2,178 research outputs found
Vector meson production in the dimuon channel in the ALICE experiment at the LHC
The purpose of the ALICE experiment at the LHC is the study of the Quark
Gluon Plasma (QGP) formed in ultra-relativistic heavy-ion collisions, a state
of matter in which quarks and gluons are deconfined. The properties of this
state of strongly-interacting matter can be accessed through the study of light
vector mesons (, and ). Indeed, the strange quark content
() of the meson makes its study interesting in connection with
the strangeness enhancement observed in heavy-ion collisions. Moreover,
and spectral function studies give information on chiral symmetry
restoration. Vector meson production in pp collisions is important as a
baseline for heavy-ion studies and for constraining hadronic models. We present
results on light vector meson production obtained with the muon spectrometer of
the ALICE experiment in pp collisions at =7 TeV. Production ratios,
integrated and differential cross sections for and are
presented. Those results are extracted for GeV/ and
Feasibility studies for quarkonium production at a fixed-target experiment using the LHC proton and lead beams (AFTER@LHC)
Used in the fixed-target mode, the multi-TeV LHC proton and lead beams allow
for studies of heavy-flavour hadroproduction with unprecedented precision at
backward rapidities - far negative Feyman-x - using conventional detection
techniques. At the nominal LHC energies, quarkonia can be studies in detail in
p+p, p+d and p+A collisions at sqrt(s_NN) ~ 115 GeV as well as in Pb+p and Pb+A
collisions at sqrt(s_NN) ~ 72 GeV with luminosities roughly equivalent to that
of the collider mode, i.e. up to 20 fb-1 yr-1 in p+p and p+d collisions, up to
0.6 fb-1 yr-1 in p+A collisions and up to 10 nb-1 yr-1 in Pb+A collisions. In
this paper, we assess the feasibility of such studies by performing fast
simulations using the performance of a LHCb-like detector.Comment: 12 pages, 14 figure
Physics perspectives with AFTER@LHC (A Fixed Target ExpeRiment at LHC)
AFTER@LHC is an ambitious fixed-target project in order to address open questions in the domain of proton and neutron spins, Quark Gluon Plasma and high- physics, at the highest energy ever reached in the fixed-target mode. Indeed, thanks to the highly energetic 7 TeV proton and 2.76 A.TeV lead LHC beams, center-of-mass energies as large as = 115 GeV in pp/pA and = 72 GeV in AA can be reached, corresponding to an uncharted energy domain between SPS and RHIC. We report two main ways of performing fixed-target collisions at the LHC, both allowing for the usage of one of the existing LHC experiments. In these proceedings, after discussing the projected luminosities considered for one year of data taking at the LHC, we will present a selection of projections for light and heavy-flavour production.Peer Reviewe
Heavy-ion Physics at a Fixed-Target Experiment Using the LHC Proton and Lead Beams (AFTER@LHC): Feasibility Studies for Quarkonium and Drell-Yan Production
We outline the case for heavy-ion-physics studies using the multi-TeV lead
LHC beams in the fixed-target mode. After a brief contextual reminder, we
detail the possible contributions of AFTER@LHC to heavy-ion physics with a
specific emphasis on quarkonia. We then present performance simulations for a
selection of observables. These show that , and
production in heavy-ion collisions can be studied in new energy and
rapidity domains with the LHCb and ALICE detectors. We also discuss the
relevance to analyse the Drell-Yan pair production in asymmetric
nucleus-nucleus collisions to study the factorisation of the nuclear
modification of partonic densities and of further quarkonia to restore their
status of golden probes of the quark-gluon plasma formation.Comment: 18 pages, 7 figure
Magnetic fields from reionisation
We present a complementary study to a new model for generating magnetic
fields of cosmological interest. The driving mechanism is the photoionisation
process by photons provided by the first luminous sources. Investigating the
transient regime at the onset of inhomogeneous reionisation, we show that
magnetic field amplitudes as high as Gauss can be obtained
within a source lifetime. Photons with energies above the ionisation threshold
accelerate electrons, inducing magnetic fields outside the Stroemgren spheres
which surround the ionising sources. Thanks to their mean free path, photons
with higher energies propagate further and lead to magnetic field generation
deeper in the neutral medium. We find that soft X-ray photons could contribute
to a significant premagnetisation of the intergalactic medium at a redshift of
z=15.Comment: accepted for publication in A&
Feasibility Studies for Single Transverse-Spin Asymmetry Measurements at a Fixed-Target Experiment Using the LHC Proton and Lead Beams (AFTER@LHC)
The measurement of Single Transverse-Spin Asymmetries, A_N, for various quarkonium states and DrellâYan lepton pairs can shed light on the orbital angular momentum of quarks and gluons, a fundamental ingredient of the proton-spin puzzle. The AFTER@LHC proposal combines a unique kinematic coverage and large luminosities thanks to the Large Hadron Collider beams to deliver precise measurements, complementary to the knowledge provided by collider experiments such as at RHIC. In this paper, we report on sensitivity studies for J/ Ï, ΄ and DrellâYan A_N done using the performance of LHCb-like or ALICE-like detectors, combined with polarised gaseous hydrogen and helium-3 targets. In particular, such analyses will provide us with new insights and knowledge about transverse-momentum-dependent parton distribution functions for quarks and gluons and on twist-3 collinear matrix elements in the proton and the neutron
Heavy-ion Physics at a Fixed-Target Experiment Using the LHC Proton and Lead Beams (AFTER@LHC): Feasibility Studies for Quarkonium and Drell-Yan Production
We outline the case for heavy-ion-physics studies using the multi-TeV lead LHC beams in the fixed-target mode. After a brief contextual reminder, we detail the possible contributions of AFTER@LHC to heavy-ion physics with a specific emphasis on quarkonia. We then present performance simulations for a selection of observables. These show that , and production in heavy-ion collisions can be studied in new energy and rapidity domains with the LHCb and ALICE detectors. We also discuss the relevance to analyse the DrellâYan pair production in asymmetric nucleusânucleus collisions to study the factorisation of the nuclear modification of partonic densities and of further quarkonium states to restore their status of golden probes of the quarkâgluon plasma formation.Peer Reviewe
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