Prompt Photon Identification in the ALICE Experiment: The Isolation Cut Method

Texte intégral

(1)Prompt Photon Identification in the ALICE Experiment: The Isolation Cut Method G. Conesa, H. Delagrange, J. Diaz, Y.V. Kharlov, Y. Schutz. To cite this version: G. Conesa, H. Delagrange, J. Diaz, Y.V. Kharlov, Y. Schutz. Prompt Photon Identification in the ALICE Experiment: The Isolation Cut Method. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Elsevier, 2007, 580, pp.1446-1459. �10.1016/j.nima.2007.06.014�. �in2p3-00138058�. HAL Id: in2p3-00138058 http://hal.in2p3.fr/in2p3-00138058 Submitted on 24 Mar 2007. HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés..

(2)

(3) !"#

(4) %$'&)(+*-,/.0123 4657

(5) (98;:< '*>= )?@A B

(6) C DFEHGJIHKLNMPO ∗ Q ESR LNTUOHV+WPOHKV+L X EHRZY[OH\ ] E_^1E+` aOSWPTUIcb ] EHdefahgBi<\ ++jlk9mjnm)opomrhqt[j[sfxsfuwq[vyxuw{uwz|qt¦u{~q¨}zu§6x{xsvB9q lsfp{{ 9©nnªsfq v6{hnU{qtsv6qt[vw{©uwA«Aq¤+qª«[ qt{ sfslu 9q {l¤hB6vymmx<uwB jn{ ¡ms !x/¢PHjU ¡¦£n [q ¤h[s{¥6t {Hr!Psfuw{q s l9kNvls[q mN+ ¡BB¬hq stnq6r®r{u¯ q v6 s a,b,. b. a. c. b,d. a. b. c. d. °;±+²n³n´µ¶P³ ·¸N¹/ºA»S¼6½¾Z¹¿Àc¹ÁpÂ_Ã|¹nÄfÅBÆÅ»rÇ2½0ÈÂ_ÉÉÊ¹Åp¹nË ÅÆ!ÄÊÂÊ¹nÄfÅpÂ~ÌÍÀÁpÎÃ|ÀÅ¡ÀN¸ÎÅpÎÄNÏÆÄÊÉ_Â_ÐP¸fÅÄN¹nÑÅ6ÁtÆÉÃ|¹nÏ6ÎPÄÏ¡ÈÂ~Åp¸Åp¸N¹/ÒhÇ2Ó2Ô ÆÄNÊ ¾ÕÖ½ÆÉÊ¹Åp¹nËÅpÎ!ÁpÏn×¨½B¸NÆ!ÁpÐ¹Ê ÀÆÁ6ÅpÂ_ËnÉ_¹nÏ ÈÂ_É_ÉBØc¹Ê¹Åp¹nË Åp¹Ê Æ!ÄÊ ÂÊ¹ÄÅpÂ~ÙN¹ÊCØfÍÚÅp¸N¹ÛËn¹nÄfÅ6ÁtÆÉhÅ6ÁtÆËtÜÂÄÐÏ[ÍÏ[Åp¹nÃ×r¼UÄCÅp¸NÂ_Ï ÀÆ!Àc¹ÁÝHÆJÃ|¹Åp¸NÎÊÖÅpÎÂÊ¹ÄÅpÂ~ÌÍZÀÁpÎPÃ|ÀÅ2ÀN¸ÎÅpÎPÄÏÞÆÄNÊZÅpÎJÏ6¹nÀNÆ!ÁtÆÅp¹Åp¸¹nÃßÌÁpÎPÃ>Åp¸N¹ÛØÆËtÜÐÁpÎÑNÄÊCÎÌ¸NÆPÊÁpÎPÄNÏ Æ!ÄÊ Ê¹nËÆnÍ ÀN¸ÎÅpÎÄNÏÂ_ÄÒhÇ2Ó2ÔÈÂ~Åp¸Åp¸N¹à¸N¹nÉ_À;ÎÌ¨Â_Ï6ÎPÉÆÅpÂÎÄÖËnÑÅpÏÂ_ÏÀÁp¹nÏ6¹nÄfÅp¹Êr× á ¤Nàq «àmN®HâxüvyýPpû þnâJýPã¡û ÿä~÷åæPïçü èp<ûé<èpêlPånû ëåïìnüí2ýPíÞû þnýPìAû çwêl÷ìtïëî ü ïPèpû ð~èpPñpû òlêyóíÞìnåé<è6òUä~ñAñ ìnð~óêyä~í2è6òUèpêyî ïôrõZö îlñpä~é!òlä~ð~ð_ìòUóêyî ï÷!øfìnêyù!çwåð~ø<óéú<ð_ìnîUíÞìPû .

(7) . "!# $&%(')' *,+'-/.10'"243576983;:=<,>@? AB%C5 <,-/? 2EDF' 38G573IH9JLK .M8N' *,+'"O 3/'"<P3/?Q+(-;?RS.M<,'T<,'"O.U8;.UR 'V<(573/5WAX? -Y:(2C<,'"-Z 83/572=<,.12C[L3;%('\+(-/? +'-;3;.U'"8]?7A3;%('_^:C5 -;È[ 6U:(? 2a+(6M5 8;05 bdcLegfih AX? -/0'"<j.U2j:(613;-5Zk-;'"6U573;.URS.U83;.MOl2S:CO 6U':C8Zk2:=O 6U':C8 O ?4616U.M8.U? 2C8nmUo pkq_JI54<,-;?42rDF'3/8N5 -;'s[ '"2('-53/'"<ut>v3;%(' %C54<,-;?42(.Uw"53/.1?42x?7ATyC2=5761Zk83/573;'z+=57-;3;? 2=8v{\.13;%|%(.U[ % b h 8/O5733/'-/'"<s.U2r+(-/.10}5 -;> 3;-572=8R4'-8'}0? 0'"243/:(0 p O ?4616U.M8.U? 2C8"q9~DF? -/` '"2n8;:([4[ '"8T3;'<n0a?4-;'3/%C572V > '"5 -/8 57[4?3/%C53+C5 -3/? 2C8E+(-/? +C5 [4573;.U2([3/%(-;?4:([ %W5n2:=O 6U'"570'"<,.U:(0 57-/'57'O 3/'"<tS>r572'"2('-/[ >V6U?48/8{\%(.MO%.M8 83;-/? 2([461>v<,'"+='"2C<,'"243?42P3;%('VO? 6U? -NO%C57-/[ 's<,'"2C8.13F> ?7A3;%('s0'"<,.U:(0mpkq\$&%('n+(%C5 8;'3/-/5 2C8;.3/.1?42u?7A3;%('. û óàêlóêyèpéP{cîUètúîUóì é6û <vlqtä~é<[påâ ìnøPòlæ<óê . ∗ . ¤M¥. . . ¦. (; S ;/,M ;; ¡"¢/ #¢£. »C¼d½¿¾7¼#ÀÁ ÂºÃ;ÄÅÆ\ÀMÂ#Â½FÇÂMÈ\ÉCÊÃk½/Ë/À½k¼BÌÍªÀ½kÁ7ÍF½. 0a'<,.U:(0x8%(?4:(6M<N0}572(.1AX'"83L548I5§0a?,<,.1y=O"53;.U? 2Y?7A]3/%(' '2('"-;[4>8;+'"O 3/-;:C0|?7ADF'3j%C5 <,-/? 2=8G`S2(?{\2¨5 8G3;%('gDF'3 ^4:C'2CO%(.U2([' '"O 3"q$&%(.M8g' '"O 3j%C548L.12=<,''<t''2s?4t,Z 8'"-;R4'"<E.12O'23;-576C©I:,Zª©_:O ?4616U.M8.U? 2C8«53 √ sN N = 130 572C< e 'ª¬.12@0a'5 8;:(-/'0'23/8«?7A%(.U[ % O%=57-/[ '"< p e 'ª¬L® Th t>ER57-/.Z 572C<E2(':(3;-576(%C54<,-/? 2C8 b pT ∼ 2 − 15 c ? :C8G¯_J_°;K'*S+'-/.U0a'"23/8E m ±²=o"7p.U2Y{\%(.MO%N3;%C'>S.1'"6U<C8 ?7AG.U2CO61:C8;.UR 'O%C57-/[ '<V%C54<,-;?42C8a572C< 0'"8;? 2C857-/' πo AX? :(2C<3/?t'E8;:(+(+(-/'"8/8'<t>5 8I0:CO%548I5A#54O 3/? -G³(´ .12C<('+'2C<,'"23;6U>@? A3/%('.UR576U:(' ´=O ? 0+C5 -;'<@3;?}3/%(' p +(-;?4+='"-;6U>r8/O5 61'<Vµ4µ´L¶Zk©IT:v572C<W+'-/.1+C%('-576_©I:,Zk©I: >.U'6M<(8"q $&%('©IH9°;K¸·u'*S+'-/.U0a'"23g{\.U616B'*S3;'2=<Y8;:CO%¨83;:C<,Z $'ª¬q,¹G:('I3/?%(.U[ %O -/?48/8«8;'"O Z .1'8«:(+§3;? √ sN N = 5.5 3;.U? 2C8I?7A]%C5 -/< +(-/?,O '8;8;'"8_573gHJgK'2C'-/[ .U'"8"´7DF' 38I{\.U6U6 t='j57tC:(2C<(5 243/61>§+(-;?,<,:=O '"<@.U2©GH°;K¸· b DF' 38&{\.3/% 105 e 'ª¬j® +'->4'"57- h '"2C57t(6U.U2([¨t?73/%r.U2CO 6U:,Z pT > 100 c 8.UR '«5 2C<j'*,O61:=8.UR 'ºDF'30'5 8;:(-;'"0'23/8"q°ª2)+=57-;3;.MO :(6M57-´ Î Ï_ÐÑ/Á Ä Ñ/¼ÒÎÓ ÓÔ.

(8) !9ì%&Pð~è_.

