ATLAS Collaboration(Aad, G. et al), Alvarez Piqueras, D., Aparisi Pozo, J. A., Bailey, A. J., Cabrera Urban, S., Castillo, F. L., et al. (2020). Measurement of differential cross sections for single diffractive dissociation in root s=8 TeV pp collisions using the ATLAS ALFA spectrometer. J. High Energy Phys., 02(2), 42–37pp.
Abstract: A dedicated sample of Large Hadron Collider proton-proton collision data at centre-of-mass energy s= 8 TeV is used to study inclusive single diffractive dissociation, pp -> X p. The intact final-state proton is reconstructed in the ATLAS ALFA forward spectrometer, while charged particles from the dissociated system X are measured in the central detector components. The fiducial range of the measurement is -4.0 < log(10)xi < -1.6 and 0.016 < |t| < 0.43 GeV2, where xi is the proton fractional energy loss and t is the squared four-momentum transfer. The total cross section integrated across the fiducial range is 1.59 +/- 0.13 mb. Cross sections are also measured differentially as functions of xi, t, and increment eta, a variable that characterises the rapidity gap separating the proton and the system X . The data are consistent with an exponential t dependence, d sigma/dt proportional to e(Bt) with slope parameter B = 7.65 +/- 0.34 GeV-2. Interpreted in the framework of triple Regge phenomenology, the xi dependence leads to a pomeron intercept of alpha(0) = 1.07 +/- 0.09.
|
Feng, J. L. et al, Garcia Soto, A., & Hirsch, M. (2023). The Forward Physics Facility at the High-Luminosity LHC. J. Phys. G, 50(3), 030501–410pp.
Abstract: High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe standard model (SM) processes and search for physics beyond the standard model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential.
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2017). Study of b(b)over-bar correlations in high energy proton-proton collisions. J. High Energy Phys., 11(11), 030–28pp.
Abstract: Kinematic correlations for pairs of beauty hadrons, produced in high energy proton-proton collisions, are studied. The data sample used was collected with the LHCb experiment at centre-of-mass energies of 7 and 8 TeV and corresponds to an integrated luminosity of 3 fb(-1). The measurement is performed using inclusive b -> J/psi X decays in the rapidity range 2 < y(J/psi) < 4.5. The observed correlations are in good agreement with theoretical predictions.
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Measurement of D-s(+/-) production asymmetry in pp collisions at root s=7 and 8 TeV. J. High Energy Phys., 08(8), 008–21pp.
Abstract: The inclusive D-s(+/-) production asymmetry is measured in pp collisions collected by the LHCb experiment at centre-of-mass energies of root s = 7 and 8 TeV. Promptly produced D-s(+/-) mesons are used, which decay as D-s(+/-) -> phi pi(+/-), with phi -> K+ K-. The measurement is performed in bins of transverse momentum, pT, and rapidity, y, covering the range 2.5 < pT < 25 : 0 GeV/c and 2.0 < y < 4.5. No kinematic dependence is observed. Evidence of nonzero D-s(+/-) production asymmetry is found with a significance of 3.3 standard deviations.
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Measurement of Z -> tau(+)tau(-) production in proton-proton collisions at root s=8 TeV. J. High Energy Phys., 09(9), 159–19pp.
Abstract: A measurement of Z -> tau(+)tau(-) production cross-section is presented using data, corresponding to an integrated luminosity of 2 fb(-1), from pp collisions at root s = 8 TeV collected by the LHCb experiment. The tau(+)tau(-)candidates are reconstructed in final states with the first tau lepton decaying leptonically, and the second decaying either leptonically or to one or three charged hadrons. The production cross-section is measured for Z bosons with invariant mass between 60 and 120 GeV/c(2), which decay to tau leptons with transverse momenta greater than 20 GeV/c and pseudorapidities between 2.0 and 4.5. The cross-section is determined to be sigma(pp -> Z -> tau+tau-)= 95.8 +/- 2.1 +/- 4.6 +/- 0.2 +/- 1.1 pb, where the first uncertainty is statistical, the second is systematic, the third is due to the LHC beam energy uncertainty, and the fourth to the integrated luminosity uncertainty. This result is compatible with NNLO Standard model predictions. The ratio of the cross-sections for Z -> tau(+)tau(- )to Z -> mu(+)mu(-) (Z -> e(+)e(-)), determined to be 1.01 +/- 0.05 (1.02 +/- 0.06), is consistent with the lepton-universality hypothesis in Z decays.
|