertex path. Combined, our work shows that three-coloring a graph with no induced seven-vertex path can be done in polynomial time.

  9. CDF silicon vertex tracker: tevatron run II preliminary results

    International Nuclear Information System (INIS)

    Ashmanskas, W.; Belforte, S.; Budagov, Yu.

    2002-01-01

    The Online Silicon Vertex Tracker (SVT) is the unique new trigger processor dedicated to the 2-D reconstruction of charged particle trajectories at Level 2 of the CDF trigger. The SVT has been successfully built, installed and operated during the 2000 and 20001 CDF data taking runs. The performance of the SVT is already very close to the design. The SVT is able to find tracks and calculate their impact parameter with high precision (σ d = 35 μm). It is possible to correct the beam position offset and give the beam position feedback to accelerator in real time. In fact, the beam position is calculated online every few seconds with an accuracy of 1 to 5 μm. The beam position is continuously sent to the accelerator control. By using trigger tracks, parent particles such as K S 's and D 0 's are reconstructed, proving that the SVT is ready to be used for physics studies

  10. Massless versus Kaluza-Klein gravitons at the LHC

    International Nuclear Information System (INIS)

    Calmet, Xavier; Aquino, Priscila de; Rizzo, Thomas G.

    2010-01-01

    We show that the LHC will be able to differentiate between a four-dimensional model with quantum gravity at ∼1 TeV where the (massless) graviton becomes strongly coupled to standard model particles at 1 TeV and brane world type models with a large extra-dimensional volume and massive Kaluza-Klein gravitons. We estimate that the 14 TeV LHC could put a limit of the order of ∼5 TeV on the four-dimensional Planck mass in a model independent way.

  11. Vertex and Tracker Research and Development for CLIC

    CERN Document Server

    Munker, M

    2017-01-01

    Challenging detector requirements are imposed by the physics goals at the future multi-TeV e+e− Compact Linear Collider (CLIC). A single point resolution of 3 μm for the vertex detector and 7 μm for the tracker is required. Moreover, the CLIC vertex detector and tracker need to be extremely light weighted with a material budget of 0.2%X0 per layer in the vertex detector and 1 - 2%X0 in the tracker. A fast time slicing of 10 ns is further required to suppress background from beam-beam interactions. A wide range of sensor and readout ASIC technologies are investigated within the CLIC silicon pixel R&D; effort. Various hybrid planar sensor assemblies with a pixel size of 25 × 25 μm2 and 55 × 55 μm2 have been produced and characterised by laboratory measurements and during test-beam campaigns. Experimental and simulation results for thin (50 μm- 500 μm) slim edge and active-edge planar, and High-Voltage CMOS sensors hybridised to various readout ASICs (Timepix, Timepix3, CLICpix) are presented.

  12. Markov branching in the vertex splitting model

    International Nuclear Information System (INIS)

    Stefánsson, Sigurdur Örn

    2012-01-01

    We study a special case of the vertex splitting model which is a recent model of randomly growing trees. For any finite maximum vertex degree D, we find a one parameter model, with parameter α element of [0,1] which has a so-called Markov branching property. When D=∞ we find a two parameter model with an additional parameter γ element of [0,1] which also has this feature. In the case D = 3, the model bears resemblance to Ford's α-model of phylogenetic trees and when D=∞ it is similar to its generalization, the αγ-model. For α = 0, the model reduces to the well known model of preferential attachment. In the case α > 0, we prove convergence of the finite volume probability measures, generated by the growth rules, to a measure on infinite trees which is concentrated on the set of trees with a single spine. We show that the annealed Hausdorff dimension with respect to the infinite volume measure is 1/α. When γ = 0 the model reduces to a model of growing caterpillar graphs in which case we prove that the Hausdorff dimension is almost surely 1/α and that the spectral dimension is almost surely 2/(1 + α). We comment briefly on the distribution of vertex degrees and correlations between degrees of neighbouring vertices

  13. Vertex Stimulation as a Control Site for Transcranial Magnetic Stimulation: A Concurrent TMS/fMRI Study.

    Science.gov (United States)

    Jung, JeYoung; Bungert, Andreas; Bowtell, Richard; Jackson, Stephen R

    2016-01-01

    A common control condition for transcranial magnetic stimulation (TMS) studies is to apply stimulation at the vertex. An assumption of vertex stimulation is that it has relatively little influence over on-going brain processes involved in most experimental tasks, however there has been little attempt to measure neural changes linked to vertex TMS. Here we directly test this assumption by using a concurrent TMS/fMRI paradigm in which we investigate fMRI blood-oxygenation-level-dependent (BOLD) signal changes across the whole brain linked to vertex stimulation. Thirty-two healthy participants to part in this study. Twenty-one were stimulated at the vertex, at 120% of resting motor threshold (RMT), with short bursts of 1 Hz TMS, while functional magnetic resonance imaging (fMRI) BOLD images were acquired. As a control condition, we delivered TMS pulses over the left primary motor cortex using identical parameters to 11 other participants. Vertex stimulation did not evoke increased BOLD activation at the stimulated site. By contrast we observed widespread BOLD deactivations across the brain, including regions within the default mode network (DMN). To examine the effects of vertex stimulation a functional connectivity analysis was conducted. The results demonstrated that stimulating the vertex with suprathreshold TMS reduced neural activity in brain regions related to the DMN but did not influence the functional connectivity of this network. Our findings provide brain imaging evidence in support of the use of vertex simulation as a control condition in TMS but confirm that vertex TMS induces regional widespread decreases in BOLD activation. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  14. Leading quantum gravitational corrections to QED

    OpenAIRE

    Butt, M. S.

    2006-01-01

    We consider the leading post-Newtonian and quantum corrections to the non-relativistic scattering amplitude of charged spin-1/2 fermions in the combined theory of general relativity and QED. The coupled Dirac-Einstein system is treated as an effective field theory. This allows for a consistent quantization of the gravitational field. The appropriate vertex rules are extracted from the action, and the non-analytic contributions to the 1-loop scattering matrix are calculated in the non-relativi...

  15. Status of vertex and tracking detector R&D at CLIC

    CERN Document Server

    AUTHOR|(SzGeCERN)754272

    2015-01-01

    The physics aims at the future CLIC high-energy linear e+e- collider set very high precision requirements on the performance of the vertex and tracking detectors. Moreover, these detectors have to be well adapted to the experimental conditions, such as the bunch train structure of the beam and the presence of beam-induced backgrounds. The principal challenges are: a point resolution of a few micron, ultra-low mass (~0.2% X0 per layer for the inner vertex region), very low power dissipation (compatible with air-flow cooling in the inner vertex region) and pulsed power operation, complemented with ~10 ns time stamping capabilities. An overview of the R&D program for pixel and tracking detectors at CLIC will be presented, including recent results on an innovative hybridisation concept based on capacitive coupling between active sensors (HV-CMOS) and readout ASICs (CLICpix).

  16. The Yang-Baxter equation for PT invariant 19-vertex models

    International Nuclear Information System (INIS)

    Pimenta, R A; Martins, M J

    2011-01-01

    We study the solutions of the Yang-Baxter equation associated with 19-vertex models invariant by the parity-time symmetry from the perspective of algebraic geometry. We determine the form of the algebraic curves constraining the respective Boltzmann weights and find that they possess a universal structure. This allows us to classify the integrable manifolds into four different families reproducing three known models, besides uncovering a novel 19-vertex model in a unified way. The introduction of the spectral parameter on the weights is made via the parameterization of the fundamental algebraic curve which is a conic. The diagonalization of the transfer matrix of the new vertex model and its thermodynamic limit properties are discussed. We point out a connection between the form of the main curve and the nature of the excitations of the corresponding spin-1 chains.

  17. Gauge dependence of the infrared behaviour of massless QED3

    International Nuclear Information System (INIS)

    Mitra, Indrajit; Ratabole, Raghunath; Sharatchandra, H.S.

    2006-01-01

    Using the Zumino identities it is shown that in a class of non-local gauges, massless QED 3 has an infrared behaviour of a conformal field theory with a continuously varying anomalous dimension of the fermion. In the usual Lorentz gauge, the fermion propagator falls off exponentially for a large separation, but this apparent fermion mass is a gauge artifact

  18. Production of massless bottom jets in p anti p and pp collisions at next-to-leading order of QCD

    Energy Technology Data Exchange (ETDEWEB)

    Bierenbaum, Isabella [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Kramer, Gustav [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2016-03-15

    We present predictions for the inclusive production of bottom jets in proton-antiproton collisions at 1.96 TeV and proton-proton collisions at 7 TeV. The bottom quark is considered massless. In this scheme, we find that at small transverse momentum (p{sub T}) the ratio of the next-to-leading order to the leading-order cross section (K factor) is smaller than one. It increases with increasing p{sub T} and approaches one at larger p{sub T} at a value depending essentially on the choice of the renormalization scale. Adding non-perturbative corrections obtained from PYTHIA Monte Carlo calculations leads to reasonable agreement with experimental b-jet cross sections obtained by the CDF and the CMS collaborations.

  19. Silicon technologies for the CLIC vertex detector

    Science.gov (United States)

    Spannagel, S.

    2017-06-01

    CLIC is a proposed linear e+e- collider designed to provide particle collisions at center-of-mass energies of up to 3 TeV. Precise measurements of the properties of the top quark and the Higgs boson, as well as searches for Beyond the Standard Model physics require a highly performant CLIC detector. In particular the vertex detector must provide a single point resolution of only a few micrometers while not exceeding the envisaged material budget of around 0.2% X0 per layer. Beam-beam interactions and beamstrahlung processes impose an additional requirement on the timestamping capabilities of the vertex detector of about 10 ns. These goals can only be met by using novel techniques in the sensor and ASIC design as well as in the detector construction. The R&D program for the CLIC vertex detector explores various technologies in order to meet these demands. The feasibility of planar sensors with a thickness of 50-150 μm, including different active edge designs, are evaluated using Timepix3 ASICs. First prototypes of the CLICpix readout ASIC, implemented in 65 nm CMOS technology and with a pixel size of 25×25μm 2, have been produced and tested in particle beams. An updated version of the ASIC with a larger pixel matrix and improved precision of the time-over-threshold and time-of-arrival measurements has been submitted. Different hybridization concepts have been developed for the interconnection between the sensor and readout ASIC, ranging from small-pitch bump bonding of planar sensors to capacitive coupling of active HV-CMOS sensors. Detector simulations based on Geant 4 and TCAD are compared with experimental results to assess and optimize the performance of the various designs. This contribution gives an overview of the R&D program undertaken for the CLIC vertex detector and presents performance measurements of the prototype detectors currently under investigation.

  20. Vertex operators and Jordan fields

    International Nuclear Information System (INIS)

    Ferreira, L.A.; Gomes, J.F.; Zimerman, A.H.

    1988-01-01

    The construction of Lie algebras in terms of Jordan algebras generators is discussed. The key to the construction is the triality relation already incorporated into matrix products. A generalisation to Kac-Moody algebras in terms of vertex operators is proposed and may provide a clue for the construction of new representations of Kac-Moody algebras in terms of Jordan fields. (author) [pt

  1. High speed digital TDC for D0 vertex reconstruction

    International Nuclear Information System (INIS)

    Gao Guosheng; Partridge, R.

    1992-01-01

    A high speed digital TDC has been built as part of the Level 0 trigger for the D0 experiment at Fermilab. The digital TDC is used to make a fast determination of the primary vertex position by timing the arrival time of beam jets detected in the Level 0 counters. The vertex position is then used by the Level 1 trigger to determine the proper sinθ weighting factors for calculation transverse energies. Commercial GaAs integrated circuits are used in the digital TDC to obtain a time resolution of σ t == 226 ps

  2. IR finite one-loop box scalar integral with massless internal lines

    International Nuclear Information System (INIS)

    Duplancic, G.; Nizic, B.

    2002-01-01

    The IR finite one-loop box scalar integral with massless internal lines has been recalculated. The result is very compact, simple and valid for arbitrary values of the relevant kinematic variables. It is given in terms of only two dilogarithms and a few logarithms, all of very simple arguments. (orig.)

  3. Microscopic models for hadronic form factors and vertex functions

    International Nuclear Information System (INIS)

    Santhanam, I.; Bhatnagar, S.; Mitra, A.N.

    1990-01-01

    We review the status of nucleon (N) and few-nucleon form factors (f.f.'s) from the view-point of a gradual unfolding of successively inner degrees of freedom (d.o.f.) with increase in q 2 . To this end we focus attention on the problem of a microscopic formulation of hadronic vertex functions (v.f.) from the point of view of their key role in understanding the physics of a large variety of few-hadron reactions on the one hand, and their practical usefulness in articulating the internal dynamics of hadron and few-hadron systems on the other hand. The criterion of an integrated view from low-energy spectroscopy to high-q 2 amplitudes is employed to emphasize the desirability of formulations in terms of relativistic dynamical equations based on Lorentz and gauge invariance in preference to phenomenological models, which often require additional assumptions beyond their original premises to extend their applicability domains. In this respect, the practical possibilities of the Bethe-Salpeter equation (BSE) in articulating the necessary dynamical ingredients are emphasized on a two-tier basis, the basis constants (3) being pre-determined from the mass spectral data (1 st stage) in preparation for the construction of the hadron-quark vertex functions (2 nd stage). An explicit construction is outlined for meson-quark and baryon-quark vertex functions as well as of meson-nucleon vertex functions in a stepwise fashion. The role of the latter as basic parameter-free ingredients is discussed for possible use in the more serious treatment in the current literature of quark-meson level (α) and meson-isobar (β) d.o.f. in 2-N and 3-N form factor studies. Since most of these studies are characterized by the use of RGM techniques at the six-quark level, a comparative discussion is also given of several contemporary RGM based models. Finally, the concrete prospects for employing such hardon-quark vertex functions for evaluating pp-bar annihilation amplitudes are briefly indicated

  4. The O(α{sub s}{sup 2}) heavy quark corrections to charged current deep-inelastic scattering at large virtualities

    Energy Technology Data Exchange (ETDEWEB)

    Blümlein, Johannes, E-mail: Johannes.Bluemlein@desy.de [Deutsches Elektronen–Synchrotron, DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Hasselhuhn, Alexander [Deutsches Elektronen–Synchrotron, DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Research Institute for Symbolic Computation (RISC), Johannes Kepler University, Altenbergerstraße 69, A-4040 Linz (Austria); Pfoh, Torsten [Deutsches Elektronen–Synchrotron, DESY, Platanenallee 6, D-15738 Zeuthen (Germany)

    2014-04-15

    We calculate the O(α{sub s}{sup 2}) heavy flavor corrections to charged current deep-inelastic scattering at large scales Q{sup 2}≫m{sup 2}. The contributing Wilson coefficients are given as convolutions between massive operator matrix elements and massless Wilson coefficients. Foregoing results in the literature are extended and corrected. Numerical results are presented for the kinematic region of the HERA data.

  5. Interacting massless scalar and source-free electromagnetic fields

    International Nuclear Information System (INIS)

    Ayyangar, B.R.N.; Mohanty, G.

    1985-01-01

    The relativistic field equations for interacting massless attractive scalar and source-free electromagnetic fields in a cylindrically symmetric spacetime of one degree of freedom with reflection symmetry have been reduced to a first order implicit differential equation depending on time which enables one to generate a class of solution to the field equations. The nature of the scalar and electromagnetic fields is discussed. It is shown that the geometry of the spacetime admits of an irrotational stiff fluid distribution without prejudice to the interacting electromagnetic fields. 10 refs. (author)

  6. Asymptotic fermion propagator in massless three-dimensional QED

    International Nuclear Information System (INIS)

    Hand, B.J.

    1993-01-01

    Massless quantum electrodynamics in two spatial and one time dimensions has a logarithmically confining static Coulomb potential, and thus nontrivial infrared behavior. We apply a technique developed for ordinary four-dimensional quantum electrodynamics in which the charged asymptotic states in the theory are dressed with soft vector bosons, in order to improve the representation of the infrared dynamics in perturbation theory. The resulting modification to the mass-shell behavior of the fermion propagator is determined, with the result that the propagator no longer possesses a mass-shell singularity

  7. N-point g-loop vertex for free bosonic theory with vacuum charge Q

    International Nuclear Information System (INIS)

    Di Vecchia, P.; Pezzella, F.; Frau, M.; Hornfeck, K.

    1988-12-01

    Starting from the N-Point Vertex on the sphere and using the sewing procedure we construct the N-Point g-Loop Vertex for a free bosonic theory with vacuum charge Q. We then show that, when this vertex is saturated with N highest weight states, it gives their correlation function on an arbitrary Riemann surface of genus g. We also extend our formalism to the case of a free scalar field compactified on a circle, which is related to the Coulomb gas description of minimal models. (orig.)

  8. A momentum space analysis of the Triple Pomeron Vertex in pQCD

    International Nuclear Information System (INIS)

    Bartels, J.

    2007-10-01

    We study properties of the momentum space Triple Pomeron Vertex in perturbative QCD. Particular attention is given to the collinear limit where transverse momenta on one side of the vertex are much larger than on the other side. We also comment on the kernels in nonlinear evolution equations. (orig.)

  9. A momentum space analysis of the Triple Pomeron Vertex in pQCD

    Energy Technology Data Exchange (ETDEWEB)

    Bartels, J. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Kutak, K. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[Instytut Fizyki Jadrowej Polskiej Akademii Nauk, Krakow (Poland)

    2007-10-15

    We study properties of the momentum space Triple Pomeron Vertex in perturbative QCD. Particular attention is given to the collinear limit where transverse momenta on one side of the vertex are much larger than on the other side. We also comment on the kernels in nonlinear evolution equations. (orig.)

  10. Partially massless higher-spin theory II: one-loop effective actions

    Energy Technology Data Exchange (ETDEWEB)

    Brust, Christopher [Perimeter Institute for Theoretical Physics,31 Caroline St. N, Waterloo, Ontario, N2L 2Y5 (Canada); Hinterbichler, Kurt [CERCA, Department of Physics, Case Western Reserve University,10900 Euclid Ave, Cleveland, OH, 44106 (United States)

    2017-01-30

    We continue our study of a generalization of the D-dimensional linearized Vasiliev higher-spin equations to include a tower of partially massless (PM) fields. We compute one-loop effective actions by evaluating zeta functions for both the “minimal” and “non-minimal” parity-even versions of the theory. Specifically, we compute the log-divergent part of the effective action in odd-dimensional Euclidean AdS spaces for D=7 through 19 (dual to the a-type conformal anomaly of the dual boundary theory), and the finite part of the effective action in even-dimensional Euclidean AdS spaces for D=4 through 8 (dual to the free energy on a sphere of the dual boundary theory). We pay special attention to the case D=4, where module mixings occur in the dual field theory and subtlety arises in the one-loop computation. The results provide evidence that the theory is UV complete and one-loop exact, and we conjecture and provide evidence for a map between the inverse Newton’s constant of the partially massless higher-spin theory and the number of colors in the dual CFT.

  11. Partially massless higher-spin theory II: one-loop effective actions

    International Nuclear Information System (INIS)

    Brust, Christopher; Hinterbichler, Kurt

    2017-01-01

    We continue our study of a generalization of the D-dimensional linearized Vasiliev higher-spin equations to include a tower of partially massless (PM) fields. We compute one-loop effective actions by evaluating zeta functions for both the “minimal” and “non-minimal” parity-even versions of the theory. Specifically, we compute the log-divergent part of the effective action in odd-dimensional Euclidean AdS spaces for D=7 through 19 (dual to the a-type conformal anomaly of the dual boundary theory), and the finite part of the effective action in even-dimensional Euclidean AdS spaces for D=4 through 8 (dual to the free energy on a sphere of the dual boundary theory). We pay special attention to the case D=4, where module mixings occur in the dual field theory and subtlety arises in the one-loop computation. The results provide evidence that the theory is UV complete and one-loop exact, and we conjecture and provide evidence for a map between the inverse Newton’s constant of the partially massless higher-spin theory and the number of colors in the dual CFT.

  12. Track and vertex reconstruction: From classical to adaptive methods

    International Nuclear Information System (INIS)

    Strandlie, Are; Fruehwirth, Rudolf

    2010-01-01

    This paper reviews classical and adaptive methods of track and vertex reconstruction in particle physics experiments. Adaptive methods have been developed to meet the experimental challenges at high-energy colliders, in particular, the CERN Large Hadron Collider. They can be characterized by the obliteration of the traditional boundaries between pattern recognition and statistical estimation, by the competition between different hypotheses about what constitutes a track or a vertex, and by a high level of flexibility and robustness achieved with a minimum of assumptions about the data. The theoretical background of some of the adaptive methods is described, and it is shown that there is a close connection between the two main branches of adaptive methods: neural networks and deformable templates, on the one hand, and robust stochastic filters with annealing, on the other hand. As both classical and adaptive methods of track and vertex reconstruction presuppose precise knowledge of the positions of the sensitive detector elements, the paper includes an overview of detector alignment methods and a survey of the alignment strategies employed by past and current experiments.

  13. The Belle II Silicon Vertex Detector

    Energy Technology Data Exchange (ETDEWEB)

    Friedl, M., E-mail: markus.friedl@oeaw.ac.at [HEPHY – Institute of High Energy Physics, Nikolsdorfer Gasse 18, 1050 Vienna (Austria); Ackermann, K. [MPI Munich, Föhringer Ring 6, 80805 München (Germany); Aihara, H. [University of Tokyo, Department of Physics, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Aziz, T. [Tata Institute of Fundamental Research, Experimental High Energy Physics Group, Homi Bhabha Road, Mumbai 400 005 (India); Bergauer, T. [HEPHY – Institute of High Energy Physics, Nikolsdorfer Gasse 18, 1050 Vienna (Austria); Bozek, A. [Institute of Nuclear Physics, Division of Particle Physics and Astrophysics, ul. Radzikowskiego 152, 31 342 Krakow (Poland); Campbell, A. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Dingfelder, J. [University of Bonn, Department of Physics and Astronomy, Nussallee 12, 53115 Bonn (Germany); Drasal, Z. [Charles University, Institute of Particle and Nuclear Physics, Ke Karlovu 3, 121 16 Praha 2 (Czech Republic); Frankenberger, A. [HEPHY – Institute of High Energy Physics, Nikolsdorfer Gasse 18, 1050 Vienna (Austria); Gadow, K. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Gfall, I. [HEPHY – Institute of High Energy Physics, Nikolsdorfer Gasse 18, 1050 Vienna (Austria); Haba, J.; Hara, K.; Hara, T. [KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Higuchi, T. [University of Tokyo, Kavli Institute for Physics and Mathematics of the Universe, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Himori, S. [Tohoku University, Department of Physics, Aoba Aramaki Aoba-ku, Sendai 980-8578 (Japan); Irmler, C. [HEPHY – Institute of High Energy Physics, Nikolsdorfer Gasse 18, 1050 Vienna (Austria); Ishikawa, A. [Tohoku University, Department of Physics, Aoba Aramaki Aoba-ku, Sendai 980-8578 (Japan); Joo, C. [Seoul National University, High Energy Physics Laboratory, 25-107 Shinlim-dong, Kwanak-gu, Seoul 151-742 (Korea, Republic of); and others

    2013-12-21

    The KEKB machine and the Belle experiment in Tsukuba (Japan) are now undergoing an upgrade, leading to an ultimate luminosity of 8×10{sup 35}cm{sup −2}s{sup −1} in order to measure rare decays in the B system with high statistics. The previous vertex detector cannot cope with this 40-fold increase of luminosity and thus needs to be replaced. Belle II will be equipped with a two-layer Pixel Detector surrounding the beam pipe, and four layers of double-sided silicon strip sensors at higher radii than the old detector. The Silicon Vertex Detector (SVD) will have a total sensitive area of 1.13m{sup 2} and 223,744 channels—twice as many as its predecessor. All silicon sensors will be made from 150 mm wafers in order to maximize their size and thus to reduce the relative contribution of the support structure. The forward part has slanted sensors of trapezoidal shape to improve the measurement precision and to minimize the amount of material as seen by particles from the vertex. Fast-shaping front-end amplifiers will be used in conjunction with an online hit time reconstruction algorithm in order to reduce the occupancy to the level of a few percent at most. A novel “Origami” chip-on-sensor scheme is used to minimize both the distance between strips and amplifier (thus reducing the electronic noise) as well as the overall material budget. This report gives an overview on the status of the Belle II SVD and its components, including sensors, front-end detector ladders, mechanics, cooling and the readout electronics.

  14. The Belle II Silicon Vertex Detector

    International Nuclear Information System (INIS)

    Friedl, M.; Ackermann, K.; Aihara, H.; Aziz, T.; Bergauer, T.; Bozek, A.; Campbell, A.; Dingfelder, J.; Drasal, Z.; Frankenberger, A.; Gadow, K.; Gfall, I.; Haba, J.; Hara, K.; Hara, T.; Higuchi, T.; Himori, S.; Irmler, C.; Ishikawa, A.; Joo, C.

    2013-01-01

    The KEKB machine and the Belle experiment in Tsukuba (Japan) are now undergoing an upgrade, leading to an ultimate luminosity of 8×10 35 cm −2 s −1 in order to measure rare decays in the B system with high statistics. The previous vertex detector cannot cope with this 40-fold increase of luminosity and thus needs to be replaced. Belle II will be equipped with a two-layer Pixel Detector surrounding the beam pipe, and four layers of double-sided silicon strip sensors at higher radii than the old detector. The Silicon Vertex Detector (SVD) will have a total sensitive area of 1.13m 2 and 223,744 channels—twice as many as its predecessor. All silicon sensors will be made from 150 mm wafers in order to maximize their size and thus to reduce the relative contribution of the support structure. The forward part has slanted sensors of trapezoidal shape to improve the measurement precision and to minimize the amount of material as seen by particles from the vertex. Fast-shaping front-end amplifiers will be used in conjunction with an online hit time reconstruction algorithm in order to reduce the occupancy to the level of a few percent at most. A novel “Origami” chip-on-sensor scheme is used to minimize both the distance between strips and amplifier (thus reducing the electronic noise) as well as the overall material budget. This report gives an overview on the status of the Belle II SVD and its components, including sensors, front-end detector ladders, mechanics, cooling and the readout electronics

  15. A Vertex and Tracking Detector System for CLIC

    CERN Document Server

    AUTHOR|(SzGeCERN)718101

    2017-01-01

    The physics aims at the proposed future CLIC high-energy linear $e^+e^−$ collider pose challenging demands on the performance of the detector system. In particular the vertex and tracking detectors have to combine precision measurements with robustness against the expected high rates of beam-induced backgrounds. The requirements include ultra-low mass, facilitated by power pulsing and air cooling in the vertex-detector region, small cell sizes and precision hit timing at the few-ns level. A detector concept meeting these requirements has been developed and an integrated R&D program addressing the challenges is progressing in the areas of ultra-thin sensors and readout ASICs, interconnect technology, mechanical integration and cooling.

