J/si an Usilon rouction crosssections at the ALAS exeriment Lancaster University, UK Email: susan.cheatham@cern.ch New ALAS measurements of romt an nonromt J/ψ an of Usilon rouction at a centreof mass energy of ev are resente. Comarisons with theoretical reictions an recision measurements mae at energies of., an 8 ev are iscusse. os(dis XXIV International Worksho on DeeInelastic Scattering an Relate Subjects Aril, DESY Hamburg, Germany Seaker. c Coyright owne by the author(s uner the terms of the Creative Commons AttributionNonCommercialNoDerivatives. International License (CC BYNCND.. htt://os.sissa.it/
J/si an Usilon rouction crosssections at the ALAS exeriment. Introuction Measurements of quarkonium rouction test multiscale Quantum Chromo Dynamics (QCD calculations at the bounary of the erturbative an nonerturbative regimes. Challenges still remain in roviing a coherent theoretical icture which can exlain all measurements simultaneously. hese stuies are also interesting since inclusive rouction of heavy flavour reresents a significant backgroun for measurements in the electroweak an Higgs sectors. Quarkonium stuies consier the imuon ecays of sameflavour quark an antiquark boun states such as J/ψ(c c an ϒ(b b. Singlemuon triggers are use, sulemente by imuon triggers, which leave the invariant mass winow aroun the signal largely unrescale. romt quarkonia are rouce irectly in the rotonroton ( interaction or through feeown ecays from higher quarkonium states. Nonromt quarkonia are rouce in the ecay chain of Bharons, where the ecay vertex can be islace from the rimary vertex. romt an nonromt rouction, as well as signal an backgroun, are searate using simultaneous massecay time fits. he large crosssection for quarkonium rouction an extensive ata samles available at the Large Haron Collier (LHC will enable etaile stuy of theoretical moels across a large range of momentum transfer. Details of the ALAS etector may be foun in [.. J/ψ rouction Figure shows the mass istributions an Figure shows the seuoroer ecay time istributions for ata collecte at.,, 8 an ev. rojections of the unbinne maximum likelihoo fit result are shown for a reresentative interval. he muon selection is equivalent in all four energy regimes, requiring muon > GeV an y <.. In aition the muon air are selecte to be oositely charge with a common vertex. A requirement of muon air > 8 GeV an y < ensures the geometrical accetance of the etector an the trigger an reconstruction efficiency corrections o not vary raily an are consistent for romt an nonromt J/ψ. In the ev stuy an isotroic sinalignment hyothesis was assume, with no geometric accetance correction alie to the ata an no sinalignment uncertainty consiere. he measurements at., an 8 ev are correcte for accetance, trigger an reconstruction efficiencies. Doubleifferential romt an nonromt J/ψ crosssections are shown in Figure for ata collecte at an 8 ev. Measurements are correcte for accetance, trigger an reconstruction efficiencies. he romt crosssections are comare to NLO Nonrelativistic QCD (NRQCD theory calculations. [,, heory uncertainties arise from scale, charm quark mass an longistance matrix elements. Reasonable agreement is seen between theory an ata. he nonromt crosssections are comare to FixeOrer with NexttoLeaingLog (FONLL theory calculations. In this case theory uncertainties arise from scale an quark masses. heory reicts slightly harer for J/ψ than is seen in the ata. he ratios of the theoretical reictions to the ata are resente in Figure for the ifferential romt crosssections of J/ψ as a function of ( for each of the eight raiity slices. FONLL os(dis
