Monopoles, vortices, and confinement

International Nuclear Information System (INIS)

Mack, G.; Pietarinen, E.

1981-10-01

An exact relation is established between an SO(3) lattice gauge theory model without monopoles, and a corresponding SU(2) model. Elimination of the monopoles (and their strings) leads to a substantial lowering of the entropy of thin vortices and a corresponding decrease of the string tension for low γ. This is revealed by approximate calculations of the vortex free energy and is confirmed by Monte Carlo data. The value of the physical transition temperature to 'hot gluon soup' is also lowered considerably. (orig.)

Baryonic hybrids: Gluons as beads on strings between quarks

International Nuclear Information System (INIS)

Cornwall, John M.

2005-01-01

V. Although we do not consider it in full detail, we show that in the qqG hybrid the gluon is a bead that can slide without friction on a string joining the q and q. We comment briefly on the significance of our findings to fluctuations of the minimal surface, a subject difficult to understand from the point of view of center vortices

Singular gauge potentials and the gluon condensate at zero temperature

International Nuclear Information System (INIS)

Langfeld, K.; Ilgenfritz, E.-M.; Reinhardt, H.; Schaefke, A.

2002-01-01

We consider a new cooling procedure which separates gluon degrees of freedom from singular center vortices in SU(2) LGT in a gauge invariant way. Restricted by a cooling scale κ 4 /σ 2 fixing the residual SO(3) gluonic action relative to the string tension, the procedure is RG invariant. In the limit κ → 0 a pure Z(2) vortex texture is left. This minimal vortex content does not contribute to the string tension. It reproduces, however, the lowest glueball states. With an action density scaling like a 4 with β, it defines a finite contribution to the action density at T = 0 in the continuum limit. We propose to interpret this a mass dimension 4 condensate related to the gluon condensate. Similarly, this vortex texture is revealed in the Landau gauge

Melting of the Abrikosov flux lattice in anisotropic superconductors

Science.gov (United States)

Beck, R. G.; Farrell, D. E.; Rice, J. P.; Ginsberg, D. M.; Kogan, V. G.

1992-01-01

It has been proposed that the Abrikosov flux lattice in high-Tc superconductors is melted over a significant fraction of the phase diagram. A thermodynamic argument is provided which establishes that the angular dependence of the melting temperature is controlled by the superconducting mass anisotropy. Using a low-frequency torsional-oscillator technique, this relationship has been tested in untwinned single-crystal YBa2Cu3O(7-delta). The results offer decisive support for the melting proposal.

Inertial mass of the Abrikosov vortex.

Science.gov (United States)

Chudnovsky, E M; Kuklov, A B

2003-08-08

We show that a large contribution to the inertial mass of the Abrikosov vortex comes from transversal displacements of the crystal lattice. The corresponding part of the mass per unit length of the vortex line is M(l)=(m(2)(e)c(2)/64 pi alpha(2)mu lambda(4)(L))ln((lambda(L)/xi), where m(e) is the bare electron mass, c is the speed of light, alpha=e(2)/Planck's over 2 pi c approximately 1/137 is the fine structure constant, mu is the shear modulus of the solid, lambda(L) is the London penetration length, and xi is the coherence length. In conventional superconductors, this mass can be comparable to or even greater than the vortex core mass computed by Suhl [Phys. Rev. Lett. 14, 226 (1965)

Singular gauge potentials and the gluon condensate at zero temperature

OpenAIRE

Langfeld, K.; Ilgenfritz, E. -M.; Reinhardt, H.; Schäfke, A.

2001-01-01

We consider a new cooling procedure which separates gluon degrees of freedom from singular center vortices in SU(2) LGT in a gauge invariant way. Restricted by a cooling scale $\\kappa^4/\\sigma^2$ fixing the residual SO(3) gluonic action relative to the string tension, the procedure is RG invariant. In the limit $\\kappa \\to 0$ a pure Z(2) vortex texture is left. This {\\it minimal} vortex content does not contribute to the string tension. It reproduces, however, the lowest glueball states. With...

Extended Josephson Relation and Abrikosov lattice deformation

International Nuclear Information System (INIS)

Matlock, Peter

2012-01-01

From the point of view of time-dependent Ginzburg Landau (TDGL) theory, a Josephson-like relation is derived for an Abrikosov vortex lattice accelerated and deformed by applied fields. Beginning with a review of the Josephson Relation derived from the two ingredients of a lattice-kinematics assumption in TDGL theory and gauge invariance, we extend the construction to accommodate a time-dependent applied magnetic field, a Floating-Kernel formulation of normal current, and finally lattice deformation due to the electric field and inertial effects of vortex-lattice motion. The resulting Josephson-like relation, which we call an Extended Josephson Relation, applies to a much wider set of experimental conditions than the original Josephson Relation, and is explicitly compatible with the considerations of TDGL theory.

A study of vorticity formation in high energy nuclear collisions

Energy Technology Data Exchange (ETDEWEB)

Becattini, F. [Universita di Firenze, Dipartimento di Fisica e Astronomia, Sesto F.no (Firenze) (Italy); INFN, Sezione di Firenze, Sesto F.no (Firenze) (Italy); Inghirami, G. [Universita di Firenze, Dipartimento di Fisica e Astronomia, Sesto F.no (Firenze) (Italy); Johann Wolfgang Goethe University, Frankfurt Institute for Advanced Studies (FIAS), Frankfurt am Main (Germany); Rolando, V.; Pagliara, G. [Universita di Ferrara, Dipartimento di Fisica e Scienze della Terra, Ferrara (Italy); INFN, Sezione di Ferrara, Ferrara (Italy); Beraudo, A.; De Pace, A.; Nardi, M. [INFN, Sezione di Torino, Turin (Italy); Del Zanna, L. [Universita di Firenze, Dipartimento di Fisica e Astronomia, Sesto F.no (Firenze) (Italy); INFN, Sezione di Firenze, Sesto F.no (Firenze) (Italy); INAF, Osservatorio Astrofisico di Arcetri, Florence (Italy); Chandra, V. [Indian Institute of Technology Gandhinagar, Ahmedabad, Gujrat (India)

2015-09-15

We present a quantitative study of vorticity formation in peripheral ultrarelativistic heavy-ion collisions at √(s{sub NN}) = 200 GeV by using the ECHO-QGP numerical code, implementing relativistic dissipative hydrodynamics in the causal Israel-Stewart framework in 3 + 1 dimensions with an initial Bjorken flow profile. We consider different definitions of vorticity which are relevant in relativistic hydrodynamics. After demonstrating the excellent capabilities of our code, which proves to be able to reproduce Gubser flow up to 8 fm/c, we show that, with the initial conditions needed to reproduce the measured directed flow in peripheral collisions corresponding to an average impact parameter b = 11.6 fm and with the Bjorken flow profile for a viscous Quark Gluon Plasma with η/s = 0.1 fixed, a vorticity of the order of some 10{sup -2} c/fm can develop at freeze-out. The ensuing polarization of Λ baryons does not exceed 1.4 % at midrapidity. We show that the amount of developed directed flow is sensitive to both the initial angular momentum of the plasma and its viscosity. (orig.)

Thermal chiral vortical and magnetic waves: New excitation modes in chiral fluids

Energy Technology Data Exchange (ETDEWEB)

Kalaydzhyan, Tigran, E-mail: tigran@caltech.edu [Department of Physics, University of Illinois, 845 W Taylor Street, Chicago, IL 60607 (United States); Jet Propulsion Laboratory, 4800 Oak Grove Dr, M/S 298, Pasadena, CA 91109 (United States); Murchikova, Elena [TAPIR, California Institute of Technology, MC 350-17, Pasadena, CA 91125 (United States)

2017-06-15

In certain circumstances, chiral (parity-violating) medium can be described hydrodynamically as a chiral fluid with microscopic quantum anomalies. Possible examples of such systems include strongly coupled quark–gluon plasma, liquid helium {sup 3}He-A, neutron stars and the Early Universe. We study first-order hydrodynamics of a chiral fluid on a vortex background and in an external magnetic field. We show that there are two previously undiscovered modes describing heat waves propagating along the vortex and magnetic field. We call them the Thermal Chiral Vortical Wave and Thermal Chiral Magnetic Wave. We also identify known gapless excitations of density (chiral vortical and chiral magnetic waves) and transverse velocity (chiral Alfvén wave). We demonstrate that the velocity of the chiral vortical wave is zero, when the full hydrodynamic framework is applied, and hence the wave is absent and the excitation reduces to the charge diffusion mode. We also comment on the frame-dependent contributions to the obtained propagation velocities.

Thermal chiral vortical and magnetic waves: New excitation modes in chiral fluids

International Nuclear Information System (INIS)

Kalaydzhyan, Tigran; Murchikova, Elena

2017-01-01

In certain circumstances, chiral (parity-violating) medium can be described hydrodynamically as a chiral fluid with microscopic quantum anomalies. Possible examples of such systems include strongly coupled quark–gluon plasma, liquid helium "3He-A, neutron stars and the Early Universe. We study first-order hydrodynamics of a chiral fluid on a vortex background and in an external magnetic field. We show that there are two previously undiscovered modes describing heat waves propagating along the vortex and magnetic field. We call them the Thermal Chiral Vortical Wave and Thermal Chiral Magnetic Wave. We also identify known gapless excitations of density (chiral vortical and chiral magnetic waves) and transverse velocity (chiral Alfvén wave). We demonstrate that the velocity of the chiral vortical wave is zero, when the full hydrodynamic framework is applied, and hence the wave is absent and the excitation reduces to the charge diffusion mode. We also comment on the frame-dependent contributions to the obtained propagation velocities.

Thermal chiral vortical and magnetic waves: New excitation modes in chiral fluids

Directory of Open Access Journals (Sweden)

Tigran Kalaydzhyan

2017-06-01

Full Text Available In certain circumstances, chiral (parity-violating medium can be described hydrodynamically as a chiral fluid with microscopic quantum anomalies. Possible examples of such systems include strongly coupled quark–gluon plasma, liquid helium 3He-A, neutron stars and the Early Universe. We study first-order hydrodynamics of a chiral fluid on a vortex background and in an external magnetic field. We show that there are two previously undiscovered modes describing heat waves propagating along the vortex and magnetic field. We call them the Thermal Chiral Vortical Wave and Thermal Chiral Magnetic Wave. We also identify known gapless excitations of density (chiral vortical and chiral magnetic waves and transverse velocity (chiral Alfvén wave. We demonstrate that the velocity of the chiral vortical wave is zero, when the full hydrodynamic framework is applied, and hence the wave is absent and the excitation reduces to the charge diffusion mode. We also comment on the frame-dependent contributions to the obtained propagation velocities.

Theory of pairing symmetry in the vortex states

NARCIS (Netherlands)

Yokoyama, Takehito; Ichioka, Yukio; Yanaka, Yukio; Golubov, Alexandre Avraamovitch

2010-01-01

We investigate pairing symmetry in an Abrikosov vortex and vortex lattice. It is shown that the Cooper pair wave function at the center of an Abrikosov vortex with vorticity m has a different parity with respect to frequency from that in the bulk if m is an odd number, while it has the same parity

Non-Abelian vortex lattices

Science.gov (United States)

Tallarita, Gianni; Peterson, Adam

2018-04-01

We perform a numerical study of the phase diagram of the model proposed in [M. Shifman, Phys. Rev. D 87, 025025 (2013)., 10.1103/PhysRevD.87.025025], which is a simple model containing non-Abelian vortices. As per the case of Abrikosov vortices, we map out a region of parameter space in which the system prefers the formation of vortices in ordered lattice structures. These are generalizations of Abrikosov vortex lattices with extra orientational moduli in the vortex cores. At sufficiently large lattice spacing the low energy theory is described by a sum of C P (1 ) theories, each located on a vortex site. As the lattice spacing becomes smaller, when the self-interaction of the orientational field becomes relevant, only an overall rotation in internal space survives.

Excluding scalar gluons

International Nuclear Information System (INIS)

Koller, K.; Krasemann, H.

1979-08-01

We investigate the Dalitz plot population and thrust angular distribution for the Orthoquarkonium decay Q anti Q → 3 scalar gluons. The Dalitz plot for scalar gluons is populated in corners where events are 2 jet like and this disagrees with existing Upsilon data. The scalar gluon thrust angular distribution is also in striking disagreement with the UPSILON data and so scalar gluons are completely ruled out. (orig.)

Quark jets, gluon jets and the three-gluon vertex

International Nuclear Information System (INIS)

Fodor, Z.

1989-11-01

Using hadronic jets in electron-positron annihilation, we suggest a simple and model-independent method to see the differences between quark and gluon jets. We define and analyse special energy dependent moments of jets and choose those which are the most characteristic to the jet type. The method handles the energy of a jet in an adequate way. We discuss new methods using jet flavor tagging, ordinary flavor tagging of a definite quark jet or discrimination between quark and gluon jets, to test the triple-gluon vertex in electron-positron annihilation. An enriched sample of gluon jets, jets with the smallest energy in four-jet events, as well as a continuous tagging variable are also studied. 21 refs., 6 figs. (Author)

Gluon attributes

International Nuclear Information System (INIS)

Weiler, T.

1981-01-01

An overview is presented of the attributes of gluons, deducible from experimental data. Particular attention is given to the photon-gluon fusion model of charm leptoproduction. The agreement with QCD and theoretical prejudice is qualitatively good

Quark and Gluon Relaxation in Quark-Gluon Plasmas

Science.gov (United States)

Heiselberg, H.; Pethick, C. J.

1993-01-01

The quasiparticle decay rates for quarks and gluons in quark-gluon plasmas are calculated by solving the kinetic equation. Introducing an infrared cutoff to allow for nonperturbative effects, we evaluate the quasiparticle lifetime at momenta greater than the inverse Debye screening length to leading order in the coupling constant.

Vortical flows

Energy Technology Data Exchange (ETDEWEB)

Wu, Jie-Zhi [Peking Univ., Beijing (China). College of Engineering; Ma, Hui-Yang [Univ. of Chinese Academy of Sciences, Beijing (China). Dept. of Physics; Zhou, Ming-De [Arizona Univ., Tucson, AZ (United States). Dept. of Aerospace and Mechanical Engineering

2015-11-01

This book is a comprehensive and intensive book for graduate students in fluid dynamics as well as scientists, engineers and applied mathematicians. Offering a systematic introduction to the physical theory of vortical flows at graduate level, it considers the theory of vortical flows as a branch of fluid dynamics focusing on shearing process in fluid motion, measured by vorticity. It studies vortical flows according to their natural evolution stages,from being generated to dissipated. As preparation, the first three chapters of the book provide background knowledge for entering vortical flows. The rest of the book deals with vortices and vortical flows, following their natural evolution stages. Of various vortices the primary form is layer-like vortices or shear layers, and secondary but stronger form is axial vortices mainly formed by the rolling up of shear layers. Problems are given at the end of each chapter and Appendix, some for helping understanding the basic theories, and some involving specific applications; but the emphasis of both is always on physical thinking.

Vortical flows

International Nuclear Information System (INIS)

Wu, Jie-Zhi; Ma, Hui-Yang; Zhou, Ming-De

2015-01-01

This book is a comprehensive and intensive book for graduate students in fluid dynamics as well as scientists, engineers and applied mathematicians. Offering a systematic introduction to the physical theory of vortical flows at graduate level, it considers the theory of vortical flows as a branch of fluid dynamics focusing on shearing process in fluid motion, measured by vorticity. It studies vortical flows according to their natural evolution stages,from being generated to dissipated. As preparation, the first three chapters of the book provide background knowledge for entering vortical flows. The rest of the book deals with vortices and vortical flows, following their natural evolution stages. Of various vortices the primary form is layer-like vortices or shear layers, and secondary but stronger form is axial vortices mainly formed by the rolling up of shear layers. Problems are given at the end of each chapter and Appendix, some for helping understanding the basic theories, and some involving specific applications; but the emphasis of both is always on physical thinking.

Properties of gluon jets

International Nuclear Information System (INIS)

Sugano, K.

1987-01-01

The properties of gluon jets are reviewed, and the measured characteristics are compared to the theoretical expectations. Although neither data nor models for the gluon jets are in the mature stage, in general the agreement between experiment and theory is remarkable. There are some intriguing differences. Since the properties of gluon jets are deeply rooted in the basic structure of non-Abelian gauge theory, the study of gluon jets casts further light on our understanding of QCD. Finally, the future prospects are discussed

Fluid vortices

National Research Council Canada - National Science Library

Green, Sheldon I

1995-01-01

... . . . . . . . . . . . . . . . Vorticity Kinematics and Dynamics - Physical Principles The Vorticity Equation with Examples . . . . Summary . . . . . . . . . . . . . . . . . Vorticity in Orthogonal...

Properties of gluon jets

International Nuclear Information System (INIS)

Sugano, K.

1988-01-01

The properties of gluon jets are reviewed from an experimental point of view. The measured characteristics are compared to theoretical expectations. Although neither data nor models for the gluon jets are in the mature stage, there are remarkable agreements and also intriguing disagreements between experiment and theory. Since much interesting data have begun to emerge from various experiments and the properties of gluon jets are deeply rooted in the basic structure of non-Abelian gauge theory, the study of gluon jets casts further light on understanding of QCD. The future prospects are discussed

Gluons in quarkonium decay

International Nuclear Information System (INIS)

Koller, K.; Walsh, T.

1978-03-01

We discuss what can be learned of the 3 S 1 quarkonium decay QantiQ → 3 gluoans QantiQ → γ + 2 gluons. The former is a way to find gluon jets and test QCD. The latter also allows us to measure gluoan + gluon → hadrons and look for pure gluonic resonances (glueballs). (orig.) [de

Gluon exchange in elastic hadron scattering

International Nuclear Information System (INIS)

Jenkovszky, L.L.; Paccanoni, F.; Chikovani, Z.E.

1991-01-01

It is generally accepted that the Pomeron, which determines the long-range component of the strong interaction, corresponds to exchange of gluons with the corresponding quantum numbers (the minimum number of such gluons is two). The C-odd partner of the Pomeron, the odderon, corresponds to exchange of an odd number of gluons (three or more). By means of a model of the nonperturbative gluon propagator, restrictions are obtained on the parameters of two-gluon (Pomeron) and three-gluon (odderon) exchange in hadron scattering. In the framework of this model an interpretation is proposed for the various asymptotic regimes in the behavior of the total cross section and of the differential cross section of elastic scattering at high energies

Gluon mass generation without seagull divergences

International Nuclear Information System (INIS)

Aguilar, Arlene C.; Papavassiliou, Joannis

2010-01-01

Dynamical gluon mass generation has been traditionally plagued with seagull divergences, and all regularization procedures proposed over the years yield finite but scheme-dependent gluon masses. In this work we show how such divergences can be eliminated completely by virtue of a characteristic identity, valid in dimensional regularization. The ability to trigger the aforementioned identity hinges crucially on the particular Ansatz employed for the three-gluon vertex entering into the Schwinger-Dyson equation governing the gluon propagator. The use of the appropriate three-gluon vertex brings about an additional advantage: one obtains two separate (but coupled) integral equations, one for the effective charge and one for the gluon mass. This system of integral equations has a unique solution, which unambiguously determines these two quantities. Most notably, the effective charge freezes in the infrared, and the gluon mass displays power-law running in the ultraviolet, in agreement with earlier considerations.

Gluon Saturation and EIC

Energy Technology Data Exchange (ETDEWEB)

Sichtermann, Ernst

2016-12-15

The fundamental structure of nucleons and nuclear matter is described by the properties and dynamics of quarks and gluons in quantum chromodynamics. Electron-nucleon collisions are a powerful method to study this structure. As one increases the energy of the collisions, the interaction process probes regions of progressively higher gluon density. This density must eventually saturate. An high-energy polarized Electron-Ion Collider (EIC) has been proposed to observe and study the saturated gluon density regime. Selected measurements will be discussed, following a brief introduction.

Duality and multi-gluon scattering

International Nuclear Information System (INIS)

Mangano, M.; Parke, S.; Xu Zhan

1988-01-01

For the six-gluon scattering process we give explicit and simple expressions for the amplitude and its square. To achieve this we use an analogy with string theories to identify a unique procedure for writing the multi-gluon scattering amplitudes in terms of a sum of gauge invariant dual sub-amplitudes multiplied by an appropriate color (Chan-Paton) factor. The sub-amplitudes defined in this way are invariant under cyclic permutations, satisfy powerful identities which relate different non-cyclic permutations and factorize in the soft gluon limit, the two-gluon collinear limit and on multi-gluon poles. Also, to leading order in the number of colors these sub-amplitudes sum incoherently in the square of the full matrix element. The results contained here are important for Monte Carlo studies of multi-jet processes at hadron colliders as well as for understanding the general structure of QCD. (orig.)

The quark gluon plasma; Le plasma de quarks et de gluons

Energy Technology Data Exchange (ETDEWEB)

Granier de Cassagnac, R. [Ecole Polytechnique, Lab. Leprince-Ringuet, 91 - Palaiseau (France)

2010-05-15

The quark-gluon plasma (QGP) is a state of matter in which the universe was expected to be a few micro-seconds after the big-bang. Violent collisions of heavy ions are supposed to re-create this state in particle accelerators. Numerous signatures of this fugacious state have already been observed at the RHIC (relativistic heavy ion collider). The first evidence of the violence of collisions is the number of generated particles: about 6000 per collision, mostly hadrons. This figure seems high but in fact is less than theoretically expected and is the first sign of the formation of a QGP that saturates the density of gluons. Another sign, observed at the RHIC is the damping of the particle jets that are produced in the collision. This damping is consistent with the crossing of a medium whose density is so high that it can not be made of hadrons but of partons. In the RHIC experiments the collective behaviour of quarks and gluons shows that they are strongly interacting with one another. This fact supports the idea that the QGP is more a perfect liquid rather than an ideal gas in which quarks and gluons move freely. (A.C.)

Modelling the gluon propagator

Energy Technology Data Exchange (ETDEWEB)

Leinweber, D.B.; Parrinello, C.; Skullerud, J.I.; Williams, A.G

1999-03-01

Scaling of the Landau gauge gluon propagator calculated at {beta} = 6.0 and at {beta} = 6.2 is demonstrated. A variety of functional forms for the gluon propagator calculated on a large (32{sup 3} x 64) lattice at {beta} = 6.0 are investigated.

Quark ACM with topologically generated gluon mass

Science.gov (United States)

Choudhury, Ishita Dutta; Lahiri, Amitabha

2016-03-01

We investigate the effect of a small, gauge-invariant mass of the gluon on the anomalous chromomagnetic moment (ACM) of quarks by perturbative calculations at one-loop level. The mass of the gluon is taken to have been generated via a topological mass generation mechanism, in which the gluon acquires a mass through its interaction with an antisymmetric tensor field Bμν. For a small gluon mass ( ACM at momentum transfer q2 = -M Z2. We compare those with the ACM calculated for the gluon mass arising from a Proca mass term. We find that the ACM of up, down, strange and charm quarks vary significantly with the gluon mass, while the ACM of top and bottom quarks show negligible gluon mass dependence. The mechanism of gluon mass generation is most important for the strange quarks ACM, but not so much for the other quarks. We also show the results at q2 = -m t2. We find that the dependence on gluon mass at q2 = -m t2 is much less than at q2 = -M Z2 for all quarks.

Gluon Polarisation Measurements at COMPASS

CERN Document Server

Silva, Luís

2012-01-01

One of the missing keys in the present understanding of the spin structure of the nucleon is the contribution from the gluons: the so-called gluon polarisation. This quantity can be determined in DIS through the photon-gluon fusion process, in which two analysis methods may be used: (i) identifying open charm events or (ii) selecting events with high $p_{T}$ hadrons. The data used in the present work were collected in the COMPASS experiment, where a 160 GeV/c naturally polarised muon beam, impinging on a polarised nucleon fixed target is used. Preliminary results for the gluon polarisation from high $p_{T}$ and open charm analyses are presented. The gluon polarisation result for high $p_{T}$ hadrons is divided, for the first time, into three statistically independent measurements at LO. The result from open charm analysis is obtained at LO and NLO. In both analyses a new weighted method based on a neural network approach is used.

Critical current of Josephson contacts with accidental position of vortexes

International Nuclear Information System (INIS)

Fistul', M.V.

1989-01-01

Josephson contact critical current dependence on magnetic field under different concentrations of Abrikosov vortices (AV) in superconducting shores is found. Pinned vortex concentration as well as correlation in the vortex position can be determined by Josephson current dependence on magnetic field

One gluon, two gluon: multigluon production via high energy evolution

International Nuclear Information System (INIS)

Kovner, Alex; Lublinsky, Michael

2006-01-01

We develop an approach for calculating the inclusive multigluon production within the JIMWLK high energy evolution. We give a formal expression of multigluon cross section in terms of a generating functional for arbitrary number of gluons n. In the dipole limit the expression simplifies dramatically. We recover the previously known results for single and double gluon inclusive cross section and generalize those for arbitrary multigluon amplitude in terms of Feynman diagramms of Pomeron - like objects coupled to external rapidity dependent field s(η). We confirm the conclusion that the AGK cutting rules in general are violated in multigluon production. However we present an argument to the effect that for doubly inclusive cross section the AGK diagramms give the leading contribution at high energy, while genuine violation only occurs for triple and higher inclusive gluon production. We discuss some general properties of our expressions and suggest a line of argument to simplify the approach further

Solitary magnetohydrodynamic vortices

International Nuclear Information System (INIS)

Silaev, I.I.; Skvortsov, A.T.

1990-01-01

This paper reports on the analytical description of fluid flow by means of localized vortices which is traditional for hydrodynamics, oceanology, plasma physics. Recently it has been widely applied to different structure turbulence models. Considerable results involved have been presented where it was shown that in magnetohydrodynamics alongside with the well-known kinds of localized vortices (e.g. Hill's vortex), which are characterized by quite a weak decrease of disturbed velocity or magnetic field (as a power of the inverse distance from vortex center), the vortices with screening (or solitary vortices) may exist. All disturbed parameters either exponentially vanish or become identically zero in outer region in the latter case. (In a number of papers numerical simulations of such the vortices are presented). Solutions in a form of solitary vortices are of particular interest due to their uniformity and solitonlike behavior. On the basis of these properties one can believe for such structures to occur in real turbulent flows

Vortices, semi-local vortices in gauged linear sigma model

International Nuclear Information System (INIS)

Kim, Namkwon

1998-11-01

We consider the static (2+1)D gauged linear sigma model. By analyzing the governing system of partial differential equations, we investigate various aspects of the model. We show the existence of energy finite vortices under a partially broken symmetry on R 2 with the necessary condition suggested by Y. Yang. We also introduce generalized semi-local vortices and show the existence of energy finite semi-local vortices under a certain condition. The vacuum manifold for the semi-local vortices turns out to be graded. Besides, with a special choice of a representation, we show that the O(3) sigma model of which target space is nonlinear is a singular limit of the gauged linear sigma model of which target space is linear. (author)

Bound states of quarks and gluons and hadronic transitions; Estados ligados de quarks e gluons e transicoes hadronicas

Energy Technology Data Exchange (ETDEWEB)

Castro, Antonio Soares de

1990-05-01

A potential which incorporates the concepts of confinement and asymptotic freedom, previously utilized in the description of the spectroscopy of mesons and baryons, is extended to the gluon sector. The mass spectroscopy of glueballs and hybrids is analyzed considering only pairwise potentials and massive constituent gluons. The mass spectrum of the color octet two-gluon system is adopted as a suitable description of the intermediate states of hadronic transitions, within the framework of the multipole expansion for quantum chromodynamics. The spin-dependent effects in the gluonium spectrum, associated with the Coulombian potential, are calculated through the inverted first Born approximation for the gluon-gluon scattering. (author). 102 refs, 1 fig, 13 tabs.

The Gluon Sivers Distribution: Status and Future Prospects

International Nuclear Information System (INIS)

Zhou, Jian; Boer, Daniël; Pisano, Cristian; Lorcé, Cédric

2015-01-01

We review what is currently known about the gluon Sivers distribution and what are the opportunities to learn more about it. Because single transverse spin asymmetries in p"↑p→πX provide only indirect information about the gluon Sivers function through the relation with the quark-gluon and tri-gluon Qiu-Sterman functions, current data from hadronic collisions at RHIC have not yet been translated into a solid constraint on the gluon Sivers function. SIDIS data, including the COMPASS deuteron data, allow for a gluon Sivers contribution of natural size expected from large N_c arguments, which is O(1/N_c) times the nonsinglet quark Sivers contribution. Several very promising processes to measure the gluon Sivers effect directly have been suggested, which besides RHIC investigations, would strongly favor experiments at AFTER@LHC and a possible future Electron-Ion Collider. Due to the inherent process dependence of TMDs, the gluon Sivers TMD probed in the various processes are different linear combinations of two universal gluon Sivers functions that have different behavior under charge conjugation and that therefore satisfy different theoretical constraints. For this reason both hadronic and DIS type of collisions are essential in the study of the role of gluons in transversely polarized protons.

The Elusive Gluon

CERN Document Server

Chala, Mikael; Perez, Gilad; Santiago, Jose

2015-01-01

We study the phenomenology of vector resonances in the context of natural composite Higgs models. A mild hierarchy between the fermionic partners and the vector resonances can be expected in these models based on the following arguments. Both direct and indirect (electroweak and flavor precision) constraints on fermionic partners are milder than the ones on spin one resonances. Also the naturalness pressure coming from the top partners is stronger than that induced by the gauge partners. This observation implies that the search strategy for vector resonances at the LHC needs to be modified. In particular, we point out the importance of heavy gluon decays (or other vector resonances) to top partner pairs that were overlooked in previous experimental searches at the LHC. These searches focused on simplified benchmark models in which the only new particle beyond the Standard Model was the heavy gluon. It turns out that, when kinematically allowed, such heavy-heavy decays make the heavy gluon elusive, and the bou...

Quark gluon plasma

CERN Document Server

Nayak, Tapan; Sarkar, Sourav

2014-01-01

At extremely high temperatures and densities, protons and neutrons may dissolve into a "soup" of quarks and gluons, called the Quark-Gluon Plasma (QGP). For a few microseconds, shortly after the Big Bang, the Universe was filled with the QGP matter. The search and study of Quark-Gluon Plasma (QGP) is one of the most fundamental research topics of our times. The QGP matter has been probed by colliding heavy ions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory, New York and the Large Hadron Collider at CERN, Geneva. By colliding heavy-ions at a speed close to that of light, scientists aim to obtain - albeit over a tiny volume of the size of a nucleus and for an infinitesimally short instant - a QGP state. This QGP state can be observed by dedicated experiments, as it reverts to hadronic matter through expansion and cooling. This volume presents some of the current theoretical and experimental understandings in the field of QGP.

The quark gluon plasma

International Nuclear Information System (INIS)

Granier de Cassagnac, R.

2010-01-01

The quark-gluon plasma (QGP) is a state of matter in which the universe was expected to be a few micro-seconds after the big-bang. Violent collisions of heavy ions are supposed to re-create this state in particle accelerators. Numerous signatures of this fugacious state have already been observed at the RHIC (relativistic heavy ion collider). The first evidence of the violence of collisions is the number of generated particles: about 6000 per collision, mostly hadrons. This figure seems high but in fact is less than theoretically expected and is the first sign of the formation of a QGP that saturates the density of gluons. Another sign, observed at the RHIC is the damping of the particle jets that are produced in the collision. This damping is consistent with the crossing of a medium whose density is so high that it can not be made of hadrons but of partons. In the RHIC experiments the collective behaviour of quarks and gluons shows that they are strongly interacting with one another. This fact supports the idea that the QGP is more a perfect liquid rather than an ideal gas in which quarks and gluons move freely. (A.C.)

TMD splitting functions in kT factorization. The real contribution to the gluon-to-gluon splitting

International Nuclear Information System (INIS)

Hentschinski, M.; Kusina, A.; Kutak, K.; Serino, M.

2018-01-01

We calculate the transverse momentum dependent gluon-to-gluon splitting function within k T -factorization, generalizing the framework employed in the calculation of the quark splitting functions in Hautmann et al. (Nucl Phys B 865:54-66, arXiv:1205.1759, 2012), Gituliar et al. (JHEP 01:181, arXiv:1511.08439, 2016), Hentschinski et al. (Phys Rev D 94(11):114013, arXiv:1607.01507, 2016) and demonstrate at the same time the consistency of the extended formalism with previous results. While existing versions of k T factorized evolution equations contain already a gluon-to-gluon splitting function i.e. the leading order Balitsky-Fadin-Kuraev-Lipatov (BFKL) kernel or the Ciafaloni-Catani-Fiorani-Marchesini (CCFM) kernel, the obtained splitting function has the important property that it reduces both to the leading order BFKL kernel in the high energy limit, to the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) gluon-to-gluon splitting function in the collinear limit as well as to the CCFM kernel in the soft limit. At the same time we demonstrate that this splitting kernel can be obtained from a direct calculation of the QCD Feynman diagrams, based on a combined implementation of the Curci-Furmanski-Petronzio formalism for the calculation of the collinear splitting functions and the framework of high energy factorization. (orig.)

Gluon saturation in a saturated environment

International Nuclear Information System (INIS)

Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan

2011-01-01

A bootstrap equation for self-quenched gluon shadowing leads to a reduced magnitude of broadening for partons propagating through a nucleus. Saturation of small-x gluons in a nucleus, which has the form of transverse momentum broadening of projectile gluons in pA collisions in the nuclear rest frame, leads to a modification of the parton distribution functions in the beam compared with pp collisions. In nucleus-nucleus collisions all participating nucleons acquire enhanced gluon density at small x, which boosts further the saturation scale. Solution of the reciprocity equations for central collisions of two heavy nuclei demonstrate a significant, up to several times, enhancement of Q sA 2 , in AA compared with pA collisions.

Role of the QCD induced gluon-gluon coupling to gauge boson pairs in the multitev region

International Nuclear Information System (INIS)

Ametller, L.; Gava, E.; Paver, N.; Treleani, D.

1985-02-01

We discuss the production of γγ and Zsup(O)γ pairs induced by the gluon-gluon fusion mechanism at typical supercollider energies. Due to the large flux of gluons with small fractional momenta, it is found that in certain kinematical configurations that subprocess, although of order (αsub(S)/π) 2 with respect to the leading quark annihilation, can give an appreciable contribution to the cross-section for Zsup(O)γ and even a larger one for the γγ production. (author)

Macroturbulence in superconductors

International Nuclear Information System (INIS)

Vlasko-Vlasov, V.K.; Nikitenko, V.I.; Polyanskii, A.A.

1994-07-01

Direct magneto-optic observation of coupling of the Abrikosov vortices into macroscopic drops of increased flux density at remagnetization of the YBCO single crystal is presented. Appearance of these flux structures correspond to strong perturbations of the current trajectories and transition fro laminar to turbulent current flow

Three gluon jets as a test of QCD

International Nuclear Information System (INIS)

Koller, K.; Walsh, T.F.

1977-10-01

As a test of quantum chromodynamics (QCD), we suggest looking for gluon jets in the decay of a heavy quark-antiquark bound state produced in e + e - -annihilation, Q anti Q → 3 gluons → 3 gluon jets. In particular, we point out that these events form a jet Dalitz plot, and we calculate the gluon or jet distributions (including the effect of polarized e + e - -beams). This process affords a test of the gluon spin. It is the analogue of two-jet angular distributions in e + e - %→ q anti q → 2 quark jets. We also estimate multiplicities and momentum distributions of hadrons in Q anti Q → 3 gluons → hadrons, using the recently discovered UPSILON (9.4) as an example. (orig.) [de

Semirelativistic potential model for three-gluon glueballs

International Nuclear Information System (INIS)

Mathieu, Vincent; Semay, Claude; Silvestre-Brac, Bernard

2008-01-01

The three-gluon glueball states are studied with the generalization of a semirelativistic potential model giving good results for two-gluon glueballs. The Hamiltonian depends only on 3 parameters fixed on two-gluon glueball spectra: the strong coupling constant, the string tension, and a gluon size which removes singularities in the potential. The Casimir scaling determines the structure of the confinement. Our results are in good agreement with other approaches and lattice calculation for the odderon trajectory but differ strongly from lattice in the J +- sector. We propose a possible explanation for this problem.

Gluon quasidistribution function at one loop

Energy Technology Data Exchange (ETDEWEB)

Wang, Wei; Zhao, Shuai [Shanghai Jiao Tong University, INPAC, Shanghai Key Laboratory for Particle Physics and Cosmology, School of Physics and Astronomy, Shanghai (China); Zhu, Ruilin [Shanghai Jiao Tong University, INPAC, Shanghai Key Laboratory for Particle Physics and Cosmology, School of Physics and Astronomy, Shanghai (China); Nanjing Normal University, Department of Physics and Institute of Theoretical Physics, Nanjing, Jiangsu (China)

2018-02-15

We study the unpolarized gluon quasidistribution function in the nucleon at one loop level in the large momentum effective theory. For the quark quasidistribution, power law ultraviolet divergences arise in the cut-off scheme and an important observation is that they all are subjected to Wilson lines. However for the gluon quasidistribution function, we first point out that the linear ultraviolet divergences also exist in the real diagram which is not connected to any Wilson line. We then study the one loop corrections to parton distribution functions in both cut-off scheme and dimensional regularization to deal with the ultraviolet divergences. In addition to the ordinary quark and gluon distributions, we also include the quark to gluon and gluon to quark splitting diagrams. The complete one-loop matching factors between the quasi and light cone parton distribution functions are presented in the cut-off scheme. We derive the P{sup z} evolution equation for quasi parton distribution functions, and find that the P{sup z} evolution kernels are identical to the DGLAP evolution kernels. (orig.)

Dynamical gluon mass in the instanton vacuum model

Science.gov (United States)

Musakhanov, M.; Egamberdiev, O.

2018-04-01

We consider the modifications of gluon properties in the instanton liquid model (ILM) for the QCD vacuum. Rescattering of gluons on instantons generates the dynamical momentum-dependent gluon mass Mg (q). First, we consider the case of a scalar gluon, no zero-mode problem occurs and its dynamical mass Ms (q) can be found. Using the typical phenomenological values of the average instanton size ρ = 1 / 3 fm and average inter-instanton distance R = 1 fm we get Ms (0) = 256 MeV. We then extend this approach to the real vector gluon with zero-modes carefully considered. We obtain the following expression Mg2 (q) = 2 Ms2 (q). This modification of the gluon in the instanton media will shed light on nonperturbative aspect on heavy quarkonium physics.

Production and recombination of gluons

International Nuclear Information System (INIS)

Temiraliev, A.T.

2006-01-01

Full text: Nonlinear Markov process of parton production has been considered. The Kolmogorov equation is applied for the evolution equation based on the approximation of independent gluons production in every decay act. We introduced a 'crossing' parameter and used the combination relations to obtain nonlinear recombination equation for the evolution of gluon structure function. (author)

The gluon structure of hadrons and nuclei from lattice QCD

Science.gov (United States)

Shanahan, Phiala

2018-03-01

I discuss recent lattice QCD studies of the gluon structure of hadrons and light nuclei. After very briefly highlighting new determinations of the gluon contributions to the nucleon's momentum and spin, presented by several collaborations over the last year, I describe first calculations of gluon generalised form factors. The generalised transversity gluon distributions are of particular interest since they are purely gluonic; they do not mix with quark distributions at leading twist. In light nuclei they moreover provide a clean signature of non-nucleonic gluon degrees of freedom, and I present the first evidence for such effects, based on lattice QCD calculations. The planned Electron-Ion Collider, designed to access gluon structure quantities, will have the capability to test this prediction, and measure a range of gluon observables including generalised gluon distributions and transverse momentum dependent gluon distributions, within the next decade.

The elusive gluon

International Nuclear Information System (INIS)

Chala, Mikael; Juknevich, Jose; Perez, Gilad

2014-11-01

We study the phenomenology of vector resonances in the context of natural composite Higgs models. A mild hierarchy between the fermionic partners and the vector resonances can be expected in these models based on the following arguments. Both direct and indirect (electroweak and flavor precision) constraints on fermionic partners are milder than the ones on spin one resonances. Also the naturalness pressure coming from the top partners is stronger than that induced by the gauge partners. This observation implies that the search strategy for vector resonances at the LHC needs to be modified. In particular, we point out the importance of heavy gluon decays (or other vector resonances) to top partner pairs that were overlooked in previous experimental searches at the LHC. These searches focused on simplified benchmark models in which the only new particle beyond the Standard Model was the heavy gluon. It turns out that, when kinematically allowed, such heavy-heavy decays make the heavy gluon elusive, and the bounds on its mass can be up to 2 TeV milder than in the simpler models considered so far for the LHC14. We discuss the origin of this difference and prospects for dedicated searches.

The elusive gluon

Energy Technology Data Exchange (ETDEWEB)

Chala, Mikael [Granada Univ. (Spain). CAFPE; Granada Univ. (Spain). Dept. de Fisica Teorica y del Cosmos; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Juknevich, Jose [International School for Advanced Studies, Trieste (Italy); Istituto Nazionale di Fisica Nucleare, Trieste (Italy); Perez, Gilad [Weizmann Institute of Science, Rehovot (Israel). Dept. of Particle Physics and Astrophysics; Santiago, Jose [Granada Univ. (Spain). CAFPE; Granada Univ. (Spain). Dept. de Fisica Teorica y del Cosmos; European Organization for Nuclear Research (CERN), Geneva (Switzerland)

2014-11-15

We study the phenomenology of vector resonances in the context of natural composite Higgs models. A mild hierarchy between the fermionic partners and the vector resonances can be expected in these models based on the following arguments. Both direct and indirect (electroweak and flavor precision) constraints on fermionic partners are milder than the ones on spin one resonances. Also the naturalness pressure coming from the top partners is stronger than that induced by the gauge partners. This observation implies that the search strategy for vector resonances at the LHC needs to be modified. In particular, we point out the importance of heavy gluon decays (or other vector resonances) to top partner pairs that were overlooked in previous experimental searches at the LHC. These searches focused on simplified benchmark models in which the only new particle beyond the Standard Model was the heavy gluon. It turns out that, when kinematically allowed, such heavy-heavy decays make the heavy gluon elusive, and the bounds on its mass can be up to 2 TeV milder than in the simpler models considered so far for the LHC14. We discuss the origin of this difference and prospects for dedicated searches.

The gluon structure of hadrons and nuclei from lattice QCD

Energy Technology Data Exchange (ETDEWEB)

Shanahan, Phiala A. [College of William and Mary, Williamsburg, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

2018-04-01

I discuss recent lattice QCD studies of the gluon structure of hadrons and light nuclei. After very briefly highlighting new determinations of the gluon contributions to the nucleon's momentum and spin, presented by several collaborations over the last year, I describe first calculations of gluon generalised form factors. The generalised transversity gluon distributions are of particular interest since they are purely gluonic; they do not mix with quark distributions at leading twist. In light nuclei they moreover provide a clean signature of non-nucleonic gluon degrees of freedom, and I present the first evidence for such effects, based on lattice QCD calculations. The planned Electron-Ion Collider, designed to access gluon structure quantities, will have the capability to test this prediction, and measure a range of gluon observables including generalised gluon distributions and transverse momentum dependent gluon distributions, within the next decade.

Selection of Photon Gluon Fusion Events in DIS

International Nuclear Information System (INIS)

Kowalik, K.; Rondio, E.; Sulej, R.; Zaremba, K.

2001-01-01

A selection of the Photon Gluon Fusion (PGF) process with light quarks for deep inelastic scattering events is presented. This process is directly sensitive to gluon polarization and our goal is to find out the most effective selection on a sample of events simulated for the SMC experiment. We compare two general multi-class classification methods - Bayes method and neural network with a conventional selection procedure. The neural network algorithm presented here is a modification of method belonging to the family of directional minimization algorithms. This method is convenient and effective for photon gluon fusion selection and determination of gluon polarization. Finally we present the estimation for precision of gluon polarization for neural network method. (author)

Interferometry with Vortices

Directory of Open Access Journals (Sweden)

P. Senthilkumaran

2012-01-01

Full Text Available Interference of optical beams with optical vortices is often encountered in singular optics. Since interferometry makes the phase observable by intensity measurement, it brings out a host of applications and helps to understand the optical vortex. In this article we present an optical vortex interferometer that can be used in optical testing and has the potential to increase the accuracy of measurements. In an optical vortex interferometer (OVI, a lattice of vortices is formed, and the movement of the cores of these vortices is tracked when one of the interfering beams is deformed. Instead of multiple vortices in an OVI, an isolated single vortex also finds applications in optical testing. Finally, singularity in scalar and vector fields is presented, and the relation between them is illustrated by the superposition of these beams.

Decomposing the Bragg glass and the peak effect in a Type-II superconductor

DEFF Research Database (Denmark)

Toft-Petersen, Rasmus; Abrahamsen, Asger Bech; Balog, Sandor

2018-01-01

. In Type-II superconductors, disorder generally works to pin vortices, giving zero resistivity below a critical current j(c). However, peaks have been observed in the temperature and field dependences of j(c). This peak effect is difficult to explain in terms of an ordered Abrikosov vortex lattice. Here we...

The very hot soup of quarks and gluons; La tres chaude soupe de quarks et de gluons

Energy Technology Data Exchange (ETDEWEB)

Ter Minassian, V.

2010-05-15

The Phenix collaboration at the RHIC collider (Usa) has measured directly, for the first time, the temperature just after 2 gold nuclei have collided. All the experimental conditions were taken to assure that the temperature measured was that of the quark-gluon plasma. The value of this temperature is 4000*10{sup 9} K, which is 1.20 as high as the theoretical temperature threshold for the existence of the quark-gluon plasma. It is a proof that the quark-gluon plasma can be created within the operating conditions of the RHIC. (A.C.)

Equation of state of quasi-free gluon gas

International Nuclear Information System (INIS)

Chakrabarty, Somenath; Syam, Debapriyo

1993-01-01

The object of this work is to derive an equation of state for a system of gluons beyond the deconfining temperature (∼200 MeV) with phenomenological applications in mind. Our starting point is the relativistic virial theorem. We assume that the non-Abelian nature of QCD (especially the confirming gluon-gluon interaction), as far as the gluon gas is concerned, can be accounted for by postulating a bag pressure (B), while the residual interaction among the gluons can be treated as if the problem is Abelian. Near the 'critical' temperature the residual interactions are seen to play an important role. Also the Stefan-Boltzmann constant is required to be replaced by an effective constant having a somewhat smaller value. (Author)

Confinement models for gluons

International Nuclear Information System (INIS)

Khadkikar, S.B.; Vinodkumar, P.C.

1987-04-01

Confinement model for gluons using a 'colour super current' is formulated. An attempt has been made to derive a suitable dielectric function corresponding to the current confinement model. A simple inhomogeneous dielectric confinement model for gluons is studied for comparison. The model Hamiltonians are second quantized and the glueball states are constructed. The spurious motion of the centre of confinement is accounted for. The results of the current confinement scheme are found to be in good agreement with the experimental candidates for glueballs. (author). 16 refs, 3 tabs

The Mixed Quark-Gluon Condensate from the Global Color Symmetry Model

Institute of Scientific and Technical Information of China (English)

ZONG Hong-Shi; PING Jia-Lun; LU Xiao-Fu; WANG Fan; ZHAO En-Guang

2002-01-01

The mixed quark-gluon condensate from the global color symmetry model is derived. It is shown that themixed quark-gluon condensate depends explicitly on the gluon propagator. This interesting feature may be regarded asan additional constraint on the model of gluon propagator. The values of the mixed quark-gluon condensate from someansatz for the gluon propagator are compared with those determined from QCD sum rules.

Effect of a magnetic field on the excess resistance of SNS sandwiches

International Nuclear Information System (INIS)

Logvenov, G.Y.; Ryazanov, V.V.

1983-01-01

The contribution of superconducting plates to the resistance of Ta--Cu--Ta sandwiches in the presence of a magnetic field of up to 170 Ge is investigated. Near the superconducting transition temperature T/sub c/H, the Ta used was in a mixed (vortical) state. It is shown that the presence of gradients of the order parameter near the Abrikosov vortices appreciably changes the penetration depth of a longitudinal electric field into the superconductor and leads to a corresponding change in the excess resistance of SNS sandwiches

Gluon Bremsstrahlung in Weakly-Coupled Plasmas

International Nuclear Information System (INIS)

Arnold, Peter

2009-01-01

I report on some theoretical progress concerning the calculation of gluon bremsstrahlung for very high energy particles crossing a weakly-coupled quark-gluon plasma. (i) I advertise that two of the several formalisms used to study this problem, the BDMPS-Zakharov formalism and the AMY formalism (the latter used only for infinite, uniform media), can be made equivalent when appropriately formulated. (ii) A standard technique to simplify calculations is to expand in inverse powers of logarithms ln(E/T). I give an example where such expansions are found to work well for ω/T≥10 where ω is the bremsstrahlung gluon energy. (iii) Finally, I report on perturbative calculations of q.

Deduction of the in-medium gluon distribution from photon-gluon fusion processes in peripheral ultrarelativistic heavy-ion collisions

International Nuclear Information System (INIS)

Greiner, M.; Hofmann, C.; Schaefer, A.; Soff, G.

1994-08-01

The photon-gluon fusion process into a pair of heavy quarks is studied for peripheral Pb+Pb collisions at LHC energies. The double differential cross section with respect to the invariant mass and the rapidity of the produced quark pair at zero rapidity is directly proportional to the gluon distribution in the nuclear medium. Differential cross sections for the b-quark production lie well in the μbarn/GeV regime which will allow the deduction of the gluon distribution at low x. Rapidity cuts for the actual detectors are also considered. (orig.)

High energy evolution of soft gluon cascades

International Nuclear Information System (INIS)

Shuvaev, A.; Wallon, S.

2006-01-01

In this paper we derive an evolution equation for the gluon density in soft gluon cascades emitted from any colored source, in the leading logarithmic approximation of perturbative QCD. We show that this equation has the same form as the BFKL equation in the forward case. An explicit expression for the total cascade wavefunction involving an arbitrary number of soft gluons is obtained. Renormalization of the colored source wavefunction turns out to be responsible for the reggeization of the source. (orig.)

High energy evolution of soft gluon cascades

Energy Technology Data Exchange (ETDEWEB)

Shuvaev, A. [St. Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg district (Russian Federation); Wallon, S. [Universite Paris XI, Laboratoire de Physique Theorique, Orsay Cedex (France)

2006-04-15

In this paper we derive an evolution equation for the gluon density in soft gluon cascades emitted from any colored source, in the leading logarithmic approximation of perturbative QCD. We show that this equation has the same form as the BFKL equation in the forward case. An explicit expression for the total cascade wavefunction involving an arbitrary number of soft gluons is obtained. Renormalization of the colored source wavefunction turns out to be responsible for the reggeization of the source. (orig.)

Moving vortex matter with coexisting vortices and anti-vortices

International Nuclear Information System (INIS)

Carneiro, Gilson

2009-01-01

Moving vortex matter, driven by transport currents independent of time, in which vortices and anti-vortices coexist is investigated theoretically in thin superconducting films with nanostructured defects. A simple London model is proposed for the vortex dynamics in films with periodic arrays of nanomagnets or cylindrical holes (antidots). Common to these films is that vortex anti-vortex pairs may be created in the vicinity of the defects by relatively small transport currents, because it adds to the current generated by the defects - the nanomagnets screening current, or the antidots backflow current - and may exceed locally the critical value for vortex anti-vortex pair creation. The model assumes that vortex matter dynamics is governed by Langevin equations, modified to account for creation and annihilation of vortex anti-vortex pairs. For pair creation, it is assumed that whenever the total current at some location exceeds a critical value, equal to that needed to separate a vortex from an anti-vortex by a vortex core diameter, a pair is created instantaneously around this location. Pair annihilation occurs by vortex anti-vortex collisions. The model is applied to films at zero external magnetic field and low temperatures. It is found that several moving vortex matter steady-states with equal numbers of vortices and anti-vortices are possible.

Bound states of quarks and gluons and hadronic transitions

International Nuclear Information System (INIS)

Castro, Antonio Soares de.

1990-05-01

A potential which incorporates the concepts of confinement and asymptotic freedom, previously utilized in the description of the spectroscopy of mesons and baryons, is extended to the gluon sector. The mass spectroscopy of glueballs and hybrids is analyzed considering only pairwise potentials and massive constituent gluons. The mass spectrum of the color octet two-gluon system is adopted as a suitable description of the intermediate states of hadronic transitions, within the framework of the multipole expansion for quantum chromodynamics. The spin-dependent effects in the gluonium spectrum, associated with the Coulombian potential, are calculated through the inverted first Born approximation for the gluon-gluon scattering. (author). 102 refs, 1 fig, 13 tabs

Primordial vorticity and gradient expansion

CERN Document Server

Giovannini, Massimo

2012-01-01

The evolution equations of the vorticities of the electrons, ions and photons in a pre-decoupling plasma are derived, in a fully inhomogeneous geometry, by combining the general relativistic gradient expansion and the drift approximation within the Adler-Misner-Deser decomposition. The vorticity transfer between the different species is discussed in this novel framework and a set of general conservation laws, connecting the vorticities of the three-component plasma with the magnetic field intensity, is derived. After demonstrating that a source of large-scale vorticity resides in the spatial gradients of the geometry and of the electromagnetic sources, the total vorticity is estimated to lowest order in the spatial gradients and by enforcing the validity of the momentum constraint. By acknowledging the current bounds on the tensor to scalar ratio in the (minimal) tensor extension of the $\\Lambda$CDM paradigm the maximal comoving magnetic field induced by the total vorticity turns out to be, at most, of the or...

Finiteness of corner vortices

Science.gov (United States)

Kalita, Jiten C.; Biswas, Sougata; Panda, Swapnendu

2018-04-01

Till date, the sequence of vortices present in the solid corners of steady internal viscous incompressible flows was thought to be infinite. However, the already existing and most recent geometric theories on incompressible viscous flows that express vortical structures in terms of critical points in bounded domains indicate a strong opposition to this notion of infiniteness. In this study, we endeavor to bridge the gap between the two opposing stream of thoughts by diagnosing the assumptions of the existing theorems on such vortices. We provide our own set of proofs for establishing the finiteness of the sequence of corner vortices by making use of the continuum hypothesis and Kolmogorov scale, which guarantee a nonzero scale for the smallest vortex structure possible in incompressible viscous flows. We point out that the notion of infiniteness resulting from discrete self-similarity of the vortex structures is not physically feasible. Making use of some elementary concepts of mathematical analysis and our own construction of diametric disks, we conclude that the sequence of corner vortices is finite.

Soft Gluon Radiation off Heavy Quarks beyond Eikonal Approximation

International Nuclear Information System (INIS)

Mazumder, Surasree; Bhattacharyya, Trambak; Abir, Raktim

2016-01-01

We calculate the soft gluon radiation spectrum off heavy quarks (HQs) interacting with light quarks (LQs) beyond small angle scattering (eikonality) approximation and thus generalize the dead-cone formula of heavy quarks extensively used in the literatures of Quark-Gluon Plasma (QGP) phenomenology to the large scattering angle regime which may be important in the energy loss of energetic heavy quarks in the deconfined Quark-Gluon Plasma medium. In the proper limits, we reproduce all the relevant existing formulae for the gluon radiation distribution off energetic quarks, heavy or light, used in the QGP phenomenology.

Infrared Behavior of Gluon and Ghost Propagators in Landau Gauge QCD

International Nuclear Information System (INIS)

von Smekal, L.; Hauck, A.; Alkofer, R.