  16. Gauge-invariant dressed fermion propagator in massless QED{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Mitra, Indrajit [Theory Group, Saha Institute of Nuclear Physics, 1/AF Bidhan-Nagar, Kolkata 700064 (India)]. E-mail: indrajit.mitra@saha.ac.in; Ratabole, Raghunath [Institute of Mathematical Sciences, C.I.T. Campus, Taramani P.O., Chennai 600113 (India)]. E-mail: raghu@imsc.res.in; Sharatchandra, H.S. [Institute of Mathematical Sciences, C.I.T. Campus, Taramani P.O., Chennai 600113 (India)]. E-mail: sharat@imsc.res.in

    2006-04-27

    The infrared behaviour of the gauge-invariant dressed fermion propagator in massless QED{sub 3} is discussed for three choices of dressing. It is found that only the propagator with the isotropic (in three Euclidean dimensions) choice of dressing is acceptable as the physical fermion propagator. It is explained that the negative anomalous dimension of this physical fermion does not contradict any field-theoretical requirement.

  17. The CDF Silicon Vertex Detector

    International Nuclear Information System (INIS)

    Tkaczyk, S.; Carter, H.; Flaugher, B.

    1993-01-01

    A silicon strip vertex detector was designed, constructed and commissioned at the CDF experiment at the Tevatron collider at Fermilab. The mechanical design of the detector, its cooling and monitoring are presented. The front end electronics employing a custom VLSI chip, the readout electronics and various components of the SVX system are described. The system performance and the experience with the operation of the

  18. No nonminimally coupled massless scalar hair for spherically symmetric neutral black holes

    Directory of Open Access Journals (Sweden)

    Shahar Hod

    2017-08-01

    Full Text Available We provide a remarkably compact proof that spherically symmetric neutral black holes cannot support static nonminimally coupled massless scalar fields. The theorem is based on causality restrictions imposed on the energy-momentum tensor of the fields near the regular black-hole horizon.

  19. SUL(3)xUX(1)-invariant description of the bilepton contribution to the WWV vertex in the minimal 331 model

    International Nuclear Information System (INIS)

    Montano, J.; Tavares-Velasco, G.; Toscano, J.J.; Ramirez-Zavaleta, F.

    2005-01-01

    We study the one-loop sensitivity of the WWV (V=γ,Z) vertex to the new massive gauge bosons predicted by the minimal SU L (3)xU X (1) model, which have unusual couplings to the standard model (SM) gauge bosons. A gauge-fixing procedure covariant under the SU L (2)xU Y (1) group was introduced for these new gauge bosons (dubbed bileptons) in order to generate gauge-invariant Green functions. The similarities between this procedure and the unconventional quantization scheme of the background field method are discussed. It is found that, for relatively light bileptons, with a mass ranging from 2m W to 6m W , the radiative corrections to the form factors associated with the WWV vertex can be of the same order of magnitude than the SM one. In the case of heavier bileptons, their contribution is smaller by about one and 2 orders of magnitude than their SM counterpart

  20. LHCb Vertex Locator Upgrade Work Report

    CERN Document Server

    Estrada, Michael

    2017-01-01

    As the LHCb prepares for the planned upgrade of its vertex locator, there is a great need for supporting work such as the design and testing of apparatus that will ensure the smooth implementation of new hardware and infrastructure. My work this summer consisted largely of tasks to support this process.

  1. Higher order corrections to energy levels of muonic atoms

    International Nuclear Information System (INIS)

    Rinker, G.A. Jr.; Steffen, R.M.

    1975-08-01

    In order to facilitate the analysis of muonic x-ray spectra, the results of numerical computations of all higher order quantum electrodynamical corrections to the energy levels of muonic atoms are presented in tabular and graphical form. These corrections include the vacuum polarization corrections caused by emission and reabsorption of virtual electron pairs to all orders, including ''double-bubble'' and ''cracked-egg'' diagrams. An estimate of the Delbruecke scattering-type correction is presented. The Lamb-shift (second- and fourth-order vertex) corrections have been calculated including the correction for the anomalous magnetic moment of the muon. The relativistic nuclear motion (or recoil) correction as well as the correction caused by the screening of the atomic electrons is presented in graphs. For the sake of completeness a graph of the nuclear polarization as computed on the basis of Chen's approach has been included. All calculations were made with a two-parameter Fermi distribution of the nuclear charge density. 7 figures, 23 references

  2. Colour-independent partition functions in coloured vertex models

    Energy Technology Data Exchange (ETDEWEB)

    Foda, O., E-mail: omar.foda@unimelb.edu.au [Dept. of Mathematics and Statistics, University of Melbourne, Parkville, VIC 3010 (Australia); Wheeler, M., E-mail: mwheeler@lpthe.jussieu.fr [Laboratoire de Physique Théorique et Hautes Energies, CNRS UMR 7589 (France); Université Pierre et Marie Curie – Paris 6, 4 place Jussieu, 75252 Paris cedex 05 (France)

    2013-06-11

    We study lattice configurations related to S{sub n}, the scalar product of an off-shell state and an on-shell state in rational A{sub n} integrable vertex models, n∈{1,2}. The lattice lines are colourless and oriented. The state variables are n conserved colours that flow along the line orientations, but do not necessarily cover every bond in the lattice. Choosing boundary conditions such that the positions where the colours flow into the lattice are fixed, and where they flow out are summed over, we show that the partition functions of these configurations, with these boundary conditions, are n-independent. Our results extend to trigonometric A{sub n} models, and to all n. This n-independence explains, in vertex-model terms, results from recent studies of S{sub 2} (Caetano and Vieira, 2012, [1], Wheeler, (arXiv:1204.2089), [2]). Namely, 1.S{sub 2}, which depends on two sets of Bethe roots, {b_1} and {b_2}, and cannot (as far as we know) be expressed in single determinant form, degenerates in the limit {b_1}→∞, and/or {b_2}→∞, into a product of determinants, 2. Each of the latter determinants is an A{sub 1} vertex-model partition function.

  3. Colour-independent partition functions in coloured vertex models

    International Nuclear Information System (INIS)

    Foda, O.; Wheeler, M.

    2013-01-01

    We study lattice configurations related to S n , the scalar product of an off-shell state and an on-shell state in rational A n integrable vertex models, n∈{1,2}. The lattice lines are colourless and oriented. The state variables are n conserved colours that flow along the line orientations, but do not necessarily cover every bond in the lattice. Choosing boundary conditions such that the positions where the colours flow into the lattice are fixed, and where they flow out are summed over, we show that the partition functions of these configurations, with these boundary conditions, are n-independent. Our results extend to trigonometric A n models, and to all n. This n-independence explains, in vertex-model terms, results from recent studies of S 2 (Caetano and Vieira, 2012, [1], Wheeler, (arXiv:1204.2089), [2]). Namely, 1.S 2 , which depends on two sets of Bethe roots, {b 1 } and {b 2 }, and cannot (as far as we know) be expressed in single determinant form, degenerates in the limit {b 1 }→∞, and/or {b 2 }→∞, into a product of determinants, 2. Each of the latter determinants is an A 1 vertex-model partition function

  4. Leading quantum gravitational corrections to scalar QED

    International Nuclear Information System (INIS)

    Bjerrum-Bohr, N.E.J.

    2002-01-01

    We consider the leading post-Newtonian and quantum corrections to the non-relativistic scattering amplitude of charged scalars in the combined theory of general relativity and scalar QED. The combined theory is treated as an effective field theory. This allows for a consistent quantization of the gravitational field. The appropriate vertex rules are extracted from the action, and the non-analytic contributions to the 1-loop scattering matrix are calculated in the non-relativistic limit. The non-analytical parts of the scattering amplitude, which are known to give the long range, low energy, leading quantum corrections, are used to construct the leading post-Newtonian and quantum corrections to the two-particle non-relativistic scattering matrix potential for two charged scalars. The result is discussed in relation to experimental verifications

  5. Preliminary studies for the LHCb vertex detector vacuum system

    CERN Document Server

    Doets, M; Van Bakel, N; Van den Brand, J F J; van den Brand, Jo

    2000-01-01

    We lay down some general considerations which will serve as a starting point for design studies of a realistic LHCb vertex detector vacuum system. Based on these considerations, we propose a design strategy and identify issues to be further studied. In particular we try to outline some boundary conditions imposed by LHC and LHCb on the vacuum system. We discuss two possibilities for the LHCb vertex detector vacuum system. The preferred strategy uses a differentially pumped vacuum system with the silicon detectors separated from the beam line vacuum. Some estimations on static vacuum pressures and gas flows are presented.

  6. Electromagnetic form factors and vertex constants for 6Li

    International Nuclear Information System (INIS)

    Blokhintsev, L.D.; Shvarts, I.A.

    1977-01-01

    It has been assumed that the main contribution to the rapidly changing part of the charge form factor of 6 Li provides the amplitude of the triangle diagram containing virtual lines of deuteron and α particle. The vertex constant G 2 for the 6 Li→α+d decay is expressed through the nuclear charge radii for 6 Li, d, and α. Taking into account coulomb interaction in the vertex of the 6 Li→α+d reaction increases G 2 by about a factor of two. The account of virtuality of a deuteron cluster also leads to an increase in G 2

  7. Mirror of the refined topological vertex from a matrix model

    CERN Document Server

    Eynard, B

    2011-01-01

    We find an explicit matrix model computing the refined topological vertex, starting from its representation in terms of plane partitions. We then find the spectral curve of that matrix model, and thus the mirror symmetry of the refined vertex. With the same method we also find a matrix model for the strip geometry, and we find its mirror curve. The fact that there is a matrix model shows that the refined topological string amplitudes also satisfy the remodeling the B-model construction.

  8. The Color Antisymmetric Ghost Propagator and One-Loop Vertex Renormalization

    OpenAIRE

    Furui, Sadataka

    2007-01-01

    The color matrix elements of the ghost triangle diagram that appears in the triple gluon vertex and the ghost-ghost-gluon triangle diagram that appears in the ghost-gluon-ghost vertex are calculated. The ghost-ghost-gluon triangle contains a loop consisting of two color diagonal ghosts and one gluon and a loop consisting of two color antisymmetric ghosts and one gluon. Consequently, the pQCD argument in the infrared region based on the one particle irreducible diagram should be modified. Impl...

  9. Lifetime tests for MAC vertex chamber

    International Nuclear Information System (INIS)

    Nelson, H.N.

    1986-07-01

    A vertex chamber for MAC was proposed to increase precision in the measurement of the B hadron and tau lepton lifetimes. Thin-walled aluminized mylar drift tubes were used for detector elements. A study of radiation hardness was conducted under the conditions of the proposed design using different gases and different operating conditions

  10. Cosmic ray test of the Belle II z-vertex trigger

    Energy Technology Data Exchange (ETDEWEB)

    Neuhaus, Sara; Skambraks, Sebastian [Technische Universitaet Muenchen (Germany); Chen, Yang; Kiesling, Christian [Max-Planck-Institut fuer Physik, Muenchen (Germany)

    2016-07-01

    The z-vertex trigger is part of the first level track trigger in the Belle II experiment. Its task is the rejection of tracks not coming from the interaction region, suppressing a large part of the machine background. Therefore the z-vertex trigger allows to relax other track trigger conditions and thus strongly increases the efficiency for channels with low track multiplicity (e.g. tau pair production). The track trigger works in several steps, first combining hits to track segments, followed by a 2D track finding in the transverse plane and finally the 3D reconstruction. Our method employs neural networks to estimate the z-vertex without explicit track reconstruction. For the first real test with cosmic rays special neural networks have been prepared. Although the track shape in the cosmic test is different than in the Belle II experiment, the neural networks require only a retraining with an appropriate data set to adapt to the new geometry.

  11. Casimir energy of massless fermions in the Slab-bag

    International Nuclear Information System (INIS)

    Paola, R.D.M. de; Rodrigues, R.B.; Svaiter, N.F.

    1999-04-01

    The zero-point energy of a massless fermion field in the interior of two parallel plates in a D-dimensional space-time at zero temperature is calculated. In order to regularize the model, a mix between dimensional and zeta function regularization procedure is used and it is founded that the regularized zero-point energy density is finite for any number of space-time dimensions. We present a general expression for the Casimir energy for the fermionic field in such a situation. (author)

  12. On the conformal transformations in the massless Thirring model

    International Nuclear Information System (INIS)

    Hadjiivanov, L.K.; Mikhov, S.G.; Stoyanov, D.T.

    1977-01-01

    On the basis of solutions for the massless scalar field in the two dimensional space-time the fields satisfying the renormalized Thirring equation are constructed. Both infinitesimal and global transformations with respect to the two-dimensional conformal group for these fields are obtained. The latter do not coincide with the standard ones. The renormalized Thirring equation is proved to be covariant under infinitesimal conformal group transformations as well as under the global transformations belonging to the universal covering of the conformal group

  13. Massless fields in curved space-time: The conformal formalism

    International Nuclear Information System (INIS)

    Castagnino, M.A.; Sztrajman, J.B.

    1986-01-01

    A conformally invariant theory for massless quantum fields in curved space-time is formulated. We analyze the cases of spin-0, - 1/2 , and -1. The theory is developed in the important case of an ''expanding universe,'' generalizing the particle model of ''conformal transplantation'' known for spin-0 to spins- 1/2 and -1. For the spin-1 case two methods introducing new conformally invariant gauge conditions are stated, and a problem of inconsistency that was stated for spin-1 is overcome

  14. The OPAL vertex drift chamber

    International Nuclear Information System (INIS)

    Carter, J.R.; Elcombe, P.A.; Hill, J.C.; Roach, C.M.; Armitage, J.C.; Carnegie, R.K.; Estabrooks, P.; Hemingway, R.; Karlen, D.; McPherson, A.; Pinfold, J.; Roney, J.M.; Routenburg, P.; Waterhouse, J.; Hargrove, C.K.; Klem, D.; Oakham, F.G.; Carter, A.A.; Jones, R.W.L.; Lasota, M.M.B.; Lloyd, S.L.; Pritchard, T.W.; Wyatt, T.R.

    1990-01-01

    A high precision vertex drift chamber has been installed in the OPAL experiment at LEP. The design of the chamber and the associated readout electronics is described. The performance of the system has been studied using cosmic ray muons and the results of these studies are presented. A space resolution of 50 μm in the drift direction is obtained using the OPAL central detector gas mixture at 4 bar. (orig.)

  15. Massless phases and confinement in extended Z(4) gauge theories

    International Nuclear Information System (INIS)

    Alcaraz, F.C.; Jacobs, L.

    1983-01-01

    We analyze a general Z(4) lattice gauge theory in four dimensions. The two-parameter model is shown to possess four distinct phases characterized by the behavior of Wilson loops carrying one or two units of flux. The appearance of a bifurcation in the phase plane just below the Wilson action is conjectured to be the precursor of the massless electrodynamicslike phase seen in the larger-N models

  16. Leading quantum gravitational corrections to scalar QED

    OpenAIRE

    Bjerrum-Bohr, N. E. J.

    2002-01-01

    We consider the leading post-Newtonian and quantum corrections to the non-relativistic scattering amplitude of charged scalars in the combined theory of general relativity and scalar QED. The combined theory is treated as an effective field theory. This allows for a consistent quantization of the gravitational field. The appropriate vertex rules are extracted from the action, and the non-analytic contributions to the 1-loop scattering matrix are calculated in the non-relativistic limit. The n...

  17. A vertex including emission of spin fields for an arbitrary bc system

    International Nuclear Information System (INIS)

    Di Vecchia, P.; Madsen, R.A.; Roland, K.

    1990-01-01

    We construct the (N+2M) Point Vertex involving the emission of N Neveu-Schwarz and 2M Ramond states for a bosonic and fermionic bc system with a bockground charge Q. From it one can compute correlation functions on the sphere involving any number of spin fields. We show in detail that the vertex satisfies overlap conditions. (orig.)

  18. Simulations of silicon vertex tracker for star experiment at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Odyniec, G.; Cebra, D.; Christie, W.; Naudet, C.; Schroeder, L.; Wilson, W. [Lawrence Berkeley Lab., CA (United States); Liko, D. [Institut fur Hochenenergiephysik, Vienna, (Austria); Cramer, J.; Prindle, D.; Trainor, T. [Univ. of Washington, Seattle (United States); Braithwaite, W. [Univ. of Arkansas, Little Rock (United States)

    1991-12-31

    The first computer simulations to optimize the Silicon Vertex Tracker (SVT) designed for the STAR experiment at RHIC are presented. The physics goals and the expected complexity of the events at RHIC dictate the design of a tracking system for the STAR experiment. The proposed tracking system will consist of a silicon vertex tracker (SVT) to locate the primary interaction and secondary decay vertices and to improve the momentum resolution, and a time projection chamber (TPC), positioned inside a solenoidal magnet, for continuous tracking.

  19. Subsubleading soft theorems of gravitons and dilatons in the bosonic string

    International Nuclear Information System (INIS)

    Vecchia, Paolo Di; Marotta, Raffaele; Mojaza, Matin

    2016-01-01

    Starting from the amplitude with an arbitrary number of massless closed states of the bosonic string, we compute the soft limit when one of the states becomes soft to subsubleading order in the soft momentum expansion, and we show that when the soft state is a graviton or a dilaton, the full string amplitude can be expressed as a soft theorem through subsubleading order. It turns out that there are string corrections to the field theoretical limit in the case of a soft graviton, while for a soft dilaton the string corrections vanish. We then show that the new soft theorems, including the string corrections, can be simply obtained from the exchange diagrams where the soft state is attached to the other external states through the three-point string vertex of three massless states. In the soft-limit, the propagator of the exchanged state is divergent, and at tree-level these are the only divergent contributions to the full amplitude. However, they do not form a gauge invariant subset and must be supplemented with extra non-singular terms. The requirement of gauge invariance then fixes the complete amplitude through subsubleading order in the soft expansion, reproducing exactly what one gets from the explicit calculation in string theory. From this it is seen that the string corrections at subsubleading order arise as a consequence of the three-point amplitude having string corrections in the bosonic string. When specialized to a soft dilaton, it remarkably turns out that the string corrections vanish and that the non-singular piece of the subsubleading term of the dilaton soft theorem is the generator of space-time special conformal transformation.

  20. The silicon vertex locator for the LHCb upgrade

    CERN Document Server

    Head, Tim

    2014-01-01

    The upgrade of the LHCb experiment, planned for 2018, will transform the entire readout to a triggerless system being read out at 40 MHz. The upgraded silicon vertex detector (VELO) must be light weight, radiation hard, and compatible with LHC vacuum requirements. It must be capable of fast pattern recognition, fast track reconstruction and high precision vertexing. This challenge is being met with a new VELO design based on hybrid pixel detectors positioned to within 5 mm of the LHC colliding beams. The detector will be shielded from the beam by a View the MathML source~300μm thick aluminium foil. Evaporative CO2 coolant circulating in micro-channels embedded in a thin silicon substrate will be used for cooling.

  1. Vertex models, TASEP and Grothendieck polynomials

    International Nuclear Information System (INIS)

    Motegi, Kohei; Sakai, Kazumitsu

    2013-01-01

    We examine the wavefunctions and their scalar products of a one-parameter family of integrable five-vertex models. At a special point of the parameter, the model investigated is related to an irreversible interacting stochastic particle system—the so-called totally asymmetric simple exclusion process (TASEP). By combining the quantum inverse scattering method with a matrix product representation of the wavefunctions, the on-/off-shell wavefunctions of the five-vertex models are represented as a certain determinant form. Up to some normalization factors, we find that the wavefunctions are given by Grothendieck polynomials, which are a one-parameter deformation of Schur polynomials. Introducing a dual version of the Grothendieck polynomials, and utilizing the determinant representation for the scalar products of the wavefunctions, we derive a generalized Cauchy identity satisfied by the Grothendieck polynomials and their duals. Several representation theoretical formulae for the Grothendieck polynomials are also presented. As a byproduct, the relaxation dynamics such as Green functions for the periodic TASEP are found to be described in terms of the Grothendieck polynomials. (paper)

  2. Twisted Frobenius Identities from Vertex Operator Superalgebras

    Directory of Open Access Journals (Sweden)

    Alexander Zuevsky

    2017-01-01

    Full Text Available In consideration of the continuous orbifold partition function and a generating function for all n-point correlation functions for the rank two free fermion vertex operator superalgebra on the self-sewing torus, we introduce the twisted version of Frobenius identity.

  3. Modeling & Informatics at Vertex Pharmaceuticals Incorporated: our philosophy for sustained impact.

    Science.gov (United States)

    McGaughey, Georgia; Patrick Walters, W

    2017-03-01

    Molecular modelers and informaticians have the unique opportunity to integrate cross-functional data using a myriad of tools, methods and visuals to generate information. Using their drug discovery expertise, information is transformed to knowledge that impacts drug discovery. These insights are often times formulated locally and then applied more broadly, which influence the discovery of new medicines. This is particularly true in an organization where the members are exposed to projects throughout an organization, such as in the case of the global Modeling & Informatics group at Vertex Pharmaceuticals. From its inception, Vertex has been a leader in the development and use of computational methods for drug discovery. In this paper, we describe the Modeling & Informatics group at Vertex and the underlying philosophy, which has driven this team to sustain impact on the discovery of first-in-class transformative medicines.

  4. First-order corrections to random-phase approximation GW calculations in silicon and diamond

    NARCIS (Netherlands)

    Ummels, R.T.M.; Bobbert, P.A.; van Haeringen, W.

    1998-01-01

    We report on ab initio calculations of the first-order corrections in the screened interaction W to the random-phase approximation polarizability and to the GW self-energy, using a noninteracting Green's function, for silicon and diamond. It is found that the first-order vertex and self-consistency

  5. Charged Particle Tracking and Vertex Detection Group summary report

    International Nuclear Information System (INIS)

    Hanson, G.; Meyer, D.

    1984-09-01

    Charged particle tracking is essential in order to investigate the new physics expected at the SSC. The Tracking Group studied radiation damage and rate limitations to tracking devices, vertex detectors, and central tracking. The Group concluded that silicon strips and large wire tracking chambers with small cells can probably survive at the design luminosity of 10 33 cm -2 sec -1 ; however, the presently designed electronics for silicon strip vertex detectors can withstand a luminosity of only 10 31 cm -2 sec -1 . Wire chambers at a radius of less than about 25 cm can withstand a luminosity of less than or equal to 10 32 cm -2 sec -1 only. Actual tracking and pattern recognition in central tracking chambers at a luminosity of 10 33 cm -2 sec -1 will be very difficult because of multiple interactions within the resolving time of the chambers; detailed simulations are needed in order to decide whether tracking is indeed possible at this luminosity. Scintillating glass fibers are an interesting possibility both for vertex detectors and for central trackers, but much research and development is still needed both on the fibers themselves and on the readout

  6. Evidence of ghost suppression in gluon mass scale dynamics

    Science.gov (United States)

    Aguilar, A. C.; Binosi, D.; Figueiredo, C. T.; Papavassiliou, J.

    2018-03-01

    In this work we study the impact that the ghost sector of pure Yang-Mills theories may have on the generation of a dynamical gauge boson mass scale, which hinges on the appearance of massless poles in the fundamental vertices of the theory, and the subsequent realization of the well-known Schwinger mechanism. The process responsible for the formation of such structures is itself dynamical in nature, and is governed by a set of Bethe-Salpeter type of integral equations. While in previous studies the presence of massless poles was assumed to be exclusively associated with the background-gauge three-gluon vertex, in the present analysis we allow them to appear also in the corresponding ghost-gluon vertex. The full analysis of the resulting Bethe-Salpeter system reveals that the contribution of the poles associated with the ghost-gluon vertex are particularly suppressed, their sole discernible effect being a slight modification in the running of the gluon mass scale, for momenta larger than a few GeV. In addition, we examine the behavior of the (background-gauge) ghost-gluon vertex in the limit of vanishing ghost momentum, and derive the corresponding version of Taylor's theorem. These considerations, together with a suitable Ansatz, permit us the full reconstruction of the pole sector of the two vertices involved.

  7. Phase transition for a uniformly frustrated 19-vertex model by use of the density matrix renormalization group

    International Nuclear Information System (INIS)

    Honda, Yasushi; Horiguchi, Tsuyoshi

    2001-01-01

    We investigate a uniformly frustrated 19-vertex model with an anisotropy parameter η by use of the density matrix renormalization group for the transfer matrix for 0.6≤η≤1.3. The scaling dimension x is calculated from eigenvalues of the transfer matrix for several values η. The finite-size scaling analyses with a logarithmic correction are carried out in order to determine transition temperatures. It is found that there are two kinds of phase transitions, although there is a possibility of a single transition. This result is not compatible with the result for the uniformly frustrated XY model

  8. Remarks on the paper ''Two-dimensional quantum field theories involving massless particles'' by N.Nakanishi

    International Nuclear Information System (INIS)

    Stoyanov, D.Ts.

