8,326 research outputs found
The Three Loop Two-Mass Contribution to the Gluon Vacuum Polarization
We calculate the two-mass contribution to the 3-loop vacuum polarization of
the gluon in Quantum Chromodynamics at virtuality for general masses
and also present the analogous result for the photon in Quantum
Electrodynamics.Comment: 5 pages Late
The 3-Loop Non-Singlet Heavy Flavor Contributions to the Structure Function g_1(x,Q^2) at Large Momentum Transfer
We calculate the massive flavor non-singlet Wilson coefficient for the heavy
flavor contributions to the polarized structure function in the
asymptotic region to 3-loop order in Quantum Chromodynamics at
general values of the Mellin variable and the momentum fraction , and
derive heavy flavor corrections to the Bjorken sum-rule. Numerical results are
presented for the charm quark contribution. Results on the structure function
in the twist-2 approximation are also given.Comment: 29 pages, 8 Figure
The unpolarized two-loop massive pure singlet Wilson coefficients for deep-inelastic scattering
We calculate the massive two--loop pure singlet Wilson coefficients for heavy
quark production in the unpolarized case analytically in the whole kinematic
region and derive the threshold and asymptotic expansions. We also recalculate
the corresponding massless two--loop Wilson coefficients. The complete
expressions contain iterated integrals with elliptic letters. The contributing
alphabets enlarge the Kummer-Poincar\'e letters by a series of square-root
valued letters. A new class of iterated integrals, the Kummer-elliptic
integrals, are introduced. For the structure functions and we also
derive improved asymptotic representations adding power corrections. Numerical
results are presented.Comment: 42, pages Latex, 8 Figure
The Initial State QED Corrections to Annihilation to a Neutral Vector Boson Revisited
We calculate the non-singlet, the pure singlet contribution, and their
interference term, at due to electron-pair initial state
radiation to annihilation into a neutral vector boson in a direct
analytic computation without any approximation. The correction is represented
in terms of iterated incomplete elliptic integrals. Performing the limit we find discrepancies with the earlier results of
Ref.~\cite{Berends:1987ab} and confirm results obtained in
Ref.~\cite{Blumlein:2011mi} where the effective method of massive operator
matrix elements has been used, which works for all but the power corrections in
. In this way, we also confirm the validity of the factorization of
massive partons in the Drell-Yan process. We also add non-logarithmic terms at
which have not been considered in \cite{Berends:1987ab}. The
corrections are of central importance for precision analyzes in
annihilation into at high luminosity.Comment: 4 pages Latex, 2 Figures, several style file
Phase Transition and Monopoles Densities in a Nearest Neighbors Two-Dimensional Spin Ice Model
In this work, we show that, due to the alternating orientation of the spins
in the ground state of the artificial square spin ice, the influence of a set
of spins at a certain distance of a reference spin decreases faster than the
expected result for the long range dipolar interaction, justifying the use of
the nearest neighbor two dimensional square spin ice model as an effective
model. Using an extension of the model presented in ref. [Scientific Reports 5,
15875 (2015)], considering the influence of the eight nearest neighbors of each
spin on the lattice, we analyze the thermodynamics of the model and study the
monopoles and string densities dependence as a function of the temperature.Comment: 11 pages, 8 figure
The two-mass contribution to the three-loop pure singlet operator matrix element
We present the two-mass QCD contributions to the pure singlet operator matrix
element at three loop order in x-space. These terms are relevant for
calculating the structure function at as well as
for the matching relations in the variable flavor number scheme and the heavy
quark distribution functions at the same order. The result for the operator
matrix element is given in terms of generalized iterated integrals that include
square root letters in the alphabet, depending also on the mass ratio through
the main argument. Numerical results are presented.Comment: 28 papges Latex, 3 figure
The O(\alpha_s^3) Heavy Flavor Contributions to the Charged Current Structure Function xF_3(x,Q^2) at Large Momentum Transfer
We calculate the massive Wilson coefficients for the heavy flavor
contributions to the non-singlet charged current deep-inelastic scattering
structure function in the asymptotic
region to 3-loop order in Quantum Chromodynamics (QCD) at general
values of the Mellin variable and the momentum fraction . Besides the
heavy quark pair production also the single heavy flavor excitation contributes. Numerical results are presented for the charm quark
contributions and consequences on the Gross-Llewellyn Smith sum rule are
discussed.Comment: 30 pages, 6 figures. arXiv admin note: text overlap with
arXiv:1504.0821
Heavy Flavor Wilson Coefficients in Deep-Inelastic Scattering: Recent Results
We present recent analytic results for the 3-loop corrections to the massive
operator matrix element for further color factors. These results
have been obtained using the method of arbitrarily large moments. We also give
an overview on the results which were obtained solving all difference and
differential equations for the corresponding master integrals that factorize at
first order.Comment: 11 pages Latex, To appear in the Proceedings of: QCDEV2017, JLAB,
Newport News, VA, USA, May 22-26, 2017; Po
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