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Properties of the eta prime meson

Description: The {eta}'(958) meson has been studied in the reaction K{sup -}p {yields} {Lambda}{eta}', with K{sup -} beam momenta ranging from 1.70 to 2.65 Gev/c. The Dalitz plots of {eta}' decay into {pi}{sup +}{pi}{sup -}{eta} and {pi}{sup +}{pi}{sup -}{gamma} have been examined, and from them we have determined that the most likely quantum numbers of the {eta}' are I{sup G}J{sup P} = 0{sup +}0{sup -}, although J{sup P} = 2{sup -} cannot be completely ruled out. They have also shown that the decay into {pi}{sup +}{sup -}{gamma} is mediated by the decay {eta}' {yields} {rho}{sup o}{gamma}. An examination of the production process has yielded further evidence for the J{sup P} = 0{sup -} assignment and suggested that the process takes place via K*(891) exchange in the t channel. Branching fractions and cross sections have been determined, and finally a search for a negatively charged {eta}' in the deuterium reaction K{sup -}d {yields} p{Lambda}{eta}' has confirmed the I = 0 assignment for the {eta}'.
Date: June 4, 1969
Creator: Rittenberg, Alan
Partner: UNT Libraries Government Documents Department

Effects of line shifts and the ion quadrupole contribution of spectral line asymmetries.

Description: Line asymmetries and the corresponding shift of spectral lines due to the electron penetration of the radiator orbitals and the ion quadrupole contribution become more significant with increasing principal quantum number and increasing electron density. The mean field static shift due to electron penetration of the orbitals gives rise to an overall shift of the line to lower energy and a significant asymmetry near line center, but does not generate much redhlue far wing asymmetry. The ion quadrupole contribution results in a small blue shift of the spectral line and a small change in asymmetry near line center, but it gives rise to a significant redhlue wing asymmetry in the far wings of the line. Experimental data fiom recent spherical implosion experiments on OMEGA shows evidence of the mean field static shift and may also show the effects of level interactions between the Ar Lyman -{gamma}, -{delta}, -{var_epsilon} lines and also the Ar He -{gamma}, -{delta} lines.
Date: January 1, 2002
Creator: Gunderson, M. A. (Mark A.); Delamater, N. D. (Norman D.); Kilcrease, D. P. (David P.) & Haynes, D. A. (Donald A.)
Partner: UNT Libraries Government Documents Department

The Spin- and Angel-Resolved Photelectron Spectrometer

Description: A spin- and angle-resolved x-ray photoelectron spectrometer for the study of magnetic materials will be discussed. It consists of a turntable with electron lenses connected to a large hemispherical analyzer. A mini-Mott spin detector is fitted to the output of the hemispherical analyzer. This system, when coupled to a synchrotron radiation source will allow determination of a complete set of quantum numbers of a photoelectron. This instrument will be used to study ferromagnetic, antiferromagnetic and nonmagnetic materials. Some prototypical materials systems to be studied with this instrument system will be proposed.
Date: May 8, 2007
Creator: Mankey, G J; Morton, S A; Tobin, J G; Yu, S W & Waddill, G D
Partner: UNT Libraries Government Documents Department

Confinement and flavor symmetry breaking via monopolecondensation

Description: We discuss dynamics of N=2 supersymmetric SU(n_c) gaugetheories with n_f quark hypermultiplets. Upon N=1 perturbation ofintroducing a finite mass for the adjoint chiral multiplet, we show thatthe flavor U(n_f) symmetry is dynamically broken to U(r) times U(n_f-r),where r\leq [n_f/2]is an integer. This flavor symmetry breaking occursdue to the condensates of magnetic degrees of freedom which acquireflavor quantum numbers due to the quark zero modes. We briefly comment onthe USp(2n_c) gauge theories. This talk is based on works with GiuseppeCarlino and Ken Konishi, hep-th/0001036 and hep-th/0005076.
Date: September 19, 2000
Creator: Murayama, Hitoshi
Partner: UNT Libraries Government Documents Department