1997-01-01

A truncation scheme for the Dyson-Schwinger equations of Euclidean QCD in Landau gauge is presented. It implements the Slavnov-Taylor identities for the three-gluon and ghost-gluon vertices, whereas irreducible four-gluon couplings as well as the gluon-ghost and ghost-ghost scattering kernels are neglected. The infrared behavior of gluon and ghost propagators is obtained analytically: The gluon propagator vanishes for small momenta, whereas the ghost propagator diverges strongly. The numerical solutions are compared with recent lattice results. The running coupling approaches a fixed point, α c ≅9.5 , in the infrared. copyright 1997 The American Physical Society

Vorticity and vortex dynamics

CERN Document Server

Wu, Jie-Zhi; Zhou, M-D

2006-01-01

The importance of vorticity and vortex dynamics has now been well rec- nized at both fundamental and applied levels of ?uid dynamics, as already anticipatedbyTruesdellhalfcenturyagowhenhewrotethe?rstmonograph onthesubject, The Kinematics of Vorticity(1954);andasalsoevidencedby the appearance of several books on this ?eld in 1990s. The present book is characterizedbythefollowingfeatures: 1. A basic physical guide throughout the book. The material is directed by a basic observation on the splitting and coupling of two fundamental processes in ?uid motion, i.e., shearing (unique to ?uid) and compre- ing/expanding.Thevorticityplaysakeyroleintheformer,andavortex isnothingbuta?uidbodywithhighconcentrationofvorticitycompared to its surrounding ?uid. Thus, the vorticity and vortex dynamics is - cordinglyde?nedasthetheoryofshearingprocessanditscouplingwith compressing/expandingprocess. 2. A description of the vortex evolution following its entire life.Thisbegins from the generation of vorticity to the formation of thi...

Constituent gluon interpretation of glueballs and gluelumps

International Nuclear Information System (INIS)

Boulanger, N.; Buisseret, F.; Mathieu, V.; Semay, C.

2008-01-01

Arguments are given that support the interpretation of the lattice QCD glueball and gluelump spectra in terms of bound states of massless constituent gluons with helicity 1. In this scheme, we show that the mass hierarchy of the currently known gluelumps and glueballs is mainly due to the number of constituent gluons and can be understood within a simple flux tube model. It is also argued that the lattice QCD 0 +- glueball should be seen as a four-gluon bound state. We finally predict the mass of the 0 - state, not yet computed in lattice QCD. (orig.)

The gluon condensation at high energy hadron collisions

Energy Technology Data Exchange (ETDEWEB)

Zhu, Wei, E-mail: weizhu@mail.ecnu.edu.cn [Department of Physics, East China Normal University, Shanghai 200241 (China); Lan, Jiangshan [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2017-03-15

We report that the saturation/CGC model of gluon distribution is unstable under action of the chaotic solution in a nonlinear QCD evolution equation, and it evolves to the distribution with a sharp peak at the critical momentum. We find that this gluon condensation is caused by a new kind of shadowing–antishadowing effects, and it leads to a series of unexpected effects in high energy hadron collisions including astrophysical events. For example, the extremely intense fluctuations in the transverse-momentum and rapidity distributions of the gluon jets present the gluon-jet bursts; a sudden increase of the proton–proton cross sections may fill the GZK suppression; the blocking QCD evolution will restrict the maximum available energy of the hadron–hadron colliders.

Gluon field distribution in baryons

International Nuclear Information System (INIS)

Bissey, F.; Cao, F-G.; Kitson, A.; Lasscock, B.G.; Leinweber, D.B.; Signal, A.I.; Williams, A.G.; Zanotti, J.M.

2005-01-01

Methods for revealing the distribution of gluon fields within the three-quark static-baryon potential are presented. In particular, we outline methods for studying the sensitivity of the source on the emerging vacuum response for the three-quark system. At the same time, we explore the possibility of revealing gluon-field distributions in three-quark systems in QCD without the use of gauge-dependent smoothing techniques. Renderings of flux tubes from a preliminary high-statistics study on a 12 3 x 24 lattice are presented

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

Quark and gluon jet properties in symmetric three-jet events

CERN Document Server

Buskulic, Damir; De Bonis, I; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Odier, P; Pietrzyk, B; Chmeissani, M; Crespo, J M; Efthymiopoulos, I; Fernández, E; Fernández-Bosman, M; Garrido, L; Juste, A; Martínez, M; Orteu, S; Pacheco, A; Padilla, C; Palla, Fabrizio; Pascual, A; Perlas, J A; Riu, I; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Farilla, A; Gelao, G; Girone, M; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Natali, S; Nuzzo, S; Ranieri, A; Raso, G; Romano, F; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Alemany, R; Bazarko, A O; Bonvicini, G; Cattaneo, M; Comas, P; Coyle, P; Drevermann, H; Forty, Roger W; Frank, M; Hagelberg, R; Harvey, J; Jacobsen, R; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Martin, E B; Mato, P; Minten, Adolf G; Miquel, R; Mir, L M; Moneta, L; Oest, T; Palazzi, P; Pater, J R; Pusztaszeri, J F; Ranjard, F; Rensing, P E; Rolandi, Luigi; Schlatter, W D; Schmelling, M; Schneider, O; Tejessy, W; Tomalin, I R; Venturi, A; Wachsmuth, H W; Wildish, T; Witzeling, W; Wotschack, J; Ajaltouni, Ziad J; Barrès, A; Boyer, C; Falvard, A; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rossignol, J M; Fearnley, Tom; Hansen, J B; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Wäänänen, A; Kyriakis, A; Markou, C; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Zachariadou, K; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Rougé, A; Rumpf, M; Tanaka, R; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Corden, M; Delfino, M C; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Curtis, L; Dorris, S J; Halley, A W; Knowles, I G; Lynch, J G; O'Shea, V; Raine, C; Reeves, P; Scarr, J M; Smith, K; Thompson, A S; Thomson, F; Thorn, S; Turnbull, R M; Becker, U; Braun, O; Geweniger, C; Graefe, G; Hanke, P; Hepp, V; Kluge, E E; Putzer, A; Rensch, B; Schmidt, M; Sommer, J; Stenzel, H; Tittel, K; Werner, S; Wunsch, M; Abbaneo, D; Beuselinck, R; Binnie, David M; Cameron, W; Colling, D J; Dornan, Peter J; Moutoussi, A; Nash, J; San Martin, G; Sedgbeer, J K; Stacey, A M; Dissertori, G; Girtler, P; Kuhn, D; Rudolph, G; Bowdery, C K; Brodbeck, T J; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Sloan, Terence; Whelan, E P; Williams, M I; Galla, A; Greene, A M; Kleinknecht, K; Quast, G; Renk, B; Rohne, E; Sander, H G; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Bencheikh, A M; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Diaconu, C A; Etienne, F; Konstantinidis, N P; Nicod, D; Payre, P; Rousseau, D; Talby, M; Sadouki, A; Thulasidas, M; Trabelsi, K; Abt, I; Assmann, R W; Bauer, C; Blum, Walter; Brown, D; Dietl, H; Dydak, Friedrich; Ganis, G; Gotzhein, C; Jakobs, K; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Wiedenmann, W; Wolf, G; Boucrot, J; Callot, O; Cordier, A; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Nikolic, I A; Park, H J; Park, I C; Schune, M H; Simion, S; Veillet, J J; Videau, I; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Rizzo, G; Sanguinetti, G; Sciabà, A; Spagnolo, P; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Vannini, C; Verdini, P G; Walsh, J; Betteridge, A P; Blair, G A; Bryant, L M; Cerutti, F; Chambers, J T; Gao, Y; Green, M G; Johnson, D L; Medcalf, T; Perrodo, P; Strong, J A; Von Wimmersperg-Töller, J H; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Edwards, M; Maley, P; Norton, P R; Thompson, J C; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Marx, B; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Beddall, A; Booth, C N; Boswell, R; Brew, C A J; Cartwright, S L; Combley, F; Köksal, A; Letho, M; Newton, W M; Rankin, C; Reeve, J; Thompson, L F; Böhrer, A; Brandt, S; Cowan, G D; Feigl, E; Grupen, Claus; Lutters, G; Minguet-Rodríguez, J A; Rivera, F; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Musolino, G; Ragusa, F; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Bellantoni, L; Elmer, P; Feng, Z; Ferguson, D P S; Gao, Y S; González, S; Grahl, J; Greening, T C; Harton, J L; Hayes, O J; Hu, H; McNamara, P A; Nachtman, J M; Orejudos, W; Pan, Y B; Saadi, Y; Schmitt, M; Scott, I J; Sharma, V; Turk, J; Walsh, A M; Wu Sau Lan; Wu, X; Yamartino, J M; Zheng, M; Zobernig, G

1996-01-01

Quark and gluon jets with the same energy, 24GeV, are compared in symmetric three-jet configurations from hadronic Z decays observed by the ALEPH detector. Jets are defined using the Durham algorithm. Gluon jets are identified using an anti-tag on b jets, based on either a track impact parameter method or a high transverse momentum lepton tag. The comparison of gluon and mixed flavour quark jets shows that gluon jets have a softer fragmentation function, a larger angular width and a higher particle multiplicity. Evidence is also presented which shows that the corresponding differences between gluon and heavy flavour jets are significantly smaller.

Quark-gluon plasma, and strangeness

International Nuclear Information System (INIS)

Rafelski, Johann; Letessier, Jean

2002-01-01

In order to recognize the new form of matter created at RHIC and SPS as the deconfined quark-gluon plasma state (QGP), we need to understand the expected properties of this phase near to the conditions of its formation and disintegration. Thus, we first develop a model of QGP considering the constrains arising from QCD properties and lattice results, and explore its properties. In the second part, we describe the kinetic theory of strangeness production in the QGP phase. We show that gluon fusion dominate and evaluate the degree of equilibration expected at RHIC

Holiday fun with soft gluons

CERN Multimedia

CERN. Geneva

2017-01-01

Emissions of soft gluons from energetic particles play an important role in collider processes. While the basic physics of soft emissions is simple, it gives rise to a variety of interesting and intricate phenomena (non-global logs, Glauber phases, super-leading logs, factorization breaking). After an introduction, I will review progress in resummation methods such as Soft-Collinear Effective Theory driven by a better understanding of soft emissions. I will also show some new results for computations of soft-gluon effects in gap-between-jets and isolation-cone cross sections.

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.

The gluon Sivers asymmetry measurements at COMPASS

CERN Document Server

Szabelski, Adam

2018-01-01

The Sivers function describes the correlation between the transverse spin of a nucleon and the transverse motion of its partons. As such, a nonzero Sivers effect for gluons could be a signature of their nonzero orbital angular momentum inside the nucleon. COMPASS has collected data of semi-inclusive deep inelastic scattering by impinging 160 GeV/$c$ muons on transversely polarised proton and deuteron targets. The gluon Sivers asymmetry is extracted from a high-$p_T$ hadron pair sample with the use of monte carlo simulations and the a neural network approach. The results of a similar analysis for a Collins-like asymmetry for gluons will also be given.

The gluon Sivers asymmetry measurements at COMPASS

CERN Document Server

Szabelski, Adam

2017-01-01

The Sivers function describes the correlation between the transverse spin of a nucleon and the transverse motion of its partons. As such, a nonzero Sivers effect for gluons could be a signature of their nonzero orbital angular momentum inside the nucleon. COMPASS has collected data of semi-inclusive deep inelastic scattering by impinging 160 GeV/$c$ muons on transversely polarised proton and deuteron targets. The gluon Sivers asymmetry is extracted from a high-$p_T$ hadron pair sample with the use of monte carlo simulations and the a neural network approach. The results of a similar analysis for a Collins-like asymmetry for gluons will also be given.

Gluon density in nuclei

International Nuclear Information System (INIS)

Ayala, A.L.

1996-01-01

In this talk we present our detailed study (theory and numbers) on the shadowing corrections to the gluon structure functions for nuclei. Starting from rather controversial information on the nucleon structure function which is originated by the recent HERA data, we develop the Glauber approach for the gluon density in a nucleus based on Mueller formula and estimate the value of the shadowing corrections in this case. Then we calculate the first corrections to the Glauber approach and show that these corrections are big. Based on this practical observation we suggest the new evolution equation which takes into account the shadowing corrections and solve it. We hope to convince you that the new evolution equation gives a good theoretical tool to treat the shadowing corrections for the gluons density in a nucleus and, therefore, it is able to provide the theoretically reliable initial conditions for the time evolution of the nucleus-nucleus cascade. The initial conditions should be fixed both theoretically and phenomenologically before to attack such complicated problems as the mixture of hard and soft processes in nucleus-nucleus interactions at high energy or the theoretically reliable approach to hadron or/and parton cascades for high energy nucleus-nucleus interaction. 35 refs., 24 figs., 1 tab

Grain boundary dissipation in high-Tc superconductors

International Nuclear Information System (INIS)

Gray, K.E.; Miller, D.J.; Field, M.B.; Kim, D.H.; Berghuis, P.

2000-01-01

Thin-film and bulk [001] tilt bicrystal grain boundaries (GBs) in YBa 2 Cu 3 O 7 exhibit a strong dependence of critical current density, J c on misorientation angle. What was initially difficult to understand was the 30x smaller J c in bulk GBs which are microscopically more perfect. The authors review an explanation of this zero-field data, which is based on the pinning of Josephson vortices by the meandering found in thin-film GBs. In addition, there is evidence that J c of GBs does not drop as quickly with applied magnetic field as expected by simple Josephson junction models. The long-wavelength pinning potential due to meandering is less effective at high fields, but Gurevich and Cooley (GC) proposed a new mechanism for an enhanced GB J c arising from pinned Abrikosov vortices in the banks of a GB which present a static, quasiperiodic pinning potential to pin GB vortices. They find a peak in J c and an unusual hysteresis which give considerable support to the GC concept. In low fields, the GBs exhibit a larger J c for field cooling, which is opposite to the usual hysteresis but agrees with GC due to the larger Abrikosov vortex density in the banks. Magnetization data on the same sample are consistent including the identification of the irreversibility field

Semirelativistic potential model for low-lying three-gluon glueballs

International Nuclear Information System (INIS)

Mathieu, Vincent; Semay, Claude; Silvestre-Brac, Bernard

2006-01-01

The three-gluon glueball states are studied with the generalization of a semirelativistic potential model giving good results for two-gluon glueballs. The Hamiltonian depends only on 3 parameters fixed on two-gluon glueball spectra: the strong coupling constant, the string tension, and a gluon size which removes singularities in the potential. The Casimir scaling determines the structure of the confinement. Low-lying J PC states are computed and compared with recent lattice calculations. A good agreement is found for 1 -- and 3 -- states, but our model predicts a 2 -- state much higher in energy than the lattice result. The 0 -+ mass is also computed

Quark-gluon mixing in pseudoscalar and tensor mesons

International Nuclear Information System (INIS)

Eremyan, Sh.S.; Nazaryan, A.E.

1986-01-01

A mixing model of quark-antiquark ang gluonium states in η, η', i(1440) pseudoscalar and f, f', Θ(1690) tensor mesons is considered. Description of and predictions for 68 two-particle decays with these particles taking part in them are obtained. It is shown that i(1440) by 85% consists of gluonium and Θ(1690) is a pure gluonic state. The quark-gluon and gluon-gluon couplings in the pseudoscalar sector are obtained to be stronger as compared to the corresponding ones in the tensor case

Gluon and quark jets in a recursive model motivated by quantum chromodynamics

International Nuclear Information System (INIS)

Sukhatme, U.P.

1979-01-01

We compute observable quantities like the multiplicity and momentum distributions of hadrons in gluon and quark jets in the framework of a recursive cascade model, which is strongly motivated by the fundamental interactions of QCD. Fragmentation occurs via 3 types of breakups: quark → meson + quark, gluon → meson + gluon, gluon → quark + antiquark. In our model gluon jets are softer than quark jets. The ratio of gluon jet to quark jet multiplicity is found to be 2 asymptotically, but much less at lower energies. Some phenomenological consequences for γ decay are discussed. (orig.)

Dynamics of nonstationary dipole vortices

DEFF Research Database (Denmark)

Hesthaven, J.S.; Lynov, Jens-Peter; Nycander, J.

1993-01-01

The dynamics of tilted dipole vortices in the equivalent barotropic vorticity (or Hasegawa-Mima) equation is studied. A recent theory is compared with numerical simulations and found to describe the short time behavior of dipole vortices well. In the long time limit the dipoles are found to eithe...... disintegrate or relax toward a steady eastward propagating dipole vortex. This relaxation is a consequence of nonviscous enstrophy loss by the dipole vortex....

Shear and bulk viscosity of high-temperature gluon plasma

Science.gov (United States)

Zhang, Le; Hou, De-Fu

2018-05-01

We calculate the shear viscosity (η) and bulk viscosity (ζ) to entropy density (s) ratios η/s and ζ/s of a gluon plasma system in kinetic theory, including both the elastic {gg}≤ftrightarrow {gg} forward scattering and the inelastic soft gluon bremsstrahlung {gg}≤ftrightarrow {ggg} processes. Due to the suppressed contribution to η and ζ in the {gg}≤ftrightarrow {gg} forward scattering and the effective g≤ftrightarrow {gg} gluon splitting, Arnold, Moore and Yaffe (AMY) and Arnold, Dogan and Moore (ADM) have got the leading order computations for η and ζ in high-temperature QCD matter. In this paper, we calculate the correction to η and ζ in the soft gluon bremsstrahlung {gg}≤ftrightarrow {ggg} process with an analytic method. We find that the contribution of the collision term from the {gg}≤ftrightarrow {ggg} soft gluon bremsstrahlung process is just a small perturbation to the {gg}≤ftrightarrow {gg} scattering process and that the correction is at ∼5% level. Then, we obtain the bulk viscosity of the gluon plasma for the number-changing process. Furthermore, our leading-order result for bulk viscosity is the formula \\zeta \\propto \\tfrac{{α }s2{T}3}{ln}{α }s-1} in high-temperature gluon plasma. Supported by Ministry of Science and Technology of China (MSTC) under the “973” Project (2015CB856904(4)) and National Natural Science Foundation of China (11735007, 11521064)

How classical gluon fields generate odd azimuthal harmonics for the two-gluon correlation function in high-energy collisions

Science.gov (United States)

Kovchegov, Yuri V.; Skokov, Vladimir V.

2018-05-01

We show that, in the saturation/color glass condensate framework, odd azimuthal harmonics of the two-gluon correlation function with a long-range separation in rapidity are generated by the higher-order saturation corrections in the interactions with the projectile and the target. At the very least, the odd harmonics require three scatterings in the projectile and three scatterings in the target. We derive the leading-order expression for the two-gluon production cross section which generates odd harmonics: the expression includes all-order interactions with the target and three interactions with the projectile. We evaluate the obtained expression both analytically and numerically, confirming that the odd-harmonics contribution to the two-gluon production in the saturation framework is nonzero.

In search of the quark-gluon plasma

International Nuclear Information System (INIS)

Schutz, Y.; Delagrange, H.

2002-01-01

This article describes in a very pedagogical manner the ultimate state of matter when quarks are no longer confined in hadrons. This state is called quark and gluon plasma, its existence is suspected through 4 facts: 1) a quark and gluon plasma that has just been created from a high energy ion-collision is mainly made up of light quarks (up and down), then this plasma should evolve towards other quarks (particularly strange quarks) because of the Pauli exclusion principle. This fact has been experimentally confirmed: at the CERN accelerator physicists have detected a higher production of strange hadrons when the energy of the collision increases; 2) some particles like ρ 0 mesons, that are made up of 2 quarks, are massively produced in ion collisions, their mass has been measured at the moment of the collision and later in the quark and gluon plasma, 2 different values have been found so it confirms the theory that predicts that free quarks have a mass that decreases as energy increases; 3) J/Ψ mesons are made up of a charmed quark combined with its anti-quark, physicists have noticed that less J/Ψ mesons are detected when the energy of the collision rises, this result agrees with the fact that in quark gluon plasma where quarks are free and of different colours and flavors, it is highly unlikely that a charmed quark combines with its anti-quark to form a J/Ψ meson; and 4) the theory of the formation of quark gluon plasma predicts that its electromagnetic radiation has a thermal radiation specificity, physicists have studied the radiation spectra emitted in the core of a ion collision, they have shown that it is a thermal radiation and that the temperature of the emitter corresponds to the temperature of a quark gluon plasma. (A.C.)

The gluon contribution to polarised nucleon structure functions

International Nuclear Information System (INIS)

Ross, G.G.; Roberts, R.G.

1990-08-01

As with all parton distributions in quantum chromodynamics (QCD) the separation of polarised nucleon structure functions into gluon and quark contributions must be specified. We consider a definition of the gluon contribution to polarised nucleon structure functions based on exclusive processes which is explicitly gauge invariant, has no regularisation ambiguities, is insensitive to infrared singularities and can be related to other polarised scattering processes. We discuss the relationship of this gluon definition to others that have recently been used and to the estimates that have been made of the gluon contribution using current algebra and other methods. A quantitative analysis of the structure function g 1 (x,Q 2 ) for polarised deep inelastic scattering is carried out, with the aim of examining the importance of the gluon contribution. Using the positivity of parton distributions the magnitude of Δg(x,Q 2 ) is constrained by a realistic estimate of the unpolarised glue. With the appropriate choice of the hard scattering cross-section, Δσ γg , we find that even with a maximally polarised glue (for x > 0.1), some polarised strange quark contribution is still needed by the data of the EMC. (author)

Nonquasineutral electron vortices in nonuniform plasmas

Energy Technology Data Exchange (ETDEWEB)

Angus, J. R.; Richardson, A. S.; Swanekamp, S. B.; Schumer, J. W. [Plasma Physics Division, Naval Research Laboratory, Washington, District of Columbia 20375 (United States); Ottinger, P. F. [Engility Corporation, Chantilly, Virginia 20151 (United States)

2014-11-15

Electron vortices are observed in the numerical simulation of current carrying plasmas on fast time scales where the ion motion can be ignored. In plasmas with nonuniform density n, vortices drift in the B × ∇n direction with a speed that is on the order of the Hall speed. This provides a mechanism for magnetic field penetration into a plasma. Here, we consider strong vortices with rotation speeds V{sub ϕ} close to the speed of light c where the vortex size δ is on the order of the magnetic Debye length λ{sub B}=|B|/4πen and the vortex is thus nonquasineutral. Drifting vortices are typically studied using the electron magnetohydrodynamic model (EMHD), which ignores the displacement current and assumes quasineutrality. However, these assumptions are not strictly valid for drifting vortices when δ ≈ λ{sub B}. In this paper, 2D electron vortices in nonuniform plasmas are studied for the first time using a fully electromagnetic, collisionless fluid code. Relatively large amplitude oscillations with periods that correspond to high frequency extraordinary modes are observed in the average drift speed. The drift speed W is calculated by averaging the electron velocity field over the vorticity. Interestingly, the time-averaged W from these simulations matches very well with W from the much simpler EMHD simulations even for strong vortices with order unity charge density separation.

Composite vortex ordering in superconducting films with arrays of blind holes

International Nuclear Information System (INIS)

Berdiyorov, G R; Milosevic, M V; Peeters, F M

2009-01-01

The pinning properties of a superconducting thin film with a square array of blind holes are studied using the nonlinear Ginzburg-Landau theory. Although blind holes provide a weaker pinning potential than holes (also called antidots), several novel vortex structures are predicted for different size and thickness of the blind holes. Orientational dimer and trimer vortex states as well as concentric vortex shells can nucleate in the blind holes. In addition, we predict the stabilization of giant vortices that may be located both in the pinning centers and/or at the interstitial sites, as well as the combination of giant vortices with sets of individual vortices. For large blind holes, local vortex shell structures inside the blind holes may transfer their symmetry to interstitial vortices as well. The subtle interplay of shell formation and traditional Abrikosov vortex lattices inside the blind holes is also studied for different numbers of trapped vortices.

Quark and gluon jet properties in symmetric three-jet events

Science.gov (United States)

Buskulic, D.; Casper, D.; de Bonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Lucotte, A.; Minard, M.-N.; Odier, P.; Pietrzyk, B.; Chmeissani, M.; Crespo, J. M.; Efthymiopoulos, I.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Juste, A.; Martinez, M.; Orteu, S.; Pacheco, A.; Padilla, C.; Palla, F.; Pascual, A.; Perlas, J. A.; Riu, I.; Sanchez, F.; Teubert, F.; Colaleo, A.; Creanza, D.; de Palma, M.; Farilla, A.; Gelao, G.; Girone, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Marinelli, N.; Natali, S.; Nuzzo, S.; Ranieri, A.; Raso, G.; Romano, F.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Alemany, R.; Bazarko, A. O.; Bonvicini, G.; Cattaneo, M.; Comas, P.; Coyle, P.; Drevermann, H.; Forty, R. W.; Frank, M.; Hagelberg, R.; Harvey, J.; Jacobsen, R.; Janot, P.; Jost, B.; Kneringer, E.; Knobloch, J.; Lehraus, I.; Martin, E. B.; Mato, P.; Minten, A.; Miquel, R.; Mir, Ll. M.; Moneta, L.; Oest, T.; Palazzi, P.; Pater, J. R.; Pusztaszeri, J.-F.; Ranjard, F.; Rensing, P.; Rolandi, L.; Schlatter, D.; Schmelling, M.; Schneider, O.; Tejessy, W.; Tomalin, I. R.; Venturi, A.; Wachsmuth, H.; Wildish, T.; Witzeling, W.; Wotschack, J.; Ajaltouni, Z.; Barrès, A.; Boyer, C.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rossignol, J.-M.; Fearnley, T.; Hansen, J. B.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Wäänänen, A.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Bourdon, P.; Rougé, A.; Rumpf, M.; Tanaka, R.; Valassi, A.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Focardi, E.; Parrini, G.; Corden, M.; Delfino, M.; Georgiopoulos, C.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Dorris, S. J.; Halley, A. W.; Knowles, I. G.; Lynch, J. G.; O'Shea, V.; Raine, C.; Reeves, P.; Scarr, J. M.; Smith, K.; Thompson, A. S.; Thomson, F.; Thorn, S.; Turnbull, R. M.; Becker, U.; Braun, O.; Geweniger, C.; Graefe, G.; Hanke, P.; Hepp, V.; Kluge, E. E.; Putzer, A.; Rensch, B.; Schmidt, M.; Sommer, J.; Stenzel, H.; Tittel, K.; Werner, S.; Wunsch, M.; Abbaneo, D.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Colling, D. J.; Dornan, P. J.; Moutoussi, A.; Nash, J.; San Martin, G.; Sedgbeer, J. K.; Stacey, A. M.; Dissertori, G.; Girtler, P.; Kuhn, D.; Rudolph, G.; Bowdery, C. K.; Brodbeck, T. J.; Colrain, P.; Crawford, G.; Finch, A. J.; Foster, F.; Hughes, G.; Sloan, T.; Whelan, E. P.; Williams, M. I.; Galla, A.; Greene, A. M.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.-G.; van Gemmeren, P.; Zeitnitz, C.; Aubert, J. J.; Bencheikh, A. M.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Calvet, D.; Carr, J.; Diaconu, C.; Etienne, F.; Konstantinidis, N.; Nicod, D.; Payre, P.; Rousseau, D.; Talby, M.; Sadouki, A.; Thulasidas, M.; Trabelsi, K.; Abt, I.; Assmann, R.; Bauer, C.; Blum, W.; Brown, D.; Dietl, H.; Dydak, F.; Ganis, G.; Gotzhein, C.; Jakobs, K.; Kroha, H.; Lütjens, G.; Lutz, G.; Männer, W.; Moser, H.-G.; Richter, R.; Rosado-Schlosser, A.; Schael, S.; Settles, R.; Seywerd, H.; Denis, R. St.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Jacquet, M.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Nikolic, I.; Park, H. J.; Park, I. C.; Schune, M.-H.; Simion, S.; Veillet, J.-J.; Videau, I.; Azzurri, P.; Bagliesi, G.; Batignani, G.; Bettarini, S.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; Dell'Orso, R.; Fantechi, R.; Ferrante, I.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Rizzo, G.; Sanguinetti, G.; Sciabà, A.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Vannini, C.; Verdini, P. G.; Walsh, J.; Betteridge, A. P.; Blair, G. A.; Bryant, L. M.; Cerutti, F.; Chambers, J. T.; Gao, Y.; Green, M. G.; Johnson, D. L.; Medcalf, T.; Perrodo, P.; Strong, J. A.; von Wimmersperg-Toeller, J. H.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Edwards, M.; Maley, P.; Norton, P. R.; Thompson, J. C.; Bloch-Devaux, B.; Colas, P.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Marx, B.; Perez, P.; Rander, J.; Renardy, J.-F.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Johnson, R. P.; Kim, H. Y.; Litke, A. M.; McNeil, M. A.; Taylor, G.; Beddall, A.; Booth, C. N.; Boswell, R.; Brew, C. A. J.; Cartwright, S.; Combley, F.; Koksal, A.; Letho, M.; Newton, W. M.; Rankin, C.; Reeve, J.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Cowan, G.; Feigl, E.; Grupen, C.; Lutters, G.; Minguet-Rodriguez, J.; Rivera, F.; Saraiva, P.; Smolik, L.; Stephan, F.; Apollonio, M.; Bosisio, L.; Della Marina, R.; Giannini, G.; Gobbo, B.; Musolino, G.; Ragusa, F.; Rothberg, J.; Wasserbaech, S.; Armstrong, S. R.; Bellantoni, L.; Elmer, P.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; González, S.; Grahl, J.; Greening, T. C.; Harton, J. L.; Hayes, O. J.; Hu, H.; McNamara, P. A.; Nachtman, J. M.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Schmitt, M.; Scott, I. J.; Sharma, V.; Turk, J. D.; Walsh, A. M.; Wu, Sau Lan; Wu, X.; Yamartino, J. M.; Zheng, M.; Zobernig, G.; Aleph Collaboration

1996-02-01

Quark and gluon jets with the same energy, 24 GeV, are compared in symmetric three-jet configurations from hadronic Z decays observed by the ALEPH detector. Jets are defined using the Durham algorithm. Gluon jets are identified using an anti-tag on b jets, based on a track impact parameter method. The comparison of gluon and mixed flavour quark jets shows that gluon jets have a softer fragmentation function, a larger angular width and a higher particle multiplicity, Evidence is presented which shows that the corresponding differences between gluon and b jets are significantly smaller. In a statistically limited comparison the multiplicity in c jets was found to be comparable with that observed for the jets of mixed quark flavour.

Dynamics of vortices in polariton quantum fluids : From full vortices, to half vortices and vortex pairs

Science.gov (United States)

Deveaud-Plédran, Benoit

2012-02-01

Polariton quantum fluids may be created both spontaneously through a standard phase transition towards a Bose Einstein condensate, or may be resonantly driven with a well-defined speed. Thanks to the photonic component of polaritons, the properties of the quantum fluid may be accessed rather directly with in particular the possibility of detained interferometric studies. Here, I will detail the dynamics of vortices, obtained with a picosecond time resolution, in different configurations, with in particular their phase dynamics. I will show in particular the dynamics the dynamics of spontaneous creation of a vortex, the dissociation of a full vortex into two half vortices as well as the dynamics of the dissociation of a dark soliton line into a street of pairs of vortices. Work done at EPFL by a dream team of Postdocs PhD students and collaborators: K. Lagoudakis, G. Nardin, T. Paraiso, G. Grosso, F. Manni, Y L'eger, M. Portella Oberli, F. Morier-Genoud and the help of our friend theorists V, Savona, M. Vouters and T. Liew.

VORTICAL MODEL OF THE WING COVERED WITH CONTINUOUSLY DISTRIBUTED CIRCULATION OF THE VORTICAL LAYER

Directory of Open Access Journals (Sweden)

B. L. Artamonov

2014-01-01

Full Text Available The linear vortical model ot the final scope of a wing is exsamined. It representis the flat rectangular spatial veil covered with continuously distributed vortical layer. Elements of digitization of a veil are the quadrangular panels laying on its surface. Method, algorithms and the program of calculation of three making vectors of inductive speed from any guided rectangular platform covered with a vortical layer are created. Its intensity linearly changes on the surface of a platform. The decision is received in elementary functions. The numerical way solves the task of a definition of the law of circulation of the attached whirlwinds in scope of a wing and calculation of its aerodynamic characteristics, being based on the accepted vortical model and a hypothesis of flat sections.

Proton-proton elastic scattering with massive gluons

International Nuclear Information System (INIS)

Sauter, Werner K.; Ducati, M.B. Gay

2001-01-01

In this contribution different approaches to generate a gluon mass are discussed. More specially a recent result for the gluon propagator with a dynamical mass, proposal by Gorbar and Natale, is used in connection with the Landshoff-Nachtmann model for the Pomeron to describe the elastic differential cross section for pp scattering, with good agreement. (author)

Improving the simulation of quark and gluon jets with Herwig 7

Energy Technology Data Exchange (ETDEWEB)

Reichelt, Daniel [Technische Universitaet Dresden, Institut fuer Kern- und Teilchenphysik, Dresden (Germany); Richardson, Peter [CERN, Theory Department, Geneva (Switzerland); Durham University, Department of Physics, IPPP, Durham (United Kingdom); Siodmok, Andrzej [Polish Academy of Sciences, Institute of Nuclear Physics, Krakow (Poland)

2017-12-15

The properties of quark and gluon jets, and the differences between them, are increasingly important at the LHC. However, Monte Carlo event generators are normally tuned to data from e{sup +}e{sup -} collisions which are primarily sensitive to quark-initiated jets. In order to improve the description of gluon jets we make improvements to the perturbative and the non-perturbative modelling of gluon jets and include data with gluon-initiated jets in the tuning for the first time. The resultant tunes significantly improve the description of gluon jets and are now the default in Herwig 7.1. (orig.)

The unconfined quarks and gluons

International Nuclear Information System (INIS)

Abdus Salam

1977-01-01

The consequences of the lepton-hadron gauge unification hypothesis with unconfined quarks and gluons being the hall-mark are discussed. Quark and gluon decays into leptons are shown to provide a new source of multileptonic production in NN, νN and μN collisions. A theorem is stated and proved which highlights the differences between the dynamics of gauge versus non-gauge 1 - particles. Empirical manifestations of gauge coloured mesons are discussed. The question of exact confinement or not is concluded to be in the end an empirical one and must be settled in the laboratory

The LPM effect in sequential bremsstrahlung: 4-gluon vertices

Energy Technology Data Exchange (ETDEWEB)

Arnold, Peter; Chang, Han-Chih [Department of Physics, University of Virginia,382 McCormick Road, Charlottesville, Virginia 22904-4714 (United States); Iqbal, Shahin [National Centre for Physics, Quaid-i-Azam University Campus, Islamabad, 45320 (Pakistan)

2016-10-24

The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. In this paper, we continue study of the case when the coherence lengths of two consecutive splitting processes overlap (which is important for understanding corrections to standard treatments of the LPM effect in QCD), avoiding soft-gluon approximations. In particular, this paper completes the calculation of the rate for real double gluon bremsstrahlung from an initial gluon with various simplifying assumptions (thick media; q̂ approximation; and large N{sub c}) by now including processes involving 4-gluon vertices.

Monte Carlo evidence for the gluon-chain model of QCD string formation

International Nuclear Information System (INIS)

Greensite, J.; San Francisco State Univ., CA

1988-08-01

The Monte Carlo method is used to calculate the overlaps string vertical stroken gluons>, where Ψ string [A] is the Yang-Mills wavefunctional due to a static quark-antiquark pair, and vertical stroken gluons > are orthogonal trial states containing n=0, 1, or 2 gluon operators multiplying the true ground state. The calculation is carried out for SU(2) lattice gauge theory in Coulomb gauge, in D=4 dimensions. It is found that the string state is dominated, at small qanti q separations, by the vacuum ('no-gluon') state, at larger separations by the 1-gluon state, and, at the largest separations attempted, the 2-gluon state begins to dominate. This behavior is in qualitative agreement with the gluon-chain model, which is a large-N colors motivated theory of QCD string formation. (orig.)

Ward identities for amplitudes with reggeized gluons

International Nuclear Information System (INIS)

Bartles, J.; Vacca, G.P.

2012-05-01

Starting from the effective action of high energy QCD we derive Ward identities for Green's functions of reggeized gluons. They follow from the gauge invariance of the effective action, and allow to derive new representations of amplitudes containing physical particles as well as reggeized gluons. We explicitly demonstrate their validity for the BFKL kernel, and we present a new derivation of the kernel.

The SU(3) running coupling from lattice gluons

Energy Technology Data Exchange (ETDEWEB)

Parrinello, C. [Edinburgh Univ. (United Kingdom). Dept. of Phys. and Astron.; UKQCD Collaboration

1995-04-01

We provide numerical results for the running coupling in SU(3) Yang-Mills theory as determined from an analysis of lattice two and three-point gluon correlation functions. The coupling is evaluated directly, from first principles, by defining suitable renormalisation constants from the lattice triple gluon vertex and gluon propagator. For momenta larger than 2GeV, the coupling is found to run according to the 2-loop asymptotic formula. The influence of lattice artifacts on the results appears negligible within the precision of our measurements, although further work on this point is in progress. ((orig.)).

Differences between quark and gluon jets at LEP1

CERN Document Server

Boutemeur, Madjid

1997-01-01

A report is ven here on the differences between quark and gluon initiated jets as measured in LEPl. Various measurements, agree qualitatively on the differences between quark and gluon jets. However a direct quantitative comparison among the measurements as well as comparisons between the measurements and analytical calculations are difficult. This is due to the dependence of the results on the selected event topologies and used jet finding algorithms. Topology dependence of the charged particle multiplicity in quark and gluon jets is studied by ALEPH and transverse momentum-like scales are proposed to account for it. OPAL produced the first quantitative test of QCD analytic prediction for the ratio of the mean particle multiplicity between gluon and quark jets valid, at least, for 39 GeV jets.

The structure of the gluon propagator

Energy Technology Data Exchange (ETDEWEB)

Leinweber, D.B.; Parrinello, C.; Skullerud, J.I.; Williams, A.G

1999-03-01

The gluon propagator has been calculated for quenched QCD in the Landau gauge at {beta} = 6.0 for volumes 16{sup 3} x 48 and 32{sup 3} x 64, and at {beta} 6.2 for volume 24{sup 3} x 48. The large volume and different lattice spacings allow us to identify and minimise finite volume and finite lattice spacing artefacts. We also study the tensor structure of the gluon propagator, confirming that it obeys the lattice Landau gauge condition.

EXPLORING THE POLARIZATION OF GLUONS IN THE NUCLEON.

Energy Technology Data Exchange (ETDEWEB)

STRATMANN,M.; VOGELSANG,W.

2007-10-22

We give an overview of the current status of investigations of the polarization of gluons in the nucleon. We describe some of the physics of the spin-dependent gluon parton distribution and its phenomenology in high-energy polarized hadronic scattering. We also review the recent experimental results.

Bounds on the gluon mass from nucleon decay

Energy Technology Data Exchange (ETDEWEB)

Avila, M.A. [Universidad Autonoma del Estado de Morelos, Morelos (Mexico)

2001-04-01

Permanent confinement of quarks is assumed to hold in QCD. However, if the gluon has a small mass it is possible to produce-quarks in hadron decays, high-energy reactions or in the early-universe. This situation is modelled by a quark-diquark potential composed of a linear (or harmonic) plus a Yukawa term. We compare our prediction for the proton decay with the experimental lower bound on its life-time, and obtain an upper bound on the gluon mass. [Spanish] Se supone se cumple el confinamiento permanente de quarks en cromodinamica cuantica. Si el gluon tiene masa pequena es posible producir quarks libres en decaimiento hadronicos, reacciones de altas energias o en el universo temprano. Esta situacion es modelada por un potencial quark-diquark, compuesto de un termino lineal (o armonico) mas un termino Yukawa. Comparamos nuestra prediccion para el decaimiento del proton con la cota inferior experimental de su vida media y obtenemos una cota superior sobre la masa del gluon.

The hadron to quark/gluon transition

International Nuclear Information System (INIS)

Brown, G.E.; Bethe, H.A.; Pizzochero, P.M.

1991-01-01

In this paper we are concerned with the hadron to quark/gluon transition. We describe the equilibrium states of hadronic matter by a Hagedorn spectrum; introducing scaling masses, as dictated by the restoration of chiral invariance with increasing temperature, we show that in the chiral SU(2) f limit there is a maximum hadron temperature (T H ) max ≅ 128 MeV. Since the quark/gluon perturbative phase involves restoration of conformal invariance, we take the bag constant to be the conformal anomaly, i.e. the gluon condensate. The stability condition P QG > 0 for the pressure requires that there is a minimum temperature; we find (T QG ) min ≅ 172 MeV for SU(2) f . According to the simple Hagedorn model, there appears to be a region of temperature between (T H ) max and (T QG ) min in which no admissible equilibrium states exist. Since the two phases cannot exist at a common temperature, in this model there is no QCD phase transition. (orig.)

Vorticity budget of a tornado-like vortex

Energy Technology Data Exchange (ETDEWEB)

Sassa, Koji; Takemura, Saki, E-mail: sassa@kochi-u.ac.jp [Department of Applied Science, Kochi University (Japan)

2011-12-22

We evaluated the vorticity budget of a tornado-like vortex by measuring vertical and horizontal circulations of it. Though spiral horizontal vortices are clearly observed to converge and tilted into the tornado-like vortex, their circulation is quite small. The conversion of the vertical vorticity concentrated at the side of the spiral horizontal vortices was found to mainly contribute to the maintenance of the tornado-like vortex.

Review of vortices in wildland fire

Science.gov (United States)

Jason M. Forthofer; Scott L. Goodrick

2011-01-01

Vortices are almost always present in the wildland fire environment and can sometimes interact with the fire in unpredictable ways, causing extreme fire behavior and safety concerns. In this paper, the current state of knowledge of the interaction of wildland fire and vortices is examined and reviewed. A basic introduction to vorticity is given, and the two common...

Vortices wiggled and dragged

International Nuclear Information System (INIS)

Reichardt, Charles

2008-01-01

When a sufficiently strong magnetic field is applied to a superconductor, some of the field can pierce it through the generation of magnetic vortices, each of which contains a quantized amount of magnetic flux. Although the superconducting state of the material outside each vortex is maintained (and destroyed within each vortex), the interaction of vortices with a current passing through the material can cause them to move, dissipating energy and thereby generating a source of electrical resistance. The ability to manipulate an individual superconducting vortex represents a powerful tool for studying the dynamics of vortices and the superconductors that support them. It could also lead to the development of a new class of fluxon-based electronics.

Gluon 2- and 3-Point Correlation Functions on the Lattice

OpenAIRE

Parrinello, Claudio

1993-01-01

I present some preliminary results, obtained in collaboration with C. Bernard and A. Soni, for the lattice evaluation of 2- and 3-point gluon correlation functions in momentum space, with emphasis on the amputated 3-gluon vertex function. The final goal of this approach is the study of the running QCD coupling constant as defined from the amputated 3-gluon vertex.

2- and 3-point gluon correlation functions on the lattice

Energy Technology Data Exchange (ETDEWEB)

Parrinello, C. (Dept. of Physics, Univ. of Edinburgh (United Kingdom))

1994-04-01

I present some preliminary results, obtained in collaboration with C. Bernard and A. Soni, for the lattice evaluation of 2- and 3-point gluon correlation functions in momentum space, with emphasis on the amputated 3-gluon vertex function. The final goal of this approach is the study of the running QCD coupling constant as defined from the amputated 3-gluon vertex. (orig.)

The gluon distribution at small x - a phenomenological analysis

International Nuclear Information System (INIS)

Harriman, P.N.; Martin, A.D.; Stirling, W.J.; Roberts, R.G.

1990-03-01

The size of the gluon distribution at small χ has important implications for phenomenology at future high energy hadron-hadron and lepton-hadron colliders. We extend a recent global parton distribution fit to investigate the constraints on the gluon from deep inelastic and prompt photon data. In particular, we estimate a band of allowed gluon distributions with qualitatively small-χ behaviour and study the implications of these on a variety of cross sections at high energy pp and ep colliders. (author)

Gluon bremsstrahlung and elastic scattering of hadrons

International Nuclear Information System (INIS)

Povh, B.

2001-01-01

The differential and the total cross sections in high energy hadron-proton interactions give a beautiful insight in the low Q 2 structure of the nucleon. The cross section is composed of two parts: a large energy independent part corresponding to the interaction of the valence quark with the target without gluon radiation and an energy dependent part caused by gluon bremsstrahlung. The gluons are located at small transverse distances of about 0.3 fm from the valence quarks. The model with two scales, the size of the hadron (R 2 ∼ 1 fm 2 ) and the size of the gluonic cloud (r 0 2 ∼ 0.1 fm 2 ), correctly predicts the total and the differential cross sections and the behaviour of diffractive dissociation in hadronic and deep inelastic events. (orig.)

Vertex of three and four gluons in the Yang-Mills theory

International Nuclear Information System (INIS)

Brandt, F.T.C.

1986-01-01

In a general covariant gauge, the structure of the three-point function with one and two external gluons on shell is studied. The contributions which result in the one-loop approximation are expressed in terms of simple functions containing collinear and soft singularities. Furthermore, the contributions asociated with the four-point vertex when all external gluons are on-sheel, are analysed. As an application of these results, the infrared structure of the gluon-gluon scattering amplitude, is studied. (author) [pt

Model independent approach to studies of the confining dual Abrikosov vortex in SU(2) lattice gauge theory

International Nuclear Information System (INIS)

Haymaker, Richard W.; Matsuki, Takayuki

2007-01-01

We address the problem of determining the type I, type II or borderline dual superconductor behavior in maximal Abelian gauge SU(2) through the study of the dual Abrikosov vortex. We find that significant electric currents in the simulation data call into question the use of the dual Ginzburg-Landau Higgs model in interpreting the data. Further, two definitions of the penetration depth parameter take two different values. The splitting of this parameter into two is intricately connected to the existence of electric currents. It is important in our approach that we employ definitions of flux and electric and magnetic currents that respect Maxwell equations exactly for lattice averages independent of lattice spacings. Applied to specific Wilson loop sizes, our conclusions differ from those that use the dual GLH model

Heavy ion collisions, the quark-gluon plasma and antinucleon annihilation

International Nuclear Information System (INIS)

Sarma, Nataraja

1985-01-01

Studies in high energy physics have indicated that nucleon and mesons are composed of quarks confined in bags by the strong colours mediated by gluons. It is reasonably expected that at suitably high baryon density and temperature of the nucleus, these bags of nucleon and mesons fuse into a big bag of quarks or gluons i.e. hadronic matter undergoes transition to a quark-gluon phase. Two techniques to achieve this transition in a laboratory are: (1) collision of two heavy nuclei, and (2) annihilation of antinucleons and antinuclei in nuclear matter. Theoretical studies as well as experimental studies associated with the transition to quark-gluon phase are reviewed. (author)

A thermodynamically general theory for convective vortices

Science.gov (United States)

Renno, Nilton O.

2008-08-01

Convective vortices are common features of atmospheres that absorb lower-entropy-energy at higher temperatures than they reject higher-entropy-energy to space. These vortices range from small to large-scale and play an important role in the vertical transport of heat, momentum, and tracer species. Thus, the development of theoretical models for convective vortices is important to our understanding of some of the basic features of planetary atmospheres. The heat engine framework is a useful tool for studying convective vortices. However, current theories assume that convective vortices are reversible heat engines. Since there are questions about how reversible real atmospheric heat engines are, their usefulness for studying real atmospheric vortices is somewhat controversial. In order to reduce this problem, a theory for convective vortices that includes irreversible processes is proposed. The paper's main result is that the proposed theory provides an expression for the pressure drop along streamlines that includes the effects of irreversible processes. It is shown that a simplified version of this expression is a generalization of Bernoulli's equation to convective circulations. It is speculated that the proposed theory not only explains the intensity, but also sheds light on other basic features of convective vortices such as their physical appearance.

Time dependence of magnetization of high temperature superconductors

International Nuclear Information System (INIS)

Larkin, A.I.; Geshkenbein, V.B.

1988-10-01

Magnetization of high T c superconductors logarithmically decreases with time. There is a maximum in the temperature dependence of the coefficient at this logarithm. If one assumes that there do exist two kinds of pinning centers, then this dependence can be described in the Anderson theory of thermal creeps of Abrikosov's vortices. The temperature dependence of the critical current is also discussed. (author). 23 refs

Vortices on hyperbolic surfaces

International Nuclear Information System (INIS)

Manton, Nicholas S; Rink, Norman A

2010-01-01

It is shown that Abelian Higgs vortices on a hyperbolic surface M can be constructed geometrically from holomorphic maps f: M → N, where N is also a hyperbolic surface. The fields depend on f and on the metrics of M and N. The vortex centres are the ramification points, where the derivative of f vanishes. The magnitude of the Higgs field measures the extent to which f is locally an isometry. Witten's construction of vortices on the hyperbolic plane is rederived, and new examples of vortices on compact surfaces and on hyperbolic surfaces of revolution are obtained. The interpretation of these solutions as SO(3)-invariant, self-dual SU(2) Yang-Mills fields on R 4 is also given.

High energy multi-gluon exchange amplitudes

International Nuclear Information System (INIS)

Jaroszewicz, T.

1980-11-01

We examine perturbative high energy n-gluon exchange amplitudes calculated in the Coulomb gauge. If n exceeds the minimum required by the t-channel quantum numbers, such amplitudes are non-leading in lns. We derive a closed system of coupled integral equations for the corresponding two-particle n-gluon vertices, obtained by summing the leading powers of ln(N μ psup(μ)), where psup(μ) is the incident momentum and Nsup(μ) the gauge-defining vector. Our equations are infra-red finite, provided the external particles are colour singlets. (author)

Forward gluon production in hadron-hadron scattering with Pomeron loops

International Nuclear Information System (INIS)

Iancu, E.

2006-01-01

We discuss new physical phenomena expected in particle production in hadron-hadron collisions at high energy, as a consequence of Pomerons loop effects in the evolution equations for the Color Glass Condensate. We focus on gluon production in asymmetric, 'dilute-dense', collisions: a dilute projectile scatters off a dense hadronic target, whose gluon distribution is highly evolved. This situation is representative for particle production in proton-proton collisions at forward rapidities (say, at LHC) and admits a dipole factorization similar to that of deep inelastic scattering (DIS). We show that at sufficiently large forward rapidities, where the Pomerons loop effects become important in the evolution of the target wavefunction, gluon production is dominated by 'black spots' (saturated gluon configurations) up to very large values of the transverse momentum, well above the average saturation momentum in the target. In this regime, the produced gluon spectrum exhibits diffusive scaling, so like DIS at sufficiently high energy. (authors)

Forward gluon production in hadron-hadron scattering with Pomeron loops

Energy Technology Data Exchange (ETDEWEB)

Iancu, E. [CEA Saclay, Service de Physique Th orique (DSM/SPhT), Unite de recherche associ e au CNRS (URA D2306), 91 - Gif-sur-Yvette (France). Direction des Sciences de la Matiere; Marquet, C.; Soyez, G. [CEA Saclay, Service de Physique Th orique (DSM/SPhT), Unite de recherche associ e au CNRS (URA D2306), 91 - Gif-sur-Yvette (France). Direction des Sciences de la Matiere; Liege Univ., Fundamental Theoretical Physics Group (Belgium)

2006-07-01

We discuss new physical phenomena expected in particle production in hadron-hadron collisions at high energy, as a consequence of Pomerons loop effects in the evolution equations for the Color Glass Condensate. We focus on gluon production in asymmetric, 'dilute-dense', collisions: a dilute projectile scatters off a dense hadronic target, whose gluon distribution is highly evolved. This situation is representative for particle production in proton-proton collisions at forward rapidities (say, at LHC) and admits a dipole factorization similar to that of deep inelastic scattering (DIS). We show that at sufficiently large forward rapidities, where the Pomerons loop effects become important in the evolution of the target wavefunction, gluon production is dominated by 'black spots' (saturated gluon configurations) up to very large values of the transverse momentum, well above the average saturation momentum in the target. In this regime, the produced gluon spectrum exhibits diffusive scaling, so like DIS at sufficiently high energy. (authors)

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)

Thermalization of mini-jets in a quark–gluon plasma

Energy Technology Data Exchange (ETDEWEB)

Iancu, Edmond, E-mail: edmond.iancu@cea.fr; Wu, Bin, E-mail: bin.wu.phys@gmail.com [Institut de Physique Théorique, CEA Saclay, CNRS UMR 3681, F-91191 Gif-sur-Yvette (France); Department of Physics, The Ohio State University, Columbus, OH 43210 (United States)

2016-12-15

We present the complete physical picture for the evolution of a high-energy jet propagating through a weakly-coupled quark-gluon plasma (QGP) by analytical and numerical investigation of thermalization of the soft components of the jet. Our results support the following physical picture: the leading particle emits a significant number of mini-jets which promptly evolve via multiple branching and thus degrade into a myriad of soft gluons, with energies of the order of the medium temperature T. Via elastic collisions with the medium constituents, these soft gluons relax to local thermal equilibrium with the plasma over a time scale which is considerably shorter than the typical lifetime of the mini-jet. The thermalized gluons form a tail which lags behind the hard components of the jet. Together with the background QGP, they behave hydrodynamically.

Quark and gluon propagators in the spherical bag model

Energy Technology Data Exchange (ETDEWEB)

Kulish, Yu V [AN Ukrainskoj SSR, Fiziko-Tekhnicheskij Inst., Kharkov

1983-12-01

The quark and gluon propagators in a spherical cavity have been obtained by summation of the quark field modes (J-1/2, J is the total moment) and gluon field modes (J=1). The requirements for the spatial components of the gluon propagator Gsub(ik)(x, x') and the quark propagator S(x, x') to be Green functions of the wave equations result in the coincidence of directions for anti x and anti x' vectors. Relations have been derived which allow verification of the self-consistency of approximations used to calculate dynamic values.

Quark and gluon propagators in the spherical bag model

International Nuclear Information System (INIS)

Kulish, Yu.V.

1983-01-01

The quark and gluon propagators in a spherical cavity have been obtained by summation of the quark field modes (J-1/2, J is the total moment) and gluon field modes (J=1). The requirements for the spatial components of the gluon propagator Gsub(ik)(x, x') and the quark propagator S(x, x') to be Green functions of the wave equations result in the coincidence of directions for anti x and anti x' vectors. Relations have been derived which allow verification of the self-consistency of approximations used to calculate dynamic values

High energy production of gluons in a quasi-multi-Regge kinematics

International Nuclear Information System (INIS)

Fadin, V.S.; Lipatov, L.N.

1989-01-01

Inelastic gluon-gluon scattering amplitudes in the Born approximation for the quasi-multi-Regge kinematics are calculated, starting with the Veneziano-type expression for the inelastic amplitude of the gluon-tachyon scattering with its subsequent simplification in the region of large energies and the Regge slope α'→0. Results obtained allow one to determine the high order corrections to the gluon Regge trajectory, the reggeon-particle vertices and to the integral kernel of the Bethe-Salpeter equation for the vacuum t-channel partial waves. 10 refs.; 7 figs

Quark vs Gluon Jet Tagging at ATLAS

CERN Document Server

Rubbo, Francesco; The ATLAS collaboration

2017-01-01

Distinguishing quark-initiated from gluon-initiated jets is useful for many measurements and searches at the LHC. We present a quark-initiated versus gluon-initiated jet tagger from the ATLAS experiment using the number of reconstructed charged particles inside the jet. The measurement of the charged-particle multiplicity inside jets from Run 1 is used to derive uncertainties on the tagger performance for Run 2. With an efficiency of 60% to select quark-initiated jets, the efficiency to select gluon-initiated jets is between 10 and 20% across a wide range in jet pT up to 1.5 TeV with about an absolute 5% systematic uncertainty on the efficiencies. In addition, we also present preliminary studies on a tagger for the ATLAS experiment using the full radiation pattern inside a jet processed as images in deep neural network classifiers.