    1978-01-01

    Some critical remarks on the paper by N.Nakanishi ''Tso-Dimensional Quantum Field Theories Involving Massless Particles'' are presented. It is stated that because of the obtained commutation relations the massless scalar fields of the theory connot have the asymptotic behaviour assumed by N.Nakanishi. The contradiction, appearing in the proof of the irreducibility of the scalar field, is demonstrated. Therefore, the theory constructed by Nakanishi, in which an attempt is made to formulate it with the help of one scalar field and correspondingly with one topological charge, is contradictory. It is shown that the statistics of the solutions is not fixed and the solutions satisfying Bose or Fermi statistics differ by constant operator factors

  9. On the exponentiation of leading infrared divergences in massless Yang-Mills theories

    International Nuclear Information System (INIS)

    Frenkel, J.; Garcia, R.L.

    1977-01-01

    We derive, in the axial gauge, the effective U-matrix which governs the behaviour of leading infrared singularities in the self-energy functions of Yang-Mills particles. We then show in a very simple manner, that these divergences, which determine the leading singularities in massless Yang-Mills theories, exponentiate [pt

  10. Massive, massless and ghost modes of gravitational waves from higher-order gravity

    DEFF Research Database (Denmark)

    Bogdanos, Charalampos; Capozziello, Salvatore; De Laurentis, Mariafelicia

    We linearize the field equations for higher order theories that contain scalar invariants other than the Ricci scalar. We find that besides a massless spin-2 field (the standard graviton), the theory contains also spin-0 and spin-2 massive modes with the latter being, in general, ghost modes. Then...

  11. New twistorial integral formulas for massless free fields of arbitrary spin

    International Nuclear Information System (INIS)

    Cardoso, J.G.

    1991-01-01

    A manifestly scaling-invariant version of the Kirchoff-D'Adhemar-Penrose field integrals is presented. The invariant integral expressions for the spinning massless free fields are directly transcribed into the framework of twistor theory. It is then shown that the resulting twistorial field integrals can be thought of as being equivalent to the universal Penrose contour integral formulas for these fields

  12. Gauge dependence of the infrared behaviour of massless QED{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Mitra, Indrajit [Theory Group, Saha Institute of Nuclear Physics, 1/AF Bidhan-Nagar, Kolkata 700064 (India)]. E-mail: indrajit.mitra@saha.ac.in; Ratabole, Raghunath [The Institute of Mathematical Sciences, CIT Campus, Taramani PO, Chennai 600113 (India)]. E-mail: raghu@imsc.res.in; Sharatchandra, H.S. [The Institute of Mathematical Sciences, CIT Campus, Taramani PO, Chennai 600113 (India)]. E-mail: sharat@imsc.res.in

    2006-03-23

    Using the Zumino identities it is shown that in a class of non-local gauges, massless QED{sub 3} has an infrared behaviour of a conformal field theory with a continuously varying anomalous dimension of the fermion. In the usual Lorentz gauge, the fermion propagator falls off exponentially for a large separation, but this apparent fermion mass is a gauge artifact.

  13. Data driven processor 'Vertex Trigger' for B experiments

    International Nuclear Information System (INIS)

    Hartouni, E.P.

    1993-01-01

    Data Driven Processors (DDP's) are specialized computation engines configured to solve specific numerical problems, such as vertex reconstruction. The architecture of the DDP which is the subject of this talk was designed and implemented by W. Sippach and B.C. Knapp at Nevis Lab. in the early 1980's. This particular implementation allows multiple parallel streams of data to provide input to a heterogenous collection of simple operators whose interconnection form an algorithm. The local data flow control allows this device to execute algorithms extremely quickly provided that care is taken in the layout of the algorithm. I/O rates of several hundred megabytes/second are routinely achieved thus making DDP's attractive candidates for complex online calculations. The original question was open-quote can a DDP reconstruct tracks in a Silicon Vertex Detector, find events with a separated vertex and do it fast enough to be used as an online trigger?close-quote Restating this inquiry as three questions and describing the answers to the questions will be the subject of this talk. The three specific questions are: (1) Can an algorithm be found which reconstructs tracks in a planar geometry and no magnetic field; (2) Can separated vertices be recognized in some way; (3) Can the algorithm be implemented in the Nevis-UMass and DDP and execute in 10-20 μs?

  14. Ghost story. II. The midpoint ghost vertex

    International Nuclear Information System (INIS)

    Bonora, L; Maccaferri, C; Scherer Santos, R.J.; Tolla, D D

    2009-01-01

    We construct the ghost number 9 three strings vertex for OSFT in the natural normal ordering. We find two versions, one with a ghost insertion at z = i and a twist-conjugate one with insertion at z = -i. For this reason we call them midpoint vertices. We show that the relevant Neumann matrices commute among themselves and with the matrix G representing the operator K 1 . We analyze the spectrum of the latter and find that beside a continuous spectrum there is a (so far ignored) discrete one. We are able to write spectral formulas for all the Neumann matrices involved and clarify the important role of the integration contour over the continuous spectrum. We then pass to examine the (ghost) wedge states. We compute the discrete and continuous eigenvalues of the corresponding Neumann matrices and show that they satisfy the appropriate recursion relations. Using these results we show that the formulas for our vertices correctly define the star product in that, starting from the data of two ghost number 0 wedge states, they allow us to reconstruct a ghost number 3 state which is the expected wedge state with the ghost insertion at the midpoint, according to the star recursion relation.

  15. Remarks on the Curci-Ferrari Model

    Science.gov (United States)

    Lavrov, Peter M.

    2012-07-01

    We study a dependence of Green's functions for the Curci-Ferrari model on the parameter resembling the gauge parameter in massless Yang-Mills theories. It is shown that the on-shell generating functional of vertex functions (effective action) depends on this parameter.

  16. Gauge-invariant on-shell Z1 in QED and QCD

    International Nuclear Information System (INIS)

    Fleischer, J.; Tarasov, O.V.

    1992-01-01

    Results of the two-loop calculation of the renormalization constant Z 1 for the on-shell fermion-fermion-vector vertex function of a general gauge theory with one massive fermion and the other particles massless are presented. Computations were performed in n dimensions and for an arbitrary covariant gauge. We found Z 1 to be gauge invariant in a renormalization scheme with simultaneous dimensional regularization of ultraviolet and infrared divergences. The charge renormalization constant in this scheme has ultraviolet and infrared divergences. It is found that infrared divergent terms in one- and two-loop approximation are proportional to be appropriate coefficient of the β function determined by ultraviolet divergences of massless particles, i.e. gluons and massless fermions. (orig.)

  17. Gauge-independent bifurcation to the chiral-symmetry-breaking solution of the Dyson-Schwinger equation in continuum QED

    International Nuclear Information System (INIS)

    Rembiesa, P.

    1990-01-01

    The Dyson-Schwinger equation for the fermion propagator can be effectively solved in the approximation of the small-momentum-transfer vertex function. There exists a critical value of the coupling constant above which the ordinary infrared-divergent solution for massless quantum electrodynamics bifurcates to another, massive solution. With a proper transverse part included in the vertex function, the bifurcation point is gauge independent, the new solution is finite in all gauges, and does not require momentum cutoffs of any kind

  18. Involution Requirement on a Boundary Makes Massless Fermions Compactified on a Finite Flat Disk Mass Protected

    Science.gov (United States)

    Mankoč Borštnik, N. S.; Nielsen, H. B.

    2006-12-01

    The genuine Kaluza-Klein-like theories--with no fields in addition to gravity--have difficulties with the existence of massless spinors after the compactification of some space dimensions \\cite{witten}. We proposed (Phys. Lett. B 633 (2006)771) such a boundary condition for spinors in 1+5 compactified on a flat disk that ensures masslessness of spinors in d=1+3 as well as their chiral coupling to the corresponding background gauge field (which solves equations of motion for a free field linear in the Riemann curvature). In this paper we study the same toy model: M^{(1+3)} x M^{(2)}, looking this time for an involution which transforms a space of solutions of Weyl equations in d=1+5 from the outside of the flat disk in x^5 and x^6 into its inside, allowing massless spinor of only one handedness--and accordingly assures mass protection--and of one charge--1/2--and infinitely many massive spinors of the same charge, chirally coupled to the corresponding background gauge field. We reformulate the operator of momentum so that it is Hermitean on the vector space of spinor states obeying the involution boundary condition.

  19. Description of the higher massless irreducible integer spins in the BRST approach

    International Nuclear Information System (INIS)

    Pashnev, A.; Tsulaya, M.

    1998-01-01

    The BRST approach is applied to the description of irreducible massless higher spins representations of the Poincare group in arbitrary dimensions. The total system of constraints in such theory includes both the first and the second class constraints. The corresponding nilpotent BRST charge contains terms up to the seventh degree in ghosts

  20. The performance of diphoton primary vertex reconstruction methods in H → γγ+Met channel of ATLAS experiment

    Science.gov (United States)

    Tomiwa, K. G.

    2017-09-01

    The search for new physics in the H → γγ+met relies on how well the missing transverse energy is reconstructed. The Met algorithm used by the ATLAS experiment in turns uses input variables like photon and jets which depend on the reconstruction of the primary vertex. This document presents the performance of di-photon vertex reconstruction algorithms (hardest vertex method and Neural Network method). Comparing the performance of these algorithms for the nominal Standard Model sample and the Beyond Standard Model sample, we see the overall performance of the Neural Network method of primary vertex selection performed better than the Hardest vertex method.

  1. The Construction of Spin Foam Vertex Amplitudes

    Directory of Open Access Journals (Sweden)

    Eugenio Bianchi

    2013-01-01

    Full Text Available Spin foam vertex amplitudes are the key ingredient of spin foam models for quantum gravity. These fall into the realm of discretized path integral, and can be seen as generalized lattice gauge theories. They can be seen as an attempt at a 4-dimensional generalization of the Ponzano-Regge model for 3d quantum gravity. We motivate and review the construction of the vertex amplitudes of recent spin foam models, giving two different and complementary perspectives of this construction. The first proceeds by extracting geometric configurations from a topological theory of the BF type, and can be seen to be in the tradition of the work of Barrett, Crane, Freidel and Krasnov. The second keeps closer contact to the structure of Loop Quantum Gravity and tries to identify an appropriate set of constraints to define a Lorentz-invariant interaction of its quanta of space. This approach is in the tradition of the work of Smolin, Markopoulous, Engle, Pereira, Rovelli and Livine.

  2. Quantum Vertex Model for Reversible Classical Computing

    Science.gov (United States)

    Chamon, Claudio; Mucciolo, Eduardo; Ruckenstein, Andrei; Yang, Zhicheng

    We present a planar vertex model that encodes the result of a universal reversible classical computation in its ground state. The approach involves Boolean variables (spins) placed on links of a two-dimensional lattice, with vertices representing logic gates. Large short-ranged interactions between at most two spins implement the operation of each gate. The lattice is anisotropic with one direction corresponding to computational time, and with transverse boundaries storing the computation's input and output. The model displays no finite temperature phase transitions, including no glass transitions, independent of circuit. The computational complexity is encoded in the scaling of the relaxation rate into the ground state with the system size. We use thermal annealing and a novel and more efficient heuristic \\x9Dannealing with learning to study various computational problems. To explore faster relaxation routes, we construct an explicit mapping of the vertex model into the Chimera architecture of the D-Wave machine, initiating a novel approach to reversible classical computation based on quantum annealing.

  3. Nonperturbative aspects of the quark-photon vertex

    International Nuclear Information System (INIS)

    Frank, M.R.

    1994-01-01

    The electromagnetic interaction with quarks is investigated through a relativistic, electromagnetic gauge-invariant treatment. Gluon dressing of the quark-photon vertex and the quark self-energy functions is described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger-Dyson equation in the rainbow approximation respectively. Results for the calculation of the quark-photon vertex are presented in both the time-like and space-like regions of photon momentum squared, however emphasis is placed on the space-like region relevant to electron scattering. The treatment presented here simultaneously addresses the role of dynamically generated q bar q vector bound states and the approach to asymptotic behavior. The resulting description is therefore applicable over the entire range of momentum transfers available in electron scattering experiments. Input parameters are limited to the model gluon two-point function which is chosen to reflect confinement and asymptotic freedom and are largely constrained by the obtained bound-state spectrum

  4. Nonperturbative Aspects of Axial Vector Vertex

    Institute of Scientific and Technical Information of China (English)

    ZONG Hong-Shi; CHEN Xiang-Song; WANG Fan; CHANG Chao-Hsi; ZHAO En-Guang

    2002-01-01

    It is shown how the axial vector current of current quarks is related to that of constituent quarks within the framework of the global color symmetry model.Gluon dressing of the axial vector vertex and the quark self-energy functions are described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger Dyson equation in the rainbow approximation,respectively.

  5. Regularization scheme dependence of virtual corrections to DY and DIS

    International Nuclear Information System (INIS)

    Khalafi, F.; Landshoff, P.V.

    1981-01-01

    One loop virtual corrections to the quark photon vertex are calculated under various assumptions and their sensitivity to the manner in which infra-red and mass singularities are regularized is studied. A method based on the use of Mellin-transforms in the Feynman parametric space is developed and shown to be convenient in calculating virtual diagrams beyond the leading logarithm in perturbative QCD. (orig.)

  6. STAR Vertex Detector Upgrade Development

    International Nuclear Information System (INIS)

    Greiner, Leo C.; Matis, Howard S.; Stezelberger, Thorsten; Vu, Chinh Q.; Wieman, Howard; Szelezniak, Michal; Sun, Xiangming

    2008-01-01

    We report on the development and prototyping efforts undertaken with the goal of producing a micro-vertex detector for the STAR experiment at the RHIC accelerator at BNL. We present the basic detector requirements and show a sensor development path, conceptual mechanical design candidates and readout architecture. Prototyping and beam test results with current generation MimoSTAR-2 sensors and a readout system featuring FPGA based on-the-fly hit finding and data sparsification are also presented

  7. Resonant frequencies of massless scalar field in rotating black-brane spacetime

    Institute of Scientific and Technical Information of China (English)

    Jing Ji-Liang; Pan Qi-Yuan

    2008-01-01

    This paper investigates the resonant frequencies of the massless scalar field in the near extremal Kerr-like black-brahe spacetime. It is shown that the different angular quantum number will present different resonant frequencies. It is also shown that the real part of the resonant frequencies increases as the compact dimensions parameter μi increases, but the magnitude of the imaginary part decreases as μi increases.

  8. Production of massless particles in collisions of strings at high energy

    International Nuclear Information System (INIS)

    Lipatov, L.N.

    1988-01-01

    The authors obtain explicit formulas (generalizing the Low-Gribov expressions) for the production amplitude of massless particles (gluons and gravitons) with low transverse momenta in the scattering of lower-mass excitations of open and closed strings. In the limit α' → 0 they reproduce the results of calculation of effective vertices for inelastic scattering amplitudes in multi-Regge kinematics in the Yang-Mills theory and in gravitation

  9. On the bosonization of the massless spinor electrodynamics

    International Nuclear Information System (INIS)

    Mikhov, S.G.; Stoyanov, D.Ts.

    1979-01-01

    A method for constructing a field transformed according to a linear representation of a Lie group out of fields transformed nonlinearly under the action of the same group is proposed. This procedure is used in order to construct spinor fields out of tensor ones. Such a ''bosonization'' of the spinor field is used to reformulate the massless spinor electrodynamics in terms of nonlinear tensor fields. It appears in this formulation that the Dirac equation is reduced to a definition of the electromagnetic vector potential in terms of the nonlinear tensor fields and to the current conservations playing the role of a consistency condition for this formulation

  10. OPAL Central Detector (Including vertex, jet and Z chambers)

    CERN Multimedia

    OPAL was one of the four experiments installed at the LEP particle accelerator from 1989 - 2000. OPAL's central tracking system consists of (in order of increasing radius) a silicon microvertex detector, a vertex detector, a jet chamber, and z-chambers. All the tracking detectors work by observing the ionization of atoms by charged particles passing by: when the atoms are ionized, electrons are knocked out of their atomic orbitals, and are then able to move freely in the detector. These ionization electrons are detected in the different parts of the tracking system. (This piece includes the vertex, jet and Z chambers) In the picture above, the central detector is the piece being removed to the right.

  11. The secondary vertex finding algorithm with the ATLAS detector

    CERN Document Server

    Heer, Sebastian; The ATLAS collaboration

    2017-01-01

    A high performance identification of jets, produced via fragmentation of bottom quarks, is crucial for the ATLAS physics program. These jets can be identified by exploiting the presence of cascade decay vertices from bottom hadrons. A general vertex-finding algorithm is introduced and its ap- plication to the search for secondary vertices inside jets is described. Kinematic properties of the reconstructed vertices are used to construct several b-jet identification algorithms. The features and performance of the secondary vertex finding algorithm in a jet, as well as the performance of the jet tagging algorithms, are studied using simulated $pp$ -> $t\\bar{t}$ events at a centre-of-mass energy of 13 TeV.

  12. Cluster algebras bases on vertex operator algebras

    Czech Academy of Sciences Publication Activity Database

    Zuevsky, Alexander

    2016-01-01

    Roč. 30, 28-29 (2016), č. článku 1640030. ISSN 0217-9792 Institutional support: RVO:67985840 Keywords : cluster alegbras * vertex operator algebras * Riemann surfaces Subject RIV: BA - General Mathematics Impact factor: 0.736, year: 2016 http://www.worldscientific.com/doi/abs/10.1142/S0217979216400300

  13. Radiation corrections to quantum processes in an intense electromagnetic field

    International Nuclear Information System (INIS)

    Narozhny, N.B.

    1979-01-01

    A derivation of an asymptotic expression for the mass correction of order α to the electron propagator in an intense electromagnetic field is presented. It is used for the calculation of radiation corrections to the electron and photon elastic scattering amplitudes in the α 3 approximation. All proper diagrams contributing to the amplitudes and containing the above-mentioned correction to the propagator were considered, but not those which include vertex corrections. It is shown that the expansion parameter of the perturbation theory of quantum electrodynamics in intense fields grows not more slowly than αchi/sup 1/3/ at least for the electron amplitude, where chi = [(eF/sub μν/p/sub ν/) 2 ] 12 /m 3 , p is a momentum of the electron, and F is the electromagnetic field tensor

  14. Domain wall partition function of the eight-vertex model with a non-diagonal reflecting end

    International Nuclear Information System (INIS)

    Yang Wenli; Chen Xi; Feng Jun; Hao Kun; Shi Kangjie; Sun Chengyi; Yang Zhanying; Zhang Yaozhong

    2011-01-01

    With the help of the Drinfeld twist or factorizing F-matrix for the eight-vertex SOS model, we derive the recursion relations of the partition function for the eight-vertex model with a generic non-diagonal reflecting end and domain wall boundary condition. Solving the recursion relations, we obtain the explicit determinant expression of the partition function. Our result shows that, contrary to the eight-vertex model without a reflecting end, the partition function can be expressed as a single determinant.

  15. Law of large numbers for the SIR model with random vertex weights on Erdős-Rényi graph

    Science.gov (United States)

    Xue, Xiaofeng

    2017-11-01

    In this paper we are concerned with the SIR model with random vertex weights on Erdős-Rényi graph G(n , p) . The Erdős-Rényi graph G(n , p) is generated from the complete graph Cn with n vertices through independently deleting each edge with probability (1 - p) . We assign i. i. d. copies of a positive r. v. ρ on each vertex as the vertex weights. For the SIR model, each vertex is in one of the three states 'susceptible', 'infective' and 'removed'. An infective vertex infects a given susceptible neighbor at rate proportional to the production of the weights of these two vertices. An infective vertex becomes removed at a constant rate. A removed vertex will never be infected again. We assume that at t = 0 there is no removed vertex and the number of infective vertices follows a Bernoulli distribution B(n , θ) . Our main result is a law of large numbers of the model. We give two deterministic functions HS(ψt) ,HV(ψt) for t ≥ 0 and show that for any t ≥ 0, HS(ψt) is the limit proportion of susceptible vertices and HV(ψt) is the limit of the mean capability of an infective vertex to infect a given susceptible neighbor at moment t as n grows to infinity.

  16. Unfolded Equations for Current Interactions of 4d Massless Fields as a Free System in Mixed Dimensions

    CERN Document Server

    Gelfond, O A

    2015-01-01

    Interactions of massless fields of all spins in four dimensions with currents of any spin is shown to result from a solution of the linear problem that describes a gluing between rank-one (massless) system and rank-two (current) system in the unfolded dynamics approach. Since the rank-two system is dual to a free rank-one higher-dimensional system, that effectively describes conformal fields in six space-time dimensions, the constructed system can be interpreted as describing a mixture between linear conformal fields in four and six dimensions. Interpretation of the obtained results in spirit of AdS/CFT correspondence is discussed.

  17. Z H η vertex in the simplest little Higgs model

    Science.gov (United States)

    He, Shi-Ping; Mao, Ying-nan; Zhang, Chen; Zhu, Shou-hua

    2018-04-01

    The issue of deriving Z H η vertex in the simplest little Higgs (SLH) model is revisited. Special attention is paid to the treatment of noncanonically-normalized scalar kinetic matrix and vector-scalar two-point transitions. We elucidate a general procedure to diagonalize a general vector-scalar system in gauge theories and apply it to the case of SLH. The resultant Z H η vertex is found to be different from those which have already existed in the literature for a long time. We also present an understanding of this issue from an effective field theory viewpoint.

  18. The color antisymmetric ghost propagator and one-loop vertex renormalization

    International Nuclear Information System (INIS)

    Furui, Sadataka

    2008-01-01

    The color matrix elements of the ghost triangle diagram that appears in the triple gluon vertex and the ghost-ghost-gluon triangle diagram that appears in the ghost-gluon-ghost vertex are calculated. The ghost-ghost-gluon triangle contains a loop consisting of two color diagonal ghosts and one gluon and a loop consisting of two color antisymmetric ghosts and one gluon. Consequently, the pQCD argument in the infrared region based on the one particle irreducible diagram should be modified. Implications for the Kugo-Ojima color confinement and the QCD running coupling are discussed. (author)

  19. arXiv Mapping the material in the LHCb vertex locator using secondary hadronic interactions

    CERN Document Server

    INSPIRE-00160626; Barter, W.; Bay, A.; Bel, L.J.; van Beuzekom, M.; Bogdanova, G.; Borghi, S.; Bowcock, T.J.V.; Buchanan, E.; Buytaert, J.; Carvalho Akiba, K.; Chen, S.; Coco, V.; Collins, P.; Crocombe, A.; Da Cunha Marinho, F.; Dall'Occo, E.; De Capua, S.; Dean, C.T.; Dettori, F.; Dossett, D.; Dreimanis, K.; Dujany, G.; Eklund, L.; Evans, T.; Ferro-Luzzi, M.; Gersabeck, M.; Gershon, T.; Hadavizadeh, T.; Harrison, J.; Hennessy, K.; Hulsbergen, W.; Hutchcroft, D.; Ilten, P.; Jans, E.; John, M.; Kopciewicz, P.; Koppenburg, P.; Lafferty, G.; Latham, T.; Leflat, A.; Majewski, M.W.; McNulty, R.; Mylroie-Smith, J.; Oblakowska-Mucha, A.; Parkes, C.; Pearce, A.; Poluektov, A.; Pritchard, A.; Qian, W.; Redford, S.; Richards, S.; Rinnert, K.; Rodrigues, E.; Sarpis, G.; Schiller, M.; Schindler, H.; Smith, M.; Smith, N.A.; Szumlak, T.; Velthuis, J.J.; Volkov, V.; Wallace, C.; Wark, H.M.; Webber, A.; Williams, M.R.J.; Williams, M.

    2018-06-13

    Precise knowledge of the location of the material in the LHCb vertex locator (VELO) is essential to reducing background in searches for long-lived exotic particles, and in identifying jets that originate from beauty and charm quarks. Secondary interactions of hadrons produced in beam-gas collisions are used to map the location of material in the VELO. Using this material map, along with properties of a reconstructed secondary vertex and its constituent tracks, a $p$-value can be assigned to the hypothesis that the secondary vertex originates from a material interaction. A validation of this procedure is presented using photon conversions to dimuons.

  20. A new efficient RLF-like algorithm for the vertex coloring problem

    Directory of Open Access Journals (Sweden)

    Adegbindin Mourchid

    2016-01-01

    Full Text Available The Recursive Largest First (RLF algorithm is one of the most popular greedy heuristics for the vertex coloring problem. It sequentially builds color classes on the basis of greedy choices. In particular, the first vertex placed in a color class C is one with a maximum number of uncolored neighbors, and the next vertices placed in C are chosen so that they have as many uncolored neighbors which cannot be placed in C. These greedy choices can have a significant impact on the performance of the algorithm, which explains why we propose alternative selection rules. Computational experiments on 63 difficult DIMACS instances show that the resulting new RLF-like algorithm, when compared with the standard RLF, allows to obtain a reduction of more than 50% of the gap between the number of colors used and the best known upper bound on the chromatic number. The new greedy algorithm even competes with basic metaheuristics for the vertex coloring problem.

  1. What can we learn from sum rules for vertex functions in QCD

    International Nuclear Information System (INIS)

    Craigie, N.S.; Stern, J.

    1982-04-01

    We demonstrate that the light cone sum rules for vertex functions based on the operator product expansion and QCD perturbation theory lead to interesting relationships between various non-perturbative parameters associated with hadronic bound states (e.g. vertex couplings and decay constants). We also show that such sum rules provide a valuable means of estimating the matrix elements of the higher spin operators in the meson wave function. (author)

  2. Lowest-order corrections to the RPA polarizability and GW self-energy of a semiconducting wire

    NARCIS (Netherlands)

    Groot, de H.J.; Ummels, R.T.M.; Bobbert, P.A.; van Haeringen, W.

    1996-01-01

    We present the results of the addition of lowest-order vertex and self-consistency corrections to the RPA polarizability and the GW self-energy for a semiconducting wire. It is found that, when starting from a local density approximation zeroth-order Green function and systematically including these

  3. Renormalization group analysis of the temperature dependent coupling constant in massless theory

    International Nuclear Information System (INIS)

    Yamada, Hirofumi.

