Invited Paper at Quark Matter 2008, 20th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions, Jaipur, India - 4-10 February 2008; Submitted to Journal of Physics G, Nuclear Physics; 10 pages, 2 figures
This paper begins with a summary of the status of the Large Hadron Collider at CERN, including the lead-ion injector chain and the plans for the first phases of commissioning and operation with colliding proton beams. In a later phase, the LHC will collide lead nuclei at centre-of-mass energies of 5.5 TeV per colliding nucleon pair. This leap to 28 times beyond what is presently accessible will open up a new regime, not only in the experimental study of nuclear matter, but also in the beam physics of hadron colliders. Ultraperipheral and hadronic interactions of highly-charged beam nuclei will cause beam losses that dominate the luminosity decay and may quench superconducting magnets, setting upper limits on luminosity and stored beam current. Lower limits are set by beam instrumentation. On the other hand, coherent radiation by the nuclear charges should provide natural cooling to overcome intra-beam scattering. As with protons, a flexible, staged approach to full performance will test the limits and make optimal use of scheduled beam time.
Construction of future Muon Collider (or dedicated mu-ring) tangential to nucleus colliders will give opportunity to realize mu-A collisions at multi-TeV center of mass energies at a luminosity of order of 10^29-10^30 cm^-2s^-1. Obviously, such colliders will essentially enlighten fundamentals of strong interactions from quark to nucleus levels as well as clarify QCD basics. This paper is devoted to estimation of main parameters of the FCC, SppC, HL-LHC, HE-LHC and RHIC based muon-nucleus collider proposals by the software AloHEP.
The physics search potential of the FEL {gamma} - Nucleus colliders is analysed using excitations of the (232)Th nucleus. It is shown that, due to the monochromacity of FEL {gamma} beam and high statistics, proposed colliders will play an important role in the field of "traditional" nuclear physics.
The feasibility of a CLIC-LHC based FEL-nucleus collider is investigated. It is shown that the proposed scheme satisfies all requirements of an ideal photon source for the Nuclear Resonance Fluorescence method. The tunability, monochromaticity and high polarization of the FEL beam together with high statistics and huge energy of LHC nucleus beams will give an unique opportunity to determine different characteristics of excited nuclear levels. The physics potential of the proposed collider is illustrated for a beam of Pb nuclei.
The feasibility of a CLIC-LHC based FEL-nucleus collider is investigated. It is shown that the proposed scheme satisfies all requirements of an ideal photon source for the Nuclear Resonance Fluorescence method. The physics potential of the proposed collider is illustrated for a beam of Pb nuclei.
Main parameters of the FEL-RHIC collider are estimated. The physics search potential of this machine is illustrated using excitations of the ^{232}Th nucleus as an example. It is shown that, due to the tunability and monochromacity of FEL beam and high statistics, proposed collider will play an important role in the field of ''traditional'' nuclear physics.
A new method has been considered to investigate the scattering reactions with photons on fully ionized nuclei. To induce $γ$-nucleus collisions a free electron laser and a heavy ion synchrotron have been considered bringing them together. Main parameters of the collider (especially LHC and HERA for the acceleration of nuclei) have been estimated. Rough calculations have also been made for the cross sections of the excited nuclei production. Finally, some design problems involving the collider have been considered.
Concerning future lepton-nucleus colliders, International Linear Collider (ILC) and Plasma Wake Field Accelerator-Linear Collider (PWFA-LC) electrons in order of 0.5 TeV and 5 TeV, respectively, colliding with Super proton-proton Collider (SppC)'s 3075 TeV lead ions, are considered as "linac-ring eA" options. In addition, 1.5 TeV option of the Muon Collider (MC) vs 3075 TeV lead ions of the SppC is also taken into account as a "ring-ring muA" collider. Luminosity values of the SppC-based eA and muA colliders are estimated. 3075 TeV lead parameters for 100 km-circumference option of the SppC ar…
Options for future $lepton-proton,lepton-nucleus,γ-proton,γ-nucleus$ and FEL$γ-nucleus$ colliders are discussed. In the spirit of this content, we consider TESLAxHERA, LEPxLHC, $μ$xTEVATRON, exRHIC, LinacxLHC, $\sqrt{s}=3TeV$ $μp$ and CLIC based colliders.
