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MULTIPERIPHERAL MODEL WITH PSEUDOSCALAR AND VECTOR MESON EXCHANGE

Description: Previous work on generalizations of the ABFST multiperipheral model is extended to allow for vector meson exchange. The intercept of the Pomeranchon pole, the magnitude of asymptotic total cross sections and off-shell corrections to them are calculated.
Date: September 1, 1972
Creator: Avalos, Daniel R. & Sorensen, Cristian.
Partner: UNT Libraries Government Documents Department

Hadron Spectroscopy Program with CLAS g12

Description: Some conclusions from this presentation are: (1) previous CLAS result on exotic {pi}{sub 1}(1600)/{alpha}{sub 2}(1320) in photoproduction confirmed with higher statistics; (2) previous CLAS result on {gamma}p {yields} pentaquark not confirmed with higher statistics; (3) high luminosity allows exploitation of rare topologies {gamma}p {yields} {phi}{pi}{sup 0}p, {phi}{eta}p, {phi}{omega}p; (4) no observation of any {Xi}* states above 1530 MeV recoiling off of K{sup +}K{sup +} lepton detection permits high statistic study of pseudoscalar dalitz decay; and (5) first observation of {eta}' Dalitz decay, {rho}-{omega} interference via e{sup +}e{sup -} channel.
Date: December 1, 2011
Creator: Weygand, Dennis
Partner: UNT Libraries Government Documents Department

Recent Results on Charm and Tau Physics from BaBar And Belle

Description: Recent results on charm and tau physics obtained at the BABAR and Belle experiments are presented in this article. The charm section will be focused on the most recent results on D{sup 0}{bar D}{sup 0} mixing at Belle and on the measurement of the pseudoscalar decay constant f{sub Ds} using charm tagged e+e- events at BABAR. In the tau section the recent results on Lepton Flavor Violation from tau decays will be discussed, as well as the recent result on the rare decay {tau}{sup -} {yields} 3{pi}{sup -}2{pi}{sup +}2{pi}{sup 0}{nu}{sub {tau}} at BABAR and the measurement of the {tau} lepton mass at Belle.
Date: October 15, 2007
Creator: Salvatore, Fabrizio F. & /Royal Holloway, U. of London
Partner: UNT Libraries Government Documents Department

GammeV: A gamma to milli-eV particle search at Fermilab

Description: GammeV is an experiment conducted at Fermilab that employs the light shining through a wall technique to search for axion-like particles and employs a particle in a jar technique to search for dilaton-like chameleon particles. We obtain limits on the coupling of photons to an axion-like particle that extend previous limits for both scalars and pseudoscalars in the milli-eV mass range. We are able to exclude the axion-like particle interpretation of the anomalous PVLAS 2006 result by more than 5 standard deviations. We also present results on a search for chameleons and set limits on their possible coupling to photons.
Date: October 1, 2008
Creator: Wester, William Carl, III
Partner: UNT Libraries Government Documents Department

GammeV: Fermilab axion-like particle photon regeneration results

Description: GammeV is an axion-like particle photon regeneration experiment conducted at Fermilab that employs the light shining through a wall technique. They obtain limits on the coupling of a photon to an axion-like particle that extend previous limits for both scalar and pseudoscalar axion-like particles in the milli-eV mass range. They are able to exclude the axion-like particle interpretation of the anomalous PVLAS 2006 result by more than 5 standard deviations.
Date: September 1, 2008
Creator: Wester, William
Partner: UNT Libraries Government Documents Department

Radiative Decays, Nonet Symmetry and SU(3) Breaking

Description: We re-examine the problem of simultaneously describing in a consistent way all radiative and leptonic decays of light mesons (V {yields} P{gamma}, P {yields} V{gamma}, P {yields} {gamma}{gamma}, V {yields} e{sup +}e{sup -}). For this purpose, we rely on the Hidden Local Symmetry model in both its anomalous and non-anomalous sectors. We show that the SU(3) symmetry breaking scheme proposed by Bando, Kugo and Yamawaki, supplemented with nonet symmetry breaking in the pseudoscalar sector, allows one to reach a nice agreement with all data, except for the K*{sup {+-}} radiative decay. An extension of this breaking pattern allows one to account for this particular decay mode too. Considered together, the whole set of radiative decays provides a pseudoscalar mixing angle {theta}{sub P} {approx_equal} and a value for {theta}{sub V} which is {approx_equal} 3{sup o} from that of ideal mixing. We also show that it is impossible, in a practical sense, to disentangle the effects of nonet symmetry breaking and those of glue inside the {eta}{prime}, using only light meson decays.
Date: June 30, 1999
Creator: O'Connell, Heath B
Partner: UNT Libraries Government Documents Department

