We study inclusive Λc±-baryon production in p p collisions in the general-mass variable-flavor-number scheme and compare with data from the LHCb, ALICE, and CMS collaborations. We perform a new fit ...of the c → Λc+ fragmentation function combining e+ e− data from OPAL and Belle. The agreement with LHC data is slightly worse compared with a calculation using an older fragmentation function, and the tension between different determinations of Λc± production cross sections from the LHC experimental collaborations is not resolved. The ratio of data for Λc+-baryon and D0-meson production seems to violate the universality of c-quark to c-hadron fragmentation.
We present a new approach to consider and include both the perturbative and the nonperturbative contributions to the multiplicities of gluon and quark jets. Thanks to this new method, we have ...included for the first time new contributions to these quantities obtaining next-to-next-to-leading-logarithmic resummed formulas. Our analytic expressions depend on two nonperturbative parameters with a clear and simple physical interpretation. A global fit of these two quantities shows how our results solve a long-standing discrepancy in the theoretical description of the data.
We elaborate the inclusive production of single heavy-flavored hadrons in
e
+
e
−
annihilation at next-to-leading order in the general-mass variable-flavor-number scheme. In this framework, we ...determine non-perturbative fragmentation functions for
D
0
,
D
+
, and
D
∗
+
mesons by fitting experimental data from the Belle, CLEO, ALEPH, and OPAL Collaborations, taking dominant electroweak corrections due to photonic initial-state radiation into account. We assess the significance of finite-mass effects through comparisons with a similar analysis in the zero-mass variable-flavor-number scheme. Under Belle and CLEO experimental conditions, charmed-hadron mass effects on the phase space turn out to be appreciable, while charm-quark mass effects on the partonic matrix elements are less important.
Using fragmentation functions for charged pions, charged kaons, and (anti)protons recently extracted from experimental data of
e
+e
−
annihilation at the
Z-boson resonance and at centre-of-mass ...energy
s
=29
GeV, we perform a global study of inclusive charged-hadron production in
p
p
̄
,
γp, and
γγ collisions at next-to-leading order in the parton model of quantum chromodynamics. Comparisons of our results with
p
p
̄
data from CERN S
p
p
̄
S and the Fermilab Tevatron,
γp data from DESY HERA, and
γγ data from CERN LEP2 allow us to test the universality of the fragmentation functions predicted by the factorization theorem. Furthermore, we perform comparisons with
e
+e
−
-annihilation data from LEP2 so as to test the scaling violations predicted by the Altarelli–Parisi evolution equations.
We discuss the inclusive production of
D
*±
-mesons in
γ
p
collisions at DESY HERA, based on a calculation at next-to-leading order in the general-mass variable-flavor-number scheme. In this ...approach,
subtraction is applied in such a way that large logarithmic corrections are resummed in universal parton distribution and fragmentation functions and finite-mass terms are taken into account. We present detailed numerical results for a comparison with data obtained at HERA and discuss various sources of theoretical uncertainties.
We calculate the full one-loop electroweak radiative corrections, of O(α2αs), to the cross section of single Z-boson inclusive hadroproduction at finite transverse momentum (pT). This includes the ...O(α) corrections to Z+j production, the O(αs) corrections to Z+γ production, and certain QCD-electroweak interference contributions involving a single quark trace. We recover the QCD and purely weak corrections and study the QED corrections and the QCD-electroweak interference contributions for the first time. We also consider direct and resolved photoproduction in elastic and inelastic scattering. We present pT and rapidity distributions for the experimental conditions at the Fermilab Tevatron and the CERN LHC and assess the significance of the various contributions.
We calculate the cross section for the inclusive production of
B
mesons in
p
p
and
p
p
¯
collisions at next-to-leading order in the general-mass variable-flavor-number scheme and show that a suitable ...choice of factorization scales leads to a smooth transition to the fixed-flavor-number scheme. Our numerical results are in good agreement with data from the Tevatron and LHC experiments at small and at large transverse momenta.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We present in analytic form the matching conditions for the strong-coupling constant alphas(nf) (mu) at the flavor thresholds to four loops in the modified minimal-subtraction scheme. Taking into ...account the present knowledge on the coefficient beta4 of the Callan-Symanzik beta function of quantum chromodynamics, we thus derive a five-loop formula for alphas(nf) (mu) together with appropriate relationships between the asymptotic scale parameters Lamda(nf) for different numbers of flavors nf.
We calculate the cross section for the inclusive production of mesons in and collisions at next-to-leading order in the general-mass variable-flavor-number scheme and show that a suitable choice of ...factorization scales leads to a smooth transition to the fixed-flavor-number scheme. Our numerical results are in good agreement with data from the Tevatron and LHC experiments at small and at large transverse momenta.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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