Thu·Jun 16, 2016Thursday·June 16, 2016

1. 01*

   An electroweak basis for neutrinoless double $\beta$ decay

   Michael L. Graesser🇺🇸

   A discovery of neutrinoless double-$\beta$ decay would be profound, providing the first direct experimental evidence of $\Delta L=2$ lepton number violating processes. While a natural explanation is provided by an effective Majorana neutrino mass, other new physics interpretations should be carefully evaluated. At low--energies such new physics could manifest itself in the form of color and $SU(2{)}_L\times U(1{)}_Y$ invariant higher dimension operators. Here we determine a complete set of electroweak invariant dimension--9 operators, and our analysis supersedes those that only impose $U(1{)}_{em}$ invariance. Imposing electroweak invariance implies: 1) a significantly reduced set of leading order operators compared to only imposing $U(1{)}_{em}$ invariance; and 2) other collider signatures. Prior to imposing electroweak invariance we find a minimal basis of 24 dimension-9 operators, which is reduced to 11 electroweak invariant operators at leading order in the expansion in the Higgs vacuum expectation value. We set up a systematic analysis of the hadronic realization of the 4-quark operators using chiral perturbation theory, and apply it to determine which of these operators have long-distance pion enhancements at leading order in the chiral expansion. We also find at dimension--11 and dimension--13 the electroweak invariant operators that after electroweak symmetry breaking produce the remaining $\Delta L=2$ operators that would appear at dimension--9 if only $U(1{)}_{em}$ is imposed.

   ↳ hep-phnucl-exnucl-thJHEP(2017)·75 citations
2. 02*

   High sensitivity phonon-mediated kinetic inductance detector with combined amplitude and phase read-out

   F. Bellini🇮🇹 · L. Cardani🇮🇹 · N. Casali🇮🇹 · M.G. Castellano🇮🇹 · I. Colantoni🇮🇹 · C. Cosmelli🇮🇹 · A. Cruciani🇮🇹 · A. D'Addabbo🇮🇹 · S. Di Domizio🇮🇹 · M. Martinez🇮🇹 · C. Tomei🇮🇹 · M. Vignati🇮🇹

   The development of wide-area cryogenic light detectors with good energy resolution is one of the priorities of next generation bolometric experiments searching for rare interactions, as the simultaneous read-out of the light and heat signals enables background suppression through particle identification. Among the proposed technological approaches for the phonon sensor, the naturally-multiplexed Kinetic Inductance Detectors (KIDs) stand out for their excellent intrinsic energy resolution and reproducibility. To satisfy the large surface requirement (several cm${}^2$) KIDs are deposited on an insulating substrate that converts the impinging photons into phonons. A fraction of phonons is absorbed by the KID, producing a signal proportional to the energy of the original photons. The potential of this technique was proved by the CALDER project, that reached a baseline resolution of 154$\pm$7 eV RMS by sampling a 2$\times$2 cm${}^2$ Silicon substrate with 4 Aluminum KIDs. In this paper we present a prototype of Aluminum KID with improved geometry and quality factor. The design improvement, as well as the combined analysis of amplitude and phase signals, allowed to reach a baseline resolution of 82$\pm$4 eV by sampling the same substrate with a single Aluminum KID.

   ↳ physics.ins-detastro-ph.IMnucl-exAppl.Phys.Lett.(2017)·37 citations
3. 03*

   $\bar{K}$ -induced formation of the $f_2(1270)$ and $f_2^{{}^{\prime }}(1525)$ resonances on proton targets

   Yin Huang🇨🇳 · Ju-jun Xie🇨🇳 · Jun He🇨🇳 · Xurong Chen🇨🇳 · Hong-fei Zhang🇨🇳

   We investigate the productiong of $f_2(1270)$ and $f_2^{{}^{\prime }}(1525)$ mesons in the $K^{-}p\to \Lambda f_2(1270)$,$K^{-}p\to \Lambda f_2^{{}^{\prime }}(1525)$ and $K^{-}p\to K^{+}{K}^{-}\Lambda$ reactions within an effective Lagrangian approach. For $K^{-}p\to f_2\Lambda$ reaction, by considering the contributions from the $t$-channel $K^{+}$ exchange and $u$-channel nucleon pole, we get a fairly good description of the experimental measurements about the total and differential cross sections. Based on the studies of the $K^{-}p\to f_2\Lambda$ reaction, we investigate $K^{-}p\to K^{+}{K}^{-}\Lambda$ reaction including the contributions from the $f_2(1270)$ and $f_2^{\prime }(1525)$ mesons decaying into $K^{+}{K}^{-}$ pair. The total cross sections and invariant mass distribution of the $Kp\to K^{+}{K}^{-}\Lambda$ reaction are predicted. The results can be tested in future experiments and therefore offer new clues on the nature of these tensor states.

   ↳ hep-phnucl-exnucl-th2 citations
4. 04*

   Energy versus centrality dependence of the jet quenching parameter $\hat{q}$ at RHIC and LHC: a new puzzle?

   Carlota Andrés🇪🇸 · Néstor Armesto🇪🇸 · Matthew Luzum🇧🇷 · Carlos A. Salgado🇪🇸 · Pía Zurita🇪🇸

   The central goal of jet quenching studies in high-energy nuclear collisions is the characterization of those QCD medium properties that are accessible by these probes. Most of the discussion in the last years has been focused on the determination of the jet quenching parameter, $\hat{q}$. We present here an extraction of this parameter using data of inclusive particle suppression at RHIC and LHC energies for different centralities. Our approach consists of fitting a $K$ factor that quantifies the departure of this parameter from an ideal estimate, $K\equiv \hat{q}/(2{ϵ}^{3/4})$, where $\hat{q}$ is determined by the local medium quantities as provided by hydrodynamical calculations. We find that this $K$ factor is larger at RHIC than at the LHC, as obtained already in previous analyses, but, surprisingly, it is almost independent of the centrality of the collision. Taken at face value, the $K$ factor would not depend on the local properties of the medium as energy density or temperature, but on global collision quantities such as the center of mass energy. This is a very intriguing, unexpected possibility for which we cannot yet provide a clear interpretation. We also comment on the limitations of the formalism that may affect this conclusion.

   ↳ hep-phnucl-exnucl-thEPJC(2016)·105 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.