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The Role of the ILC in the Study of Cosmic Dark Matter

Description: Though there is strong evidence that dark matter is a major component of the universe, most aspects of dark matter are completely mysterious. We do not know what dark matter is, and we do not know how it is distributed in our galaxy. To resolve these and related questions, we will need information both from particle physics and from astrophysics. In this article, we will describe a path toward the solution of the problems of dark matter, and we will highlight the important role that the ILC has to play in this study.
Date: December 14, 2005
Creator: Battaglia, Marco; /LBL, Berkeley /UC, Berkeley; Peskin, Michael E. & /SLAC
Partner: UNT Libraries Government Documents Department

Conference Summary

Description: Summary of the conference, summarizing both theoretical and experimental presentations and discussions.
Date: November 9, 2005
Creator: Brodsky, Stanley J.; /SLAC; Rijssenbeek, Michael & /SUNY, Stony Brook
Partner: UNT Libraries Government Documents Department

Z' Phenomenology and the LHC

Description: A brief pedagogical overview of the phenomenology of Z{prime} gauge bosons is ILC in determining Z{prime} properties is also discussed. and explore in detail how the LHC may discover and help elucidate the models, review the current constraints on the possible properties of a Z{prime} nature of these new particles. We provide an overview of the Z{prime} studies presented. Such particles can arise in various electroweak extensions of that have been performed by both ATLAS and CMS. The role of the the Standard Model (SM). We provide a quick survey of a number of Z{prime}.
Date: October 17, 2006
Creator: Rizzo, Thomas G.
Partner: UNT Libraries Government Documents Department

The Role of Collinear Photons In the Rare Decay B to X_s ell ell

Description: We review the phenomenology of the rare decay {bar B} {yields} X{sub s}{ell}{sup +}{ell}{sup -}. We present the results of a detailed phenomenological analysis and discuss the role of the decay in the search for new physics at present and future colliders. Moreover, we extensively elaborate on the size of electromagnetic logarithms ln(m{sub b}{sup 2}/m{sub {ell}}{sup 2}) in view of experimental cuts. We point out the differences in the analyses of BaBar and Belle and give suggestions on how to treat collinear photons in the experimental analyses. These recommendations correspond precisely to theoretical prescriptions and can be combined with measurements performed at a Super-B factory.
Date: August 7, 2008
Creator: Huber, T.; Hurth, T. & Lunghi, E.
Partner: UNT Libraries Government Documents Department

On the Physics Case of a Super Flavour Factory

Description: We summarize the physics case of a high-luminosity e{sup +}e{sup -} flavor factory collecting an integrated luminosity of 50 - 75 ab{sup -1}. Many New Physics sensitive measurements involving B and D mesons and {tau} leptons, unique to a Super Flavor Factory, can be performed with excellent sensitivity to new particles with masses up to {approx} 100 (or even {approx} 1000) TeV. Flavor- and CP-violating couplings of new particles that may be discovered at the LHC can be measured in most scenarios, even in unfavorable cases assuming minimal flavor violation. Together with the LHC, a Super Flavor Factory, following either the SuperKEKB or the SuperB proposal, could be soon starting the project of reconstructing the New Physics Lagrangian.
Date: November 7, 2007
Creator: Browder, T.; Ciuchini, M.; Gershon, T.; Hazumi, M.; Hurth, T.; Okada, Y. et al.
Partner: UNT Libraries Government Documents Department

Status of SM Calculations of b to s Transitions

Description: We report recent progress in SM calculations of b {yields} s transitions. We discuss the first NNLL prediction of the {bar B} {yields} X{sub s}{gamma} branching ratio, including important additional subtleties due to non-perturbative corrections and logarithmically-enhanced cut effects, and also recent results on the inclusive mode {bar B} {yields} X{sub s}{ell}{sup +}{ell}{sup -}. Moreover, new results on the corresponding exclusive modes are reviewed. Finally, we comment on the present status of the so-called B {yields} K{pi} puzzle in hadronic b {yields} s transitions.
Date: April 4, 2007
Creator: Hurth, Tobias & /SLAC, /CERN
Partner: UNT Libraries Government Documents Department

NNLL QCD Contribution of the Electromagentic Dipole Operator to \bar B --> X_s gamma

