Wormholes in f(Q,T) gravity with different matter Lagrangian density
Pith reviewed 2026-05-21 04:05 UTC · model grok-4.3
The pith
Different matter Lagrangian densities permit non-exotic asymptotically flat wormholes in f(Q,T) gravity.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The central claim is that non-exotic asymptotically flat wormhole solutions exist for all considered matter Lagrangian densities. Different Lm choices enable the same shape function to be supported by varied fluid configurations, or vice versa, identical fluids to yield different geometries. The energy conditions and physical characteristics of these solutions are shown to be distinct and critically dependent on the selected Lm.
What carries the argument
The modified field equations obtained by varying the f(Q,T) action with respect to the metric for each choice of matter Lagrangian Lm; these equations share a common structure but differ through coefficients A_i that depend on alpha and beta.
If this is right
- Solutions with linear and asymptotically linear equations of state exist for every Lm and remain asymptotically flat.
- The same shape function can be maintained with different fluid configurations by switching Lm.
- Identical fluids produce different wormhole geometries when Lm is changed.
- Energy density and pressure profiles differ markedly for each choice of Lm.
- All solutions satisfy the null energy condition without requiring exotic matter.
Where Pith is reading between the lines
- The Lm choice effectively acts as an extra tunable parameter that decouples the geometry from the fluid in modified-gravity wormhole models.
- This flexibility suggests that observational searches for wormhole signatures could test specific Lm assumptions rather than the gravity theory alone.
- Extending the same approach to other f(Q,T) forms could show whether the non-exotic property persists beyond the linear case examined here.
Load-bearing premise
The field equations obtained after varying the action with respect to the metric remain valid and solvable when the matter Lagrangian is switched from -P to -T or to rho while keeping the same linear or asymptotically linear equation of state.
What would settle it
A derivation showing that, for one of the three Lm choices, the metric functions fail to approach flat spacetime at large r while satisfying the assumed equation of state.
Figures
read the original abstract
This study explores asymptotically flat wormhole solutions in $f(Q,T)=\alpha Q+ \beta T$ gravity, expanding upon our prior work (arXiv:2602.00527v1) with matter Lagrangian density, $L_m=-P$ . Here, we examine the implications of employing $Lm=-T$ and $L_m=\rho$. The field equations, derived via action variation, share a common general structure but are fundamentally dictated by the parameters $\alpha$ and $\beta$ through the coefficients $A_i$. Solutions with linear and asymptotically linear equation of state are explored. We conclude that non-exotic asymptotically flat wormhole solutions exist for all considered matter Lagrangian densities. A key outcome is the demonstration that different $L_m$ choices enable the same shape function to be supported by varied fluid configurations, or vice versa, identical fluids to yield different geometries. The energy conditions and physical characteristics of these solutions are shown to be distinct and critically dependent on the selected $L_m$.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript explores asymptotically flat wormhole solutions in f(Q,T) = αQ + βT gravity for three choices of matter Lagrangian density (Lm = −P, Lm = −T, and Lm = ρ). Field equations are derived for linear and asymptotically linear equations of state; explicit solutions are presented and shown to satisfy the null, weak, and strong energy conditions for suitable parameter choices. The central claim is that non-exotic solutions exist for all three Lm choices, with different Lm permitting the same shape function to be supported by varied fluid configurations (or vice versa).
Significance. If the internal consistency of the Lm = −T solutions is confirmed, the work would usefully illustrate the sensitivity of wormhole geometries in f(Q,T) gravity to the choice of matter Lagrangian, extending the authors’ prior Lm = −P results. The demonstration that identical shape functions can be realized by different fluids (and conversely) is a concrete, falsifiable outcome. The absence of machine-checked derivations or fully parameter-free predictions limits the strength of the result relative to other modified-gravity wormhole papers.
major comments (2)
- [§3] §3 (Field equations for Lm = −T): The variation of the action with respect to the metric produces extra terms proportional to δT/δgμν that depend explicitly on the perfect-fluid decomposition T = ρ − 3p. The manuscript states that the resulting equations share a common structure whose coefficients Ai are fixed by α and β, yet provides no explicit verification that the solved ρ(r) and p(r) regenerate a trace T identical to the one assumed in the variation. This self-consistency check is load-bearing for the claim that non-exotic solutions exist for Lm = −T.
- [§4.2] §4.2 (Linear EOS solutions): For the reported choices of α and β that yield asymptotically flat wormholes, the paper does not demonstrate that the same numerical values of α and β simultaneously satisfy the field equations for all three Lm choices without additional tuning. If the parameter sets differ across Lm, the statement that “different Lm choices enable the same shape function” requires a direct side-by-side comparison of the metric functions and fluid profiles.
minor comments (2)
- [§2] The notation for the shape function b(r) and the redshift function Φ(r) is introduced without an explicit statement of the asymptotic flatness conditions imposed at spatial infinity.
- [Table 1] Table 1 (energy-condition summary) lists satisfaction of NEC, WEC, and SEC but does not indicate the radial intervals over which each condition holds; a plot or explicit interval would improve clarity.
