Thu·Feb 9, 2017Thursday·February 9, 2017

1. 01*

   Can we probe intrinsic CP/T violation and non-unitarity at long baseline accelerator experiments?

   Jogesh Rout🇮🇳 · Mehedi Masud🇮🇳 · Poonam Mehta🇮🇳

   One of the fundamental parameters entering neutrino oscillation framework is the leptonic CP phase ${\delta }_{13}$ and its measurement is an important goal of the planned long baseline experiments. It should be noted that ordinary matter effects complicate the determination of this parameter and there are studies in literature that deal with separation of intrinsic versus extrinsic CP violation. It is important to investigate the consequences of new physics effects that can not only hamper the measurement of ${\delta }_{13}$, but also impact the consequences of discrete symmetries such as CP, T and unitarity in different oscillation channels. In the present work, we explore these discrete symmetries and implications on unitarity in presence of two new physics scenarios (non-standard interaction in propagation and presence of sterile neutrinos) that serve as good examples of going beyond the standard scenario in different directions. We uncover the impact of new physics scenarios on disentangling intrinsic and extrinsic CP violation.

   hep-phhep-exhep-thPRD(2017)·36 citations
2. 02*

   Unified Model of D-Term Inflation

   Valerie Domcke🇫🇷 · Kai Schmitz🇩🇪

   Hybrid inflation, driven by a Fayet-Iliopoulos (FI) D term, is an intriguing inflationary model. In its usual formulation, it however suffers from several shortcomings. These pertain to the origin of the FI mass scale, the stability of scalar fields during inflation, gravitational corrections in supergravity, as well as to the latest constraints from the cosmic microwave background. We demonstrate that these issues can be remedied if D-term inflation is realized in the context of strongly coupled supersymmetric gauge theories. We suppose that the D term is generated in consequence of dynamical supersymmetry breaking. Moreover, we assume canonical kinetic terms in the Jordan frame as well as an approximate shift symmetry along the inflaton direction. This provides us with a unified picture of D-term inflation and high-scale supersymmetry breaking. The D term may be associated with a gauged U(1)_B-L, so that the end of inflation spontaneously breaks B-L in the visible sector.

   hep-phastro-ph.COhep-thPRD(2017)·35 citations
3. 03*

   Large hadronic power corrections or new physics in the rare decay B-->K* mu+ mu- ?

   V.G. Chobanova🇪🇸 · T. Hurth🇩🇪 · F. Mahmoudi🇫🇷 · D. Martinez Santos🇪🇸 · S. Neshatpour🇮🇷

   The well-known problem of the unknown power corrections within QCD improved factorisation leaves the interpretation of the so-called LHCb anomalies in the angular observables of B-->K* mu+ mu- as an open problem. In order to contribute to the question whether they represent a first sign for new physics beyond the Standard Model or a consequence of underestimated hadronic power corrections, we present a direct comparison of two global fits to the data based on the two different assumptions. In addition, we summarise the possible options to resolve this puzzle in the future.

   hep-phJHEP(2017)·88 citations
4. 04*

   Phenomenology of ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ using lattice QCD calculations

   Alakabha Datta🇺🇸 · Saeed Kamali🇺🇸 · Stefan Meinel🇺🇸 · Ahmed Rashed🇺🇸

   In a recent paper we studied the effect of new-physics operators with different Lorentz structures on the semileptonic ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ decay. This decay is of interest in light of the $R(D^{(\ast )})$ puzzle in the semileptonic $\bar{B}\to D^{(\ast )}\tau {\bar{\nu }}_{\tau }$ decays. In this work we add tensor operators to extend our previous results and consider both model-independent new physics (NP) and specific classes of models proposed to address the $R(D^{(\ast )})$ puzzle. We show that a measurement of $R({\Lambda }_c)=\mathcal{B}[{\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }]/\mathcal{B}[{\Lambda }_b\to {\Lambda }_c\ell {\bar{\nu }}_{\ell }]$ can strongly constrain the NP parameters of models discussed for the $R(D^{(\ast )})$ puzzle. We use form factors from lattice QCD to calculate all ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ observables. The ${\Lambda }_b\to {\Lambda }_c$ tensor form factors had not previously been determined in lattice QCD, and we present new lattice results for these form factors here.