{rho} Polarization and Model Independent Extraction of |V{sub ub}|/|V{sub cd}| from D--> {rho}{ell}{nu}and B--> {rho}{ell}{nu}

Description: We briefly discuss the predictions of the heavy quark effective theory for the semileptonic decays of a heavy pseudoscalar to a light one, or to a light vector meson. We point out that measurement of combinations of differential helicity decay rates at Cleo-c and the B factories can provide a model independent means of extracting the ratio |V{sub ub}|/|V{sub cd}|. We briefly discuss the corrections to this prediction.
Date: April 1, 2002
Creator: Roberts, Winston
Partner: UNT Libraries Government Documents Department

Quenched Chiral Log and Light Quark Mass from Overlap Fermions

Description: We study the quenched chiral behavior of the pion with mass as low as {approx} 180 MeV. The calculation is done on a quenched lattice of size 16{sup 3} x 28 and a = 0.2 fm with 80 configurations using overlap fermions and an improved gauge action. Using an improved constrained curve fitting technique, we find that the ground state pseudoscalar mass versus bare quark mass behavior is well controlled with small statistical errors; this permits a reliable fit of the quenched chiral log effects, a determination of the chiral log parameter ({delta} = 0.26(3)), and an estimate of the renormalized mass of the light quark (m{sup {ovr MS}}({mu} = 2 GeV) = 3.7(3) MeV).
Date: June 1, 2002
Creator: Draper, Terrence; Dong, Shao-Jing; Horvath, Ivan; Lee, Frank; Liu, Keh-Fei; Mathur, Nilmani et al.
Partner: UNT Libraries Government Documents Department

Search for NMSSM Higgs bosons in the h ---> aa ---> mu mu mu mu, mu mu tau tau channels using p anti-p collisions at s**(1/2) = 1.96-TeV

Description: We report on a first search for production of the lightest neutral CP-even Higgs boson (h) in the next-to-minimal supersymmetric standard model, where h decays to a pair of neutral pseudoscalar Higgs bosons (a), using 4.2 fb{sup -1} of data recorded with the D0 detector at Fermilab. The a bosons are required to either both decay to {mu}{sup +}{mu}{sup -} or one to {mu}{sup +}{mu}{sup -} and the other to {tau}{sup +}{tau}{sup -}. No significant signal is observed, and we set limits on its production as functions of M{sub a} and M{sub h}.
Date: May 1, 2009
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Partner: UNT Libraries Government Documents Department

Test of Lepton Universality in Upsilon(1S) Decays at BaBar

Description: The ratio R{sub {tau}{mu}}({Upsilon}(1S))={Lambda}{sub {Upsilon}(1S){yields}{tau}{sup +}{tau}{sup -}}/{Lambda}{sub {Upsilon}(1S){yields}{mu}{sup +}{mu}{sup -}} is measured using a sample of (121.8 {+-} 1.2) x 10{sup 6}{Upsilon}(3S) events recorded by the BABAR detector. This measurement is intended as a test of lepton universality and as a search for a possible light pseudoscalar Higgs boson. In the standard model (SM) this ratio is expected to be close to 1. Any significant deviations would violate lepton universality and could be introduced by the coupling to a light pseudoscalar Higgs boson. The analysis studies the decays {Upsilon}(3S) {yields} {Upsilon}(1S){sub {pi}{sup +}{pi}{sup -}}, {Upsilon}(1S) {yields} {ell}{sup +}{ell}{sup -}, where l = {mu}, {tau}. The result, R{sub {tau}{mu}}({Upsilon}(1S))=1.005 {+-} 0.013(stat) {+-} 0.022(syst), shows no deviation from the expected SM value, while improving the precision with respect to previous measurements.
Date: June 7, 2010
Creator: del Amo Sanchez, P.; Lees, J.P.; Poireau, V.; Prencipe, E.; Tisserand, V.; /Annecy, LAPP et al.
Partner: UNT Libraries Government Documents Department