Quantum chromodynamics as effective theory of quarks and composite gluons

International Nuclear Information System (INIS)

Fuss, T.

2004-01-01

The dynamics of quarks is described by a nonperturbatively regularized NJL model which is canonically quantized and fulfil a probability interpretation. The quantum field theory of this model is formulated in a functional space. The wave functions of the quarks and gluons are calculated as eigenstates of Hard-Core equations and the gluons are considered as relativistic bound states of colored quark-antiquark pairs. The effective dynamics of the quarks and gluons is derived from weak mapping in functional space. This leads to the functional formulation of the phenomenological SU(3) local gauge invariant quark-gluon equations in temporal gauge. This means that the local gauge symmetry is a dynamical effect resulting from the quark model

Theory of concentrated vortices an introduction

CERN Document Server

Alekseenko, S V; Okulov, V L

2007-01-01

Vortex motion is one of the basic states of a flowing continuum. Intere- ingly, in many cases vorticity is space-localized, generating concentrated vortices. Vortex filaments having extremely diverse dynamics are the most characteristic examples of such vortices. Notable examples, in particular, include such phenomena as self-inducted motion, various instabilities, wave generation, and vortex breakdown. These effects are typically ma- fested as a spiral (or helical) configuration of a vortex axis. Many publications in the field of hydrodynamics are focused on vortex motion and vortex effects. Only a few books are devoted entirely to v- tices, and even fewer to concentrated vortices. This work aims to highlight the key problems of vortex formation and behavior. The experimental - servations of the authors, the impressive visualizations of concentrated vortices (including helical and spiral) and pictures of vortex breakdown primarily motivated the authors to begin this work. Later, the approach based on the hel...

Modeling of oceanic vortices

Science.gov (United States)

Cushman-Roisin, B.

Following on a tradition of biannual meetings, the 5th Colloquium on the Modeling of Oceanic Vortices was held May 21-23, 1990, at the Thayer School of Engineering at Dartmouth College, Hanover, N.H. The colloquium series, sponsored by the Office of Naval Research, is intended to gather oceanographers who contribute to our understanding of oceanic mesoscale vortices via analytical, numerical and experimental modeling techniques.

Describing gluons at zero and finite temperature

International Nuclear Information System (INIS)

Maas, A.

2010-01-01

Any description of gluons requires a well-defined gauge. This is complicated non-perturbatively by Gribov copies. A possible method-independent gauge definition to resolve this problem is presented and afterwards used to study the properties of gluons at any temperature. It is found that only chromo-electric properties reflect the phase transition. From these the gauge-invariant phase transition temperature is determined for SU(2) and SU(3) Yang-Mills theory independently. (author)

Shadowing of gluons in perturbative QCD: A comparison of different models

International Nuclear Information System (INIS)

Jalilian-Marian, Jamal; Wang, Xin-Nian

2001-01-01

We investigate the different perturbative QCD-based models for nuclear shadowing of gluons. We show that, in the kinematic region appropriate to the BNL relativistic heavy ion collider experiment, all models give similar estimates for the magnitude of gluon shadowing. At scales relevant to CERN large hadron collider (LHC), there is a sizable difference between the predictions of the different models. However, the uncertainties in gluon shadowing coming from a different parametrization of the gluon distribution in nucleons, are larger than those due to different perturbative QCD models of gluon shadowing. We also investigate the effect of initial nonperturbative shadowing on the magnitude of perturbative shadowing and show that the magnitudes of perturbative and nonperturbative shadowing are comparable at RHIC but perturbative shadowing dominates over nonperturbative shadowing at smaller values of x reached at LHC

Quark and gluon condensate in vacuum

International Nuclear Information System (INIS)

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

1979-01-01

The mechanism of quark confinement has been reviewed. The fact that coloured particles in a free state cannot be observed is connected with specific properties of vacuum in quantum chromodynamics. The basic hypothesis consists in the existence of vacuum fields, quark and gluon condensates, which affect the coloured objects. The vacuum transparent relative to noncharged ''white'' states serves as a source of the force acting upon the coloured particles. It has been a sucess to examine strictly the action of the vacuum fields on quarks when the distance between them is relatively small and the force of the vacuum fields on quarks is relatively small too. It is shown that the interaction with the vacuum fields manifests itself earlier than the forces connected with the gluon exchange do. It is assumed that the vacuum condensate of quarks and gluons and its relation to properties of resonances and to the bag model exist in reality. The dispersion sum rules are used for calculating masses and lepton widths of resonances

Soft gluon resummation in the infrared region and the Froissart bound

CERN Document Server

Pancheri, Giulia; Godbole, Rohini M; Srivastava, Yogendra N

2010-01-01

We describe the taming effect induced by soft gluon $k_t$-resummation on the rapid rise of QCD mini-jet contributions to the total cross-sections.This results from an eikonal model in which the rise of the total cross-section is due to mini-jet contribution. We perform the calculation with current Parton Density Functions (PDFs). The impact parameter distribution we use is obtained as the Fourier transform of the resummed $k_t$-distribution of soft gluons emitted from the initial state during the collision.The emission, which is energy dependent, destroys the initial collinearity of partons.In this model, the strong power-like rise due to the increasing number of low-x gluon collisions is tamed by the acollinearity induced by soft gluon kt-resummation down to zero gluon momenta. It explicitly links a singular soft gluon coupling in the infrared region to the behaviour dictated by the Froissart bound for the total cross-section. The model describes well both proton and photon processes at present accelerator e...

Compact vortices

Energy Technology Data Exchange (ETDEWEB)

Bazeia, D.; Losano, L.; Marques, M.A.; Zafalan, I. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, PB (Brazil); Menezes, R. [Universidade Federal da Paraiba, Departamento de Ciencias Exatas, Rio Tinto, PB (Brazil); Universidade Federal de Campina Grande, Departamento de Fisica, Campina Grande, PB (Brazil)

2017-02-15

We study a family of Maxwell-Higgs models, described by the inclusion of a function of the scalar field that represent generalized magnetic permeability. We search for vortex configurations which obey first-order differential equations that solve the equations of motion. We first deal with the asymptotic behavior of the field configurations, and then implement a numerical study of the solutions, the energy density and the magnetic field. We work with the generalized permeability having distinct profiles, giving rise to new models, and we investigate how the vortices behave, compared with the solutions of the corresponding standard models. In particular, we show how to build compact vortices, that is, vortex solutions with the energy density and magnetic field vanishing outside a compact region of the plane. (orig.)

Sources of CAM3 vorticity bias during northern winter from diagnostic study of the vorticity equation

Energy Technology Data Exchange (ETDEWEB)

Grotjahn, Richard [University of California, Department of Land, Air and Water Resources, Davis, CA (United States); Pan, Lin-Lin; Tribbia, Joseph [National Center for Atmospheric Research, Boulder, CO (United States)

2011-06-15

CAM3 (Community Atmosphere Model version 3) simulation bias is diagnosed using the vorticity equation. The study compares CAM3 output with ECMWF (European Centre for Medium-Range Weather Forecasts) 40 year reanalysis (ERA-40) data. A time mean vorticity bias equation is also formulated and the terms are grouped into categories: linear terms, nonlinear terms, transient contributions, and friction (calculated as a residual). Frontal cyclone storms have much weaker band passed kinetic energy and enstrophy in CAM3. The downstream end of the North Atlantic storm track (NAST) has large location error. While the vorticity equation terms have similar amplitude ranking in CAM3 and ERA-40 at upper levels, the ranking differs notably in the lower troposphere. The linear and friction terms dominate the vorticity bias equation. The transient terms contribute along the storm track, but the nonlinear terms are generally much smaller, with the primary exception being over the Iberian peninsula. Friction is much stronger in CAM3. As evidence, nearly all wavelengths (including the longest planetary waves) have smaller amplitude in CAM3 than in ERA-40 vorticity data. Negative near surface vorticity tendency bias on the European side of the Arctic is linked to the NAST track error (evident in the divergence term). CAM3 misses the Beaufort high in sea level pressure (SLP) due to low level warm temperature bias, too little vortex compression, and to too little horizontal advection of negative vorticity compared with ERA-40. Generally lower SLP values in CAM3 over the entire Arctic follow from lower level warm bias in CAM3. (orig.)

Linearly Polarized Gluons and the Higgs Transverse Momentum Distribution

NARCIS (Netherlands)

Boer, Daniel; den Dunnen, Wilco J.; Pisano, Cristian; Schlegel, Marc; Vogelsang, Werner

2012-01-01

We study how gluons carrying linear polarization inside an unpolarized hadron contribute to the transverse momentum distribution of Higgs bosons produced in hadronic collisions. They modify the distribution produced by unpolarized gluons in a characteristic way that could be used to determine

Gluon amplitudes as 2 d conformal correlators

Science.gov (United States)

Pasterski, Sabrina; Shao, Shu-Heng; Strominger, Andrew

2017-10-01

Recently, spin-one wave functions in four dimensions that are conformal primaries of the Lorentz group S L (2 ,C ) were constructed. We compute low-point, tree-level gluon scattering amplitudes in the space of these conformal primary wave functions. The answers have the same conformal covariance as correlators of spin-one primaries in a 2 d CFT. The Britto-Cachazo-Feng-Witten (BCFW) recursion relation between three- and four-point gluon amplitudes is recast into this conformal basis.

Identified particles in quark and gluon jets

CERN Document Server

Abreu, P; Adye, T; Ajinenko, I; Alekseev, G D; Alemany, R; Allport, P P; Almehed, S; Amaldi, Ugo; Amato, S; Andreazza, A; Andrieux, M L; Antilogus, P; Apel, W D; Åsman, B; Augustin, J E; Augustinus, A; Baillon, Paul; Bambade, P; Barão, F; Barbi, M S; Barbiellini, Guido; Bardin, Dimitri Yuri; Barker, G; Baroncelli, A; Bärring, O; Barrio, J A; Bartl, Walter; Bates, M J; Battaglia, Marco; Baubillier, M; Baudot, J; Becks, K H; Begalli, M; Beillière, P; Belokopytov, Yu A; Benvenuti, Alberto C; Berggren, M; Bertini, D; Bertrand, D; Besançon, M; Bianchi, F; Bigi, M; Bilenky, S M; Billoir, P; Bizouard, M A; Bloch, D; Blume, M; Bolognese, T; Bonesini, M; Bonivento, W; Booth, P S L; Bosio, C; Botner, O; Boudinov, E; Bouquet, B; Bourdarios, C; Bowcock, T J V; Bozzo, M; Branchini, P; Brand, K D; Brenke, T; Brenner, R A; Bricman, C; Brown, R C A; Brückman, P; Brunet, J M; Bugge, L; Buran, T; Burgsmüller, T; Buschmann, P; Cabrera, S; Caccia, M; Calvi, M; Camacho-Rozas, A J; Camporesi, T; Canale, V; Canepa, M; Cankocak, K; Cao, F; Carena, F; Carroll, L; Caso, Carlo; Castillo-Gimenez, M V; Cattai, A; Cavallo, F R; Chabaud, V; Charpentier, P; Chaussard, L; Checchia, P; Chelkov, G A; Chen, M; Chierici, R; Chliapnikov, P V; Chochula, P; Chorowicz, V; Chudoba, J; Cindro, V; Collins, P; Contri, R; Cortina, E; Cosme, G; Cossutti, F; Cowell, J H; Crawley, H B; Crennell, D J; Crosetti, G; Cuevas-Maestro, J; Czellar, S; Dahl-Jensen, Erik; Dahm, J; D'Almagne, B; Dam, M; Damgaard, G; Dauncey, P D; Davenport, Martyn; Da Silva, W; Defoix, C; Deghorain, A; Della Ricca, G; Delpierre, P A; Demaria, N; De Angelis, A; de Boer, Wim; De Brabandere, S; De Clercq, C; La Vaissière, C de; De Lotto, B; De Min, A; De Paula, L S; De Saint-Jean, C; Dijkstra, H; Di Ciaccio, Lucia; Di Diodato, A; Djama, F; Djannati, A; Dolbeau, J; Doroba, K; Dracos, M; Drees, J; Drees, K A; Dris, M; Durand, J D; Edsall, D M; Ehret, R; Eigen, G; Ekelöf, T J C; Ekspong, Gösta; Elsing, M; Engel, J P; Erzen, B; Espirito-Santo, M C; Falk, E; Fassouliotis, D; Feindt, Michael; Ferrer, A; Fichet, S; Filippas-Tassos, A; Firestone, A; Fischer, P A; Föth, H; Fokitis, E; Fontanelli, F; Formenti, F; Franek, B J; Frenkiel, P; Fries, D E C; Frodesen, A G; Frühwirth, R; Fulda-Quenzer, F; Fuster, J A; Galloni, A; Gamba, D; Gandelman, M; García, C; García, J; Gaspar, C; Gasparini, U; Gavillet, P; Gazis, E N; Gelé, D; Gerber, J P; Gerdyukov, L N; Gokieli, R; Golob, B; Gopal, Gian P; Gorn, L; Górski, M; Guz, Yu; Gracco, Valerio; Graziani, E; Green, C; Grefrath, A; Gris, P; Grosdidier, G; Grzelak, K; Gumenyuk, S A; Gunnarsson, P; Günther, M; Guy, J; Hahn, F; Hahn, S; Hajduk, Z; Hallgren, A; Hamacher, K; Harris, F J; Hedberg, V; Henriques, R P; Hernández, J J; Herquet, P; Herr, H; Hessing, T L; Heuser, J M; Higón, E; Hilke, Hans Jürgen; Hill, T S; Holmgren, S O; Holt, P J; Holthuizen, D J; Hoorelbeke, S; Houlden, M A; Hrubec, Josef; Huet, K; Hultqvist, K; Jackson, J N; Jacobsson, R; Jalocha, P; Janik, R; Jarlskog, C; Jarlskog, G; Jarry, P; Jean-Marie, B; Johansson, E K; Jönsson, L B; Jönsson, P E; Joram, Christian; Juillot, P; Kaiser, M; Kapusta, F; Karafasoulis, K; Karlsson, M; Karvelas, E; Katargin, A; Katsanevas, S; Katsoufis, E C; Keränen, R; Khokhlov, Yu A; Khomenko, B A; Khovanskii, N N; King, B J; Kjaer, N J; Klapp, O; Klein, H; Klovning, A; Kluit, P M; Köne, B; Kokkinias, P; Koratzinos, M; Korcyl, K; Kostyukhin, V; Kourkoumelis, C; Kuznetsov, O; Krammer, Manfred; Kreuter, C; Kronkvist, I J; Krumshtein, Z; Krupinski, W; Kubinec, P; Kucewicz, W; Kurvinen, K L; Lacasta, C; Laktineh, I; Lamsa, J; Lanceri, L; Lane, D W; Langefeld, P; Lapin, V; Laugier, J P; Lauhakangas, R; Leder, Gerhard; Ledroit, F; Lefébure, V; Legan, C K; Leitner, R; Lemonne, J; Lenzen, Georg; Lepeltier, V; Lesiak, T; Libby, J; Liko, D; Lindner, R; Lipniacka, A; Lippi, I; Lörstad, B; Loken, J G; López, J M; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J N; Maehlum, G; Mahon, J R; Malmgren, T G M; Malychev, V; Mandl, F; Marco, J; Marco, R P; Maréchal, B; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Martínez-Rivero, C; Martínez-Vidal, F; Martí i García, S; Masik, J; Matorras, F; Matteuzzi, C; Matthiae, Giorgio; Mazzucato, M; McCubbin, M L; McKay, R; McNulty, R; Medbo, J; Merk, M; Meroni, C; Meyer, S; Meyer, W T; Michelotto, M; Migliore, E; Mirabito, L; Mitaroff, Winfried A; Mjörnmark, U; Moa, T; Møller, R; Mönig, K; Monge, M R; Morettini, P; Müller, H; Münich, K; Mulders, M; Mundim, L M; Murray, W J; Muryn, B; Myatt, Gerald; Naraghi, F; Navarria, Francesco Luigi; Navas, S; Nawrocki, K; Negri, P; Neumann, W; Neumeister, N; Nicolaidou, R; Nielsen, B S; Nieuwenhuizen, M; Nikolaenko, V; Niss, P; Nomerotski, A; Normand, Ainsley; Novák, M; Oberschulte-Beckmann, W; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, Risto; Österberg, K; Ouraou, A; Paganini, P; Paganoni, M; Pagès, P; Pain, R; Palka, H; Papadopoulou, T D; Papageorgiou, K; Pape, L; Parkes, C; Parodi, F; Passeri, A; Pegoraro, M; Peralta, L; Pernicka, Manfred; Perrotta, A; Petridou, C; Petrolini, A; Petrovykh, M; Phillips, H T; Piana, G; Pierre, F; Pimenta, M; Podobnik, T; Podobrin, O; Pol, M E; Polok, G; Poropat, P; Pozdnyakov, V; Privitera, P; Pukhaeva, N; Pullia, Antonio; Radojicic, D; Ragazzi, S; Rahmani, H; Rames, J; Ratoff, P N; Read, A L; Reale, M; Rebecchi, P; Redaelli, N G; Regler, Meinhard; Reid, D; Reinhardt, R; Renton, P B; Resvanis, L K; Richard, F; Richardson, J; Rídky, J; Rinaudo, G; Ripp, I; Romero, A; Roncagliolo, I; Ronchese, P; Roos, L; Rosenberg, E I; Roudeau, Patrick; Rovelli, T; Rückstuhl, W; Ruhlmann-Kleider, V; Ruiz, A; Rybicki, K; Rybin, A; Saarikko, H; Sacquin, Yu; Sadovskii, A; Sahr, O; Sajot, G; Salt, J; Sánchez, J; Sannino, M; Schimmelpfennig, M; Schneider, H; Schwickerath, U; Schyns, M A E; Sciolla, G; Scuri, F; Seager, P; Sedykh, Yu; Segar, A M; Seitz, A; Sekulin, R L; Serbelloni, L; Shellard, R C; Siegrist, P; Silvestre, R; Simonetti, S; Simonetto, F; Sissakian, A N; Sitár, B; Skaali, T B; Smadja, G; Smirnov, N; Smirnova, O G; Smith, G R; Sosnowski, R; Souza-Santos, D; Spassoff, Tz; Spiriti, E; Sponholz, P; Squarcia, S; Stampfer, D; Stanescu, C; Stanic, S; Stapnes, Steinar; Stavitski, I; Stevenson, K; Stocchi, A; Strauss, J; Strub, R; Stugu, B; Szczekowski, M; Szeptycka, M; Tabarelli de Fatis, T; Tavernet, J P; Chikilev, O G; Thomas, J; Tilquin, A; Timmermans, J; Tkatchev, L G; Todorov, T; Todorova, S; Toet, D Z; Tomaradze, A G; Tomé, B; Tonazzo, A; Tortora, L; Tranströmer, G; Treille, D; Tristram, G; Trombini, A; Troncon, C; Tsirou, A L; Turluer, M L; Tyapkin, I A; Tyndel, M; Tzamarias, S; Überschär, B; Ullaland, O; Uvarov, V; Valenti, G; Vallazza, E; Van der Velde, C; van Apeldoorn, G W; van Dam, P; Van Doninck, W K; Van Eldik, J; Van Lysebetten, A; Vassilopoulos, N; Vegni, G; Ventura, L; Venus, W A; Verbeure, F; Verlato, M; Vertogradov, L S; Vilanova, D; Vincent, P; Vitale, L; Vlasov, E; Vodopyanov, A S; Vrba, V; Wahlen, H; Walck, C; Weierstall, M; Weilhammer, Peter; Weiser, C; Wetherell, Alan M; Wicke, D; Wickens, J H; Wielers, M; Wilkinson, G R; Williams, W S C; Winter, M; Witek, M; Wlodek, T; Woschnagg, K; Yip, K; Yushchenko, O P; Zach, F; Zaitsev, A; Zalewska-Bak, A; Zalewski, Piotr; Zavrtanik, D; Zevgolatakos, E; Zimin, N I; Zito, M; Zontar, D; Zucchelli, G C; Zumerle, G

1997-01-01

A sample of about 1.4 million hadronic \\z decays, selected among the data recorded by the DELPHI detector at LEP during 1994, was used to measure for the first time the momentum spectra of \\kp, \\ko, \\p, \\l and their antiparticles in gluon and quark jets. As observed for inclusive charged particles, the production spectra of identified particles were found to be softer in gluon jets than in quark jets, with a higher total multiplicity.

χc charmonium - a tool to investigate gluon polarization

International Nuclear Information System (INIS)

Batunin, A.V.; Slabospitskij, S.R.

1986-01-01

Production of particles with a hidden charm Χ C in polarized parton beams (quarks or gluons) is studied. Parton polarization is shown to cause the changes of angular distributions of Χ C meson decay products, which allows one to investigate possible gluon polarization in hadrons

Infrared behaviour of three and four gluon vertices in Yang-Mills theory

International Nuclear Information System (INIS)

Brandt, F.T.; Frenkel, J.

1985-01-01

The structure of the 3-point function with one and two external gluons on-shell is studied in a general covariant gauge. The contributions which result in one loop approximation are expressed in terms of simple functions containing collinear and soft singularities. Furthermore, the contributions associated with the 4-point vertex when all external gluons are on-shell are analysed. As an application of these results, the infrared structure of gluon-gluon scattering amplitude is studied. (Author) [pt

Structure functions and pair correlations of the quark-gluon plasma

International Nuclear Information System (INIS)

Thoma, Markus H.

2005-01-01

Recent experiments at RHIC and theoretical considerations indicate that the quark-gluon plasma, present in the fireball of relativistic heavy-ion collisions, might be in a liquid phase. The liquid state can be identified by characteristic correlation and structure functions. Here definitions of the structure functions and pair correlations of the quark-gluon plasma are presented as well as perturbative results. These definitions might be useful for verifying the quark-gluon-plasma liquid in QCD lattice calculations

Heavy Flavour Production as Probe of Gluon Sivers Function

International Nuclear Information System (INIS)

Godbole, Rohini M.; Kaushik, Abhiram; Misra, Anuradha; Rawoot, Vaibhav; Sonawane, Bipin

2017-01-01

Heavy flavour production like J/ψ and D-meson production in scattering of electrons/unpolarized protons off polarized proton target offer promising probes to investigate gluon Sivers function. In this talk, I will summarize our recent work on transverse single spin asymmetry in J/ψ-production and D-meson production in pp↑ scattering using a generalized parton model approach. We compare predictions obtained using different models of gluon Sivers function within this approach and then, taking into account the transverse momentum dependent evolution of the unpolarized parton distribution functions and gluon Sivers function, we study the effect of evolution on asymmetry. (author)

Infra-red ghost contribution to the gluon Green's functions

International Nuclear Information System (INIS)

Paccanoni, F.

1985-01-01

The Schwinger-Dyson equations for the ghost propagator and the ghost-ghost-gluon vertex function are studied in the Landau gauge. A confining infra-red singularity is assumed for the gluon propagator and a suitable approximation is devised for the solution of the integral equations. It is found that the bare values of the ghost propagator and coupling cannot be a consistent solution of either equation. It is determined a possible behaviour of the correction factor for the ghost propagator in the small-momentum limit and discussed the consistency of the approximation schemes for the gluon propagator that neglet Faddeev-Popov ghost

Superconducting superfluids in neutron stars

International Nuclear Information System (INIS)

Carter, B.

2002-01-01

For treatment of the layers below the crust of a neutron star it is useful to employ a relativistic model involving three independently moving constituents, representing superfluid neutrons, superfluid protons, and degenerate negatively charged leptons. A Kalb-Ramond type formulation is used here to develop such a model for the specific purpose of application at the semi macroscopic level characterised by lengthscales that are long compared with the separation between the highly localised and densely packed proton vortices of the Abrikosov type lattice that carries the main part of the magnetic flux, but that are short compared with the separation between the neutron vortices. (orig.)

Travelling water waves with compactly supported vorticity

International Nuclear Information System (INIS)

Shatah, Jalal; Walsh, Samuel; Zeng, Chongchun

2013-01-01

In this paper, we prove the existence of two-dimensional, travelling, capillary-gravity, water waves with compactly supported vorticity. Specifically, we consider the cases where the vorticity is a δ-function (a point vortex), or has small compact support (a vortex patch). Using a global bifurcation theoretic argument, we construct a continuum of finite-amplitude, finite-vorticity solutions for the periodic point vortex problem. For the non-periodic case, with either a vortex point or patch, we prove the existence of a continuum of small-amplitude, small-vorticity solutions. (paper)

The five-gluon amplitude and one-loop integrals

International Nuclear Information System (INIS)

Bern, Z.; Dixon, L.; Kosower, D.A.

1992-12-01

We review the conventional field theory description of the string motivated technique. This technique is applied to the one-loop five-gluon amplitude. To evaluate the amplitude a general method for computing dimensionally regulated one-loop integrals is outlined including results for one-loop integrals required for the pentagon diagram and beyond. Finally, two five-gluon helicity amplitudes are given

Dynamical instabilities in quark-gluon plasma with hard jet

International Nuclear Information System (INIS)

Pavlenko, O.P.

1990-01-01

The dynamical instabilities, whose development can be expected under the hard jet propagating through the quark-gluon plasma, are analyzed. The possible signals of the quark-gluon plasma formation in ultrarelativistic nuclear collisions connected with the development of the plasma-jet instabilities are discussed. 10 refs

Two theoretical treatments of the quark-gluon plasma

International Nuclear Information System (INIS)

Carrington, M.E.

1989-01-01

The study of the quark-gluon plasma is of direct relevance to questions about the confinement properties of QCD and the validity of the standard theory of QCD in a different physical regime. Part 1 of this work contains a brief discussion of the theoretical and numerical evidence for the existence of the quark-gluon plasma. In the next two sections, two different approaches are discussed. In Part 2, the problem is presented in the general framework of kinetic theory. A definition of the Wigner distribution operator is introduced for quarks and a set of kinetic equations are derived for the momentum moments of this operator. A Wigner distribution operator is defined for gluons and the momentum of this operator are calculated and related to physical quantities. In Part 3, a calculation of linear response functions in a hot gluon plasma is presented. Problems related to gauge invariance and to the definition of a thermal ensemble in the presence of unphysical degrees of freedom are discussed. Results in different gauges and with different ensembles are compared, and the implications of the results for plasma oscillations are discussed

Gluon contribution to the Sivers effect. COMPASS results on deuteron target

Directory of Open Access Journals (Sweden)

Szabelski Adam

2015-01-01

Full Text Available Sivers effect for gluons is connected to gluon orbital angular momentum which may be the missing part of the nucleon spin puzzle. We present a method of extraction of Sivers effect for gluons from COMPASS SIDIS data on transversely polarised target. In order to access the Sivers effect for gluons photon-gluon fusion (PGF process is used. To enhance the fraction of PGF in the sample high-pT hadron pair events are selected. The method is based on a assumption that there are 3 processes contributing to the muon-nucleon scattering: PGF, leading process and QCD Compton process. Then one performs a weighting procedure which enables to extract the asymmetries for the 3 contributing processes simultaneously. In order to do that a neural network trained by a Monte Carlo to assign to each event 3 probabilities corresponding to the 3 processes is needed. Finaly we show results of Sivers effect for gluons extraction on COMPASS data with transversely polarised deuteron target. APGFsinΦ2h–ΦS = −0.14 ± 0.15 (stat. at ‹XG› = 0.126.

Vorticity and Λ polarization in baryon rich matter

Science.gov (United States)

Baznat, Mircea; Gudima, Konstantin; Prokhorov, George; Sorin, Alexander; Teryaev, Oleg; Zakharov, Valentin

2018-02-01

The polarization of Λ hyperons due to axial chiral vortical effect is discussed. The effect is proportional to (strange) chemical potential and is pronounced at lower energies in baryon-rich matter. The polarization of ¯ has the same sihn and larger magnitude. The emergence of vortical structures is observed in kinetic QGSM models. The hydrodynamical helicity separation receives the contribution of longitudinal velocity and vorticity implying the quadrupole structure of the latter. The transition from the quark vortical effects to baryons in confined phase may be achieved by exploring the axial charge. At the hadronic level the polarization corresponds to the cores of quantized vortices in pionic superfluid. The chiral vortical effects may be also studied in the frmework of Wigner function establishing the relation to the thermodynamical approach to polarization.

On the application of gluon to heavy quarkonium fragmentation function

International Nuclear Information System (INIS)

Qi Wei; Wang Jianxiong

2007-01-01

We analyze the uncertainties induced by different definitions of the momentum fraction z in the application of gluon to heavy quarkonium fragmentation function. We numerically calculate the initial g→J/ψ fragmentation functions by using the non-covariant definitions of z with finite gluon momentum and find that these fragmentation functions have strong dependence on the gluon momentum k. As |k|→∞, these fragmentation functions approach to the fragmentation function in the light-cone definition. We find that when |k| is small (for instance in the typical energy scale (about 4-20GeV) of the gluon production at the hadron colliders, such as Tevatron and LHC), large uncertainty remains while the in-covariant definitions of z are employed in the application of the fragmentation functions. (authors)

Inclusive gluon production in deep inelastic scattering at high parton density

International Nuclear Information System (INIS)

Kovchegov, Yuri V.; Tuchin, Kirill

2002-01-01

We calculate the cross section of single inclusive gluon production in deep inelastic scattering at very high energies in the saturation regime, where the parton densities inside hadrons and nuclei are large and the evolution of structure functions with energy is nonlinear. The expression we obtain for the inclusive gluon production cross section is generated by this nonlinear evolution. We analyze the rapidity distribution of the produced gluons as well as their transverse momentum spectrum given by the derived expression for the inclusive cross section. We propose an ansatz for the multiplicity distribution of gluons produced in nuclear collisions which includes the effects of nonlinear evolution in both colliding nuclei

Constituent gluons and the static quark potential

Energy Technology Data Exchange (ETDEWEB)

Greensite, Jeff [San Francisco State Univ., CA (United States); Szczepaniak, Adam P. [Indiana Univ., Bloomington, IN (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

2016-04-01

We suggest that Hamiltonian matrix elements between physical states in QCD might be approximated, in Coulomb gauge, by "lattice-improved" tree diagrams; i.e. tree diagram contributions with dressed ghost, transverse gluon, and Coulomb propagators obtained from lattice simulations. Such matrix elements can be applied to a variational treatment of hadronic states which include constituent gluons. As an illustration and first application of this hybrid approach, we derive a variational estimate of the heavy quark potential for distances up to 2.5 fm. The Coulomb string tension in SU(3) gauge theory is about a factor of four times greater than the asymptotic string tension. In our variational approach, using for simplicity a single variational parameter, we can reduce this overshoot by nearly the factor required. The building blocks of our approach are Coulomb gauge propagators, and in this connection we present new lattice results for the ghost and transverse gluon propagators in position space.

On the stability of shear-Alfven vortices

International Nuclear Information System (INIS)

Jovanovic, D.; Horton, W.

1993-08-01

Linear stability of shear-Alfven vortices is studied analytically using the Lyapunov method. Instability is demonstrated for vortices belonging to the drift mode, which is a generalization of the standard Hasegawa-Mima vortex to the case of large parallel phase velocities. In the case of the convective-cell mode, short perpendicular-wavelength perturbations are stable for a broad class of vortices. Eventually, instability of convective-cell vortices may occur on the perpendicular scale comparable with the vortex size, but it is followed by a simultaneous excitation of coherent structures with better localization than the original vortex

Improving the Simulation of Quark and Gluon Jets with Herwig 7 arXiv

CERN Document Server

Reichelt, Daniel; Siodmok, Andrzej

2017-12-16

The properties of quark and gluon jets, and the differences between them, are increasingly important at the LHC. However, Monte Carlo event generators are normally tuned to data from $e^+e^-$ collisions which are primarily sensitive to quark-initiated jets. In order to improve the description of gluon jets we make improvements to the perturbative and the non-perturbative modelling of gluon jets and include data with gluon-initiated jets in the tuning for the first time. The resultant tunes significantly improve the description of gluon jets and are now the default in Herwig 7.1.

Study of gluon condensates using the Bogolyubov transformation

International Nuclear Information System (INIS)

Iracane, Daniel

1985-01-01

We describe the ground state of non-perturbative QCD as a gluon condensate. In the framework of the Coulomb gauge Hamiltonian, we introduce an effective interaction between infrared gluons by removing high-momentum gluons. The Bogoliubov transformation provides us with our variational space. The minimisation over this Fock subspace leads to a non-perturbative vacuum and its excitations. The minimum functional space for a boson dynamic is a distribution set. We find two kinds of condensation. The first one occurs only for zero-momentum states and looks like the Bose Condensation. In the second one, the quasiparticle spectrum shows a finite gap and the vacuum is a superconducting state. We give constraints on the interaction so that the superconducting phase is more bounded than the Bose one. (author) [fr

The gluon Reggeization in perturbative QCD at NLO

Energy Technology Data Exchange (ETDEWEB)

Fadin, V.S. [Novosibirsk State Univ., Institute for Nuclear Physics (Russian Federation)

2005-07-01

The gluon Reggeization is one of the outstanding properties of QCD. It is extremely important for description of high energy processes. In particular, it appears as the basis of the BFKL approach to summation of the terms strengthened by powers of log(1/x). The hypothesis is extremely powerful, since all scattering amplitudes are expressed in terms of the gluon trajectory and several Reggeon vertices. Now the hypothesis is proved in NLA (next-to leading approximation). The proof is based on bootstrap relations. It is shown that an infinite number of these relations is reduced to several bootstrap conditions on the gluon trajectory and the Reggeon vertices. It is shown that fulfillment of these conditions means a proof of the Reggeization hypothesis. All bootstraps conditions are formulated explicitly and are proved to be fulfilled.

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.

Effects of outer perturbances on dynamics of wake vortices

International Nuclear Information System (INIS)

Baranov, N.A.; Belotserkovsky, A.S.; Turchak, L.I.

2004-01-01

One of the problems in aircraft flight safety is reduction of the risk related with aircraft encounter with wake vortices generated by other aircraft. An efficient approach to this problem is design of systems providing information on areas of potential danger of wake vortices to pilots in real time. The main components of such a system are a unit for calculations of wake vortices behind aircraft and a unit for calculations of areas of potential danger. A promising way to development of real time algorithms for calculation of wake vortices is the use of vortex methods in CFD based on the hypothesis of quasi-3D flow in the area of wake vorticity. The mathematical model developed by our team calculates positions and intensity of wake vortices past aircraft taking account of such effects as viscous dissipation of vortices, effects of ambient turbulence, wind shear, as well as viscous interaction between wake vortices and the underlying surface. The necessity of including the last factor could be stems from the fact that in the case where wake vortices are in close proximity of the rigid surface, the viscous interaction between the wake vortices and the surface boundary layer results in the boundary layer separation changing the overall intensity and dynamics of the wake vortices. To evaluate the boundaries of the danger areas the authors use an approach based on calculation of additional aerodynamic forces and moments acting on the aircraft encountering wake vortices by means of evaluation of the aircraft additional velocities and angular rates corresponding to distribution of disturbed velocities on the aircraft surface. These criteria could be based on local characteristics of the vorticity areas or on characteristics related to the perturbation effects on the aircraft. The latter characteristics include the actual aerodynamic roll moment, the maximum angular rate or the maximum roll of the aircraft under perturbations in the wake vortices. To estimate the accuracy

Dynamics of vortices in superconductors

International Nuclear Information System (INIS)

Weinan, E.

1992-01-01

We study the dynamics of vortices in type-II superconductors from the point of view of time-dependent Ginzburg-Landau equations. We outline a proof of existence, uniqueness and regularity of strong solutions for these equations. We then derive reduced systems of ODEs governing the motion of the vortices in the asymptotic limit of large Ginzburg-Landau parameter

Regge behaviour of distribution functions and evolution of gluon ...

Indian Academy of Sciences (India)

work we solved DGLAP evolution equation for gluon distribution function at low-x in next-to-leading order (NLO) and the t and x-evolutions of gluon distribution function thus obtained have been compared with global MRST2004 and GRV98 parametrizations. In PQCD, since the higher-order terms in the leading logarithmic.

Gluon saturation and baryon stopping in the SPS, RHIC, and LHC energy regions

International Nuclear Information System (INIS)

Li Shuang; Feng Shengqin

2012-01-01

A new geometrical scaling method with a gluon saturation rapidity limit is proposed to study the gluon saturation feature of the central rapidity region of relativistic nuclear collisions. The net-baryon number is essentially transported by valence quarks that probe the saturation regime in the target by multiple scattering. We take advantage of the gluon saturation model with geometric scaling of the rapidity limit to investigate net baryon distributions, nuclear stopping power and gluon saturation features in the SPS and RHIC energy regions. Predictions for net baryon rapidity distributions, mean rapidity loss and gluon saturation feature in central Pb + Pb collisions at the LHC are made in this paper. (authors)

The PLUTO experiment at DORIS (DESY) and the discovery of the gluon (A recollection)

International Nuclear Information System (INIS)

Stella, Bruno R.; Meyer, Hans-Juergen

2010-08-01

With the aim of determining the contribution of the PLUTO experiment at the DORIS e + e - storage ring to the discovery of the gluon, as members of this former collaboration we have reconsidered all the scientific material produced by PLUTO in 1978 and the first half of 1979. It is clear that the experiment demonstrated the main decay of the Y(9.46 GeV) resonance to be mediated by 3 gluons, by providing evidence for the agreement of this hypothesis with average values and differential distributions of all possible experimental variables and by excluding all other possible alternative models. Moreover PLUTO measured in June 1979 the matrix element of the 3-gluon decay to be quantitatively as expected by QCD (even after hadronization) and, having checked the possibility to correctly trace the gluons' directions, demonstrated the spin 1 nature of the gluon by excluding spin 0 and spin 1/2. The hadronization of the gluon like a quark jet, hypothesized in the 3-gluon jet Monte Carlo simulation, was compatible with the topological data at this energy and was shown to be an approximation at 10% level for the multiplicity (∼ vertical stroke vertical stroke > -1 ); the right expected gluon fragmentation was needed for the inclusive distributions; this was the first experimental study of (identified) gluon jets. In the following measurements at the PETRA storage ring, these results were confirmed by PLUTO and by three contemporaneous experiments by evidencing at higher energies the gluon radiation (''bremsstrahlung''), the softer one, by jet broadening, and the hard one, by the emission of (now clearly visible) gluon jets by quarks. The gluon's spin 1 particle nature was also confirmed. The PLUTO results on Y decays had been confirmed both by contemporaneous experiments at DORIS (partially) and later (also partially) were confirmed by more sophisticated detectors. (orig.)

Energy dependence of the differences between the quark and gluon jet fragmentation

CERN Document Server

Abreu, P; Adye, T; Agasi, E; Ajinenko, I; Aleksan, Roy; Alekseev, G D; Alemany, R; Allport, P P; Almehed, S; Alvsvaag, S J; Amaldi, Ugo; Amato, S; Andreazza, A; Andrieux, M L; Antilogus, P; Apel, W D; Arnoud, Y; Åsman, B; Augustin, J E; Augustinus, A; Baillon, Paul; Bambade, P; Barão, F; Barate, R; Bardin, Dimitri Yuri; Baroncelli, A; Bärring, O; Barrio, J A; Bartl, Walter; Bates, M J; Battaglia, Marco; Baubillier, M; Baudot, J; Becks, K H; Begalli, M; Beillière, P; Belokopytov, Yu A; Belous, K S; Benvenuti, Alberto C; Berggren, M; Bertrand, D; Bianchi, F; Bigi, M; Bilenky, S M; Billoir, P; Bloch, D; Blume, M; Blyth, S; Bolognese, T; Bonesini, M; Bonivento, W; Booth, P S L; Borisov, G; Bosio, C; Bosworth, S; Botner, O; Bouquet, B; Bourdarios, C; Bowcock, T J V; Bozzo, M; Branchini, P; Brand, K D; Brenke, T; Brenner, R A; Bricman, C; Brillault, L; Brown, R C A; Brückman, P; Brunet, J M; Bugge, L; Buran, T; Burgsmüller, T; Buschmann, P; Buys, A; Cabrera, S; Caccia, M; Calvi, M; Camacho-Rozas, A J; Camporesi, T; Canale, V; Canepa, M; Cankocak, K; Cao, F; Carena, F; Carrilho, P; Carroll, L; Caso, Carlo; Castillo-Gimenez, M V; Cattai, A; Cavallo, F R; Cerrito, L; Chabaud, V; Charpentier, P; Chaussard, L; Chauveau, J; Checchia, P; Chelkov, G A; Chen, M; Chierici, R; Chliapnikov, P V; Chochula, P; Chorowicz, V; Chudoba, J; Cindro, V; Collins, P; Contreras, J L; Contri, R; Cortina, E; Cosme, G; Cossutti, F; Crawley, H B; Crennell, D J; Crosetti, G; Cuevas-Maestro, J; Czellar, S; Dahl-Jensen, Erik; Dahm, J; D'Almagne, B; Dam, M; Damgaard, G; Dauncey, P D; Davenport, Martyn; Da Silva, W; Defoix, C; Deghorain, A; Della Ricca, G; Delpierre, P A; Demaria, N; De Angelis, A; de Boer, Wim; De Brabandere, S; De Clercq, C; La Vaissière, C de; De Lotto, B; De Min, A; De Paula, L S; De Saint-Jean, C; Dijkstra, H; Di Ciaccio, Lucia; Djama, F; Dolbeau, J; Dönszelmann, M; Doroba, K; Dracos, M; Drees, J; Drees, K A; Dris, M; Dufour, Y; Dupont, F; Edsall, D M; Ehret, R; Eigen, G; Ekelöf, T J C; Ekspong, Gösta; Elsing, M; Engel, J P; Ershaidat, N; Erzen, B; Espirito-Santo, M C; Falk, E; Fassouliotis, D; Feindt, Michael; Ferrer, A; Filippas-Tassos, A; Firestone, A; Fischer, P A; Föth, H; Fokitis, E; Fontanelli, F; Formenti, F; Franek, B J; Frenkiel, P; Fries, D E C; Frodesen, A G; Frühwirth, R; Fulda-Quenzer, F; Fuster, J A; Galloni, A; Gamba, D; Gandelman, M; García, C; García, J; Gaspar, C; Gasparini, U; Gavillet, P; Gazis, E N; Gelé, D; Gerber, J P; Gerdyukov, L N; Gibbs, M; Gokieli, R; Golob, B; Gopal, Gian P; Gorn, L; Górski, M; Guz, Yu; Gracco, Valerio; Graziani, E; Grosdidier, G; Grzelak, K; Gumenyuk, S A; Gunnarsson, P; Günther, M; Guy, J; Hahn, F; Hahn, S; Hallgren, A; Hamacher, K; Hao, W; Harris, F J; Hedberg, V; Henriques, R P; Hernández, J J; Herquet, P; Herr, H; Hessing, T L; Higón, E; Hilke, Hans Jürgen; Hill, T S; Holmgren, S O; Holt, P J; Holthuizen, D J; Hoorelbeke, S; Houlden, M A; Hrubec, Josef; Huet, K; Hultqvist, K; Jackson, J N; Jacobsson, R; Jalocha, P; Janik, R; Jarlskog, C; Jarlskog, G; Jarry, P; Jean-Marie, B; Johansson, E K; Jönsson, L B; Jönsson, P E; Joram, Christian; Juillot, P; Kaiser, M; Kapusta, F; Karafasoulis, K; Karlsson, M; Karvelas, E; Katsanevas, S; Katsoufis, E C; Keränen, R; Khomenko, B A; Khovanskii, N N; King, B J; Kjaer, N J; Klapp, O; Klein, H; Klovning, A; Kluit, P M; Köne, B; Kokkinias, P; Koratzinos, M; Korcyl, K; Kostyukhin, V; Kourkoumelis, C; Kuznetsov, O; Kramer, P H; Krammer, Manfred; Kreuter, C; Kronkvist, I J; Krumshtein, Z; Krupinski, W; Kubinec, P; Kucewicz, W; Kurvinen, K L; Lacasta, C; Laktineh, I; Lamblot, S; Lamsa, J; Lanceri, L; Lane, D W; Langefeld, P; Lapin, V; Last, I; Laugier, J P; Lauhakangas, R; Leder, Gerhard; Ledroit, F; Lefébure, V; Legan, C K; Leitner, R; Lemoigne, Y; Lemonne, J; Lenzen, Georg; Lepeltier, V; Lesiak, T; Lindner, R; Lipniacka, A; Lippi, I; Lörstad, B; Loken, J G; López, J M; López-Aguera, M A; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J N; Maehlum, G; Malychev, V; Mandl, F; Marco, J; Maréchal, B; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Maron, T; Martínez-Rivero, C; Martínez-Vidal, F; Martí i García, S; Masik, J; Matorras, F; Matteuzzi, C; Matthiae, Giorgio; Mazzucato, M; McCubbin, M L; McKay, R; McNulty, R; Medbo, J; Meroni, C; Meyer, S; Meyer, W T; Michelotto, M; Migliore, E; Mirabito, L; Mitaroff, Winfried A; Mjörnmark, U; Moa, T; Møller, R; Mönig, K; Monge, M R; Morettini, P; Müller, H; Mundim, L M; Murray, W J; Muryn, B; Myatt, Gerald; Naraghi, F; Navarria, Francesco Luigi; Navas, S; Nawrocki, K; Negri, P; Neumann, W; Neumeister, N; Nicolaidou, R; Nielsen, B S; Nieuwenhuizen, M; Nikolaenko, V; Niss, P; Nomerotski, A; Normand, Ainsley; Oberschulte-Beckmann, W; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, Risto; Österberg, K; Ouraou, A; Paganini, P; Paganoni, M; Pagès, P; Palka, H; Papadopoulou, T D; Papageorgiou, K; Pape, L; Parkes, C; Parodi, F; Passeri, A; Pegoraro, M; Peralta, L; Pernegger, H; Pernicka, Manfred; Perrotta, A; Petridou, C; Petrolini, A; Petrovykh, M; Phillips, H T; Piana, G; Pierre, F; Pimenta, M; Pindo, M; Plaszczynski, S; Podobrin, O; Pol, M E; Polok, G; Poropat, P; Pozdnyakov, V; Prest, M; Privitera, P; Pukhaeva, N; Pullia, Antonio; Radojicic, D; Ragazzi, S; Rahmani, H; Rames, J; Ratoff, P N; Read, A L; Reale, M; Rebecchi, P; Redaelli, N G; Regler, Meinhard; Reid, D; Renton, P B; Resvanis, L K; Richard, F; Richardson, J; Rídky, J; Rinaudo, G; Ripp, I; Romero, A; Roncagliolo, I; Ronchese, P; Roos, L; Rosenberg, E I; Rosso, E; Roudeau, Patrick; Rovelli, T; Rückstuhl, W; Ruhlmann-Kleider, V; Ruiz, A; Saarikko, H; Sacquin, Yu; Sadovskii, A; Sajot, G; Salt, J; Sánchez, J; Sannino, M; Schimmelpfennig, M; Schneider, H; Schwickerath, U; Schyns, M A E; Sciolla, G; Scuri, F; Seager, P; Sedykh, Yu; Segar, A M; Seitz, A; Sekulin, R L; Shellard, R C; Siccama, I; Siegrist, P; Simonetti, S; Simonetto, F; Sissakian, A N; Sitár, B; Skaali, T B; Smadja, G; Smirnov, N; Smirnova, O G; Smith, G R; Sosnowski, R; Souza-Santos, D; Spassoff, Tz; Spiriti, E; Sponholz, P; Squarcia, S; Stanescu, C; Stapnes, Steinar; Stavitski, I; Stichelbaut, F; Stocchi, A; Strauss, J; Strub, R; Stugu, B; Szczekowski, M; Szeptycka, M; Tabarelli de Fatis, T; Tavernet, J P; Chikilev, O G; Tilquin, A; Timmermans, J; Tkatchev, L G; Todorov, T; Toet, D Z; Tomaradze, A G; Tomé, B; Tonazzo, A; Tortora, L; Tranströmer, G; Treille, D; Trischuk, W; Tristram, G; Trombini, A; Troncon, C; Tsirou, A L; Turluer, M L; Tyapkin, I A; Tyndel, M; Tzamarias, S; Überschär, B; Ullaland, O; Uvarov, V; Valenti, G; Vallazza, E; Van der Velde, C; van Apeldoorn, G W; van Dam, P; Van Doninck, W K; Van Eldik, J; Vassilopoulos, N; Vegni, G; Ventura, L; Venus, W A; Verbeure, F; Verlato, M; Vertogradov, L S; Vilanova, D; Vincent, P; Vitale, L; Vlasov, E; Vodopyanov, A S; Vrba, V; Wahlen, H; Walck, C; Waldner, F; Weierstall, M; Weilhammer, Peter; Weiser, C; Wetherell, Alan M; Wicke, D; Wickens, J H; Wielers, M; Wilkinson, G R; Williams, W S C; Winter, M; Witek, M; Woschnagg, K; Yip, K; Yushchenko, O P; Zach, F; Zaitsev, A; Zalewska-Bak, A; Zalewski, Piotr; Zavrtanik, D; Zevgolatakos, E; Zimin, N I; Zito, M; Zontar, D; Zuberi, R; Zucchelli, G C; Zumerle, G; Charpentier, Ph; Gavillet, Ph; Jarlskog, Ch; Papadopoulou, Th D

1996-01-01

Three jet events arising from decays of the Z boson, collected by the DELPHI detector, were used to measure differences in quark and gluon fragmentation. Gluon jets were anti-tagged by identifying b quark jets. Unbiased quark jets came from events with two jets plus one photon. Quark and gluon jet properties in different energy ranges were compared for the first time within the same detector. Quark and gluon jets of nearly the same energy in symmetric three jet event topologies were also compared. Using three independent methods, the average value of the ratio of the mean charged multiplicities of gluon and quark jets is \\[ =1.241\\pm 0.015\\ (stat.) \\pm 0.025\\ (syst.). \\] Gluon jets are broader and produce fragments with a softer energy spectrum than quark jets of equivalent energy. The string effect has been observed in fully symmetric three jet events. The measured ratio R_{\\gamma} of the charged particle flow in the q\\overline{q} inter-jet region of the q\\bar{q}g and q\\bar{q}\\gamma samples agrees with the p...

Quark-Gluon Plasma

CERN Document Server

1990-01-01

This volume contains 14 review articles on the theory and phenomenology of the creation and diagnosis of quark-gluon plasma. They are written by active investigators of in the various research topics, which range from the QCD foundation through transport theory and thermalization models to the examination of possible signatures. The monograph should be useful not only to the experienced researchers in the subject but also to newcomers.

Effects of gluon radiation in hadronic collisions

International Nuclear Information System (INIS)

Gustafson, Goesta.

1989-10-01

In this talk I discuss effects of gluon emission in soft collisions, the so-called 'soft radiation' in the Fritjof model. It is seen e.g. that the pT in the fragmentation regions, the seagull effect, increases with energy in fair agreement with experiments. I also discuss the content of strange and heavier quarks in high-pT gluon jets. Within the dipole scheme for QCD cascades on finds a larger production of heavier quarks than in previous approaches. Qualitative agreement with data is obtained for the K/π ratio and D meson production

Dynamics of fractional vortices in long Josephson junctions

International Nuclear Information System (INIS)

Gaber, Tobias

2007-01-01

In this thesis static and dynamic properties of fractional vortices in long Josephson junctions are investigated. Fractional vortices are circulating supercurrents similar to the well-known Josephson fluxons. Yet, they show the distinguishing property of carrying only a fraction of the magnetic flux quantum. Fractional vortices are interesting non-linear objects. They spontaneously appear and are pinned at the phase discontinuity points of so called 0-κ junctions but can be bend or flipped by external forces like bias currents or magnetic fields. 0-κ junctions and fractional vortices are generalizations of the well-known 0-π junctions and semifluxons, where not only phase jumps of pi but arbitrary values denoted by kappa are considered. By using so-called artificial 0-κ junctions that are based on standard Nb-AlO x -Nb technology the classical dynamics of fractional vortices has been investigated experimentally for the very first time. Here, half-integer zero field steps could be observed. These voltage steps on the junction's current-voltage characteristics correspond to the periodic flipping/hopping of fractional vortices. In addition, the oscillatory eigenmodes of fractional vortices were investigated. In contrast to fluxons fractional vortices have an oscillatory eigenmode with a frequency within the plasma gap. Using resonance spectroscopy the dependence of the eigenmode frequency on the flux carried by the vortex and an applied bias current was determined. (orig.)

Non-perturbative power corrections to ghost and gluon propagators

International Nuclear Information System (INIS)

Boucaud, Philippe; Leroy, Jean-Pierre; Yaouanc, Alain Le; Lokhov, Alexey; Micheli, Jacques; Pene, Olivier; RodrIguez-Quintero, Jose; Roiesnel, Claude

2006-01-01

We study the dominant non-perturbative power corrections to the ghost and gluon propagators in Landau gauge pure Yang-Mills theory using OPE and lattice simulations. The leading order Wilson coefficients are proven to be the same for both propagators. The ratio of the ghost and gluon propagators is thus free from this dominant power correction. Indeed, a purely perturbative fit of this ratio gives smaller value ( ≅ 270MeV) of Λ M-barS-bar than the one obtained from the propagators separately( ≅ 320MeV). This argues in favour of significant non-perturbative ∼ 1/q 2 power corrections in the ghost and gluon propagators. We check the self-consistency of the method

Transverse momentum of gluons in ep-scattering at HERA

International Nuclear Information System (INIS)

Cholewa, A.

2005-11-01

A Monte Carlo analysis of the phase space of hard interacting gluons in ep-scattering is presented. The event generator CASCADE is used in combination with the program HZTOOL to identify the accessible regions of phase space of present HERA measurements. A map of the k t -x g -plane is presented to show that in the region -3≤log g ≤-1 transverse gluon momenta of up to k t >or sim 20 GeV are accessible to HERA measurements. Furthermore the observables x γ and the transverse jet energy E T are found to be highly sensitive to the transverse momentum and the longitudinal momentum fraction of gluons. (orig.) (orig.)

Neural network classification of quark and gluon jets

International Nuclear Information System (INIS)

Graham, M.A.; Jones, L.M.; Herbin, S.

1995-01-01

We demonstrate that there are characteristics common to quark jets and to gluon jets regardless of the interaction that produced them. The classification technique we use depends on the mass of the jet as well as the center-of-mass energy of the hard subprocess that produces the jet. In addition, we present the quark-gluon separability results of an artificial neural network trained on three-jet e + e - events at the Z 0 mass, using a back-propagation algorithm. The inputs to the network are the longitudinal momenta of the leading hadrons in the jet. We tested the network with quark and gluon jets from both e + e - →3 jets and bar pp→2 jets. Finally, we compare the performance of the artificial neural network with the results of making well chosen physical cuts

Gluon asymmetries in the leptoproduction of J/Ψ

International Nuclear Information System (INIS)

Godbole, R.M.; Gupta, S.; Sridhar, K.