The production of collective excitations of the (154)Sm at FEL{gamma}+LHC collider is investigated. We show that this machine will be a powerful tool for investigation of high energy level excitations.
Simple generic expressions to compute double-parton scattering (DPS) cross sections in high-energy proton-nucleus and nucleus-nucleus collisions, as a function of the corresponding single-parton cross sections, are presented. Estimates of DPS contributions are studied for two specific processes at LHC energies: (i) same-sign W-boson pair production in p-Pb, and (ii) double-J/psi production in Pb-Pb, using NLO predictions with nuclear parton densities for the corresponding single-parton cross sections. The expected DPS cross sections and event rates after typical acceptance and efficiency losse…
A generic expression of double-parton scattering cross sections in high-energy nucleus-nucleus (A-A) collisions is derived as a function of the corresponding single-parton hard cross sections and of the A-A event centrality. We consider the case of prompt-J/psi production in lead-lead (Pb-Pb) at the CERN Large Hadron Collider and find that about 20% (35%) of the J/psi events in minimum-bias (most central) collisions contain a second J/psi from double parton interactions. In Pb-Pb at 5.5 TeV, in the absence of final-state effects, about 240 double-J/psi events are expected per unit midrapidity …
Construction of the ERLC (twin LC) collider tangential to LHC or FCC will give opportunity to realize eA collisions at multi-TeV center-of-mass energies. Luminosity estimations show that values comparable with that of ERL60 based eA colliders are achievable while center of mass energies are essentially higher. Certainly, proposed eA colliders have great potential for clarifying QCD basics and nuclear structure.
Main parameters of different colliders which can be realized if a special 1 TeV energy linear electron accelerator or corresponding linear collider is constructed tangential to LHC are estimated. It is shown that L_ep=10^32cm^-2s^-1 at sqrt(s_ep)=5.29 TeV can be achieved within moderate upgrade of LHC parameters. Then, gamma-p collider with the same luminosity and sqrt(s)=4.82 TeV can be realized using Compton backscattering of laser beam off the electron beam. Concerning the nucleus beam, L*A=10^31cm^-2s^-1 can be achieved at least for light and medium nuclei both for eA and gamma-A options. …
In this work we analyse the theoretical uncertainties on the predictions for the photoproduction of light vector mesons in coherent pp, pA and AA collisions at the LHC energies using the color dipole approach. In particular, we present our predictions for the rapidity distribution for rh0 and phi photoproduction and perform an analysis on the uncertainties associated to the choice of vector meson wavefunctionand the phenomenological models for the dipole cross section. Comparison is done with the recent ALICE analysis on coherent production of rho at 2.76 TeV in PbPb collisions.
Exclusive photoproduction of heavy quarkonia in high-energy ultraperipheral ion-ion interactions (gamma A --> V A, where V = J/Psi,Upsilon and the nucleus A remains intact) offers a useful means to constrain the small-x nuclear gluon density. We discuss preliminary results on J/Psi photoproduction in Au-Au collisions at RHIC energies, as well as full simulation-reconstruction studies of photo-produced Upsilon's in Pb-Pb interactions at the LHC.