Measurement of the Branching Fraction for D8+ rarr tau+nu_tau and Extraction of the Decay Constant f_D_s

Description: The branching fraction for the decay D{sub s}{sup +} {yields} {tau}{sup +}{nu}{sub {tau}} with {tau}{sup +} {yields} e{sup +}{bar {nu}}{sub {tau}}, is measured using a data sample corresponding to an integrated luminosity of 427 fb{sup -1} collected at center of mass energies near 10.58 GeV with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at SLAC. In the process e{sup +}e{sup -} {yields} c{bar c} {yields} D*{sub s}{sup +} {bar D}{sub TAG}{bar K}X, the D*{sub s}{sup +} meson is reconstructed as a missing particle, and the subsequent decay D*{sub s}{sup +} {yields} D{sub s}{sup +}{gamma} yields an inclusive D{sub s}{sup +} data sample. Here {bar D}{sub TAG} refers to a fully reconstructed hadronic {bar D} decay, {bar K} is a K{sup -} or {bar K}{sup 0}, and X stands for any number of charged or neutral pions. The decay D{sub s}{sup +} {yields} K{sub S}{sup 0}K{sup +} is isolated also, and from ratio of event yields and known branching fractions, {Beta}(D{sub s}{sup +} {yields} {tau}{sup +}{nu}{sub {tau}}) = (4.5 {+-} 0.5 {+-} 0.4 {+-} 0.3)% is determined. The pseudoscalar decay constant is extracted to be f{sub D{sub s}} = (233 {+-} 13 {+-} 10 {+-} 7) MeV, where the first uncertainty is statistical, the second is systematic, and the third results from the uncertainties on the external measurements used as input to the calculation.
Date: June 4, 2010
Creator: Lees, J.P.; Poireau, V.; Prencipe, E.; Tisserand, V.; /Annecy, LAPP; Garra Tico, J. et al.
Partner: UNT Libraries Government Documents Department

VMD, the WZW Lagrangian and ChPT:The Third Mixing Angle

Description: We show that the Hidden Local Symmetry Model, supplemented with well-known procedures for breaking flavor SU(3) and nonet symmetry, provides all the information contained in the standard Chiral Perturbation Theory (ChPT) Lagrangian L{sup (0)} + L{sup (1)}. This allows to rely on radiative decays of light mesons (VP{gamma} and P{gamma}{gamma}) in order to extract some numerical information of relevance to ChPT: a value for {Lambda}{sub 1} = 0.20 {+-} 0.04, a quark mass ratio of {approx_equal} 21.2 {+-} 2.4, and a negligible departure from the Gell-Mann--Okubo mass formula. The mixing angles are {theta}{sub 8} = {minus}20.40{degree} {+-} 0.96{degree} and {theta}{sub 0} = {minus}0.05{degree} {+-} 0.99{degree}. We also give the values of all decay constants. It is shown that the common mixing pattern with one mixing angle {theta}{sub P} is actually quite appropriate and algebraically related to the {eta}/{eta}{prime} mixing pattern presently preferred by the ChPT community. For instance the traditional {theta}{sub p} is functionally related to the ChPT {theta}{sub 8} and fulfills {theta}{sub P} {approx_equal} {theta}{sub 8}/2. The vanishing of {theta}{sub 0}, supported by all data on radiative decays, gives a novel relation between mixing angles and the violation of nonet symmetry in the pseudoscalar sector. Finally, it is shown that the interplay of nonet symmetry breaking through U(3) {r_arrow} SU(3) x U(1) satisfies all requirements of the physics of radiative decays without any need for additional glueballs.
Date: March 31, 1999
Creator: O'Connell, Heath B
Partner: UNT Libraries Government Documents Department

