arXiv subjects

B. F. L. Ward

Publications and source records attributed to B. F. L. Ward.

At least 73 records · Page 4Linked to original sources

arXiv2013

KK MC 4.22: CEEX EW Corrections for f\bar{f}\rightarrow f'\bar{f'} at LHC and Muon Colliders

We present the upgrade of the coherent exclusive (CEEX) exponentiation realization of the Yennie-Frautschi-Suura (YFS) theory used in our Monte Carlo ({\cal KK} MC) to the processes f\bar{f}\rightarrow f'\bar{f'}, f=μ,τ,q,ν_\ell, f'=e,μ,τ,q,ν_\ell, q=u,d,s,c,b,t, \ell=e,μ,τwith f\ne f', with an eye toward the precision physics of the LHC and possible high energy muon colliders. We give a brief summary of the CEEX theory in comparison to the older (EEX) exclusive exponentiation theory and illustrate theoretical results relevant to the LHC and possible muon collider physics programs.

hep-ph↗

arXiv2013

Comparisons of Predictions from Exact Amplitude-Based Resummation Methods with LHC and Cosmological Data

We present the current status of the comparisons with the respective data of the predictions of our approach of exact amplitude-based resummation in quantum field theory in two areas of investigation: precision QCD calculations of all four of us as needed for LHC physics and the resummed quantum gravity realization by one of us (B.F.L.W.) of Einstein's theory of general relativity as formulated by Feynman. The agreement between the theoretical predictions and the data exhibited continues to be encouraging.

hep-ph↗

arXiv2013

HERWIRI2: Exponentiated Electroweak Corrections in a Hadronic Event Generator

Reaching the desired precision level for W and Z processes at the LHC will require a mixture of higher-order QCD and electroweak corrections. HERWIRI2 is a step in implementing QED x QCD exponentiation in a hadronic event generator. This program implements leading electroweak corrections and coherent exclusive exponentiation in a HERWIG environment. We discuss the status of the program, recent tests, and future developments.

hep-ph↗

arXiv2013

An Estimate of Λin Resummed Quantum Gravity in the Context of Asymptotic Safety

We show that, by using recently developed exact resummation techniques based on the extension of the methods of Yennie, Frautschi and Suura to Feynman's formulation of Einstein's theory, we get quantum field theoretic descriptions for the UV fixed-point behaviors of the dimensionless gravitational and cosmological constants postulated by Weinberg. Connecting our work to the attendant phenomenological asymptotic safety analysis of Planck scale cosmology by Bonanno and Reuter, we estimate the value of the cosmological constant Λ. We find the encouraging estimate ρ_Λ\equiv \fracΛ{8πG_N} \simeq (2.4\times 10^{-3}eV)^4. While this numerical value is close to recent experimental observations, we caution the reader that the estimate involves a number of model parameters that still possess significant levels of uncertainty, such as the value of the transition time between the Planck scale cosmology era and the Friedmann-Robertson-Walker radiation dominated era, where our current understanding allows for at least two orders of magnitude in its uncertainty and this would change our estimate of ρ_Λby at least four orders of magnitude. We discuss such theoretical uncertainties as well. We show why GUT and EW scale vacuum energies from spontaneous symmetry breaking are suppressed in our approach to the estimation of ρ_Λ. As a bonus, we show how our estimate constrains susy GUTS.

gr-qc↗

arXiv2013

Phenomenological Study of the Interplay between IR-Improved DGLAP-CS Theory and the Precision of an NLO ME Matched Parton Shower MC

We present a phenomenological study of the current status of the application of our approach of {\it exact} amplitude-based resummation in quantum field theory to precision QCD calculations, by realistic MC event generator methods, as needed for precision LHC physics. We discuss recent results as they relate to the interplay of the attendant IR-Improved DGLAP-CS theory of one of us and the precision of exact NLO matrix-element matched parton shower MC's in the Herwig6.5 environment as determined by comparison to recent LHC experimental observations on single heavy gauge boson production and decay. The level of agreement between the new theory and the data continues to be a reason for optimism. In the spirit of completeness, we discuss as well other approaches to the same theoretical predictions that we make here from the standpoint of physical precision with an eye toward the (sub-)1% QCD \otimes EW total theoretical precision regime for LHC physics.

hep-ph↗

arXiv2013

Interplay of IR-Improved DGLAP-CS Theory and NLO Parton Shower MC Precision

We present the interplay between the new IR-improved DGLAP-CS theory and the precision of NLO parton shower/ME matched MC`s as it is realized by the new MC Herwiri1.031 in interface to MC@NLO. We discuss phenomenological implications using comparisons with recent LHC data on single heavy gauge boson production.

hep-ph↗

arXiv2013

An Estimate of Lambda in Resummed Quantum Gravity in the Context of Asymptotic Safety and Planck Scale Cosmology: Constraints on SUSY GUTS

We use the amplitude-based resummation of Feynman`s formulation of Einstein`s theory to arrive at a UV finite approach to quantum gravity. We show that we recover the UV fixed point recently claimed by the exact field-space renormalization group approach. We use our approach in the context of the attendant Planck scale cosmology formulation of Bonanno and Reuter to estimate the value of the cosmological constant as ρ_Λ=(0.0024 eV)^4. We show that the closeness of this estimate to experiment constrains susy GUT models.

hep-ph↗

arXiv2013

Phenomenology of the Interplay between IR-Improved DGLAP-CS Theory and NLO ME Matched Parton Shower MC Precision

We present the current status of the application of our approach of {\it exact} amplitude-based resummation in quantum field theory to precision QCD calculations, by realistic MC event generator methods, as needed for precision LHC physics.In this ongoing program of research, we discuss recent results as they relate to the interplay of the attendant IR-Improved DGLAP-CS theory of one of us and the precision of exact NLO matrix element matched parton shower MC's in the Herwig6.5 environment in relation to recent LHC experimental observations. There continues to be reason for optimism in the attendant comparison of theory and experiment.