Main parameters and physics goals of different colliders, which can be realized if a special 1 TeV energy linear electron accelerator or corresponding linear collider is constructed tangential to LHC, are discussed. It is shown that L_(ep)=10^(32)cm^(-2)s^(-1) at sqrt(s_(ep))=5.29 TeV can be achieved within moderate upgrade of LHC parameters. Then, Gamma-p collider with he same luminosity and sqrt(s)=4.82 TeV can be realized using Compton backscattering of laser beam off the electron beam. Concerning the nucleus beam, L*A=10^(31)cm^(-2)s^(-1) can be achieved at least for light and medium nucle…
The stochastic dynamics of c and b quarks in the fireball created in nucleus-nucleus collisions at RHIC and LHC is studied employing a relativistic Langevin equation, based on a picture of multiple uncorrelated random collisions with the medium. Heavy-quark transport coefficients are evaluated within a pQCD approach, with a proper HTL resummation of medium effects for soft scatterings. The Langevin equation is embedded in a multi-step setup developed to study heavy-flavor observables in pp and AA collisions, starting from a NLO pQCD calculation of initial heavy-quark yields, complemented in th…
A snapshot of the results for heavy-flavour observables in heavy-ion (AA) collisions at RHIC and LHC obtained with our transport calculations is displayed. The initial charm and beauty production is simulated through pQCD tools (POWHEG+PYTHIA) and is validated through the comparison with data from pp collisions. The propagation of c and b quarks in the medium formed in heavy-ion collisions is studied through a transport setup based on the relativistic Langevin equation. With respect to past works we perform a more systematic study, providing results with different choices of transport coeffici…
Experimental data for hadron radial and elliptic flow are used to investigate their influence on the shape of the thermal photon spectrum at RHIC. Leaving alone the actual mechanism of photon production and its time evolution, we concentrate on the spectrum shape. Radial and longitudinal flow of the bulk can change significantly the observed photon energy spectrum via the Doppler Effect. Experimental thermal photon data are described by local frame temperature parameter which depends on the assumption of longitudinal and radial flow. From the observed hadron elliptic flow we estimate the modul…
We present a study of the heavy-flavor dynamics in nucleus-nucleus collisions. The initial (hard) production of c and b quarks is taken from NLO pQCD predictions. The presence of a hot medium (a Quark Gluon Plasma described by hydrodynamics) affects the final spectra of open-charm (beauty) hadrons and their decay electrons with respect to what found in pp collisions. The propagation of c and b quarks in the plasma is based on a picture of multiple uncorrelated random collisions, described by a relativistic Langevin equation. A microscopic evaluation of the transport coefficients is provided wi…
Proton-nucleus (p+A) collisions have long been recognized as a crucial component of the physics programme with nuclear beams at high energies, in particular for their reference role to interpret and understand nucleus-nucleus data as well as for their potential to elucidate the partonic structure of matter at low parton fractional momenta (small-x). Here, we summarize the main motivations that make a proton-nucleus run a decisive ingredient for a successful heavy-ion programme at the Large Hadron Collider (LHC) and we present unique scientific opportunities arising from these collisions. We al…
In this talk I review the New Physics reach of semileptonic beta decay experiments, and their interplay with LHC searches. Assuming the new particles are heavy enough we can use an Effective Field Theory approach to analyze the LHC searches, what allows us to perform a direct and model-independent comparison with low-energy experiments.
We discuss the prospects of using jets as precision probes in electron-nucleus collisions at the future Electron-Ion Collider. Jets produced in deep-inelastic scattering can be calibrated by a measurement of the scattered electron. Such electron-jet "tag and probe" measurements call for an approach that is orthogonal to most HERA jet measurements as well as previous studies of jets at the future EIC. We present observables such as the electron-jet momentum balance, azimuthal correlations and jet substructure, which can provide constraints on the parton transport coefficient in nuclei. We compa…
The exclusive reconstruction of D^0 mesons in the ALICE experiment allows to study the QCD energy loss of charm quarks in the deconfined quark-gluon plasma (QGP) medium expected to be produced in central nucleus-nucleus collisions at the Large Hadron Collider.
