Quark Confinement in C-periodic Cylinders at Temperatures above T_c
Holland, K; Wiese, U.-J.
1997-01-01
Due to the Gauss law, a single quark cannot exist in a periodic volume, while it can exist with C-periodic boundary conditions. In a C-periodic cylinder of cross section A = L_x L_y and length L_z >> L_x, L_y containing deconfined gluons, regions of different high temperature Z(3) phases are aligned along the z-direction, separated by deconfined- deconfined interfaces. In this geometry, the free energy of a single static quark diverges in proportion to L_z. Hence, paradoxically, the quark is ...
Bouzas, Antonio O.; Larios, F.
2015-11-01
We study the DIS and photo-production modes of pairs at the proposed LHeC and its potential to probe the electromagnetic and weak dipole moments (MDM and EDM for ttγ) of the top quark. A framework of eight independent gauge invariant dimension six operators involving the top quark and the electroweak gauge bosons is used. Four of those operators modify the charged tbW coupling which can be probed through the single (anti) top production mode as reported in the literature. One generates ttγ(Z) as well as tbW couplings, while other two do not generate tbW but only ttγ(Z). Our focus is on the MDM and EDM of the top quark for which the photo-production mode of can be an excellent probe. At the proposed electron energies of Ee = 60 and 140 GeV the LHeC could set constraints stronger than the indirect limits from b → sγ and the potential limits of the LHC through production[1].
Bound States of (Anti-)Scalar-Quarks in $SU(3)_{c}$ Lattice QCD
Iida, H; Takahashi, T T
2007-01-01
Light scalar-quarks \\phi (colored scalar particles or idealized diquarks) and their color-singlet hadronic states are studied with quenched SU(3)_c lattice QCD in terms of mass generation. We investigate ``scalar-quark mesons'' \\phi^\\dagger \\phi and ``scalar-quark baryons'' \\phi\\phi\\phi as the bound states of scalar-quarks \\phi. We also investigate the bound states of scalar-quarks \\phi and quarks \\psi, i.e., \\phi^\\dagger \\psi, \\psi\\psi\\phi and \\phi\\phi\\psi, which we name ``chimera hadrons''. All the new-type hadrons including \\phi are found to have a large mass due to large quantum corrections by gluons, even for zero bare scalar-quark mass m_\\phi=0 at a^{-1}\\sim 1{\\rm GeV}. We conjecture that all colored particles generally acquire a large effective mass due to dressed gluon effects.
Scalar-Quark Systems and Chimera Hadrons in SU(3)_c Lattice QCD
Iida, H; Takahashi, T T
2007-01-01
Light scalar-quarks \\phi (colored scalar particles or idealized diquarks) and their color-singlet hadronic states are studied with quenched SU(3)_c lattice QCD in terms of mass generation in strong interaction without chiral symmetry breaking. We investigate ``scalar-quark mesons'' \\phi^\\dagger \\phi and ``scalar-quark baryons'' \\phi\\phi\\phi which are the bound states of scalar-quarks \\phi. We also investigate the bound states of scalar-quarks \\phi and quarks \\psi, i.e., \\phi^\\dagger \\psi, \\psi\\psi\\phi and \\phi\\phi\\psi, which we name ``chimera hadrons''. All the new-type hadrons including \\phi are found to have a large mass even for zero bare scalar-quark mass m_\\phi=0 at a^{-1}\\simeq 1GeV. We find that the constituent scalar-quark and quark picture is satisfied for all the new-type hadrons. Namely, the mass of the new-type hadron composed of m \\phi's and n \\psi's, M_{{m}\\phi+{n}\\psi}, satisfies M_{{m}\\phi+{n}\\psi}\\simeq {m} M_\\phi +{n} M_\\psi, where M_\\phi and M_\\psi are the constituent scalar-quark and quark...
Quark Confinement in C-periodic Cylinders at Temperatures above $T_c$
Holland, K
1997-01-01
Due to the Gauss law, a single quark cannot exist in a periodic volume, while it can exist with C-periodic boundary conditions. In a C-periodic cylinder of cross section A = L_x L_y and length L_z >> L_x, L_y containing deconfined gluons, regions of different high temperature Z(3) phases are aligned along the z-direction, separated by deconfined- deconfined interfaces. In this geometry, the free energy of a single static quark diverges in proportion to L_z. Hence, paradoxically, the quark is confined, although the temperature T is larger than T_c. At T around T_c, the confined phase coexists with the three deconfined phases. The deconfined-deconfined interfaces can be completely or incompletely wet by the confined phase. The free energy of a quark behaves differently in these two cases. In contrast to claims in the literature, our results imply that deconfined-deconfined interfaces are not Euclidean artifacts, but have observable consequences in a system of hot gluons.
Tagging b and c quark events in e+e- collisions with neural networks
High purity samples of b quark events and, if possible, of c quark events are attempted to produce, and the width of Γ(Z0 → bb-bar) is measured. The different variables and the method to select the most discriminating variables are given. The physical results obtained with these methods are recalled, and new results are presented with variables connected with the impact parameter. Some neural networks used throughout this work and some results on c quark events selection are also presented. (K.A.) 9 refs.; 6 figs
A measurement of the weak axial couplings of the b- and c-quark
Elsen, E.; Ambrus, K.; Bethke, S.; Dieckmann, A.; Eckerlin, G.; Heintze, J.; Hellenbrand, K.H.; Komamiya, S.; Krogh, J. von; Rieseberg, H.; Schmitt, H. von der; Smolik, L.; Spitzer, J.; Wagner, A.; Zimmer, M. (Heidelberg Univ. (Germany, F.R.). Physikalisches Inst.); Allison, J.; Barlow, R.J.; Chrin, J.; Duerdoth, I.P.; Loebinger, F.K.; Macbeth, A.A.; Murphy, P.G.; Stephens, K. (Manchester Univ. (UK)); Bartel, W.; Felst, R.; Haidt, D.; Kado, H.; Knies, G.; Krehbiel, H.; Magnussen, N.; Meinke, R.; Naroska, B.; Olsson, J.; Ramcke, R.; Schmidt, D.; Steffen, P. (Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany, F.R.)); Bowdery, C.K.; Finch, A.J.; Foster, F.; Hughes, G.; Nye, J.M.; Walker, I.W. (Lancaster Univ. (UK)); Cartwright, S.L.; Clarke, D.; Marshall, R.; Middleton, R.P. (Rutherford Appleton Lab., Chilton (UK)); Greenshaw, T.; Hagemann, J.; Heinzelmann, G.; Kleinwort, C.; Kuhlen, M.; Ould-Saada, F.; Schneekloth, U.; Weber, G. (Hamburg Univ. (Germany, F.R.). 2. Inst. fuer; JADE Collaboration
1990-04-01
The forward backward charge asymmetries of the b and c quarks are measured with the JADE detector at PETRA at {radical}s=35 GeV and 44 GeV using both electrons and muons to tag the heavy quarks. At {radical}s=35 GeV, a simultaneous fit for the two asymmetries yields the result A{sub b}=-9.3{plus minus}5.2% (stat.) and A{sub c}=-9.6{plus minus}4.0% (stat.). A fit for the b-asymmetry alone gives A{sub b}=-11.6{plus minus}4.8% (stat.). The systematic errors are comparable with the statistical uncertainties. Combining the measurements at both energies and alternately constraining the weak coupling of the c and b quark to their Standard Model values (a{sub c}=1, a{sub b}=-1) increases the precision of the measurement of coupling constant of the other quark. Using this procedure a{sub b}=-0.72{plus minus}0.34 and a{sub c}=0.79{plus minus}0.40, where the numbers are corrected for Banti B-mixing and the errors include both statistical and systematic contributions. The mixing parameter for continuum banti b-production is determined to be {chi}=0.24{plus minus}0.12 if both heavy quark coupling constants are constrained to their values in the Standard Model. (orig.).
c, b-quark FB asymmetries by inclusive electrons
We have measured, with electron tagging, the forward-backward asymmetries of charm- and bottom-quark pair productions at = 58.01 GeV, based on 23,783 hadronic events selected from a data sample of 197 pb-1 taken with the TOPAZ detector at TRISTAN. The measured forward-backward asymmetries are AFBc = -0.49 ± 0.20(stat.) ± 0.08(sys.) and AFBb = -0.64 ± 0.35(stat.) ± 0.13(sys.), which are consistent with the standard model predictions. (author)
Jido, Daisuke
2016-01-01
The possibility to have diquark configuration in heavy baryons, such as Lambda_c and Lambda_b, is examined by a nonrelativistic potential model with a heavy quark and a light scalar diquark. Assuming that the Lambda_c and Lambda_b baryons are composed of the heavy quark and the scalar-isoscalar ud diquark, we solve the two-body Schrodinger equation with the Coulomb plus linear potential and obtain the energy spectra for the heavy baryons. Contrary to our expectation, it is found that the potential determined by the quarkonium spectra fails to reproduce the excitation spectra of the Lambda_c and Lambda_b in the quark-diquark picture, while the Lambda_c and Lambda_b spectra is reproduced with a half strength of the confinement string tension than for the quarkonium. The Xi_c excitation energy is also calculated and is found to be smaller than Lambda_c in the quark-diquark model. This is not consistent with the experimental observation. These puzzles should be solved when one takes the quark-diquark picture for ...
Quark (diquark) fragmentation in soft π-p interactions at P=40 GeV/c
The quark and diquark fragmentation into π+--, K0-mesons and Λ-hyperons in soft π-p-interactions at 40 GeV/c is studied. Fragmentation Dsup(πsup(+-)) (Xsub(F)) and invariant Fsup(πsup(+-)) (Xsub(F)) functions are compared with analogous data on ν(anti ν)p - interactions. It is shown that a good agreement exists in the region Xsub(F) > or approximately 0.15 for these different processes. The Xsub(E)-dependence of the quark and diquark fragmentation function for neutral kaons is similar to that in e+e- annihilation. The pickup probability of strange s(anti s) quark (lambda sub(s)) and diquark (lambda sub(qq)) relative to u(anti u) and d(anti d) quarks from the sea has been found to be equal to lambda sub(s)=0.17 and lambda sub(qq)=0.14+-0.03
Properties of Scalar-Quark Systems in SU(3)c Lattice QCD
Iida, Hideaki; Suganuma, Hideo
2008-01-01
We perform the first study for the bound states of colored scalar particles $\\phi$ ("scalar quarks") in terms of mass generation with quenched SU(3)$_c$ lattice QCD. We investigate the bound states of $\\phi$, $\\phi^\\dagger\\phi$ and $\\phi\\phi\\phi$ ("scalar-quark hadrons"), as well as the bound states of $\\phi$ and quarks $\\psi$, i.e., $\\phi^\\dagger\\psi$, $\\psi\\psi\\phi$ and $\\phi\\phi\\psi$ ("chimera hadrons"). All these new-type hadrons including $\\phi$ have a large mass of several GeV due to large quantum corrections by gluons, even for zero bare scalar-quark mass $m_\\phi=0$ at $a^{-1}\\sim 1{\\rm GeV}$. We find a similar $m_\\psi$-dependence between $\\phi^\\dagger\\psi$ and $\\phi\\phi\\psi$, which indicates their similar structure due to the large mass of $\\phi$. From this study, we conjecture that all colored particles generally acquire a large effective mass due to dressed gluons.
Hernández, A. E. Cárcamo; Mart'\\inez, R.; Ochoa, F.
2013-01-01
We take up again the study of the mass spectrum of the quark sector in a model with gauge symmetry $SU(3)_{c}\\otimes SU(3)_{L}\\otimes U(1)_{X}$ (331). In a special type II-like 331 model, we obtain specific zero-texture mass matrices for the quarks which predict four massless quarks ($u,c,d,s$) and two massive quarks ($b,t$) at the electroweak scale ($\\sim $ GeV). By considering the mixing between the SM quarks and new exotic quarks at large scales predicted by the model, we find that a third...
Hernández, A E Cárcamo; Ochoa, F
2013-01-01
We take up again the study of the mass spectrum of the quark sector in a model with gauge symmetry $SU(3)_{c}\\otimes SU(3)_{L}\\otimes U(1)_{X}$ (331). In a special type II-like 331 model, we obtain specific zero-texture mass matrices for the quarks which predict four massless quarks ($u,c,d,s$) and two massive quarks ($b,t$) at the electroweak scale ($\\sim $ GeV). By considering the mixing between the SM quarks and new exotic quarks at large scales predicted by the model, we find that a third quark (associated to the charm quark) acquires a mass. The remaining light quarks ($u,d,s$) get small masses ($\\sim$ MeV) via radiative corrections.
Rodionov, E. N.
1994-01-01
We build a model which is based on the assumption that the {\\bf c} and {\\bf s,b} quarks are excited states of {\\bf u} and {\\bf d} quarks. This model predicts the non-existence of the {\\bf top} quark and estimates the size of the quarks to be of order $10^{-7}$ fm.
Abreu, P; Adye, T; Adzic, P; Ajinenko, I; Albrecht, Z; Alderweireld, T; Alekseev, G D; Alemany, R; Allmendinger, T; Allport, P P; Almehed, S; Amaldi, Ugo; Amapane, N; Amato, S; Anassontzis, E G; Andersson, P; Andreazza, A; Andringa, S; Antilogus, P; Apel, W D; Arnoud, Y; Åsman, B; Augustin, J E; Augustinus, A; Baillon, Paul; Bambade, P; Barão, F; Barbiellini, Guido; Barbier, R; Bardin, Dimitri Yuri; Barker, G; Baroncelli, A; Battaglia, Marco; Baubillier, M; Becks, K H; Begalli, M; Behrmann, A; Beillière, P; Belokopytov, Yu A; Benekos, N C; Benvenuti, Alberto C; Bérat, C; Berggren, M; Bertini, D; Bertrand, D; Besançon, M; Bigi, M; Bilenky, S M; Bizouard, M A; Bloch, D; Blom, H M; Bonesini, M; Bonivento, W; Boonekamp, M; Booth, P S L; Borgland, A W; Borisov, G; Bosio, C; Botner, O; Boudinov, E; Bouquet, B; Bourdarios, C; Bowcock, T J V; Boyko, I; Bozovic, I; Bozzo, M; Branchini, P; Brenke, T; Brenner, R A; Brückman, P; Brunet, J M; Bugge, L; Buran, T; Burgsmüller, T; Buschbeck, Brigitte; Buschmann, P; Cabrera, S; Caccia, M; Calvi, M; Camporesi, T; Canale, V; Carena, F; Carroll, L; Caso, Carlo; Castillo-Gimenez, M V; Cattai, A; Cavallo, F R; Chabaud, V; Charpentier, P; Chaussard, L; Checchia, P; Chelkov, G A; Chierici, R; Shlyapnikov, P; Chochula, P; Chorowicz, V; Chudoba, J; Cieslik, K; Collins, P; Contri, R; Cortina, E; Cosme, G; Cossutti, F; Cowell, J H; Crawley, H B; Crennell, D J; Crépé, S; Crosetti, G; Cuevas-Maestro, J; Czellar, S; Davenport, Martyn; Da Silva, W; Deghorain, A; Della Ricca, G; Delpierre, P A; Demaria, N; De Angelis, A; de Boer, Wim; De Clercq, C; De Lotto, B; De Min, A; De Paula, L S; Dijkstra, H; Di Ciaccio, Lucia; Dolbeau, J; Doroba, K; Dracos, M; Drees, J; Dris, M; Duperrin, A; Durand, J D; Eigen, G; Ekelöf, T J C; Ekspong, Gösta; Ellert, M; Elsing, M; Engel, J P; Erzen, B; Espirito-Santo, M C; Falk, E; Fanourakis, G K; Fassouliotis, D; Fayot, J; Feindt, Michael; Ferrari, P; Ferrer, A; Ferrer-Ribas, E; Ferro, F; Fichet, S; Firestone, A; Flagmeyer, U; Föth, H; Fokitis, E; Fontanelli, F; Franek, B J; Frodesen, A G; Frühwirth, R; Fulda-Quenzer, F; Fuster, J A; Galloni, A; Gamba, D; Gamblin, S; Gandelman, M; García, C; Gaspar, C; Gaspar, M; Gasparini, U; Gavillet, P; Gazis, E N; Gelé, D; Gerdyukov, L N; Ghodbane, N; Gil, I; Glege, F; Gokieli, R; Golob, B; Gómez-Ceballos, G; Gonçalves, P; González-Caballero, I; Gopal, Gian P; Gorn, L; Górski, M; Guz, Yu; Gracco, Valerio; Grahl, J; Graziani, E; Green, C; Grimm, H J; Gris, P; Grosdidier, G; Grzelak, K; Günther, M; Guy, J; Hahn, F; Hahn, S; Haider, S; Hallgren, A; Hamacher, K; Hansen, J; Harris, F J; Hedberg, V; Heising, S; Hernández, J J; Herquet, P; Herr, H; Hessing, T L; Heuser, J M; Higón, E; Holmgren, S O; Holt, P J; Hoorelbeke, S; Houlden, M A; Hrubec, Josef; Huet, K; Hughes, G J; Hultqvist, K; Jackson, J N; Jacobsson, R; Jalocha, P; Janik, R; Jarlskog, C; Jarlskog, G; Jarry, P; Jean-Marie, B; Johansson, E K; Jönsson, P E; Joram, C; Juillot, P; Kapusta, F; Karafasoulis, K; Katsanevas, S; Katsoufis, E C; Keränen, R; Kersevan, Borut P; Khomenko, B A; Khovanskii, N N; Kiiskinen, A P; King, B J; Kinvig, A; Kjaer, N J; Klapp, O; Klein, H; Kluit, P M; Kokkinias, P; Koratzinos, M; Kostyukhin, V; Kourkoumelis, C; Kuznetsov, O; Kriznic, E; Krstic, P S; Krumshtein, Z; Kubinec, P; Kurowska, J; Kurvinen, K L; Lamsa, J; Lane, D W; Langefeld, P; Lapin, V; Laugier, J P; Lauhakangas, R; Leder, Gerhard; Ledroit, F; Lefébure, V; Leinonen, L; Leisos, A; Leitner, R; Lemonne, J; Lenzen, Georg; Lepeltier, V; Lesiak, T; Lethuillier, M; Libby, J; Liko, D; Lipniacka, A; Lippi, I; Lörstad, B; Loken, J G; Lopes, J H; López, J M; López-Fernandez, R; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J N; Mahon, J R; Maio, A; Malek, A; Malmgren, T G M; Maltezos, S; Malychev, V; Mandl, F; Marco, J; Marco, R P; Maréchal, B; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Martínez-Rivero, C; Martínez-Vidal, F; Martí i García, S; Masik, J; Mastroyiannopoulos, N; Matorras, F; Matteuzzi, C; Matthiae, Giorgio; Mazzucato, F; Mazzucato, M; McCubbin, M L; McKay, R; McNulty, R; McPherson, G; Meroni, C; Meyer, W T; Myagkov, A; Migliore, E; Mirabito, L; Mitaroff, Winfried A; Mjörnmark, U; Moa, T; Moch, M; Møller, R; Mönig, K; Monge, M R; Moreau, X; Morettini, P; Morton, G A; Müller, U; Münich, K; Mulders, M; Mulet-Marquis, C; Muresan, R; Murray, W J; Muryn, B; Myatt, Gerald; Myklebust, T; Naraghi, F; Nassiakou, M; Navarria, Francesco Luigi; Navas, S; Nawrocki, K; Negri, P; Némécek, S; Neufeld, N; Neumeister, N; Nicolaidou, R; Nielsen, B S; Nikolenko, M; Nomokonov, V P; Normand, Ainsley; Nygren, A; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, Risto; Orazi, G; Österberg, K; Ouraou, A; Paganoni, M; Paiano, S; Pain, R; Paiva, R; Palacios, J; Palka, H; Papadopoulou, T D; Papageorgiou, K; Pape, L; Parkes, C; Parodi, F; Parzefall, U; Passeri, A; Passon, O; Pegoraro, M; Peralta, L; Pernicka, Manfred; Perrotta, A; Petridou, C; Petrolini, A; Phillips, H T; Pierre, F; Pimenta, M; Piotto, E; Podobnik, T; Pol, M E; Polok, G; Poropat, P; Pozdnyakov, V; Privitera, P; Pukhaeva, N; Pullia, Antonio; Radojicic, D; Ragazzi, S; Rahmani, H; Ratoff, P N; Read, A L; Rebecchi, P; Redaelli, N G; Regler, Meinhard; Reid, D; Reinhardt, R; Renton, P B; Resvanis, L K; Richard, F; Rídky, J; Rinaudo, G; Røhne, O M; Romero, A; Ronchese, P; Rosenberg, E I; Rosinsky, P; Roudeau, Patrick; Rovelli, T; Royon, C; Ruhlmann-Kleider, V; Ruiz, A; Saarikko, H; Sacquin, Yu; Sadovskii, A; Sajot, G; Salt, J; Sampsonidis, D; Sannino, M; Schneider, H; Schwemling, P; Schwering, B; Schwickerath, U; Schyns, M A E; Scuri, F; Seager, P; Sedykh, Yu; Segar, A M; Sekulin, R L; Shellard, R C; Sheridan, A; Siebel, M; Simard, L C; Simonetto, F; Sissakian, A N; Smadja, G; Smirnova, O G; Smith, G R; Sokolov, A; Sopczak, André; Sosnowski, R; Spassoff, Tz; Spiriti, E; Sponholz, P; Squarcia, S; Stanescu, C; Stanic, S; Stevenson, K; Stocchi, A; Strauss, J; Strub, R; Stugu, B; Szczekowski, M; Szeptycka, M; Tabarelli de Fatis, T; Chikilev, O G; Tegenfeldt, F; Terranova, F; Thomas, J; Timmermans, J; Tinti, N; Tkatchev, L G; Todorova-Nová, S; Tomaradze, A G; Tomé, B; Tonazzo, A; Tortora, L; Tranströmer, G; Treille, D; Tristram, G; Trochimczuk, M; Troncon, C; Tsirou, A L; Turluer, M L; Tyapkin, I A; Tzamarias, S; Ullaland, O; Uvarov, V; Valenti, G; Vallazza, E; Van der Velde, C; van Apeldoorn, G W; van Dam, P; Van Doninck, W K; Van Eldik, J; Van Lysebetten, A; Van Remortel, N; Van Vulpen, I B; Vassilopoulos, N; Vegni, G; Ventura, L; Venus, W A; Verbeure, F; Verlato, M; Vertogradov, L S; Verzi, V; Vilanova, D; Vitale, L; Vlasov, E; Vodopyanov, A S; Vollmer, C F; Voulgaris, G; Vrba, V; Wahlen, H; Walck, C; Weiser, C; Wicke, D; Wickens, J H; Wilkinson, G R; Winter, M; Witek, M; Wolf, G; Yi, J; Yushchenko, O P; Zalewska-Bak, A; Zalewski, Piotr; Zavrtanik, D; Zevgolatakos, E; Zimin, N I; Zucchelli, G C; Zumerle, G
2000-01-01
The partial decay width $R_c$ of the $Z$ into $c\\bar{c}$ quark pair and the number of charm quarks $n_c$ per $b$ decay are measured with the DELPHI detector at \\mbox{LEP 1}. Particle identification provides clear $D^0$, $D^+$, $D_s^+$ and $\\Lambda_c^+$ signatures. The charm hadron production rate is measured in each channel by a fit to the scaled energy, impact parameter information and the invariant mass spectrum. Two measurements of $R_c$ are presented, from the $D^{*+}$ production rate and from the overall charm counting, including strange charm baryon production, in $c\\bar{c}$ events. The multiplicity $n_c$, which includes hidden $c\\bar{c}$ and strange charm baryon production, is inferred from the charm counting in $b\\bar{b}$ events. The final results are $R_c = 0.1665 \\pm 0.0095$ and $n_c = 1.166 \\pm 0.086$.
Dowdall, R J; Davies, C T H; Horgan, R R; Monahan, C J; Shigemitsu, J
2013-05-31
We present the first lattice QCD calculation of the decay constants f(B) and f(B(s)) with physical light quark masses. We use configurations generated by the MILC Collaboration including the effect of u, d, s, and c highly improved staggered quarks in the sea at three lattice spacings and with three u/d quark mass values going down to the physical value. We use improved nonrelativistic QCD (NRQCD) for the valence b quarks. Our results are f(B)=0.186(4) GeV, f(B(s))=0.224(4) GeV, f(B(s))/f(B)=1.205(7), and M(B(s))-M(B)=85(2) MeV, superseding earlier results with NRQCD b quarks. We discuss the implications of our results for the standard model rates for B((s))→μ(+)μ(-) and B→τν. PMID:23767714
Quark-gluon plasma at finite baryon density: A large-N/sub c/ approach
A simple model for the quark-gluon plasma with a nonzero baryon number B is developed in a microcanonical (i.e., fixed B) approach. The model exhibits features which one expects will emerge from a nonperturbative treatment of QCD. We show the existence of a critical chemical potential μ/sub c/ such that, for T>0, physical properties are unaffected by chemical potentials μ when chemical bondμchemical bond<μ/sub c/. μ/sub c/ therefore resembles a mass gap
Quark-gluon plasma at finite baryon density: A large-N/sub c/ approach
Azakov, S.I.; Salomonson, P.; Skagerstam, B.h.
1987-10-01
A simple model for the quark-gluon plasma with a nonzero baryon number B is developed in a microcanonical (i.e., fixed B) approach. The model exhibits features which one expects will emerge from a nonperturbative treatment of QCD. We show the existence of a critical chemical potential ..mu../sub c/ such that, for T>0, physical properties are unaffected by chemical potentials ..mu.. when chemically bond..mu..chemically bond<..mu../sub c/. ..mu../sub c/ therefore resembles a mass gap.