    1987-06-01

    A general analysis of finite temperature renormalization group equations for massless theories is presented. It is found that in a direction where momenta and temperature are scaled up with their ratio fixed the coupling constant behaves in the same manner as in zero temperature and that asymptotic freedom at short distances is also maintained at finite temperature. (author)

  4. New anomaly: nonvanishing interaction of longitudinal real photons in massless quantum electrodynamics

    International Nuclear Information System (INIS)

    Gorskij, A.S.; Ioffe, B.L.; Khodzhamiryan, A.Yu.

    1989-01-01

    It is shown that in massless electrodynamics (when the electron mass is strictly zero) the cross section of longitudinal photon interaction on mass shell is nonvanishing. The reasons of appearance of this effects and its possible consequences as well as analogous effects in other quantum field theories (especially non-Abelian gauge theories) are discussed. 7 refs.; 2 figs

  5. Twisted Frobenius identies from vertex operator superalgebras

    Czech Academy of Sciences Publication Activity Database

    Zuevsky, Alexander

    2017-01-01

    Roč. 2017, 9 November (2017), č. článku 2340410. ISSN 1687-9120 Institutional support: RVO:67985840 Keywords : vertex operator superalgebras * intertwining operators * Riemann surfaces Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 0.643, year: 2016 https://www.hindawi.com/journals/amp/2017/2340410/

  6. Development of Data Processing Algorithms for the Upgraded LHCb Vertex Locator

    CERN Document Server

    AUTHOR|(CDS)2101352

    The LHCb detector will see a major upgrade during LHC Long Shutdown II, which is planned for 2019/20. The silicon Vertex Locator subdetector will be upgraded for operation under the new run conditions. The detector will be read out using a data acquisition board based on an FPGA. The work presented in this thesis is concerned with the development of the data processing algorithms to be used in this data acquisition board. In particular, work in three different areas of the FPGA is covered: the data processing block, the low level interface, and the post router block. The algorithms produced have been simulated and tested, and shown to provide the required performance. Errors in the initial implementation of the Gigabit Wireline Transmitter serialized data in the low level interface were discovered and corrected. The data scrambling algorithm and the post router block have been incorporated in the front end readout chip.

  7. The three-gluon vertex of QCD

    International Nuclear Information System (INIS)

    Koller, K.; Zerwas, P.M.; Walsh, T.F.

    1978-12-01

    We show how the Q 2 evolution of gluon jets can be used to provide indirect but strong evidence for the 3 gluon vertex of QCD. We propose looking for this evolution in the QantiQ → 3G → hadrons decay of successive 1 3 S 1 quarkonium states. The results apply to other processes if G jets can be isolated. (orig.) [de

  8. Vertex chamber for the KEDR detector

    International Nuclear Information System (INIS)

    Aulchenko, V.M.; Chilingarov, A.G.; Kolachev, G.M.; Lazarenko, O.B.; Nagaslaev, V.P.; Romanov, L.V.

    1989-01-01

    The project and design of the vertex chamber for the KEDR detector is described. The chamber consists of 6 cylindrical layers of tubes with 10 mm diameter and 800 mm length. The tubes are made of 20 μm thick aluminized mylar. The prototype tests show that it is possible to achieve a resolution of 20-30 μm using the cool gas mixtures. (orig.)

  9. (2 + 1)-dimensional interacting model of two massless spin-2 fields as a bi-gravity model

    Science.gov (United States)

    Hoseinzadeh, S.; Rezaei-Aghdam, A.

    2018-06-01

    We propose a new group-theoretical (Chern-Simons) formulation for the bi-metric theory of gravity in (2 + 1)-dimensional spacetime which describe two interacting massless spin-2 fields. Our model has been formulated in terms of two dreibeins rather than two metrics. We obtain our Chern-Simons gravity model by gauging mixed AdS-AdS Lie algebra and show that it has a two dimensional conformal field theory (CFT) at the boundary of the anti de Sitter (AdS) solution. We show that the central charge of the dual CFT is proportional to the mass of the AdS solution. We also study cosmological implications of our massless bi-gravity model.

  10. Radiative corrections in bumblebee electrodynamics

    Directory of Open Access Journals (Sweden)

    R.V. Maluf

    2015-10-01

    Full Text Available We investigate some quantum features of the bumblebee electrodynamics in flat spacetimes. The bumblebee field is a vector field that leads to a spontaneous Lorentz symmetry breaking. For a smooth quadratic potential, the massless excitation (Nambu–Goldstone boson can be identified as the photon, transversal to the vacuum expectation value of the bumblebee field. Besides, there is a massive excitation associated with the longitudinal mode and whose presence leads to instability in the spectrum of the theory. By using the principal-value prescription, we show that no one-loop radiative corrections to the mass term is generated. Moreover, the bumblebee self-energy is not transverse, showing that the propagation of the longitudinal mode cannot be excluded from the effective theory.

  11. Effectiveness of Vertex Nomination via Seeded Graph Matching to Find Bijections Between Similar Networks

    Science.gov (United States)

    2018-02-01

    Information Directorate This report is published in the interest of scientific and technical information exchange, and its publication does not...the current prototype. 15. SUBJECT TERMS Vertex Nomination via Seeded Graph Matching (VN via SGM), Seeded Graph Matching (SGM), Vertex of Interest (VOI...Author’s Example ................................................................................................................. 4 4.2.2 Simple

  12. Vertex Stimulation as a Control Site for Transcranial Magnetic Stimulation: A Concurrent TMS/fMRI Study

    OpenAIRE

    Jung, JeYoung; Bungert, Andreas; Bowtell, Richard; Jackson, Stephen R.

    2016-01-01

    Background A common control condition for transcranial magnetic stimulation (TMS) studies is to apply stimulation at the vertex. An assumption of vertex stimulation is that it has relatively little influence over on-going brain processes involved in most experimental tasks, however there has been little attempt to measure neural changes linked to vertex TMS. Here we directly test this assumption by using a concurrent TMS/fMRI paradigm in which we investigate fMRI blood-oxygenation-level-depen...

  13. Singletons, higher spin massless states and the supermembrane

    International Nuclear Information System (INIS)

    Bergshoeff, E.; Salam, A.; Sezgin, E.; Tanii, Yoshiaki.

    1988-01-01

    We analyse the spectrum of the eleven dimensional supermembrane quantized in AdS 4 xS 7 background. The classical membrane lives at the boundary of AdS 4 which is S 2 xS 1 , and has OSp(8,4) symmetry. We find that the spectrum contains, in addition to the N=8 supersymmetric (massive) singletons (which may possibly be the ultimate preons), also massless states of all higher integer and half-integer spin. These states fill the irreducible representations of OSp(8,4) with highest spin s max =2,4,6,... The s max =2 multiplet corresponds to the states of the de Wit-Nicolai's N=8 gauged supergravity in four dimensions. (author). 24 refs

  14. Analytic continuation of massless two-loop four-point functions

    International Nuclear Information System (INIS)

    Gehrmann, T.; Remiddi, E.

    2002-01-01

    We describe the analytic continuation of two-loop four-point functions with one off-shell external leg and internal massless propagators from the Euclidean region of space-like 1→3 decay to Minkowskian regions relevant to all 1→3 and 2→2 reactions with one space-like or time-like off-shell external leg. Our results can be used to derive two-loop master integrals and unrenormalized matrix elements for hadronic vector-boson-plus-jet production and deep inelastic two-plus-one-jet production, from results previously obtained for three-jet production in electron-positron annihilation. (author)

  15. Unfolded equations for current interactions of 4d massless fields as a free system in mixed dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Gelfond, O. A., E-mail: gel@lpi.ru [Russian Academy of Sciences, Institute of System Research (Russian Federation); Vasiliev, M. A., E-mail: vasiliev@lpi.ru [Russian Academy of Sciences, I. E. Tamm Department of Theoretical Physics, Lebedev Physical Institute (Russian Federation)

    2015-03-15

    Interactions of massless fields of all spins in four dimensions with currents of any spin are shown to result from a solution of the linear problem that describes a gluing between a rank-one (massless) system and a rank-two (current) system in the unfolded dynamics approach. Since the rank-two system is dual to a free rank-one higher-dimensional system that effectively describes conformal fields in six space-time dimensions, the constructed system can be interpreted as describing a mixture between linear conformal fields in four and six dimensions. An interpretation of the obtained results in the spirit of the AdS/CFT correspondence is discussed.

  16. Vertex ring-indexed Lie algebras

    International Nuclear Information System (INIS)

    Fairlie, David; Zachos, Cosmas

    2005-01-01

    Infinite-dimensional Lie algebras are introduced, which are only partially graded, and are specified by indices lying on cyclotomic rings. They may be thought of as generalizations of the Onsager algebra, but unlike it, or its sl(n) generalizations, they are not subalgebras of the loop algebras associated with sl(n). In a particular interesting case associated with sl(3), their indices lie on the Eisenstein integer triangular lattice, and these algebras are expected to underlie vertex operator combinations in CFT, brane physics, and graphite monolayers

  17. Classical field configurations and infrared slavery

    Science.gov (United States)

    Swanson, Mark S.

    1987-09-01

    The problem of determining the energy of two spinor particles interacting through massless-particle exchange is analyzed using the path-integral method. A form for the long-range interaction energy is obtained by analyzing an abridged vertex derived from the parent theory. This abridged vertex describes the radiation of zero-momentum particles by pointlike sources. A path-integral formalism for calculating the energy of the radiation field associated with this abridged vertex is developed and applications are made to determine the energy necessary for adiabatic separation of two sources in quantum electrodynamics and for an SU(2) Yang-Mills theory. The latter theory is shown to be consistent with confinement via infrared slavery.

  18. JTAG boundary-scan of the Belle II pixel vertex detector

    Energy Technology Data Exchange (ETDEWEB)

    Leitl, Philipp [Max-Planck-Institut fuer Physik (Germany); Collaboration: Belle II-Collaboration

    2016-07-01

    For the upgrade of the Vertex Detector at the Belle II experiment, DEPFET sensors will be used. This new technology requires specific electronics for controlling and readout. Therefore three different kinds of Application-Specific Integrated Circuits (ASICs) are mounted very close to the sensors. Because of space limitations ball grid arrays (BGAs) are used for the contacts to the electronic circuitry. After the mounting process this results in a lack of physical access to the electrical connections. With Boundary-Scan tests, following the IEEE Std 1149.1, it is possible to regain access to the pins for interconnection tests. In this way a quality assurance (QA) is possible to verify that the integration was done correctly and that the circuitry and the electronics are working properly. The present user-friendly system is presented, including the description of additionally developed hardware as well as necessary adjustments to the netlist files and Boundary-Scan Description Language (BSDL) Files of the ASICs. Achieved measurement results from the so far produced detector modules are shown.

  19. Silicon vertex detector for superheavy elements identification

    Directory of Open Access Journals (Sweden)

    Bednarek A.

    2012-07-01

    Full Text Available Silicon vertex detector for superheavy elements (SHE identification has been proposed. It will be constructed using very thin silicon detectors about 5 μm thickness. Results of test of 7.3 μm four inch silicon strip detector (SSD with fission fragments and α particles emitted by 252Cf source are presented

  20. MS vs. pole masses of gauge bosons II: Two-loop electroweak fermion correct

    International Nuclear Information System (INIS)

    Jegerlehner, F.; Kalmykov, M.Yu.; Veretin, O.

    2002-12-01

    We have calculated the fermion contributions to the shift of the position of the poles of the massive gauge boson propagators at two-loop order in the Standard Model. Together with the bosonic contributions calculated previously the full two-loop corrections are available. This allows us to investigate the full correction in the relationship between anti M anti S and pole masses of the vector bosons Z and W. Two-loop renormalization and the corresponding renormalization group equations are discussed. Analytical results for the master-integrals appearing in the massless fermion contributions are given. A new approach of summing multiple binomial sums has been developed. (orig.)

  1. Development of pixel detectors for SSC vertex tracking

    International Nuclear Information System (INIS)

    Kramer, G.; Shapiro, S.L.; Arens, J.F.; Jernigan, J.G.; Skubic, P.

    1991-04-01

    A description of hybrid PIN diode arrays and a readout architecture for their use as a vertex detector in the SSC environment is presented. Test results obtained with arrays having 256 x 256 pixels, each 30 μm square, are also presented. The development of a custom readout for the SSC will be discussed, which supports a mechanism for time stamping hit pixels, storing their xy coordinates, and storing the analog information within the pixel. The peripheral logic located on the array, permits the selection of those pixels containing interesting data and their coordinates to be selectively read out. This same logic also resolves ambiguous pixel ghost locations and controls the pixel neighbor read out necessary to achieve high spatial resolution. The thermal design of the vertex tracker and the proposed signal processing architecture will also be discussed. 5 refs., 13 figs., 3 tabs

  2. First Results from the LHCb Vertex Locator

    CERN Multimedia

    Borghi, S

    2010-01-01

    LHCb is a dedicated experiment to study new physics in the decays of beauty and charm hadrons at the Large Hadron Collider (LHC) at CERN. The beauty and charm hadrons are identified through their flight distance in the Vertex Locator (VELO), and hence the detector is critical for both the trigger and offline physics analyses. The VELO is the silicon detector surrounding the interaction point, and is the closest LHC vertex detector to the interaction point, located only 7 mm from the LHC beam during normal operation. The detector will operate in an extreme and highly non-uniform radiation environment. The VELO consists of two retractable detector halves with 21 silicon micro-strip tracking modules each. A module is composed of two n+-on-n 300 micron thick half disc sensors with R-measuring and Phi-measuring micro-strip geometry, mounted on a carbon fibre support paddle. The minimum pitch is approximately 40 $\\mu$m. The detector is also equipped with one n-on-p module. The detectors are operated in vacuum and a...

  3. AdS{sub 3}/CFT{sub 2}, finite-gap equations and massless modes

    Energy Technology Data Exchange (ETDEWEB)

    Lloyd, Thomas; Stefański, Bogdan Jr. [Centre for Mathematical Science, City University London,Northampton Square, London EC1V 0HB (United Kingdom)

    2014-04-29

    It is known that string theory on AdS{sub 3}×M{sub 7} backgrounds, where M{sub 7}=S{sup 3}×S{sup 3}×S{sup 1} or S{sup 3}×T{sup 4}, is classically integrable. This integrability has been previously used to write down a set of integral equations, known as the finite-gap equations. These equations can be solved for the closed string spectrum of the theory. However, it has been known for some time that the finite-gap equations on these AdS{sub 3}×M{sub 7} backgrounds do not capture the dynamics of the massless modes of the closed string theory. In this paper we re-examine the derivation of the AdS{sub 3}×M{sub 7} finite-gap system. We find that the conditions that had previously been imposed on these integral equations in order to implement the Virasoro constraints are too strict, and are in fact not required. We identify the correct implementation of the Virasoro constraints on finite-gap equations and show that this new, less restrictive condition captures the complete closed string spectrum on AdS{sub 3}×M{sub 7}.

  4. On the identification of gravitation with the massless spin 2 field

    International Nuclear Information System (INIS)

    Meszaros, A.

    1984-05-01

    The identification of gravitation with the massless spin 2 gauge field (the gauge group is the group of translations) requires to restrict the solutions of Einstein's equations to the class of topologically trivial manifolds. It is shown that the validity of this restriction in nature is supported by the present-day empirical facts. The identification has a drastic impact on cosmology, because the fulfilment of the cosmological principle seems to be improbable. (author)

  5. A hadron-quark vertex function

    International Nuclear Information System (INIS)

    Mitra, A.N.; Bhatnagar, S.

    1992-01-01

    This paper reports that the interrelation between the 4D and 3D forms of the Bethe-Salpeter equation (BSE) with a kernel K(q,q') which depends on the relative four-momenta, q μ = q μ - P · qP μ /P 2 , orthogonal to P μ is exploited to obtain a hadron-quark vertex function of the Lorentz-invariant form Γ(q) = D(q 2 ) circle time φ(q). The denominator function D(q 2 ) is universal and controls the 3D BSE, which provides the mass spectra with the eigenfunctions φ(q). The vertex function, directly related to the 4D wave function Ψ which satisfies a corresponding BSE, defines a natural off-shell extension over the whole of four-momentum space, and provides the basis for the evaluation of transition amplitudes via appropriate quark-loop diagrams. The key role of the quantity q 2 in this formalism is clarified in relation to earlier approaches, in which the applications of this quantity had mostly been limited to the mass shell (q · P = 0). Two applications (f p values for P → ell bar ell and F π for π 0 → γγ) are sketched as illustrations of this formalism, and attention is drawn to the problem of complex amplitudes for bigger quark loops with more hadrons, together with the role of the D(q) function in overcoming this problem

  6. Exact Solution of the Six-Vertex Model with Domain Wall Boundary Conditions. Disordered Phase

    CERN Document Server

    Bleher, P M

    2005-01-01

    The six-vertex model, or the square ice model, with domain wall boundary conditions (DWBC) has been introduced and solved for finite $N$ by Korepin and Izergin. The solution is based on the Yang-Baxter equations and it represents the free energy in terms of an $N\\times N$ Hankel determinant. Paul Zinn-Justin observed that the Izergin-Korepin formula can be re-expressed in terms of the partition function of a random matrix model with a nonpolynomial interaction. We use this observation to obtain the large $N$ asymptotics of the six-vertex model with DWBC in the disordered phase. The solution is based on the Riemann-Hilbert approach and the Deift-Zhou nonlinear steepest descent method. As was noticed by Kuperberg, the problem of enumeration of alternating sign matrices (the ASM problem) is a special case of the the six-vertex model. We compare the obtained exact solution of the six-vertex model with known exact results for the 1, 2, and 3 enumerations of ASMs, and also with the exact solution on the so-called f...

  7. Bifurcation of the Quark Self-Energy: Infra-Red and Ultra-Violet Cut-Offs

    NARCIS (Netherlands)

    Atkinson, D.; Johnson, P. W.

    1987-01-01

    The quark self-energy in massless QCD is studied in the approximation that both the quark-gluon vertex and the gluon propagator remain bare. It is shown that chiral invariance is not spontaneously broken at a critical coupling λc>0, unless both infrared and ultraviolet cutoffs are introduced.

  8. A quantum relativistic integrable model as the continuous limit of the six-vertex model

    International Nuclear Information System (INIS)

    Zhou, Y.K.

    1992-01-01

    The six-vertex model in two-dimensional statistical mechanics is used to construct the L-matrix of a one-dimensional quantum relativistic integrable model through a continuous limit. This is the first step to extend the method used earlier by the author to construct quantum completely integrable systems from other well-known two-dimensional vertex models. (orig.)

  9. Vertex Normals and Face Curvatures of Triangle Meshes

    KAUST Repository

    Sun, Xiang; Jiang, Caigui; Wallner, Johannes; Pottmann, Helmut

    2016-01-01

    This study contributes to the discrete differential geometry of triangle meshes, in combination with discrete line congruences associated with such meshes. In particular we discuss when a congruence defined by linear interpolation of vertex normals

  10. Uncovering the triple omeron vertex from Wilson line formalism

    International Nuclear Information System (INIS)

    Chirilli, G. A.; Szymanowski, L.; Wallon, S.

    2011-01-01

    We compute the triple omeron vertex from the Wilson line formalism, including both planar and nonplanar contributions, and get perfect agreement with the result obtained in the Extended Generalized Logarithmic Approximation based on Reggeon calculus.

  11. Tripartite connection condition for a quantum graph vertex

    Czech Academy of Sciences Publication Activity Database

    Cheon, T.; Exner, Pavel; Turek, Ondřej

    2010-01-01

    Roč. 375, č. 2 (2010), s. 113-118 ISSN 0375-9601 R&D Projects: GA MŠk LC06002 Institutional research plan: CEZ:AV0Z10480505 Keywords : Schrodinger operator * Singular vertex * Boundary conditions Subject RIV: BA - General Mathematics Impact factor: 1.963, year: 2010

  12. The design and performance of the ZEUS micro vertex detector

    Energy Technology Data Exchange (ETDEWEB)

    Polini, A. [Bologna Univ. (Italy)]|[INFN Bologna (Italy); Brock, I.; Goers, S. [Bonn Univ. (DE). Physikalisches Institut] (and others)

    2007-08-15

    In order to extend the tracking acceptance, to improve the primary and secondary vertex reconstruction and thus enhancing the tagging capabilities for short lived particles, the ZEUS experiment at the HERA Collider at DESY installed a silicon strip vertex detector. The barrel part of the detector is a 63 cm long cylinder with silicon sensors arranged around an elliptical beampipe. The forward part consists of four circular shaped disks. In total just over 200k channels are read out using 2.9 m{sup 2} of silicon. In this report a detailed overview of the design and construction of the detector is given and the performance of the completed system is reviewed. (orig.)

  13. Exploratory study of the three-gluon vertex on the lattice

    Energy Technology Data Exchange (ETDEWEB)

    Parrinello, C. (Department of Physics and Astronomy, University of Edinburgh, Mayfield Road, Edinburgh EH93JZ (United Kingdom))

    1994-10-01

    We define and evaluate on the lattice the amputated three-gluon vertex function in momentum space. We give numerical results for 16[sup 3][times]40 and 24[sup 3][times]40 quenched lattices at [beta]=6.0. A good numerical signal is obtained at the price of enforcing the gauge-fixing condition with high accuracy. By comparing results from two different lattice volumes, we try to investigate the crucial issue of finite volume effects. We also outline a method for the lattice evaluation of the QCD running coupling as defined from the three-gluon vertex, while being aware that a realistic calculation will require larger [beta] values and very high statistics.

  14. The design and performance of the ZEUS micro vertex detector

    International Nuclear Information System (INIS)

    Polini, A.; Brock, I.; Goers, S.

    2007-08-01

    In order to extend the tracking acceptance, to improve the primary and secondary vertex reconstruction and thus enhancing the tagging capabilities for short lived particles, the ZEUS experiment at the HERA Collider at DESY installed a silicon strip vertex detector. The barrel part of the detector is a 63 cm long cylinder with silicon sensors arranged around an elliptical beampipe. The forward part consists of four circular shaped disks. In total just over 200k channels are read out using 2.9 m 2 of silicon. In this report a detailed overview of the design and construction of the detector is given and the performance of the completed system is reviewed. (orig.)

  15. An efficicient data structure for three-dimensional vertex based finite volume method

    Science.gov (United States)

    Akkurt, Semih; Sahin, Mehmet

    2017-11-01

    A vertex based three-dimensional finite volume algorithm has been developed using an edge based data structure.The mesh data structure of the given algorithm is similar to ones that exist in the literature. However, the data structures are redesigned and simplied in order to fit requirements of the vertex based finite volume method. In order to increase the cache efficiency, the data access patterns for the vertex based finite volume method are investigated and these datas are packed/allocated in a way that they are close to each other in the memory. The present data structure is not limited with tetrahedrons, arbitrary polyhedrons are also supported in the mesh without putting any additional effort. Furthermore, the present data structure also supports adaptive refinement and coarsening. For the implicit and parallel implementation of the FVM algorithm, PETSc and MPI libraries are employed. The performance and accuracy of the present algorithm are tested for the classical benchmark problems by comparing the CPU time for the open source algorithms.

  16. Quantum entanglement: the unitary 8-vertex braid matrix with imaginary rapidity

    International Nuclear Information System (INIS)

    Chakrabarti, Amitabha; Chakraborti, Anirban; Jedidi, Aymen

    2010-01-01

    We study quantum entanglements induced on product states by the action of 8-vertex braid matrices, rendered unitary with purely imaginary spectral parameters (rapidity). The unitarity is displayed via the 'canonical factorization' of the coefficients of the projectors spanning the basis. This adds one more new facet to the famous and fascinating features of the 8-vertex model. The double periodicity and the analytic properties of the elliptic functions involved lead to a rich structure of the 3-tangle quantifying the entanglement. We thus explore the complex relationship between topological and quantum entanglement. (fast track communication)

  17. Non-Schwinger solution of the two-dimensional massless spinor electrodynamics

    International Nuclear Information System (INIS)

    Mikhov, S.G.

    1981-01-01

    In the present paper a regularization procedure is formulated for the current in the two-dimensional massless spinor electrodynamics that is both gauge and γ 5 -gauge invariant. This gives rise to an operator solution of the model that does not involve a massive photon. The latter solution is studied in some detail, and it is shown that although a charge operator exists, it does not define the electric charge of the spinor field. This can be a manifestation of the charge screening mechanism that is present in the Schwinger model [ru

  18. Massless second-order tetradic spin-3 and higher-helicity bosons

    Energy Technology Data Exchange (ETDEWEB)

    Aragone, C; La Roche, H [Universidad Simon Bolivar, Caracas (Venezuela) Dept. de Fisica

    1982-11-21

    The unique, uniform, second-order formulation of massless bosons of helicity >=3 is presented here in terms of tetradic fields. The actions we find are shown to coincide both with the first-order (tetradic) formulation of Vasiliev and with the symmetric second-order description of Fronsdal. We carefully analyse the gravitational coupling of the spin-3 field and find that tetradic spin-3 matter presents the same translational consistency problem as symmetric matter does. Furthermore, in the curved tetradic case the generalized Lorentz invariance can be restored by the addition of nominimal terms.

  19. Thermodynamics, phase transition and quasinormal modes with Weyl corrections

    Energy Technology Data Exchange (ETDEWEB)

    Mahapatra, Subhash [The Institute of Mathematical Sciences,Chennai 600113 (India)

    2016-04-21

    We study charged black holes in D dimensional AdS space, in the presence of four derivative Weyl correction. We obtain the black hole solution perturbatively up to first as well as second order in the Weyl coupling, and show that first law of black hole thermodynamics is satisfied in all dimensions. We study its thermodynamic phase transition and then calculate the quasinormal frequencies of the massless scalar field perturbation. We find that, here too, the quasinormal frequencies capture the essence of black hole phase transition. Few subtleties near the second order critical point are discussed.

