Dijet, dihadron, hadron-jet angular correlations have been reckoned as important probes of the transverse momentum broadening effects in relativistic nuclear collisions. When a pair of high-energy jets created in hard collisions traverse the quark-gluon plasma produced in heavy-ion collisions, they become de-correlated due to the vacuum soft gluon radiation associated with the Sudakov logarithms and the medium-induced transverse momentum broadening. For the first time, we employ the systematical resummation formalism and establish a baseline calculation to describe the dihadron and hadron-jet angular correlation data in pp and peripheral AA collisions where the medium effect is negligible. We demonstrate that the medium-induced broadening p 2 ⊥ and the so-called jet quenching parameterq can be extracted from the angular de-correlations observed in AA collisions. A global χ 2 analysis of dihadron and hadron-jet angular correlation data renders the best fit p 2 ⊥ ∼ 13 GeV 2 for a quark jet at RHIC top energy. Further experimental and theoretical efforts along the direction of this work shall significantly advance the quantitative understanding of transverse momentum broadening and help us acquire unprecedented knowledge of jet quenching parameter in relativistic heavy-ion collisions.

In this paper, we study the production of isolated-photon plus a jet in pp and P bP b collisions, which can be used as an important probe to the jet transport property in quark gluon plasma created in heavy ion collisions. Normally, there are two types of observables associated with the production of isolated-photon plus a jet, namely, the azimuthal angular correlation and the transverse momentum imbalance. To understand both observables in the full kinematical region, we need to employ the perturbative QCD calculation, which takes into account the hard splitting of partons, together with the Sudakov resummation formalism, which resums soft gluon splittings. Furthermore, by introducing energy-loss into the system, we calculate the enhancement of the momentum imbalance distribution for AA as compared to pp collisions and make predictions for future unfolded experimental data. In addition, in order to extract the jet transport coefficient more precisely in our numerical calculation, we also distinguish quark jets from gluon jets, since they interact with quark gluon plasma with different strengths. This work provides a reliable theoretical tool for the calculation of the gamma-jet correlation, which can lead us to a more precise extraction of the jet transport coefficient in relativistic heavy-ion collisions. I. INTRODUCTIONCreated in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven and later at the Large Hadron Collider (LHC) at CERN, the Quark-Gluon Plasma (QGP) is undoubtedly one of the most interesting discoveries in relativistic heavyion collision experiments. A lot of efforts have been devoted to unravel the mysteries of this strongly-coupled fluid, which is also related to the very early stages of the universe.Due to multiple scatterings with QGP which induces additional gluon radiations, high energy jets traversing QGP medium can lose a significant fraction of their energy [1][2][3][4][5][6][7][8][9]. In the Baier-Dokshitzer-Mueller-Peigne-Schiff-Zakharov (BDMPS-Z) jet energy loss formalism [2][3][4][5], the signature of energy loss is characterized by the so-called jet transport coefficientq [10][11][12], which is defined as transverse momentum square transfer per unit length and reflects the density of QGP medium. In particular, early efforts in the quantitative extraction of the jet-transport coefficient from the JET collaboration were performed by calculating the nuclear modification factor (R AA ) for single hadron production using different energy-loss models, by comparing between RHIC and LHC experimental data on nucleus-nucleus (AA) collision and elementary hadron-hadron (pp) collisions [13].At the LHC, dijet transverse momentum imbalance has become an important gateway to quantitatively study the properties of quark-gluon plasma created in heavy-ion collisions. In particular, its difference between P bP b and pp collisions [14-16] reveals that high energy jets tend to lose a significant amount of energy when traversing QGP medium created in P bP b collisions [17][18][19][20][21][22][23][24]...

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We develop the first systematic theoretical approach to dijet asymmetries in hadron-hadron collisions based on the perturbative QCD (pQCD) expansion and the Sudakov resummation formalism. We find that the pQCD calculation at next-to-leading order is indispensable to describe the experimental data, while the Sudakov resummation formalism is vital near the end points where the pQCD expansion fails to converge due to the appearance of large Sudakov logarithms. Utilizing our resummation improved pQCD approach, we obtain good agreement with the most up-to-date fully corrected ATLAS data on dijet asymmetry in pp collisions. Combining with the BDMPS jet energy loss formalism, we extract the value of jet transport coefficientq0 ∼ 2-6 GeV 2 /fm for the quark-gluon-plasma created in P bP b collisions at 2.76A TeV. This work paves the way for a more complete and deeper understanding of the properties of strongly-coupled QCD medium via the studies of dijet asymmetries in relativistic heavy-ion collisions.

In this work, the efficient electron loss process was observed for the transmission of 10-to 18-keV Cu − and Cl − ions through Al 2 O 3 nanocapillaries. The fractions of the scattered particles were simultaneously measured using a position-sensitive microchannel plate detector. The neutrals were guided through the capillary via multiple grazing scattering. In particular, the scattered Cl − ions were observed in the transmission, whereas no Cu − ion was formed. In contrast to highly charged ions, these results support strongly the fact that the scattering events dominate the transport of negative ions through the nanocapillaries and that there is no direct evidence for the formation of negative charge patches inside the capillaries which are able to repulse and guide negative ions efficiently.