Changes between Version 8 and Version 9 of Private/RefereeComments/Section_2
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- Oct 1, 2013, 2:35:58 PM (11 years ago)
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Private/RefereeComments/Section_2
v8 v9 60 60 indeed implemented. 61 61 62 >>> 63 62 >>> The whole paragraph has been re-written for better clarity. The "according to their decay products" expression was referring only to lambda and k-shorts, whose decay products are considered, as an approximation, on average 30% 63 >>> electromagnetically interacting, and 70% strongly interacting. On the other hand charged pions deposit 100% in HCAL if it has not been decayed by the event generator. These are set by default in the configuration file, but they can, as explained >>> in the text, be changed. 64 64 65 65 Eq 2.1 : It is not clear whether the same resolution is used for ECAL and … … 73 73 two detectors would need to be spelt out and compared to the actual values. 74 74 75 Eq 2.2. : Several problems here too. It is not clear whether the shower energy is or is not distributed over 75 >>> For producing the plots we use the nominal resolutions from CMS and ATLAS. The resolution is different for ECAL and HCAL (the text has been changed to make this clear). 76 >>> We are not in favour of quoting the CMS and ATLAS resolutions, since, at this level, we want to stay general and not give the impression that Delphes is limited to these two experiments. 77 >>> We emphasize that Delphes can be used with completely different parameters, corresponding to any generic (symmetric) detector 78 79 Eq 2.2. : Several problems here too. 80 81 * It is not clear whether the shower energy is or is not distributed over 76 82 several towers. Neither Eq 2.2 nor the text seems to mention that. I 77 83 seem to understand that the energy of each particle is concentrated in … … 79 85 reader will certainly miss this subtlety. 80 86 81 * ECAL and HCAL are undefined, even though the casual reader may go as far as guessing that they are defined by equation 2.1 (?) 87 >>> addressed: the sentence: "The energy of each particle is concentrated in 88 one single tower." has been added. 89 90 * sigma(ECAL) and sigma(HCAL) are undefined, even though the casual reader may go as far as guessing that they are defined by equation 2.1 (?) 91 92 >>> addressed: "The parameters $sigma_{ECAL}$ and $sigma_{HCAL}$ are respectively the ECAL and HCAL resolutions, defined in equation~(\ref{eq:calores})" 82 93 83 94 * What is the physics motivation for doing a log-normal instead of a Gaussian smearing? 84 95 96 >>> The lognomal distribution resembles to a gaussian when mean > 6*sigma, that is for most values at high energy, but has the advantage a low energy to be always positive. This ensures to to avoid the positive bias in the effective mean and s.d >>> induced by having a truncated gaussian. 97 85 98 * To define a log-normal distribution, one usually gives the mean and sigma of the logarithm of the distribution, which is normal. Here, are the authors talking about the mean and variance of the log-normal distribution? I guess so, but it would be good to clarify. 99 100 >>>We are talking about the mean and the variance of the lognormal, which have pretty complicated expression in terms of the mean and variance of the normal variable, which, as the referee correctly remarked, are usually given. However, it is clear >>>from the text that the m, and s are the mean and variance of the log-normal distribution and not the mean and variance of the normal distribution. 101 86 102 87 103 PAGE 4 … … 99 115 In \DELPHES, the calorimeters have a finite segmentation in pseudo-rapidity and azimuthal angle ($\eta$,$\phi$). The size of the elementary cells can be defined in the configuration file. For simplicity the segmentation is uniform and for computational reasons we assume the same granularity for ECAL and HCAL. The coordinate of the resulting calorimeter object, the tower, is computed as the geometrical center of the cell. 100 116 101 Long-lived particles reaching the calorimeters deposit a fixed fraction of their energy in the corresponding ECAL ($f_{ECAL}$) and HCAL ($f_{HCAL}$) cells. 117 Long-lived particles reaching the calorimeters deposit a fixed fraction of their energy in the corresponding ECAL ($f_{ECAL}$) and HCAL ($f_{HCAL}$) cells. Since ECAL and HCAL are perfectly overlaid, each particle reaches one ECAL and one HCAL cell. 102 118 By default in \DELPHES electrons and photons leave all their energy in ECAL ($f_{ECAL}=1$), hadrons deposit all their energy in HCAL ($f_{HCAL}=1$), 103 119 with the exception of kaons and $\Lambda$ that share their energy deposit between ECAL and HCAL ($f_{ECAL}=0.3$ and $f_{ECAL}=0.7$), while muons, neutrinos and neutralinos, do not deposit anything in the calorimeters. 104 120 In practice, the user has the freedom to change the default setup, and define for each long-lived particle more accurate values for $f_{ECAL}$ and $f_{HCAL}. 105 121 106 The resolution of the calorimeters isparametrised as a function of the particle energy and the pseudo-rapidity:122 The resolutions of ECAL and HCAL are independently parametrised as a function of the particle energy and the pseudo-rapidity: 107 123 \begin{equation} 108 124 \left(\frac{\sigma}{E}\right)^2 = \left(\frac{S(\eta)}{\sqrt{E}}\right)^2 … … 116 132 \label{eq:etow} 117 133 \end{equation} 118 where the sum runs over all particles that reach the given tower, and $\text{ln}\mathcal{N}(m,s)$ is the log-normal distribution with mean $m$ and variance $s$. A calorimeter tower is also characterized by its position in the ($\eta$,$\phi$) plane, given by the geometrical center of the corresponding cell. In order to avoid having to deal with discrete tower positions, an additional uniform smearing of the position over the cell range is performed.134 The energy of each particle is concentrated in one single tower and the sum runs over all particles that reach the given tower. $\text{ln}\mathcal{N}(m,s)$ is the log-normal distribution with mean $m$ and variance $s$. The parameters $sigma_{ECAL}$ and $sigma_{HCAL}$ are respectively the ECAL and HCAL resolutions, defined in equation~(\ref{eq:calores}). A calorimeter tower is also characterized by its position in the ($\eta$,$\phi$) plane, given by the geometrical center of the corresponding cell. In order to avoid having to deal with discrete tower positions, an additional uniform smearing of the position over the cell range is performed. 119 135 120 136 Calorimeter towers are, along with tracks, crucial ingredients for reconstructing isolated electrons and photons, as well as high-level objects such as jets and missing transverse energy.