(9). Uòèp!¡ìné<ô é<îlø<ñpèàêyèAìnä~îé ìAð_åìnóôSêlåó ãèpÛê .ö òl-ÛêUìnìnñ[ùñpñpèpíÞúPìòUòUìnñUé<æ<ï0ñpä~&<èté<îtøå< û ò(ûP!h¨õ;æ<èèèAò[îUú<ìnæPùæ!ó1è/ëîUòUä~æPñtæ<ìnä~èpî/ð êyèð~!¡ó1òl¨ô æ<èpèê23'ìn4 ìnð~ø<ñpñpè5èpòUúPó ç òlæ<ìn.è ñp)fñpéfèpúPìnòUðrìnìné<ñpñpñpèAèpúPø<ò[îlìnè éPÛñtèä~éÛïé<ó1óøP êìnø<é<é ìnPð ëPètêîlä~î¡<ä~ä~îU7é ñpø<6hîl8èîU$yä~ó:û éN9 û 1þ ;<¡æ<ä~ñ[æÛä~îhé<ónò = è6òlètñ6òlóê ôSã.ö - Pû tü 34 5 Pû þ !¡ô Pû þ. DF' 3¸3;?4+=?461?4[ > b DF' 3\8%=57+' ´ DF'3 7ÁX-57[40a'"23/53/.1?42 AX:(2CO 3;.U? 2Ć' 3/O q h O? :(6M<§t'L0'"5 8;:(-/'"<3;?? t,3[email protected],AX?4-Z 0}53/.1?4257t? :,3_3/%(''"2('-/[ >@-;'<,.M8F3/-;.Ut(:,3/.1?42N?7Al3;%('IDF' 3 5A3/'-3/-/5R4'-8.U2([B3/%('l0a'<,.U:(0zmUo opdq $&%(.M8`.U2C<g?7A8F3/:C<SZ .U'"8-/'"^:(.U-/'"8.M<,'23;.1y=O"53;.U? 2j? ADF' 3/8572C<L0'5 8;:(-;'"0'23"´ 5 8G5 O"O :(-53/'6U>§5 8I+=?8;8;.1tC61'4Ć?7Al3/%('+C5 -3/? 2? -«DF' 3g'2,Z '-/[ >t='AX? -/'&5 2C<a5A3;'"-«^:('2=O%(.12C[Cq7©R '"-;>E533/-/54O 3/.1R4' 0' 3/%(?,<)3/?g+'-;AX? -/0 3;%C.U8l0'"548:C-;'"0a'"23.M83;?g3/5 [«DF'3/8 {\.13;%Y+C-;?40a+(3g+(%C?73;?42C8G'0.3;3;'<? +C+=?8.13;'3;?@3;%('GDF' 3 <,.U-;'O 3/.1?42q f %(?73/? 2C8G'0'-/[ 'E576U0a?8F3G:(2C57613;'"-;'<AX-/? 0 3;%C'<,'2=8'j0'"<(.1:(0x5 2C<+(-;?RS.M<,')50'"548:(-/'0'"243\? A 3;%C'@?4-;.U[ .U2C576¸'2('"-;[4>¨? A_3;%C'§+C5 -3/? 2V'"0a.133/'"<r.12r3;%(' ? +C+=?8.13;'j<,.U-;'O 3/.1?42q G2? 2('L%C5 2C<º´,3/%(.U8IO ? .U2CO.U<,'"2CO ' 3;'O%(2(.M^:('&{\.16U6,%('6U+E3;?L61?,O"576U.1w"'i8;+C53/.U5 616U>j3/%('DF' 3«572=< ? 23;%C'? 3;%('"-%C572C<.13}5 616U?{_8E3;?st(:(.U6M<V3/%('+C57-;3;?42 AX-57[ 0'"24353/.1?42)AX:(2CO 3;.U? 2}{\.13;%(?4:,3B3;%C'\2(''<E? A-/'"O? 2,Z 83;-/:CO 3/.12([i3/%('DF' 39'"2('-/[ >&AX-/? 0v3;%('«<(' 3;'O 3/'"<g%C5 <(-;?42C8q $&%S:C8"´0'<,.1:C0 ' '"O 3/8&O ?4:(6M<§t'jO%C57-5 O 3;'-/.Uw'"<tS>§5 O%C5 2([ '¸?7A(3/%('\8%C5 +='¸?7A=3;%('¸AX-/5 [ 0'2353;.U? 2)AX:(2CO 3/.1?42´ .dq7' qU´tS>5g-;'<,.U83;-/.Ut(:,3;.U? 2a-53;%C'-l3;%=5725G-/'"<(:CO 3/.1?42E? A 3;%C']DF' 3&'2C'-/[ > q °ª2©GH°;K¸·_Ć+(%(?73/? 2C8\5 -;'L<,'3;'"O 3;'<@tS>}3/%('j+(%(? 3;?42 8;+='O 3;-/? 0'3;'- f J m1o²=o 7p 572=<_3/%('lAX:,3;:C-;'B'"61'O 3;-/?7Z 0}57[42(' 3/.UO&O5 61?4-;.U0' 3/'-l· ¨Ki5 6m1o³,´;o pkq$&%('&.U<('23;.1y(Z O573;.U? 2+=?{i'-&? A+(-/? 0+,3_+(%C?73;?42C8&53_6U?{ .M8&6U.10aZ p .13;'"<tS>}3/%('jtC5 O`S[4-;?4:(2C<O-;'53;'<tS>@<('"O5>}T+C%(?73/? 2C8 b 0}5 .12(6U> ´ 0 h q,©i3\%(.U[ %('"{\%('"-;'G3;%C' π → γγ p , γ/π 0 -53;.U?j.U2CO -/'"548'8´3/%('I-/'"<,:=O 3;.U? 2? AT3/%('I?4+='"2(.U2([)572([461' t' 3F{i''2+(%(?73/? 2C89+(-/?S<(:CO '83/%('«0'-/[ .U2([_? A(t=? 3;%a<,' Z O5>\+C%(?73/? 2C8.U23;?\5¸8;.U2([ 6U'B8%(?{i'-0.10.MO`S.12([\5&8;.12([461' +(%(? 3;?42q$&%C'"8;'0'-/[ '<+(%(?73/? 2C8g57-/'E5tC5 O`S[ -/? :C2C< AX? -a+(-/? 0+,3+(%(? 3;? 2=8+C5 -3/.UO:(6M57-/61>s<,. }O:(613E3/?n8;:(+,Z +(-/'"8/8qS°ª2§3;%(.M8&+C57+'-´S{¸'g{\.U616<,.M8/O :C8/8¸3;%('gAX'"548.Ut(.U61.13F> ?7A=.U<,'"23;.1AX>.U2([g+(-/? 0+,3+C%(?73/? 2C8.12µ µ§5 2C<j%('5R>Zk.1?42 O ?4616U.M8.U? 2C8tS>_8;%(?{¸'"-C3/? +? 6U? [4>&5 2C576U>,8.M8 1 m1o±(´¿o 7p572=< .M8?46U573;.U? 2O -/.13;'-/.M5(q °ª25EAX? -;3;%=O ? 0.U2([a+C57+'-´S{¸'j<,.M8;O:C8/8«3/%('L.U<('23;.1y(Z O573;.U? 2?7Aº+(-/? 0+,3;Zd+C%(?73/? 2gDF' 3«'"R '"2438]572=<a3;%('_-/'"O? 2,Z 83;-/:CO 3/.1?42}?7A%C54<,-;?42,ZUDF' 3]AX'53;:C-;'8_mUo pkq. . . . φ. . F. φmin. . φmax. 220◦. 320◦. . 60◦. 180◦. . 0◦. 360◦. > @?BAC ED F (GIH JH KFLH JMNC H,"OC DjPM *C C C JC:PA C OC (D °ª2©IH9°;K¸·_´ +(%C?73;?42C8l{\.U616,t'_<,' 3/'"O 3;'"<atS>j3/%('\+(%(? Z 3;? 2 8;+='O 3;-/? 0'3;'- f J v{\%C.UO%P'2C5 t(6U'"83;?0'"57Z 8:(-/'{\.13;%G%(.1[4%_+(-/'"O.U8;.1?42&3;%('".1- Zd0? 0'"2435(´/57613;%(?4:([ % ? 2(6U>L{\.3/%E5G-;'<,:CO '<)5 O"O '"+,3/5 2CO 'i572C<)5 6U8;?ItS>L3/%('«AX:(Z 3;:(-/''"61'O 3/-;?405 [ 2('3;.MOO"576U? -/.10'3;'-· ¨Ki5 6{\%(.MO%I%C548 6U5 -;[4'-E54OO'+,3572CO' b $57tC61'no h t(:,3}6U?{¸'"--/'"8;? 6U:,3;.U? 2 3;%C5 2 f J q7K¸%C57-/[ '<I+=57-;3;.MO 6U'"883;-/'"5 0a.U2([&AX-/? 0DF' 38 57-/'i<,'3;'O 3;'<at>)3;%('_$ f KG´73;%('\0}57.U2<,' 3/'"O 3/? -B? A=3/%(' ©IH°;K¸·TO'23;-576S3/-/54O`.U2([L8>,83;'"0q4J_'-/' ´ {¸'iAX?,O :C8]? 2 f J ¨3/?<,' 3/'"O 3a+(%(? 3;? 2=8q9$&%C'§5 O"O '+(3/572=O '"8L? A_576U6 3;%('a<,' 3/'"O 3/? -8_-/'6U'R5723GAX? -_3/%(.M8G83;:C<(>57-/')-;'"+=?4-3/'"< .12§$57tC61'aoG5 2C<}3/%('.U-¸6U?,O573;.U? 2.M8i+(.UO 3;:(-/'"<§.12 .1[=q=o4q © AX:(616i<,'"8/O -/.U+,3;.U? 2s?7A&3/%('©IH9°;K¸·z<,' 3/'"O 3;? -)O"572st' AX? :(2C<.12§¯_' AFqm1o pkq K¸?42CO '"-;2(.U2([ 'R4'23 [ '"2('-53/.1?42Ń{¸' O? 2C8;.M<,'-/'"< +(-;?40+,3@+(%C?73;?42u+(-/?,<,:CO 3;.U? 2v.U2v3/%('¨6U'"54<,.U2([r?4-/<,'"?7Al3;%(' 3/5 2C<(5 -/< N?,<,'"65 2C<N2('*S3I3;?§61'5 <,.U2([?4-/<,'"AX-/5 [ 0'23/573;.U? 2@+(%(?73/? 2C8"qC$&%(')5 .10 ?7Al? :(-\.U2SR '8F3/.1[5Z 3;.U? 2.M83;?L<,'R4'6U? +5 2E5 61[4? -/.3/%(0PO"57+C5 t(6U'¸? AC.U<('23;.1AX>Z .12([a+(-/? 0+,3\+(%(? 3;?42C8\572C<@?7A0.12(.U0.1w".12C[E3/%('L{\-;?42([ .U<,'"23;.1y=O573;.U? 2W?7AL+C57-;3;.MO 6U'"8"´l05 .12C61> ´«548+(-;?40+,3 π0 +(%(?73/? 2C8"q\$&%('-/'s57-/'n8;.1[42(.1y=O5 243N<,.M8;O-;'"+C572=O .U'"8@t='Z 3F{¸'"'2¨3;%('}'"R '23j[ '"2('-53/? -8 f $\JI°F©x´9J_·¸¯ Q° e 572C< IH O"576MO :(6M53/.1?42C8q°ª2 3/%('Q+(-/'"8;'23r83/53/'Q?7A `2C?{\61'<,[ '4´3;%C'-/'§.M82(?n8F3/-;?42([¨5 -;[4:(0'23.U2VA#5R4? ?7A5 2>}? A3;%C'"8;'G[4'2('"-/573;? -8"q °ª28:CO%O .U-/O:(0}8F3572CO'"8"´ {¸')548;8;:(0'"<@3;%=53 f $\J_°F©z.U8_5-;'5 8;? 2C5 t(61'g? +(3;.U? 2 3;?<,'"0? 2C83;-53/'\3;%('GR576U.U<,.13F>?7A?4:(-¸5 +(+(-/?45 O%9q °ª23/%(.U8¸+C5 +='"-"´ 3;%(?8'G'R '"23/8]O? 23/5 .12(.U2([5)+(-;?40+,3 +(%(?73/? 2V5 2C<T5DF' 357-/'}-;'AX'-/-;'<¨3;?¨548 DF' 3a'R4'23/8"q γ $&%('<(? 0.12=5723º+(-;?,O'"8/8'8=O? 23;-/.1tC:,3;.U2([&533;%('l+C5 -3/? 2 61'"R '657-/'&3;%('jK¸? 0+,3/? 2572=<}572(2(.U%(.U6U573;.U? 2}+(-/?,O '8;8;'"8. . . . . . RQ. ,S. @. T. .U. YX Z. WV. .U. fúñpèpìnð~ô9ê ð~òUîìnä~ñpêyó%òlð~è$"ä~ñpð~¡îUètæ<îhæ<ó ä~ä~¨ñ[éæ0èpòUêtèpòlûêlæ<ìn!hñ6è òUæ<ä~Pèé<èpåîUòlæ<èpñ6ó äòU¨òlóæ2èpêê"òUä~æP¡îÛèä~îlð~ñ ð+øìn& íÞð~ó<ìnêyä ä~'ùí2èÞä <è6èîUòUä~Nèpåêû(éf¡ìn!hð¨ä~æ<ð~ä~ðè;é ú<îUêyPæ<ó ä ìn<#úøPèpèêyñtèpèé!ó%ìò $ òlä <æ<èpèAéñpòUð~ä òø<ëîyû òUèpêyîó%$Hñpèpð~ð~î*)<êlè +&ëÛòlæ<èAú<ìnêyòlä~ñpð~èàä~é,$óêlí2îì%&óøPòä òlî 7. . . . . . º S "! ¨ ,!# ( (!¿ S S Sg 4= " "!¿=. . F. . . . . F. . . . η. (|η| < 0.9). |η|. . 1. . . . . . ". . [. \.