1990-07-01

We study J/Ψ production, in deep inelastic scattering experiments with polarised beams and polarised targets. The spin asymmetries are seen to depend strongly on the particular form of the spin dependent gluon distributions used. Therefore, it should be possible in these experiments, to discriminate between different parametrizations of polarised gluon distributions, and hence between the distinctly different physical pictures of the proton spin underlying these parametrizations. (author). 18 refs, 4 figs, 1 tab

Theory of Concentrated Vortices

DEFF Research Database (Denmark)

Alekseenko, Sergey; Kuibin, Pavel; Okulov, Valery

This book presents comprehensive and authoritative coverage of the wide field of concentrated vortices observed in nature and technique. The methods for research of their kinematics and dynamics are considered. Special attention is paid to the flows with helical symmetry. The authors have describ...... models of vortex structures used for interpretation of experimental data which serve as a ground for development of theoretical and numerical approaches to vortex investigation. Achievements in the fields of stability analysis, waves on vortices and vortex breakdown are also presented....

Transverse gluon contributions to the thermal static potential of heavy quarkonium

International Nuclear Information System (INIS)

Zhu, Jia-Qing; Li, Yun-De

2015-01-01

The transverse gluon contributions to the thermal static potentials of heavy quarkonia in isotropic medium are studied. Using the resummation of the damping rates method developed by Hou and Li, the infrared divergence that appeared in the effective potential calculations of transverse gluon is avoided. The comparisons between the transverse and the longitudinal contributions for heavy quarkonia are discussed. The results show that the dissociation scales of quarkonia in thermal medium are decreased by the transverse gluon contributions

Where and how the quark-gluon matter should be searched for?

International Nuclear Information System (INIS)

Strugalski, Z.

1997-01-01

The experimentally based answers are presented to the questions: 1) Where and how the quark-gluon matter should be searched for? 2) How to create objects of highly excited quark-gluon matter? 3) How to study the phase transitions in excited quark-gluon matter? In the argumentation, experimental information has been used about hadron passages through layers of intranuclear matter, about mechanisms of hadron-nucleus and nucleus-nucleus collisions, and about energy transfer from hadronic projectiles to target nuclei

Kinematical Compatibility Conditions for Vorticity Across Shock Waves

Science.gov (United States)

Baty, Roy

2015-11-01

This work develops the general kinematical compatibility conditions for vorticity across arbitrary shock waves in compressible, inviscid fluids. The vorticity compatibility conditions are derived from the curl of the momentum equation using singular distributions defined on two-dimensional shock wave surfaces embedded in three-dimensional flow fields. The singular distributions are represented as generalized differential operators concentrated on moving shock wave surfaces. The derivation of the compatibility conditions for vorticity requires the application of second-order generalized derivatives and elementary tensor algebra. The well-known vorticity jump conditions across a shock wave are then shown to follow from the general kinematical compatibility conditions for vorticity by expressing the flow field velocity in vectorial components normal and tangential to a shock surface.

Differences between quark and gluon jets as seen at LEP

International Nuclear Information System (INIS)

Tasevsky, M.

2001-01-01

The differences between quark and gluon jets are studied using LEP results on jet widths, scale dependent multiplicities, ratios of multiplicities, slopes and curvatures and fragmentation functions. It is emphasized that the observed differences stem primarily from the different quark and gluon colour factors

Accessing the distribution of linearly polarized gluons in unpolarized hadrons

NARCIS (Netherlands)

Boer, Daniël; Brodsky, Stanley J.; Mulders, Piet J.; Pisano, Cristian

2011-01-01

Gluons inside unpolarized hadrons can be linearly polarized provided they have a nonzero transverse momentum. The simplest and theoretically safest way to probe this distribution of linearly polarized gluons is through cos(2 phi) asymmetries in heavy quark pair or dijet production in electron-hadron

Differences between Quark and Gluon jets as seen at LEP

CERN Document Server

Tasevsky, Marek

2001-01-01

The differences between quark and gluon jets are studied using LEP results on jet widths, scale dependent multiplicities, ratios of multiplicities, slopes and curvatures and fragmentation functions. It is emphasized that the observed differences stem primarily from the different quark and gluon colour factors.

Introduction to quantum chromo transport theory for quark-gluon plasmas

International Nuclear Information System (INIS)

Gyulassy, M.; Elze, H.Th.; Iwazaki, A.; Vasak, D.

1986-08-01

Upcoming heavy ion experiments at the AGS and SPS are aimed at producing and diagnosing a primordial form of matter, the quark-gluon plasma. In these lectures some recent developments on formulating a quantum transport theory for quark-gluon plasmas are introduced. 46 refs

Quark-Gluon Plasma Signatures

CERN Document Server

Vogt, Ramona

1998-01-01

Aspects of quark-gluon plasma signatures that can be measured by CMS are discussed. First the initial conditions of the system from minijet production are introduced, including shadowing effects. Color screening of the Upsilon family is then presented, followed by energy loss effects on charm and bottom hadrons, high Pt jets and global observables.

Experimental properties of gluon and quark jets from a point source

CERN Document Server

Abbiendi, G.; Alexander, G.; Allison, John; Altekamp, N.; Anderson, K.J.; Anderson, S.; Arcelli, S.; Asai, S.; Ashby, S.F.; Axen, D.; Azuelos, G.; Ball, A.H.; Barberio, E.; Barlow, Roger J.; Batley, J.R.; Baumann, S.; Bechtluft, J.; Behnke, T.; Bell, Kenneth Watson; Bella, G.; Bellerive, A.; Bentvelsen, S.; Bethke, S.; Betts, S.; Biebel, O.; Biguzzi, A.; Blobel, V.; Bloodworth, I.J.; Bock, P.; Bohme, J.; Bonacorsi, D.; Boutemeur, M.; Braibant, S.; Bright-Thomas, P.; Brigliadori, L.; Brown, Robert M.; Burckhart, H.J.; Capiluppi, P.; Carnegie, R.K.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Chrisman, D.; Ciocca, C.; Clarke, P.E.L.; Clay, E.; Cohen, I.; Conboy, J.E.; Cooke, O.C.; Couyoumtzelis, C.; Coxe, R.L.; Cuffiani, M.; Dado, S.; Dallavalle, G.Marco; Davis, R.; De Jong, S.; de Roeck, A.; Dervan, P.; Desch, K.; Dienes, B.; Dixit, M.S.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Estabrooks, P.G.; Etzion, E.; Fabbri, F.; Fanfani, A.; Fanti, M.; Faust, A.A.; Fiedler, F.; Fierro, M.; Fleck, I.; Folman, R.; Frey, A.; Furtjes, A.; Futyan, D.I.; Gagnon, P.; Gary, J.W.; Gascon, J.; Gascon-Shotkin, S.M.; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Gibson, V.; Gibson, W.R.; Gingrich, D.M.; Glenzinski, D.; Goldberg, J.; Gorn, W.; Grandi, C.; Graham, K.; Gross, E.; Grunhaus, J.; Gruwe, M.; Hanson, G.G.; Hansroul, M.; Hapke, M.; Harder, K.; Harel, A.; Hargrove, C.K.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Herndon, M.; Herten, G.; Heuer, R.D.; Hildreth, M.D.; Hill, J.C.; Hobson, P.R.; Hoch, M.; Hocker, James Andrew; Hoffman, Kara Dion; Homer, R.J.; Honma, A.K.; Horvath, D.; Hossain, K.R.; Howard, R.; Huntemeyer, P.; Igo-Kemenes, P.; Imrie, D.C.; Ishii, K.; Jacob, F.R.; Jawahery, A.; Jeremie, H.; Jimack, M.; Jones, C.R.; Jovanovic, P.; Junk, T.R.; Kanzaki, J.; Karlen, D.; Kartvelishvili, V.; Kawagoe, K.; Kawamoto, T.; Kayal, P.I.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kim, D.H.; Klier, A.; Kobayashi, T.; Kobel, M.; Kokott, T.P.; Kolrep, M.; Komamiya, S.; Kowalewski, Robert V.; Kress, T.; Krieger, P.; von Krogh, J.; Kuhl, T.; Kyberd, P.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Lauber, J.; Lautenschlager, S.R.; Lawson, I.; Layter, J.G.; Lee, A.M.; Lellouch, D.; Letts, J.; Levinson, L.; Liebisch, R.; List, B.; Littlewood, C.; Lloyd, A.W.; Lloyd, S.L.; Loebinger, F.K.; Long, G.D.; Losty, M.J.; Lu, J.; Ludwig, J.; Lui, D.; Macchiolo, A.; Macpherson, A.; Mader, W.; Mannelli, M.; Marcellini, S.; Markopoulos, C.; Martin, A.J.; Martin, J.P.; Martinez, G.; Mashimo, T.; Mattig, Peter; McDonald, W.John; McKenna, J.; Mckigney, E.A.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Menke, S.; Merritt, F.S.; Mes, H.; Meyer, J.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Mir, R.; Mohr, W.; Montanari, A.; Mori, T.; Nagai, K.; Nakamura, I.; Neal, H.A.; Nisius, R.; O'Neale, S.W.; Oakham, F.G.; Odorici, F.; Ogren, H.O.; Oreglia, M.J.; Orito, S.; Palinkas, J.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Patt, J.; Perez-Ochoa, R.; Petzold, S.; Pfeifenschneider, P.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poffenberger, P.; Poli, B.; Polok, J.; Przybycien, M.; Rembser, C.; Rick, H.; Robertson, S.; Robins, S.A.; Rodning, N.; Roney, J.M.; Rosati, S.; Roscoe, K.; Rossi, A.M.; Rozen, Y.; Runge, K.; Runolfsson, O.; Rust, D.R.; Sachs, K.; Saeki, T.; Sahr, O.; Sang, W.M.; Sarkisian, E.K.G.; Sbarra, C.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schieck, J.; Schmitt, S.; Schoning, A.; Schroder, Matthias; Schumacher, M.; Schwick, C.; Scott, W.G.; Seuster, R.; Shears, T.G.; Shen, B.C.; Shepherd-Themistocleous, C.H.; Sherwood, P.; Siroli, G.P.; Sittler, A.; Skuja, A.; Smith, A.M.; Snow, G.A.; Sobie, R.; Soldner-Rembold, S.; Spagnolo, S.; Sproston, M.; Stahl, A.; Stephens, K.; Steuerer, J.; Stoll, K.; Strom, David M.; Strohmer, R.; Surrow, B.; Talbot, S.D.; Taras, P.; Tarem, S.; Teuscher, R.; Thiergen, M.; Thomas, J.; Thomson, M.A.; Torrence, E.; Towers, S.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turcot, A.S.; Turner-Watson, M.F.; Ueda, I.; Van Kooten, Rick J.; Vannerem, P.; Verzocchi, M.; Voss, H.; Wackerle, F.; Wagner, A.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wermes, N.; White, J.S.; Wilson, G.W.; Wilson, J.A.; Wyatt, T.R.; Yamashita, S.; Yekutieli, G.; Zacek, V.; Zer-Zion, D.

1999-01-01

Gluon jets are identified in hadronic Z0 decays as all the particles in a hemisphere opposite to a hemisphere containing two tagged quark jets. Gluon jets defined in this manner are equivalent to gluon jets produced from a color singlet point source and thus correspond to the definition employed for most theoretical calculations. In a separate stage of the analysis, we select quark jets in a manner to correspond to calculations, as the particles in hemispheres of flavor tagged light quark (uds) events. We present the distributions of rapidity, scaled energy, the logarithm of the momentum, and transverse momentum with respect to the jet axes, for charged particles in these gluon and quark jets. We also examine the charged particle multiplicity distributions of the jets in restricted intervals of rapidity. For soft particles at large transverse momentum, we observe the charged particle multiplicity ratio of gluon to quark jets to be 2.29 +- 0.09 +- 0.15 in agreement with the prediction that this ratio should ap...

Monte Carlo study on the properties of gluon and quark jets

CERN Document Server

Kun Shi Zhang; Mei Ling Yu; Lian Shou Liu

2002-01-01

The 3-jet events produced in e/sup +/e/sup -/ collisions at 91.2 GeV have been studied using Monte Carlo method. After applying two angular cuts the three angles between the jets are used to identify the individual jet in 3-jet events. The energy distributions of the three jets, the mean particle multiplicities, mean transverse momenta of the three jets in equal energy bins and their distributions have been analyzed. Comparing with the corresponding results from the quark jets in 2-jet events, a simple method to select gluon and quark jets from 3-jet events is obtained. The properties of the gluon and quark jets being selected using the introduced method are in qualitative agreement with the expectations of perturbative QCD. The ratio of the mean multiplicity between quark and gluon jets, /sub gluon///sub quark/, has been calculated. The results, again, agree with the experimental results from SLD, OPAL, ALEPH, and DELPHI Collaborations, indicating that the method proposed to select gluon and quark jets from ...

Rapidity evolution of gluon TMD from low to moderate x

International Nuclear Information System (INIS)

Balitsky, I.

2016-01-01

I discuss how the rapidity evolution of gluon transverse momentum dependent distribution (TMD) changes from nonlinear evolution at small x << 1 to linear evolution at moderate x ∼ 1. I have described the rapidity evolution of gluon TMD in the whole range of Bjorken x B and the whole range of transverse momentum. It should be emphasized that with our definition of rapidity cutoff the leading-order matrix elements of TMD operators are UV-finite so the rapidity evolution is the only evolution and it describes all the dynamics of gluon TMDs in the leading-log approximation

Vortex profiles and vortex interactions at the electroweak crossover

OpenAIRE

Chernodub, M. N.; Ilgenfritz, E. -M.; Schiller, A.

1999-01-01

Local correlations of Z-vortex operators with gauge and Higgs fields (lattice quantum vortex profiles) as well as vortex two-point functions are studied in the crossover region near a Higgs mass of 100 GeV within the 3D SU(2) Higgs model. The vortex profiles resemble certain features of the classical vortex solutions in the continuum. The vortex-vortex interactions are analogous to the interactions of Abrikosov vortices in a type-I superconductor.

Multiplicity distributions of gluon and quark jets and tests of QCD analytic predictions

CERN Document Server

Ackerstaff, K; Allison, J; Altekamp, N; Anderson, K J; Anderson, S; Arcelli, S; Asai, S; Axen, D A; Azuelos, Georges; Ball, A H; Barberio, E; Barlow, R J; Bartoldus, R; Batley, J Richard; Baumann, S; Bechtluft, J; Beeston, C; Behnke, T; Bell, A N; Bell, K W; Bella, G; Bentvelsen, Stanislaus Cornelius Maria; Bethke, Siegfried; Biebel, O; Biguzzi, A; Bird, S D; Blobel, Volker; Bloodworth, Ian J; Bloomer, J E; Bobinski, M; Bock, P; Bonacorsi, D; Boutemeur, M; Bouwens, B T; Braibant, S; Brigliadori, L; Brown, R M; Burckhart, Helfried J; Burgard, C; Bürgin, R; Capiluppi, P; Carnegie, R K; Carter, A A; Carter, J R; Chang, C Y; Charlton, D G; Chrisman, D; Clarke, P E L; Cohen, I; Conboy, J E; Cooke, O C; Cuffiani, M; Dado, S; Dallapiccola, C; Dallavalle, G M; Davis, R; De Jong, S; del Pozo, L A; Desch, Klaus; Dienes, B; Dixit, M S; do Couto e Silva, E; Doucet, M; Duchovni, E; Duckeck, G; Duerdoth, I P; Eatough, D; Edwards, J E G; Estabrooks, P G; Evans, H G; Evans, M; Fabbri, Franco Luigi; Fanti, M; Faust, A A; Fiedler, F; Fierro, M; Fischer, H M; Fleck, I; Folman, R; Fong, D G; Foucher, M; Fürtjes, A; Futyan, D I; Gagnon, P; Gary, J W; Gascon, J; Gascon-Shotkin, S M; Geddes, N I; Geich-Gimbel, C; Geralis, T; Giacomelli, G; Giacomelli, P; Giacomelli, R; Gibson, V; Gibson, W R; Gingrich, D M; Glenzinski, D A; Goldberg, J; Goodrick, M J; Gorn, W; Grandi, C; Gross, E; Grunhaus, Jacob; Gruwé, M; Hajdu, C; Hanson, G G; Hansroul, M; Hapke, M; Hargrove, C K; Hart, P A; Hartmann, C; Hauschild, M; Hawkes, C M; Hawkings, R; Hemingway, Richard J; Herndon, M; Herten, G; Heuer, R D; Hildreth, M D; Hill, J C; Hillier, S J; Hobson, P R; Homer, R James; Honma, A K; Horváth, D; Hossain, K R; Howard, R; Hüntemeyer, P; Hutchcroft, D E; Igo-Kemenes, P; Imrie, D C; Ingram, M R; Ishii, K; Jawahery, A; Jeffreys, P W; Jeremie, H; Jimack, Martin Paul; Joly, A; Jones, C R; Jones, G; Jones, M; Jost, U; Jovanovic, P; Junk, T R; Karlen, D A; Kartvelishvili, V G; Kawagoe, K; Kawamoto, T; Kayal, P I; Keeler, Richard K; Kellogg, R G; Kennedy, B W; Kirk, J; Klier, A; Kluth, S; Kobayashi, T; Kobel, M; Koetke, D S; Kokott, T P; Kolrep, M; Komamiya, S; Kress, T; Krieger, P; Von Krogh, J; Kyberd, P; Lafferty, G D; Lahmann, R; Lai, W P; Lanske, D; Lauber, J; Lautenschlager, S R; Layter, J G; Lazic, D; Lee, A M; Lefebvre, E; Lellouch, Daniel; Letts, J; Levinson, L; Lloyd, S L; Loebinger, F K; Long, G D; Losty, Michael J; Ludwig, J; Macchiolo, A; MacPherson, A L; Mannelli, M; Marcellini, S; Markus, C; Martin, A J; Martin, J P; Martínez, G; Mashimo, T; Mättig, P; McDonald, W J; McKenna, J A; McKigney, E A; McMahon, T J; McPherson, R A; Meijers, F; Menke, S; Merritt, F S; Mes, H; Meyer, J; Michelini, Aldo; Mikenberg, G; Miller, D J; Mincer, A; Mir, R; Mohr, W; Montanari, A; Mori, T; Morii, M; Müller, U; Mihara, S; Nagai, K; Nakamura, I; Neal, H A; Nellen, B; Nisius, R; O'Neale, S W; Oakham, F G; Odorici, F; Ögren, H O; Oh, A; Oldershaw, N J; Oreglia, M J; Orito, S; Pálinkás, J; Pásztor, G; Pater, J R; Patrick, G N; Patt, J; Pearce, M J; Pérez-Ochoa, R; Petzold, S; Pfeifenschneider, P; Pilcher, J E; Pinfold, J L; Plane, D E; Poffenberger, P R; Poli, B; Posthaus, A; Rees, D L; Rigby, D; Robertson, S; Robins, S A; Rodning, N L; Roney, J M; Rooke, A M; Ros, E; Rossi, A M; Routenburg, P; Rozen, Y; Runge, K; Runólfsson, O; Ruppel, U; Rust, D R; Rylko, R; Sachs, K; Saeki, T; Sarkisyan-Grinbaum, E; Sbarra, C; Schaile, A D; Schaile, O; Scharf, F; Scharff-Hansen, P; Schenk, P; Schieck, J; Schleper, P; Schmitt, B; Schmitt, S; Schöning, A; Schröder, M; Schultz-Coulon, H C; Schumacher, M; Schwick, C; Scott, W G; Shears, T G; Shen, B C; Shepherd-Themistocleous, C H; Sherwood, P; Siroli, G P; Sittler, A; Skillman, A; Skuja, A; Smith, A M; Snow, G A; Sobie, Randall J; Söldner-Rembold, S; Springer, R W; Sproston, M; Stephens, K; Steuerer, J; Stockhausen, B; Stoll, K; Strom, D; Szymanski, P; Tafirout, R; Talbot, S D; Tanaka, S; Taras, P; Tarem, S; Teuscher, R; Thiergen, M; Thomson, M A; Von Törne, E; Towers, S; Trigger, I; Trócsányi, Z L; Tsur, E; Turcot, A S; Turner-Watson, M F; Utzat, P; Van Kooten, R; Verzocchi, M; Vikas, P; Vokurka, E H; Voss, H; Wäckerle, F; Wagner, A; Ward, C P; Ward, D R; Watkins, P M; Watson, A T; Watson, N K; Wells, P S; Wermes, N; White, J S; Wilkens, B; Wilson, G W; Wilson, J A; Wolf, G; Wyatt, T R; Yamashita, S; Yekutieli, G; Zacek, V; Zer-Zion, D

1999-01-01

Gluon jets are identified in e+e- hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon jets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent of a jet finding algorithm. The charged particle multiplicity distribution of the gluon jets is presented, and is analyzed for its mean, dispersion, skew, and curtosis values, and for its factorial and cumulant moments. The results are compared to the analogous results found for a sample of light quark (uds) jets, also defined inclusively. We observe differences between the mean, skew and curtosis values of gluon and quark jets, but not between their dispersions. The cumulant moment results are compared to the predictions of QCD analytic calculations. A calculation which includes next-to-next-to-leading order corrections and energy conservation is observe...

The PLUTO experiment at DORIS (DESY) and the discovery of the gluon (A recollection)

Energy Technology Data Exchange (ETDEWEB)

Stella, Bruno R. [Rome-3 Univ. (Italy). Dipt. di Fisica; Istituto Nazionale di Fisica Nucleare, Rome (Italy); Meyer, Hans-Juergen

2010-08-15

With the aim of determining the contribution of the PLUTO experiment at the DORIS e{sup +}e{sup -} storage ring to the discovery of the gluon, as members of this former collaboration we have reconsidered all the scientific material produced by PLUTO in 1978 and the first half of 1979. It is clear that the experiment demonstrated the main decay of the Y(9.46 GeV) resonance to be mediated by 3 gluons, by providing evidence for the agreement of this hypothesis with average values and differential distributions of all possible experimental variables and by excluding all other possible alternative models. Moreover PLUTO measured in June 1979 the matrix element of the 3-gluon decay to be quantitatively as expected by QCD (even after hadronization) and, having checked the possibility to correctly trace the gluons' directions, demonstrated the spin 1 nature of the gluon by excluding spin 0 and spin 1/2. The hadronization of the gluon like a quark jet, hypothesized in the 3-gluon jet Monte Carlo simulation, was compatible with the topological data at this energy and was shown to be an approximation at 10% level for the multiplicity ({approx} < p {sub vertical} {sub stroke} {sub vertical} {sub stroke} {sub >}{sup -1}); the right expected gluon fragmentation was needed for the inclusive distributions; this was the first experimental study of (identified) gluon jets. In the following measurements at the PETRA storage ring, these results were confirmed by PLUTO and by three contemporaneous experiments by evidencing at higher energies the gluon radiation (''bremsstrahlung''), the softer one, by jet broadening, and the hard one, by the emission of (now clearly visible) gluon jets by quarks. The gluon's spin 1 particle nature was also confirmed. The PLUTO results on Y decays had been confirmed both by contemporaneous experiments at DORIS (partially) and later (also partially) were confirmed by more sophisticated detectors. (orig.)

A two-loop four-gluon helicity amplitude in QCD

Energy Technology Data Exchange (ETDEWEB)

Dixon, L.

2000-01-06

The authors present the two-loop pure gauge contribution to the gluon-gluon scattering amplitude with maximal helicity violation. The construction of the amplitude does not rely directly on Feynman diagrams, but instead uses its analytic properties 4--2{epsilon} dimensions. The authors evaluate the loop integrals appearing in the amplitude through order({epsilon}{sup 0})in terms of polylogarithms.

Gyrofluid potential vorticity equation and turbulent equipartion states

DEFF Research Database (Denmark)

Madsen, Jens; Juul Rasmussen, Jens; Naulin, Volker

2015-01-01

. The equation is relevant for transport barriers in magnetically confined plasmas because particle density, ion temperature and the radial electric field are mutually coupled through the potential vorticity. The potential vorticity equation is derived from an energy conserving, four-field, electrostatic, full......An equation governing potential vorticity in a magnetized plasmas is derived. The equation is analogous to Ertel's theorem. In the long wave-length limit the potential vorticity equals the ratio of the gyro-frequency plus the E × B- and diamagnetic polarization densities to the particle density...

Flavour equilibration studies of quark-gluon plasma with non-zero ...

Indian Academy of Sciences (India)

Abstract. Flavour equilibration for a thermally equilibrated but chemically non- equilibrated quark-gluon plasma is presented. Flavour equilibration is studied enforcing baryon number conservation. In addition to the usual processes like single additional gluon production gg ⇌ ggg and its reverse and quark–antiquark pair ...

Quark and gluon tagging in dijet mass resonance search

CERN Document Server

Kellermann, Edgar

2013-01-01

Several models beyond the Standard Model predict new phenomena in particle physics, which would appear as resonant signals in dijet mass distributions. An example for such a resonance is the excited quark q, which is a consequence of Compositeness Models postulating that quarks and leptons are build by more fundamental particles. The main signature of an excited quark would be a dijet event, originated from the radiation of a gluon from the original excited quark when going back to its non-excited state, leading to a quark and a gluon in the final state (with a branching ratio of 83%) . Other examples are the heavy vector bosonsW0 decaying to two quarks and colour octet scalar S8 decaying to two gluons.

Analysis of the proton longitudinal structure function from the gluon distribution function

International Nuclear Information System (INIS)

Boroun, G.R.; Rezaei, B.

2012-01-01

We make a critical, next-to-leading order, study of the relationship between the longitudinal structure function F L and the gluon distribution proposed in Cooper-Sarkar et al. (Z. Phys. C 39:281, 1988; Acta Phys. Pol. B 34:2911 2003), which is frequently used to extract the gluon distribution from the proton longitudinal structure function at small x. The gluon density is obtained by expanding at particular choices of the point of expansion and compared with the hard Pomeron behavior for the gluon density. Comparisons with H1 data are made and predictions for the proposed best approach are also provided. (orig.)

One-loop Higgs plus four gluon amplitudes. Full analytic results

International Nuclear Information System (INIS)

Badger, Simon; Nigel Glover, E.W.; Williams, Ciaran; Mastrolia, Pierpaolo

2009-10-01

We consider one-loop amplitudes of a Higgs boson coupled to gluons in the limit of a large top quark mass. We treat the Higgs as the real part of a complex field φ that couples to the self-dual field strengths and compute the one-loop corrections to the φ-NMHV amplitude, which contains one gluon of positive helicity whilst the remaining three have negative helicity. We use four-dimensional unitarity to construct the cut-containing contributions and a hybrid of Feynman diagram and recursive based techniques to determine the rational piece. Knowledge of the φ-NMHV contribution completes the analytic calculation of the Higgs plus four gluon amplitude. For completeness we also include expressions for the remaining helicity configurations which have been calculated elsewhere. These amplitudes are relevant for Higgs plus jet production via gluon fusion in the limit where the top quark is large compared to all other scales in the problem. (orig.)

Quantized vortices in superfluids and superconductors

International Nuclear Information System (INIS)

Thoulessi, D.J.; Wexler, C.; Ping Ao, Ping; Niu, Qian; Geller, M.R.

1998-01-01

We give a general review of recent developments in the theory of vortices in superfluids and superconductors, discussing why the dynamics of vortices is important, and why some key results are still controversial. We discuss work that we have done on the dynamics of quantized vortices in a superfluid. Despite the fact that this problem has been recognized as important for forty years, there is still a lot of controversy about the forces on and masses of quantized vortices. We think that one can get unambiguous answers by considering a broken symmetry state that consists of one vortex in an infinite ideal system. We argue for a Magnus force that is proportional to the superfluid density, and we find that the effective mass density of a vortex in a neutral superfluid is divergent at low frequencies. We have generalized some of the results for a neutral superfluid to a charged system. (Copyright (1998) World Scientific Publishing Co. Pte. Ltd)

The Theory of Vortical Gravitational Fields

Directory of Open Access Journals (Sweden)

Rabounski D.

2007-04-01

Full Text Available This paper treats of vortical gravitational fields, a tensor of which is the rotor of the general covariant gravitational inertial force. The field equations for a vortical gravitational field (the Lorentz condition, the Maxwell-like equations, and the continuity equation are deduced in an analogous fashion to electrodynamics. From the equations it is concluded that the main kind of vortical gravitational fields is “electric”, determined by the non-stationarity of the acting gravitational inertial force. Such a field is a medium for traveling waves of the force (they are different to the weak deformation waves of the space metric considered in the theory of gravitational waves. Standing waves of the gravitational inertial force and their medium, a vortical gravitational field of the “magnetic” kind, are exotic, since a non-stationary rotation of a space body (the source of such a field is a very rare phenomenon in the Universe.

Gluon fragmentation in T(1S) decays

International Nuclear Information System (INIS)

Bienlein, J.K.

1983-05-01

In T(1S) decays most observables (sphericity, charged multiplicity, photonic energy fraction, inclusive spectra) can be understood assuming that gluons fragment like quarks. New results from LENA use the (axis-independent) Fox-Wolfram moments for the photonic energy deposition. Continuum reactions show 'standard' Field-Feynman fragmentation. T(1S) decays show a significant difference in the photonic energy topology. It is more isotropic than with the Field-Feynman fragmentation scheme. Gluon fragmentation into isoscalar mesons (a la Peterson and Walsh) is excluded. But if one forces the leading particle to be isoscalar, one gets good agreement with the data. (orig.)

Polarization in heavy-ion collisions: magnetic field and vorticity

Science.gov (United States)

Baznat, M.; Gudima, K.; Prokhorov, G.; Sorin, A.; Teryaev, O.; Zakharov, V.

2017-12-01

The polarization of hyperons due to axial chiral vortical effect is discussed. The effect is proportional to (strange) chemical potential and is pronounced at lower energies, contrary to that of magnetic field. The polarization of antihyperons has the same sign and larger magnitude. The emergence of vortical structures is observed in kinetic QGSM models. The hydrodynamical helicity separation receives the contribution of longitudinal velocity and vorticity implying the quadrupole structure of the latter. The transition from the quark vortical effects to baryons in confined phase may be achieved by exploring the axial charge. At the hadronic level the polarization corresponds to the cores of quantized vortices in pionic superfluid. The chiral vortical effects may be also studied in the frmework of Wigner function establishing the relation to the thermodynamical approach to polarization.

Dilepton production from quark gluon plasma using non-equilibrium thermodynamics

International Nuclear Information System (INIS)

Sinha, B.

1984-01-01

The importance of the approach phase to the thermodynamic equilibrium has been investigated for dilepton production from quark-gluon plasma - an effective temperature for the quarks as Brounian particle in a heat bath of gluons has been suggested. The spectrum for low invariant mass is, as a consequence, sharper

Gluon condensate from lattice caculations: SU(3) pure gauge theory

International Nuclear Information System (INIS)

Kripfganz, J.

1981-01-01

A short distance expansion of Wilson loops is used to define and isolate vacuum expectation values of composite gluon operators. It is applied to available lattice Monte Carlo data for SU(3) pure gauge theory. The value obtained for the gluon condensate is consistent with the ITEP estimate. (author)

On generating counter-rotating streamwise vortices

KAUST Repository

Winoto, S H

2015-09-23

Counter-rotating streamwise vortices are known to enhance the heat transfer rate from a surface and also to improve the aerodynamic performance of an aerofoil. In this paper, some methods to generate such counter-rotating vortices using different methods or physical conditions will be briefly considered and discussed.

On generating counter-rotating streamwise vortices

KAUST Repository

Winoto, S H; Mitsudharmadi, Hatsari; Budiman, A C; Hasheminejad, S M; Nadesan, T; Tandiono; Low, H T; Lee, T S

2015-01-01

Counter-rotating streamwise vortices are known to enhance the heat transfer rate from a surface and also to improve the aerodynamic performance of an aerofoil. In this paper, some methods to generate such counter-rotating vortices using different methods or physical conditions will be briefly considered and discussed.

Electrohydrodynamic (EHD) vortices in helical turbulence

International Nuclear Information System (INIS)

Kikuchi, H.

1996-01-01

The study of large-scale coherent hydrodynamic (HD) vortex generation has been extended to electrified charged dusty vortices to be termed as electrohydrodynamic (EHD) vortices, incorporating helical turbulence in electric and magnetic fields into that in fluid velocity, which are all created by an external DC electric field on the background. A new equation of EHD vortices is introduced on the basis of a set of EHD or electromagnetohydrodynamic (EMHD) equations, including equations of state and a full set of Maxwell's equations by using functional techniques for estimating equations for an ensemble average, turbulent background, and additional random field. In fact, EHD vortices for a charged dusty fluid can be more explosive with larger instabilities than HD vortices. In addition, it is inferred that an external DC electric field could provide the origin of additional self-organization to a coalescence of fluid vortex and electric field lines as a manifestation of a new frozen-in field concept for electric fields when the electric Reynolds number is sufficiently high. This is discussed on the basis of a set of general transport equations for fluid vorticity, magnetic and electric fields that are rederived concisely. In particular, a novel concept of electric field line merging-reconnection is developed in close relation to fluid vortex line merging, indicating a coalescence of fluid vortex breakdown or merging point and electric field line reconnection point, X-type or O-type with possible application to tornadic thunderstorms. In fact, a thundercloud charge distribution so as to provide a coalescence of fluid vortex and electric field lines is quite possible without theoretical inconsistency, and is thought most likely to occur from observations available so far. (orig.)

A Family of Vortices to Study Axisymmetric Vortex Breakdown and Reconnection

Science.gov (United States)

Young, Larry A.

2007-01-01

A new analytic model describing a family of vortices has been developed to study some of the axisymmetric vortex breakdown and reconnection fluid dynamic processes underlying body-vortex interactions that are frequently manifested in rotorcraft and propeller-driven fixed-wing aircraft wakes. The family of vortices incorporates a wide range of prescribed initial vorticity distributions -- including single or dual-core vorticity distributions. The result is analytical solutions for the vorticity and velocities for each member of the family of vortices. This model is of sufficient generality to further illustrate the dependence of vortex reconnection and breakdown on initial vorticity distribution as was suggested by earlier analytical work. This family of vortices, though laminar in nature, is anticipated to provide valuable insight into the vortical evolution of large-scale rotor and propeller wakes.

Multiplicity distributions of gluon and quark jets and tests of QCD analytic predictions

Science.gov (United States)

OPAL Collaboration; Ackerstaff, K.; et al.

Gluon jets are identified in e+e^- hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon jets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent of a jet finding algorithm. The charged particle multiplicity distribution of the gluon jets is presented, and is analyzed for its mean, dispersion, skew, and curtosis values, and for its factorial and cumulant moments. The results are compared to the analogous results found for a sample of light quark (uds) jets, also defined inclusively. We observe differences between the mean, skew and curtosis values of gluon and quark jets, but not between their dispersions. The cumulant moment results are compared to the predictions of QCD analytic calculations. A calculation which includes next-to-next-to-leading order corrections and energy conservation is observed to provide a much improved description of the data compared to a next-to-leading order calculation without energy conservation. There is agreement between the data and calculations for the ratios of the cumulant moments between gluon and quark jets.

Controlled Manipulation of Individual Vortices in a Superconductor

Energy Technology Data Exchange (ETDEWEB)

Straver, E.W.J.

2010-04-05

We report controlled local manipulation of single vortices by low temperature magnetic force microscope (MFM) in a thin film of superconducting Nb. We are able to position the vortices in arbitrary configurations and to measure the distribution of local depinning forces. This technique opens up new possibilities for the characterization and use of vortices in superconductors.

The hard gluon component of the QCD Pomeron

International Nuclear Information System (INIS)

White, A.R.

1996-01-01

The authors argue that deep-inelastic diffractive scaling provides fundamental insight into the QCD Pomeron. The logarithmic scaling violations seen experimentally are in conflict with the scale-invariance of the BFKL Pomeron and with phenomenological two-gluon models. Instead the Pomeron appears as a single gluon at short-distances, indicating the appearance of a Super-Critical phase of Reggeon Field Theory. That the color compensation takes place at a longer distance is consistent with the Pomeron carrying odd color charge parity

Nielsen's identity and gluon condensation at finite temperature

International Nuclear Information System (INIS)

Skalozub, V.V.

1992-11-01

The gauge dependence problem of the gluon field zero component condensate, A 0 =const, is investigated in finite temperature SU(3) gluodynamics. The two-loop effective action W(A 0 ,ξ) is recalculated in the background R ξ gauge. The obtained result somewhat differs from that of other authors. By straightforward calculation it is shown that W(A 0 ,ξ) satisfies the Nielsen (the Ward type) identity. Thus, the gauge invariance of the gluon condensation phenomenon is proved. (author). 14 refs

On the motion of multiple helical vortices

Science.gov (United States)

Wood, D. H.; Boersma, J.

2001-11-01

The analysis of the self-induced velocity of a single helical vortex (Boersma & Wood 1999) is extended to include equally spaced multiple vortices. This arrangement approximates the tip vortices in the far wake of multi-bladed wind turbines, propellers, or rotors in ascending, descending, or hovering flight. The problem is reduced to finding, from the Biot Savart law, the additional velocity of a helix due to an identical helix displaced azimuthally. The resulting Biot Savart integral is further reduced to a Mellin Barnes integral representation which allows the asymptotic expansions to be determined for small and for large pitch. The Biot Savart integral is also evaluated numerically for a total of two, three and four vortices over a range of pitch values. The previous finding that the self-induced velocity at small pitch is dominated by a term inversely proportional to the pitch carries over to multiple vortices. It is shown that a far wake dominated by helical tip vortices is consistent with the one-dimensional representation that leads to the Betz limit on the power output of wind turbines. The small-pitch approximation then allows the determination of the blade&s bound vorticity for optimum power extraction. The present analysis is shown to give reasonable estimates for the vortex circulation in experiments using a single hovering rotor and a four-bladed propeller.

Vortices and vortex lattices in quantum ferrofluids

International Nuclear Information System (INIS)

Martin, A M; Marchant, N G; Parker, N G; O’Dell, D H J

2017-01-01

The experimental realization of quantum-degenerate Bose gases made of atoms with sizeable magnetic dipole moments has created a new type of fluid, known as a quantum ferrofluid, which combines the extraordinary properties of superfluidity and ferrofluidity. A hallmark of superfluids is that they are constrained to rotate through vortices with quantized circulation. In quantum ferrofluids the long-range dipolar interactions add new ingredients by inducing magnetostriction and instabilities, and also affect the structural properties of vortices and vortex lattices. Here we give a review of the theory of vortices in dipolar Bose–Einstein condensates, exploring the interplay of magnetism with vorticity and contrasting this with the established behaviour in non-dipolar condensates. We cover single vortex solutions, including structure, energy and stability, vortex pairs, including interactions and dynamics, and also vortex lattices. Our discussion is founded on the mean-field theory provided by the dipolar Gross–Pitaevskii equation, ranging from analytic treatments based on the Thomas–Fermi (hydrodynamic) and variational approaches to full numerical simulations. Routes for generating vortices in dipolar condensates are discussed, with particular attention paid to rotating condensates, where surface instabilities drive the nucleation of vortices, and lead to the emergence of rich and varied vortex lattice structures. We also present an outlook, including potential extensions to degenerate Fermi gases, quantum Hall physics, toroidal systems and the Berezinskii–Kosterlitz–Thouless transition. (topical review)

Vortices and vortex lattices in quantum ferrofluids

Science.gov (United States)

Martin, A. M.; Marchant, N. G.; O'Dell, D. H. J.; Parker, N. G.

2017-03-01

The experimental realization of quantum-degenerate Bose gases made of atoms with sizeable magnetic dipole moments has created a new type of fluid, known as a quantum ferrofluid, which combines the extraordinary properties of superfluidity and ferrofluidity. A hallmark of superfluids is that they are constrained to rotate through vortices with quantized circulation. In quantum ferrofluids the long-range dipolar interactions add new ingredients by inducing magnetostriction and instabilities, and also affect the structural properties of vortices and vortex lattices. Here we give a review of the theory of vortices in dipolar Bose-Einstein condensates, exploring the interplay of magnetism with vorticity and contrasting this with the established behaviour in non-dipolar condensates. We cover single vortex solutions, including structure, energy and stability, vortex pairs, including interactions and dynamics, and also vortex lattices. Our discussion is founded on the mean-field theory provided by the dipolar Gross-Pitaevskii equation, ranging from analytic treatments based on the Thomas-Fermi (hydrodynamic) and variational approaches to full numerical simulations. Routes for generating vortices in dipolar condensates are discussed, with particular attention paid to rotating condensates, where surface instabilities drive the nucleation of vortices, and lead to the emergence of rich and varied vortex lattice structures. We also present an outlook, including potential extensions to degenerate Fermi gases, quantum Hall physics, toroidal systems and the Berezinskii-Kosterlitz-Thouless transition.

Tunneling decay of self-gravitating vortices

Directory of Open Access Journals (Sweden)

Dupuis Éric

2018-01-01

Full Text Available We investigate tunneling decay of false vortices in the presence of gravity, in which vortices are trapped in the false vacuum of a theory of scalar electrodynamics in three dimensions. The core of the vortex contains magnetic flux in the true vacuum, while outside the vortex is the appropriate topologically nontrivial false vacuum. We numerically obtain vortex solutions which are classically stable; however, they could decay via tunneling. To show this phenomenon, we construct the proper junction conditions in curved spacetime. We find that the tunneling exponent for the vortices is half that for Coleman-de Luccia bubbles and discuss possible future applications.

Probing sea quarks and gluons: the electron-ion collider project

International Nuclear Information System (INIS)

Horn, T.

2014-01-01

A future Electron-Ion Collider (EIC) would be the world's first polarized electron-proton collider, and the world's first e-A collider, and would seek the QCD foundation of nucleons and nuclei in terms of the sea quarks and gluons, matching to these valence quark studies. The EIC will provide a versatile range of kinematics and beam polarization, as well as beam species, to allow for mapping the spin and spatial structure of the quark sea and gluons, to discover the collective effects of gluons in atomic nuclei, and to understand the emergence of hadronic matter from color charge. (authors)

Fragmentation of quarks and gluons

International Nuclear Information System (INIS)

Soeding, P.

1983-10-01

The author presents a review about quark and gluon jets. He describes the particle contents of the different types of jets. Finally he considers the hadronization mechanism with special regards to three-jet events in e + e - annihilation and hadronization in nuclear matter. (HSI)

Quark versus Gluon Jet Tagging Using Jet Images with the ATLAS Detector

CERN Document Server

The ATLAS collaboration

2017-01-01

Distinguishing quark-initiated from gluon-initiated jets is useful for many measurements and searches at the LHC. This note presents a jet tagger for distinguishing quark-initiated from gluon-initiated jets, which uses the full radiation pattern inside a jet processed as an image in a deep neural network classifier. The study is conducted using simulated dijet events in $\\sqrt{s}$=13 TeV pp collisions with the ATLAS detector. Across a wide range of quark jet identification efficiencies, the neural network tagger achieves a gluon jet rejection that is comparable to or better than the performance of the jet width and track multiplicity observables conventionally used for quark-versus-gluon jet tagging.

Bogoliubov condensation of gluons and spontaneous gauge symmetry breaking in QCD

International Nuclear Information System (INIS)

Pervushin, V.N.; Roepke, G.; Volkov, M.K.; Blaschke, D.; Pavel, H.P.; Litvin, A.

1995-08-01

The ''squeezed'' representation of commutation relations for gluon fields in QCD is formulated as the mathematical tool for the description of the gluon condensate. We first consider λφ 4 theory and show that the ''squeezed'' Bogoliubov condensate can lead to the spontaneous appearance of a mass. Using the ''squeezed'' representation, we show that in the non-Abelian theory spontaneous gauge symmetry breaking (SGSB) and the appearance of a constituent mass of gluons can be described. We construct a projector onto the oscillator - like variables, for which the ''squeezed'' representation is valid, by using the formal solution of the Gauss equation instead of fixing a gauge. We discuss the effects of the SGSB and present as an application of the approach the calculation of the gluon mass from the difference of the η' and the η - meson masses. (author). 27 refs

Quark-gluon plasma 2

CERN Document Server

1995-01-01

This is a sequel to the review volume Quark-Gluon Plasma. There are 13 articles contributed by leading investigators in the field, covering a wide range of topics about the theoretical approach to the subject. These contributions are timely reviews of nearly all the actively pursued problems, written in a pedagogical style suitable for beginners as well as experienced researchers.

Muoproduction of J/ψ and the gluon distribution of the nucleon

International Nuclear Information System (INIS)

Ashman, J.; Combley, F.; Salmon, D.; Wheeler, S.; Bee, C.P.; Brown, S.C.; Court, G.; Francis, D.; Gabathuler, E.; Gamet, R.; Hayman, P.; Holt, J.R.; Jones, T.; Matthews, M.; Wimpenny, S.J.; Coignet, G.; Toth, J.; Urban, L.; Drees, J.; Edwards, A.W.; Hamacher, K.; Korzen, B.; Kruener, U.; Moenig, K.; Pavel, N.; Peschel, H.; Nassalski, J.; Sandacz, A.; Windmolders, R.; Ernst, T.; Landgraf, U.; Schroeder, T.; Stier, H.E.; Stock, J.; Wallucks, W.

1992-01-01

Measurements are presented of the inclusive distributions of the J/ψ meson produced by muons of energy 200 GeV from an ammonia target. The gluon distribution of the nucleon has been derived from the data in the range 0.04< x<0.36 using a technique based on the colour singlet model. An arbitrary normalisation factor is required to obtain a reasonable integral of the gluon distribution. Some comments are made on the use of J/ψ production by virtual photons to extract the gluon distribution at HERA. (orig.)

Low-energy behavior of gluons and gravitons from gauge invariance

DEFF Research Database (Denmark)

di Vecchia, Paolo; Bern, Zvi; Davies, Scott

2014-01-01

We show that at tree level, on-shell gauge invariance can be used to fully determine the first subleading soft-gluon behavior and the first two subleading soft-graviton behaviors. Our proofs of the behaviors for n-gluon and n-graviton tree amplitudes are valid in D dimensions and are similar to Low...

Topological vortices in gauge models of graphene

Science.gov (United States)

Zhang, Xin-Hui; Li, Xueqin; Hao, Jin-Bo

2018-06-01

Graphene-like structure possessing the topological vortices and knots, and the magnetic flux of the vortices configuration quantized, are proposed in this paper. The topological charges of the vortices are characterized by Hopf indices and Brower degrees. The Abelian background field action (BF action) is a topological invariant for the knot family, which is just the total sum of all the self-linking numbers and all the linking numbers. Flux quantization opens the possibility of having Aharonov-Bohm-type effects in graphene without external electromagnetic field.

Streamwise vortices destabilize swimming bluegill sunfish (Lepomis macrochirus).

Science.gov (United States)

Maia, Anabela; Sheltzer, Alex P; Tytell, Eric D

2015-03-01

In their natural environment, fish must swim stably through unsteady flows and vortices, including vertical vortices, typically shed by posts in a flow, horizontal cross-flow vortices, often produced by a step or a waterfall in a stream, and streamwise vortices, where the axis of rotation is aligned with the direction of the flow. Streamwise vortices are commonly shed by bluff bodies in streams and by ships' propellers and axial turbines, but we know little about their effects on fish. Here, we describe how bluegill sunfish use more energy and are destabilized more often in flow with strong streamwise vorticity. The vortices were created inside a sealed flow tank by an array of four turbines with similar diameter to the experimental fish. We measured oxygen consumption for seven sunfish swimming at 1.5 body lengths (BL) s(-1) with the turbines rotating at 2 Hz and with the turbines off (control). Simultaneously, we filmed the fish ventrally and recorded the fraction of time spent maneuvering side-to-side and accelerating forward. Separately, we also recorded lateral and ventral video for a combination of swimming speeds (0.5, 1.5 and 2.5 BL s(-1)) and turbine speeds (0, 1, 2 and 3 Hz), immediately after turning the turbines on and 10 min later to test for accommodation. Bluegill sunfish are negatively affected by streamwise vorticity. Spills (loss of heading), maneuvers and accelerations were more frequent when the turbines were on than in the control treatment. These unsteady behaviors, particularly acceleration, correlated with an increase in oxygen consumption in the vortex flow. Bluegill sunfish are generally fast to recover from roll perturbations and do so by moving their pectoral fins. The frequency of spills decreased after the turbines had run for 10 min, but was still markedly higher than in the control, showing that fish partially adapt to streamwise vorticity, but not completely. Coping with streamwise vorticity may be an important energetic

Two-gluon emission and interference in a thin QCD medium: insights into jet formation

International Nuclear Information System (INIS)

Casalderrey-Solana, Jorge; Pablos, Daniel; Tywoniuk, Konrad

2016-01-01

In heavy-ion collisions, an abundant production of high-energy QCD jets allows to study how these multiparticle sprays are modified as they pass through the quark-gluon plasma. In order to shed new light on this process, we compute the inclusive two-gluon rate off a hard quark propagating through a color deconfined medium at first order in medium opacity. We explicitly impose an energy ordering of the two emitted gluons, such that the “hard” gluon can be thought of as belonging to the jet substructure while the other is a “soft” emission (which can be collinear or medium-induced). Our analysis focusses on two specific limits that clarify the modification of the additional angle- and formation time-ordering of splittings. In one limit, the formation time of the “hard” gluon is short compared to the “soft” gluon formation time, leading to a probabilistic formula for production of and subsequent radiation off a quark-gluon antenna. In the other limit, the ordering of formation is reverted, which automatically leads to the fact that the jet substructure is resolved by the medium. We observe in this case a characteristic delay: the jet radiates as one color current (quark) up to the formation of the “hard” gluon, at which point we observe the onset of radiation of the new color current (gluon). Within our kinematic constraints, our computation supports a picture in which the in-medium jet dynamics are described as a collection of subsequent antennas which are resolved by the medium according to their transverse extent.

Self-consistent one-gluon exchange in soliton bag models

International Nuclear Information System (INIS)

Dodd, L.R.; Adelaide Univ.; Williams, A.G.

1988-01-01

The treatment of soliton bag models as two-point boundary value problems is extended to include self-consistent one-gluon exchange interactions. The colour-magnetic contribution to the nucleon-delta mass splitting is calculated self-consistently in the mean-field, one-gluon-exchange approximation for the Friedberg-Lee and Nielsen-Patkos models. Small glueball mass parameters (m GB ∝ 500 MeV) are favoured. Comparisons with previous calculations are made. (orig.)

Phenomenological Evidence for Gluon Depletion in pA Collisions

OpenAIRE

Hwa, R. C.; Pisut, J.; Pisutova, N.

2000-01-01

The data of J/psi suppression at large x_F in pA collisions are used to infer the existence of gluon depletion as the projectile proton traverses the nucleus. The modification of the gluon distribution is studied by use of a convolution equation whose non-perturbative splitting function is determined phenomenologically. The depletion factor at x_1=0.8 is found to be about 25% at A=100.

Quark Loop Effects on Dressed Gluon Propagator in Framework of Global Color Symmetry Model

Institute of Scientific and Technical Information of China (English)

ZONG Hong-Shi; SUN Wei-Min

2006-01-01

Based on the global color symmetry model (GCM), a method for obtaining the quark loop effects on the dressed gluon propagator in GCM is developed. In the chiral limit, it is found that the dressed gluon propagator containing the quark loop effects in the Nambu-Goldstone and Wigner phases are quite different. In solving the quark self-energy functions in the two different phases and subsequent study of bag constant one should use the above dressed gluon propagator as input. The above approach for obtaining the current quark mass effects on the dressed gluon propagator is quite general and can also be used to calculate the chemical potential dependence of the dressed gluon propagator.

Experimental Observations of Ion Phase-Space Vortices

DEFF Research Database (Denmark)

Pécseli, Hans; Armstrong, R. J.; Trulsen, J.

1981-01-01

Experimental observations of ion phase-space vortices are reported. The ion phase-space vortices form in the region of heated ions behind electrostatic ion acoustic shocks. The results are in qualitative agreement with numerical and analytic studies....

Vorticity imbalance and stability in relation to convection

Science.gov (United States)

Read, W. L.; Scoggins, J. R.

1977-01-01

A complete synoptic-scale vorticity budget was related to convection storm development in the eastern two-thirds of the United States. The 3-h sounding interval permitted a study of time changes of the vorticity budget in areas of convective storms. Results of analyses revealed significant changes in values of terms in the vorticity equation at different stages of squall line development. Average budgets for all areas of convection indicate systematic imbalance in the terms in the vorticity equation. This imbalance resulted primarily from sub-grid scale processes. Potential instability in the lower troposphere was analyzed in relation to the development of convective activity. Instability was related to areas of convection; however, instability alone was inadequate for forecast purposes. Combinations of stability and terms in the vorticity equation in the form of indices succeeded in depicting areas of convection better than any one item separately.

Multiplicity distributions of gluon and quark jets and a test of QCD analytic calculations

International Nuclear Information System (INIS)

Gary, J. William

1999-01-01

Gluon jets are identified in e + e - hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon jets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent of a jet finding algorithm. The mean and first few higher moments of the gluon jet charged particle multiplicity distribution are compared to the analogous results found for light quark (uds) jets, also defined inclusively. Large differences are observed between the mean, skew and curtosis values of the gluon and quark jets, but not between their dispersions. The cumulant factorial moments of the distributions are also measured, and are used to test the predictions of QCD analytic calculations. A calculation which includes next-to-next-to-leading order corrections and energy conservation is observed to provide a much improved description of the separated gluon and quark jet cumulant moments compared to a next-to-leading order calculation without energy conservation. There is good quantitative agreement between the data and calculations for the ratios of the cumulant moments between gluon and quark jets. The data sample used is the LEP-1 sample of the OPAL experiment at LEP

Multiplicity distributions of gluon and quark jets and a test of QCD analytic calculations

Energy Technology Data Exchange (ETDEWEB)

Gary, J. William

1999-03-01

Gluon jets are identified in e{sup +}e{sup -} hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon jets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent of a jet finding algorithm. The mean and first few higher moments of the gluon jet charged particle multiplicity distribution are compared to the analogous results found for light quark (uds) jets, also defined inclusively. Large differences are observed between the mean, skew and curtosis values of the gluon and quark jets, but not between their dispersions. The cumulant factorial moments of the distributions are also measured, and are used to test the predictions of QCD analytic calculations. A calculation which includes next-to-next-to-leading order corrections and energy conservation is observed to provide a much improved description of the separated gluon and quark jet cumulant moments compared to a next-to-leading order calculation without energy conservation. There is good quantitative agreement between the data and calculations for the ratios of the cumulant moments between gluon and quark jets. The data sample used is the LEP-1 sample of the OPAL experiment at LEP.

Multiplicity distributions of gluon and quark jets and a test of QCD analytic calculations

Energy Technology Data Exchange (ETDEWEB)

Gary, J.W. [California Univ., Riverside, CA (United States). Dept. of Physics

1999-03-01

Gluon jets are identified in e{sup +}e{sup -} hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon jets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent of a jet finding algorithm. The mean and first few higher moments of the gluon jet charged particle multiplicity distribution are compared to the analogous results found for light quark (uds) jets, also defined inclusively. Large differences are observed between the mean, skew and curtosis values of the gluon and quark jets, but not between their dispersions. The cumulant factorial moments of the distributions are also measured, and are used to test the predictions of QCD analytic calculations. A calculation which includes next-to-next-to-leading order corrections and energy conservation is observed to provide a much improved description of the separated gluon and quark jet cumulant moments compared to a next-to-leading order calculation without energy conservation. There is good quantitative agreement between the data and calculations for the ratios of the cumulant moments between gluon and quark jets. The data sample used is the LEP-1 sample of the OPAL experiment at LEP. (orig.) 6 refs.

Multiplicity distributions of gluon and quark jets and a test of QCD analytic calculations

International Nuclear Information System (INIS)

Gary, J.W.

