Comments on LHCb-PAPER-2014-67 We do congratulate the authors with this nice paper. A first question is on shape of the AP-component, which is justified in lines 208-215. However, the motivation leaves a lot of freedom to chose any shape. What fraction of the AP-shape is the sixth-order polynomial based on MC and what fraction is the broad RBW based on not-modeled fragmentation effects? I can not judge it from looking at the shape in Figs 4 and 5. Since the shape of AP might affect the parameters of the resonances in a different way in each of the three p_t bins I would like to see whether all the masses and widths give consistent results in case they are determined independently in each of the p_t bins. A second question is on the overall momentum/mass scale. I presume the uncertainty of the overall momentum scale in the values quoted on page 17 (line 298) is 0.17 MeV. I'm surprised it is so small. Is this taken from another paper? Comments line-by-line: Title ----- Replace "structure" by "broad resonances". A structure can be anything. Abstract -------- We strongly suggest to mention the 5840 and 5960 resonances in the abstract, as they are discussed so prominently in the paper. Replace "in the high transverse momentum region" by "at high transverse pion momentum". In the abstract and conclusions is written "Parameters of these structures are obtained..." This is quite vague. Could this be a bit more specific? For instance, "mass and natural width of these structures are obtained..." or similar. 1 Intro ------- Line 6-8: There is a small contradiction here. First, L is defined as a the relative orbital angular momentum of the two quarks, and then the total angular momentum of the light quark only is |L+-0.5|. In the heavy-quark approximation, there is only the orbital angular momentum of the light quark L. So, this can be fixed by defining L as "the orbital angular momentum of the light quark". Or replace "and the total angular momentum of the light quark j_q" by "and the combination of the relative orbital momentum with the spin of the light quark j_q = |L+-1/2|". Line 25: Replace "Since the B* decays " by "Since the B* meson decays ". Line 28: We suggest: "Due to the missing photon, the peaks from decays to B*pi are shifted ...". Line 33: We appreciate the explanation of the nomenclature in lines 11-14, but here you introduce a new primed B "B' ". Can you add that in the explanation? Footnote: Replace "Letter" by "paper". 2 Detector ---------- Figure 1: Could you make these plots a bit bigger? And make the y-axis title smaller? Replace "fitted with a double Crystal Ball" by "modeled with a double Crystal Ball". This will make it consistent with the rest of the sentence. Add a dash "-" in "second-order". All plots: Make all text in a standard font (not in a bold font). 3 Selection ------------ Line 98: Replace "requires that the trigger which ... is based exclusively" by "requires that the software trigger decision is based exclusively". Line 103 and 105: Use the abbreviation "PV" here. Line 123: Is the background from Bc decay negligible? If so, you could consider a sentence like: "The background from $B_c^+$ mesons is negligible, due to the small production rate of $B_c^+$ mesons, and the fact that the decay $B_c^+\to B^0 \pi^+$ is Cabibbo suppressed \cite{LHCb-PAPER-2013-044}." Line 131: Replace "the lab frame" by "the centre of mass system". A laboratory angle of 150 degrees would not fit in the LHCb acceptance. Line 141: Remove "respectively". It is not needed here. Line 143: Add "mass difference" to "distributions". Figure 3: - Although RS and WS are explained in the text. it helps to understand the plots if these are written in full. - Replace "empty" by "white". An empty histogram is a flat line with zero entries. Line 149, 157: - Use consistently "combinations" for both RS and WS, instead of "events". - It is only after comparison with WS that more events than expected from random combinations show up visibly at masses lower than (NOT "under") the sharp resonances. Therefore, lines 157-162 should move to before "Furthermore . . .". - It is not clear if the RS-WS distribution are fitted or if both the RS and WS distributions are fitted simultaneously. - The statement "It has been checked .. ." is not convincing. Certainly not that WS should describe the combinatorial background of the RS combinations. Equation 1: The numerator sqrt(Gamma(m)) is strange. I expect Gamma(m)**2, or m_0 Gamma(m)**2 if I should believe John Libby. (http://www-pnp.physics.ox.ac.uk/~libby/Teaching/2005/C4-JL-lecture2.pdf) 4 Fit model ------------ Line 200: What is l ? Perhaps it can be defined in lines 6-12 ? 5 Results --------- Line 233: What is meant with "alternative hypotheses" ? Perhaps the explanation could be repeated then in the caption of Tab.3. Table 3: The caption does not match the Table: the top quadruplet does not only contain 5840. Why is the width of the 5840 incompatible between the B+pi- and B0pi+ final states? 7 Interpretation ------------------ Below line 305: The ratio should in a larger format. Best regards, for the Nikhef group, Tjeerd Ketel