  20. An asynchronous data-driven readout prototype for CEPC vertex detector

    Science.gov (United States)

    Yang, Ping; Sun, Xiangming; Huang, Guangming; Xiao, Le; Gao, Chaosong; Huang, Xing; Zhou, Wei; Ren, Weiping; Li, Yashu; Liu, Jianchao; You, Bihui; Zhang, Li

    2017-12-01

    The Circular Electron Positron Collider (CEPC) is proposed as a Higgs boson and/or Z boson factory for high-precision measurements on the Higgs boson. The precision of secondary vertex impact parameter plays an important role in such measurements which typically rely on flavor-tagging. Thus silicon CMOS Pixel Sensors (CPS) are the most promising technology candidate for a CEPC vertex detector, which can most likely feature a high position resolution, a low power consumption and a fast readout simultaneously. For the R&D of the CEPC vertex detector, we have developed a prototype MIC4 in the Towerjazz 180 nm CMOS Image Sensor (CIS) process. We have proposed and implemented a new architecture of asynchronous zero-suppression data-driven readout inside the matrix combined with a binary front-end inside the pixel. The matrix contains 128 rows and 64 columns with a small pixel pitch of 25 μm. The readout architecture has implemented the traditional OR-gate chain inside a super pixel combined with a priority arbiter tree between the super pixels, only reading out relevant pixels. The MIC4 architecture will be introduced in more detail in this paper. It will be taped out in May and will be characterized when the chip comes back.

  1. Discussion on the electronic problems of straw vertex detector

    International Nuclear Information System (INIS)

    Xi Deming

    1992-01-01

    The measurement of the characteristic time of the output waveform of straw vertex detector, the design of its high resolution and high counting rate readout system and the problems of the charge and time calibrations are discussed

  2. The elliptic quantum algebra Uq,p(sl-hatN) and its vertex operators

    International Nuclear Information System (INIS)

    Chang Wenjing; Ding Xiangmao

    2009-01-01

    We construct a realization of the elliptic quantum algebra U q,p (sl-hat N ) for any given level k in terms of free boson fields and their twisted partners. It can be considered as the elliptic deformation of the Wakimoto realization of the quantum affine algebra U q (sl-hat N ). We also construct a family of screening currents, which commute with the currents of U q,p (sl-hat N ) up to total q-differences. And we give explicit twisted expressions for the type I and type II vertex operators of U q,p (sl-hat N ) by twisting the known results of the type I vertex operators of the quantum affine algebra U q (sl-hat N ) and the new results of the type II vertex operators of U q (sl-hat N ) we obtained in this paper.

  3. Edge-injective and edge-surjective vertex labellings

    DEFF Research Database (Denmark)

    Brandt, Stephan; Rautenbach, D.; Regen, F.

    2010-01-01

    For a graph G = (V, E) we consider vertex-k-labellings f : V → {1,2, ,k} for which the induced edge weighting w : E → {2, 3,., 2k} with w(uv) = f(u) + f(v) is injective or surjective or both. We study the relation between these labellings and the number theoretic notions of an additive basis and ...

  4. Gravitational Collapse of Massless Fields in an Expanding Universe

    Directory of Open Access Journals (Sweden)

    Yoo Chul-Moon

    2018-01-01

    Full Text Available Gravitational collapse of a massless scalar field with the periodic boundary condition in a cubic box is reported. This system can be regarded as a lattice universe model. The initial data is constructed for a Gaussian like profile of the scalar field taking the integrability condition associated with the periodic boundary condition into account. For a large initial amplitude, a black hole is formed after a certain period of time. While the scalar field spreads out in the whole region for a small initial amplitude. The difference of the late time expansion law of the lattice universe depending on the final fate of the gravitational collapse is discussed.

  5. dS/CFT correspondence from a holographic description of massless scalar fields in Minkowski space-time

    International Nuclear Information System (INIS)

    Loran, Farhang

    2004-01-01

    We solve Klein-Gordon equation for massless scalars on (d+1)-dimensional Minkowski (Euclidean) space in terms of the Cauchy data on the hypersurface t=0. By inserting the solution into the action of massless scalars in Minkowski (Euclidean) space we obtain the action of dual theory on the boundary t=0 which is exactly the holographic dual of conformally coupled scalars on (d+1)-dimensional (Euclidean anti) de Sitter space obtained in (A)dS/CFT correspondence. The observed equivalence of dual theories is explained using the one-to-one map between conformally coupled scalar fields on Minkowski (Euclidean) space and (Euclidean anti) de Sitter space which is an isomorphism between the hypersurface t=0 of Minkowski (Euclidean) space and the boundary of (A)dS space

  6. Massive spin-one fields from couplings with five massless real scalars

    Science.gov (United States)

    Bizdadea, Constantin; Cioroianu, Eugen-Mihaita; Saliu, Solange-Odile

    2017-12-01

    In this paper we implement a new procedure by which one may generate mass for a vector field in the context of its interactions to a system of five real scalar fields. This purpose will be achieved by means of the general multi-step program from [1] adapted to the present situation: (1) we begin with a free theory in four space-time dimensions whose Lagrangian action is given by the sum between the standard Maxwell action and that for a collection consisting in five massless real scalar fields; (2) we construct a general class of gauge theories whose free limit is that from step (1) by means of the deformation of the solution to the master equation [2, 3] with the help of local BRST cohomology [4-6]; (3) we perform some suitable redefinitions of the free parameters that label interacting theories from (2) such that the mass terms become manifest in the new free limit. The outputs of our procedure can be synthesized in: (A) the vector field acquires mass; (B) the scalar fields gain gauge transformations; (C) the gauge algebras of the interacting theories are Abelian; (D) the propagator of the massive vector field emerging from the gauge-fixed actions behaves, in the limit of large Euclidean momenta, like that from the massless case.

  7. The H1 silicon vertex detector

    International Nuclear Information System (INIS)

    Pitzl, D.; Behnke, O.; Biddulph, M.; Boesiger, K.; Eichler, R.; Erdmann, W.; Gabathuler, K.; Gassner, J.; Haynes, W.J..; Horisberger, R.; Kausch, M.; Lindstroem, M.; Niggli, H.; Noyes, G.; Pollet, P.; Steiner, S.; Streuli, S.; Szeker, K.; Truoel, P.

    2000-01-01

    The design, construction and performance of the H1 silicon vertex detector is described. It consists of two cylindrical layers of double-sided, double-metal silicon sensors read out by a custom designed analog pipeline chip. The analog signals are transmitted by optical fibres to a custom-designed ADC board and are reduced on PowerPC processors. Details of the design and construction are given and performance figures from the first data-taking periods are presented

  8. Vertical integration technologies for vertex detectors

    International Nuclear Information System (INIS)

    Ratti, L.

    2011-01-01

    This work is focused on the use of vertical integration (3D) technologies in the design of hybrid or monolithic pixel detectors in view of applications to silicon vertex trackers (SVTs) at the future high luminosity colliders. After a short introduction on the specifications of next-generation SVTs, the paper will discuss the general features of 3D microelectronic processes and the benefits they can provide to the design of pixel detectors for high energy physics experiments.

  9. Fine pitch and low material readout bus in the Silicon Pixel Vertex Tracker for the PHENIX Vertex Tracker upgrade

    International Nuclear Information System (INIS)

    Fujiwara, Kohei

    2010-01-01

    The construction of the Silicon Pixel Detector is starting in spring 2009 as project of the RHIC-PHENIX Silicon Vertex Tracker (VTX) upgrade at the Brookhaven National Laboratory. For the construction, we have developed a fine pitch and low material readout bus as the backbone parts of the VTX. In this article, we report the development and production of the readout bus.

  10. Use of an electron reflector to improve dose uniformity at the vertex during total skin electron therapy

    International Nuclear Information System (INIS)

    Peters, V.G.

    2000-01-01

    Purpose: The vertex of the scalp is always tangentially irradiated during total skin electron therapy (TSET). This study was conducted to determine the dose distribution at the vertex for a commonly used irradiation technique and to evaluate the use of an electron reflector, positioned above the head, as a means of improving the dose uniformity. Methods and Materials: Phantoms, simulating the head of a patient, were irradiated using our standard procedure for TSET. The technique is a six-field irradiation using dual angled electron beams at a treatment distance of 3.6 meters. Vertex dosimetry was performed using ionization methods and film. Measurements were made for an unmodified 6 MeV electron beam and for a 4 MeV beam obtained by placing an acrylic scattering plate in the beam line. Studies were performed to examine the effect of electron scattering on vertex dose when a lead reflector, 50 x 50 cm in area, was positioned above the phantom. Results: The surface dose at the vertex, in the absence of the reflector, was found to be less than 40% of the prescribed skin dose. Use of the lead reflector increased this value to 73% for the 6 MeV beam and 99% for the degraded 4 MeV beam. Significant improvements in depth dose were also observed. The dose enhancement is not strongly dependent on reflector distance or angulation since the reflector acts as a large source of broadly scattered electrons. Conclusion: The vertex may be significantly underdosed using standard techniques for total skin electron therapy. Use of an electron reflector improves the dose uniformity at the vertex and may reduce or eliminate the need for supplemental irradiation

  11. Study of a DEPFET vertex detector and of supersymmetric smuons at the ILC

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xun

    2009-01-21

    This thesis is devoted to the study of the performance of a pixel vertex detector based on DEPFET technology at the International Linear Collider (ILC). The ILC is the proposed next generation e{sup +}e{sup -} collider to explore the physics at the Terascale. At the ILC with its well-defined initial state of collisions, possible discoveries at the Large Hadron Collider can be verified and studied more accurately. It is expected that the precision measurements of the ILC will answer many fundamental questions about the universe, such as the generation of particle masses and the origin of electroweak spontaneous symmetry breaking. The ambitious physics goals present challenges to the ILC detectors. Several detector concepts have been proposed in recent years. A crucial device for all these concepts is the pixel vertex detector. It provides precise impact parameter information of charged particles, jet flavor tagging and improves overall tracking efficiency. To meet the requirements of the ILC environment, the vertex detector will be arranged in a concentric multi-layer array around the interaction point to cover as large a solid angle as possible. Endcap disks are considered in some designs. Silicon pixel sensor technologies must be employed to provide excellent point resolution. The DEPFET technology, which integrates the first level of amplification into a depleted silicon bulk, is one of the promising candidates. The DEPFET sensor is very sensitive with a high signal-to-noise ratio. Power consumption is minimized due to the internal storage of signal charges. The good radiation tolerance makes it capable of working close to the interaction point. In this thesis, we discuss the detailed simulation of the DEPFET vertex detector, following the general vertex detector layout proposed by the TESLA collaboration. The simulation is used to evaluate the impact parameter resolution. We also discuss the DEPFET test beam analysis on two-track resolution. The whole analysis

  12. Study of a DEPFET vertex detector and of supersymmetric smuons at the ILC

    International Nuclear Information System (INIS)

    Chen, Xun

    2009-01-01

    This thesis is devoted to the study of the performance of a pixel vertex detector based on DEPFET technology at the International Linear Collider (ILC). The ILC is the proposed next generation e + e - collider to explore the physics at the Terascale. At the ILC with its well-defined initial state of collisions, possible discoveries at the Large Hadron Collider can be verified and studied more accurately. It is expected that the precision measurements of the ILC will answer many fundamental questions about the universe, such as the generation of particle masses and the origin of electroweak spontaneous symmetry breaking. The ambitious physics goals present challenges to the ILC detectors. Several detector concepts have been proposed in recent years. A crucial device for all these concepts is the pixel vertex detector. It provides precise impact parameter information of charged particles, jet flavor tagging and improves overall tracking efficiency. To meet the requirements of the ILC environment, the vertex detector will be arranged in a concentric multi-layer array around the interaction point to cover as large a solid angle as possible. Endcap disks are considered in some designs. Silicon pixel sensor technologies must be employed to provide excellent point resolution. The DEPFET technology, which integrates the first level of amplification into a depleted silicon bulk, is one of the promising candidates. The DEPFET sensor is very sensitive with a high signal-to-noise ratio. Power consumption is minimized due to the internal storage of signal charges. The good radiation tolerance makes it capable of working close to the interaction point. In this thesis, we discuss the detailed simulation of the DEPFET vertex detector, following the general vertex detector layout proposed by the TESLA collaboration. The simulation is used to evaluate the impact parameter resolution. We also discuss the DEPFET test beam analysis on two-track resolution. The whole analysis procedures

  13. Fast simulation and topological vertex finding in JAVA

    International Nuclear Information System (INIS)

    Walkowiak, Wolfgang

    2001-01-01

    An overview of the fast Monte Carlo simulation for NLC detector studies as currently provided in the Java Analysis Studio environment is presented. Special emphasis is given to the simulation of tracks. In addition, the SLD collaboration's topological vertex finding algorithm (ZVTOP) has been implemented in the Java Analysis Studio framework

  14. Massless scalar field in de Sitter spacetime: unitary quantum time evolution

    International Nuclear Information System (INIS)

    Cortez, Jerónimo; Blas, Daniel Martín-de; Marugán, Guillermo A Mena; Velhinho, José M

    2013-01-01

    We prove that, under the standard conformal scaling, a free scalar field in de Sitter spacetime admits an O(4)-invariant Fock quantization such that time evolution is unitarily implemented. Since this applies in particular to the massless case, this result disproves previous claims in the literature. We discuss the relationship between this quantization with unitary dynamics and the family of O(4)-invariant Hadamard states given by Allen and Folacci, as well as with the Bunch–Davies vacuum. (paper)

  15. Numerical Study of the Ghost-Ghost-Gluon Vertex on the Lattice

    International Nuclear Information System (INIS)

    Mihara, A.; Cucchieri, A.; Mendes, T.

    2004-01-01

    It is well known that, in Landau gauge, the renormalization function of the ghost-ghost-gluon vertex Z-tilde1 (p2) is finite and constant, at least to all orders of perturbation theory. On the other hand, a direct non-perturbative verification of this result using numerical simulations of lattice QCD is still missing. Here we present a preliminary numerical study of the ghost-ghost-gluon vertex and of its corresponding renormalization function using Monte Carlo simulations in SU(2) lattice Landau gauge. Data were obtained in 4 dimensions for lattice couplings β = 2.2, 2.3, 2.4 and lattice sides N = 4, 8, 16

  16. Numerical study of the ghost-ghost-gluon vertex on the lattice

    International Nuclear Information System (INIS)

    Mihara, A.; Cucchieri, A.; Mendes, T.

    2004-01-01

    It is well known that, in Landau gauge, the renormalization function of the ghost-ghost-gluon vertex Z∼ 1 1(p 2 ) is finite and constant, at least to all orders of perturbation theory. On the other hand, a direct non-perturbative verification of this result using numerical simulations of lattice QCD is still missing. Here we present a preliminary numerical study of the ghost-ghost-gluon vertex and of its corresponding renormalization function using Monte Carlo simulations in SU(2) lattice Landau gauge. Data were obtained in 4 dimensions for lattice couplings β= 2.2, 2.3, 2.4 and lattice sides N = 4, 8, 16. (author)

  17. The SuperB Silicon Vertex Tracker and 3D vertical integration

    CERN Document Server

    Re, Valerio

    2011-01-01

    The construction of the SuperB high luminosity collider was approved and funded by the Italian government in 2011. The performance specifications set by the target luminosity of this machine (> 10^36 cm^-2 s^-1) ask for the development of a Silicon Vertex Tracker with high resolution, high tolerance to radiation and excellent capability of handling high data rates. This paper reviews the R&D activity that is being carried out for the SuperB SVT. Special emphasis is given to the option of exploiting 3D vertical integration to build advanced pixel sensors and readout electronics that are able to comply with SuperB vertexing requirements.

  18. NLO Vertex for a Forward Jet plus a Rapidity Gap at High Energies

    CERN Document Server

    Hentschinski, Martin; Murdaca, Beatrice; Vera, Agustín Sabio

    2015-01-01

    We present the calculation of the forward jet vertex associated to a rapidity gap (coupling of a hard pomeron to the jet) in the BFKL formalism at next-to-leading order (NLO). Real emission contributions are computed via Lipatov's effective action. The NLO jet vertex turns out to be finite within collinear factorization and allows, together with the NLO non-forward gluon Green's function, to perform NLO studies of jet production in diffractive events (e.g. Mueller-Tang dijets).

  19. Loop-quantum-gravity vertex amplitude.

    Science.gov (United States)

    Engle, Jonathan; Pereira, Roberto; Rovelli, Carlo

    2007-10-19

    Spin foam models are hoped to provide the dynamics of loop-quantum gravity. However, the most popular of these, the Barrett-Crane model, does not have the good boundary state space and there are indications that it fails to yield good low-energy n-point functions. We present an alternative dynamics that can be derived as a quantization of a Regge discretization of Euclidean general relativity, where second class constraints are imposed weakly. Its state space matches the SO(3) loop gravity one and it yields an SO(4)-covariant vertex amplitude for Euclidean loop gravity.

  20. On the transfer matrix of the supersymmetric eight-vertex model. I. Periodic boundary conditions

    Science.gov (United States)

    Hagendorf, Christian; Liénardy, Jean

    2018-03-01

    The square-lattice eight-vertex model with vertex weights a, b, c, d obeying the relation (a^2+ab)(b^2+ab) = (c^2+ab)(d^2+ab) and periodic boundary conditions is considered. It is shown that the transfer matrix of the model for L  =  2n  +  1 vertical lines and periodic boundary conditions along the horizontal direction possesses the doubly degenerate eigenvalue \\Thetan = (a+b){\\hspace{0pt}}2n+1 . This proves a conjecture by Stroganov from 2001. The proof uses the supersymmetry of a related XYZ spin-chain Hamiltonian. The eigenstates of the transfer matrix corresponding to \\Thetan are shown to be the ground states of the spin-chain Hamiltonian. Moreover, for positive vertex weights \\Thetan is the largest eigenvalue of the transfer matrix.

  1. Dynamical Vertex Approximation for the Hubbard Model

    Science.gov (United States)

    Toschi, Alessandro

    A full understanding of correlated electron systems in the physically relevant situations of three and two dimensions represents a challenge for the contemporary condensed matter theory. However, in the last years considerable progress has been achieved by means of increasingly more powerful quantum many-body algorithms, applied to the basic model for correlated electrons, the Hubbard Hamiltonian. Here, I will review the physics emerging from studies performed with the dynamical vertex approximation, which includes diagrammatic corrections to the local description of the dynamical mean field theory (DMFT). In particular, I will first discuss the phase diagram in three dimensions with a special focus on the commensurate and incommensurate magnetic phases, their (quantum) critical properties, and the impact of fluctuations on electronic lifetimes and spectral functions. In two dimensions, the effects of non-local fluctuations beyond DMFT grow enormously, determining the appearance of a low-temperature insulating behavior for all values of the interaction in the unfrustrated model: Here the prototypical features of the Mott-Hubbard metal-insulator transition, as well as the existence of magnetically ordered phases, are completely overwhelmed by antiferromagnetic fluctuations of exponentially large extension, in accordance with the Mermin-Wagner theorem. Eventually, by a fluctuation diagnostics analysis of cluster DMFT self-energies, the same magnetic fluctuations are identified as responsible for the pseudogap regime in the holed-doped frustrated case, with important implications for the theoretical modeling of the cuprate physics.

  2. Triangle identity and free differential algebra of massless higher spins

    Energy Technology Data Exchange (ETDEWEB)

    Vasiliev, M A [AN SSSR, Moscow. Fizicheskij Inst.

    1989-09-25

    In terms of Berezins's theory of symbols of operators, the integral formulation is suggested for the free differential algebra which gives rise to consistent equations of motion of interacting massless fields of all spins 0{le}s<{infinity} in the frameworks of gravity. In the first nontrivial order of the expansion in powers of curvatures, Frobenius consistency conditions for higher-spin equations of motion are shown to reduce to the simple geometrical fast that there are two ways for splitting any quadrangle in two triangles. To clarify our construction, we illustrate how it works in the simplest case of pure gravity. (orig.).

  3. [Umbilical blood-gas status at cesarean section for breech presentation: a comparison with vertex presentation].

    Science.gov (United States)

    Haruta, M; Saeki, N; Naka, Y; Funato, T; Ohtsuki, Y

    1989-10-01

    Umbilical blood-gas status at elective cesarean section with oxygen inhalation for breech presentation (25 cases) was compared with that for vertex presentation (25 cases), so as to confirm the security of full-term breech fetuses delivered by cesarean section under spinal anesthesia. Umbilical arterial oxygen levels were significantly lower in the breech group (Mean PO2:18.9 mmHg; SO2:37.3%; Oxygen content:7.6 ml/dl). The number of hypoxemic fetuses was significantly higher in the breech group (the breech: 7; the vertex; 0). The other umbilical blood-gas values revealed no significant differences between the breech and vertex groups, and were within normal limits in both groups. Oxygen extraction in the breech (Mean: 49.0%) was higher than that in the vertex (32.9%). Therefore decreased umbilical blood flow in the breech was suggested. The incidence of depression at 1 minute after delivery in the breech infants (24%) was significantly higher than that in the vertex infants (0%). It became obvious in the breech that as the interval between the uterine incision and delivery increased, umbilical arterial blood tended to acidosis and the 1 minute Apgar score decreased. Cesarean section for breech presentation requires sufficient and optimal incisions of the abdominal wall and uterus as well as a skillful manual delivery technique, because the fetus or neonate should be protected against asphyxia resulting from umbilical compression and prolonged delivery interval.

  4. cellGPU: Massively parallel simulations of dynamic vertex models

    Science.gov (United States)

    Sussman, Daniel M.

    2017-10-01

    Vertex models represent confluent tissue by polygonal or polyhedral tilings of space, with the individual cells interacting via force laws that depend on both the geometry of the cells and the topology of the tessellation. This dependence on the connectivity of the cellular network introduces several complications to performing molecular-dynamics-like simulations of vertex models, and in particular makes parallelizing the simulations difficult. cellGPU addresses this difficulty and lays the foundation for massively parallelized, GPU-based simulations of these models. This article discusses its implementation for a pair of two-dimensional models, and compares the typical performance that can be expected between running cellGPU entirely on the CPU versus its performance when running on a range of commercial and server-grade graphics cards. By implementing the calculation of topological changes and forces on cells in a highly parallelizable fashion, cellGPU enables researchers to simulate time- and length-scales previously inaccessible via existing single-threaded CPU implementations. Program Files doi:http://dx.doi.org/10.17632/6j2cj29t3r.1 Licensing provisions: MIT Programming language: CUDA/C++ Nature of problem: Simulations of off-lattice "vertex models" of cells, in which the interaction forces depend on both the geometry and the topology of the cellular aggregate. Solution method: Highly parallelized GPU-accelerated dynamical simulations in which the force calculations and the topological features can be handled on either the CPU or GPU. Additional comments: The code is hosted at https://gitlab.com/dmsussman/cellGPU, with documentation additionally maintained at http://dmsussman.gitlab.io/cellGPUdocumentation

  5. The Mark II vertex detectors: Status and prospects

    International Nuclear Information System (INIS)

    Jaros, J.A.

    1987-03-01

    The art of detecting the decay vertices from heavy quarks and leptons is comparatively new at electron-positron storage rings. So far, drift chambers positioned just outside the vacuum pipes which surround the interfaction region have provided the first accurate determinations of the tau and bottom lifetimes, and confirmed earlier measurements of charmed particle lifetimes. ''Second generation'' vertex detectors have demonstrated the feasibility of tagging heavy flavors by observing decay vertices, and are being used to search for anomalous decay topologies. These chambers have modest resolution on the scale of the effects they seek to measure, but are now well-understood and reliable tools. A generation of vertex detectors, considerably more ambitious, is under construction for experiments at SLC and LEP. They boast impact parameter resolution improved by a factor of four or more over previous detectors, and sub-millimeter track-pair resolution. The Mark II collaboration hopes to reach these goals with a high pressure precision drift chamber, and eventually surpass them with the addition of a silicon microstrip detector

  6. The Mark II vertex detectors: Status and prospects

    Energy Technology Data Exchange (ETDEWEB)

    Jaros, J.A.

    1987-03-01

    The art of detecting the decay vertices from heavy quarks and leptons is comparatively new at electron-positron storage rings. So far, drift chambers positioned just outside the vacuum pipes which surround the interfaction region have provided the first accurate determinations of the tau and bottom lifetimes, and confirmed earlier measurements of charmed particle lifetimes. ''Second generation'' vertex detectors have demonstrated the feasibility of tagging heavy flavors by observing decay vertices, and are being used to search for anomalous decay topologies. These chambers have modest resolution on the scale of the effects they seek to measure, but are now well-understood and reliable tools. A generation of vertex detectors, considerably more ambitious, is under construction for experiments at SLC and LEP. They boast impact parameter resolution improved by a factor of four or more over previous detectors, and sub-millimeter track-pair resolution. The Mark II collaboration hopes to reach these goals with a high pressure precision drift chamber, and eventually surpass them with the addition of a silicon microstrip detector.

  7. Comparison of forward collider vertex detectors for B physics at hadron accelerators

    International Nuclear Information System (INIS)

    Harr, R.F.; Karchin, P.E.; Kennedy, C.J.

    1993-01-01

    Two silicon vertex detector designs have been proposed for a forward collider B physics experiment at the SSC: in one the silicon system is put outside the beampipe (like in the forward part of the proposed BCD detector); and in the other the silicon system is put inside the beampipe, close to the circulating beams, with the use of open-quote roman pots close-quote (as in the COBEX proposal). In what follows these will be referred to as the inside and outside designs. The two designs are significantly different in their construction and impact on the rest of the experiment. The authors would like to understand how the designs compare for doing B physics and what are the factors that most greatly influence the results. Two measurements relying on the vertex detector and of particular importance for B physics are the reconstructed vertex position and B mass. They have analyzed the resolution achievable in these 2 quantities for open-quote models close-quote of the two forward collider vertex detector designs. The design parameters - beampipe radius and thickness, silicon position and resolution, etc. - have been varied about their normal values to observe their effect on these resolutions. They find very little difference between the two designs; both give nearly the same decay length error, impact parameter error, and reconstructed B mass error, for a large range of geometrical parameters. The design parameter having the most significant impact on the errors of B decay vertices is found to be the point resolution of the silicon detectors

  8. Kac--Moody current algebras of D = 2 massless gauge theories, their representations and applications

    International Nuclear Information System (INIS)

    Craigie, N.S.; Nahm, W.; Narain, K.S.