A Les Houches Interface for BSM Generators

Description: We propose to combine and slightly extend two existing 'Les Houches Accords' to provide a simple generic interface between beyond-the-standard-model parton-level and event-level generators. All relevant information--particle content, quantum numbers of new states, masses, cross sections, parton-level events, etc.--is collected in one single file, which adheres to the Les Houches Event File (LHEF) standard.
Date: December 1, 2007
Creator: Alwall, J.; Boos, E.; Dudko, L.; Gigg, M.; Herquet, M.; Pukhov, A. et al.
Partner: UNT Libraries Government Documents Department

Light Kaluza Klein States in Randall-Sundrum Models with Custodial SU(2)

Description: We consider Randall-Sundrum scenarios based on SU(2){sub L} x SU(2){sub R} and a discrete parity exchanging L with R. The custodial and parity symmetries can be used to make the tree level contribution to the T parameter and the anomalous couplings of the bottom quark to the Z very small. We show that the resulting quantum numbers typically induce a negative T parameter at one loop that, together with the positive value of the S parameter, restrict considerably these models. There are nevertheless regions of parameter space that successfully reproduce the fit to electroweak precision observables with light Kaluza-Klein excitations accessible at colliders. We consider models of gauge-Higgs unification that implement the custodial and parity symmetries and find that the electroweak data singles out a very well defined region in parameter space. In this region one typically finds light gauge boson Kaluza-Klein excitations as well as light SU(2){sub L} singlet, and sometimes also doublet, fermionic states, that mix with the top quark, and that may yield interesting signatures at future colliders.
Date: July 1, 2006
Creator: Carena, Marcela; Ponton, Eduardo; Santiago, Jose & Wagner, Carlos E. M.
Partner: UNT Libraries Government Documents Department

Efficient analytic computation of higher-order QCD amplitudes

Description: The authors review techniques simplifying the analytic calculation of one-loop QCD amplitudes with many external legs, for use in next-to-leading-order corrections to multi-jet processes. Particularly useful are the constraints imposed by perturbative unitarity, collinear singularities and a supersymmetry-inspired organization of helicity amplitudes. Certain sequences of one-loop helicity amplitudes with an arbitrary number of external gluons have been obtained using these constraints.
Date: March 1, 1995
Creator: Bern, Z.; Chalmers, G.; Dixon, L.; Dunbar, D.C. & Kosower, D.A.
Partner: UNT Libraries Government Documents Department

Single sector supersymmetry breaking

Description: We review recent work on realistic models that break supersymmetry dynamically and give rise to composite quarks and leptons, all in a single sector. These models have a completely natural suppression of flavor-changing neutral currents, and the hierarchy of Yukawa couplings is explained by the dimensionality of composite states. The generic signatures are unification of scalar masses with different quantum numbers at the compositeness scale, and lighter gaugino, Higgsino, and third-generation sfermion masses.
Date: March 18, 1999
Creator: Luty, Markus A. & Terning, John
Partner: UNT Libraries Government Documents Department

Improved single sector supersymmetry breaking

Description: Building on recent work by N. Arkani-Hamed and the present authors, we construct realistic models that break supersymmetry dynamically and give rise to composite quarks and leptons, all in a single strongly-coupled sector. The most important improvement compared to earlier models is that the second-generation composite states correspond to dimension-2 ''meson'' operators in the ultraviolet. This leads to a higher scale for flavor physics, and gives a completely natural suppression of flavor-changing neutral currents. We also construct models in which the hierarchy of Yukawa couplings is explained by the dimensionality of composite states. These models provide an interesting and viable alternative to gravity- and gauge-mediated models. The generic signatures are unification of scalar masses with different quantum numbers at the compositeness scale, and lighter gaugino, Higgsino, and third-generation squark and slepton masses. We also analyze large classes of models that give rise to both compositeness and supersymmetry breaking, based on gauge theories with confining, fixed-point, or free-magnetic dynamics.
Date: December 9, 1998
Creator: Luty, Markus A. & Terning, John
Partner: UNT Libraries Government Documents Department

