We put bounds on the variation of value fine structure constant $\ensuremath{\alpha}$, at time big bang nucleosynthesis. study carefully all light elements up to ${}^{7}$Li. correct a previous upper limit $|\ensuremath{\Delta}\ensuremath{\alpha}/\ensuremath{\alpha}|$ estimated from ${}^{4}\mathrm{He}$ primordial abundance and we find interesting new potential limits (depending baryon-to-photon ratio) ${}^{7}\mathrm{Li},$ whose production is governed large extent by Coulomb barriers. The...

A bstract We compute a large collection of string worldsheet correlators describing light probes interacting with heavy black hole microstates. The states consist NS5 branes carrying momentum and/or fundamental charge. In the fivebrane decoupling limit, theory on family such backgrounds is given by exactly solvable null-gauged WZW models. construct physical vertex operators in these cosets, including all massless fluctuations. class novel heavy-light-light-heavy AdS 3 where include those...

Light probes interacting with heavy bound states such as black holes give rise to observables containing valuable dynamical information. Recently, a family of hole microstates was shown admit an exact string worldsheet description. We construct the physical vertex operators these models, and compute extensive set novel heavy-light correlators. then obtain first match between correlators in holographically dual conformal field theory. conjecture closed formula for arbitrary number light...

A bstract Correlation functions of the SL(2,ℝ)-WZW model involving spectrally flowed vertex operators are notoriously difficult to compute. An explicit integral expression for corresponding three-point was recently conjectured in [1]. In this paper, we provide a proof conjecture. For this, extend methods [2] based on so-called SL(2,ℝ) series identifications, which relate belonging different spectral flow sectors. We also highlight role holomorphic covering maps context. Our results...

We review the Coulomb gas computation of three-point functions in $SL(2,\mathbb{R})$ Wess-Zumino-Novikov-Witten model and obtain explicit expressions for generic states. These amplitudes have been computed past by this other methods but analytic continuation number screening charges required formalism had only performed particular cases. After showing that ghost contributions to correlators can be generally expressed terms Schur polynomials, we solve Aomoto integrals complex plane, a new set...

We provide an explicit example of how the string winding modes can be incorporated in double field theory. Our guiding case is closed bosonic compactified on a circle radius close to self-dual point, where some with non-zero or discrete momentum number become massless and enhance $U(1) \times U(1)$ symmetry $SU(2) SU(2)$. compute three-point scattering amplitudes slightly massive states, extract corresponding effective low energy gauge The enhanced at point Higgs-like mechanism arising when...

We compute three-point functions for the $SL(2,\mathbb{R})$-WZNW model. After reviewing case of two-point correlator, we spectral flow preserving and nonpreserving correlation in space-time picture involving three vertex operators carrying an arbitrary amount flow. When only one or two insertions have nontrivial numbers, method employ allows us to find expressions without any constraint on spin values. Unlike these cases, same procedure restrains possible configurations when vertices belong...

We consider three-point correlation functions for superstrings propagating in AdS$_3\times S^3 \times T^4$. In the RNS formalism, these generically involve correlators with current insertions. When vertex operators non-trivial spectral flow charges are present, their complicated OPEs currents imply that standard methods can not be used to compute such correlators. Here we develop novel techniques computing all $m$-basis of supersymmetric model. then show how, some cases, results translated...

A bstract We compute all worldsheet three-point functions involving spectrally-flowed operators in chiral multiplets of the space-time theory for strings AdS 3 × S T 4 , thus completing analysis full /CFT 2 ring. make use techniques recently developed bosonic sector, based on holomorphic covering maps from to boundary. highlight role so-called series identifications when dealing with complications originated by picture-changing states. find an exact agreement predictions holographic CFT at...

We provide a novel local definition for spectrally flowed vertex operators in the SL(2,\mathbb{R}) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>S</mml:mi><mml:mi>L</mml:mi><mml:mo stretchy="false" form="prefix">(</mml:mo><mml:mn>2</mml:mn><mml:mo>,</mml:mo><mml:mstyle mathvariant="double-struck"><mml:mi>ℝ</mml:mi></mml:mstyle><mml:mo form="postfix">)</mml:mo></mml:mrow></mml:math> -WZW model, generalising proposal of Maldacena and Ooguri...

A bstract We present a detailed study of spectrally flowed four-point functions in the SL(2,ℝ) WZW model, focusing on their conformal block decomposition. Dei and Eberhardt conjectured general formula relating these observables to unflowed counterparts. Although latter are not known closed form, expansion has been formally established. By combining this information with integral transform that encodes effect spectral flow, we show how describe considerable number s -channel exchanges,...

We construct the effective action for toroidal compactifications of bosonic string theory from generalized Scherk-Schwarz reductions double field theory. The enhanced gauge symmetry arising at special points in moduli space is incorporated into this framework by promoting O(k, k) duality group k-tori to O(n, n), n being dimension group, which allows account full massless sector show that reproduces right masses scalar and vector fields when moving sligthly away maximal enhancement....

A set of recursive relations satisfied by Selberg-type integrals involving monomial symmetric polynomials are derived, generalizing previous results in Aomoto (1987) SIAM J. Math. Anal. 18 545–49 and Iguri (2009) Lett. Phys. 89 141–58. These formulas provide a well-defined algorithm for computing Selberg–Schur whenever the Kostka numbers relating Schur functions corresponding explicitly known. We illustrate usefulness our discussing some interesting examples.

In this article we investigate the structure of four-point functions AdS3-WZNW model. We consider integral expression for unflowed correlator involving at least one state in discrete part spectrum derived by analytic continuation from H 3 + -WZNW model and show that conformal blocks can be obtained those with an extremal-weight means intertwining operator. adapt procedure dealing correlators a single unit spectral flow charge get factorized corresponding function. finally transform formulas...

After an appropriate restatement of the Gelfand–Naimark–Segal construction for topological *-algebras we prove that there exists isomorphism among set Cycl(A) weakly continuous strongly cyclic *-representations a barreled dual-separable *-algebra with unit A, space HilbA(A*) Hilbert spaces are continuously embedded in A* and * -invariant under dual left regular action corresponding reproducing kernels. We show these isomorphisms cone morphisms many interesting results follow from this fact....

Recently an exact worldsheet description of strings propagating in certain black hole microstate geometries was constructed terms null-gauged WZW models. In this paper we consider a family such coset models, which the currents being gauged are specified by set parameters that priori take arbitrary values. We show consistency spectrum CFT implies quantisation conditions and parity restrictions on gauging parameters. also derive these constraints from independent geometrical analysis...

We derive a generalized Nielsen identity for the case of Yang-Mills theories that include some classical fields. discuss under which circumstances effective action fields (i.e., after integration quantum fields) becomes gauge fixing independent. conclude test provide physical insight into problem gauge-fixing dependence action.

In this article we investigate the structure of four-point functions $AdS_3$-WZNW model. We consider integral expression for unflowed correlator involving at least one state in discrete part spectrum derived by analytic continuation from $H_3^+$-WZNW model and show that conformal blocks can be obtained those with an extremal-weight means intertwining operator. adapt procedure dealing correlators a single unit spectral flow charge get factorized corresponding function. finally transform...

The duality angles deformation developed by de Roo and Wagemans within the context of $N=4$ gauged supergravity is used in order to study certain classes gaugings $N=8$ supergravity, namely, those that are consistent when halving maximal $D=4$ theory. After reviewing truncation process from terms embedding tensor formalism, Roo-Wagemans phases method implemented for solving resulting constraints on gauging parameters means Sch\"on-Weidner ansatz. In contrast with twenty semisimple admitting...