Showing 1 - 10 of 179 Items

Date: 2021-02-01

Creator: Stephen G. Naculich

Access: Open access

We examine in detail the structure of the Regge limit of the (nonplanar) N = 4 SYM four-point amplitude. We begin by developing a basis of color factors Cik suitable for the Regge limit of the amplitude at any loop order, and then calculate explicitly the coefficients of the amplitude in that basis through three-loop order using the Regge limit of the full amplitude previously calculated by Henn and Mistlberger. We compute these coefficients exactly at one loop, through O(ϵ 2) at two loops, and through O(ϵ) at three loops, verifying that the IR-divergent pieces are consistent with (the Regge limit of) the expected infrared divergence structure, including a contribution from the three-loop correction to the dipole formula. We also verify consistency with the IR-finite NLL and NNLL predictions of Caron-Huot et al. Finally we use these results to motivate the conjecture of an all-orders relation between one of the coefficients and the Regge limit of the N = 8 supergravity four-point amplitude.

Date: 2018-03-01

Creator: Robert W. Brown, Stephen G. Naculich

Access: Open access

Color-factor symmetry is used to derive a KLT-type relation for tree-level QCD amplitudes containing gluons and an arbitrary number of massive or massless quark-antiquark pairs, generalizing the expression for Yang-Mills amplitudes originally postulated by Bern, De Freitas, and Wong. An explicit expression is given for all amplitudes with two or fewer quark-antiquark pairs in terms of the (modified) momentum kernel. We also introduce the bicolor scalar theory, the “zeroth copy” of QCD, containing massless biadjoint scalars and massive bifundamental scalars, generalizing the biadjoint scalar theory of Cachazo, He, and Yuan. We derive KLT-type relations for tree-level amplitudes of biadjoint and bicolor theories using the color-factor symmetry possessed by these theories.

Date: 2012-05-21

Creator: Alexander C. Edison, Stephen G. Naculich

Access: Open access

Color-ordered amplitudes for the scattering of n particles in the adjoint representation of SU(N) gauge theory satisfy constraints arising solely from group theory. We derive these constraints for n=.5 at all loop orders using an iterative approach. These constraints generalize well-known tree-level and one-loop group theory relations. © 2012 Elsevier B.V.

Date: 2012-01-01

Creator: Alexander C. Edison, Stephen G. Naculich

Access: Open access

Color-ordered amplitudes for the scattering of n particles in the adjoint representation of SU(N) gauge theory satisfy constraints that arise from group theory alone. These constraints break into subsets associated with irreducible representations of the symmetric group Sn, which allows them to be presented in a compact and natural way. Using an iterative approach, we derive the constraints for six-point amplitudes at all loop orders, extending earlier results for n = 4 and n = 5. We then decompose the four-, five-, and six-point group-theory constraints into their irreducible Sn subspaces. We comment briefly on higher-point two-loop amplitudes. © SISSA 2012.

Date: 1992-01-01

Creator: S. Henderson, K. Kinoshita, F. Pipkin, M. Procario, M., Saulnier, R. Wilson, J. Wolinski, D. Xiao, R. Ammar, P. Baringer, D. Coppage, R. Davis, P. Haas, M. Kelly, N. Kwak, Ha Lam, S. Ro, Y. Kubota, J. K. Nelson, D. Perticone, R. Poling, S. Schrenk, G. Crawford, R. Fulton, T. Jensen, D. R. Johnson, H. Kagan, R. Kass, R. Malchow, F. Morrow, J. Whitmore

Access: Open access

We report new measurements of semileptonic branching fractions of B mesons produced at the '(4S) resonance determined by fitting the inclusive electron and muon momentum spectra to different theoretical models. Using B(B»'X"-») to denote the average of the semileptonic branching fractions for B decay to electrons and muons, we obtain B(B»'X"-»)= (10.5±0.2±0.4)% using the refined free-quark model of Altarelli et al., and B(B»'X"-»)=(11.2±0.3±0.4)% using a modified version of the form-factor model of Isgur et al., in which the D**"-» contribution is allowed to float in the fit. The average of these two results is B(B»'X"-»)=(10.8±0. 2±0.4±0.4)%, where the errors are statistical, systematic uncertainties in the measurement, and systematic uncertainties associated with the theoretical models, respectively. Semileptonic branching fractions as low as this are difficult to accommodate in theoretical models where hadronic B-meson decays arise only from spectator diagrams. We use dilepton yields to limit the uncertainty in the semileptonic branching fraction due to the possible existence of non-BB» decays of the '(4S). In addition, we tag neutral B mesons using the decays B»0'D*+- and B»0'D*+"-» to obtain the first direct measurement of semileptonic branching fractions for neutral B mesons; the average of the electron and muon results for neutral B mesons is B(B»0'X"-»)=(9.9±3.0±0.9)%. © 1992 The American Physical Society.

