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$B-L$ model in light of the CDF II result

Sanjoy Mandal, Hemant Prajapati, Rahul Srivastava

TL;DR

The paper investigates whether a gauged $U(1)_{B-L}$ extension can explain the CDF II $W$-mass anomaly via shifts in the $Z$-boson sector and oblique parameters $S$, $T$, and $U$. It analyzes both kinetic-mixing and two $B-L$ realizations (vector without mass mixing and chiral with mass mixing), showing that kinetic mixing alone cannot resolve the anomaly within current collider bounds, while the chiral model can realize regions of parameter space compatible with $S$, $T$, $U$ and dark matter constraints. The work computes DM relic abundance and direct-detection prospects for the scalar DM $chi_d$, finding viable high-mass regions when accompanied by the appropriate oblique parameters, albeit under stringent collider and direct-detection limits. It also juxtaposes recent CMS and ATLAS $W$-mass measurements, highlighting that CMS constraints broaden the allowed space but the CDF II result remains in tension with others, implying no common region that satisfies all current data. Overall, the study demonstrates that a chiral $U(1)_{B-L}$ model can reconcile the $W$-mass anomaly with DM phenomenology, but ongoing experimental discrepancies must be resolved to confirm such scenarios.

Abstract

Recent CDF II collaboration's result on $W$ mass measurements contradict Standard Model prediction, requiring new physics to explain this anomaly. Such new physics may manifest through tree-level or loop-level corrections to the mass of the $W$ boson. In this work, we investigate the possibility that the CDF-II result is indicative of new physics not directly changing the $W$ boson mass but rather the $Z$ boson mass. Since the $Z$ boson mass goes as an input into the Standard Model prediction for $W$ boson mass, this change in $Z$ mass ultimately leads to the discrepancy between the CDF-II measurement and the Standard Model expectation. We demonstrate this idea through one of the simplest and most studied $U(1)$ gauge extensions of the Standard Model, namely the gauged $U(1)_{B-L}$ extension. We demonstrate that $B-L$ extended models can explain the revised best-fit values for $S$, $T$, and $U$ following the CDF II results. We studied the parameter space of models with and without mixing between neutral gauge bosons. We also reviewed the dark matter constraints and demonstrated that there is parameter space that is compatible with the current $W$ boson mass, relic abundance, and direct detection experiments.

$B-L$ model in light of the CDF II result

TL;DR

The paper investigates whether a gauged extension can explain the CDF II -mass anomaly via shifts in the -boson sector and oblique parameters , , and . It analyzes both kinetic-mixing and two realizations (vector without mass mixing and chiral with mass mixing), showing that kinetic mixing alone cannot resolve the anomaly within current collider bounds, while the chiral model can realize regions of parameter space compatible with , , and dark matter constraints. The work computes DM relic abundance and direct-detection prospects for the scalar DM , finding viable high-mass regions when accompanied by the appropriate oblique parameters, albeit under stringent collider and direct-detection limits. It also juxtaposes recent CMS and ATLAS -mass measurements, highlighting that CMS constraints broaden the allowed space but the CDF II result remains in tension with others, implying no common region that satisfies all current data. Overall, the study demonstrates that a chiral model can reconcile the -mass anomaly with DM phenomenology, but ongoing experimental discrepancies must be resolved to confirm such scenarios.

Abstract

Recent CDF II collaboration's result on mass measurements contradict Standard Model prediction, requiring new physics to explain this anomaly. Such new physics may manifest through tree-level or loop-level corrections to the mass of the boson. In this work, we investigate the possibility that the CDF-II result is indicative of new physics not directly changing the boson mass but rather the boson mass. Since the boson mass goes as an input into the Standard Model prediction for boson mass, this change in mass ultimately leads to the discrepancy between the CDF-II measurement and the Standard Model expectation. We demonstrate this idea through one of the simplest and most studied gauge extensions of the Standard Model, namely the gauged extension. We demonstrate that extended models can explain the revised best-fit values for , , and following the CDF II results. We studied the parameter space of models with and without mixing between neutral gauge bosons. We also reviewed the dark matter constraints and demonstrated that there is parameter space that is compatible with the current boson mass, relic abundance, and direct detection experiments.
Paper Structure (11 sections, 71 equations, 16 figures, 3 tables)

This paper contains 11 sections, 71 equations, 16 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Kinetic-Mixing and $W$ mass
  3. Minimal and chiral $B-L$ model
  4. Vector $B-L$ Model
  5. Chiral $B-L$ Model
  6. $W$ mass and the $S$, $T$, $U$ Parameters
  7. New Physics Contribution To $S$, $T$, $U$
  8. Dark Matter Constraints
  9. Dark Matter Constraints in View of Recent CMS and ATLAS Results
  10. Conclusion
  11. Annihilation channels for scalar DM $\chi_d$

Figures (16)

  • Figure 1: $Z$ mass versus kinetic mixing $\kappa$. The coloured lines in each panel correspond to different $g_{x}$ and $M_{Z'}$ values while keeping the ratio $\frac{M_{Z'}}{g_x}$ constant.
  • Figure 2: Constraint on $g_x$ as a function of $M_{Z'}$. The shaded regions are ruled out from LEP-II Carena:2004xsCacciapaglia:2006pk, ATLAS and CMS dilepton searches ATLAS:2019erbCMS:2021ctt.
  • Figure 3: Neutrino mass generation in $B-L$ model through type-I seesaw mechanism.
  • Figure 4: Neutrino mass generation in Chiral $B-L$ model through Dirac type II seesaw
  • Figure 5: $Z$ and $Z'$ boson mixing at loop level in the vector B-L model.
  • ...and 11 more figures