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Bc meson hadropro duction in kT -factorization approach
V.A. Saleev and D.V. Vasin Samara State University, Russia Plan 1. Intro duction 2. The kT -factorization approach 3. The Bc-meson pro duction in the fusion mo del with charm excitation in a proton 4. The Bc-meson pro duction in the fragmentation approach 5. Results and conclusions


Email: saleev@ssu.samara.ru Email: vasin@ssu.samara.ru


Intro duction Nowadays the exp erimental search for Bc mesons is carried out at the CERN e+e- collider LEP [1] and at the Fermilab Tevatron pp collider [2]. п The hadronic pro duction of the Bc and Bc mesons have b een calculated in the parton mo del using different approaches: 1. Fragmentation mo del [3,4,5,6] 2. Fusion mo del [3,4,7] 3. Charm excitation [7] mBc = mb + mc. mb = 5.1 GeV, mc = 1.5 GeV. fBc = 560 MeV. ------------------------------------н [1] K. Ackerstaff et al. (OPAL Coll.), CERN-PRE-97-137 (1997).
[2] F. Ab e et al. (CDF Coll.), FERMILAB-Conf-95/202-E (1995). [3] S.S. Gershtein, V.V. Kiselev, A.K. Likho ded, A.V. Tkabladze, A.V. Berezhnoy and A.I. Onishchenko, IHEP-98-22 (1998). [4] K. Kolo dziej, R. Rи uckl, Nucl.Instrum.Meth. A408 (1998) 33. [5] K. Cheung and T.C. Yuan, Phys.Rev. D53 (1996) 1232. [6] C.-H. Chang, Y.-Q. Chen and R.J. Oakes, Phys.Rev. D54 (1996) 4344. [7] S.P. Baranov, Phys.Rev. D56 (1997) 3046.


The kT -factorization approach In the parton mo del: PM(pp bп , s) = п bX Ѕ dx1G(x1, І2) Ѕ (1)

dx2G(x2, І2) (g g bп ^), ^ b, s pg,i = xipp,i, ^ = x1x2s. s

In the kT -factorization approach [7,8]: KT(pp bп , s) = п bX dx1 d1 2 2 = dk1T (x1, k1T , І2) Ѕ x1 2 dx2 d2 2 2 Ѕ dk2T (x2, k2T , І2) Ѕ x2 2 2 Ѕ (g g bп k1T , 1, k2T , 2, ^) ^ b, 2 s (2)
2 2 pg,i = xipp,i + ki,T , ^ = x1x2s - k1T - k2T , s ki,T = (0, ki,T , 0). ------------------------------------н 100 (1983) 1. [8] E. Kuraev, L. Lipatov, and V. Fadin, Sov.Phys.JETP 44 (1976) 443; Y. Balitskii and L. Lipatov, Sov.J.Nucl.Phys. 28 (1978) 822.

[7] L.V. Grib ov, E.M. Levin and M.G. Ryskin, Phys.Rep.


The Bc-meson pro duction In the kinematic region under consideration: mc mBc and mc pT , and we use two approaches for Bc-meson pro duction: 1. The Bc-meson pro duction in the fusion mo del with charm excitation in a proton
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2. The Bc-meson pro duction in the fragmentation approach
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The Bc-meson pro duction in the fusion mo del with charm excitation in a proton
1x10
0

p + p B* + X c s = 1 . 8 T e V |y | < 1 . 5

d ( p p B c X ) / d p T , n b / G e V

1x10

-1

JB

*

1x10

-2

JS GRV

1x10

-3

KMR

1x10

-4

10

15

20

25

30

35

40

45

50

pT, G eV


The Bc-meson pro duction in the fragmentation approach
1x10
0

p + p B* + X c s = 1 . 8 T e V |y | < 1 . 5

d ( p p B c X ) / d p T , n b / G e V
*

1x10

-1

1x10

-2

JB JS
-3

1x10

GRV

KMR
1x10
-4

10

15

20

25

30

35

40

45

50

pT, G eV


Comparison with previous calculations in parton mo del
1x10
0

- K . C h e u n g a n d T .C . Y u a n [ 5 ] - A .K . L ik h o d e d e t a l.[ 3 ] ( g g B c b )

d ( p p B c X ) / d p T , n b / G e V

1x10

-1

F ra g m e n ta tio n (o u r re s u lts ) F u s io n (o u r re s u lts ) p + p B* + X c s = 1 . 8 T e V |y | < 1

*

1x10

-2

1x10

-3

1x10

-4

10

15

20

25

30

35

40

45

50

pT, G eV
[3] S.S. Gershtein, V.V. Kiselev, A.K. Likho ded, A.V. Tkabladze, A.V. Berezhnoy and A.I. Onishchenko, IHEP-98-22 (1998). [5] K. Cheung and T.C. Yuan, Phys.Rev. D53 (1996) 1232.


Comparison two approaches: fragmentation and fusion
1x10
0

p + p B* + X c s = 1 . 8 T e V |y | < 1 . 5

d ( p p B c X ) / d p T , n b / G e V

1x10

-1

F ra g m e n ta tio n F u s io n
-2

*

1x10

JS

JS GRV
-3

1x10

GRV
1x10
-4

10

15

20

25

30

35

40

45

50

pT, G eV


Comparison Bc and Bc meson pro duction with previous calculations in parton mo del and Tevatron data
1x10
0

- E . B ra a te n a n d A .K . L ik h o d e d [ 9 ] P a rto n m o d e l k T -fa c to riz a tio n a p p ro a c h
1x10
-1

d / d p T , n b / G e V

1x10

-2

JB GRV

JS

s = 2 T e V |y | < 1 R 0 = 1 .1 8 G e V s = 0 . 2 3 m c= 1 .5 G e V m b = 4 .8 G e V

3 /2

1x10

-3

KM R
1x10
-4

10

15

20

25

30

35

40

45

50

pT, G eV

Bc meson cross section (pT > 6 GeV, |y | < 1): P M = 2.5 nb [9] exp 10 ‘ 6 nb [10] K T 6 nb (JB, KMR) K T 10 nb (JS) ------------------------------------н [9] K. Anikeev at al., FERMILAB-Pub-01/197 (2001) 480.
[10] F. Ab e at al., CDF Coll., Phys.Rev.Lett. 81 (1998) 2432; F. Ab e at al., CDF Coll., Phys.Rev. D58 (1998) 112004.