    1987-01-01

    We give a classification of the Kac--Moody current algebras of all the possible massless fermion-gauge theories in two dimensions. It is shown that only Kac--Moody algebras based on A/sub N/, B/sub N/, C/sub N/, and D/sub N/ in the Cartan classification with all possible central charge occur.The representation of local fermion fields and simply laced Kac--Moody algebras with minimal central charge in terms of free boson fields on a compactified space is discussed in detail, where stress is laid on the role played by the boundary conditions on the various collective modes. Fractional solitons and the possible soliton representation of certain nonsimply laced algebras is also analysed. We briefly discuss the relationship between the massless bound state sector of these two-dimensional gauge theories and the critically coupled two-dimensional nonlinear sigma model, which share the same current algebra. Finally we briefly discuss the relevance of Sp(n) Kac--Moody algebras to the physics of monopole-fermion systems. copyright 1987 Academic Press, Inc

  9. Exploratory study of a novel low occupancy vertex detector architecture based on high precision timing for high luminosity particle colliders

    Energy Technology Data Exchange (ETDEWEB)

    Orel, Peter, E-mail: porel@hawaii.edu; Varner, Gary S.; Niknejadi, Pardis

    2017-06-11

    Vertex detectors provide space–time coordinates for the traversing charged particle decay products closest to the interaction point. Resolving these increasingly intense particle fluences at high luminosity particle colliders, such as SuperKEKB, is an ever growing challenge. This results in a non-negligible occupancy of the vertex detector using existing low material budget techniques. Consequently, new approaches are being studied that meet the vertexing requirements while lowering the occupancy. In this paper, we introduce a novel vertex detector architecture. Its design relies on an asynchronous digital pixel matrix in combination with a readout based on high precision time-of-flight measurement. Denoted the Timing Vertex Detector (TVD), it consists of a binary pixel array, a transmission line for signal collection, and a readout ASIC. The TVD aims to have a spatial resolution comparable to the existing Belle2 vertex detector. At the same time it offers a reduced occupancy by a factor of ten while decreasing the channel count by almost three orders of magnitude. Consequently, reducing the event size from about 1 MB/event to about 5.9 kB/event.

  10. Vertex detectors: The state of the art and future prospects

    Energy Technology Data Exchange (ETDEWEB)

    Damerell, C.J.S. [Rutherford Appleton Laboratory, Didcot (United Kingdom)

    1997-01-01

    We review the current status of vertex detectors (tracking microscopes for the recognition of charm and bottom particle decays). The reasons why silicon has become the dominant detector medium are explained. Energy loss mechanisms are reviewed, as well as the physics and technology of semiconductor devices, emphasizing the areas of most relevance for detectors. The main design options (microstrips and pixel devices, both CCD`s and APS`s) are discussed, as well as the issue of radiation damage, which probably implies the need to change to detector media beyond silicon for some vertexing applications. Finally, the evolution of key performance parameters over the past 15 years is reviewed, and an attempt is made to extrapolate to the likely performance of detectors working at the energy frontier ten years from now.

  11. High-frequency asymptotics of the local vertex function. Algorithmic implementations

    Energy Technology Data Exchange (ETDEWEB)

    Tagliavini, Agnese; Wentzell, Nils [Institut fuer Theoretische Physik, Eberhard Karls Universitaet, 72076 Tuebingen (Germany); Institute for Solid State Physics, Vienna University of Technology, 1040 Vienna (Austria); Li, Gang; Rohringer, Georg; Held, Karsten; Toschi, Alessandro [Institute for Solid State Physics, Vienna University of Technology, 1040 Vienna (Austria); Taranto, Ciro [Institute for Solid State Physics, Vienna University of Technology, 1040 Vienna (Austria); Max Planck Institute for Solid State Research, D-70569 Stuttgart (Germany); Andergassen, Sabine [Institut fuer Theoretische Physik, Eberhard Karls Universitaet, 72076 Tuebingen (Germany)

    2016-07-01

    Local vertex functions are a crucial ingredient of several forefront many-body algorithms in condensed matter physics. However, the full treatment of their frequency dependence poses a huge limitation to the numerical performance. A significant advancement requires an efficient treatment of the high-frequency asymptotic behavior of the vertex functions. We here provide a detailed diagrammatic analysis of the high-frequency asymptotic structures and their physical interpretation. Based on these insights, we propose a frequency parametrization, which captures the whole high-frequency asymptotics for arbitrary values of the local Coulomb interaction and electronic density. We present its algorithmic implementation in many-body solvers based on parquet-equations as well as functional renormalization group schemes and assess its validity by comparing our results for the single impurity Anderson model with exact diagonalization calculations.

  12. Vertex detectors: The state of the art and future prospects

    International Nuclear Information System (INIS)

    Damerell, C.J.S.

    1997-01-01

    We review the current status of vertex detectors (tracking microscopes for the recognition of charm and bottom particle decays). The reasons why silicon has become the dominant detector medium are explained. Energy loss mechanisms are reviewed, as well as the physics and technology of semiconductor devices, emphasizing the areas of most relevance for detectors. The main design options (microstrips and pixel devices, both CCD's and APS's) are discussed, as well as the issue of radiation damage, which probably implies the need to change to detector media beyond silicon for some vertexing applications. Finally, the evolution of key performance parameters over the past 15 years is reviewed, and an attempt is made to extrapolate to the likely performance of detectors working at the energy frontier ten years from now

  13. Three-point Green's function of massless QED in position space to lowest order

    International Nuclear Information System (INIS)

    Mitra, Indrajit

    2009-01-01

    The transverse part of the three-point Green's function of massless QED is determined to the lowest order in position space. Taken together with the evaluation of the longitudinal part in Mitra (2008) (J. Phys. A: Math. Theor. 41 315401), this gives a relation for QED which is analogous to the star-triangle relation. We relate our result to conformal-invariant three-point functions

  14. Cubic scattering amplitudes for all massless representations of the Poincare group in any space-time dimension

    International Nuclear Information System (INIS)

    Fradkin, E.S.; Metsaev, R.R.

    1996-02-01

    Using the language of highest weight representations and the light cone formalism we construct a full list of cubic amplitudes of scattering for all bosonic massless representations of the Poincare group in any even space-time dimension. (author). 29 refs

  15. Fatigue crack shape prediction based on vertex singularity

    Czech Academy of Sciences Publication Activity Database

    Hutař, Pavel; Náhlík, Luboš

    2008-01-01

    Roč. 2, č. 1 (2008), s. 45-52 ISSN 1802-680X R&D Projects: GA ČR GA101/08/1623; GA ČR GP106/06/P239 Institutional research plan: CEZ:AV0Z20410507 Keywords : 3D vertex singularity * crack shape * fatigue crack propagation Subject RIV: JL - Materials Fatigue, Friction Mechanics

  16. Three-loop corrections to the soft anomalous dimension in multileg scattering

    CERN Document Server

    Almelid, Øyvind; Gardi, Einan

    2016-01-01

    We present the three-loop result for the soft anomalous dimension governing long-distance singularities of multi-leg gauge-theory scattering amplitudes of massless partons. We compute all contributing webs involving semi-infinite Wilson lines at three loops and obtain the complete three-loop correction to the dipole formula. We find that non-dipole corrections appear already for three coloured partons, where the correction is a constant without kinematic dependence. Kinematic dependence appears only through conformally-invariant cross ratios for four coloured partons or more, and the result can be expressed in terms of single-valued harmonic polylogarithms of weight five. While the non-dipole three-loop term does not vanish in two-particle collinear limits, its contribution to the splitting amplitude anomalous dimension reduces to a constant, and it only depends on the colour charges of the collinear pair, thereby preserving strict collinear factorization properties. Finally we verify that our result is consi...

  17. Light-cone gauge versus proper-time gauge for massless spinning particles

    International Nuclear Information System (INIS)

    Skagerstam, B.S.; Stern, A.

    1987-01-01

    Although the light-cone gauge is convenient for many applications in physics, it is known to distort topology. We show that as a consequence, some interesting, possibly physical, features of a quantum theory may be missed when working in the light-cone gauge. We shall illustrate this by examining the description of massless spinning particles in an arbitrary number of space-time dimensions. When quantizing such particles in four space-time dimensions (without introducing Grassmann degrees of freedom), the light-cone gauge yields a purely bosonic spectrum, i.e. the helicity λ is integer-valued. The problem is rectified by going to the proper-time gauge; there λ = 0, ±1/2, ±1, ... Upon using the proper-time gauge to quantize massless particle systems in more than four space-time dimensions, we find the following interesting features: Except for space-time dimension d equal to 5 and 9, (i) wave functions cannot be expressed as global functions of momentum (or position). (This is also true for d=4.) Further, for d ≠ 5 and 9, (ii) the helicity group spin (d-2) and (iii) canonical position operators do not exist, globally. (The result that helicity cannot be globally defined resembles a known property of nonabelian monopoles arising in grand unified theories. There, topological obstructions prevent one from defining the color group, globally.) All of the features (i)-(iii) are missed when working in the light-cone gauge. (orig.)

  18. Status of the CBM micro vertex detector

    Energy Technology Data Exchange (ETDEWEB)

    Koziel, Michal [Goethe-Universitaet Frankfurt (Germany); Collaboration: CBM-MVD-Collaboration

    2015-07-01

    The fixed-target experiment CBM at FAIR will explore the phase diagram of strongly interacting matter in the regime of highest net baryon densities with numerous probes, among them open charm. For the reconstruction of open charm hadrons with the CBM experiment a Micro Vertex Detector (MVD) with an excellent spatial resolution of the secondary decay vertex is required. Hence, a material budget of a few 0.1% X0 is mandatory for the individual detector stations positioned downstream in close vicinity to the target. To reduce multiple scattering, the MVD operates in vacuum, which poses challenging requirements on both, the power dissipation of the sensors and the integration concept. Here one should mention the selection of high-performance materials providing the mechanical support and cooling for the 0.05 mm thin sensors, establishing the sensor quality assessment procedures as well as defining the sensor integration. In addition, a substantial progress with respect to sensor development will be reported, mainly to the studies on their radiation hardness. Also, the 2nd generation of the sensor control and read-out based on TRBv3 standard has been commissioned. In this contribution we highlight several activities that have been successfully accomplished, which enable us to define the start version of the CBM MVD.

  19. Vertex maps on graphs -- Perron-Frobenius Theory

    OpenAIRE

    Bernhardt, Chris

    2015-01-01

    The goal of this paper is to describe the connections between Perron-Frobenius theory and vertex maps on graphs. In particular, it is shown how Perron-Frobenius theory gives results about the sets of integers that can arise as periods of periodic orbits, about the concepts of transitivity and topological mixing, and about horseshoes and topological entropy. This is a preprint. The final version will appear in the Journal of Difference Equations and Applications.

  20. Developments in solid state vertex detectors

    International Nuclear Information System (INIS)

    Damerell, C.J.S.

    1984-12-01

    Since the discovery of the J/psi in November 1974, there has been a strong interest in the physics of particles containing higher-flavour quarks (charm, bottom, top, ...). High precision vertex detectors can be used to identify the decay products of parent particles which have lifetimes of the order 10 -13 s. The paper surveys the progress which is being made in developing silicon detectors with the necessary tracking precision (< approx. 5 μm) to be used for this purpose in fixed target experiments and also in colliders such as SLC and LEP. (author)

  1. Silicon detectors for tracking and vertexing

    International Nuclear Information System (INIS)

    Nomerotski, Andrei

    2009-01-01

    This review covers recent developments in silicon detectors used for particle physics experiments for the tracking and vertexing systems. After a general introduction the main focus of the report is on new challenges for this field posed by requirements of the future generation machines. Technologies reviewed in more detail are column parallel CCDs, DEPFET, vertical integration of sensors and electronics and several others which allow fast readout and low mass design. Important system issues such as mechanical arrangements for the sensors and power distribution, which are critical for the low mass design, are also discussed.

  2. Constraint on the QED vertex from the mass anomalous dimension γm = 1

    International Nuclear Information System (INIS)

    Bashir, A.; Pennington, M.R.

    1995-10-01

    We discuss the structure of the non-perturbative fermion-boson vertex in quenched QED. We show that it is possible to construct a vertex which not only ensures that the fermion propagator is multiplicatively renormalizable, obeys the appropriate Ward-Takahashi identity, reproduces perturbation theory for weak couplings and guarantees that the critical coupling at which the mass is dynamically generated is gauge independent but also makes sure that the value for the anomalous dimension for the mass function is strictly 1, as Holdom and Mahanta have proposed. (author). 8 refs

  3. Recent developments in high precision vertex chambers at SLAC

    International Nuclear Information System (INIS)

    Rust, D.R.

    1984-04-01

    Three detectors MARK II, MAC, AND HRS are using or planning small drift chambers placed as close as possible to the interaction print at PEP. There is also a program of development for a gaseous vertex detector for MARK II at SLC. All these programs are reviewed. 13 references

  4. VXD3: The SLD vertex detector upgrade based on a 307 Mpixel CCD system

    International Nuclear Information System (INIS)

    1995-07-01

    The SLD Collaboration is building a new CCD vertex detector (VXD3) comprising 96 3.2 Mpixel CCDs of 13 cm 2 each for a total of 307 million pixels. This system is an upgrade of the Pioneering CCD vertex detector VXD2 which has operated in SLD since 1992. The CCDs of VXD3 are mounted on beryllium ladders in three cylinders, providing three space point measurements along each track of about 5 microns resolution in all three coordinates. The design and construction of VXD3 builds on three years of successful performance of VXD2. Significant improvements are achieved with VXD3 in impact parameters resolution (about a factor of two) and acceptance (∼20%) through optimized geometry and reduced material. New readout electronics have been developed for this system. This new vertex detector will be installed in late 1995 for the future runs of SLD

  5. Measurement of the charm and beauty structure functions using the H1 vertex detector at HERA

    International Nuclear Information System (INIS)

    Aaron, F.D.; Alexa, C.; Preda, T.; Rotaru, M.; Stoicea, G.; Zus, R.; Aldaya Martin, M.; Alimujiang, K.; Antunovic, B.; Bartel, W.; Brandt, G.; Campbell, A.J.; Cholewa, A.; Deak, M.; Boer, Y. de; Eckerlin, G.; Elsen, E.; Felst, R.; Fischer, D.J.; Fleischer, M.; Gayler, J.; Glazov, A.; Gouzevitch, M.; Grell, B.R.; Haidt, D.; Helebrant, C.; Janssen, M.E.; Jung, H.; Katzy, J.; Kleinwort, C.; Knutsson, A.; Kraemer, M.; Krastev, K.; Kutak, K.; Levonian, S.; Lipka, K.; List, J.; Marti, L.; Meyer, A.B.; Meyer, H.; Meyer, J.; Michels, V.; Niebuhr, C.; Nikiforov, A.; Nozicka, M.; Olsson, J.E.; Panagoulias, I.; Papadopoulou, T.; Pitzl, D.; Placakyte, R.; Radescu, V.; Rurikova, Z.; Schmitt, S.; Schoeffel, L.; Sefkow, F.; Staykova, Z.; Steder, M.; Vargas Trevino, A.; Vinokurova, S.; Driesch, M. von den; Wissing, C.; Wuensch, E.; Andreev, V.; Belousov, A.; Eliseev, A.; Fomenko, A.; Gogitidze, N.; Lebedev, A.; Loktionova, N.; Malinovski, E.; Rusakov, S.; Shtarkov, L.N.; Soloviev, Y.; Vazdik, Y.; Asmone, A.; Stella, B.; Backovic, S.; Dubak, A.; Lastovicka-Medin, G.; Picuric, I.; Raicevic, N.; Baghdasaryan, A.; Ghazaryan, S.; Volchinski, V.; Zohrabyan, H.; Barrelet, E.; Begzsuren, K.; Ravdandorj, T.; Tseepeldorj, B.; Bizot, J.C.; Brisson, V.; Delcourt, B.; Jacquet, M.; Li, G.; Pascaud, C.; Tran, T.H.; Zhang, Z.; Zomer, F.; Boudry, V.; Moreau, F.; Specka, A.; Bozovic-Jelisavcic, I.; Mudrinic, M.; Pandurovic, M.; Smiljanic, I.; Bracinik, J.; Kenyon, I.R.; Newman, P.R.; Shaw-West, R.N.; Thompson, P.D.; Brinkmann, M.; Habib, S.; List, B.; Pokorny, B.; Toll, T.; Bruncko, D.; Cerny, V.; Ferencei, J.; Murin, P.; Tomasz, F.; Bunyatyan, A.; Buschhorn, G.; Chekelian, V.; Dossanov, A.; Grindhammer, G.; Kiesling, C.; Kogler, R.; Liptaj, A.; Olivier, B.; Raspiareza, A.; Shushkevich, S.; Bystritskaya, L.; Efremenko, V.; Fedotov, A.; Kropivnitskaya, A.; Lubimov, V.; Ozerov, D.; Petrukhin, A.; Rostovtsev, A.; Zhokin, A.; Cantun Avila, K.B.; Contreras, J.G.; Ruiz Tabasco, J.E.; Cassol-Brunner, F.; Diaconu, C.; Hoffmann, D.; Sauvan, E.; Trinh, T.N.; Vallee, C.; Cerny, K.; Pejchal, O.; Polifka, R.; Salek, D.; Valkarova, A.; Zacek, J.; Coughlan, J.A.; Morris, J.V.; Sankey, D.P.C.; Cozzika, G.; Feltesse, J.; Perez, E.; Cvach, J.; Reimer, P.; Zalesak, J.; Dainton, J.B.; Gabathuler, E.; Greenshaw, T.; Klein, M.; Kluge, T.; Kretzschmar, J.; Laycock, P.; Maxfield, S.J.; Mehta, A.; Patel, G.D.; Rahmat, A.J.; Daum, K.; Meyer, H.; Del Degan, M.; Grab, C.; Leibenguth, G.; Sauter, M.; Zimmermann, T.; Delvax, J.; Wolf, E.A. de; Favart, L.; Hreus, T.; Janssen, X.; Marage, P.; Mozer, M.U.; Roland, B.; Roosen, R.; Sunar, D.; Sykora, T.; Mechelen, P. van; Dodonov, V.; Lytkin, L.; Povh, B.; Egli, S.; Hildebrandt, M.; Horisberger, R.; Falkiewicz, A.; Goerlich, L.; Mikocki, S.; Milcewicz-Mika, I.; Nowak, G.; Sopicki, P.; Turnau, J.; Glushkov, I.; Henschel, H.; Hiller, K.H.; Kostka, P.; Lange, W.; Naumann, T.; Piec, S.; Henderson, R.C.W.; Sloan, T.; Hennekemper, E.; Herbst, M.; Jung, A.W.; Krueger, K.; Lendermann, V.; Schultz-Coulon, H.C.; Urban, K.; Herrera, G.; Lopez-Fernandez, R.; Joensson, L.; Osman, S.; Kapichine, M.; Makankine, A.; Morozov, A.; Palichik, V.; Spaskov, V.; Tchoulakov, V.; Landon, M.P.J.; Rizvi, E.; Thompson, G.; Traynor, D.; Martyn, H.U.; Mueller, K.; Nowak, K.; Robmann, P.; Straumann, U.; Truoel, P.; Schoening, A.; South, D.; Wegener, D.; Tsakov, I.

    2010-01-01

    Inclusive charm and beauty cross sections are measured in e - p and e + p neutral current collisions at HERA in the kinematic region of photon virtuality 5≤Q 2 ≤2000 GeV 2 and Bjorken scaling variable 0.0002≤x≤0.05. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of 189 pb -1 . The numbers of charm and beauty events are determined using variables reconstructed by the H1 vertex detector including the impact parameter of tracks to the primary vertex and the position of the secondary vertex. The measurements are combined with previous data and compared to QCD predictions. (orig.)

  6. Measurement of the Charm and Beauty Structure Functions using the H1 Vertex Detector at HERA

    CERN Document Server

    Aaron, FD; Alexa, C; Alimujiang, K; Andreev, V; Antunovic, B; Asmone, A; Backovic, S; Baghdasaryan, A; Barrelet, E; Bartel, W; Begzsuren, K; Belousov, A; Bizot, J C; Boudry, V; Bozovic-Jelisavcic, I; Bracinik, J; Brandt, G; Brinkmann, M; Brisson, V; Bruncko, D; Bunyatyan, A; Buschhorn, G; Bystritskaya, L; Campbell, A J; Cantun Avila, K B; Cassol-Brunner, F; Cerny, K; Cerny, V; Chekelian, V; Cholewa, A; Contreras, J G; Coughlan, J A; Cozzika, G; Cvach, J; Dainton, J B; Daum, K; Deak, M; de Boer, Y; Delcourt, B; Del Degan, M; Delvax, J; De Wolf, E A; Diaconu, C; Dodonov, V; Dossanov, A; Dubak, A; Eckerlin, G; Efremenko, V; Egli, S; Eliseev, A; Elsen, E; Falkiewicz, A; Favart, L; Fedotov, A; Felst, R; Feltesse, J; Ferencei, J; Fischer, D -J; Fleischer, M; Fomenko, A; Gabathuler, E; Gayler, J; Ghazaryan, Samvel; Glazov, A; Glushkov, I; Goerlich, L; Gogitidze, N; Gouzevitch, M; Grab, C; Greenshaw, T; Grell, B R; Grindhammer, G; Habib, S; Haidt, D; Helebrant, C; Henderson, R C W; Hennekemper, E; Henschel, H; Herbst, M; Herrera, G; Hildebrandt, M; Hiller, K H; Hoffmann, D; Horisberger, R; Hreus, T; Jacquet, M; Janssen, M E; Janssen, X; Jonsson, L; Jung, Andreas Werner; Jung, H; Kapichine, M; Katzy, J; Kenyon, I R; Kiesling, C; Klein, M; Kleinwort, C; Kluge, T; Knutsson, A; Kogler, R; Kostka, P; Kraemer, M; Krastev, K; Kretzschmar, J; Kropivnitskaya, A; Kruger, K; Kutak, K; Landon, M P J; Lange, W; Lastovicka-Medin, G; Laycock, P; Lebedev, A; Leibenguth, G; Lendermann, V; Levonian, S; Li, G; Lipka, K; Liptaj, A; List, B; List, J; Loktionova, N; Lopez-Fernandez, R; Lubimov, V; Lytkin, L; Makankine, A; Malinovski, E; Marage, P; Marti, Ll; Martyn, H -U; Maxfield, S J; Mehta, A; Meyer, A B; Meyer, H; Meyer, H; Meyer, J; Michels, V; Mikocki, S; Milcewicz-Mika, I; Moreau, F; Morozov, A; Morris, J V; Mozer, Matthias Ulrich; Mudrinic, M; Muller, K; Murin, P; Naumann, Th; Newman, P R; Niebuhr, C; Nikiforov, A; Nowak, G; Nowak, K; Nozicka, M; Olivier, B; Olsson, J E; Osman, S; Ozerov, D; Palichik, V; Panagoulias, I; Pandurovic, M; Papadopoulou, Th; Pascaud, C; Patel, G D; Pejchal, O; Perez, E; Petrukhin, A; Picuric, I; Piec, S; Pitzl, D; Placakyte, R; Pokorny, B; Polifka, R; Povh, B; Preda, T; Radescu, V; Rahmat, A J; Raicevic, N; Raspiareza, A; Ravdandorj, T; Reimer, P; Rizvi, E; Robmann, P; Roland, B; Roosen, R; Rostovtsev, A; Rotaru, M; Ruiz Tabasco, J E; Rurikova, Z; Rusakov, S; Salek, D; Sankey, D P C; Sauter, M; Sauvan, E; Schmitt, S; Schoeffel, L; Schoning, A; Schultz-Coulon, H -C; Sefkow, F; Shaw-West, R N; Shtarkov, L N; Shushkevich, S; Sloan, T; Smiljanic, Ivan; Soloviev, Y; Sopicki, P; South, D; Spaskov, V; Specka, Arnd E; Staykova, Z; Steder, M; Stella, B; Stoicea, G; Straumann, U; Sunar, D; Sykora, T; Tchoulakov, V; Thompson, G; Thompson, P D; Toll, T; Tomasz, F; Tran, T H; Traynor, D; Trinh, T N; Truol, P; Tsakov, I; Tseepeldorj, B; Turnau, J; Urban, K; Valkarova, A; Vallee, C; Van Mechelen, P; Vargas Trevino, A; Vazdik, Y; Vinokurova, S; Volchinski, V; von den Driesch, M; Wegener, D; Wissing, Ch; Wunsch, E; Zacek, J; Zalesak, J; Zhang, Z; Zhokin, A; Zimmermann, T; Zohrabyan, H; Zomer, F; Zus, R

    2010-01-01

    Inclusive charm and beauty cross sections are measured in e-p and e+p neutral current collisions at HERA in the kinematic region of photon virtuality 5vertex detector including the impact parameter of tracks to the primary vertex and the position of the secondary vertex. The measurements are combined with previous data and compared to QCD predictions.

  7. Performance of the CDF Silicon VerteX detector

    International Nuclear Information System (INIS)

    Schneider, O.

    1992-11-01

    The current status of the online and offline performance of the CDF Silicon VerteX detector is presented. So far, at low radiation dose, the device delivers good quality data. After the latest alignment using collision data, a spatial resolution of 13 pm is achieved in the transverse plane, demonstrating that CDF has a powerful tool to detect b decay vertices

  8. The Mark III vertex chamber: Studies using DME

    International Nuclear Information System (INIS)

    Pitman, D.

