共查询到20条相似文献,搜索用时 25 毫秒
1.
《The European Physical Journal C - Particles and Fields》2006,47(3):597-610
A measurement of charm and beauty dijet photoproduction cross sections at the ep collider HERA is presented. Events are selected
with two or more jets of transverse momentum pt
jet1(2)>11(8) GeV in the central range of pseudo-rapidity -0.9<ηjet1(2)<1.3. The fractions of events containing charm and beauty quarks are determined using a method based on the impact parameter,
in the transverse plane, of tracks to the primary vertex, as measured by the H1 central vertex detector. Differential dijet
cross sections for charm and beauty, and their relative contributions to the flavour inclusive dijet photoproduction cross
section, are measured as a function of the transverse momentum of the leading jet, the average pseudo-rapidity of the two
jets and the observable xγ
obs. Taking into account the theoretical uncertainties, the charm cross sections are consistent with a QCD calculation in next-to-leading
order, while the predicted cross sections for beauty production are somewhat lower than the measurement. 相似文献
2.
Adler SS Afanasiev S Aidala C Ajitanand NN Akiba Y Alexander J Amirikas R Aphecetche L Aronson SH Averbeck R Awes TC Azmoun R Babintsev V Baldisseri A Barish KN Barnes PD Bassalleck B Bathe S Batsouli S Baublis V Bazilevsky A Belikov S Berdnikov Y Bhagavatula S Boissevain JG Borel H Borenstein S Brooks ML Brown DS Bruner N Bucher D Buesching H Bumazhnov V Bunce G Burward-Hoy JM Butsyk S Camard X Chai JS Chand P Chang WC Chernichenko S Chi CY Chiba J Chiu M Choi IJ Choi J Choudhury RK Chujo T 《Physical review letters》2006,96(3):032001
The invariant differential cross section for inclusive electron production in p+p collisions at [FORMULA: SEE TEXT] has been measured by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider over the transverse momentum range 0.4相似文献
3.
We have calculated the next-to-leading order cross section for the inclusive production of charm quarks as a function of
the transverse momentum pT and the rapidity in two approaches using massive or massless charm quarks. For the single-resolved cross section we have
derived the massless limit from the massive theory. We find that this limit differs from the genuine massless version with
factorization by finite corrections. By adjusting subtraction terms we establish a massive theory with subtraction which approaches the massless theory very fast with increasing transverse momentum. With these results and including
the equivalent results for the direct cross section obtained previously as well as double-resolved contributions, we calculate
the inclusive cross section in collisions using realistic evolved non-perturbative fragmentation functions and compare with recent data from the LEP collaborations
ALEPH, L3 and OPAL. We find good agreement.
Received: 14 February 2003 / Published online: 5 May 2003 相似文献
4.
C. Adloff et al. 《The European Physical Journal C - Particles and Fields》2000,18(2):293-302
The inclusive cross section for the photoproduction of neutral pions has been measured as a function of the transverse momentum,
rapidity, and Feynman x of the mesons at an average photon–proton centre-of-mass energy of 208 GeV and for photon virtualities below GeV. The measurement extends the range covered by previous charged particle measurements at HERA by two units of rapidity in the photon
direction down to a value of in the centre-of-mass frame. The transverse momentum distribution is well described over the whole measured range by a power law ansatz, while an exponential
fit falls below the data at transverse momentum values above 1.5 GeV/c. Good agreement with the predictions of the Monte Carlo
models PYTHIA and PHOJET is found. In the context of the PYTHIA model the data are inconsistent with large intrinsic transverse
momentum values in the photon.
Received: 14 June 2000 / Published online: 27 November 2000 相似文献
5.
The next-to-leading order cross section for the inclusive production of charm quarks in collisions is calculated as a function of the transverse momentum and the rapidity y in approaches using massive or massless charm quarks. For the direct cross section we derive the massless limit from the
massive theory with the result that this limit differs from the massless version with factorization by finite corrections. Subtracting or adding these corrections allows us to compare the two approaches on equal
footing. We establish massless and massive versions with 3 and 4 initial flavours which are shown to approach the massless
approximations very fast with increasing . With these results we calculate the inclusive cross section in collisions using realistic evolved fragmentation functions with appropriate factorization scales and compare with recent
data for from three LEP collaborations after single- and double-resolved contributions have been added.
Received: 25 September 2001 / Published online: 5 November 2001 相似文献
6.
