We study the thermodynamics and phase structure of asymptotically flat nondilatonic as well as dilatonic black branes in a cavity in arbitrary dimensions (D). We consider the canonical ensemble and so the charge inside the cavity and the temperature at the wall are fixed. We analyze the stability of the black brane equilibrium states and derive the phase structures. For the zero charge case we find an analog of Hawking-Page phase transition for these black branes in arbitrary dimensions. When the charge is non-zero, we find that below a critical value of the charge, the phase diagram has a line of first-order phase transition in a certain range of temperatures which ends up at a second order phase transition point (critical point) as the charge attains the critical value. We calculate the critical exponents at that critical point. Although our discussion is mainly concerned with the nondilatonic branes, we show how it easily carries over to the dilatonic branes as well.

Complete fusion excitation functions for 11,10 B+ 159 Tb have been measured at energies around the respective Coulomb barriers, and the existing complete fusion measurements for 7 Li+ 159 Tb have been extended to higher energies. The measurements show significant reduction of complete fusion cross sections at above-barrier energies for both the reactions, 10 B+ 159 Tb and 7 Li+ 159 Tb, when compared to those for 11 B+ 159 Tb. The comparison shows that the extent of suppression of complete fusion cross sections is correlated with the α-separation energies of the projectiles. Also, the two reactions, 10 B+ 159 Tb and 7 Li+ 159 Tb were found to produce incomplete fusion products at energies near the respective Coulomb barriers, with the α-particle emitting channel being the favoured incomplete fusion process in both the cases.PACS number(s): 24.10. Eq, 25.70.Jj, 25.70.Pj, 25.70.Mn, 27.70.+q

We give explicit constructions of static, non-supersymmetric p-brane (for p ≤ d − 4, where d is the space-time dimensionality and including p = −1 or D-instanton) solutions of type II supergravities in diverse dimensions. A subclass of these are the static counterpart of the time dependent solutions obtained in [hep-th/0309202]. Depending on the forms of the nonextremality function G(r) defined in the text, we discuss various possible solutions and their region of validity. We show how one class of these solutions interpolate between the p-brane-anti p-brane solutions and the usual BPS p-brane solutions in d = 10, while the other class, although have BPS limits, do not have such an interpretation. We point out how the time dependent solutions mentioned above can be obtained by a Wick rotation of one class of these static solutions. We also discuss another type of solutions which might seem non-supersymmetric, but we show by a coordinate transformation that they are nothing but the near horizon limits of the various BPS p-branes already known.

In the previous paper [hep-th/9904112], we argued that there exist BPS bound states of Dp branes carrying certain units of quantized constant electric field for every $p$ (with $1 \le p \le 8$). Each of these bound states preserves one half of the spacetime supersymmetries. In this paper, we construct these bound state configurations explicitly for $2 \le p \le 7$ from Schwarz's $(m,n)$-string or (F, D1) bound state in type IIB string theory by T-dualities along the transverse directions. We calculate the charge per $(2\pi)^{p -1} \alpha'^{(p - 1)/2}$ of $(p -1)$-dimensional area for F-strings in (F, Dp) and the tension for each of these bound states. The results agree precisely with those obtained previously from the worldvolume study. We study the decoupling limit for the (F, D3) bound state and find that Maldacena's $AdS_5/CFT_4$ correspondence may hold true even with respect to thisbound state but now with an effective string coupling rather than the usual string coupling. This coupling is quantized and can be independent of the usual string coupling in certain limit.Comment: 37 pages, Revtex, typos corrected and references adde

We point out that the solution of $(4+n)$-dimensional gravity coupled to the dilaton and an $n$-form field strength can give rise to a flat 4-dimensional universe (with a scale factor) of the type proposed recently under time dependent compactifications. The compact internal spaces could be hyperbolic, flat or spherical and the solution is identical to the space-like two brane or S2-brane. As has been shown previously for SM2 solution with a fixed field strength we show that for $n=7$ (where the dilaton is vanishing and with a general field strength), 6 the corresponding SM2 and SD2 solutions can give accelerating cosmologies in Einstein frame for both hyperbolic and flat internal spaces, thereby meeting the challenge of obtaining such a solution from M/String theory compactifications.Comment: 12 pages, latex, two figures, v4: minor clarifications and references added, version to appear in Physics Letters B,v5:some misleading phrases in the introduction have been correcte

It is well-known that the low energy string theory admits a non-singular solitonic super five-brane solution which is the magnetic dual to the fundamental string solution. By using the symmetry of the type IIB string theory, we construct an SL(2, Z) multiplet of magnetically charged super five-branes starting from this solitonic solution. These solutions are characterized by two integral three-form charges (q 1 , q 2 ) and are stable when the integers are coprime. We obtain an expression for the tension of these (q 1 , q 2 ) five-branes as envisaged by Witten. The SL(2, Z) multiplets of black strings and black fivebranes and the existence of similar magnetic dual solutions of strings in type II string theory in D < 10 have also been discussed. .in * Earlier attempt for the construction of SL(2, Z) multiplet of five-brane solution of type IIB string theory were made in [13,14], but the solutions described there are incomplete.

No abstract

An (m, n)-string bound state (with m, n relatively prime integers) in type IIB string theory can be interpreted from the D-string worldsheet point of view as n D-strings carrying m units of quantized electric flux or quantized electric field. We argue, from the D-brane worldvolume point of view, that similar Dp-brane bound states should also exist for 2 ≤ p ≤ 8 in both type IIA (when p is even) and type IIB (when p is odd) string theories. As in p = 1 case, these bound states can each be interpreted as n Dp-branes carrying m units of quantized constant electric field. In particular, they all preserve one half of the spacetime supersymmetries.