√s NN = 5.02 TeV using the ALICE detector at the LHC. The measurement covers the p T interval 0.5 < p T < 12 GeV/c and the rapidity range −1.065 < y cms < 0.135 in the centre-of-mass reference frame. The contribution of electrons from background sources was subtracted using an invariant mass approach. The nuclear modification factor R pPb was calculated by comparing the p T -differential invariant cross section in p-Pb collisions to a pp reference at the same centre-of-mass energy, which was obtained by interpolating measurements at √ s = 2.76 TeV and √ s = 7 TeV. The R pPb is consistent with unity within uncertainties of about 25%, which become larger for p T below 1 GeV/c. The measurement shows that heavy-flavour production is consistent with binary scaling, so that a suppression in the high-p T yield in Pb-Pb collisions has to be attributed to effects induced by the hot medium produced in the final state. The data in p-Pb collisions are described by recent model calculations that include cold nuclear matter effects. IntroductionThe Quark-Gluon Plasma (QGP) [1,2], a colour-deconfined state of strongly-interacting matter, is predicted to exist at high temperature according to lattice Quantum Chromodynamics (QCD) calculations [3]. These conditions can be reached in ultra-relativistic heavy-ion collisions [4][5][6][7][8][9][10]. Charm and beauty (heavy-flavour) quarks are mostly produced in initial hard scattering processes on a very short time scale, shorter than the formation time of the QGP medium [11], and thus experience the full temporal and spatial evolution of the collision. While interacting with the QGP medium, heavy quarks lose energy via elastic and radiative processes [12][13][14]. Heavy-flavour hadrons are therefore well-suited probes to study the properties of the QGP. The effect of energy loss on heavy-flavour production can be characterised via the nuclear modification factor (R AA ) of heavy-flavour hadrons. The R AA is defined as the ratio of the heavy-flavour hadron yield in nucleusnucleus (A-A) collisions to that in proton-proton (pp) collisions scaled by the average number of binary nucleon-nucleon collisions. The R AA is studied differentially as a function of transverse momentum (p T ), rapidity ( y) and collision centrality. It was measured at the Relativistic Heavy Ion Collider (RHIC) [15][16][17][18] and at the Large Hadron Collider (LHC) [19][20][21][22]. At RHIC, in central The interpretation of the measurements in A-A collisions requires the study of heavy-flavour production in p-A collisions, which provides access to cold nuclear matter (CNM) effects. These effects are not related to the formation of a colour-deconfined medium, but are present in case of colliding nuclei (or protonnucleus). An important CNM effect in the initial state is partondensity shadowing or saturation, which can be described using modified parton distribution functions (PDF) in the nucleus [23] or using the Color Glass Condensate (CGC) effective theory [24]. Further CNM effects include energy loss [25] in...

We investigate the thermodynamic properties and the lattice stability of two-dimensional crystalline membranes, such as graphene and related compounds, in the low temperature quantum regime T → 0. A key role is played by the anharmonic coupling between in-plane and out-of-plane lattice modes that, in the quantum limit, has very different consequences from those in the classical regime. The role of retardation, namely of the frequency dependence, in the effective anharmonic interactions turns out to be crucial in the quantum regime. We identify a crossover temperature, T * , between classical and quantum regimes, which is ∼ 70 − 90 K for graphene. Below T * , the heat capacity and thermal expansion coefficient decrease as power laws with decreasing temperature, tending to zero for T → 0 as required by the third law of thermodynamics.

Sub-laser cycle time scale of electronic response to strong laser fields enables attosecond dynamical imaging in atoms, molecules and solids 1-4 . Optical tunneling and high harmonic generation 2, 5-7 are the hallmarks of attosecond imaging in optical domain, including imaging of phase transitions in solids 8, 9 . Topological phase transition yields a state of matter intimately linked with electron dynamics, as manifested via the chiral edge currents in topological insulators 10 . Does topological state of matter leave its mark on optical tunnelling 1 arXiv:1806.11232v2 [physics.optics]

Out of plane vibrations are suppressed in graphene layers placed on a substrate. These vibrations, in suspended samples, are relevant for the understanding of properties such as the electrical resistivity, the thermal expansion coefficient, and others. We use a general framework to study the properties of the out of plane mode in graphene on different substrates, taking into account the dynamics of the substrate. We discuss broadening of this mode and how it hybridizes with the substrate Rayleigh mode, comparing our model with experimental observations. We use the model to estimate the substrate induced changes in the thermal expansion coefficient and in the temperature dependence of the electrical resistivity.

We theoretically and experimentally investigated wasp-waisted magnetic hysteresis curves at a low temperature for CoFe2O4 nanopowders.

We argue, for a wide class of systems including graphene, that in the low temperature, high density, large separation and strong screening limits the drag resistivity behaves as d(-4), where d is the separation between the two layers. The results are independent of the energy dispersion relation, the dependence on momentum of the transport time, and the electronic wave function structure. We discuss how a correct treatment of the electron-electron interactions in an inhomogeneous dielectric background changes the theoretical analysis of the experimental drag results of Kim et al (2011 Phys. Rev. B 83 161401). We find that a quantitative understanding of the available experimental data (Kim et al 2011 Phys. Rev. B 83 161401) for drag in graphene is lacking.

We investigate the spontaneous emission rate of a two-level quantum emitter near a graphene-coated substrate under the influence of an external magnetic field or strain induced pseudo-magnetic field. We demonstrate that the application of the magnetic field can substantially increase or decrease the decay rate. We show that a suppression as large as 99% in the Purcell factor is achieved even for moderate magnetic fields. The emitter's lifetime is a discontinuous function of |B|, which is a direct consequence of the occurrence of discrete Landau levels in graphene. We demonstrate that, in the near-field regime, the magnetic field enables an unprecedented control of the decay pathways into which the photon/polariton can be emitted. Our findings strongly suggest that a magnetic field could act as an efficient agent for on-demand, active control of light-matter interactions in graphene at the quantum level.The possibility of tailoring light-matter interactions at a quantum level has been a sought-after goal in optics since the pioneer work of Purcell 1 , where it was first shown that the environment can strongly modify the spontaneous emission (SE) rate of a quantum emitter. To achieve such objective, several approaches have been proposed so far. One of them is to investigate SE in different system geometries [2][3][4][5][6][7][8][9][10][11] . Advances in nanofabrication techniques have not only allowed the increase of the spectroscopic resolution of molecules in complex environments 12 , but have also led to the use of nanometric objects, such as antennas and tips, to modify the lifetime, and enhance the fluorescence of single molecules [13][14][15][16] . The presence of metamaterials may also strongly affect quantum emitters' radiative processes. For instance, the impact of negative refraction and of the hyperbolic dispersion on the SE have been investigated [17][18][19] . Also, the influence of cloaking devices on the SE of atoms has been recently addressed 20 .Progress in plasmonics has also allowed for a unprecedented control of light-matter interactions at a quantum level. When the emitter is located near a plasmonic structure it may experience a strong enhancement of the local field. This effect can be exploited in the development of important applications in nanoplasmonics [21][22][23][24][25] . However, structures made of noble metals are hardly tunable, which unavoidably limit their application in photonic devices. To circumvent these limitations, graphene has emerged as an alternative plasmonic material due to its extraordinary electronic and optical properties [26][27][28][29][30][31] . Indeed, graphene hosts extremely confined plasmons, facilitating strong light-matter interactions [28][29][30][31] . In addition, the plasmon spectrum in doped graphene is highly tunable through electrical or chemical modification of the charge carrier density. Due to these properties, graphene is a promising material platform for several photonic applications, specially in the THz frequency range 30 . At the quantum leve...

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