Description: We present an independent calculation of that part of the O({alpha}{sub s}{sup 2}) contribution to dipole operator {Omicron}{sub 7}. Using a different method, we find complete agreement mass ambiguity appearing at NLL accuracy. the complete NNLL prediction of {Lambda}({bar B} {yields} X{sub s}{gamma}) which will resolve the charm quark the decay width {Lambda}({bar B} {yields} X{sub s}{gamma}) which arises from the self-interference term of the electromagnetic with a previous calculation. This NNLL contribution is an important ingredient for
Date: May 16, 2006
Creator: Asatrian, H.M.; Hovhannisyan, A.; Poghosyan, V.; Inst., /Yerevan Phys.; Ewerth, T.; Greub, C. et al.
Partner: UNT Libraries Government Documents Department

New Observables In the Decay Mode \bar B_d \-->\bar K^{0*} \ell^+ \ell^-

Description: We discuss the large set of observables available from the angular distributions of the decay {bar B}{sub d} {yields} {bar K}*{sup 0}{ell}{sup +}{ell}{sup -}. We present a NLO analysis of all observables based on the QCD factorization approach in the low-dilepton mass region and an estimate of {Lambda}/m{sub b} corrections. Moreover, we discuss their sensitivity to new physics. We explore the experimental sensitivities at LHCb (10 fb{sup -1}) and SuperLHCb (100 fb{sup -1}) based on a full-angular fit method and explore the sensitivity to right handed currents. We also show that the previously discussed transversity amplitude A{sub T}{sup (1)} cannot be measured at the LHCb experiment or at future B factory experiments as it requires a measurement of the spin of the final state particles.
Date: August 7, 2008
Creator: Egede, U.; /Imperial Coll., London; Hurth, T.; /SLAC, /CERN; Matias, J.; Ramon, M. et al.
Partner: UNT Libraries Government Documents Department

Reduction of Quark Mass Scheme Dependence in B bar -> Xs gamma at the NNLL Level

Description: The uncertainty of the theoretical prediction of the B {yields} X{sub s}{gamma} branching ratio at NLL level is dominated by the charm mass renormalization scheme ambiguity. In this paper we calculate those NNLL terms which are related to the renormalization of m{sub c}, in order to get an estimate of the corresponding uncertainty at the NNLL level. We find that these terms significantly reduce (by typically a factor of two) the error on BR(B {yields} X{sub s}{gamma}) induced by the definition of m{sub c}. Taking into account the experimental accuracy of around 10% and the future prospects of the B factories, we conclude that a NNLL calculation would increase the sensitivity of the observable B {yields} X{sub s}{gamma} to possible new degrees of freedom beyond the SM significantly.
Date: June 20, 2005
Creator: Asatrian, H.M.; Inst., /Yerevan Phys.; Greub, C.; U., /Bern; Hovhannisyan, A.; Inst., /Yerevan Phys. et al.
Partner: UNT Libraries Government Documents Department

Towards the NNLL Precision in the Decay $\bar B \rightarrow X_s \gamma$

Description: The present NLL prediction for the decay rate of the rare inclusive process {bar B} {yields} X{sub s}{gamma} has a large uncertainty due to the charm mass renormalization scheme ambiguity. We estimate that this uncertainty will be reduced by a factor of 2 at the NNLL level. This is a strong motivation for the on-going NNLL calculation, which will thus significantly increase the sensitivity of the observable {bar B} {yields} X{sub s}{gamma} to possible new degrees of freedom beyond the SM. We also give a brief status report of the NNLL calculation.
Date: January 5, 2006
Creator: Asatrian, Hrachia M.; Hovhannisyan, Artyom; Poghosyan, Vahagn; Inst., /Yerevan Phys.; Greub, Christoph; U., /Bern 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

Logarithmically enhanced corrections to the decayrate and forward backward asymmetry in \bar B to \ell^+ \ell^-

