[Rivet] thrustMinor returns zero while calculating transverse thrust

[Holger Schulz]

On 21/11/13 16:59, Deepak Kar wrote:
> Hi Holger,
>
> Thanks, that is very helpful to know. Since many of us now calculating
> transverse quantities, may be it will be useful to add these methods
> more clearly?
Hmm, I guess so. Right now the 3D thrust is abused IIRC to
avoid code-duplication.

These lines:

         // Transverse Thrust calculation requires p_z to be set to 0
         Vector3 mom = p.momentum().vector3();
         mom.setZ(0.0);
         momenta.push_back(mom);

Are essentially a hack.

At transverse Thrust projection could be introduced, will suggest this
to Andy.

Holger

>
> Cheers,
> Deepak
>
> On Thu, Nov 21, 2013 at 4:50 PM, Holger Schulz
> <hschulz at physik.hu-berlin.de> wrote:
>> Hi Deepak,
>>
>> in the transverse case you get Thrust minor by asking
>> the thrust projection for major:
>>
>> double minor  = thrust.thrustMajor();
>>
>> Cheers,
>> Holger
>>
>> On 21/11/13 16:39, Deepak Kar wrote:
>>> Hi,
>>>
>>> We are trying to finalize the Rivet analysis for arXiv:1207.6915
>>> (ATLAS charged particle event shape).
>>> A previous version of the data values is already in HepData, which
>>> needs an update (more [lots were addded, systematics reduced following
>>> referee review). Also a previous version of the analysis was written
>>> (but never validated), but it seemed to work. However, with rivet
>>> 1.8.3, thrustMinor returns zero, however thrustMajor gives non-zero
>>> values. The relevant part of the code:
>>>
>>>
>>>  // Loop over particles
>>>        foreach (const Particle& p, particles500) {
>>>          num500 += 1;
>>>          ptSum500 += p.momentum().pT()/GeV;
>>>
>>>          // Transverse Thrust calculation requires p_z to be set to 0
>>>          Vector3 mom = p.momentum().vector3();
>>>          mom.setZ(0.0);
>>>          momenta.push_back(mom);
>>>        }
>>>
>>>
>>>  // Actual Thrust calculation
>>>       Thrust thrust;
>>>       thrust.calc(momenta);
>>>
>>>       const double T  = 1.0 - thrust.thrust();
>>>       const double TM = thrust.thrustMinor();
>>>
>>>
>>> We will convert the code to 2.0.x once it is fixed.
>>>
>>> Thanks,
>>> Deepak
>>>
>
>