Monteiro, Antony Prakash; Kumar, K B Vijaya
2016-01-01
The complete spectrum of $c\\bar{b}$ states is obtained in a phenomenological non relativistic quark model(NRQM), which consists of a confinement potential and one gluon exchange potential (OGEP) as effective quark - antiquark potential. We make predictions for the radiative decay (E1 and M1) widths and weak decay widths of $c\\bar{b}$ states in the framework of NRQM formalism.
Form factors of ηc in light-front quark model
We study the form factors of the ηc meson in the light-front quark model. We explicitly show that the transition form factor of ηc → γ*γ as a function of the momentum transfer is consistent with the experimental data by the BaBar collaboration, while the decay constant of ηc is found to be fηc = 230.5+52.2-61.0 and 303.6+115.2-116.4 MeV for ηc ∝ c anti c by using two ηc → γγ decay widths of 5.3 ± 0.5 and 7.2 ± 2.1 keV, given by Particle Data Group and Lattice QCD calculation, respectively. (orig.)
Form factors of {eta}{sub c} in light-front quark model
Geng, Chao-Qiang [Chongqing University of Posts and Telecommunications, College of Mathematics and Physics, Chongqing (China); National Center for Theoretical Sciences, Physics Division, Hsinchu (China); National Tsing Hua University, Department of Physics, Hsinchu (China); Lih, Chong-Chung [Shu-Zen College of Medicine and Management, Department of Optometry, Kaohsiung Hsien (China); National Center for Theoretical Sciences, Physics Division, Hsinchu (China); National Tsing Hua University, Department of Physics, Hsinchu (China)
2013-08-15
We study the form factors of the {eta}{sub c} meson in the light-front quark model. We explicitly show that the transition form factor of {eta}{sub c} {yields} {gamma}{sup *}{gamma} as a function of the momentum transfer is consistent with the experimental data by the BaBar collaboration, while the decay constant of {eta}{sub c} is found to be f{sub {eta}{sub c}} = 230.5{sup +52.2}{sub -61.0} and 303.6{sup +115.2}{sub -116.4} MeV for {eta}{sub c} {proportional_to} c anti c by using two {eta}{sub c} {yields} {gamma}{gamma} decay widths of 5.3 {+-} 0.5 and 7.2 {+-} 2.1 keV, given by Particle Data Group and Lattice QCD calculation, respectively. (orig.)
Compatibility of Quark and Resonant Picture Excited Baryon Multiplets in 1/N_c
Cohen, T D; Cohen, Thomas D.; Lebed, Richard F.
2003-01-01
We demonstrate that the two major complementary pictures of large N_c baryon resonances--as single-quark orbital excitations about a closed-shell core [giving SU(2N_F) x O(3) multiplets], and as resonances in meson-baryon scattering amplitudes--are completely compatible in a specific sense: Both pictures give rise to a set of multiplets of degenerate states, for which any complete spin-flavor multiplet within one picture fills the quantum numbers of complete multiplets in the other picture. This result is demonstrated by: (i) straightforward computation of the lowest multiplets in both pictures; (ii) a study of the nature of quark excitations in a hedgehog picture; (iii) direct group-theoretical comparison of the constraints in the two pictures.
Heavy quark symmetry and weak decays of the $b$-baryons in pentaquarks with a $c\\bar{c}$ component
Ali, Ahmed; Aslam, M Jamil; Rehman, Abdur
2016-01-01
The discovery of the baryonic states $P_c^+(4380)$ and $P_c^+(4450)$ by the LHCb collaboration has evoked a lot of theoretical interest. These states have the minimal quark content $c \\bar{c} u u d$. Interpreted as hidden charm diquark-diquark-antiquark baryons, the assigned spin and angular momentum quantum numbers are $P_c^+(4380)= \\{\\bar{c} [cu]_{s=1} [ud]_{s=1}; L_{\\mathcal{P}}=0, J^{\\rm P}=\\frac{3}{2}^- \\}$ and $P_c^+(4450)= \\{\\bar{c} [cu]_{s=1} [ud]_{s=0}; L_{\\mathcal{P}}=1, J^{\\rm P}=\\frac{5}{2}^+ \\}$, where $s=0,1$ are the spins of the diquarks and $L_{\\mathcal{P}}=0,1$ are the orbital angular momentum quantum numbers of the pentaquarks. We point out that heavy quark symmetry allows only the higher mass pentaquark state $P_c^+(4450)$ having $[ud]_{s=0}$ to be produced in $\\Lambda_b^0$ decays, whereas the lower mass state $P_c^+(4380)$ having $[ud]_{s=1}$ is disfavored. Pentaquark spectrum is rich enough to accommodate a $J^P=\\frac{3}{2}^-$ state, which has the correct light diquark spin $\\{\\bar{c} [cu...
Colorless quark-gluon gas in the limit of large N sub c
Azakov, S.I.
1989-03-01
A quark-gluon gas in a finite volume with global internal symmetry group SU(N{sub c}) on the states of which the condition of being colorless is imposed is studied in the limit N{sub c} {yields} {infinity}. It is shown that without allowance for the conservation law of the baryon charge this system undergoes a phase transition of the third kind. However, in the more realistic situation in which this conservation law is taken into account there is no phase transition.
Numerical simulation of QCD with u, d, s and c quarks in the twisted-mass Wilson formulation
A first study of numerical Monte Carlo simulations with two quark doublets, a mass-degenerate one and a mass-split one, interpreted as u, d, s and c quarks, is carried out in the framework of the twisted mass Wilson lattice formulation. Tuning the bare parameters of this theory is explored on 123.24 and 163.32 lattices at lattice spacings a ≅0.20 fm and a ≅0.15 fm, respectively. (Orig.)
Baryogenesis of the Universe in cSMCS Model plus Iso-Doublet Vector Quark
Darvishi, Neda
2016-01-01
CP violation of the SM is insufficient to explain the baryon asymmetry in the universe and therefore an additional source of CP violation is needed. Here the extension of the SM by a neutral complex scalar singlet with a nonzero vacuum expectation value (cSMCS) plus a heavy vector quark pair is considered. This model offers the spontaneous CP violation and proper description in the baryogenesis, it leads strong enough first-order electro-weak phase transition to suppress the baryon-violating sphaleron process.
Matagne, N
2011-01-01
We show that the two complementary pictures of large $N_c$ baryons - the single-quark orbital excitation about a symmetric core and the meson-nucleon resonance -- are compatible for $\\ell$ = 3 SU(4) baryons. The proof is based on a simple Hamiltonian including operators up to order $\\mathcal{O}(N^0_c)$ used previously in the literature for $\\ell$ = 1.
Pentaquark Θ+, constituent quark structures, and prediction of charmed Θc0 and bottomed Θb+
The newly observed Θ+ resonance is believed to be a pentaquark with the constituent quarks uudds-bar. There are a few options for the constituent quark structure. Some advocate diquark-diquark-antiquark (ud)-(ud)-s-bar while others favor diquark-triquark (ud)-(uds-bar) structure. We use the color-spin hyperfine interaction to examine the energy levels of these structures, and we find that the diquark-diquark-antiquark structure is slightly favored. We proceed to write down the flavor triplet and antisextet of the charmed or bottomed exotic baryons with internal qqqqQ-bar quarks. We also estimate the mass of Θc0 and Θb+
Density of Saturated Nuclear Matter at Large $N_{c}$ and Heavy Quark Mass Limits
Adhikari, Prabal; Datta, Ishaun
2013-01-01
We exhibit the existence of stable, saturated nuclear matter in the large $N_{c}$ and heavy quark mass limits of QCD. In this limit, baryons (with the same spin flavor structure) interact at leading order in $N_{c}$ via a repulsive interaction due to the Pauli exclusion principle and at subleading order in $1/N_c$ via the exchange of glueballs. Assuming that the lightest glueball is a scalar, which implies that the subleading baryon interaction is attractive, we find that nuclear matter saturates since the subleading attractive interaction is longer ranged than the leading order repulsive one. We find that the saturated matter is in the form of a crystal with either a face-centered cubic or a hexagonal-close-packed symmetry with baryon densities of $\\mathcal{O}((\\, \\tilde{\\alpha}_{s} m_q (\\ln (N_{c}m_{q}\\Lambda_{\\textrm{QCD}}^{-1}))^{-1})^3 )$. Remarkably, the leading order expression for the density of saturated nuclear matter is independent of the lighest glueball mass and scalar-glueball-baryon coupling in...
Dynamical Color Correlations in a $SU(2)_c$ Quark Exchange Model of Nuclear Matter
Gardner, S; Piekarewicz, J
1994-01-01
The quark exchange model is a simple realization of an adiabatic approximation to the strong-coupling limit of Quantum Chromodynamics (QCD): the quarks always coalesce into the lowest energy set of flux tubes. Nuclear matter is thus modeled in terms of its quarks. We wish to study the correlations imposed by total wavefunction antisymmetry when color degrees of freedom are included. To begin with, we have considered one-dimensional matter with a $SU(2)$ color internal degree of freedom only. We proceed by constructing a totally antisymmetric, color singlet {\\it Ansatz} characterized by a variational parameter $\\lambda$ (which describes the length scale over which two quarks in the system are clustered into hadrons) and by performing a variational Monte Carlo calculation of the energy to optimize $\\lambda$ for a fixed density. We calculate the $q-q$ correlation function as well, and discuss the qualitative differences between the system at low and high density.
Gilani, Amjad Hussain Shah
2005-01-01
There are eight quarks in each family and there are three families of quarks i.e. c, b, t. Also, we propose similar structure for leptons. The nature of strong force is named as `third order electroweak'.
Abreu, P; Adzic, P; Albrecht, Z; Alderweireld, T; Alekseev, G D; Alemany, R; Allmendinger, T; Allport, P P; Almehed, S; Amaldi, Ugo; Amato, S; Anassontzis, E G; Andersson, P; Andreazza, A; Andringa, S; Antilogus, P; Apel, W D; Arnoud, Y; Åsman, B; Augustin, J E; Augustinus, A; Baillon, Paul; Bambade, P; Barão, F; Barbiellini, Guido; Barbier, R; Bardin, Dimitri Yuri; Barker, G; Baroncelli, A; Battaglia, Marco; Baubillier, M; Becks, K H; Begalli, M; Beillière, P; Belokopytov, Yu A; Belous, K S; Benvenuti, Alberto C; Bérat, C; Berggren, M; Bertini, D; Bertrand, D; Besançon, M; Bianchi, F; Bigi, M; Bilenky, S M; Bizouard, M A; Bloch, D; Blom, H M; Bonesini, M; Bonivento, W; Boonekamp, M; Booth, P S L; Borgland, A W; Borisov, G; Bosio, C; Botner, O; Boudinov, E; Bouquet, B; Bourdarios, C; Bowcock, T J V; Boyko, I; Bozovic, I; Bozzo, M; Branchini, P; Brenke, T; Brenner, R A; Brückman, P; Brunet, J M; Bugge, L; Buran, T; Burgsmüller, T; Buschmann, P; Cabrera, S; Caccia, M; Calvi, M; Camporesi, T; Canale, V; Carena, F; Carroll, L; Caso, Carlo; Castillo-Gimenez, M V; Cattai, A; Cavallo, F R; Chabaud, V; Chapkin, M M; Charpentier, P; Chaussard, L; Checchia, P; Chelkov, G A; Chierici, R; Chliapnikov, P V; Chochula, P; Chorowicz, V; Chudoba, J; Cieslik, K; Collins, P; Contri, R; Cortina, E; Cosme, G; Cossutti, F; Cowell, J H; Crawley, H B; Crennell, D J; Crépé, S; Crosetti, G; Cuevas-Maestro, J; Czellar, S; Davenport, Martyn; Da Silva, W; Deghorain, A; Della Ricca, G; Delpierre, P A; Demaria, N; De Angelis, A; de Boer, Wim; De Brabandere, S; De Clercq, C; De Lotto, B; De Min, A; De Paula, L S; Dijkstra, H; Di Ciaccio, Lucia; Dolbeau, J; Doroba, K; Dracos, M; Drees, J; Dris, M; Duperrin, A; Durand, J D; Eigen, G; Ekelöf, T J C; Ekspong, Gösta; Ellert, M; Elsing, M; Engel, J P; Erzen, B; Espirito-Santo, M C; Falk, E; Fanourakis, G K; Fassouliotis, D; Fayot, J; Feindt, Michael; Fenyuk, A; Ferrari, P; Ferrer, A; Ferrer-Ribas, E; Fichet, S; Firestone, A; Flagmeyer, U; Föth, H; Fokitis, E; Fontanelli, F; Franek, B J; Frodesen, A G; Frühwirth, R; Fulda-Quenzer, F; Fuster, J A; Galloni, A; Gamba, D; Gamblin, S; Gandelman, M; García, C; Gaspar, C; Gaspar, M; Gasparini, U; Gavillet, P; Gazis, E N; Gelé, D; Ghodbane, N; Gil, I; Glege, F; Gokieli, R; Golob, B; Gómez-Ceballos, G; Gonçalves, P; González-Caballero, I; Gopal, Gian P; Gorn, L; Górski, M; Guz, Yu; Gracco, Valerio; Grahl, J; Graziani, E; Green, C; Grimm, H J; Gris, P; Grosdidier, G; Grzelak, K; Günther, M; Guy, J; Hahn, F; Hahn, S; Haider, S; Hallgren, A; Hamacher, K; Hansen, J; Harris, F J; Hedberg, V; Heising, S; Hernández, J J; Herquet, P; Herr, H; Hessing, T L; Heuser, J M; Higón, E; Holmgren, S O; Holt, P J; Hoorelbeke, S; Houlden, M A; Hrubec, Josef; Huet, K; Hughes, G J; Hultqvist, K; Jackson, J N; Jacobsson, R; Jalocha, P; Janik, R; Jarlskog, C; Jarlskog, G; Jarry, P; Jean-Marie, B; Johansson, E K; Jönsson, P E; Joram, C; Juillot, P; Kapusta, F; Karafasoulis, K; Katsanevas, S; Katsoufis, E C; Keränen, R; Kersevan, Borut P; Khomenko, B A; Khovanskii, N N; Kiiskinen, A P; King, B J; Kinvig, A; Kjaer, N J; Klapp, O; Klein, H; Kluit, P M; Kokkinias, P; Koratzinos, M; Kostyukhin, V; Kourkoumelis, C; Kuznetsov, O; Krammer, Manfred; Kriznic, E; Krstic, J; Krumshtein, Z; Kubinec, P; Kurowska, J; Kurvinen, K L; Lamsa, J; Lane, D W; Langefeld, P; Lapin, V; Laugier, J P; Lauhakangas, R; Leder, Gerhard; Ledroit, F; Lefébure, V; Leinonen, L; Leisos, A; Leitner, R; Lemonne, J; Lenzen, Georg; Lepeltier, V; Lesiak, T; Lethuillier, M; Libby, J; Liko, D; Lipniacka, A; Lippi, I; Lörstad, B; Loken, J G; Lopes, J H; López, J M; López-Fernandez, R; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J N; Mahon, J R; Maio, A; Malek, A; Malmgren, T G M; Malychev, V; Mandl, F; Marco, J; Marco, R P; Maréchal, B; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Martínez-Rivero, C; Martínez-Vidal, F; Martí i García, S; Mastroyiannopoulos, N; Matorras, F; Matteuzzi, C; Matthiae, Giorgio; Masik, J; Mazzucato, F; Mazzucato, M; McCubbin, M L; McKay, R; McNulty, R; McPherson, G; Meroni, C; Meyer, W T; Migliore, E; Mirabito, L; Mitaroff, Winfried A; Mjörnmark, U; Moa, T; Moch, M; Møller, R; Mönig, K; Monge, M R; Moreau, X; Morettini, P; Morton, G A; Müller, U; Münich, K; Mulders, M; Mulet-Marquis, C; Muresan, R; Murray, W J; Muryn, B; Myatt, Gerald; Myklebust, T; Naraghi, F; Navarria, Francesco Luigi; Navas, S; Nawrocki, K; Negri, P; Némécek, S; Neufeld, N; Neumeister, N; Nicolaidou, R; Nielsen, B S; Nikolenko, M; Nomokonov, V P; Normand, Ainsley; Nygren, A; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, Risto; Orazi, G; Österberg, K; Ouraou, A; Paganoni, M; Paiano, S; Pain, R; Paiva, R; Palacios, J; Palka, H; Papadopoulou, T D; Papageorgiou, K; Pape, L; Parkes, C; Parodi, F; Parzefall, U; Passeri, A; Passon, O; Pegoraro, M; Peralta, L; Pernicka, Manfred; Perrotta, A; Petridou, C; Petrolini, A; Phillips, H T; Pierre, F; Pimenta, M; Piotto, E; Podobnik, T; Pol, M E; Polok, G; Poropat, P; Pozdnyakov, V; Privitera, P; Pukhaeva, N; Pullia, Antonio; Radojicic, D; Ragazzi, S; Rahmani, H; Rakoczy, D; Ratoff, P N; Read, A L; Rebecchi, P; Redaelli, N G; Regler, Meinhard; Reid, D; Reinhardt, R; Renton, P B; Resvanis, L K; Richard, F; Rídky, J; Rinaudo, G; Røhne, O M; Romero, A; Ronchese, P; Rosenberg, E I; Rosinsky, P; Roudeau, Patrick; Rovelli, T; Royon, C; Ruhlmann-Kleider, V; Ruiz, A; Saarikko, H; Sacquin, Yu; Sadovskii, A; Sajot, G; Salt, J; Sampsonidis, D; Sannino, M; Schneider, H; Schwemling, P; Schwickerath, U; Schyns, M A E; Scuri, F; Seager, P; Sedykh, Yu; Segar, A M; Sekulin, R L; Shellard, R C; Sheridan, A; Siebel, M; Simard, L C; Simonetto, F; Sissakian, A N; Smadja, G; Smirnov, N; Smirnova, O G; Smith, G R; Sopczak, André; Sosnowski, R; Spassoff, Tz; Spiriti, E; Sponholz, P; Squarcia, S; Stampfer, D; Stanescu, C; Stanic, S; Stevenson, K; Stocchi, A; Strauss, J; Strub, R; Stugu, B; Szczekowski, M; Szeptycka, M; Tabarelli de Fatis, T; Tegenfeldt, F; Terranova, F; Thomas, J; Timmermans, J; Tinti, N; Tkatchev, L G; Todorova-Nová, S; Tomaradze, A G; Tomé, B; Tonazzo, A; Tortora, L; Tranströmer, G; Treille, D; Tristram, G; Trochimczuk, M; Troncon, C; Tsirou, A L; Turluer, M L; Tyapkin, I A; Tzamarias, S; Überschär, B; Ullaland, O; Uvarov, V; Valenti, G; Vallazza, E; van Apeldoorn, G W; van Dam, P; Van Doninck, W K; Van Eldik, J; Van Lysebetten, A; Van Vulpen, I B; Vassilopoulos, N; Vegni, G; Ventura, L; Venus, W A; Verbeure, F; Verlato, M; Vertogradov, L S; Verzi, V; Vilanova, D; Vitale, L; Vlasov, E; Vodopyanov, A S; Vollmer, C F; Voulgaris, G; Vrba, V; Wahlen, H; Walck, C; Weiser, C; Wicke, D; Wickens, J H; Wilkinson, G R; Winter, M; Witek, M; Wolf, G; Yi, J; Yushchenko, O P; Zaitsev, A; Zalewska-Bak, A; Zalewski, Piotr; Zavrtanik, D; Zevgolatakos, E; Zimin, N I; Zucchelli, G C; Zumerle, G
1999-01-01
A measurement of the forward--backward asymmetry of $e^{+}e^{-} \\to c\\bar{c}$ and $e^{+}e^{-} \\to b\\bar{b}$ on the $Z$ resonance is performed using about 3.5 million hadronic $Z$ decays collected by the DELPHI detector at LEP in the years 1992 to 1995. The heavy quark is tagged by the exclusive reconstruction of several $D$ meson decay modes. The forward--backward asymmetries for $c$ and $b$ quarks at the $Z$ resonance are determined to be: \\[ \\renewcommand{\\arraystretch}{1.6} \\begin{array}{rcr@{\\!\\!\\;\\,}l} \\Afbc(\\sqrt{s} = 91.235 \\, {\\rm GeV}) &=& &0.0659\\,\\, \\pm\\,\\, 0.0094\\, (stat)\\,\\, \\pm\\,\\, 0.0035\\, (syst) \\\\ \\Afbb (\\sqrt{s} = 91.235 \\, {\\rm GeV}) &=& &0.0762\\,\\, \\pm\\,\\, 0.0194\\, (stat)\\,\\, \\pm\\,\\, 0.0085\\, (syst) \\\\ \\Afbc(\\sqrt{s} = 89.434\\, {\\rm GeV}) &=&-&0.0496\\,\\, \\pm\\,\\, 0.0368\\, (stat)\\,\\, \\pm\\,\\, 0.0053\\, (syst) \\\\ \\Afbb(\\sqrt{s} = 89.434\\, {\\rm GeV}) &=& &0.0567\\,\\, \\pm\\,\\, 0.0756\\, (stat)\\,\\, \\pm\\,\\ 0.0117\\, (syst) \\\\ \\Afbc(\\sqrt{s} = 92.990\\, {\\r...
The mixed quark-gluon condensate from an effective quark-quark interaction
Meissner, Thomas
1997-01-01
We exhibit the method for obtaining non perturbative quark and gluonic vacuum condensates from a model truncation of QCD. The truncation allows for a phenomenological description of the quark-quark interaction in a framework which maintains all global symmetries of QCD and allows an 1/N_c expansion. Within this approach the functional integration over the gluon fields can be performed and therefore any gluonic vacuum observable can be expressed in terms of a quark operator and the gluon propa...
The most important particle accelerators that can contribute to quark production efforts are overviewed. The history of the discovery of quark particles is outlined. The so-called y-particles were found with 9460 MeV mass in 1977, the new particle was called beauty quark. The tau-particles were discovered in 1975. The most important features of the new generation of particles, the quark family are discussed. (R.P.)
Samart, Daris; Yan, Yupeng
2016-01-01
We construct, in the work, chiral $SU(3)$ Lagrangian with $D$ mesons of spin $J^P=0^-$ and $J^P=1^-$ and charmed baryons of spin $J^P=1/2^+$ and $J^P=3/2^+$. There are 42 leading two-body counter-terms involving two charmed baryon fields and two $D$ meson fields in the constructed Lagrangian. The heavy-quark spin symmetry leads to 35 sum rules while the large-$N_c$ operator analysis predicts 29 ones at the next-to leading order of $1/N_c$ expansion. The combination of the sum rules from both the heavy-quark symmetry and the large-$N_c$ analysis results in 38 independent sum rules which reduces the number of free parameters in the chiral Lagrangian down to 4 only. This is a remarkable result demonstrating the consistency of the heavy-quark symmetry and large-$N_c$ operator analysis.
Jido, Daisuke; Sakashita, Minori
2016-08-01
The possibility of having a diquark configuration in heavy baryons, such as Λ and Λ, is examined by a nonrelativistic potential model with a heavy quark and a light scalar diquark. Assuming that the Λ and Λ baryons are composed of the heavy quark and the point-like scalar-isoscalar ud diquark, we solve the two-body Schrödinger equation with the Coulomb plus linear potential and obtain the energy spectra for the heavy baryons. Contrary to our expectation, it is found that the potential determined by the quarkonium spectra fails to reproduce the excitation spectra of the Λ and Λ in the quark-diquark picture, while the Λ and Λ spectra are reproduced with half the strength of the confinement string tension than for the quarkonium. The finite size effect of the diquark is also examined and it is found that the introduction of a finite size diquark would resolve the failure of the spectrum reproduction. The Ξ excitation energy is also calculated and is found to be smaller than Λ in the quark-diquark model. This is not consistent with experimental observations.
Multileptons from heavy quarks
The paper is concerned with a brief look at the various multilepton signals that are expected at p-barp colliders from the production and cascade decay of top quarks, plus the backgrounds from b and c production. (author)
Experimental results which proved the reality of quarks are reviewed along with further experiments broadening the representation of quarks and leptons and providing the basis to develop the theory of elementary particles. The discovery of the J/psi particle is noted to give rise to the discovery of c-quark, the existance of which is confirmed by the discovery of charmed hadrons. The main aspects of quantum chromodynamics explaining the mechanism of strong interaction of quarks are considered along with those of the Weinberg-Salam theory proposed to describe weak and electromagnetic interactions of quarks and leptons. Experimental data testifying to the existance of heavy tausup(+-) leptons are presented. The history of discovery of γ mesons and of a new heavier b-quark is described. Perspectives for studying elementary particles are discussed. Further studies of γ mesons, discovery and investigation of charmed particles are noted to be immediate tasks along with the search for manifestation of t-quark considered to be a partner of b-quark from the viewpoint of the Weinberg-Salam model
Quark spin and quark orbital angular momentum content of the proton
Li, B.A. [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States)
1995-09-01
In a quark-meson theory it is found that the smallness of quark spin content and strong strange quark polarization can be understood by the anomaly and large {ital N}{sub {ital c}} expansion very well. It has been proved in this theory that the proton spin is mostly carried by quark orbital angular momentum. {copyright} {ital 1995 American Institute of Physics.}
Gutsche, Thomas; Korner, Jurgen G; Lyubovitskij, Valery E; Santorelli, Pietro; Habyl, Nurgul
2015-01-01
Recently there has been much interest in the tauonic semileptonic meson decays B -> D+ tau + nu_tau and B -> D* + tau + nu_tau where one has found larger rates than what is predicted by the Standard Model. We analyze the corresponding semileptonic baryon decays Lambda_b(0) -> Lambda_c(+) + tau(-) + antinu_tau with particular emphasis on the lepton helicity flip and scalar contributions which vanish for zero lepton masses. We calculate the total rate, differential decay distributions, the longitudinal and transverse polarization of the daughter baryon Lambda_c(+) and the tau-lepton, and the lepton-side forward-backward asymmetries. The nonvanishing polarization of the daughter baryon Lambda_c(+) leads to hadron-side asymmetries in e.g. the decay Lambda_c(+) -> Lambda(0) + pi(+) and azimuthal correlations between the two final state decay planes which we specify. We provide numerical results on these observables using results of the covariant confined quark model. We find large lepton mass effects in the q2-spe...
