Publications (130)245.63 Total impact

Article: Effective string theory and the longrange relativistic corrections to the quarkantiquark potential
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ABSTRACT: The complete expression of the heavy quarkantiquark potential up to order $1/m^2$ is known from QCD in terms of Wilson loop expectation values. We use that expression and a mapping, assumed to be valid at large distances, between Wilson loop expectation values and correlators evaluated in the effective string theory, to compute the potential. We obtain previously unknown results for the spin and momentumindependent parts of the potential. They may be interpreted as relativistic corrections to the string tension, $\sigma$, effectively reducing it by an amount $9\,\zeta_3/(2\pi^3) \times (\sigma/m)^2$ in the equal mass case. We confirm known results for the other parts of the potential. Finally, we compute the discrete spectrum of a heavy quarkantiquark pair whose interaction is just given by the potential prescribed by the effective string theory.07/2014; 
Article: The Physics of the B Factories
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ABSTRACT: This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C.06/2014;  [Show abstract] [Hide abstract]
ABSTRACT: We highlight the progress, current status, and open challenges of QCDdriven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to stronglycoupled, complex systems in particle and condensedmatter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.04/2014;  [Show abstract] [Hide abstract]
ABSTRACT: We give a short overview of the renormalization properties of rectangular Wilson loops, the Polyakov loop correlator and the cyclic Wilson loop. We then discuss how to renormalize loops with more than one intersection, using the simplest nontrivial case as an illustrative example. Our findings expand on previous treatments. The generalized exponentiation theorem is applied to the Polyakov loop correlator and used to renormalize linear divergences in the cyclic Wilson loop.12/2013;  [Show abstract] [Hide abstract]
ABSTRACT: Heavy Majorana neutrinos enter in many scenarios of physics beyond the Standard Model: in the original seesaw mechanism they provide a natural explanation for the small masses of the Standard Model neutrinos and in the simplest leptogenesis framework they are at the origin of the baryonic matter of the universe. In this paper, we develop an effective field theory for nonrelativistic Majorana particles, which is analogous to the heavyquark effective theory. Then, we apply it to the case of a heavy Majorana neutrino decaying in a hot and dense plasma of Standard Model particles, whose temperature is much smaller than the mass of the Majorana neutrino but still much larger than the electroweak scale. The thermal corrections to the width computed in the effective field theory agree with recent results obtained using different methods, whereas the derivation appears to be simpler. The effective field theory presented here is suitable to be used for a variety of different models involving nonrelativistic Majorana fermions.Journal of High Energy Physics 07/2013; 2013(12). · 5.62 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We study the symmetries of the threeheavyquark system under exchange of the quark fields within the effective field theory framework of potential nonrelativistic QCD. The symmetries constrain the form of the matching coefficients in the effective theory. We then focus on the colorsinglet sector and determine the so far unknown leading ultrasoft contribution to the static potential, which is of order αs4lnμ, and consequently to the static energy, which is of order αs4lnαs. Finally, in the case of an equilateral geometry, we solve the renormalization group equations and resum the leading ultrasoft logarithms for the static potential of three quarks in a color singlet, octet and decuplet representation.Physical review D: Particles and fields 04/2013; 87(7).  [Show abstract] [Hide abstract]
ABSTRACT: In a weakcoupling effective field theory framework we study quarkonium dissociation induced by inelastic scattering with partons in the medium. This is the dominant dissociation process for temperatures such that the Debye mass is larger than the binding energy. We evaluate the dissociation cross section and the corresponding thermal decay width. At leading order we derive a convolution formula relating the two, which is consistent with the optical theorem and QCD at finite temperature. Bound state effects are systematically included. They add contributions to the cross section and width that are beyond a quasifree approximation, whose validity is critically reviewed. For temperatures such that the Debye mass is smaller than the binding energy, the dominant dissociation mechanism is gluodissociation consisting in quarkonium dissociation induced by the absorbtion of a gluon from