M. Shifman

On the motion of heavy quarks inside hadrons: Universal distributions and inclusive decays

In previous papers we have pointed out that there exists a QCD analog of the phenomenological concept of the so called Fermi motion for the heavy quark inside a hadron. Here we show in a more detailed way how this comes about and we analyze the limitations of this concept. Non-perturbative as well as perturbative aspects are included. We emphasize both the similarities and the differences to the well-known treatment of deep inelastic lepton-nucleon scattering. We derive a model-independent {\em lower} bound on the kinetic energy of the heavy quark inside the hadron.In previous papers we have pointed out that there exists a QCD analog of the phenomenological concept of the so-called Fermi motion for the heavy quark inside a hadron. Here we show in a more detailed way how this comes about and we analyze the limitations of this concept. Nonperturbative as well as perturbative aspects are included. We emphasize both similarities and differences to the well-known treatment of deep inelastic lepton-nucleon scattering. We derive a model-independent lower bound on the kinetic energy of the heavy quark inside the hadron.

Diluting the cosmological constant in infinite volume extra dimensions

We argue that the cosmological constant problem can be solved in a braneworld model with infinite-volume extra dimensions, avoiding no-go arguments applicable to theories that are four-dimensional in the infrared. Gravity on the brane becomes higher-dimensional at super-Hubble distances, which entails that the relation between the acceleration rate and vacuum energy density flips upside down compared to the conventional one. The acceleration rate decreases with increasing the energy density. The experimentally acceptable rate is obtained for the energy density larger than (1 TeV)

Sum rules for heavy flavor transitions in the small velocity limit

^4

Domain walls in supersymmetric Yang-Mills theories

. The results are stable under quantum corrections because supersymmetry is broken only on the brane and stays exact in the bulk of infinite volume extra space. Consistency of 4D gravity and cosmology on the brane requires the quantum gravity scale to be around

High power n of m b in b -flavored widths and n = 5 → ∞ limit

10^{-3}

Large extra dimensions: Becoming acquainted with an alternative paradigm

eV. Testable predictions emerging within this approach are: (i) simultaneous modifications of gravity at sub-millimeter and the Hubble scales; (ii) Hagedorn-type saturation in TeV energy collisions due to the Regge spectrum with the spacing equal to

b→s+γ: A QCD-CONSISTENT ANALYSIS OF THE PHOTON ENERGY DISTRIBUTION

10^{-3}

Heavy quark distribution function in QCD and the AC2M2 model

eV.

Higgs Decay into Two Photons through the W-boson Loop: No Decoupling in the

We show how sum rules for the weak decays of heavy flavor hadrons can be derived as the moments of spectral distributions in the small velocity limit. Our derivation of the sum rules is based on the operator product expansion. This systematic approach allows us to determine corrections to these sum rules, to obtain new sum rules, and it provides us with a transparent physical interpretation; it also opens a new perspective on the notion of the heavy quark mass. Applying these sum rules we derive a {ital lower} bound on the deviation of the exclusive form factor {ital F}{sub {ital B}{r_arrow}{ital D}}{sup *} from unity at zero recoil; likewise we give a field-theoretical derivation of a previously formulated inequality between the expectation value for the kinetic energy operator of the heavy quark and for the chromomagnetic operator. We analyze how the known results on nonperturbative corrections must be understood when one takes into account the normalization point dependence of the low scale parameters. The relation between the field-theoretic derivation of the sum rules and the quantum-mechanical approach is elucidated.

m_W

We present a detailed analysis of the domain walls in supersymmetric gluodynamics and SQCD. We use the (corrected) Veneziano-Yankielowicz effective Lagrangians to explicitly obtain the wall profiles and check recent results of Dvali and Shifman: (i) the BPS-saturated nature of the walls and (ii) the {ital exact} expressions for the wall energy density which depend only on global features of dynamics (the existence of a nontrivial central extension of N=1 superalgebra in the theories which admit wall-like solutions). If supersymmetry is softly broken by the gluino mass, the degeneracy of the distinct vacua is gone, and one can consider the decay rate of the {open_quotes}false{close_quotes} vacuum into the genuine one. We do this calculation in the limit of the small gluino mass. Finally, we comment on the controversy regarding the existence of N distinct chirally asymmetric vacua in SU(N) SUSY gluodynamics. {copyright} {ital 1997} {ital The American Physical Society}