119204877
Consistent Factorization of Jet Observables in Exclusive Multijet Cross-Sections
Abstract We demonstrate the consistency at the next-to-leading-logarithmic (NLL) level of a factorization theorem based on Soft-Collinear Effective Theory (SCET) for jet shapes in e + e − collisions. We consider measuring jet observables in exclusive multijet final states defined with cone and k T -type jet algorithms. Consistency of the factorization theorem requires that the renormalization group evolution of hard, jet, and soft functions is such that the physical cross section is independent of the factorization scale μ . The anomalous dimensions of the various factorized pieces, however, depend on the color representation of jets, choice of jet observable, the number of jets whose shapes are measured, and the jet algorithm, making it highly nontrivial to satisfy the consistency condition. We demonstrate the intricate cancellations between anomalous dimensions that occur at the NLL level, so that, up to power corrections that we identify, our factorization of the jet shape distributions is consistent for any number of quark and gluon jets, for any number of jets whose shapes are measured or unmeasured, for any angular size R of the jets, and for any of the algorithms we consider. Corrections to these results are suppressed by the SCET expansion parameter λ (set by the ratio of the typical momentum in a jet transverse to the jet axis to the total jet energy) and in the jet separation measure 1 / t 2 = tan 2 ( R / 2 ) / tan 2 ( ψ / 2 ) , where ψ is the angular separation between jets. Our results can be used to calculate a wide variety of jet observables in multijet final states to NLL accuracy.
117935318
CP‐Violating Sources for Electroweak Baryogenesis
In this talk I derive the CP‐violating sources for the squark number density in the MSSM generated by interactions with the spacetime‐varying Higgs vev during a first‐order electroweak phase transition.
118742958
Universality of Nonperturbative Effects in Event Shapes
Nonperturbative effects in event shape distributions can be characterized by shape functions derived in the eikonal approximation or, equivalently, from soft-collinear effective theory. The use of energy flow operators and the boost invariance of the Wilson lines of soft gluons in the shape functions leads to a proof of universality for power corrections to the mean values of event shapes, without invoking the single gluon approximation.
17888703
Resonant Flavor Oscillations in Electroweak Baryogenesis
Electroweak baryogenesis (EWBG) in extensions of the Standard Model will be tested quantitatively in upcoming nuclear and particle physics experiments, but only to the extent that theoretical computations are robust. Currently there exist orders-of-magnitude discrepancies between treatments of charge transport dynamics during EWBG performed by different groups, each relying on different sets of approximations. In this work, we introduce a consistent power counting scheme (in ratios of length scales) for treating systematically the dynamics of EWBG: CP-asymmetric flavor oscillations, collisions, and diffusion. Within the context of a simplified model of EWBG, we derive the relevant Boltzmann equations using non-equilibrium field theory, and solve them exactly without ansatz for the functional form of the density matrices. We demonstrate the existence of a resonant enhancement in charge production when the flavor oscillation length is comparable to the wall thickness. We compare our results with the existing treatment of EWBG by Konstandin, Prokopec, Schmidt, and Seco (KPSS) who previously identified the importance of flavor oscillations in EWBG. We conclude: (i) the power counting of KPSS breaks down in the resonant regime, and (ii) this leads to substantial underestimation of the charge generated in the unbroken phase, and potentially of the final baryon asymmetry.
122534296
Peeking inside jets for clues of new physics
Observables probing jet structure and substructure help uncover clues about the energetic particles which originated them, such as ordinary light quarks and gluons or from decays of heavy particles in and beyond the Standard Model. This talk overviews such recently introduced methods.
26881716
Resonant relaxation in electroweak baryogenesis
We compute the leading, chiral charge-changing relaxation term in the quantum transport equations that govern electroweak baryogenesis using the closed time path formulation of nonequilibrium quantum field theory. We show that the relaxation transport coefficients may be resonantly enhanced under appropriate conditions on electroweak model parameters and that such enhancements can mitigate the impact of similar enhancements in the CP-violating source terms. We also develop a power counting in the time and energy scales entering electroweak baryogenesis and include effects through second order in ratios epsilon of the small and large scales. We illustrate the implications of the resonantly enhanced [script O](epsilon 2) terms using the Minimal Supersymmetric Standard Model, focusing on the interplay between the requirements of baryogenesis and constraints obtained from collider studies, precision electroweak data, and electric dipole moment searches.