J/si an Usilon rouction crosssections at the ALAS exeriment Entries / ( MeV 8. < < GeV. < y* <. ALAS reliminary +b s NN =. ev Fit Moel romt Signal Nonromt Signal romt Bkg Nonromt Bkg Entries / MeV ALAS reliminary s= ev,. fb. < <. GeV. < y <. Entries / MeV..8....8..........8.8.9 m( [GeV romt Non romt J/ψ ψ(s N ψ(s Entries / MeV..8....8 ALAS reliminary s=8 ev,. fb. < <. GeV y <. 8 Entries / MeV 8 romt Non romt J/ψ ψ(s N ψ(s [GeV m.......8.8.9 m( [GeV..8....8 m( [GeV Caniates /. GeV..8....8 m( [GeV ALAS reliminary y <. s = ev,. b. < <. GeV..8.9...... m(µ + µ [GeV Fit Backgroun Figure : rojections of the fit result over the mass istributions for ata collecte at.,, 8 an ev for one reresentative interval. he ata are shown with error bars in black, suerimose with the iniviual comonents of the fit result rojections, where the total romt an nonromt comonents are reresente by the ashe an otte lines, resectively, an the shae areas show the signal romt an nonromt contributions. [9,, 8 calculations mae within the framework of erturbative QCD are quite successful in escribing nonromt rouction of quarkonium states. he romt crosssections are comare to NRQCD. here is greater uncertainty seen in the theory inicating a satisfactory unerstaning of the romt rouction mechanisms is still to be achieve Figure shows the nonromt ifferential J/ψ rouction fraction at ev measure in the most central raiity region ( y <. comare to revious measurements from ALAS in collisions at. an ev, an from the Collier Detector at Fermilab (CDF in collisions at s =.9 ev. Some eenence is seen on the centreofmass energy an initial state. os(dis. Usilon rouction Both NNLO* Color Singlet Moel (CSM [ an the Color Evaoration Moel (CEM [, reictions have some roblems in escribing the normalisation an shae of the ifferential sectra. In articular, NNLO* CSM ramatically unerestimates the rate at high transverse momenta, where the ata ten to agree better with the CEM.
J/si an Usilon rouction crosssections at the ALAS exeriment Entries / (. s Entries /. s 8. < < GeV. < y* <. ALAS reliminary +b s NN =. ev Fit Moel romt Signal Nonromt Signal romt Bkg Nonromt Bkg 8 ALAS reliminary s=8 ev,. fb romt Non romt J/ψ ψ(s N ψ(s. < <. GeV y <. τ [s 8 τ( [s Entries /. s Caniates /. s ALAS reliminary s= ev,. fb romt Non romt J/ψ ψ(s N ψ(s. < <. GeV. < y <. 8 τ( [s ALAS reliminary s = ev. b y <.. < <. GeV 8 + (µ µ [s Fit romt Signal Nonromt Signal Backgroun Figure : rojections of the fit result over the seuoroer ecay time istributions for ata collecte at.,, 8 an ev for one reresentative interval. he ata are shown with error bars in black, suerimose with the iniviual comonents of the fit result rojections, where the total romt an nonromt comonents are reresente by the ashe an otte lines, resectively, an the shae areas show the signal romt an nonromt contributions. [9,, 8 os(dis y ata x,. y. ALAS reliminary ata x,. y <. ata x,. y <. s= ev,. fb 9 romt J/ψ ata x ata x ata x 89,. y <.,. y <.,. y <. ata x,. y <. ata x,. y <. NRQCD reiction ( [GeV y ata x,. y. ALAS reliminary ata x,. y <. ata x,. y <. s=8 ev,. fb ata x,. y <. ata x,. y <. 9 romt J/ψ ata x,. y <. ata x,. y <. 8 ata x,. y <. NRQCD reiction 8 9 ( [GeV y ata x,. y. ALAS reliminary ata x,. y <. 9 8 s= ev,. fb Nonromt J/ψ ata x ata x ata x ata x 89,. y <.,. y <.,. y <.,. y <. ata x,. y <. ata x,. y <. FONLL reiction ( [GeV y ata x,. y. ALAS reliminary ata x,. y <. 9 8 s=8 ev,. fb Nonromt J/ψ ata x ata x ata x ata x 8 9,. y <.,. y <.,. y <.,. y <. ata x,. y <. ata x,. y <. FONLL reiction ( [GeV Figure : he ifferential romt crosssection times imuon branching fraction of J/ψ as a function of ( for each slice of raiity. romt rouction (to, nonromt (bottom, ev (left an 8 ev (right. For each increasing raiity slice, an aitional scaling factor of is alie to the lotte oints for visual clarity. he theoretical reictions use are NRQCD for romt an FONLL for nonromt rouction. [