Adler SS Afanasiev S Aidala C Ajitanand NN Akiba Y Alexander J Amirikas R Aphecetche L Aronson SH Averbeck R Awes TC Azmoun R Babintsev V Baldisseri A Barish KN Barnes PD Bassalleck B Bathe S Batsouli S Baublis V Bazilevsky A Belikov S Berdnikov Y Bhagavatula S Boissevain JG Borel H Borenstein S Brooks ML Brown DS Bruner N Bucher D Buesching H Bumazhnov V Bunce G Burward-Hoy JM Butsyk S Camard X Chai JS Chand P Chang WC Chernichenko S Chi CY Chiba J Chiu M Choi IJ Choi J Choudhury RK Chujo T 《Physical review letters》2005,94(8):082301
The PHENIX experiment has measured midrapidity transverse momentum spectra (0.4
相似文献
7.
Aaltonen T Álvarez González B Amerio S Amidei D Anastassov A Annovi A Antos J Apollinari G Appel JA Apresyan A Arisawa T Artikov A Asaadi J Ashmanskas W Auerbach B Aurisano A Azfar F Badgett W Barbaro-Galtieri A Barnes VE Barnett BA Barria P Bartos P Bauce M Bauer G Bedeschi F Beecher D Behari S Bellettini G Bellinger J Benjamin D Beretvas A Bhatti A Binkley M Bisello D Bizjak I Bland KR Blumenfeld B Bocci A Bodek A Bortoletto D Boudreau J Boveia A Brau B Brigliadori L Brisuda A Bromberg C 《Physical review letters》2011,106(14):141803
We report the most sensitive direct search for pair production of fourth-generation bottomlike chiral quarks (b') each decaying promptly to tW. We search for an excess of events with an electron or muon, at least five jets (one identified as due to a b or c quark), and an imbalance of transverse momentum by using data from pp collisions collected by the CDF II detector at Fermilab with an integrated luminosity of 4.8 fb(-1). We observe events consistent with background expectation, calculate upper limits on the b' pair-production cross section (σ(bb')) ?30 fb for m(b') > 375 GeV/c2), and exclude m(b') < 372 GeV/c2 at 95% confidence level assuming a 100% branching ratio of b' to tW. 相似文献
8.
Vejcik S Velev G Vidal R Vilar R Vologouev I Vucinic D Wagner RG Wagner RL Wahl J Wallace NB Walsh AM Wang C Wang CH Wang MJ Watanabe T Watts T Webb R Wenzel H Wester WC Wicklund AB Wicklund E Williams HH Wilson P Winer BL Winn D Wolbers S 《Physical review letters》2000,84(5):845-850
The transverse momentum and total cross section of e(+)e(-) pairs in the Z-boson region of 66相似文献
9.
A.L.S. Angelis G. Basini H.-J. Besch R.E. Breedon L. Camilleri T.J. Chapin R.L. Cool P.T. Cox C. von Gagern C. Grosso-Pilcher D.S. Hanna B.M. Humphries J.T. Linnemann C. Newman-Holmes R.B. Nickerson N. Phinney B.G. Pope J.M. Yelton 《Physics letters. [Part B]》1984,147(6):472-476
A sample of 58e+e? events with an invariant mass greater than 11 GeV/c2 produced in pp collisions at a centre-of-mass energy of 62.3 GeV is discussed. The cross sections are presented as a function of the mass and transverse momentum. The electron pairs produced with a mean transverse momentum of 2.50 ± 0.25 GeV/c. 相似文献
10.
The H Collaboration 《The European Physical Journal C - Particles and Fields》2005,41(4):453-467
A measurement of the beauty production cross section in ep collisions at a centre-of-mass energy of 319 GeV is presented. The data were collected with the H1 detector at the HERA collider in the years 1999-2000. Events are selected by requiring the presence of jets and muons in the final state. Both the long lifetime and the large mass of b-flavoured hadrons are exploited to identify events containing beauty quarks. Differential cross sections are measured in photoproduction, with photon virtualities Q2 < 1 GeV2, and in deep inelastic scattering, where 2 < Q2 < 100 GeV2. The results are compared with perturbative QCD calculations to leading and next-to-leading order. The predictions are found to be somewhat lower than the data.Received: 7 February 2005, Revised: 26 April 2005, Published online: 31 May 2005 相似文献
11.
Aad G Abbott B Abdallah J Abdelalim AA Abdesselam A Abdinov O Abi B Abolins M Abramowicz H Abreu H Acerbi E Acharya BS Adams DL Addy TN Adelman J Aderholz M Adomeit S Adragna P Adye T Aefsky S Aguilar-Saavedra JA Aharrouche M Ahlen SP Ahles F Ahmad A Ahsan M Aielli G Akdogan T Akesson TP Akimoto G Akimov AV Akiyama A Alam MS Alam MA Albert J Albrand S Aleksa M Aleksandrov IN Alessandria F Alexa C Alexander G Alexandre G Alexopoulos T Alhroob M Aliev M Alimonti G Alison J Aliyev M Allport PP 《Physical review letters》2012,108(4):041805
A search for new phenomena in tt events with large missing transverse momentum in proton-proton collisions at a center-of-mass energy of 7 TeV is presented. The measurement is based on 1.04 fb(-1) of data collected with the ATLAS detector at the LHC. Contributions to this final state may arise from a number of standard model extensions. The results are interpreted in terms of a model where new top-quark partners are pair produced and each decay to an on-shell top (or antitop) quark and a long-lived undetected neutral particle. The data are found to be consistent with standard model expectations. A limit at 95% confidence level is set excluding a cross section times branching ratio of 1.1 pb for a top-partner mass of 420 GeV and a neutral particle mass less than 10 GeV. In a model of exotic fourth generation quarks, top-partner masses are excluded up to 420 GeV and neutral particle masses up to 140 GeV. 相似文献
12.