the medium. We calculate the gluodissociation cross section and width at nexttoleadingorder accuracy.Journal of High Energy Physics 03/2013; 2013(5). · 5.62 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: In finitetemperature field theory, the cyclic Wilson loop is defined as a rectangular Wilson loop spanning the whole compactified time direction. In a generic nonabelian gauge theory, we calculate the perturbative expansion of the cyclic Wilson loop up to order g^4. At this order and after charge renormalization, the cyclic Wilson loop is known to be ultraviolet divergent. We show that the divergence is not associated with cusps in the contour but is instead due to the contour intersecting itself because of the periodic boundary conditions. One consequence of this is that the cyclic Wilson loop mixes under renormalization with the correlator of two Polyakov loops. The resulting renormalization equation is tested up to order g^6 and used to resum the leading logarithms associated with the intersection divergence. Implications for lattice studies of this operator, which may be relevant for the phenomenology of quarkonium at finite temperature, are discussed.Journal of High Energy Physics 12/2012; 2013(3). · 5.62 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: In the framework of SoftCollinear Effective Theory, the jet quenching parameter, $\hat{q}$, has been evaluated by adding the effect of Glauber gluon interactions to the propagation of a highlyenergetic collinear parton in a medium. The result, which holds in covariant gauges, has been expressed in terms of the expectation value of two Wilson lines stretching along the direction of the fourmomentum of the parton. In this paper, we show how that expression can be generalized to an arbitrary gauge by the addition of transverse Wilson lines. The transverse Wilson lines are explicitly computed by resumming interactions of the parton with Glauber gluons that appear only in noncovariant gauges. As an application of our result, we discuss the contribution to $\hat{q}$ coming from transverse momenta of order $g^2T$ in a medium that is a weaklycoupled quarkgluon plasma.Journal of High Energy Physics 08/2012; 2013(2). · 5.62 Impact Factor  Physical Review Letters 06/2012; 108(26). · 7.73 Impact Factor
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ABSTRACT: We compare lattice data for the shortdistance part of the static energy in 2+1 flavor quantum chromodynamics (QCD) with perturbative calculations, up to nexttonexttonextto leadinglogarithmic accuracy. We show that perturbation theory describes very well the lattice data at short distances, and exploit this fact to obtain a determination of the product of the lattice scale r_0 with the QCD scale Lambda_{MS}. With the input of the value of r_0, this provides a determination of the strong coupling alpha_s at the typical distance scale of the lattice data. We obtain alpha_s(1.5 GeV)=0.326\pm0.019, which provides a novel determination of alpha_s at low energy and with threeloop accuracy (including resummation of the leading ultrasoft logarithms). When this value is evolved to the Zmass scale M_Z, it corresponds to alpha_s(M_Z)=0.1156^{+0.0021}_{0.0022}.Physical review D: Particles and fields 05/2012; 86(11).  [Show abstract] [Hide abstract]
ABSTRACT: The paper contains a systematic, modelindependent treatment of electric dipole (E1) transitions in heavy quarkonium. Within the effective field theory framework of potential nonrelativistic QCD (pNRQCD), we derive the complete set of relativistic corrections of relative order v^2 both for weakly and stronglycoupled quarkonia. The result supports and complements former results from potential model calculations.Physical review D: Particles and fields 03/2012; 85(9).  [Show abstract] [Hide abstract]
ABSTRACT: These are the proceedings of the "Workshop on Precision Measurements of alphas" held at the MaxPlanckInstitute for Physics, Munich, February 911, 2011. The workshop explored in depth the determination of alphas(mZ) in the MSbar scheme from the key categories where high precision measurements are currently being made, including DIS and global PDF fits, taudecays, electroweak precision observables and Zdecays, eventshapes, and lattice QCD. These proceedings contain a short summary contribution from the speakers, as well as the lists of authors, conveners, participants, and talks.09/2011;  [Show abstract] [Hide abstract]
