Probing the Region of Massless Quarks in Quenched Lattice QCD using Wilson Fermions

We study the spectrum of $H(m)=\gamma_5 W(-m)$ with $W(m)$ being the Wilson-Dirac operator on the lattice with bare mass equal to $m$. The background gauge fields are generated using the SU(3) Wilson action at $\beta=5.7$ on an $8^3\times 16$ lattice. We find evidence that the spectrum of $H(m)$ is gapless for $1.02 < m < 2.0$, implying that the physical quark is massless in this whole region.Comment: 22 pages, LaTeX file, uses elsart.sty, includes 11 figures A typographical error in one reference has been fixe

Effective non-Markovian description of a system interacting with a bath

We study a harmonic system coupled to chain of first neighbor interacting oscillators. After deriving the exact dynamics of the system, we prove that one can effectively describe the exact dynamics by considering a suitable shorter chain. We provide the explicit expression for such an effective dynamics and we provide an upper bound on the error one makes considering it instead of the dynamics of the full chain. We eventually prove how error, timescale and number of modes in the truncated chain are related

Understanding the tsunami with a simple model

In this paper, we use the approximation of shallow water waves (Margaritondo G 2005 Eur. J. Phys. 26 401) to understand the behaviour of a tsunami in a variable depth. We deduce the shallow water wave equation and the continuity equation that must be satisfied when a wave encounters a discontinuity in the sea depth. A short explanation about how the tsunami hit the west coast of India is given based on the refraction phenomenon. Our procedure also includes a simple numerical calculation suitable for undergraduate students in physics and engineering

A Mean Field Approach To The Instanton-Induced Effect Close To The QCD Phase Transition

In the instanton models the chiral phase transition is driven by a transition from random instanton-antiinstanton liquid and correlated instanton-antiinstanton molecules. So far this phenomenon was studied by numerical simulations, while we develop alternative semi-analytic approach. For two massless quark flavors, both instantons and ``molecules" generate specific 4-fermion effective interactions. After those are derived, we determine the temperature dependence of the thermodynamic quantities, the quark condensate and the fraction of molecules using standard mean field method. Using Bethe-Salpeter equation, we calculate T-dependence of mesonic correlation functions.Comment: 26 pages, LaTeX, 6 postscript files of 6 figures in additio

Absence of exposed bone following dental extraction in beagle dogs treated with 9 months of high-dose zoledronic acid combined with dexamethasone

Purpose: Factors contributing to osteonecrosis of the jaw with anti-remodeling drug treatment are unclear. Epidemiologic and experimental studies have suggested the combination of bisphosphonates and dexamethasone results in osteonecrosis of the jaw more often than either agent alone. The goal of this study was to assess the combination of these 2 drugs in a large animal model previously shown to be susceptible to exposed bone in the oral cavity when treated with bisphosphonates. Materials and Methods: Skeletally mature beagle dogs were untreated controls or treated with zoledronic acid (ZOL), dexamethasone (DEX), or ZOL plus DEX. ZOL and DEX were given at doses based on those used in humans. All animals underwent single molar extraction at 7 and 8 months after the start of the study. Extraction sites were obtained at month 9 for assessment of osseous healing using micro-computed tomography and histology. Results: No animals were observed to have exposed bone after dental extraction, yet 1 animal treated with ZOL and 1 treated with ZOL plus DEX had severely disrupted extraction sites as viewed by computed tomography and histology. These 2 animals had an intense periosteal reaction that was less obvious but still present in all ZOL-treated animals and absent from untreated animals. There was no significant difference in bone volume within the socket among groups at 4 or 8 weeks after healing, yet the ratio of surface to volume was significantly higher in animals treated with ZOL plus DEX at 8 weeks compared with control animals. Conclusions: These findings suggest a more complex pathophysiology to osteonecrosis of the jaw than is implied by previous epidemiologic studies and those in rodents and raise questions about the potential role of DEX in its etiology.© 2013 American Association of Oral and Maxillofacial Surgeons

Limit cycles of effective theories

A simple example is used to show that renormalization group limit cycles of effective quantum theories can be studied in a new way. The method is based on the similarity renormalization group procedure for Hamiltonians. The example contains a logarithmic ultraviolet divergence that is generated by both real and imaginary parts of the Hamiltonian matrix elements. Discussion of the example includes a connection between asymptotic freedom with one scale of bound states and the limit cycle with an entire hierarchy of bound states.Comment: 8 pages, 3 figures, revtex

Local Commutativity and Causality in Interacting PP-wave String Field Theory

In this paper, we extend our previous study of causality and local commutativity of string fields in the pp-wave lightcone string field theory to include interaction. Contrary to the flat space case result of Lowe, Polchinski, Susskind, Thorlacius and Uglum, we found that the pp-wave interaction does not affect the local commutativity condition. Our results show that the pp-wave lightcone string field theory is not continuously connected with the flat space one. We also discuss the relation between the condition of local commutativity and causality. While the two notions are closely related in a point particle theory, their relation is less clear in string theory. We suggest that string local commutativity may be relevant for an operational defintion of causality using strings as probes.Comment: Latex, JHEP3.cls, 18 pages, no figures. v2: add comments about the UV-IR mixing effect displayed in our result. version to appear in JHE

New Measurements of Fine-Scale CMB Polarization Power Spectra from CAPMAP at Both 40 and 90 GHz

We present new measurements of the cosmic microwave background (CMB) polarization from the final season of the Cosmic Anisotropy Polarization MAPper (CAPMAP). The data set was obtained in winter 2004-2005 with the 7 m antenna in Crawford Hill, New Jersey, from 12 W-band (84-100 GHz) and 4 Q-band (36-45 GHz) correlation polarimeters with 3.3' and 6.5' beamsizes, respectively. After selection criteria were applied, 956 (939) hours of data survived for analysis of W-band (Q-band) data. Two independent and complementary pipelines produced results in excellent agreement with each other. A broad suite of null tests as well as extensive simulations showed that systematic errors were minimal, and a comparison of the W-band and Q-band sky maps revealed no contamination from galactic foregrounds. We report the E-mode and B-mode power spectra in 7 bands in the range 200 < l < 3000, extending the range of previous measurements to higher l. The E-mode spectrum, which is detected at 11 sigma significance, is in agreement with cosmological predictions and with previous work at other frequencies and angular resolutions. The BB power spectrum provides one of the best limits to date on B-mode power at 4.8 uK^2 (95% confidence).Comment: 19 pages, 17 figures, 2 tables, submitted to Ap