The forthcoming LHC measurement of hadron multiplicity in proton-nucleus collisions is a crucial test of the k_t factorization and gluon saturation based models. Here, we provide quantitative predictions for the pseudorapidity distribution of charged particles produced in minimum bias proton-nucleus collisions at the LHC based on the idea of gluon saturation in the color-glass condensate framework. Our formulation gives good descriptions of the LHC and RHIC data for the charged-hadron multiplicities in both proton-proton and nucleus-nucleus collisions, and also the deep inelastic scattering at…
Single and pair top-quark production in proton-lead (p-Pb) and lead-lead (Pb-Pb) collisions at the CERN Large Hadron Collider (LHC) and future circular collider (FCC) energies, are studied with next-to-leading-order perturbative QCD calculations including nuclear parton distribution functions. At the LHC, the pair-production cross sections amount to sigma(t-tbar) = 3.4 mub in Pb-Pb at sqrt(s) = 5.5 TeV, and sigma(t-tbar) = 60 nb in p-Pb at sqrt(s) = 8.8 TeV. At the FCC energies of sqrt(s) = 39 and 63 TeV, the same cross sections are factors of 90 and 55 times larger respectively. In the lepton…
We calculate production rates for several hard processes in ultraperipheral proton-nucleus and nucleus-nucleus collisions at the LHC. The resulting high rates demonstrate that some key directions in small $x$ research proposed for HERA will be accessible at the LHC through these ultraperipheral processes. Indeed, these measurements can extend the HERA $x$ range by roughly a factor of 10 for similar virtualities. Nonlinear effects on the parton densities will thus be significantly more important in these collisions than at HERA.
The cross section for the nuclear diffractive dissociation in proton-lead collisions at the LHC is estimated. Based on the current theoretical uncertainties for the single (target) diffactive cross section in hadron-hadron reactions one obtains sigma_SD(5.02 TeV) = 19.67 \pm 5.41 mb and sigma_SD(8.8 TeV) = 18.76 \pm 5.77 mb, respectively. The invariant mass M_X for the reaction pPb -> pX is also analyzed. Discussion is performed on the main theoretical uncertainties associated to the calculations.
We study in details the space-time dependence of the production of muonic, pionic, and other exotic atoms by the coherent photon exchange between nuclei at the Large Hadron Collider (LHC) at CERN. We show that a multipole expansion of the electromagnetic interaction yields an useful insight of the bound-free production mechanism which has not been explored in the literature. Predictions for the spatial, temporal, and angular distribution, as well as the total cross sections, for the production of exotic atoms are also included.
We use an event-by-event hydrodynamical description of the heavy-ion collision process with Glauber initial conditions to calculate the thermal emission of photons. The photon rates in the hadronic phase follow from a spectral function approach and a density expansion, while in the partonic phase they follow from the AMY perturbative rates. The calculated photon elliptic flows are lower than those reported recently by both the ALICE and PHENIX collaborations.
Proton-nucleus collisions (p+A) at LHC energies provide a rigorous test of the Color Glass Condensate (CGC), a model proposed to describe the high energy limit of Quantum Chromodynamics. In the CGC the average multiplicity of charged particles at midrapidity in p+A collisions depends logarithmically on the number of participants, $N_{part}$. In contrast, the Wounded Nucleon Model (WNM) of independent nucleon-nucleon scatterings, verified at RHIC energies, predicts that multiplicity in p+A depends linearly on $N_{part}$. We argue that for the first time, the dependence of mean multiplicity on $…
In this paper we investigate the Exotic Charmonium (EC) production in $γγ$ interactions present in proton-proton, proton-nucleus and nucleus-nucleus collisions at the CERN Large Hadron Collider (LHC) energies as well as for the proposed energies of the Future Circular Collider (FCC). Our results demonstrate that the experimental study of these processes is feasible and can be used to constrain the theoretical decay widths and shed some light on the configuration of the considered multiquark states.
Apparently universal trends have been observed in relativistic nucleus-nucleus collisions up to RHIC energies. Here, we review these trends and we discuss their agnostic extrapolation to heavy ion collisions at the LHC.
The potential of the ALICE, ATLAS, CMS and LHCb detectors for the measurement of quarkonium in heavy-ion collisions, both in nucleus-nucleus (A-A) and in proton-nucleus (p-A) interactions, in the years 2015 until about 2030 in the LHC Runs 2, 3 and 4 with larger statistics and detector upgrades is described. A selection of newly available observables is discussed.