(10) g + q → γ + q,. b o h. q + q¯ → γ + g.. $ %('"8;'9+(-/?,O '8;8;'"8C{¸'"-;'98;.U0:(6M53/'"<\tS>i3;%(''R4'23=[4'2,Z & '-53/? - f $\JI°F© Cq ±Ym1o ´; pAX? -Gµ µrO ?4616U.M8.U? 2C8G53 √ $9'ª¬Eq¸$&%('Y<(' A#57:C63§+=57-;3;? 2Q<,.M83;-/.1t(:(3;.U? 2 s = 5.5 AX:(2CO 3;.U? 2´ e ¯¬ HQm (o pkĆ{&5 8\:=8'<ºq ,.12CO')3/%(')+(-/?7Z <,:CO 3;.U? 2)O-;?8;88;'"O 3;.U? 2C8<,-/? +j^:(.UO`S6U>G{\.13;% ´"'R4'23/8 p {i'-/'Y8;5 0+(61'<.12v3;%('NAX?4616U?{\.U2([ t(.U2C8 2T b 57t? :,3 pˆ o"C´ 4 n'R4'23/8+='"-t(.U2 h ´ T ´ ´ [20, 40] [40, 60] [60, 80] e 'ª¬L® q$?I? t(3/57.U25GO ? 23/.12S:(?4:C89<,.1'-;Z 572=< [80, 100] c '23/.U5 6O-;?8;88;'"O 3/.1?42C8?R '"-C3/%('l{\%(? 6U' Zk-572([4' ´;3;%('8' pˆ AX? :C-8/570+(6U'"8{i'-/']{i'.U[ %3;'<LtS>G3/%('.U-TO? -/-;'8+? 2=<,.12C[ O -/?48/8i8'O 3;.U? 2=8iO"576MO :(6M53/'"<§t> f $\J_°F©q(°ª2? -<,'-¸3;? '2C-;.MO%3;%(')8/570+(6U'j{\.3/%'R '"23/8_<,'3;'O 3;'<.12 f J ´ {i'E-/'"83;-/.UO 3;'<N3;%C'a[4'2('"-/573;'<N+(-/? 0+,3L+(%(?73/? 2C8G3/?5 8;? 6U.U<n572([461'}8;61.U[ %3/61>6M57-/[ '"-g3;%C5 2¨3/%(' f J ¨54OO'+,Z 3/5 2CO '3/?5R ?4.U<Y+=?8;8;.1tC61'}t? :(2=<(57-/>' '"O 3/8"´9<,'yC2('"< tS>3;%('L-572([4'"8 AX? -i3;%('L+C8;':=<,? -57+(.M<,.13F>.12 |η | < 0.2 3;%C'\'R '"23BO'23;'"-Zkγ?7AZk0}5 8/88;>,8F3/'0z5 2C< 200◦ < φγ < ◦ AX? -]3/%('G5 w.U0:,3/%C576572([461'4q 340 ·]R '"24389{\.13;%)3F{¸?BDF'3/8.12)3;%('«yC2C576S83/53/' Ó5 616U'"<iDF'3Z DF' 3j'"R '238´57-/'E58.U[ 2C.y=O"5723g8;? :C-/O'?7A¸tC5 O`S[ -/? :C2C< AX? DF'3'"R '238q $&%('">\{¸'"-;'l8.U0:C6U573;'"<ItS>\%C57-< c Ki¹ γ +(-/?,O '8;8;'"8B.U2}3/%('G6U'"54<,.U2([)+ c Ki¹? -<,'-´. .U. . . . \. U. . [. q + q → g + g,. .U. q + q0 → q + q0 , q + q¯ → q + q¯,. b h. q + g → q + g,. 3. Pèpòlèpñ6òUóêyî û. @. 8X. 0. b<2. g + g → g + g,. /N¶

(11) µ/ PN1O . ,qUo q

(12) µ. $&%('"8;'+(-/?,O '"8/8;'"8O? 23;-/.1tC:,3;'N3/?V3/%(' DF'3@tC54O`4Z γ [ -/? C : 2C<V3/%(-/? :([4%W%=57-<rAX-57[40'23/573;.U? 2r+C%(?73/? 2v572=< Zd0'"8;? 2}+C-;?,<,:CO 3;.U? 2548«8;''2§.12§¯_' AFqm 4pkq π0 $9?W8.U0:(6M53/'n5O ?4243/.12S:(?4:C8 Zª8;+='O 3;-/:(0 ?7A Z p π0 0'"8;? 2C8¸AX-/? 0 )3/?o e 'ª¬L® ´,T{¸'g[ '"2('-53/'"<%=57-< c c Ki¹v+C-;?,O '8;8;'"8].12}'".1[4%43¸t(.12=8]?7ABo e 'ª¬L® {\.M<S3/%.12 c 3;%C' -/5 2([ 'AX-;?40±4l3;?Io" e 'ª¬L ® 572=<&.12IAX? :(-=0a?4-;' pˆT t(.U2C8\? Al³7 e 'ª¬j ® g{\.M<S3;%.U2@3/%(' -572C[ 'GAX-;?40|o"4 pˆ 3;?)±4 e 'ª¬L ® b 5 t=?4:,3_o³ (´ I'R4'T23/8l+'-]tC.12 h q $&%(' {\%(?461' 8+'"O 3;-/:(0 {&5 8«3/5 ` '25 8«3;%('j8;:(0 ?7A93;%('8'. [. $&%(' <(.U83;-/.1tC:,3;.U? 2C8¸? t(3/57.U2('<aAX-;?40 8;.U0:(6M53/.1?42C8 p {¸'"-;'i2(? -/T0}576U.1w"'"<3;?g3;%C'_2S:(0t'-B? A'"R '238l' *,+='O 3/'"< .12N58F3572C<C57-<§>4'"57-\? AlHJgKv-;:C2(2(.U2([ b 8;'')$57t(6U' h q ©I8G{¸'a8.U0:(6M53/'"<¨<,.'-/'23 t(.12=8´'"54O%N? 2('E{\.3/% pˆ 5a<(.'-/'23\2S:(0t'-_? A'"R '238T´,{i'j+(-/?SO''<,'"<@.123/%(' AX? 6U61?{\.U2([j{&5> ²Q$&%('N-5{ <,.M83;-/.1t(:(3;.U? 2C8}{i'-/'2(? -/0}576U.1w"'"<r3;?s3/%(' 2S:(0Et='"-\?7AB8.U0:(6M53/'"<'R4'23/8&.U2'"54O% t(.U25 2C< pˆT 3/?I3/%('iO-;?8;88;'"O 3/.1?42C8lO5 6UO:(6U573;'<jtS> f $\JI°F©)q .1Z 2C5 616U> ´3/%(')<,.1'"-;'"243_<,.M83;-/.1t(:(3;.U? 2C8&{i'-/'gO? 0Et(.12C'"< 3/?g?4t,3/5 .12E3;%C'&<(.'-/'23;.M576(O-;?8;8l8;'"O 3;.U? 25 8B5GAX:(2CO Z 3/.1?42}?7A q. \. .U. pT. ãèpêyè ú<êyó!ñtèpêyîlè8îU$èpèpêlîî¡ä~éòUóòlæ<òlæ<èpèä~êBòlñpêUèpìné!é<òlîIèp'êyèpçwêló%îl$èAçíÞí2ìnóîlí2îBîyèpëPéîyòUòUø<èpí íûó%$còlæ<èæfìnê pˆT. 5. . 2→2. 2. , . 8;5 0a+C61'8º{¸'".1[4%3;'"<LtS>g3;%C'.U-O ?4-;-/'"8;+? 2C<,.U2([_O-;?8;88;'"O Z 3;.U? 2C8"q,$&%('L[ '2C'-53;.U? 2@?7A9%=57-< c Ki¹ +(-/?,O '8;8;'"8¸{i548 -;'8F3/-;.MO 3/'"<.U23;%('j+C-;?,O '8;8&O'23;'"-Zk?7AZk0}5 8/8i8;>,8F3/'0 3/? 5 2C<j.U2j3;%('¸'R4'23O '"23;'-;Zk?7AZk0548;898>,8Z |yparton | < 0.2 3;'0 3;? ´{\.13;%C? :,3572S>n5 w.U0:,3/%C576i572,Z |η | < 0.15 [ 6U'«6U.10.13/53/jet .1?42q¹I:('¸3;?G3;%C'i8;0}576U6 f J )54OO '"+,3/5 2CO '4´ {¸'g%C5 <3;?-/'"83;-/.UO 3¸3/%('L-/5 +(.U<(.3F>}-572([4'I? A[ '"2('-53/'"< DF' 3ZUDF' 3_'"R '"2438i0a?4-;'L8;'R '"-;'"61>3/%C572@3;%=53\?7A3;%(' Z1DF'3 γ 'R '"23/8"q $?8;.10E:(6U573;'_'"R '"2438]O ?4-;-/'"8;+? 2C<,.U2([L3/? f t,Z f t@O? 61Z 61.M8.U? 2=8´ {i'«548;8;:(0'"<G3;%=535 f t,Z f tO ?4616U.U8;.U? 2L.U89'"^:(.URZ 576U'23I3/?@5µ4µrO ? 6U6U.U8;.1?42O ?424357.U2(.U2([§?4:(-G8;.1[42C576d´+(61:=8 572|:(2=<,'-/61>S.U2([ %('"5RS>Zd.U? 2|O? 6U61.M8;.1?42Ó? 2C83;.13;:(3;.U2([ 3;%(')t=5 O`S[ -/? :(2=<ºqC$&%S:C8"´,µ µVO ?4616U.M8.U? 2C8_[ '2C'-53;'<t> f $\JI°F©)´l{¸'"-;'§0a'"-;[4'"<T{\.13;%%('"5RS>Zk.1?42sO? 6U61.M8;.1?42C8 +(-;?,<,:=O '"<tS>j3;%('\JI ° ° e o q ± Em7±p,'"R '23l[ '"2('-53/? AX? - f t,Z f tuO? 6U61.M8;.1?42C8}53 √ $'ª¬ 572=< s = 5.5A .10+C54O 3«+C5 -/5 0' 3;'"AX0q N N. . g + g → q + q0 .. ä~å<û û cìtëóøPòó%$P'nìnêlä~óø<î . ¿. pT. 2→2. ±. 0Q.

