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Measurement of the partial width of the Z0 into b {Mathematical expression} final states using their semi-leptonic decays

Zeitschrift für Physik C Particles and Fields 56:1 (1992) 47-61

Authors:

P Abreu, W Adam, T Adye, E Agasi, GD Alekseev, P Allen, S Almehed, SJ Alvsvaag, U Amaldi, EG Anassontzis, A Andreazza, P Antilogus, WD Apel, RJ Apsimon, B Ã…sman, JE Augustin, A Augustinus, P Baillon, P Bambade, F Barao, R Barate, G Barbiellini, DY Bardin, A Baroncelli, O Barring, JA Barrio, W Bartl, MJ Bates, M Battaglia, M Baubillier, KH Becks, CJ Beeston, M Begalli, P Beilliere, Y Belokopytov, P Beltran, D Benedic, M Berggren, D Bertrand, F Bianchi, MS Bilenky, P Billoir, J Bjarne, D Bloch, S Blyth, V Bocci, PN Bogolubov, T Bolognese, M Bonesini, W Bonivento, PSL Booth, P Borgeaud, G Borisov, H Borner, C Bosio, B Bostjancic, S Bosworth, O Botner, B Bouquet, C Bourdarios, TJV Bowcock, M Bozzo, S Braibant, P Branchini, KD Brand, RA Brenner, H Briand, C Bricman, RCA Brown, N Brummer, JM Brunet, L Bugge, T Buran, H Burmeister, JAMA Buytaert, M Caccia, M Calvi, AJ Camacho Rozas, T Camporesi, V Canale, F Cao, F Carena, L Carroll, C Caso, E Castelli, MV Castillo Gimenez, A Cattai, FR Cavallo, L Cerrito, V Chabaud, A Chan, P Charpentier, L Chaussard, J Chauveau, P Checchia, GA Chelkov, L Chevalier, P Chliapnikov, V Chorowicz, JTM Chrin

Abstract:

The spectra of prompt electrons and muons from the semi-leptonic decays of heavy hadrons produced in Z0 decays have been used to measure the coupling of the Z0 to b quarks weighted by the B hadrons mean semi-leptonic branching fraction, giving a value: {Mathematical expression}. The data has also been used to measure the value of the fragmentation parameter, defined in the context of the LUND PS Model, version 7.2, giving: {Mathematical expression}. The corresponding value of the mean fraction of the beam energy taken by a B hadron in the fragmentation of a b quark is: {Mathematical expression}. If the values of {Mathematical expression} and ΓH are taken from the Standard Model, the following value is obtained for the mean semi-leptonic braching fraction of B hadrons: BRslb=(10.1±0.7)%. Taking the value of {Mathematical expression} from an independent analysis of DELPHI data based on the use of the boosted sphericity product, a value: BRslb=(10.1±1.3)% is obtained. © 1992 Springer-Verlag.

Search for excited charged leptons in Z0 decays

Zeitschrift für Physik C Particles and Fields 53:1 (1992) 41-49

Authors:

P Abreu, W Adam, F Adami, T Adye, T Akesson, GD Alekseev, P Allen, S Almehed, F Alted, SJ Alvsvaag, U Amaldi, E Anassontzis, P Antilogus, WD Apel, B Ã…sman, P Astier, JE Augustin, A Augustinus, P Baillon, P Bambade, F Barao, G Barbiellini, DY Bardin, A Baroncelli, O Barring, W Bartl, MJ Bates, M Baubillier, KH Becks, CJ Beeston, M Begalli, P Beilliere, Y Belokopytov, P Beltran, D Benedic, JM Benlloch, M Berggren, D Bertrand, S Biagi, F Bianchi, JH Bibby, MS Bilenky, P Billoir, J Bjarne, D Bloch, S Blyth, PN Bogolubov, T Bolognese, M Bonapart, M Bonesini, W Bonivento, PSL Booth, M Boratav, P Borgeaud, G Borisov, H Borner, C Bosio, O Botner, B Bouquet, M Bozzo, S Braibant, P Branchini, KD Brand, RA Brenner, C Bricman, RCA Brown, N Brummer, JM Brunet, L Bugge, T Buran, H Burmeister, JAMA Buytaert, M Caccia, M Calvi, AJ Camacho Rozas, JE Campagne, A Campion, T Camporesi, V Canale, F Cao, L Carroll, C Caso, E Castelli, MV Castillo Gimenez, A Cattai, FR Cavallo, L Cerrito, P Charpentier, P Checchia, GA Chelkov, L Chevalier, P Chliapnikov, V Chorowicz, R Cirio, MP Collins, JL Contreras, R Contri, G Cosme, F Couchot, HB Crawley

