118668452
Neutrino-induced forward meson-production reactions in nucleon resonance region
As a first step toward developing a reaction model that enables a comprehensive description of neutrino-nucleon reactions in the nucleon resonance region, we have applied for the first time a dynamical coupled-channels model, which successfully describes \pi N, \gamma N --> \pi N, \eta N, \pi \pi N, K\Lambda, K\Sigma reactions up to W = 2 GeV, to predict the neutrino-induced meson-production reactions with \Delta S = 0 at the forward angle limit. This has been achieved by relating the divergence of the axial-current matrix elements at Q^2 = 0 to the \pi N --> X reaction amplitudes through the PCAC hypothesis. We present the contributions from each of the \pi N, \eta N, \pi \pi N, K\Lambda, K\Sigma channels to the F_2 structure function at Q^2 --> 0 limit up to W = 2 GeV.
14437805
Consideration of nuclear forces from the viewpoint of the renormalization group: Relation of nuclear forces between phenomenological approach and nuclear effective field theory
A relation between nuclear forces derived using a phenomenological approach and nuclear effective field theory (NEFT) is proposed from a renormalization group point of view. A phenomenological nuclear force (V ph ) and an NEFT-based NN-potential (V EFT ) are satisfactorily related to each other through the Wilsonian renormalization group (WRG) method. It is clearly shown that use of the simple contact interactions in NEFT is adequate to simulate small scale phenomena, and that an NEFT-based NN-potential (V EFT ) is free from dependence on the model used to describe small scale phenomena. We study the characteristics of V EFT from a WRG point of view, emphasizing points that have not previously been fully recognized. We also use the V low k method and a unitary transformation method to relate V ph to V EFT . It is found that they are not appropriate for this purpose.
85451103
Extraction of Meson Resonances from Three-pions Photo-production Reactions
We have investigated the model dependence of meson resonance properties extracted from the Dalitz-plot analysis of the three-pions photoproduction reactions on the nucleon. Within a unitary model developed in Phys. Rev. D 84, 114019 (2011), we generate Dalitz-plot distributions as data to perform an isobar model fit that is similar to most of the previous analyses of three-pion production reactions. It is found that the resonance positions from the two models agree well when both fit the data accurately, except for the resonance poles near branch points. The residues of the resonant amplitudes extracted from the two models and by the usual Breit-Wigner procedure agree well only for the isolated resonances with narrow widths. For overlapping resonances, most of the extracted residues could be drastically different. Our results suggest that even with high precision data, the resonance extraction should be based on models within which the amplitude parametrization is constrained by three-particle unitarity condition.
117947270
Meson spectroscopy with unitary coupled-channels model for heavy-meson decay into three mesons
We develop a model for describing excited mesons decay into three mesons. The properties of the excited mesons can be extracted with this model. The model maintains the three-body unitarity that has been missed in previous data analyses based on the conventional isobar models. We study an importance of the three-body unitarity in extracting hadron properties from data. For this purpose, we use the unitary and isobar models to analyze the same pseudo data of gamma p -> pi+pi+pi-n, and extract the properties of excited mesons. We find a significant difference between the unitary and isobar models in the extracted properties of excited mesons, such as the mass, width and coupling strength to decay channels.
122375456
Renormalization group analysis of nuclear current operators
A Wilsonian renormalization group (WRG) equation for nuclear current operators in two-nucleon systems is derived. Nuclear current operators relevant to low-energy Gamow-Teller transitions are analyzed using the WRG equation. We employ the axial two-body current operators from phenomenological models and heavy-baryon chiral perturbation theory, which are quite different from one another in describing small-scale physics. After reducing the model space of the operators using the WRG equation, we find that there still remains a significant model dependence at {lambda}=200 MeV, where {lambda} is the sharp cutoff specifying the size of the model space. A model-independent effective current operator is found at a rather small cutoff value, {lambda}=70 MeV. By simulating the effective current operator at {lambda}=70 MeV, we obtain a current operator based on a pionless theory, thereby arguing that an equivalence relation exists between nuclear current operators of phenomenological models and those of effective field theories.