(13) .

(14). . . L. ¤. ¤ ª¦. ;¦. . 1030. 107. 0.5 1027. 106. . . F. . . d σ/dp T (mb c/GeV). #. . . ¤. . ¦. fC. . . hTAA iC. mb−1. . 102. 10-9. 10. 10-10. 1. 20. . d σ/dp T (mb c/GeV). \. O. N\. 40. 60. 80 100 p T (GeV/c). 10-2. ²v$&%(')<,.1'"-;'"243/.U5 6O -/?48/8\8'O 3/.1?42@{&5 8&0E:(63/.1+C61.U'"<tS> 3;%('a.123/'[ -53/'"<N6U:(0.U2(?48;.3F>'*S+'"O 3;'<.U2Y? 2C'E-/:(2,Z 2(.12C[)+='"-;.U?,< 43;%('G61:(0.U2(?48;.13F> 572C<-/:(2(2(.U2([j3/.10' L 57-/'6U.M8F3/'"<L.U2)$5 t(61'«(q$&%('«O-;?8;8º8;'"O 3;.U? 2C8.12 f t,Z f t O ? 6U6U.U8;.1?42C8G{¸'"-;'E? t,357.U2('"<AX-/? 0 3/%(?48;'E.U2Nµ4µrO ? 6U6U.Z b ·«^q b ± hh 8.U? 2C8itS>57+C+(61>S.U2([E3;%(' FtC.12C5 -;>8/O5 61.U2([ <,'"8/O -/.1t'"<.12§<(' 3/5 .16M8].U2§¯\'A#8qm C´F4³p. 103. 10-8. . . pp collisions jet-jet γ -jet. 10-7. PbPb collisions. . 103. jet-jet γ -jet. 10-3. 102. 10. dN/dpT (counts c / GeV). 2í ètèpìné!í)ò <ð~ø<ø<í2êyä~é<ä~éPå óìîUä òîlë òUìnìné é fìnê êl|ø<éPëé<ètä~ìné<êBåó%òl$Sä~í2êlø<(è éPé<$óä~é<êhå òlæ<ìè ò 5 ã û 3Cè úèpêlä ç óð~ð~ä~îUä~óé ñpí /î ;ò î ô &Pç ô & H!9ìné %ììn&<ð~ø<ð~$ èèpóî¡ê %ó <$cä #òlæ<èpèêlèpé!éø<ò¨ñpñpð~óètð~ìnð~êä~îUä~ó ó'é2ètêyñpð_èpìné!ú òlêl$ø<ìnð~é<ä òUñ6ä~òlèpä~î+ó7é òUìn$ùóètêhé Pô $&Pêlóç ôí &5 ñpú<óð~úð~ä~ètîlé ä~ó<é<ä î ¨%ó $29 ü %;û èpé!òlêUìnð~ä òë . ý Pû ý

(15) ü Pû Pû

(16) ü Pû ü í2ä~é<ä~íAø<Lí &<ä_ìnî ýPû

(17) ý . -4. dN/dpT (counts c / GeV). !9ì%&<ð~è/ü. 10 10-5. . d2 σAA dpT dy. . C. geo = hTAA iC · σAA · fC ·. d2 σpp b ± h dpT dy. 1. {\%('-/' .M8¨3;%('+(-/?,<,:CO 3s? A3;%C'Q2:=O 6U'"57hT iC ?R '-/6M57+AX:(AA 2CO 3;.U? 2ÄX? -g3;%C'aO? -/-;'8+? 2C<(.12([O '"243/-/5 6Z .3F>YO6U548;8 l´ .M8L3;%C'3;%('}O '"23;-576U.3F>NA#54O 3/? -)572=< fC 0t.M8«3;%('g[ '"? 0' 3/-;.MO5 6=O -/?48/8«8;'"O 3;.U? 2 geo σAA = 7745 ¯\' AFqGm 7pkq]$&%('O ?4-;-/'"8;+=?42C<,.U2([nR5 61:C'"8AX?4-§<,.1'"-Z '23gO'23;-576U.3/.1'8G5 -;'61.M8F3/'"<Y.12Y$57tC61'a±(q$&%('aO-;?8;8 8'O 3;.U? 2{&5 8B5R4'-57[ '<j? 2}O'23;-576U.3F>L3/?j? t,357.U2a3;%(' O -/?48/8]8'O 3/.1?42}AX? -¸0a.U2(.U0:(0 t(.M5 8iO ?4616U.M8.U? 2C8"q ¨'a? t,357.U2('"<t>3/%('57t?R ')+(-/?,O '<,:(-/')3;%C'a8;+='O Z Zd6U.1`4' b DF' 3ZUDF' 3 h 3;-5? A«+(-/? 0+,3L+(%(? 3;? 2=8 b ZUDF' 3 h 5 2C< γ γ .U2µ µV572C< f t,Z f tYO ?4616U.M8.U? 2C8G53g³(q ³ $'ª¬z' *,+'"O 3;'"< 3;?t'a<,'3;'O 3;'<.U23/%(' f J ¨5 OO'+,3572CO'<,:(-/.U2([5. 10-6 20. 60. 80 100 p T (GeV/c). wç ä~ð~å<Pä~ùûHèpè òlüPèpûWñ6îUòU-ä~è é<ú2åèpð~ñ6ä~è2é/òUêlìnôHìÖé ãBJó%ö.$ó1-ú<'ïèpêyó$êyóð_í2ìnêú<úPúòÞ è ú<øPæ<ú<ú ónæ<còlóónìné<òlé óî Aé<îí2$çä~yêyéPè6óä~òííàèø<y'í è6èpòléç&PyòUä_è6îtìnòï îSè ô'2&Pètìnéç ôéòlî & ï = îlè <èpñpóúòlètä~óñ6é òlé<è îàñpìnóé!êlð~ø<ð~è ä~í"îUåä~ó&ä 'é<èpèpîêHéÖó%ìò$NóéñpóòUø<æ<é!è òlî¨ð~èó$éò òlæ<ç èBì êyä~ä~îàå!cæ!è ó%àò $¡û òUç æ<ì è ä #ä~ú<î èpûð~êlónèpòléîónòUòlä_ìnæ2ìné ðr÷ñpø<êlòlìnóæ<éPîlèîç òlä òlä~ètîBìnêlè <è6òlètêyí2ä~é<è $óêBìîyò[ìné <ìnê cã êyø<é<éPä~é<å2ëè ìnêpû. . . γ •¤ ¦ . . ª. V. . 40. ¤. . F. ¦. F. «. ¤ γ. F. ¤ 7¦ √ sN N = 5.5A M

(18) y /. F. . ¿). W. . ◦¦. . . y / . . Q. h 0 '"-;[4'"<Ö 6U:C8F3/'-8 b 5 6U8;?NO576U6U'"<¨? 2('ZkO61:C83;'"a 0 q9¹I:C' π f 3;?3;%(' J n[ '"? 0' 3/-;>4´?R '-/6M57+(+'"<Ö 6U:C8F3/'-8L%C57+(Z +='"2V'"8/8'"23;.M576U61>YAX? ?7A\'2C'-/[ >nt='"> ? 2=<T± e 'ª¬q π0 $&%('"8;'T+(%(? 3;? 2=8O ?42C8F3/.3/:,3;'V3;%('V0}5 .12 tC54O`S[ -/? :(2C< AX? -+(-/? 0+,3@+(%(?73/? 2.M<,'23;.1y=O"53;.U? 2v5 2C<O ?4243/-;.Ut(:,3/' 8.U[ 2(.1y=O"5723;6U> 3/? 3;%C'u.U2CO 6U:C8;.1R4'v+(%(? 3;? 2 8+'"O 3;-/:(0q $&%('¸8;+='O 3/-/5I?7A,3;%C'i<,.1'-/'23+(%C?73;?42,Zk61.U` ']'"R '"24385 2C< 3;%('".1-E-;'"6U573;.UR 'O ?423;-/.1t(:(3;.U? 2n3;?N3/%('§+C-;?40a+(3Zk+(%(?73/? 2 8+'"O 3;-/:(0zAX?4O ?4616U.U8;.U? 2C8¸57-/'_[ .UR '"2}.12 .U[Cq±(q. 83/572=<(57-<j> '57-?7ACH9JLKn-/:(2(2(.U2([C´<,.M8;+(6U5>4'"<L.U2 .U[Cq7,q. 7

(19) ¶ O . . ,q,q. ~i54O`S[ -/? :(2C<z'R4'23/8T5 -;'v<,:C'Q05 .12C61>z3;? <,'O5> 5 2=<xt(-/'0}8;83;-57%C61:(2C[ +(%(?73/? 2C8P572=<x0.U8;.U<('23;.1yC'"< 7 %C54<,-;?42C8"q¸¹G'"O5>+(%C?73;?42C8§AX-;?40 DF'3ZUDF' 3'R4'23/8O5 2 t'<,' 3/'"O 3/'"<¨.12 f J n5 8L'.13;%C'-)8;.12([461'a+(%(? 3;?42C8L? -. . . pp. Q.

