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On Certain Subclasses of Analytic Functions Involving Carlson-Shaffer Operator and Related to Lemniscate of Bernoulli

DOI: 10.1155/2014/295703

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Abstract:

The object of the present investigation is to solve the Fekete-Szeg? problem and determine the sharp upper bound to the second Hankel determinant for a new class of analytic functions involving the Carlson-Shaffer operator in the unit disk. We also obtain a sufficient condition for normalized analytic functions in the unit disk to be in this class. 1. Introduction and Preliminaries Let be the class of functions of the form which are analytic in the open unit disk . A function is said to be starlike of order , if Similarly, a function is said to be convex of order , if By usual notations, we write these classes of functions by and , respectively. We denote and , the familiar subclasses of starlike, convex functions in . Furthermore, let denote the class of analytic functions normalized by such that in . For functions and , analytic in , we say that is subordinate to , written as or , if there exists a Schwarz function , which (by definition) is analytic in with , , and , . Furthermore, if the function is univalent in , then we have the following equivalence relation (cf., e.g., [1]; see also [2]): For functions analytic in , we define the Hadamard product (or convolution) of and by Note that is also analytic in . Carlson and Shaffer [3] defined the linear operator in terms of the incomplete beta function by where and denotes the Pochhammer symbol (or shifted factorial) given, in terms of the Gamma function , by If is given by (1), then it follows from (7) that We note that for (i);(ii);(iii);(iv), the well-known Ruscheweyh derivative [4] of ;(v), the well-known Owa-Srivastava fractional differential operator [5]. We also observe that and . With the aid of the linear operator , we introduce a subclass of as follows. Definition 1. A function is said to be in the class , if it satisfies the condition It follows from (12) and the definition of subordination that a function satisfies the following subordination relation: We further note that if , then the function lies in the region bounded by the right half of the lemniscate of Bernoulli given by Noonan and Thomas [6] defined the th Hankel determinant of a sequence of real or complex numbers by This determinant has been studied by several authors including Noor [7] with the subject of inquiry ranging from the rate of growth of (as ) to the determination of precise bounds with specific values of and for certain subclasses of analytic functions in the unit disc . For , , , and , the Hankel determinant simplifies to The Hankel determinant was considered by Fekete and Szeg? [8] and we refer to as the second

References

[1]  S. S. Miller and P. T. Mocanu, “Differential subordinations and univalent functions,” The Michigan Mathematical Journal, vol. 28, no. 2, pp. 157–172, 1981.
[2]  S. S. Miller and P. T. Mocanu, Differential Subordinations: Theory and Applications, vol. 225 of Monographs and Textbooks in Pure and Applied Mathematics, Marcel Dekker, New York, NY, USA, 2000.
[3]  B. C. Carlson and D. B. Shaffer, “Starlike and prestarlike hypergeometric functions,” SIAM Journal on Mathematical Analysis, vol. 15, no. 4, pp. 737–745, 1984.
[4]  S. Ruscheweyh, “New criteria for univalent functions,” Proceedings of the American Mathematical Society, vol. 49, pp. 109–115, 1975.
[5]  S. Owa and H. M. Srivastava, “Univalent and starlike generalized hypergeometric functions,” Canadian Journal of Mathematics, vol. 39, no. 5, pp. 1057–1077, 1987.
[6]  J. W. Noonan and D. K. Thomas, “On the second Hankel determinant of areally mean -valent functions,” Transactions of the American Mathematical Society, vol. 223, pp. 337–346, 1976.
[7]  K. I. Noor, “Hankel determinant problem for the class of functions with bounded boundary rotation,” Revue Roumaine de Mathématique Pures et Appliquées, vol. 28, no. 8, pp. 731–739, 1983.
[8]  M. Fekete and G. Szeg?, “Eine bemerkung über ungerade schlichte funktionen,” Journal of the London Mathematical Society, vol. 8, pp. 85–89, 1933.
[9]  P. L. Duren, Univalent Functions, Grundlehren der Mathematischen Wissenschaften, Springer, New York, NY, USA, 1983.
[10]  F. R. Keogh and E. P. Merkes, “A coefficient inequality for certain classes of analytic functions,” Proceedings of the American Mathematical Society, vol. 20, pp. 8–12, 1969.
[11]  W. Koepf, “On the Fekete-Szeg? problem for close-to-convex functions II,” Archiv der Mathematik, vol. 49, no. 5, pp. 420–433, 1987.
[12]  W. Koepf, “On the Fekete-Szeg? problem for close-to-convex functions,” Proceedings of the American Mathematical Society, vol. 101, no. 1, pp. 89–95, 1987.
[13]  A. Janteng, S. A. Halim, and M. Darus, “Coefficient inequality for a function whose derivative has a positive real part,” Journal of Inequalities in Pure and Applied Mathematics, vol. 7, no. 2, article 50, 2006.
[14]  A. Janteng, S. A. Halim, and M. Darus, “Estimate on the second Hankel functional for functions whose derivative has a positive real part,” Journal of Quality Measurement and Analysis, vol. 4, pp. 189–195, 2008.
[15]  T. H. MacGregor, “Functions whose derivative has a positive real part,” Transactions of the American Mathematical Society, vol. 104, pp. 532–537, 1962.
[16]  R. J. Libera and E. J. Z?otkiewicz, “Early coefficients of the inverse of a regular convex function,” Proceedings of the American Mathematical Society, vol. 85, no. 2, pp. 225–230, 1982.
[17]  R. J. Libera and E. J. Z?otkiewicz, “Coefficient bounds for the inverse of a function with derivative in ,” Proceedings of the American Mathematical Society, vol. 87, no. 2, pp. 251–257, 1983.
[18]  W. C. Ma and D. Minda, “A unified treatment of some special classes of univalent functions,” in Proceedings of the Conference on Complex Analysis (Tianjin, 1992), Z. Li, F. Ren, L. Yang and, and S. Zhang, Eds., pp. 157–169, International Press, Cambridge, Mass, USA, 1994.
[19]  I. S. Jack, “Functions starlike and convex of order α,” Journal of the London Mathematical Society, vol. 3, pp. 469–474, 1971.

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