Quark matter symmetry energy and quark stars
Chu, Peng-Cheng; Chen, Lie-Wen
2012-01-01
We extend the confined-density-dependent-mass (CDDM) model to include isospin dependence of the equivalent quark mass. Within the confined-isospin-density-dependent-mass (CIDDM) model, we study the quark matter symmetry energy, the stability of strange quark matter, and the properties of quark stars. We find that including isospin dependence of the equivalent quark mass can significantly influence the quark matter symmetry energy as well as the properties of strange quark matter and quark sta...
Eberl, H; Bartl, A; Hidaka, K; Majerotto, W
2016-01-01
We calculate the decay width of h0 -> b bbar in the Minimal Supersymmetric Standard Model (MSSM) with quark flavour violation (QFV) at full one-loop level. We study the effect of scarm-stop mixing and sstrange-sbottom mixing taking into account the constraints from the B meson data. We discuss and compare in detail the decays h0 -> c cbar and h0 -> b bbar within the framework of the perturbative mass insertion technique using the Flavour Expansion Theorem. The deviation of both decay widths from the Standard Model values can be quite large. Whereas in h0 -> c cbar it is almost entirely due to the flavour violating part of the MSSM, in h0 -> b bbar it is mainly due to the flavour conserving part. Nevertheless, the QFV contribution to Gamma(h0 -> b bbar) due to scarm-stop mixing and chargino exchange can go up to about 8%.
Systematic study of $Z^+_c$ family from quark model's perspective
Deng, Chengrong; Huang, Hongxia; Wang, Fan
2015-01-01
Inspired by the present experimental status of charged charmonium-like states $Z_c^+$, the tetraquark states $[cu][\\bar{c}\\bar{d}]$ are systematically studied in a color flux-tube model with a multi-body confinement potential. The investigation indicates that charged charmonium-like states $Z_c^+(3900)$ or $Z_c^+(3885)$, $Z_c^+(3930)$, $Z_c^+(4020)$ or $Z_c^+(4025)$, $Z_1^+(4050)$, $Z_2^+(4250)$, and $Z_c^+(4200)$ can be uniformly described as tetraquark states $[cu][\\bar{c}\\bar{d}]$ with the quantum numbers $n^{2S+1}L_J$ and $J^P$ of $1^{3}S_1$ and $1^+$, $2^{3}S_1$ and $1^+$, $1^5S_2$ and $2^+$, $1^3P_1$ and $1^-$, $1^5D_1$ and $1^+$, and $1^3D_1$ and $1^+$, respectively. The predicted lowest charged tetraquark state $[cu][\\bar{c}\\bar{d}]$ with $0^+$ and $1^1S_0$ has a energy of $3780\\pm10$ MeV in the model. The tetraquark states are compact three-dimensional spatial configurations similar to a rugby ball, the higher orbital angular momentum $L$ between the diquark $[cu]$ and antidiquark $[\\bar{c}\\bar{d}]$,...
Heavy quark distribution function in hadrons
Oganesian, A. G.
2008-01-01
The moments of the heavy quark-parton distribution functions in a heavy pseudoscalar meson, obtained in QCD sum rules, are expanded in the inverse heavy quark. Comparison with the finite mass results reveals that while the heavy mass expansion works reasonably well for the $b$ quark, one has to take into account terms of higher than $(1/m_c)^2$ order for the $c$ quark.
Top Quark Flavor Changing Decay t → cH0 in Little Higgs Model
Farshid Tabbakh; LIU Jing-Jing; MA Wen-Gan; ZHANG Ren-You; HOU Hong-Sheng
2005-01-01
We study theoretically the quantum effects of the littlest Higgs model (LH) mediated by flavor changing one-loop Feynman diagrams on the rare decay process t → cH0. The comparison of the decay width in the LH model with that in the standard model (SM) is made. We find that the decay branch ratio of t → cH0 in the LH model is at most of the order ～ 10-12, which is two order larger than in the SM. The numerical results show that the difference between the branch ratios in the LH model and the SM is generally sensitive to the LH model parameters, such as symmetry breaking scale f, Higgs boson mass mH0, and x = v'4f /v2 in our chosen parameter space, but relatively insensitive to the value choice of the cosine of the mixing angle c and the ratio λ1/λ2.
Feynman x distributions and transverse momentum pT distributions for the inclusive reactions pp → h±, π0, K-s0 Λ0, anti Λ0, K*±, Σ*± + anything at 360 GeV/c are analyzed in terms of the quark-diquark fragmentation models. Comparison of the model predictions with inclusive data reveals that the model with diquarks can quantitatively describe all data. In particular for the baryon production such as pp → Λ0 + anything, the model without diquarks shows serious discrepancies with the data. Using the quark-diquark fragmentation model, we have found that the primordial transverse momentum T> ≅ 0.6 GeV/c can well reproduce pT2 distributions and the Feynman x-pT correlations. (author)
Bootstrapping quarks and gluons
Dual topological unitarization (DTU) - the approach to S-matrix causality and unitarity through combinatorial topology - is reviewed. Amplitudes associated with triangulated spheres are shown to constitute the core of particle physics. Each sphere is covered by triangulated disc faces corresponding to hadrons. The leading current candidate for the hadron-face triangulation pattern employs 3-triangle basic subdiscs whose orientations correspond to baryon number and topological color. Additional peripheral triangles lie along the hadron-face perimeter. Certain combinations of peripheral triangles with a basic-disc triangle can be identified as quarks, the flavor of a quark corresponding to the orientation of its edges that lie on the hadron-face perimeter. Both baryon number and flavor are additively conserved. Quark helicity, which can be associated with triangle-interior orientation, is not uniformly conserved and interacts with particle momentum, whereas flavor does not. Three different colors attach to the 3 quarks associated with a single basic subdisc, but there is no additive physical conservation law associated with color. There is interplay between color and quark helicity. In hadron faces with more than one basic subdisc, there may occur pairs of adjacent flavorless but colored triangles with net helicity +-1 that are identifiable as gluons. Broken symmetry is an automatic feature of the bootstrap. T, C and P symmetries, as well as up-down flavor symmetry, persist on all orientable surfaces
We discuss the results accumulated during the last five years in heavy quark physics and try to draw a simple general picture of the present situation. The survey is based on a unified point of view resulting from quantum chromodynamics. (orig.)
Inclusive production of rho0 and f is studied in anti pp interactions at 12 GeV/c. The cross sections for rho0 and f are found to be 6.7 +- 0.3 mb and 1.4 +- 0.3 mb, respectively. The inclusive cross sections are presented as functions of c.m. rapidity, Feynman x and p2sub(T). The data are compared with the predictions of the quark fusion model which is found to give a reasonable description of the experimental features. (author)
Prospects for the measurement of the Higgs Yukawa couplings to b and c quarks, and muons at CLIC
Grefe, C.; Laštovička, Tomáš; Strube, J.
2013-01-01
Roč. 73, č. 2 (2013), s. 1-7. ISSN 1434-6044 Institutional support: RVO:68378271 Keywords : Higgs * branching * ratio * Yukawa * couplings * quarks * muons * CLIC * inear collider Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 5.436, year: 2013
Measurements of top quark properties at CDF
Kraan, Aafke C.; /Pennsylvania U.
2006-11-01
The top quark with its mass of about 172 GeV/c{sup 2} is the most massive fundamental particle observed by experiment. In this talk they highlight the most recent measurements of several top quark properties performed with the CDF detector based on data samples corresponding to integrated luminosities up to 1 fb{sup -1}. These results include a search for top quark pair production via new massive resonances, measurements of the helicity of the W boson from top-quark decay, and a direct limit on the lifetime of the top quark.
Mass spectra of doubly heavy baryons in the relativistic quark model
Ebert, D; Faustov, R. N.; Galkin, V. O.; Martynenko, A. P.
2002-01-01
Mass spectra of baryons consisting of two heavy (b or c) and one light quarks are calculated in the framework of the relativistic quark model. The light quark-heavy diquark structure of the baryon is assumed. Under this assumption the ground and excited states of both the diquark and quark-diquark bound system are considered. The quark-diquark potential is constructed. The light quark is treated completely relativistically, while the expansion in the inverse heavy quark mass is used revealing...
Amsler, C.; DeGrand, T.; Krusche, B.
2008-01-01
This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2778 new measurements from 645 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and re...
Forward particle production in π-p and K-p collisions at 58 GeV/c and comparison with quark models
We present single inclusive πsup(+-), π0 and Ksup(+-) spectra in the forward fragmentation region (x>0.2, psub(T)<1.5 GeV/c) as well as correlations between two charged particles. The data were recorded in an unseparated negative hadron beam at the CERN SPS using a large acceptance forward spectrometer. Our measurements are compared in detail with several models which emphasise the role of the beam valence quarks in this production process. The connection to measurements at large psub(T) is also investigated. (orig.)
Molecular and compact four-quark states
Vijande, Javier; Valcarce, A.
2009-01-01
We study charmonium ($c\\bar c n\\bar n$), bottomonium ($b\\bar b n\\bar n$) and exotic ($cc\\bar n\\bar n$ and $bb\\bar n\\bar n$) four-quark states by means of a standard non-relativistic quark potential model. We look for possible bound states. Among them we are able to distinguish between meson-meson molecules and compact four-quark states.
QQqq Four-Quark Bound States in Chiral SU(3) Quark Model
ZHANG Ming; ZHANG Hai-Xia; ZHANG Zong-Ye
2008-01-01
The possibility of QQqq heavy-light four-quark bound states has been analyzed by means of the chiral SU(3) quark model, where Q is the heavy quark (c or b) and q is the light quark (u, d, or s). We obtain a bound state for the bbnn configuration with quantum number JP=1+, I=0 and for the ccnn (JP=1+, I=0) configuration, which is not bound but slightly above the D*D* threshold (n is u or d quark). Meanwhile, we also conclude that a weakly bound state in bbnn system can also be found without considering the chiral quark interactions between the two light quarks, yet its binding energy is weaker than that with the chiral quark interactions.
Alves, Alexandre; Camargo, Daniel A.; Dias, Alex G.
2016-07-01
Motivated by a solution to the strong C P problem, we propose a model where a new heavy neutral C P -even Higgs boson couples to vectorlike quarks enhancing its production cross section whose dominant decays are into weak bosons. The masses of the vectorlike quarks are generated through interactions with a singlet scalar field charged under a broken global U (1 ) symmetry, providing a solution to the strong C P problem by means of the Peccei-Quinn mechanism. The diboson excess observed by the ATLAS Collaboration is discussed as the new heavy Higgs boson is a candidate to explain a possible signal in this channel. We also show that the 14 TeV LHC is capable of discovering this heavy Higgs with masses up to 1 TeV in the H →Z Z →ℓ+ℓ,SUP- ℓ'+ℓ'- search channel using boosted decision trees to better discriminate between signals and backgrounds and to tame systematic uncertainties in the background rates.
On quark-lepton complementarity
Recent measurements of the neutrino solar mixing angle and the Cabibbo angle satisfy the empirical relation θsol + θC ≅ (π/4). This relation suggests the existence of a correlation between the mixing matrices of leptons and quarks, the so called quark-lepton complementarity. Here, we examine the possibility that this correlation originates in the strong hierarchy in the mass spectra of quarks and charged leptons, and the seesaw mechanism that gives mass to the Majorana neutrinos. In a unified treatment of quarks and leptons in which the mass matrices of all fermions have a similar Fritzsch texture, we calculate the mixing matrices VCKM and UMNSP as functions of quark and lepton masses and only two free parameters, in very good agreement with the latest experimental values on masses and mixings. Three essential ingredients to explain the quark-lepton complementarity relation are identified: the strong hierarchy in the mass spectra of quarks and charged leptons, the normal seesaw mechanism and the assumption of maximal CP violation in the lepton sector
The enigmatic properties of quarks have been described by introducing for them a new SU(3) degree of freedom, which is an exact symmetry, with the additional constraint that only states scalar under this new group, named SU/sub c/(3), can be observed. This assumption implies that quarks, which transform under SU/sub c/(3) as the fundamental representation, cannot be observed alone but only in pairs q anti q (mesons) or in triplets (baryons). This new degree of freedom accounts for the symmetry in the other quantum numbers of the baryon wave function and successfully explains (π0 → 2 γ) or reduces (R value) previous discrepancies. The purpose of this work is to show that the octonion algebra supplies a natural framework both for the SU(3) character of the new degree of freedom and for the nonobservability of nonsinglet states
A New Model for Quark Mass Matrix
JIANG Zhi-Wei
2011-01-01
We study the status of S3, I.e. A slightly broken symmetry of quarks and propose a new model in which the S3 symmetry among the three generation up-quarks is slightly broken into the C2 symmetry while the S3 symmetry of the down-quarks is completely broken in a different way.%@@ We study the status of Sa, i.e.a slightly broken symmetry of quarks and propose a new model in which the Sa symmetry among the three generation up-quarks is slightly broken into the C symmetry while the S symmetry of the down-quarks is completely broken in a different way.
Radial Correlations between two quarks
Green, A M; Pennanen, P; Michael, C
2001-01-01
In nuclear many-body problems the short-range correlation between two nucleons is well described by the corresponding correlation in the {two}-body problem. Therefore, as a first step in any attempt at an analogous description of many-quark systems, it is necessary to know the two-quark correlation. With this in mind, we study the light quark distribution in a heavy-light meson with a static heavy quark. The charge and matter radial distributions of these heavy-light mesons are measured on a lattice with a light quark mass about that of the strange quark. Both distributions can be well fitted upto r approx 0.7 fm with the exponential form w_i^2(r), where w_i(r)=A exp(-r/r_i). For the charge(c) and matter(m) distributions r_c approx 0.32(2) fm and r_m \\approx 0.24(2) fm. We also discuss the normalisation of the total charge (defined to be unity in the continuum limit) and matter integrated over all space, finding 1.30(5) and 0.4(1) respectively for a lattice spacing approx 0.17 fm.
Top quark mass measurements at CDF
Maki, Tuula; /Helsinki U. /Helsinki Inst. of Phys.
2007-10-01
The top quark mass is interesting both as a fundamental parameter of the standard model as well as an important input to precision electroweak tests. The CDF Collaboration has measured the top quark mass with high precision in all decay channels with complementary methods. A combination of the results from CDF gives a top quark mass of 170.5{+-}1.3(stat.){+-}1.8(syst.) GeV/c{sup 2}.
Production and decay of heavy top quarks
Experimental evidence indicates that the top quark exists and has a mass between 50 and 200 GeV/c2. The decays of a top quark with a mass in this range are studied with emphasis placed on the mass region near the threshold for production of real W bosons. Topics discussed are: (1) possible enhancement of strange quark production when MW + ms t W + mb; (2) exclusive decays of T mesons to B and B* mesons using the non-relativistic quark model; (3) polarization of intermediate W's in top quark decay as a source of information on the top quark mass. The production of heavy top quarks in an e+e- collider with a center-of-mass energy of 2 TeV is studied. The effective-boson approximation for photons, Z0's and W's is reviewed and an analogous approximation for interfaces between photons and Z0's is developed. The cross sections for top quark pair production from photon-photon, photon-Z0, Z0Z0, and W+W- fusion are calculated using the effective-boson approximation. Production of top quarks along with anti-bottom quarks via γW+ and Z0W+ fusion is studied. An exact calculation of γe+ → bar νt bar b is made and compared with the effective-W approximation. 31 refs., 46 figs
Thermodynamics of Constituent Quarks
Pirner, H. J.; Wachs, M
1997-01-01
We investigate the thermal behavior of quarks and antiquarks interacting via a temperature-dependent linear potential. The quarks are constituent quarks with dynamically generated masses from the background linear $\\sigma$-model.We find a transition from a system of bound mesons to a correlated quark gas at the same temperature as the chiral transition temperature.
Heavy quark spectroscopy and decay
The understanding of q anti q systems containing heavy, charmed, and bottom quarks has progressed rapidly in recent years, through steady improvements in experimental techniques for production and detection of their decays. These lectures are meant to be an experimentalist's review of the subject. In the first of two lectures, the existing data on the spectroscopy of the bound c anti c and b anti b systems will be discussed. Emphasis is placed on comparisons with the theoretical models. The second lecture covers the rapidly changing subject of the decays of heavy mesons (c anti q and b anti q), and their excited states. In combination, the spectroscopy and decays of heavy quarks are shown to provide interesting insights into both the strong and electroweak interactions of the heavy quarks. 103 refs., 39 figs
The quark-gluon plasma (QGP) is a state of matter in which the universe was expected to be a few micro-seconds after the big-bang. Violent collisions of heavy ions are supposed to re-create this state in particle accelerators. Numerous signatures of this fugacious state have already been observed at the RHIC (relativistic heavy ion collider). The first evidence of the violence of collisions is the number of generated particles: about 6000 per collision, mostly hadrons. This figure seems high but in fact is less than theoretically expected and is the first sign of the formation of a QGP that saturates the density of gluons. Another sign, observed at the RHIC is the damping of the particle jets that are produced in the collision. This damping is consistent with the crossing of a medium whose density is so high that it can not be made of hadrons but of partons. In the RHIC experiments the collective behaviour of quarks and gluons shows that they are strongly interacting with one another. This fact supports the idea that the QGP is more a perfect liquid rather than an ideal gas in which quarks and gluons move freely. (A.C.)
Multibody quark forces in quantum chromodynamics
A general exposition of multibody quark forces in quantum chromodynamics is given. The low-energy Hamiltonian involves two-, three-, and four-body quark potentials. We compute the short-range three- and four-body potentials to lowest-order terms in v/c and show that the former does not contribute to the mass of baryons
On the strange quark mass with improved staggered quarks
Hein, J.; Davies, C; Lepage, G. P.; Mason, Q.; Trottier, H.
2002-01-01
We present results on the sum of the masses of light and strange quark using improved staggered quarks. Our calculation uses 2+1 flavours of dynamical quarks. The effects of the dynamical quarks are clearly visible.
Fitting Precision Electroweak Data with Exotic Heavy Quarks
Chang, Darwin; Chang, We-Fu; Ma, Ernest
1999-01-01
The 1999 precision electroweak data from LEP and SLC persist in showing some slight discrepancies from the assumed standard model, mostly regarding $b$ and $c$ quarks. We show how their mixing with exotic heavy quarks could result in a more consistent fit of all the data, including two unconventional interpretations of the top quark.
Understanding penta quark with various quark models
Ping, J; Wang, F; Goldman, T; Ping, Jialun; Qing, Di; Wang, Fan
2004-01-01
The pentaquark state recently discovered has been studied with three quark models which either fit the nucleon spin structure or the $NN$ scattering. A minimum $\\Theta^+$ mass of 1620 MeV is obtained both for the ${1/2}^\\pm$ state. The mixing of various color structure configurations, which would reduce the mass of the penta-quark state, should be taking into account in the calculation of penta-quark mass.
Yuji Takeuchi
2012-10-01
Since the top quark was discovered at Tevatron in 1995, many top quark properties have been measured. However, the top quark is still interesting due to unique features which originate from the extremely heavy mass, and providing various test grounds on the Standard Model as well as searches for a new physics. Though the measurements of the top quark had been performed only at Tevatron so far, LHC is now ready for measurements with more top quarks than Tevatron. In this article, recent measurements of top quark properties from Tevatron (CDF and DØ) as well as LHC (ATLAS and CMS) are presented.
Thermalization of Quark Matter Produced at the Highest Energy of a Relativistic Heavy-Ion Collider
XU Xiao-Ming
2005-01-01
@@ Thermalization of quark matter is studied via a transport equation, which includes triple-quark elastic scattering amplitudes calculated in perturbative QCD. The triple-quark scatterings are demonstrated to be important for an anisotropic initial quark distribution produced in central Au-Au collisions at √sNN = 200 GeV. By examining momentum isotropy to which the transport equation leads, we can determine a thermalization time of 2.2fm/c for quark matter itself to thermalize by the two-quark and the triple-quark elastic scatterings. Meanwhile, an initial thermal quark distribution function is obtained.
HARD QUARK-QUARK SCATTERING WITH EXCLUSIVE REACTIONS*
Barton, D; Bunce, G.; Carroll, A.; Makdisi, Y.; Baller, B.; Blazey, G.; Courant, H.; Heller, K; Heppelmann, S.; Marshak, M.; Peterson, E.; Shupe, M.; Wahl, D.; Gushue, S.; Russell, J.
1985-01-01
We present data from π-p → elastic and ρ-p final states for scattering at 90° center of mass, -t = 9 GeV2/c2. A large ρ-p signal is seen and the ρ- are strongly polarized. This polarization tests a QCD prediction that quarks cannot flip helicity. The test fails dramatically.
The D OE collaboration reports on a search for the Standard Model top quark in p bar p collisions at √s = 1.8 TeV at the Fermilab Tevatron, with an integrated luminosity of approximately 50 pb-1. We have searched for t bar t production in the dilepton and single-lepton decay channels, with and without tagging of b quark jets. We observe 17 events with an expected background of 3.8 ± 0.6 events. The probability for an upward fluctuation of the background to produce the observed signal is 2 x 10-6 (equivalent to 4.6 standard deviations). The kinematic properties of the excess events are consistent with top quark decay. We conclude that we have observed the top quark and measure its mass to be 199-21+19 (stat.) ±22 (syst.) GeV/c21 and its production cross section to be 6.4 ± 2.2 pb. Other decay channels are under study such as the t bar t to all-jets channel which might yield additional information about the top quark
Tevatron combined top quark mass
We summarize the top-quark mass measurements from the CDF and D0 experiments at Fermilab. We combine published Run I (1992-1996) measurements with the most precise published and preliminary Run II (2001-2012) measurements using a data set corresponding to up to 8.7 fb-1 of pp-bar collisions. Taking uncertainty correlations into account, and adding in quadrature the statistical and systematic uncertainties, the resulting preliminary Tevatron average mass of the top quark is mt = 173.20 ± 0.87 GeV/c2. (authors)
Zhou, A Z; Wu, X J; Wang, N; Hong, X Y
2004-01-01
A starquake mechanism for pulsar glitches is developed in the solid quark star model. It is found that the general glitch natures (i.e., the glitch amplitudes and the time intervals) could be reproduced if solid quark matter, with high baryon density but low temperature, has properties of shear modulus \\mu = 10^{30~34} erg/cm^3 and critical stress \\sigma_c = 10^{18~24} erg/cm^3. The post-glitch behavior may represent a kind of damped oscillations.
ZONG Hong-Shi; WU Xiao-Hua; SUN Wei-Min; ZHAO En-Guang; WANG Fan
2003-01-01
A method for obtaining the smallcurrent quark mass dependence of the dressed quark propagator froman effective quark-quark interaction model is developed. Within this approach the small current quark mass effects ondressed-quark propagator have been studied. A comparison with previous results is given.
Symmetries and aggregates of quarks as constituents of hadrons
The interest of the Lie algebra of the group SU(n) for the classification of hadrons and the description of some of their static properties is emphasized for n=3, 4, 6, 8. The cases n=3 and 4 allow to introduce the quark flavors (u,d,s,) and (u,d,c,s), respectively, and the consideration of the spin of hadrons leads to the chain SU(2m) contains SU(m) x SU(2). The hadrons are described as bound states or aggregates of quarks of type quark-quark-quark for baryons and quark-antiquark for mesons. The Pauli exclusion principle applied to the three-quark baryons requires the introduction of a new quantum number, the color: each flavor of quark then comes in three colors
Photoproduction of Heavy Quarks
Krämer, Michael
1995-01-01
Heavy quarks are copiously produced in two-photon collisions at $e^+e^-$ colliders. The theoretical predictions including QCD radiative corrections are compared to recent experimental data on $\\gamma\\gamma$ production of charm quarks at PETRA, PEP, TRISTAN and LEP. Photoproduction of heavy quarks at HERA is an important tool to measure the gluon distribution in the proton. New theoretical results on heavy quark photoproduction at large transverse momenta are discussed and NLO predictions for ...
Renormalized quark-anti-quark free energy
Zantow, F.; Kaczmarek, O.; Karsch, F.; Petreczky, P.
2003-01-01
We present results on the renormalized quark-anti-quark free energy in SU(3) gauge theory at finite temperatures. We discuss results for the singlet, octet and colour averaged free energies and comment on thermal relations which allow to extract separately the potential energy and entropy from the free energy.
ATLAS collaboration; LHCb collaboration
2016-01-01
Measurements of top quarks from Run-I and Run-II of the LHC are presented. Results on differential and inclusive top quark production cross sections, measured by the ATLAS, CMS and LHCb experiments, and measurements of top quark properties and mass are reported.
Xu, R. X.
2004-01-01
The quark matter may have great implications in astrophysical studies, which could appear in the early Universe, in compact stars, and/or as cosmic rays. After a general review of astrophysical quark matter, the density-dominated quark matter is focused.