For the first time in the CERN history two experimental programs devoted to study nucleus-nucleus collisions at high energies are performed in parallel. In the SPS ion program, carried out by NA61/SHINE, interactions of light and medium size ions in the energy range 5-20 GeV are investigated. The program aims to discover the critical point of strongly interacting matter as well as establish properties of the onset of deconfinement. In 2010 ALICE, ATLAS and CMS at LHC recorded first data on Pb+Pb collisions at the highest energy reached up to now, 2760 GeV. This opens a new exciting area in the…
We introduce a global analysis of collinearly factorized nuclear parton distribution functions (PDFs) including, for the first time, data constraints from LHC proton-lead collisions. In comparison to our previous analysis, EPS09, where data only from charged-lepton-nucleus deep inelastic scattering (DIS), Drell-Yan (DY) dilepton production in proton-nucleus collisions and inclusive pion production in deuteron-nucleus collisions were the input, we now increase the variety of data constraints to cover also neutrino-nucleus DIS and low-mass DY production in pion-nucleus collisions. The new LHC da…
We compute v4/(v2)^2 in ideal and viscous hydrodynamics. We investigate its sensitivity to details of the hydrodynamic model and compare the results to experimental data from RHIC. Whereas v2 has a significant sensitivity only to initial eccentricity and viscosity while being insensitive to freeze out temperature, we find that v4/(v2)^2 is quite insensitive to initial eccentricity. On the other hand, it can still be sensitive to shear viscosity in addition to freeze out temperature, although viscous effects do not universally increase v4/(v2)^2 as originally predicted. Consistent with data, we…
An experimental overview of the energy dependence of strangeness production is presented. The strange hadrons are considered a good probe to study the QCD matter created in relativistic nucleus-nucleus collisions. The heavy-ion experiments at SPS, RHIC, and LHC have recorded a wealth of data in proton-proton, proton-nucleus and nucleus-nucleus collisions at several beam energies. In this proceeding, I discuss the invariant yield and azimuthal anisotropy measurement of strange hadrons in nucleus-nucleus collisions at SPS, RHIC, and LHC.
Simple power counting arguments in the dilute-dense framework of the Color Glass Condensate (CGC) Effective Field Theory predict that even and odd azimuthal anisotropy harmonics of two-particle correlations in proton-nucleus collisions at the LHC will respectively satisfy v^2_{2n} ~ N_{ch}^0 and v^2_{2n+1} ~ N_{ch}, where N_{ch} denotes the number of charged particles. We show that these expectations are borne out qualitatively, and even quantitatively, within systematic uncertainties, for v_2 and v_4 in comparisons with data from the ATLAS collaboration. We also observe that ATLAS data for th…
We investigate the potentialities offered by the study of J/psi exclusive photo-production in ultra-peripheral collisions at a fixed-target experiment using the proton and lead LHC beams (generically denoted as AFTER@LHC) on hydrogen targets and at RHIC in the collider mode. We compare the expected counting rates in both set-ups. Studying Single-Transverse-Spin Asymmetries (A_N) in such a process provides a direct path to the proton Generalised Parton Distribution (GPD) E_g(x,xi,t). We evaluate the expected precision on A_N for realistic conditions with the LHCb detector in pH(pol) and PbH(pol…
We obtain prompt di-photon cross-section in proton-nucleus collisions in Hamiltonian light-cone approach within a hybrid approximation, treating the projectile proton in the parton model and the target nucleus in the Color-Glass-Condensate approach. We study in details the di-photon correlations in quark-nucleus and proton-nucleus collisions at RHIC and the LHC. We show that the single fragmentation di-photon produces the away side correlations peak, and the double fragmentation component of prompt di-photon is responsible for the near-side peak, and the long-range in rapidity near-side azimut…
Two Key Day-One Observables in Electron-Nucleus Collisions at the Upcoming Electron-Ion Collider and Their Implications for Baryon Number Carrier Investigations