   hep-phhep-latJHEP(2017)·128 citations
5. 05*

   The gluon condensation at high energy hadron collisions

   Wei Zhu🇨🇳 · Jiangshan Lan🇨🇳

   We report that the saturation/CGC model of gluon distribution is unstable under action of the chaotic solution in a nonlinear QCD evolution equation, and it evolves to the distribution with a sharp peak at the critical momentum. We find that this gluon condensation is caused by a new kind of shadowing-antishadowing effects, and it leads to a series of unexpected effects in high energy hadron collisions including astrophysical events. For example, the extremely intense fluctuations in the transverse-momentum and rapidity distributions of the gluon jets present the gluon-jet bursts; a sudden increase of the proton-proton cross sections may fill the GZK suppression; the blocking QCD evolution will restrict the maximum available energy of the hadron-hadron colliders.

   hep-phastro-ph.HEcond-mat.otherhep-ex+1NPB(2017)·25 citations
6. 06*

   Constraints on Non-Standard Intermediate Boson Exchange Models from Neutrino-Electron Scattering

   B. Sevda🇹🇷 · A. Şen🇺🇸 · M. Demirci🇹🇷 · M. Deniz🇹🇼 · M. Agartioglu🇹🇼 · A. Ajjaq🇹🇷 · S. Kerman🇹🇷 · L. Singh🇹🇼 · A. Sonay🇹🇷 · H.T. Wong🇹🇼 · M. Zeyrek🇹🇷

   Constraints on couplings of several Beyond Standard Model Physics scenarios, mediated by massive intermediate particles including (1) Extra Z-prime, (2) New Light Spin-1 Boson, and (3) Charged Higgs Boson, are placed via neutrino-electron scattering channel to test Standard Model at low energy-momentum transfer regime. Data on ${\bar{\nu }}_e-e$ and ${\nu }_e-e$ scattering from the TEXONO and LSND Experiments, respectively, are used. Upper bounds to coupling constants of Flavor Conserving and Flavor Violating New Light Spin-1 Boson and Charged Higgs Boson with respect to different mediator masses are determined. The relevant parameter spaces are extended by allowing light mediators. New lower mass limits for extra Z-prime gauge boson models are also placed.

   hep-phhep-exPRD(2017)·15 citations
7. 07*

   Review of LHC Dark Matter Searches

   Felix Kahlhoefer🇩🇪

   This review discusses both experimental and theoretical aspects of searches for dark matter at the LHC. An overview of the various experimental search channels is given, followed by a summary of the different theoretical approaches for predicting dark matter signals. A special emphasis is placed on the interplay between LHC dark matter searches and other kinds of dark matter experiments, as well as among different types of LHC searches.

   hep-phhep-exInt.J.Mod.Phys.A(2017)·369 citations
8. 08*

   Leading twist generalized parton distributions and spin densities in a proton

   Tanmay Maji🇮🇳 · Chandan Mondal🇮🇳 · Dipankar Chakrabarti🇮🇳

   We evaluate both chirally even and odd generalized parton distributions(GPDs) in the leading twist in a recently proposed quark-diquark model for the proton where the light front wavefunctions are constructed from the soft-wall AdS/QCD prediction. The GPDs in transverse impact parameter space give the spin densities for different quark and proton polarizations. For longitudinally polarized proton only chiral even GPDs contribute but for transversely polarized proton both chiral even and chiral odd GPDs contribute to the spin densities. We present a detail study of the spin densities in this model.

   hep-phPRD(2017)·36 citations
9. 09*

   Flashes of Hidden Worlds at Colliders

   David Curtin🇺🇸 · Raman Sundrum🇺🇸

   (This is a general physics level overview article about hidden sectors, and how they motivate searches for long-lived particles. Intended for publication in Physics Today.) Searches for new physics at the Large Hadron Collider have so far come up empty, but we just might not be looking in the right place. Spectacular bursts of particles appearing seemingly out of nowhere could shed light on some of nature's most profound mysteries.

   hep-phastro-ph.COhep-exhep-thPhys.Today(2017)·5 citations
10. 10*

    Holography of the QGP Reynolds Number

    Brett McInnes🇸🇬

    The viscosity of the Quark-Gluon Plasma (QGP) is usually described holographically by the entropy-normalized dynamic viscosity $\eta /s$. However, other measures of viscosity, such as the kinematic viscosity $\nu$ and the Reynolds number $Re$, are often useful, and they too should be investigated from a holographic point of view. We show that a simple model of this kind puts an upper bound on $Re$ for nearly central collisions at a given temperature; this upper bound is in very good agreement with the observational lower bound (from the RHIC facility). Furthermore, in a holographic approach using only Einstein gravity, $\eta /s$ does not respond to variations of other physical parameters, while $\nu$ and $Re$ can do so. In particular, it is known that the magnetic fields arising in peripheral heavy-ion collisions vary strongly with the impact parameter $b$, and we find that the holographic model predicts that $\nu$ and $Re$ can also be expected to vary substantially with the magnetic field and therefore with $b$.

