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Next-to-leading order QCD corrections to pp --> b b_bar b b_bar + X at the LHC: the quark induced case

T. Binoth, N. Greiner, A. Guffanti, J. -Ph. Guillet, T. Reiter, J. Reuter

TL;DR

The paper tackles the need for precise NLO QCD predictions for the quark-induced pp -> bb̄bb̄ + X process, a key background in Higgs and BSM searches. It employs a GOLEM-based approach for the virtual one-loop corrections and Catani-Seymour dipole subtraction for real emissions, with two independent calculation paths and external event generators to ensure reliability. The results show that NLO corrections significantly reduce renormalization-scale uncertainties and yield more stable predictions for four-b-jet observables, including the invariant bb̄ distribution. This work establishes a robust framework for complex multi-jet final states at the LHC and lays the groundwork for a complete NLO treatment including the gluon-induced channel.

Abstract

The production of two b-quark pairs is a prominent background for Higgs and New Physics searches in various extensions of the Standard Model. We present here the next-to-leading order QCD corrections to the quark induced subprocess using the GOLEM approach for the virtual corrections. We show that our result considerably improves the prediction and conclude that the inclusion of next-to-leading order effects is indispensable for reliable studies of four b-quark observables in hadronic collisions.

Next-to-leading order QCD corrections to pp --> b b_bar b b_bar + X at the LHC: the quark induced case

TL;DR

The paper tackles the need for precise NLO QCD predictions for the quark-induced pp -> bb̄bb̄ + X process, a key background in Higgs and BSM searches. It employs a GOLEM-based approach for the virtual one-loop corrections and Catani-Seymour dipole subtraction for real emissions, with two independent calculation paths and external event generators to ensure reliability. The results show that NLO corrections significantly reduce renormalization-scale uncertainties and yield more stable predictions for four-b-jet observables, including the invariant bb̄ distribution. This work establishes a robust framework for complex multi-jet final states at the LHC and lays the groundwork for a complete NLO treatment including the gluon-induced channel.

Abstract

The production of two b-quark pairs is a prominent background for Higgs and New Physics searches in various extensions of the Standard Model. We present here the next-to-leading order QCD corrections to the quark induced subprocess using the GOLEM approach for the virtual corrections. We show that our result considerably improves the prediction and conclude that the inclusion of next-to-leading order effects is indispensable for reliable studies of four b-quark observables in hadronic collisions.

Paper Structure

This paper contains 6 sections, 4 figures, 1 table.

Table of Contents

  1. Introduction
  2. Calculation
  3. Virtual corrections
  4. Real emission corrections
  5. Results
  6. Conclusion

Figures (4)

  • Figure 1: Six-quark topologies which contribute to the leading order amplitude $q\bar{q}\to b\bar{b}b\bar{b}$.
  • Figure 2: Pentagon and hexagon one-loop topologies which contribute to the virtual corrections to order ${\cal O}(\alpha_s^3)$.
  • Figure 3: The dependence of the LO and NLO prediction of $pp(q\bar{q})\to b\bar{b}b\bar{b} + X$ at the LHC ($\sqrt{s}=14$ TeV) on the renormalisation scale $\mu_R=x \mu_0$ with $\mu_0=\sqrt{\sum_j p_T^2(b_j)}$. The factorisation scale is fixed to $\mu_F=100$ GeV.
  • Figure 4: Invariant mass ($m_{bb}$) distribution of the two leading $b$-quarks (see text). The LO/NLO bands are obtained by varying the renormalisation scale $\mu_R$ between $\mu_0/4$ and $2\mu_0$ with $\mu_0 = \sqrt{\sum_j p_T^2(b_j)}$. The full (dashed) line shows the NLO (LO) prediction for the value $\mu_R=\mu_0/2$.