Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Dijets with large rapidity separation at the next-to-leading BFKL for search of large extra dimension gravity at colliders

Anatolii Iu. Egorov, Victor T. Kim, Viktor A. Murzin, Vadim A. Oreshkin

TL;DR

This work addresses probing gravity with large extra dimensions (ADD) in the trans-Planckian, eikonal regime using high-mass Mueller-Navelet dijets with large rapidity separation. The authors compare ADD-signal cross sections, computed in the eikonal framework, to SM QCD backgrounds modeled with DGLAP and, crucially, with next-to-leading logarithmic (NLL) BFKL evolution, which better describes large-rapidity data than LL or DGLAP alone. They perform detailed numerical studies for $\sqrt{s}=13$, 40, and 100 TeV, varying the number of extra dimensions $n_D$ and the gravity scale $M_D$, and applying realistic high-mass cuts $M_{jj} > M_{jj\min}$ and rapidity separations $\Delta y$, to project sensitivities at HL-LHC, FCC-hh, and CEPC-SppC. The results show that NLL BFKL background estimates are robust and that sensitivities on $M_D$ grow with collider energy (e.g., $M_D < 3$ TeV at 13 TeV, $<10$ TeV at 40 TeV, $<30$ TeV at 100 TeV), while cautioning that DGLAP-based backgrounds can significantly overestimate SM rates in this regime. The study highlights the complementary role of this kinematic channel in searches for extra dimensions, requiring high luminosity and fine-grained detectors to exploit large-rapidity, high-mass dijet events.

Abstract

Search for the gravity with large extra dimensions at collider energies is considered in the trans-Planckian eikonal regime, i. e., when $\sqrt{\hat{s}} \gg M_D \gg \sqrt{-\hat{t}}$. Here $\hat{s}$ and $\hat{t}$ are the Mandelstam variables of colliding parton-parton system and $M_D$ is the Planck mass scale in the space-time with compactified $n_D$ extra dimensions. A relevant observable for this regime may be the cross section of high-mass ($M_{jj}\sim\sqrt{\hat{s}} \gg M_D$) dijet production with large rapidity separation. Then the standard model (SM) background should be calculated within the next-to-leading logarithmic (NLL) approximation of Lipatov-Fadin-Kuraev-Balitsky (BFKL) formalism of quantum chromodynamics (QCD) suitable for $\sqrt{\hat{s}}\gg\sqrt{-\hat{t}}\ggΛ_\mathrm{QCD}$. In this work the signal of the large extra dimension gravity as well as the NLL BFKL QCD background are estimated for the high-luminosity Large Hadron Collider (HL-LHC) and future colliders such as FCCpp and CEPC-SppC.

Dijets with large rapidity separation at the next-to-leading BFKL for search of large extra dimension gravity at colliders

TL;DR

This work addresses probing gravity with large extra dimensions (ADD) in the trans-Planckian, eikonal regime using high-mass Mueller-Navelet dijets with large rapidity separation. The authors compare ADD-signal cross sections, computed in the eikonal framework, to SM QCD backgrounds modeled with DGLAP and, crucially, with next-to-leading logarithmic (NLL) BFKL evolution, which better describes large-rapidity data than LL or DGLAP alone. They perform detailed numerical studies for , 40, and 100 TeV, varying the number of extra dimensions and the gravity scale , and applying realistic high-mass cuts and rapidity separations , to project sensitivities at HL-LHC, FCC-hh, and CEPC-SppC. The results show that NLL BFKL background estimates are robust and that sensitivities on grow with collider energy (e.g., TeV at 13 TeV, TeV at 40 TeV, TeV at 100 TeV), while cautioning that DGLAP-based backgrounds can significantly overestimate SM rates in this regime. The study highlights the complementary role of this kinematic channel in searches for extra dimensions, requiring high luminosity and fine-grained detectors to exploit large-rapidity, high-mass dijet events.