119109289
Explanation of the More Effective Effective Field Theory
We show that the so-called more effective effective field theory (MEEFT) is essentially equivalent to the proper nuclear effective field theory (NEFT) in describing low-energy electroweak processes in nuclei. A key to understanding their equivalence is the relation between aN EFT-based NN -potential and a phenomenological potential through the Wilsonian renormalization group equation. We also discuss an important advantage of MEEFT.
29394289
A New Phase at a Finite Quark Density from AdS/CFT
We explore phases of N=2 super Yang-Mills theory at finite quark density by introducing quark chemical potential in a D3-D7 setup. We formulate the thermodynamics of brane embeddings and find that we need to renormalize the finite chemical potential due to the divergence of the thermodynamic potentials and we find that the density versus chemical potential equation of state has rich structure. This yields two distinct first order phase transitions in a small window of quark density. In order words, there is a new first order phase transition in the region of deconfined quarks. In this new phase, the chemical potential is a decreasing function of the density. We suggest that this might be relevant to the difference in sQGP--wQGP phases of QCD.
8805719
Local recoil of extended solitons: a string theory example
It is well-known that localized topological defects (solitons) experience recoil when they suffer an impact by incident particles. Higher-dimensional topological defects develop distinctive wave patterns propagating along their worldvolume under similar circumstances. For 1-dimensional topological defects (vortex lines), these wave patterns fail to decay in the asymptotic future: the propagating wave eventually displaces the vortex line a finite distance away from its original position (the distance is proportional to the transferred momentum). The quantum version of this phenomenon, which we call ``local recoil'', can be seen as a simple geometric manifestation of the absence of spontaneous symmetry breaking in 1+1 dimensions. Analogously to soliton recoil, local recoil of vortex lines is associated with infrared divergences in perturbative expansions. In perturbative string theory, such divergences appear in amplitudes for closed strings scattering off a static D1-brane. Through a Dirac-Born-Infeld analysis, it is possible to resum these divergences in a way that yields finite, momentum-conserving amplitudes.
16327431
Recoiling D-branes
Abstract We propose a new method to describe a recoiling D-brane that is elastically scattered by closed strings in the nonrelativistic region. We utilize the low-energy effective field theory on the worldvolume of the D-brane, and the velocity of the D-brane is described by the time derivative of the expectation values of the massless scalar fields on the worldvolume. The effects of the closed strings are represented by a source term for the massless fields in this method. The momentum conservation condition between the closed strings and the D-brane is derived up to the relative sign of the momentum of the D-brane.
119230109
Baryon-charge Chemical Potential in AdS/CFT
We present a closed framework of AdS/CFT with finite U(1)B-charge chemical potential. We show how the gauge-invariant identification of the chemical potential with the bulk gauge field emerges from the standard AdS/CFT dictionary. Physical importance and necessity of the Minkowski embeddings within the present framework is also shown numerically in the D3-D7 systems. We point out that the D3-D7 model with only the black-hole embeddings does not have the low-temperature and lowchemical-potential region in the grand-canonical ensemble, hence it is incomplete. A physical interpretation that explains these numerical results is also proposed.
1079114
Dirichlet Boundary Conditions in Generalized Liouville Theory toward a QCD String
We consider bosonic noncritical strings as QCD strings and we present a basic strategy to construct them in the context of Liouville theory. We show that Dirichlet boundary conditions play important roles in generalized Liouville theory. Specifically, they are used to stabilize the classical configuration of strings and also utilized to treat tachyon condensation in our model. We point out that Dirichlet boundary conditions for the Liouville mode maintains Weyl invariance, if an appropriate condition is satisfied, in the background with a (non-linear) dilaton.