Searches for new physics in events with a photon andb-quark jet at CDF

Abstract

T. AFFOLDER et al.PHYSICAL REVIEW D 65 052006 052006-2We have searched for evidence of physics beyond the standard model in events that include an energetic photon and an energetic b-quark jet, produced in 85 pb Ϫ1 of p p collisions at 1.8 TeV at the Tevatron Collider at Fermilab. This signature, containing at least one gauge boson and a third-generation quark, could arise in the production and decay of a pair of new particles, such as those predicted by supersymmetry, leading to a production rate exceeding standard model predictions. We also search these events for anomalous production of missing transverse energy, additional jets and leptons (e, and ), and additional b quarks. We find no evidence for any anomalous production of ␥b or ␥bϩX events. We present limits on two supersymmetric models: a model where the photon is produced in the decay 2 0 →␥ 1 0 , and a model where the photon is produced in the neutralino decay into the gravitino LSP, 1 0 →␥G . We also present our limits in a modelindependent form and test methods of applying model-independent limits.

PYTHIA and the preoccupied proton

“…In particular, the rise of N ⊥ with p t (jet) to a saturation value (pedestal) should reflect increase of the MPI rate with increasing p-p centrality in response to the trigger condition [1,11]. Figure 2 (first) shows CDF UE data for N ⊥ vs p t (jet) (points) in a conventional plot format [12]. The curves are from PYTHIA.…”

Comparing the PYTHIA Monte Carlo to a two-component (soft + hard) model of hadron production in high-energy p–p collisions

“…The UE for high-energy p-p collisions is by definition complementary to an eventwise-triggered dijet or pQCD leading-order process [51]. Access to the UE is expected via the transverse (azimuth) region or TR component of the single-particle charge density relative to the trigger (or of 1D azimuth correlations as in Fig.…”

“…The UE study reported in Ref. [51] considers chargejet evolution and properties of the UE within an acceptance p t > 0.5 GeV/c and |η| < 1. Trigger (leading) jets (jet in each event with greatest P T 1 = i∈jet p ti ) fall in the range P T 1 ∈ [0.5, 50] GeV/c.…”

Explicit jet veto as a tool to purify the underlying event in the Drell–Yan process using CMS Open Data

“…So, the practical understanding of UE is limited to the phenomenological models. The CDF [2][3][4][5] experiment at Tevatron and the ATLAS [6][7][8][9][10][11], ALICE [12] and CMS [13][14][15][16][17] experiments at LHC have carried out several measurements of parameters and observables sensitive to UE at their available center-of-mass energies ( √ s). Due to easy identification of Z-boson production, the experiments usually study the UE activities in the events containing the Drell-Yan(DY) process.…”