skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Impact of the heavy-quark matching scales in PDF fits

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1411797
Grant/Contract Number:
SC0010129
Resource Type:
Journal Article: Published Article
Journal Name:
European Physical Journal. C, Particles and Fields
Additional Journal Information:
Journal Volume: 77; Journal Issue: 12; Related Information: CHORUS Timestamp: 2017-12-07 05:13:55; Journal ID: ISSN 1434-6044
Publisher:
Springer Science + Business Media
Country of Publication:
Germany
Language:
English

Citation Formats

The xFitter Developers’ Team:, Bertone, V., Britzger, D., Camarda, S., Cooper-Sarkar, A., Geiser, A., Giuli, F., Glazov, A., Godat, E., Kusina, A., Luszczak, A., Lyonnet, F., Olness, F., Plačakytė, R., Radescu, V., Schienbein, I., and Zenaiev, O. Impact of the heavy-quark matching scales in PDF fits. Germany: N. p., 2017. Web. doi:10.1140/epjc/s10052-017-5407-3.
The xFitter Developers’ Team:, Bertone, V., Britzger, D., Camarda, S., Cooper-Sarkar, A., Geiser, A., Giuli, F., Glazov, A., Godat, E., Kusina, A., Luszczak, A., Lyonnet, F., Olness, F., Plačakytė, R., Radescu, V., Schienbein, I., & Zenaiev, O. Impact of the heavy-quark matching scales in PDF fits. Germany. doi:10.1140/epjc/s10052-017-5407-3.
The xFitter Developers’ Team:, Bertone, V., Britzger, D., Camarda, S., Cooper-Sarkar, A., Geiser, A., Giuli, F., Glazov, A., Godat, E., Kusina, A., Luszczak, A., Lyonnet, F., Olness, F., Plačakytė, R., Radescu, V., Schienbein, I., and Zenaiev, O. 2017. "Impact of the heavy-quark matching scales in PDF fits". Germany. doi:10.1140/epjc/s10052-017-5407-3.
@article{osti_1411797,
title = {Impact of the heavy-quark matching scales in PDF fits},
author = {The xFitter Developers’ Team: and Bertone, V. and Britzger, D. and Camarda, S. and Cooper-Sarkar, A. and Geiser, A. and Giuli, F. and Glazov, A. and Godat, E. and Kusina, A. and Luszczak, A. and Lyonnet, F. and Olness, F. and Plačakytė, R. and Radescu, V. and Schienbein, I. and Zenaiev, O.},
abstractNote = {},
doi = {10.1140/epjc/s10052-017-5407-3},
journal = {European Physical Journal. C, Particles and Fields},
number = 12,
volume = 77,
place = {Germany},
year = 2017,
month =
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1140/epjc/s10052-017-5407-3

Save / Share:
  • In this contribution we present the NNPDF2.1 parton distribution functions (PDF) set. The NNPDF2.1 set is a set extracted from a global fit to Deep-Inelastic Scattering (DIS), fixed target Drell-Yan (DY), Electroweak vector boson and inclusive jet cross-sections at colliders data. It is performed using the NNPDF methodology which relies on Monte Carlo techniques for determination of uncertainties and Neural Networks as unbiased interpolants.
  • Heavy-light QCD currents are matched with heavy-quark effective theory (HQET) currents at two loops and leading order in 1/{ital m}. A single formula applies to all current matchings. As a by-product, a master formula for the two-loop anomalous dimension of the QCD current {ital {bar q}}{gamma}{sup [{mu}}{sub 1}...{gamma}{sup {mu}}{sub {ital n}]}{ital q} is obtained, yielding a new result for the tensor current. The dependence of matching coefficients on {gamma}{sub 5} prescriptions is elucidated. Ratios of QCD matrix elements are obtained, independently of the three-loop anomalous dimension of HQET currents. The two-loop coefficient in {ital f}{sub {ital B}}{sup *}/{ital f}{sub {italmore » B}} =1{minus}2{alpha}{sub {ital s}}({ital m}{sub {ital b}})/3{pi}{minus}{ital K}{sub {ital b}}{alpha}{sub {ital s}}{sup 2}/{pi}{sup 2} +{ital O}({alpha}{sub {ital s}}{sup 3},1/{ital m}{sub {ital b}}) is {ital K}{sub {ital b}}=83/12+4/81{pi}{sup 2}+2/27{pi}{sup 2}ln2{minus}1/9{zeta}(3){minus}19/54{ital N}{sub {ital l}} +{Delta}{sub {ital c}}=6.37+{Delta}{sub {ital c}}, with {ital N}{sub {ital l}}=4 light flavors, and a correction {Delta}{sub {ital c}}=0.18{plus_minus}0.01 that takes account of the nonzero ratio {ital m}{sub {ital c}}/{ital m}{sub {ital b}}=0.28{plus_minus}0.03. Convergence of the perturbative series is poor: the fastest apparent convergence would entail {alpha}{sub {ital s}}({mu}) at {mu}=370 MeV. ``Naive non-Abelianization`` of large-{ital N}{sub {ital l}} results, via {ital N}{sub {ital l}}{r_arrow}{ital N}{sub {ital l}}{minus}33/2, gives reasonable approximations to exact two-loop results. All-order results for anomalous dimensions and matching coefficients are obtained at large {beta}{sub 0}=11=2/3{ital N}{sub {ital l}}. Consistent cancellation between infrared- and ultraviolet-renormalon ambiguities is demonstrated.« less
  • We discuss perturbative O(g{sup 2} a) matching with static heavy quarks and domain-wall light quarks for lattice operators relevant to B-meson decays and B{sup 0} - {bar B}{sup 0} mixing. The chiral symmetry of the light domain-wall quarks does not prohibit operator mixing at O(a) for these operators. The O(a) corrections to physical quantities are non-negligible and must be included to obtain high-precision simulation results for CKM physics. We provide results using plaquette, Symanzik, Iwasaki and DBW2 gluon actions and applying APE, HYP1 and HYP2 link-smearing for the static quark action.
  • The one-loop QCD heavy-quark potential is computed to order v{sup 2} in the color singlet and octet channels. Several errors in the previous literature are corrected. To be consistent with the velocity power counting, the full dependence on |p+p{sup '}|/|p{sup '}-p| is kept. The matching conditions for the NRQCD one-loop potential are computed by comparing the QCD calculation with that in the effective theory. The graphs in the effective theory are also compared to terms from the hard, soft, potential, and ultrasoft regimes in the threshold expansion. The issue of off-shell versus on-shell matching and gauge dependence is discussed inmore » detail for the 1/(m|k|) term in the potential. Matching on-shell gives a 1/(m|k|) potential that is gauge independent and does not vanish for QED. (c) 2000 The American Physical Society.« less
  • We show that for theoretical as well as phenomenological reasons the baryon magnetic moments that fulfill simple group transformation properties should be taken in intrinsic rather than nuclear magnetons. A fit of the recent experimental data to the reduced matrix elements of the usual octet electromagnetic current is still not good, and in order to obtain acceptable agreement, one has to add correction terms to the octet current. We have texted two kinds of corrections: U-spin-scalar terms, which are singles out by the model-independent algebraic properties of the hadron electromagnetic current, and octet U-spin vectors, which could come from quark-massmore » breaking in a nonrelativistic quark model. We find that the U-spin-scalar terms are more important than the U-spin vectors for various levels of demanded theoretical accuracy.« less