(20) . A#5 83=-/'"O ?42C83;-/:CO 3/.1?42i0'3;%(?,<I<('"8/O -/.1t'"<\.U2 ,'"O 3/.1?42I±(q {i548]57+(+C61.U'"<ºq. d σ/dp T (mb c/GeV). 10-6 hadron π0 π01 clust+γ decay+γ brems π01 clust γ decay γ brems. 10-7. ±(qUo q. X. 10-9. 0.013 0.036 ∆E = ⊕ √ ⊕ 0.0112, E E E. 10-10. prompt. 10-11 20. 40. 60. /(d σ/p )γ. T. Q. ±(q,q. 40. 60. . √ s = 5.5 F. (•). M

(21). (N) () π0. (). F. γ . C D«(DCEPM(C*CCS. ] # π 0 (M) ¤ s z . ). . . .U . . D. "=. V. W

(22) :¶_µ/ L¶0N . ZS. . °ª2s3;%(.M8)8;'"O 3/.1?42´{i'<,'"8/O -/.Ut='3/%('-/'"8;+=?42C8'aAX:(2=O Z 3;.U? 2=8G? A f J Y5 2C<N3/%('}$ f KGq n'a:=8'<N3;%C'8;.U0:,Z f 6M53;'< $\JI°F© b µ4µ h 5 2C< f $\JI°F©J_° 4° e b#f t,Z f t h 'R4'23/8<,'8;O-;.Ut='<Q.U2 S'O 3;.U? 2P,´&572C<u{¸'¨+='"-Z AX? -/0'"<5ÄX:(6U6ZC'"<([ '"< N?423;'¨Ki57-/6U?s8;.U0:(6M53/.1?42? A 3;%C'_3;-572=8+? -;3]?7A+C5 -3/.UO61'8].U2 f J q$&%C'_{\%(? 6U'_.U2,Z AX? -/0}53/.1?42?7A3;%C'_O%C57-/[ '<j+C57-;3;.MO 6U'"8BO? 6U61'O 3/'"<Et>)3;%(' ©IH9°;K¸·WO'23;-5763/-/54O`.U2([a8>,83;'0 {&5 8¸:C8;'"<º´,tC:,3&3;%('. .U. . S. 80 100 p (GeV/c). lòä~|ä~ñtå<ð~èpñpû îóPð~<ð~û ä~è6îUòlä~óèpú<é<ñpúòlîhèpè êìJò $ä~êléìní2ôSè ãö.îUú-Ûèpîlñ6!còlòUèêyêlè ì|ìn í2%ó $ ä~éP<åBä #òUón$èpêlòUêlóìnèpí ðéòàæfì ìnú<ê yæPèpónòyòUç óyè6éPòçwð~è ä~ù'èèpé!óú<òé<ìnèä~êyé ç ñp1ó ð~'ø<èpîlêyòlð_èpìnêú<úè < è6 òUèpñ6òUè óé<ä~è6é2çñpôHð~ø<ãBîyòU.ö èp-ê ú<ú<ð~ø<æPî2ónòUú<óæPé<ónî òU$óêyé<óî í $êl<óèpí ñtìtë <èpñté<ìtónë ò òlòlìnêlä~é óø< í %ó úP$ æ<åónèpòUé<óèpéPú<êlî(ìæ<òU$ónêyè òló0óí é<úPPî æ<&<$ónêlêyóèpòUí2óí éîUç&<îyð~òUä~êyùêlètìnèí2æ<îlúfð~ø<îlìnòlé<ê êUòUå ìnä~æPñpð~ð~èpø<îÞé<å<ä~é òlû ónlòUóè6ìn¨òyðrç lèpæ<è6ê ì ò2$<êUèêlìnó'í2é|èpé

(23) è îlòU%úîÞ6ètòUìñ6ó çç ú<êyóí2úPòú<æ<ónòlóé;ä~é ç yèpòBè 'ètéòlî F. . $&%('«A#5 83-/'"O? 2C83;-/:CO 3/.1?42L+(-;?RS.M<,'"85\+C5 -/5 0a'3;-/.1w"'"< -;'8+? 2C8;'a?7A&°F$ rm 7p¸572=<¨$ f K m pBAX? -j6U? 2([ Zd6U.1R4'"< O%C57-/[ '<§+C5 -3/.UO61'8qC°ª23;%(.M8\A#548F3I-/'"O? 2C83;-/:CO 3;.U? 2sm ±4pk´ O%C57-/[ '<G+=57-;3;.MO 6U'"857-/'«<,' 3/'"O 3;'"<{\.3/%572E572([4:(6U5 -9-/'"8Z 572C<5O ?42C83/5723g0a?40'23;:(0 ? 6U:,3;.U? 2? A ∆α ≈ 1.1◦ -;'8?461:,3/.1?42 q=$&%('8'j-/'"8;? 6U:,3;.U? 2=8_57-/'L3;%(' ∆p/p = 2 % 05 .12L+C5 -/5 0' 3;'"-/8? AS3;%(' e 57:C8/8.M572L8;0a'57-/.12C[_57+(+(6U.U'"< 3;?L3;%C'_[ '"2('-53/'"<±Zk0? 0'23/5Cq7©\A3/'-&80'"5 -;.U2([=´+C57-;Z 3;.MO 6U''2('"-;[4.1'8{¸'"-;'N-/'"O"576MO :(6M53/'"<.12u? -<,'-3/?rO ?42,Z 8'"-;R4'¸3/%('_+C5 -3/.UO61'I0548;8;'"8"q7$&%('I<(' 3;'O 3/.1?42572C<.M<,'2(Z 3;.1y=O573;.U? 2+C-;?4tC57t(.U6U.3F>L{&5 893/57`4'2a5 8 P{\.3/%(.U23/%(' +C8'":C<,? Zd-57+(.M<,.13F>-572([4' 572=<AX? -«3;-572C8;R '"-/8;' |η| < 0.7 0a?40'23/5 N'ª¬L® 5 2C<{&5 8&O ?42C8;.U<,'"-;'<3;? p > 150 c R5 2(.M8%}?4:,3/8;T.U<('I?7Aº3/%(.M8«-572([4' q. T. 9. b ³ h. {\%('-/')'2C'-/[ .U'"8I5 -;'E[ .UR '"2N.12 e 'ª¬ 5 2C<N+?48;.3/.1?42C8I.U2 O 0q (?4-0? -/'B<,' 357.U6U88;''\mUo"±C´¿o 7pkq $&%(' f J g'2('"-;[4> 3;%(-/'"8;%(? 6M<.M8«(q³ e 'ª¬Eq. 2. 0 20. (F). . :. 0.229 σx = √ ⊕ 0.096 E. 1. . h. 0V. (d σ/p ). T i,jet-jet. 80 100 p T (GeV/c). . brem. π0 F7¦. b. {\%('-/'j3;%C''2C'-/[ >.U8I[ .UR '2N.U2 e 'ª¬ :(2(.13/8 3 m1o C´ pkq S.10E:(6M53;.U? 28;?7A3F{&57-/' ´,{\.13;%C.12Y3;%('jAX-570')? A«©_6U.U¯_?? 3 m pk´/{&5 8=3/:(2('"<I3;?&-/'+(-/?,<,:CO'93/%(.U8'"2('-/[ >\-/'"8;? 6U:,3/.1?42q $&%('+?48;.3/.1?42G-/'"8;? 6U:,3;.U? 2g53<,.1'"-;'"23.U2CO.U<,'"2CO 'B5 2,Z [ 6U'"8]{&5 8«8F3/:C<,.U'"<tS>8.U0:C6U573;.U? 2C8"q n'I?4t,3/5 .12('<º´. πo1 clust+γ +γ decay breem πo1 clust γ decay γ. 3. B. . $&%('-/'"8;+=?42C8;'@? Ag5 f J +(-/?73/?73F>S+'@{&5 80'"57Z 8 :(-/'"<n53aK¸·¸¯ .U2s3;'"83Zkt'"570 ' *,+'-/.10'238j572C<n.13 {i548lAX? :(2=<3;%C573«3/%('G'"2('-/[ >E-;'8?461:(3;.U? 2}.M8«[4.1R4'2}tS> ´. 10-8. BH. 8X. 0G C}!#(CS"!#"l0H("!#%$}!#&!('*),+. 9! ,!#. °ª23;%C.U8G572C<2('*S3I8'O 3;.U? 2=8´(+C-;?40a+(3I+(%(? 3;? 2.M<,'2(Z 3;.1y=O573;.U? 2E5 2C<a8:(+C+(-;'8;8;.U? 2)? AO ?423/570.U2C53/.1?42E<,:C'¸3/?. . ³. 3. a⊕b=. √ a2 + b 2.