Institute of Theoretical Physics, State Key Laboratory of Quantum Optics Technologies and Devices & Collaborative Innovation Center of Extreme Optics, Shanxi University（山西大学理论物理研究所、量子光学技术与器件国家重点实验室及极端光学协同创新中心）；Laboratory of High Energy Physics, Physical-Technical Institute of Uzbekistan Academy of Sciences（乌兹别克斯坦科学院物理技术研究所高能物理实验室）；Department of Natural Sciences, National University of Science and Technology MISIS (NUST MISIS), Almalyk Branch（国立科技大学米西思（NUST MISIS）阿尔马雷克分校自然科学系）
We model effects of color fluctuations (CFs) in the light-cone photon wave function and for the first time make predictions for the distribution over the number of wounded nucleons $ν$ in the inelastic photon-nucleus scattering. We show that CFs lead to a dramatic enhancement of this distribution at $ν=1$ and large $ν> 10$. We also study the implications of different scales and CFs in the photon wave function on the total transverse energy $ΣE_T$ and other observables in inelastic $γA$ scattering with different triggers. Our predictions can be tested in proton-nucleus and nucleus-nucleus ultra…
The current experimental and theoretical status of hadron and jet production at large transverse momentum in high-energy nucleus-nucleus collisions is summarised. The most important RHIC results are compared to theoretical parton energy loss predictions providing direct information on the (thermo)dynamical properties of hot and dense QCD matter. Prospects for the LHC are also outlined.
There are a large number of physics programs one can explore in electron-nucleus collisions at a future electron-ion collider. Collision geometry is very important in these studies, while the measurement for an event-by-event geometric control is rarely discussed in the prior deep inelastic scattering experiments off a nucleus. This paper seeks to provide some detailed studies on the potential of tagging collision geometries through forward neutron multiplicity measurements with a zero degree calorimeter. This type of geometry handle, if achieved, can be extremely beneficial in constraining nu…
The LHC brings nuclear collisions to the TeV scale for the first time and the first data show the qualitative differences of this new regime. The corresponding phase-space available encompasses completely uncharted regions of QCD in which high-density or high-temperature domains can be identified. Proton-nucleus runs are essential for a complete interpretation of the data and for the study of new regimes dominated by large occupation numbers in the hadronic wave function. I comment here the physics opportunities for p+Pb runs at the LHC and d+Au runs at RHIC and the corresponding needs in view…
Gluons may converge to a stable state at a critical momentum in nucleon. This gluon condensation will greatly increase the proton-proton cross section provided that the collision energies exceed the gluon condensation threshold. Based on the analyses of cosmic gamma-ray spectra, we find that the $p-Pb$ and $Pb-Pb$ collisions at the LHC are close to the energy region of the gluon condensation effect. We warn that for the next generation of hadron colliders increasing the collision energies, the extremely strong gamma-rays will be emitted in a narrow space of the accelerator due to the gluon con…
We review current results on physics with photons at the LHC and discuss realistic perspectives of photon physics at future colliders. In particular, we focus on Standard Model (SM) measurements with photons at the upcoming high-luminosity and a possible high-energy LHC as well as jet measurements at an Electron-Ion Collider (EIC) to be constructed either at BNL or at JLAB and their potential to constrain nuclear parton densities. We also discuss future searches for physics beyond the SM with photons in the high-luminosity phase of the LHC.
In view of the good agreement between the LHCb prompt-eta(c) data at sqrt(s)=7 and 8 TeV and the NLO colour-singlet model predictions --i.e. the leading v^2 NRQCD contribution--, we provide predictions in the LHCb acceptance for the forthcoming 13 TeV analysis bearing on data taken during the LHC Run2. We also provide predictions for sqrt(s)=115 GeV for proton-hydrogen collisions in the fixed-target mode which could be studied during the LHC Run3. Our predictions are complemented by a full theoretical uncertainty analysis. In addition to cross section predictions, we elaborate on the uncertain…