Date: 1992-01-01

Creator: G. Crawford, R. Fulton, T. Jensen, D. R. Johnson, H., Kagan, R. Kass, R. Malchow, F. Morrow, J. Whitmore, P. Wilson, D. Bortoletto, D. Brown, J. Dominick, R. L. McIlwain, D. H. Miller, M. Modesitt, C. R. Ng, S. F. Schaffner, E. I. Shibata, I. P.J. Shipsey, M. Battle, H. Kroha, K. Sparks, E. H. Thorndike, C. H. Wang, M. S. Alam, I. J. Kim, W. C. Li, X. C. Lou, B. Nemati, V. Romero

Access: Open access

Using the CLEO detector at the Cornell Electron Storage Ring, we observe B-meson decays to c+ and report on improved measurements of inclusive branching fractions and momentum spectra of other baryons. For the inclusive decay Bc+X with c+pK-+, we find that the product branching fraction B(Bc+X)B(c+pK-+)=(0.273±0.051±0.039)%. Our measured inclusive branching fractions to noncharmed baryons are B(BpX)=(8.0±0.5±0.3)%, B(BX)=(3.8±0.4±0.6)%, and B(B-X)=(0.27±0.05±0.04)%. From these rates and studies of baryon-lepton and baryon-antibaryon correlations in B decays, we have estimated the branching fraction B(Bc+X) to be (6.40.8±0.8)%. Combining these results, we calculate B(c+pK-) to be (4.3±1.0±0.8)%. © 1992 The American Physical Society.

Date: 1992-01-01

Creator: J. Alexander, C. Bebek, K. Berkelman, D. Besson, T. E., Browder, D. G. Cassel, E. Cheu, D. M. Coffman, P. S. Drell, R. Ehrlich, R. S. Galik, M. Garcia-Sciveres, B. Geiser, B. Gittelman, S. W. Gray, D. L. Hartill, B. K. Heltsley, K. Honscheid, J. Kandaswamy, N. Katayama, P. C. Kim, D. L. Kreinick, J. D. Lewis, G. S. Ludwig, J. Masui, J. Mevissen, N. B. Mistry, S. Nandi, C. R. Ng, E. Nordberg, C. Grady

Access: Open access

Using the CLEO II detector, we have accurately measured Ds decay branching ratios relative to the mode for the and states, for which there are conflicting claims; our results are 0.540.090.06 and 1.200.150.11, respectively. © 1992 The American Physical Society.

Date: 1993-01-01

Creator: M. Procario, S. Yang, R. Balest, K. Cho, M., Daoudi, W. T. Ford, D. R. Johnson, K. Lingel, M. Lohner, P. Rankin, J. G. Smith, J. P. Alexander, C. Bebek, K. Berkelman, D. Besson, T. E. Browder, D. G. Cassel, H. A. Cho, D. M. Coffman, P. S. Drell, R. Ehrlich, R. S. Galik, M. Garcia-Sciveres, B. Geiser, B. Gittelman, S. W. Gray, D. L. Hartill, B. K. Heltsley, K. Honscheid, C. D. Jones, S. L. Jones

Access: Open access

With the CLEO-II detector at the Cornell Electron Storage Ring, we have measured branching fractions for tau lepton decay into one-prong final states with multiple π0's Bhnπ0, normalized to the branching fraction for tau decay into one charged particle and a single π0. We find Bh2π0/Bhπ0=0. 345±0.006±0.016, Bh3π0/Bhπ0=0.041 ±0.003±0. 005, and Bh4π0/Bhπ0=0.006±0.002±0.002. © 1993 The American Physical Society.

Date: 1991-01-01

Creator: K. Kinoshita, F. M. Pipkin, M. Procario, Richard Wilson, J., Wolinski, D. Xiao, Y. Zhu, R. Ammar, P. Baringer, D. Coppage, R. Davis, P. Haas, M. Kelly, N. Kwak, Ha Lam, S. Ro, Y. Kubota, J. K. Nelson, D. Perticone, R. Poling, S. Schrenk, G. Crawford, R. Fulton, T. Jensen, D. R. Johnson, H. Kagan, R. Kass, R. Malchow, F. Morrow, J. Whitmore, P. Wilson

Access: Open access

We have made measurements of decay modes of neutral D mesons into exclusive final states containing photons using data collected with the CLEO detector at the Cornell Electron Storage Ring. We report observation of D0'K-+-+0 (charge conjugates are implicit), and present new measurements of the branching ratios for D0'K-+0, D0'K0+0-, D0'K00, K*0, and D0'K0. Where possible, results are compared with theoretical predictions for two-body D0 decays. © 1991 The American Physical Society.

Date: 1991-01-01

Creator: R. Fulton, T. Jensen, D. R. Johnson, H. Kagan, R., Kass, F. Morrow, J. Whitmore, P. Wilson, D. Bortoletto, W. Y. Chen, J. Dominick, R. L. McIlwain, D. H. Miller, C. R. Ng, S. F. Schaffner, E. I. Shibata, I. P.J. Shipsey, W. M. Yao, M. Battle, K. Sparks, E. H. Thorndike, C. H. Wang, M. S. Alam, I. J. Kim, W. C. Li, V. Romero, C. R. Sun, P. N. Wang, M. M. Zoeller, M. Goldberg, T. Haupt

Access: Open access

We report new measurements of the branching fractions B. Combining these results with our previous measurement of BD*+l we find that the ratio of semileptonic widths for final states with a vector meson and pseudoscalar meson is (2.6-0.6-0.8+1.1+1.0) and the ratio of charged- to neutral-B-meson lifetimes is (0.89±0.19±0.13)(f00f+-) where (f00f+-) is the ratio of neutral- to charged-B-meson production at the branching fraction, we calculate |Vcb|=0.040±0.006±0.006, where the first error is statistical and the second is systematic and dominated by the uncertainty in the B-meson lifetime. © 1991 The American Physical Society.