2-pi Photoproduction from CLAS and CB-ELSA - The Search for Missing Resonances

Description: 2-pi-photoproduction is one of the promising reactions to search for baryon resonances that have been predicted but have not yet been observed. The gamma-rho --> rho-pi{sup 0}-pi{sup 0}(CB-ELSA) and the gamma-rho --> rho-pi{sup +}-pi{sup -} (CLAS) data show interesting resonance structures. A partial wave analysis (PWA) has to be done to determine which baryon resonances contribute what their quantum numbers and their relative couplings to the different accessible rho-2-pi-channels and to the photon are. First preliminary PWA-results on the lowest energy rho-pi{sup 0}-pi{sup 0} data (sq rt s<1.8 GeV)look very promising. From an extension of this analysis to higher energies combining the rho-pi{sup 0}-pi{sup 0} and the rho-pi{sup +}-pi{sup -}-data, one can expect; interesting results on resonances decaying into Delta-pi, N-rho, N(pi-pi)s, N*-pi, and Delta*-pi.
Date: October 1, 2003
Creator: Thoma, Ulrike
Partner: UNT Libraries Government Documents Department

Sfermion precision measurements at a linear collider

Description: At future e{sup +}e{sup -} linear colliders, the event rates and clean signals of scalar fermion production--in particular for the scalar leptons--allow very precise measurements of their masses and couplings and the determination of their quantum numbers. Various methods are proposed for extracting these parameters from the data at the sfermion thresholds and in the continuum. At the same time, NLO radiative corrections and non-zero width effects have been calculated in order to match the experimental accuracy. The substantial mixing expected for the third generation sfermions opens up additional opportunities. Techniques are presented for determining potential CP-violating phases and for extracting tan {beta} from the stau sector, in particular at high values. The consequences of possible large mass differences in the stop and sbottom system are explored in dedicated analyses.
Date: September 25, 2003
Creator: al., A. Freitas et
Partner: UNT Libraries Government Documents Department

Transition nucleon resonance electrocouplings from CLAS data on pi+pi-p electroproduction off protons.

Description: Electrocouplings of excited proton states with masses less than 1.8 GeV were determined for the first time from the CLAS data on {pi}{sup +}{pi}{sup -}p electroproduction at photon virtualities Q{sup 2} < 1.5 GeV {sup 2}. Electrocouplings were obtained from a combined fit of all available observables within the framework of a phenomenological reaction model. Accurate information on the Q{sup 2}-evolution of {gamma}{sub virt}NN* electrocouplings for many excited proton states with masses less than 1.8 GeV and at photon virtualities up to 1.5 GeV{sup 2} have become available from CLAS data on {pi}{sup +}{pi}{sup -}p electroproduction. These results open up new opportunities for theory to explore confinement mechanisms in the baryon sector through their manifestation in the structure of excited proton states of various quantum numbers, as it was outlined. The analysis reported here covers the range of photon virtualities, where both meson-baryon and quark degrees of freedom can be relevant. Our results on high lying N* electrocouplings for the first time make it possible to explore the transition from meson-baryon to quark degrees of freedom in the structure of excited proton states with masses above 1.6 GeV within the framework of dynamical coupled channel approaches under development in EBAC at Jefferson Lab.
Date: October 1, 2011
Creator: Mokeev, Victor
Partner: UNT Libraries Government Documents Department

A Les Houches Interface for BSM Generators

Description: We propose to combine and slightly extend two existing 'Les Houches Accords' to provide a simple generic interface between beyond-the-standard-model parton-level and event-level generators. All relevant information--particle content, quantum numbers of new states, masses, cross sections, parton-level events, etc.--is collected in one single file, which adheres to the Les Houches Event File (LHEF) standard.
Date: January 23, 2008
Creator: Alwall, J.; Boos, E.; Dudko, L.; Gigg, M.; Herquet, M.; Pukhov, A. et al.
Partner: UNT Libraries Government Documents Department

K+ p Multiparticle Production in the 30" NAL Hybrid Chamber at the Highest Possible Energy

Description: One of the unique features of NAL that cannot be duplicated elsewhere (i.e. at CERN-ISR) is the ability to make high energy neutrino beams and high energy meson beams, It appears that meson-proton interactions may have given us some insight into hadron structure because the asymmetry (2 quarks on 3) which one observes in them cannot be seen in proton-proton (3 quarks on 3) interactions. Although the asymmetry can be observed in {pi} p collisions, it is likely that more can be learned if the role played by a single quark or parton can be identified, In K{sup +}p interactions this becomes a possibility because one quark in the K{sup +} meson carries a strangeness quantum number which has potential for identification after the interaction by means of the K{sup o} decay signature.
Date: June 1, 1972
Creator: Diamond, R.N.; Erwin, A.R.; Thompson, M.A. & U., /Wisconsin
Partner: UNT Libraries Government Documents Department