Rossi P Mirazita M Ronchetti F De Sanctis E Adams G Ambrozewicz P Anciant E Anghinolfi M Asavapibhop B Audit G Avakian H Bagdasaryan H Ball JP Barrow S Battaglieri M Beard K Bektasoglu M Bellis M Benmouna N Berman BL Bertozzi W Bianchi N Biselli AS Boiarinov S Bonner BE Bouchigny S Bradford R Branford D Briscoe WJ Brooks WK Burkert VD Butuceanu C Calarco JR Carman DS Carnahan B Chen S Cole PL Cords D Corvisiero P Crabb D Crannell H Cummings JP De Vita R Degtyarenko PV Denizli H Dennis L 《Physical review letters》2005,94(1):012301
13.
Abazov VM Abbott B Abolins M Acharya BS Adams M Adams T Aguilo E Ahn SH Ahsan M Alexeev GD Alkhazov G Alton A Alverson G Alves GA Anastasoaie M Ancu LS Andeen T Anderson S Andrieu B Anzelc MS Arnoud Y Arov M Arthaud M Askew A Asman B Assis Jesus AC Atramentov O Autermann C Avila C Ay C Badaud F Baden A Bagby L Baldin B Bandurin DV Banerjee P Banerjee S Barberis E Barfuss AF Bargassa P Baringer P Barreto J Bartlett JF Bassler U Bauer D Beale S Bean A Begalli M Begel M Belanger-Champagne C 《Physical review letters》2008,101(6):062001
We report on a measurement of the inclusive jet cross section in pp[over ] collisions at a center-of-mass energy sqrt[s]=1.96 TeV using data collected by the D0 experiment at the Fermilab Tevatron Collider corresponding to an integrated luminosity of 0.70 fb;{-1}. The data cover jet transverse momenta from 50 to 600 GeV and jet rapidities in the range -2.4 to 2.4. Detailed studies of correlations between systematic uncertainties in transverse momentum and rapidity are presented, and the cross section measurements are found to be in good agreement with next-to-leading order QCD calculations. 相似文献
14.
Adler SS Afanasiev S Aidala C Ajitanand NN Akiba Y Alexander J Amirikas R Aphecetche L Aronson SH Averbeck R Awes TC Azmoun R Babintsev V Baldisseri A Barish KN Barnes PD Bassalleck B Bathe S Batsouli S Baublis V Bazilevsky A Belikov S Berdnikov Y Bhagavatula S Boissevain JG Borel H Borenstein S Brooks ML Brown DS Bruner N Bucher D Buesching H Bumazhnov V Bunce G Burward-Hoy JM Butsyk S Camard X Chai JS Chand P Chang WC Chernichenko S Chi CY Chiba J Chiu M Choi IJ Choi J Choudhury RK Chujo T 《Physical review letters》2004,92(5):051802
J/psi production has been measured in proton-proton collisions at square root of s=200 GeV over a wide rapidity and transverse momentum range by the PHENIX experiment at the Relativistic Heavy Ion Collider. Distributions of the rapidity and transverse momentum, along with measurements of the mean transverse momentum and total production cross section are presented and compared to available theoretical calculations. The total J/psi cross section is 4.0+/-0.6(stat)+/-0.6(syst)+/-0.4(abs) mu b. The mean transverse momentum is 1.80+/-0.23(stat)+/-0.16(syst) GeV/c. 相似文献
15.
《The European Physical Journal C - Particles and Fields》2007,49(2):511-522
The photoproduction of prompt photons, together with an accompanying jet, has been studied in ep collisions at a centre-of-mass
energy of 318 GeV with the ZEUS detector at HERA using an integrated luminosity of 77 pb-1. Cross sections were measured for the transverse energy of the photon and the jet larger than 5 and 6 GeV, respectively.
The differential γ+jet cross sections were reconstructed as functions of the transverse energy, pseudorapidity and xγ
obs, the fraction of the incoming photon momentum taken by the photon-jet system. Predictions based on leading-logarithm parton-shower
Monte Carlo models and next-to-leading-order (NLO) QCD generally underestimate the cross sections for the transverse energies
of prompt photons below 7 GeV, while the kT-factorisation QCD calculation agrees with the data better. When the minimum transverse energy of prompt photons is increased
to 7 GeV, both NLO QCD and the kT-factorisation calculations are in good agreement with the data. 相似文献
16.
