Questions --------- 1) L.26-29. What do you mean with "when the angular momentum is properly considered" ? We think you mean that the CP eigenvalue of Ds*K is opposite to DsK due to the relative angular momentum of the final state. We'd suggest a small rephrasing of L.26-29: "The Bs->Ds*K decays are particularly interesting because the formalism to determine gamma is the same as for the Bs->DsK decays, apart from the CP eigenvalue of the final state due to the relative orbital momentum of the Ds*K final state." 2) L.105. You say "hadrons misidentified as photons". Is this dominated by pi0's? If so, perhaps you could consider replacing 'hadrons' by 'neutral pions'? 3) L.142 You say you fix the width of tyour signal peak, scaled by the width of the signal by data/mc difference. How did you get the width from data, ie. how was the scale parameter determined? We would also suggest then to rephrase "scaled by a variable parameter". 4) Fig.3 left. How comes that the Bs->Dsrho events do not peak at the Bs-mass ? (Perhaps indeed you often miss one photon from the pi0 decay?) 5) L.192 You say the uncertainty due to Ds*pi cross feed comes from the limited knowledge of its BR. Do you use the PDG value, or your own yield determination? 6) Tab.1 What do you mean with the absolute variation? The caption suggest this is the variation on R*, but the 10^-4 suggest it is the BR ? 1 Intro -------- L.17 "The weak phase ... CKM parameters." -> "The weak phase gamma is the angle of the unitarity triangle with the worst precision." L.25 "... based on approximately ... data." -> "... based on the LHCb data recorded in 2011 corresponding to 1.0 fb-1." L.49 "of _the_ time-dependent CP" L.54 "was evaluated according to:" -> "is evaluated according to" [no semi-colon] 3 Selection ------------ L.99 "calorimetric cluster" -> "calorimeter cluster" L.125 [skip :] "as each other" L.131 [add :] "... is observed around the expected value DeltaM = 143.8 MeV." 4 Yield -------- L.146-148 [We suggest a rephrase: ] "Fully reconstructed background events are due to B0 decays to the same final states as the Bs0 signal, Ds*pi and Ds*K." L.155 [We suggest to add: ] "... contributions in the Ds*K fit, which are estimated from the known branching fractions." Fig.3, left: [add charges to the decay in the legend:] "Bs->Dsrho" -> "Bs0->Ds-rho+" 5 Systematics -------------- L.173/174 [After the result, in L.213, you come back to a systematic on the relative efficiencies. This can be better described here. We would suggest to modify the first sentence: ] "The systematic uncertainties on R* can be separated in uncertainties on the relative event yields (due to the modelling of the background) and on the relative selection efficiency (due to BDT and PID cuts)." L.184-194 [Guidelines suggest not to use single-sentence paragraphs.] L.185 [How about this rephrase: ] "being a variable parameter in the fit, is studied by varying ..." -> "which is allowed to vary in the fit, is studied by fixing the B0->Ds*K yield at its expected value, with a Gaussian constraint corresponding to its uncertainty." L.190 [this comes twice, suggest to skip the first: ] "into Ds*K, " L.195 [After the result, in L.213, you come back to a systemati on the relative efficiencies. This can be better described here. We would suggest to add a sentence before L.195: ] "The uncertainty on the relative selection efficiency originates from uncertainties on the agreement between data and simulation leading to an uncertainty on the BDT selection efficiency, and from uncertainties on the PID selection efficiency." L.197 [skip: ] 'extensive' L.202 [suggest a rephrase: ] "The uncertainty on the pi and K PID efficiencies of the bachelor particle have been extracted..." L.211-213 [We suggest not to discuss the sources systematic uncertainties here. How about this rephrasing instead: ] "The result R* is obtained from the ratio of event yields (0.062+-0.004 (stat)+...-... (sys) ), multiplied by the ratio of efficiencies (1.095+0.012-0.015)." L.215 [skip: ] 'very' L.217/218 "... good description of the measurements for both the vector (R*) and scalar (R) dceays." L.219 [We suggest to add the explicit value used: ] "B(B0s->Ds*pi)=2.0+-0.5x10^-3 obtained by ..." L.221 "bf" -> "\BR"