1999-01-01

Gluon jets are identified in e + e - hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon jets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent of a jet finding algorithm. The mean and first few higher moments of the gluon jet charged particle multiplicity distribution are compared to the analogous results found for light quark (uds) jets, also defined inclusively. Large differences are observed between the mean, skew and curtosis values of the gluon and quark jets, but not between their dispersions. The cumulant factorial moments of the distributions are also measured, and are used to test the predictions of QCD analytic calculations. A calculation which includes next-to-next-to-leading order corrections and energy conservation is observed to provide a much improved description of the separated gluon and quark jet cumulant moments compared to a next-to-leading order calculation without energy conservation. There is good quantitative agreement between the data and calculations for the ratios of the cumulant moments between gluon and quark jets. The data sample used is the LEP-1 sample of the OPAL experiment at LEP. (orig.)

Multiplicity distributions of gluon and quark jets and a test of QCD analytic calculations

Science.gov (United States)

Gary, J. William

1999-03-01

Gluon jets are identified in e +e - hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon hets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent of a jet finding algorithm. The mean and first few higher moments of the gluon jet charged particle multiplicity distribution are compared to the analogous results found for light quark (uds) jets, also defined inclusively. Large differences are observed between the mean, skew and curtosis values of the gluon and quark jets, but not between their dispersions. The cumulant factorial moments of the distributions are also measured, and are used to test the predictions of QCD analytic calculations. A calculation which includes next-to-next-to-leading order corrections and energy conservation is observed to provide a much improved description of the separated gluon and quark jet cumulant moments compared to a next-to-leading order calculation without energy conservation. There is good quantitative agreement between the data and calculations for the ratios of the cumulant moments between gluon and quark jets. The data sample used is the LEP-1 sample of the OPAL experiment at LEP.

Bose–Einstein condensation and thermalization of the quark–gluon plasma

International Nuclear Information System (INIS)

Blaizot, Jean-Paul; Gelis, François; Liao, Jinfeng; McLerran, Larry; Venugopalan, Raju

2012-01-01

In ultra-relativistic heavy ion collisions, the matter formed shortly after the collision is a dense, out of equilibrium, system of gluons characterized by a semi-hard momentum scale Q s . Simple power counting arguments indicate that this system is over-occupied: the gluon occupation number is parametrically large when compared to a system in thermal equilibrium with the same energy density. On short time scales, soft elastic scattering tends to drive the system toward the formation of a Bose–Einstein condensate that contains a large fraction of the gluons while contributing little to the energy density. The lifetime and existence of this condensate depends on whether inelastic processes, that occur on the same time scale as elastic processes, preferably increase or decrease the number of gluons. During this overpopulated stage, and all the way to thermalization, the system behaves as a strongly interacting fluid, even though the elementary coupling constant is small. Finally, we argue that while complete isotropization may never be reached, the system may yet evolve for a long time with a fixed anisotropy between average longitudinal and transverse momenta.

Eleven lectures on the physics of the quark-gluon plasma

International Nuclear Information System (INIS)

McLerran, L.

1984-10-01

These lectures are intended to be an introduction to the physics of the quark-gluon plasma, and were presented at a workshop on The Physics of the Quark-Gluon Plasma held at Hua-Zhong Normal University in Wuhan, People's Republic of China in September, 1983. The lectures cover perturbation theory of the plasma at high temperature as well as the non-perturbative methods and results of lattice gauge theory computations. Physical models of the confinement-deconfinement phase transition and the modes of chiral symmetry breaking are presented. The possibility that a quark-gluon plasma might be produced in ultra-relativistic nuclear collisions is analyzed. Separate entries were prepared for the data base for the eleven lectures

Interaction of vortices with flexible piezoelectric beams

Science.gov (United States)

Goushcha, Oleg; Akaydin, Huseyin Dogus; Elvin, Niell; Andreopoulos, Yiannis

2012-11-01

A cantilever piezoelectric beam immersed in a flow is used to harvest fluidic energy. Pressure distribution induced by naturally present vortices in a turbulent fluid flow can force the beam to oscillate producing electrical output. Maximizing the power output of such an electromechanical fluidic system is a challenge. In order to understand the behavior of the beam in a fluid flow where vortices of different scales are present, an experimental facility was set up to study the interaction of individual vortices with the beam. In our set up, vortex rings produced by an audio speaker travel at specific distances from the beam or impinge on it, with a frequency varied up to the natural frequency of the beam. Depending on this frequency both constructive and destructive interactions between the vortices and the beam are observed. Vortices traveling over the beam with a frequency multiple of the natural frequency of the beam cause the beam to resonate and larger deflection amplitudes are observed compared to excitation from a single vortex. PIV is used to compute the flow field and circulation of each vortex and estimate the effect of pressure distribution on the beam deflection. Sponsored by NSF Grant: CBET #1033117.

Dynamics of Chern-Simons vortices

International Nuclear Information System (INIS)

Collie, Benjamin; Tong, David

2008-01-01

We study vortex dynamics in three-dimensional theories with Chern-Simons interactions. The dynamics is governed by motion on the moduli space M in the presence of a magnetic field. For Abelian vortices, the magnetic field is shown to be the Ricci form over M; for non-Abelian vortices, it is the first Chern character of a suitable index bundle. We derive these results by integrating out massive fermions and following the fate of their zero modes.

Stability of two-dimensional vorticity filaments

International Nuclear Information System (INIS)

Elhmaidi, D.; Provenzale, A.; Lili, T.; Babiano, A.

2004-01-01

We discuss the results of a numerical study on the stability of two-dimensional vorticity filaments around a circular vortex. We illustrate how the stability of the filaments depends on the balance between the strain associated with the far field of the vortex and the local vorticity of the filament, and we discuss an empirical criterion for filament stability

Why does gravitational radiation produce vorticity?

International Nuclear Information System (INIS)

Herrera, L; Barreto, W; Carot, J; Prisco, A Di

2007-01-01

We calculate the vorticity of worldlines of observers at rest in a Bondi-Sachs frame, produced by gravitational radiation, in a general Sachs metric. We claim that such an effect is related to the super-Poynting vector, in a similar way as the existence of the electromagnetic Poynting vector is related to the vorticity in stationary electrovacuum spacetimes

Stability of relative equilibria of three vortices

DEFF Research Database (Denmark)

Aref, Hassan

2009-01-01

Three point vortices on the unbounded plane have relative equilibria wherein the vortices either form an equilateral triangle or are collinear. While the stability analysis of the equilateral triangle configurations is straightforward, that of the collinear relative equilibria is considerably mor...

Gluon structure function for deeply inelastic scattering with nucleus in QCD

Energy Technology Data Exchange (ETDEWEB)

Ayala Filho, Alvaro L; Ducati, M.B. Gay [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Fisica; Levin, Eugene [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); [Petersburg Nuclear Physics Institute, Gatchina (Russian Federation). Theory Dept.

1995-06-01

In this talk we present the first calculation of the gluon structure function for nucleus in QCD. We discuss the Glauber formula for the gluon structure function and the violation of this simple approach that we anticipate in QCD. (author). 10 refs, 4 figs.

Strangeness Production in a Chemically Equilibrating Quark-Gluon Plasma

Institute of Scientific and Technical Information of China (English)

HE Ze-Jun; LONG Jia-Li; MA Yu-Gang; MA Guo-Liang

2004-01-01

@@ We study the strangeness of a chemically equilibrating quark-gluon plasma at finite baryon density based on the and will accelerate with the change of the initial system from a chemically non-equilibrated to an equilibrated system. We also find that the calculated strangeness is very different from the one in the thermodynamic equilibrium system. This study may be helpful to understand the formation of quark-gluon plasma via a chemically non-equilibrated evolution framework.

Regularization of the light-cone gauge gluon propagator singularities using sub-gauge conditions

Energy Technology Data Exchange (ETDEWEB)

Chirilli, Giovanni A.; Kovchegov, Yuri V.; Wertepny, Douglas E. [Department of Physics, The Ohio State University,191 W Woodruff Ave, Columbus, OH 43210 (United States)

2015-12-21

Perturbative QCD calculations in the light-cone gauge have long suffered from the ambiguity associated with the regularization of the poles in the gluon propagator. In this work we study sub-gauge conditions within the light-cone gauge corresponding to several known ways of regulating the gluon propagator. Using the functional integral calculation of the gluon propagator, we rederive the known sub-gauge conditions for the θ-function gauges and identify the sub-gauge condition for the principal value (PV) regularization of the gluon propagator’s light-cone poles. The obtained sub-gauge condition for the PV case is further verified by a sample calculation of the classical Yang-Mills field of two collinear ultrarelativistic point color charges. Our method does not allow one to construct a sub-gauge condition corresponding to the well-known Mandelstam-Leibbrandt prescription for regulating the gluon propagator poles.

First measurement of the Sivers asymmetry for gluons using SIDIS data

Directory of Open Access Journals (Sweden)

C. Adolph

2017-09-01

Full Text Available The Sivers function describes the correlation between the transverse spin of a nucleon and the transverse motion of its partons. For quarks, it was studied in previous measurements of the azimuthal asymmetry of hadrons produced in semi-inclusive deep inelastic scattering of leptons off transversely polarised nucleon targets, and it was found to be non-zero. In this letter the evaluation of the Sivers asymmetry for gluons is presented. The contribution of the photon–gluon fusion subprocess is enhanced by requiring two high transverse-momentum hadrons. The analysis method is based on a Monte Carlo simulation that includes three hard processes: photon–gluon fusion, QCD Compton scattering and the leading-order virtual-photon absorption process. The Sivers asymmetries of the three processes are simultaneously extracted using the LEPTO event generator and a neural network approach. The method is applied to samples of events containing at least two hadrons with large transverse momentum from the COMPASS data taken with a 160 GeV/c muon beam scattered off transversely polarised deuterons and protons. With a significance of about two standard deviations, a negative value is obtained for the gluon Sivers asymmetry. The result of a similar analysis for a Collins-like asymmetry for gluons is consistent with zero.

Collision dynamics of two-dimensional non-Abelian vortices

Science.gov (United States)

Mawson, Thomas; Petersen, Timothy C.; Simula, Tapio

2017-09-01

We study computationally the collision dynamics of vortices in a two-dimensional spin-2 Bose-Einstein condensate. In contrast to Abelian vortex pairs, which annihilate or pass through each other, we observe non-Abelian vortex pairs to undergo rungihilation—an event that converts the colliding vortices into a rung vortex. The resulting rung defect subsequently decays to another pair of non-Abelian vortices of different type, accompanied by a magnetization reversal.

Looking at the gluon moment of the nucleon with dynamical twisted mass fermions

International Nuclear Information System (INIS)

Alexandrou, Constantia; Cyprus Institute, Nicosia; Drach, Vincent; Wiese, Christian; Hadjiyiannakou, Kyriakos; Jansen, Karl; Deutsches Elektronen-Synchrotron; Kostrzewa, Bartosz

2013-11-01

To understand the structure of hadrons it is important to know the PDF of their constituents, the quarks and gluons. In our work we aim to compute the first moment of the gluon PDF left angle x right angle g for the nucleon. We follow two possible approaches in order to extract the gluon moment: the Feynman-Hellmann theorem and a direct method with smearing of the gluon operator. We present preliminary results computed on 24 3 x 48 lattices for the case where the Feynman-Hellman theorem is used and 32 3 x 64 lattices for the direct method, employing N f =2+1+1 maximally twisted mass fermions.

Why superconducting vortices follow to moving hot sport?

Science.gov (United States)

Sergeev, Andrei; Michael, Reizer

Recent experiments reported in Nature Comm. 7, 12801, 2016 show that superconducting vortices follow to the moving hot sport created by a focused laser beam, i.e. vortices move from the cold area to the moving hot area. This behavior is opposite to the vortex motion observed in numerous measurements of the vortex Nernst effect, where vortices always move against the temperature gradient. Taking into account that superconducting magnetization currents do not transfer entropy, we analyze the balance of forces acting on a vortex in stationary and dynamic temperature gradients. We show that the dynamic measurements may be described by a single vortex approximation, while in stationary measurements interaction between vortices is critical. Supported by NRC.

On trailing vortices: A short review

International Nuclear Information System (INIS)

Jacquin, Laurent

2005-01-01

This paper reviews some mechanisms involved in the dynamics of vortices in fluid flows. The topic is first introduced by pointing out its importance in aerodynamics. Several basic notions useful to appraise experimental observations are then surveyed, namely: centrifugal instabilities, inertial waves, cooperative instabilities, vortex merger, vortex breakdown and turbulence in vortices. Each topic is illustrated with experimental or numerical results

Airfoil Drag Reduction using Controlled Trapped Vorticity Concentrations

Science.gov (United States)

Desalvo, Michael; Glezer, Ari

2017-11-01

The aerodynamic performance of a lifting surface at low angles of attack (when the base flow is fully attached) is improved through fluidic modification of its ``apparent'' shape by superposition of near-surface trapped vorticity concentrations. In the present wind tunnel investigations, a controlled trapped vorticity concentration is formed on the pressure surface of an airfoil (NACA 4415) using a hybrid actuator comprising a passive obstruction of scale O(0.01c) and an integral synthetic jet actuator. The jet actuation frequency [Stact O(10)] is selected to be at least an order of magnitude higher than the characteristic unstable frequency of the airfoil wake, thereby decoupling the actuation from the global instabilities of the base flow. Regulation of vorticity accumulation in the vicinity of the actuator by the jet effects changes in the local pressure, leading in turn to changes in the airfoil's drag and lift. Trapped vorticity can lead to a significant reduction in drag and reduced lift (owing to the sense of the vorticity), e.g. at α =4° and Re = 6.7 .105 the drag and lift reductions are 14% and 2%, respectively. PIV measurements show the spatial variation in the distribution of vorticity concentrations and yield estimates of the corresponding changes in circulation.

Quark and gluon fragmentation in high energy e+e- annihilation

International Nuclear Information System (INIS)

Saxon, D.H.

1986-07-01

The paper on quark and gluon fragmentation in high energy e + e - annihilation is based on lectures given at the International School of High Energy Physics, Yugoslavia, 1986. Fragmentation Models, charged particle multiplicity, Bose-Einstein correlations, single particle inclusive distributions, hadrons in jets, leading particle effects, baryon production, comparison of quark and gluon jets, and the string effect, are all discussed. (UK)

Experimental study of rapidity gaps in gluon jets

CERN Document Server

Gary, J W

2003-01-01

Gluon jets are selected from hadronic Z/sup 0/ decay events produced in e/sup +/e/sup -/ annihilations, collected with the OPAL detector at LEP. A subsample of these jets is identified which exhibit a large gap in the rapidity distribution of particles within the jet. These jets are observed to demonstrate a high degree of sensitivity to the presence of color reconnection, i.e. higher order QCD processes affecting the underlying color structure. We test two QCD Monte Carlo programs which implement color reconnection: one in the Ariadne Monte Carlo and the other by Rathsman in the Pythia Monte Carlo. We find these models can describe our gluon jet measurements only if very large values are used for the cutoff parameters which serve to terminate the parton showers, and conclude that color reconnection as implemented in these models is disfavored. Further, we use our data on gluon jets with a rapidity gap to search for glueball-like objects in the leading part of those jets. We do not find any clear evidence for...

Thick vortices in SU(2) lattice gauge theory

OpenAIRE

Cheluvaraja, Srinath

2004-01-01

Three dimensional SU(2) lattice gauge theory is studied after eliminating thin monopoles and the smallest thick monopoles. Kinematically this constraint allows the formation of thick vortex loops which produce Z(2) fluctuations at longer length scales. The thick vortex loops are identified in a three dimensional simulation. A condensate of thick vortices persists even after the thin vortices have all disappeared. The thick vortices decouple at a slightly lower temperature (higher beta) than t...

Initial conditions of non-equilibrium quark-gluon plasma evolution

International Nuclear Information System (INIS)

Shmatov, S.V.

2002-01-01

In accordance with the hydrodynamic Bjorken limit, the initial energy density and temperature for a chemical non-equilibrium quark-gluon system formed in the heavy ion collisions at the LHC are computed. The dependence of this value on the type of colliding nuclei and the collision impact parameter is studied. The principle possibility of the non-equilibrium quark-gluon plasma (QGP) formation in the light nuclei collisions is shown. The life time of QGP is calculated. (author)

Transport quasiparticles and transverse interactions in quark-gluon plasmas

International Nuclear Information System (INIS)

Baym, Gordon

1996-01-01

Calculations of the properties of interacting quark-gluon plasmas are beset by infrared divergences associated with the fact that magnetic interactions, i.e., those occurring through exchange of transverse gluons, are, in the absence of a 'magnetic mass''in QCD, not screened. In this lecture we discuss the effects of magnetic interactions on the transport coefficients and the quasiparticle structure of quark-gluon plasmas. We describe how inclusion of dynamical screening effects - corresponding to Landau damping of the virtual quanta exchanged - leads to finite transport scattering rates. In the weak coupling limit, dynamical screening effects dominate over a magnetic mass. We illustrate the breakdown of the quasi particle structure of degenerate plasmas caused by long-ranged magnetic interactions, describe the structure of fermion quasiparticles in hot relativistic plasmas, and touch briefly on the problem of the lifetime of quasiparticle in the presence of long-ranged magnetic interactions. (author)

Low-momentum ghost dressing function and the gluon mass

International Nuclear Information System (INIS)

Boucaud, Ph.; Leroy, J. P.; Le Yaouanc, A.; Micheli, J.; Pene, O.; Gomez, M. E.; Rodriguez-Quintero, J.

2010-01-01

We study the low-momentum ghost propagator Dyson-Schwinger equation in the Landau gauge, assuming for the truncation a constant ghost-gluon vertex, as it is extensively done, and a simple model for a massive gluon propagator. Then, regular Dyson-Schwinger equation solutions (the zero-momentum ghost dressing function not diverging) appear to emerge, and we show the ghost propagator to be described by an asymptotic expression reliable up to the order O(q 2 ). That expression, depending on the gluon mass and the zero-momentum Taylor-scheme effective charge, is proven to fit pretty well some low-momentum ghost propagator data [I. L. Bogolubsky, E. M. Ilgenfritz, M. Muller-Preussker, and A. Sternbeck, Phys. Lett. B 676, 69 (2009); Proc. Sci., LAT2007 (2007) 290] from big-volume lattice simulations where the so-called ''simulated annealing algorithm'' is applied to fix the Landau gauge.

Transitions between Taylor vortices and spirals via wavy Taylor vortices and wavy spirals

International Nuclear Information System (INIS)

Hoffmann, Ch; Altmeyer, S; Pinter, A; Luecke, M

2009-01-01

We present numerical simulations of closed wavy Taylor vortices and of helicoidal wavy spirals in the Taylor-Couette system. These wavy structures appearing via a secondary bifurcation out of Taylor vortex flow and out of spiral vortex flow, respectively, mediate transitions between Taylor and spiral vortices and vice versa. Structure, dynamics, stability and bifurcation behaviour are investigated in quantitative detail as a function of Reynolds numbers and wave numbers for counter-rotating as well as corotating cylinders. These results are obtained by solving the Navier-Stokes equations subject to axial periodicity for a radius ratio η=0.5 with a combination of a finite differences method and a Galerkin method.

An introduction to quark-gluon plasma and high energy heavy ion collisions

International Nuclear Information System (INIS)

McLerran, L.

1987-01-01

The quark-gluon plasma, and how it might be produced in ultra-relativistic nuclear collisions is reviewed. I briefly introduce the quark-gluon plasma, and what we might learn from studying it. I then discuss what has been learned from the recent results from the CERN oxygen run. I then attempt to address the issue of whether A = 16 and E = 200 GeV are sufficient to make a quark-gluon plasma. I discuss strangeness and charm production as well as electromagnetic probes of the plasma

Numerical estimates of the evolution of quark and gluon populations inside QCD jets

International Nuclear Information System (INIS)

Garetto, M.

1980-01-01

The system of first order differential equations for the probabilities of producing nsub(g) gluons and nsub(q) quarks in a single gluon or quark jet are solved numerically for a convenient choice of the parameters A, A-tilde, B. Relevant branching ratios as the evolution parameter Y increases are shown. The different behaviour of the distributions in the quark- and in the gluon-jet is discussed. (author)

Dynamical properties of vortical structures on the beta-plane

DEFF Research Database (Denmark)

Sutyrin, G.G.; Hesthaven, J.S.; Lynov, Jens-Peter

1994-01-01

The long-time evolution of monopolar and dipolar vortices influenced by the large-scale gradient of the ambient potential vorticity (the beta-effect) is studied by direct numerical solutions of the equivalent barotropic quasi-geostrophic equation. Translation and reorganization of vortical...... structures are shown to depend strongly on their intensity. Transport of trapped fluid by vortical structures is illustrated by calculating particle trajectories and by considering closed isolines of potential vorticity and the streamfunction in a co-moving reference frame. The initial behaviour of strong...... monopoles is found to be well described by a recent approximate theory for the evolution of azimuthal mode one, even for times longer than the linear Rossby wave period. In the long-time limit, strong monopoles transport particles mainly westward, although the meridional displacement is several times larger...

Experimental properties of gluon and quark jets from a point source

International Nuclear Information System (INIS)

Abbiendi, G.; Ackerstaff, K.; Alexander, G.

1999-01-01

Gluon jets are identified in hadronic Z 0 decays as all the particles in a hemisphere opposite to a hemisphere containing two tagged quark jets. Gluon jets defined in this manner are equivalent to gluon jets produced from a color singlet point source and thus correspond to the definition employed for most theoretical calculations. In a separate stage of the analysis, we select quark jets in a manner to correspond to calculations, as the particles in hemispheres of flavor tagged light quark (uds) events. We present the distributions of rapidity, scaled energy, the logarithm of the momentum, and transverse momentum with respect to the jet axes, for charged particles in these gluon and quark jets. We also examine the charged particle multiplicity distributions of the jets in restricted intervals of rapidity. For soft particles at large p T , we observe the charged particle multiplicity ratio of gluon to quark jets to be 2.29±0.09(stat.)±0.15(syst.), in agreement with the prediction that this ratio should approximately equal the ratio of QCD color factors, C A /C F =2.25. The intervals used to define soft particles and large p T for this result, p T < 3.0 GeV/c, are motivated by the predictions of the Herwig Monte Carlo multihadronic event generator. Additionally, our gluon jet data allow a sensitive test of the phenomenon of non-leading QCD terms known as color reconnection. We test the model of color reconnection implemented in the Ariadne Monte Carlo multihadronic event generator and find it to be disfavored by our data. (orig.)

Gluon condensation and modelling of quark confinement in QCD-motivated Nambu-Jona-Lasinio model

International Nuclear Information System (INIS)

Bel'kov, A.A.; Ebert, D.; Emel'yanenko, A.V.

1992-01-01

The possibility of modelling of a quark propagator without poles realizing quark confinement is considered on the basis of a nonperturbative gluon propagator including gluon condensation and a dynamical gluon mass. The property of spontaneous chiral symmetry breaking is retained providing us with a reasonable pattern of low-lying meson properties. 2 figs.; 1 tab

Observation of Polarization Vortices in Momentum Space

Science.gov (United States)

Zhang, Yiwen; Chen, Ang; Liu, Wenzhe; Hsu, Chia Wei; Wang, Bo; Guan, Fang; Liu, Xiaohan; Shi, Lei; Lu, Ling; Zi, Jian

2018-05-01

The vortex, a fundamental topological excitation featuring the in-plane winding of a vector field, is important in various areas such as fluid dynamics, liquid crystals, and superconductors. Although commonly existing in nature, vortices were observed exclusively in real space. Here, we experimentally observed momentum-space vortices as the winding of far-field polarization vectors in the first Brillouin zone of periodic plasmonic structures. Using homemade polarization-resolved momentum-space imaging spectroscopy, we mapped out the dispersion, lifetime, and polarization of all radiative states at the visible wavelengths. The momentum-space vortices were experimentally identified by their winding patterns in the polarization-resolved isofrequency contours and their diverging radiative quality factors. Such polarization vortices can exist robustly on any periodic systems of vectorial fields, while they are not captured by the existing topological band theory developed for scalar fields. Our work provides a new way for designing high-Q plasmonic resonances, generating vector beams, and studying topological photonics in the momentum space.

Certain exclusive processes in QCD taking into account two-gluon states

International Nuclear Information System (INIS)

Baier, V.N.; Grozin, A.G.

1982-01-01

The wave functions and evolution equations for mesons are classified completely taking into account two-gluon states and then are compared to the Altarelli-Parisi evolution equations. The form factors of completely neutral mesons and the probabilities for exclusive decays of quarkonium states are found taking into account two-gluon states

Mechanism of J/PSI production: determining gluon distributions

International Nuclear Information System (INIS)

Nandi, S.; Schneider, H.R.

1978-01-01

Assuming a generalised Drell-Yan type mechanism for hadronic PSI-production, the relative importance of the different possible contributions is estimated from the data. We find that about 80% of the pp → PSI X cross-section is due to gluons. Therefore, these data give some information on the gluon distribution G(x) in the proton. Assuming xG(x) approximately (1-x)sup(n), data restrict n to 4... 6, in agreement with dimensional counting rules. The energy dependence of sigma(anti p p → PSI X)/sigma(pp → PSIX) is predicted. (orig.) [de

Gluon gas viscosity in nonperturbative region

International Nuclear Information System (INIS)

Il'in, S.V.; Mogilevskij, O.A.; Smolyanskij, S.A.; Zinov'ev, G.M.

1992-01-01

Using the Green-Kubo-type formulae and the cutoff model motivated by Monte Carlo lattice gluodynamics simulations we find the temperature behaviour of shear viscosity of gluon gas in the region of deconfinement phase transition. 22 refs.; 1 fig. (author)

Grain boundary transport properties in YBa{sub 2}Cu{sub 3}O{sub x} coated conductors.

Energy Technology Data Exchange (ETDEWEB)

Berghuis, P.; Miller, D. J.; Kim, D. H.; Gray, K. E.; Feenstra, R.; Christen, D. K.

2000-11-02

Critical current data obtained as a function of magnetic field on an isolated grain boundary (GB) of a coated conductor and two other types of bicrystal GBs of YBa{sub 2}Cu{sub 3}O{sub x} show a peak in the critical current and an unusual hysteresis. These results provide support for a new mechanism for enhanced GB critical currents, arising from interactions of GB vortices with pinned Abrikosov vortices in the banks of a GB, as suggested by Gurevich and Cooley. A substantial fraction of this enhancement, which can exceed a factor of ten, also occurs upon surpassing the critical current of the grains after zero field cooling. A bulk GB and thin film GBs show qualitatively identical results.

Plaquette expectation value and gluon condensate in three dimensions

CERN Document Server

Hietanen, A; Laine, Mikko; Rummukainen, K; Schröder, Y

2005-01-01

In three dimensions, the gluon condensate of pure SU(3) gauge theory has ultraviolet divergences up to 4-loop level only. By subtracting the corresponding terms from lattice measurements of the plaquette expectation value and extrapolating to the continuum limit, we extract the finite part of the gluon condensate in lattice regularization. Through a change of regularization scheme to MSbar and (inverse) dimensional reduction, this result would determine the first non-perturbative coefficient in the weak-coupling expansion of hot QCD pressure.

Gluon chains and multiquark hadrons

International Nuclear Information System (INIS)

Jadach, S.; Jezabek, M.

1979-01-01

A monopole approximation to the confining potential is proposed. In this approximation spatially separated groups of quarks carry a definite total colour charge. The potentials which lead to the formation of gluon chains are discussed. The generalization of a (3,3bar) chain notion, studied by Tiktopoulos, to the case of arbitrary colour charges is given. It is argued that these generalized chains may be unstable with respect to splitting into a system of weakly interacting chains of the (3,3bar) type. A unified picture of the high energy hadronic collisions, based on the gluon chain notion and the monopole approximation is proposed. In the meson-meson sector this picture is equivalent to the topological approach. For the other processes it is similar to the approach of Rossi and Veneziano. However, it is argued that the introduction of the junction line into the quark frame is superfluous. The results are expressed in the language of the coloured dual diagrams which provide a generalization of those of Harari and Rosner. (author)

Non-perturbative inputs for gluon distributions in the hadrons

International Nuclear Information System (INIS)

Ermolaev, B.I.; Troyan, S.I.

2017-01-01

Description of hadronic reactions at high energies is conventionally done in the framework of QCD factorization. All factorization convolutions comprise non-perturbative inputs mimicking non-perturbative contributions and perturbative evolution of those inputs. We construct inputs for the gluon-hadron scattering amplitudes in the forward kinematics and, using the optical theorem, convert them into inputs for gluon distributions in the hadrons, embracing the cases of polarized and unpolarized hadrons. In the first place, we formulate mathematical criteria which any model for the inputs should obey and then suggest a model satisfying those criteria. This model is based on a simple reasoning: after emitting an active parton off the hadron, the remaining set of spectators becomes unstable and therefore it can be described through factors of the resonance type, so we call it the resonance model. We use it to obtain non-perturbative inputs for gluon distributions in unpolarized and polarized hadrons for all available types of QCD factorization: basic, K_T-and collinear factorizations. (orig.)

Soft probes of the quark gluon plasma in ATLAS

CERN Document Server

Wozniak, K W; The ATLAS collaboration

2014-01-01

Measurements of low-$p_{T}$ (< 5 GeV) particle production have provided valuable insight on the production and evolution of the quark-gluon plasma in Pb+Pb collisions at the LHC. In particular, measurements of elliptic and higher order collective flow imprinted on the azimuthal angle distributions of low-$p_{T}$ particles directly probe the strongly-coupled dynamics of the quark gluon plasma and test hydrodynamic model descriptions of its evolution. The large acceptance of detectors like ATLAS have made it possible to measure flow event-by-event and to determine the correlations between different harmonics. Recent measurements of low-$p_{T}$ particle production and multi-particle correlations in proton-lead collisions have shown features similar to the collective flow observed in Pb+Pb collisions. Results will be presented from a variety of single and multi-particle measurements in Pb+Pb and proton-Pb collisions that probe the collective dynamics of the quark gluon plasma and possibly provide evidence for ...

Non-perturbative inputs for gluon distributions in the hadrons

Energy Technology Data Exchange (ETDEWEB)

Ermolaev, B.I. [Ioffe Physico-Technical Institute, Saint Petersburg (Russian Federation); Troyan, S.I. [St. Petersburg Institute of Nuclear Physics, Gatchina (Russian Federation)

2017-03-15

Description of hadronic reactions at high energies is conventionally done in the framework of QCD factorization. All factorization convolutions comprise non-perturbative inputs mimicking non-perturbative contributions and perturbative evolution of those inputs. We construct inputs for the gluon-hadron scattering amplitudes in the forward kinematics and, using the optical theorem, convert them into inputs for gluon distributions in the hadrons, embracing the cases of polarized and unpolarized hadrons. In the first place, we formulate mathematical criteria which any model for the inputs should obey and then suggest a model satisfying those criteria. This model is based on a simple reasoning: after emitting an active parton off the hadron, the remaining set of spectators becomes unstable and therefore it can be described through factors of the resonance type, so we call it the resonance model. We use it to obtain non-perturbative inputs for gluon distributions in unpolarized and polarized hadrons for all available types of QCD factorization: basic, K{sub T}-and collinear factorizations. (orig.)

Correlations between Abelian monopoles and center vortices

Energy Technology Data Exchange (ETDEWEB)

Hosseini Nejad, Seyed Mohsen, E-mail: smhosseininejad@ut.ac.ir; Deldar, Sedigheh, E-mail: sdeldar@ut.ac.ir

2017-04-15

We study the correlations between center vortices and Abelian monopoles for SU(3) gauge group. Combining fractional fluxes of monopoles, center vortex fluxes are constructed in the thick center vortex model. Calculating the potentials induced by fractional fluxes constructing the center vortex flux in a thick center vortex-like model and comparing with the potential induced by center vortices, we observe an attraction between fractional fluxes of monopoles constructing the center vortex flux. We conclude that the center vortex flux is stable, as expected. In addition, we show that adding a contribution of the monopole-antimonopole pairs in the potentials induced by center vortices ruins the Casimir scaling at intermediate regime.

Doppler Velocity Signatures of Idealized Elliptical Vortices

Directory of Open Access Journals (Sweden)

Wen-Chau Lee

2006-01-01

Full Text Available Doppler radar observations have revealed a class of atmospheric vortices (tropical cyclones, tornadoes, dust devils that possess elliptical radar reflectivity signatures. One famous example is Typhoon Herb (1996 that maintained its elliptical reflectivity structure over a 40-hour period. Theoretical work and dual-Doppler analyses of observed tropical cyclones have suggested two physical mechanisms that can explain the formation of two types of elliptical vortices observed in nature, namely, the combination of a circular vortex with either a wavenumber two vortex Rossby wave or a deformation field. The characteristics of these two types of elliptical vortices and their corresponding Doppler velocity signatures have not been previously examined.

Phenomenology of gluon TMDs at NNLL

NARCIS (Netherlands)

Garcia, M.

2015-01-01

All the leading-Twist (un)polarized gluon transverse momentum dependent parton distribution functions have the same evolution, once they are properly defined in order to cancel spurious rapidity divergences. Currently known perturbative ingredients can be used to resum large logarithms up to

Recursive Neural Networks in Quark/Gluon Tagging

CERN Multimedia

CERN. Geneva

2018-01-01

Vidyo contribution Based on the natural tree-like structure of jet sequential clustering, the recursive neural networks (RecNNs) embed jet clustering history recursively as in natural language processing. We explore the performance of RecNN in quark/gluon discrimination. The results show that RecNNs work better than the baseline BDT by a few percent in gluon rejection at the working point of 50\\% quark acceptance. We also experimented on some relevant aspects which might influence the performance of networks. It shows that even only particle flow identification as input feature without any extra information on momentum or angular position is already giving a fairly good result, which indicates that most of the information for q/g discrimination is already included in the tree-structure itself.

Quarks and gluons in hadrons and nuclei

International Nuclear Information System (INIS)

Close, F.E.

1989-12-01

These lectures discuss the particle-nuclear interface -- a general introduction to the ideas and application of colored quarks in nuclear physics, color, the Pauli principle, and spin flavor correlations -- this lecture shows how the magnetic moments of hadrons relate to the underlying color degree of freedom, and the proton's spin -- a quark model perspective. This lecture reviews recent excitement which has led some to claim that in deep inelastic polarized lepton scattering very little of the spin of a polarized proton is due to its quarks. This lecture discusses the distribution functions of quarks and gluons in nucleons and nuclei, and how knowledge of these is necessary before some quark-gluon plasma searches can be analyzed. 56 refs., 2 figs

Statistical balance of vorticity and a new scale for vortical structures in turbulence

International Nuclear Information System (INIS)

Novikov, E.A.

1993-01-01

The balance of one-point and two-point statistical characterics of vorticity, is considered on the basis of the Navier-Stokes equations. It is shown that within the inertial range of scales (L Re -3/4 much-lt r much-lt L, L external scale, Re Reynolds number) there is a physically distinguished scale l s ∼L Re -3/10 . The balance of vortical correlations with scales r≥l s is directly affected by the large-scale motion. l s is a natural length scale for the ''vortex strings,'' observed experimentally and numerically in three-dimensional turbulent flows. The twist of vortex lines in the internal structure of vortex strings is also briefly discussed

Study of high-transverse momentum quark and gluon jet fragmentation

International Nuclear Information System (INIS)

Ghez, P.

1986-09-01

The fragmentation properties of high-transverse momentum jets are investigated using new data from the ISR and the SPS collider. Effects from gluon radiation are clearly demonstrated by comparison with a state-of-the-art model including QCD parton cascade evolution and string hadronization, which gives in general good agreement with the data. Differences between quark and gluon jets are discussed as well as Q 2 -dependent scaling violation effects

Determination of the gluon polarisation from open charm production at COMPASS

CERN Document Server

Koblitz, Susanne

2009-01-01

One of the main goals of the COMPASS experiment at CERN is the determination of the gluon polarisation in the nucleon. It is determined from spin asymmetries in the scattering of 160 GeV/c polarised muons on a polarised LiD target. The gluon polarisation is accessed by the selection of photon-gluon fusion (PGF) events. The PGF-process can be tagged through hadrons with high transverse momenta or through charmed hadrons in the final state. The advantage of the open charm channel is that, in leading order, the PGF-process is the only process for charm production, thus no physical background contributes to the selected data sample. This thesis presents a measurement of the gluon polarisation from the COMPASS data taken in the years 2002-2004. In the analysis, charm production is tagged through a reconstructed D0-meson decaying in $D^{0}-> K^{-}pi^{+}$ (and charge conjugates). The reconstruction is done on a combinatorial basis. The background of wrong track pairs is reduced using kinematic cuts to the reconstruc...

'' Ideal Gas '' gluon plasma with medium dependent dispersion relation

International Nuclear Information System (INIS)

Gorenstein, M.I.

1995-01-01

An '' ideal gas '' model with temperature dependent particle mass is constructed for the gluon plasma equation of state. This simple model gives us an example of a system with temperature dependent effective Hamiltonian. To satisfy thermodynamical relations in these systems, standard statistical mechanics formulas have to be supplemented by special requirements which are considered in details. A self-consistent '' ideal gas '' formulation is used to describe Monte Carlo lattice data for the thermodynamical functions of SU(2) and SU(3) gluon plasma. 14 refs., 8 figs

Plaquette expectation value and gluon condensate in three dimensions

International Nuclear Information System (INIS)

Hietanen, Ari; Kajantie, Keijo; Schroeder, York; Laine, Mikko; Rummukainen, Kari

2005-01-01

In three dimensions, the gluon condensate of pure SU(3) gauge theory has ultraviolet divergences up to 4-loop level only. By subtracting the corresponding terms from lattice measurements of the plaquette expectation value and extrapolating to the continuum limit, we extract the finite part of the gluon condensate in lattice regularization. Through a change of regularization scheme to MS-bar and (inverse) dimensional reduction, this result would determine the first non-perturbative coefficient in the weak-coupling expansion of hot QCD pressure. (author)

The quark and gluon condensates in the Nambu-Jona-Lasinio model

International Nuclear Information System (INIS)

Ebert, D.; Volkov, M.K.

1991-10-01

Systematic study of the role of the nonperturbative gluon condensate arising in a QCD motivated NJL model is presented. The effects of the gluon condensate on meson coupling constants, the pion decay constant, quark condensate and mass formulae are investigated. An interesting result is the decrease of the scale Λ of chiral symmetry breaking. (author). 21 refs

A solution of the DGLAP equation for gluon at low x

Indian Academy of Sciences (India)

Using (43) we will estimate the logarithmic slope of the structure function from the proposed gluon distribution at several points of expansion and compare with data [19] at. Q2 =20 GeV2 where the data on the slope are available. 3. Results and discussion. In the present paper, we have obtained a new description of gluon ...

J/ψ-production mechanisms and determination of the gluon density at HERA

International Nuclear Information System (INIS)

Jung, H.; Schuler, G.A.; Terron, J.

1992-02-01

We discuss photo- and leptoproduction of J/ψ-mesons at energies ranging from fixed-target experiments up to HERA. Elastic and diffractive production as well as various inelastic processes are studied. We investigate the range in which J/ψ-production is described by photon-gluon fusion in the colour-singlet model. We show how inelastic J/ψ production at HERA can be used to extract the gluon density. We estimate an accessible range of 3 x 10 -4 < x < 0.1 and discuss sources of errors in the reconstruction of the gluon density at HERA. (orig.)

Aerodynamics and vortical structures in hovering fruitflies

Science.gov (United States)

Meng, Xue Guang; Sun, Mao

2015-03-01

We measure the wing kinematics and morphological parameters of seven freely hovering fruitflies and numerically compute the flows of the flapping wings. The computed mean lift approximately equals to the measured weight and the mean horizontal force is approximately zero, validating the computational model. Because of the very small relative velocity of the wing, the mean lift coefficient required to support the weight is rather large, around 1.8, and the Reynolds number of the wing is low, around 100. How such a large lift is produced at such a low Reynolds number is explained by combining the wing motion data, the computed vortical structures, and the theory of vorticity dynamics. It has been shown that two unsteady mechanisms are responsible for the high lift. One is referred as to "fast pitching-up rotation": at the start of an up- or downstroke when the wing has very small speed, it fast pitches down to a small angle of attack, and then, when its speed is higher, it fast pitches up to the angle it normally uses. When the wing pitches up while moving forward, large vorticity is produced and sheds at the trailing edge, and vorticity of opposite sign is produced near the leading edge and on the upper surface, resulting in a large time rate of change of the first moment of vorticity (or fluid impulse), hence a large aerodynamic force. The other is the well known "delayed stall" mechanism: in the mid-portion of the up- or downstroke the wing moves at large angle of attack (about 45 deg) and the leading-edge-vortex (LEV) moves with the wing; thus, the vortex ring, formed by the LEV, the tip vortices, and the starting vortex, expands in size continuously, producing a large time rate of change of fluid impulse or a large aerodynamic force.

Gluon and ghost propagator studies in lattice QCD at finite temperature

International Nuclear Information System (INIS)

Aouane, Rafik

2013-01-01

Gluon and ghost propagators in quantum chromodynamics (QCD) computed in the infrared momentum region play an important role to understand quark and gluon confinement. They are the subject of intensive research thanks to non-perturbative methods based on Dyson-Schwinger (DS) and functional renormalization group (FRG) equations. Moreover, their temperature behavior might also help to explore the chiral and deconfinement phase transition or crossover within QCD at non-zero temperature. Our prime tool is the lattice discretized QCD (LQCD) providing a unique ab-initio non-perturbative approach to deal with the computation of various observables of the hadronic world. We investigate the temperature dependence of Landau gauge gluon and ghost propagators in pure gluodynamics and in full QCD. Regarding the gluon propagator, we compute its longitudinal D L as well its transversal D T components. The aim is to provide a data set in terms of fitting formulae which can be used as input for DS (or FRG) equations. We deal with full (N f =2) LQCD with the twisted mass fermion discretization. We employ gauge field configurations provided by the tmfT collaboration for temperatures in the crossover region and for three fixed pion mass values in the range [300,500] MeV. Finally, within SU(3) pure gauge theory (at T=0) we compute the Landau gauge gluon propagator according to different gauge fixing criteria. Our goal is to understand the influence of gauge copies with minimal (non-trivial) eigenvalues of the Faddeev-Popov operator.

Charmed quark production as a gluon probe

International Nuclear Information System (INIS)

Phillips, R.J.N.

1980-09-01

The lowest-order QCD mechanisms for producing cc or other heavy quarks depend on the gluon distributions in hadrons; hence the latter can be extracted directly from experiment. Recent results are described. (author)

A numerical study of vorticity-enhanced heat transfer

Science.gov (United States)

Wang, Xiaolin; Alben, Silas

2012-11-01

The Glezer lab at Georgia Tech has found that vorticity produced by vibrated reeds can improve heat transfer in electronic hardware. Vortices enhance forced convection by boundary layer separation and thermal mixing in the bulk flow. In this work, we simulate the heat transfer process in a 3-dimensional plate-fin heat sink. We propose a simplified model by considering flow and temperature in a 2-D channel, and extend the model to the third dimension using a 1-D heat fin model. We simulate periodically steady-state solutions. We determine how the global Nusselt number is increased, depending on the vortices' strengths and spacings, in the parameter space of Reynolds and Peclet numbers. We find a surprising spatial oscillation of the local Nusselt number due to the vortices. Support from NSF-DMS grant 1022619 is acknowledged.

Gluon structure function of a color dipole in the light-cone limit of lattice QCD

International Nuclear Information System (INIS)

Gruenewald, D.; Ilgenfritz, E.-M.; Pirner, H. J.

2009-01-01

We calculate the gluon structure function of a color dipole in near-light-cone SU(2) lattice QCD as a function of x B . The quark and antiquark are external nondynamical degrees of freedom which act as sources of the gluon string configuration defining the dipole. We compute the color dipole matrix element of transversal chromo-electric and chromo-magnetic field operators separated along a direction close to the light cone, the Fourier transform of which is the gluon structure function. As vacuum state in the pure glue sector, we use a variational ground state of the near-light-cone Hamiltonian. We derive a recursion relation for the gluon structure function on the lattice similar to the perturbative Dokshitzer-Gribov-Lipatov-Altarelli-Parisi equation. It depends on the number of transversal links assembling the Schwinger string of the dipole. Fixing the mean momentum fraction of the gluons to the 'experimental value' in a proton, we compare our gluon structure function for a dipole state with four links with the next-to-leading-order MRST 2002 and the CTEQ AB-0 parametrizations at Q 2 =1.5 GeV 2 . Within the systematic uncertainty we find rather good agreement. We also discuss the low x B behavior of the gluon structure function in our model calculation.

Point vortex description of drift wave vortices: Dynamics and transport

International Nuclear Information System (INIS)

Kono, M.; Horton, W.

1991-05-01

Point-vortex description for drift wave vortices is formulated based on the Hasegawa-Mima equation to study elementary processes for the interactions of vortices as well as statistical properties like vortex diffusion. Dynamical properties of drift wave vortices known by numerical experiments are recovered. Furthermore a vortex diffusion model discussed by Horton based on numerical simulations is shown to be analytically obtained. A variety of phenomena arising from the short-range nature of the interaction force of point vortices are suggested. 12 refs., 10 figs

Calculation of parton fragmentation functions from jet calculus: gluon applications

International Nuclear Information System (INIS)

Lassila, K.E.; Ng, A.

1985-01-01

A method is presented for calculation of general parton fragmentation functions based on jet calculus plus meson and baryon wave functions. Results for gluon fragmentation into mesons and baryons are discussed and related to recent information on upsilon decay into gluons. The expressions derived can be used directly in e + e - cross section predictions and will need to be folded in with baryon parton distribution functions when used in p-barp collisions. (author)

Quark-gluon plasma (Selected Topics)

International Nuclear Information System (INIS)

Zakharov, V. I.

2012-01-01

Introductory lectures to the theory of (strongly interacting) quark-gluon plasma given at the Winter School of Physics of ITEP (Moscow, February 2010). We emphasize theoretical issues highlighted by the discovery of the low viscosity of the plasma. The topics include relativistic hydrodynamics, manifestations of chiral anomaly in hydrodynamics, superfluidity, relativistic superfluid hydrodynamics, effective stringy scalars, holographic models of Yang-Mills theories.

Gluon transport equation with effective mass and dynamical onset of Bose–Einstein condensation

International Nuclear Information System (INIS)

Blaizot, Jean-Paul; Jiang, Yin; Liao, Jinfeng

2016-01-01

We study the transport equation describing a dense system of gluons, in the small scattering angle approximation, taking into account medium-generated effective masses of the gluons. We focus on the case of overpopulated systems that are driven to Bose–Einstein condensation on their way to thermalization. The presence of a mass modifies the dispersion relation of the gluon, as compared to the massless case, but it is shown that this does not change qualitatively the scaling behavior in the vicinity of the onset.

A solution of the DGLAP equation for gluon at low x

Indian Academy of Sciences (India)

We obtain a solution of the DGLAP equation for the gluon at low first by expanding the gluon in a Taylor series and then using the method of characteristics. We test its validity by comparing it with that of Glück, Reya and Vogt. The convergence criteria of the approximation used are also discussed. We also calculate ...

Dynamics of quantised vortices in superfluids

CERN Document Server

Sonin, Edouard B

2016-01-01

A comprehensive overview of the basic principles of vortex dynamics in superfluids, this book addresses the problems of vortex dynamics in all three superfluids available in laboratories (4He, 3He, and BEC of cold atoms) alongside discussions of the elasticity of vortices, forces on vortices, and vortex mass. Beginning with a summary of classical hydrodynamics, the book guides the reader through examinations of vortex dynamics from large scales to the microscopic scale. Topics such as vortex arrays in rotating superfluids, bound states in vortex cores and interaction of vortices with quasiparticles are discussed. The final chapter of the book considers implications of vortex dynamics to superfluid turbulence using simple scaling and symmetry arguments. Written from a unified point of view that avoids complicated mathematical approaches, this text is ideal for students and researchers working with vortex dynamics in superfluids, superconductors, magnetically ordered materials, neutron stars and cosmological mo...

Potential vorticity field in the Bay of Bengal during southwest monsoon

Digital Repository Service at National Institute of Oceanography (India)

Murty, V.S.N.; Rao, D.P.

theta), potential vorticity distribution is complex due to wind and freshwater forcings. The beta -effect dominates the potential vorticity field on 26.9 sigma theta isopycnal. The field of potential vorticity closely follows that of circulation...

Inflating metastable quark-gluon plasma universe

International Nuclear Information System (INIS)

Jenkovszky, L.L.; Kaempfer, B.; Sysoev, V.M.

1990-01-01

We show within the Friedmann model with the equation of state p(T)=aT 4 -AT that our universe has expanded exponentially when it was in a metastable quark-gluon plasma state. The scale factor during that epoch increased by many orders of magnitude. 13 refs.; 5 figs

Polarized photons from quark-gluon plasma

International Nuclear Information System (INIS)

Goloviznin, V.V.; Snigirev, A.M.; Zinov'ev, G.M.

1988-01-01

The degree of polarization of magnetic bremsstrahlung radiation resulting from the interaction of escaping quarks with a collective confining color field is calculated. For a wide rapidity interval the angle at which the photon is registered and constitutes about 25%. This could signal about quark-gluon plasma formation

Hairpin vortices in turbulent boundary layers

International Nuclear Information System (INIS)

Eitel-Amor, G; Schlatter, P; Flores, O

2014-01-01

The present work addresses the question whether hairpin vortices are a dominant feature of near-wall turbulence and which role they play during transition. First, the parent-offspring mechanism is investigated in temporal simulations of a single hairpin vortex introduced in a mean shear flow corresponding to turbulent channels and boundary layers up to Re τ = 590. Using an eddy viscosity computed from resolved simulations, the effect of a turbulent background is also considered. Tracking the vortical structure downstream, it is found that secondary hairpins are created shortly after initialization. Thereafter, all rotational structures decay, whereas this effect is enforced in the presence of an eddy viscosity. In a second approach, a laminar boundary layer is tripped to transition by insertion of a regular pattern of hairpins by means of defined volumetric forces representing an ejection event. The idea is to create a synthetic turbulent boundary layer dominated by hairpin-like vortices. The flow for Re τ < 250 is analysed with respect to the lifetime of individual hairpin-like vortices. Both the temporal and spatial simulations demonstrate that the regeneration process is rather short-lived and may not sustain once a turbulent background has formed. From the transitional flow simulations, it is conjectured that the forest of hairpins reported in former DNS studies is an outer layer phenomenon not being connected to the onset of near-wall turbulence.

Gluon density determination from open charm events at HERA

International Nuclear Information System (INIS)

Woudenberg, R. van; Ould-Saada, F.; Eisenberg, Y.; Glasman, C.; Karshon, U.; Montag, A.; Egli, S.

1992-01-01

We study some prospects of measuring the gluon density in the proton using charm events at HERA for the ep center of mass energy √s = 314 GeV. We invoke the QCD-improved boson-gluon fusion model and find the following cross-section: σ(ep → ecanti cX) ≅ O(0.6 μb). This cross-section would provide O(10 8 ) events/year, for an integrated luminosity of 100 pb -1 . We have investigated two traditional methods for tagging of charm, namely, D *± reconstruction using the process D *± → D 0 π ± → (K -+ π ± )π ± , and dileptonic decays of charmed hadrons (canti c → l + l - X). The inclusive cross-sections after full detector simulation are 10 3 pb and 10 2 pb, respectively. In both cases the background was strongly reduced. By using these events, the gluon distribution in the proton can be measured in the range 10 -3 ≤ x g ≤ 10 -1 . We conclude that an adequate discrimination among the present theoretical parametrizations can be achieved at HERA. (orig.)

Unintegrated gluon distributions in D*± and dijet associated photoproduction at HERA

International Nuclear Information System (INIS)

Lipatov, A.V.; Zotov, N.P.

2006-01-01

We consider the photoproduction of D *± mesons associated with two hadron jets at HERA collider in the framework of the k T -factorization approach. The unintegrated gluon densities in a proton are obtained from the full CCFM, from unified BFKL-DGLAP evolution equations as well as from the Kimber-Martin-Ryskin prescription. Resolved photon contributions are reproduced by the initial-state gluon radiation. We investigate different production rates and make a comparison with the recent experimental data taken by the ZEUS collaboration. Special attention is given to the specific dijet correlations which can provide unique information about non-collinear gluon evolution dynamics. (orig.)

On the link between martian total ozone and potential vorticity

Science.gov (United States)

Holmes, James A.; Lewis, Stephen R.; Patel, Manish R.

2017-01-01

We demonstrate for the first time that total ozone in the martian atmosphere is highly correlated with the dynamical tracer, potential vorticity, under certain conditions. The degree of correlation is investigated using a Mars global circulation model including a photochemical model. Potential vorticity is the quantity of choice to explore the dynamical nature of polar vortices because it contains information on winds and temperature in a single scalar variable. The correlation is found to display a distinct seasonal variation, with a strong positive correlation in both northern and southern winter at poleward latitudes in the northern and southern hemisphere respectively. The identified strong correlation implies variations in polar total ozone during winter are predominantly controlled by dynamical processes in these spatio-temporal regions. The weak correlation in northern and southern summer is due to the dominance of photochemical reactions resulting from extended exposure to sunlight. The total ozone/potential vorticity correlation is slightly weaker in southern winter due to topographical variations and the preference for ozone to accumulate in Hellas basin. In northern winter, total ozone can be used to track the polar vortex edge. The ozone/potential vorticity ratio is calculated for both northern and southern winter on Mars for the first time. Using the strong correlation in total ozone and potential vorticity in northern winter inside the polar vortex, it is shown that potential vorticity can be used as a proxy to deduce the distribution of total ozone where satellites cannot observe for the majority of northern winter. Where total ozone observations are available on the fringes of northern winter at poleward latitudes, the strong relationship of total ozone and potential vorticity implies that total ozone anomalies in the surf zone of the northern polar vortex can potentially be used to determine the origin of potential vorticity filaments.

Tight focusing properties of linearly polarized Gaussian beam with a pair of vortices

Energy Technology Data Exchange (ETDEWEB)

Chen, Ziyang [Department of Physics, Zhejiang University, Hangzhou 310027 (China); College of Information Science and Engineering, Institute of Optics and Photonics, Huaqiao University, Xiamen, Fujian 361021 (China); Pu, Jixiong [College of Information Science and Engineering, Institute of Optics and Photonics, Huaqiao University, Xiamen, Fujian 361021 (China); Zhao, Daomu, E-mail: zhaodaomu@yahoo.com [Department of Physics, Zhejiang University, Hangzhou 310027 (China)

2011-07-25

The properties of a pair of vortices embedded in a Gaussian beam focused by a high numerical-aperture are studied on the basis of vector Debye integral. The vortices move and rotate in the vicinity of the focal plane for a pair of vortices with equal topological charges. For incident beam with a pair of vortices with opposite topological charges, the vortices move toward each other, annihilate and revive in the vicinity of focal plane. -- Highlights: → The properties of a pair of vortices focused by a high numerical-aperture are studied. → It is shown that the focusing vortices with equal topological charges move toward and rotate. → It is shown that the focusing vortices with opposite topological charges move toward each other, annihilate and revive.

A QCD derivation of the additive quark model from two and three gluon exchanges

International Nuclear Information System (INIS)

Lipkin, H.J.