Phenomenology of quark-lepton symmetric models
Quark-lepton symmetric models are a new class of gauge theories which unify the quarks and leptons. In these models the gauge group of the standard model is extended to include a color group for the leptons, and consequently the quarks and leptons can then be related by a Z2 discrete quark-lepton symmetry. Phenomenological implications of these theories are explored. Two varieties are analysed: one being the simplest quark-lepton symmetric model, and the other containing conventional left-right symmetry. Each theory has a Z' boson, whose masses are constrained at 90% C.L. to be greater than 700 GeV and 650 GeV respectively. Phenomenological constraints from rare decays and the implications of the extended fermion spectrum are also examined. 37 refs., 2 tabs
Quark Orbital Angular Momentum
Burkardt, Matthias
2016-06-01
Generalized parton distributions provide information on the distribution of quarks in impact parameter space. For transversely polarized nucleons, these impact parameter distributions are transversely distorted and this deviation from axial symmetry leads on average to a net transverse force from the spectators on the active quark in a DIS experiment. This force when acting along the whole trajectory of the active quark leads to transverse single-spin asymmetries. For a longitudinally polarized nucleon target, the transverse force implies a torque acting on the quark orbital angular momentum (OAM). The resulting change in OAM as the quark leaves the target equals the difference between the Jaffe-Manohar and Ji OAMs.
The quark model began as little more than a quantum-number counting device. After a brief period during which quarks only played a symmetry role, serious interest in quark dynamics developed. The marriage of the principle of local gauge invariance and quarks has been astonishingly productive. Although many questions still need to be be answered, there is little doubt that the strong, weak and electroweak interactions of matter are described by gauge theories of interactions of the quarks. This review is focussed on the successes
Quark Orbital Angular Momentum
Burkardt, Matthias
2016-03-01
Generalized parton distributions provide information on the distribution of quarks in impact parameter space. For transversely polarized nucleons, these impact parameter distributions are transversely distorted and this deviation from axial symmetry leads on average to a net transverse force from the spectators on the active quark in a DIS experiment. This force when acting along the whole trajectory of the active quark leads to transverse single-spin asymmetries. For a longitudinally polarized nucleon target, the transverse force implies a torque acting on the quark orbital angular momentum (OAM). The resulting change in OAM as the quark leaves the target equals the difference between the Jaffe-Manohar and Ji OAMs.
Foot, R; Volkas, R R
1992-01-01
Quark-lepton symmetric models are a class of gauge theories motivated by the similarities between the quarks and leptons. In these models the gauge group of the standard model is extended to include a ``color'' group for the leptons. Consequently, the quarks and leptons can then be related by a $Z_2$ discrete quark-lepton symmetry which is spontaneously broken by the vacuum. Models utilizing quark-lepton symmetry with acceptable and interesting collider phenomenology have been constructed. The cosmological consequences of these models are also discussed.
Lavelle, Martin; McMullan, David
1995-01-01
It is shown that colour can only be defined on gauge invariant states. Since the ability to associate colour with constituent quarks is an integral part of the constituent quark model, this means that, if we want to extract constituent quarks from QCD, we need to dress Lagrangian quarks with gluons so that the result is gauge invariant. We further prove that gauge fixings can be used to construct such dressings. Gauge invariant dressed quark states are presented and a direct approach to the i...
Carinhas, P A
1993-01-01
Typical nuclear equations of state and a quark bag model, surprisingly, allow compact stars with alternate layers of neutrons and quarks. One can determine on the basis of the Gibbs free energy which phase, nuclear or quark, is energetically favorable. Using the nuclear equation of state of Wiringa, and a quark equation of state given by Freedman and McLerran, the allowed quark parameter space for such layer stars is searched. This paper differs from past work in that configurations are found in which quark matter is located exterior and interior to shells of nuclear matter, i.e., dependent on quark parameters, a star may contain several alternating layers of quark and nuclear matter. Given the uncertainty in the quark parameter space, one can estimate the probability for finding pure neutron stars, pure quark stars (strange stars), stars with a quark core and a nucleon exterior, or layer stars. Several layer models are presented. The physical characteristics, stability, and results of a thorough search of th...
Kim, S. B.
1995-08-01
Top quark production is observed in{bar p}p collisions at{radical}s= 1.8 TeV at the Fermilab Tevatron. The Collider Detector at Fermilab (CDF) and D{O} observe signals consistent with t{bar t} to WWb{bar b}, but inconsistent with the background prediction by 4.8{sigma} (CDF), 4.6a (D{O}). Additional evidence for the top quark Is provided by a peak in the reconstructed mass distribution. The kinematic properties of the excess events are consistent with the top quark decay. They measure the top quark mass to be 176{plus_minus}8(stat.){plus_minus}10(sys.) GeV/c{sup 2} (CDF), 199{sub -21}{sup+19}(stat.){plus_minus}22(sys.) GeV/c{sup 2} (D{O}), and the t{bar t} production cross section to be 6.8{sub -2.4}{sup+3.6}pb (CDF), 6.4{plus_minus}2.2 pb (D{O}).
Quark Number Susceptibility with Finite Quark Mass in Holographic QCD
Kim, Kyung-il; Kim, Youngman; Takeuchi, Shingo; Tsukioka, Takuya
2010-01-01
We study the effect of a finite quark mass on the quark number susceptibility in the framework of holographic QCD. We work in a bottom-up model with a deformed AdS black hole and D3/D7 model to calculate the quark number susceptibility at finite temperature with/without a finite quark chemical potential. As expected the finite quark mass suppresses the quark number susceptibility. We find that at high temperatures $T\\ge 600$ MeV the quark number susceptibility of light quarks and heavy quarks...
Space-Time Geometry of Quark and Strange Quark Matter
无
2007-01-01
We study quark and strange quark matter in the context of general relativity. For this purpose, we solve Einstein's field equations for quark and strange quark matter in spherical symmetric space-times. We analyze strange quark matter for the different equations of state (EOS) in the spherical symmetric space-times, thus we are able to obtain the space-time geometries of quark and strange quark matter. Also, we discuss die features of the obtained solutions. The obtained solutions are consistent with the results of Brookhaven Laboratory, i.e. the quark-gluon plasma has a vanishing shear (i.e. quark-gluon plasma is perfect).
El Yakoubi, M.A
2007-03-15
The PVA4 experiment (Parity Violating in hall A4 in Mainz) aims at assessing the contribution of the strange quark to the charge and current distributions in the nucleon. In order to determine these distributions, measurements of the elastic scattering of longitudinal polarized electrons on a hydrogen target have been performed. 2 types of interaction are involved in this experiment: the electromagnetic interaction (virtual photon exchange) that dominates, and the weak interaction (neutral Z{sup 0} boson exchange). The non-conservation of the parity in the weak interaction induces an asymmetry in the counting rate according to the helicity of the electron beam. The difficulty of this experiment is that it requires the control of the systematic errors and the recording of high statistics due to the low asymmetry (about 10{sup -5} and 10{sup -6} according to the transferred momentum). This document presents the first Rosenbluth separation specific to the PVA4 at Q = 0.23 GeV/c{sup 2}. A formalism related to the violation of parity to separate the strange form factors is developed. The PVA4 experimental setup dedicated to the experiment is given, as well as the Monte-Carlo technique used to extract the strange quark contribution is detailed. The data analysis at forwards and backwards angles has enabled us to determine the following asymmetry values of parity violation: (-5.44 {+-} 0.54 (stat) {+-} 0.26 (sys)) ppm forwards and (-17.1 {+-} 1.4 (stat)) ppm backwards. The combining of these asymmetry values at Q = 0.23 GeV/c{sup 2} has led to the determination of the strange form factors G{sub E}{sup s} and G{sub M}{sup s}: G{sub E}{sup s} = (0.047 {+-} 0.041) and G{sub M}{sup s} = (-0.052 {+-} 0.164). It is also shown that while the strange quark electric component is compatible with a null value, a non-zero contribution of the magnetic part is possible.
The top quark, when it was finally discovered at Fermilab in 1995 completed the three-generation structure of the Standard Model (SM) and opened up the new field of top quark physics. Viewed as just another SM quark, the top quark appears to be a rather uninteresting species. Produced predominantly, in hadron-hadron collisions, through strong interactions, it decays rapidly without forming hadrons, and almost exclusively through the single mode t -> Wb. The relevant CKM coupling Vtb is already determined by the (three-generation) unitarity of the CKM matrix. Rare decays and CP violation are unmeasurable small in the SM. Yet the top quark is distinguished by its large mass, about 35 times larger than the mass of the next heavy quark, and intriguingly close to the scale of electroweak (EW) symmetry breaking. This unique property raises a number of interesting questions. Is the top quark mass generated by the Higgs mechanism as the SM predicts and is its mass related to the top-Higgs-Yukawa coupling? Or does it play an even more fundamental role in the EW symmetry breaking mechanism? If there are new particles lighter than the top quark, does the top quark decay into them? Could non-SM physics first manifest itself in non-standard couplings of the top quark which show up as anomalies in top quark production and decays? Top quark physics tries to answer these questions. Several properties of the top quark have already been examined at the Tevatron. These include studies of the kinematical properties of top production, the measurements of the top mass, of the top production cross-section, the reconstruction of t bar t pairs in the fully hadronic final states, the study of τ decays of the top quark, the reconstruction of hadronic decays of the W boson from top decays, the search for flavor changing neutral current decays, the measurement of the W helicity in top decays, and bounds on tbar t spin correlations. Most of these measurements are limited by the small sample of
Ahmadov, A.; Azuelos, G.; Bauer, U.; Belyaev, A.; Berger, E. L.; Sullivan, Z.; Tait, T. M. P.
2000-03-24
The top quark, when it was finally discovered at Fermilab in 1995 completed the three-generation structure of the Standard Model (SM) and opened up the new field of top quark physics. Viewed as just another SM quark, the top quark appears to be a rather uninteresting species. Produced predominantly, in hadron-hadron collisions, through strong interactions, it decays rapidly without forming hadrons, and almost exclusively through the single mode t {r_arrow} Wb. The relevant CKM coupling V{sub tb} is already determined by the (three-generation) unitarity of the CKM matrix. Rare decays and CP violation are unmeasurable small in the SM. Yet the top quark is distinguished by its large mass, about 35 times larger than the mass of the next heavy quark, and intriguingly close to the scale of electroweak (EW) symmetry breaking. This unique property raises a number of interesting questions. Is the top quark mass generated by the Higgs mechanism as the SM predicts and is its mass related to the top-Higgs-Yukawa coupling? Or does it play an even more fundamental role in the EW symmetry breaking mechanism? If there are new particles lighter than the top quark, does the top quark decay into them? Could non-SM physics first manifest itself in non-standard couplings of the top quark which show up as anomalies in top quark production and decays? Top quark physics tries to answer these questions. Several properties of the top quark have already been examined at the Tevatron. These include studies of the kinematical properties of top production, the measurements of the top mass, of the top production cross-section, the reconstruction of t{bar t}pairs in the fully hadronic final states, the study of {tau} decays of the top quark, the reconstruction of hadronic decays of the W boson from top decays, the search for flavor changing neutral current decays, the measurement of the W helicity in top decays, and bounds on t{bar t} spin correlations. Most of these measurements are limited by
Distributions of leptons in decays of polarised heavy quarks
Czarnecki, A
2009-01-01
Analytic formulae are given for QCD corrections to the lepton spectra in decays of polarised up and down type heavy quarks. These formulae are much simpler than the published ones for the corrections to the spectra of charged leptons originating from the decays of unpolarised quarks and polarised up type quarks. Distributions of leptons in semileptonic $\\Lambda_c$ and $\\Lambda_b$ decays can be used as spin analysers for the corresponding heavy quarks. Thus our results can be applied to the decays of polarised charm and bottom quarks. For the charged leptons the corrections to the asymmetries are found to be small in charm decays whereas for bottom decays they exhibit a non-trivial dependence on the energy of the charged lepton. Short life-time enables polarisation studies for the top quark. Our results are directly applicable for processes involving polarised top quarks.
Vijande, Javier; Barnea, N.; Richard, J. M.; Valcarce, A.
2009-01-01
The physics of charm has become one of the best laboratories exposing the limitations of the naive constituent quark model and also giving hints into a more mature description of meson spectroscopy, beyond the simple quark--antiquark configurations. In this talk we review some recent studies of multiquark components in the charm sector and discuss in particular exotic and non-exotic four-quark systems, both with pairwise and many-body forces.
Testa, Massimo
1990-01-01
In the large quark mass limit, an argument which identifies the mass of the heavy-light pseudoscalar or scalar bound state with the renormalized mass of the heavy quark is given. The following equation is discussed: m(sub Q) = m(sub B), where m(sub Q) and m(sub B) are respectively the mass of the heavy quark and the mass of the pseudoscalar bound state.
El Yakoubi, Marouan Abdelbaste [Universite de Paris XI, Paris (France)
2007-07-01
Quantum Chromodynamics describes the proton as three valence quarks surrounded by a sea of quark-antiquark pairs and gluons.The purpose of an international program, which the PVA4 experiment takes part, is to quantify the contribution of the strange quark to the charge and current distributions in the nucleon. Experimentally, to determine these distributions measurements of elastic scattering of longitudinally polarized electrons ///on a hydrogen target are performed. Two types of interactions intervene in these experiments: the electromagnetic interaction (virtual photon exchange) which dominates, and the weak interaction (neutral boson Z{sup 0} exchange). The non-conservation of parity in the weak interaction induces an asymmetry in the counting rate according to the helicity of the electron beam. The difficulty of these experiments is that they require to control the systematic errors and to record high statistics due to the low asymmetry (about 10{sup -5} and 10{sup -6} according to the transferred momentum). This document presents the first Rosenbluth separation specific to the PVA4 at Q{sup 2} = 0.23(GeV/c){sup 2}. A formalism related to the violation of parity to separate the strange form factors is developed. The PVA4 experimental setup dedicated to the measurement is given, as well as the Monte Carlo technique used to extract the strange quark contribution is detailed. The results of the analysis are presented, and show that while the strange quark electric component is compatible with a null value, a nonzero contribution of magnetic part is possible. (author)
Dzhunushaliev, V D
1997-01-01
The spherically symmetric solution in classical SU(3) Yang - Mills theory is found. It is supposed that such solution describes a classical quark. It is regular in origin and hence the interaction between two quarks is small on the small distance. The obtained solution has the singularity on infinity. It is possible that is the reason why the free quark cannot exist. Evidently, nonlocality of this object leads to the fact that in quantum chromodynamic the difficulties arise connected with investigation of quarks interaction on large distance.
We review the current status of heavy-quark symmetry and its applications to weak decays of hadrons containing a single heavy quark. After an introduction to the underlying physical ideas, we discuss in detail the formalism of the heavy-quark effective theory, including a comprehensive treatment of symmetry breaking corrections. We then illustrate some nonperturbative approaches, which aim at a dynamical, QCD-based calculation of the universal form factors of the effective theory. The main focus is on results obtained using QCD sum rules. Finally, we perform an essentially model-independent analysis of semileptonic B meson decays in the context of the heavy-quark effective theory. ((orig.))
Dakin, James T.
1974-01-01
Reviews theoretical principles underlying the quark model. Indicates that the agreement with experimental results and the understanding of the quark-quark force are two hurdles for the model to survive in the future. (CC)
New quarks: exotic versus strong
Holdom, B.
2011-01-01
The new quarks of a fourth family are being pushed into the strongly interacting regime due to the lower limits on their masses. The theoretical basis and experimental implications of such quarks are compared with exotic quarks.
Effect of temperature gradient on heavy quark anti-quark potential using gravity dual model
Ganesh, S
2016-01-01
The Quark-gluon plasma (QGP) is an expanding fireball, with finite dimensions. Given the finite dimensions, the temperature would be highest at the center, and close to the critical temperature, $T_c$, at the boundary, giving rise to a temperature gradient inside the QGP. A heavy quark anti-quark pair immersed in the QGP medium would see this temperature gradient. The effect of the temperature gradient on the quark anti-quark potential is analyzed using a gravity dual model. The resulting modification to the potential due to the temperature gradient is seen to have a $L^{-2}$ correction term. This could be a possible fallout of the breaking of conformal invariance at finite temperature.
Search for strange quark matter
Hill, J C
2000-01-01
We present results of a search for charged and neutral strangelets produced on collisions of 11.6 A GeV/c Au beams with Pt or Pb targets. Yields of light nuclei and hypernuclei produced by coalescence were measured. Penalty factors were measured for the addition to a fragment of a nucleon or strange hadron. These are useful in planning future searches for strange quark matter.
Yazgan, Efe; Collaboration, for the CMS
2014-01-01
Measurements involving top quarks provide important tests of QCD. A selected set of top quark measurements in CMS including the strong coupling constant, top quark pole mass, constraints on parton distribution functions, top quark pair differential cross sections, ttbar+0 and >0 jet events, top quark mass studied using various kinematic variables in different phase-space regions, and alternative top quark mass measurements is presented. The evolution of expected uncertainties in future LHC ru...
Top quark mass measurement in dilepton channel
In this work, we measured the top quark mass in tt'-' events produced in pp'-' interactions at the center-of-mass energy 1.96 TeV using CDF detector. We used dilepton in tt'-' events where both W bosons from top quarks are decaying into leptons. The data sample corresponds to 340 pb-1. We found there 33 tt'-' candidates while expecting 10.5 ± 1.9 background events. In the measurement, we reconstruct one, representative mass for each event using the assumption about longitudinal momentum of in tt'-' system, in order to be able to kinematically solve the under-constrained system. The mass distributions (templates) are created for simulated signal and background events. Templates are parametrized in order to obtain smooth probability density functions. Likelihood maximization which includes these parametrized templates is then performed on reconstructed masses obtained from data sample in order to obtain final top quark mass estimate. The result of applying this procedure on data events is top quark mass estimate 169.5+7.7-7.2(stat.) ± 4.0(syst.) GeV/c2 for 30 out of 33 candidates, where the solution for top quark mass was found. This measurement was a part of first top quark mass measurement in dilepton channel at CDF in Run II. The top quark mass measured here is consistent with the CDF measurement in dilepton channel from Run I Mtop = 167.4 ± 10.3(stat.) ± 4.8(syst.) GeV/c2. Moreover, the combined result of four top quark mass measurements in dilepton channel from Run II (one of these four measurements is our measurement) Mtop = 167.9 ± 5.2(stat.) ± 3.7(syst.) GeV/c2 significantly (by ∼ 40%) improved the precision of top quark mass determination from Run I. It should be also noted, that this combined result is consistent with measurement obtained in 'lepton+jets' channel at CDF in Run II (Mtop = 173.5+3.9-3.8 GeV/c2). So, we don't have yet any indication about new physics beyond the Standard Model. My main contribution in this analysis was the optimization
Renz, Manuel; /Karlsruhe U., EKP
2008-06-01
In the first part of this diploma thesis, the current version of the KIT Flavor Separator, a neural network which is able to distinguish between tagged b-quark jets and tagged c/light-quark jets, is presented. In comparison with previous versions four new input variables are utilized and new Monte Carlo samples with a larger number of simulated events are used for the training of the neural network. It is illustrated that the output of the neural network is continuously distributed between 1 and -1, whereas b-quark jets accumulate at 1, however, c-quark jets and light-quark jets have outputs next to -1. To ensure that the network output describes observed events correctly, the shapes of all input variables are compared in simulation and data. Thus the mismodelling of any input variable is excluded. Moreover, the b jet and light jet output distributions are compared with the output of samples of observed events, which are enhanced in the particular flavor. In contrast to previous versions, no b-jet output correction function has to be calculated, because the agreement between simulation and collision data is excellent for b-quark jets. For the light-jet output, correction functions are developed. Different applications of the KIT Flavor Separator are mentioned. For example it provides a precious input to all three CDF single top quark analyses. Furthermore, it is shown that the KIT Flavor Separator is a universal tool, which can be used in every high-p{sub T} analysis that requires the identification of b-quark jets with high efficiency. As it is pointed out, a further application is the estimation of the flavor composition of a given sample of observed events. In addition a neural network, which is able to separate c-quark jets from light-quark jets, is trained. It is shown, that all three flavors can be separated in the c-net-Flavor Separator plane. As a result, the uncertainties on the estimation of the flavor composition in events with one tagged jet are cut
Non-commutative model of quark interactions
A non-commutative model of quark interactions with the generalized O(2.6) symmetry in quantum phase space is considered. The model is based on the Snyder-Yang algebra, which includes in the relativistically invariant way two parameters μc and λc with dimensionality of mass and length. The equations of motion obtained in the framework of the model contain the rising potentials which provide the confinement of color particles. The values of the parameters μc and λc, as well as the masses of constituent and current quarks are estimated
QCD phase transition with chiral quarks and physical quark masses.
Bhattacharya, Tanmoy; Buchoff, Michael I; Christ, Norman H; Ding, H-T; Gupta, Rajan; Jung, Chulwoo; Karsch, F; Lin, Zhongjie; Mawhinney, R D; McGlynn, Greg; Mukherjee, Swagato; Murphy, David; Petreczky, P; Renfrew, Dwight; Schroeder, Chris; Soltz, R A; Vranas, P M; Yin, Hantao
2014-08-22
We report on the first lattice calculation of the QCD phase transition using chiral fermions with physical quark masses. This calculation uses 2+1 quark flavors, spatial volumes between (4 fm)(3) and (11 fm)(3) and temperatures between 139 and 196 MeV. Each temperature is calculated at a single lattice spacing corresponding to a temporal Euclidean extent of N(t) = 8. The disconnected chiral susceptibility, χ(disc) shows a pronounced peak whose position and height depend sensitively on the quark mass. We find no metastability near the peak and a peak height which does not change when a 5 fm spatial extent is increased to 10 fm. Each result is strong evidence that the QCD "phase transition" is not first order but a continuous crossover for m(π) = 135 MeV. The peak location determines a pseudocritical temperature T(c) = 155(1)(8) MeV, in agreement with earlier staggered fermion results. However, the peak height is 50% greater than that suggested by previous staggered results. Chiral SU(2)(L) × SU(2)(R) symmetry is fully restored above 164 MeV, but anomalous U(1)(A) symmetry breaking is nonzero above T(c) and vanishes as T is increased to 196 MeV. PMID:25192088
Rafelski, Johann
1998-01-01
We present a brief survey of the development of nuclear physics towards relativistic quark physics. This is followed by a thorough discussion of the quest for the observation of the dissolution of nuclear matter into the deconfined quark matter (QGP) in relativistic nuclear collisions. Use of strange particle signatures in search for QGP is emphasized.
Eric Laenen
2012-10-01
The theoretical aspects of a number of top quark properties such as its mass and its couplings are reviewed. Essential aspects in the theoretical description of top quark production, singly, in pairs and in association, as well as its decay related to spin and angular correlations are discussed.
Like any other electrically charged particles, quarks should give out electromagnetic radiation (photons) when they vibrate. One of the physics results from CERN's LEP collider is the first clear observation of this quark radiation from electron-positron collisions. At lower energies this radiation could only be inferred
Properties of bound states containing fourth family quarks
The heavy fourth generation of quarks that have sufficiently small mixing with the three known SM families form hadrons. In the present work, we calculate the masses and decay constants of mesons containing either both quarks from the fourth generation or one from fourth family and the other from observed SM quarks, namely charm or bottom quark, in the framework of the QCD sum rules. In the calculations, the two gluon condensate diagrams as nonperturbative contributions are taken into account. The obtained numerical results are reduced to the known masses and decay constants of the b-bar b and c-bar c quarkonia, when the fourth family quark is replaced by the bottom or charm quark.
The hadronization time of heavy quark in nuclear matter
Song, Taesoo
2016-01-01
We study the hadronization time of heavy quark in nuclear matter by using the coalescence model and the spatial diffusion constant of heavy quark from lattice Quantum Chromodynamic calculations, assuming that the main interaction of heavy quark at the critical temperature is hadronization. It is found that the hadronization time of heavy quark is about 3 fm/c for $2\\pi T_c D_s=6$, if a heavy quark is combined with the nearest light antiquark in coordinate space without any correlation between momentum of heavy quark and that of light antiquark which form a heavy meson. However, the hadronization time reduces to 0.6-1.2 fm/c for charm and 0.4-0.9 fm/c for bottom, depending on heavy meson radius, in the presence of momentum correlation. Considering the interspace between quarks and antiquarks at the critical temperature, it seems that the hadronization of heavy quark does not happen instantaneously but gradually for a considerable time, if started from the thermal distribution of quarks and antiquarks.
String formation and chiral symmetry breaking in the heavy-light quark-antiquark system in QCD
Simonov, YA; Tjon, JA
2000-01-01
The effective quark Lagrangian is written for a light quark in the field of a static antiquark, explicitly containing field correlators as coefficient functions of products of quark operators. At large N-c the closed system of equations for the gauge-invariant quark Green's function in the field of
Light Quark Mass Effects in Bottom Quark Mass Determinations
Hoang, A. H.
2001-01-01
Recent results for charm quark mass effects in perturbative bottom quark mass determinations from $\\Upsilon$ mesons are reviewed. The connection between the behavior of light quark mass corrections and the infrared sensitivity of some bottom quark mass definitions is examined in some detail.
Light Quark Mass Effects in Bottom Quark Mass Determinations
Hoang, A H
2000-01-01
Recent results for charm quark mass effects in perturbative bottom quark mass determinations from $\\Upsilon$ mesons are reviewed. The connection between the behavior of light quark mass corrections and the infrared sensitivity of some bottom quark mass definitions is examined in some detail.
Simple-minded estimate of the masses of baryons containing single heavy quarks
Zalewska, Agnieszka; Zalewski, Kacper
1996-01-01
The masses of the yet undiscovered baryons containing single $c$ or $b$ quarks are estimated from the known masses using the following rules: equal distances in mass between the isomultiplets forming sextets, equal mass differences between the corresponding spin one-half baryons containing $c$ and $b$ quarks, hyperfine splittings inversely proportional to the masses of the heavy quarks.
Quark contribution to the proton spin in the chiral quark-meson model
Stern, J. (Laboratoire de Physique Theorique, Universite des Sciences et de la Technologie Houari Boumediene, Alger (DZ)); Clement, G. (Departement de Physique, Ecole Normale Spuerieure, Vieux-Kouba, Alger (DZ))
1988-12-01
It has been argued that, to leading order in the 1/N/sub c/ expansion, very little of the spin of the proton is carried by the helicities of its constituent quarks, in accordance with the results of a recent EMC experiment. The authors investigate this question by a direct computation in the chiral quark-meson model, where the proton spin is generated by cranking a mean field hedgehog baryon. For not too small values of the quark-meson coupling constant, their results are consistent with the EMC data.