C. Adloff et al. 《The European Physical Journal C - Particles and Fields》1999,10(3):373-393
The electroproduction of and mesons is studied in elastic, quasi-elastic and inclusive reactions for four momentum transfers and photon-proton centre of mass energies GeV. The data were taken with the H1 detector at the electron proton collider HERA in the years 1995 to 1997. The total virtual
photon-proton cross section for elastic production is measured as a function of and W. The dependence of the production rates on the square of the momentum transfer from the proton (t) is extracted. Decay angular distributions are analysed and the ratio of the longitudinal and transverse cross sections is
derived. The ratio of the cross sections for quasi-elastic and meson production is measured as a function of . The results are discussed in terms of theoretical models based upon perturbative QCD. Differential cross sections for inclusive
and inelastic production of mesons are determined and predictions within two theoretical frameworks are compared with the data, the non-relativistic
QCD factorization approach including colour octet and colour singlet contributions, and the model of Soft Colour Interactions.
Received: 10 March 1999 / Published online: 8 September 1999 相似文献
17.
Abulencia A Acosta D Adelman J Affolder T Akimoto T Albrow MG Ambrose D Amerio S Amidei D Anastassov A Anikeev K Annovi A Antos J Aoki M Apollinari G Arguin JF Arisawa T Artikov A Ashmanskas W Attal A Azfar F Azzi-Bacchetta P Azzurri P Bacchetta N Bachacou H Badgett W Barbaro-Galtieri A Barnes VE Barnett BA Baroiant S Bartsch V Bauer G Bedeschi F Behari S Belforte S Bellettini G Bellinger J Belloni A Ben Haim E Benjamin D Beretvas A Beringer J Berry T Bhatti A Binkley M Bisello D Bishai M 《Physical review letters》2006,96(12):122001
We report on a measurement of the inclusive jet production cross section as a function of the jet transverse momentum in pp collisions at (square root s)=1.96 TeV using data collected with the upgraded Collider Detector at Fermilab in run II, corresponding to an integrated luminosity of 385 pb-1. The measurement is carried out for jets with rapidity 0.1相似文献
18.
We study high energy proton-proton elastic scattering in the framework of Pomeron exchange model. The cross section of the process are calculated without any free parameters. Our finding is that Pomeron exchange theory gives perfect fits to total cross section at the energy of√s higher than 10 GeV and to differential cross section at the momentum transfer [t] less than 1.5 GeV2. For total cross section at lower energy √s < 10 GeV and differential cross section at larger momentum transfer region of |t| > 1.5 GeV2, the Pomeron exchange theory needs to be improved. 相似文献
19.
The TileCal System of the ATLAS Collaboration C. Alexa et al. 《The European Physical Journal C - Particles and Fields》2003,28(3):297-304
The energy spectrum and the cross section of photonuclear interactions of 180 GeV muons in iron were measured at the CERN
SPS using prototype modules of the ATLAS hadron calorimeter. The differential cross section for a muon fractional energy loss was measured in the range 0.1<v<1. The integrated cross section is cm2g-1 in agreement with the theoretical prediction of cm2g-1. The best adjustment of the data to the theory is achieved for the value of of the photon-nucleon cross section for photons with energies in the range from 18 to 180 GeV.
Received: 22 January 2003 / Published online: 5 May 2003 相似文献
20.
Seidl R Hasuko K Abe K Adachi I Aihara H Anipko D Asano Y Aushev T Bakich AM Balagura V Barberio E Bartel W Bay A Bitenc U Bizjak I Blyth S Bozek A Bracko M Browder TE Chang P Chen A Cheon BG Choi Y Choi YK Chuvikov A Dalseno J Danilov M Dash M Dragic J Eidelman S Fratina S Gabyshev N Gershon T Go A Gokhroo G Golob B Gorisek A Grosse Perdekamp M Ha HC Hayasaka K Hayashii H Hazumi M Hokuue T Hoshi Y Hou S Hou WS Iijima T Inami K Ishikawa A Itoh R Iwasaki M Iwasaki Y Kang JH Kapusta P Katayama N 《Physical review letters》2006,96(23):232002
The Collins effect connects transverse quark spin with a measurable azimuthal dependence in the yield of hadronic fragments around the quark's momentum vector. Using two different reconstruction methods, we find evidence of statistically significant azimuthal asymmetries for charged pion pairs in e(+)e(-) annihilation at a center-of-mass energy of 10.52 GeV, which can be attributed to a transverse polarization of the primordial quarks. The measurement was performed using a sample of 79 x 10(6) hadronic events collected with the Belle detector. 相似文献