ABSTRACT: The thermal width of heavyquarkonium bound states in a quarkgluon plasma has been recently derived in an effective field theory approach. Two phenomena contribute to the width: the Landau damping phenomenon and the breakup of a coloursinglet bound state into a colouroctet heavy quarkantiquark pair by absorption of a thermal gluon. In the paper, we investigate the relation between the singlettooctet thermal breakup and the socalled gluodissociation, a mechanism for quarkonium dissociation widely used in phenomenological approaches. The gluodissociation thermal width is obtained by convoluting the gluon thermal distribution with the cross section of a gluon and a 1S quarkonium state to a colour octet quarkantiquark state in vacuum, a cross section that at leading order, but neglecting colouroctet effects, was computed long ago by Bhanot and Peskin. We will, first, show that the effective field theory framework provides a natural derivation of the gluodissociation factorization formula at leading order, which is, indeed, the singlettooctet thermal breakup expression. Second, the singlettooctet thermal breakup expression will allow us to improve the BhanotPeskin cross section by including the contribution of the octet potential, which amounts to include finalstate interactions between the heavy quark and antiquark. Finally, we will quantify the effects due to finalstate interactions on the gluodissociation cross section and on the quarkonium thermal width.Journal of High Energy Physics 09/2011; · 5.62 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: I review some recent progress, open puzzles and future opportunities in heavy quarkonium physics in the framework of effective field theories06/2011;  [Show abstract] [Hide abstract]
ABSTRACT: We present an effective field theory based extraction of the ɛc mass and width from a recent measurement by CLEO of the photon line shape in the J/ψ>ɛcγ decay.05/2011;  [Show abstract] [Hide abstract]
ABSTRACT: We compute the complete imaginary part of the NRQCD Lagrangian at order 1/M^4 in the heavyquark mass expansion, which includes center of mass operators, and at order alpha_s^2 in the matching coefficients. We also compute the imaginary part of the NRQCD Lagrangian at order 1/M^6 and at order alpha_s^2 that contributes to the Swave and Pwave inclusive decay widths of heavy quarkonium into light hadrons at order v^7 in the heavyquark velocity expansion. If we count alpha_s(M) ~ v^2, the calculation provides the complete nexttoleading order corrections to the Pwave hadronic widths, and in the original NRQCD power counting, the complete nexttoleading order corrections to the vector Swave widths, and part of the nexttonextto leading order corrections to the pseudoscalar Swave widths. In the Swave case, we confirm previous findings and add new terms in a more conservative power counting. In the Pwave case, our results are in disagreement with previous ones. Constraints induced by Poincare' invariance on the NRQCD fourfermion sector are studied for the first time and provide an additional check of the calculation. Perspectives for phenomenological applications are discussed.Physical review D: Particles and fields 04/2011; 83(7).  [Show abstract] [Hide abstract]
ABSTRACT: I review some recent developments in the theory of heavy quarkonium in an effective field theory framework.01/2011;  [Show abstract] [Hide abstract]
ABSTRACT: We correct eq. (A.1) and the following comment of JHEP 0608 (2006) 039. The correction does not affect the rest of the paper that remains unchanged.Journal of High Energy Physics 01/2011; 2011(4):12. · 5.62 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We use the recently obtained theoretical expression for the complete QCD static energy at nexttonexttonextto leadinglogarithmic accuracy to determine r(0)Lambda((MS) over bar) by comparison with available lattice data, where r(0) is the lattice scale and Lambda((MS) over bar) is the QCD scale. We obtain r(0)Lambda((MS) over bar) = 0.622(0.015)(+0.019) for the zeroflavor case. The procedure we describe can be directly used to obtain r(0)Lambda((MS) over bar) in the unquenched case, when unquenched lattice data for the static energy at short distances becomes available. Using the value of the strong coupling alpha(s) as an input, the unquenched result would provide a determination of the lattice scale r(0).01/2011;
Publication Stats
2k  Citations  
245.63  Total Impact Points  
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Institutions

2013

FriedrichSchillerUniversity Jena
Jena, Thuringia, Germany


2009–2013

University of Technology Munich
 Faculty of Physics
München, Bavaria, Germany


1990–2011

University of Milan
 Department of Physics
Milano, Lombardy, Italy


2010

Università degli Studi di Genova
 Department of Physics
Genova, Liguria, Italy


1997–2000

Universität Heidelberg
 Institute of Theoretical Physics
Heidelburg, BadenWürttemberg, Germany 
Heidelberg University
Tiffin, Ohio, United States 
Hampton University
Hampton, Virginia, United States


1995–2000

CERN
Genève, Geneva, Switzerland


1998–1999

University of Vienna
Wien, Vienna, Austria 
Instituto Técnico y Cultural
Santa Clara de Portugal, Michoacán, Mexico 
University of Southampton
Southampton, England, United Kingdom


1996

University of Bologna
Bolonia, EmiliaRomagna, Italy


1992–1996

INFN  Istituto Nazionale di Fisica Nucleare
Frascati, Latium, Italy