Effects of Light Scalar Mesons in eta -> 3pi decay

Description: We study the role of a possible nonet of light scalar mesons in the still interesting [eta] -> 3[p]i decay process, with the primary motivation of learning more about the scalars themselves. The framework is a conventional non-linear chiral Lagrangian of pseudoscalars and vectors extended to include the scalars. The parameters involving the scalars were previously obtained to fit the s-wave [pi][pi] and [pi] K scatterings in the region up to about 1 GeV as well as the strong decay [eta]' --> [eta][pi][pi]. At first, one might expect a large enhancement from diagrams including a light [sigma] (560). However there is an amusing cancellation mechanism which prevents this from occurring. In the simplest model there is an enhancement of about 13 per cent in the [eta] -> 3[pi] decay rate due to the scalars. In a more complicated model which includes derivative type symmetry breakers, the cancellation is modified and the scalars contribute about 30 percent of the total decay rate (although the total is not significantly changed). The vectors do not contribute much. Our model produces a reasonable estimate for the related a{sub 0}(980) - f{sub 0}(980) mixing strength, which has been a topic of current debate. Promising directions for future work along the present line are suggested.
Date: October 1, 2002
Creator: Abdel-Rehim, Abdou; Black, Deirdre; Fariborz, Amir H. & Schechter, Joseph
Partner: UNT Libraries Government Documents Department

Chiral effective field theory predictions for muon capture on deuteron and $^3$He

Description: The muon-capture reactions {sup 2}H({mu}{sup -}, {nu}{sub {mu}})nn and {sup 3}He({mu}{sup -},{nu}{sub {mu}}){sup 3}H are studied with nuclear strong-interaction potentials and charge-changing weak currents, derived in chiral effective field theory. The low-energy constants (LEC's) c{sub D} and c{sub E}, present in the three-nucleon potential and (c{sub D}) axial-vector current, are constrained to reproduce the A=3 binding energies and the triton Gamow-Teller matrix element. The vector weak current is related to the isovector component of the electromagnetic current via the conserved-vector-current constraint, and the two LEC's entering the contact terms in the latter are constrained to reproduce the A=3 magnetic moments. The muon capture rates on deuteron and {sup 3}He are predicted to be 399 {+-} 3 sec{sup -1} and 1494 {+-} 21 sec{sup -1}, respectively, where the spread accounts for the cutoff sensitivity as well as uncertainties in the LEC's and electroweak radiative corrections. By comparing the calculated and precisely measured rates on {sup 3}He, a value for the induced pseudoscalar form factor is obtained in good agreement with the chiral perturbation theory prediction.
Date: January 1, 2012
Creator: Laura E. Marcucci, A. Kievsky, S. Rosati, R. Schiavilla, M. Viviani
Partner: UNT Libraries Government Documents Department

A Measurement of the Rate of Muon Capture in Hydrogen Gas andDetermination of the Proton's Induced Pseudoscalar Coupling gP

Description: This dissertation describes a measurement of the rate ofnuclear muon capture by the proton, performed by the MuCap Collaborationusing a new technique based on a time projection chamber operating inultraclean, deuterium-depleted hydrogen gas at room temperature and 1 MPapressure. The hydrogen target's low gas density of 1 percent compared toliquid hydrogen is key to avoiding uncertainties that arise from theformation of muonic molecules. The capture rate was obtained from thedifference between the mu- disappearance rate in hydrogen--as determinedfrom data collected in the experiment's first physics run in fall2004--and the world averagefor the mu+ decay rate. After combining theresults of my analysis with the results from another independent analysisof the 2004 data, the muon capture rate from the hyperfine singlet groundstate of the mu-p atom is found to be Lambda_S = 725.0 +- 17.4 1/s, fromwhich the induced pseudoscalar coupling of the nucleon, gP(q2 = -0.88m2mu)= 7.3 +- 1.1, is extracted. This result for gP is consistent withtheoretical predictions that are based on the approximate chiral symmetryof QCD.
Date: July 10, 2007
Creator: Banks, Thomas Ira
Partner: UNT Libraries Government Documents Department