    1987-04-01

    Studies have been performed using a prototype of a pressurized wire vertex chamber with 8 mm diameter straw geometry. A 35 μm spatial resolution using dimethyl ether (DME) at 1 bar and 30 μm using argon ethane (50/50 mixture) at 4 bar was obtained. Preliminary studies show the DME to adversely affect such materials as aluminized Mylar and Delrin

  9. Simultaneous dense coding affected by fluctuating massless scalar field

    Science.gov (United States)

    Huang, Zhiming; Ye, Yiyong; Luo, Darong

    2018-04-01

    In this paper, we investigate the simultaneous dense coding (SDC) protocol affected by fluctuating massless scalar field. The noisy model of SDC protocol is constructed and the master equation that governs the SDC evolution is deduced. The success probabilities of SDC protocol are discussed for different locking operators under the influence of vacuum fluctuations. We find that the joint success probability is independent of the locking operators, but other success probabilities are not. For quantum Fourier transform and double controlled-NOT operators, the success probabilities drop with increasing two-atom distance, but SWAP operator is not. Unlike the SWAP operator, the success probabilities of Bob and Charlie are different. For different noisy interval values, different locking operators have different robustness to noise.

  10. Convergence of the Stochastic Six-Vertex Model to the ASEP

    Energy Technology Data Exchange (ETDEWEB)

    Aggarwal, Amol, E-mail: amolaggarwal@g.harvard.edu [Harvard University Cambridge (United States)

    2017-06-15

    In this note we establish the convergence of the stochastic six-vertex model to the one-dimensional asymmetric simple exclusion process, under a certain limit regime recently predicted by Borodin-Corwin-Gorin. This convergence holds for arbitrary initial data.

  11. Free massless fermionic fields of arbitrary spin in d-dimensional anti-de Sitter space

    Energy Technology Data Exchange (ETDEWEB)

    Vasiliev, M A

    1988-04-25

    Free massless fermionic fields of arbitrary spins, corresponding to fully symmetric tensor-spinor irreducible representations of the flat little group SO(d-2), are described in d-dimensional anti-de Sitter space in terms of differential forms. Appropriate linearized higher-spin curvature 2-forms are found. Explicitly gauge invariant higher-spin actions are constructed in terms of these linearized curvatures.

  12. The classical electromagnetic theory which corresponds to the two dimensions quantum electrodynamics with massless fermions

    International Nuclear Information System (INIS)

    Galvao, C.A.P.; Mignaco, J.A.

    1994-01-01

    The classical electromagnetic theory is analysed which corresponds to the two-dimensional quantum electrodynamics with massless spinor fields (Schwinger model). The chiral anomaly is introduced as a currents property, which in the two-dimensional spinor fields are duality related. It is also shown that the resulting classical theory is consistent. (author). 5 refs

  13. Infrared finite ghost propagator in the Feynman gauge

    International Nuclear Information System (INIS)

    Aguilar, A. C.; Papavassiliou, J.

    2008-01-01

    We demonstrate how to obtain from the Schwinger-Dyson equations of QCD an infrared finite ghost propagator in the Feynman gauge. The key ingredient in this construction is the longitudinal form factor of the nonperturbative gluon-ghost vertex, which, contrary to what happens in the Landau gauge, contributes nontrivially to the gap equation of the ghost. The detailed study of the corresponding vertex equation reveals that in the presence of a dynamical infrared cutoff this form factor remains finite in the limit of vanishing ghost momentum. This, in turn, allows the ghost self-energy to reach a finite value in the infrared, without having to assume any additional properties for the gluon-ghost vertex, such as the presence of massless poles. The implications of this result and possible future directions are briefly outlined

  14. Free massless fields of arbitrary spin in the de Sitter space and initial data for a higher spin superalgebra

    Energy Technology Data Exchange (ETDEWEB)

    Vasiliev, M A

    1987-11-01

    Linearized curvatures are constructed for massless higher spin fields on the (anti-) de Sitter background. The quite uniform description for free massless fields of all integer and half-integer spins s greater than or equal to 3/2 is presented, based on these curvatures. In particular, the actions and the equations of motion are given in a simple form. The proposed linearized curvatures provide 'initial data' for determination of a non-Abelian higher spin symmetry that may correspond to a hypothetical non-trivial theory of higher spins interacting with gravity and themselves. It is noted that the conjugation law for fermion fields should be modified drastically after transition from the anti-de-Sitter geometry to the de Sitter one.

  15. General Vertex-Distinguishing Total Coloring of Graphs

    Directory of Open Access Journals (Sweden)

    Chanjuan Liu

    2014-01-01

    Full Text Available The general vertex-distinguishing total chromatic number of a graph G is the minimum integer k, for which the vertices and edges of G are colored using k colors such that any two vertices have distinct sets of colors of them and their incident edges. In this paper, we figure out the exact value of this chromatic number of some special graphs and propose a conjecture on the upper bound of this chromatic number.

  16. Primary vertex reconstruction with the ATLAS detector

    International Nuclear Information System (INIS)

    Meloni, F.

    2016-01-01

    Efficient and precise reconstruction of the primary vertex in a LHC collision is essential for determining the full kinematic properties of a hard-scatter event and of soft interactions as a measure of the amount of pile-up. The reconstruction of primary vertices in the busy, high pile-up environment of Run-2 of the LHC is a challenging task. The algorithms developed by the ATLAS experiments to reconstruct multiple vertices with small spatial separation are presented.

  17. Revisiting light stringy states in view of the 750 GeV diphoton excess

    Energy Technology Data Exchange (ETDEWEB)

    Anastasopoulos, Pascal, E-mail: pascal@hep.itp.tuwien.ac.at [Technische Universität Wien, Institut für Theoretische Physik, A-1040 Vienna (Austria); Bianchi, Massimo, E-mail: massimo.bianchi@roma2.infn.it [Dipartimento di Fisica and Sezione I.N.F.N., Università di Roma “Tor Vergata”, Via della Ricerca Scientifica 1, 00133 Roma (Italy)

    2016-10-15

    We investigate light massive string states that appear at brane intersections. They replicate the massless spectrum in a richer fashion and may be parametrically lighter than standard Regge excitations. We identify the first few physical states and determine their BRST invariant vertex operators. In the supersymmetric case we reconstruct the super-multiplet structure. We then compute some simple interactions, such as the decay rate of a massive scalar or vector into two massless fermions. Finally we suggest an alternative interpretation of the 750 GeV diphoton excess at LHC in terms of a light massive string state, a replica of the Standard Model Higgs.

  18. Three-loop massive form factors: complete light-fermion corrections for the vector current

    Science.gov (United States)

    Lee, Roman N.; Smirnov, Alexander V.; Smirnov, Vladimir A.; Steinhauser, Matthias

    2018-03-01

    We compute the three-loop QCD corrections to the massive quark-anti-quark-photon form factors F 1 and F 2 involving a closed loop of massless fermions. This subset is gauge invariant and contains both planar and non-planar contributions. We perform the reduction using FIRE and compute the master integrals with the help of differential equations. Our analytic results can be expressed in terms of Goncharov polylogarithms. We provide analytic results for all master integrals which are not present in the large- N c calculation considered in refs. [1, 2].

  19. Geometric representation of the generator of duality in massless and massive p-form field theories

    International Nuclear Information System (INIS)

    Contreras, Ernesto; Martinez, Yisely; Leal, Lorenzo

    2010-01-01

    We study the invariance under duality transformations in massless and massive p-form field theories and obtain the Noether generators of the infinitesimal transformations that correspond to this symmetry. These generators can be realized in geometrical representations that generalize the loop representation of the Maxwell field, allowing for a geometrical interpretation which is studied.

  20. Regulating the infrared by mode matching: a massless scalar in expanding spaces with constant deceleration

    NARCIS (Netherlands)

    Janssen, T.M.; Prokopec, T.

    2011-01-01

    In this paper we consider a massless scalar field, with a possible coupling ξ to the Ricci scalar in a D dimensional Friedmann-Lemaître-Robertson-Walker space-time with a constant deceleration parameter q=ϵ-1, ϵ=-H˙/H2. Correlation functions for the Bunch-Davies vacuum of such a theory have long

  1. Lifetime tests for MAC vertex chamber

    International Nuclear Information System (INIS)

    Nelson, H.

    1986-01-01

    A vertex chamber for MAC was proposed in fall 1983 to increase precision in the measurement of the B hadron and tau lepton lifetimes. The chamber had to be placed within the existing central drift chamber, making access for repairs difficult and costly. Therefore for detector elements thin-walled aluminized mylar drift tubes (straws) were used because of their simplicity and robustness. The diameter of the drift tubes was 6.9 mm. The radial extent of the proposed chamber was from 3 cm to 10 cm, the inner wall of the central drift. It was clear that radiation levels, from synchrotron x-rays and overfocussed electrons, were potentially high. Since the drift distance is short in the straws, it was desirable to operate them at the highest possible gas gain, to achieve the best spatial resolution. There was a likelihood of drawing large currents in the chamber and thus causing radiation damage. Therefore a study of radiation hardness under the conditions of their proposed design was undertaken. In tests, argon-hydrocarbon mixtures consistently became unusable at ∼0.05 C/cm collected charge, due to anode buildup. Argon-CO 2 mixtures, while underquenched, were operational to 0.25 C/cm, at which point loss of cathode material became intolerable. Argon-xenon-CO 2 proved to be quenched as well as argon-hydrocarbons, but was limited by cathode damage. The MAC vertex chamber has operated at a distance of 4.6 cm from the e + e - interaction point at PEP for two years and has shown no aging effects

  2. N-point g-loop vertex for a free fermionic theory with arbitrary spin

    International Nuclear Information System (INIS)

    Di Vecchia, P.; Pezzella, F.; Frau, M.; Hornfeck, K.

    1990-01-01

    We use the sewing procedure of the operator formalism to construct explicitly the N-point g-loop vertex V N;g for a free fermionic (b, c)-system with conformal weight (λ, 1-λ). We show that this vertex has the structure we expect from geometrical arguments. We obtain also several geometrical objects, e.g. the holomorphic λ-differentials on an arbitrary Riemann surface, which turn out to be expressed as a Poincare θ-series over all elements of the Schottky group. From V N;g we compute explicitly correlation functions for our system, finding agreement with the geometrical procedure. (orig.)

  3. N-point g-loop vertex for a free fermionic theory with arbitrary spin

    International Nuclear Information System (INIS)

    Di Vecchia, P.; Pezzella, F.; Frau, M.; Hornfeck, K.

    1989-07-01

    We use the sewing procedure of the operator fomalism to construct explicitly the N-Point g-Loop Vertex V N;g for a free fermionic (b, c)-system with conformal weight (λ, 1-λ). We show that this Vertex has the structure we expect from geometrical arguments. We obtain also several geometrical objects, e.g. the holomorphic λ differentials on an arbitrary Riemann surface, which turn out to be expressed as a Poincare θ series over all elements of the Schottky group. From V N;g we compute explicitly correlation functions for our system, finding agreement with the geometrical procedure. (orig.)

  4. On D-brane anti D-brane effective actions and their corrections to all orders in alpha-prime

    International Nuclear Information System (INIS)

    Hatefi, Ehsan

    2013-01-01

    Based on a four point function, the S-matrix elements at disk level of the scattering amplitude of one closed string Ramond-Ramond field (C) and two tachyons and one scalar field, we find out new couplings in brane anti brane effective actions for p = n, p+2 = n cases. Using the infinite corrections of the vertex of one RR, one gauge and one scalar field and applying the correct expansion, it is investigated in detail how we produce the infinite gauge poles of the amplitude for p = n case. By discovering new higher derivative corrections of two tachyon-two scalar couplings in brane anti brane systems to all orders in α', we also obtain the infinite scalar poles in (t'+s'+u)-channel in field theory. Working with the complete form of the amplitude with the closed form of the expansion and comparing all the infinite contact terms of this amplitude, we derive several new Wess-Zumino couplings with all their infinite higher derivative corrections in the world volume of brane anti brane systems. In particular, in producing all the infinite scalar poles of C V φ V T V T > , one has to consider the fact that scalar's vertex operator in (-1)-picture must carry the internal σ 3 Chan-Paton matrix. The symmetric trace effective action has a non-zero coupling between Dφ (1)i and Dφ (2) i while this coupling does not exist in ordinary trace effective action

  5. Lattice Hamiltonian approach to the massless Schwinger model. Precise extraction of the mass gap

    International Nuclear Information System (INIS)

    Cichy, Krzysztof; Poznan Univ.; Kujawa-Cichy, Agnieszka; Szyniszewski, Marcin; Manchester Univ.

    2012-12-01

    We present results of applying the Hamiltonian approach to the massless Schwinger model. A finite basis is constructed using the strong coupling expansion to a very high order. Using exact diagonalization, the continuum limit can be reliably approached. This allows to reproduce the analytical results for the ground state energy, as well as the vector and scalar mass gaps to an outstanding precision better than 10 -6 %.

  6. Axial gravity, massless fermions and trace anomalies

    International Nuclear Information System (INIS)

    Bonora, L.; Cvitan, M.; Giaccari, S.; Stemberga, T.; Prester, P.D.; Pereira, A.D.; UFF-Univ. Federal Fluminense, Niteroi

    2017-01-01

    This article deals with two main topics. One is odd parity trace anomalies in Weyl fermion theories in a 4d curved background, the second is the introduction of axial gravity. The motivation for reconsidering the former is to clarify the theoretical background underlying the approach and complete the calculation of the anomaly. The reference is in particular to the difference between Weyl and massless Majorana fermions and to the possible contributions from tadpole and seagull terms in the Feynman diagram approach. A first, basic, result of this paper is that a more thorough treatment, taking account of such additional terms and using dimensional regularization, confirms the earlier result. The introduction of an axial symmetric tensor besides the usual gravitational metric is instrumental to a different derivation of the same result using Dirac fermions, which are coupled not only to the usual metric but also to the additional axial tensor. The action of Majorana and Weyl fermions can be obtained in two different limits of such a general configuration. The results obtained in this way confirm the previously obtained ones. (orig.)

  7. Axial gravity, massless fermions and trace anomalies

    Energy Technology Data Exchange (ETDEWEB)

    Bonora, L. [International School for Advanced Studies (SISSA), Trieste (Italy); KEK, Tsukuba (Japan). KEK Theory Center; INFN, Sezione di Trieste (Italy); Cvitan, M.; Giaccari, S.; Stemberga, T. [Zagreb Univ. (Croatia). Dept. of Physics; Prester, P.D. [Rijeka Univ. (Croatia). Dept. of Physics; Pereira, A.D. [UERJ-Univ. Estadual do Rio de Janeiro (Brazil). Dept. de Fisica Teorica; UFF-Univ. Federal Fluminense, Niteroi (Brazil). Inst. de Fisica

    2017-08-15

    This article deals with two main topics. One is odd parity trace anomalies in Weyl fermion theories in a 4d curved background, the second is the introduction of axial gravity. The motivation for reconsidering the former is to clarify the theoretical background underlying the approach and complete the calculation of the anomaly. The reference is in particular to the difference between Weyl and massless Majorana fermions and to the possible contributions from tadpole and seagull terms in the Feynman diagram approach. A first, basic, result of this paper is that a more thorough treatment, taking account of such additional terms and using dimensional regularization, confirms the earlier result. The introduction of an axial symmetric tensor besides the usual gravitational metric is instrumental to a different derivation of the same result using Dirac fermions, which are coupled not only to the usual metric but also to the additional axial tensor. The action of Majorana and Weyl fermions can be obtained in two different limits of such a general configuration. The results obtained in this way confirm the previously obtained ones. (orig.)

  8. Veselago focusing of anisotropic massless Dirac fermions

    Science.gov (United States)

    Zhang, Shu-Hui; Yang, Wen; Peeters, F. M.

    2018-05-01

    Massless Dirac fermions (MDFs) emerge as quasiparticles in various novel materials such as graphene and topological insulators, and they exhibit several intriguing properties, of which Veselago focusing is an outstanding example with a lot of possible applications. However, up to now Veselago focusing merely occurred in p-n junction devices based on the isotropic MDF, which lacks the tunability needed for realistic applications. Here, motivated by the emergence of novel Dirac materials, we investigate the propagation behaviors of anisotropic MDFs in such a p-n junction structure. By projecting the Hamiltonian of the anisotropic MDF to that of the isotropic MDF and deriving an exact analytical expression for the propagator, precise Veselago focusing is demonstrated without the need for mirror symmetry of the electron source and its focusing image. We show a tunable focusing position that can be used in a device to probe masked atom-scale defects. This study provides an innovative concept to realize Veselago focusing relevant for potential applications, and it paves the way for the design of novel electron optics devices by exploiting the anisotropic MDF.

  9. The Mark II Vertex Drift Chamber

    International Nuclear Information System (INIS)

    Alexander, J.P.; Baggs, R.; Fujino, D.

    1989-03-01

    We have completed constructing and begun operating the Mark II Drift Chamber Vertex Detector. The chamber, based on a modified jet cell design, achieves 30 μm spatial resolution and 2 gas mixtures. Special emphasis has been placed on controlling systematic errors including the use of novel construction techniques which permit accurate wire placement. Chamber performance has been studied with cosmic ray tracks collected with the chamber located both inside and outside the Mark II. Results on spatial resolution, average pulse shape, and some properties of CO 2 mixtures are presented. 10 refs., 12 figs., 1 tab

  10. The ZEUS vertex detector: Design and prototype

    International Nuclear Information System (INIS)

    Alvisi, C.; Anzivino, G.; Arzarello, F.; Barbagli, G.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, G.; Bruni, P.; Camerini, U.; Cara Romeo, G.; Castellini, G.; Chiarini, M.; Cifarelli, L.; Cindolo, F.; Ciralli, F.; Contin, A.; Costa, M.; D'Auria, S.; Del Papa, C.; De Pasquale, S.; Fiori, F.; Forte, A.; Frasconi, F.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Lisowski, B.; Maccarrone, G.; Margotti, A.; Massam, T.; Nania, R.; O'Shea, V.; Palmonari, F.; Pelfer, P.; Pilastrini, R.; Qian, S.; Sartorelli, G.; Schioppa, M.; Susinno, G.; Timellini, R.; Zichichi, A.; Bologna Univ.; Cosenza Univ.; Florence Univ.; Istituto Nazionale di Fisica Nucleare, Bologna; Istituto Nazionale di Fisica Nucleare, Florence; Istituto Nazionale di Fisica Nucleare, Frascati; Consiglio Nazionale delle Ricerche, Florence

    1991-01-01

    A gas vertex detector, operated with dimethylether (DME) at atmospheric pressure, is presently being built for the ZEUS experiment at HERA. Its main design features, together with the performances of a prototype measured at various operating voltages, particle rates and geometrical conditions on a CERN Proton Synchrotron test beam, are presented. A spatial resolution down to 35 μm and an average wire efficiency of 96% have been achieved, for a 3 mm gas gap relative to each sense wire. (orig.)

  11. Readout ASIC for ILC-FPCCD vertex detector

    International Nuclear Information System (INIS)

    Takubo, Yosuke; Miyamoto, Akiya; Ikeda, Hirokazu; Yamamoto, Hitoshi; Itagaki, Kennosuke; Nagamine, Tadashi; Sugimoto, Yasuhiro

    2010-01-01

    The concept of FPCCD (Fine Pixel CCD) whose pixel size is 5x5μm 2 has been proposed as vertex detector at ILC. Since FPCCD has 128 x20,000 pixels in one readout channel, its readout poses a considerable challenge. We have developed a prototype of readout ASIC to readout the large number of pixels during the inter-train gap of the ILC beam. In this paper, we report the design and performance of the readout ASIC.

  12. Silicon vertex tracker for RHIC PHENIX experiment

    Energy Technology Data Exchange (ETDEWEB)

    Taketani, A [RIKEN, Nishina Ctr Accelerator Based Sci, Wako, Saitama, Japan; Cianciolo, Vince [ORNL; Enokizono, Akitomo [Oak Ridge National Laboratory (ORNL); PHENIX, Collaboration [The

    2010-01-01

    The PHENIX experiment at Relativistic Heavy Ion Collider will be equipped with Silicon Vertex tracker to enhance its physics capability. There are four layers of silicon sensor to reconstruct charged tracks with 50 {micro}m resolution of decay length measurement. The VTX surrounds the collision point. The inner two layers and the outer two layers are composed of 30 pixel ladders and 44 stripixel ladders, respectively. We have been developing these detectors and done a performance test with 120 GeV proton beam.

  13. The Belle II silicon vertex detector assembly and mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Adamczyk, K. [H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342 (Poland); Aihara, H. [Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan); Angelini, C. [Dipartimento di Fisica, Università di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Aziz, T.; Babu, V. [Tata Institute of Fundamental Research, Mumbai 400005 (India); Bacher, S. [H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342 (Poland); Bahinipati, S. [Indian Institute of Technology Bhubaneswar, Satya Nagar (India); Barberio, E.; Baroncelli, Ti.; Baroncelli, To. [School of Physics, University of Melbourne, Melbourne, Victoria 3010 (Australia); Basith, A.K. [Indian Institute of Technology Madras, Chennai 600036 (India); Batignani, G. [Dipartimento di Fisica, Università di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Bauer, A. [Institute of High Energy Physics, Austrian Academy of Sciences, 1050 Vienna (Austria); Behera, P.K. [Indian Institute of Technology Madras, Chennai 600036 (India); Bergauer, T. [Institute of High Energy Physics, Austrian Academy of Sciences, 1050 Vienna (Austria); Bettarini, S., E-mail: stefano.bettarini@pi.infn.it [Dipartimento di Fisica, Università di Pisa, I-56127 Pisa (Italy); INFN Sezione di Pisa, I-56127 Pisa (Italy); Bhuyan, B. [Indian Institute of Technology Guwahati, Assam 781039 (India); Bilka, T. [Faculty of Mathematics and Physics, Charles University, 121 16 Prague (Czech Republic); Bosi, F. [INFN Sezione di Pisa, I-56127 Pisa (Italy); Bosisio, L. [Dipartimento di Fisica, Università di Trieste, I-34127 Trieste (Italy); INFN Sezione di Trieste, I-34127 Trieste (Italy); and others

    2017-02-11

    The Belle II experiment at the asymmetric SuperKEKB collider in Japan will operate at an instantaneous luminosity approximately 50 times greater than its predecessor (Belle). The central feature of the experiment is a vertex detector comprising two layers of pixelated silicon detectors (PXD) and four layers of double-sided silicon microstrip detectors (SVD). One of the key measurements for Belle II is CP violation asymmetry in the decays of beauty and charm hadrons, which hinges on a precise charged-track vertex determination and low-momentum track measurement. Towards this goal, a proper assembly of the SVD components with precise alignment ought to be performed and the geometrical tolerances should be checked to fall within the design limits. We present an overview of the assembly procedure that is being followed, which includes the precision gluing of the SVD module components, wire-bonding of the various electrical components, and precision 3D coordinate measurements of the final SVD modules. Finally, some results from the latest test-beam are reported.

  14. Structure of the vertex function in finite quantum electrodynamics

    International Nuclear Information System (INIS)

    Mannheim, P.D.

    1975-01-01

    We study the structure of the renormalized electromagnetic current vertes, GAMMA-tilde/sub μ/(p,p+q,q), in finite quantum electrodynamics. Using conformal invariance we find that GAMMA-tilde/sub μ/(p,p,0) takes the simple form of Z 1 γ/sub μ/ when the external fermions are far off the mass shell. We interpret this result as an old theorem on the structure of the vertex function due to Gell--Mann and Zachariasen. We give the general structure of the vertex for arbitrary momentum transfer parametrically, and discuss how the Bethe--Salpeter equation and the Federbush--Johnson theorem are satisfied. We contrast the meaning of pointlike in a finite field theory with the meaning understood in the parton model. We discuss to what extent the condition Z 1 = 0, which may hold in conformal theories other than finite quantum electrodynamics, may be interpreted as a bootstrap condition. We show that the vanishing of Z 1 prevents their being bound states in the Migdal--Polyakov bootstrap

  15. An analytic distribution function for a mass-less cored stellar system in a cuspy dark-matter halo

    NARCIS (Netherlands)

    Breddels, Maarten A.; Helmi, Amina

    2013-01-01

    We demonstrate the existence of a distribution function that can be used to represent spherical mass-less cored stellar systems having constant mildly tangential velocity anisotropy embedded in cuspy dark-matter halos. In particular, we derived analytically the functional form of the distribution

  16. 2D massless QED Hall half-integer conductivity and graphene

    International Nuclear Information System (INIS)

    Martínez, A Pérez; Querts, E Rodriguez; Rojas, H Pérez; Gaitan, R; Rodriguez-Romo, S

    2011-01-01

    Starting from the photon self-energy tensor in a magnetized medium, the 3D complete antisymmetric form of the conductivity tensor is found in the static limit of a fermion system C-non-invariant under fermion–antifermion exchange. The massless relativistic 2D fermion limit in QED is derived by using the compactification along the dimension parallel to the magnetic field. In the static limit and at zero temperature, the main features of the quantum Hall effect (QHE) are obtained: the half-integer QHE and the minimum value proportional to e 2 /h for the Hall conductivity. For typical values of graphene the plateaus of the Hall conductivity are also reproduced. (paper)

  17. A non-perturbative approach to the Coleman-Weinberg mechanism in massless scalar QED

    International Nuclear Information System (INIS)

    Malbouisson, A.P.C.; Nogueira, F.S.; Svaiter, N.F.