Description: We study logarithmically enhanced electromagnetic corrections to the decay rate in the high dilepton invariant mass region as well as corrections to the forward backward asymmetry (FBA) of the inclusive rare decay {bar B} {yields} X{sub s}{ell}{sup +}{ell}{sup -}. As expected, the relative effect of these corrections in the high dilepton mass region is around -8% for the muonic final state and therefore much larger than in the low dilepton mass region. We also present a complete phenomenological analysis, to improved NNLO accuracy, of the dilepton mass spectrum and the FBA integrated in the low dilepton mass region, including a new approach to the zero of the FBA. The latter represents one of the most precise predictions in flavor physics with a theoretical uncertainty of order 5%. We find (q{sub 0}{sup 2}){mu}{mu} = (3.50 {+-} 0.12)GeV{sup 2}. For the high dilepton invariant mass region, we have {Beta}({bar B} {yields} X{sub s}{mu}{mu}){sub high} = (2.40{sub -0.62}{sup +0.69}) x 10{sup -7}. The dominant uncertainty is due to the 1/m{sub b} corrections and can be significantly reduced in the future. For the low dilepton invariant mass region, we confirm previous results up to small corrections.
Date: January 9, 2008
Creator: Huber, Tobias; Hurth, Tobias & Lunghi, Enrico
Partner: UNT Libraries Government Documents Department

Rare Decays as a Probe for New Physics

Description: We discuss the indirect search for new degrees of freedom beyond the standard model, within flavour physics. In particular, we analyze the minimal flavour violation hypothesis and its phenomenological implications, especially the large-tan {beta} scenario in supersymmetric models, and also compare it with the constrained minimal flavour violation scenario. Moreover, we briefly discuss some recent progress in inclusive b {yields} s transitions and present a status report of the so-called K{pi} puzzle.
Date: January 3, 2007
Creator: Hurth, Tobias
Partner: UNT Libraries Government Documents Department

Simplified Models for a First Characterization of New Physics at the LHC

Description: Low-energy SUSY and several other theories that address the hierarchy problem predict pair-production at the LHC of particles with Standard Model quantum numbers that decay to jets, missing energy, and possibly leptons. If an excess of such events is seen in LHC data, a theoretical framework in which to describe it will be essential to constraining the structure of the new physics. We propose a basis of four deliberately simplified models, each specified by only 2-3 masses and 4-5 branching ratios, for use in a first characterization of data. Fits of these simplified models to the data furnish a quantitative presentation of the jet structure, electroweak decays, and heavy-flavor content of the data, independent of detector effects. These fits, together with plots comparing their predictions to distributions in data, can be used as targets for describing the data within any full theoretical model.
Date: June 19, 2009
Creator: Alwall, Johan; Schuster, Philip & Toro, Natalia
Partner: UNT Libraries Government Documents Department

New Physics Search in the LHCb Era

Description: The authors present theoretical and experimental preparations for an indirect search for new physics (NP) using the rare decay {bar B}{sub d} {yields} {bar K}*{sup 0}{mu}{sup +}{mu}{sup -}. They design new observables with very small theoretical uncertainties and good experimental resolution.
Date: June 11, 2010
Creator: Hurth, Tobias; /SLAC, /CERN & ,
Partner: UNT Libraries Government Documents Department

Twistor String Theory and QCD

Description: The author reviews recent progress in using twistor-inspired methods to compute perturbative scattering amplitudes in gauge theory, for application to collider physics.
Date: December 8, 2005
Creator: Dixon, Lance J.
Partner: UNT Libraries Government Documents Department

Recent Developments in Perturbative QCD

Description: I review recent progress in perturbative QCD on two fronts: extending next-to-next-to-leading order QCD corrections to a broader range of collider processes, and applying twistor-space methods (and related spinoffs) to computations of multi-parton scattering amplitudes.
Date: July 11, 2005
Creator: Dixon, Lance J.
Partner: UNT Libraries Government Documents Department

Flavour-Violating Gluino and Squark Decays

Description: We consider scenarios with large flavour violating entries in the squark mass matrices focusing on the mixing between second and third generation squarks. These entries govern both, flavour violating low energy observables on the one hand and squark and gluino decays on the other hand. We first discuss the constraints on the parameter space due to the recent data on B mesons from the B factories and Tevatron. We then consider flavour violating squark and gluino decays and show that they can still be typically of order 10% despite the stringent constraints from low energy data. Finally we briefly comment on the impact for searches and parameter determinations at future collider experiments such as the upcoming LHC or a future International Linear Collider.
Date: June 11, 2010
Creator: Hurth, Tobias & Porod, Werner
Partner: UNT Libraries Government Documents Department