2929156
Relativistic Electrodynamics of Spinning Compact Objects
A theoretical study of some electrodynamic features of a region close to a slowly-rotating magnetized relativistic star is performed. To be a little more specific, based on the solution-generating method given by Wald, the magnetic fields around both uncharged and (slightly) charged relativistic stars have been obtained. Particularly for a charged relativistic star, again following the argument by Wald, the star was shown to gradually accrete charge until it reached an equilibrium value Q = 2B0J . This value of the equilibrium charge seems to be generic as a rotating black hole is known to accrete exactly the same amount. Although these results are equally relevant to all species of slowly-rotating relativistic stars, we particularly have the rotating neutron star in mind. As such, it would be of some interest to attempt to make contact with a real pulsar case. Thus, we discuss how many of the theoretical results obtained in the present work can be carried over to a realistic, general relativistic description of a pulsar’s magnetosphere.
119244769
Solutions in IR Modified Horava-Lifshitz Gravity
In order to allow the asymptotically flat, we consider Ho\v{r}ava-Lifshitz gravity theory with a soft violation of the detailed balance condition and obtain various solutions. In particular, we find that such theory coupled to a global monopole leads to a solution representing a space with deficit solid angle, which is well matched with genuine feature of GR.
15692757
Magnetic alignment process: a new mechanism for extracting energy from rotating black holes
The magnetic alignment process is proposed as a complementary or companion process to the Blandford–Znajek mechanism for the rotational energy extraction from a Kerr black hole, to serve as a viable model for the central engine of quasars, AGN, and even GRB. In contrast to the environment assumed in the Blandford–Znajek mechanism, in which the rotating hole's spin axis and the asymptotic direction of the magnetic field are aligned, this new process operates when they are generally misaligned, which obviously is the more natural situation likely to happen. The time scales over which these two processes take place and the total radiated powers released at the horizon by them have been estimated and found to be nearly comparable. This may imply that in a random, non-axisymmetric configuration, the magnetic alignment process would operate first, during which some of the hole's rotational energy is released, and then upon completion of the alignment, the Blandford–Znajek mechanism may follow and the rest of the hole's rotational energy, if any left, would be further released.
14255357
Closed strings interacting with non-commutative D-branes
Abstract Closed string dynamics in the presence of non-commutative D p -branes is investigated. In particular, we compute bulk closed string two-point scattering amplitudes; the bulk space-time geometries encoded in the amplitudes are shown to be consistent with the recently proposed background space-time geometries dual to non-commutative Yang–Mills theories. Three-point closed string absorption/emission amplitudes are obtained to show some features of non-commutative D p -branes, such as modified pole structures and exponential phase factors linearly proportional to the external closed string momentum.
18034270
Nonequilibrium quantum dynamics of second order phase transitions
We use the so-called Liouville\char21{}von Neumann (LvN) approach to study the nonequilibrium quantum dynamics of time-dependent second order phase transitions. The LvN approach is a canonical method that unifies the functional Schr\"odinger equation for the quantum evolution of pure states and the LvN equation for the quantum description of mixed states of either equilibrium or nonequilibrium. As nonequilibrium quantum mechanical systems we study a time-dependent harmonic and an anharmonic oscillator and find the exact Fock space and density operator for the harmonic oscillator and the nonperturbative Gaussian Fock space and density operator for the anharmonic oscillator. The density matrix and the coherent, thermal, and coherent-thermal states are found in terms of their classical solutions, for which the effective Hamiltonians and equations of motion are derived. The LvN approach is further extended to quantum fields undergoing time-dependent second order phase transitions. We study an exactly solvable model with a finite smooth quench and find the two-point correlation functions. Because of the spinodal instability of long wavelength modes, the two-point correlation functions lead to the ${t}^{1/4}$-scaling relation during the quench and the Cahn-Allen scaling relation ${t}^{1/2}$ after completion of the quench. Further, after the finite quench the domain formation shows a time-lag behavior at the cubic power of the quench period. Finally we study the time-dependent phase transition of a self-interacting scalar field.