AUTHOR|(CDS)2071660; Schael, Stefan; Rohlf, James W
2007-01-01
In the past thirty years particle physics has developed rapidly resulting in the formulation of the Standard Model, which seems to provide, at least in principle, a microscopic description for all known physical phenomena except gravity. The Standard Model is not complete, e.g. it lacks any explanation for the pattern of particle masses. The Higgs mechanism provides a solution to the problem of how particles acquire their masses. It implies the existence of at least one new particle, the Higgs boson H0 , which has not yet been observed. The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) will be switched on in winter 2007. If the Higgs boson exists, the LHC will be able to detect it. Depending on the mass of the Higgs boson, physicists have a clear idea regarding its experi- mental signature. For quite low masses (50 < mH0 < 130[ GeV]) )1 the Higgs will predominantly decay into two b-quarks. The present study describes the investigation of the identification ca- pabi...
Four-quark states in the heavy quark system
Four-quark states Rsub(4q)=anti qanti qqq in a heavy quark system are considered in the framework of the potential model. A special attention is paid on the possibility of observing such states in a direct channel in e+e- annihilation. It is shown that in the system anti canti ccc there must exist a resonance with Jsup(PC)=1sup(--), spin S=2, the mass M approximately 6.75 GeV, the electron width GITAsub(esup(+)esup(-)) approximately 0.02 eV and the total width GITAsub(tot) approximately 10 MeV. For analogous state in the systems anti cantiscs and anti santi sss are obtained Msub(anti canti scs) approximately 4.8 GeV, GITAsub(esup(+)esup(-)) approximately 0.4 eV and Msub(anti santi sss) approximately 2.7 GeV, GITAsub(esup(+)esup(-)) approximately 3 eV. The decay modes of such states and possibilities of their observation are discussed. The masses of C-even 4-quark states are also calculated, their 2γ decay widths and the probabilities of charmonium and upsilonium radiative decays into these states are estimated
Multiple Parton Scattering in Nuclei: Quark-quark Scattering
Schafer, Andreas; Wang, Xin-Nian; Zhang, Ben-Wei
2007-01-01
Modifications to quark and antiquark fragmentation functions due to quark-quark (antiquark) double scattering in nuclear medium are studied systematically up to order \\cal{O}(\\alpha_{s}^2)$ in deeply inelastic scattering (DIS) off nuclear targets. At the order $\\cal{O}(\\alpha_s^2)$, twist-four contributions from quark-quark (antiquark) rescattering also exhibit the Landau-Pomeranchuck-Midgal (LPM) interference feature similar to gluon bremsstrahlung induced by multiple parton scattering. Comp...
Test of the quark statistics rules in processes of hadron multiple production
The quark combinatorics rules are tested in processes of kaon production. Investigated is one of the basic suppositions of the quark combineableness: hypothesis on the fact that the processes of quark blending into hadrons do not depend on quantum numbers of the united quarks. Yields of caons in k-p- collisions at 32 GeV/c and pp-collisions at 405 GeV/c are presented
We investigate the properties of multi-strange baryonic systems, comparing conventional many -- Λ hypernuclei, where the strange quarks are localized in individual hyperons, to ''strangelets'' or chunks of strange matter, which involves delocalized quarks which roam in a single large bag. Mass formulae and strong/weak decay modes for such objects are discussed, as well as the prospects for producing multi-strange systems in relativistic heavy ion collisions. For production, we consider two extremes, one based on the coalescence model and another which assumes the formation of quark-gluon-plasma. We mention the experimental searches which are underway or planned, using heavy ion beams
Beauty-quark and charm-quark pair production asymmetries at LHCb
Gauld, Rhorry; Pecjak, Ben D; Re, Emanuele
2015-01-01
The LHCb collaboration has recently performed a first measurement of the angular production asymmetry in the distribution of beauty quarks and anti-quarks at a hadron collider. We calculate the corresponding standard model prediction for this asymmetry at fixed-order in perturbation theory. Our results show good agreement with the data, which is provided differentially for three bins in the invariant mass of the $b \\bar b$ system. We also present similar predictions for both beauty-quark and charm-quark final states within the LHCb acceptance for a collision energy of $\\sqrt{s} = 13 \\, {\\rm TeV}$. We finally point out that a measurement of the ratio of the $b \\bar b$ and $c \\bar c$ cross sections may be useful for experimentally validating charm-tagging efficiencies.
Evidence for production of single top quarks
Abazov, V.M.; /Dubna, JINR; Abbott, B.; /Oklahoma U.; Abolins, M.; /Michigan State U.; Acharya, B.S.; /Tata Inst.; Adams, M.; /Illinois U., Chicago; Adams, T.; /Florida State U.; Aguilo, E.; /Simon Fraser U.; Ahn, S.H.; /Korea U., KODEL; Ahsan, M.; /Kansas State U.; Alexeev, G.D.; /Dubna, JINR; Alkhazov, G.; /St. Petersburg, INP /Michigan U.
2008-03-01
We present first evidence for the production of single top quarks in the D0 detector at the Fermilab Tevatron p{bar p} collider. The standard model predicts that the electroweak interaction can produce a top quark together with an antibottom quark or light quark, without the antiparticle top quark partner that is always produced from strong coupling processes. Top quarks were first observed in pair production in 1995, and since then, single top quark production has been searched for in ever larger datasets. In this analysis, we select events from a 0.9 fb{sup -1} dataset that have an electron or muon and missing transverse energy from the decay of a W boson from the top quark decay, and two, three, or four jets, with one or two of the jets identified as originating from a b hadron decay. The selected events are mostly backgrounds such as W+jets and t{bar t} events, which we separate from the expected signals using three multivariate analysis techniques: boosted decision trees, Bayesian neural networks, and matrix element calculations. A binned likelihood fit of the signal cross section plus background to the data from the combination of the results from the three analysis methods gives a cross section for single top quark production of {sigma}(p{bar p} {yields} tb + X, tqb + X) = 4.7 {+-} 1.3 pb. The probability to measure a cross section at this value or higher in the absence of signal is 0.014%, corresponding to a 3.6 standard deviation significance. The measured cross section value is compatible at the 10% level with the standard model prediction for electroweak top quark production. We use the cross section measurement to directly determine the Cabibbo-Kobayashi-Maskawa quark mixing matrix element that describes the Wtb coupling and find |V{sub tb}f{sub 1}{sup L}| = 1.31{sub -0.21}{sup +0.25}, where f{sub 1}{sup L} is a generic vector coupling. This model-independent measurement translates into 0.68 < |V{sub tb}| {le} 1 at the 95% C.L. in the standard model.
Continuum estimate of the heavy quark momentum diffusion coefficient $\\kappa$
Kaczmarek, Olaf
2014-01-01
Among quantities playing a central role in the theoretical interpretation of heavy ion collision experiments at RHIC and LHC are so-called transport coefficients. Out of those heavy quark diffusion coefficients play an important role e.g. for the analysis of the quenching of jets containing c or b quarks (D or B mesons) as observed at RHIC and LHC. We report on a lattice investigation of heavy quark momentum diffusion within pure SU(3) plasma above the deconfinement transition with the quarks...
Distributions of leptons in decays of polarised heavy quarks
Czarnecki, A; Jeżabek, M.
1994-01-01
Analytic formulae are given for QCD corrections to the lepton spectra in decays of polarised up and down type heavy quarks. These formulae are much simpler than the published ones for the corrections to the spectra of charged leptons originating from the decays of unpolarised quarks and polarised up type quarks. Distributions of leptons in semileptonic $\\Lambda_c$ and $\\Lambda_b$ decays can be used as spin analysers for the corresponding heavy quarks. Thus our results can be applied to the de...
Effect of Quark Strong Interaction in Phase Transition on Supernova Explosion
LAI Xiang-Jun; LUO Zhi-Quan; LIU Jing-Jing; LIU Hong-Lin
2008-01-01
The effect of quark interactions perturbatively to order αc on the conversion, from quark matter to strange quark matter, is studied systematically based on a recent set of current quark masses. The process has a significant effect on increasing the core temperature, the neutrino abundance and the neutrino energies even if there is no quark interaction. Furthermore, with the switch of the strong interaction among quarks, these quantities will increase respectively to some further extents with αc increase. Taking αc = 0.47 as an example, the temperature, the neutrino abundance and the total neutrino energies are further raised by about 10%, 7%, and 20% respectively, which is weakly dependent on the initial temperature. Combining the effect of the current quark mass and the effect of the quark strong interaction, the results of the conversions will greatly enhance the probability of success for a supernova explosion and deeply influence the dynamics of the supernova evolution.
Spectroscopy of heavy quark hadrons
Heavy quarks play special roles in the hadron spectroscopy. Some distinct features of heavy quark dynamics and their significance in the P-wave baryons with a single heavy quark are discussed. We also explore a new color configuration in exotic tetra-quark mesons with two heavy quarks. Finally, possibility of bound states of a charmed baryon with a nucleon and nuclei are examined. (author)
ZONG Hong-Shi; PING Jia-Lun; SUN Wei-Min; CHANG Chao-Hsi; WANG Fan
2002-01-01
We exhibit a method for obtaining the low chemical potential dependence of the dressed quark propagatorfrom an effective quark-quark interaction model. Within this approach we explore the chemical potential dependenceof the dressed-quark propagator, which provides a means of determining the behavior of the chiral and deconfinementorder parameters. A comparison with the results of previous researches is given.
Xu, R
2005-01-01
Members of the family of pulsar-like stars are distinguished by their different manifestations observed, i.e., radio pulsars, accretion-driven X-ray pulsars, X-ray bursts, anomalous X-ray pulsars/soft gamma-ray repeaters, compact center objects, and dim thermal neutron stars. Though one may conventionally think that these stars are normal neutron stars, it is still an open issue whether they are actually neutron stars or quark stars, as no convincing work, either theoretical from first principles or observational, has confirmed Baade-Zwicky's original idea that supernovae produce neutron stars. After introducing briefly the history of pulsars and quark stars, the author summarizes the recent achievements in his pulsar group, including quark matter phenomenology at low temperature, starquakes of solid pulsars, low-mass quark stars, and the pulsar magnetospheric activities.
Top quark studies at future e+e- colliders are considered. Two issues are discussed: a - Some results are presented on the decays of top quarks. Energy distributions of charged leptons and neutrinos in t→bW→be+ν and jets in t→bW→bdu decays are sensitive to the structure of tbW vertex. Distributions of charged leptons from top decays are particularly useful in polarization studies whereas neutrinos are sensitive to deviations from the Standard Model. b - Recent calculations are renewed on the top quark pair production in e+e- annihilation. The differential cross sections in the threshold region can lead to an accurate determination of the top quark mass and the interquark potential. The effects of the top-Higgs Yukawa coupling and some higher order QCD corrections are also under control. ((orig.))
Narendra Singh
2003-01-01
Assuming a relation between the quark mass matrices of the two sectors a unique solution can be obtained for the CKM ﬂavor mixing matrix. A numerical example is worked out which is in excellent agreement with experimental data.
We propose and discuss a numerical use for our previous precision results for the radiative corrections to unpolarized spin one-half baryon semileptonic decays, which is not compromised to fixing the form factors at prescribed values. We present various cross-checks and comparisons with other results available in the literature of such analytical radiative corrections. Our analysis, however, is general and applies to all charge assignments to the baryons allowed by heavy quarks. The procedure is exemplified with the processes Ξ0→Σ+eν and Λc+→Λe+ν
The distribution of h1(x) of quark transverse polarization can be measured by Deep Inelastic Scattering using Collins effect as quark polarimeter. We propose to calibrate this polarimeter in e+e- → 2 jets. We give an explanation of single spin asymmetries in inclusive meson production based on the Collins effect. We propose a proportionality between the electric dipole moment of the nucleon on its tensor charge. (authors)
Quark Orbital Angular Momentum
Burkardt Matthias
2015-01-01
Definitions of orbital angular momentum based on Wigner distributions are used as a framework to discuss the connection between the Ji definition of the quark orbital angular momentum and that of Jaffe and Manohar. We find that the difference between these two definitions can be interpreted as the change in the quark orbital angular momentum as it leaves the target in a DIS experiment. The mechanism responsible for that change is similar to the mechanism that causes transverse single-spin asy...
Sørensen, Paul Haase; Taylor, John C.
1984-01-01
Processes with coloured particles in the initial state are generally infrared divergent. We investigate the effect of this on processes with colourless particles in the initial state, when the amplitude is near an intermediate quark pole. The result is a characteristic logarithmic depedence on the...... 'binding energy'(even though spectator interactions are taken into account), and the result is gauge-invariant. Summed to all orders the logarithms could perhaps suppress the quark pole....
Sørensen, Paul Haase; Taylor, John C.
1984-01-01
Processes with coloured particles in the initial state are generally infrared divergent. We investigate the effect of this on processes with colourless particles in the initial state, when the amplitude is near an intermediate quark pole. The result is a characteristic logarithmic depedence...... on the 'binding energy'(even though spectator interactions are taken into account), and the result is gauge-invariant. Summed to all orders the logarithms could perhaps suppress the quark pole....
The Multimedia Project Quarked!
Bean, Alice; MacDonald, Teresa
2011-01-01
Can exposure to fundamental ideas about the nature of matter help motivate children in math and science and support the development of their understanding of these ideas later? Physicists, designers, and museum educators at the University of Kansas created the Quarked!(tm) Adventures in the subatomic Universe project to provide an opportunity for youth to explore the subatomic world in a fun and user friendly way. The project components include a website (located at http://www.quarked.org) an...
Heavy Quarks in the Quark-Gluon Plasma
Rapp, Ralf
2010-01-01
Heavy-flavor particles are believed to provide valuable probes of the medium produced in ultrarelativistic collisions of heavy nuclei. In this article we review recent progress in our understanding of the interactions of charm and bottom quarks in the Quark-Gluon Plasma (QGP). For individual heavy quarks, we focus on elastic interactions for which the large quark mass enables a Brownian motion treatment. This opens a unique access to thermalization mechanisms for heavy quarks at low momentum, and thus to their transport coefficients in the quark-gluon fluid. Different approaches to evaluate heavy-quark diffusion are discussed and compared, including perturbative QCD, effective potential models utilizing input from lattice QCD and string-theoretic estimates in conformal field theories. Applications to heavy-quark observables in heavy-ion collisions are realized via relativistic Langevin simulations, where we illustrate the important role of a realistic medium evolution to quantitatively extract the heavy-quark...
Constraints on nucleon quark models from deep inelastic scattering data
Within the context of Q.C.D. it is assumed that quarks and gluons have rather sharply defined masses in the confinement region. Then the experimental data on structure functions give an upper limit to the light quark masses approximately 600MeV. Target mas corrections to scaling depend on further approximations
Quark scattering of quarks and hadrons
Friesen, A.V.; Kalinovsky, Yu.L.; Toneev, V.D.
2014-03-01
The in-medium elastic scattering qq→qq,qq{sup ¯}→qq{sup ¯} and q{sup ¯}q{sup ¯}→q{sup ¯}q{sup ¯} is calculated within the two-flavor Polyakov-loop-extended Nambu–Jona-Lasinio model. The integral and differential quark–quark scattering, its energy and temperature dependence are considered and their flavor dependence is emphasized. The comparison with results of other approaches is presented. The consideration is implemented to the case of quark–pion scattering characterizing the interaction between quarks and hadrons in a kinetic multiphase treatment, and the first estimate of the quark–pion cross sections is given. A possible application of the obtained results to heavy ion collisions is shortly discussed.
Tung, Kwong-Kwai Humphrey
1992-01-01
The rare decays bto sX are sensitive to strong interaction corrections. The effects can be estimated by a renormalization group technique which requires the evaluation of QCD mixing among effective operators. In the dimensional reduction and the naive dimensional regularization methods, there are discrepancies in evaluating the QCD mixing of the four-quark operators with the bto sgamma and bto s+gluon dipole operators. In this thesis, the problem is investigated by considering the contributions of the epsilon -scalar field and the epsilon -dimensional operators that distinguish between the two methods. The discrepancies are shown to come from the epsilon-dimensional four-quark operators in dimensional reduction and not from the epsilon -scalar field. In the decay bto sl^+l^ -, the intermediate of cc pairs in the charm-penguin diagram can form the resonance states J/psi and psi^'. In the published literature, there is a sign discrepancy in the Breit-Wigner amplitude for the resonance effects. Here, the sign difference is settled by considering the unitarity limit of the amplitude in the Argand diagram. The effects of the resonances are quite substantial on the invariant mass spectrum for this decay. However, they are shown to be negligible on the dilepton energy spectrum below 0.95 GeV. The energy spectrum is, thus, more useful than the invariant mass spectrum for measurements of the top -quark mass. The decays Bto K^*X are well modeled by the quark-level decays bto sX. In the quark model, the hadronization is done using a nonrelativistic wave function. In the decay B to K^*gamma, the large K ^* recoil creates an uncertainty in calculating the branching ratio using the quark model. The problem is explored by considering other meson processes where data exist. The data on the pi form factor and the omegapi^0 transition form factor suggest the necessity to retain relativistic spinor and meson normalizations in the quark -model; however, the data do not resolve the
Static quark anti-quark free energy and the running coupling at finite temperature
Kaczmarek, O; Petreczky, P; Zantow, F
2004-01-01
We analyze the free energy of a static quark anti-quark pair in quenched QCD at short and large distances. From this we deduce running couplings, g^2(r,T), and determine the length scale that separates at high temperature the short distance perturbative regime from the large distance non-perturbative regime in the QCD plasma phase. Ambiguities in the definition of a coupling beyond the perturbative regime are discussed in their relation to phenomenological considerations on heavy quark bound states in the quark gluon plasma. Our analysis suggests that it is more appropriate to characterize the non-perturbative properties of the QCD plasma phase close to T_c in terms remnants of the confinement part of the QCD force rather than a strong Coulombic force.
Making quark matter at brook haven's new collider
Quarks are believed to come in 6 flavours, only the lightest of which, the up and down quarks, are found in protons and neutrons. Isolated quarks have never been observed. As quarks are brought closer together, the force between them decreases dramatically, vanishing as the separation becomes very small. This suggests that quarks may become unbound if the density of quarks could be increased by squeezing a nucleus. The nucleus would have melted their constituent quarks, now free to roam the extended volume of the compressed nucleus. This situation would make a significant change in the structure of matter corresponding to a change of phase, rather like the transition from solid to liquid, but in this case from quark confined matter, to a quark gluon plasma (QGP). This new state of matter is thought to have been the natural phase of matter until 10 micro-seconds after the big-bang, and also to exist today in the core of neutron stars. Calculations show that the energy density needed to observe the phase transition is around 1 GeV/fm3, approximately 8 times that of normal nuclear matter. Attempts to recreate QGP have been underway at the relativistic heavy ion collider (RHIC) and at the CERN by colliding heavy-ion beams at the maximal energy possible. Between 4000 and 5000 charged particles are produced in the most violent events. The experimental challenge is to establish the existence of QGP from all this wealth of data. (A.C.)
Hydrodynamics of a quark droplet
Bjerrum-Bohr, Johan J; Døssing, Thomas
2011-01-01
We present a simple model of a multi-quark droplet evolution based on the hydrodynamical description. This model includes collective expansion of the droplet, effects of the vacuum pressure and surface tension. The hadron emission from the droplet is described following Weisskopf's statistical model. We have considered evolution of baryon-free droplets which have different initial temperatures and expansion rates. As a typical trend we observe an oscillating behavior of the droplet radius superimposed with a gradual shrinkage due to the hadron emission. The characteristic life time of droplets with radii 1.5-2 fm are about 9-16 fm/c.
Top quark couplings and polarization
Precise measurements of top quark couplings are presented. The measurements cover the single top tW cross section, the top-quark branching-fraction ratio R=B(t → Wb)/B(t → Wq) and the CKM matrix element Vtb from the single top cross sections. Top quark polarisation in the t-channel single-top quark production and dilepton tt, and W-helicity fraction measurements along with searches of top quark anomalous couplings in lepton plus jet channel are also presented. Finally measurements of top quark pair production in association with a W or Z boson or a photon are presented
Physics with boosted top quarks
Kuutmann, Elin Bergeaas
2014-01-01
The production at the LHC of boosted top quarks (top quarks with a transverse momentum that greatly exceeds their rest mass) is a promising process to search for phenomena beyond the Standard Model. In this contribution several examples are discussed of new techniques to reconstruct and identify (tag) the collimated decay topology of the boosted hadronic decays of top quarks. Boosted top reconstruction techniques have been utilized in searches for new physical phenomena. An overview is given of searches by ATLAS, CDF and CMS for heavy new particles decaying into a top and an anti-top quark, vector-like quarks and supersymmetric partners to the top quark.
Dileptons from a Chemically Equilibrating Quark-Gluon Plasma at Finite Baryon Density
GUAN Na-Na; HE Ze-Jun; LONG Jia-Li; CAI Xiang-Zhou
2008-01-01
We perform a complete calculation for the delepton production from the processes q(q-) →l(l-), Compton-like (qg→ql(l-),(q-)g→ql(l-)), q(q-)→gl(l-), gluon fusion g(g-)→c(c-), annihilation q(q-)→c(c-) as well as multiple scattering of quarks in a chemically equilibrating quark-gluon plasma system at finite baryon density. It is found that quark-antiquark annihilation,Compton-like, gluon fusion and multiple scattering of quarks give important contribution. Moreover, the increase of the quark phase life-time with increasing initial quark chemical potential makes the dilepton yield as an increasing function of the initial quark chemical potential.
SU(6) model with heavy t-quark
The representation assignments of fermions in a previous model are changed to make t-quark heavy. Together with this, the third generation (t,b,tau) as well as c-quark show some peculiar feature. For example, the left-handed component of the observed b-quark is a mixture of an SU(2) singlet with a component of a doublet, and meson (bsub(i).sup(c)dsub(i)) will decay through baryon number violating interactions of tau++psup(c). (author)
Liu, Qi; Jung, Chulwoo
2012-01-01
We present a systematic study of the effectiveness of light quark mass reweighting. This method allows a single lattice QCD ensemble, generated with a specific value of the dynamical light quark mass, to be used to determine results for other, nearby light dynamical quark masses. We study two gauge field ensembles generated with 2+1 flavors of dynamical domain wall fermions with light quark masses m_l=0.02 (m_\\pi=620 MeV) and m_l=0.01 (m_\\pi=420 MeV). We reweight each ensemble to determine results which could be computed directly from the other and check the consistency of the reweighted results with the direct results. The large difference between the 0.02 and 0.01 light quark masses suggests that this is an aggressive application of reweighting as can be seen from fluctuations in the magnitude of the reweighting factor by four orders of magnitude. Never-the-less, a comparison of the reweighed topological charge, average plaquette, residual mass, pion mass, pion decay constant, and scalar correlator between ...
Hadron production in the quark combinatorics with color quarks
An effect of color quark correlations on the M:B:anti B ratio of meson, baryon and antibaryon yields in the case of multiple hadron production is considered. It is shown that when the quark baryon number reveals itself like the probability of baryon state production of the quark, the M:B:anti B ratio in the central region weakly depends on the color correlations, and it is close to the value obtained earlier without account for the color quark states
Quark-quark Double Scattering and Modified (Anti-)Quark Fragmentation Functions in Nuclei
Zhang, Ben-Wei; Wang, Xin-Nian; Schaefer, Andreas
2007-01-01
Quark-quark double scattering in eA DIS and its contribution to quark and anti-quark fragmentation functions are investigated with the generalized factorization of the relevant twist-four processes in pQCD. It is shown that the resulting modifications to quark and anti-quark fragmentation functions are different. While the numerical size of these effects cannot be determined from pQCD, the structure of our result leads to a number of qualitative predictions for the relative size of the effect...
Quark energy loss in an expanding quark-gluon plasma
Zakharov, B. G.
1998-01-01
We study the quark energy loss in an expanding quark-gluon plasma. The expanding plasma produced in high energy AA-collision is described by Bjorken's model. The dependence of the energy loss on the infrared cutoff for the radiated gluons, on the quark mass, and on the initial conditions of QCD plasma is investigated.
Studying quark condensates within models of four-quark interaction
Molodtsov, S. V.; Zinovjev, G. M.
2013-01-01
Analysing two models of four-quark interactions which are of intrinsic difference in the behaviours of their correlation lengths some issues of quark condensations are considered. It is demonstrated that the quark condensates substantially are not sensitive to the details of those interactions in the range of coupling constants interesting for applications.
Observable contributions of new exotic quarks to quark mixing
del Aguila, F.; Perez-Victoria, M.; J. Santiago
2000-01-01
Models with new vector-like quarks can produce observable quark mixing effects which are forbidden in the Standard Model. We classify all such models and write down the effective Lagrangian that results from integrating out the new quarks. We study the relations between neutral and charged currents and discuss how to distinguish among the different possibilities.
