Search results for "Collision"

Search for new phenomena in final states with an energetic jet and large missing transverse momentum inppcollisions ats=13  TeVusing the ATLAS detect…

2016

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses proton-proton collision data corresponding to an inte ...

Neutron-skin effect and centrality dependence of high-pT observables in nuclear collisions

2016

We report on our studies of the neutron-skin effects in high-pT observables at the LHC. We study the impact of the neutron-skin effect on the centrality dependence of inclusive direct photon, highpT hadron and W± production in nuclear collisions at the LHC. The neutron-skin effect refers to the observation that in spherical heavy nuclei, the tail of the neutron distribution extends farther than the distribution of protons, which can affect observables sensitive to electroweak phenomena in very peripheral collisions. We quantify this effect for direct photons, charged hadrons and W bosons as a function of the collision centrality. In the case of direct photons we find that it will be difficu…

Search for new phenomena in dijet events using 37  fb−1 of pp collision data collected at s=13  TeV with the ATLAS detector

2017

Dijet events are studied in the proton-proton collision dataset recorded at root s = 13 TeV with the ATLAS detector at the Large Hadron Collider in 2015 and 2016, corresponding to integrated lumino ...

Search for Dark Matter Candidates and Large Extra Dimensions in Events with a Photon and Missing Transverse Momentum inppCollision Data ats=7  TeVwit…

2013

Search for the Standard Model Higgs Boson in the Diphoton Decay Channel with4.9  fb−1ofppCollision Data ats=7  TeVwith ATLAS

2012

A search for the standard model Higgs boson is performed in the diphoton decay channel. The data used correspond to an integrated luminosity of 4.9  fb-1 collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of √s=7  TeV. In the diphoton mass range 110–150 GeV, the largest excess with respect to the background-only hypothesis is observed at 126.5 GeV, with a local significance of 2.8 standard deviations. Taking the look-elsewhere effect into account in the range 110–150 GeV, this significance becomes 1.5 standard deviations. The standard model Higgs boson is excluded at 95% confidence level in the mass ranges of 113–115 GeV and…

Where Do Diffractive Nucleons Go?

1974

Nucleon and pion-nucleon distributions from the diffractive component in pp collisions are analysed. Diffractive events are assumed to come from a mechanism pp → N*p, in which a proton is diffractively excited to a nova N*. The decay properties of N* are determined by assuming that a Pomeron-proton collision behaves as a proton-proton collision. Correlations within the diffractive component are computed and seen to be numerically small. Even interference with the pionization component does not reproduce the observed pattern of pion (in the plateau)-proton (in the fragmentation region) correlations. This may imply the existence of long-range correlations within the pionization component.

Production ofWbosons in proton-nucleus collisions

1979

It is shown that nuclear effects can cause an enhancement in the cross section for production of $W$ bosons in a proton-nucleus collision. The cross section near threshold is a few orders of magnitude higher than expected from a linear dependence on the atomic number. Encouraging implications for experiments with fixed targets at laboratory energies of ${10}^{3}$ GeV and higher are discussed. We also discuss lepton-pair production off nuclei.

Charge separation relative to the reaction plane in Pb-Pb collisions atsNN=2.76  TeV

2013

Measurements of charge-dependent azimuthal correlations with the ALICE detector at the LHC are reported for Pb-Pb collisions at root s(NN) = 2.76 TeV. Two- and three-particle charge-dependent azimuthal correlations in the pseudorapidity range vertical bar eta vertical bar < 0.8 are presented as a function of the collision centrality, particle separation in pseudorapidity, and transverse momentum. A clear signal compatible with a charge-dependent separation relative to the reaction plane is observed, which shows little or no collision energy dependence when compared to measurements at RHIC energies. This provides a new insight for understanding the nature of the charge-dependent azimuthal co…

Probing the Quantum Interference between Singly and Doubly Resonant Top-Quark Production in pp Collisions at s=13  TeV with the ATLAS Detector

2018

This Letter presents a normalized differential cross-section measurement in a fiducial phase-space region where interference effects between top-quark pair production and associated production of a single top quark with a W boson and a b-quark are significant. Events with exactly two leptons (ee, μμ, or eμ) and two b-tagged jets that satisfy a multiparticle invariant mass requirement are selected from 36.1  fb^{-1} of proton-proton collision data taken at sqrt[s]=13  TeV with the ATLAS detector at the LHC in 2015 and 2016. The results are compared with predictions from simulations using various strategies for the interference. The standard prescriptions for interference modeling are signifi…

Single inclusive hadron production in pA collisions at NLO

2016

We study single inclusive forward hadron production in high energy proton-nucleus collisions at next-to-leading order in the Color Glass Condensate framework. Recent studies have shown that the next-to-leading order corrections to this process are large and negative at large transverse momentum, leading to negative cross sections. We propose to overcome this difficulty by introducing an explicit rapidity factorization scale when subtracting the rapidity divergence into the evolution of the target.