Abstract

Search for the gravity with large extra dimensions at collider energies is considered in the trans-Planckian eikonal regime, i. e., when . Here and are the Mandelstam variables of colliding parton-parton system and is the Planck mass scale in the space-time with compactified extra dimensions. A relevant observable for this regime may be the cross section of high-mass () dijet production with large rapidity separation. Then the standard model (SM) background should be calculated within the next-to-leading logarithmic (NLL) approximation of Lipatov-Fadin-Kuraev-Balitsky (BFKL) formalism of quantum chromodynamics (QCD) suitable for . In this work the signal of the large extra dimension gravity as well as the NLL BFKL QCD background are estimated for the high-luminosity Large Hadron Collider (HL-LHC) and future colliders such as FCCpp and CEPC-SppC.

Paper Structure

This paper contains 7 sections, 6 equations, 4 figures.

Table of Contents

  1. INTRODUCTION
  2. Gravity in space-time with large compactified extra dimensions
  3. QCD background estimation
  4. Definition of observable
  5. Numerical calculations
  6. Results and discussion
  7. Summary

Figures (4)

  • Figure 1: Effective minimum transverse momentum, $p_{\perp\min}^{\mathrm{eff}}$, of jets forming an MN dijet after applying the $M_{jj}$ selection for the case $p_{\perp1}\neq p_{\perp2}$ (a); and for the case $p_{\perp1} = p_{\perp2}$ (b).
  • Figure 2: The MN dijet cross section with the imposed dijet mass selection $\hbox{$M_{jj}$}\xspace>\hbox{$M_{jj\mathrm{min}}$}\xspace$ in $pp$ collisions at $\hbox{$\sqrt{s}$}\xspace=13$ TeV. The ADD gravity signal is shown for various parameter choices, including the number of extra dimensions $n_D$, and the Plank scale $\hbox{$M_{D}$}\xspace$ in the presence of $n_D$ extra dimensions. The QCD background includes either contributions calculated with the LO+LL DGLAP or LL/NLL BFKL corrections. Panel (a) corresponds to $\hbox{$M_{jj\mathrm{min}}$}\xspace=6$ TeV, and panel (b) to $\hbox{$M_{jj\mathrm{min}}$}\xspace=9$ TeV.
  • Figure 3: The MN dijet cross section with the imposed dijet mass selection $\hbox{$M_{jj}$}\xspace>\hbox{$M_{jj\mathrm{min}}$}\xspace$ in $pp$ collisions at $\hbox{$\sqrt{s}$}\xspace=40$ TeV. The ADD gravity signal is shown for various parameter choices, including the number of extra dimensions $n_D$, and the Plank scale $\hbox{$M_{D}$}\xspace$ in the presence of $n_D$ extra dimensions. The QCD background includes either contributions calculated with the LO+LL DGLAP or LL/NLL BFKL corrections. Panel (a) corresponds to $\hbox{$M_{jj\mathrm{min}}$}\xspace=9$ TeV, and panel (b) to $\hbox{$M_{jj\mathrm{min}}$}\xspace=30$ TeV.
  • Figure 4: The MN dijet cross section with the imposed dijet mass selection $\hbox{$M_{jj}$}\xspace>\hbox{$M_{jj\mathrm{min}}$}\xspace$ in $pp$ collisions at $\hbox{$\sqrt{s}$}\xspace=100$ TeV. The ADD gravity signal is shown for various parameter choices, including the number of extra dimensions $n_D$, and the Plank scale $\hbox{$M_{D}$}\xspace$ in the presence of $n_D$ extra dimensions. The QCD background includes either contributions calculated with the LO+LL DGLAP or LL/NLL BFKL corrections. Panel (a) corresponds to $\hbox{$M_{jj\mathrm{min}}$}\xspace=30$ TeV, and panel (b) to $\hbox{$M_{jj\mathrm{min}}$}\xspace=70$ TeV.