STAR HardProbes PWG

["Ma, Rongrong" <marr AT bnl.gov>]

Hello Nihar, Lijuan

For the Upsilon paper we just published, a threshold of 18 (HT2) was used. We 
also published Jpsi cross section in 500 GeV pp collisions using HT2, which 
covers Jpsi down to 4 GeV/c. The MB sample (20 B) we aim to record should be 
sufficient for covering low-pT Jpsi, and Upsilon even though Upsilon can 
already be measured down to 0 pT with HT2 trigger. 

Furthermore, the 20 B MB events roughly correspond to 2 nb^-1 of luminosity. 
So any HT trigger with a pre-scale larger than 20 will not be very useful, 
which I think is the case for our current HT1 (threshold = 11). So I think it 
only makes sense to raise the threshold to 15 if there is physics program 
requiring it, such that the pre-scale can be smaller than 20. Otherwise, we 
should probably drop the HT1 trigger. 

For the question of whether we can use threshold 15 for Upsilon, the answer 
is yes, However, the issue is that we will not be able to sample the full 
luminosity with this threshold, which effectively reduces the statistics. So 
I do not see a strong motivation there. 

Best
Rongrong

> On Jun 21, 2023, at 10:57 AM, Nihar Sahoo via Star-hp-l 
> <star-hp-l AT lists.bnl.gov> wrote:
> 
> Dear Lijuan,
> 
> sorry, I could not join yesterday trigger board meeting.
> 
> As per BUR 23+25, we have mainly Jet substructure, gamma+jet, J/psi and 
> Upsilon physics program in Au+Au.
> 
> 1) For Jet substructure measurement, HT1 and HT2 with 11 (~2.6 GeV) and 18 
> (~4.2 GeV), respectively, would be OK.
> 2) For gamma+jet: BHT3(+L2gamma) 25 (~5.9 GeV); I think this is same with 
> previous runs; so it is OK.
> 3) J/psi: probably Lower HT1 threshold 11 (~2.6 GeV)
> 4)Upsilon: both HT1,2 with threshold 11 and 18 would be Ok.
> But need to confirm from PAs (Others can comment) if it is Ok to use HT2 as 
> 15 (~3.5) for Upsilon analysis or not.
> 
> Thank you
> Nihar
> 
> 
>> For Run23, we have the following:
>> BHT1-VPD100: the threshold is 11
>> BHT2-VPD100: the threshold is 18
>> BHT3: the threshold is 25
> 
> On 2023-06-21 18:54, ruanlj via Star-triggerboard-l wrote:
>> Hi All,
>> After yesterday's trigger board meeting, I went to check the BHT
>> thresholds for Run 16.
>> As mentioned by Rongrong, there was no BHT2 trigger for hard probes 
>> physics.
>> There were two triggers:
>> BHT1-VPD10: the threshold was set to 16 and later was changed to 15
>> BHT3: the threshold was 25
>> For Run23, we have the following:
>> BHT1-VPD100: the threshold is 11
>> BHT2-VPD100: the threshold is 18
>> BHT3: the threshold is 25
>> My question to hard probes pwg/experts: is the current threshold
>> setting for BHT triggers good for your physics program?
>> Lijuan
>> _______________________________________________
>> Star-triggerboard-l mailing list
>> Star-triggerboard-l AT lists.bnl.gov
>> https://lists.bnl.gov/mailman/listinfo/star-triggerboard-l
> _______________________________________________
> Star-hp-l mailing list
> Star-hp-l AT lists.bnl.gov
> https://lists.bnl.gov/mailman/listinfo/star-hp-l