Implications of D^0-\overline D^0 Mixing for New Physics

Description: We provide a comprehensive, up-to-date analysis of possible New Physics contributions to the mass difference {Delta}M{sub D} in D{sup 0}-{bar D}{sup 0} mixing. We consider the most general low energy effective Hamiltonian and include leading order QCD running of effective operators. We then explore an extensive list of possible New Physics models that can generate these operators, which we organize as including Extra Fermions, Extra Gauge Bosons, Extra Scalars, Extra Space Dimensions and Extra Symmetries. For each model we place restrictions on the allowed parameter space using the recent evidence for observation of D meson mixing. In many scenarios, we find strong constraints that surpass those from other search techniques and provide an important test of flavor changing neutral currents in the up-quark sector. We also review the recent BaBar and Belle findings, and describe the current status of the Standard Model predictions of D{sup 0}-{bar D}{sup 0} mixing.
Date: June 8, 2007
Creator: Golowich, Eugene; /Massachusetts U., Amherst; Hewett, JoAnne; /SLAC; Pakvasa, Sandip; U., /Hawaii et al.
Partner: UNT Libraries Government Documents Department

The B -> pi Form Factor from Light-cone Sum Rules in Soft-collinear Effective Theory

Description: Recently, we have derived light-cone sum rules for exclusive B-meson decays into light energetic hadrons from correlation functions within soft-collinear effective theory [1]. In these sum rules the short-distance scale refers to ''hard-collinear'' interactions with virtualities of order {Lambda}{sub QCD}m{sub b}. Hard scales (related to virtualities of order m{sub b}{sup 2}) are integrated out and enter via external coefficient functions in the sum rule. Soft dynamics is encoded in light-cone distribution amplitudes for the B-meson, which describe both the factorizable and non-factorizable contributions to exclusive B-meson decay amplitudes. Factorization of the correlation function has been verified to one-loop accuracy. Thus, a systematic separation of hard, hard-collinear, and soft dynamics in the heavy-quark limit is possible.
Date: October 17, 2005
Creator: Hurth, Tobias; /SLAC, /CERN; De Fazio, Fulvia; /INFN, Bari; Feldmann, Thorsten & U., /Siegen
Partner: UNT Libraries Government Documents Department

Precise Predictions for W + 3 Jet Production at Hadron Colliders

Description: We report on the first next-to-leading order QCD computation of W + 3-jet production in hadronic collisions including all partonic subprocesses. We compare the results with CDF data from the Tevatron, and find excellent agreement. The renormalization and factorization scale dependence is reduced substantially compared to leading-order calculations. The required one-loop matrix elements are computed using on-shell methods, implemented in a numerical program, BlackHat. We use the SHERPA package to generate the real-emission contributions and to integrate the various contributions over phase space. We use a leading-color (large-N{sub c}) approximation for the virtual part, which we confirm in W + 1,2-jet production to be valid to within three percent. The present calculation demonstrates the utility of on-shell methods for computing next-to-leading-order corrections to processes important to physics analyses at the Large Hadron Collider.
Date: February 23, 2009
Creator: Berger, C.F.; /MIT, LNS; Bern, Z.; /UCLA; Dixon, L.J.; /SLAC et al.
Partner: UNT Libraries Government Documents Department

SCET Sum Rules for B to P and B to V Transition Form Factors

Description: We investigate sum rules for heavy-to-light transition form factors at large recoil derived from correlation functions with interpolating currents for light pseudoscalar or vector fields in soft-collinear effective theory (SCET). We consider both, factorizable and nonfactorizable contributions at leading power in the {Lambda}/m{sub b} expansion and to first order in the strong coupling constant {alpha}{sub s}, neglecting contributions from 3-particle distribution amplitudes in the B-meson. We pay particular attention to various sources of parametric and systematic uncertainties. We also discuss certain form factor ratios where part of the hadronic uncertainties related to the B-meson distribution amplitude and to logarithmically enhanced {alpha}{sub s} corrections cancel.
Date: December 18, 2007
Creator: De Fazio, Fulvia; /INFN, Bari; Feldmann, Thorsten; U., /Siegen; Hurth, Tobias & /SLAC, /CERN
Partner: UNT Libraries Government Documents Department