(24) \. . . . . dN/dpT (counts c/GeV). %C5 -/< 5 -;'_<,.M8/O :C8/8'<ºq $&%('I.U<,'"23;.1yC'"<+(-/? 0+,3]+C%(?7Z π0 3;?42}8+'"O 3;-/:(0 ' *,+'"O 3;'"<E3/?jt='\0'"548:C-;'<E<,:C-;.U2([L? 2(' -/:(2(2(.U2([)+'-/.1?,<}.M8¸+(-;'8'"23;'"<q $9{i?}<,.'-/'23\+(-/?,O '"<(:(-;'8i3;?}8;'6U'"O 3_+C-;?40a+(3&+C%(?7Z 3;?42C8T{i'-/'v57+(+C61.U'"< 3;%(' S%(?{i'- S%C5 +='©_2C5 61>,8;.U8 b ,© h ´S5 2C<3/%('I°F8;? 6M53/.1?42K¸:(3 N'3;%(?,< b °;K h qS$&%(' AX? -/0'-j.M<,'23/.yC'8L+(%(? 3;? 2=8Lt>¨572C5 61>Sw.U2([3;%C'8%C5 +=' ?7A\3/%('@8;%(?{i'-).U2 f J ´B572C<T3;%('@6U5733;'"-357[8572=< .M<,'23;.1yC'895&+(%(? 3;?42)5 8º+(-/? 0+,3.A,.1357+(+'"5 -/8.U8;? 6M53/'"<º´ .dq,' qU´{\.13;%C? :,3_O%C5 -;[4'"<}+C5 -3/.UO61'8«.U2.38&R.MO .U2(.13F> q,$&%(' °;K x0' 3/%(?,<}.M8¸<,'8;O-;.Ut'"<.U2 S'"O 3;.U? 2@³(q. ". . ". . CqUo q/ 1 /µ/O . 102. 10. . 20. dN/dpT (counts c/GeV). . VQ.13;%W3;%(.M8}0' 3/%(?,<W+(%(?73/?. 2C8}5 -;'.M<,'23/.yC'<W{\.3/%± `S.12=<s?7A&+(:(-/.3/.1'8´%C.1[4%´0'"<,.U:(0 572C<n6U?{j´9<,'"+='"2C<SZ .U2([? 2s3/%('§-/'FDF'O 3/.1?42V^4:=576U.3F>n?7A&3;%C'§%('5R>Zk.1?42s'2,Z RS.1-/? 2C0a'"23"q]©I8'*(570+(6U' ´B{i'8;%(?{ 3/%('N-/'"8;:(638aAX? 0'"<,.U:(0 +(:C-;.13F>Zd+(%C?73;?42C8 3;%('G+(-/? 0+,3Zk+(%(? 3;?42}.U<,'"2,Z 3;.1y=O"53;.U? 2r' O .U'2CO>s{i54857t? :(3 4³&|AX? -µ µvO ? 6U6U.Z 8;.1?42C8}572C<W57t? :(3 ³& AX? - f t(Z f tQO? 6U61.M8.U? 2=8qB$&%(' {\-/? 2([\.M<,'23/.y=O"53/.1?42g+C-;?4tC57t(.U6U.3F>4´ .¿q"' qU´ 3/%('«+(-/? t=57t(.U6Z .13F>}?7A9.M<,'23/.AX>S.U2([a5tC5 O`S[4-;?4:(2C<'R4'23\5 8i5+(-/? 0+,3 +(%(? 3;?42´S-/5 2([ '<aAX-;?40 3;? 4 .12§3;%('LO548'G?7A9?42(' Z 572C<V0a'<,.U:(0 +(:(-/.3F>s.M<,'23/.y=O"53/.1?42572=< O 6U:C83;'"π0 AX-/? 0 ³\3/?o³ .U2)3;%C'iO"5 8;'«?7A(%=5 <,-/? 2C8"q$&%('«-/'0}57.U2,Z .U2([ tC5 O`S[4-;?4:(2C<LAX-/? 0uDF' 3ZUDF' 3]'"R '"2438l{i548B8F3/.16U6,3/?? π0 %(.U[ % b .U[Cq h q (:C-3/%('-B.U0+(-;?R4'0'23l?7AtC5 O`S[ -/? :C2C< 8;:(+(+(-/'"8/8.U? 2t>j.U2CO-;'5 8;.12([_3;%('&+(%(? 3;?42)+(:(-/.3F>j.M8l8F3/.16U6 +?48/8.Ut(6U'jt(:,3g573\3;%('aO ?8F3_? Al:C2C5 O"O '+(3/57tC61'j6U?{+C%(?7Z 3;?42.M<,'23/.y=O"53/.1?42' O.1'"2CO >4q$&%S:C8"´5 <(<,.13;.U? 2=576.U<,'"2,Z 3;.1y=O"53;.U? 2§+(-;?,O'"<,:(-/'"8«%C5 <}3;?at='g<,'R4'6U? +'"<3/?E?R4'-;Z O ?40'\3;%('g6U.10.13/53/.1?42C8]? Aº3;%(' ,©0' 3;%C?S<q. \. 60. 103. 80 100 p T (GeV/c). PbPb collisions jet-jet γ -jet. 102. 10. 1 20. 40. 60. 80 100 p T (GeV/c). ~ä å<û ìn<ûé <èpç yé!è6òlòä )fè è 'Jètéí2òlî è <ä~ø<í ¡ä úPòUø<æêläîlòæ<ë!ó1ç¨ú<æPèpêónòUîlóæféìnúîUúè2èpìnñpéfòlêlìnìÛð ëä~îUé ä~îlè6ä~é|òyç lè6 ò òlìnø<æ<é úè9è ¡ìnéäúòUÞètæÛñ6ôòlòlèæ<&Pè/ç ôPñpð~ø<& óí2êlêyPä~èpé<ó1îUó¡úîlóé ä éòrë|<ñpä~óä~é<é;ð~åð~ä~ìîlîlä~òUóîlìé<òUòUìnîHä~éîyìòUfòHä~ñtìnýPìnê ðcû ýèp cêyêlã !cóêyè î 0û êyóø<&Pé<òUé<ìnä~ä~é<é<å è ëèt$ìnóêê . (•) ¤ 7¦ γ ª F . Q. . F. F. _. (◦) 7¦. ¤. . . #. . M

(25). . F. 6U5 -j3;%('@? 2('§[ '2C'-53;'<nt>¨3;%C'%('"5RS>Zk.1?42sO? 6U61.M8;.1?42´ 05>E+='"-3/:(-/t3;%(.M8].M<,'"5 6(3/? +? 6U? [ >4q7$9??R '-O ?40'¸3/%(.M8 <,. O:(63F>4´S{¸'L<,'R4'6U? +'"<3F{¸?a<,.'-/'23&.U8;? 6M53/.1?42@O:,3 0a'3;%(?,<(8"q,~i?73;%@0' 3;%C?S<C8\8'57-O%}AX? -&%C54<,-;?42C8¸.12C8;.M<,' h ?7A 5O ?42('§O '"23;'-/'"<T5 -;?4:(2C<¨3;%C'@<,.U-;'O 3/.1?42 b η ® , h φ.M0<,'2,Z e 'ª¬L0 %(.1[4%,Z +C%(?73/? 2O"572C<,.M<(573;'"8 b p p > 20 3;.1yC'"<tST>}3;%C' ,© 0' 3/%(?,<ºqC$&%(T'jO ?42('L.U8\<(' yC2('<t> 3;%('G-/54<,.1:=8 .12}3/%(' b ´ h 8+C54O '4´. . /. *C D PG H,"!¿=E9. 40. S. . . Q. pp collisions jet-jet γ -jet. 1. f %(?73/? 2Y8;+'"O 3/-/5?7A Z1DF'3g572=<DF' 3;Z1DF'3G'R4'23/8I{¸'"-;' γ .M<,'23;.1yC'<tC548'<)0}57.U2(6U>j? 2E3;%('&8;%C57+'&?7A(3/%('\8%(?{i'<,'"R '6U? +C+='<.U2W3;%('Ö576U? -/.U0a'3;'"-572C<W:C8;.12C[ f -;.U2CO .1Z +C5 6LK¸? 0+? 2('"23§©_2C5 61>,8;.U8§0a'3;%(?,< b ¯\' AFqgm1o±(´7o 7p h q. . 103. C ". /. $&%('0}57.U2N.M<,'"5}t'%C.12C<N3;%('E°;K .U8_3;%C573G+(-/? 0+,3 +(%(? 3;?42C8B572C<+C57-;3;?42C8+(-/?S<(:CO '<.U2E+=57-;3;? 2O ?4616U.M8.U? 2C8 57-/'j'0.133/'"<.U2?4+(+=?8.13;'E<,.1-/'"O 3;.U? 2C8"qC©G8_3/%('-/').M8I2(? %C54<,-;?42AX-;?40 3;%C')+C57-;3;?42aDF' 3C>S.U2([}.U23;%('8/570')<,.1Z -/'"O 3/.1?42)5 83;%(']+C%(?73/? 2´"3;%('¸6U5733/'-8;%(?4:(6U<j5 +(+'"57-9.U8;?7Z 6M53;'<ºqJ_?{i'R4'-´(3/%(':(2C<,'"-;6U>S.12(['R4'23"´.U2¨+=57-;3;.MO :,Z. R. R=. φη. p. (φ0 − φ)2 + (η0 − η)2 .. b. . . $&%('@0E:(613;.U+(61.MO .13F>T.U2C8.M<,'@3;%('O ?42('<,'+'2C<C8E?42V3/%(' O ? 2C'¸8;.1w"'¸572=<)? 2)3;%('i'R4'2393F>S+' q (?4- Z1DF'3'"R '"24389.U2 γ µ µO? 6U61.M8;.1?42C8´73;%('"-;'\.M8«5 610?483]2(?)+=57-;3;.MO 6U'\.12C8;.M<,'_3/%('. OQ. h.

(26) !9ì%&Pð~è« 4 ä~éòlètåêlìòlè;è

(27) 2ñpä~èpé<ñ6ë$óê¡ìnéôP&ç ôP&ñpóð~ð~ä~îlä~óé<î û. O ?42(' ´º.U2C<,'"+='"2C<,'"243/61>n?7A¸3;%('}'"2('-/[ >Y?7Ai3;%('}+(-/? 0+,3 +(%(? 3;?42´ºt(:,3LAX? -&DF'3ZUDF' 3j'R4'23/8g3/%('-/'a.U8j5O 6U'"5 -j<,' Z +'2C<,'"2CO '§?7Ai3;%('0E:(613;.U+(61.MO .13F>n{\.3/%s3;%('LDF'3'2('"-;[4> q $&%S:C8"´l5 +(+(6U>S.12([ O :(3/8E3;?¨3;%('+C5 -3/.UO61'8.U2C8;.U<('5 p O ?42('57-/? :C2C<¨5+(%CT?73;?42TO572=<,.U<C53;'}%C'6U+C8j:C8L3/?<,.M8FZ 3;.U2([4:(.U8;%}t' 3F{i''2 ZUDF' 3¸5 2C<gDF' 3;Z1DF'3¸'R4'23/8"q4$&%C'\3F{¸? γ <,.1'"-;'"23°;K 8l<,'"O.U<('i.1A5I+(%(? 3;? 2aO5 2C<,.M<(53/'¸.M8.U8;?7Z 6M53;'<572C<8;%(? :(6M<Et='\357[4[ '"<a5 8B5L+C-;?40a+(3l+C%(?73/? 2}5 8 AX? 6U6U?{_8 b . h I?}%C5 <,-/? 2{\.13;% 57t?R 'j5a[ .UR '23/%(-;'8%C? 6M< p .M8AX? :C2C<.123/%('YO? T2('4q ¨'Ö576U6\3/%(.U8§0' 3;%C?S< 83/5 2C<(57-<°;K Tq b .U. h $&%('L8;:(0 ?7A93;%('g3;-572=8R4'-8'G0a?40'23;:(0 ? A5 616 %C54<,-/? 2C8.U2C8.M<,'¨3;%('VO? 2('n.M8N80}576U6U'-3;%C5 2P5 [4.1R4'23;%C-;'8%(?46U<q n'O5 61693;%(.M8I0'3;%(?,<N°;K b °;K x{\.3/%}3;%C-;'8%(?46U<? 23;%C' S:(0 h q. . è è ;ñpóð~ð~ä~îUä~óé<î ç lè6òè 'ètéòlî. Pû /ç Pû lè6òyç lè6òè 'ètéòlî Pû ü. ü. Pû ü. Pû 2ç Pû . ô &Pç ô &ñpóð~ð~ä~îUä~óé<î ç lè6òè 'ètéòlî Pû .

