Renormalization of twist-four operators in light-cone gauge

We compute one-loop renormalization group equations for non-singlet twist-four operators in QCD. The calculation heavily relies on the light-cone gauge formalism in the momentum fraction space that essentially rephrases the analysis of all two-to-two and two-to-three transition kernels to purely algebraic manipulations both for non- and quasipartonic operators. This is the first brute force calculation of this sector available in the literature. Fourier transforming our findings to the coordinate space, we checked them against available results obtained within a conformal symmetry-based formalism that bypasses explicit diagrammatic calculations and confirmed agreement with the latter

The flaw in the firewall argument

A lot of confusion surrounds the issue of black hole complementarity, because the question has been considered without discussing the mechanism which guarantees unitarity. Considering such a mechanism leads to the following: (1) The Hawking quanta with energy E of order the black hole temperature T carry information, and so only appropriate processes involving <math altimg="si1.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mi>E</mi><mo>≫</mo><mi>T</mi></math> quanta can have any possible complementary description with an information-free horizon; (2) The stretched horizon describes all possible black hole states with a given mass M , and it must expand out to a distance <math altimg="si2.gif" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>s</mi></mrow><mrow><mtext><ce:italic>bubble</ce:italic></mtext></mrow></msub></math> before it can accept additional infalling bits; (3) The Hawking radiation has a specific low temperature T , and infalling quanta interact significantly with it only within a distance <math altimg="si3.gif" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>s</mi></mrow><mrow><mi>α</mi></mrow></msub></math> of the horizon. One finds <math altimg="si4.gif" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>s</mi></mrow><mrow><mi>α</mi></mrow></msub><mo>≪</mo><msub><mrow><mi>s</mi></mrow><mrow><mtext><ce:italic>bubble</ce:italic></mtext></mrow></msub></math> for <math altimg="si1.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mi>E</mi><mo>≫</mo><mi>T</mi></math> , and this removes the argument against complementarity recently made by Almheiri et al. In particular, the condition <math altimg="si1.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mi>E</mi><mo>≫</mo><mi>T</mi></math> leads to the notion of ‘fuzzball complementarity’, where the modes around the horizon are indeed correctly entangled in the complementary picture to give the vacuum

Hamiltonian, path integral and BRST formulations of large N scalar QCD 2 on the light-front and spontaneous symmetry breaking

Recently Grinstein, Jora, and Polosa have studied a theory of large- N scalar quantum chromodynamics in one space and one time dimension. This theory admits a Bethe–Salpeter equation describing the discrete spectrum of quark–antiquark bound states. They consider gauge fields in the adjoint representation of SU(N) and scalar fields in the fundamental representation. The theory is asymptotically free and linearly confining. The theory could possibly provide a good field theoretic framework for the description of a large class of diquark–antidiquark (tetra-quark) states. Recently we have studied the light-front quantization of this theory without a Higgs potential. In the present work, we study the light-front Hamiltonian, path integral, and BRST formulations of the theory in the presence of a Higgs potential. The light-front theory is seen to be gauge invariant, possessing a set of first-class constraints. The explicit occurrence of spontaneous symmetry breaking in the theory is shown in unitary gauge as well as in the light-front ’t Hooft gauge

Metric-independent measures for supersymmetric extended object theories on curved backgrounds

For Green–Schwarz superstring σ -model on curved backgrounds, we introduce a non-metric measure Φ≡ϵijϵIJ(∂iφI)(∂jφJ) with two scalars φI(I=1,2) used in ‘Two-Measure Theory’ (TMT). As in the flat-background case, the string tension T=(2πα′)−1 emerges as an integration constant for the Ai -field equation. This mechanism is further generalized to supermembrane theory, and to super- p -brane theory, both on general curved backgrounds. This shows the universal applications of dynamical measure of TMT to general supersymmetric extended objects on general curved backgrounds

