435 research outputs found
Relativistic corrections to prompt photo- and hadroproduction
We systematically calculate the relativistic corrections to prompt
photoproduction and hadroproduction using the factorization formalism of
nonrelativistic QCD. Specifically, we include the and
color-singlet and the ,
, and color-octet channels as well as
the effects due to the mixing between the and
channels. We provide all the squared hard-scattering
amplitudes in analytic form. Assuming the nonrelativistic-QCD long-distance
matrix elements to satisfy the velocity scaling rules, we find the relativistic
corrections to be appreciable, except in the color-singlet
channel of hadroproduction. We also observe significant differences in the line
shapes of the relativistic corrections between photoproduction and
hadroproduction.Comment: 26 pages, 3 figures, matches journal versio
Relativistic corrections to polarization in photo- and hadroproduction
We systematically calculate the relativistic corrections to the polarization
variables of prompt photoproduction and hadroproduction using the
factorization formalism of nonrelativistic QCD. Specifically, we include the
and color-singlet and the
, , and color-octet
channels as well as the effects due to the mixing between the
and channels. We provide all the squared hard-scattering
amplitudes in analytic form. Assuming the nonrelativistic-QCD long-distance
matrix elements to satisfy the velocity scaling rules, we find the relativistic
corrections to be appreciable, especially at small transverse momentum
and large inelasticity . The results obtained here and in our previous work
on the unpolarized yield [Phys. Rev. D 90, 014045 (2014)] will help to render
global analyses of prompt production data more complete and hopefully
to shed light on the polarization puzzle.Comment: 42 pages, 4 figures, matches journal version, PRD Editors' Suggestio
Complete Nonrelativistic-QCD Prediction for Prompt Double Hadroproduction
We perform a complete study of prompt double hadroproduction at
leading order in the nonrelativistic-QCD factorization framework by including
all possible pairings of the Fock states ,
, and with . We find that the
and channels of and
production and the and channels of
production, which have been overlooked so far, greatly dominate at
large invariant masses and rapidity separations of the pair, and that
their inclusion nearly fills the large gap between previous incomplete
predictions within the color-singlet model and the recent measurement by the
CMS Collaboration at the CERN LHC, leaving room for next-to-leading-order
corrections of typical size.Comment: 5 pages, 4 figures, matches journal versio
Environmental factors controlling the distributions of Botryococcus braunii (A, B and L) biomarkers in a subtropical freshwater wetland
Here we report the molecular biomarker co-occurrence of three different races of Botryococcus braunii (B. braunii) in the freshwater wetland ecosystem of the Florida Everglades, USA. Thespecific biomarkers include C32–C34 botryococcenes for race B, C27–C32 n-alkadienes and n-alkatrienes for race A, and lycopadiene for race L. The n-alkadienes and n-alkatrienes were present up to 3.1 and 69.5 µg/g dry weight (dw), while lycopadiene was detected in lower amounts up to 3.0 and 1.5 µg/g dw in periphyton and floc samples, respectively. Nutrient concentrations (P and N) did not significantly correlate with the abundances of these compounds. In contrast, n-alkadienes and n-alkatrienes were present in wider diversity and higher abundance in the floc from slough (deeper water and longer hydroperiod) than ridge (shallower water and shorter hydroperiod) locations. n-Alkadienes, n-alkatrienes, and lycopadiene, showed lower δ13C values from −40.0 to −35.5‰, suggesting that the source organisms B. braunii at least partially utilize recycled CO2 (13C depleted) produced from OM respiration rather than atmospheric CO2 (13C enriched) as the major carbon sources
production at the LHC challenges nonrelativistic-QCD factorization
We analyze the first measurement of production, performed by the
LHCb Collaboration, in the nonrelativistic-QCD (NRQCD) factorization framework
at next-to-leading order (NLO) in the strong-coupling constant and
the relative velocity of the bound quarks including the feeddown from
mesons. Converting the long-distance matrix elements (LDMEs) extracted by
various groups from yield and polarization data to the case
using heavy-quark spin symmetry, we find that the resulting NLO NRQCD
predictions greatly overshoot the LHCb data, while the color-singlet model
provides an excellent description.Comment: 5 pages, 2 figures, minor changes, note regarding arXiv:1411.7350
[hep-ph] added, accepted for publication in Physical Review Letter
Inclusive production in decay at in NRQCD factorization
Inclusive production from decay is
studied within the framework of nonrelativistic QCD (NRQCD) factorization at
leading order in , which includes the contributions of
and
. For both channels, the
short-distance coefficients are calculated through ,
which is next-to-leading order for the second one. By fitting to the measured
branching fractions to and , we obtain
the color-octet long-distance matrix element (LDME)
GeV, where the first error is
experimental and the second one due to the renormalization scale dependence, if
we use as input
GeV as obtained via potential-model analysis. Previous LDME sets, extracted
from data of prompt hadroproduction, yield theoretical predictions
that systematically undershoot or mildly overshoot the experimental values of
.Comment: 10 pages, 8 figures, minor changes, matches journal versio
Positive del Pezzo Geometry
Real, complex, and tropical algebraic geometry join forces in a new branch of
mathematical physics called positive geometry. We develop the positive geometry
of del Pezzo surfaces and their moduli spaces, viewed as very affine varieties.
Their connected components are derived from polyhedral spaces with Weyl group
symmetries. We study their canonical forms and scattering amplitudes, and we
solve the likelihood equations.Comment: 34 pages, 4 figure
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