Charge exchange {rho}{sup zero}{pi}{sup +} photoproduction and implications for searches of exotic meson

Description: The authors analyze the processes {rvec {gamma}} + p {r_arrow} {rho}{sup 0}{pi}{sup +}n at low momentum transfer focusing on a possibility of production of an exotic J{sup PC} = 1{-+} meson state. In particular they discuss polarization observables and conclude that linear photon polarization is instrumental for separating of the exotic wave.
Date: October 1, 1999
Creator: Afanasev, A.V. & Szczepaniak, A.P.
Partner: UNT Libraries Government Documents Department

Tunneling from super- to normal-deformed minima in nuclei.

Description: An excited minimum, or false vacuum, gives rise to a highly elongated superdeformed (SD) nucleus. A brief review of superdeformation is given, with emphasis on the tunneling from the false to the true vacuum, which occurs in the feeding and decay of SD bands. During the feeding process the tunneling is between hot states, while in the decay it is from a cold to a hot state. The {gamma} spectra connecting SD and normal-deformed (ND) states provide information on several physics issues: the decay mechanism; the spin/parity quantum numbers, energies and microscopic structures of SD bands; the origin of identical SD bands; the quenching of pairing with excitation energy; and the chaoticity of excited ND states at 2.5-5 MeV. Other examples of tunneling in nuclei, which are briefly described, include the possible role of tunneling in {Delta}I = 4 bifurcation in SD bands, sub-barrier fusion and proton emitters.
Date: January 8, 1998
Creator: Khoo, T. L.
Partner: UNT Libraries Government Documents Department

Boundary conditions on internal three-body wave functions

Description: For a three-body system, a quantum wave function {Psi}{sub m}{sup {ell}} with definite {ell} and m quantum numbers may be expressed in terms of an internal wave function {chi}{sub k}{sup {ell}} which is a function of three internal coordinates. This article provides necessary and sufficient constraints on {chi}{sub k}{sup {ell}} to ensure that the external wave function {Psi}{sub k}{sup {ell}} is analytic. These constraints effectively amount to boundary conditions on {chi}{sub k}{sup {ell}} and its derivatives at the boundary of the internal space. Such conditions find similarities in the (planar) two-body problem where the wave function (to lowest order) has the form r{sup |m|} at the origin. We expect the boundary conditions to prove useful for constructing singularity free three-body basis sets for the case of nonvanishing angular momentum.
Date: October 1, 1999
Creator: Mitchell, Kevin A. & Littlejohn, Robert G.
Partner: UNT Libraries Government Documents Department

Meson spectroscopy with unitary coupled-channels model for heavy-meson decay into three mesons

Description: We develop a model for describing excited mesons decay into three mesons. The properties of the excited mesons can be extracted with this model. The model maintains the three-body unitarity that has been missed in previous data analyses based on the conventional isobar models. We study an importance of the three-body unitarity in extracting hadron properties from data. For this purpose, we use the unitary and isobar models to analyze the same pseudo data of {gamma}p {yields} {pi}{sup +}{pi}{sup +}{pi}{sup -}n, and extract the properties of excited mesons. We find a significant difference between the unitary and isobar models in the extracted properties of excited mesons, such as the mass, width and coupling strength to decay channels. Hadron properties such as quantum numbers (spin, parity, etc.), mass and (partial) width have been long studied as a subject called hadron spectroscopy. The hadron properties provide important information for understanding internal structure of the hadron and dynamics which governs it. The dynamics here is of course QCD in its nonperturbative regime. The hadron properties can be extracted from data through a careful analysis, in many cases, partial wave analysis (PWA). Thus it is essential for hadron spectroscopy to have a reliable theoretical analysis tool.
Date: April 1, 2012
Creator: Nakamura, Satoshi
Partner: UNT Libraries Government Documents Department

Excited light isoscalar mesons from lattice QCD

Description: I report a recent lattice QCD calculation of an excited spectrum of light isoscalar mesons, something that has up to now proved challenging for lattice QCD. With novel techniques we extract an extensive spectrum with high statistical precision, including spin-four states and, for the first time, light isoscalars with exotic quantum numbers. In addition, the hidden flavour content of these mesons is determined, providing a window on annihilation dynamics in QCD. I comment on future prospects including applications to the study of resonances.
Date: July 1, 2011
Creator: Thomas, Christopher
Partner: UNT Libraries Government Documents Department

