نتایج جستجو برای: free field

تعداد نتایج: 1262393  

2004
Scott Watson

In this talk I will discuss the role of finite temperature quantum corrections in string cosmology and show that they can lead to a stabilization mechanism for the volume moduli. I will show that from the higher dimensional perspective this results from the effect of states of enhanced symmetry on the one-loop free energy. These states lead not only to stabilization, but also suggest an alterna...

Abstract The spontaneous emission spectrum from a driven three-level atom placed inside a double-band photonic crystal has been investigated. We use the model which assumes the upper levels of the atomic transition are coupled via a classical driving field. The transition from one of the upper levels to lower level couples to the modes of the modified reservoir, and the transition from the oth...

Journal: :Progress of Theoretical Physics Supplement 2013

Journal: :IEEE Transactions on Plasma Science 1985

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه ولی عصر (عج) - رفسنجان - دانشکده ریاضی 1389

in this thesis, first the notion of weak mutual associativity (w.m.a.) and the necessary and sufficient condition for a $(l,gamma)$-associated hypersemigroup $(h, ast)$ derived from some family of $lesssim$-preordered semigroups to be a hypergroup, are given. second, by proving the fact that the concrete categories, semihypergroups and hypergroups have not free objects we will introduce t...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه علم و صنعت ایران - دانشکده فیزیک 1382

لیزر الکترون آزاد دستگاه تولید نورهمدوس با قابلیت بسیار است. عملا روی هر طول موج قابل تنظیم بوده و از بازده بسیار زیاد نیز برخوردار است که در آزمایشگاهها تا40 درصد و از نظر نظری تا 65 درصد قابل افزایش می باشد و بااین روند رشد همچنان ادامه دارد. نور این لیزرها در اثر برهم کنش سه عامل تولید می شود. باریکه الکترون، یک موج الکترومغناطیسی که در همان راستای حرکت الکترونها در کاواک لیزر حرکت می کند و ...

1995
Kenneth Dalton

We show that Einstein’s gravitational field has zero energy, momentum, and stress. This conclusion follows directly from the gravitational field equations, in conjunction with the differential law of energy-momentum conservation T ;ν = 0. Einstein rejected this conservation law despite the fact that it is generally covariant. We trace his rejection to a misapplication of Gauss’ divergence formu...

Journal: :Physical review letters 2001
M Machholm N E Henriksen

We consider impulsive excitation of a linear polar molecule by a plane polarized electromagnetic "half-cycle" pulse in the terahertz range. A rotational wave packet is created with angular momentum states of different parity. The time evolution of the wave packet corresponds to alternating molecular orientations with respect to the polarization axis of the field. This field-free time-dependent ...

2008
DANIEL E. LÓPEZ-FOGLIANI

Free field representations of vertex algebra in SL(2,R)k/U(1) × U(1) WZNW model are constructed by considering a twisted version of the Bershadsky-Kutasov free field description of discrete states in the two-dimensional black hole CFT. These correspond to conjugate representations describing primary states in the model on SL(2,R)/U(1)× U(1). A particular evaluation of these leads to identities ...

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