Search for Heavy Stable Charged Particles in pp collisions at sqrt(s) = 7 TeV
Entry on CERN Document Server for Draft 1
On Tue, 16 Nov 2010, Marco Costa wrote:
l'ho letto Ti mando un commento generale a caldo poi si puo scendere nel dettaglio.
Viene definito un estimatore per definire la compatibilita' della perdita di energia de/dx di una particella
carica con quella di una MIP e dedurre da eventuali differenze la presenza di una HSCP.
Non viene mostrata nessuna distribuzione di de/dx, nessuna distribuzione del campione di tracce su cui
si lavora e si taglia ma solo due figure finali un po' amorfe e una tabella
In compenso il testo e' pieno di tanti piccoli dettagli che fanno pensare ad un lavoro accurato ma non ci sono i plot per
convincersi della cosa
Credo che CMS abbia bisogno di dimostare la credibilita e l'attendibilita di quello che dichiara soprattutto
quando si spinge in territori nuovi, oltre SM. e che debba essere comprensibile anche per qualcuno che non e' CMS
Questo articolo cosi' com'e' non assolve a questi due mandati''
On Wed, 17 Nov 2010, Ernesto MIGLIORE wrote:
» concordo con il commento di Marco.
Noto pero` che la versione “v3” del PAS era piu` lunga (20 pg anziche' 9) e
maggiormente corredata da figure, tra cui gli spettri di dE/dx.
Immagino sia stata una scelta editoriale di ARC+publication board per
mantenere in formato di “letter” i primi articoli di CMS riguardanti limiti
su nuova fisica. Ciao,
On Wed, 24 Nov 2010, Mario Pelliccioni wrote:
Anzitutto, personalmente trovo che per lo spazio che avevano a disposizione
sia ragionevolmente completa come descrizione
Inline comments
l.18 (EM): move the gluino symbol before the parentheses
lines 28,29 (MP): remove the semicolumn in the list of possible triggers, as it makes difficult to realize it is an actual list
l.30 (EM): pT>100 GeV/c → ET>100 GeV (if it is a calorimetric measurement)
line 44 (MP): “The dE/dx measurement” → “The dE/dx measurement precision”
l.44-48 (EM): naively I would expect the saturation being more relevant for thicker (500 um) outermost modules (so it is not clear why is discussed in detail the case of 300 um thick modules)
lines 49,50 (MP): While I don't know for the trigger, the statement that the reconstruction efficiency in the muon detector is limited by requirements on the arrival time of the particles to the muon system is quite strong and not really supported by any study. This may be the case for the specific HSCP scenario, but it is not in the general case, as the sentece implies.
l.52-53 (EM): “reaching very-low values”: try to be more quantitative
line 3 (in the paragraph with no lines after line 53) (MP): Did you try to cut on the flight significance instead of cutting on the impact parameters? A measurement of an impact parameter comes with an error, and it is more logic to use the significance (either the 3D flight information or the 2D transverse flight).
l.64+1 and below (EM): which are the units in which I_h is expressed (ADC/cm, electrons/cm,..)? This affects the units for the coefficients “K” and “C” of eq.3 (values in l.68)
line 69 (MP): remove significantly. Going from a 7% resolution at low pT to a 12% resolution at hight pT doesn't seem a drastical change
line 75 (MP): it would be better for the reader to remind that i corresponds to the i-th class of charge measurements
lines 80-83 (MP): did you do any study to prove that the systematic effect determination found in the region below 75 GeV/c2 is constant also beyond the control sample region? (in particular, in the region over 100 GeV/c2…)
lines 111-122 (MP): what you define as signal acceptance is actually the sum of very different contributions to the selection. The use of acceptance has a very specific meaning and it is improper when used for various selection criteria (track requirements, jet energy scale, etc.)
line 123 (MP): I don't know if it already exists, but it would be nice to have a reference on how the systematic uncertainty on the integrated luminosity (you can remove “absolute value of”) was calculated, or at least provide a sentence explaining it.
line 124 (MP): the use of the term C.L. is improper in a Bayesian approach. What you are actually determining is a Probability Interval. Confidence level is a pure frequentist concept.
l.125 (EM): I would say that what is “conservative” is the assumption of zero background and not the 95% CL upper limit
(To me a “more” conservative upper limit is a 96% CL value instead of 95%)
Table.1 (EM): A bit obscure the meaning of the pT^cut and Ias^cut columns. E.g. for “Loose Mu” category, it seems that the tracks are selected in a 34-36 GeV/c “box” and not in a “half-plane” pT>34,…,36 GeV/c where the exact threshold is determined for having a fixed background efficiency.
If these are the ranges of the pT (Ias) thresholds used, specify
the word “range” in the caption or in the table headings.
Finally pT are in GeV/c units.
Fig.1,2 (EM) I guess that “preliminary” will disappear in the final version
EM Ernesto
MP Mario