What does this equation mean?

Because that sensitivity is unmeasured, the paper computes it instead, anchoring the calculation to the density-functional strain sensitivities already published for this material family and to a Grüneisen-type estimate relating the tilt to the same electron-lattice coupling that fixes graphene’s own strain response, and reports the result as a band spanning roughly a factor of six rather than a single number. That spread propagates directly into the temperature: sweeping the computed sensitivity across its conservative-to-optimistic range moves the analog Hawking temperature by roughly the same factor of six the sensitivity itself carries. The paper does not treat that spread as a flaw to explain away. It treats measuring $\partial$ W/$\partial$$\text{strain}$ directly, in an operando-strain photoemission sweep of exactly the kind Lanz and collaborators already built most of the apparatus for, as the device’s first and most important milestone — the single experiment that would collapse today’s sixfold uncertainty into a real number.