Creating intense polarized electron beam via laser stripping and spin-orbit interaction

Description: The recent advance in laser field make it possible to excite and strip electrons with definite spin from hydrogen atoms. The sources of hydrogen atoms with orders of magnitude higher currents (than that of the conventional polarized electron cathods) can be obtained from H{sup -} sources with good monochromatization. With one electron of H{sup -} stripped by a laser, the remained electron is excited to upper state (2P{sup 3/2} and 2P{sup 1/2}) by a circular polarization laser light from FEL. Then, it is excited to a high quantum number (n=7) with mostly one spin direction due to energy level split of the states with a definite direction of spin and angular momentum in an applied magnetic field and then it is stripped by a strong electric field of an RF cavity. This paper presents combination of lasers and fields to get high polarization and high current electron source.
Date: December 1, 2010
Creator: Danilov, V.; Ptitsyn, V. & Gorlov, T.
Partner: UNT Libraries Government Documents Department

NUCLEAR COLLISIONS AT VERY HIGH ENERGY

Description: What do we know about nuclei? The literature of the last 20 or 30 years contains a wealth of fascinating detail about their structure, their energy levels and single particle aspects, their collective motion, and the way they interact with each other in collisions. Both the quantity and detail of the experimental data, and the sophistication of some of the theory is impressive. Yet what we know about nuclei concerns their properties at only one point on the graph of the equation of state of nuclear matter which is illustrated in Fig. 1. Aside from the trivial point at the origin, and the energy per nucleon at normal density, the curve drawn is a guess. The point where it crosses the axis at {rho}/{rho}{sub 0} {approx} 2 is based on nuclear matter calculations. We do not even know the curvature (compressibility) at normal density. Virtually everything we know about nuclei concerns their normal state. Some interesting possibilities for the state of nuclear matter at high density are illustrated in Fig. 1. The Lee-Wick super dense state is illustrated, as is the effect of a phase transition, corresponding to a situation where a state of special correlation having the quantum numbers of the pion (pion condensate) becomes degenerate with ground state. Perhaps the ultimate goal of research with relativistic energy nuclei is to study nuclear matter under abnormal conditions of high particle and energy density. This is a break from the past. Nuclear physicists have concentrated on studying nuclei under normal conditions of low energy and temperature. High energy physicists have concentrated on putting higher and higher energy into a small volume. We do not know what surprises await us, but several possible rewards are mentioned in this paper. To make it plausible why we expect to encounter new and interesting ...
Date: August 1, 1977
Creator: Glendenning, N.K.
Partner: UNT Libraries Government Documents Department

Electron Density Measurements in the National Spherical Torus Experiment Detached Divertor Region Using Stark Broadening of Deuterium Infrared Paschen Emission Lines

Description: Spatially resolved measurements of deuterium Balmer and Paschen line emission have been performed in the divertor region of the National Spherical Torus Experiment using a commercial 0.5 m Czerny-Turner spectrometer. While the Balmer emission lines, Balmer and Paschen continua in the ultraviolet and visible regions have been extensively used for tokamak divertor plasma temperature and density measurements, the diagnostic potential of infrared Paschen lines has been largely overlooked. We analyze Stark broadening of the lines corresponding to 2-n and 3-m transitions with principle quantum numbers n = 7-12 and m = 10-12 using recent Model Microfield Method calculations (C. Stehle and R. Hutcheon, Astron. Astrophys. Supl. Ser. 140, 93 (1999)). Densities in the range (5-50) x 10{sup 19} m{sup -3} are obtained in the recombining inner divertor plasma in 2-6 MW NBI H-mode discharges. The measured Paschen line profiles show good sensitivity to Stark effects, and low sensitivity to instrumental and Doppler broadening. The lines are situated in the near-infrared wavelength domain, where optical signal extraction schemes for harsh nuclear environments are practically realizable, and where a recombining divertor plasma is optically thin. These properties make them an attractive recombining divertor density diagnostic for a burning plasma experiment.
Date: April 27, 2007
Creator: Soukhanovskii, V A; Johnson, D W; Kaita, R & Roquemore, A L
Partner: UNT Libraries Government Documents Department