J/si an Usilon rouction crosssections at the ALAS exeriment Ratio of theory [8 ev / ev ALAS reliminary s=8 ev,. fb Ratio of theory [8 ev / ev ALAS reliminary s=8 ev,. fb s= ev,. fb s= ev,. fb Ratio of ata [8 ev / ev romt J/ψ CrossSection Ratio of ata [8 ev / ev Nonromt J/ψ CrossSection 8 ev / ev. y.. y <. 8 ev / ev. y.. y <.. y <.. y <.. y <.. y <.. y <.. y <.. y <.. y <.. y <.. y <. 8 9 8 9 ( [GeV. y <.. y <. 8 9 8 9 ( [GeV Figure : he ratio of the 8 ev an ev ifferential crosssections are resente for romt (left an nonromt (right J/ψ for both ata an theoretical reictions. he theoretical reictions use are NRQCD for romt an FONLL for nonromt rouction. he uncertainty on the ata ratio oes not account for ossible correlations between an 8 ev ata, an no uncertainty is shown for the ratio of theory reictions. [ Nonromt Fraction..9.8........ ALAS reliminary ALAS ev,. b, y <. ALAS ev,. fb,. < y <. ALAS. ev, b, y <. CDF (.9 ev, 9. b, y <. 8 9 (µ + µ [GeV os(dis Figure : Nonromt ifferential J/ψ rouction fraction measure in the most central raiity region ( y <. comare to revious measurements from ALAS in collisions at. an ev, an from CDF in collisions at s =.9 ev. he error bars reresent the total uncertainty on the measurements (statistical an systematic. [8 Comarison of results have been mae to several theoretical moels, but none rovie an accurate escrition of the ata over the full range of ϒ transverse momenta accessible with the ev ataset.. Associate rouction he final state of J/ψ associate with a W or Z boson can arise from a single artonarton interaction or two istinct artonarton interactions within the same collision. Associate
J/si an Usilon rouction crosssections at the ALAS exeriment rouction robes the quarkonium rouction mechanism an is sensitive to multile arton interactions. Measurements of the azimuthal angle between the Z boson an J/ψ suggest that both single an ouble arton scattering contributions may be resent in the ata. Measurements of the W boson an J/ψ suggest that single arton scattering is the ominant contribution. A higher rouction rate is reicte through colouroctet transitions than through coloursinglet rocesses, but the execte rouction rate from the sum of singlet an octet contributions is lower than the ata by a factor of to in the range stuie.. Conclusion Many ublications an analyses are in rogress in. he large quarkonium samle from Run has allowe etaile tests of QCD incluing crosssections an branching fractions of stanar quarkonium, associate rouction with vector bosons, hotons an aitional quarkonia. Run measurements are just starting an the results are eagerly awaite. References [ he ALAS Collaboration he ALAS Exeriment at the CERN Large Haron Collier, [JINS (8 S8 [ Y.Q. Ma, K. Wang, an K.. Chao, [arxiv:.98 [ H.S. Shao, [arxiv:.9 [ Ma, YanQing an Wang, Kai an Chao, Kuanga, [arxiv:9. [ L.HarlanLang an W.A. Stirling, htt://suerchic.heforge.org/chigen.html. [ Frawley, Anthony D. an Ullrich,. an Vogt, R. [arxiv:8. [ Barger, Vernon D. an Keung, WaiYee an hillis, R. J. N., [ZEYA,C,9 [8 he ALAS Collaboration Measurement of the ifferential nonromt J/ψ rouction fraction in s = ev collisions at the ALAS exeriment, [ALASCONF os(dis [9 he ALAS Collaboration Stuy of J/ψ an ψ(s rouction in s NN =. ev +b an s =. ev collisions with the ALAS etector", [ALASCONF [ he ALAS Collaboration Measurement of the ifferential crosssections of romt an nonromt rouction of J/ψ an ψ(s in collisions at s = an 8 ev with the ALAS etector", [ARXIV:. [ he ALAS Collaboration Measurement of Usilon rouction in ev collisions at ALAS, [arxiv:. [ he ALAS Collaboration Measurement of ϒ(nS rouction with +b collisions at snn =. ev an collisions at s =. ev, [ALASCONF [ he ALAS Collaboration "Observation an measurements of the rouction of romt an nonromt J/ψ mesons in association with a Z boson in collisions at s = 8 ev", [arxiv:.8 [ he ALAS Collaboration "Measurement of the rouction cross section of romt J/ψ mesons in association with a W ± boson in collisions at s = ev", [arxiv:.8