Simulated Author's Rebuttal
We thank the referee for the careful and constructive review of our manuscript. We respond to each major comment below and indicate the revisions made to address them.
read point-by-point responses
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Referee: [§3] §3 (Field equations for Lm = −T): The variation of the action with respect to the metric produces extra terms proportional to δT/δgμν that depend explicitly on the perfect-fluid decomposition T = ρ − 3p. The manuscript states that the resulting equations share a common structure whose coefficients Ai are fixed by α and β, yet provides no explicit verification that the solved ρ(r) and p(r) regenerate a trace T identical to the one assumed in the variation. This self-consistency check is load-bearing for the claim that non-exotic solutions exist for Lm = −T.
Authors: We agree that an explicit self-consistency verification strengthens the presentation. In the revised manuscript we have added a direct substitution in §3: the solved ρ(r) and p(r) are inserted back into T = ρ − 3p and shown to recover the trace assumed during the variation for the reported parameter choices. This confirms the internal consistency of the Lm = −T solutions. revision: yes
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Referee: [§4.2] §4.2 (Linear EOS solutions): For the reported choices of α and β that yield asymptotically flat wormholes, the paper does not demonstrate that the same numerical values of α and β simultaneously satisfy the field equations for all three Lm choices without additional tuning. If the parameter sets differ across Lm, the statement that “different Lm choices enable the same shape function” requires a direct side-by-side comparison of the metric functions and fluid profiles.
Authors: The field equations take different forms for each Lm, so α and β must be chosen separately to satisfy the equations and asymptotic flatness. To address the request for explicit comparison, we have inserted a new table in the revised §4.2 that lists the shape function, redshift function, and fluid profiles (ρ, p) for an identical shape function realized under all three Lm choices, each with its corresponding α and β. This makes the dependence on Lm choice transparent while preserving the central claim. revision: yes
Circularity Check
No significant circularity; derivations are independent of inputs
full rationale
The paper derives modified field equations for f(Q,T) gravity under three choices of Lm, assumes standard wormhole shape functions and linear/asymptotically linear EOS, solves for ρ(r) and p(r) by fixing α and β, and verifies energy conditions. The self-citation to prior work on Lm=-P provides context for the extension but is not invoked as a uniqueness theorem or to close any derivation step. No equation reduces to a fitted parameter renamed as prediction, no ansatz is smuggled via citation, and the central existence claim rests on explicit solution of the differential system rather than tautological redefinition. The approach is self-contained against the assumed metric and EOS inputs.
Axiom & Free-Parameter Ledger
free parameters (2)
- α
- β
axioms (2)
- domain assumption Variation of the action with the chosen f(Q,T) yields field equations whose structure is controlled by coefficients A_i that depend on α and β.
- domain assumption The matter sector can be described by a perfect fluid with linear or asymptotically linear equation of state for each choice of Lm.
Lean theorems connected to this paper
-
IndisputableMonolith/Foundation/RealityFromDistinction.leanreality_from_one_distinction unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
We employ the linear representation f(Q,T)=αQ+βT … Solutions with linear and asymptotically linear equation of state are explored.
-
IndisputableMonolith/Cost/FunctionalEquation.leanwashburn_uniqueness_aczel unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
The field equations … share a common general structure but are fundamentally dictated by the parameters α and β through the coefficients Ai.
What do these tags mean?
- matches
- The paper's claim is directly supported by a theorem in the formal canon.
- supports
- The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
- extends
- The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
- uses
- The paper appears to rely on the theorem as machinery.
- contradicts
- The paper's claim conflicts with a theorem or certificate in the canon.
- unclear
- Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.
Reference graph
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Solutions with Linear EoS The linear EoS is pivotal in the study of worm- hole physics, since it describes the material properties of the exotic matter that is necessary for sustaining a traversable geometry. Taking into account pr(r) = ωρ (r), (42) and applying Eqs.(35) and (36) it can be obtained b(r) = rn1(ω,β ), (43) n1(ω,β ) = 1 + 3β β − ω (1 + 2β )....
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[2]
Asymptotically linear EoS Although the linear EoS is the most common form typically considered for these equations, a broader range of solutions can be derived within the context of worm- hole theory by employing a variable EoS. This strategy is predicated on the idea that asymptotically linear EoS should be considered a more comprehensive type of EoS rat...
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[3]
(38) and (39) in EoS (42), we will have b(r) = rn2(ω,β ), (75) in which n2(ω,β ) = 2β − 1 ω + 2β
Solutions with Linear EoS For a linear EoS by using Eqs. (38) and (39) in EoS (42), we will have b(r) = rn2(ω,β ), (75) in which n2(ω,β ) = 2β − 1 ω + 2β. (76) It is obvious that it fulfills all the conditions for worm- hole theory provided that n2 < 1 holds. To guarantee a positive energy density, it is essential that the following condition must be satis...
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[4]
Through the examination of various forms of g(r), alternative solutions for b(r) can be real- ized
Asymptotically linear EoS Now, we will investigate a variable EoS as indicated in Eq.(49), and reiterate the same strategy as presented in section III A 2. Through the examination of various forms of g(r), alternative solutions for b(r) can be real- ized. Considering that the energy density must be posi- tive, the coefficient of equation (38) is obligated t...
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We will initiate with the given shape function in Eq
(82) Currently, we are looking into two special shape func- tions and addressing their physical properties within the context of f (Q,T ) theory. We will initiate with the given shape function in Eq. (57). By choosing α = −β = − 8D = − 8ω = − 2, results in b(r) = ( 2 r + 1 ) 4 , in this case the condition β < 1 2 is not valid. It is appar- ent that the en...
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discussion (0)
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