Measurement of the bottom quark lifetime
The quark mixing matrix is constrained by the lifetime of the bottom quark, the off-diagonal elements involving the b quark being completely determined by the lifetime and the branching ratio between the decays b → u and b → c. If the binding of the b quark into hadrons has no effect on its decay rate, the inclusive lifetime measurement discussed here reflects precisely the quark total decay rate. Their experience with charmed hadrons serves to warn that the situation may not be so simple, and they are eager to find techniques for determining the lifetimes of individual hadron states, particularly the mesons B+, B/sub d/0 and B/sub s/0. The subject of this note, however, is a detailed evaluation of prospects for improving the inclusive measurement, as it has been performed at PEP and PETRA, based upon the impact parameter distribution of leptons from the b hadron semileptonic decays. This note supersedes intermediate reports from the Asilomar and Granlibakken meetings. The first two sections are based mainly upon studies with Monte Carlo generated quantities in which they explore the kinematics of bottom particle semileptonic decays to develop event selection criteria and measure sensitivity of the impact parameter to the lifetime and to the details of particle production. Detector effects are considered in section 3, data reduction in sections 4 and 5, and conclusions in section 6. 6 references, 11 figures, 1 table
Precision Determination of the Top Quark Mass
Movilla Fernandez, Pedro A.; /LBL, Berkeley
2007-05-01
The CDF and D0 collaborations have updated their measurements of the mass of the top quark using proton-antiproton collisions at {radical}s = 1.96 TeV produced at the Tevatron. The uncertainties in each of the top-antitop decay channels have been reduced. The new Tevatron average for the mass of the top quark based on about 1 fb{sup -1} of data per experiment is 170.9 {+-} 1.8 GeV/c{sup 2}.
Measurement of the Top Quark Mass
We present a measurement of the top quark mass using a sample of t bar t decays into an electron or a muon, a neutrino, and four jets. The data were collected in p bar p collisions at √(s)=1.8 TeV with the Collider Detector at Fermilab and correspond to an integrated luminosity of 109 pb-1 . We measure the top quark mass to be 175.9±4.8(stat)±4.9( syst) GeV /c2 . copyright 1998 The American Physical Society
Strongly Coupled Quark Gluon Plasma (SCQGP)
Bannur, Vishnu M.
2005-01-01
We propose that the reason for the non-ideal behavior seen in lattice simulation of quark gluon plasma (QGP) and relativistic heavy ion collisions (URHICs) experiments is that the QGP near T_c and above is strongly coupled plasma (SCP), i.e., strongly coupled quark gluon plasma (SCQGP). It is remarkable that the widely used equation of state (EoS) of SCP in QED (quantum electrodynamics) very nicely fits lattice results on all QGP systems, with proper modifications to include color degrees of ...
Light-quark, heavy-quark systems
There are at least three reasons for studying the physics of B and D mesons. First, the Standard Model predicts observable signal of CP violation in decays of B mesons. Second, the rates for rare decays of heavy mesons are sensitive to departures from the Standard Model. Third, precise determination of the elements of the KM matrix is naturally performed through the study of decays of heavy mesons or baryons. This discussion focuses on the heavy-quark effective theory, with discussions on symmetries and meson decay constants. Further developments in this field of study are briefly introduced. 56 refs., 3 figs
Relativistic formulation of quark model
A relativistic model, which describes spin-orbital excitations of quark-antiquark bound system, is proposed. A formulation of the model provides the meson classification established in frame of the nonrelativistic quark model. 3 refs
Fedi, G.; CMS Collaboration
2016-07-01
The most recent results which concern the heavy quark hadrons done in the CMS experiment are reported. The searching area spans over the heavy quark spectroscopy, production cross sections, beauty meson decay properties, rare decays, and CP violation.
The Quark's Model and Confinement
Novozhilov, Yuri V.
1977-01-01
Quarks are elementary particles considered to be components of the proton, the neutron, and others. This article presents the quark model as a mathematical concept. Also discussed are gluons and bag models. A bibliography is included. (MA)
Richard, Jean-Marc
1994-01-01
We review the spectroscopy and some properties of hadrons containing two charmed quarks, or more generally, two heavy quarks. This includes heavy baryons such as $(bcu)$, and possible exotic multiquark states.
A Scaling Law for Quark Masses
Fritzsch, Harald; Özer, Alp Deniz
2004-01-01
We show that the observed quark masses seem to be consistent with a simple scaling law. Due to the precise values of the heavy quarks we are able to calculate the quark masses in the light quark sector. We discuss a possible value for the strange quark mass. We show that the u-type quark masses obey the scaling law very well.
Gauge-invariant approach to quark dynamics
Sazdjian, H.
2016-02-01
The main aspects of a gauge-invariant approach to the description of quark dynamics in the nonperturbative regime of quantum chromodynamics (QCD) are first reviewed. The role of the parallel transport operation in constructing gauge-invariant Green's functions is then presented, and the relevance of Wilson loops for the representation of the interaction is emphasized. Recent developments, based on the use of polygonal lines for the parallel transport operation, are presented. An integro-differential equation, obtained for the quark Green's function defined with a phase factor along a single, straight line segment, is solved exactly and analytically in the case of two-dimensional QCD in the large- N c limit. The solution displays the dynamical mass generation phenomenon for quarks, with an infinite number of branch-cut singularities that are stronger than simple poles.
Search for 4th generation quarks
Khalil, Sadia
2013-01-01
We present the results of searches for a new heavy 4th generation and vector-like quark using leptonic, and semileptonic final states comprising of electron(s) and/or muon(s) and jets. The full sample of 5 fb$^{-1}$ of pp collisions recorded with CMS experiment in 2011 at the center-of-mass energy of 7 TeV has been used. In leptonic final states, two same sign dilepton and trilepton channels have been explored. For semileptonic events, the search for heavy quarks is carried out using events with one lepton, and at least four jets with imbalance in transverse momenta, requiring at least one of the jet identified as originating from the fragmentation of a b-quark. No significant excess of events over Standard Model expectations is observed, therefore upper mass limits are set at 95\\% C.L.
Ion-induced quark-gluon implosion.
Frankfurt, L; Strikman, M
2003-07-11
We investigate nuclear fragmentation in the central proton-nucleus and nucleus-nucleus collisions at the energies of CERN LHC. Within the semiclassical approximation we argue that because of the fast increase with energy of the cross sections of soft and hard interactions each nucleon is stripped in the average process off "soft" partons and fragments into a collection of leading quarks and gluons with large p(t). Valence quarks and gluons are streaming in the opposite directions when viewed in the c.m. of the produced system. The resulting pattern of the fragmentation of the colliding nuclei leads to an implosion of the quark and gluon constituents of the nuclei. The nonequilibrium state produced at the initial stage in the nucleus fragmentation region is estimated to have densities >/=50 GeV/fm(3) at the LHC energies and probably >/=10 GeV/fm(3) at BNL RHIC. PMID:12906475
Gauge-invariant approach to quark dynamics
Sazdjian, H
2016-01-01
The main aspects of a gauge-invariant approach to the description of quark dynamics in the nonperturbative regime of QCD are first reviewed. In particular, the role of the parallel transport operation in constructing gauge-invariant Green's functions is presented, and the relevance of Wilson loops for the representation of the interaction is emphasized. Recent developments, based on the use of polygonal lines for the parallel transport operation, are then presented. An integro-differential equation is obtained for the quark Green's function defined with a phase factor along a single, straight line segment. It is solved exactly and analytically in the case of two-dimensional QCD in the large $N_c$ limit. The solution displays the dynamical mass generation phenomenon for quarks, with an infinite number of branch-cut singularities that are stronger than simple poles.
String Junction Model, Cluster Hypothesis, Penta-Quark Baryon and Tetra-Quark Meson
Imachi, Masahiro; Otsuki, Shoichiro
2007-01-01
Thirty years ago we proposed string junction model of hadrons and examined structure and reaction of hadrons including exotic ones. Since 2003 some attentions have been paid to exotic hadrons, especially to penta-quark baryon. By critically examining its theoretical analysis of Diakonov et. al, we introduce to our model "cluster hypothesis", which guarantees the classical and established picture that mass difference of hadrons among flavor multiplet members comes from that of the constituents. According to the hypothesis, the penta-quark baryon Theta^+ (S=+1) including a strange anti-quark s(bar), which is assigned to a member of 10^* representation of flavor SU(3), is heavier than non-strange members of the multiplet by Delta_s =130 ~ 150 MeV, the mass difference between the strange and non-strange quarks. In our model the mass of the penta-quark baryon is estimated as around 3 GeV. Quite recently, the Belle Collaboration has reported a candidate for tetra-quark meson, Z^+(4430 MeV). This gives us powerful c...
H Weigel
2003-11-01
In this talk I review studies of hadron properties in bosonized chiral quark models for the quark ﬂavor dynamics. Mesons are constructed from Bethe–Salpeter equations and baryons emerge as chiral solitons. Such models require regularization and I show that the two-fold Pauli–Villars regularization scheme not only fully regularizes the effective action but also leads the scaling laws for structure functions. For the nucleon structure functions the present approach serves to determine the regularization prescription for structure functions whose leading moments are not given by matrix elements of local operators. Some numerical results are presented for the spin structure functions.
Quark Orbital Angular Momentum
Burkardt Matthias
2015-01-01
Full Text Available Definitions of orbital angular momentum based on Wigner distributions are used as a framework to discuss the connection between the Ji definition of the quark orbital angular momentum and that of Jaffe and Manohar. We find that the difference between these two definitions can be interpreted as the change in the quark orbital angular momentum as it leaves the target in a DIS experiment. The mechanism responsible for that change is similar to the mechanism that causes transverse single-spin asymmetries in semi-inclusive deep-inelastic scattering.
This set of lectures deals with the transition from nuclear matter to quark matter. The reader will learn not only about the theory of quark- gluon plasmas but also how they are obtained in the laboratory through heavy-ion collisions or where they can be found in astrophysical objects such as compact stars. The book fills a gap between well-known textbook material and the research literature and is thus perfectly suited for postgraduate students who wish to enter this field, for lecturers looking for advanced material for their courses and for scientists in search of a modern source of reference on these topics
Smith, Martin C.; Willenbrock, Scott S.
1996-01-01
The top quark decays more quickly than the strong-interaction time scale, $\\lqcd^{-1}$, and might be expected to escape the effects of nonperturbative QCD. Nevertheless, the top-quark pole mass, like the mass of a stable heavy quark, is ambiguous by an amount proportional to $\\lqcd$.
Holographic Penta and Hepta Quark State in Confining Gauge Theories
Ghoroku, Kazuo; Taminato, Tomoki; Toyoda, Fumihiko
2010-01-01
We study a new embedding solutions of D5 brane in an asymptotic AdS${}_5\\times S^5$ space-time, which is dual to a confining $SU(N_c)$ gauge theory. The D5 brane is wrapped on $S^5$ as in the case of the vertex of holographic baryon. However, the solution given here is different from the usual baryon vertex in the point that it couples to $k$-anti-quarks and $N_c+k$ quarks on the opposite two points of $S^5$, the north and south poles, respectively. The total quark number of this state is preserved as $N_c$ when minus one is assigned to anti-quark, then it forms a color singlet like the baryon. However, this includes anti-quarks and quarks, whose number is larger than that of the baryon. When we set as $N_c=3$, we find the so called penta and hepta-quark states. We study the dynamical properties of these states by solving the vertex and string configurations for such states. The mass spectra of these states and the tension of the stretched vertex are estimated, and they are compared with that of the baryon.
Determination of the width of the top quark
Abazov, V M; Abolins, M; Acharya, B S; Adams, M; Adams, T; Alexeev, G D; Alkhazov, G; Altona, A; Alverson, G; Alves, G A; Ancu, L S; Aoki, M; Arnoud, Y; Arov, M; Askew, A; \\degAsman, B; Atramentov, O; Avila, C; BackusMayes, J; Badaud, F; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, S; Barberis, E; Baringer, P; Barreto, J; Bartlett, J F; Bassler, U; Bazterra, V; Beale, S; Bean, A; Begalli, M; Begel, M; Belanger-Champagne, C; Bellantoni, L; Beri, S B; Bernardi, G; Bernhard, R; Bertram, I; Besan?con, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Blazey, G; Blessing, S; Bloom, K; Boehnlein, A; Boline, D; Bolton, T A; Boos, E E; Borissov, G; Bose, T; Brandt, A; Brandt, O; Brock, R; Brooijmans, G; Bross, A; Brown, D; Brown, J; Bu, X B; Buchholz, D; Buehler, M; Buescher, V; Bunichev, V; Burdinb, S; Burnett, T H; Buszello, C P; Calpas, B; Camacho-P?erez, E; Carrasco-Lizarraga, M A; Casey, B C K; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K M; Chandra, A; Chen, G; Chevalier-Th?ery, S; Cho, D K; Cho, S W; Choi, S; Choudhary, B; Christoudias, T; Cihangir, S; Claes, D; Clutter, J; Cooke, M; Cooper, W E; Corcoran, M; Couderc, F; Cousinou, M -C; Croc, A; Cutts, D; ?Cwiok, M; Das, A; Davies, G; De, K; de Jong, S J; De La Cruz-Burelo, E; D?eliot, F; Demarteau, M; Demina, 47 R; Denisov, D; Denisov, S P; Desai, S; DeVaughan, K; Diehl, H T; Diesburg, M; Dominguez, A; Dorland, T; Dubey, A; Dudko, L V; Duggan, D; Duperrin, A; Dutt, S; Dyshkant, A; Eads, M; Edmunds, D; Ellison, J; Elvira, V D; Enari, Y; Eno, S; Evans, H; Evdokimov, A; Evdokimov, V N; Facini, G; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Fortner, M; Fox, H; Fuess, S; Gadfort, T; Garcia-Bellido, A; Gavrilov, V; Gay, P; Geist, W; Geng, W; Gerbaudo, D; Gerber, C E; Gershtein, Y; Ginther, G; Golovanov, G; Goussiou, A; Grannis, P D; Greder, S; Greenlee, H; Greenwood, Z D; Gregores, E M; Grenier, G; Gris, Ph; Grivaz, J -F; Grohsjean, A; Gr?unendahl, S; Gr?unewald, M W; Guo, F; Guo, J; Gutierrez, G; Gutierrez, P; Haasc, A; Hagopian, S; Haley, J; Han, L; Harder, K; Harel, A; Hauptman, J M; Hays, J; Head, T; Hebbeker, T; Hedin, D; Hegab, H; Heinson, A P; Heintz, U; Hensel, C; La Cruz, I Heredia-De; Herner, K; Hesketh, G; Hildreth, M D; Hirosky, R; Hoang, T; Hobbs, J D; Hoeneisen, B; Hohlfeld, M; Hossain, S; Hubacek, Z; Huske, N; Hynek, V; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jaffr?e, M; Jain, S; Jamin, D; Jesik, R; Johns, K; Johnson, M; Johnston, D; Jonckheere, A; Jonsson, P; Joshi, J; Justed, A; Kaadze, K; Kajfasz, E; Karmanov, D; Kasper, P A; Katsanos, I; Kehoe, R; Kermiche, S; Khalatyan, N; Khanov, A; Kharchilava, A; Kharzheev, Y N; Khatidze, D; Kirby, M H; Kohli, J M; Kozelov, A V; Kraus, J; Kumar, A; Kupco, A; Kur?ca, T; Kuzmin, V A; Kvita, J; Lammers, S; Landsberg, G; Lebrun, P; Lee, H S; Lee, S W; Lee, W M; Lellouch, J; Li, L; Li, Q Z; Lietti, S M; Lim, J K; Lincoln, D; Linnemann, J; Lipaev, V V; Lipton, R; Liu, Y; Liu, Z; Lobodenko, A; Lokajicek, M; Love, P; Lubatti, H J; Luna-Garciae, R; Lyon, A L; Maciel, A K A; Mackin, D; Madar, R; Maga?na-Villalba, R; Malik, S; Malyshev, V L; Maravin, Y; Mart?\\inez-Ortega, J; McCarthy, R; McGivern, C L; Meijer, M M; Melnitchouk, A; Menezes, D; Mercadante, P G; Merkin, M; Meyer, A; Meyer, J; Mondal, N K; Muanza, G S; Mulhearn, M; Nagy, E; Naimuddin, M; Narain, M; Nayyar, R; Neal, H A; Negret, J P; Neustroev, P; Novaes, S F; Nunnemann, T; Obrant, G; Orduna, J; Osman, N; Osta, J; Garz?on, G J Otero y; Owen, 1 M; Padilla, M; Pangilinan, M; Parashar, N; Parihar, V; Park, S K; Parsons, J; Partridgec, R; Parua, N; Patwa, A; Penning, B; Perfilov, M; Peters, K; Peters, Y; Petrillo, G; P?etroff, P; Piegaia, R; Piper, J; Pleier, M -A; Podesta-Lermaf, P L M; Podstavkov, V M; Pol, M -E; Polozov, P; Popov, A V; Prewitt, M; Price, D; Protopopescu, S; Qian, J; Quadt, A; Quinn, B; Rangel, M S; Ranjan, K; Ratoff, P N; Razumov, I; Renkel, P; Rich, P; Rijssenbeek, M; Ripp-Baudot, I; Rizatdinova, F; Rominsky, M; Royon, C; Rubinov, P; Ruchti, R; Safronov, G; Sajot, G; S?anchez-Hern?andez, A; Sanders, M P; Sanghi, B; Santos, A S; Savage, G; Sawyer, L; Scanlon, T; Schamberger, R D; Scheglov, Y; Schellman, H; Schliephake, T; Schlobohm, S; Schwanenberger, C; Schwienhorst, R; Sekaric, J; Severini, H; Shabalina, E; Shary, V; Shchukin, A A; Shivpuri, R K; Simak, V; Sirotenko, V; Skubic, P; Slattery, P; Smirnov, D; Smith, K J; Snow, G R; Snow, J; Snyder, S; S?oldner-Rembold, S; Sonnenschein, L; Sopczak, A; Sosebee, M; Soustruznik, K; Spurlock, B; Stark, J; Stolin, V; Stoyanova, D A; Strauss, E; Strauss, M; Strom, D; Stutte, L; Svoisky, P; Takahashi, M; Tanasijczuk, A; Taylor, W; Titov, M; Tokmenin, V V; Tsybychev, D; Tuchming, B; Tully, C; Tuts, P M; Uvarov, L; Uzunyan, S Uvarov S; Van Kooten, R; van Leeuwen, W M; Varelas, N; Varnes, E W; Vasilyev, I A; Verdier, P; Vertogradov, L S; Verzocchi, M; Vesterinen, M; Vilanova, D; Vint, P; Vokac, P; Wahl, H D; Wang, M H L S; Warchol, J; Watts, G; Wayne, M; Weberg, M; Welty-Rieger, L; Wetstein, M; White, A; Williams, D Wicke M R J; Wilson, G W; Wimpenny, S J; Wobisch, M; Wood, D R; Wyatt, T R; Xie, Y; Xu, C; Yacoob, S; Yamada, R; Yang, W -C; Yasuda, T; Yatsunenko, Y A; Ye, Z; Yin, H; Yip, K; Yoo, H D; Youn, S W; Yu, J; Zelitch, S; Zhao, T; Zhou, B; Zhu, J; Zielinski, M; Zieminska, D; Zivkovic, L
2010-01-01
We extract the total width of the top quark, Gamma_t, from the partial decay width Gamma(t -> W b) measured using the t-channel cross section for single top quark production and from the branching fraction B(t -> W b) measured in ttbar events using up to 2.3 fb^-1 of integrated luminosity collected by the D0 Collaboration at the Tevatron ppbar Collider. The result is Gamma_t = 1.99 +0.69 -0.55 GeV, which translates to a top-quark lifetime of tau_t = (3.3 +1.3 -0.9) x 10^-25 s. Assuming a high mass fourth generation b' quark and unitarity of the four-generation quark-mixing matrix, we set the first upper limit on |Vtb'| < 0.63 at 95% C.L.
Continuum estimate of the heavy quark momentum diffusion coefficient $\\kappa$
Kaczmarek, Olaf
2014-01-01
Among quantities playing a central role in the theoretical interpretation of heavy ion collision experiments at RHIC and LHC are so-called transport coefficients. Out of those heavy quark diffusion coefficients play an important role e.g. for the analysis of the quenching of jets containing c or b quarks (D or B mesons) as observed at RHIC and LHC. We report on a lattice investigation of heavy quark momentum diffusion within pure SU(3) plasma above the deconfinement transition with the quarks treated to leading order in the heavy mass expansion. We measure the relevant colour-electric Euclidean correlator and based on several lattice spacings perform the continuum extrapolation. This extends our previous studies progressing towards a removal of lattice artifacts and a physical interpretation of the results. We find that the correlation function clearly exceeds its perturbative counterpart which suggests that at temperatures just above the critical one, non-perturbative interactions felt by the heavy quarks ar...
Helicity-dependent generalized parton distributions and composite constituent quarks
Scopetta, S; Scopetta, Sergio; Vento, Vicente
2004-01-01
An approach recently proposed to calculate the nucleon generalized parton distributions (GPDs) in a constituent quark model (CQM) scenario, considering the constituent quarks as complex systems, is used here to obtain helicity-dependent GPDs. They are obtained from the wave functions of the non relativistic CQM of Isgur and Karl, convoluted with the helicity-dependent GPDs of the constituent quarks themselves. The latter are modelled by using the polarized structure functions of the constituent quark, the double distribution representation of GPDs, and a recently proposed phenomenological constituent quark form factor. The present approach permits to access a kinematical range corresponding to both the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi and the Efremov-Radyushkin-Brodsky-Lepage regions, for small values of the momentum transfer and of the skewedness parameter. In this kinematical region, the present calculation represents a prerequisite for the evaluation of cross sections relevant to deeply virtual C...
C P Singh
2000-04-01
Recent trends in the research of quark gluon plasma (QGP) are surveyed and the current experimental and theoretical status regarding the properties and signals of QGP is reported. We hope that the experiments commencing at relativistic heavy-ion collider (RHIC) in 2000 will provide a glimpse of the QGP formation.
New experimental and theoretical developments in heavy quark spectroscopy are reviewed. From studies of J/psi decays, the eta' is found to have some ''glue'' or other inert component, while the iota (a glueball candidate) probably contains some quarks as well. The xi(2.2) persists in new Mark III data, but is not seen by the DM2 collaboration. The production of charmonium states by anti pp reactions is reviewed. First evidence for a P- wave charmed meson, D(2420), has been presented by the ARGUS group. Radiative UPSILON decay studies fail to confirm the zeta(8.3) and begin to place useful limits on Higgs bosons. First results from an experiment at Fermilab on low-background hadronic production of UPSILON states are shown. Accurate measurements of chi/sub b/(1P) masses by the ARGUS collaboration are noted, and interpreted as favoring scalar quark confinement. Studies of t and other heavy quarks will probe the q anti q interaction below 0.05 fm, are likely to be strongly affected by t anti t-Z interference, and can provide varied information on Higgs bosons. 144 refs., 21 figs
Quark-meson coupling model with short-range quark-quark interactions
Saito, Koichi; Tsushima, Kazuo
2000-01-01
Short-range quark-quark correlations are introduced into the quark-meson coupling (QMC) model phenomenologically. We study the effect of the correlations on the structure of the nucleon in dense nuclear matter. With the addition of correlations, the saturation curve for symmetric nuclear matter is much improved at high density.
Chemical Evolution of Strongly Interacting Quark-Gluon Plasma
At very initial stage of relativistic heavy ion collisions a wave of quark-gluon matter is produced from the break-up of the strong color electric field and then thermalizes at a short time scale (~1 fm/c). However, the quark-gluon plasma (QGP) system is far out of chemical equilibrium, especially for the heavy quarks which are supposed to reach chemical equilibrium much late. In this paper a continuing quark production picture for strongly interacting QGP system is derived, using the quark number susceptibilities and the equation of state; both of them are from the results calculated by the Wuppertal-Budapest lattice QCD collaboration. We find that the densities of light quarks increase by 75% from the temperature T=400 MeV to T=150 MeV, while the density of strange quark annihilates by 18% in the temperature region. We also offer a discussion on how this late production of quarks affects the final charge-charge correlations
Years after its discovery in 1995 by CDF and D0, the top quark still undergoes intense investigations at the Tevatron. Using up to the full Run II data sample, new measurements of top quark production and properties by the D0 Collaboration are presented. In particular, the first observation of single top quark s-channel production, the measurement of differential t t-bar distributions, forward-backward t t-bar asymmetry, a new measurement of the top quark mass, and a measurement of the top quark charge are discussed
Beauty-quark and charm-quark pair production asymmetries at LHCb
Gauld, Rhorry; Haisch, Ulrich; Pecjak, Ben D.; Re, Emanuele
2015-08-01
The LHCb Collaboration has recently performed a first measurement of the angular production asymmetry in the distribution of beauty quarks and antiquarks at a hadron collider. We calculate the corresponding standard model prediction for this asymmetry at fixed order in perturbation theory. Our results show good agreement with the data, which are provided differentially for three bins in the invariant mass of the b b ¯ system. We also present similar predictions for both beauty-quark and charm-quark final states within the LHCb acceptance for a collision energy of √{s }=13 TeV . We finally point out that a measurement of the ratio of the b b ¯ and c c ¯ cross sections may be useful for experimentally validating charm-tagging efficiencies.
Weak decays of the Bc meson to Bs and B mesons in the relativistic quark model
Semileptonic and non-leptonic decays of the Bc meson to Bs and B mesons, caused by the c→s,d quark transitions, are studied in the framework of the relativistic quark model. The heavy quark expansion in inverse powers of the active c and spectator anti b quark is used to simplify calculations while the final s and d quarks in the Bs and B mesons are treated relativistically. The decay form factors are explicitly expressed through the overlap integrals of the meson wave functions in the whole accessible kinematical range. The obtained results are compared with the predictions of other approaches. (orig.)
Quark-Number Susceptibility at Finite Chemical Potential and Zero Temperature
HE Deng-Ke; JIANG Yu; FENG Hong-Tao; SUN Wei-Min; ZONG Hong-Shi
2008-01-01
We give a direct method for calculating the quark-number susceptibility at finite chemical potential and zero temperature.In this approach the quark-number susceptibility is totally determined by G[μ](p)(the dressed quark propagator at finite chemical potential μ).By applying the general result in our previous study[Phys.Rev.C 71(2005)015205,034901,73 (2006) 016004] G[μ](p)is calculated from the model quark propagator proposed by Pagels and Stokar[Phys.Rev.D 20(1979)2947].The full analytic expression of the quark-number susceptibility at finite μ and zero T is obtained.