hep-ph↗

arXiv2012

IR-Improved Operator Product Expansions in non-Abelian Gauge Theory

We present a formulation of the operator product expansion that is infrared finite to all orders in the attendant massless non-Abelian gauge theory coupling constant, which we will often-times associate with the QCD theory, the theory that we actually have as our primary objective in view of the operation of the LHC at CERN. We make contact in this way with the recently introduced IR-improved DGLAP-CS theory and point-out phenomenological implications accordingly, with an eye toward the precision QCD theory for LHC physics.

hep-ph↗

arXiv2012

Estimates of Radiation by Superluminal Neutrinos

We show that the more energetic superluminal neutrinos with quadratically dispersed superluminalities δ=β^2-1, for β=v/c where v is the neutrino velocity, also lose significant energy to radiation to the ν+e^-+e^+ final state in travelling from CERN to Gran Sasso as has been shown to occur for those with constant superluminality by Cohen and Glashow if indeed δ\simeq 5\times 10^{-5}. In addition, we clarify the dependence of such radiative processes on the size of the superluminality.

hep-ph↗

arXiv2012

HERWIRI2: CEEX Electroweak Corrections in a Hadronic MC

Reaching the 1% precision level for W and Z production calculations for the LHC will require a mixture of higher order QCD and electroweak corrections. As a first step toward implementing the combined QED\otimesQCD exponentiation proposed in previous work, we have implemented the order alpha electroweak corrections and YFS exponentiation structure of the KK Monte Carlo in HERWIG. We discuss the current status of this program and sketch the further developments needed to reach the desired precision level.

hep-ph↗

arXiv2012

Exact Amplitude-Based Resummation in Quantum Field Theory: Recent Results

We present the current status of the application of our approach of exact amplitude-based resummation in quantum field theory to two areas of investigation: precision QCD calculations of all three of us as needed for LHC physics and the resummed quantum gravity realization by one of us (B.F.L.W.) of Feynman's formulation of Einstein's theory of general relativity. We discuss recent results as they relate to experimental observations. There is reason for optimism in the attendant comparison of theory and experiment.

hep-ph↗

arXiv2011

The Epsilon Expansion of Feynman Diagrams via Hypergeometric Functions and Differential Reduction

Higher-order diagrams required for radiative corrections to mixed electroweak and QCD processes at the LHC and anticipated future colliders will require numerically stable representations of the associated Feynman diagrams. The hypergeometric representation supplies an analytic framework that is useful for deriving such stable representations. We discuss the reduction of Feynman diagrams to master integrals, and compare integration-by-parts methods to differential reduction of hypergeometric functions. We describe the problem of constructing higher-order terms in the epsilon expansion, and characterize the functions generated in such expansions.

math-ph↗

arXiv2011

Chinese Magic in Loop Integrals

We present an approach to higher point loop integrals using Chinese magic in the virtual loop integration variable. We show, using the five point function in the important e^+e^-\to f\bar{f}+γprocess for ISR as a pedagogical vehicle, that we get an expression for it directly reduced to one scalar 5-point function and 4-, 3-, and 2- point integrals, thereby avoiding the computation of the usual three tensor 5-pt Passarino-Veltman reduction. We argue that this offers potential for greater numerical stability.

hep-ph↗

arXiv2011

New Approach to GUTs

We introduce a new string-inspired approach to the subject of grand unification which allows the GUT scale to be small, \lesssim 200 TeV, so that it is within the reach of {\em conceivable} laboratory accelerated colliding beam devices. The key ingredient is a novel use of the heterotic string symmetry group physics ideas to render baryon number violating effects small enough to have escaped detection to date. This part of the approach involves new unknown parameters to be tested experimentally. A possible hint at the existence of these new parameters may already exist in the EW precision data comparisons with the SM expectations.

hep-ph↗

arXiv2011

QCD for the LHC

We discuss the new era of precision QCD as it relates to the physics requirements of the LHC for both the signal and background type processes. Some attention is paid to the issue of the theoretical error associated with any given theoretical prediction. In the cases considered, we present where the theory precision is at this writing and where it needs to go in order that it not impede the discovery potential of the LHC physics program. To complete the discussion, we also discuss possible paradigms the latter program may help us understand and some new developments that may play a role in achieving that respective understanding.

hep-ph↗

arXiv2011

Differential Reduction Techniques for the Evaluation of Feynman Diagrams

Stable reduction methods will be important in the evaluation of high-order perturbative diagrams appearing in QCD and mixed QCD-electroweak radiative corrections at the LHC. Differential reduction techniques are useful for relating hypergeometric functions with shifted values of the parameters. We present a proposition relating the number of master integrals in the expansion of a Feynman diagram to the number of derivatives in a differential reduction.

math-ph↗

arXiv2010

HERWIRI1.031: New Approach to Parton Shower MC's in Precision QCD Theory

The new IR-improved Dokshitzer-Gribov-Lipatov-Altarelli-Parisi-Callan-Symanzik (DGLAP-CS) kernels recently developed by one of us is implemented in the HERWIG6.5 environment to generate a new MC, HERWIRI1.0(31), for hadron-hadron scattering at high energies. The comparison between the parton shower generated by the standard DGLAP-CS kernels and that generated by the new IR-improved DGLAP-CS kernels is illustrated using MC data. This is done for some of the respective exact {\cal O}(α_s) corrected spectra using the seamless interfaces to MC@NLO while making comparisons with FNAL data. Some discussion of possible implications for LHC phenomenology is also presented.

hep-ph↗