Exclusive Higgs Boson Production with bottom quarks at Hadron Colliders

TL;DR

The paper computes the next-to-leading order QCD cross sections for exclusive Higgs production with a bottom quark pair in hadron collisions, covering both the SM and MSSM. By formulating the cross section as a convolution of PDFs with partonic ${\hat\sigma}_{NLO}$ and examining OS versus MSbar renormalization for the bottom Yukawa coupling, it assesses scale and scheme uncertainties. The results show substantial improvement in perturbative stability at NLO, while highlighting a notable renormalization-scheme dependence. In MSSM scenarios with large tan_beta, the b bbar h production rate can be enhanced by up to three orders of magnitude, underscoring its potential as a discovery channel at the Tevatron and LHC.

Abstract

We present the next-to-leading order QCD corrected rate for the production of a scalar Higgs boson with a pair of high p_T bottom and anti-bottom quarks at the Tevatron and at the Large Hadron Collider. Results are given for both the Standard Model and the Minimal Supersymmetric Standard Model. The exclusive b-bbar-h production rate is small in the Standard Model, but it can be greatly enhanced in the Minimal Supersymmetric Standard Model for large tan(beta), making b-bbar-h an important discovery mode. We find that the next-to-leading order QCD results are much less sensitive to the renormalization and factorization scales than the lowest order results, but have a significant dependence on the choice of the renormalization scheme for the bottom quark Yukawa coupling.

Figures (9)

• Figure 1: Sample of diagrams corresponding to ${\cal O}(\alpha_s)$ virtual corrections where the Higgs boson couples to an internal fermion loop and not to the external $b\bar{b}$ pair. The circled cross denotes all possible insertion of the final state Higgs boson leg, each insertion corresponding to a different diagram.
• Figure 2: $\sigma_{ NLO}$ and $\sigma_{ LO}$ for $p\bar{p}\to b\bar{b}h$ at $\sqrt{s}\!=\!2$ TeV (top) and for $pp\to b\bar{b}h$ at $\sqrt{s}\!=\!14$ TeV (bottom) as a function of the renormalization/factorization scale $\mu$, for $M_h=120$ GeV. The curves labeled $\sigma_{ LO,OS}$ and $\sigma_{ NLO,OS}$ use the $OS$ renormalization scheme for the bottom quark Yukawa coupling, while the curves labeled $\sigma_{ LO,MS}$ and $\sigma_{ NLO,MS}$ use the $\overline{MS}$ scheme.
• Figure 3: The absolute value of the percentage difference $\Delta(\%)\!=\!(\sigma_{ NLO,OS}-\sigma_{ NLO,\overline{MS}})/(\sigma_{ NLO,OS}+\sigma_{ NLO,\overline{MS}})$ for $p\bar{p}\to b\bar{b}h$ at $\sqrt{s}=2$ TeV (top) and for $pp\to b\bar{b}h$ at $\sqrt{s}=14$ TeV (bottom) as a function of the renormalization/factorization scale $\mu$, for $M_h=120$ GeV. The $OS$ and $\overline{MS}$ labels refer to the renormalization scheme chosen for the bottom quark Yukawa coupling. The curves labeled as $\Delta(m_b(\mu)_{1l})$ and $\Delta(m_b(\mu)_{2l})$ use the $\overline{MS}$ bottom quark Yukawa coupling with the 1-loop running mass of Eq. (\ref{['eq:mb_msbar_rg_1l']}) and the 2-loop running mass of Eq. (\ref{['eq:mb_msbar_rg_2l']}), respectively.
• Figure 4: $\sigma_{ NLO,MS}$ and $\sigma_{ LO,MS}$ for $p\bar{p}\to b\bar{b}h$ at $\sqrt{s}\!=\!2$ TeV (top) and for $pp\to b\bar{b}h$ at $\sqrt{s}\!=\!14$ TeV (bottom) as a function of the cut imposed on the final state bottom and anti-bottom transverse momentum ($p_T^b$), for $M_h\!=\!120$ GeV and $\mu\!=\!\mu_0\!=\!m_b+M_h/2$.
• Figure 5: Transverse momentum distributions at LO and NLO of the bottom or anti-bottom quark with the largest $p_T$. Shown are the $p_T^{max}$ distributions for $p\bar{p}\to b\bar{b}h$ production at $\sqrt{s}\!=\!2$ TeV (left) and $pp\to b\bar{b}h$ production at $\sqrt{s}\!=\!14$ TeV (right) in the SM and using the OS scheme for the bottom quark Yukawa coupling. At the Tevatron we choose $\mu\!=\!2 m_b+M_h$, while at the LHC we choose $\mu\!=\!2 (2 m_b+M_h)$.