7,072 research outputs found
Coulomb corrections to inclusive cross sections at the future Electron - Ion Collider
The experimental results of the future electron -- ion () collider are
expected to constrain the dynamics of the strong interactions at small values
of the Bjorken -- variable and large nuclei. Recently it has been suggested
that Coulomb corrections can be important in inclusive and diffractive
interactions. In this paper we present a detailed investigation of the impact
of the Coulomb corrections to some of the observables that will be measured in
the future collider. In particular, we estimate the magnitude of these
corrections for the charm and longitudinal cross sections in inclusive and
diffractive interactions. Our results demonstrate that the Coulomb corrections
for these observables are negligible, which implies that they can be used to
probe the QCD dynamics.Comment: 9 pages, 6 figures. Improved version to be published in Physical
Review
Quarkonium+ production in coherent hadron - hadron interactions at LHC energies
In this paper we study the ( and )
production in coherent hadron - hadron interactions at LHC energies.
Considering the ultrarelativistic protons as a source of photons, we estimate
the cross section using the
non-relativistic QCD (NRQCD) factorization formalism and considering different
sets of values for the matrix elements. Our results for the total cross sections and rapidity distributions at
and 14 TeV demonstrate that the experimental analysis of the
production at LHC is feasible.Comment: 6 pages, 3 figures, 1 table. Improved version with a new figure.
Version to be published in European Physical Journal
Detection of the Transverse Proximity Effect: Radiative Feedback from Bright QSOs
Measuring the response of the intergalactic medium to a blast of ionizing
radiation allows one to infer the physical properties of the medium and, in
principle, the lifetime and isotropy of the radiating source. The most
sensitive such measurements can be made if the source of radiation is near the
line of sight to a bright background QSO. We present results based on deep
Keck/HIRES observations of the QSO triplet KP76, KP77 and KP78 at z ~2.5, with
separations of 2-3 arcmin on the plane of the sky. Using accurate systemic
redshifts of the QSOs from near-IR spectroscopy, we quantify the state of the
IGM gas in the proximity regions where the expected ionizing flux from the
foreground QSOs exceeds that of the metagalactic background by factors of
10-200, assuming constant and isotropic emission. Based on the unusual
ionization properties of the absorption systems with detected HI, CIV, and OVI,
we conclude that the gas has been significantly affected by the UV radiation
from the nearby QSOs. Aided by observations of the galaxy density near the
foreground QSOs, we discuss several effects that may explain why the transverse
proximity effect has eluded most previous attempts to detect it. Our
observations suggest that the luminosities of KP76 and KP77 have remained
comparable to current values over timescales of, respectively, Delta t > 25 Myr
and 16 Myr < Delta t < 33 Myr - consistent with typical QSO lifetimes estimated
from independent, less-direct methods. There is no evidence that the UV
radiation from either QSO was significantly anisotropic during these intervals.Comment: 19 pages, 17 figures, ApJ, in pres
About possible contribution of intrinsic charm component to inclusive spectra of charmed mesons
We calculate differential energy spectra (-distributions) of charmed
particles produced in proton-nucleus collisions, assuming the existence of
intrinsic heavy quark components in the proton wave function. For the
calculation, the recently proposed factorization scheme is used, based on the
Color Glass Condensate theory and specially suited for predictions of a
production of particles with large rapidities. It is argued that the intrinsic
charm component can, if it exists, dominate in a sum of two components,
intrinsic + extrinsic, of the inclusive spectrum of charmed particles produced
in proton-nucleus collisions at high energies, in the region of medium ,
, and can give noticeable contribution to atmospheric fluxes
of prompt muons and neutrinos.Comment: 10 pages, 4 figures. Version published in J. Phys. G
Theory of standing spin waves in finite-size chiral spin soliton lattice
We present a theory of standing spin wave (SSW) in a monoaxial chiral
helimagnet. Motivated by experimental findings on the magnetic field-dependence
of the resonance frequency in thin films of CrNbS[Goncalves
et al., Phys. Rev. B95, 104415 (2017)], we examine the SSW over a chiral
soliton lattice (CSL) excited by an ac magnetic field applied parallel and
perpendicular to the chiral axis. For this purpose, we generalize Kittel-Pincus
theories of the SSW in ferromagnetic thin films to the case of non-collinear
helimagnet with the surface end spins which are softly pinned by an anisotropy
field. Consequently, we found there appear two types of modes. One is a Pincus
mode which is composed of a long-period Bloch wave and a short-period ripple
originated from the periodic structure of the CSL. Another is a short-period
Kittel ripple excited by space-periodic perturbation which exists only in the
case where the ac field is applied perpendicular the chiral axis. We
demonstrate that the existence of the Pincus mode and the Kittel ripple is
consistent with experimentally found double resonance profile.Comment: 17 pages, 14 figure
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