Lepton Universality Test in Upsilon(1S) Decays at BaBar

Description: Using a sample of 122 million {Upsilon}(3S) decays collected with the BABAR detector at the PEP-II asymmetric energy collider at the SLAC National Accelerator Laboratory, we measure the ratio R{sub {tau}{mu}} = BR({Upsilon}(1S) {yields} {tau}{sup +}{tau}{sup -})/BR({Upsilon}(1S) {yields} {mu}{sup +}{mu}{sup -}); the measurement is intended as a test of lepton universality and as a possible search for a light pseudoscalar Higgs boson in Next to Minimal Supersymmetric Standard Model (NMSSM) scenarios. Such a boson could appear in a deviation of the ratio R{sub {tau}{mu}} from the Standard Model expectation, that is 1, except for small lepton mass corrections. The analysis exploits the decays {Upsilon}(3S) {yields} {Upsilon}(1S){pi}{sup +}{pi}{sup -}, {Upsilon}(1S) {yields} l{sup +}l{sup -}, where l = {mu},{tau}.
Date: April 10, 2012
Creator: Guido, Elisa & /Genoa U. /INFN, Genoa
Partner: UNT Libraries Government Documents Department

Discovering the Higgs Bosons of Minimal Supersymmetry with Tau Leptons and a Bottom Quark

Description: We investigate the prospects for the discovery at the CERN Large Hadron Collider or at the Fermilab Tevatron of neutral Higgs bosons through the channel where the Higgs are produced together with a single bottom quark and the Higgs decays into a pair of tau leptons, bg {yields} b{phi}{sup 0} {yields} b{tau}{sup +}{tau}{sup -}, {phi}{sup 0} = h{sup 0},H{sup 0},A{sup 0}. We work within the framework of the minimal supersymmetric model. The dominant physics background from the production of b{tau}{sup +}{tau}{sup -}, j{tau}{sup +}{tau}{sup -} (j = g, u, d, s, c), b{bar b}W{sup +}W{sup -}, W +2j and Wbj is calculated with realistic acceptance cuts and efficiencies. Promising results are found for the CP-odd pseudoscalar (A{sup 0}) and the heavier CP-even scalar (H{sup 0}) Higgs bosons with masses up to one TeV.
Date: November 7, 2007
Creator: Kao, Chung; Dicus, Duane; Malhotra, Rahul & Wang, Yili
Partner: UNT Libraries Government Documents Department

Measurement of the Pseudoscalar Decay Constantf_D_s Using Charm-Tagged Events in e+e- Collisions atsqrt{s}=10.58 GeV

Description: Using 230.2 fb{sup -1} of e{sup +}e{sup -} annihilation data collected with the BABAR detector at and near the peak of the {Upsilon}(4S) resonance, 489 {+-} 55 events containing the pure leptonic decay D{sub s}{sup +} {yields} {mu}{sup +}{nu}{sub {mu}} have been isolated in charm-tagged events. The ratio of partial widths {Lambda}(D{sub s}{sup +} {yields} {mu}{sup +}{nu}{sub {mu}})/{Lambda}(D{sub s}{sup +} {yields} {phi}{pi}{sup +}) is measured to be 0.143 {+-} 0.018 {+-} 0.006 allowing a determination of the pseudoscalar decay constant f{sub D{sub 2}} = (283 {+-} 17 {+-} 7 {+-} 14) MeV. The errors are statistical, systematic, and from the D{sub s}{sup +} {yields} {phi}{pi}{sup +} branching ratio, respectively.
Date: September 5, 2006
Creator: Aubert, B.
Partner: UNT Libraries Government Documents Department

Measurements of B to {pi, eta, eta'} l nu Branching Fractions andDetermination of |Vub| with Semileptonically Tagged B Mesons