Strange quark matter and quark stars with the Dyson-Schwinger quark model
Chen, H; Schulze, H -J
2016-01-01
We calculate the equation of state of strange quark matter and the interior structure of strange quark stars in a Dyson-Schwinger quark model within rainbow or Ball-Chiu vertex approximation. We emphasize constraints on the parameter space of the model due to stability conditions of ordinary nuclear matter. Respecting these constraints, we find that the maximum mass of strange quark stars is about 1.9 solar masses, and typical radii are 9--11 km. We obtain an energy release as large as $3.6 \\times 10^{53}\\,\\text{erg}$ from conversion of neutron stars into strange quark stars.
Top quark decays in extended models
We evaluate the FCNC decays t → H0 + c at tree-level and t → γ + c at one-loop level in the context of Alternative Left-Right symmetric Models (ALRM) with extra isosinglet heavy fermions; in the first case, FCNC decays occurs at tree-level and they are only suppressed by the mixing between ordinary top and charm quarks. (author)
Enhancement of new physics signal sensitivity with mistagged charm quarks
Kim, Doojin; Park, Myeonghun
2016-07-01
We investigate the potential for enhancing search sensitivity for signals having charm quarks in the final state, using the sizable bottom-mistagging rate for charm quarks at the LHC. Provided that the relevant background processes contain light quarks instead of charm quarks, the application of b-tagging on charm quark-initiated jets enables us to reject more background events than signal ones due to the relatively small mistagging rate for light quarks. The basic idea is tested with two rare top decay processes: i) t → ch → cb b bar and ii) t → bH+ → b b bar c where h and H+ denote the Standard Model-like higgs boson and a charged higgs boson, respectively. The major background source is a hadronic top quark decay such as t → bW+ → b s bar c. We test our method with Monte Carlo simulation at the LHC 14 TeV, and find that the signal-over-background ratio can be increased by a factor of O (6- 7) with a suitably designed (heavy) flavor tagging algorithm and scheme.
Enhancement of new physics signal sensitivity with mistagged charm quarks
Doojin Kim
2016-07-01
Full Text Available We investigate the potential for enhancing search sensitivity for signals having charm quarks in the final state, using the sizable bottom-mistagging rate for charm quarks at the LHC. Provided that the relevant background processes contain light quarks instead of charm quarks, the application of b-tagging on charm quark-initiated jets enables us to reject more background events than signal ones due to the relatively small mistagging rate for light quarks. The basic idea is tested with two rare top decay processes: i t→ch→cbb¯ and ii t→bH+→bb¯c where h and H+ denote the Standard Model-like higgs boson and a charged higgs boson, respectively. The major background source is a hadronic top quark decay such as t→bW+→bs¯c. We test our method with Monte Carlo simulation at the LHC 14 TeV, and find that the signal-over-background ratio can be increased by a factor of O(6–7 with a suitably designed (heavy flavor tagging algorithm and scheme.
The alchemy of the production of states containing the heavy quarks in hadron-hadron or photon-hadron collisions offers an opportunity to study hadronic dynamics in a manner not readily available elsewhere. The focus is on an approach based on a simple interpretation of QCD developed at Illinois and Argonne. This approach seems to offer the possibility of forming a connection between the dynamics of heavy particle production and recent developments in the theory of large-transverse-momentum processes. It is very interesting to see how the connection with large-P/sub T/ emerges from a fairly reasonable model. In the model discussed, the production of heavy quarks in photoproduction is thought of as arising from diagrams which constitute the lowest-order-QCD process available and are considered applicable either for a real photon or for a virtual photon arising from inelastic lepton scattering. 25 references
Smith, F T
1997-01-01
From sets and simple operations on sets, a Feynman Checkerboard physics model is constructed that allows computation of force strength constants and constituent mass ratios of elementary particles, giving a tree level constituent Truth Quark (top quark) mass of roughly 130 GeV, which is (in my opinion) supported by dileptonic events and some semileptonic events. See http://galaxy.cau.edu/tsmith/HDFCmodel.html and http://www.innerx.net/personal/tsmith/HDFCmodel.html This model is similar to a Lie algebra D4-D5-E6 model: Chapter 1 - Introduction. Chapter 2 - From Sets to Clifford Algebras. Chapter 3 - Octonions and E8 lattices. Chapter 4 - E8 spacetime and particles. Chapter 5 - HyperDiamond Lattices. Chapter 6 - Internal Symmetry Space. Chapter 7 - Feynman Checkerboards. Chapter 8 - Charge = Amplitude to Emit Gauge Boson. Chapter 9 - Mass = Amplitude to Change Direction. Chapter 10 - Protons, Pions, and Physical Gravitons.
The Multimedia Project Quarked!
Bean, Alice
2011-01-01
Can exposure to fundamental ideas about the nature of matter help motivate children in math and science and support the development of their understanding of these ideas later? Physicists, designers, and museum educators at the University of Kansas created the Quarked!(tm) Adventures in the subatomic Universe project to provide an opportunity for youth to explore the subatomic world in a fun and user friendly way. The project components include a website (located at http://www.quarked.org) and hands-on education programs. These are described and assessment results are presented. Questions addressed include the following. Can you engage elementary and middle school aged children with concepts related to particle physics? Can young children make sense of something they can't directly see? Do teachers think the material is relevant to their students?
Supersymmetric top quark decays
The supersymmetric decays of the top quark into charged Higgs plus bottom, t → H+b, and into the supersymmetric partner of the top (u1) plus the lightest neutralino (χ10), t → u1χ10, are discussed within the framework of the Minimal Supersymmetric Standard Model with radiatively induced breaking of the gauge group SU(2) x U(1). The possibility of detecting these decays at present, i.e. given the available bounds on supersymmetric parameters, is compared with the situation a Next e+e- Linear Collider would face if supersymmetric particles were still undiscovered at LEP II. The indirect implications for t → H+b and t → u1χ10 of a measurement of the bottom quark decay b → sγ at the Standard Model level are taken into account. (orig.)
Heavy-baryon quark model picture from lattice QCD
Vijande, J; Garcilazo, H
2015-01-01
The ground state and excited spectra of baryons containing three identical heavy quarks, $b$ or $c$, have been recently calculated in nonperturbative lattice QCD. The energy of positive and negative parity excitations has been determined with high precision. Lattice results constitute a unique opportunity to learn about the quark-confinement mechanism as well as elucidating our knowledge about the nature of the strong force. We analyze the nonperturbative lattice QCD results by means of heavy-quark static potentials derived using SU(3) lattice QCD. We make use of different numerical techniques for the three-body problem.
Anomalous single top quark production at the LHC
Najafabadi, M. Mohammadi; Pooya, G.
2010-09-01
The anomalous top quark interactions with gluon (tug, tcg) allow the production of single top quarks at the Large Hadron Collider (LHC). Using the angular distribution of the charged lepton from the W boson in the top decay, we show that with the data of 10 fb-1 of integrated luminosity and in the collisions with the center of mass energy of 14 TeV, the anomalous up and charm quarks coupling parameters κu, c/Λ can be measured down to 0.005 and 0.007 TeV-1, respectively.
Embedding of leptons and quarks in octonionic structures
All leptons and quarks are united into the Dirac spinor hyperfield constructed over systems of nonassociative postoctonium numbers obtained by the Cayley-Dickson iterative process for octonions. Spontaneously broken G2xSU(3)LxU(1) gauge symmetry is formulted and the colour SU(3)c quark symmetry is explained as the unbroken subgroup of G2, the broken automorphism group of postoctonium hypernumbers. The right eigenvalues of the electric charges of leptons and quarks (of two generations) are obtained from the requirement of the invariance of trilinear associative form under the phase-transformation. 8 refs
Quark-antiquark pairs in the quark model
We study the structure of the spin of the proton and the Λ hyperon in an unquenched quark model which incorporates the effects of quark-antiquark pair creation via a microscopic, QCD-inspired, quark-antiquark creation mechanism. It is shown that the inclusion of the qq-bar pairs leads to a sizeable contribution of the orbital angular momentum to the spin of the proton and the Λ hyperon.
Simula, Silvano
2001-01-01
The application of relativistic constituent quark models to the evaluation of the electromagnetic properties of the nucleon and its resonances is addressed. The role of the pair creation process in the Feynmann triangle diagram is discussed and the importance both of choosing the light-front formalism and of using a Breit frame where the plus component of the four-momentum transfer is vanishing, is stressed. The nucleon elastic form factors are calculated free of spurious effects related to t...
Santopinto, E
2015-01-01
In this contribution, we briefly discuss the results for charmonium and bottomonium spectra with self-energy corrections in the unquenched quark model, due to the coupling to the meson-meson continuum. The UQM formalism can be extended to include also the effects of hybrid mesons, i.e. hybrid loops. Finally, we discuss the results of a calculation of hybrid mesons spectrum in Coulomb Gauge QCD.
Pallante, E.; R. Petronzio(INFN RM2)
1994-01-01
We construct an effective Lagrangian for low energy hadronic interactions through an infinite expansion in inverse powers of the low energy cutoff Î›Ï‡ of all possible chiral invariant non-renormalizable interactions between quarks and mesons degrees of freedom arising from the bosonization of a general Nambu-Jona Lasinio type Lagrangian including all multiquark effective interactions. We restrict our analysis to the leading terms in the 1/Nc expansion and to the divergent part of the resonan...
Rafelski, Johann
2007-01-01
Matter in its present form was formed when our Universe emerged from the quark-gluon phase (QGP) at about 30mus into its evolution. To explore this early period in the laboratory, we study highly excited matter formed in relativistic heavy ion collision experiments: heavy nuclei crash into each other, and form compressed and energetically excited nuclear matter, resembling in its key features the stuff which filled the early Universe. In these experiments we further explore the physics of the...
Nayak, Tapan; Sarkar, Sourav
2014-01-01
At extremely high temperatures and densities, protons and neutrons may dissolve into a "soup" of quarks and gluons, called the Quark-Gluon Plasma (QGP). For a few microseconds, shortly after the Big Bang, the Universe was filled with the QGP matter. The search and study of Quark-Gluon Plasma (QGP) is one of the most fundamental research topics of our times. The QGP matter has been probed by colliding heavy ions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory, New York and the Large Hadron Collider at CERN, Geneva. By colliding heavy-ions at a speed close to that of light, scientists aim to obtain - albeit over a tiny volume of the size of a nucleus and for an infinitesimally short instant - a QGP state. This QGP state can be observed by dedicated experiments, as it reverts to hadronic matter through expansion and cooling. This volume presents some of the current theoretical and experimental understandings in the field of QGP.
Full text: Recently, the question of the charm quark contribution to the thermodynamics of the QGP has received some attention. In particular at the high temperatures that can be reached in heavy ion collisions at the LHC a better understanding the thermal contribution of charm to bulk thermodynamics will become relevant. Lattice QCD can provide an answer to this question, but fully dynamical, 4-flavor ensembles do not yet exist. The large charm quark mass also is expected to introduce additional cut-off effects. Nonetheless, as an exploratory study, we recently calculated the second-, fourth- and sixth-order susceptibilities for the charm quark in the partially quenched approximation using the p4 action. We found that our results were in good agreement with perturbative estimates for these quantities. We also studied correlations between charm and the lighter flavors. We compared these quantities to simple quasiparticle and resonance gas models. Lastly, we shall also comment on calculations of the charm's contribution to the pressure within the partially quenched approximation. (author)
Fields, symmetries, and quarks
'Fields, symmetries, and quarks' covers elements of quantum field theory, symmetries, gauge field theories and phenomenological descriptions of hadrons, with special emphasis on topics relevant to nuclear physics. It is aimed at nuclear physicists in general and at scientists who need a working knowledge of field theory, symmetry principles of elementary particles and their interactions and the quark structure of hadrons. The book starts out with an elementary introduction into classical field theory and its quantization. As gauge field theories require a working knowledge of global symmetries in field theories this topic is then discussed in detail. The following part is concerned with the general structure of gauge field theories and contains a thorough discussion of the still less widely known features of Non-Abelian gauge field theories. Quantum Chromodynamics (QCD), which is important for the understanding of hadronic matter, is discussed in the next section together with the quark compositions of hadrons. The last two chapters give a detailed discussion of phenomenological bag-models. The MIT bag is discussed, so that all theoretical calculations can be followed step by step. Since in all other bag-models the calculational methods and steps are essentially identical, this chapter should enable the reader to actually perform such calculations unaided. A last chapter finally discusses the topological bag-models which have become quite popular over the last few years. (orig.)
Color Superconducting Quark Matter in Neutron Stars
Heiselberg, H.
1999-01-01
Color superconductivity in quark matter is studied for electrically charge neutral neutron star matter in $\\beta$-equilibrium. Both bulk quark matter and mixed phases of quark and nuclear matter are treated. The electron chemical potential and strange quark mass affect the various quark chemical potentials and therefore also the color superconductivity due to dicolor pairing or color-flavor locking.
Top Quark Physics -- a Popular Review
Lampe, Bodo
1995-01-01
The top quark has been discovered at FERMILAB last year. The following features of top quark physics will be discussed in this article: the top quark in the standard model production and decay of the top quark in proton collisions (direct evidence for top) virtual effects of top quarks in electroweak observables (indirect evidence for top)
Parametrization of Fully Dressed Quark Propagator
MA Wei-Xing; ZHU Ji-Zhen; ZHOU Li-Juan; SHEN Peng-Nian; HU Zhao-Hui
2005-01-01
Based on an extensive study of the Dyson-Schwinger equations for a fully dressed quark propagator in the "rainbow" approximation, a parametrized form of the quark propagator is suggested. The corresponding quark selfform of the quark propagator proposed in this work describes a confining quark propagation, and is quite convenient to be used in any numerical calculations.
Messner, R. [Stanford Univ., CA (United States)
1997-01-01
This report covers preliminary measurements from SLD on heavy quark production at the Z{sup 0}, using 150,000 hadronic Z{sup 0} decays accumulated during the 1993-1995 runs. A measurement of R{sub b} with a lifetime double tag is presented. The high electron beam polarization of the SLC is employed in the direct measurement of the parity-violating parameters A{sub b} and A{sub c} by use of the left-right forward-backward asymmetry. The lifetimes of B{sup +} and B{sup 0} mesons have been measured by two analyses. The first identifies semileptonic decays of B mesons with high (p,p{sub t}) leptons; the second analysis isolates a sample of B meson decays with a two-dimensional impact parameter tag and reconstructs the decay length and charge using a topological vertex reconstruction method.
The structure of this report is as follows. Section 2 looks at quarks, starting with a review of previous experimental searches and continuing with the phenomenology of the different varieties of quark which are mentioned above. We study the direct production and detection of conventional fractionally charged quarks, of strongly interacting coloured quarks with appetite, and of quarks with indeterminate mass or integer charge. We also examine the search for indirect manifestations of quarks with non-standard colour, or with substructure. Section 3 deals with monopoles, starting with a summary of motivations for their existence, and their expected properties, as well as a review of the previous searches. It continues with a survey of the different ways of looking for conventional magnetic monopoles and other possible topological excitations in gauge theories. (orig./HSI)
Validity of Parametrized Quark Propagator
ZHU Ji-Zhen; ZHOU Li-Juan; MA Wei-Xing
2005-01-01
Based on an extensively study of the Dyson-Schwinger equations for a fully dressed quark propagator in the "rainbow" approximation, a parametrized fully dressed quark propagator is proposed in this paper. The parametrized propagator describes a confining quark propagator in hadron since it is analytic everywhere in complex p2-plane and has no Lemmann representation. The validity of the new propagator is discussed by comparing its predictions on selfenergy functions Af(p2), Bf(p2) and effective mass Mf(p2) of quark with flavor f to their corresponding theoretical results produced by Dyson-Schwinger equations. Our comparison shows that the parametrized quark propagator is a good approximation to the fully dressed quark propagator given by the solutions of Dyson-Schwinger equations in the rainbow approximation and is convenient to use in any theoretical calculations.
Validity of Parametrized Quark Propagator
ZHUJi-Zhen; ZHOULi-Juan; MAWei-Xing
2005-01-01
Based on an extensively study of the Dyson-Schwinger equations for a fully dressed quark propagator in the “rainbow”approximation, a parametrized fully dressed quark propagator is proposed in this paper. The parametrized propagator describes a confining quark propagator in hadron since it is analytic everywhere in complex p2-plane and has no Lemmann representation. The validity of the new propagator is discussed by comparing its predictions on selfenergy functions A/(p2), Bl(p2) and effective mass M$(p2) of quark with flavor f to their corresponding theoretical results produced by Dyson-Schwinger equations. Our comparison shows that the parametrized quark propagator is a good approximation to the fully dressed quark propagator given by the solutions of Dyson-Schwinger equations in the rainbow approximation and is convenient to use in any theoretical calculations.
First determination of the electric charge of the top quark
Abazov, V M; Abolins, M; Acharya, B S; Adams, M; Adams, T; Agelou, M; Ahn, S H; Ahsan, M; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Anastasoaie, M; Andeen, T; Anderson, S; Andrieu, B; Anzelc, M S; Arnoud, Y; Arov, M; Askew, A; Åsman, B; Assis-Jesus, A C S; Atramentov, O; Autermann, C; Avila, C; Ay, C; Badaud, F; Baden, A; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, P; Banerjee, S; Barberis, E; Bargassa, P; Baringer, P; Barnes, C; Barreto, J; Bartlett, J F; Bassler, U; Bauer, D; Bean, A; Begalli, M; Begel, M; Belanger-Champagne, C; Bellantoni, L; Bellavance, A; Benítez, J A; Beri, S B; Bernardi, G; Bernhard, R; Berntzon, L; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Binder, M; Biscarat, C; Black, K M; Blackler, I; Blazey, G; Blekman, F; Blessing, S; Bloch, D; Bloom, K; Blumenschein, U; Böhnlein, A; Boeriu, O; Bolton, T A; Borissov, G; Bos, K; Bose, T; Brandt, A; Brock, R; Brooijmans, G; Bross, A; Brown, D; Buchanan, N J; Buchholz, D; Bühler, M; Büscher, V; Burdin, S; Burke, S; Burnett, T H; Busato, E; Buszello, C P; Butler, J M; Calfayan, P; Calvet, S; Cammin, J; Caron, S; Carvalho, W; Casey, B C K; Cason, N M; Castilla-Valdez, H; Chakraborty, D; Chan, K M; Chandra, A; Charles, F; Cheu, E; Chevallier, F; Cho, D K; Choi, S; Choudhary, B; Christofek, L; Claes, D; Clement, B; Clément, C; Coadou, Y; Cooke, M; Cooper, W E; Coppage, D; Corcoran, M; Cousinou, M C; Cox, B; Crepe-Renaudin, S; Cutts, D; Cwiok, M; Da Motta, H; Das, A; Das, M; Davies, B; Davies, G; Davis, G A; De, K; de Jong, P; De Jong, S J; De La Cruz-Burelo, E; De Oliveira Martins, C; Degenhardt, J D; Déliot, F; Demarteau, M; Demina, R; Demine, P; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Doidge, M; Dominguez, A; Dong, H; Dudko, L V; Duflot, L; Dugad, S R; Duggan, D; Duperrin, A; Dyer, J; Dyshkant, A; Eads, M; Edmunds, D; Edwards, T; Ellison, J; Elmsheuser, J; Elvira, V D; Eno, S; Ermolov, P; Evans, H; Evdokimov, A; Evdokimov, V N; Fatakia, S N; Feligioni, L; Ferapontov, A V; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Fleck, I; Ford, M; Fortner, M; Fox, H; Fu, S; Fuess, S; Gadfort, T; Galea, C F; Gallas, E; Galyaev, E; García, C; García-Bellido, A; Gardner, J; Gavrilov, V; Gay, A; Gay, P; Gelé, D; Gelhaus, R; Gerber, C E; Gershtein, Yu; Gillberg, D; Ginther, G; Gollub, N; Gómez, B; Goussiou, A; Grannis, P D; Greenlee, H; Greenwood, Z D; Gregores, E M; Grenier, G; Gris, P; Grivaz, J F; Grünendahl, S; Grünewald, M W; Guo, F; Guo, J; Gutíerrez, G; Gutíerrez, P; Haas, A; Hadley, N J; Haefner, P; Hagopian, S; Haley, J; Hall, I; Hall, R E; Han, L; Hanagaki, K; Hansson, P; Harder, K; Harel, A; Harrington, R; Hauptman, J M; Hauser, R; Hays, J; Hebbeker, T; Hedin, D; Hegeman, J G; Heinmiller, J M; Heinson, A P; Heintz, U; Hensel, C; Herner, K; Hesketh, G; Hildreth, M D; Hirosky, R; Hobbs, J D; Hoeneisen, B; Hoeth, H; Hohlfeld, M; Hong, S J; Hooper, R; Houben, P; Hu, Y; Hubacek, Z; Hynek, V; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jaffré, M; Jain, S; Jakobs, K; Jarvis, C; Jenkins, A; Jesik, R; Johns, K; Johnson, C; Johnson, M; Jonckheere, A; Jonsson, P; Juste, A; Käfer, D; Kahn, S; Kajfasz, E; Kalinin, A M; Kalk, J M; Kalk, J R; Kappler, S; Karmanov, D; Kasper, J; Kasper, P; Katsanos, I; Kau, D; Kaur, R; Kehoe, R; Kermiche, S; Khalatyan, N; Khanov, A; Kharchilava, A I; Kharzheev, Yu M; Khatidze, D; Kim, H; Kim, T J; Kirby, M H; Klima, B; Kohli, J M; Konrath, J P; Kopal, M; Korablev, V M; Kotcher, J; Kothari, B; Koubarovsky, A; Kozelov, A V; Kozminski, J; Krop, D; Kryemadhi, A; Kühl, T; Kumar, A; Kunori, S; Kupco, A; Kurca, T; Kvita, J; Lammers, S; Landsberg, G L; Lazoflores, J; Le Bihan, A C; Lebrun, P; Lee, W M; Leflat, A; Lehner, F; Lesne, V; Lévêque, J; Lewis, P; Li, J; Li, Q Z; Lima, J G R; Lincoln, D; Linnemann, J; Lipaev, V V; Lipton, R; Liu, Z; Lobo, L; Lobodenko, A; Lokajícek, M; Lounis, A; Love, P; Lubatti, H J; Lynker, M; Lyon, A L; Maciel, A K A; Madaras, R J; Mättig, P; Magass, C; Magerkurth, A; Magnan, A M; Makovec, N; Mal, P K; Malbouisson, H B; Malik, S; Malyshev, V L; Mao, H S; Maravin, Y; Martens, M; McCarthy, R; Meder, D; Melnitchouk, A; Mendes, A; Mendoza, L; Merkin, M; Merritt, K W; Meyer, A; Meyer, J; Michaut, M; Miettinen, H; Millet, T; Mitrevski, J; Molina, J; Mondal, N K; Monk, J; Moore, R W; Moulik, T; Muanza, G S; Mulders, M; Mulhearn, M; Mundim, L; Mutaf, Y D; Nagy, E; Naimuddin, M; Narain, M; Naumann, N A; Neal, H A; Negret, J P; Neustroev, P; Nöding, C; Nomerotski, A; Novaes, S F; Nunnemann, T; O'Dell, V; O'Neil, D C; Obrant, G; Oguri, V; Oliveira, N; Oshima, N; Otec, R; Oteroy-Garzon, G J; Owen, M; Padley, P; Parashar, N; Park, S J; Park, S K; Parsons, J; Partridge, R; Parua, N; Patwa, A; Pawloski, G; Perea, P M; Pérez, E; Peters, K; Petroff, P; Petteni, M; Piegaia, R; Piper, J; Pleier, M A; Podesta-Lerma, P L M; Podstavkov, V M; Pogorelov, Y; Pol, M E; Pompos, A; Pope, B G; Popov, A V; Potter, C; Prado da Silva, W L; Prosper, H B; Protopopescu, S D; Qian, J; Quadt, A; Quinn, B; Rangel, M S; Rani, K J; Ranjan, K; Ratoff, P N; Renkel, P; Reucroft, S; Rijssenbeek, M; Ripp-Baudot, I; Rizatdinova, F K; Robinson, S; Rodrigues, R F; Royon, C; Rubinov, P; Ruchti, R; Rud, V I; Sajot, G; Sánchez-Hernández, A; Sanders, M P; Santoro, A F S; Savage, G; Sawyer, L; Scanlon, T; Schaile, A D; Schamberger, R D; Scheglov, Y; Schellman, H; Schieferdecker, P; Schmitt, C; Schwanenberger, C; Schwartzman, A; Schwienhorst, R; Sekaric, J; Sen-Gupta, S; Severini, H; Shabalina, E; Shamim, M; Shary, V; Shchukin, A A; Shephard, W D; Shivpuri, R K; Shpakov, D; Siccardi, V; Sidwell, R A; Simák, V; Sirotenko, V I; Skubic, P L; Slattery, P F; Smith, R P; Snow, G R; Snow, J; Snyder, S; Söldner-Rembold, S; Song, X; Sonnenschein, L; Sopczak, A; Sosebee, M; Soustruznik, K; Souza, M; Spurlock, B; Stark, J; Steele, J; Stolin, V; Stone, A; Stoyanova, D A; Strandberg, J; Strandberg, S; Strang, M A; Strauss, M; Ströhmer, R; Strom, D; Strovink, M; Stutte, L; Sumowidagdo, S; Sznajder, A; Talby, M; Tamburello, P; Taylor, W; Telford, P; Temple, J; Tiller, B; Titov, M; Tokmenin, V V; Tomoto, M; Toole, T; Torchiani, I; Towers, S; Trefzger, T; Trincaz-Duvoid, S; Tsybychev, D; Tuchming, B; Tully, C; Turcot, A S; Tuts, P M; Unalan, R; Uvarov, L; Uvarov, S; Uzunyan, S; Vachon, B; vanden Berg, P J; Van Kooten, R; Van Leeuwen, W M; Varelas, N; Varnes, E W; Vartapetian, A H; Vasilyev, I A; Vaupel, M; Verdier, P; Vertogradov, L S; Verzocchi, M; Villeneuve-Séguier, F; Vint, P; Vlimant, J R; Von Törne, E; Voutilainen, M; Vreeswijk, M; Wahl, H D; Wang, L; Wang, M H L; Warchol, J; Watts, G; Wayne, M; Weber, M; Weerts, H; Wermes, N; Wetstein, M; White, A; Wicke, D; Wilson, G W; Wimpenny, S J; Wobisch, M; Womersley, J; Wood, D R; Wyatt, T R; Xie, Y; Xuan, N; Yacoob, S; Yamada, R; Yan, M; Yasuda, T; Yatsunenko, Y A; Yip, K; Yoo, H D; Youn, S W; Yu, C; Yu, J; Yurkewicz, A; Zatserklyaniy, A; Zeitnitz, C; Zhang, D; Zhao, T; Zhou, B; Zhu, J; Zielinski, M; Zieminska, D; Zieminski, A; Zutshi, V; Zverev, E G
2007-01-01
We present the first determination of the electric charge of the top quark, using top quark pairs (ttbar) produced in ppbar collisions at sqrt(s)=1.96 TeV by the Fermilab Tevatron collider. We use 370 pb-1 of data collected by the D0 experiment and select events with at least one high transverse momentum electron or muon, high transverse energy imbalance, and four or more jets. We discriminate between b- and bbar-quark jets by using the charge and momenta of tracks within the jet cones. The data is consistent with the expected electric charge, |q|=2e/3. We exclude, at the 92% C.L., that the sample is solely due to the production of exotic quark pairs QQbar with |q|=4e/3. We place an upper limit on the fraction of QQbar pairs rho < 0.80 at the 90% C.L.