1982-06-01

The contributions to the Pomeron from two and three gluon exchanges are shown to give the correct combinatorial factors for the additive quark model relation between meson and baryon Pomeron couplings, even though two-quark and three-quark operators are involved. Similar results hold for the contributions to hadron masses from three-gluon vertices as well as one-gluon exchange. The color algebra reduces the multiquark couplings to a linear function of quark number. (author)

Gluon scattering in N=4 super Yang-Mills at finite temperature

International Nuclear Information System (INIS)

Ito, Katsushi; Iwasaki, Koh; Nastase, Horatiu

2008-01-01

We extend the AdS/CFT prescription of Alday and Maldacena to finite temperature T, defining an amplitude for gluon scattering in N=4 Super Yang-Mills at strong coupling from string theory. It is defined by a lightlike 'Wilson loop' living at the horizon of the T-dual to the black hole in AdS space. Unlike the zero temperature case, this is different from the Wilson loop contour defined at the boundary of the AdS black hole metric. Thus at nonzero T there is no relation between gluon scattering amplitudes and the Wilson loop. We calculate a gauge theory observable that can be interpreted as the amplitude at strong coupling for forward scattering of a low energy gluon (E >T) in both cutoff and generalized dimensional regularization. The generalized dimensional regularization is defined in string theory as an IR modified dimensional reduction. For this calculation, the corresponding usual Wilson loop of the same boundary shape was argued to be related to the jet quenching parameter of the finite temperature N=4 SYM plasma, while the gluon scattering amplitude is related to the viscosity coefficient. (author)

Growth and wall-transpiration control of nonlinear unsteady Görtler vortices forced by free-stream vortical disturbances

Science.gov (United States)

Marensi, Elena; Ricco, Pierre

2017-11-01

The generation, nonlinear evolution, and wall-transpiration control of unsteady Görtler vortices in an incompressible boundary layer over a concave plate is studied theoretically and numerically. Görtler rolls are initiated and driven by free-stream vortical perturbations of which only the low-frequency components are considered because they penetrate the most into the boundary layer. The formation and development of the disturbances are governed by the nonlinear unsteady boundary-region equations with the centrifugal force included. These equations are subject to appropriate initial and outer boundary conditions, which account for the influence of the upstream and free-stream forcing in a rigorous and mutually consistent manner. Numerical solutions show that the stabilizing effect on nonlinearity, which also occurs in flat-plate boundary layers, is significantly enhanced in the presence of centrifugal forces. Sufficiently downstream, the nonlinear vortices excited at different free-stream turbulence intensities Tu saturate at the same level, proving that the initial amplitude of the forcing becomes unimportant. At low Tu, the disturbance exhibits a quasi-exponential growth with the growth rate being intensified for more curved plates and for lower frequencies. At higher Tu, in the typical range of turbomachinery applications, the Görtler vortices do not undergo a modal stage as nonlinearity saturates rapidly, and the wall curvature does not affect the boundary-layer response. Good quantitative agreement with data from direct numerical simulations and experiments is obtained. Steady spanwise-uniform and spanwise-modulated zero-mass-flow-rate wall transpiration is shown to attenuate the growth of the Görtler vortices significantly. A novel modified version of the Fukagata-Iwamoto-Kasagi identity, used for the first time to study a transitional flow, reveals which terms in the streamwise momentum balance are mostly affected by the wall transpiration, thus

Physical properties corresponding to vortical flow geometry

Energy Technology Data Exchange (ETDEWEB)

Nakayama, K, E-mail: nakayama@aitech.ac.jp [Department of Mechanical Engineering, Aichi Institute of Technology, Toyota, Aichi 470-0392 (Japan)

2014-10-01

We examine a vortical flow geometry specified by the velocity gradient tensor ∇v, and derive properties representing the symmetry (axisymmetry or skewness) of the vortical flow in the swirl plane and a property specifying inflowing (outflowing) motion in all directions around the point. We focus on the radial and azimuthal velocities in a plane nonparallel to the eigenvector corresponding to the real eigenvalue of ∇v and show that these components are expressed as specific quadratic forms. The real and imaginary parts of the complex eigenvalues of ∇v represent averages of these eigenvalues of the quadratic forms, and are inadequate to specify the detailed flow geometry uniquely. The new properties complement specifying the precise flow geometry of the vortical flow.

Towards laboratory detection of topological vortices in superfluid phases of QCD

Science.gov (United States)

Das, Arpan; Dave, Shreyansh S.; de, Somnath; Srivastava, Ajit M.

2017-10-01

Topological defects arise in a variety of systems, e.g. vortices in superfluid helium to cosmic strings in the early universe. There is an indirect evidence of neutron superfluid vortices from the glitches in pulsars. One also expects that the topological defects may arise in various high baryon density phases of quantum chromodynamics (QCD), e.g. superfluid topological vortices in the color flavor locked (CFL) phase. Though vastly different in energy/length scales, there are universal features in the formation of all these defects. Utilizing this universality, we investigate the possibility of detecting these topological superfluid vortices in laboratory experiments, namely heavy-ion collisions (HICs). Using hydrodynamic simulations, we show that vortices can qualitatively affect the power spectrum of flow fluctuations. This can give an unambiguous signal for superfluid transition resulting in vortices, allowing for the check of defect formation theories in a relativistic quantum field theory system, and the detection of superfluid phases of QCD. Detection of nucleonic superfluid vortices in low energy HICs will give opportunity for laboratory controlled study of their properties, providing crucial inputs for the physics of pulsars.

Time evolution of the quark-gluon plasma

International Nuclear Information System (INIS)

Cooper, F.; New Hampshire Univ., Durham, NH

1993-01-01

We review progress in our understanding the production and time evolution of the quark gluon plasma starting with boost invariant initial conditions in a filed theory model based on the Schwinger mechanism of particle production via tunneling

Gluon and ghost propagator studies in lattice QCD at finite temperature

Energy Technology Data Exchange (ETDEWEB)

Aouane, Rafik

2013-04-29

Gluon and ghost propagators in quantum chromodynamics (QCD) computed in the infrared momentum region play an important role to understand quark and gluon confinement. They are the subject of intensive research thanks to non-perturbative methods based on Dyson-Schwinger (DS) and functional renormalization group (FRG) equations. Moreover, their temperature behavior might also help to explore the chiral and deconfinement phase transition or crossover within QCD at non-zero temperature. Our prime tool is the lattice discretized QCD (LQCD) providing a unique ab-initio non-perturbative approach to deal with the computation of various observables of the hadronic world. We investigate the temperature dependence of Landau gauge gluon and ghost propagators in pure gluodynamics and in full QCD. Regarding the gluon propagator, we compute its longitudinal D{sub L} as well its transversal D{sub T} components. The aim is to provide a data set in terms of fitting formulae which can be used as input for DS (or FRG) equations. We deal with full (N{sub f}=2) LQCD with the twisted mass fermion discretization. We employ gauge field configurations provided by the tmfT collaboration for temperatures in the crossover region and for three fixed pion mass values in the range [300,500] MeV. Finally, within SU(3) pure gauge theory (at T=0) we compute the Landau gauge gluon propagator according to different gauge fixing criteria. Our goal is to understand the influence of gauge copies with minimal (non-trivial) eigenvalues of the Faddeev-Popov operator.

Characteristics and controllability of vortices in ferromagnetics, ferroelectrics, and multiferroics.

Science.gov (United States)

Zheng, Yue; Chen, W J

2017-08-01

Topological defects in condensed matter are attracting e significant attention due to their important role in phase transition and their fascinating characteristics. Among the various types of matter, ferroics which possess a switchable physical characteristic and form domain structure are ideal systems to form topological defects. In particular, a special class of topological defects-vortices-have been found to commonly exist in ferroics. They often manifest themselves as singular regions where domains merge in large systems, or stabilize as novel order states instead of forming domain structures in small enough systems. Understanding the characteristics and controllability of vortices in ferroics can provide us with deeper insight into the phase transition of condensed matter and also exciting opportunities in designing novel functional devices such as nano-memories, sensors, and transducers based on topological defects. In this review, we summarize the recent experimental and theoretical progress in ferroic vortices, with emphasis on those spin/dipole vortices formed in nanoscale ferromagnetics and ferroelectrics, and those structural domain vortices formed in multiferroic hexagonal manganites. We begin with an overview of this field. The fundamental concepts of ferroic vortices, followed by the theoretical simulation and experimental methods to explore ferroic vortices, are then introduced. The various characteristics of vortices (e.g. formation mechanisms, static/dynamic features, and electronic properties) and their controllability (e.g. by size, geometry, external thermal, electrical, magnetic, or mechanical fields) in ferromagnetics, ferroelectrics, and multiferroics are discussed in detail in individual sections. Finally, we conclude this review with an outlook on this rapidly developing field.

Nonautonomous Vortices in (2+1)-Dimensional Graded-Index Waveguide

International Nuclear Information System (INIS)

Lai Xian-Jing; Zhang Jie-Fang; Cai Xiao-Ou

2015-01-01

With the help of self-similarity transformation, we construct and study the nonautonomous vortices with different topological charges inside a planar graded-index nonlinear waveguide, analytically, and numerically. Although these vortices are approximate, they can reflect the real properties of self-similar optical beam during a short-term propagation. Existence of these autonomous vortices require delicate balances between the system parameters such as diffraction, nonlinearity, gain, and external potential. We are concerned with some special but interesting situations, and discussing the changes of the height, width, energy, and central position of the vortices as the increase of propagation distance. Moreover, we are also interested in the azimuthal modulational instability of the system, and comparing our prediction for the modulational instability growth rates to numerical results. (paper)

The strong running coupling from an approximate gluon Dyson-Schwinger equation

International Nuclear Information System (INIS)

Alkofer, R.; Hauck, A.

1996-01-01

Using Mandelstam's approximation to the gluon Dyson-Schwinger equation we calculate the gluon self-energy in a renormalisation group invariant fashion. We obtain a non-perturbative Β function. The scaling behavior near the ultraviolet stable fixed point is in good agreement with perturbative QCD. No further fixed point for positive values of the coupling is found: α S increases without bound in the infrared

QCD-motivated Nambu-Jona-Lasinio model with quark and gluon condensates

International Nuclear Information System (INIS)

Ebert, D.; Volkov, M.K.

1991-01-01

We present a systematic study of the role of the nonperturbative gluon condensate arising in a QCD-motivated NJL model. The effects of the gluon condensate on induced meson couplings, the pion decay constant, quark condensate and mass formulae are investigated. An interesting result is the change of the scale Λ of chiral symmetry breaking and of the universal four-quark coupling κ. (orig.)

Electromagnetic signals of quark gluon plasma

Indian Academy of Sciences (India)

Successive equilibration of quark degrees of freedom and its effects on electromagnetic signals of quark gluon plasma are discussed. The effects of the variation of vector meson masses and decay widths on photon production from hot strongly interacting matter formed after Pb + Pb and S + Au collisions at CERN SPS ...

Driven motion of vortices in superconductors

International Nuclear Information System (INIS)

Crabtree, G.W.; Leaf, G.K.; Kaper, H.G.; Vinokur, V.M.; Koshelev, A.E.; Braun, D.W.; Levine, D.M.

1995-09-01

The driven motion of vortices in the solid vortex state is analyzed with the time-dependent Ginzburg-Landau equations. In large-scale numerical simulations, carried out on the IBM Scalable POWERparallel (SP) system at Argonne National Laboratory, many hundreds of vortices are followed as they move under the influence of a Lorentz force induced by a transport current in the presence of a planar defect (similar to a twin boundary in YBa 2 CU 3 O 7 ). Correlations in the positions and velocities of the vortices in plastic and elastic motion are identified and compared. Two types of plastic motion are observed. Organized plastic motion displaying long-range orientational correlation and shorter-range velocity correlation occurs when the driving forces are small compared to the pinning forces in the twin boundary. Disorganized plastic motion displaying no significant correlation in either the velocities or orientation of the vortex system occurs when the driving and pinning forces axe of the same order

Physics and astrophysics of quark-gluon plasma

Energy Technology Data Exchange (ETDEWEB)

Anon.

1993-06-15

The quark gluon plasma - matter too hot or dense for quarks to crystallize into particles - played a vital role in the formation of the Universe. Efforts to recreate and understand this type of matter are forefront physics and astrophysics, and progress was highlighted in the Second International Conference on Physics and Astrophysics of Quark Gluon Plasma (ICPA-QGP 93), held in Calcutta from 19-23 January. (The first conference in the series was held in Bombay in February 1988). Although primarily motivated towards enlightening the Indian physics community in this new and rapidly evolving area, in which India now plays an important role, the conference also catered for an international audience. Particular emphasis was placed on the role of quark gluon plasma in astrophysics and cosmology. While Charles Alcock of Lawrence Livermore looked at a less conventional picture giving inhomogeneous ('clumpy') nucleosynthesis, David Schramm (Chicago) covered standard big bang nucleosynthesis. The abundances of very light elements do not differ appreciably for these contrasting scenarios; the crucial difference between them shows up for heavier elements like lithium-7 and -8 and boron-11. Richard Boyd (Ohio State) highlighted the importance of accurate measurements of the primordial abundances of these elements for clues to the cosmic quark hadron phase transition. B. Banerjee (Bombay) argued, on the basis of lattice calculations, for only slight supercooling in the cosmic quark phase transition - an assertion which runs counter to the inhomogeneous nucleosynthesis scenario.

Physics and astrophysics of quark-gluon plasma

International Nuclear Information System (INIS)

Anon.

1993-01-01

The quark gluon plasma - matter too hot or dense for quarks to crystallize into particles - played a vital role in the formation of the Universe. Efforts to recreate and understand this type of matter are forefront physics and astrophysics, and progress was highlighted in the Second International Conference on Physics and Astrophysics of Quark Gluon Plasma (ICPA-QGP 93), held in Calcutta from 19-23 January. (The first conference in the series was held in Bombay in February 1988). Although primarily motivated towards enlightening the Indian physics community in this new and rapidly evolving area, in which India now plays an important role, the conference also catered for an international audience. Particular emphasis was placed on the role of quark gluon plasma in astrophysics and cosmology. While Charles Alcock of Lawrence Livermore looked at a less conventional picture giving inhomogeneous ('clumpy') nucleosynthesis, David Schramm (Chicago) covered standard big bang nucleosynthesis. The abundances of very light elements do not differ appreciably for these contrasting scenarios; the crucial difference between them shows up for heavier elements like lithium-7 and -8 and boron-11. Richard Boyd (Ohio State) highlighted the importance of accurate measurements of the primordial abundances of these elements for clues to the cosmic quark hadron phase transition. B. Banerjee (Bombay) argued, on the basis of lattice calculations, for only slight supercooling in the cosmic quark phase transition - an assertion which runs counter to the inhomogeneous nucleosynthesis scenario

Check of the bootstrap conditions for the gluon Reggeization

International Nuclear Information System (INIS)

Papa, A.

2000-01-01

The property of gluon Reggeization plays an essential role in the derivation of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equation for the cross sections at high energy √s in perturbative QCD. This property has been proved to all orders of perturbation theory in the leading logarithmic approximation and it is assumed to be valid also in the next-to-leading logarithmic approximation, where it has been checked only to the first three orders of perturbation theory. From s-channel unitarity, however, very stringent 'bootstrap' conditions can be derived which, if fulfilled, leave no doubts that gluon Reggeization holds

Soft Probes of the Quark-Gluon Plasma in ATLAS

CERN Document Server

Wozniak, K W; The ATLAS collaboration

2014-01-01

Measurements of low-$p_{_{\\rm T}}$ ($<$ 5 GeV) particles in Pb+Pb collisions at the LHC provide valuable insight in the production and evolution of the quark-gluon plasma. In particular, measurements of the elliptic and higher order collective flow imprinted on the azimuthal angle distributions of low-$p_{T}$ particles directly probe the strongly-coupled dynamics of the quark gluon plasma and test hydrodynamic model descriptions of its evolution. The large acceptance of detectors like ATLAS makes it possible to measure flow event-by-event and to determine the correlations between different event planes and different flow harmonics.

A gluon cluster solution of effective Yang-Mills theory

CERN Document Server

Pavlovsky, O V

2001-01-01

A classical solution of the effective Yang-Mills (YM) theory with a finite energy and nonstandard Lagrangian was obtained. Influence of vacuum polarization on gluon cluster formation was discussed. Appearance of cluster solutions in the theory of non-Abelian fields can take place only if the result goes beyond the framework of pure YM theory. It is shown that account of quantum effects of polarized vacuum in the presence of a classical gluon field can also result in formation of the solutions. Solutions with the finite intrinsic energy are provided. Besides, fields of colour groups SU(2) were studied

Dilepton spectrum from quark-gluon plasma in second Born approximation

International Nuclear Information System (INIS)

Makhlin, A.N.

1989-01-01

The real time temperature Keldysh technique has been used to calculate the rate of dilepton emission from quark-gluon plasma in the first order with respect to strong coupling constant. This approximation us shown to be inconsistent. The radiative corrections turned to be of the same order as the contribution of real processes with gluons. Nevertheless the general properties inherent in dilepton emission from continuous media can be verified by measuring the lepton distribution inside the dilepton. 11 refs.; 2 figs

Quark-gluon plasma in strong magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Kalaydzhyan, Tigran

2013-04-15

One of the fundamental problems in subatomic physics is the determination of properties of matter at extreme temperatures, densities and electromagnetic fields. The modern ultrarelativistic heavy-ion experiments are able to study such states (the quark-gluon plasma) and indicate that the physics at extreme conditions differs drastically from what is known from the conventional observations. Also the theoretical methods developed mostly within the perturbative framework face various conceptual problems and need to be replaced by a nonperturbative approach. In this thesis we study the physics of the strongly-coupled quark-gluon plasma in external magnetic fields as well as general electromagnetic and topological properties of the QCD and QCD-like systems. We develop and apply various nonperturbative techniques, based on e.g. gauge-gravity correspondence, lattice QCD simulations, relativistic hydrodynamics and condensed-matter-inspired models.

Quark-gluon plasma in strong magnetic fields

International Nuclear Information System (INIS)

Kalaydzhyan, Tigran

2013-04-01

One of the fundamental problems in subatomic physics is the determination of properties of matter at extreme temperatures, densities and electromagnetic fields. The modern ultrarelativistic heavy-ion experiments are able to study such states (the quark-gluon plasma) and indicate that the physics at extreme conditions differs drastically from what is known from the conventional observations. Also the theoretical methods developed mostly within the perturbative framework face various conceptual problems and need to be replaced by a nonperturbative approach. In this thesis we study the physics of the strongly-coupled quark-gluon plasma in external magnetic fields as well as general electromagnetic and topological properties of the QCD and QCD-like systems. We develop and apply various nonperturbative techniques, based on e.g. gauge-gravity correspondence, lattice QCD simulations, relativistic hydrodynamics and condensed-matter-inspired models.

Quantum Simulations of Strongly Coupled Quark-Gluon Plasma

International Nuclear Information System (INIS)

Filinov, V.S.; Bonitz, M.; Ivanov, Yu.B.

2013-01-01

In recent years, there has been an increasing interest in dynamics and thermodynamics of non-Abelian plasmas at both very high temperature and density. It is expected that a specific state of matter with unconfined quarks and gluons - the so called quark - gluon plasma (QGP) - can exist. The most fundamental way to compute properties of the strongly interacting matter is provided by the lattice QCD. Interpretation of these very complicated computations requires application of various QCD motivated, albeit schematic, models simulating various aspects of the full theory. Moreover, such models are needed in cases when the lattice QCD fails, e.g. at large baryon chemical potentials and out of equilibrium. A semi-classical approximation, based on a point like quasi-particle picture has been recently introduced in literature. It is expected that it allows to treat soft processes in the QGP which are not accessible by the perturbative means and the main features of non-Abelian plasmas can be understood in simple semi-classical terms without the difficulties inherent to a full quantum field theoretical analysis. Here we propose stochastic simulation of thermodynamics and kinetic properties for QGP in semi-classical approximation in the wide region of temperature, density and quasi-particles masses. We extend previous classical nonrelativistic simulations based on a color Coulomb interaction to the quantum regime and take into account the Fermi (Bose) statistics of quarks (gluons) and quantum degeneracy self-consistently. In grand canonical ensemble for finite and zero baryon chemical potential we use the direct quantum path integral Monte Carlo method (PIMC) developed for finite temperature within Feynman formulation of quantum mechanics to do calculations of internal energy, pressure and pair correlation functions. The QGP quasi-particles representing dressed quarks, antiquarks and gluons interact via color quantum Kelbg pseudopotential rigorously derived in for Coulomb

The gluon momentum fraction of the nucleon from lattice QCD

International Nuclear Information System (INIS)

Alexandrou, Constantia; Hadjiyiannakou, Kyriakos; Constantinou, Martha; Jansen, Karl; Wiese, Christian; Panagopoulos, Haralambos

2016-01-01

We perform a direct calculation of the gluon momentum fraction of the nucleon using maximally twisted mass fermion ensembles with N_f=2+1+1 flavors at a pion mass of about 370 MeV and a lattice spacing of a∼0.082 fm and with N_f=2 flavors at the physical pion mass and a lattice spacing of a∼0.093 fm. In the definition of the gluon operator we employ stout smearing to obtain a statistically significant result for the bare matrix elements. In addition, we perform a lattice perturbative calculation including 2 levels of stout smearing to carry out the mixing and the renormalization of the quark and gluon operators. We find, after conversion to the MS scheme at a scale of 2 GeV: left angle x right angle "R_g=0.284(23)(23) for pion mass of about 370 MeV and left angle x right angle "R_g=0.283(23)(15) for the physical pion mass.

Squeezed colour states in gluon jet

Science.gov (United States)

Kilin, S. YA.; Kuvshinov, V. I.; Firago, S. A.

1993-01-01

The possibility of the formation of squeezed states of gluon fields in quantum chromodynamics due to nonlinear nonperturbative self interaction during jet evolution in the process of e(+)e(-) annihilation into hadrons, which are analogous to the quantum photon squeezed states in quantum electrodynamics, is demonstrated. Additionally, the squeezing parameters are calculated.

Soft gluon contributions to hard processes

International Nuclear Information System (INIS)

Ciafaloni, M.

1981-10-01

The main concern of this paper is in trying to elucidate the origin of large QCD perturbative corrections and explain how to deal with them to all orders. They come essentially from the phase space regions close to the kinematical boundary of a hard process, in which one or many gluons become soft

Numerical analysis of propeller induced ground vortices by actuator disk model

NARCIS (Netherlands)

Yang, Y.; Veldhuis, L.L.M.; Eitelberg, G.

2017-01-01

Abstract: During the ground operation of aircraft, the interaction between the propulsor-induced flow field and the ground may lead to the generation of ground vortices. Utilizing numerical approaches, the source of vorticity entering ground vortices is investigated. The results show that the

Potential Vorticity Evolution in the Co-orbital Region of Embedded Protoplanets

International Nuclear Information System (INIS)

Koller, J.

2004-01-01

This thesis presents two-dimensional hydrodynamic disk simulations with embedded protoplanets, emphasizing the non-linear dynamics in the co-orbital region. In particular, it demonstrates how a protoplanetary disk responds to embedded low mass planets at the inviscid limit. Since the potential vorticity (PV) flow is not conserved, due to the spiral shocks and possibly boundary layer effects emanating from the planet, the PV profile develops inflection points which eventually render the flow unstable. Vortices are produced in association with the potential vorticity minima. Born in the separatrix region, these vortices experience close encounters with the planet, consequently exerting strong torques on the planet. The existence of these vortices, if confirmed, have important implications on planetary migration rates. The formation of vortices is discussed in more detail and a key parameter is found which depends solely on planet mass and sound speed. With this key parameter, one can predict the disk evolution, PV growth rates, and threshold conditions for forming vortices in the co-orbital region. An analytical estimate for the change of PV due to shocks is compared to the actual change in PV in the hydrodynamic simulations. They match well except in the inner region where vortices form. In addition, extensive resolution tests were carried out but uncertainties remain about the physics of this particular region

QCD-motivated Nambu-Jona-Lasinio model with quark and gluon condensates

International Nuclear Information System (INIS)

Ebert, D.; Volkov, M.K.

1991-01-01

A systematic study of the role of the nonperturbative gluon condensate arising in a QCD-motivated Nambu-Jona-Lasinio model is presented. The effects of the gluon condensate on induced meson couplings, the pion decay constant, quark condensate and mass formulae are investigated. An interesting result is the change of the scale Λ of chiral symmetry breaking and of the universal four-quark coupling constant κ. 20 refs

Regge behaviour of structure function and gluon distribution at low-x in leading order

International Nuclear Information System (INIS)

Sarma, J.K.

2000-01-01

We present a method to find the gluon distribution from the F 2 proton structure function data at low-x assuming the Regge behaviour of the gluon distribution function at this limit. We use the leading order (LO) Altarelli-Parisi (AP) evolution equation in our analysis and compare our result with those of other authors. We also discuss the limitations of the Taylor expansion method in extracting the gluon distribution from the F 2 structure function used by those authors. (orig.)

A Laboratory Study of Vortical Structures in Rotating Convection Plumes

Science.gov (United States)

Fu, Hao; Sun, Shiwei; Wang, Yuan; Zhou, Bowen; Thermal Turbulence Research Team

2015-11-01

A laboratory study of the columnar vortex structure in rotating Rayleigh-Bénard convection is conducted. A rectangular water tank is uniformly heated from below and cooled from above, with Ra = (6 . 35 +/- 0 . 77) ×107 , Ta = 9 . 84 ×107 , Pr = 7 . 34 . The columnar vortices are vertically aligned and quasi steady. Two 2D PIV systems were used to measure velocity field. One system performs horizontal scans at 9 different heights every 13.6s, covering 62% of the total depth. The other system scans vertically to obtain the vertical velocity profile. The measured vertical vorticity profiles of most vortices are quasi-linear with height while the vertical velocities are nearly uniform with only a small curvature. A simple model to deduce vertical velocity profile from vertical vorticity profile is proposed. Under quasi-steady and axisymmetric conditions, a ``vortex core'' assumption is introduced to simplify vertical vorticity equation. A linear ODE about vertical velocity is obtained whenever a vertical vorticity profile is given and solved with experimental data as input. The result is approximately in agreement with the measurement. This work was supported by Undergraduates Training Project (J1103410).

Ginzburg-Landau vortices

CERN Document Server

Bethuel, Fabrice; Helein, Frederic

2017-01-01

This book is concerned with the study in two dimensions of stationary solutions of uɛ of a complex valued Ginzburg-Landau equation involving a small parameter ɛ. Such problems are related to questions occurring in physics, e.g., phase transition phenomena in superconductors and superfluids. The parameter ɛ has a dimension of a length which is usually small.  Thus, it is of great interest to study the asymptotics as ɛ tends to zero. One of the main results asserts that the limit u-star of minimizers uɛ exists. Moreover, u-star is smooth except at a finite number of points called defects or vortices in physics. The number of these defects is exactly the Brouwer degree – or winding number – of the boundary condition. Each singularity has degree one – or as physicists would say, vortices are quantized. The singularities have infinite energy, but after removing the core energy we are lead to a concept of finite renormalized energy.  The location of the singularities is completely determined by minimiz...

Error Propagation dynamics: from PIV-based pressure reconstruction to vorticity field calculation

Science.gov (United States)

Pan, Zhao; Whitehead, Jared; Richards, Geordie; Truscott, Tadd; USU Team; BYU Team

2017-11-01

Noninvasive data from velocimetry experiments (e.g., PIV) have been used to calculate vorticity and pressure fields. However, the noise, error, or uncertainties in the PIV measurements would eventually propagate to the calculated pressure or vorticity field through reconstruction schemes. Despite the vast applications of pressure and/or vorticity field calculated from PIV measurements, studies on the error propagation from the velocity field to the reconstructed fields (PIV-pressure and PIV-vorticity are few. In the current study, we break down the inherent connections between PIV-based pressure reconstruction and PIV-based vorticity calculation. The similar error propagation dynamics, which involve competition between physical properties of the flow and numerical errors from reconstruction schemes, are found in both PIV-pressure and PIV-vorticity reconstructions.

A gauge quantum field theory of confined quarks and gluons

International Nuclear Information System (INIS)

Voelkel, A.H.

1983-01-01

A SU(3)-gauge quantum field theory with a quark triplet, an antiquark triplet and a self-conjugate gluon octet as basic fields is investigated. In virtue of a non trivial coupling between the representation of the translation group and the SU(3)-colour charge of the basic fields it is proved: (i) The basic quark, antiquark and gluon fields are confined. (ii) Every statevector of the physical Hilbert space is a SU(3)-colour singlet state. (iii) Poincare invariance holds in the physical Hilbert space. (orig.)

Recent status in the search for the quark-gluon plasma

International Nuclear Information System (INIS)

Wong, Cheuk-Yin.

1995-01-01

The author reviews recent experimental results in the search for the quark-gluon plasma. Because the magnitudes of many signals for the plasma are directly proportional to the reaction cross sections, the author examines the corrections to the commonly used lowest-order cross sections. The author finds that the corrections are often significant and should be properly taken into account. The use of dileptons and photons with large transverse momenta is suggested as a means to study the boundary of the quark-gluon plasma

Multiplicities of $\\pi^{0}$, $\\eta$, $K^{0}$ and of charged particles in quark and gluon jets

CERN Document Server

Abbiendi, G.; Ainsley, C.; Akesson, P.F.; Alexander, G.; Allison, John; Anderson, K.J.; Arcelli, S.; Asai, S.; Ashby, S.F.; Axen, D.; Azuelos, G.; Bailey, I.; Ball, A.H.; Barberio, E.; Barlow, Roger J.; Batley, J.R.; Baumann, S.; Behnke, T.; Bell, Kenneth Watson; Bella, G.; Bellerive, A.; Bentvelsen, S.; Bethke, S.; Biebel, O.; Bloodworth, I.J.; Bock, P.; Bohme, J.; Boeriu, O.; Bonacorsi, D.; Boutemeur, M.; Braibant, S.; Bright-Thomas, P.; Brigliadori, L.; Brown, Robert M.; Burckhart, H.J.; Cammin, J.; Capiluppi, P.; Carnegie, R.K.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Ciocca, C.; Clarke, P.E.L.; Clay, E.; Cohen, I.; Cooke, O.C.; Couchman, J.; Couyoumtzelis, C.; Coxe, R.L.; Cuffiani, M.; Dado, S.; Dallavalle, G.Marco; Dallison, S.; de Roeck, A.; Dervan, P.; Desch, K.; Dienes, B.; Dixit, M.S.; Donkers, M.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Estabrooks, P.G.; Etzion, E.; Fabbri, F.; Fanti, M.; Feld, L.; Ferrari, P.; Fiedler, F.; Fleck, I.; Ford, M.; Frey, A.; Furtjes, A.; Futyan, D.I.; Gagnon, P.; Gary, J.W.; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Glenzinski, D.; Goldberg, J.; Grandi, C.; Graham, K.; Gross, E.; Grunhaus, J.; Gruwe, M.; Gunther, P.O.; Hajdu, C.; Hanson, G.G.; Hansroul, M.; Hapke, M.; Harder, K.; Harel, A.; Hargrove, C.K.; Harin-Dirac, M.; Hauke, A.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Hensel, C.; Herten, G.; Heuer, R.D.; Hildreth, M.D.; Hill, J.C.; Hocker, James Andrew; Hoffman, Kara Dion; Homer, R.J.; Honma, A.K.; Horvath, D.; Hossain, K.R.; Howard, R.; Huntemeyer, P.; Igo-Kemenes, P.; Ishii, K.; Jacob, F.R.; Jawahery, A.; Jeremie, H.; Jones, C.R.; Jovanovic, P.; Junk, T.R.; Kanaya, N.; Kanzaki, J.; Karapetian, G.; Karlen, D.; Kartvelishvili, V.; Kawagoe, K.; Kawamoto, T.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kim, D.H.; Klein, K.; Klier, A.; Kobayashi, T.; Kobel, M.; Kokott, T.P.; Komamiya, S.; Kowalewski, Robert V.; Kress, T.; Krieger, P.; von Krogh, J.; Kuhl, T.; Kupper, M.; Kyberd, P.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Lawson, I.; Layter, J.G.; Leins, A.; Lellouch, D.; Letts, J.; Levinson, L.; Liebisch, R.; Lillich, J.; List, B.; Littlewood, C.; Lloyd, A.W.; Lloyd, S.L.; Loebinger, F.K.; Long, G.D.; Losty, M.J.; Lu, J.; Ludwig, J.; Macchiolo, A.; Macpherson, A.; Mader, W.; Mannelli, M.; Marcellini, S.; Marchant, T.E.; Martin, A.J.; Martin, J.P.; Martinez, G.; Mashimo, T.; Mattig, Peter; McDonald, W.John; McKenna, J.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Mendez-Lorenzo, P.; Merritt, F.S.; Mes, H.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Mohr, W.; Montanari, A.; Mori, T.; Nagai, K.; Nakamura, I.; Neal, H.A.; Nisius, R.; O'Neale, S.W.; Oakham, F.G.; Odorici, F.; Ogren, H.O.; Oh, A.; Okpara, A.; Oreglia, M.J.; Orito, S.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Patt, J.; Pfeifenschneider, P.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poli, B.; Polok, J.; Pooth, O.; Przybycien, M.; Quadt, A.; Rembser, C.; Rick, H.; Robins, S.A.; Rodning, N.; Roney, J.M.; Rosati, S.; Roscoe, K.; Rossi, A.M.; Rozen, Y.; Runge, K.; Runolfsson, O.; Rust, D.R.; Sachs, K.; Saeki, T.; Sahr, O.; Sarkisyan, E.K.G.; Sbarra, C.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schmitt, S.; Schroder, Matthias; Schumacher, M.; Schwick, C.; Scott, W.G.; Seuster, R.; Shears, T.G.; Shen, B.C.; Shepherd-Themistocleous, C.H.; Sherwood, P.; Siroli, G.P.; Skuja, A.; Smith, A.M.; Snow, G.A.; Sobie, R.; Soldner-Rembold, S.; Spagnolo, S.; Sproston, M.; Stahl, A.; Stephens, K.; Stoll, K.; Strom, David M.; Strohmer, R.; Surrow, B.; Talbot, S.D.; Tarem, S.; Taylor, R.J.; Teuscher, R.; Thiergen, M.; Thomas, J.; Thomson, M.A.; Torrence, E.; Towers, S.; Trefzger, T.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turner-Watson, M.F.; Ueda, I.; Vannerem, P.; Verzocchi, M.; Voss, H.; Vossebeld, J.; Waller, D.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wengler, T.; Wermes, N.; Wetterling, D.; White, J.S.; Wilson, G.W.; Wilson, J.A.; Wyatt, T.R.; Yamashita, S.; Zacek, V.; Zer-Zion, D.

2000-01-01

We compared the multiplicities of pizero, eta, Kzero and of charged particles in quark and gluon jets in 3-jet events, as measured by the OPAL experiment at LEP. The comparisons were performed for distributions unfolded to 100% pure quark and gluon jets, at an effective scale Qjet which took into account topological dependences of the 3-jet environment. The ratio of particle multiplicity in gluon jets to that in quark jets as a function of Qjet for pizero, eta and Kzero was found to be independent of the particle species. This is consistent with the QCD prediction that the observed enhancement in the mean particle rate in gluon jets with respect to quark jets should be independent of particle species. In contrast to some theoretical predictions and previous observations, we observed no evidence for an enhancement of eta meson production in gluon jets with respect to quark jets, beyond that observed for charged particles. We measured the ratio of the slope of the average charged particle multiplicity in gluon ...

Lattice vortices in the two-dimensional Abelian Higgs model

International Nuclear Information System (INIS)

Grunewald, S.; Ilgenfritz, E.-M.; Mueller-Preussker, M.

1986-01-01

Multi-vortices of the 2D Abelian Higgs model on a finite lattice by relaxation of Monte-Carlo equilibrium configurations are generated and identified. The lattice vortices have action and a uniquely defined topological charge corresponding to the continuum ones. They exhibit the expected exponential decay behaviour and satisfy approximately the classical equations of motion. Vortex-antivortex superpositions are seen as well, supporting the dilute gas picture. Single vortices finally relax into ''dislocations'' and dissapear. A background charge construction turns out nearly insensitive with respect to dislocations

The soft-gluon current at one-loop order

CERN Document Server

Catani, S

2000-01-01

We study the soft limit of one-loop QCD amplitudes and we derive the process-independent factorization formula that controls the singular behaviour in this limit. This is obtained from the customary eikonal factorization formula valid at tree (classical) level by introducing a generalized soft-gluon current that embodies the quantum corrections. We compute the explicit expression of the soft-gluon current at one-loop order. It contains purely non-abelian correlations between the colour charges of each pair of hard-momentum partons in the matrix element. This leads to colour correlations between (two and) three hard partons in the matrix element squared. Exploiting colour conservation, we recover QED-like factorization for the square of the matrix elements with two and three hard partons.

Laboratory experiments on multipolar vortices in a rotating fluid

NARCIS (Netherlands)

Trieling, R.R.; Heijst, van G.J.F.; Kizner, Ziv

2010-01-01

The instability properties of isolated monopolar vortices have been investigated experimentally and the corresponding multipolar quasisteady states have been compared with semianalytical vorticity-distributed solutions to the Euler equations in two dimensions. A novel experimental technique was

Pinning down the large-x gluon with NNLO top-quark pair differential distributions

Energy Technology Data Exchange (ETDEWEB)

Czakon, Michał [Institut für Theoretische Teilchenphysik und Kosmologie, RWTH Aachen University,D-52056 Aachen (Germany); Hartland, Nathan P. [Department of Physics and Astronomy, VU University Amsterdam,De Boelelaan 1081, NL-1081, HV Amsterdam (Netherlands); Nikhef,Science Park 105, NL-1098 XG Amsterdam (Netherlands); Mitov, Alexander [Cavendish Laboratory, University of Cambridge,Cambridge CB3 0HE (United Kingdom); Nocera, Emanuele R. [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, OX1 3NP, Oxford (United Kingdom); Rojo, Juan [Department of Physics and Astronomy, VU University Amsterdam,De Boelelaan 1081, NL-1081, HV Amsterdam (Netherlands); Nikhef,Science Park 105, NL-1098 XG Amsterdam (Netherlands)

2017-04-10

Top-quark pair production at the LHC is directly sensitive to the gluon PDF at large x. While total cross-section data is already included in several PDF determinations, differential distributions are not, because the corresponding NNLO calculations have become available only recently. In this work we study the impact on the large-x gluon of top-quark pair differential distributions measured by ATLAS and CMS at √s=8 TeV. Our analysis, performed in the NNPDF3.0 framework at NNLO accuracy, allows us to identify the optimal combination of LHC top-quark pair measurements that maximize the constraints on the gluon, as well as to assess the compatibility between ATLAS and CMS data. We find that differential distributions from top-quark pair production provide significant constraints on the large-x gluon, comparable to those obtained from inclusive jet production data, and thus should become an important ingredient for the next generation of global PDF fits.

Inclusive gluon production in the dipole approach: Abramovskii-Gribov-Kancheli (AGK) cutting rules

International Nuclear Information System (INIS)

Levin, Eugene; Prygarin, Alex

2008-01-01

We consider single gluon production in the dipole model and reproduce the result of Kovchegov and Tuchin for the adjoint (gluonic) dipole structure of the inclusive cross section. We show the validity of the adjoint dipole structure to any order of evolution by deriving and solving the nonlinear evolution for the nondiagonal cross section of a dipole scattering off the target. The form of the solution to this equation restores the dipole interpretation for nondiagonal cross sections that appear in gluon production. Using this formalism, we analyze the single inclusive production cross section in terms of the contributions of different multiplicities, and we derive the Abramovskii-Gribov-Kancheli (AGK) cutting rules for two-Pomeron exchange. The cutting rules, which were found in this formalism, fully reproduce the original AGK rules for the total cross section. However, for the case of gluon production, the AGK rules are violated already for one-gluon emission from the vertex

Pinning down the large-x gluon with NNLO top-quark pair differential distributions

International Nuclear Information System (INIS)

Czakon, Michał; Hartland, Nathan P.; Mitov, Alexander; Nocera, Emanuele R.; Rojo, Juan

2017-01-01

Top-quark pair production at the LHC is directly sensitive to the gluon PDF at large x. While total cross-section data is already included in several PDF determinations, differential distributions are not, because the corresponding NNLO calculations have become available only recently. In this work we study the impact on the large-x gluon of top-quark pair differential distributions measured by ATLAS and CMS at √s=8 TeV. Our analysis, performed in the NNPDF3.0 framework at NNLO accuracy, allows us to identify the optimal combination of LHC top-quark pair measurements that maximize the constraints on the gluon, as well as to assess the compatibility between ATLAS and CMS data. We find that differential distributions from top-quark pair production provide significant constraints on the large-x gluon, comparable to those obtained from inclusive jet production data, and thus should become an important ingredient for the next generation of global PDF fits.

The angular ordering in soft-gluon emission

International Nuclear Information System (INIS)

Tesima, K.

1987-01-01

The way to evaluate multi-parton cross-sections systematically is discussed. In the leading-double-log approximation in QCD, the successive emission of soft gluons is at successively smaller angles. The angular ordering, however, is violated in the next-to-leading order

Vitality of optical vortices

CSIR Research Space (South Africa)

Roux, FS

2014-02-01

Full Text Available Optical vortices are always created or annihilated in pairs with opposite topological charges. However, the presence of such a vortex dipole does not directly indicate whether they are associated with a creation or an annihilation event. Here we...

Dilepton as a signature for the baryon-rich quark-gluon matter

International Nuclear Information System (INIS)

Zejun He; Jiaju Zhang

1995-01-01

From the full stopping scenario, we study dilepton production in a baryon rich quark-gluon fireball on the basis of a relativistic hydrodynamic model, and find that with increasing initial baryon density a characteristic valley and a subsequent peak, which more uniquely signal the formation of the baryon-rich quark-gluon matter, appear in the total dilepton yield. Such characteristics can be tested in future experiments at CERN and Brookhaven. (author). Letter-to-the-editor

Gluons from logarithmic slopes of F2 in the NLL approximation

International Nuclear Information System (INIS)

Golec-Biernat, K.

1994-02-01

We make a critical, next-to-leading order, study of the accuracy of the ''Prytz'' relation, which is frequently used to extract the gluon distribution at small x from the logarithmic slopes of the structure function F 2 . We find that the simple relation is not generally valid in the HERA regime, but show that it is a reasonable approximation for gluons which are sufficiency singular at small x. (author). 9 refs, 3 figs

Crosswind Shear Gradient Affect on Wake Vortices

Science.gov (United States)

Proctor, Fred H.; Ahmad, Nashat N.

2011-01-01

Parametric simulations with a Large Eddy Simulation (LES) model are used to explore the influence of crosswind shear on aircraft wake vortices. Previous studies based on field measurements, laboratory experiments, as well as LES, have shown that the vertical gradient of crosswind shear, i.e. the second vertical derivative of the environmental crosswind, can influence wake vortex transport. The presence of nonlinear vertical shear of the crosswind velocity can reduce the descent rate, causing a wake vortex pair to tilt and change in its lateral separation. The LES parametric studies confirm that the vertical gradient of crosswind shear does influence vortex trajectories. The parametric results also show that vortex decay from the effects of shear are complex since the crosswind shear, along with the vertical gradient of crosswind shear, can affect whether the lateral separation between wake vortices is increased or decreased. If the separation is decreased, the vortex linking time is decreased, and a more rapid decay of wake vortex circulation occurs. If the separation is increased, the time to link is increased, and at least one of the vortices of the vortex pair may have a longer life time than in the case without shear. In some cases, the wake vortices may never link.

Use of acoustic vortices in acoustic levitation

DEFF Research Database (Denmark)

Cutanda Henriquez, Vicente; Santillan, Arturo Orozco; Juhl, Peter Møller

2009-01-01

Acoustic fields are known to exert forces on the surfaces of objects. These forces are noticeable if the sound pressure is sufficiently high. Two phenomena where acoustic forces are relevant are: i) acoustic levitation, where strong standing waves can hold small objects at certain positions......, counterbalancing their weight, and ii) acoustic vortices, spinning sound fields that can impinge angular momentum and cause rotation of objects. In this contribution, both force-creating sound fields are studied by means of numerical simulations. The Boundary Element Method is employed to this end. The simulation...... of acoustical vortices uses an efficient numerical implementation based on the superposition of two orthogonal sound fields with a delay of 90° between them. It is shown that acoustic levitation and the use of acoustic vortices can be combined to manipulate objects in an efficient and controlled manner without...

Visible-Frequency Metasurface for Structuring and Spatially Multiplexing Optical Vortices.

Science.gov (United States)

Mehmood, M Q; Mei, Shengtao; Hussain, Sajid; Huang, Kun; Siew, S Y; Zhang, Lei; Zhang, Tianhang; Ling, Xiaohui; Liu, Hong; Teng, Jinghua; Danner, Aaron; Zhang, Shuang; Qiu, Cheng-Wei

2016-04-06

A multifocus optical vortex metalens, with enhanced signal-to-noise ratio, is presented, which focuses three longitudinal vortices with distinct topological charges at different focal planes. The design largely extends the flexibility of tuning the number of vortices and their focal positions for circularly polarized light in a compact device, which provides the convenience for the nanomanipulation of optical vortices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of the gluon polarisation from open charm production at COMPASS

Energy Technology Data Exchange (ETDEWEB)

Koblitz, Susanne

2009-01-27

One of the main goals of the COMPASS experiment at CERN is the determination of the gluon polarisation in the nucleon, {delta}G/G. It is determined from spin asymmetries in the scattering of 160GeV/c polarised muons on a polarised LiD target. The gluon polarisation is accessed by the selection of photon-gluon fusion (PGF) events. The PGF-process can be tagged through hadrons with high transverse momenta or through charmed hadrons in the final state. The advantage of the open charm channel is that, in leading order, the PGF-process is the only process for charm production, thus no physical background contributes to the selected data sample. This thesis presents a measurement of the gluon polarisation left angle {delta}g/g right angle from the COMPASS data taken in the years 2002-2004. In the analysis, charm production is tagged through a reconstructed D{sup 0}-meson decaying in D{sup 0}{yields} K{sup -}{pi}{sup +} (and charge conjugates). The reconstruction is done on a combinatorial basis. The background of wrong track pairs is reduced using kinematic cuts to the reconstructed D{sup 0}-candidate and the information on particle identification from the Ring Imaging Cerenkov counter. In addition, the event sample is separated into D{sup 0}-candidates, where a soft pion from the decay of the D{sup *}-meson to a D{sup 0}-meson, is found, and the D{sup 0}-candidates without this tag. Due to the small mass difference between D{sup *}-meson and D{sup 0}-meson the signal purity of the D{sup *}-tagged sample is about 7 times higher than in the untagged sample. The gluon polarisation left angle {delta}g/g right angle is measured from the event asymmetries for the for the different spin configurations of the COMPASS target. To improve the statistical precision of the final results, the events in the final sample are weighted. The use of a signal and a background weight allows the separation of left angle {delta}g/g right angle, and a possible asymmetry in the combinatorial

Determination of the gluon polarisation from open charm production at COMPASS

International Nuclear Information System (INIS)

Koblitz, Susanne

2009-01-01

One of the main goals of the COMPASS experiment at CERN is the determination of the gluon polarisation in the nucleon, ΔG/G. It is determined from spin asymmetries in the scattering of 160GeV/c polarised muons on a polarised LiD target. The gluon polarisation is accessed by the selection of photon-gluon fusion (PGF) events. The PGF-process can be tagged through hadrons with high transverse momenta or through charmed hadrons in the final state. The advantage of the open charm channel is that, in leading order, the PGF-process is the only process for charm production, thus no physical background contributes to the selected data sample. This thesis presents a measurement of the gluon polarisation left angle Δg/g right angle from the COMPASS data taken in the years 2002-2004. In the analysis, charm production is tagged through a reconstructed D 0 -meson decaying in D 0 → K - π + (and charge conjugates). The reconstruction is done on a combinatorial basis. The background of wrong track pairs is reduced using kinematic cuts to the reconstructed D 0 -candidate and the information on particle identification from the Ring Imaging Cerenkov counter. In addition, the event sample is separated into D 0 -candidates, where a soft pion from the decay of the D * -meson to a D 0 -meson, is found, and the D 0 -candidates without this tag. Due to the small mass difference between D * -meson and D 0 -meson the signal purity of the D * -tagged sample is about 7 times higher than in the untagged sample. The gluon polarisation left angle Δg/g right angle is measured from the event asymmetries for the for the different spin configurations of the COMPASS target. To improve the statistical precision of the final results, the events in the final sample are weighted. The use of a signal and a background weight allows the separation of left angle Δg/g right angle, and a possible asymmetry in the combinatorial background. This method results in an average value of the gluon polarisation

Gluon Polarisation in the Nucleon and Longitudinal Double Spin Asymmetries from Open Charm Muoproduction

CERN Document Server

Alekseev, M; Alexandrov, Yu; Alexeev, G D; Amoroso, A; Austregisilio, A; Badelek, B; Balestra, F; Ball, J; Barth, J; Baum, G; Bedfer, Y; Bernhard, J; Bertini, R; Bettinelli, M; Birsa, R; Bisplinghoff, J; Bordalo, P; Bradamante, F; Bravar, A; Bressan, A; Brona, G; Burtin, E; Bussa, M P; Chapiro, A; Chiosso, M; Chung, S U; Cicuttin, A; Colantoni, M; Crespo, M L; Dalla Torre, S; Dafni, T; Das, S; Dasgupta, S S; Denisov, O.Yu; Dhara, L; Diaz, V; Dinkelbach, A M; Donskov, S V; Doshita, N; Duic, V; Dunnweber, W; Efremov, A; El Alaoui, A; Eversheim, P D; Eyrich, W; Faessler, M; Ferrero, A; Finger, M; Finger, M., jr; Fischer, H; Franco, C; Friedrich, J M; Garfagnini, R; Gautheron, F; Gavrichtchouk, O P; Gazda, R; Gerassimov, S; Geyer, R; Giorgi, M; Gobbo, B; Goertz, S; Grabmuller, S; Grajek, O A; Grasso, A; Grube, B; Gushterski, R; Guskov, A; Haas, F; Hagemann, R; von Harrach, D; Hasegawa, T; Heckmann, J; Heinsius, F H; Hermann, R; Herrmann, F; Hess, C; Hinterberger, F; von Hodenberg, M; Horikawa, N; Hoppner, Ch; d'Hose, N; Ilgner, C; Ishimoto, S; Ivanov, O; Ivanshin, Yu; Iwata, T; Jahn, R; Jasinski, P; Jegou, G; Joosten, R; Kabuss, E; Kafer, W; Kang, D; Ketzer, B; Khaustov, G V; Khokhlov, Yu.A; Kiefer, J; Kisselev, Yu; Klein, F; Klimaszewski, K; Koblitz, S; Koivuniemi, J H; Kolosov, V N; Komissarov, E V; Kondo, K; Konigsmann, Kay; Konorov, I; Konstantinov, V F; Korzenev, A; Kotzinian, A M; Kouznetsov, O; Kowalik, K; Kramer, M; Kral, A; Kroumchtein, Z V; Kuhn, R; Kunne, F; Kurek, K; Le Goff, J M; Lednev, A A; Lehmann, A; Levorato, S; Lichtenstadt, J; Liska, T; Maggiora, A; Maggiora, M; Magnon, A; Mallot, G K; Mann, A; Marchand, C; Marroncle, J; Martin, A; Marzec, J; Massmann, F; Matsuda, T; Maximov, A N; Meyer, W; Michigami, T; Mikhailov, Yu.V; Moinester, M A; Mutter, A; Nagaytsev, A; Nagel, T; Nassalski, J; Negrini, S; Nerling, F; Neubert, S; Neyret, D; Nikolaenko, V I; Olshevsky, A G; Ostrick, M; Padee, A; Panknin, R; Panebianco, S; Panzieri, D; Parsamyan, B; Paul, S; Pawlukiewicz-Kaminska, B; Perevalova, E; Pesaro, G; Peshekhonov, D V; Piragino, G; Platchkov, S; Pochodzalla, J; Polak, J; Polyakov, V A; Pontecorvo, G; Pretz, J; Quintans, C; Rajotte, J.-F; Ramos, S; Rapatsky, V; Reicherz, G; Reggiani, D; Richter, A; Robinet, F; Rocco, E; Rondio, E; Ryabchikov, D I; Samoylenko, V D; Sandacz, A; Santos, H; Sapozhnikov, M G; Sarkar, S; Savin, Igor A; Sbrizza, G; Schiavon, P; Schill, C; Schmitt, L; Schroder, W; Shevchenko, O.Yu; Siebert, H.-W; Silva, L; Sinha, L; Sissakian, A N; Slunecka, M; Smirnov, G I; Sosio, S; Sozzi, F; Srnka, A; Stolarski, M; Sulc, M; Sulej, R; Takekawa, S; Tessaro, S; Tessarotto, F; Teufel, A; Tkatchev, L G; Venugopal, G; Virius, M; Vlassov, N V; Vossen, A; Weitzel, Q; Wenzl, K; Windmolders, R; Wislicki, W; Wollny, H; Zaremba, K; Zavertyaev, M; Zemlyanichkina, E; Ziembicki, M; Zhao, J; Zhuravlev, N; Zvyagin, A

2009-01-01

The gluon polarisation in the nucleon has been determined by detecting charm production via D0 meson decay to charged K and pi in polarised muon scattering off a longitudinally polarised deuteron target. The data were taken by the COMPASS Collaboration at CERN between 2002 and 2006 and corresponds to an integrated luminosity of 2.8 fb^-1. The dominant underlying process of charm production is the photon-gluon fusion to a cc-bar pair. A leading order QCD approach gives an average gluon polarisation of (Delta g/g)_x= -0.49 +- 0.27(stat) +- 0.11(syst) at a scale mu^2 ~ 13 (GeV/c)^2 and at an average gluon momentum fraction (x) ~ 0.11. The longitudinal cross-section asymmetry for D0 production is presented in bins of the transverse momentum and the energy of the D0 meson.

Soft gluon resummation for gluon-induced Higgs Strahlung

Energy Technology Data Exchange (ETDEWEB)

Harlander, Robert; Zirke, Tom [Fachbereich C, Bergische Universitaet Wuppertal (Germany); Kulesza, Anna; Theeuwes, Vincent [Institute for Theoretical Physics, WWU Muenster (Germany)

2015-07-01

We study the effect of soft gluon emission on the total cross section predictions for the gg → HZ associated Higgs production process at the LHC. To this end, we perform resummation of threshold corrections at the NLL accuracy in the absolute threshold production limit and in the threshold limit for production of a ZH system with a given invariant mass. Analytical results and numerical predictions for various possible LHC collision energies are presented. The perturbative stability of the results is verified by including universal NNLL effects. We find that resummation significantly reduces the scale uncertainty of the gg → HZ contribution, which is the dominant source of perturbative uncertainty to ZH production. We use our results to evaluate updated numbers for the total inclusive cross section of associated pp → ZH production at the LHC. The reduced scale uncertainty of the gg → HZ component translates into a decrease of the overall scale error by about a factor of two.

Fluctuation spectroscopy: From Rayleigh-Jeans waves to Abrikosov vortex clusters

Science.gov (United States)

Varlamov, A. A.; Galda, A.; Glatz, A.

2018-01-01

critical temperature and quantum fluctuations at zero temperature in the vicinity of the second critical field. The analysis of the latter allows us to present fluctuation formation as a fragmentation of the Abrikosov lattice. This review highlights a series of experimental findings followed by microscopic description and numerical analysis of the effects of fluctuations on numerous properties of superconductors in the entire phase diagram and beyond the superconducting phase.