Neutron spectroscopic factors of 55 Ni hole-states from (p,d) transfer reactions

Spectroscopic information has been extracted on the hole-states of 55 Ni, the least known of the quartet of nuclei ( 55 Ni, 57 Ni, 55 Co and 57 Cu), one nucleon away from 56 Ni, the N=Z=28 double magic nucleus. Using the H1(Ni56,d)Ni55 transfer reaction in inverse kinematics, neutron spectroscopic factors, spins and parities have been extracted for the f7/2 , p3/2 and the s1/2 hole-states of 55 Ni. These new data provide a benchmark for large basis calculations that include nucleonic orbits in both the sd and pf shells. State of the art calculations have been performed to describe the excitation energies and spectroscopic factors of the s1/2 hole-state below Fermi energy

Nucleon–nucleon resonances at intermediate energies using a complex energy formalism

We apply our method of complex scaling, valid for a general class of potentials, in a search for nucleon–nucleon S-matrix poles up to 2 GeV laboratory kinetic energy. We find that the realistic potentials JISP16, constructed from inverse scattering, and chiral field theory potentials N 3 LO and N 2 LO opt support resonances in energy regions well above their fit regions. In some cases these resonances have widths that are small when compared with the real part of the S-matrix pole

Electron g-2 in Light-front Quantization

Basis Light-front Quantization has been proposed as a nonperturbative framework for solving quantum field theory. We apply this approach to Quantum Electrodynamics and explicitly solve for the light-front wave function of a physical electron. Based on the resulting light-front wave function, we evaluate the electron anomalous magnetic moment. Nonperturbative mass renormalization is performed. Upon extrapolation to the infinite basis limit our numerical results agree with the Schwinger result obtained in perturbation theory to an accuracy of 0.06%

Neutrino seesaw mechanism with texture zeros

In the context of the Type I seesaw mechanism, we carry out a systematic study of the constraints that result from zeros in both the Dirac and right-handed Majorana neutrino mass matrices. We find that most constraints can be expressed in the standard form with one or two element/cofactor zeros alone, while there are 9 classes of nonstandard constraints. We show that all the constraints are stable under one-loop renormalization group running from the lightest right-handed neutrino mass scale to the electroweak scale. We study the predictions of the nonstandard constraints for the lightest neutrino mass, Dirac CP phase and neutrinoless double beta decay

A predictive model of Dirac neutrinos

Assuming lepton number conservation, hermiticity of the neutrino mass matrix and <math altimg="si1.gif" xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mi>ν</mi></mrow><mrow><mi>μ</mi></mrow></msub><mtext>–</mtext><msub><mrow><mi>ν</mi></mrow><mrow><mi>τ</mi></mrow></msub></math> exchange symmetry, we show that we can determine the neutrino mass matrix completely from the existing data. Comparing with the existing data, our model predicts an inverted mass hierarchy (close to a degenerate pattern) with the three neutrino mass values, <math altimg="si2.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mn>9.16</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup><mtext> </mtext><mtext>eV</mtext></math> , <math altimg="si3.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mn>9.21</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup><mtext> </mtext><mtext>eV</mtext></math> and <math altimg="si4.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mn>7.80</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup><mtext> </mtext><mtext>eV</mtext></math> , a large value for the CP violating phase, <math altimg="si5.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mi>δ</mi><mo>=</mo><mn>109.63</mn><mi mathvariant="normal">°</mi></math> , and of course, the absence of neutrinoless ββ decay. All of these predictions can be tested in the forthcoming or future precision neutrino experiments

Benchmarking nuclear models for Gamow–Teller response

A comparative study of the nuclear Gamow–Teller response (GTR) within conceptually different state-of-the-art approaches is presented. Three nuclear microscopic models are considered: (i) the recently developed charge-exchange relativistic time blocking approximation (RTBA) based on the covariant density functional theory, (ii) the shell model (SM) with an extended “jj77” model space and (iii) the non-relativistic quasiparticle random-phase approximation (QRPA) with a Brueckner G-matrix effective interaction. We study the physics cases where two or all three of these models can be applied. The Gamow–Teller response functions are calculated for 208 Pb, 132 Sn and 78 Ni within both RTBA and QRPA. The strengths obtained for 208 Pb are compared to data that enable a firm model benchmarking. For the nucleus 132 Sn, also SM calculations are performed within the model space truncated at the level of a particle–hole (ph) coupled to vibration configurations. This allows a consistent comparison to the RTBA where ph⊗phonon coupling is responsible for the spreading width and considerable quenching of the GTR. Differences between the models and perspectives of their future developments are discussed