(28) . Pû ü ý ý. Pû 2ç Pû 2ç .

(29) 2ç . lè6òyç lè6òè 'ètéòlî Pû tý. . Pû ü þ. þ. Pû 2ç Pû ç

(30) 2ç . . V. V. ". O O 11 U¶ . @. ³,qUo q. ¶ . Eµ . ". ". . . \. . . . 4. . 0X. . . . . . . . .

(31) ý . ý. ý çhý

(32) . . . .

(33) àç þ. . . . . . \. ". . . ". JQ. !h æ<èàð~ó 1ú<ø<êyä òë!çú<æ<ónòlóéJä<èpéòUä )<ñ ìòl ä~óéJè

(34) 2ñpä~èpé<ñ6ëä~îì%&óøPò $ óêrÛñpóð~ð~ä~îUä~óéPî+ìnéÞì%& óøPò $ óê+ôP& ç ôP2& ñpóð~ð~ä~îUä~óéPî û. ý

(35) . 3/%('.U8;? 6M53/.1?42Y' O.1'"2CO >{\.13;%¨3;%C'a+C%(?73/? 2n'2('"-;[4> {&5 8B?4tC8;'-/R '"<q ²nDF'3ZUDF' 39'"R '238 $&%(']°;K [ .UR '85\8;05 616U'-9+(-;?4tC57tC.161Z .13F>@? A]0.U8;.U<('23;.1AX>S.12([@5? 2C' ZªO 6U:C8F3/'5 8G5}+(%(? Z π0 3/? 2Y.U2 f t,Z f tY3/%C572¨.12Yµ µO? 6U61.M8;.1?42C8q$&%('a{\-;?42([ .M<,'23/.y=O"53/.1?42N+(-;?4tC57tC.16U.3F>.U2CO -/'"548'8_{\.13;%N3/%(' p 3/%(-;'8%C? 6M<N572C<N.M8I^:C548..U2C<,'+'2=<,'23G? AB3;%('aO ?42(T' 8;.1w"'IAX?4-\6U5 -;[4' 3;%(-/'"8;%(? 6M<(8"q($&%('j<,'+'2=<,'2CO'j?7A p 3/.yO53/.1?42E+C-;?4tC57t(.U6U.3F>j{\.13;%E3;%(' 3/%('&{\-;?42([G.M<,'"24T p 3/%(-;'8%C? 6M<).M8B8F3/-;?42([C´-/5 2([ .U2([GAX-;?40 57t? :,3«³ Z T e 'ª¬j AX?4- th ® )3;?§5 t=?4:,3Eo³ZF7, AX? p =6 pth = T ³77 e 'ªT ¬L ® @AX?4-)µ4µO ?4616U.U8;.U? 2C8a572C<VAX-;?40 57t? :,3 Z 2 e 'ª¬L 4 |AX? ® 3;?n57t? :,3o Zo³%|AX? th pT = 6 f e 'ª¬j ® \AX? - t,Z f t@O ?4616U.M8.U? 2C8"q pth = 2 T $&%('g-53;.U?? A3;%C' ZUDF' 3\8.U[ 2C5 6C3/?3/%('iDF' 3;Z1DF'3&t=5 O`Z γ [ -/? :(2C<.U8L-/'+? -;3;'<N.12s$57t(6U'³§5 2C< .U[48"q 5 2C< Cq °ª2}3;%('LO548'G?7A O ?4616U.U8;.U? 2C8"´ 3/%(.M8¸-53/.1?-;.M8'8¸8;6U.1[4%43/61> pp e {\.3/% AX? - th 'ª¬L ® ]t(:(39AX? - f t,Z f taO ? 6U6U.U8;.1?42C8"´ R pT = 2 3;%(.M8«-53/.1?a8%C?{_8«5)0}57*S.U0:C0 573 ´5 63/%(? :([4% R = 0.3 53i3;%(.M8&R576U:('I3/%('L°;K ' O .U'2CO>}.U8\5 610?483i3;%('L%C5 6A 3;%C5 2a573B¯ g(q\{\.13;%? 2(6U>)5g0?S<('-53;'i.U0a+C-;?R4'0'23 ?7Al3;%('a8.U[ 2=5763/?§tC54O`S[ -/? :(2C<@-53;.U?Cq (?4-_3;%C'6M57-/[ '"83 e 'ª¬j 3;%(-/'"8;%(? 6M<(8 b th 572C< ® h ´3;%C'8;.U[ 2C5 6 pT p =4 3;?§t=5 O`S[ -/? :(2=<@-5T3/[email protected];05 616U'-I3;%C5 2AX?4-I3/%('E6U?{i'-. . \. . . . Q. B. ý

(36) . . . ". . . . . . ý

(37) . . c. . . "V. . . . pT. - O ? 2C')8.Uw'8\.12 G 3;%C'a-572C[ ' 572=<Y+C5 -3/.UO61'E3;%C-;'8%(?46U<C8 0.1 < R < 0.8 e 'ª¬L® q n'¨5 +(+(6U.1'<Q3/%('Y°;K ´ 5 2C< p0th = 2 c 'R '"23/8ayC613;'"-;'<r3/%(-/? :([4% T' 3/%(?,<W3;?T-/'"O ?42C83;-/:CO 3/'"< 3;%C'$ f K 572C< f J r5 O"O '+(3/572=O '"8a572=<V-/'"8;+=?42C8'8q $&%('G°;K ' O .U'2CO>{i548]<,' y=2('"<548B3/%('I-53/.1?j? Aº3;%(' 2S:(0t'-B? A=.M8?46U573;'<6U?{r+(:C-;.13F>Zd+(%C?73;?42C83;?g3;%C'&3;?73576 2S:(0t'-G?7AB6U?{+(:C-;.13F>Zd+(%C?73;?42C8 4 q$&%('<,'"+='"2C<,'"2CO ' ?7A3;%C']°;K ' O .U'2CO>I{\.13;%L3/%(']'2C'-/[ >_? A43/%(']+(%(? 3;?42 O5 2C<,.M<(53/'iAX? -DF' 3;Z1DF'3]'R4'23/8l.M8]8;%(?{\2.U2 .U[48"q ³L572=< }AX?4572C<Y(q,Ć-/'"8;+'"O 3/.1R4'6U> ´572C< ´ R= 0.1 pth =2 T ? AB e 'ª¬j §5 2C< ® q$&%('E-/573;.U?48\? AB3;%('E.123/'[ -576M8\ 3;%(' .M8?46U573;'"<n6U?{ +(:(-/.3F>Zk+(%(?73/? 2T8;+='O 3;-/:(0 572C<n3/%('3/?7Z 3/5 646U?{T+(:(-/.13F>4Zk+(%(? 3;?42)8+'"O 3;-/:(0ÁX?4-t?73/% ZUDF' 3B572=< γ DF' 3;Z1DF'3)'R4'23/8L572=<AX?4-L<(.'-/'23jR576U:('"8L? A«3;%C'O? 2(' 8;.1w"'I572C< ´5 -;'_-/'+? -;3;'<.12@$5 t(61' Cq pth $&%('I0}57T.U2}AX'53;:C-;'8BAX? :C2C<57-/'\3/%('_AX?4616U?{\.12C[ ² ZUDF' 39'"R '"2438 °ª2G3/%('«O"5 8;'B?7Aµ µ}O ? 6U6U.U8;.1?42C8"´3;%(']°;K γ ' O .U'2CO>E.M8«O61?8'_3;?o z.12C<('+'2C<,'"23;6U>a? A3;%(' O ? 2C'8;.Uw'}572C<n? A¸3/%(' 3;%C-;'8%(?46U<´t(:,3jAX?4- f t,Z p f tYO ?4616U.M8.U? 2C8i3/%('-/').M8I5 T2.U0+=?4-35723G<,'"+='"2C<,'"2CO ' ?7A«3/%('}' O.1'"2CO >?42 572C< 3;%('8;0}576U61'"-g3;%(' R pth O ? 2C'@8;.1w"'@572=<s3;%('@%(.U[ %('"-3/%(' T 3;%C-;'8%(?46U<T3;%(' p t='33;'"-B3;%C'\.U8;? 6M53/.1?42E' }O.1'"2CO >4q _T?j<,'"+='"2C<,'"2CO '\? A. . è . ¥ M

(38). c pth T = 6. γ . V¨'83;:=<,.1'<3;%('°;K" ' O .U'2CO>AX? ". ¥ M

(39). . . "J. . c pth T =4. . \. ". ¥ M

(40). γ . ". X. pth T =2. . " . . . Q. *. JS.

(41) R = 0.1. 1. Isolated γ / all γ. Isolated γ / all γ. R = 0.1 pT,thres = 6 GeV/c pT,thres = 4 GeV/c. 0.8. pT,thres = 2 GeV/c. 0.6. 1 pT,thres = 6 GeV/c. 0.4. 0.2. 0.2. 40. 60. pT,thres = 2 GeV/c. 0.6. 0.4. 0 20. pT,thres = 4 GeV/c. 0.8. 0 20. 80 100 p T (GeV/c). 40. 60. R = 0.2. 1. Isolated γ / all γ. Isolated γ / all γ. R = 0.2 pT,thres = 6 GeV/c pT,thres = 4 GeV/c. 0.8. pT,thres = 2 GeV/c. 0.6. 60. 0 20. 80 100 p T (GeV/c). pT. . R = 0.2 ¤ . 7¦. . . pT . . pT,thres = 2 GeV/c. 0.6. 0.2. 40. pT,thres = 4 GeV/c. 0.8. 0.2. . ¤ 7¦. pT,thres = 6 GeV/c. 0.4. <ú ø<êyä~å<óú í2ûhhýPìnúPéû¨òõ;úPæ<êlónóòUéPóå éPî <ìnèpî*é<$òUó1ø<ä ¡)<é<ñ éñ6ìòU¨òlä~óä~ñpóé|óéé<ó%è$r è

(42) 2îUòlä æ<pèñpèàpä~ètîBú<éPìnæPñpé ë0ónÛòUó%ó üPé $ ï 2ìn4#é $óê ä < èpéòUè ä )<èP òlæ<êyètîlæ<óð <(î $óêñpóð~ð~ä~îUä~óéPî û . 1. 0.4. 0 20. 80 100 p T (GeV/c). 40. 60. 80 100 p T (GeV/c). Pú ø<êlä~å<úóí2ûh PìnúPéû¨òõ;ú<æ<êyónóòlé<óå é<î <ìnèpî(é!<$òló ø<ä )fé<ñtéñ6ìòlhòlä~óä~ñpóé|óé é<ó%è$S è