Inclusive gluon production in the QCD Reggeon field theory: Pomeron loops included

International Nuclear Information System (INIS)

Altinoluk, Tolga; Kovner, Alex; Lublinsky, Michael

2009-01-01

We continue the study of hadronic scattering amplitudes at high energy by systematically including nonlinear effects of finite partonic density in hadronic wave function as well as the effects of multiple rescatterings in the scattering process. In this paper we derive expressions for a single inclusive gluon production amplitude and multigluon inclusive production amplitudes when the rapidities of all observed gluons are not very different. We show that at leading order these observables exhibit a semiclassical structure. Beyond the semiclassical result, we find that the gluon emission has some characteristic features different from the JIMWLK and KLWMIJ limits in that the gluons are not emitted independently in rapidity space, but have a correlated component with correlation length (in rapidity space) of order one. We demonstrate the consistency between this feature of the multigluon observables and the Hamiltonian of the QCD Reggeon Field Theory (H RFT ) derived in the companion paper [1]. We also show that the evolution of these observables with total rapidity of the process is generated by H RFT of [1]. We discuss whether this evolution is equivalent to evolution with H JIMWLK as far as this set of observables is concerned.

Magnetic monopoles, center vortices, confinement and topology of gauge fields

International Nuclear Information System (INIS)

Reinhardt, H.; Engelhardt, M.; Langfeld, K.; Quandt, M.; Schaefke, A.

2000-01-01

The vortex picture of confinement is studied. The deconfinement phase transition is explained as a transition from a phase in which vortices percolate to a phase of small vortices. Lattice results are presented in support of this scenario. Furthermore the topological properties of magnetic monopoles and center vortices arising, respectively, in Abelian and center gauges are studied in continuum Yang-Mills-theory. For this purpose the continuum analog of the maximum center gauge is constructed

Magnetic Monopoles, Center Vortices, Confinement and Topology of Gauge Fields

OpenAIRE

Reinhardt, H.; Engelhardt, M.; Langfeld, K.; Quandt, M.; Sch"afke, A.

1999-01-01

The vortex picture of confinement is studied. The deconfinement phase transition is explained as a transition from a phase in which vortices percolate to a phase of small vortices. Lattice results are presented in support of this scenario. Furthermore the topological properties of magnetic monopoles and center vortices arising, respectively, in Abelian and center gauges are studied in continuum Yang-Mills-theory. For this purpose the continuum analog of the maximum center gauge is constructed.

Bound-state quark and gluon contributions to structure functions in QCD

International Nuclear Information System (INIS)

Brodsky, S.J.

1991-01-01

One can distinguish two types of contributions to the quark and gluon structure functions of hadrons in quantum chromodynamics: 'intrinsic' contributions, which are due to the direct scattering on the bound-state constituents, and 'extrinsic' contributions, which are derived from particles created in the collision. In this talk, I discuss several aspects of deep inealstic structure functions in which the bound-state structure of the proton plays a crucial role: (1) the properties of the intrinsic gluon distribution associated with the proton bound-state wavefunction; (2) the separation of the quark structure function of the proton into intrinsic 'bound-valence' and extrinsic 'non-valence' components which takes into account the Pauli principle; (3) the properties and identification of intrinsic heavy quark structure functions; and (4) a theory of shadowing and anti-shadowing of nuclear structure functions, directly related to quark-nucleon interactions and the gluon saturation phenomenon. (orig.)

A T-matrix calculation for in-medium heavy-quark gluon scattering

International Nuclear Information System (INIS)

Huggins, K.; Rapp, R.

2012-01-01

The interactions of charm and bottom quarks in a quark-gluon plasma (QGP) are evaluated using a thermodynamic 2-body T-matrix. We specifically focus on heavy-quark (HQ) interactions with thermal gluons with an input potential motivated by lattice-QCD computations of the HQ free energy. The latter is implemented into a field-theoretic ansatz for color-Coulomb and (remnants of) confining interactions. This, in particular, enables to discuss corrections to the potential approach, specifically hard-thermal-loop corrections to the vertices, relativistic corrections deduced from pertinent Feynman diagrams, and a suitable projection on transverse thermal gluons. The resulting potentials are applied to compute scattering amplitudes in different color channels and utilized for a calculation of the corresponding HQ drag coefficient in the QGP. A factor of ∼2-3 enhancement over perturbative results is obtained, mainly driven by the resummation in the attractive color-channels.

Bound-state quark and gluon contributions to structure functions in QCD

International Nuclear Information System (INIS)

Brodsky, S.J.

1990-08-01

One can distinguish two types of contributions to the quark and gluon structure functions of hadrons in quantum chromodynamics: ''intrinsic'' contributions, which are due to the direct scattering on the bound-state constituents, and ''extrinsic'' contributions, which are derived from particles created in the collision. In this talk, I discussed several aspects of deep inelastic structure functions in which the bound-state structure of the proton plays a crucial role: the properties of the intrinsic gluon distribution associated with the proton bound-state wavefunction; the separation of the quark structure function of the proton onto intrinsic ''bound-valence'' and extrinsic ''non-valence'' components which takes into account the Pauli principle; the properties and identification of intrinsic heavy quark structure functions; and a theory of shadowing and anti-shadowing of nuclear structure functions, directly related to quark-nucleon interactions and the gluon saturation phenomenon. 49 refs., 5 figs

Infrared behavior of gluons and ghosts in ghost-antighost symmetric gauges

International Nuclear Information System (INIS)

Alkofer, R.; Fischer, C.S.; Reinhardt, H.; Smekal, L. von

2003-01-01

To investigate the possibility of a ghost-antighost condensate, the coupled Dyson-Schwinger equations for the gluon and ghost propagators in Yang-Mills theories are derived in general covariant gauges, including ghost-antighost symmetric gauges. The infrared behavior of these two-point functions is studied in a bare-vertex truncation scheme which has proven to be successful in the Landau gauge. In all linear covariant gauges the same infrared behavior as in the Landau gauge is found: The gluon propagator is infrared-suppressed whereas the ghost propagator is infrared-enhanced. This infrared singular behavior provides an indication against a ghost-antighost condensate. In the ghost-antighost symmetric gauges we find that the infrared behavior of the gluon and ghost propagators cannot be determined when replacing all dressed vertices by bare ones. The question of a BRS invariant dimension-2 condensate remains to be further studied

A stress field in the vortex lattice in the type-II superconductor

Directory of Open Access Journals (Sweden)

Maruszewski, Bogdan

2008-02-01

Full Text Available Magnetic flux can penetrate a type-II superconductor in the form of Abrikosov vortices (also called flux lines, flux tubes, or fluxons, each carrying a quantum of magnetic flux. These tiny vortices of supercurrent tend to arrange themselves in a triangular and/or quadratic flux-line lattice, which is more or less perturbed by material inhomogeneities that pin the flux lines. Pinning is caused by imperfections of the crystal lattice, such as dislocations, point defects, grain boundaries, etc. Hence, a honeycomb-like pattern of the vortex array presents some mechanical properties. If the Lorentz force of interactions between the vortices is much bigger than the pinning force, the vortex lattice behaves elastically. So we assume that the pinning force is negligible in the sequel and we deal with soft vortices. The vortex motion in the vortex lattice and/or creep of the vortices in the vortex fluid is accompanied by energy dissipation. Hence, except for the elastic properties, the vortex field is also of a viscous character. The main aim of the paper is a formulation of a thermoviscoelastic stress - strain constitutive law consisted of coexistence of the ordered and disordered states of the vortex field. Its form describes an auxetic-like thermomechanical (anomalous property of the vortex field.

Muoproduction of J/ψ-mesons and the gluon distribution in nucleons

International Nuclear Information System (INIS)

Jong, Maarten de.

1991-01-01

The cross sections for production of J/ψ-mesons in muon-scattering at hydrogen and deuterium have been measured at a muon-energy of 280 GeV in order to extract from these the momentum distribution of gluons in the nucleon. These cross sections turned out to be equal for protons and neutrons within the experimental error. In the framework of the colour singlet model the gluon distribution has been determined from the cross section for the inelastic production of J/ψ mesons. At small gluon impulses the distribution obtained resembles a brems-strahlung spectrum. This distribution decreases, according to a simple description (counting rules) at larger impulses. The same model however underestimates the cross section for elastic production of J/ψ-mesons seriously. It is found that in inelastic production of J/ψ-mesons both helicities of the meson occur equally. Also a correlation has been observed between the scattering plane and the plane in which the J/ψ meson decays. The production of J/ψ-mesons and ψ'-mesons has been investigated in muon scattering at concrete at the same incoming energy. The measured ratio of their cross sections agrees with the colour singlet model but disagrees with the simplified description which characterizes the 'photon-gluon fusion model'. The possible nuclear-mass dependence of the cross section for J/ψ-meson production has been investigated in interactions of muons with tin and carbon at an energy of 280 GeV. This possible dependence turns out to be absent which means that on the basis of the colour singlet model the distributions of the gluons in the nucleon are equal in tin and carbon. (author). 103 refs.; 60 figs.; 19 tabs

Two-Loop Gluon to Gluon-Gluon Splitting Amplitudes in QCD

International Nuclear Information System (INIS)

Bern, Z.

2004-01-01

Splitting amplitudes are universal functions governing the collinear behavior of scattering amplitudes for massless particles. We compute the two-loop g → gg splitting amplitudes in QCD, N = 1, and N = 4 super-Yang-Mills theories, which describe the limits of two-loop n-point amplitudes where two gluon momenta become parallel. They also represent an ingredient in a direct x-space computation of DGLAP evolution kernels at next-to-next-to-leading order. To obtain the splitting amplitudes, we use the unitarity sewing method. In contrast to the usual light-cone gauge treatment, our calculation does not rely on the principal-value or Mandelstam-Leibbrandt prescriptions, even though the loop integrals contain some of the denominators typically encountered in light-cone gauge. We reduce the integrals to a set of 13 master integrals using integration-by-parts and Lorentz invariance identities. The master integrals are computed with the aid of differential equations in the splitting momentum fraction z. The ε-poles of the splitting amplitudes are consistent with a formula due to Catani for the infrared singularities of two-loop scattering amplitudes. This consistency essentially provides an inductive proof of Catani's formula, as well as an ansatz for previously-unknown 1/ε pole terms having non-trivial color structure. Finite terms in the splitting amplitudes determine the collinear behavior of finite remainders in this formula

Theory of Concentrated Vortices

DEFF Research Database (Denmark)

Alekseenko, Sergey; Kuibin, Pavel; Okulov, Valery

This book presents comprehensive and authoritative coverage of the wide field of concentrated vortices observed in nature and technique. The methods for research of their kinematics and dynamics are considered. Special attention is paid to the flows with helical symmetry. The authors have describ...

Experimental studies of unbiased gluon jets from $e^{+}e^{-}$ annihilations using the jet boost algorithm

CERN Document Server

Abbiendi, G.; Akesson, P.F.; Alexander, G.; Allison, John; Amaral, P.; Anagnostou, G.; Anderson, K.J.; Arcelli, S.; Asai, S.; Axen, D.; Azuelos, G.; Bailey, I.; Barberio, E.; Barlow, R.J.; Batley, R.J.; Bechtle, P.; Behnke, T.; Bell, Kenneth Watson; Bell, P.J.; Bella, G.; Bellerive, A.; Benelli, G.; Bethke, S.; Biebel, O.; Boeriu, O.; Bock, P.; Boutemeur, M.; Braibant, S.; Brigliadori, L.; Brown, Robert M.; Buesser, K.; Burckhart, H.J.; Campana, S.; Carnegie, R.K.; Caron, B.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Csilling, A.; Cuffiani, M.; Dado, S.; De Roeck, A.; De Wolf, E.A.; Desch, K.; Dienes, B.; Donkers, M.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Etzion, E.; Fabbri, F.; Feld, L.; Ferrari, P.; Fiedler, F.; Fleck, I.; Ford, M.; Frey, A.; Furtjes, A.; Gagnon, P.; Gary, John William; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Giunta, Marina; Goldberg, J.; Gross, E.; Grunhaus, J.; Gruwe, M.; Gunther, P.O.; Gupta, A.; Hajdu, C.; Hamann, M.; Hanson, G.G.; Harder, K.; Harel, A.; Harin-Dirac, M.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Hensel, C.; Herten, G.; Heuer, R.D.; Hill, J.C.; Hoffman, Kara Dion; Horvath, D.; Igo-Kemenes, P.; Ishii, K.; Jeremie, H.; Jovanovic, P.; Junk, T.R.; Kanaya, N.; Kanzaki, J.; Karapetian, G.; Karlen, D.; Kawagoe, K.; Kawamoto, T.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kim, D.H.; Klein, K.; Klier, A.; Kluth, S.; Kobayashi, T.; Kobel, M.; Komamiya, S.; Kormos, Laura L.; Kramer, T.; Krieger, P.; von Krogh, J.; Kruger, K.; Kuhl, T.; Kupper, M.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Layter, J.G.; Leins, A.; Lellouch, D.; Letts, J.; Levinson, L.; Lillich, J.; Lloyd, S.L.; Loebinger, F.K.; Lu, J.; Ludwig, J.; Macpherson, A.; Mader, W.; Marcellini, S.; Martin, A.J.; Masetti, G.; Mashimo, T.; Mattig, Peter; McDonald, W.J.; McKenna, J.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Menges, W.; Merritt, F.S.; Mes, H.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Moed, S.; Mohr, W.; Mori, T.; Mutter, A.; Nagai, K.; Nakamura, I.; Nanjo, H.; Neal, H.A.; Nisius, R.; O'Neale, S.W.; Oh, A.; Okpara, A.; Oreglia, M.J.; Orito, S.; Pahl, C.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poli, B.; Polok, J.; Pooth, O.; Przybycien, M.; Quadt, A.; Rabbertz, K.; Rembser, C.; Renkel, P.; Rick, H.; Roney, J.M.; Rosati, S.; Rozen, Y.; Runge, K.; Sachs, K.; Saeki, T.; Sarkisyan, E.K.G.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schieck, J.; Schoerner-Sadenius, Thomas; Schroder, Matthias; Schumacher, M.; Schwick, C.; Scott, W.G.; Seuster, R.; Shears, T.G.; Shen, B.C.; Sherwood, P.; Siroli, G.; Skuja, A.; Smith, A.M.; Sobie, R.; Soldner-Rembold, S.; Spano, F.; Stahl, A.; Stephens, K.; Strom, David M.; Strohmer, R.; Tarem, S.; Tasevsky, M.; Taylor, R.J.; Teuscher, R.; Thomson, M.A.; Torrence, E.; Toya, D.; Tran, P.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turner-Watson, M.F.; Ueda, I.; Ujvari, B.; Vollmer, C.F.; Vannerem, P.; Vertesi, R.; Verzocchi, M.; Voss, H.; Vossebeld, J.; Waller, D.; Ward, C.P.; Ward, D.R.; Warsinsky, M.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wengler, T.; Wermes, N.; Wetterling, D.; Wilson, G.W.; Wilson, J.A.; Wolf, G.; Wyatt, T.R.; Yamashita, S.; Zer-Zion, D.; Zivkovic, Lidija

2004-01-01

We present the first experimental results based on the jet boost algorithm, a technique to select unbiased samples of gluon jets in e+e- annihilations, i.e. gluon jets free of biases introduced by event selection or jet finding criteria. Our results are derived from hadronic Z0 decays observed with the OPAL detector at the LEP e+e- collider at CERN. First, we test the boost algorithm through studies with Herwig Monte Carlo events and find that it provides accurate measurements of the charged particle multiplicity distributions of unbiased gluon jets for jet energies larger than about 5 GeV, and of the jet particle energy spectra (fragmentation functions) for jet energies larger than about 14 GeV. Second, we apply the boost algorithm to our data to derive unbiased measurements of the gluon jet multiplicity distribution for energies between about 5 and 18 GeV, and of the gluon jet fragmentation function at 14 and 18 GeV. In conjunction with our earlier results at 40 GeV, we then test QCD calculations for the en...

Bosonization with inclusion of the gluon condensate

International Nuclear Information System (INIS)

Ebert, D.; Volkov, M.K.

1994-01-01

The effects of the gluon condensate on the quark condensate and on masses and coupling constants of composite mesons are discussed within a QCD-motivated Nambu-Jona-Lasinio model for zero temperature as well as for the case of finite temperature and baryon number density. (orig.)

Screening in an expanding quark-gluon plasma

International Nuclear Information System (INIS)

Broniowski, W.

1988-12-01

Effects of expansion on the Debye length in quark-gluon plasma are calculated in an abelian, boost invariant model. It is found that for early times the screening is significantly more efficient than what follows from naive static considerations. 11 refs., 1 fig., 1 tab. (author)

Higgs production in gluon fusion beyond NNLO

Energy Technology Data Exchange (ETDEWEB)

Ball, Richard D. [Edinburgh Univ. (United Kingdom). Tait Inst.; Bonvini, Marco [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Forte, Stefano [Milano Univ. (Italy). Dipt. di Fisica; INFN, Sezione di Milano (Italy); Marzani, Simone [Durham Univ. (United Kingdom). Inst. for Particle Physics Phenomenology; Ridolfi, Giovanni [Genova Univ. (Italy). Dipt. di Fisica; INFN, Sezione di Genova (Italy)

2013-03-15

We construct an approximate expression for the cross section for Higgs production in gluon fusion at next-to-next-to-next-to-leading order (N{sup 3}LO) in {alpha}{sub s} with finite top mass. We argue that an accurate approximation can be constructed by exploiting the analiticity of the Mellin space cross section, and the information on its singularity structure coming from large N (soft gluon, Sudakov) and small N (high energy, BFKL) all order resummation. We support our argument with an explicit comparison of the approximate and the exact expressions up to the highest (NNLO) order at which the latter are available. We find that the approximate N{sup 3}LO result amounts to a correction of 17% to the NNLO QCD cross section for production of a 125 GeV Higgs at the LHC (8 TeV), larger than previously estimated, and it significantly reduces the scale dependence of the NNLO result.

Higgs production in gluon fusion beyond NNLO

International Nuclear Information System (INIS)

Ball, Richard D.; Bonvini, Marco; Forte, Stefano; Marzani, Simone; Ridolfi, Giovanni

2013-01-01

We construct an approximate expression for the cross section for Higgs production in gluon fusion at next-to-next-to-next-to-leading order (N 3 LO) in α s with finite top mass. We argue that an accurate approximation can be constructed by exploiting the analyticity of the Mellin space cross section, and the information on its singularity structure coming from large N (soft gluon, Sudakov) and small N (high energy, BFKL) all order resummation. We support our argument with an explicit comparison of the approximate and the exact expressions up to the highest (NNLO) order at which the latter are available. We find that the approximate N 3 LO result amounts to a correction of 17% to the NNLO QCD cross section for production of a 125 GeV Higgs at the LHC (8 TeV), larger than previously estimated, and it significantly reduces the scale dependence of the NNLO result

Higgs production in gluon fusion beyond NNLO

Energy Technology Data Exchange (ETDEWEB)

Ball, Richard D. [Tait Institute, University of Edinburgh, Edinburgh EH9 3JZ, Scotland (United Kingdom); Bonvini, Marco [Deutsches Elektronen-Synchroton, DESY, Notkestraße 85, D-22603 Hamburg (Germany); Forte, Stefano, E-mail: forte@mi.infn.it [Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy); Marzani, Simone [Institute for Particle Physics Phenomenology, Durham University, Durham DH1 3LE, England (United Kingdom); Ridolfi, Giovanni [Dipartimento di Fisica, Università di Genova and INFN, Sezione di Genova, Via Dodecaneso 33, I-16146 Genova (Italy)

2013-09-21

We construct an approximate expression for the cross section for Higgs production in gluon fusion at next-to-next-to-next-to-leading order (N{sup 3}LO) in α{sub s} with finite top mass. We argue that an accurate approximation can be constructed by exploiting the analyticity of the Mellin space cross section, and the information on its singularity structure coming from large N (soft gluon, Sudakov) and small N (high energy, BFKL) all order resummation. We support our argument with an explicit comparison of the approximate and the exact expressions up to the highest (NNLO) order at which the latter are available. We find that the approximate N{sup 3}LO result amounts to a correction of 17% to the NNLO QCD cross section for production of a 125 GeV Higgs at the LHC (8 TeV), larger than previously estimated, and it significantly reduces the scale dependence of the NNLO result.

Higgs production in gluon fusion beyond NNLO

International Nuclear Information System (INIS)

Ball, Richard D.; Forte, Stefano; Marzani, Simone

2013-03-01

We construct an approximate expression for the cross section for Higgs production in gluon fusion at next-to-next-to-next-to-leading order (N 3 LO) in α s with finite top mass. We argue that an accurate approximation can be constructed by exploiting the analiticity of the Mellin space cross section, and the information on its singularity structure coming from large N (soft gluon, Sudakov) and small N (high energy, BFKL) all order resummation. We support our argument with an explicit comparison of the approximate and the exact expressions up to the highest (NNLO) order at which the latter are available. We find that the approximate N 3 LO result amounts to a correction of 17% to the NNLO QCD cross section for production of a 125 GeV Higgs at the LHC (8 TeV), larger than previously estimated, and it significantly reduces the scale dependence of the NNLO result.

Sharp vorticity gradients in two-dimensional turbulence and the energy spectrum

DEFF Research Database (Denmark)

Kuznetsov, E.A.; Naulin, Volker; Nielsen, Anders Henry

2010-01-01

Formation of sharp vorticity gradients in two-dimensional (2D) hydrodynamic turbulence and their influence on the turbulent spectra are considered. The analog of the vortex line representation as a transformation to the curvilinear system of coordinates moving together with the di-vorticity lines...... is developed and compressibility of this mapping appears as the main reason for the formation of the sharp vorticity gradients at high Reynolds numbers. In the case of strong anisotropy the sharp vorticity gradients can generate spectra which fall off as k −3 at large k, which appear to take the same form...

Parallel magnetic field suppresses dissipation in superconducting nanostrips

Energy Technology Data Exchange (ETDEWEB)

Wang, Yong-Lei; Glatz, Andreas; Kimmel, Gregory J.; Aranson, Igor S.; Thoutam, Laxman R.; Xiao, Zhi-Li; Berdiyorov, Golibjon R.; Peeters, François M.; Crabtree, George W.; Kwok, Wai-Kwong

2017-11-13

The motion of Abrikosov vortices in type-II superconductors results in a finite resistance in the presence of an applied electric current. Elimination or reduction of the resistance via immobilization of vortices is the "holy grail" of superconductivity research. Common wisdom dictates that an increase in the magnetic field escalates the loss of energy since the number of vortices increases. Here we show that this is no longer true if the magnetic field and the current are applied parallel to each other. Our experimental studies on the resistive behavior of a superconducting Mo0.79Ge0.21 nanostrip reveal the emergence of a dissipative state with increasing magnetic field, followed by a pronounced resistance drop, signifying a reentrance to the superconducting state. Large-scale simulations of the 3D time-dependent Ginzburg-Landau model indicate that the intermediate resistive state is due to an unwinding of twisted vortices. When the magnetic field increases, this instability is suppressed due to a better accommodation of the vortex lattice to the pinning configuration. Our findings show that magnetic field and geometrical confinement can suppress the dissipation induced by vortex motion and thus radically improve the performance of superconducting materials.

Parallel magnetic field suppresses dissipation in superconducting nanostrips.

Science.gov (United States)

Wang, Yong-Lei; Glatz, Andreas; Kimmel, Gregory J; Aranson, Igor S; Thoutam, Laxman R; Xiao, Zhi-Li; Berdiyorov, Golibjon R; Peeters, François M; Crabtree, George W; Kwok, Wai-Kwong

2017-11-28

The motion of Abrikosov vortices in type-II superconductors results in a finite resistance in the presence of an applied electric current. Elimination or reduction of the resistance via immobilization of vortices is the "holy grail" of superconductivity research. Common wisdom dictates that an increase in the magnetic field escalates the loss of energy since the number of vortices increases. Here we show that this is no longer true if the magnetic field and the current are applied parallel to each other. Our experimental studies on the resistive behavior of a superconducting Mo 0.79 Ge 0.21 nanostrip reveal the emergence of a dissipative state with increasing magnetic field, followed by a pronounced resistance drop, signifying a reentrance to the superconducting state. Large-scale simulations of the 3D time-dependent Ginzburg-Landau model indicate that the intermediate resistive state is due to an unwinding of twisted vortices. When the magnetic field increases, this instability is suppressed due to a better accommodation of the vortex lattice to the pinning configuration. Our findings show that magnetic field and geometrical confinement can suppress the dissipation induced by vortex motion and thus radically improve the performance of superconducting materials.

Decay or collapse: Aircraft wake vortices in grid turbulence

NARCIS (Netherlands)

Ren, M.; Elsenaar, A.; van Heijst, G.J.F.; Kuczaj, Arkadiusz K.; Geurts, Bernardus J.

2006-01-01

Trailing vortices are naturally shed by airplanes and they typically evolve into a counter-rotating vortex pair. Downstream of the aircraft, these vortices can persist for a very long time and extend for several kilometers. This poses a potential hazard to following aircraft, particularly during

Influence of artificial tip perturbation on asymmetric vortices flow over a chined fuselage

Directory of Open Access Journals (Sweden)

Shi Wei

2015-08-01

Full Text Available An experimental study was conducted with the aim of understanding behavior of asymmetric vortices flow over a chined fuselage. The tests were carried out in a wind tunnel at Reynolds number of 1.87 × 105 under the conditions of high angles of attack and zero angle of sideslip. The results show that leeward vortices flow becomes asymmetric vortices flow when angle of attack increases over 20°. The asymmetric vortices flow is asymmetry of two forebody vortices owing to the increase of angle of attack but not asymmetry of vortex breakdown which appears when angle of attack is above 35°. Asymmetric vortices flow is sensitive to tip perturbation and is non-deterministic due to randomly distributed natural minute geometrical irregularities on the nose tip within machining tolerance. Deterministic asymmetric vortices flow can be obtained by attaching artificial tip perturbation which can trigger asymmetric vortices flow and decide asymmetric vortices flow pattern. Triggered by artificial tip perturbation, the vortex on the same side with perturbation is in a higher position, and the other vortex on the opposite side is in a lower position. Vortex suction on the lower vortex side is larger, which corresponds to a side force pointing to the lower vortex side.

On hairpin vortices in a transitional boundary layer

Directory of Open Access Journals (Sweden)

Uruba Václav

2012-04-01

Full Text Available In the presented paper the results of experiments on transitional boundary layer are presented. The boundary layer was generated on smooth flat wall with zero pressure gradient forming one side of the channel of rectangular cross section. The hairpin vortices, packets of hairpin vortices, turbulent spots and calmed regions were experimentally investigated using time-resolved PIV technique.

Dynamical gluon masses in perturbative calculations at the loop level

International Nuclear Information System (INIS)

Machado, Fatima A.; Natale, Adriano A.

2013-01-01

Full text: In the phenomenology of strong interactions one always has to deal at some extent with the interplay between perturbative and non-perturbative QCD. On one hand, the former has quite developed tools, yielded by asymptotic freedom. On the other, concerning the latter, we nowadays envisage the following scenario: 1) There are strong evidences for a dynamically massive gluon propagator and infrared finite coupling constant; 2) There is an extensive and successful use of an infrared finite coupling constant in phenomenological calculations at tree level; 3) The infrared finite coupling improves the perturbative series convergence; 4) The dynamical gluon mass provides a natural infrared cutoff in the physical processes at the tree level. Considering this scenario it is natural to ask how these non-perturbative results can be used in perturbative calculations of physical observables at the loop level. Recent papers discuss how off-shell gauge and renormalization group invariant Green functions can be computed with the use of the Pinch Technique (PT), with IR divergences removed by the dynamical gluon mass, and using a well defined effective charge. In this work we improve the former results by the authors, which evaluate 1-loop corrections to some two- and three-point functions of SU(3) pure Yang-Mills, investigating the dressing of quantities that could account for an extension of loop calculations to the infrared domain of the theory, in a way applicable to phenomenological calculations. One of these improvements is maintaining the gluon propagator transverse in such a scheme. (author)

Baryonic decay of the J/psi and gluon spin

International Nuclear Information System (INIS)

Pallin, D.

1985-04-01

A study of the J/psi state of the charmomium (c antic state) was performed at the D.C.I. collider in Orsay with the DM2 detector. 9 millions of J/psi have been produced, corresponding to more than one half of the actual world statistics. The very simple mecanism of the e +- annihilation into baryon-antibaryon via the J/psi state, allows measurements of the gluon spin through the emitted baryon angular distribution. The analyse of the channels J/psi → p antip and Λ antiΛ, permits to obtain parameters for the angular distributions. These experimental values favour very clearly a vectorial gluon hypothesis, as postulated by the quantum Chromodynamics [fr

Hard wall - soft wall - vorticity scattering in shear flow

NARCIS (Netherlands)

Rienstra, S.W.; Singh, D.K.

2014-01-01

An analytically exact solution, for the problem of lowMach number incident vorticity scattering at a hard-soft wall transition, is obtained in the form of Fourier integrals by using theWiener-Hopf method. Harmonic vortical perturbations of inviscid linear shear flow are scattered at the wall

Hard wall - soft wall - vorticity scattering in shear flow

NARCIS (Netherlands)

Rienstra, S.W.; Singh, D.K.

2014-01-01

An analytically exact solution, for the problem of low Mach number incident vorticity scattering at a hard-soft wall transition, is obtained in the form of Fourier integrals by using the Wiener-Hopf method. Harmonic vortical perturbations of inviscid linear shear flow are scattered at the wall

NLO QCD result for the gluon polarization from open charm $D^{0}$ meson production at COMPASS

CERN Document Server

Kurek, Krzysztof

2011-01-01

One of the main goals of the COMPASS experiment is the measurement of the gluon contribution to the nucleon spin. Among the processes studied by COMPASS, open- charm $D^{0}$ meson production seems to be the cleanest channel for probing gluons in the energy range covered by the experiment. The gluon polarisation is related to the measured asymmetry for charmed mesons production via the analyzing power (asymmetry at the partonic level) calculated in the perturbative QCD frame. The analyzing power for the "photon-gluon fusion" process corresponds to a LO QCD approximation. The signicant improvement of the statistical precision and the new, nal LO result are presented . The NLO QCD corrections to the partonic cross sections (unpolarised and polarized ones) are now also included into the analysis scheme since these higher order contributions are not negligible. The preliminary NLO QCD result on the gluon polarisation based on a set of measured $D^{0}$ meson asymmetries in kinematical bins of the $D^{0}$ energy amd...

LONG-TERM EVOLUTION OF PLANET-INDUCED VORTICES IN PROTOPLANETARY DISKS

International Nuclear Information System (INIS)

Fu, Wen; Li, Hui; Li, Shengtai; Lubow, Stephen

2014-01-01

Recent observations of large-scale asymmetric features in protoplanetary disks suggest that large-scale vortices exist in such disks. Massive planets are known to be able to produce deep gaps in protoplanetary disks. The gap edges could become hydrodynamically unstable to the Rossby wave/vortex instability and form large-scale vortices. In this study we examine the long-term evolution of these vortices by carrying out high-resolution two-dimensional hydrodynamic simulations that last more than 10 4 orbits (measured at the planet's orbit). We find that the disk viscosity has a strong influence on both the emergence and lifetime of vortices. In the outer disk region where asymmetric features are observed, our simulation results suggest that the disk viscous α needs to be low, ∼10 –5 -10 –4 , to sustain vortices to thousands and up to 10 4 orbits in certain cases. The chance of finding a vortex feature in a disk then decreases with smaller planet orbital radius. For α ∼ 10 –3 or larger, even planets with masses of 5 M J will have difficulty either producing or sustaining vortices. We have also studied the effects of different disk temperatures and planet masses. We discuss the implications of our findings on current and future protoplanetary disk observations

Evidence for a spin 1 gluon in three jet events

International Nuclear Information System (INIS)

Brandelik, R.; Braunschweig, W.; Gather, K.; Kadansky, V.; Kirschfink, F.J.; Luebelsmeyer, K.; Martyn, H.U.; Peise, G.; Rimkus, J.; Sander, H.G.

1980-08-01

High energy e + e - annihilation events obtained in the TASSO detector at PETRA have been used to determine the spin of the gluon in the reaction e + e - → q anti qg. We analyzed angular correlations between the 3 jet axes. While vector gluons are consistent with the data (55% confidence limit), scalar fluons are disfavored by 3.8 standard deviations, corresponding to a confidence level of about 10 -4 . Our conclusion is free of possible biases due to uncertainties in the fragmentation process or in determining the q anti qg kinematic from the observed hadrons. (orig.)

Jet-Tagged Back-Scattering Photons for Quark Gluon Plasma Tomography

Energy Technology Data Exchange (ETDEWEB)

Fries, Rainer J. [Cyclotron Institute and Department of Physics and Astronomy, Texas A and M University, College Station, TX 77845 (United States); De, Somnath; Srivastava, Dinesh K. [Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata – 700064 (India)

2013-05-02

Direct photons are important probes for quark gluon plasma created in high energy nuclear collisions. Various sources of direct photons in nuclear collisions are known, each of them endowed with characteristic information about the production process. However, it has been challenging to separate direct photon sources through measurements of single inclusive photon spectra and photon azimuthal asymmetry. Here we explore a method to identify photons created from the back-scattering of high momentum quarks off quark gluon plasma. We show that the correlation of back-scattering photons with a trigger jet leads to a signal that should be measurable at RHIC and LHC.

Experimental status of the search for the quark-gluon plasma in ultra-relativistic heavy ion interactions

International Nuclear Information System (INIS)

Salmeron, R.A.

1992-01-01

The deconfinement of quarks, antiquarks and gluons, and the phase transition from a hadron phase to a quark-gluon plasma phase are presented after recalling some elementary notions about normal nuclear matter. Eight proposed signatures of the quark-gluon plasma are described and a summary is given of the experiments concerning three of them: Bose-Einstein interference, the suppression of the J/ψ production and strange particles production. (author)

Vortices in a rotating dark matter condensate

International Nuclear Information System (INIS)

Yu, Rotha P; Morgan, Michael J

2002-01-01

We examine vortices in a self-gravitating dark matter Bose-Einstein condensate (BEC), consisting of ultra-low mass scalar bosons that arise during a late-time cosmological phase transition. Rotation of the dark matter BEC imprints a background phase gradient on the condensate, which establishes a harmonic trap potential for vortices. A numerical simulation of vortex dynamics shows that the vortex number density, n v ∝ r -1 , resulting in a flat velocity profile for the dark matter condensate. (letter to the editor)

Inward propagating chemical waves in Taylor vortices.

Science.gov (United States)

Thompson, Barnaby W; Novak, Jan; Wilson, Mark C T; Britton, Melanie M; Taylor, Annette F

2010-04-01

Advection-reaction-diffusion (ARD) waves in the Belousov-Zhabotinsky reaction in steady Taylor-Couette vortices have been visualized using magnetic-resonance imaging and simulated using an adapted Oregonator model. We show how propagating wave behavior depends on the ratio of advective, chemical and diffusive time scales. In simulations, inward propagating spiral flamelets are observed at high Damköhler number (Da). At low Da, the reaction distributes itself over several vortices and then propagates inwards as contracting ring pulses--also observed experimentally.

Comparing the dynamics of skyrmions and superconducting vortices

International Nuclear Information System (INIS)

Olson Reichhardt, C.J.; Lin, S.Z.; Ray, D.; Reichhardt, C.

2014-01-01

Highlights: • We describe similarities and differences between skyrmion and vortex dynamics. • The Magnus force can dramatically alter skyrmion transport. • The pinning becomes very weak when the Magnus force is strong. - Abstract: Vortices in type-II superconductors have attracted enormous attention as ideal systems in which to study nonequilibrium collective phenomena, since the self-ordering of the vortices competes with quenched disorder and thermal effects. Dynamic effects found in vortex systems include depinning, nonequilibrium phase transitions, creep, structural order–disorder transitions, and melting. Understanding vortex dynamics is also important for applications of superconductors which require the vortices either to remain pinned or to move in a controlled fashion. Recently, topological defects called skyrmions have been realized experimentally in chiral magnets. Here we highlight similarities and differences between skyrmion dynamics and vortex dynamics. Many of the previous ideas and experimental setups that have been applied to superconducting vortices can also be used to study skyrmions. We also discuss some of the differences between the two systems, such as the potentially large contribution of the Magnus force in the skyrmion system that can dramatically alter the dynamics and transport properties

Quarks and gluons in nuclear and particle physics

International Nuclear Information System (INIS)

Van Hove, L.

1988-01-01

This paper provides a broad overview of strong interactions, or nuclear forces, as ones understanding has expanded over the past 25 years. The major particles and models are briefly touched upon. The author expands upon the field theories which have evolved to explain the experimental work, and the present model of quarks and gluons which form the components of hadrons. The standard model has been very successful in explaining much of the newly acquired experimental data. But the property of confinement, where the partons, (quarks and gluons), are not observed seperately has precluded observation of these particles. He touches on the manifestation of these particles in high energy physics, where they model the observed particles and resonances, and are responsible for the production of hadronic jets. However in nuclear physics, one does not need to postulate the existance of these particles to explain the properties of nuclei, until one deals with interaction energies in the range of GeV. The author then touches on the area of ultra-relativistic nuclear physics, where the partons must play a role in the effects which are observed. In particular he discusses deep inelastic lepton scattering on nuclei, the Drell-Yan process in nuclei, and ultra-relativistic nuclear collisions. Finally he gives a brief discussion of the quark-gluon plasma, which is postulated to form during very high energy collisions, manifesting itself as a brief deconfinement of the partons into an equilibrium plasma

Influence of Initial Vorticity Distribution on Axisymmetric Vortex Breakdown and Reconnection

Science.gov (United States)

Young, Larry A.

2007-01-01

An analytical treatment has been developed to study some of the axisymmetric vortex breakdown and reconnection fluid dynamic processes underlying body-vortex interactions that are frequently manifested in rotorcraft and propeller-driven fixed-wing aircraft wakes. In particular, the presence of negative vorticity in the inner core of a vortex filament (one example of which is examined in this paper) subsequent to "cutting" by a solid body has a profound influence on the vortex reconnection, leading to analog flow behavior similar to vortex breakdown phenomena described in the literature. Initial vorticity distributions (three specific examples which are examined) without an inner core of negative vorticity do not exhibit vortex breakdown and instead manifest diffusion-like properties while undergoing vortex reconnection. Though this work focuses on laminar vortical flow, this work is anticipated to provide valuable insight into rotary-wing aerodynamics as well as other types of vortical flow phenomena.

4D-flat compactifications with brane vorticities

International Nuclear Information System (INIS)

Randjbar Daemi, S.; Rubakov, V.

2004-07-01

We present solutions in six-dimensional gravity coupled to a sigma model, in the presence of three-brane sources. The space transverse to the branes is a compact non-singular manifold. The example of O(3) sigma model in the presence of two three-branes is worked out in detail. We show that the four-dimensional flatness is obtained with a single condition involving the brane tensions, which are in general different and may be both positive, and another characteristic of the branes, vorticity. We speculate that the adjustment of the effective four- dimensional cosmological constant may occur through the exchange of vorticity between the branes. We then give exact instanton type solutions for sigma models targeted on a general Kaehler manifold, and elaborate in this framework on multi-instantons of the O(3) sigma model. The latter have branes, possibly with vorticities, at the instanton positions, thus generalizing our two-brane solution. (author)

4d-flat compactifications with brane vorticities

International Nuclear Information System (INIS)

Randjbar-Daemi, Seif; Rubakov, Valery

2004-01-01

We present solutions in six-dimensional gravity coupled to a sigma model, in the presence of three-brane sources. The space transverse to the branes is a compact non-singular manifold. The example of O(3) sigma model in the presence of two three-branes is worked out in detail. We show that the four-dimensional flatness is obtained with a single condition involving the brane tensions, which are in general different and may be both positive, and another characteristic of the branes, vorticity. We speculate that the adjustment of the effective four-dimensional cosmological constant may occur through the exchange of vorticity between the branes. We then give exact instanton type solutions for sigma models targeted on a general Kaehler manifold, and elaborate in this framework on multi-instantons of the O(3) sigma model. The latter have branes, possibly with vorticities, at the instanton positions, thus generalizing our two-brane solution. (author)

Dilepton production from the quark-gluon plasma using (3 +1 )-dimensional anisotropic dissipative hydrodynamics

Science.gov (United States)

Ryblewski, Radoslaw; Strickland, Michael

2015-07-01

We compute dilepton production from the deconfined phase of the quark-gluon plasma using leading-order (3 +1 )-dimensional anisotropic hydrodynamics. The anisotropic hydrodynamics equations employed describe the full spatiotemporal evolution of the transverse temperature, spheroidal momentum-space anisotropy parameter, and the associated three-dimensional collective flow of the matter. The momentum-space anisotropy is also taken into account in the computation of the dilepton production rate, allowing for a self-consistent description of dilepton production from the quark-gluon plasma. For our final results, we present predictions for high-energy dilepton yields as a function of invariant mass, transverse momentum, and pair rapidity. We demonstrate that high-energy dilepton production is extremely sensitive to the assumed level of initial momentum-space anisotropy of the quark-gluon plasma. As a result, it may be possible to experimentally constrain the early-time momentum-space anisotropy of the quark-gluon plasma generated in relativistic heavy-ion collisions using high-energy dilepton yields.

One-loop light-cone QCD, effective action for reggeized gluons and QCD RFT calculus

Energy Technology Data Exchange (ETDEWEB)

Bondarenko, S.; Pozdnyakov, S.; Prygarin, A. [Ariel University, Physics Department, Ariel (Israel); Lipatov, L. [St. Petersburg State University, St. Petersburg (Russian Federation); Petersburg Nuclear Physics Institute, Gatchina (Russian Federation)

2017-09-15

The effective action for reggeized gluons is based on the gluodynamic Yang-Mills Lagrangian with external current for longitudinal gluons added, see Lipatov (Nucl Phys B 452:369, 1995; Phys Rep 286:131, 1997; Subnucl Ser 49:131, 2013; Int J Mod Phys Conf Ser 39:1560082, 2015; Int J Mod Phys A 31(28/29):1645011, 2016; EPJ Web Conf 125:01010, 2016). On the base of classical solutions, obtained in Bondarenko et al. (Eur Phys J C 77(8):527, 2017), the one-loop corrections to this effective action in light-cone gauge are calculated. The RFT calculus for reggeized gluons similarly to the RFT introduced in Gribov (Sov Phys JETP 26:414, 1968) is proposed and discussed. The correctness of the results is verified by calculation of the propagators of A{sub +} and A{sub -} reggeized gluons fields and application of the obtained results is discussed as well. (orig.)

Baryon scattering at high energies. Wave function, impact factor, and gluon radiation

International Nuclear Information System (INIS)

Bartels, J.; Motyka, L.; Jagellonian Univ., Krakow

2007-11-01

The scattering of a baryon consisting of three massive quarks is investigated in the high energy limit of perturbative QCD. A model of a relativistic proton-like wave function, dependent on valence quark longitudinal and transverse momenta and on quark helicities, is proposed, and we derive the baryon impact factors for two, three and four t-channel gluons. We find that the baryonic impact factor can be written as a sum of three pieces: in the first one a subsystem consisting of two of the three quarks behaves very much like the quark-antiquark pair in γ * scattering, whereas the third quark acts as a spectator. The second term belongs to the odderon, whereas in the third (C-even) piece all three quarks participate in the scattering. This term is new and has no analogue in γ * scattering. We also study the small x evolution of gluon radiation for each of these three terms. The first term follows the same pattern of gluon radiation as the γ * -initiated quark-antiquark dipole, and, in particular, it contains the BFKL evolution followed by the 2→4 transition vertex (triple Pomeron vertex). The odderon-term is described by the standard BKP evolution, and the baryon couples to both known odderon solutions, the Janik-Wosiek solution and the BLV solution. Finally, the t-channel evolution of the third term starts with a three reggeized gluon state which then, via a new 3→4 transition vertex, couples to the four gluon (two-Pomeron) state. We briefly discuss a few consequences of these findings, in particular the pattern of unitarization of high energy baryon scattering amplitudes. (orig.)

Baryon scattering at high energies. Wave function, impact factor, and gluon radiation

Energy Technology Data Exchange (ETDEWEB)

Bartels, J. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Motyka, L. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik]|[Jagellonian Univ., Krakow (Poland). Inst. of Physics

2007-11-15

The scattering of a baryon consisting of three massive quarks is investigated in the high energy limit of perturbative QCD. A model of a relativistic proton-like wave function, dependent on valence quark longitudinal and transverse momenta and on quark helicities, is proposed, and we derive the baryon impact factors for two, three and four t-channel gluons. We find that the baryonic impact factor can be written as a sum of three pieces: in the first one a subsystem consisting of two of the three quarks behaves very much like the quark-antiquark pair in {gamma}{sup *} scattering, whereas the third quark acts as a spectator. The second term belongs to the odderon, whereas in the third (C-even) piece all three quarks participate in the scattering. This term is new and has no analogue in {gamma}{sup *} scattering. We also study the small x evolution of gluon radiation for each of these three terms. The first term follows the same pattern of gluon radiation as the {gamma}{sup *}-initiated quark-antiquark dipole, and, in particular, it contains the BFKL evolution followed by the 2{yields}4 transition vertex (triple Pomeron vertex). The odderon-term is described by the standard BKP evolution, and the baryon couples to both known odderon solutions, the Janik-Wosiek solution and the BLV solution. Finally, the t-channel evolution of the third term starts with a three reggeized gluon state which then, via a new 3{yields}4 transition vertex, couples to the four gluon (two-Pomeron) state. We briefly discuss a few consequences of these findings, in particular the pattern of unitarization of high energy baryon scattering amplitudes. (orig.)

Prediction of a new region in the H-T phase diagram of a disordered type II superconductor

International Nuclear Information System (INIS)

Nandgaonkar, Ajay; Kanhere, D.G.; Trivedi, Nandini

1997-01-01

The phase diagram of a type II superconductor (SC) in the magnetic field (B) - temperature (T) plane is shown schematically. At low T the system consists of an Abrikosov triangular vortex lattice which melts as the temperature is increased. At high B, the rigidity of the vortex lattice C 66 decreases with increasing B. Thus, the melting curve essentially tracks the H c2 behaviour, as shown in region (a) in fig. It was further suggested by Nelson, based on a mapping of vortices in 3D onto a problem of boson world-lines in spatial 2D and 1 imaginary dimension, that the classical statistical mechanics of vortices is analogous to the problem of quantum melting of the bosons. He used this mapping to predict a novel reentrant behavior of the phase boundary. These predictions were verified by experiments

Quark-gluon mixing in scalar mesons

International Nuclear Information System (INIS)

Eremyan, Sh.S.; Nazaryan, A.E.

1986-01-01

Scalar mesons are considered within the quark-gluon mixing model. It is shown that there exists decouplet of scalar particles consisting of S* (975), ε (1400), S*' (1700), δ (980) and κ (1350) resonances. It has turned out that the long ago known S* (975)-resonance is a nearly pure glouball. A good description of all available experimental data on scalar meson decays is obtained

The role of three-gluon correlation functions in the single spin asymmetry

Directory of Open Access Journals (Sweden)

Beppu Hiroo

2015-01-01

Full Text Available We study the twist-3 three-gluon contribution to the single spin asymmetry in the light-hadron production in pp collision in the framework of the collinear factorization. We derive the corresponding cross section formula in the leading order with respect to the QCD coupling constant. We also present a numerical calculation of the asymmetry at the RHIC energy, using a model for the three-gluon correlation functions suggested by the asymmetry for the D-meson production at RHIC. We found that the asymmetries for the light-hadron and the jet productions are very useful to constrain the magnitude and form of the correlation functions. Since the three-gluon correlation functions shift the asymmetry for all kinds of hadrons in the same direction, it is unlikely that they become a main source of the asymmetry.

Experimental test of the flavor independence of the quark-gluon coupling constant

International Nuclear Information System (INIS)

Althoff, M.; Braunschweig, W.; Kirschfink, F.J.; Luebelsmeyer, K.; Martyn, H.U.; Rimkus, J.; Rosskamp, P.; Sander, H.G.; Schmitz, D.; Siebke, H.; Wallraff, W.; Duchovni, E.; Karshon, U.; Mikenberg, G.; Mir, R.; Revel, D.; Ronat, E.; Shapira, A.; Yekutieli, G.; Baranko, G.; Barklow, T.; Caldwell, A.; Cherney, M.; Izen, J.M.; Mermikides, M.; Rudolph, G.; Strom, D.; Takashima, M.; Venkataramania, H.; Wicklund, E.; Sau Lan Wu; Zobernig, G.; Eisenberg, Y.; Eskreys, A.; Gather, K.; Hultschig, H.; Joos, P.; Koetz, U.; Kowalski, H.; Ladage, A.; Loehr, B.; Lueke, D.; Maettig, P.; Maettig, P.; Notz, D.; Nowak, R.J.; Pyrlik, J.; Rushton, M.; Schuette, W.; Trines, D.; Wolf, G.; Xiao, C.

1984-01-01

Reconstruction of charged Dsup(*)'s produced inclusively in e + e - annhilations at c.m. energies near 34.4 GeV is accomplished in the decay modes Dsup(*+) -> D 0 π + -> K - π + π 0 π + and Dsup(*+) -> D 0 π + -> K - π + π - π + π + and their charge conjugates. Using these and previously reported Dsup(*+) -> D 0 π + -> K - π + π + and Dsup(*+) -> D 0 π + -> K - π + π + + missing π 0 channels we present evidence for hard gluon bremsstrahlung from charm quarks and show that the ratio of the quark-gluon coupling constant of charm quarks to the coupling constant obtained in the average hadronic event, αsub(s)sup(c)/αsub(s) = 1.00 +- 0.20 +- 0.20. Our result provides evidence that the quark-gluon coupling constant is independent of flavor. (orig.)

Compressible dynamic stall vorticity flux control using a dynamic ...

Indian Academy of Sciences (India)

systems, such as a wind turbine, are prevented from ever entering dynamic stall, essentially disregarding potential ... future generations of such systems, an overwhelming need has developed to avail this benefit safely. ... approach must diffuse the vorticity prior to its coalescence, but keep the vorticity over the airfoil up to ...

Continuous control of asymmetric forebody vortices in a bi-stable state

Science.gov (United States)

Wang, Qi-te; Cheng, Ke-ming; Gu, Yun-song; Li, Zhuo-qi

2018-02-01

Aiming at the problem of continuous control of asymmetric forebody vortices at a high angle of attack in a bi-stable regime, a dual synthetic jet actuator embedded in an ogive forebody was designed. Alternating unsteady disturbance with varying degree asymmetrical flow fields near the nozzles is generated by adjusting the duty cycle of the drive signal of the actuator, specifically embodying the asymmetric time-averaged pattern of jet velocity, vorticity, and turbulent kinetic energy. Experimental results show that within the range of relatively high angles of attack, including the angle-of-attack region in a bi-stable state, the lateral force of the ogive forebody is continuously controlled by adjusting the duty cycle of the drive signal; the position of the forebody vortices in space, the vorticity magnitude, the total pressure coefficient near the vortex core, and the vortex breakdown location are continuously changed with the duty cycle increased observed from the time-averaged flow field. Instantaneous flow field results indicate that although the forebody vortices are in an unsteady oscillation state, a continuous change in the forebody vortices' oscillation balance position as the duty cycle increases leads to a continuous change in the model's surface pressure distribution and time-averaged lateral force. Different from the traditional control principle, in this study, other different degree asymmetrical states of the forebody vortices except the bi-stable state are obtained using the dual synthetic jet control technology.

Ultra relativistic heavy ions collisions or the search for quark-gluon plasmas

International Nuclear Information System (INIS)

Blaizot, J.P.

1985-03-01

This paper reviews some aspects of the physics of ultra-relativistic heavy ion collisions. The qualitative changes expected in the properties of hadronic matter at high temperature and/or large baryon density are described in terms of simple models. We discuss a scenario giving the space-time evolution of a quark-gluon plasma. Finally we address the difficult question of the possible signatures of the formation of a quark-gluon plasma in heavy ion collisions

Nonperturbative quark-gluon thermodynamics at finite density

Science.gov (United States)

Andreichikov, M. A.; Lukashov, M. S.; Simonov, Yu. A.

2018-03-01

Thermodynamics of the quark-gluon plasma at finite density is studied in the framework of the Field Correlator Method, where thermodynamical effects of Polyakov loops and color magnetic confinement are taken into account. Having found good agreement with numerical lattice data for zero density, we calculate pressure P(T,μ), for 0 confinement.

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.

Classical gluon production amplitude for nucleus-nucleus collisions:First saturation correction in the projectile

International Nuclear Information System (INIS)

Chirilli, Giovanni A.; Kovchegov, Yuri V.; Wertepny, Douglas E.

2015-01-01

We calculate the classical single-gluon production amplitude in nucleus-nucleus collisions including the first saturation correction in one of the nuclei (the projectile) while keeping multiple-rescattering (saturation) corrections to all orders in the other nucleus (the target). In our approximation only two nucleons interact in the projectile nucleus: the single-gluon production amplitude we calculate is order-g"3 and is leading-order in the atomic number of the projectile, while resumming all order-one saturation corrections in the target nucleus. Our result is the first step towards obtaining an analytic expression for the first projectile saturation correction to the gluon production cross section in nucleus-nucleus collisions.

Theoretical estimation of Photons flow rate Production in quark gluon interaction at high energies

Science.gov (United States)

Al-Agealy, Hadi J. M.; Hamza Hussein, Hyder; Mustafa Hussein, Saba

2018-05-01

photons emitted from higher energetic collisions in quark-gluon system have been theoretical studied depending on color quantum theory. A simple model for photons emission at quark-gluon system have been investigated. In this model, we use a quantum consideration which enhances to describing the quark system. The photons current rate are estimation for two system at different fugacity coefficient. We discussion the behavior of photons rate and quark gluon system properties in different photons energies with Boltzmann model. The photons rate depending on anisotropic coefficient : strong constant, photons energy, color number, fugacity parameter, thermal energy and critical energy of system are also discussed.

Effects of sharp vorticity gradients in two-dimensional hydrodynamic turbulence

DEFF Research Database (Denmark)

Kuznetsov, E.A.; Naulin, Volker; Nielsen, Anders Henry

2007-01-01

The appearance of sharp vorticity gradients in two-dimensional hydrodynamic turbulence and their influence on the turbulent spectra are considered. We have developed the analog of the vortex line representation as a transformation to the curvilinear system of coordinates moving together with the ......The appearance of sharp vorticity gradients in two-dimensional hydrodynamic turbulence and their influence on the turbulent spectra are considered. We have developed the analog of the vortex line representation as a transformation to the curvilinear system of coordinates moving together...... with the divorticity lines. Compressibility of this mapping can be considered as the main reason for the formation of the sharp vorticity gradients at high Reynolds numbers. For two-dimensional turbulence in the case of strong anisotropy the sharp vorticity gradients can generate spectra which fall off as k−3 at large...

The Born-Infeld vortices induced from a generalized Higgs mechanism.

Science.gov (United States)

Han, Xiaosen

2016-04-01

We construct self-dual Born-Infeld vortices induced from a generalized Higgs mechanism. Two specific models of the theory are of focused interest where the Higgs potential is either of a | ϕ | 4 - or | ϕ | 6 -type. For the | ϕ | 4 -model, we obtain a sharp existence and uniqueness theorem for doubly periodic and planar vortices. For doubly periodic solutions, a necessary and sufficient condition for the existence is explicitly derived in terms of the vortex number, the Born-Infeld parameter, and the size of the periodic lattice domain. For the | ϕ | 6 -model, we show that both topological and non-topological vortices are present. This new phenomenon distinguishes the model from the classical Born-Infeld-Higgs theory studied earlier in the literature. A series of results regarding doubly periodic, topological, and non-topological vortices in the | ϕ | 6 -model are also established.