Abstract:

Using a data sample of 115000 hadronic Z0 decays, a search was performed for the production of excited charged leptons decaying into an ordinary lepton and one photon. Pair production of excited leptons of mass below 45 GeV/c2 is excluded. From an analysis of the lepton-photon mass spectra this experiment is also able to exclude single production of these particles for masses that reach up to 85 GeV/c2, if the compositeness scale is below 1 TeV. © 1992 Springer-Verlag.

Multiplicity dependence of mean transverse momentum in e+e- annihilations at LEP energies

Physics Letters B 276:1-2 (1992) 254-262

Authors:

P Abreu, W Adam, F Adami, T Adye, T Akesson, GD Alekseev, P Allen, S Almehed, SJ Alvsvaag, U Amaldi, E Anassontzis, P Antilogus, WD Apel, RJ Apsimon, B Ã…sman, JE Augustin, A Augustinus, P Baillon, P Bambade, F Barao, R Barate, G Barbiellini, DY Bardin, A Baroncelli, O Barring, W Bartl, MJ Bates, M Battaglia, M Baubillier, KH Becks, CJ Beeston, M Begalli, P Beilliere, Y Belokopytov, K Belous, P Beltran, D Benedic, JM Benlloch, M Berggren, D Bertrand, F Bianchi, MS Bilenky, P Billoir, J Bjarne, D Bloch, S Blyth, V Bocci, PN Bogolubov, T Bolognese, M Bonapart, M Bonesini, W Bonivento, PSL Booth, P Borgeaud, G Borisov, H Borner, C Bosio, B Bostjancic, O Botner, B Bouquet, C Bourdarios, M Bozzo, S Braibant, P Branchini, KD Brand, RA Brenner, H Briand, C Bricman, RCA Brown, N Brummer, JM Brunet, L Bugge, T Buran, H Burmeister, JAMA Buytaert, M Caccia, M Calvi, AJ Camacho Rozas, A Campion, T Camporesi, V Canale, F Cao, F Carena, L Carroll, C Caso, E Castelli, MV Castillo Gimenez, A Cattai, FR Cavallo, L Cerrito, A Chan, P Charpentier, L Chaussard, J Chauveau, P Checchia, GA Chelkov, L Chevalier, P Chliapnikov, V Chorowicz, R Cirio

Abstract:

A strong increase of the mean transverse momentum 〈pt〉 with the number of charged particles nch is observed in e+e - annihilations into hadrons at LEP energies. The effect resembles correlations observed in hadron-hadron interactions. In e+e- annihilations the 〈Pt〉 and nch correlations can be accounted for by gluon radiation. © 1992.

Production of strange particles in the hadronic decays of the Z0

Physics Letters B 275:1-2 (1992) 231-242

Authors:

P Abreu, W Adam, F Adami, T Adye, T Akesson, GD Alekseev, P Allen, S Almehed, SJ Alvsvaag, U Amaldi, E Anassontzis, P Antilogus, WD Apel, RJ Apsimon, B Ã…sman, JE Augustin, A Augustinus, P Baillon, P Bambade, F Barao, R Barate, G Barbiellini, DY Bardin, A Baroncelli, O Barring, W Bartl, MJ Bates, M Battaglia, M Baubillier, KH Becks, CJ Beeston, M Begalli, P Beilliere, Y Belokopytov, P Beltran, D Benedic, JM Benlloch, M Berggren, D Bertrand, F Bianchi, MS Bilenky, P Billoir, J Bjarne, D Bloch, S Blyth, V Bocci, PN Bogolubov, T Bolognese, M Bonapart, M Bonesini, W Bonivento, PSL Booth, P Borgeaud, G Borisov, H Borner, C Bosio, B Bostjancic, O Botner, B Bouquet, C Bourdarios, M Bozzo, S Braibant, P Branchini, KD Brand, RA Brenner, H Briand, C Bricman, RCA Brown, N Brummer, JM Brunet, L Bugge, T Buran, H Burmeister, JAMA Buytaert, M Caccia, M Calvi, AJC Rozas, A Campion, T Camporesi, V Canale, F Cao, F Carena, L Carroll, C Caso, E Castelli, MVC Gimenez, A Cattai, FR Cavallo, L Cerrito, A Chan, M Chapkin, P Charpentier, L Chaussard, J Chauveau, P Checchia, GA Chelkov, L Chevalier, P Chliapnikov, V Chorowicz, R Cirio

Abstract:

An analysis of the production of strange particles from the decays of the Z0 boson into multihadronic final states is presented. The analysis is based on about 90 000 selected hadronic Z0 decays collected by the DELPHI detector at LEP in 1990. Ks 0, K*±, Λ(Λ) and Ξ- (ө+) have been identified by their characteristic decays. The measured production cross sections are compared with predictions of the Lund Monte Carlo tuned to data at PEP/PETRA energies. © 1992.

Search for scalar leptoquarks from Z0 decays

Physics Letters B 275:1-2 (1992) 222-230

Authors:

P Abreu, W Adam, F Adami, T Adye, T Akesson, GD Alekseev, P Allen, S Almehed, SJ Alvsvaag, UA Amaldi, E Anassontzis, P Antilogus, WD Apel, RJ Apsimon, B Ã…sman, P Astier, JE Augustin, A Augustinus, P Baillon, P Bambade, F Barao, R Barate, G Barbiellini, DY Bardin, A Baroncelli, O Barring, W Bartl, MJ Bates, M Battaglia, M Baubillier, KH Beckes, CJ Beeston, M Begalli, P Beilliere, Y Belokopytov, P Beltran, D Benedic, JM Benlloch, M Berggren, D Bertrand, F Bianchi, MS Bilenky, P Billoir, J Bjarne, D Bloch, S Blyth, V Bocci, PN Bogolubov, T Bolognese, M Bonapart, M Bonesini, W Bonievento, PSL Booth, M Boratav, P Borgeaud, H Borner, C Bosio, B Bostjancic, O Botner, B Bouquet, M Bozzo, S Braibant, P Branchini, KD Brand, RA Benner, C Bricman, RCA Brown, N Brummer, JM Brunet, L Bugge, T Buran, H Burmeister, JAMA Buytaert, M Caccia, M Calvi, AJ Camacho Rozas, A Campin, T Camporesi, V Canale, F Cao, F Carena, L Carroll, C Caso, E Castelli, MV Castillo Gimenez, A Cattai, FR Cavallo, L Cerrito, A Chan, M Chapkin, P Charpentier, P Checchia, GA Chelkov, L Chevalier, P Chliapnikov, V Chorowicz, R Cirio, MP Clara, P Collins, JL Contreras

Abstract:

We have searched for pair produced scalar leptoquarks each decaying to a quark and a charged lepton in a sample of 116 000 hadronic Z0 events produced at LEP. No candidate was detected and cross section and branching ratio limits are set for the above process at 95% CL. Mass limits are found to be about 42 GeV/c2 depending only slightly on the models used and a coupling times branching ratio exclusion line is drawn for a scalar leptoquark with a free coupling. We have also probed the mass region above 45 GeV/c2 for a singly produced scalar leptoquark and set limits on the cross section and the coupling λ2/4π up to 60 GeV. © 1992.