(43) 2îUòlä æ<pèñpè/pä~èpîú<é<ìnæ<ñ6é ë0ónòló%ó üPé $ ï ìn4#é $óê ä < èpé!òlè ä )fèP òUæ<êyèpîUæ<óð PîPô &PçPô &ñpóð~ð~ä~îUä~óéPî û . . R¥ = 0.1 M

(44). . ¤ 7¦. pT. ³,q,q. N. . R = 0.2 ¤ . . pT. . . . ¦. . . . . pT . . F. R¥ = 0.1 M

(45). ¶ . 1 1¶ O R /. "J. e 'ª¬L® h 5 2C<}.13/8&<,'"+='"2C<,'2=O ' 3;%C-;'8%(?46U< b th pT = 2 {\.13;% .M8)2('"[ 6U.1[4.1t(6U' q$&%('§?4+,3;.U0:C0 R5 61:('8)? A\3;%(' °;K x+C5 -/5 0' 3;'"-/8"´4O? 2C8;.M<,'-/.12C[)t=? 3;%§8;.U[ 2C5 6C3/?tC54O`4Z [ -/? :C2C<}-53;.U?E5 2C<}' }O.1'"2CO >4´S{¸'"-;'IAX? :(2C<3;?at=' R= e 'ª¬j 572=< ® q th. $&%('°;K 0' 3;%C?S<Y8'3/8I5a3/%(-/'"8;%(? 6M< 3/?3/%(' Σ 8:(0 ?7A93/%('g3;-572C8;R '"-/8;'I0?40a'"23;:(0 ? A5 6163;p%CT'j+C57-;3;.1Z O 6U'"8BAX?4:(2C<}.U2§5j[4.1R4'2O? 2('I5 -;?4:(2C<E3;%C'I+(%(? 3;?42§O5 2,Z <,.U<C53;'4q n'&8F3/:C<,.U'"<j3/%('i' O .U'2CO>L?7A(3/%('«0' 3/%(?,<jAX?43;%(-/'"8;%(? 6M<¨R5 61:C'"8j? A&Cq ,´]o ´5 2C<s± e 'ª¬L ® AX? -Lµ4µ O ? 6U6U.U8;.1?42C8"´7572C<at' 3F{i''2³L5 2C<}³7 e 'ª¬L ® iAX? - f t,Z f t O ? 6U6U.U8;.1?42C8"q °k39'0'-/[ '<G3;%C573AX? - f t,Z f tO ?4616U.U8;.U? 2C8. V. pT. ". 0.2. . pT = 2. S. . . Σ pT.

(46) 14. R = 0.1 Signal γ / Bkg γ. Signal γ / Bkg γ. R = 0.1 pT,thres = 2 GeV/c pT,thres = 4 GeV/c. 12. pT,thres = 6 GeV/c. 10. 14. 6. 6. 4. 4. 2. 2 60. pT,thres = 6 GeV/c. 10 8. 40. pT,thres = 4 GeV/c. 12. 8. 0 20. pT,thres = 2 GeV/c. 0 20. 80 100 p (GeV/c). 40. 60. T. T. R = 0.2 Signal γ / Bkg γ. Signal γ / Bkg γ. R = 0.2 14. pT,thres = 2 GeV/c pT,thres = 4 GeV/c. 12. pT,thres = 6 GeV/c. 10. 6. 4. 4. 2. 2 60. ¤. 7¦. . ¤ . ª¦ pth T. γ . . k¦. 7. . pT¥. . M

(47). . R = 0.1 . . ¤ . ¤ 7¦. . V. b. . 80 100 p (GeV/c). ¤. ¦. . ¤ . ª¦ pth T. γ . ". F. ª¦. . pT¥. . M

(48). . R = 0.1 . . ¤ . ¤ 7¦. }. F. {\%('-/' .M8¸5jA#5 O 3/? -«3;%C573«3/5 ` '8].U243/?E54OO ?4:(23]3;%C' f (R) -;'8+? 2C8;'@AX:(2CO 3/.1?42W5 2C<W5 OO'+,3572CO'?7AI3/%('R57-/.1?4:C8 <,' 3/'"O 3/? -8i.12SR ?461R4'"<ºq .M8\'"^:C5 63;?? 2C'g{\%C'2N<,' Z f (R) 3;'"O 3;?4--/'"8;+=?42C8;'¸572=<E54OO '"+,3/5 2CO 'i57-/'«.U[ 2(?4-;'<ºq°ª2E?4:(O5 8;' ´"{¸'«3;?S? ` ´"<('"<,:CO'"<LAX-/? 0 f (R) = 0.95 − 1.5 × R y(33/.12([3;%('E0a'572NR576U:('8_?7Al3/%('j3;-572=8R4'-8'L0? 0'2(Z 3;:(0 8;:(0 AX? -¸<(' 3;'O 3/'"<}'"R '238]-/'+? -;3;'"<.U2@$57tC61' Cq $&%(.M8=0a'3;%(?,<\{&5 857+C+(61.U'"<\3;?«-/'"O? 2C83;-/:CO 3;'"<&'"R '"2438 3;?NO5 6UO:(6U573;'a3;%C'}°;K ¨' O .U'2CO>AX?4-L3;%('<,.1'-/'23 R5 61:C'"8]? Aº3;%('gO ?42('I8;.1w"'I-/'+? -;3;'"<.U2§$57t(6U' ,q. ". Σp = 2 T , R × f (R). 60. yêúPä êlä~òå<óëí2û ìn PúPé û:ò-ú<ä~ åæ<éfón4 ìnòlð ó$é<êlä îó<í èp&é!ë òlä )fç -yè èp- ò5 è ú<'ð~êló1èpóé!í2òlî úú<¨òø<òUêyú<ó ä æ<ò&<ë ónìnòlóñ[ìnùé<é åî êyó&! ø<ë+é 4-- 5 $ä êy<óð~èpóí é! òlä y)fú<èpè ò#ø ç yè6<òó è 'é èt6éïPòlìnî é AìnîAìB$ó%ø<$cé<üPñ6ï òlä~Aìóéné ó%$ ï<è $óPê ìné ôP&Pç ôøP&2ú ñpóìnð~ð~é ä~îUä~óPé<ûîtü û . . a. 40. T. .M8)2(? 3)3;%('@57+(+(-/? +C-;.M53/'a+=57-570' 3/'-L3;?Ö ? 0+C5 -;'-/' Z 8;:(638AX?4-<,.1'-/'23O? 2('i8.Uw'89<,:('«3;?G.3883;-/? 2([IR5 -;.M5Z 3;.U? 2{\.3/% Lq$5 t(61' _[4.1R4'"83/%('¸0'5725 2C<L-;?S? 30'"5 2 8/^4:=57-/'§R576U:('"8a? AI3;%C'+=57-;3;.MO 6U'<,.M83;-/.1t(:(3;.U? 2C8a.U2C8.M<,' <,.1'"-;'"23\O? 2('j8;.1w"'"8"q ¨'gAX? :C2C<@3;%C573\5a0? -/'L57+(+(-/?7Z ? 2G3;%C'B0a?40'2,Z +(-/.U573;'l+C5 -/5 0a'3;'"-.M8º5¸3;%(-/'"8;%(?46U< Σ0pT 3;:C0 8;:(0 <,'"2C8.13F>}<,' y=2('"<548. Σ0pT. pT,thres = 6 GeV/c. 0 20. 80 100 p (GeV/c). yêú<ä êyä~òå<óëí2ûNìnþúPé û ò-!ú<ä~ åæ<éfón4 ìnòlð ó$é<êyä îó<í èp&éëTòUä )<ç -yè è6- ;ò¡5 è8ú<'ð~êyó1èpóéí2òUî úPúPhòø<òlêlú<óä æPò&fë0ónìnòUóñ[ìnù!é<é åî.êl&ó øPë é 4-- 5 $ä êl<óð~èpó1í é òUä y)<ú<è6è øPò ç yèp<ò/ó1¡è 'é èp[é!ïòlìnî éìnîAì7$ó%øP$Hé<üPñ6òUï ä~Þìóéné ó%$ ï:è $óê PAìné Û;ñpø<óú ð~ð~ä~îUìnä~óé é<îtû Pû ü . pT,thres = 4 GeV/c. 10. 6. 40. pT,thres = 2 GeV/c. 12. 8. T. . 14. 8. 0 20. 80 100 p (GeV/c). B. "J . h. . .

(49) !9ì%&<ð~è/ý. !9ì%&Pð~èàþ éòlètåêlìòlè 4E-è

(50) 2ñpä~ètéPñpë$óêcêlèpñpóé<îlòlêyø<ñ6òUèF2Þìnéô&Pç ô& è ' èpéòUîä~éôHãö.- ìné+!¡ô û. êlîUéìä~óòUòUéPä~èpó/åî ûêló ì&PòUòUè ìnìnä~é é<îlè ä~å7éf&ìnëð ìnòlêlæ<èç è yòlè6æ<ò èr4 òlñpóàóé<í2ä~éèèpòlòlîlètæ<ä åtèóêlBìòlìnè$é ó7ÛêS&f!ú<ìnÛìnñ[êyù!ìnòlåä~é ñpêlð~óèøPôPí2é &óç ôPí2l&2èpè6é!òyñpç òlóyø<èpð~ð~íò ä ç òlæ<êlèpîlæ<óð Nû è è è ñpóð~ð~ä~îlä~óé<î Pû û Pû ü Pû ý û Pû àç Pû Pû ç Pû þ û Pô &ç Pô &ñpóð~ð~ä~îlä~óé<î Pû û Pû ü <û ü û Pû àç Pû <û àç û ý !9%ì &<ð~ è úf47ì ìn$ètê ø<ìnòUé<ä~éBñpñ6ð~'nòlè ä~ìnó<ð~éø<ä~îlèòl%ó êyìn$hä é &<òU7øPæ<òlèÞ6¡ä~óñpó!é<óónîBé<ò*èÞ%ó 4$rîUòUètä pèæPìnéè$òl-óêl÷!ê/ìnøfé<ìnìn î ð~'êyðSè èpòlêyæ<îU62èÞèà4Eåí2èt- óéP+í2ètêló%èpì$éòlòlòUè æ<øPÚèí)úfã ìnîU øPê òlí%ä~ñtÿ ð~ìnèpîî ìné |óé<ð ëB$óê <è6òlèpñpòlè ú<ìnêyòlä~ñpð~ètîtû . ¤ ª¦ γ . F. F R pth T . . . pth T = 2. ¥ M

(51). . . . c pth T = 4. ¤ . ¥ M

(52). c pth T =6. . . . . . . . . . . . . . . . . . . . . ¤. . «. ¥. . ¦. ¤¥ M