Top quark pair production at NNLO in the quark-antiquark channel
Abelof, Gabriel; Majer, Imre
2015-01-01
We present the derivation of the NNLO two-parton final state contributions to top pair production in the quark-antiquark channel proportionnal to the leading colour factor $N_c^2$. Together with the three and four-parton NNLO contributions derived in a previous publication, this enables us to complete the phenomenologically most important NNLO corrections to top pair hadro-production in this channel. We derive this two-parton contribution using the massive extension of the NNLO antenna subtraction formalism and implement those corrections in a parton-level event generator providing full kinematical information on all final state particles. Combining the new leading-colour contributions with the light quark contributions derived previously, we present NNLO differential distributions for LHC and Tevatron. We also compute the differential top quark forward-backward asymmetry at Tevatron and find that our results are in good agreement with the measurements by the D0 collaboration.
Quark matter or new particles?
Michel, F. Curtis
1988-01-01
It has been argued that compression of nuclear matter to somewhat higher densities may lead to the formation of stable quark matter. A plausible alternative, which leads to radically new astrophysical scenarios, is that the stability of quark matter simply represents the stability of new particles compounded of quarks. A specific example is the SU(3)-symmetric version of the alpha particle, composed of spin-zero pairs of each of the baryon octet (an 'octet' particle).
Phenomenology of heavy quark systems
The spectroscopy of heavy quark systems is examined with regards to spin independent and spin dependent potentials. It is shown that a qualitative picture exists of the spin-independent forces, and that a semi-quantitative understanding exists for the spin-dependent effects. A brief review is then given of the subject of the decays of hadrons containing heavy quarks, including weak decays at the quark level, and describing corrections to the spectator model
Antinori, Federico; Bass, Steffen A.; Bellwied, Rene; Ullrich, Thomas; Velkovska, Julia; Wiedemann, Urs
2005-04-01
Why another conference devoted to ultra-relativistic heavy-ion physics? As we looked around the landscape of the existing international conferences and workshops, we realized that there was not a single one tailored to the people who are most directly involved with the actual research work: students, post-docs, and junior faculty/research scientists. Of course there are schools, but that was not what we had in mind. We wanted a meeting where young researchers could come together to discuss in depth the physics that they are working on without any hindrance. The major conferences have very limited time for discussions which is often shared amongst the most established. This leaves little room for young people to ask their questions and to get the detailed feedback which they deserve and which satisfies their curiosity. A discussion-driven workshop, centering on those without whom there will be no future—that seemed like what was needed. And thus the Hot Quarks workshop was born. The aim of Hot Quarks was to enhance the direct exchange of scientific information among the younger members of the community, from both experiment and theory. Participation was by invitation only in order to emphasize the contributions from junior researchers. This approach makes the workshop unique among the many forums in the field. For young scientists it represented an opportunity for exposure that they would not have had in one of the major conferences. The hope is that this meeting has helped to stimulate the next generation of scientists in our field and, at the same time, strengthened their sense of community. It all came together from 18 24 July 2004, when the 77 participants met at The Inn at Snakedance in the Taos Ski Valley, New Mexico, USA, for the first Hot Quarks workshop. Photograph Participants gather in the sunshine at the foot of the Taos Ski Valley chairlift. By all accounts, Hot Quarks 2004 was a great success. Every participant had the opportunity to present her or
Brown, Laurie Mark; Dresden, Max; Hoddeson, Lillian
2009-01-01
Part I. Introduction; 1. Pions to quarks: particle physics in the 1950s Laurie M Brown, Max Dresden and Lillian Hoddeson; 2. Particle physics in the early 1950s Chen Ning Yang; 3. An historian's interest in particle physics J. L. Heilbron; Part II. Particle discoveries in cosmic rays; 4. Cosmic-ray cloud-chamber contributions to the discovery of the strange particles in the decade 1947-1957 George D. Rochester; 5. Cosmic-ray work with emulsions in the 1940s and 1950s Donald H. Perkins; Part III. High-energy nuclear physics; Learning about nucleon resonances with pion photoproduction Robert L. Walker; 7. A personal view of nucleon structure as revealed by electron scattering Robert Hofstadter; 8. Comments on electromagnetic form factors of the nucleon Robert G. Sachs and Kameshwar C. Wali; Part IV. The new laboratory; 9. The making of an accelerator physicist Matthew Sands; 10. Accelerator design and construction in the 1950s John P. Blewett; 11. Early history of the Cosmotron and AGS Ernest D. Courant; 12. Panel on accelerators and detectors in the 1950s Lawrence W. Jones, Luis W. Alvarez, Ugo Amaldi, Robert Hofstadter, Donald W. Kerst, Robert R. Wilson; 13. Accelerators and the Midwestern Universities Research Association in the 1950s Donald W. Kerst; 14. Bubbles, sparks and the postwar laboratory Peter Galison; 15. Development of the discharge (spark) chamber in Japan in the 1950s Shuji Fukui; 16. Early work at the Bevatron: a personal account Gerson Goldhaber; 17. The discovery of the antiproton Owen Chamberlain; 18. On the antiproton discovery Oreste Piccioni; Part V. The Strange Particles; 19. The hydrogen bubble chamber and the strange resonances Luis W. Alvarez; 20. A particular view of particle physics in the fifties Jack Steinberger; 21. Strange particles William Chinowsky; 22. Strange particles: production by Cosmotron beams as observed in diffusion cloud chambers William B. Fowler; 23. From the 1940s into the 1950s Abraham Pais; Part VI. Detection of the
Simulations with dynamical HISQ quarks
Bazavov, A; DeTar, C; Freeman, W; Gottlieb, Steven; Heller, U M; Hetrick, J E; Laiho, J; Levkova, L; Oktay, M; Osborn, J; Sugar, R L; Toussaint, D; Van de Water, R S
2010-01-01
We report on the status of a program of generating and using configurations with four flavors of dynamical quarks, using the HISQ action. We study the lattice spacing dependence of physical quantities in these simulations, using runs at several lattice spacings, but with the light quark mass held fixed at two tenths of the strange quark mass. We find that the lattice artifacts in the HISQ simulations are much smaller than those in the asqtad simulations at the same lattice spacings and quark masses. We also discuss methods for setting the scale, or assigning a lattice spacing to ensembles run at unphysical parameters.
Production of Heavy Quarks Close to Threshold
Adel, K.; Ynduráin, F. J.
1995-01-01
We calculate production by vector and axial currents of heavy quark pairs ($c\\bar{c}$, $b\\bar{b}$, $t\\bar{t}$) close to threshold. We take into account strong interaction contributions (including radiative corrections and leading nonperturbative effects) by using the Fermi-Watson final state interaction theorem. We use the results obtained to compare with experiment for open production of $c\\bar{c}$, $b\\bar{b}$ near threshold, and to give a reliable estimate of the so-called ``threshold effec...
Systematics of heavy quark production at RHIC
Vogt, R.
2002-01-30
We discuss a program for systematic studies of heavy quark production in pp, pA and AA interactions. The Q{ovr Q} production cross sections themselves cannot be accurately predicted to better than 50% at RHIC. For studies of deviations in Q{ovr Q} production such as those by nuclear shadowing and heavy quark energy loss, the pp cross-section thus needs to be measured. We then show that the ratio of pA to pp dilepton mass distributions can provide a measurement of the nuclear gluon distribution. With total rates and nuclear shadowing under control it is easier to study energy loss and to use c{ovr c} as a normalization of J/{Psi} production.
Quark and Gluon Relaxation in Quark-Gluon Plasmas
Heiselberg, H.; Pethick, C. J.
1993-01-01
The quasiparticle decay rates for quarks and gluons in quark-gluon plasmas are calculated by solving the kinetic equation. Introducing an infrared cutoff to allow for nonperturbative effects, we evaluate the quasiparticle lifetime at momenta greater than the inverse Debye screening length to leading order in the coupling constant.
Fluctuation sound absorption in quark matter
Kerbikov, B O
2016-01-01
We investigate the sound absorption in quark matter due to the interaction of the sound wave with the precritical fluctuations of the diquark-pair field above $T_c$. The soft collective mode of the pair field is derived using the time dependent Ginzburg-Landau functional with random Langevin forces. The strong absorption near the phase transition line may be viewed as a manifestation of the Mandelshtam-Leontovich slow relaxation time theory.
LHCb pentaquarks in constituent quark models
Ortega, P G; Fernández, F
2016-01-01
The recently discovered $P_c(4380)^+$ and $P_c(4450)^+$ states at LHCb have masses close to the $\\bar D\\Sigma_c^*$ and $\\bar D^*\\Sigma_c$ thresholds, respectively, which suggest that they may have significant meson-baryon molecular components. We analyze these states in the framework of a constituent quark model which has been applied to a wide range of hadronic observables, being the model parameters, therefore, completely constrained. The $P_c(4380)^+$ and $P_c(4450)^+$ are studied as molecular states composed by charmed baryons and open charm mesons. Several bound states with the proper binding energy are found in the $\\bar D\\Sigma_c^*$ and $\\bar D^*\\Sigma_c$ channels. We discuss the possible assignments of these states from their decay widths. Moreover, two more states are predicted, associated with the $\\bar D\\Sigma_c$ and $\\bar D^* \\Sigma_c^*$ thresholds.
Top Quark Studies at Hadron Colliders
Sinervo, Pekka K.
1996-01-01
The techniques used to study top quarks at hadron colliders are presented. The analyses that discovered the top quark are described, with emphasis on the techniques used to tag b-quark jets in candidate events. The most recent measurements of top quark properties by the CDF and DZero collaborations are reviewed, including the top quark cross section, mass, branching fractions and production properties. Future top quark studies at hadron colliders are discussed, and predictions for event yield...
The Discovery of the Top Quark
Sinervo, P.K.
1995-12-01
The top quark and the Higgs boson are the heaviest elementary particles predicted by the standard model. The four lightest quark flavours, the up, down, strange and charm quarks, were well-established by the mid-1970's. The discovery in 1977 of the {Tau} resonances, a new family of massive hadrons, required the introduction of the fifth quark flavour. Experimental and theoretical studies have indicated that this quark also has a heavier partner, the top quark.
Baryons with Two Heavy Quarks as Solitons
Bander, Myron; Subbaraman, Anand
1994-01-01
Using the chiral soliton model and heavy quark symmetry we study baryons containing two heavy quarks. If there exists a stable (under strong interactions) meson consisting of two heavy quarks and two light ones, then we find that there always exists a state of this meson bound to a chiral soliton and to a chiral anti-soliton, corresponding to a two heavy quark baryon and a baryon containing two heavy anti-quarks and five light quarks, or a ``heptaquark".
Kurkela, Aleksi
2016-01-01
We generalize the state-of-the-art perturbative Equation of State of cold quark matter to nonzero temperatures, needed in the description of neutron star mergers and core collapse processes. The new result is accurate to order g^5 in the gauge coupling, and is based on a novel framework for dealing with the infrared sensitive soft field modes of the theory. The zero Matsubara mode sector is treated using a dimensionally reduced effective theory, while the soft non-zero modes are resummed using the Hard Thermal Loop approximation. This combination of known effective descriptions offers unprecedented access to small but nonzero temperatures, both in and out of beta equilibrium.
This volume is a compilation of the papers presented at the September 1983 NATO ASI Conference on Quarks and Leptons. Subjects covered include: physics results of the UAl collaboration at the CERN proton-antiproton collider, charged current mixing and CP-violation, lattice quantum chromodynamics, lattice gauge theory with matter, left-right symmetric models of weak interactions, extensions of the standard model, supersymmetry in particle physics, quasi nambu-Goldstone fermions, cosmology and particle physics, low energy theorem for the Goldstino, superstrings, different formulations of N=1 supergravity and model building, and supersymmetric GUTS
It is argued on theoretical and phenomenological grounds that confinement of quarks is intrinsically a many-body interaction. The Born-Oppenheimer approximation to the bag model is shown to give rise to a static potential energy that consists of a sum of two-body Coulomb terms and a many-body confining term. Following the success of this potential in heavy Q anti Q systems it is being applied to Q2 anti Q2. Preliminary calculations suggest that dimeson bound states with exotic flavor, such as bb anti s anti s, exist. 13 refs., 5 figs
Kurkela, Aleksi; Vuorinen, Aleksi
2016-07-22
We generalize the state-of-the-art perturbative equation of state of cold quark matter to nonzero temperatures, needed in the description of neutron star mergers and core collapse processes. The new result is accurate to O(g^{5}) in the gauge coupling, and is based on a novel framework for dealing with the infrared sensitive soft field modes of the theory. The zero Matsubara mode sector is treated via a dimensionally reduced effective theory, while the soft nonzero modes are resummed using the hard thermal loop approximation. This combination of known effective descriptions offers unprecedented access to small but nonzero temperatures, both in and out of beta equilibrium. PMID:27494468
Direct Top Quark Production at Hadron Colliders as a Probe of New Physics
Hosch, M.; Whisnant, K.; Young, B. -L.
1997-01-01
We examine the effect of an anomalous flavor changing chromomagnetic moment which allows direct top quark production (two partons combining into an unaccompanied single top quark in the s-channel) at hadron colliders. We consider both t-c-g and t-u-g couplings. We find that the anomalous charm quark coupling parameter $\\kappa_c / \\Lambda$ can be measured down to $.06 TeV^{-1}(.009 TeV^{-1}$) at the Tevatron with the Main Injector upgrade(LHC). The anomalous up quark coupling parameter $\\kappa...
Inclusive χc and b-quark production in bar pp collisions at √s =1.8 TeV
We report the full reconstruction of χc mesons through the decay chain χc→J/ψ γ, J/ψ→μ+μ-, using data obtained at the Collider Detector at Fermilab in 2.6±0.2 pb-1 of bar pp collisions at √s =1.8 TeV. This exclusive χc sample is used to measure the χc-meson production cross section times branching fractions. We obtain σxB=3.2±0.4(stat)-1.1+1.2(syst) nb for χc mesons decaying to J/ψ with pT>6.0 GeV/c and pseudorapidity |η|Tb>8.5 GeV/c and |yb|<1
Top Quark Physics: Future Measurements
We discuss the study of the top quark at future experiments and machines. Top's large mass makes it a unique probe of physics at the natural electroweak scale. We emphasize measurements of the top quark's mass, width, and couplings, as well as searches for rare or nonstandard decays, and discuss the complementary roles played by hadron and lepton colliders
Top quark physics: Future Measurements
We discuss the study of the top quark at future experiments and machines. Top's large mass makes it a unique probe of physics at the natural electroweak scale. We emphasize measurements of the top quark's mass, width, and couplings, as well as searches for rare or nonstandard decays, and discuss the complementary roles played by hadron and lepton colliders
Neubert, Matthias(PRISMA Cluster of Excellence & Mainz Institut for Theoretical Physics, Johannes Gutenberg University, D-55099, Mainz, Germany)
1996-01-01
We give an introduction to the heavy-quark effective theory and the $1/m_Q$ expansion, which provide the modern framework for a systematic, model-independent description of the properties and decays of hadrons containing a heavy quark. We discuss the applications of these concepts to spectroscopy and to the weak decays of $B$ mesons.
Bag model of quark confinement
The flavor and color models along with the bag confinement model for quarks are described together with a brief history of quark theory and experiment. The implications of these theories for the structure of the present elementary particles and hence that of all matter are given as well
Color superconductivity and quark stars
The search for new phases of strange quark matter inside neutron stars has recently received a lot of attention since it has been shown that the attractive nature of the one gluon exchange interaction in QCD may produce a superconducting phase in quark matter. We study an extended version of the Chromodielectric model with a BCS quark pairing implemented, and analyze the superconducting color flavor locked phase. We show that the inclusion in the free energy density of a negative term of the diquark condensate ensures the stability of quark matter. We explore the implications of our results in the structure of compact quark stars and explicitly show that CFL stars can be absolutely stable and more compact than strange stars
Color superconductivity and quark stars
Malheiro, M. [Instituto Tecnologico de Aeronautica, CTA, 12-228-900, Sao Jose dos Campos (Brazil); Instituto de Fisica, Universidade Federal Fluminense, 24-210-320, Niteroi (Brazil); Linares, L.P. [Instituto de Fisica, Universidade Federal Fluminense, 24-210-320, Niteroi (Brazil); Fiolhais, M. [Departamento de Fisica, Centro de Fisica Computacional, Universidade de Coimbra, P-3004-516 Coimbra (Portugal); Taurines, A. [Department of Physics, University of Wales Swansea, Singleton Park, Swansea, SA2 8PP (United Kingdom)
2007-06-15
The search for new phases of strange quark matter inside neutron stars has recently received a lot of attention since it has been shown that the attractive nature of the one gluon exchange interaction in QCD may produce a superconducting phase in quark matter. We study an extended version of the Chromodielectric model with a BCS quark pairing implemented, and analyze the superconducting color flavor locked phase. We show that the inclusion in the free energy density of a negative term of the diquark condensate ensures the stability of quark matter. We explore the implications of our results in the structure of compact quark stars and explicitly show that CFL stars can be absolutely stable and more compact than strange stars.
Jet quenching and heavy quarks
Renk, Thorsten
2014-05-01
Jet quenching and more generally physics at high transverse momentum PT scales is a cornerstone of the heavy-ion physics program at both RHIC and LHC. In this work, the current understanding of jet quenching in terms of a QCD shower evolution being modified by the surrounding medium is reviewed along with the evidence for this picture from light parton high PT observables. Conceptually, the same QCD shower description should also be relevant for heavy quarks, but with several important modifications introduced by the quark masses. Thus especially in the limit of small jet energy over quark mass Ejet/mq, the relevant physics may be rather different from light quark jets, and several attempts to explain the observed phenomenology of heavy quarks at high PT are discussed here.
Jet quenching and heavy quarks
Jet quenching and more generally physics at high transverse momentum PT scales is a cornerstone of the heavy-ion physics program at both RHIC and LHC. In this work, the current understanding of jet quenching in terms of a QCD shower evolution being modified by the surrounding medium is reviewed along with the evidence for this picture from light parton high PT observables. Conceptually, the same QCD shower description should also be relevant for heavy quarks, but with several important modifications introduced by the quark masses. Thus especially in the limit of small jet energy over quark mass Ejet/mq, the relevant physics may be rather different from light quark jets, and several attempts to explain the observed phenomenology of heavy quarks at high PT are discussed here
Investigation of the splitting of quark and gluon jets
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Zaitsev, A; Zalewska-Bak, A; Zalewski, Piotr; Zavrtanik, D; Zevgolatakos, E; Zimin, N I; Zucchelli, G C; Zumerle, G
1998-01-01
The splitting processes in identified quark and gluon jets are investigated using longitudinal and transverse observables. The jets are selected from symmetric three-jet events measured in Z decays L with the {\\sc Delphi} detector in 1991-1994. Gluon jets are identified using heavy quark anti-tagging. Scaling violations in identified gluon jets are observed for the first time. The scale energy dependence of the gluon fragmentation function is found to be about two times larger than for the corresponding quark jets, consistent with the QCD expectation $C_A/C_F$. The primary splitting of gluons and quarks into subjets agrees with fragmentation models and, for specific regions of the jet resolution $y$, with NLLA calculations. The maximum of the ratio of the primary subjet splittings in quark and gluon jets is $2.77\\pm0.11\\pm0.10$. Due to non-perturbative effects, the data are below the expectation at small $y$. The transition from the perturbative to the non-perturbative domain appears at smaller $y$ for quark ...
Schramm, D.N. [Chicago Univ., IL (United States)]|[Fermi National Accelerator Lab., Batavia, IL (United States); Fields, B.; Thomas, D. [Chicago Univ., IL (United States)
1992-01-01
The possible implications of the quark-hadron transition for cosmology are explored. Possible surviving signatures are discussed. In particular, the possibility of generating a dark matter candidate such as strange nuggets or planetary mass black holes is noted. Much discussion is devoted to the possible role of the transition for cosmological nucleosynthesis. It is emphasized that even an optimized first order phase transition will not significantly alter the nucleosynthesis constraints on the cosmological baryon density nor on neutrino counting. However, it is noted that Be and B observations in old stars may eventually be able to be a signature of a cosmologically significant quark-hadron transition. It is pointed out that the critical point in this regard is whether the observed B/Be ratio can be produced by spallation processes or requires cosmological input. Spallation cannot produce a B/Be ratio below 7.6. A supporting signature would be Be and B ratios to oxygen that greatly exceed galactic values. At present, all data is still consistent with a spallagenic origin.
The possible implications of the quark-hadron transition for cosmology are explored. Possible surviving signatures are discussed. In particular, the possibility of generating a dark matter candidate such as strange nuggets or planetary mass black holes is noted. Much discussion is devoted to the possible role of the transition for cosmological nucleosynthesis. It is emphasized that even an optimized first order phase transition will not significantly alter the nucleosynthesis constraints on the cosmological baryon density nor on neutrino counting. However, it is noted that Be and B observations in old stars may eventually be able to be a signature of a cosmologically significant quark-hadron transition. It is pointed out that the critical point in this regard is whether the observed B/Be ratio can be produced by spallation processes or requires cosmological input. Spallation cannot produce a B/Be ratio below 7.6. A supporting signature would be Be and B ratios to oxygen that greatly exceed galactic values. At present, all data is still consistent with a spallagenic origin
Quark mass density- and temperature- dependent model for bulk strange quark matter
al, Yun Zhang et.
2002-01-01
It is shown that the quark mass density-dependent model can not be used to explain the process of the quark deconfinement phase transition because the quark confinement is permanent in this model. A quark mass density- and temperature-dependent model in which the quark confinement is impermanent has been suggested. We argue that the vacuum energy density B is a function of temperature. The dynamical and thermodynamical properties of bulk strange quark matter for quark mass density- and temper...
Heavy quark fragmenting jet functions
Heavy quark fragmenting jet functions describe the fragmentation of a parton into a jet containing a heavy quark, carrying a fraction of the jet momentum. They are two-scale objects, sensitive to the heavy quark mass, mQ, and to a jet resolution variable, τN. We discuss how cross sections for heavy flavor production at high transverse momentum can be expressed in terms of heavy quark fragmenting jet functions, and how the properties of these functions can be used to achieve a simultaneous resummation of logarithms of the jet resolution variable, and logarithms of the quark mass. We calculate the heavy quark fragmenting jet function GQQ at O(αs), and the gluon and light quark fragmenting jet functions into a heavy quark, GgQ and GlQ, at O(αs2). We verify that, in the limit in which the jet invariant mass is much larger than mQ, the logarithmic dependence of the fragmenting jet functions on the quark mass is reproduced by the heavy quark fragmentation functions. The fragmenting jet functions can thus be written as convolutions of the fragmentation functions with the matching coefficients Jij, which depend only on dynamics at the jet scale. We reproduce the known matching coefficients Jij at O(αs), and we obtain the expressions of the coefficients JgQ and JlQ at O(αs2). Our calculation provides all the perturbative ingredients for the simultaneous resummation of logarithms of mQ and τN
Quark Propagation in the Quark-Gluon Plasma
Li, Xiangdong; Shakin, C M; Sun, Qing; Li, Xiangdong; Li, Hu; Sun, Qing
2004-01-01
It has recently been suggested that the quark-gluon plasma formed in heavy-ion collisions behaves as a nearly ideal fluid. That behavior may be understood if the quark and antiquark mean-free- paths are very small in the system, leading to a "sticky molasses" description of the plasma, as advocated by the Stony Brook group. This behavior may be traced to the fact that there are relatively low-energy $q\\bar{q}$ resonance states in the plasma leading to very large scattering lengths for the quarks. These resonances have been found in lattice simulation of QCD using the maximum entropy method (MEM). We have used a chiral quark model, which provides a simple representation of effects due to instanton dynamics, to study the resonances obtained using the MEM scheme. In the present work we use our model to study the optical potential of a quark in the quark-gluon plasma and calculate the quark mean-free-path. Our results represent a specific example of the dynamics of the plasma as described by the Stony Brook group...