    1995-08-01

    We rederived non-perturbatively the Coleman-Weinberg expression for the effective potential for massless scalar QED. Our result is not restricted to small values of the coupling constants. This shows that the Coleman-Weinberg result can be established beyond the range of perturbation theory. Also, we derive it in a manifestly renormalization group invariant way. It is shown that with the derivation given no Landau ghost singularity arises. The finite temperature case is discussed. (author). 13 refs

  18. Silicon vertex detector upgrade in the ALPHA experiment

    CERN Document Server

    Amole, C; Ashkezari, M.D; Baquero-Ruiz, M; Bertsche, W; Burrows, C; Butler, E; Capra, A; Cesar, C.L; Chapman, S; Charlton, M; Deller, A; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M.C; Gill, D.R; Gutierrez, A; Hangst, J.S; Hardy, W.N; Hayden, M.E; Humphries, A.J; Isaac, C.A; Jonsell, S; Kurchaninov, L; Little, A; Madsen, N; McKenna, J.T.K; Menary, S; Napoli, S.C; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Rasmussen, C.Ø; Robicheaux, F; Sacramento, R.L; Sampson, J.A; Sarid, E; Seddon, D; Silveira, D.M; So, C; Stracka, S; Tharp, T; Thompson, R.I; Thornhill, J; Tooley, M.P; Van Der Werf, D.P; Wells, D

    2013-01-01

    The Silicon Vertex Detector (SVD) is the main diagnostic tool in the ALPHA-experiment. It provides precise spatial and timing information of antiproton (antihydrogen) annihilation events (vertices), and most importantly, the SVD is capable of directly identifying and analysing single annihilation events, thereby forming the basis of ALPHA ' s analysis. This paper describes the ALPHA SVD and its upgrade, installed in the ALPHA ' s new neutral atom trap.

  19. Silicon vertex detector upgrade in the ALPHA experiment

    Energy Technology Data Exchange (ETDEWEB)

    Amole, C. [Department of Physics and Astronomy, York University, Toronto, ON, M3J 1P3 (Canada); Andresen, G.B. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Ashkezari, M.D. [Department of Physics, Simon Fraser University, Burnaby, BC, V5A 1S6 (Canada); Baquero-Ruiz, M. [Department of Physics, University of California at Berkeley, Berkeley, CA 94720-7300 (United States); Bertsche, W. [School of Physics and Astronomy, University of Manchester, M13 9PL Manchester (United Kingdom); The Cockcroft Institute, Daresbury Laboratory, WA4 4AD Warrington (United Kingdom); Burrows, C. [Department of Physics, College of Science, Swansea University, Swansea SA2 8PP (United Kingdom); Butler, E. [Physics Department, CERN, CH-1211 Geneva 23 (Switzerland); Capra, A. [Department of Physics and Astronomy, York University, Toronto, ON, M3J 1P3 (Canada); Cesar, C.L. [Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-972 (Brazil); Chapman, S. [Department of Physics, University of California at Berkeley, Berkeley, CA 94720-7300 (United States); Charlton, M.; Deller, A.; Eriksson, S. [Department of Physics, College of Science, Swansea University, Swansea SA2 8PP (United Kingdom); Fajans, J. [Department of Physics, University of California at Berkeley, Berkeley, CA 94720-7300 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Friesen, T. [Department of Physics and Astronomy, University of Calgary, Calgary, Alberta T2N 1N4 (Canada); Fujiwara, M.C. [Department of Physics and Astronomy, University of Calgary, Calgary, Alberta T2N 1N4 (Canada); TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Gill, D.R. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Gutierrez, A. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z4 (Canada); and others

    2013-12-21

    The Silicon Vertex Detector (SVD) is the main diagnostic tool in the ALPHA-experiment. It provides precise spatial and timing information of antiproton (antihydrogen) annihilation events (vertices), and most importantly, the SVD is capable of directly identifying and analysing single annihilation events, thereby forming the basis of ALPHA's analysis. This paper describes the ALPHA SVD and its upgrade, installed in the ALPHA's new neutral atom trap.

  20. Multipole expansion of vertex functions in an arbitrary frame

    International Nuclear Information System (INIS)

    Daumens, Michel

    1977-01-01

    Vertex functions are expanded on the bases of tensor spherical harmonics and tensor multipoles. The coefficients of the expansions are rotational invariant form factors. The relations with those defined in particular frames by Durand, De Celles and Marr, and by De Rafael are exhibited. Finally multipolar form factors are built which are irreducible under pure Lorentz transformations [fr

  1. Combining Vertex-centric Graph Processing with SPARQL for Large-scale RDF Data Analytics

    KAUST Repository

    Abdelaziz, Ibrahim

    2017-06-27

    Modern applications, such as drug repositioning, require sophisticated analytics on RDF graphs that combine structural queries with generic graph computations. Existing systems support either declarative SPARQL queries, or generic graph processing, but not both. We bridge the gap by introducing Spartex, a versatile framework for complex RDF analytics. Spartex extends SPARQL to support programs that combine seamlessly generic graph algorithms (e.g., PageRank, Shortest Paths, etc.) with SPARQL queries. Spartex builds on existing vertex-centric graph processing frameworks, such as Graphlab or Pregel. It implements a generic SPARQL operator as a vertex-centric program that interprets SPARQL queries and executes them efficiently using a built-in optimizer. In addition, any graph algorithm implemented in the underlying vertex-centric framework, can be executed in Spartex. We present various scenarios where our framework simplifies significantly the implementation of complex RDF data analytics programs. We demonstrate that Spartex scales to datasets with billions of edges, and show that our core SPARQL engine is at least as fast as the state-of-the-art specialized RDF engines. For complex analytical tasks that combine generic graph processing with SPARQL, Spartex is at least an order of magnitude faster than existing alternatives.

  2. Lattice Hamiltonian approach to the massless Schwinger model. Precise extraction of the mass gap

    Energy Technology Data Exchange (ETDEWEB)

    Cichy, Krzysztof [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Poznan Univ. (Poland). Faculty of Physics; Kujawa-Cichy, Agnieszka [Poznan Univ. (Poland). Faculty of Physics; Szyniszewski, Marcin [Poznan Univ. (Poland). Faculty of Physics; Manchester Univ. (United Kingdom). NOWNano DTC

    2012-12-15

    We present results of applying the Hamiltonian approach to the massless Schwinger model. A finite basis is constructed using the strong coupling expansion to a very high order. Using exact diagonalization, the continuum limit can be reliably approached. This allows to reproduce the analytical results for the ground state energy, as well as the vector and scalar mass gaps to an outstanding precision better than 10{sup -6} %.

  3. Lorentz transformations, sideways shift and massless spinning particles

    Science.gov (United States)

    Bolonek-Lasoń, K.; Kosiński, P.; Maślanka, P.

    2017-06-01

    Recently (Stone et al. (2015) [16]) the influence of the so called ;Wigner translations; (more generally-Lorentz transformations) on circularly polarized Gaussian packets (providing the solution to Maxwell equations in paraxial approximation) has been studied. It appears that, within this approximation, the Wigner translations have an effect of shifting the wave packet trajectory parallel to itself by an amount proportional to the photon helicity. It has been suggested that this shift may result from specific properties of the algebra of Poincare generators for massless particles. In the present letter we describe the general relation between transformation properties of electromagnetic field on quantum and classical levels. It allows for a straightforward derivation of the helicity-dependent transformation rules. We present also an elementary derivation of the formula for sideways shift based on classical Maxwell theory. Some comments are made concerning the generalization to higher helicities and the relation to the coordinate operator defined long time ago by Pryce.

  4. Lorentz transformations, sideways shift and massless spinning particles

    Directory of Open Access Journals (Sweden)

    K. Bolonek-Lasoń

    2017-06-01

    Full Text Available Recently (Stone et al. (2015 [16] the influence of the so called “Wigner translations” (more generally-Lorentz transformations on circularly polarized Gaussian packets (providing the solution to Maxwell equations in paraxial approximation has been studied. It appears that, within this approximation, the Wigner translations have an effect of shifting the wave packet trajectory parallel to itself by an amount proportional to the photon helicity. It has been suggested that this shift may result from specific properties of the algebra of Poincare generators for massless particles. In the present letter we describe the general relation between transformation properties of electromagnetic field on quantum and classical levels. It allows for a straightforward derivation of the helicity-dependent transformation rules. We present also an elementary derivation of the formula for sideways shift based on classical Maxwell theory. Some comments are made concerning the generalization to higher helicities and the relation to the coordinate operator defined long time ago by Pryce.

  5. Lorentz transformations, sideways shift and massless spinning particles

    Energy Technology Data Exchange (ETDEWEB)

    Bolonek-Lasoń, K. [Department of Statistical Methods, Faculty of Economics and Sociology (Poland); Kosiński, P. [Department of Computer Science, Faculty of Physics and Applied Informatics, University of Łódź, Pomorska 149/153, 90-236 Łódź (Poland); Maślanka, P., E-mail: pmaslan@uni.lodz.pl [Department of Computer Science, Faculty of Physics and Applied Informatics, University of Łódź, Pomorska 149/153, 90-236 Łódź (Poland)

    2017-06-10

    Recently (Stone et al. (2015) ) the influence of the so called “Wigner translations” (more generally-Lorentz transformations) on circularly polarized Gaussian packets (providing the solution to Maxwell equations in paraxial approximation) has been studied. It appears that, within this approximation, the Wigner translations have an effect of shifting the wave packet trajectory parallel to itself by an amount proportional to the photon helicity. It has been suggested that this shift may result from specific properties of the algebra of Poincare generators for massless particles. In the present letter we describe the general relation between transformation properties of electromagnetic field on quantum and classical levels. It allows for a straightforward derivation of the helicity-dependent transformation rules. We present also an elementary derivation of the formula for sideways shift based on classical Maxwell theory. Some comments are made concerning the generalization to higher helicities and the relation to the coordinate operator defined long time ago by Pryce.

  6. Construction of the CDF silicon vertex detector

    International Nuclear Information System (INIS)

    Skarha, J.; Barnett, B.; Boswell, C.; Snider, F.; Spies, A.; Tseng, J.; Vejcik, S.; Carter, H.; Flaugher, B.; Gonzales, B.; Hrycyk, M.; Nelson, C.; Segler, S.; Shaw, T.; Tkaczyk, S.; Turner, K.; Wesson, T.; Carithers, W.; Ely, R.; Haber, C.; Holland, S.; Kleinfelder, S.; Merrick, T.; Schneider, O.; Wester, W.; Wong, M.; Amidei, D.; Derwent, P.; Gold, M.; Matthews, J.; Bacchetta, N.; Bisello, D.; Busetto, G.; Castro, A.; Loreti, M.; Pescara, L.; Bedeschi, F.; Bolognesi, V.; Dell'Agnello, S.; Galeotti, S.; Mariotti, M.; Menzione, A.; Punzi, G.; Raffaelli, F.; Risotri, L.; Tartarelli, F.; Turini, N.; Wenzel, H.; Zetti, F.; Bailey, M.; Garfinkel, A.; Shaw, N.; Tipton, P.; Watts, G.

    1992-04-01

    Technical details and methods used in constructing the CDF silicon vertex detector are presented. This description includes a discussion of the foam-carbon fiber composite structure used to silicon microstrip detectors and the procedure for achievement of 5 μm detector alignment. The construction of the beryllium barrel structure, which houses the detector assemblies, is also described. In addition, the 10 μm placement accuracy of the detectors in the barrel structure is discussed and the detector cooling and mounting systems are described. 12 refs

  7. Topological Symmetry, Spin Liquids and CFT Duals of Polyakov Model with Massless Fermions

    Energy Technology Data Exchange (ETDEWEB)

    Unsal, Mithat

    2008-04-30

    We prove the absence of a mass gap and confinement in the Polyakov model with massless complex fermions in any representation of the gauge group. A U(1){sub *} topological shift symmetry protects the masslessness of one dual photon. This symmetry emerges in the IR as a consequence of the Callias index theorem and abelian duality. For matter in the fundamental representation, the infrared limits of this class of theories interpolate between weakly and strongly coupled conformal field theory (CFT) depending on the number of flavors, and provide an infinite class of CFTs in d = 3 dimensions. The long distance physics of the model is same as certain stable spin liquids. Altering the topology of the adjoint Higgs field by turning it into a compact scalar does not change the long distance dynamics in perturbation theory, however, non-perturbative effects lead to a mass gap for the gauge fluctuations. This provides conceptual clarity to many subtle issues about compact QED{sub 3} discussed in the context of quantum magnets, spin liquids and phase fluctuation models in cuprate superconductors. These constructions also provide new insights into zero temperature gauge theory dynamics on R{sup 2,1} and R{sup 2,1} x S{sup 1}. The confined versus deconfined long distance dynamics is characterized by a discrete versus continuous topological symmetry.

  8. On the total irregularity strength of caterpillar with each internal vertex has degree three

    Science.gov (United States)

    Indriati, Diari; Rosyida, Isnaini; Widodo

    2018-04-01

    Let G be a simple, connected and undirected graph with vertex set V and edge set E. A total k-labeling f:V \\cup E\\to \\{1,2,\\ldots,k\\} is defined as totally irregular total k-labeling if the weights of any two different both vertices and edges are distinct. The weight of vertex x is defined as wt(x)=f(x)+{\\sum }xy\\in Ef(xy), while the weight of edge xy is wt(xy)=f(x)+f(xy)+f(y). A minimum k for which G has totally irregular total k-labeling is mentioned as total irregularity strength of G and denoted by ts(G). This paper contains investigation of totally irregular total k-labeling and determination of their total irregularity strengths for caterpillar graphs with each internal vertex between two stars has degree three. The results are ts({S}n,3,n)=\\lceil \\frac{2n}{2}\\rceil, ts({S}n,3,3,n)=\\lceil \\frac{2n+1}{2}\\rceil and ts({S}n,3,3,3,n)=\\lceil \\frac{2n+2}{2}\\rceil for n > 4:

  9. The upgrade of the vertex detector to form the central part of the silicon tracker in DELPHI

    International Nuclear Information System (INIS)

    Brenner, R.

    1997-01-01

    The DELPHI vertex detector has undergone a final upgrade to meet the physics requirements at LEP200. The old vertex detector has been made longer by 24 cm and is now the barrel part of the silicon tracker with a very forward part at both ends. The configuration and first results on the stability and performance of the barrel part is reported. (orig.)

  10. TRACKING AND VERTEXING WITH THE ATLAS INNER DETECTOR IN THE LHC RUN2 AND BEYOND

    CERN Document Server

    Choi, Kyungeon; The ATLAS collaboration

    2017-01-01

    Run-2 of the LHC has provided new challenges to track and vertex reconstruction with higher centre-of-mass energies and luminosity leading to increasingly high-multiplicity environments, boosted, and highly-collimated physics objects. To achieve this goal, ATLAS is equipped with the Inner Detector tracking system built using different technologies, silicon planar sensors (pixel and micro-strip) and gaseous drift- tubes, all embedded in a 2T solenoidal magnetic field. In addition, the Insertable B-layer (IBL) is a fourth pixel layer, which was inserted at the centre of ATLAS during the first long shutdown of the LHC. An overview of the use of each of these subdetectors in track and vertex reconstruction, as well as the algorithmic approaches taken to the specific tasks of pattern recognition and track fitting, is given. The performance of the Inner Detector tracking and vertexing will be summarised. These include a factor of three reduction in the reconstruction time, optimisation for the expected conditions, ...

  11. Tracking and Vertexing with the ATLAS Inner Detector in the LHC Run2 and Beyond

    CERN Document Server

    Swift, Stewart Patrick; The ATLAS collaboration

    2017-01-01

    Run-2 of the LHC has provided new challenges to track and vertex reconstruction with higher centre-of-mass energies and luminosity leading to increasingly high-multiplicity environments, boosted, and highly-collimated physics objects. To achieve this goal, ATLAS is equipped with the Inner Detector tracking system built using different technologies, silicon planar sensors (pixel and micro-strip) and gaseous drift- tubes, all embedded in a 2T solenoidal magnetic field. In addition, the Insertable B-layer (IBL) is a fourth pixel layer, which was inserted at the centre of ATLAS during the first long shutdown of the LHC. An overview of the use of each of these subdetectors in track and vertex reconstruction, as well as the algorithmic approaches taken to the specific tasks of pattern recognition and track fitting, is given. The performance of the Inner Detector tracking and vertexing will be summarised. These include a factor of three reduction in the reconstruction time, optimisation for the expected conditions, ...

  12. Could a Weak Coupling Massless SU(5) Theory Underly the Standard Model S-Matrix

    Science.gov (United States)

    White, Alan R.

    2011-04-01

    The unitary Critical Pomeron connects to a unique massless left-handed SU(5) theory that, remarkably, might provide an unconventional underlying unification for the Standard Model. Multi-regge theory suggests the existence of a bound-state high-energy S-Matrix that replicates Standard Model states and interactions via massless fermion anomaly dynamics. Configurations of anomalous wee gauge boson reggeons play a vacuum-like role. All particles, including neutrinos, are bound-states with dynamical masses (there is no Higgs field) that are formed (in part) by anomaly poles. The contributing zero-momentum chirality transitions break the SU(5) symmetry to vector SU(3)⊗U(1) in the S-Matrix. The high-energy interactions are vector reggeon exchanges accompanied by wee boson sums (odd-signature for the strong interaction and even-signature for the electroweak interaction) that strongly enhance couplings. The very small SU(5) coupling, αQUD ≲ 1/120, should be reflected in small (Majorana) neutrino masses. A color sextet quark sector, still to be discovered, produces both Dark Matter and Electroweak Symmetry Breaking. Anomaly color factors imply this sector could be produced at the LHC with large cross-sections, and would be definitively identified in double pomeron processes.

  13. Coulomb’s law corrections and fermion field localization in a tachyonic de Sitter thick braneworld

    International Nuclear Information System (INIS)

    Cartas-Fuentevilla, Roberto; Escalante, Alberto; Germán, Gabriel; Herrera-Aguilar, Alfredo; Mora-Luna, Refugio Rigel

    2016-01-01

    Following recent studies which show that it is possible to localize gravity as well as scalar and gauge vector fields in a tachyonic de Sitter thick braneworld, we investigate the solution of the gauge hierarchy problem, the localization of fermion fields in this model, the recovering of the Coulomb law on the non-relativistic limit of the Yukawa interaction between bulk fermions and gauge bosons localized in the brane, and confront the predicted 5D corrections to the photon mass with its upper experimental/observational bounds, finding the model physically viable since it passes these tests. In order to achieve the latter aims we first consider the Yukawa interaction term between the fermionic and the tachyonic scalar fields MF(T)ΨΨ-bar in the action and analyze four distinct tachyonic functions F(T) that lead to four different structures of the respective fermionic mass spectra with different physics. In particular, localization of the massless left-chiral fermion zero mode is possible for three of these cases. We further analyze the phenomenology of these Yukawa interactions among fermion fields and gauge bosons localized on the brane and obtain the crucial and necessary information to compute the corrections to Coulomb’s law coming from massive KK vector modes in the non-relativistic limit. These corrections are exponentially suppressed due to the presence of the mass gap in the mass spectrum of the bulk gauge vector field. From our results we conclude that corrections to Coulomb’s law in the thin brane limit have the same form (up to a numerical factor) as far as the left-chiral massless fermion field is localized on the brane. Finally we compute the corrections to the Coulomb’s law for an arbitrarily thick brane scenario which can be interpreted as 5D corrections to the photon mass. By performing consistent estimations with brane phenomenology, we found that the predicted corrections to the photon mass, which are well bounded by the experimentally

  14. Coulomb’s law corrections and fermion field localization in a tachyonic de Sitter thick braneworld

    Energy Technology Data Exchange (ETDEWEB)

    Cartas-Fuentevilla, Roberto; Escalante, Alberto [Instituto de Física, Benemérita Universidad Autónoma de Puebla,Apdo. postal J-48, 72570 Puebla, Pue. (Mexico); Germán, Gabriel [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México,Apdo. Postal 48-3, 62251 Cuernavaca, Morelos (Mexico); Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road,Oxford, OX1 3NP (United Kingdom); Herrera-Aguilar, Alfredo [Instituto de Física, Benemérita Universidad Autónoma de Puebla,Apdo. postal J-48, 72570 Puebla, Pue. (Mexico); Institutode Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo,Edificio C-3, Ciudad Universitaria, CP 58040, Morelia, Michoacán (Mexico); Mora-Luna, Refugio Rigel [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México,Apdo. Postal 48-3, 62251 Cuernavaca, Morelos (Mexico)

    2016-05-11

    Following recent studies which show that it is possible to localize gravity as well as scalar and gauge vector fields in a tachyonic de Sitter thick braneworld, we investigate the solution of the gauge hierarchy problem, the localization of fermion fields in this model, the recovering of the Coulomb law on the non-relativistic limit of the Yukawa interaction between bulk fermions and gauge bosons localized in the brane, and confront the predicted 5D corrections to the photon mass with its upper experimental/observational bounds, finding the model physically viable since it passes these tests. In order to achieve the latter aims we first consider the Yukawa interaction term between the fermionic and the tachyonic scalar fields MF(T)ΨΨ-bar in the action and analyze four distinct tachyonic functions F(T) that lead to four different structures of the respective fermionic mass spectra with different physics. In particular, localization of the massless left-chiral fermion zero mode is possible for three of these cases. We further analyze the phenomenology of these Yukawa interactions among fermion fields and gauge bosons localized on the brane and obtain the crucial and necessary information to compute the corrections to Coulomb’s law coming from massive KK vector modes in the non-relativistic limit. These corrections are exponentially suppressed due to the presence of the mass gap in the mass spectrum of the bulk gauge vector field. From our results we conclude that corrections to Coulomb’s law in the thin brane limit have the same form (up to a numerical factor) as far as the left-chiral massless fermion field is localized on the brane. Finally we compute the corrections to the Coulomb’s law for an arbitrarily thick brane scenario which can be interpreted as 5D corrections to the photon mass. By performing consistent estimations with brane phenomenology, we found that the predicted corrections to the photon mass, which are well bounded by the experimentally

  15. The role of geometry in 4-vertex origami mechanics

    Science.gov (United States)

    Waitukaitis, Scott; Dieleman, Peter; van Hecke, Martin

    Origami offers an interesting design platform metamaterials because it strongly couples mechanics with geometry. Even so, most research carried out so far has been limited to one or two particular patterns. I will discuss the full geometrical space of the most common origami building block, the 4-vertex, and show how exotic geometries can have dramatic effects on the mechanics.

  16. Regge vertex for quark production in the central rapidity region in the next-to-leading order

    Energy Technology Data Exchange (ETDEWEB)

    Kozlov, M. G., E-mail: M.G.Kozlov@inp.nsk.su; Reznichenko, A. V., E-mail: A.V.Reznichenko@inp.nsk.su [Russian Academy of Sciences, Budker Institute of Nuclear Physics, Siberian Branch (Russian Federation)

    2016-03-15

    The effective vertex for quark production in the interaction of a Reggeized quark and a Reggeized gluon is calculated in the next-to-leading order (NLO). The resulting vertex is the missing component of the NLO multi-Regge amplitude featuring quark and gluon exchanges in the t channels. This calculation will make it possible to develop in future the bootstrap approach to proving quark Reggeization in the next-to-leading logarithmic approximation.

  17. Relativistic gravitation from massless systems of scalar and vector fields

    International Nuclear Information System (INIS)

    Fonseca Teixeira, A.F. da.

    1979-01-01

    Under the laws of Einstein's gravitational theory, a massless system consisting of the diffuse sources of two fields is discussed. One fields is scalar, of long range, the other is a vector field of short range. A proportionality between the sources is assumed. Both fields are minimally coupled to gravitation, and contribute positive definitely to the time component of the energy momentum tensor. A class of static, spherically symmetric solutions of the equations is obtained, in the weak field limit. The solutions are regular everywhere, stable, and can represent large or small physical systems. The gravitational field presents a Schwarzschild-type asymptotic behavior. The dependence of the energy on the various parameters characterizing the system is discussed in some detail. (Author) [pt

  18. Development of new assembly techniques for a silicon micro-vertex detector unit using the flip-chip bonding method

    International Nuclear Information System (INIS)

    Saitoh, Y.; Takeuchi, H.; Mandai, M.; Kanazawa, H.; Yamanaka, J.; Miyahara, S.; Kamiya, M.; Fujita, Y.; Higashi, Y.; Ikeda, H.; Ikeda, M.; Koike, S.; Matsuda, T.; Ozaki, H.; Tanaka, M.; Tsuboyama, T.; Avrillon, S.; Okuno, S.; Haba, J.; Hanai, H.; Mori, S.; Yusa, K.; Fukunaga, C.

    1994-01-01

    Full-size models of a detector unit for a silicon micro-vertex detector were built for the KEK B factory. The Flip-Chip Bonding (FCB) method using a new type anisotropic conductive film was examined. The structure using the FCB method successfully provides a new architecture for the silicon micro-vertex detector unit. (orig.)

  19. On the consistent interactions in D=11 among a graviton, a massless gravitino and a three-form

    International Nuclear Information System (INIS)

    Cioroianu, E.M.; Diaconu, E.; Sararu, S.C.

    2009-01-01

    The couplings that can be introduced between a massless Rarita-Schwinger field, a Pauli-Fierz field and an Abelian three-form gauge field in eleven spacetime dimensions are analyzed in the context of the deformation of the solution of the master equation. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  20. SPARTex: A Vertex-Centric Framework for RDF Data Analytics

    KAUST Repository

    Abdelaziz, Ibrahim

    2015-08-31

    A growing number of applications require combining SPARQL queries with generic graph search on RDF data. However, the lack of procedural capabilities in SPARQL makes it inappropriate for graph analytics. Moreover, RDF engines focus on SPARQL query evaluation whereas graph management frameworks perform only generic graph computations. In this work, we bridge the gap by introducing SPARTex, an RDF analytics framework based on the vertex-centric computation model. In SPARTex, user-defined vertex centric programs can be invoked from SPARQL as stored procedures. SPARTex allows the execution of a pipeline of graph algorithms without the need for multiple reads/writes of input data and intermediate results. We use a cost-based optimizer for minimizing the communication cost. SPARTex evaluates queries that combine SPARQL and generic graph computations orders of magnitude faster than existing RDF engines. We demonstrate a real system prototype of SPARTex running on a local cluster using real and synthetic datasets. SPARTex has a real-time graphical user interface that allows the participants to write regular SPARQL queries, use our proposed SPARQL extension to declaratively invoke graph algorithms or combine/pipeline both SPARQL querying and generic graph analytics.