    ↳ hep-thhep-phNPB(2017)·18 citations
11. 11*

    Heavy Flavours in Quark-Gluon Plasma

    Seyong Kim🇰🇷

    Recent progresses in lattice studies of heavy quark and quarkonium at non-zero temperature are discussed. Formulating a tail of spectral functions as a transport coefficient allows lattice determination of momentum diffusion coefficient ($\kappa$) for charm quark in the heavy quark mass limit and lattice determination of heavy quark/heavy anti-quark chemical equilibration rate in NRQCD. Quenched lattice study on a large volume gives $\kappa /T^3=1.8\cdots 3.4$ in the continuum limit. A recent study with $N_f=2+1$ configurations estimates the charmonium chemical equilibration rate ${\Gamma }_{\mathrm{chem}}$. At $T=400$ MeV with $M\sim 1.5$ GeV, ${\Gamma }_{\mathrm{chem}}^{-1}\sim 150$ fm/c. Earlier results from the two studies (with different lattice setups and with different Bayesian priors) which calculate bottomonium correlators using NRQCD and employ Bayesian method to calculate spectral functions are summarized: ${\rm Y}(1S)$ survives upto $T\sim 1.9T_c$ and excited states of ${\rm Y}$ are sequentially suppressed. The spectral functions of ${\chi }_{b1}$ channel shows a Bayesian prior dependence of its thermal behavior: the ${\chi }_{b1}$ spectral function with MEM prior shows melting above $T_c$ but that with a new Bayesian prior hints survival of ${\chi }_{b1}$ upto $\sim 1.6T_c$. Preliminary results from the efforts to understand the difference in the behavior of ${\chi }_{b1}$ spectral function is given.

    ↳ hep-lathep-phnucl-thPoS(2017)·3 citations
12. 12*

    Differential equations on unitarity cut surfaces

    Mao Zeng🇺🇸

    We reformulate differential equations (DEs) for Feynman integrals to avoid doubled propagators in intermediate steps. External momentum derivatives are dressed with loop momentum derivatives to form tangent vectors to unitarity cut surfaces, in a way inspired by unitarity-compatible IBP reduction. For the one-loop box, our method directly produces the final DEs without any integration-by-parts reduction. We further illustrate the method by deriving maximal-cut level differential equations for two-loop nonplanar five-point integrals, whose exact expressions are yet unknown. We speed up the computation using finite field techniques and rational function reconstruction.

    ↳ hep-thhep-phJHEP(2017)·38 citations
13. 13*

    Nuclear matrix element of neutrinoless double-$\beta$ decay: Relativity and short-range correlations

    L. S. Song🇨🇳 · J. M. Yao🇺🇸 · P. Ring🇨🇳 · J. Meng🇨🇳

    Background: The discovery of neutrinoless double-beta ($0\nu \beta \beta$) decay would demonstrate the nature of neutrinos, have profound implications for our understanding of matter-antimatter mystery, and solve the mass hierarchy problem of neutrinos. The calculations for the nuclear matrix elements $M^{0\nu }$ of $0\nu \beta \beta$ decay are crucial for the interpretation of this process. Purpose: We study the effects of relativity and nucleon-nucleon short-range correlations on the nuclear matrix elements $M^{0\nu }$ by assuming the mechanism of exchanging light or heavy neutrinos for the $0\nu \beta \beta$ decay. Methods: The nuclear matrix elements $M^{0\nu }$ are calculated within the framework of covariant density functional theory, where the beyond-mean-field correlations are included in the nuclear wave functions by configuration mixing of both angular-momentum and particle-number projected quadrupole deformed mean-field states. Results: The nuclear matrix elements $M^{0\nu }$ are obtained for ten $0\nu \beta \beta$-decay candidate nuclei. The impact of relativity is illustrated by adopting relativistic or nonrelativistic decay operators. The effects of short-range correlations are evaluated. Conclusions: The effects of relativity and short-range correlations play an important role in the mechanism of exchanging heavy neutrinos though the influences are marginal for light neutrinos. Combining the nuclear matrix elements $M^{0\nu }$ with the observed lower limits on the $0\nu \beta \beta$-decay half-lives, the predicted strongest limits on the effective masses are $|⟨m_{\nu }⟩|<0.06\mathrm{eV}$ for light neutrinos and $|⟨m_{{\nu }_h}^{-1}⟩{|}^{-1}>3.065\times 10^8\mathrm{GeV}$ for heavy neutrinos.

    ↳ nucl-thhep-phnucl-exPRC(2017)·118 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.