Late-Stage Vortical Structures and Eddy Motions in a Transitional Boundary Layer

International Nuclear Information System (INIS)

Xiao-Bing, Liu; Zheng-Qing, Chen; Chao-Qun, Liu

2010-01-01

A high-order direct numerical simulation of flow transition over a flat-plate at a free stream Mach number 0.5 is carried out. Formation and development of three-dimensional vortical structures, typically shown as A-vortices, hairpin vortices and ring-like vortices, are observed. Numerical results show that there is a strong downdraft motion of fluid excited by every ring-like vortex in the late-stage of the transition process. At two sides of the vortical structure centerline, the downdraft motions induced by the ring-like vortex and the rotating legs superimpose. This is responsible for the appearance of a high-speed streak associated with the positive spike observed in a previous investigation and the appearance of a high-shear layer in the near wall region. (fundamental areas of phenomenology(including applications))

Quark charges and colour gluon mass from deep-inelastic bremsstrahlung

International Nuclear Information System (INIS)

Pandita, P.N.

1978-01-01

Sum rules are derived for the structure function V(x) for the 'three-photon' process e +- + p →e +- + γ +X which can distinguish between various colour models below colour threshold, independently of the quark and gluon distributions. A careful study of the sum rule for V(x) in the broken colour gauge theory model can in principle be used to determine the colour gluon mass. Invoking the specific assumptions of the dominance of p-type quarks and neglecting the sea of quark-antiquark pairs, bounds for V(x) are obtained in terms of νW 2 (x) which can distinguish between various colour models below colour threshold. (author)

Sharp asymptotic estimates for vorticity solutions of the 2D Navier-Stokes equation

Directory of Open Access Journals (Sweden)

Yuncheng You

2008-12-01

Full Text Available The asymptotic dynamics of high-order temporal-spatial derivatives of the two-dimensional vorticity and velocity of an incompressible, viscous fluid flow in $mathbb{R}^2$ are studied, which is equivalent to the 2D Navier-Stokes equation. It is known that for any integrable initial vorticity, the 2D vorticity solution converges to the Oseen vortex. In this paper, sharp exterior decay estimates of the temporal-spatial derivatives of the vorticity solution are established. These estimates are then used and combined with similarity and $L^p$ compactness to show the asymptotical attraction rates of temporal-spatial derivatives of generic 2D vorticity and velocity solutions by the Oseen vortices and velocity solutions respectively. The asymptotic estimates and the asymptotic attraction rates of all the derivatives obtained in this paper are independent of low or high Reynolds numbers.

Longitudinal vortices in a transitioning boundary layer

International Nuclear Information System (INIS)

Anders, J.B.; Backwelder, R.F.

1980-01-01

Naturally occurring spanwise variations of the streamwise velocity component, characteristic of longitudinal vortices embedded in a transitioning boundary layer were explored using hot-wire anemometers. A vibrating ribbon introduced stable or unstable Tollmien-Schlichting waves into the laminar boundary layer. These damped or growing disturbances always developed a strong three-dimensional pattern even though no spanwise perturbations were artificially induced. Changing the radius of the leading edge and other modifications to the flat plate, wind tunnel and boundary layer did not alter the spanwise wavelength of the vortices. (orig.)

Scaling properties of Wilson loops pierced by P-vortices

DEFF Research Database (Denmark)

Dunn, Patrick; Greensite, Jeffrey Paul

2012-01-01

P-vortices, in an SU(N) lattice gauge theory, are excitations on the center-projected Z(N) lattice. We study the ratio of expectation values of SU(2) Wilson loops, on the unprojected lattice, linked to a single P-vortex, to that of Wilson loops which are not linked to any P-vortices. When...

Imparting small vorticity to a Bianchi type-VIh empty spacetime

Science.gov (United States)

Batakis, Nikos A.

1981-04-01

We present and briefly discuss a Bianchi type-VIh empty spacetime. The field equations have been solved after being linearized with respect to a parameter which imparts vorticity to the model. The limit of zero vorticity is an already known solution.

The Interaction of Two Surface Vortices Near a Topographic Slope in a Stratified Ocean

Directory of Open Access Journals (Sweden)

Charly de Marez

2017-10-01

Full Text Available We study the influence of bottom topography on the interaction of two identical vortices in a two-layer, quasi-geostrophic model. The two vortices have piecewise-uniform potential vorticity and are lying in the upper layer of the model. The topography is a smooth bottom slope. For two cyclones, topography modifies the merger critical distance and the merger efficiency: the topographic wave and vortices can advect the two cyclones along the shelf when they are initially far from it or towards the shelf when they are initially closer to it. They can also advect the two cyclones towards each other and thus favour merger. The cyclones deform, and the potential vorticity field undergoes filamentation. Regimes of partial vortex merger or of vortex splitting are then observed. The interaction of the vorticity poles in the two layers are analysed to explain the evolution of the two upper layer cyclones. For taller topography, two new regimes appear: vortex drift and splitting; and filamentation and asymmetric merger. They are due to the hetonic coupling of lower layer vorticity with the upper layer vortices (a heton is a baroclinic vortex dipole, carrying heat and momentum and propagating horizontally in the fluid, or to the strong shear that the former exerts on the latter. The interaction of two anticyclones shows regimes of co-rotation or merger, but specifically, it leads to the drift of the two vortices away from the slope, via a hetonic coupling with oppositely-signed vorticity in the lower layer. This vorticity originates in the breaking of the topographic wave. The analysis of passive tracer evolution confirms the inshore or offshore drift of the fluid, the formation of tracer fronts along filaments and its stirring in regions of vortex merger. The trajectories of particles indicate how the fluid initially in the vortices is finally partitioned.

Internal and vorticity waves in decaying stratified flows

Science.gov (United States)

Matulka, A.; Cano, D.

2009-04-01

Most predictive models fail when forcing at the Rossby deformation Radius is important and a large range of scales have to be taken into account. When mixing of reactants or pollutants has to be accounted, the range of scales spans from hundreds of Kilometers to the Bachelor or Kolmogorov sub milimiter scales. We present some theoretical arguments to describe the flow in terms of the three dimensional vorticity equations, using a lengthscale related to the vorticity (or enstrophy ) transport. Effect of intermittent eddies and non-homogeneity of diffusion are also key issues in the environment because both stratification and rotation body forces are important and cause anisotropy/non-homogeneity. These problems need further theoretical, numerical and observational work and one approach is to try to maximize the relevant geometrical information in order to understand and therefore predict these complex environmental dispersive flows. The importance of the study of turbulence structure and its relevance in diffusion of contaminants in environmental flows is clear when we see the effect of environmental disasters such as the Prestige oil spill or the Chernobil radioactive cloud spread in the atmosphere. A series of Experiments have been performed on a strongly stratified two layer fluid consisting of Brine in the bottom and freshwater above in a 1 square meter tank. The evolution of the vortices after the passage of a grid is video recorded and Particle tracking is applied on small pliolite particles floating at the interface. The combination of internal waves and vertical vorticity produces two separate time scales that may produce resonances. The vorticity is seen to oscilate in a complex way, where the frecuency decreases with time.

Lagrangian investigations of vorticity dynamics in compressible turbulence

Science.gov (United States)

Parashar, Nishant; Sinha, Sawan Suman; Danish, Mohammad; Srinivasan, Balaji

2017-10-01

In this work, we investigate the influence of compressibility on vorticity-strain rate dynamics. Well-resolved direct numerical simulations of compressible homogeneous isotropic turbulence performed over a cubical domain of 10243 are employed for this study. To clearly identify the influence of compressibility on the time-dependent dynamics (rather than on the one-time flow field), we employ a well-validated Lagrangian particle tracker. The tracker is used to obtain time correlations between the instantaneous vorticity vector and the strain-rate eigenvector system of an appropriately chosen reference time. In this work, compressibility is parameterized in terms of both global (turbulent Mach number) and local parameters (normalized dilatation-rate and flow field topology). Our investigations reveal that the local dilatation rate significantly influences these statistics. In turn, this observed influence of the dilatation rate is predominantly associated with rotation dominated topologies (unstable-focus-compressing, stable-focus-stretching). We find that an enhanced dilatation rate (in both contracting and expanding fluid elements) significantly enhances the tendency of the vorticity vector to align with the largest eigenvector of the strain-rate. Further, in fluid particles where the vorticity vector is maximally misaligned (perpendicular) at the reference time, vorticity does show a substantial tendency to align with the intermediate eigenvector as well. The authors make an attempt to provide physical explanations of these observations (in terms of moment of inertia and angular momentum) by performing detailed calculations following tetrads {approach of Chertkov et al. ["Lagrangian tetrad dynamics and the phenomenology of turbulence," Phys. Fluids 11(8), 2394-2410 (1999)] and Xu et al. ["The pirouette effect in turbulent flows," Nat. Phys. 7(9), 709-712 (2011)]} in a compressible flow field.

Renormalizability of a quark-gluon model with soft BRST breaking in the infrared region

CERN Document Server

Baulieu, L; Gomez, A J; Lemes, V E R; Sobreiro, R F; Sorella, S P

2010-01-01

We prove the renormalizability of a quark-gluon model with a soft breaking of the BRST symmetry, which accounts for the modification of the large distance behavior of the quark and gluon correlation functions. The proof is valid to all orders of perturbation theory, by making use of softly broken Ward identities.

Quark-gluon plasma and the little bang

International Nuclear Information System (INIS)

McLerran, L.

1981-06-01

A space-time picture of the fragmentation and central regions is presented for extremely high energy head-on heavy nucleus collisions. The energy densities of the matter produced in such collisions are estimated. Speculations concerning the possible formation of a quark-gluon plasma are discussed, as are possible experimental signals for analyzing such a plasma

Exploring Quarks, Gluons and the Higgs Boson

Science.gov (United States)

Johansson, K. Erik

2013-01-01

With real particle collision data available on the web, the amazing dynamics of the fundamental particles of the standard model can be explored in classrooms. Complementing the events from the ATLAS experiment with animations of the fundamental processes on the quark and gluon level makes it possible to better understand the invisible world of…

Hadronic total cross-sections through soft gluon summation in impact parameter space

International Nuclear Information System (INIS)

Grau, A.

1999-01-01

IThe Bloch-Nordsieck model for the parton distribution of hadrons in impact parameter space, constructed using soft gluon summation, is investigated in detail. Its dependence upon the infrared structure of the strong coupling constant α s is discussed, both for finite as well as singular, but integrable, α s . The formalism is applied to the prediction of total proton-proton and proton-antiproton cross-sections, where screening, due to soft gluon emission from the initial valence quarks, becomes evident

Medium-induced gluon radiation beyond the eikonal approximation

CERN Document Server

Apolinário, Liliana; Milhano, Guilherme; Salgado, Carlos A

2014-01-01

In this work we improve existing calculations of radiative energy loss by computing corrections that implement energy-momentum conservation, previously only implemented a posteriori, in a rigorous way. Using the path-integral formalism, we compute in-medium splittings allowing transverse motion of all particles in the emission process, thus relaxing the assumption that only the softest particle is permitted such movement. This work constitutes the extension of the computation carried out for x$\\rightarrow$1 in Phys. Lett. B718 (2012) 160-168, to all values of x, the momentum fraction of the energy of the parent parton carried by the emitted gluon. In order to accomplish a general description of the whole in-medium showering process, in this work we allow for arbitrary formation times for the emitted gluon. We provide general expressions and their realisation in the path integral formalism within the harmonic oscillator approximation.

Gluon saturation beyond (naive) leading logs

Energy Technology Data Exchange (ETDEWEB)

Beuf, Guillaume

2014-12-15

An improved version of the Balitsky–Kovchegov equation is presented, with a consistent treatment of kinematics. That improvement allows to resum the most severe of the large higher order corrections which plague the conventional versions of high-energy evolution equations, with approximate kinematics. This result represents a further step towards having high-energy QCD scattering processes under control beyond strict Leading Logarithmic accuracy and with gluon saturation effects.

The gluon propagator in momentum space

International Nuclear Information System (INIS)

Bernard, C.; Soni, A.

1992-01-01

We consider quenched QCD on a 16 3 x40 lattice at β=6.0. We give preliminary numerical results for the lattice gluon propagator evaluated both in coordinate and momentum space. Our findings are compared with earlier results in the literature at zero momentum. In addition, by considering nonzero momenta we attempt to extract the form of the propagator and compare it to continuum predictions formulated by Gribov and others

Hadronization of the quark-gluon plasma

International Nuclear Information System (INIS)

Mueller, B.; Sano, M.; Sato, H.; Schaefer, A.

1986-11-01

We construct a model for hadronization of the quark-gluon plasma, based on the relativistic coalescence model. We relate the coalescence amplitude to the one-particle Wigner function for quarks in the plasma. The relation between the Wigner function and the nucleon structure function is pointed out. We derive explicit expressions for the production of mesons and baryons in the framework of the relativistic harmonic oscillator model of hadronic structure. (author)

Compound quarks and gluons and parton confinement (proposal of a different approach)

International Nuclear Information System (INIS)

Krolikowski, W.

1978-01-01

The author develops further the compound model proposed in 1971, where coloured quarks are factorized into elementary constituents carrying separately the flavour and colour quantum numbers and obeying the 'compensating' wrong statistics. An 'effective quantum chromodynamics' is conjectured, where both coloured quarks and vector gluons (which obey good statistics) are factorized into elementary constituents obeying wrong statistics. Then the Pauli connection of spin and statistics confines these elementary constituents within bound states obeying good statistics. In the parton model approximation with these elementary constituents as partons it prevents also coloured quarks and vector gluons from appearing as free particles. The expected confinement violation for coloured quarks and vector gluons and the observed scaling violation have here a common origin, namely the clustering of elementary constituents inside hadrons. The basic difference between leptons and quarks is related in this model to wrong statistics of elementary constituents involved in the quark structure. (Auth.)

Hello diquark, goodbye gluon

International Nuclear Information System (INIS)

Fredriksson, S.

1984-01-01

The Stockholm diquark is a very small (0.1-0.2 fm), bound pair of two unequal quarks in spin 0 and colour 3*. If it exists, it is expected to simulate many of the trends presently attributed to perturbative gluon processes. The Stockholm group (S. Ekelin, M. Jaendel, T.I. Larson and myself) is therefore looking for reactions where the non-perturbative QCD phenomenon of diquark formation would give signatures completely different from those of perturbative gluonic contributions. I report here on some new suggestions for diquark effects in deep inelastic scattering, with emphasis on neutron-proton differences, proton production in the current fragmentation region and nuclear target (''EMC'') effects

Tales of 1001 gluons

Energy Technology Data Exchange (ETDEWEB)

Weinzierl, Stefan, E-mail: weinzierl@uni-mainz.de

2017-03-13

This report is centred around tree-level scattering amplitudes in pure Yang–Mills theories, the most prominent example is given by the tree-level gluon amplitudes of QCD. I will discuss several ways of computing these amplitudes, illustrating in this way recent developments in perturbative quantum field theory. Topics covered in this review include colour decomposition, spinor and twistor methods, off- and on-shell recursion, MHV amplitudes and MHV expansion, the Grassmannian and the amplituhedron, the scattering equations and the CHY representation. At the end of this report there will be an outlook on the relation between pure Yang–Mills amplitudes and scattering amplitudes in perturbative quantum gravity.

Adiabatic effective action for vortices in neutral and charged superfluids

International Nuclear Information System (INIS)

Hatsuda, M.; Sato, M.; Yahikozawa, S.; Hatsuda, T.

1996-01-01

Adiabatic effective action for vortices in neutral and charged superfluids at zero temperature are calculated using the topological Landau-Ginzburg theory recently proposed by Hatsuda, Yahikozawa, Ao and Thouless, and vortex dynamics are examined. The Berry phase term arising in the effective action naturally yields the Magnus force in both neutral and charged superfluids. It is shown that in neutral superfluid there is only one degree of freedom, namely the center of vorticities, and the vortex energy is proportional to the sum of all vorticities so that it is finite only for the vanishing total vorticity of the system. On the other hand the effective mass and the vortex energy for a vortex in charged superfluids are defined individually as expected. The effects of the vortex core on these quantities are also estimated. The possible depinning scenario which is governed by the Magnus force and the inertial mass is also discussed

Monte Carlo study on the properties of gluon and quark jets

CERN Document Server

Zhang Kun Shi; Yu Mei Ling; LianShouLiu

2002-01-01

The 3-jet events produced in e sup + e sup - collisions at 91.2 GeV have been studied using Monte Carlo method. After applying two angular cuts the three angles between the jets are used to identify the individual jet in 3-jet events. The energy distributions of the three jets, the mean particle multiplicities, mean transverse momenta of the three jets in equal energy bins and their distributions have been analyzed. Comparing with the corresponding results from the quark jets in 2-jet events, a simple method to select gluon and quark jets from 3-jet events is obtained. The properties of the gluon and quark jets being selected using the introduced method are in qualitative agreement with the expectations of perturbative QCD. The ratio of the mean multiplicity between quark and gluon jets, sub g sub l sub u sub o sub n / sub q sub u sub q sub r sub k , has been calculated. The results, again, agree with the experimental results from SLD, OPAL, ALEPH and DELPHI Collaborations, indicating that the method propose...

HUNTING THE QUARK GLUON PLASMA.

Energy Technology Data Exchange (ETDEWEB)

LUDLAM, T.; ARONSON, S.

2005-04-11

The U.S. Department of Energy's Relativistic Heavy Ion Collider (RHIC) construction project was completed at BNL in 1999, with the first data-taking runs in the summer of 2000. Since then the early measurements at RHIC have yielded a wealth of data, from four independent detectors, each with its international collaboration of scientists: BRAHMS, PHENIX, PHOBOS, and STAR [1]. For the first time, collisions of heavy nuclei have been carried out at colliding-beam energies that have previously been accessible only for high-energy physics experiments with collisions of ''elementary'' particles such as protons and electrons. It is at these high energies that the predictions of quantum chromodynamics (QCD), the fundamental theory that describes the role of quarks and gluons in nuclear matter, come into play, and new phenomena are sought that may illuminate our view of the basic structure of matter on the sub-atomic scale, with important implications for the origins of matter on the cosmic scale. The RHIC experiments have recorded data from collisions of gold nuclei at the highest energies ever achieved in man-made particle accelerators. These collisions, of which hundreds of millions have now been examined, result in final states of unprecedented complexity, with thousands of produced particles radiating from the nuclear collision. All four of the RHIC experiments have moved quickly to analyze these data, and have begun to understand the phenomena that unfold from the moment of collision as these particles are produced. In order to provide benchmarks of simpler interactions against which to compare the gold-gold collisions, the experiments have gathered comparable samples of data from collisions of a very light nucleus (deuterium) with gold nuclei, as well as proton-proton collisions, all with identical beam energies and experimental apparatus. The early measurements have revealed compelling evidence for the existence of a new form of nuclear

HUNTING THE QUARK GLUON PLASMA

International Nuclear Information System (INIS)

LUDLAM, T.; ARONSON, S.

2005-01-01

The U.S. Department of Energy's Relativistic Heavy Ion Collider (RHIC) construction project was completed at BNL in 1999, with the first data-taking runs in the summer of 2000. Since then the early measurements at RHIC have yielded a wealth of data, from four independent detectors, each with its international collaboration of scientists: BRAHMS, PHENIX, PHOBOS, and STAR [1]. For the first time, collisions of heavy nuclei have been carried out at colliding-beam energies that have previously been accessible only for high-energy physics experiments with collisions of ''elementary'' particles such as protons and electrons. It is at these high energies that the predictions of quantum chromodynamics (QCD), the fundamental theory that describes the role of quarks and gluons in nuclear matter, come into play, and new phenomena are sought that may illuminate our view of the basic structure of matter on the sub-atomic scale, with important implications for the origins of matter on the cosmic scale. The RHIC experiments have recorded data from collisions of gold nuclei at the highest energies ever achieved in man-made particle accelerators. These collisions, of which hundreds of millions have now been examined, result in final states of unprecedented complexity, with thousands of produced particles radiating from the nuclear collision. All four of the RHIC experiments have moved quickly to analyze these data, and have begun to understand the phenomena that unfold from the moment of collision as these particles are produced. In order to provide benchmarks of simpler interactions against which to compare the gold-gold collisions, the experiments have gathered comparable samples of data from collisions of a very light nucleus (deuterium) with gold nuclei, as well as proton-proton collisions, all with identical beam energies and experimental apparatus. The early measurements have revealed compelling evidence for the existence of a new form of nuclear matter at extremely high

First measurement of the gluon polarisation in the nucleon using D mesons at COMPASS

CERN Document Server

von Hodenberg, Martin

2005-01-01

The complicated structure of the nucleon has been studied with great success in deep-inelastic lepton-nucleon scattering (DIS) experiments at CERN, SLAC and DESY. As a result the unpolarised structure functions have been measured accurately over a wide kinematic range. From these measurements it is possible to determine the gluon density in the nucleon with good accuracy via a so-called QCD fit. In the case of the spin structure of the nucleon the situation is different. Even after decades of experimental and theoretical efforts it remains to be understood how the spin of the nucleon of 1/2 in units of h-bar is to be accounted for in terms of contributions from the quarks and gluons inside the nucleon. Of particular interest is the question whether the polarised gluon density can explain the unexpected smallness of the quark contribution to the nucleon spin. The QCD fit, which worked well in the unpolarised case, yields a polarised gluon density Delta G which is only badly constrained. This is due to the fact...

Localized vortices in ηi-modes

International Nuclear Information System (INIS)

Nycander, J.; Lynov, J.P.; Juul Rasmussen, J.

1992-01-01

For a wide variety of nonlinear wave equations necessary conditions for the existence of localized, stationary structures can be found by applying a simple procedure, involving two steps: First the linear dispersion relation is obtained and the regions of the phase velocity of linear waves found. Secondly, assuming that localized solutions exist, their velocities are determined by using integral relations. The obtained velocity takes the form of a ''center of mass velocity''. If this velocity falls outside the regions of phase velocities for linear waves then nonlinear localized vortices may exist. Otherwise, the structure will couple to the linear waves and gradually disperse. Applying this method we have shown that monopole vortex solutions exist for drift waves driven by the ion temperature gradient in a magnetized plasma, the so-called η i -modes. Numerical solutions show that such vortices are steadily propagating and stable and they generally emerge from localized initial conditions. Our study is motivated by recent high resolution simulations of η i -turbulence, where it was observed that coherent vortices developed spontaneously. These had a dominating influence on the evolution of the turbulence, and the associated anomalous transport was found to be significantly reduced as compared with the predictions from quasilinear theory. (author) 8 refs., 3 figs

Electrochemical Analysis of Taylor Vortices.

Czech Academy of Sciences Publication Activity Database

Wouahbi, F.; Allaf, K.; Sobolík, Václav

2007-01-01

Roč. 37, 1 (2007) , s. 57-62 ISSN 0021-891X Institutional research plan: CEZ:AV0Z40720504 Keywords : electrodiffusion method * taylor vortices * three-segment electrode Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.417, year: 2007

Analysis of propeller-induced ground vortices by particle image velocimetry

NARCIS (Netherlands)

Yang, Y.; Sciacchitano, A.; Veldhuis, L.L.M.; Eitelberg, G.

2017-01-01

Abstract: The interaction between a propeller and its self-induced vortices originating on the ground is investigated in a scaled experiment. The velocity distribution in the flow field in two different planes containing the self-induced vortices is measured by particle image velocimetry (PIV).

Quark-Gluon Soup -- The Perfectly Liquid Phase of QCD

Science.gov (United States)

Heinz, Ulrich

2015-03-01

At temperatures above about 150 MeV and energy densities exceeding 500 MeV/fm3, quarks and gluons exist in the form of a plasma of free color charges that is about 1000 times hotter and a billion times denser than any other plasma ever created in the laboratory. This quark-gluon plasma (QGP) turns out to be strongly coupled, flowing like a liquid. About 35 years ago, the nuclear physics community started a program of relativistic heavy-ion collisions with the goal of producing and studying QGP under controlled laboratory conditions. This article recounts the story of its successful creation in collider experiments at Brookhaven National Laboratory and CERN and the subsequent discovery of its almost perfectly liquid nature, and reports on the recent quantitatively precise determination of its thermodynamic and transport properties.

A Glimpse of Gluons through Deeply Virtual Compton Scattering on the Proton

OpenAIRE

Defurne, M.; Jiménez-Argüello, A. Martì; Ahmed, Z.; Albataineh, H.; Allada, K.; Aniol, K. A.; Bellini, V.; Benali, M.; Boeglin, W.; Bertin, P.; Brossard, M.; Camsonne, A.; Canan, M.; Chandavar, S.; Chen, C.

2017-01-01

The proton is composed of quarks and gluons, bound by the most elusive mechanism of strong interaction called confinement. In this work, the dynamics of quarks and gluons are investigated using deeply virtual Compton scattering (DVCS): produced by a multi-GeV electron, a highly virtual photon scatters off the proton which subsequently radiates a high energy photon. Similarly to holography, measuring not only the magnitude but also the phase of the DVCS amplitude allows to perform 3D images of...

"Submesoscale Soup" Vorticity and Tracer Statistics During the Lateral Mixing Experiment

Science.gov (United States)

Shcherbina, A.; D'Asaro, E. A.; Lee, C. M.; Molemaker, J.; McWilliams, J. C.

2012-12-01

A detailed view of upper-ocean velocity, vorticity, and tracer statistics was obtained by a unique synchronized two-vessel survey in the North Atlantic in winter 2012. In winter, North Atlantic Mode water region south of the Gulf Stream is filled with an energetic, homogeneous, and well-developed submesoscale turbulence field - the "submesoscale soup". Turbulence in the soup is produced by frontogenesis and the surface layer instability of mesoscale eddy flows in the vicinity of the Gulf Stream. This region is a convenient representation of the inertial range of the geophysical turbulence forward cascade spanning scales of o(1-100km). During the Lateral Mixing Experiment in February-March 2012, R/Vs Atlantis and Knorr were run on parallel tracks 1 km apart for 500 km in the submesoscale soup region. Synchronous ADCP sampling provided the first in-situ estimates of full 3-D vorticity and divergence without the usual mix of spatial and temporal aliasing. Tracer distributions were also simultaneously sampled by both vessels using the underway and towed instrumentation. Observed vorticity distribution in the mixed layer was markedly asymmetric, with sparse strands of strong anticyclonic vorticity embedded in a weak, predominantly cyclonic background. While the mean vorticity was close to zero, distribution skewness exceeded 2. These observations confirm theoretical and numerical model predictions for an active submesoscale turbulence field. Submesoscale vorticity spectra also agreed well with the model prediction.

An efficient and general numerical method to compute steady uniform vortices

Science.gov (United States)

Luzzatto-Fegiz, Paolo; Williamson, Charles H. K.

2011-07-01

Steady uniform vortices are widely used to represent high Reynolds number flows, yet their efficient computation still presents some challenges. Existing Newton iteration methods become inefficient as the vortices develop fine-scale features; in addition, these methods cannot, in general, find solutions with specified Casimir invariants. On the other hand, available relaxation approaches are computationally inexpensive, but can fail to converge to a solution. In this paper, we overcome these limitations by introducing a new discretization, based on an inverse-velocity map, which radically increases the efficiency of Newton iteration methods. In addition, we introduce a procedure to prescribe Casimirs and remove the degeneracies in the steady vorticity equation, thus ensuring convergence for general vortex configurations. We illustrate our methodology by considering several unbounded flows involving one or two vortices. Our method enables the computation, for the first time, of steady vortices that do not exhibit any geometric symmetry. In addition, we discover that, as the limiting vortex state for each flow is approached, each family of solutions traces a clockwise spiral in a bifurcation plot consisting of a velocity-impulse diagram. By the recently introduced "IVI diagram" stability approach [Phys. Rev. Lett. 104 (2010) 044504], each turn of this spiral is associated with a loss of stability for the steady flows. Such spiral structure is suggested to be a universal feature of steady, uniform-vorticity flows.

K factor for Higgs boson production via gluon fusion process at hadron colliders

International Nuclear Information System (INIS)

Tanaka, H.

1992-01-01

In this paper soft gluon corrections for Higgs boson production at hadron colliders are calculated. It is found that the soft contributions for the Higgs boson production via gluon fusion process is large and it cannot be neglected even at SSC energy. Some qualitative discussions for the QCD corrections to the Higgs boson production at hadron colliders and their background processes are presented for various Higgs boson mass cases

Strangeness and the quark-gluon plasma: An experimenter's perspective

International Nuclear Information System (INIS)

Odyniec, G.

1994-02-01

Current status of experimental results on strange particle production in relativistic nucleus-nucleus collisions is reviewed. Emphasis is placed on the relevance to the hypothetical quark-gluon plasma formation and the origin of the Universe

An experimental investigation of wind pressures on square pillars in tornado-like vortices

International Nuclear Information System (INIS)

Iwatani, Yoshiharu; Maruta, Eizou; Kanda, Makoto; Hattori, Yousuke; Hamano, Naoki; Matsuura, Takeshi

1992-01-01

This report describes a laboratory simulation of tornado-like vortices and laboratory measurements of steady wind loads on model structures in tornado-like vortices. The variations of wind direction and wind speed of tornado-like vortices and ground surface pressure under tornado-like vortices with the swirl ratio, Reynolds number and the surface roughness were investigated. Wind pressure distributions on square pillars were measured in tornado-like vortices. It was observed in the experiment that the negative pressures on the roof faces of square pillars were high and distributed rather uniformly but these on the side faces differed greatly from place to place and locally became high. The high pressure regions on the side faces were close to ground surface in the case where the model structures stood in the center of tornado-like vortex, and became higher as the increase of distance between the model structures and the center of tornado-like vortices. (author)

Effects of wing locations on wing rock induced by forebody vortices

Directory of Open Access Journals (Sweden)

Ma Baofeng

2016-10-01

Full Text Available Previous studies have shown that asymmetric vortex wakes over slender bodies exhibit a multi-vortex structure with an alternate arrangement along a body axis at high angle of attack. In this investigation, the effects of wing locations along a body axis on wing rock induced by forebody vortices was studied experimentally at a subcritical Reynolds number based on a body diameter. An artificial perturbation was added onto the nose tip to fix the orientations of forebody vortices. Particle image velocimetry was used to identify flow patterns of forebody vortices in static situations, and time histories of wing rock were obtained using a free-to-roll rig. The results show that the wing locations can affect significantly the motion patterns of wing rock owing to the variation of multi-vortex patterns of forebody vortices. As the wing locations make the forebody vortices a two-vortex pattern, the wing body exhibits regularly divergence and fixed-point motion with azimuthal variations of the tip perturbation. If a three-vortex pattern exists over the wing, however, the wing-rock patterns depend on the impact of the highest vortex and newborn vortex. As the three vortices together influence the wing flow, wing-rock patterns exhibit regularly fixed-points and limit-cycled oscillations. With the wing moving backwards, the newborn vortex becomes stronger, and wing-rock patterns become fixed-points, chaotic oscillations, and limit-cycled oscillations. With further backward movement of wings, the vortices are far away from the upper surface of wings, and the motions exhibit divergence, limit-cycled oscillations and fixed-points. For the rearmost location of the wing, the wing body exhibits stochastic oscillations and fixed-points.

Physics of the quark-gluon plasma

International Nuclear Information System (INIS)

Polonyi, J.; Institut National de Physique Nucleaire et de Physique des Particules; Lorand Eoetvoes Univ., Budapest

1995-01-01

Some features of the high temperature gluonic matter, such as the breakdown of the fundamental group symmetry by the kinetic energy, the screening of test quarks by some unusual gluon states and the explanation of the absence of isolated quarks in the vacuum without the help of infinities are presented in this talk. Special attention is paid to separate the dynamical input inferred from the numerical results of lattice gauge theory from the kinematics. (author)

The gluon propagator in momentum space

Energy Technology Data Exchange (ETDEWEB)

Bernard, C. [Washington Univ., St. Louis, MO (United States). Dept. of Physics; Parrinello, C. [New York Univ., NY (United States). Dept. of Physics]|[Brookhaven National Lab., Upton, NY (United States); Soni, A. [Brookhaven National Lab., Upton, NY (United States)

1992-12-31

We consider quenched QCD on a 16{sup 3}{times}40 lattice at {beta}=6.0. We give preliminary numerical results for the lattice gluon propagator evaluated both in coordinate and momentum space. Our findings are compared with earlier results in the literature at zero momentum. In addition, by considering nonzero momenta we attempt to extract the form of the propagator and compare it to continuum predictions formulated by Gribov and others.

The gluon propagator in momentum space

Energy Technology Data Exchange (ETDEWEB)

Bernard, C. (Washington Univ., St. Louis, MO (United States). Dept. of Physics); Parrinello, C. (New York Univ., NY (United States). Dept. of Physics Brookhaven National Lab., Upton, NY (United States)); Soni, A. (Brookhaven National Lab., Upton, NY (United States))

1992-01-01

We consider quenched QCD on a 16[sup 3][times]40 lattice at [beta]=6.0. We give preliminary numerical results for the lattice gluon propagator evaluated both in coordinate and momentum space. Our findings are compared with earlier results in the literature at zero momentum. In addition, by considering nonzero momenta we attempt to extract the form of the propagator and compare it to continuum predictions formulated by Gribov and others.

The gluon propagator in momentum space

Energy Technology Data Exchange (ETDEWEB)

Bernard, C. (Dept. of Physics, Washington Univ., St. Louis, MO (United States)); Parrinello, C. (Physics Dept., New York Univ., NY (United States) Physics Dept., Brookhaven National Lab., Upton, NY (United States)); Soni, A. (Physics Dept., Brookhaven National Lab., Upton, NY (United States))

1993-03-01

We consider quenched QCD on a 16[sup 3] x 40 lattice at [beta] = 6.0. We give preliminary numerical results for the lattice gluon propagator evaluated both in coordinate and momentum space. Our findings are compared with earlier results in the literature at zero momentum. In addition, by considering nonzero momenta we attempt to extract the form of the propagator and compare it to continuum predictions formulated by Gribov and others. (orig.)

Constraining anomalous gluon self-interactions at the LHC: a reappraisal arXiv

CERN Document Server

Hirschi, V.; Tsinikos, I.; Vryonidou, E.

Anomalous self-interactions of non-abelian gauge fields can be described by higher dimensional operators featuring gauge-invariant combinations of the field strengths. In the case of QCD, the gluon self-interactions start to be modified at dimension six by operators of the type $GGG$, with $G$ the gluon field strength tensor, possibly leading to deviations in all observables and measurements that probe strong interactions at very small distances. In this work we consider the sensitivity to the triple gluon operator of a series of observables at the LHC in di-jet, three- and multi-jet final states and heavy-quark production. We critically re-examine the robustness of long-standing as well as more recent proposals addressing issues such as the validity of the EFT expansion and the impact of higher order QCD corrections. Our results support the conclusion that multi-jet observables can reliably bound these anomalous interactions to the level that their impact on other key observables at the LHC, involving for ex...

Resummation of soft gluon logarithms in the DGLAP evolution of fragmentation functions

International Nuclear Information System (INIS)

Albino, S.; Kniehl, B.A.; Kramer, G.; Ochs, W.

2005-10-01

We define a general scheme for the evolution of fragmentation functions which resums both soft gluon logarithms and mass singularities in a consistent manner and to any order, and requires no additional theoretical assumptions. Using the Double Logarithmic Approximation and the known perturbative results for the splitting functions, we present our scheme with the complete contribution from the double logarithms, being the largest soft gluon logarithms. We show that the resulting approximation is more complete than the Modified Leading Logarithm Approximation even with the fixed order contribution calculated to leading order only, and find, after using it to fit quark and gluon fragmentation functions to experimental data, that this approximation in our scheme gives a good description of the data from the largest χ p values to the peak region in ξ=ln(1/χ p ), in contrast to other approximations. In addition, we develop a treatment of hadron mass effects which gives additional improvements at large ξ. (orig.)

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.

NGluon. A package to calculate one-loop multi-gluon amplitudes

Energy Technology Data Exchange (ETDEWEB)

Badger, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Niels Bohr Institute, Copenhagen (Denmark). Niels Bohr International Academy and Discovery Center; Biedermann, B.; Uwer, P. [Humboldt Univ., Berlin (Germany). Inst. fuer Physik

2010-11-15

We present a computer library for the numerical evaluation of colour-ordered n-gluon amplitudes at one-loop order in pure Yang-Mills theory. The library uses the recently developed technique of generalised unitarity. Running in double precision the library yields reliable results for up to 14 gluons with only a small fraction of events requiring a re-evaluation using extended floating point arithmetic. We believe that the library presented here provides an important contribution to future LHC phenomenology. The program may also prove useful in cross checking results obtained by other methods. In addition, the code provides a sample implementation which may serve as a starting point for further developments. (orig.)

NGluon. A package to calculate one-loop multi-gluon amplitudes

International Nuclear Information System (INIS)

Badger, S.; Niels Bohr Institute, Copenhagen; Biedermann, B.; Uwer, P.

2010-11-01

We present a computer library for the numerical evaluation of colour-ordered n-gluon amplitudes at one-loop order in pure Yang-Mills theory. The library uses the recently developed technique of generalised unitarity. Running in double precision the library yields reliable results for up to 14 gluons with only a small fraction of events requiring a re-evaluation using extended floating point arithmetic. We believe that the library presented here provides an important contribution to future LHC phenomenology. The program may also prove useful in cross checking results obtained by other methods. In addition, the code provides a sample implementation which may serve as a starting point for further developments. (orig.)

Searching for gluon number fluctuations effects in eA collisions

Energy Technology Data Exchange (ETDEWEB)

Kugeratski, M. S. [Universidade Federal de Santa Catarina, Campus Joinville, Rua Presidente Prudente de Moraes, 406, CEP 89218-000, Joinville, SC (Brazil); Gonçalves, V. P.; Santana Amaral, J. T. de [Instituto de Física e Matemática, Universidade Federal de Pelotas, Caixa Postal 354, CEP 96010-900, Pelotas, RS (Brazil)

2014-11-11

We propose to investigate the gluon number fluctuations effects in deep inelastic electron-ion scattering at high energies. We estimate the nuclear structure function F{sub 2}{sup A}(x,Q{sup 2}), as well the longitudinal and charm contributions, using a generalization for nuclear targets of the Golec-Biernat-Wusthoff (GBW) model which describes the electron proton HERA data. Here we consider that the nucleus at high energies acts as an amplifier of the physics of high parton densities. For a first investigation we study the scattering with Ca and Pb nuclei. Our preliminary results predict that the effects of gluon number fluctuations are small in the region of the future electron ion collider.

Diffractive J/ψ photoproduction as a probe of the gluon density

International Nuclear Information System (INIS)

Ryskin, M.G.; Roberts, R.G.; Martin, A.D.; Levin, E.M.

1995-11-01

We use perturbative QCD beyond the leading Ln Q 2 approximation, to show how measurements of diffractive J/ψ production at HERA can provide a sensitive probe of the gluon density of the proton at small values of Bjorken x. We estimate both the effect of the relativistic motion of the c and c within the J/ψ and of the rescattering of the cc quark pair on the proton. We find that the available data for diffractive J/ψ photoproduction can discriminate between the gluon distributions of the most recent sets of partons. (author). 18 refs., 9 figs., 1 tab

The Mellin transform technique for the extraction of the gluon density

International Nuclear Information System (INIS)

Graudenz, D.

1995-06-01

A new method is presented to determine the gluon density in the proton from jet production in deeply inelastic scattering. By using the technique of Mellin transforms not only for the solution of the scale evolution equation of the parton densities but also for the evaluation of scattering cross sections, the gluon density can be extracted in next-to-leading order QCD. The method described in this paper is, however, more general, and can be used in situations where a repeated fast numerical evaluation of scattering cross sections for varying parton distribution functions is required. (orig.)

Interaction of plasma vortices with resonant particles

DEFF Research Database (Denmark)

Jovanovic, D.; Pécseli, Hans; Juul Rasmussen, J.

1990-01-01

Kinetic effects associated with the electron motion along magnetic field lines in low‐beta plasmas are studied. Using the gyrokinetic description of electrons, a kinetic analog of the reduced magnetohydrodynamic equations is derived, and it is shown that in the strongly nonlinear regime...... particles. The evolution equations indicate the possibility of excitation of plasma vortices by electron beams....... they possess localized solutions in the form of dipolar vortices, which can efficiently interact with resonant electrons. In the adiabatic limit, evolution equations are derived for the vortex parameters, describing exchange of the energy, enstrophy, and of the Poynting vector between the vortex and resonant...

Two-gluon correlations in heavy–light ion collisions

International Nuclear Information System (INIS)

Wertepny, Douglas E.

2014-01-01

We derive the cross-section for two-gluon production in heavy–light ion collisions in the saturation/Color Glass Condensate framework. This calculation includes saturation effects to all orders in one of the nuclei (heavy ion) along with a single saturation correction in the projectile (light ion). The calculation of the correlation function predicts (qualitatively) two identical ridge-like correlations, near- and away-side. This prediction was later supported by experimental findings in p + A collisions at the LHC. Concentrating on the energy and geometry dependence of the correlation functions we find that the correlation function is nearly center-of-mass energy independent. The geometry dependence of the correlation function leads to an enhancement of near- and away-side correlations for the tip-on-tip U + U collisions when compared with side-on-side U + U collisions, an exactly opposite behavior from the correlations generated by the elliptic flow of the quark–gluon plasma

Chemical Evolution of Strongly Interacting Quark-Gluon Plasma

International Nuclear Information System (INIS)

Pan, Ying-Hua; Zhang, Wei-Ning

2014-01-01

At very initial stage of relativistic heavy ion collisions a wave of quark-gluon matter is produced from the break-up of the strong color electric field and then thermalizes at a short time scale (~1 fm/c). However, the quark-gluon plasma (QGP) system is far out of chemical equilibrium, especially for the heavy quarks which are supposed to reach chemical equilibrium much late. In this paper a continuing quark production picture for strongly interacting QGP system is derived, using the quark number susceptibilities and the equation of state; both of them are from the results calculated by the Wuppertal-Budapest lattice QCD collaboration. We find that the densities of light quarks increase by 75% from the temperature T=400 MeV to T=150 MeV, while the density of strange quark annihilates by 18% in the temperature region. We also offer a discussion on how this late production of quarks affects the final charge-charge correlations

Agradient velocity, vortical motion and gravity waves in a rotating shallow-water model

Science.gov (United States)

Sutyrin Georgi, G.

2004-07-01

A new approach to modelling slow vortical motion and fast inertia-gravity waves is suggested within the rotating shallow-water primitive equations with arbitrary topography. The velocity is exactly expressed as a sum of the gradient wind, described by the Bernoulli function,B, and the remaining agradient part, proportional to the velocity tendency. Then the equation for inverse potential vorticity,Q, as well as momentum equations for agradient velocity include the same source of intrinsic flow evolution expressed as a single term J (B, Q), where J is the Jacobian operator (for any steady state J (B, Q) = 0). Two components of agradient velocity are responsible for the fast inertia-gravity wave propagation similar to the traditionally used divergence and ageostrophic vorticity. This approach allows for the construction of balance relations for vortical dynamics and potential vorticity inversion schemes even for moderate Rossby and Froude numbers assuming the characteristic value of |J(B, Q)| = to be small. The components of agradient velocity are used as the fast variables slaved to potential vorticity that allows for diagnostic estimates of the velocity tendency, the direct potential vorticity inversion with the accuracy of 2 and the corresponding potential vorticity-conserving agradient velocity balance model (AVBM). The ultimate limitations of constructing the balance are revealed in the form of the ellipticity condition for balanced tendency of the Bernoulli function which incorporates both known criteria of the formal stability: the gradient wind modified by the characteristic vortical Rossby wave phase speed should be subcritical. The accuracy of the AVBM is illustrated by considering the linear normal modes and coastal Kelvin waves in the f-plane channel with topography.

Generation of the vorticity mode by sound in a Bingham plastic

Science.gov (United States)

Perelomova, Anna; Wojda, Pawel

2011-10-01

This study investigates interaction between acoustic and non-acoustic modes, such as vorticity mode, in some class of a non-newtonian fluid called Bingham plastic. The instantaneous equations describing interaction between different modes are derived. The attention is paid to the nonlinear effects in the field of intense sound. The resulting equations which describe dynamics of both sound and the vorticity mode apply to both periodic and aperiodic sound of any waveform. They use only instantaneous quantities and do not imply averaging over the sound period. The theory is illustrated by an example of acoustic force of vorticity induced in the field of a Gaussian sound beam. Some unusual peculiarities in both sound and the vorticity induced in its field as compared to a newtonian fluid, are discovered.

QCD evolution of (un)polarized gluon TMDPDFs and the Higgs q T -distribution

Science.gov (United States)

Echevarria, Miguel G.; Kasemets, Tomas; Mulders, Piet J.; Pisano, Cristian

2015-07-01

We provide the proper definition of all the leading-twist (un)polarized gluon transverse momentum dependent parton distribution functions (TMDPDFs), by considering the Higgs boson transverse momentum distribution in hadron-hadron collisions and deriving the factorization theorem in terms of them. We show that the evolution of all the (un)polarized gluon TMDPDFs is driven by a universal evolution kernel, which can be resummed up to next-to-next-to-leading-logarithmic accuracy. Considering the proper definition of gluon TMDPDFs, we perform an explicit next-to-leading-order calculation of the unpolarized ( f {1/ g }), linearly polarized ( h {1/⊥ g }) and helicity ( g {1/L g }) gluon TMDPDFs, and show that, as expected, they are free from rapidity divergences. As a byproduct, we obtain the Wilson coefficients of the refactorization of these TMDPDFs at large transverse momentum. In particular, the coefficient of g {1/L g }, which has never been calculated before, constitutes a new and necessary ingredient for a reliable phenomenological extraction of this quantity, for instance at RHIC or the future AFTER@LHC or Electron-Ion Collider. The coefficients of f {1/ g } and h {1/⊥ g } have never been calculated in the present formalism, although they could be obtained by carefully collecting and recasting previous results in the new TMD formalism. We apply these results to analyze the contribution of linearly polarized gluons at different scales, relevant, for instance, for the inclusive production of the Higgs boson and the C-even pseudoscalar bottomonium state η b . Applying our resummation scheme we finally provide predictions for the Higgs boson q T -distribution at the LHC.

Lattice Boltzmann model capable of mesoscopic vorticity computation

Science.gov (United States)

Peng, Cheng; Guo, Zhaoli; Wang, Lian-Ping

2017-11-01

It is well known that standard lattice Boltzmann (LB) models allow the strain-rate components to be computed mesoscopically (i.e., through the local particle distributions) and as such possess a second-order accuracy in strain rate. This is one of the appealing features of the lattice Boltzmann method (LBM) which is of only second-order accuracy in hydrodynamic velocity itself. However, no known LB model can provide the same quality for vorticity and pressure gradients. In this paper, we design a multiple-relaxation time LB model on a three-dimensional 27-discrete-velocity (D3Q27) lattice. A detailed Chapman-Enskog analysis is presented to illustrate all the necessary constraints in reproducing the isothermal Navier-Stokes equations. The remaining degrees of freedom are carefully analyzed to derive a model that accommodates mesoscopic computation of all the velocity and pressure gradients from the nonequilibrium moments. This way of vorticity calculation naturally ensures a second-order accuracy, which is also proven through an asymptotic analysis. We thus show, with enough degrees of freedom and appropriate modifications, the mesoscopic vorticity computation can be achieved in LBM. The resulting model is then validated in simulations of a three-dimensional decaying Taylor-Green flow, a lid-driven cavity flow, and a uniform flow passing a fixed sphere. Furthermore, it is shown that the mesoscopic vorticity computation can be realized even with single relaxation parameter.

Casimir meets Poisson: improved quark/gluon discrimination with counting observables

Science.gov (United States)

Frye, Christopher; Larkoski, Andrew J.; Thaler, Jesse; Zhou, Kevin

2017-09-01

Charged track multiplicity is among the most powerful observables for discriminating quark- from gluon-initiated jets. Despite its utility, it is not infrared and collinear (IRC) safe, so perturbative calculations are limited to studying the energy evolution of multiplicity moments. While IRC-safe observables, like jet mass, are perturbatively calculable, their distributions often exhibit Casimir scaling, such that their quark/gluon discrimination power is limited by the ratio of quark to gluon color factors. In this paper, we introduce new IRC-safe counting observables whose discrimination performance exceeds that of jet mass and approaches that of track multiplicity. The key observation is that track multiplicity is approximately Poisson distributed, with more suppressed tails than the Sudakov peak structure from jet mass. By using an iterated version of the soft drop jet grooming algorithm, we can define a "soft drop multiplicity" which is Poisson distributed at leading-logarithmic accuracy. In addition, we calculate the next-to-leading-logarithmic corrections to this Poisson structure. If we allow the soft drop groomer to proceed to the end of the jet branching history, we can define a collinear-unsafe (but still infrared-safe) counting observable. Exploiting the universality of the collinear limit, we define generalized fragmentation functions to study the perturbative energy evolution of collinear-unsafe multiplicity.

Taming the forces between quarks and gluons calorons out of the box : scientific papers by Pierre van Baal

CERN Document Server

Van Baal, Pierre; Korthals Altes, Chris P

2013-01-01

This volume is a collection of selected papers by Pierre van Baal on the subject of quark-gluon interactions. He concentrates on semi-perturbative phenomena that occur when these particles are confined to a box. He introduced in 1998 the notion of calorons to explain what happens in the high temperature phase of the quark-gluon plasma. Van Baal's discoveries of the mathematical intricacies of twisted gluon field configurations have left their mark on the field, opening new directions for numerical simulations. This reprint is intended to be a comprehensive introduction for all those who wish to have deeper understanding of quark-gluon dynamics.

Streaming vorticity flux from oscillating walls with finite amplitude

Science.gov (United States)

Wu, J. Z.; Wu, X. H.; Wu, J. M.

1993-01-01

How to describe vorticity creation from a moving wall is a long standing problem. This paper discusses relevant issues at the fundamental level. First, it is shown that the concept of 'vorticity flux due to wall acceleration' can be best understood by following fluid particles on the wall rather than observing the flow at fixed spatial points. This is of crucial importance when the time-averaged flux is to be considered. The averaged flux has to be estimated in a wall-fixed frame of reference (in which there is no flux due to wall acceleration at all); or, if an inertial frame of reference is used, the generalized Lagrangian mean (GLM) also gives the same result. Then, for some simple but typical configurations, the time-averaged vorticity flux from a harmonically oscillating wall with finite amplitude is analyzed, without appealing to small perturbation. The main conclusion is that the wall oscillation will produce an additional mean vorticity flux (a fully nonlinear streaming effect), which is partially responsible for the mechanism of vortex flow control by waves. The results provide qualitative explanation for some experimentally and/or computationally observed phenomena.

Direct observation of rectified motion of vortices by Lorentz microscopy

Indian Academy of Sciences (India)

We have investigated the vortex dynamics for the `ratchet' operation in a niobium superconductor via a direct imaging of Lorentz microscopy. We directly observe one-directional selective motion of field-gradient-driven vortices along fabricated channels. This results from the rectification of vortices in a spatially asymmetric ...

Propagation and diffraction of optical vortices

International Nuclear Information System (INIS)

Fischer, Pascal; Skelton, Susan E.; Leburn, Christopher G.; Streuber, Casey T.; Wright, Ewan M.; Dholakia, Kishan

2008-01-01

We explore the propagation and diffraction of optical vortices (Laguerre-Gaussian beams) of varying azimuthal index past a circular obstacle and Young's double slits. When the beam and obstacle centers are aligned the famous spot of Arago, which arises for zero azimuthal index, is replaced for non-zero azimuthal indices by a dark spot of Arago, a simple consequence of the conserved phase singularity at the beam center. We explore how for larger azimuthal indices, as the beam and obstacle centers are progressively misaligned, the central dark spot breaks up into several dark spots of Arago. Using Young's double slits we can easily measure the azimuthal index of the vortex beam, even for polychromatic vortices generated by broadband supercontinuum radiation

Peak effect in twinned superconductors

International Nuclear Information System (INIS)

Larkin, A.I.; Marchetti, M.C.; Vinokur, V.M.

1995-01-01

A sharp maximum in the critical current J c as a function of temperature just below the melting point of the Abrikosov flux lattice has recently been observed in both low- and high-temperature superconductors. This peak effect is strongest in twinned crystals for fields aligned with the twin planes. We propose that this peak signals the breakdown of the collective pinning regime and the crossover to strong pinning of single vortices on the twin boundaries. This crossover is very sharp and can account for the steep drop of the differential resistivity observed in experiments. copyright 1995 The American Physical Society

Resummation and the gluon damping rate in hot QCD

International Nuclear Information System (INIS)

Pisarski, R.D.

1990-08-01

At high temperature a consistent perturbative expansion requires the resummation of an infinite subset of loop corrections into an effective expansion. This effective exansion is used to compute the gluon damping rate at leading order. 25 refs

Quark condensate contributions to the gluon self-energy and the ρ meson sum rule

International Nuclear Information System (INIS)

Steele, T.G.

1989-01-01

The operator-product expansion will be employed to obtain the lowest-order, quark condensate component of both the gluon self-energy and the ρ meson correlation function to all orders in the quark mass parameter. Field-theoretic aspects of the self-energy and correlation function will be considered, and physical effects to the quark condensate upon gluon mass generation will be examined. (orig.)

Searching for the quarks and gluons plasma

International Nuclear Information System (INIS)

Gerschel, C.; Kluberg, L.

1989-01-01

Some investigations involving quark matter, at CERN, are discussed. The CERN available oxygen and sulfur beams, with energy about 200 GeV/nuclei, allow the obtention of high energy densities, never reached before. The possibilities of investigating (at CERN) the quarks and gluons plasma are considered. The first and unexpected results obtained from the NA38 experiment are overviewed [fr

On the evolution of vortices in massive protoplanetary discs

Science.gov (United States)

Pierens, Arnaud; Lin, Min-Kai

2018-05-01

It is expected that a pressure bump can be formed at the inner edge of a dead-zone, and where vortices can develop through the Rossby Wave Instability (RWI). It has been suggested that self-gravity can significantly affect the evolution of such vortices. We present the results of 2D hydrodynamical simulations of the evolution of vortices forming at a pressure bump in self-gravitating discs with Toomre parameter in the range 4 - 30. We consider isothermal plus non-isothermal disc models that employ either the classical β prescription or a more realistic treatment for cooling. The main aim is to investigate whether the condensating effect of self-gravity can stabilize vortices in sufficiently massive discs. We confirm that in isothermal disc models with Q ≳ 15, vortex decay occurs due to the vortex self-gravitational torque. For discs with 3≲ Q ≲ 7, the vortex develops gravitational instabilities within its core and undergoes gravitational collapse, whereas more massive discs give rise to the formation of global eccentric modes. In non-isothermal discs with β cooling, the vortex maintains a turbulent core prior to undergoing gravitational collapse for β ≲ 0.1, whereas it decays if β ≥ 1. In models that incorpore both self-gravity and a better treatment for cooling, however, a stable vortex is formed with aspect ratio χ ˜ 3 - 4. Our results indicate that self-gravity significantly impacts the evolution of vortices forming in protoplanetary discs, although the thermodynamical structure of the vortex is equally important for determining its long-term dynamics.