Description: The authors report measurements of branching fractions for the decays B {yields} P{ell}{nu}{sub {ell}}, where P are the pseudoscalar charmless mesons {pi}{sup -}, {pi}{sup 0}, {eta} and {eta}{prime}, based on 348 fb{sup -1} of data collected with the BABAR detector, using B{sup 0} and B{sup +} mesons found in the recoil of a second B meson decaying as B {yields} D{sup (*)}{ell}{nu}{sub {ell}}. Assuming isospin symmetry, they combine pionic branching fractions to obtain {Beta}(B{sup 0} {yields} {pi}{sup -} {ell}{sup +} {nu}{sub {ell}}) = (1.54 {+-} 0.17{sub (stat)} {+-} 0.09{sub (syst)}) x 10{sup -4}; they find 3.2{sigma} evidence of the decay B{sup +} {yields} {eta}{ell}{sup +}{nu}{sub {ell}} and measure its branching fraction to be (0.64 {+-} 0.20{sub (stat)} {+-} 0.3{sub (syst)}) x 10{sup -4}, and determine {Beta}(B{sup +} {yields} {eta}{prime}{ell}{sup +}{nu}{sub {ell}}) < 0.47 x 10{sup -4} to 90% confidence level. Using partial branching fractions for the pionic decays in ranges of the momentum transfer and a recent form factor calculation, they obtain the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |V{sub ub}| = (4.0 {+-} 0.5{sub (stat)} {+-} 0.2{sub (syst){sub -0.5}{sup +0.7}(theory)}) x 10{sup -3}.
Date: June 2, 2008
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E. et al.
Partner: UNT Libraries Government Documents Department

Higgs Discovery in the Presence of Light CP-Odd Scalars

Description: Many models of electroweak symmetry breaking have an additional light pseudoscalar. If the Higgs boson can decay to a new pseudoscalar, LEP searches for the Higgs can be significantly altered and the Higgs can be as light as 86 GeV. Discovering the Higgs boson in these models is challenging when the pseudoscalar is lighter than 10 GeV because it decays dominantly into tau leptons. In this paper, we discuss discovering the Higgs in a subdominant decay mode where one of the pseudoscalars decays to a pair of muons. This search allows for potential discovery of a cascade-decaying Higgs boson with the complete Tevatron data set or early data at the LHC.
Date: June 19, 2009
Creator: Lisanti, Mariangela; Wacker, Jay G. & /SLAC /Stanford U., Phys. Dept.
Partner: UNT Libraries Government Documents Department

Search for Higgs bosons predicted in two-Higgs-doublet models via decays to tau lepton pairs in 1.96-TeV p anti-p collisions

Description: We present the results of a search for Higgs bosons predicted in two-Higgs-doublet models, in the case where the Higgs bosons decay to tau lepton pairs, using 1.8 fb{sup -1} of integrated luminosity of p{bar p} collisions recorded by the CDF II experiment at the Fermilab Tevatron. Studying the mass distribution in events where one or both tau leptons decay leptonically, no evidence for a Higgs boson signal is observed. The result is used to infer exclusion limits in the two-dimensional space of tan {beta} versus m{sub A} (the ratio of the vaccum expectation values of the two Higgs doublets and the mass of the pseudoscalar boson, respectively).
Date: June 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, Jahred A.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Partner: UNT Libraries Government Documents Department

Search for 14.4-KeV Solar Axions Emitted in the M1-Transition of Fe-57 Nuclei with CAST

Description: We have searched for 14.4 keV solar axions or more general axion-like particles (ALPs), that may be emitted in the M1 nuclear transition of 57Fe, by using the axion-to-photon conversion in the CERN Axion Solar Telescope (CAST) with evacuated magnet bores (Phase I). From the absence of excess of the monoenergetic X-rays when the magnet was pointing to the Sun, we set model-independent constraints on the coupling constants of pseudoscalar particles that couple to two photons and to a nucleon g{sub ay}|-1.19g{sub aN}{sup 0}+g{sub aN}{sup 3}| < 1.36 x 10{sup -16} GeV{sup -1} for ma < 0.03 eV at the 95% confidence level.
Date: December 2, 2011
Creator: Andriamonje, S.; Aune, S.; Autiero, D.; Barth, K.; Belov, A.; Beltran, B. et al.
Partner: UNT Libraries Government Documents Department

GammeV: results and future plans at Fermilab

Description: GammeV is an axion-like particle photo regeneration experiment that employs the light shining through a wall technique. We obtain limits on the coupling of a photon to an axion-like particle that extend previous limits for both scalar and pseudoscalar particles in the milli-eV mass range. We have reconfigured our apparatus to search for chameleon particles. We describe the current results and future plans for similar activities at Fermilab.
Date: May 1, 2010
Creator: Wester, William
Partner: UNT Libraries Government Documents Department